High-Performance and Highly Safe Solvate Ionic Liquid-Based Gel Polymer Electrolyte by Rapid UV-Curing for Lithium-Ion Batteries

作者：Gao, Xinzhu; Yuan, Wei^*; Yang, Yang; Wu, Yaopeng; Wang, Chun; Wu, Xuyang; Zhang, Xiaoqing; Yuan, Yuhang; Tang, Yong; Chen, Yu; Yang, Chenghao; Zhao, Bote

来源：ACS applied materials & interfaces, 2022, 14(38): 43397-43406.

DOI：10.1021/acsami.2c13325

• lithium-ion battery
• gel polymer electrolyte
• solvate ionic liquid
• UV-curing
• in situ method
• highly safe

Utilizing ionic liquids (ILs) with low flammability as the precursor component for a gel polymer electrolyte is a smart strategy out of safety concerns. Solvate ionic liquids (SILs) consist of equimolar lithium bis(trifluoromethylsulfonyl)imide and tetraglyme, alleviating the main problems of high viscosity and low Li+ conductivity of conventional ILs. In this study, within a very short time of 30 s, a SIL turns immobile using efficient and controllable UV-curing with an ethoxylated trimethylolpropane triacrylate (ETPTA) network, forming a homogeneous SIL-based gel polymer electrolyte (SGPE) with enhanced thermal stability (216 degrees C), robust mechanical strength (compression modulus: 1.701 MPa), and high ionic conductivity (0.63 mS cm-1 at room temperature). A Li|SGPE|LiFePO4 cell demonstrates high charge/discharge reversibility and cycling stability with a capacity retention rate of 99.7% after 750 cycles and an average Coulombic efficiency of 99.7%, owing to its excellent electrochemical compatibility with Li-metal. A close-contact electrode/ electrolyte interface is formed by in situ curing of the electrolyte on the electrode surface, which enables the pouch full cell to work stably under the conditions of cutting/bending. In view of the excellent mechanical, thermal, and electrochemical performances of SGPE, it is believed to be a promising gel polymer electrolyte for constructing high-safety lithium-ion batteries (LIBs).