The construction of molybdenum disulfide/cobalt selenide heterostructures @ N-doped carbon for stable and high-rate sodium storage

Abstract

Constructing heterostructures is an important approach to develop high-performance anode materials for sodium ion batteries (SIBs). The abundant phase interfaces provide numerous defects and active sites for rapid electron/ion transport. Herein, CoSe2 ⊂ NC@NC/MoS2 heterostructures are prepared through a multi-step reaction strategy, CoSe2 nanoparticles served as the coating shells for MoS2 cores are anchored in carbon frameworks. The core–shell structure effectively buffers the double volume expansion and inhibits the dissolution of MoS2 and CoSe2 in the electrolyte. As SIBs anodes, the heterostructure delivers a high reversible capacity of 481.6 mAh g−1 at 0.5 A g−1 after 100 cycles, superior rate capability (174.5 mAh g−1 at 20.0 A g−1), excellent long-term cycle performance (333.4 mAh g−1 after 2000 cycles at 5.0 A g−1). The DFT calculation proves that the electronic distribution of heterostructures is reconstructed with enhanced conductivity. The kinetic analysis, mechanism characterizations and full-cells tests exhibit the synergistic reaction mechanism among different components and practical application prospects. The heterostructure also shows more rapid ions diffusion kinetics than single components.