Liquid-Phase Synthesis of Nanosized Na11Sn2PS12 Solid Electrolytes for Room Temperature All-Solid-State Sodium Batteries

The nanosized Na 11 Sn 2 PS 12 solid electrolyte with a particle size of around 200 nm is synthesized using the liquid-phase method using 1,2-dimethoxyethane. The sintering conditions for Na 11 Sn 2 PS 12 crystallization are systematically optimized to maximize ionic conductivity. The highest room temperature ionic conductivity of the liquid-phase-synthesized Na 11 Sn 2 PS 12 electrolytes (LP-Na 11 Sn 2 PS 12 ) is 1.73 × 10 –4 S cm –1, which is comparable with that of ball-milling samples (BM-Na 11 Sn 2 PS 12 ) of 2.16 × 10 –4 S cm –1 . Both Na 11 Sn 2 PS 12 electrolytes show an electrochemical window of 0.3–3.2 V. Moreover, the as-synthesized Na 11 Sn 2 PS 12 electrolytes are employed as solid electrolytes in TiS 2 /Na 11 Sn 2 PS 12 /Na all-solid-state batteries. The TiS 2 /LP-Na 11 Sn 2 PS 12 /Na battery shows a higher reversible capacity of 142.4 mAh g –1 compared with 110.5 mAh g –1 for the TiS 2 /BM-Na 11 Sn 2 PS 12 /Na battery after 10 cycles under 20 mA g –1 at 25 °C. The better performance of the TiS 2 /LP-Na 11 Sn 2 PS 12 /Na battery can be ascribed to improved solid–solid contact between the electrolyte and the electrode arising from the nanosized particles of LP-Na 11 Sn 2 PS 12 electrolytes.