No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Anion Concentration Gradient-Assisted Construction of a Solid–Electrolyte Interphase for a Stable Zinc Metal Anode at High Rates
Abstract
Coulombic efficiency (CE) and cycle life of metal anodes (lithium, sodium, zinc) are limited by dendritic growth and side reactions in rechargeable metal batteries. Here, we proposed a concept for constructing an anion concentration gradient (ACG)-assisted solid-electrolyte interphase (SEI) for ultrahigh ionic conductivity on metal anodes, in which the SEI layer is fabricated through an in situ chemical reaction of the sulfonic acid polymer and zinc (Zn) metal. Owing to the driving force of the sulfonate concentration gradient and high bulky sulfonate concentration, a promoted Zn2+ ionic conductivity and inhibited anion diffusion in the SEI layer are realized, resulting in a significant suppression of dendrite growth and side reaction. The presence of ACG-SEI on the Zn metal enables stable Zn plating/stripping over 2000 h at a high current density of 20 mA cm-2 and a capacity of 5 mAh cm-2 in Zn/Zn symmetric cells, and moreover an improved cycling stability is also observed in Zn/MnO2 full cells and Zn/AC supercapacitors. The SEI layer containing anion concentration gradients for stable cycling of a metal anode sheds a new light on the fundamental understanding of cation plating/stripping on metal electrodes and technical advances of rechargeable metal batteries with remarkable performance under practical conditions.
... To enhance Zn anode reliability by inhibiting parasitic reactions or guiding uniform Zn deposition, various strategies, including electrode structure design [16][17][18][19], electrode interface modification [20][21][22], and electrolyte optimization [23][24][25][26], have been explored. Among these, the introduction of functional additives stands out as a feasible and effective approach with a substantial scale effect [27][28][29]. ...
Aqueous Zn²⁺-ion batteries (AZIBs), recognized for their high security, reliability, and cost efficiency, have garnered considerable attention. However, the prevalent issues of dendrite growth and parasitic reactions at the Zn electrode interface significantly impede their practical application. In this study, we introduced a ubiquitous biomolecule of phenylalanine (Phe) into the electrolyte as a multifunctional additive to improve the reversibility of the Zn anode. Leveraging its exceptional nucleophilic characteristics, Phe molecules tend to coordinate with Zn²⁺ ions for optimizing the solvation environment. Simultaneously, the distinctive lipophilicity of aromatic amino acids empowers Phe with a higher adsorption energy, enabling the construction of a multifunctional protective interphase. The hydrophobic benzene ring ligands act as cleaners for repelling H2O molecules, while the hydrophilic hydroxyl and carboxyl groups attract Zn²⁺ ions for homogenizing Zn²⁺ flux. Moreover, the preferential reduction of Phe molecules prior to H2O facilitates the in situ formation of an organic–inorganic hybrid solid electrolyte interphase, enhancing the interfacial stability of the Zn anode. Consequently, Zn||Zn cells display improved reversibility, achieving an extended cycle life of 5250 h. Additionally, Zn||LMO full cells exhibit enhanced cyclability of retaining 77.3% capacity after 300 cycles, demonstrating substantial potential in advancing the commercialization of AZIBs.
Supplementary Information
The online version contains supplementary material available at 10.1007/s40820-024-01380-x.
... Investigating innovative technologies for energy conservation and enhanced energy utilization is undergoing vigorous advancement in response to the mounting apprehensions surrounding energy consumption and the imperative of sustainable development. [1][2][3][4] Multifunctional electrochemical devices founded upon electrochemical stimulation of metal ion intercalation and deintercalation exhibit promising prospects in forthcoming energy storage and conversion systems. [5,6] The charging and discharging of batteries are accompanied by an electrochemical redox reaction or the insertion/dissolution of ions. ...
Electrochromic batteries as emerging smart energy devices are highly sought after owing to their real‐time energy monitoring through visual color conversion. However, their large‐scale applicability is hindered by insufficient capacity, inadequate cycling stability, and limited color variation. Herein, a flexible Zn‐ion electrochromic battery (ZIEB) was assembled with sodium vanadate (VONa+) cathode, ion‐redistributing hydrogel electrolyte, and Zn anode to address these challenges. The electrolyte contains anchored −SO3⁻ and ‐NH3⁺, which facilitates ionic transportation and prevents Zn dendrite formation by promoting orientated Zn²⁺ deposition on the Zn (002) surface. The ZIEB exhibits a continuous reversible color transition, ranging from fully charged orange to mid‐charged brown and drained green. It also demonstrates a high specific capacity of 302.4 mAh ⋅ g⁻¹ at 0.05 A ⋅ g⁻¹ with a capacity retention of 96.3 % after 500 cycles at 3 A ⋅ g⁻¹. Additionally, the ZIEB maintains stable energy output even under bending, rolling, knotting, and twisting. This work paves a new strategy for the design of smart energy devices in wearable electronics.
... 82 PZIL-Zn effectively regulates the Zn 2+ and H 2 O relationship by leveraging the strong attraction between amphoteric groups and water molecules, facilitating the desolvation process, and preventing corrosion of the Zn metal anode. Similarly, a uniformly distributed anion concentration gradient solid electrolyte interface sulfonate layer was prepared by an in situ chemical reaction of the sulfonic acid polymer with metal Zn. 83 This interfacial layer, under the electrostatic shielding effect, isolates water molecules and anions in the electrolyte, effectively inhibiting side reactions. In another study, Hao et al. applied a simple spin-coating strategy to deposit polyvinyl butyral (PVB) polymer films as an artificial interfacial layer on the Zn anode surface. ...
Aqueous zinc‐based batteries (AZBs) with the advantages of high safety, low cost, and satisfactory energy density are regarded as one of the most promising candidates for future energy storage systems. Rampant dendrite growth and severe side reactions that occur at the Zn anode hinder its further development. Recently, a growing number of studies have demonstrated that side reactions are closely related to the active water molecules belonging to the Zn ²⁺ solvated structure in the electrolyte, and reducing the occurrence of side reactions by regulating the relationship between the above two has proven to be a reliable pathway. Nevertheless, a systematic summary of the intrinsic mechanisms and practical applications of the route is lacking. This review presents a detailed description of the close connection between H 2 O and side reactions at Zn anodes and gives a comprehensive review of experimental strategies to inhibit side reactions by modulating the relationship between Zn ²⁺ and H 2 O, including anode interface engineering and electrolyte engineering. In addition, further implementation of the above strategies and the modification means for future Zn anodes are discussed.
... In contrast, bare Zn cell experiences a gradual increase in voltage hysteresis, leading to a short circuit after 140 h [ Fig. 3(a)]. To further assess the efficiency of the p-Gr coating in facilitating the reversible plating/ stripping process of Zn, 27 half-cells were assembled by coupling bare Cu or p-Gr@Cu electrodes with the bare Zn electrode to gather the CE information. Notably, the cell equipped with p-Gr@Cu sustains over 700 cycles, maintaining an impressive average CE value of 99.18%. ...
The inadequate cycling stability of Zn anodes, caused by dendritic growth and side reactions, impedes the practical advancement of aqueous Zn metal batteries. Graphene (Gr) has garnered considerable attention in recent years owing to the high degree of lattice constant match to Zn(002). However, the inherent zincophobicity of Gr and its hindrance to Zn2+ transport have necessitated intricate optimization strategies. In this work, we propose a straightforward solution by fabricating a protective layer for Zn anodes using Gr powder (p-Gr), which could effectively modulate Zn deposition behavior. The homogenized interfacial electric field and abundant edges of p-Gr nanosheets facilitate the planar deposition of Zn while concurrently exhibiting excellent capabilities in restricting side reactions. As a result, symmetric cells demonstrate long-lasting lifespan over 2500 h under 5.0 mA cm−2. Furthermore, when paired with a ZnxV2O5 cathode, full cells showcase outstanding capacity retention and cycling stability. Our research imparts valuable insight into the design of high-performance Zn metal anode based on graphene materials.
... Therefore, despite these strategies being developed to inhibit the dendrite growth and side reactions of Zn, high stability, and Zn-ion conductivity have not been well established yet, especially at high current/capacity. Currently, the existing Zn electrodes working at high current density (>10 mA·cm -2 ) and deposition capacity can only be operated at a limited timescale (<1000 h) [24,25]. Therefore, the development of functional SEIs that could well improve the ionic conductivity of the Zn anode surface is crucial to the suppression of dendrite growth and side reactions under the conditions of both a high current density and a high deposition capacity (>4 mAh cm -2 ). ...
Rechargeable zinc (Zn) metal batteries have long been plagued by dendrite growth and parasitic reactions due to the absence of a stable Zn-ion conductive solid-electrolyte interphase (SEI). Although the current strategies assist in suppressing dendritic Zn growth, it is still a challenge to obtain the operation-stability of Zn anode with high Coulombic efficiency (CE) required to implement a sustainable and long-cycling life of Zn metal batteries. In this perspective, we summarize the advantages of the functional gradient interphase (FGI) and try to fundamentally understand the transport behaviors of Zn ions, based on recently an article understanding Zn chemistry. The correlation between the function-orientated design of gradient interphase and key challenges of Zn metal anodes in accelerating Zn²⁺ transport kinetics, improving electrode reversibility, and inhibiting Zn dendrite growth and side reactions was particularly emphasized. Finally, the rational design and innovative directions are provided for the development and application of functional gradient interphase in rechargeable Zn metal battery systems.
Zinc metal anodes are gaining popularity in aqueous electrochemical energy storage systems for their high safety, cost‐effectiveness, and high capacity. However, the service life of zinc metal anodes is severely constrained by critical challenges, including dendrites, water‐induced hydrogen evolution, and passivation. In this study, a protective two‐dimensional metal–organic framework interphase is in situ constructed on the zinc anode surface with a novel gel vapor deposition method. The ultrathin interphase layer (~1 μm) is made of layer‐stacking 2D nanosheets with angstrom‐level pores of around 2.1 Å, which serves as an ion sieve to reject large solvent–ion pairs while homogenizes the transport of partially desolvated zinc ions, contributing to a uniform and highly reversible zinc deposition. With the shielding of the interphase layer, an ultra‐stable zinc plating/stripping is achieved in symmetric cells with cycling over 1000 h at 0.5 mA cm⁻² and ~700 h at 1 mA cm⁻², far exceeding that of the bare zinc anodes (250 and 70 h). Furthermore, as a proof‐of‐concept demonstration, the full cell paired with MnO2 cathode demonstrates improved rate performances and stable cycling (1200 cycles at 1 A g⁻¹). This work provides fresh insights into interphase design to promote the performance of zinc metal anodes.
