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Lithium-metal batteries (LMBs) with high energy densities have aroused intensive interest in electrical energy storage devices but suffer from the risk of thermal runaway, especially under harsh conditions of high temperature or thermal abuse. Pursuing intrinsically thermally stable electrolytes with higher performance and higher safety beyond commercial liquid electrolytes is a major challenge in this field. Here we report on a unique, highly durable sulfolane-based gel electrolyte constructed by a facile gelling strategy. This method takes advantages of thermotolerant sulfolane as a plasticizer and strong dipole-dipole interactions to achieve the gelation of polymer polyvinylidene fluoride/polyethylene oxide. We systematically investigated the influence of gelled sulfolane on gel formation, lithium plating/stripping, and solid electrolyte interphase. Benefiting from favorable interface engineering, the sulfolane-based gel electrolyte remarkably enhances the cyclic and safety performances of LMBs. When used in the Li/LiCoO2battery, the resulting gel electrolyte enables long-term cycling stability at high temperatures up to 90°C. Moreover, the thermal safety of practical Li/LiCoO2pouch cells (up to 190°C) has also been demonstrated by accelerating rate calorimetry. These results contribute to the development of high-safety LMBs that require abuse tolerance, high energy, and long calendar life.

Polymer-derived nitrogen-doped porous carbon networks display stable electrochemical properties and have been extensively studied as electrode materials. However, the precise control of pore morphology and size distribution remains challenging. Herein, the pore structure of polyimide membranes was initially established by controlling the coating thickness. Subsequent to carbonization, the pore morphology and surface area were further controlled. The resulting optimized porous carbon exhibits a uniform pore distribution, a large specific surface area, and appropriate heteroatom content. In a three-electrode system, it achieves a specific capacitance of 328.4 F g−1at 0.5 A g−1. Additionally, the symmetric supercapacitor delivers an impressive energy density of 20.3 Wh kg−1at 350 W kg−1in a 6 M KOH electrolyte, retaining 88.5 % of its specific capacity after 5000 cycles. Notably, the specific capacitance of a flexible solid-state device is 151.6 mF cm−2at 2 mA cm−2. This work introduces a simple, environmentally friendly approach for producing porous carbon from polyimide with adjustable morphology.

Electrochemo-mechanical failure of Ni-rich cathodes leads to rapid performance degradation, and thus hinders their practical implementation in all-solid-state lithium batteries (ASSLBs). To solve this problem, herein, we propose a bifunctional chemomechanics strategy by protecting polycrystalline LiNi0.6Co0.2Mn0.2O2(NCM) cathodes using a high-mechanical-strength fast ionic conductor LiZr2(PO4)3(LZP) coating layer. The coating layer’s synergistic effect between mechanical strength and electrochemical stability is studied in Li6PS5Cl (LPSCl)-based ASSLBs for the first time. Using finite element method (FEM) simulations and various characterization techniques, we demonstrate that the robust and stable LZP (Young’s modulus 140.7 GPa, electrochemical stability window >5 V) coating layer mitigates the volume change and particle disintegration of polycrystalline NCM and electrochemical decomposition of LPSCl on the LPSCl/NCM interface. As a result, the LZP-modified ASSLBs display remarkably improved reversible capacity, cycle life, and rate performance. The synergy of mechanical and electrochemical properties of the coating layer will provide valuable guidance for the development of high-energy-density ASSLBs.