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a,b,d) Cycling performance and c) Rate capability of batteries with PDOL@PP, PDOL@PVDF‐HFP, PDOL@PDA/PVDF‐HFP GPEs. and commercial electrolyte at 25 °C. e,f,g,h) Charge/discharge voltage profiles of LiFePO4//Li batteries with the above prepared GPEs at different current density and PDOL@PDA/PVDF‐HFP cell at 2 C at different cycles.
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Lithium metal battery (LMB) possessing a high theoretical capacity is a promising candidate of advanced energy storage devices. However, its safety and stability are challenged by lithium dendrites and the leakage of liquid electrolyte. Here, a self‐enhancing gel polymer electrolyte (GPE) is created by in situ polymerizing 1,3‐dioxolane (DOL) in th...
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... The cell capacity and energy density are calculated based on Lithium iron phosphate loading. [8,[31][32][33][34][35][36] DOL was polymerized by adding 1 mmol of LiFSI salt into 1 ml DOL [8,37]. The chemical synthesis scheme is shown as in Figure 1a. Figure 1b is the optical pictures of DOL monomer liquid, PDOL-LiFSI mixture and purified PDOL polymer. ...
... By adding c-LLZO before polymerization process ends, composite electrolytes (G1, G5, G10) can be produced as well. 1 H-NMR spectra of different samples are shown in Figure 1c. DOL spectrum is at the bottom of Figure 1c, in which the singlet peak at 4.91 ppm is assigned to 2 hydrogen atoms of methylene group [36] between two oxygen atoms and the singlet peak at 3.88 ppm is assigned to 4 hydrogen atoms of ethylene group [36] in DOL [35]. The integral ratio of these two peaks should be 1/2 and calculate to be 1/2.08. 1 H-NMR spectrum of purifies PDOL [33] is in the middle of Figure 1c. ...
... The integral ratio of these two peaks should be 1/2 and calculate to be 1/2.08. 1 H-NMR spectrum of purifies PDOL [33] is in the middle of Figure 1c. Methylene hydrogens and ethylene hydrogens in PDOL have singlet peaks at chemical shift of 4.77 ppm and 3.73 ppm [35,36]. Again, the integrals ratio of these two peaks should be 1/2 as well and calculated to be 1 to 1.98, which confirm the successful polymerization of DOL (PDOL produced). ...
Quasi-solid composited electrolytes were produced by LiFSI initiated polymerized poly-(Dioxolane) (PDOL) with garnet-LLZO (Li7La2Zr3O12) nanofibers and used in lithium-metal batteries. Linear sweep voltammetry shows that the initial oxidation voltage of 4.6 V for Gel-10% (G10, 10% wt. LLZO in PDOL) vs Li/Li+. EIS test of stainless steel// stainless steel symmetric cells for Gel-1% (G1), Gel-5% (G5) and Gel-10% (G10) show ion conductivity (5*10-5 S/cm). Li/G10/Li symmetric cells have stable stripping-plating cycling performance over 1300 hours continuously with the current density of 0.1 mA/cm2 at 25 oC, indicating a good interface contact and stable lithium-ion transport pathway through the composite electrolytes. LFP/G10/Li batteries have stable charge-discharge plateau, low polarization voltage of 0.07-volt, energy efficiency of 95% and coulombic efficiency of ~99% at current density of 26.3 mA/g at 25 oC for over 100 cycles.
... Furthermore, signals of lattice oxygen are observed, which again suggest the absence of CEI formation on parts of the LiCoO 2 surface. LiF and Li 3 N are observed in the F 1s spectra ( Figure S8) and N 1s spectra ( Figure S9) of the Li-CoO 2 after cycling in PDOL-T-F, which results from the decomposition of LiTFSI [44]. In addition, the more polar LiSO 2 F and SO 2 F components [41] also appear in the S 2p spectra (Figure 5d), which effectively reduces the interfacial impedance and enables rapid conduction of Li-ion. ...
... The elemental composition of the Li surface is tested using XPS. The results of the F 1s spectrum (Figure 6b) and N 1s spectrum ( Figure S10) show that the Li surface after PDOL cycling contained the lowest amount of LiF and Li 3 N, which mainly originated from the decomposition of LiTFSI [44]. The signals of LiF and Li 3 N are significantly enhanced after the introduction of TMS and FEC. ...
