Construction of cobalt sulfide/molybdenum disulfide heterostructure as the anode material for sodium ion batteries

Molybdenum disulfide has been considered as an ideal candidate anode material for alkali-ion batteries because of its unique layered structure as well as considerable theoretical capacity. However, poor electronic conductivity and large volume expansion in the repeatedly charging/discharging process impede its practical application. In this work, we fabricate a cobalt sulfide/molybdenum disulfide-based anode material with a heterostructure for sodium-ion batteries (SIBs), which can be constructed by combining a one-pot hydrothermal route with a solid-state sulfidation step. Compared with the anodes based on pure cobalt sulfide and pure molybdenum disulfide materials, the cobalt sulfide/molybdenum disulfide-based one displays superior cycling stability (e.g., 510.9 mAh g⁻¹ @1 A g⁻¹ at the 1000th cycle), and an extraordinary rate performance (341 mAh g⁻¹ @10 A g⁻¹). The material characterizations show that the obtained cobalt sulfide/molybdenum disulfide material has abundance mesopores. The kinetics analysis further confirms the decreasing of charge transfer resistance and the increasing of sodium ions diffusion coefficient with the cycling for this material. As a result, the reasonable design of the cobalt sulfide/molybdenum disulfide heterostructure can provide abundant active sites for the storage of sodium ions and facilitate surface capacity-controlling behavior. This work offers useful insights into the utilization of those heterostructured materials for SIBs.