Fig 2 - available via license: Creative Commons Attribution-NonCommercial 3.0 Unported
Content may be subject to copyright.
Source publication
We review the development of carbon???sulfur composites and the application for Li???S batteries. Discussions are devoted to the synthesis approach of the various carbon???sulfur composites, the structural transformation of sulfur, the carbon???sulfur interaction and the impacts on electrochemical performances. Perspectives are summarized regarding...
Context in source publication
Context 1
... for the carbon-sulfur composite so far, and is also the best choice for industrial production. In this context, the thermal behaviour of sulfur is of interest. Elemental sulfur has a variety of crystalline and molecular/polymeric forms. The identication of these allotropic forms has been the subject of study over decades, and is summarized in Fig. 2 where cyclo-S 8 and catena-S 8 co-exist. S 8 rings undergo thermal scission to form linear sulfenyl diradicals at 159 C. Between 159 C and 444.6 C, sulfur rst polymerizes and then depoly- merizes, accompanied with a viscosity change which reaches a maximum at 186 to 188 C. S 8 is predominant at 444.6 C, but is dissociated into short ...
Similar publications
A single step strategy capable of improving specific capacity, power capability and faradic yield of a Li/CFx battery system is developed. The excellent electrochemical performance achieved here using fluorinated graphene with a very low fluorine content (x = 0.22) could lead to the development of highly efficient primary battery systems with low c...
A sulfur cathode with excellent electrochemical performance has been designed based on hollow PANI spheres, which can suppress the shuttle effect and buffer the volume expansion effectively. The discharge capacity is as high as 602 mA h g−1 even after 1000 cycles at 0.5 C.
While little success has been obtained over the past few years in attempts to increase the capacity of Li-ion batteries, significant improvement in the power density has been achieved, opening the route to new applications, from hybrid electric vehicles to high-power electronics and regulation of the intermittency problem of electric energy supply...
Using first principles density functional theory the formation energies of various binary compounds of lithium
graphite and its homologues were calculated. Lithium and graphite react to form Li1C6 (+141 mV) but not form
LiC4 (−143 mV), LiC3 (−247 mV) and LiC2 (−529 mV) because they are less stable than lithium metal itself.
Properties of structure...
A high performance Li3VO4/N-doped C anode was successfully prepared, which delivers an initial discharge/charge capacity of 600/472 mA h g-1 at 150 mA g-1, maintaining 462/460 mA h g-1 after 100 cycles. It shows no capacity attenuation over 2200 cycles at 2000 mA g-1, delivering a discharge/charge capacity of 267/264 mA h g-1.
Citations
... The detailed electrochemical reaction during charge-discharge process can be found in Figure 3a. [53] In discharging stage, the solid element sulfur in cathode is reduced to the intermediate LiPS at a voltage of 2.3 V. This reaction exhibits relatively fast reaction kinetics owing to the high solvency of LiPS in electrolyte and contributes the theoretical capacity of 418 mAh/g. ...
... The LiPS diffusion process is inevitably in the sulfur cathode with simple porous carbon material. [53] Reproduced with permission from Ref. [53]. Copyright 2013, Royal Society of Chemistry. ...
... The LiPS diffusion process is inevitably in the sulfur cathode with simple porous carbon material. [53] Reproduced with permission from Ref. [53]. Copyright 2013, Royal Society of Chemistry. ...
Currently, lithium sulfur (Li−S) battery with high theoretical energy density has attracted great research interest. However, the diffusion and loss process of intermediate lithium polysulfide during charge‐discharge hindered the application of the Li−S battery in modern life. To overcome this issue, metal organic frameworks (MOFs) and their composites have been regarded as effective additions to restrain the LiPS diffusion process for Li−S battery. Benefiting from the unique structure with rich active sites to adsorb LiPS and accelerate the LiPS redox, the Li−S batteries with MOFs modified exhibit superior electrochemical performance. Considering the rapid development of MOFs in Li−S battery, this review summarizes the recent studies of MOFs and their composites as the sulfur host materials, functional interlayer, separator coating layer, and separator/solid electrolyte for Li−S batteries in detail. In addition, the promising design strategies of functional MOF materials are proposed to improve the electrochemical performance of Li−S battery.