In-situ polymerized electrolytes significantly enhance the interfacial compatibility of lithium metal batteries (LMBs). Typically, in-situ polymerized 1,3-dioxolane (PDOL) exhibits low interfacial resistance, yet still suffers from low ionic conductivity and a narrow electrochemical stability window (ESW). Here, an ultra-stable PDOL-based polymer electrolyte is developed by incorporating plasticizers of tetramethylene sulfone (TMS) and fluorinated ethylene carbonate (FEC) into the 3D cross-linked network, achieving a significant enhancement in the transport capacity and efficiency of Li-ion. The ionic conductivity reaches 3.63×10−4 S cm−1 even at room temperature, and the transference number (\(t_{{\rm Li}^{+}}\)) is even higher at 0.85. Furthermore, the ESW of this electrolyte can be increased to 4.5 V with the addition of TMS, which forms a thin and robust antioxidant cathode-electrolyte interface (CEI) on the surface of high-voltage LiCoO2. FEC generates an inorganic-rich solid-electrolyte interface (SEI) on the Li anode, which effectively inhibits the growth of lithium dendrites. Benefiting from the aforementioned advantages, the high-voltage lithium metal battery demonstrates outstanding long-cycle stability, with 93.2% capacity retention after 200 cycles. This work offers a straightforward and accessible method for the practical implementation of high energy density in-situ polymerized solid-state LMBs.
... This porous PVDF-HFP has excellent liquid electrolyte retention ability and absorbs a large amount of Li + , ensuring sufficient Li + migration ability. Gang Sui [137] further modified the electrospun PVDF-HFP fiber membrane with dopamine (PDA). PDA can form hydrogen bonds with in-situ polymerized PDOL to further enhance the mechanical strength of the electrolyte membrane. ...
Polymer solid-state lithium batteries (SSLB) are regarded as a promising energy storage technology to meet growing demand due to their high energy density and safety. Ion conductivity, interface stability and battery assembly process are still the main challenges to hurdle the commercialization of SSLB. As the main component of SSLB, poly(1,3-dioxolane) (PDOL)-based solid polymer electrolytes polymerized in-situ are becoming a promising candidate solid electrolyte, for their high ion conductivity at room temperature, good battery electrochemical performances, and simple assembly process. This review analyzes opportunities and challenges of PDOL electrolytes toward practical application for polymer SSLB. The focuses include exploring the polymerization mechanism of DOL, the performance of PDOL composite electrolytes, and the application of PDOL. Furthermore, we provide a perspective on future research directions that need to be emphasized for commercialization of PDOL-based electrolytes in SSLB. The exploration of these schemes facilitates a comprehensive and profound understanding of PDOL-based polymer electrolyte and provides new research ideas to boost them toward practical application in solid-state batteries.
... Impressively, the battery using GPETS achieves remarkable Li plating/stripping stability in comparison with other GPEs in previous reports (Table S1). [46][47][48][49][50] The polarization voltages of Li||Li symmetrical cells using different electrolytes were measured at current densities of 0.5, 1.0, and 2.0 mA cm −2 and a fixed plating capacity of 1.0 mAh cm −2 ( Figure 4E). At 0.5 mA cm −2 , the GPETS shows an overpotential of 43 mV, which rises to 57 and 78 mV at 1.0 and 2.0 mA cm −2 , respectively. ...
... The cell exhibits exceptional cycling stability with high Coulombic efficiencies close to 100% when cycled at 5 C. A capacity retention of 74% can be obtained after 5000 cycles, corresponding to an ultralow capacity decay of 0.005% per cycle ( Figure S17C), which is a considerable advantage over GPEs (Table S1). [46][47][48][49][50] GPETS has the potential to be used in LMBs based on its improved performance in LiFePO 4 ||Li cells. ...
Li−I2 batteries have attracted much interest due to their high capacity, exceptional rate performance, and low cost. Even so, the problems of unstable Li anode/electrolyte interface and severe polyiodide shuttle in Li−I2 batteries need to be tackled. Herein, the interfacial reactions on the Li anode and I2 cathode have been effectively optimized by employing a well‐designed gel polymer electrolyte strengthened by cross‐linked Ti–O/Si–O (GPETS). The interpenetrating network‐reinforced GPETS with high ionic conductivity (1.88 × 10⁻³ S cm⁻¹ at 25°C) and high mechanical strength endows uniform Li deposition/stripping over 1800 h (at 1.0 mA cm⁻², with a plating capacity of 3.0 mAh cm⁻²). Moreover, the GPETS abundant in surface hydroxyls is capable of capturing soluble polyiodides at the interface and accelerating their conversion kinetics, thus synergistically mitigating the shuttle effect. Benefiting from these properties, the use of GPETS results in a high capacity of 207 mAh g⁻¹ (1 C) and an ultra‐low fading rate of 0.013% per cycle over 2000 cycles (5 C). The current study provides new insights into advanced electrolytes for Li−I2 batteries.
