A solid-like dual-salt polymer electrolyte for Li-metal batteries capable of stable operation over an extended temperature range

• DOI: 10.1016/j.ensm.2021.02.045
• Publication Date: 2021-02-26T18:23:18Z
• Authors: Jing Yu; Jiapeng Liu; Xidong Lin; Ho Mei Law; Guodong Zhou; Stephen C.T. Kwok; Matthew J. Robson; Junxiong Wu; Francesco Ciucci
• Keywords: High conductivity; Li-metal anode; Dual salts; High/low-temperature performance; Solid-like polymer electrolyte; 01 natural sciences; 7. Clean energy; Coordinated solvents; 0104 chemical sciences; 3. Good health

Abstract Solid polymer electrolytes (SPEs) and gel polymer electrolytes (GPEs) show great promise for the realization of commercial, high performance Li-metal batteries (LMBs). However, the interfacial and high-temperature instability of GPEs, and the low room-temperature ionic conductivity of SPEs still limit their practical implementation. This article presents a solid-like dual-salt polymer electrolyte (DSPE), consisting of coordinated solvents and thermally stable Li-salts within a temperature-resistant polymer matrix, as a promising new strategy for addressing these issues. The developed DSPE demonstrates high ionic conductivity of 0.16, 0.73, and 1.93 mS cm−1 at −20, 20, and 100 °C, respectively. Li|DSPE|LiFePO4 batteries using this DSPE deliver an initial discharge capacity of 151 mAh g−1 at 0.5C, a rate performance of 123 mAh g−1 at 3C, and excellent long-term stability with a retained capacity of 143 mAh g−1 after 500 cycles at 0.5C and 23 °C. Further, the battery shows stable cycling between −10 °C and 80 °C. This impressive electrochemical performance is ascribed to the high Li+ conductivity of the membrane, the stabilization of the Al current collector, and the formation of a robust, LiF-rich solid-electrolyte interphase containing conductive Li-B-O-based species.