... As newly emerged carbon materials, porous carbon materials have the characteristics of a high specific surface area, strong adsorption capacity, and high thermal stability. Although porous carbon has been used for adsorption, catalysis, electrochemical energy storage, and other fields [17][18][19], the nonlinear optics and OL properties of porous carbon have not been reported. ...
With the wide application of intense lasers, the protection of human eyes and detectors from laser damage is becoming more and more strict. In this paper, we study the nonlinear optical limiting (OL) properties of porous carbon with a super large specific surface area (2.9 × 103 m2/g) using the nanosecond Z-scan technique. Compared to the traditional OL material C60, the porous carbon material shows an excellent broadband limiting effect, and the limiting thresholds correspond to 0.11 J/cm2 for 532 nm and 0.25 J/cm2 for 1064 nm pulses, respectively. The nonlinear scattering experiments showed that the OL behavior was mainly attributed to the nonlinear scattering effect, which is caused by the rapid growth and expansion of bubbles in the dispersion induced by laser irradiation, and the scattered light distribution is consistent with the results of Mie’s scattering. These results suggest that porous carbon materials are expected to be applied to the field of laser protection in the future to further protect the human eye and precision optical instruments.
... The arrangement of the Li-metal anode (theoretical capacity of 3860 mA h g −1 ) with the sulfur cathode (theoretical capacity of 1675 mA h g −1 ) can achieve signicantly higher theoretical energy densities of 2500 W h kg −1 or 2800 W h L −1 with respect to the weight or volume basis, with complete conversion of sulfur into Li 2 S [S 8 + 16Li + + 16e − / 8Li 2 S] in the electrochemical process, which is several times higher than that of the conventional Li-ion rechargeable batteries. [5][6][7][8] During the discharging process, Li + ions are reacted with sulfur and form long-chained polysuldes, further reduction converted long-chained polysuldes to shortlength suldes, Li 2 S 4 , Li 2 S 2, and Li 2 S as the nal product. In the charging process, Li + ions are moved toward the Li-metal anode, and sulfur is formed at the cathode. ...
Lithium–sulfur (Li–S) batteries are considered promising next-generation energy storage devices due to their low cost and high energy density (2600 W h kg⁻¹). However, the practical applicability of Li–S batteries is hindered by the insulating nature of sulfur cathodes, and the high solubility of polysulfides (Li2Sx, 3 < x ≤ 8) which are formed during the electrochemical process. Integrating sulfur into the carbon host is an effective way to enhance the conductivity of the electrode which hampers the shuttling effect of the polysulfides. Here in this study, hierarchical porous carbon structures (HPC) are prepared from spent coffee waste (SCW) by the KOH activation process and are encapsulated with sulfur (SHPC) which increases the interaction between sulfur and carbon and enhances both the electronic and ionic conductivities. Further wrapping of SHPC with N-doped multi-walled carbon nanotubes (NCNTs) gives a SHPC-NCNT composite, which alleviates the shuttling of polysulfides by trapping them and ensures the required conductivity to the sulfur cathode during the Li⁺ reactions. When studied as a cathode material for Li–S batteries, the prepared cathode showed 664 and 532 mA h g⁻¹ specific capacities after 150 cycles at 0.2C and 0.5C, respectively. The stable cyclability and rate capability properties of SPHCNCNT suggest that the prepared sulfur composite is suitable as a cathode material for Li⁺ energy storage applications.
... This mesoporous structure with a huge specific surface area is able to provide more active sites for the adsorption of elemental sulfur and maintain sufficient channels for Li + transportation during galvanic charge and discharge processes. [28][29][30] The sulfur is encapsulated into CoNC@ZnNC DSNCs using the temperature-dependent encapsulation methodology by taking advantage of the solubility difference of sulfur in formamide. Initially, elemental sulfur was added to the FA solvent and heated at 160°C for 10 min with stirring until it dissolved completely and formed a transparent solution with a concentration of 2 g L −1 ( Figure S5, Supporting Information). ...