... In other words, PILs uniformly filled out the pores of the nanofibrous membrane and improved the physical interactions whereas addition of ILMs further improves the ion-dipole interaction between PILs-ILs. These results into formation of highly stable and strong interweaving networked around the PVDF-HFP NFs [52,56]. Thus, with addition of ILs further improves the mechanical properties. ...
... As shown in Fig. S17, the electrochemical stability window of UZE reaches up to 5.9 V (vs. Li + /Li), which is 1.1 V higher than that of PPE and significantly exceeds other literature-reported polyether electrolytes [18,20,22,27,35,45,46]. The interaction between ZIF-67 and polymer not only lead to the rapid Li + transport, but also enhances oxidative stability of polyether chain through the promotion of polymerization degree. ...
... Apart from that, -CF 3 signal in PPE representing the decomposition of TFSI − disappears in UZE and emerges as -N(SO 2 ) 2 (CF 3 ) 2 (293.2 eV, C 1 s and 401.8 eV, N 1 s) with higher proportion instead, suggesting the alleviated reduction of TFSI − by Li anode upon the caging effect of ZIF-67 [46]. This can also be verified through the decrease of LiF and Li 3 N proportion in Fig. 6e and 6f, since both are regarded as the final reduction products of TFSI − . ...
... Therefore, TEP-GPE effectively slowed down the decomposition of LiTFSI and reduced the content of inorganic components (LiF). The right amount of LiF could enhance and stabilize the SEI layer [26,27], while too much LiF made the deposition of lithium ions more inhomogeneous. Finally, the SEI layer in TEP-GPE contains the rigid inorganic components and flexible organic components [28], which provide flexibility and elasticity to stabilize the lithium metal anode during cycling. ...
The existing electrolytes suffer from the uncontrolled Li⁺ deposition, flammability, and limited ionic conductivity problems. The gel-electrolyte is a core technology for the lithium metal batteries as they offer diverse tools for constructing unique solvent structure and suppress the uncontrolled growth of lithium dendrites. Here, a localized-anion gel-electrolyte with poly(ethyl acrylate/acrylic acid lithium) is reported to achieve a dendrite-free lithium deposition with the stable solid-electrolyte interphase. The flame-retardant triethyl phosphate are engaged in gel-electrolyte as a plasticizer with a solution casting method, which improves the safety of Li metal batteries. The TFSI⁻ is localized by anionphilic -COOLi in the vicinity of polymers, which maintains the uniform lithium flux and suppresses the deposition to achieve the smooth lithium growth. The lithiophilic -COOR group homogenized the Li⁺ flow at the electrode/electrolyte interface and alleviated the local lithium-ion flow. The LFP//Li cells assembled with the gel-electrolyte can still maintain a coulombic efficiency of 99% and capacity retention of 96% after 320 cycles at 1 C. And the NCM811//Li cells assembled with the gel-electrolyte can maintain about 90% coulombic efficiency and 88% capacity retention after 120 cycles at 0.5 C. In summary, this work provides an effective strategy for the application of next-generation high-safety lithium metal batteries.
... Polymerization of DOL was analyzed by Fourier transform infrared spectroscopy (Thermo Fisher Nicolet iS5 FTIR spectroscopy). 1 H, 7 Li NMR and 13 C spectra were collected on Bruker AVANCE 3HD 600 MHz instruments using DMSO-d6 as solvent. [16,19,27] A scanning electron microscope (Zeiss G500) was used to observe the surface of the lithium metal anode after cycling. WATERS 2414 was used for GPC measurement, in which the PDD and PDDT electrolytes were dissolved in tetrahydrofuran (THF) with a concentration around 4 mg mL À 1 ; 2 mL solution was taken and flowed through a 0.45 μm filter at a flow rate of 1 mL min À 1 . ...
