Synthesis and electrochemical performance of xLiV3O8·yLi3V2(PO4)3/rGO composite cathode materials for lithium ion batteries

Abstract

A series of xLiV₃O₈·yLi₃V₂(PO₄)₃/rGO (x : y = 2 : 1, 3 : 1, 1 : 1, 1 : 2, and 1 : 3) composites are synthesized by simple mechanical mixing of LiV₃O₈ and Li₃V₂(PO₄)/rGO, which are prepared by the hydrothermal method and the sol–gel route, respectively. From scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs, the composites are found to be a mixture of rod-like LiV₃O₈ particles and flower-shaped Li₃V₂(PO₄)/rGO. Among these composites, the 2LiV₃O₈·Li₃V₂(PO₄)/rGO electrode delivers an initial discharge capacity of 197 mA h g⁻¹ at a current density of 100 mA g⁻¹ between 2.0 V and 4.3 V, and shows the best comprehensive electrochemical property. The diffusion coefficients of Li ions in the 2LiV₃O₈·Li₃V₂(PO₄)/rGO electrode are in the range of 10^−11.5 to 10^−9.5 cm² s⁻¹ obtained using the galvanostatic intermittent titration technique (GITT).