Mo-doping modulated cationic vacancy in Zn3V2O8 with enhanced electrochemical performance for lithium-ion batteries

Given diverse redox reactions and abundant raw materials, Zn3V2O8 with high specific capacity is considered as a potential anode material for lithium-ion batteries. Same as other transition metal oxides, Zn3V2O8 suffers from infertile conductivity, sluggish ion diffusion and fast capacity loss derived from volume expansion during discharge/charge process, further hindering its application. In this work, a novel Mo doped Zn3V2O8 (Zn3V2-xMo5x/6O8) anode material with cationic vacancy (V vacancy) has been designed through a facile sol-gel method. It is found that a small Mo-doping amount has nearly no influence on the crystal structure, morphology and element valence states of Zn3V2O8. Mo doped Zn3V2O8 samples possess smaller charge transfer resistance and higher lithium ion diffusion coefficient. The results of electrochemical performance illustrate that Mo doped Zn3V2O8 can deliver higher reversible specific capacities and better rate capability compared with Zn3V2O8, which can be ascribed to the introduction of V vacancy. In particular, when Mo-doping amount is set as 0.03, the obtained Zn3V1.97Mo0.025O8 exhibits a reversible capacity of 481.1 mAh g-1 after 600 cycles at 1 A g-1. It is believed that this work could provide an effective and feasible strategy to construct high performance transition metal vanadate anode materials for lithium-ion batteries.