Structural stability and electronic property in K2S under pressure

Abstract

In this work, the structures, phase sequence, and metallic properties of K2S have been systematically explored. We confirm that the P63/mmc phase is the best possible candidate for the stable structure of K2S at low pressure range. Although the phases of P63/mmc and Cmcm K2S are semiconductors, two new structures of P6/mmm and P3m1 emerge with metallic characters at high pressures. The analyses of electronic localization functions reveal that the conductivity mainly comes from the electrons surrounding S atom chains, which supplies a potential way to improve the conductivity of sulfur to enhance the electrode recharge ability and rate capability in alkali sulfide battery under pressure.