Fluorinated Superionic Oxychloride Solid Electrolytes for High-Voltage All-Solid-State Lithium Batteries
Yingjie Gao, Shumin Zhang, Feipeng Zhao, Jian Wang, Jigang Zhou, Weihan Li, Sixu Deng, Jiamin Fu, Xiaoge Hao, Ruying Li, Xueliang Sun
Abstract
As the demand for higher energy density grows rapidly, the development of high-voltage all-solid-state lithium batteries (ASSLBs) becomes essential. However, most existing solid electrolytes (SEs) are still incapable of stable operation at high voltages. Herein, we report a series of fluorinated lithium tantalum oxychlorides (LTOC-F) as amorphous SEs for high-voltage ASSLBs. The optimized LTOC-10%F SE exhibits remarkably improved high-voltage stability and a high ionic conductivity of 2.3 mS cm –1 at 25 °C. The ASSLB using an LCO cathode and LTOC-10%F SE achieves a high capacity of 180 mAh g –1 with a cutoff voltage of 4.5 V and high-capacity retention of 81% after 300 cycles. Furthermore, the underlying mechanisms for enhanced performance are identified as the intrinsically extended electrochemical window of SE and the in-situ-formed LiF-rich cathode-electrolyte interface (CEI). Overall, this work provides a fluorination strategy for high-voltage ASSLBs and also offers insights into the analysis of amorphous SEs and CEIs.