Synthesizing nonstoichiometric Li3−3xV2+x(PO4)3/C as cathode materials for high-performance lithium-ion batteries by solid state reaction

Abstract

A simple solid state reaction method has been developed to synthesize nonstoichiometric Li_3−3xV_2+x(PO₄)₃/C (x = 0–0.15) nanocomposites. Among them, Li_3−3xV_2+x(PO₄)₃/C nanocomposites with x = 0.10 exhibit the best performance, especially notable for its high-rate performance. The discharge capacity of 124.3 mA h g⁻¹ is delivered at 20C, almost 1.5 times that of stoichiometric Li₃V₂(PO₄)₃/C nanocomposites cathode (85 mA h g⁻¹). Long-life cycling performance at a high rate of 20C is also exhibited, retaining 98.3% of its original discharge capacity (124.3 mA h g⁻¹) after 1000 cycles. The cyclic voltammetry and AC impedance analysis indicate that the Li_3−3xV_2+x(PO₄)₃/C (x = 0.10) composites show the best ionic diffusivity and lowest resistance.