Wang Yikui,Tao Jianming,Wang Jiangjie,Chen Shaoyang,Yang Yanmin,Lin Yingbin
Serious structural irreversibility and interfacial side reactions pose major challenges for the stable operation of LiCoO 2 cathodes at high voltages. Herein, we report a polymer-based solid electrolyte (SLP) composed succinonitrile, LiTFSI and PVDF as a binder to address these issues. The SLP binder exhibits superior performance compared to traditional PVDF and PVDF binders with LiTFSI, with higher ionic conductivity (8.46 × 10 − 5 S cm − 1 at 30 ℃), lower activation energy of 0.38 eV and excellent adhesion. Even with just 3% SLP binder, LiCoO 2 cathode operating at a cutoff voltage of 4.6 V and loaded with ~ 6.0 mg cm − 2 active material demonstrates improved rate capability at higher compaction densities, delivering a discharge specific capacity of 146.5 mAh g − 1 after 100 cycles at 0.5 C-rate. The SLP binder not only enhances Li + conduction but also facilitates the formation of a stable cathode-electrolyte interphase, thus reducing the Li + diffusion barrier and interface polarization, and enhancing battery’s performance at low temperature. Furthermore, the SPL binder’s high compatibility and elasticity with the electrolyte mitigate irreversible structural changes and volume expansion in LiCoO 2 during cycling, leading to better preservation of the layered structure and lower internal stress for stable cycling under high temperatures. This strategy provides a novel interface protection idea for electroceramic cathode materials and may facilitate commercial development.
All-solid-state batteries (ASSBs) have garnered considerable attention as promising candidates for next-generation energy storage systems due to their potentially simultaneously enhanced safety capacities and improved energy densities. However, the solid future still calls for materials with high ionic conductivity, electrochemical stability, and favorable interfacial compatibility. In this study, we present a series of halide solid-state electrolytes (SSEs) utilizing a doping strategy with highly valent elements, demonstrating an outstanding combination of enhanced ionic conductivity and oxidation stability. Among these, Li2.6In0.8Ta0.2Cl6 emerges as the standout performer, displaying a superionic conductivity of up to 4.47 mS cm–1 at 30 °C, along with a low activation energy barrier of 0.321 eV for Li+ migration. Additionally, it showcases an extensive oxidation onset of up to 5.13 V (vs Li+/Li), enabling high-voltage ASSBs with promising cycling performance. Particularly noteworthy are the ASSBs employing LiCoO2 cathode materials, which exhibit an extended cyclability of over 1400 cycles, with 70% capacity retention under 4.6 V (vs Li+/Li), and a capacity of up to 135 mA h g–1 at a 4 C rate, with the loading of active materials at 7.52 mg cm–2. This study demonstrates a feasible approach to designing desirable SSEs for energy-dense, highly stable ASSBs.
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