Electrolyte precursor-free approach to prepare composite electrolyte for all-solid-state Na-ion battery

Composite electrolytes with higher conductivities have been widely studied, aiming at application to advanced all-solid-state batteries with good safety and high energy density. Most composite electrolytes are prepared via physical blend of electrolyte precursors or modification/doping/reaction based on one of them, which may confine people's scope for the further development of advanced solid electrolytes. Herein, we first prepare composite electrolytes via sophisticated design of chemical reaction without using any electrolyte precursors. Chemical reaction between NaNH2 and B10H14 is successfully used to synthesize NaBH4-Na2B12H12 composite electrolyte with special core-shell structure. Importantly, the NaBH4-Na2B12H12 composite electrolyte synthesized via electrolyte precursor-free approach exhibits a high ionic conductivity of 1 x 10-4 S/cm at 373 K-over 1 (or 4) magnitude higher than the bulk Na2B12H12 (or NaBH4) and excellent electrochemical stability up to 5 V (vs. Na thorn /Na). All-solid-state Na-ion battery using the as-synthesized composite electrolyte can reversibly work more than 100 cycles with capacity retention of 75.4 mAh/g at 348 K and 0.1 & DEG;C. This work sheds new lights on the preparation of more advanced composite electrolytes. & COPY; 2023 Published by Elsevier Ltd.