Rationally designed C/CoS@SnS 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/CoS@SnS composite material by loading SnS nanocrystals onto MOF-derived C/CoS nanostructures. The C/CoS@SnS composite has multiple active sites to store lithium ions. The specific capacity reaches 3.1 mAh cm when the current density is 0.224 mA cm. The asynchronous electrochemical reaction between CoS and SnS 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 and a coulomb efficiency of 99.7% after 500 cycles with a high current density of 2.24 mA cm. The research results obtained in this work provides a feasible strategy to improve the performance of electrodes systematically.