Electrolytes with anion‐dominated solvation are promising candidates to achieve dendrite‐free and high‐voltage potassium metal batteries. However, it's challenging to form anion‐reinforced solvates at low salt concentrations. Herein, we construct an anion‐reinforced solvation structure at a moderate concentration of 1.5 M with weakly coordinated cosolvent ethylene glycol dibutyl ether. The unique solvation structure accelerates the desolvation of K+, strengthens the oxidative stability to 4.94 V and facilitates the formation of inorganic‐rich and stable electrode‐electrolyte interface. These enable stable plating/stripping of K metal anode over 2200 h, high capacity retention of 83.0% after 150 cycles with a high cut‐off voltage of 4.5 V in K0.67MnO2//K cells, and even 91.5% after 30 cycles under 4.7 V. This work provides insight into weakly coordinated cosolvent and opens new avenues for designing ether‐based high‐voltage electrolytes.
Electrolytes with anion‐dominated solvation are promising candidates to achieve dendrite‐free and high‐voltage potassium metal batteries. However, it's challenging to form anion‐reinforced solvates at low salt concentrations. Herein, we construct an anion‐reinforced solvation structure at a moderate concentration of 1.5 M with weakly coordinated cosolvent ethylene glycol dibutyl ether. The unique solvation structure accelerates the desolvation of K⁺, strengthens the oxidative stability to 4.94 V and facilitates the formation of inorganic‐rich and stable electrode‐electrolyte interface. These enable stable plating/stripping of K metal anode over 2200 h, high capacity retention of 83.0 % after 150 cycles with a high cut‐off voltage of 4.5 V in K0.67MnO2//K cells, and even 91.5 % after 30 cycles under 4.7 V. This work provides insight into weakly coordinated cosolvent and opens new avenues for designing ether‐based high‐voltage electrolytes.
The practical application of aqueous Zn‐ion batteries (AZIBs) is hindered by the crazy Zn dendrites growth and the H2O‐induced side reactions, which rapidly consume the Zn anode and H2O molecules, especially under the lean electrolyte and Zn anode. Herein, a natural disaccharide, d‐trehalose (DT), is exploited as a novel multifunctional co‐solvent to address the above issues. Molecular dynamics simulations and spectral characterizations demonstrate that DT with abundant polar −OH groups can form strong interactions with Zn²⁺ ions and H2O molecules, and thus massively reconstruct the coordination structure of Zn²⁺ ions and the hydrogen bonding network of the electrolyte. Especially, the strong H‐bonds between DT and H2O molecules can not only effectively suppress the H2O activity but also prevent the rearrangement of H2O molecules at low temperature. Consequently, the AZIBs using DT30 electrolyte can show high cycling stability even under lean electrolyte (E/C ratio = 2.95 µL mAh⁻¹), low N/P ratio (3.4), and low temperature (−12 °C). As a proof‐of‐concept, a Zn||LiFePO4 pack with LiFePO4 loading as high as 506.49 mg can be achieved. Therefore, DT as an eco‐friendly multifunctional co‐solvent provides a sustainable and effective strategy for the practical application of AZIBs.
The crystallographic orientation of Zn metal is related to its deposition pattern, plating/stripping reversibility as well as HER and corrosion. Herein, theoretical calculations show (002) crystal plane of Zn metal...
Despite rechargeable aqueous Zn‐ion batteries (AZIBs) exhibit advantages such as high safety, high specific energy, and low cost, etc, the implementation of Zn anodes is still hampered by insufficient cyclability and grievous side reactions. To improve the cycling stability of the zinc anode, a stable zinc anode/electrolyte interface is needed to suppress dendrite formation and side reactions. Herein, a self‐regulating endogenous organic–inorganic hybrid interface layer (EHI) in situ on the surface of the Zn anode by regulating solvent molecules is constructed. The EHI consists of an organic outer layer containing N─H and ─CH3 and an inorganic inner layer containing ZnO and ZnCO3, which effectively inhibits hydrogen evolution and dendrite growth. Consequently, AZIBs with the EHI achieve a lifespan exceeding 5500 h in 3 mA cm⁻², and stripping/plating on copper foils for 600 cycles with an average coulomb efficiency (CE) of 99.47%. This study provides a feasible idea for realizing stable and reversible zinc‐ion batteries.
Aqueous zinc‐ion batteries (ZIBs) are promising large‐scale energy storage devices because of their low cost and high safety. However, owing to the high activity of H 2 O molecules in electrolytes, hydrogen evolution reaction and side reactions usually take place on Zn anodes. Herein, additive‐free PCA−Zn electrolyte with capacity of suppressing the activity of free and solvated H 2 O molecules was designed by selecting the cationophilic and solventophilic anions. In such electrolyte, contact ion‐pairs and solvent‐shared ion‐pairs were achieved even at low concentration, where PCA ⁻ anions coordinate with Zn ²⁺ and bond with solvated H 2 O molecules. Simultaneously, PCA ⁻ anions also induce the construction of H‐bonds between free H 2 O molecules and them. Therefore, the activity of free and solvated H 2 O molecules is effectively restrained. Furthermore, since PCA ⁻ anions possess a strong affinity with metal Zn, they can also adsorb on Zn anode surface to protect Zn anode from the direct contact of H 2 O molecules, inhibiting the occurrence of water‐triggered side reactions. As a result, plating/stripping behavior of Zn anodes is highly reversible and the coulombic efficiency can reach to 99.43 % in PCA−Zn electrolyte. To illustrate the feasibility of PCA−Zn electrolyte, the Zn||PANI full batteries were assembled based on PCA−Zn electrolyte and exhibited enhanced cycling performance.
Aqueous Zn metal batteries are emerging as a promising candidate for the next‐generation largescale energy storage system due to their high safety, low lost, and eco‐friendliness. Nevertheless, their practical application is restricted by the uncontrollable Zn dendrite growth and the limited utilization of the Zn metal anode. Herein, a room temperature electrodeposition strategy based on an optimized rate relationship between the diffusion and consumption of Cu²⁺ to prepare a (111)‐textured Cu current collector for the construction of the dendrite‐free Zn metal anode with high reversibility is developed. Attributed to the high lattice match between the (002) facet of Zn with the (111) facet of Cu, the deposition of Zn along its [001] orientation is achieved on the (111)‐textured Cu. The (002) facets horizontally aligned with the current collector endow Zn with the dendrite‐free planar construction and superior corrosion resistance, resulting in a high reversibility with a long life‐span over 2186 cycles. Impressively, the resultant Zn anodes can stabilize the operation of pouch cells with an extremely demanding negative‐to‐positive capacity ratio of 2. This work provides a new avenue for the development of the current collectors for the low‐cost sustainable energy storage.
Polyethylene glycol (PEG) additives have attracted significant attention as a cost-effective approach for modifying the deposition behavior of Zinc (Zn) anodes. In this study, we investigated the effectiveness of PEG additives in 1 M ZnSO4 aqueous electrolytes, specifically examining the effect of PEG molecular weight on Zn deposition. By exploring the adsorption of PEG polymers with different molecular weights, we identified the PEG with a molecular weight of 300 g mol−1 (PEG300) as the most suitable polymer. In terms of electrochemical performance, Zn anodes exhibited steady cycling for 232 cycles with high reversibility in 1 M ZnSO4 electrolyte with 0.1 wt.% PEG300. By contrast, Zn anodes using the control electrolyte of 1 M ZnSO4 began to fail after only 70 cycles. These findings highlight the potential of PEG300 as a simple and adaptable additive for significantly extending the longevity of Zn metal anodes.
Aqueous zinc‐ion batteries (ZIBs) are promising large‐scale energy storage devices because of their low cost and high safety. However, owing to the high activity of H2O molecules in electrolytes, hydrogen evolution reaction and side reactions usually take place on Zn anodes. Herein, additive‐free PCA−Zn electrolyte with capacity of suppressing the activity of free and solvated H2O molecules was designed by selecting the cationophilic and solventophilic anions. In such electrolyte, contact ion‐pairs and solvent‐shared ion‐pairs were achieved even at low concentration, where PCA⁻ anions coordinate with Zn²⁺ and bond with solvated H2O molecules. Simultaneously, PCA⁻ anions also induce the construction of H‐bonds between free H2O molecules and them. Therefore, the activity of free and solvated H2O molecules is effectively restrained. Furthermore, since PCA⁻ anions possess a strong affinity with metal Zn, they can also adsorb on Zn anode surface to protect Zn anode from the direct contact of H2O molecules, inhibiting the occurrence of water‐triggered side reactions. As a result, plating/stripping behavior of Zn anodes is highly reversible and the coulombic efficiency can reach to 99.43 % in PCA−Zn electrolyte. To illustrate the feasibility of PCA−Zn electrolyte, the Zn||PANI full batteries were assembled based on PCA−Zn electrolyte and exhibited enhanced cycling performance.
Electrochromic batteries as emerging smart energy devices are highly sought after owing to their real‐time energy monitoring through visual color conversion. However, their large‐scale applicability is hindered by insufficient capacity, inadequate cycling stability, and limited color variation. Herein, a flexible Zn‐ion electrochromic battery (ZIEB) was assembled with sodium vanadate (VONa+) cathode, ion‐redistributing hydrogel electrolyte, and Zn anode to address these challenges. The electrolyte contains anchored ‐SO3‐ and ‐NH3+, which facilitates ionic transportation and prevents Zn dendrite formation by promoting orientated Zn2+ deposition on the Zn (002) surface. The ZIEB exhibits a continuous reversible color transition, ranging from fully charged orange to mid‐charged brown and drained green. It also demonstrates a high specific capacity of 302.4 mAh·g‐1 at 0.05 A·g‐1 with a capacity retention of 96.3% after 500 cycles at 3 A·g‐1. Additionally, the ZIEB maintains stable energy output even under bending, rolling, knotting, and twisting. This work paves a new strategy for the design of smart energy devices in wearable electronics.