Single‐atomic catalysts (SACs) are effective in mitigating the shuttling effect and slow redox kinetics of lithium polysulfides (LiPSs) in lithium–sulfur (Li–S) batteries, but their ideal performance has yet to be achieved due to the multi–step conversion of LiPSs requiring multifunctional active sites for tandem catalysis. Here we have developed double–shelled nano‐cages (DSNCs) to address this challenge, featuring separated and tunable single‐atom sites as nano reactors that trigger tandem catalysis and promote the efficient electrochemical conversion of LiPSs. This enables high capacity and durable Li–S batteries. The DSNCs, with inner Co–N 4 and outer Zn–N 4 sites (S/CoNC@ZnNC DSNCs), exhibit a high specific capacity of 1186 mAh g ⁻¹ at 1 C, along with a low capacity fading rate of 0.063% per cycle over 500 cycles. Even with a high sulfur loading (4.2 mg cm ⁻² ) and a low E/S ratio (6 μL mg ⁻¹ ), the cell displays excellent cycling stability. Moreover, the Li–S pouch cells are capable of stable cycling for more than 160 cycles. These results demonstrate the feasibility of driving successive sulfur conversion reactions with separated active sites, and are expected to inspire further catalyst design for high performance Li−S batteries.
This article is protected by copyright. All rights reserved
... Though lithium-ion batteries rule the world of batteries, their low specific capacity and safety issues limit their applications in electric vehicles, etc. Lithium-sulfur (LiÀ S) batteries gain attention because of their high energy density of up to 2600 Wh kg À 1 , their low cost, and their environment friendliness. [1][2][3][4] However, the main challenges obscuring the practical use of LiÀ S batteries are selfdischarge, the low conductivity of sulfur, dissolution of lithium polysulfides (LiPSs) in the electrolyte causing polysulfide shuttle between the electrodes and mysterious electrode/electrolyte interfacial properties. [4] One of the most common approaches to solve the aforementioned issues is using carbon-based cathode hosts to enhance the conductivity of sulfur and trap lithium polysulfides. ...
With high theoretical capacity and energy density, lithium‐sulfur batteries (Li−S) have the potential to meet future energy demands including electric vehicles. Various strategies have been developed to address the challenges of Li−S batteries such as polysulfide shuttling, capacity fading, and lithium dendrite formation. By using suitable electrolyte additives, it is possible to enhance the interfacial properties of Li−S batteries and mitigate polysulfide shuttling. In the present work, an aprotic ionic liquid Triethylsulfonium bis(trifluoromethane sulfonyl)imide ([S222][TFSI]) has been used as an electrolyte additive, and the physico‐electrochemical and interfacial properties are investigated. The Li||Li cell with hybrid electrolyte shows stable interfacial resistance and the EIS study during the first discharge and charge of Li−S cell demonstrates stable charge transfer and bulk resistances which indicate the enhanced interfacial properties and the inhibition of polysulfide shuttling. The first‐principles calculations were conducted to investigate the nature of the interaction between the lithium polysulfides (LiPSs) and the [S222][TFSI] molecule. Long chain LiPSs (Li2Sx, 4<x<8) interact with [S222][TFSI] molecule via Li‐bond and hyperconjugation effect. [S222][TFSI] shows the ability to dissolve Li2S and Li2S2 precipitation at the cathode surface which can result in increased utilization of active sulfur and reduced capacity fading.
... Indeed, ionic materials such as Li 2 S can form during charge/ discharge processes during battery operation in sulfur− graphite batteries. 15 In addition, in a recent paper, we showed the presence of Li 2 S at the termination of {111} and {001} stable surfaces of the Cl−Argyrodite, 16 which supports the hypothesis of an incipient phase separation working naturally as a possible coating agent. Therefore, Li 2 S represents an interesting starting material to develop and test a comprehensive simulation methodology aimed at understanding how diffusion phenomena occurring at electrolyte/electrode interfaces affect battery performance. ...
