Promoting the conversion of S and Li2S using a Co3O4@NC additive in all-solid-state Li–S batteries

Abstract

All-solid-state lithium–sulfur batteries (ASSLSBs) are promising candidates for the development of next-generation batteries with high energy density and improved safety. Nevertheless, the sluggish reaction kinetics of the S and Li₂S cathode and the low active material content hinder the further development of ASSLSBs. Herein, a Co₃O₄@nitrogen-doped carbon (Co₃O₄@NC) nanocomposite is used as an electronically conductive additive to promote the conversion kinetics of S and Li₂S in the solid sulfur cathode. With a high sulfur content of 50 wt% and sulfur loading of 4 mg cm⁻², ASSLSBs with the S–Co₃O₄@NC–Li₇P₃S₁₁ (S–CoNC–LPS) composite cathode exhibit a high specific capacity of 1313 mA h g⁻¹ at 0.2 mA cm⁻², as well as a reversible capacity of 1167 mA h g⁻¹ after 100 charge/discharge cycles. Furthermore, the S–CoNC–LPS cathode also demonstrates a high areal capacity of 16.12 mA h cm⁻², corresponding to a reversible capacity of 1343 mA h g⁻¹, and good cycling stability even with an ultra-high sulfur loading of 12 mg cm⁻². Such a superior electrochemical performance can be attributed to the fact that Co₃O₄@NC lowers the reaction energy barrier and promotes the interconversion of S and Li₂S.