Construction of MoS2/CoS2/SNGr three-dimensional interconnected network composites for advanced sodium-ion batteries

Generally, the bimetallic sulfides could produce more abundant redox reactions and form more stable heterostructures, which make the composites exhibit better specific capacity, rate performance and cycle life. Therefore, a designed hierarchical nanostructured composite material (MoS2/CoS2/SNGr) consisting of CoS2 nanoparticles, MoS2 nanosheets and heteroatom doped graphene was achieved by employing a combination of hydrothermal and solvothermal methods with the assistance of 1,10-phenanthroline. In this unique architecture, on the one hand, MoS2 and sulfur and nitrogen co-doped graphene (SNGr) composite served as a substrate can not only prevent the direct exposure of CoS2 to the electrolyte but also maintain the structural stability of the electrode. On the other hand, the SNGr and three-dimensional interconnected network structure can greatly reduce the diffusion distance of the sodium ion and electron. Due to the above excellent structure, the prepared MoS2/CoS2/SNGr composite material exhibits very high sodium storage performance of 584.7 mAh g- 1 at 2 A g- 1 after 700 cycles, outstanding pseudocapacitance of 78 % at a scan rate of 1 mV s- 1 and small electrochemical impedance of 9.3 Omega. Consequently, this MoS2/CoS2/SNGr composite is a promising candidate as an anode material for high-performance sodium-ion batteries.