The unstable zinc anode/electrolyte interface induced by corrosion, interfacial water splitting reaction, and dendrite growth seriously degrades the performances of metal Zn anode in aqueous electrolyte. Herein, the nucleation and growth of zinc hydroxide sulfate (ZHS), an interfacial by-product, has been tailored by Tween 80 in the electrolyte, which thereby assists in in-situ forming a dense solid electrolyte interphase (SEI) with small-sized ZHS and evenly distributed Tween 80. This SEI has high corrosion resistance and uniform distribution of zinc ions, which not only contributes to blocking the interfacial side reactions but also induces stable and calm zinc plating/stripping. Consequently, the modified electrolyte can confer the assembled Zn∥Zn symmetric cell with a stable operation life over 1500 h at 1 mA·cm−2 and 1 mAh·cm−2 as well as the practical Zn∥NH4V4O10 full battery with a high-rate capacity of 120 mAh·g−1 at the current density of 5 A·g−1. This work provides a way for regulating and reusing interfacial by-products, and a new sight on stabilization electrodes/electrolyte interfaces.
The growing environmental pollution issues and continuous energy dilemma call for high‐performance energy storage systems (ESSs). While the inevitable safety concerns appear and restrict the application of lithium‐ion batteries in large‐scale ESSs. Contrastively, zinc ion batteries (ZIBs) attract increasing attention due to the inherent advantages of high safety, low cost, and environmental friendliness. However, the poor stability and reversibility of Zn anodes bring severe difficulty for its practical application. Considerable efforts are devoted in the anode modification, such as electrolyte adjustment, interfacial engineering, and anode structure design, but there is still a fuzzy field concerning the reaction process, regulation mechanism, and modified effect. Reviewing the history, the development of various electrodes greatly depends on the breakthrough in advanced characterization technologies, while the summarizations of technological advances in the Zn anode are still deficient. Hence, this review concentrates on the recent progress in various characterization techniques and related strategies of anode protection. The information is especially highlighted that each technique can offer the crucial or auxiliary role they play in proving specific issues. Furthermore, the opinions on current limitations and future directions of common characterization techniques are also discussed in detail, aiming to give a comprehensive perspective in designing advanced zinc anodes.
The aqueous zinc‐ion battery is promising as grid scale energy storage device, but hindered by the instable electrode/electrolyte interface. Herein, we report the lean‐water ionic liquid electrolyte for aqueous zinc metal batteries. The lean‐water ionic liquid electrolyte creates the hydrophobic tri‐layer interface assembled by first two layers of hydrophobic OTF⁻ and EMIM⁺ and third layer of loosely attached water, beyond the classical Gouy–Chapman–Stern theory based electrochemical double layer. By taking advantage of the hydrophobic tri‐layer interface, the lean‐water ionic liquid electrolyte enables a wide electrochemical working window (2.93 V) with relatively high zinc ion conductivity (17.3 mS/cm). Furthermore, the anion crowding interface facilitates the OTF⁻ decomposition chemistry to create the mechanically graded solid electrolyte interface layer to simultaneously suppress the dendrite formation and maintain the mechanical stability. In this way, the lean‐water based ionic liquid electrolyte realizes the ultralong cyclability of over 10000 cycles at 20 A/g and at practical condition of N/P ratio of 1.5, the cumulated areal capacity reach 1.8 Ah/cm², which outperforms the state‐of‐the‐art zinc metal battery performance. Our work highlights the importance of the stable electrode/electrolyte interface stability, which would be practical for building high energy grid scale zinc‐ion battery.
The aqueous zinc‐ion battery is promising as grid scale energy storage device, but hindered by the instable electrode/electrolyte interface. Herein, we report the lean‐water ionic liquid electrolyte for aqueous zinc metal batteries. The lean‐water ionic liquid electrolyte creates the hydrophobic tri‐layer interface assembled by first two layers of hydrophobic OTF‐ and EMIM+ and third layer of loosely attached water, beyond the classical Gouy–Chapman–Stern theory based electrochemical double layer. By taking advantage of the hydrophobic tri‐layer interface, the lean‐water ionic liquid electrolyte enables a wide electrochemical working window (2.93 V) with relatively high zinc ion conductivity (17.3 mS/cm). Furthermore, the anion crowding interface facilitates the OTF‐ decomposition chemistry to create the mechanically graded solid electrolyte interface layer to simultaneously suppress the dendrite formation and maintain the mechanical stability. In this way, the lean‐water based ionic liquid electrolyte realizes the ultralong cyclability of over 10000 cycles at 20 A/g and at practical condition of N/P ratio of 1.5, the cumulated areal capacity reach 1.8 Ah/cm2, which outperforms the state‐of‐the‐art zinc metal battery performance. Our work highlights the importance of the stable electrode/electrolyte interface stability, which would be practical for building high energy grid scale zinc‐ion battery.
Reversible and dendrite‐free zinc (Zn) circulation is essential for longevous aqueous zinc‐ion batteries (ZIBs) and greatly impacted by the property of Zn interface and electrolyte, especially when confronted with high current density and large area capacity. Herein, a hierarchical Zn interface is constructed by the preferential anion surfactant adsorption and reaction, and assists to reduce the interfacial energy and side reactions for enhanced diffusion kinetics and reversibility during Zn plating/stripping. Thus, highly reversible and smooth Zn anodes are achieved with a long‐term stability of 5500 h at 1 mA cm⁻²/1 mAh cm⁻², an impressive rate up to 40 mA cm⁻² for 10 mAh cm⁻² and a large cumulative plating capacity of 4.45 Ah cm⁻² at 10 mA cm⁻² in Zn symmetric cells. Even under a high depth of discharge of 60% (5.85/7.65 mAh cm⁻²), Zn symmetric batteries can still maintain ca. 800 h's life. The proposed countermeasure has also proved to be valid in prolonging the lifespan and stability of Zn‐MnO2 full batteries at both low and high cycling current densities.
The performance of zinc‐ion batteries is severely hindered by the uncontrolled growth of dendrites and the severe side reactions on the zinc anode interface. To address these challenges, a weak‐water‐coordination electrolyte is realized in a peptone‐ZnSO4‐based electrolyte to simultaneously regulate the solvation structure and the interfacial environment. The peptone molecules have stronger interaction with Zn²⁺ ions than with water molecules, making them more prone to coordinate with Zn²⁺ ions and then reducing the active water in the solvated sheath. Meantime, the peptone molecules selectively adsorb on the Zn metal surface, and then are reduced to form a stable solid‐electrolyte interface layer that can facilitate uniform and dense Zn deposition to inhabit the dendritic growth. Consequently, the Zn||Zn symmetric cell can exhibit exceptional cycling performance over 3200 h at 1.0 mA cm⁻²/1.0 mAh cm⁻² in the peptone‐ZnSO4‐based electrolyte. Moreover, when coupled with a Na2V6O16·3H2O cathode, the cell exhibits a long lifespan of 3000 cycles and maintains a high capacity retention rate of 84.3% at 5.0 A g⁻¹. This study presents an effective approach for enabling simultaneous regulation of the solvation structure and interfacial environment to design a highly reversible Zn anode.
The quasi‐solid electrolytes (QSEs) have attracted extensive attentions due to their improved ion transport properties and high stability, which is synergistically based on tunable functional groups and confined solvent molecules among polymetric networks. However, the trade‐off effect between the polymer content and ionic conductivity exists in QSEs, limiting their rate performance. In this work, the epitaxial polymerization strategy is used to build the gradient hydrogel networks (GHNs) covalently fixed on zinc anode. Then we reveal that the asymmetric distribution of negative charges benefits GHNs with fast and selective ionic transport properties, realizing a higher Zn ²⁺ transference number of 0.65 than the homogeneous networks (0.52) at same polymer content. Meanwhile, the high‐density networks formed at GHNs/Zn interface can efficiently immobilize free water and homogenize the Zn ²⁺ flux, greatly inhibiting the water‐involved parasitic reactions and dendrites growth. Thus, the GHNs enable dendrite‐free stripping/plating over 1000 h at 8 mA cm ⁻² and 1 mAh cm ⁻² in Zn||Zn symmetric cell, as well as the evidently prolonged cycles in various full cells. This work will shed light on asymmetric engineering of ion transport channels in advanced quasi‐solid battery systems to achieve high energy and safety.
This article is protected by copyright. All rights reserved
The cycling instability of metallic Zn anodes hinders the practicability of aqueous Zn‐ion batteries, though aqueous Zn‐ion batteries may be the most credible alternative technology for future electrochemical energy storage applications. Commercially available trivalent chromium conversion films (TCCF) were successfully employed as robust artificial interphases on Zn metal anodes (ZMAs). Fabricated through a simple immersion method, the TCCF‐protected Zn (TCCF@Zn) electrode enables a super‐low nucleation overpotential for Zn plating of 6.9 mV under 1 mA cm ⁻² , outstanding Coulombic efficiency of 99.7% at 3 mA cm ⁻² for 1600 cycles in Zn||Cu asymmetric cells and superior cyclability in symmetric Zn||Zn batteries at 0.2, 2 and 5 mA cm ⁻² for 2500 h and 10 mA cm ⁻² for 1200 h. More importantly, the TCCF@Zn||V 2 O 5 full cell exhibited a specific capacity of 118.5 mAh g ⁻¹ with a retention of 53.4% at 3 A g ⁻¹ for 3000 cycles, which is considerably larger than that of the pristine Zn||V 2 O 5 full cell (59.7 mAh g ⁻¹ with a retention of 25.7%). This study demonstrates a highly efficient and low‐cost surface modification strategy derived from an industrially applicable trivalent chromium passivation technique aimed at obtaining dendrite‐free ZMAs with high reversibility for practical Zn batteries in the near future.
