Amorphous Na 2 TiS 3 as an active material for all-solid-state sodium batteries

Abstract

Amorphous transition metal polysulfides are promising high capacity electrode active materials for sodium secondary batteries. Here we report the superior electrode performance of amorphous Na 2 TiS 3 . Crystalline (c-) and amorphous (a-) Na 2 TiS 3 were prepared by solid phase reaction with heat treatment and mechanochemical reaction, respectively. a-Na 2 TiS 3 showed 10 fold higher ionic conductivity (1.5 © 10 16 S cm 11 ) than that of c-Na 2 TiS 3 . The all-solid-state cells using c-Na 2 TiS 3 and a-Na 2 TiS 3 showed reversible capacities of 110 mAh g 11 and 250 mAh g 11 , respectively. Amorphization of Na 2 TiS 3 is a powerful way to improve electrode performance in all-solid-state sodium secondary batteries.