A high performance fireproof quasi-solid-state electrolyte enabled by multi-phase synergistic mechanism

Composite quasi-solid electrolytes usually suffer from reduced safety performance due to the presence of liquid plasticizers and an inherently unsafe polymer matrix. Adding inorganic fillers is an effective strategy to improve the safety performance of quasi-solid electrolytes, but excessive content may block ion transport channels, leading to a decrease in electrochemical performance. Therefore, it is proposed to construct a multi-phase synergistic non-flammable composite quasi-solid electrolyte (MS-NCQE) by combining an intrinsically safe porous composite framework with a Li+ conductive polymer through in-situ solidification technique. Thanks to multi-phase synergistic mechanism, a porous composite framework consisting of ceramic powder as well as a non-flammable polymer matrix enables MS-NCQE to exhibit significantly improved safety properties. At the same time, due to the interaction between the third-phase Li+ conductive polymer and ceramic powder, MS-NCQE presents excellent lithium ion transport performance (6.59×10−4 S cm−1 at 25°C) and dendrite resistance (0.1 mA cm−2; 3000 h). Further, the as-prepared LiFePO4|Li and LiNi0.83Co0.12Mn0.05O2|Li batteries display outstanding cycling performance. In particular, the capacity retention rate of the LiFePO4|Li battery is approximately 98% after 300 cycles at 0.5 C, and its average Coulombic efficiency is higher than 99.8%. In addition, the pouch cell can work normally and safely under different abuse conditions. This work provides new insights into the design of composite quasi-solid electrolytes with high safety and excellent electrochemical properties.