Vertically aligned VS2 on graphene as a 3D heteroarchitectured anode material with capacitance-dominated lithium storage

Abstract

Vertically aligned 2D few-layered VS₂ nanosheets onto a 2D graphene substrate were, for the first time, crafted by scalable solvothermal and post-annealing processes. The resulting 3D heterostructured VS₂-on-graphene (denoted as VS₂@Gr) is composed of interconnected nanosheet networks with an efficient exposure of electrochemically active surfaces, nanosheet edges, and abundant porous channels. Such robust hierarchical architectures possess significant advantages over individual building blocks, inhibiting intersheet aggregation, facilitating electrolyte percolation/active-material utilization, promoting ion diffusion/electron conduction, and retaining structural integrity/mechanical stability. Surprisingly, these synergetic characteristics endow VS₂@Gr with very favorable capacitive kinetics in the Li-storage behavior. When employed as an anode, the VS₂@Gr exhibits remarkable electrochemical performance with large reversible capacity (989 mA h g⁻¹ at 0.1 A g⁻¹), high initial coulombic efficiency (64%), a larger ion diffusion coefficient, superior rate capability (675 mA h g⁻¹ at 1 A g⁻¹), and long cycling stability (77% retention at 10 A g⁻¹ after 10 000 cycles), outperforming its VS₂ counterpart with a dominant diffusion-controlled behavior. This work may provide new insights into the architectural engineering of 3D heterostructured nanomaterials comprising two dissimilar 2D constituents for advanced energy storage.