In order to investigate Li2S as a potential protective coating for lithium anode batteries using superionic electrolytes, we need to describe reactions and transport for systems at scales of >10,000 atoms for time scales beyond nanoseconds, which is most impractical for quantum mechanics (QM) calculations. To overcome this issue, here, we first report the development of the reactive analytical force field (ReaxFF) based on density functional theory (DFT) calculations on model systems at the PBE0/TZVP and M062X/TZVP levels. Then, we carry out reactive molecular dynamics simulations (RMD) for up to 20 ns to investigate the diffusion mechanisms in bulk Li2S as a function of vacancy density, determining the activation barrier for diffusion and conductivity. We show that RMD predictions for diffusion and conductivity are comparable to experiments, while results on model systems are consistent with and validated by short (10–100 ps) ab initio molecular dynamics (AIMD). This new ReaxFF for Li2S systems enables practical RMD on spatial scales of 10–100 nm (10,000 to 10 million atoms) for the time scales of 20 ns required to investigate predictively the interfaces between electrodes and electrolytes, electrodes and coatings, and coatings and electrolytes during the charging and discharging processes.
... It also buffers the volumetric changes during charge-discharge cycles, preventing failure, among other advantages. [8] The preparation of biomassderived carbons as a sulfur host has been reviewed [9,10] indicating that a natural source of biomass offers a sustainable precursor for the mass production of carbons. In this matter, the use of wastederived biomass offers an attractive alternative due to its low price and high availability, which also contributes to a circular economy and sustainable development. ...
The fabrication of cathodes with carbonized Agave tequilana bagasse for Li–S batteries is performed for the first time. Three porous carbonaceous structures are developed and studied to elucidate the best carbon textural properties in terms of their surface area and pore size distribution: hierarchical porosity, highly microporous, and nonporous material, for sulfur hosting in Li–S cathodes. N2 physorption, scanning electron microscopy, infrared spectroscopy, and potentiometric titrations analysis are performed to determine the textural, morphology, and physicochemical properties. The fabricated coin cells, CR2032, with cathodes made of mesoporous carbons, display a high discharge current (≈1600 mAh g⁻¹), superior performance, and cyclability up to 250 cycles. The performance of batteries is found to be strongly influenced by surface area and pore size of the carbon materials. The carbonized tequila bagasse hosting sulfur can be very useful to fabricate cathodes for Li–S batteries with high initial capacity and cycling stability.
... The temperature is further increased to 444.6°C, accompanied by the breakage of S─S bonds, allotropes containing rings of [5][6][7][8][9]18, and 20 sulfur atoms are taken shape, such as pentameric sulfur (S 5 ), cyclichexasulfide (S 6 ), as well as cyclicheptasulfide (S 7 ), whose structures, however, are extremely unstable and appear polymerization and depolymerization. [30] Simultaneously, it is followed by a change in sulfur viscosity, which achieves a maximum at 186-188°C, and elastic and sub-stable amorphous sulfur are developed when the hardening is conducted within this step. When the temperature exceeds 444.6°C, the S─S bond breaks again, forming linear sulfur of small molecules in liquid or vapor states, i.e., dimer sulfur (S 2 ), trimer sulfur (S 3 ), and tetramer sulfur (S 4 ) ( Figure 3). ...
It is undeniable that the dissolution of polysulfides is beneficial in speeding up the conversion rate of sulfur in electrochemical reactions. But it also brings the bothersome “shuttle effect”. Therefore, if polysulfides can be retained on the cathode side, the efficient utilization of the polysulfides can be guaranteed to achieve the excellent performance of lithium‐sulfur batteries. Based on this idea, considerable methods have been developed to inhibit the shuttling of polysulfides. It is necessary to emphasize that no matter which method is used, the solvation mechanism, and existence forms of polysulfides are essential to analyze. Especially, it is important to clarify the sizes of different forms of polysulfides when using the size effect to inhibit the shuttling of polysulfides. In this review, a comprehensive summary and in‐depth discussion of the solvation mechanism, the existing forms of polysulfides, and the influencing factors affecting polysulfides species are presented. Meanwhile, the size of diverse polysulfide species is sorted out for the first time. Depending on the size of polysulfides, tactics of using size effect in cathode, separator, and interlayer parts are elaborated. Finally, a design idea of materials pore size is proposed to satisfy the use of size effect to inhibit polysulfides shuttle.
