Unleashing the Potential of Li-Metal Batteries A Breakthrough Ultra-High Room-Temperature Ionic Conductivity Composite Solid-State Electrolyte

Abstract: The solid-state electrolyte is critical for achieving next-generation high energy density and high-safety batteries. Solid polymer electrolytes (SPEs) possess great potential for commercial application owing to their compatibility with the existing manufacturing systems. However, unsatisfactory room-temperature ionic conductivity severely limits its application. Herein, an ultra-high room-temperature ionic conductivity composite solid-state electrolyte (CSE) is prepared by introducing an appropriate amount of SiO2 nanosphere to the PVDF-HFP matrix. By doing this, the polymer particles are divided and surrounded by SiO2. And the interface amount is maximized resulting in the high ionic conductivity of 1.35 mS cm-1 under room temperature. In addition, the CSE shows a wide electrochemical window of 4.95 V and a moderate Li+ transference number of 0.44. The CSE demonstrates good stability with Li anode, with Li symmetric cells that could cycle 1000 h at a current density of 0.2 mA cm-2. The full cell assembled with LiFePO4 (LFP) and Li metal displays a high reversible specific capacity of 157.8 mAh g-1 at 0.1C, and it could maintain 92.9% of initial capacity after 300 cycles at 3C. Moreover, the strategy is applied in solid-state sodium/potassium batteries and displays excellent performance.