This article is protected by copyright. All rights reserved
The poor reversibility and stability of Zn metal anode (ZMA) caused by uncontrolled Zn deposition behaviors and serious side reactions severely impeded the practical application of aqueous Zn metal battery. Herein, a liquid‐dynamic and self‐adaptive protective layer (LSPL) was constructed on the ZMA surface for inhibiting dendrites and by‐products formation. Interestingly, the outer LSPL consists of liquid perfluoropolyether (PFPE), which can dynamically adapt volume change during repeat cycling and inhibit side reactions. Moreover, it can also decrease the de‐solvation energy barrier of Zn²⁺ by strong interaction between C–F bond and foreign Zn²⁺, improving Zn²⁺ transport kinetics. For the LSPL inner region, in‐situ formed ZnF2 through the spontaneous chemical reaction between metallic Zn and part PFPE can establish an unimpeded Zn²⁺ migration pathway for accelerating ion transfer, thereby restricting Zn dendrites formation. Consequently, the LSPL‐modified ZMA enables reversible Zn deposition/dissolution up to 2000 h at 1 mA cm⁻² and high coulombic efficiency of 99.8% at 4 mA cm⁻². Meanwhile, LSPL@Zn||NH4V4O10 full cells deliver an ultralong cycling lifespan of 100 00 cycles with 0.0056% per cycle decay rate at 10 A g⁻¹. This self‐adaptive layer provides a new strategy to improve the interface stability for next‐generation aqueous Zn battery.
Inorganic all‐solid‐state sodium batteries (IASSSBs) are emerged as promising candidates to replace commercial lithium‐ion batteries in large‐scale energy storage systems due to their potential advantages, such as abundant raw materials, robust safety, low price, high‐energy density, favorable reliability and stability. Inorganic sodium solid electrolytes (ISSEs) are an indispensable component of IASSSBs, gaining significant attention. Herein, this review begins by discussing the fundamentals of ISSEs, including their ionic conductivity, mechanical property, chemical and electrochemical stabilities. It then presents the crystal structures of advanced ISSEs (e.g., β/β′′ ‐alumina, NASICON, sulfides, complex hydride and halide electrolytes) and the related issues, along with corresponding modification strategies. The review also outlines effective approaches for forming intimate interfaces between ISSEs and working electrodes. Finally, current challenges and critical perspectives for the potential developments and possible directions to improve interfacial contacts for future practical applications of ISSEs are highlighted. This comprehensive review aims to advance the understanding and development of next‐generation rechargeable IASSSBs.
This article is protected by copyright. All rights reserved
Aqueous zinc‐ion batteries (AZIBs) offer promising prospects for large‐scale energy storage due to their inherent abundance and safety features. However, the growth of zinc dendrites remains a primary obstacle to the practical industrialization of AZIBs, especially under harsh conditions of high current densities and elevated temperatures. To address this issue, we developed a Janus separator with an exceptionally ultrathin thickness of 29 μm. This Janus separator features the bacterial cellulose (BC) layer on one side and Ag nanowires/bacterial cellulose (AgNWs/BC) layer on the other side. The high zincophilic property and excellent electric/thermal conductivity of AgNWs make them ideal for serving as an ion pump to accelerate Zn2+ transport in the electrolyte, resulting in the greatly improved Zn2+ conductivity, the deposition of homogeneous Zn nuclei, and dendrite‐free Zn. Consequently, the Zn||Zn symmetrical cells with the Janus separator exhibit a stable cycle life of over 1000 hours under 80 mA cm−2 and sustain over 600 hours at 10 mA cm−2 under 50°C. Furthermore, the Janus separator enables excellent cycling stability in AZIBs, aqueous zinc‐ion capacitors (AZICs), and scaled‐up flexible soft‐packaged batteries. Our study demonstrates the potential of functional separators in promoting the application of aqueous zinc batteries, particularly under harsh conditions.
This article is protected by copyright. All rights reserved
The artificial solid electrolyte interphase (SEI) plays a pivotal role in Zn anode stabilization but its long‐term effectiveness at high rates is still challenged. Herein, to achieve superior long‐life and high‐rate Zn anode, an exquisite electrolyte additive, lithium bis(oxalate)borate (LiBOB), is proposed to in‐situ derive a highly Zn2+‐conductive SEI and to dynamically patrol its cycling‐initiated defects. Profiting from the as‐constructed real‐time, automatic SEI repairing mechanism, the Zn anode can be cycled with distinct reversibility over 1800 h at an ultrahigh current density of 50 mA cm‐2, presenting a record‐high cumulative capacity up to 45 Ah cm−2. The superiority of the formulated electrolyte is further demonstrated in the Zn||MnO2 and Zn||NaV3O8 full batteries, even when tested under harsh conditions (limited Zn supply (N/P≈3), 2500 cycles). This work brings inspiration for developing fast‐charging Zn batteries toward grid‐scale storage of renewable energy sources.
Aprotic lithium-oxygen (Li-O2) batteries have attracted extensive attention due to their ultrahigh theoretical energy density. However, slow and undesired electron transfer during cathodic reactions causes low cyclic stability in these batteries. Here, we demonstrate that O2 mass transport and electron transfer for cathodic reactions in Li-O2 batteries could be decoupled by a double-cathode structure that efficiently enables stable electron transfer between the cathode and Li2O2/O2. This resolves various side reactions and slow Li2O2 reaction kinetics issues in conventional Li-O2 batteries, leading to stable operation of the cell for nearly 2 months at a capacity of 0.2 and 5 mAh cm⁻², with more than 4- and 10-fold increases in cycle life when compared with single-cathode batteries. These remarkable improvements in the cyclic stability of Li-O2 batteries with double cathodes provide an interesting concept for improving the operational stability of other metal-rechargeable batteries with conversion-type chemistry.
Lithium metal batteries are considered a promising candidate for high‐energy‐density energy storage. However, the strong reducibility and high reactivity of lithium lead to low Coulombic efficiency when contacting oxidants, such as lithium polysulfide caused by the serious “shuttle effect” in lithium–sulfur batteries. Herein we design selectively permeable lithium‐ion channels on lithium metal surface, which allow lithium ions to pass through by electrochemical overpotential, while the polysulfides are effectively blocked due to the much larger steric hindrance than lithium ions. The selective permeation of lithium ions through the channels is further elucidated by the molecular simulation and visualization experiment. Consequently, a prolonged cycle life of 75 cycles and high Coulombic efficiency of 99 % are achieved in a practical Li–S pouch cell with limited amounts of lithium and electrolyte, confirming the unique role the selective ion permeation plays in protecting highly reactive alkali metal anodes in working batteries.
Metallic zinc is an ideal anode due to its high theoretical capacity (820 mAh g−1), low redox potential (−0.762 V versus the standard hydrogen electrode), high abundance and low toxicity. When used in aqueous electrolyte, it also brings intrinsic safety, but suffers from severe irreversibility. This is best exemplified by low coulombic efficiency, dendrite growth and water consumption. This is thought to be due to severe hydrogen evolution during zinc plating and stripping, hitherto making the in-situ formation of a solid–electrolyte interphase (SEI) impossible. Here, we report an aqueous zinc battery in which a dilute and acidic aqueous electrolyte with an alkylammonium salt additive assists the formation of a robust, Zn2+-conducting and waterproof SEI. The presence of this SEI enables excellent performance: dendrite-free zinc plating/stripping at 99.9% coulombic efficiency in a Ti||Zn asymmetric cell for 1,000 cycles; steady charge–discharge in a Zn||Zn symmetric cell for 6,000 cycles (6,000 h); and high energy densities (136 Wh kg−1 in a Zn||VOPO4 full battery with 88.7% retention for >6,000 cycles, 325 Wh kg−1 in a Zn||O2 full battery for >300 cycles and 218 Wh kg−1 in a Zn||MnO2 full battery with 88.5% retention for 1,000 cycles) using limited zinc. The SEI-forming electrolyte also allows the reversible operation of an anode-free pouch cell of Ti||ZnxVOPO4 at 100% depth of discharge for 100 cycles, thus establishing aqueous zinc batteries as viable cell systems for practical applications. A solid–electrolyte interphase that is permeable to Zn(ii) ions but waterproof is formed using an aqueous electrolyte composition. Cycling performances in an anode-free aqueous pouch cell show promise for intrinsically safe energy storage applications.
Aqueous zinc (Zn) metal batteries (ZMBs) are considered a promising candidate for grid‐scale energy storage due to their freedom from fire hazards. However, a limited reversibility of Zn metal electrode caused by dendritic Zn growth has hindered the advent of high‐capacity Zn metal batteries (>4 mAh cm⁻²). Herein, it is reported that fast electrokinetic Zn‐ion transport extremely improves the Zn metal reversibility. It is revealed that a negatively charged porous layer (NPL) provides the electrokinetic Zn‐ion transport by surface conduction, and consequently impedes the depletion of Zn‐ion on electrode surface as indicated by numerical simulations and overlimiting current behavior. Due to the quick Zn‐ion delivery, a dendrite‐free and densely packed Zn metal deposit is accommodated inside its pores. With the introduction of the NPL, the cycling stability of Zn symmetric cell is enhanced by 21 times at 10 mA cm⁻²/10 mAh cm⁻². Average Coulombic efficiency of 99.6% is achieved over 500 cycles for electrodeposition/stripping at 30 mA cm⁻²/5 mAh cm⁻² on NPL–Cu electrode. Furthermore, a high‐capacity Zn/V2O5 full cell with the NPL exhibits an extraordinary stability over 1000 cycles at a capacity of 4.8 mAh cm⁻².
Solid-state lithium (Li)–air batteries are recognized as a next-generation solution for energy storage to address the safety and electrochemical stability issues that are encountered in liquid battery systems1–4. However, conventional solid electrolytes are unsuitable for use in solid-state Li–air systems owing to their instability towards lithium metal and/or air, as well as the difficulty in constructing low-resistance interfaces⁵. Here we present an integrated solid-state Li–air battery that contains an ultrathin, high-ion-conductive lithium-ion-exchanged zeolite X (LiX) membrane as the sole solid electrolyte. This electrolyte is integrated with cast lithium as the anode and carbon nanotubes as the cathode using an in situ assembly strategy. Owing to the intrinsic chemical stability of the zeolite, degeneration of the electrolyte from the effects of lithium or air is effectively suppressed. The battery has a capacity of 12,020 milliamp hours per gram of carbon nanotubes, and has a cycle life of 149 cycles at a current density of 500 milliamps per gram and at a capacity of 1,000 milliamp hours per gram. This cycle life is greater than those of batteries based on lithium aluminium germanium phosphate (12 cycles) and organic electrolytes (102 cycles) under the same conditions. The electrochemical performance, flexibility and stability of zeolite-based Li–air batteries confer practical applicability that could extend to other energy-storage systems, such as Li–ion, Na–air and Na–ion batteries.
