Nano-grain dependent 3D hierarchical VS2 microrods with enhanced intercalation kinetic for sodium storage properties

Construction of well-defined three-dimensional (3D) assembled architectures is an effective strategy to improve the electrochemical reaction kinetics of sodium-ion storage. Herein, 3D hierarchical VS2 microrods assembled by nanosheets comprised of small VS2 nano-grains are controllably synthesized by a facile in-situ chemical etching approach. Results show that the addition amount of ethanol serving as the etching agent has a great influence on the oriented growth and size (thickness-to-diameter ratio) of VS2 nano-grains. Moreover, (001)-oriented VS2 nano-grains with larger thickness-to-diameter ratio expose more layer-edges and unsaturated S-edges, and then dramatically improve the intercalation kinetic, eventually leading to the enhancement of rate performance and cycling capacity. When applied as anode for sodium ion batteries, this material affords a high capacity of 255 and 230 mAhg−1 even at a high rate of 1.0 and 2.0 A g−1, and a reversible capacity of 350 mAhg−1 is still achieved after the following cycling test of 200 cycles at 0.2 A g−1. The controllability and simplicity of the in-situ chemical etching approach, combined with the superior sodium storage properties present a promising strategy for the development of versatile synthesis techniques for energy storage applications.