Unveiling the reaction mechanism of an Sb2S3–Co9S8/NC anode for high-performance lithium-ion batteries

Abstract

Metal sulfides are promising lithium-ion battery anode materials with high specific capacities, but there has been little in-depth discussion on the reaction mechanism of metal sulfides. In this study, a robust bimetallic sulfide heterogeneous material (Sb₂S₃–Co₉S₈/NC) based on a metal–organic framework was designed. The combination of in situ X-ray diffraction and ex situ transmission electron microscopy revealed the phase evolution behavior during the first cycle. During the lithiation process, Sb₂S₃ undergoes lithium insertion, conversion and alloying reactions to form crystalline Li₂S, Li₃Sb and metallic Sb. Co₉S₈ undergoes lithium insertion and transformation to form metallic Co and Li₂S. Lithium ions are extracted from the nanocrystalline phase and transformed into the original Sb₂S₃ and Co₉S₈ phases. The Sb₂S₃–Co₉S₈/NC anode exhibits excellent cycle stability (616 mA h g⁻¹ at 2 A g⁻¹ after 900 cycles) and fast lithium ion transfer kinetics. These results demonstrate the lithiation/delithiation mechanism of the Sb₂S₃-based anode and provide a new path for the development of high-performance LIB anodes based on bimetallic sulfides.