  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.