Discovering the underlying reason for Li anode failure is a critical step towards applications of lithium metal batteries (LMBs). In this work, we conduct deuterium‐oxide (D2O) titration experiments in a novel on‐line gas analysis mass spectrometry (MS) system, to determine the content of metallic Li and lithium hydride (LiH) in cycled Li anodes disassembled from practical LiCoO2/Li LMBs. The practical cell is comprised of ultrathin Li anode (50 μm), high loading LiCoO2 (17 mg cm⁻², 2.805 mAh cm⁻²) and different formulated electrolytes. Our results suggest that the amount of LiH accumulation is negatively correlated with cyclability of practical LMBs. More importantly, we reveal a temperature sensitive equilibrium (Li + 1/2 H2 ⇌ LiH) governing formation and decomposition process of LiH at Li anode. We believe that the unusual understanding provided by this study will draw forth more insightful efforts to realize efficient Li protection and the ultimate applications of “holy grail” LMBs.
Lithium (Li) metal is one of the most promising alternative anode materials of next‐generation high‐energy‐density batteries demanded for advanced energy storage in the coming fourth industrial revolution. Nevertheless, disordered Li deposition easily causes short lifespan and safety concerns and thus severely hinders the practical applications of Li metal batteries. Tremendous efforts are devoted to understanding the mechanism for Li deposition, while the final deposition morphology tightly relies on the Li nucleation and early growth. Here, the recent progress in insightful and influential models proposed to understand the process of Li deposition from nucleation to early growth, including the heterogeneous model, surface diffusion model, crystallography model, space charge model, and Li‐SEI model, are highlighted. Inspired by the abovementioned understanding on Li nucleation and early growth, diverse anode‐design strategies, which contribute to better batteries with superior electrochemical performance and dendrite‐free deposition behavior, are also summarized. This work broadens the horizon for practical Li metal batteries and also sheds light on more understanding of other important metal‐based batteries involving the metal deposition process. Lithium (Li) nucleation and early growth processes significantly determine the final deposition behavior. The recent progress in influential models proposed to understand the process of Li nucleation and early growth is highlighted. Inspired by the abovementioned understanding, diverse anode‐design strategies, which contribute to better batteries with superior electrochemical performance and dendrite‐free deposition behavior, are also summarized.
Zinc-ion batteries (ZIBs) are promising alternative energy storage devices to lithium-ion batteries owing to the merits of large abundance, high theoretical capacity, and environmental friendliness. However, critical challenges including low working voltage (below 2 V), low energy density as well as dendrites formation during long cycling caused by aqueous ZIB systems still hinder their practical applications. Herein, a high-voltage Zn-graphite battery (ZGB) based on a non-zinc ion single-salt electrolyte (2.5 M LiPF6 in carbonate solvent) is developed. Moreover, we surprisingly found that Zn²⁺ is dissolved in the LiPF6 single-salt electrolyte during resting and discharging processes, thus enabling reversible Zn plating/stripping mechanism on the Zn foil anode in the ZGB over the voltage window of 1.0–3.1 V. As a result, the ZGB achieves long-term cycling performance with capacity retention of ∼100% for over 1200 cycles at 3 C and high Coulombic efficiency of ∼ 100% in 1.0–3.1 V with no dendrites formation. Moreover, the ZGB exhibits high working voltage of up to 2.2 V, thus contributing to both high energy density (up to 210 Wh kg⁻¹) and high power density (up to 1013 W kg⁻¹), superior than most reported ZIBs.
The application of lithium metal as an anode material for next generation high energy‐density batteries has to overcome the major bottleneck that is the seemingly unavoidable growth of Li dendrites caused by non‐uniform electrodeposition on the electrode surface. This problem must be addressed by clarifying the detailed mechanism. In this work the mass‐transfer of Li‐ions is investigated, a key process controlling the electrochemical reaction. By a phase field modeling approach, the Li‐ion concentration and the electric fields are visualized to reveal the role of three key experimental parameters, operating temperature, Li‐salt concentration in electrolyte, and applied current density, on the microstructure of deposited Li. It is shown that a rapid depletion of Li‐ions on electrode surface, induced by, e.g., low operating temperature, diluted electrolyte and a high applied current density, is the underlying driving force for non‐uniform electrodeposition of Li. Thus, a viable route to realize a dendrite‐free Li plating process would be to mitigate the depletion of Li‐ions on the electrode surface. The methodology and results in this work may boost the practical applicability of Li anodes in Li metal batteries and other battery systems using metal anodes.
Electrolyte engineering is critical for developing Li metal batteries. While recent works improved Li metal cyclability, a methodology for rational electrolyte design remains lacking. Herein, we propose a design strategy for electrolytes that enable anode-free Li metal batteries with single-solvent single-salt formations at standard concentrations. Rational incorporation of –CF2– units yields fluorinated 1,4-dimethoxylbutane as the electrolyte solvent. Paired with 1 M lithium bis(fluorosulfonyl)imide, this electrolyte possesses unique Li–F binding and high anion/solvent ratio in the solvation sheath, leading to excellent compatibility with both Li metal anodes (Coulombic efficiency ~ 99.52% and fast activation within five cycles) and high-voltage cathodes (~6 V stability). Fifty-μm-thick Li|NMC batteries retain 90% capacity after 420 cycles with an average Coulombic efficiency of 99.98%. Industrial anode-free pouch cells achieve ~325 Wh kg⁻¹ single-cell energy density and 80% capacity retention after 100 cycles. Our design concept for electrolytes provides a promising path to high-energy, long-cycling Li metal batteries.
Aqueous zinc (Zn) batteries (AZBs) are widely considered as a promising candidate for next‐generation energy storage owing to their excellent safety features. However, the application of a Zn anode is hindered by severe dendrite formation and side reactions. Herein, an interfacial bridged organic–inorganic hybrid protection layer (Nafion‐Zn‐X) is developed by complexing inorganic Zn‐X zeolite nanoparticles with Nafion, which shifts ion transport from channel transport in Nafion to a hopping mechanism in the organic–inorganic interface. This unique organic–inorganic structure is found to effectively suppress dendrite growth and side reactions of the Zn anode. Consequently, the Zn@Nafion‐Zn‐X composite anode delivers high coulombic efficiency (ca. 97 %), deep Zn plating/stripping (10 mAh cm⁻²), and long cycle life (over 10 000 cycles). By tackling the intrinsic chemical/electrochemical issues, the proposed strategy provides a versatile remedy for the limited cycle life of the Zn anode.
The membrane-based reverse electrodialysis (RED) technique has a fundamental role in harvesting clean and sustainable osmotic energy existing in the salinity gradient. However, the current designs of membranes cannot cope with the high output power density and robustness. Here, we construct a sulfonated poly (ether ether ketone) (SPEEK) nanochannel membrane with numerous nanochannels for a membrane-based osmotic power generator. The parallel nanochannels with high space charges show excellent cation-selectivity, which could further be improved by adjusting the length and charge density of nanochannels. Based on numerical simulation, the system with space charge shows better conductivity and selectivity than those of a surface-charged nanochannel. The output power density of our proposed membrane-based device reaches up to 5.8 W/m2 by mixing artificial seawater and river water. Additionally, the SPEEK membranes exhibit good mechanical properties, endowing the possibility of creating a high-endurance scale-up membrane-based generator system. We believe that this work provides useful insights into material design and fluid transport for the power generator in osmotic energy conversion.
Rechargeable aqueous zinc batteries (RAZB) have been re‐evaluated because of the superiority in addressing safety and cost concerns. Nonetheless, the limited lifespan arising from dendritic electrodeposition of metallic Zn hinders their further development. Herein, a metal–organic framework (MOF) was constructed as front surface layer to maintain a super‐saturated electrolyte layer on the Zn anode. Raman spectroscopy indicated that the highly coordinated ion complexes migrating through the MOF channels were different from the solvation structure in bulk electrolyte. Benefiting from the unique super‐saturated front surface, symmetric Zn cells survived up to 3000 hours at 0.5 mA cm⁻², near 55‐times that of bare Zn anodes. Moreover, aqueous MnO2–Zn batteries delivered a reversible capacity of 180.3 mAh g⁻¹ and maintained a high capacity retention of 88.9 % after 600 cycles with MnO2 mass loading up to 4.2 mg cm⁻².
A proof‐of‐concept study on a liquid/liquid (L/L) two‐phase electrolyte interface is reported by using the polarity difference of solvent for the protection of Li‐metal anode with long‐term operation over 2000 h. The L/L electrolyte interface constructed by non‐polar fluorosilicane (PFTOS) and conventionally polar dimethyl sulfoxide solvents can block direct contact between conventional electrolyte and Li anode, and consequently their side reactions can be significantly eliminated. Moreover, the homogeneous Li‐ion flow and Li‐mass deposition can be realized by the formation of a thin and uniform solid‐electrolyte interphase (SEI) composed of LiF, LixC, LixSiOy between PFTOS and Li anode, as well as the super‐wettability state of PFTOS to Li anode, resulting in the suppression of Li dendrite formation. The cycling stability in a lithium–oxygen battery as a model is improved 4 times with the L/L electrolyte interface.
Electroplating has been studied for centuries, not only in the laboratory but also in industry for machinery, electronics, automobile, aviation, and other fields. The lithium‐metal anode is the Holy Grail electrode because of its high energy density. But the recyclability of lithium‐metal batteries remains quite challenging. The essence of both conventional electroplating and lithium plating is the same, reduction of metal cations. Thus, industrial electroplating knowledge can be applied to revisit the electroplating process for lithium‐metal anodes. In conventional electroplating, some strategies like using additives, modifying substrates, applying pulse current, and agitating electrolyte have been explored to suppress dendrite growth. These methods are also effective in lithium‐metal anodes. Inspired by that, we revisit the fundamental electroplating theory for lithium‐metal anodes in this Minireview, mainly drawing attention to the theory of electroplating thermodynamics and kinetics. Analysis of essential differences between traditional electroplating and plating/stripping of lithium‐metal anodes is also presented. Thus, industrial electroplating knowledge can be applied to the electroplating process of lithium‐metal anodes to improve commercial lithium‐metal batteries and the study of lithium plating/stripping can further enrich the classical electroplating technique.
