New understanding of Li3VO4/C as potential anode for Li-ion batteries: Preparation, structure characterization and lithium insertion mechanism

Abstract The article gives a totally new understanding about lithium insertion behavior of Li 3 VO 4 as potential anode material for Li-ion batteries. The carbon-coated Li 3 VO 4 (Li 3 VO 4 /C) sample was synthesized firstly using simple solid-state method. X-ray diffraction, Raman spectra and Rietveld refinement results show that single-phase Li 3 VO 4 /C can be obtained even under the presence of carbon and reducing atmosphere. The final product demonstrates a favorable electronic conductivity with 6.67% residual carbon. Electrochemical testing shows that Li 3 VO 4 /C holds both much higher specific capacity and better electrochemical performance than that of carbon-free Li 3 VO 4 sample. The Li 3 VO 4 /C electrode display a discharge capacity of 738.5 mAh g −1 and a charge (reversible) capacity of 547.1 mAh g −1 with a high initial coulombic efficiency of 78.0% in the first cycle. First-principles calculation and GITT results illustrate that the maximum embeddable Li-ion number in a single cell is 3 corresponding to the change of V 5+ to V 2+ , and the Li-inserted sites is predicted by first-principles calculations. Furthermore, lithium insertion/de-insertion mechanism of Li 3 VO 4 /C is studied by in-situ XRD, and the results surely confirm that Li 3 VO 4 /C undergoes a reversible insertion/de-insertion mechanism during discharge/charge process.