Gel polymer electrolytes (GPEs) have potential as substitutes for liquid electrolytes in lithium‐metal batteries (LMBs). Their semi‐solid state also makes GPEs suitable for various applications, including wearables and flexible electronics. Here, we report the initiation of ring‐opening polymerization of 1,3‐dioxolane (DOL) by Lewis acid and the introduction of diluent 1,1,2,2‐tetrafluoroethyl 2,2,3,3‐tetrafluoropropyl ether (TTE) to regulate electrolyte structure for a more stable interface. This diluent‐blended GPE exhibits enhanced electrochemical stability and ion transport properties compared to a blank version without it. FTIR and NMR proved the effectiveness of monomer polymerization and further determined the molecular weight distribution of polymerization by gel permeation chromatography (GPC). Experimental and simulation results show that the addition of TTE enhances ion association and tends to distribute on the anode surface to construct a robust and low‐impedance SEI. Thus, the polymer battery achieves 5 C charge‐discharge at room temperature and 200 cycles at low temperature −20 °C. The study presents an effective approach for regulating solvation structures in GPEs, promoting advancements in the future design of GPE‐based LMBs.
... Reproduced with permission. [42] Copyright 2021, the authors, published by Wiley-VCH GmbH. (E) Scheme of construction of 3D cross-linked network structure. ...
... LiFePO 4 |Li battery exhibited a high initial capacity (151.8 mAh g −1 ) and a high capacity retention ratio of 91.8% after 200 cycles. Chen et al. [42] prepared a nanofiber membrane of polydopamine/ PVDF-hexafluoropropylene (PDA/PVDF-HFP) as the skeleton, then the DOL precursor solution was in situ polymerized in the fibrous skeleton to form a PDOLbased GPE ( Figure 2D). PDA significantly increased the strength of the PVDF-HFP nanofiber membrane from 4.6 to 8.2 MPa due to the hydrogen bond interaction between PDA and PVDF-HFP. ...
Abstract The application of lithium‐based batteries is challenged by the safety issues of leakage and flammability of liquid electrolytes. Polymer electrolytes (PEs) can address issues to promote the practical use of lithium metal batteries. However, the traditional preparation of PEs such as the solution‐casting method requires a complicated preparation process, especially resulting in side solvents evaporation issues. The large thickness of traditional PEs reduces the energy density of the battery and increases the transport bottlenecks of lithium‐ion. Meanwhile, it is difficult to fill the voids of electrodes to achieve good contact between electrolyte and electrode. In situ polymerization appears as a facile method to prepare PEs possessing excellent interfacial compatibility with electrodes. Thus, thin and uniform electrolytes can be obtained. The interfacial impedance can be reduced, and the lithium‐ion transport throughput at the interface can be increased. The typical in situ polymerization process is to implant a precursor solution containing monomers into the cell and then in situ solidify the precursor under specific initiating conditions, and has been widely applied for the preparation of PEs and battery assembly. In this review, we focus on the preparation and application of in situ polymerization method in gel polymer electrolytes, solid polymer electrolytes, and composite polymer electrolytes, in which different kinds of monomers and reactions for in situ polymerization are discussed. In addition, the various compositions and structures of inorganic fillers, and their effects on the electrochemical properties are summarized. Finally, challenges and perspectives for the practical application of in situ polymerization methods in solid‐state lithium‐based batteries are reviewed.
... The incorporation of a liquid plasticizer allows the formation of better electrode interfaces, and results in good cycling stability and improved performance [6][7][8]. However, the liquid plasticizer has a negative impact on the mechanical properties of the final GPEs [9,10]. One of the main strategies to overcome this challenge is based on the incorporation of inorganic materials, resulting in composite gel polymer electrolytes (CGPEs) [11,12]. ...
To effectively use (Li) lithium metal anodes, it is becoming increasingly necessary to create membranes with high lithium conductivity, electrochemical and thermal stabilities, as well as adequate mechanical properties. Composite gel polymer electrolytes (CGPE) have emerged as a promising strategy, offering improved ionic conductivity and structural performance compared to polymer electrolytes. In this study, a simple and scalable approach was developed to fabricate a crosslinked polyethylene oxide (PEO)-based membrane, comprising two different glass fiber reinforcements, in terms of morphology and thickness. The incorporation of a solvated ionic liquid into the developed membrane enhances the ionic conductivity and reduces flammability in the resulting CGPE. Galvanostatic cycling experiments demonstrate favorable performance of the composite membrane in symmetric Li cells. Furthermore, the CGPE demonstrated electrochemical stability, enabling the cell to cycle continuously for more than 700 h at a temperature of 40 °C without short circuits. When applied in a half-cell configuration with lithium iron phosphate (LFP) cathodes, the composite membrane enabled cycling at different current densities, achieving a discharge capacity of 144 mAh·g-1. Overall, the findings obtained in this work highlight the potential of crosslinked PEO-based composite membranes for high-performance Li metal anodes, with enhanced near room temperature conductivity, electrochemical stability, and cycling capability.