Although lithium metal is the best anode for lithium‐based batteries, the uncontrollable lithium dendrites especially under deep stripping and plating states hamper its practical applications. Here, a dendrite‐free lithium anode is developed based on vertically oriented lithium–copper–lithium arrays, which can be facilely produced via traditional rolling or repeated stacking approaches. Such vertically oriented arrays not only enable both the lithium‐ion flux and the electric field to be regulated, but also can act as a “dam” to guide the regular plating of lithium, thus efficiently buffering the volume change of the lithium anode upon cycling. As a consequence, the vertically oriented anode exhibits an excellent deep stripping and plating capability upto 50 mAh cm−2, high rate capabilities (20 mA cm−2), and long cycle life (2000 h). Based on this anode, a full lithium battery with a LiCoO2 cathode delivers a good cycle life, holding great potential for practical lithium‐metal batteries with high energy densities. Vertically oriented lithium–copper–lithium arrays are facilely produced to efficiently inhibit the growth of dendrites especially under deep stripping and plating states, since such unique geometry enables both the lithium‐ion flux and the electron field to be regulated, guiding the regular stripping and plating of lithium. This provides a potential for practical applications for lithium‐based batteries with high energy densities.
The use of ‘water-in-salt’ electrolytes has considerably expanded the electrochemical window of aqueous lithium-ion batteries to 3 to 4 volts, making it possible to couple high-voltage cathodes with low-potential graphite anodes1–4. However, the limited lithium intercalation capacities (less than 200 milliampere-hours per gram) of typical transition-metal-oxide cathodes5,6 preclude higher energy densities. Partial7,8 or exclusive⁹ anionic redox reactions may achieve higher capacity, but at the expense of reversibility. Here we report a halogen conversion–intercalation chemistry in graphite that produces composite electrodes with a capacity of 243 milliampere-hours per gram (for the total weight of the electrode) at an average potential of 4.2 volts versus Li/Li⁺. Experimental characterization and modelling attribute this high specific capacity to a densely packed stage-I graphite intercalation compound, C3.5[Br0.5Cl0.5], which can form reversibly in water-in-bisalt electrolyte. By coupling this cathode with a passivated graphite anode, we create a 4-volt-class aqueous Li-ion full cell with an energy density of 460 watt-hours per kilogram of total composite electrode and about 100 per cent Coulombic efficiency. This anion conversion–intercalation mechanism combines the high energy densities of the conversion reactions, the excellent reversibility of the intercalation mechanism and the improved safety of aqueous batteries.
Rechargeable aprotic alkali metal (Li or Na)–O2 batteries are the subject of great interest because of their high theoretical specific energy. However, the growth of dendrites and cracks at the Li or Na anode, as well as their corrosive oxidation lead to poor cycling stability and safety issues. Understanding the mechanism and improving Li/Na-ion plating and stripping electrochemistry are therefore essential to realizing their technological potential. Here, we report how the use of a Li-Na alloy anode and an electrolyte additive realizes an aprotic bimetal Li-Na alloy–O2 battery with improved cycling stability. Electrochemical investigations show that stripping and plating of Li and Na and the robust and flexible passivation film formed in situ (by 1,3-dioxolane additive reacting with the Li-Na alloy) suppress dendrite and buffer alloy anode volume expansion and thus prevent cracking, avoiding electrolyte consumption and ensuring high electron transport efficiency and continued electrochemical reactions. © 2018, The Author(s), under exclusive licence to Springer Nature Limited.
The cycle life and energy density of rechargeable metal batteries are largely limited by the dendritic growth of their metal anodes (lithium, sodium or zinc). Here we develop a three-dimensional cross-linked polyethylenimine lithium-ion-affinity sponge as the lithium metal anode host to mitigate the problem. We show that electrokinetic surface conduction and electro-osmosis within the high-zeta-potential sponge change the concentration and current density profiles, which enables dendrite-free plating/stripping of lithium with a high Coulombic efficiency at high deposition capacities and current densities, even at low temperatures. The use of a lithium-hosting sponge leads to a significantly improved cycling stability of lithium metal batteries with a limited amount of lithium (for example, the areal lithium ratio of negative to positive electrodes is 0.6) at a commercial-level areal capacity. We also observed dendrite-free morphology in sodium and zinc anodes, which indicates a broader promise of this approach. © 2018, The Author(s), under exclusive licence to Springer Nature Limited.
Alkaline zinc-based flow batteries are regarded to be among the best choices for electric energy storage. Nevertheless, application is challenged by the issue of zinc dendrite/accumulation. Here, we report a negatively charged nanoporous membrane for a dendrite-free alkaline zinc-based flow battery with long cycle life. Free of zinc dendrite/accumulation, stable performance is afforded for ∼240 cycles at current densities ranging from 80 to 160 mA cm-2 using the negatively charged nanoporous membrane. Furthermore, 8 h and 7 h plating/stripping processes at 40 mA cm-2 yield an average energy efficiency of 91.92% and an areal discharge capacity above 130 mAh cm-2. A peak power density of 1056 mW cm-2 is achieved at 1040 mA cm-2. This study may provide an effective way to address the issue of zinc dendrite/accumulation for zinc-based batteries and accelerate the advancement of these batteries.
Metallic zinc (Zn) has been regarded as an ideal anode material for aqueous batteries because of its high theoretical capacity (820 mA h g-1), low potential (-0.762 V versus the standard hydrogen electrode), high abundance, low toxicity and intrinsic safety. However, aqueous Zn chemistry persistently suffers from irreversibility issues, as exemplified by its low coulombic efficiency (CE) and dendrite growth during plating/ stripping, and sustained water consumption. In this work, we demonstrate that an aqueous electrolyte based on Zn and lithium salts at high concentrations is a very effective way to address these issues. This unique electrolyte not only enables dendrite-free Zn plating/stripping at nearly 100% CE, but also retains water in the open atmosphere, which makes hermetic cell configurations optional. These merits bring unprecedented flexibility and reversibility to Zn batteries using either LiMn2O4 or O2 cathodes-the former deliver 180 W h kg-1 while retaining 80% capacity for >4,000 cycles, and the latter deliver 300 W h kg-1 (1,000 W h kg-1 based on the cathode) for >200 cycles.
Lithium–sulfur batteries are a promising energy-storage technology due to their relatively low cost and high theoretical energy density. However, one of their major technical problems is the shuttling of soluble polysulfides between electrodes, resulting in rapid capacity fading. Here, we present a metal–organic framework (MOF)-based battery separator to mitigate the shuttling problem. We show that the MOF-based separator acts as an ionic sieve in lithium–sulfur batteries, which selectively sieves Li+ ions while efficiently suppressing undesired polysulfides migrating to the anode side. When a sulfur-containing mesoporous carbon material (approximately 70 wt% sulfur content) is used as a cathode composite without elaborate synthesis or surface modification, a lithium–sulfur battery with a MOF-based separator exhibits a low capacity decay rate (0.019% per cycle over 1,500 cycles). Moreover, there is almost no capacity fading after the initial 100 cycles. Our approach demonstrates the potential for MOF-based materials as separators for energy-storage applications.
Researchers must find a sustainable way of providing the power our modern lifestyles demand.
Efficient, rechargeable Mg and Ca batteries
Divalent rechargeable metal batteries such as those based on magnesium and calcium are of interest because of the abundance of these elements and their lower tendency to form dendrites, but practical demonstrations are lacking. Hou et al . used methoxyethyl amine chelants in which the ligands attach to the metal atom in more than one place, modulating the solvation structure of the metal ions to enable a facile charge-transfer reaction (see the Perspective by Zuo and Yin). In full battery cells, these components lead to high efficiency and energy density. Theoretical calculations were used to understand the solvation structures. —MSL
Thanks to a stable fluorinated interphase formed on top of a Zn metal anode, a Zn metal battery shows 99.9% Coulombic efficiency and record-high Zn utilization.
In situconstruction of a multifunctional solid electrolyte interphase (SEI) for Zn anodes is promising to address the dendrite growth and side reactions (corrosion and hydrogen evolution) in aqueous Zn-ion batteries. However, there is a lack of constructive methods for choosing suitable SEI compounds and feasible implementation routes. Here, inspired by the SEI-design for Li-metal batteries, we identified that Zn3(PO4)2with high interface energy could suppress Zn dendrite growth effectively and ZnF2could accelerate the kinetics of Zn²⁺transference and deposition, and thus constructing a composite SEI mainly composed of Zn3(PO4)2and ZnF2(ZCS) is likely to improve interface deposition and electrode kinetics comprehensively. However, the high redox potential of Zn/Zn²⁺and H2/H⁺makes it difficult to develop anin situSEI for Zn anodes in aqueous electrolytesviatraditional electrochemical routes. Considering this dilemma, we take advantage of the instability of KPF6in an aqueous environment and buildin situZCS on the Zn anode through the PF6⁻anion-induced chemical strategy. Surprisingly, ZCS-Zn exhibits enhanced reversibility with a smooth and compact structure during long-term cycling. Both cumulative capacity (2020 mA h cm⁻²) and the product of the largest current density and areal capacity (10 mA cm⁻²× 20 mA h cm⁻²) applied to ZCS-Zn reach the highest levels compared with those reported in recent reports under mildly acidic conditions. This work paves a new way for designing a desirable SEI on the Zn anode and may also guide the interface engineering of other systems to overcome the intrinsic defects in constructing favorable interphases.
The zinc metal anodes in aqueous zinc-ion batteries suffer from low cycling performance caused by uncontrolled dendrite. We have designed sulfonated poly-ether-ether-ketone (SPEEK) polymers as a surface coating layer on the zinc anode for dendrite suppression, in which the sulfonic groups in polymers act as effective active sites for zinc-ion diffusion. In SPEEK, the un-sulfonated domain serves as the framework and the sulfonated domain serves as the functional part to re-distribute the zinc ions. By optimizing the degree of SPEEK sulfonation, the best zinc anode coating has been achieved to present a high reversibility of over 1600 hours in symmetric cells and improved performance in full cells.
