Sodium thiophosphate electrolyte thin films prepared by pulsed laser deposition for bulk-type all-solid-state sodium rechargeable batteries

Abstract

Sodium rechargeable batteries using earth-abundant raw material sources are more suitable for wide application as compared to lithium batteries. The development of inorganic solid electrolytes with high Na-ion conductivity is indispensable to realize all-solid-state sodium batteries. The sulfide solid electrolyte with cubic Na3PS4 phase has a high sodium-ion conductivity at room temperature. This research has addressed, for the first time, the preparation of Na3PS4 electrolyte thin films using pulsed laser deposition, to be applied in bulk-type all-solid-state sodium batteries. The heat-treated Na3PS4 thin film exhibited a conductivity of 3.5 × 10−5 S cm−1 at 25°C and the activation energy for conduction was calculated to be 45 kJ mol−1. The active material in the form of NaCrO2 particles coated with Na3PS4 thin film was applied in all-solid-state batteries, which functioned as a sodium secondary battery at room temperature.