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

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.