Graphene-based one-dimensional macroscopic assemblies (GBOMAs) have attracted great attention and extensive efforts have been devoted to enabling great progress. However, their applications are still restricted to less functionalized electronics, and the superior potentials remain scarce. Herein, inspired by natural scallion structure, a novel strategy was introduced to effectively improve battery performances through the mesoscale scallion-like wrapping of graphene. The obtained RGO/Ag-Li anodes demonstrated an ultralow overpotential of ∼11.3 mV for 1800 h at 1 mA cm-2 in carbonate electrolytes, which is superior to those of the most previous reports. Besides, this strategy can also be further expanded to the high mass loading of various cathode nanomaterials, and the resulting RGO/LiFePO4 cathodes exhibited remarkable rate performance and cycle stability. This work opens a new avenue to explore and broaden the applications of GBOMAs as scaffolds in fabricating full lithium batteries via maximizing their advantages derived from the unique structure and properties.
When two is better than four
Batteries based on the reaction of zinc and oxygen have been used for more than a century, but these have been primary (that is, nonrechargeable) cells. These batteries use an alkaline electrolyte and require a four-electron reduction of oxygen to water, which is a slow process. Sun et al. show that with the right choice of nonalkaline electrolyte, the battery can operate using a two-electron zinc-oxygen/zinc peroxide chemistry that is far more reversible. By making the electrolyte hydrophobic, water is excluded from the near surface of the cathode, thus preventing the four-electron reduction. These batteries also show higher energy density and better cycling stability.
Science , this issue p. 46
High-energy rechargeable lithium (Li) metal batteries (LMBs) with Li metal anode (LMA) were first developed in the 1970s, but their practical applications have been hindered by the safety and low-efficiency concerns related to LMA. Recently, a worldwide effort on LMA-based rechargeable LMBs has been revived to replace graphite-based, Li-ion batteries because of the much higher energy density that can be achieved with LMBs. This review focuses on the recent progress on the stabilization of LMA with nonaqueous electrolytes and reveals the fundamental mechanisms behind this improved stability. Various strategies that can enhance the stability of LMA in practical conditions and perspectives on the future development of LMA are also discussed. These strategies include the use of novel electrolytes such as superconcentrated electrolytes, localized high-concentration electrolytes, and highly fluorinated electrolytes, surface coatings that can form a solid electrolyte interphase with a high interfacial energy and self-healing capabilities, development of "anode-free" Li batteries to minimize the interaction between LMA and electrolyte, approaches to enable operation of LMA in practical conditions, etc. Combination of these strategies ultimately will lead us closer to the large-scale application of LMBs which often is called the "Holy Grail" of energy storage systems.
Lithium (Li) metal represents one of the most promising anode materials for constructing high-energy-density rechargeable batteries. However, uncontrolled Li dendrite growth induces limited lifespan and safety hazards, impeding the development of Li metal batteries severely. Introducing a Li host has been shown to effectively relieve dendrite growth, while further construction of lithiophilic sites will significantly facilitate uniform Li deposition for stably cycling Li metal batteries. Herein, a boroxine covalent organic framework (COF-1) is employed to construct a lithiophilic host for dendrite inhibition in working Li metal batteries. The well-defined boroxine sites demonstrate ideal lithiophilicity to reduce the Li nucleation energy barrier, and the ordered framework structure of COF-1 affords a uniform distribution of the lithiophilic sites. As a result, the COF-1-based Li host affords a more than doubled lifespan of routine anodes in both half- and full cells. This work demonstrates the promising potential of applying advanced framework materials to essential energy-related processes.
Rechargeable aqueous metal-ion batteries are very promising as alternative energy storage devices during the post-lithium-ion era because of their green and safe inherent features. Among the different aqueous metal-ion batteries, aqueous zinc-ion batteries (ZIBs) have recently been studied extensively due to their unique and outstanding benefits that hold promise for large-scale power storage systems. However, zinc anode problems in ZIBs, such as zinc dendrites and side reactions, severely shorten the ZIB's cycle lifetime, thus restricting their practical application. Here, we sum up in detail the recent progress on general strategies to suppress zinc dendrites and zinc anode side reactions based on advanced materials and structure design, including the modification of the planar zinc electrode surface layer, internal structural optimization of the zinc bulk electrode, modification of the electrolyte and construction of the multifunctional separator. The various functional materials, structures and battery efficiencies are discussed. Finally, the challenges for ZIBs are identified in the production of functional zinc anodes.
Rechargeable zinc metal batteries (RZMBs) offer a compelling complement to existing lithium ion and emerging lithium metal batteries for meeting the increasing energy storage demands of the future. Multiple recent reports have suggested that optimized electrolytes resolve a century-old challenge for RZMBs by achieving extremely reversible zinc plating/stripping with Coulombic efficiencies (CEs) approaching 100%. However, the disparity among published testing methods and conditions severely convolutes electrolyte performance comparisons. The lack of rigorous and standardized protocols is rapidly becoming an impediment to ongoing research and commercialization thrusts. This Perspective examines recent efforts to improve the reversibility of the zinc metal anode in terms of key parameters, including CE protocols, plating morphology, dendrite formation and long-term stability. Then we suggest the most appropriate standard protocols for future CE determination. Finally, we envision future strategies to improve zinc/electrolyte stability so that research efforts can be better aligned towards realistic performance targets for RZMB commercialization. Zinc metal batteries (ZMBs) provide a promising alternative to lithium metal batteries but share the formidable challenges in reversibility. The authors discuss the key performance metrics of ZMBs and propose a protocol to assess the true reversibility of zinc metal anodes.
Electrochemical capacitors can store electrical energy harvested from intermittent sources and deliver energy quickly, but their energy density must be increased if they are to efficiently power flexible and wearable electronics, as well as larger equipment. This Review summarizes progress in the field of materials for electrochemical capacitors over the past decade as well as outlines key perspectives for future research. We describe electrical double-layer capacitors based on high-surface-area carbons, pseudocapacitive materials such as oxides and the two-dimensional inorganic compounds known as MXenes, and emerging microdevices for the Internet of Things. We show that new nanostructured electrode materials and matching electrolytes are required to maximize the amount of energy and speed of delivery, and different manufacturing methods will be needed to meet the requirements of the future generation of electronic devices. Scientifically justified metrics for testing, comparison and optimization of various kinds of electrochemical capacitors are provided and explained.
Recent success in extending the electrochemical stability window of aqueous electrolytes to 3.0 V by using 21m “water-in-salt” (WiS) has raised a high expectation for developing safe aqueous Li-ion batteries. However, the most compatible Li4Ti5O12 anodes still cannot use in WiS electrolyte due to the cathodic limit (1.9 V vs. Li/Li+). Herein, a UV-curable hydrophilic polymer is introduced to further extend the cathodic limit of WiS electrolytes and replace separator. In addition, a localized strongly basic solid polymer electrolyte (SPE) layer is coated on anode to promote the formation of LiF-rich SEI. The synthetic impacts of UV-crosslink and local alkaline SPE on anodes extend the electrochemical stability window of the solid-state aqueous polymer electrolyte to ~ 3.86 V even at a reduced salt concentration of 12 mol kg-1. It enables a separator-free LiMn2O4//Li4Ti5O12 aqueous full cell with a practical capacity ratio (1.14) of cathode and anode to deliver a steady energy density of 151 Wh kg-1 at 0.5 C with initial Coulombic efficiency of 90.50% and cycle for over 600 cycles with average Coulombic efficiency of 99.97%, which was never reported before for aqueous LiMn2O4//Li4Ti5O12 full cell. This flexible and long-duration aqueous Li-ion battery with hydrogel WiSE can be widely used as the power sources in wearable devices and electrical transportations where both energy density and battery safety are of high priority. An ultra-thick LTO electrode with UV-curable polymer electrolyte as binder is demonstrated as solid state battery electrode. And a high-voltage (7.4 V) solid-state bipolar cell is assembled with solid-state UV-curable polymer as electrolyte.
Aqueous zinc ion batteries (ZIBs) are truly promising contenders for the future large-scale electrical energy storage applications due to their cost-effectiveness, environmental friendliness, intrinsic safety, and competitive gravimetric energy density. In light of this, massive research efforts have been devoted to the design and development of high-performance aqueous ZIBs; however, there are still obstacles to overcome before realizing their full potentials. Here, the current advances, existing limitations, along with the possible solutions in the pursuit of cathode materials with high voltage, fast kinetics, and long cycling stability are comprehensively covered and evaluated, together with an analysis of their structures, electrochemical performance, and zinc ion storage mechanisms. Key issues and research directions related to the design of highly reversible zinc anodes, the exploration of electrolytes satisfying both low cost and good performance, as well as the selection of compatible current collectors are also discussed, to guide the future design of aqueous ZIBs with a combination of high gravimetric energy density, good reversibility, and a long cycle life.
The low cycle stability of lithium anode has become one of the bottlenecks restricting the development of lithium-metal batteries with high theoretical energy density. Serious side reactions between lithium and electrolyte components are one of the key reasons for the poor cycle stability of lithium anode. Herein, lithiated graphene oxide (GO-Li) and lithium poly(styrene sulfate) (PSS-Li) are used to construct the composite membranes for the protection of Li-anode, which show the long-term operation over 1000 h in Li‖Li symmetric cells in the presence of redox chemicals as an indicator of side reaction source. The high content of Li+ of PSS-Li can not only inhibit the dissolution and diffusion of redox molecules in the membrane, but also improve Li+ transport rate through the membrane. Taking lithium-oxygen (Li-O2) battery as the model device and 2,2,6,6-tetramethyl-1-piperidinyloxy as model redox chemicals to accelerate cathodic reaction. Compared with those of conventional membranes, the artificial membranes can effectively inhibit the side reaction between the redox molecules and lithium anode. Consequently, the energy efficiency and cycle stability (over three times) of Li-O2 batteries are greatly improved. It provides an important theoretical basis and technical support for the design and preparation of membrane for high performance energy-conversion batteries.
