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.