Rationally designed C/Co₉S₈@SnS₂ nanocomposite as a highly efficient anode for lithium-ion batteries

Nanostructured transition metal sulfides are promising anode materials for lithium-ion batteries. Nevertheless, it is still a great challenge to prepare capacity-improved electrodes without reducing their rate capability and cycle stability. In this paper, we present a C/Co₉S₈@SnS₂ composite material by loading SnS₂ nanocrystals onto MOF-derived C/Co₉S₈ nanostructures. The C/Co₉S₈@SnS₂ composite has multiple active sites to store lithium ions. The specific capacity reaches 3.1 mAh cm^-2 when the current density is 0.224 mA cm^-2. The asynchronous electrochemical reaction between Co₉S₈ and SnS₂ offsets the volume expansion of the anode material. Meanwhile, the compact adhesion of carbon layers on the interfaces suppresses the destruction of the anode during the charging-discharging processes. Consequently, the synthesized electrode presents favorable capacity with high current density or under long-term cycling conditions. The prepared battery has a reversible specific capacity of 0.452 mAh cm^-2 and a coulomb efficiency of 99.7% after 500 cycles with a high current density of 2.24 mA cm^-2. The research results obtained in this work provides a feasible strategy to improve the performance of electrodes systematically.