Zinc metal is recognized as one of the most promising anodes for Zn-based batteries in the energy-storage system. However, the deposition and transference of bivalent Zn2+ into the host structure suffer from sluggish kinetics accompanying the side-reactions at the interface. Herein, we report a new class of Zn anode modified by three-dimensional (3D) nanoporous ZnO architecture coating Zn plate (designated as Zn@ZnO-3D) prepared by in-situ Zn(OH)42- deposition onto the surface. Benefit from this novel structure, it has been proven to accelerate the kinetics of Zn2+ transference and deposition via the electrostatic attraction toward Zn2+ rather than the hydrated one in the electrical double layer. As a consequence, it achieves an average 99.55 % Zn utilization and 1000 cycles long-time stability. Meanwhile, the Zn@ZnO-3D/MnO2 full-cell delivers a nearly 100 % capacity retention after 500 cycles at 0.5 A g-1 with a specific capacity of 212.9 mA h g-1. We believe the mechanistic insight into the kinetics and thermodynamics properties of Zn metal, and the understanding of structure-interface-function relationships is very enlightening to other metal anodes in aqueous systems.
Zinc-ion batteries (ZIBs) are promising candidates for large-scale energy storage applications due to its large abundance, low toxicity, and low cost. In this work, we configured a zinc-based nonaqueous dual-ion battery (ZDIB) for the first time by using expanded graphite cathode, zinc foil anode, and ionic liquid (IL) electrolyte. The adoption of IL suppressed dendritic growth of zinc and avoided hydrogen evolution, resulting in satisfactory safety of the battery. Notably, this prepared ZDIB delivered a reversible discharge capacity of 57 mAh g−1 and a capacity retention of ~86% after 500 cycles. In addition, we developed a nonaqueous battery with dual-carbon configuration (ZDCB), exhibiting a reversible discharge capacity of 58 mAh g−1 and a capacity retention of ~88% after 500 cycles. These two kinds of nonaqueous zinc-based battery systems show potential applications for large-scale energy storage with good safety and environmental friendliness.
Aqueous Zn anodes have been revisited for their intrinsic safety, low cost, and high volumetric capacity; however, deep-seated issues of the dendrite growth and intricate side-reactions hindered their rejuvenation. Herein, a “brightener-inspired” polyamide coating layer which elevates the nucleation barrier and restricts Zn²⁺ 2D diffusion is constructed to effectively regulate the aqueous Zn deposition behavior. Importantly, serving as a buffer layer that isolates active Zn from bulk electrolytes, this interphase also suppresses the free water/O2-induced corrosion and passivation. With this synergy effect, the polymer-modified Zn anode produces reversible, dendrite-free plating/stripping with a 60-fold enhancement in running lifetime (over 8,000 h) compared to the bare Zn, and even at an ultrahigh areal capacity of 10 mAh cm⁻² (10 mA cm⁻² for 1 h, 85% depth of discharge). This efficient rechargeability for Zn anodes enables a substantially stable full-cell paired with a MnO2 cathode. The strategy presented here is straightforward and scalable, representing a stark, but promising approach to solve the anode issues in advanced Zn battery.
Zinc metal featuring low cost, high capacity, low potential, and environmental benignity is an exciting anode material for aqueous energy storage devices. Unfortunately, the dendrite growth, limited reversibility, and undesired hydrogen evolution hinder its application. Herein, we demonstrate that MOF ZIF-8 annealed at 500°C (ZIF-8-500) can be used as a host material for high-efficiency (approximately 100%) and dendrite-free Zn plating and stripping because of its porous structure, trace amount of zinc in the framework, and high over-potential for hydrogen evolution. The [email protected] anode (i.e., ZIF-8-500 pre-plated with 10.0 mAh cm ⁻² Zn) is coupled with an activated carbon cathode or an I 2 cathode to form a hybrid supercapacitor or a rechargeable battery, respectively. The supercapacitor delivers a high energy density of 140.8 Wh kg ⁻¹ (normalized to the mass of active materials in electrodes) while retaining 72% capacity over 20,000 cycles, and the battery shows a long life of 1,600 cycles. Aqueous Zn-based batteries and supercapacitors have been considered as promising candidates for electrochemical energy storage devices because of the inherent advantages of metallic Zn. Unfortunately, the stability of the Zn anode in the mild electrolyte is still much limited by the dendrite growth, undesired hydrogen evolution, and the formation of inert “dead” Zn. Here, we report the utilization of MOF ZIF-8 treated with an optimized temperature (500°C) as a host material for the development of highly stable and dendrite-free Zn metal anodes. The ZIF-8-500 anode exhibits unprecedented reversibility of Zn plating/stripping behavior, high Coulombic efficiency (close to 100%), and dendrite-free Zn. The novel [email protected] anode coupled with an activated carbon cathode or an I 2 cathode works well. This work represents a new and low-cost avenue for developing a highly reversible zinc metal anode. Zn-based MOF ZIF-8-500 (annealed at 500°C) possesses the trace amount of Zn ⁰ in the host framework and the high over-potential for hydrogen evolution. The resulting ZIF-8-500 anode exhibits high efficiency (close to 100%) and dendrite-free Zn plating/stripping.
The development of solid-state lithium batteries is largely hindered by the undesired lithium dendrite propagation during battery operations. High electronic conductivity of solid electrolytes is now revealed to be the main culprit.
Potassium-ion batteries (PIBs) have been considered as promising alternatives to lithium-ion batteries due to the high natural K abundance of 2.09 wt.% (vs. 0.0017 wt.% for Li) and low K/K+ redox potential of −2.93 V (vs. -2.71 V for Na/Na+). However, PIB electrodes still suffer huge challenges due to the large K-ion radius and slow reaction dynamics. Herein, we report a high-capacity Sb@CSN composite anode with Sb nanoparticles uniformly encapsulated by carbon sphere network (CSN) for PIBs. First-principles computations and electrochemical characterizations confirm a reversible sequential phase transformation of KSb2, KSb, K5Sb4, and K3Sb during potassiation/depotassiation process. In a concentrated 4M KTFSI/EC+DEC electrolyte, the Sb@CSN anode delivers a high reversible capacity of 551 mAh/g at 100 mA/g for 100 cycles with an extremely slow capacity decay of only 0.06% per cycle from the 10th to 100th cycling; when up to a high current density of 200 mA/g, Sb@CSN anode still maintains a capacity of 504 mAh/g for 220 cycles. The Sb@CSN anodes demonstrate one of the best electrochemical performances for all K-ion batteries anodes reported to date. The exceptional performances of Sb@CSN should be attributed to the efficient capsulation of small Sb nanoparticles into conductive carbon network as well as the formation of a robust KF-rich SEI layer on Sb@CSN anode in the concentrated 4M KTFSI/EC+DEC electrolyte.
The lithium–O2 battery is one of most promising energy storage and conversion devices due to its ultrahigh theoretical energy density and hence has broad application potential in electrical vehicles and stationary power systems. However, the present Li–O2 battery suffers from a series of challenges for its practical application, such as its low capacity and rate capability, poor round-trip efficiency and short cycle life. These challenges mainly arise from the sluggish and unsustainable discharge and charge reactions at lithium and oxygen electrodes, which determine the performance and durability of a battery. In this review, we first provide insights on the present understanding of the discharge/charge mechanism of such a battery and follow up with establishing a correlation between the specific materials/structures of the battery modules and their functionality/stability within the recent progress in electrodes, electrolytes and redox mediators. Considerable emphasis is paid to the importance of functional orientation design and the synthesis of materials/structures towards accelerating and sustaining the electrode reactions of Li–O2 batteries. Moreover, the future directions and perspectives of rationally constructed material and surface/interface structures, as well as their optimal combinations are proposed for enhancement of the electrode reaction rate and sustainability, and consequently for a better performance and durability of such batteries.
The development of multivalent cation based rechargeable devices have attracted increased interest because that one mole of multivalent ion can contribute double (for M²⁺) or triple (for M³⁺) electrons than monovalent ion (M⁺). Recently, multivalent cation based battery systems (e.g. Mg²⁺ and Al³⁺ batteries) have been widely investigated, however, less attention were paid on multivalent cation based supercapacitors and especially hybrid supercapacitors. Herein, we demonstrate a Zn-ion based hybrid supercapacitor (Zn-HSC) through directly designing Zn foil as both anode and current collector, and bio-carbon derived porous material as the cathode. The bivalent nature and high abundance of zinc can enable the Zn-HSC to achieve high energy density with low cost. After optimization, this Zn-HSC demonstrated superior electrochemical performances such as high discharge capacitance (170 F g⁻¹ at 0.1 A g⁻¹), good rate performance (~ 85% capacitance retention at 2 A g⁻¹), high energy density (52.7 Wh kg⁻¹ at 1725 W kg⁻¹ based on the weight of active materials), and excellent cycling stability with 91% capacitance retention after 20,000 cycles at 2 A g⁻¹.
Lithium-ion batteries have had a profound impact on our daily life, but inherent limitations make it difficult for Li-ion chemistries to meet the growing demands for portable electronics, electric vehicles and grid-scale energy storage. Therefore, chemistries beyond Li-ion are currently being investigated and need to be made viable for commercial applications. The use of metallic Li is one of the most favoured choices for next-generation Li batteries, especially Li–S and Li–air systems. After falling into oblivion for several decades because of safety concerns, metallic Li is now ready for a revival, thanks to the development of investigative tools and nanotechnology-based solutions. In this Review, we first summarize the current understanding on Li anodes, then highlight the recent key progress in materials design and advanced characterization techniques, and finally discuss the opportunities and possible directions for future development of Li anodes in applications.
Perfluorosulfonic acid ionomers (PFSI) with different side-chain lengths have been investigated with respect to their morphology and electrochemical properties in vanadium flow batteries (VFB). The results indicated that the membrane with the shortest side chains (SSC-M2) displayed small ion clusters and a low degree of hydrophobic-hydrophilic separation, which is favourable to reduce the cross-over of vanadium ions in the VFB. SSC-M2 shows a similar proton conductivity to Nafion, which carries longer ionic side chains but with much lower ion permeability. As a result, the VFB assembled with SSC-M2 exhibited a superior coulombic efficiency and a voltage efficiency close to that of Nafion115. In situ mass transfer revealed that SSC-M2 had a remarkably low degree of vanadium and water transfer across the membrane, which resulted in lower capacity fading than in the case of Nafion115. These results indicate that a membrane with short side chains is an ideal option in the fabrication of high-performance VFBs with low capacity loss.