... Despite the promising benefits, it is imperative to consider the inherent challenges of ASSLSBs to achieve a more comprehensive analysis. Firstly, the ionic and electronic insulating properties of sulfur make it difficult to use as the cathode; sulfur must be mixed with SSEs and carbon additives to form the triple-phase boundary with the ions and electrons [13]. Secondly, the intimate interfacial contact between sulfide-based SSEs and electron-conducting additives can promote sulfide-based SSE degradation, resulting in less conductive interphase around the active materials [14]. ...
The high theoretical energy density and superior safety of all-solid-state lithium-sulfur batteries (ASSLSBs) make them a promising candidate for large-scale energy storage applications. The sulfur active material used in the positive electrode exhibits a higher power density compared to the lithium sulfide active material employed in the electrode. However, the limited utilization of sulfur in the positive electrode is due to its low ionic and electronic conductivity. Herein, sulfur is confined within porous carbon (S/C) by vapor deposition to ensure electronic conductivity. Subsequently, LiX additives (where X = F, Cl, Br, and I) are introduced into the S/C composite to enhance ionic conductivity. In situ electrochemical impedance spectroscopy (EIS) with distribution of relaxation times (DRT) analysis and electrochemical evaluations demonstrated that the introduction of LiI additives significantly enhances ion transfer on the S/C composite, thereby improving its reaction electrochemical reaction activity during cycling. The electrochemical performance of ASSLSBs with LiX additives on S/C composite generally exhibits a decreasing trend in the order of LiI > LiBr > LiCl > LiF. The S/C composite with LiI additives (S/C@LiI) cathode employed in ASSLSBs demonstrated an impressive high discharge capacity of 2016.9 mAh g⁻¹ after 275 cycles with a capacity retention of 100% and a reversible discharge capacity of 627.1 mAh g⁻¹ at 1C for up to 450 cycles.
Graphical abstract
The introduction of LiI additives enhances ion transfer on the S/C composite cathode demonstrated by the in situ EIS and DRT analysis, thereby improving the electrochemical performance.
... Moreover, the pore size distribution shows that Co/N@CNT is a micromesoporous material, and the immense specific area and the hierarchical nature of the micro/mesoporous structure provide a significant number of active adsorption sites and also facilitate rapid ion penetration and rapid material transfer. [23,24] Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) pictures of the two carbon materials are displayed in Figure 2c-f, and Figures S2 and S3, Supporting Information, where it can be seen that there are many Co nanoparticles loaded on the extremities of the carbon nanotubes, similar to leaves growing on plant stems. Also, it can be observed from Figure 2d that not all the Co is loaded on the ends of the carbon nanotubes, and there is still a small amount of Co particles encapsulated by the carbon nanotubes. ...
Sodium–potassium (NaK) alloy electrodes are ideal for next‐generation dendrite‐free alkali metal electrodes due to their dendrite‐free nature. However, issues such as slow diffusion kinetics due to the large K⁺ radius and the loss of active potassium during the reaction severely limit its application. Here a novel cobalt/nitrogen‐doped carbon material is designed and it is applied to the construction of a NaK alloy electrode. The experimental and theoretical results indicate that the confining effect of the nitrogen‐doped graphitic carbon layer can protect the cobalt nanoparticles from corrosion leaching, while the presence of Co─Nx bonds and cobalt nanoparticles provides more active sites for the reaction, realizing the synergistic effect of adsorption‐catalytic modulation, lowering the K⁺ diffusion energy barrier and promoting charge transfer and ion diffusion. The application of this electrode to a symmetrical battery can achieve more than 1800 stable cycles under a current density of 0.4 mA cm⁻² and a charge/discharge specific capacity of 122.64 mAh g⁻¹ under a current of 0.5C in a full battery. This finding provides a new idea to realize a fast, stable, and efficient application of NaK alloy electrodes.
