Sol–gel-assisted, fast and low-temperature synthesis of La-doped Li3V2(PO4)3/C cathode materials for lithium-ion batteries

Abstract

A series of La-doped Li₃V₂(PO₄)₃/C cathode materials for Li-ion batteries are synthesized by a sol–gel-assisted, low-temperature sintering process. La(NO₃)₃ acts not only as the La source, but also, together with the intermediate product LiNO₃, promotes combustion, the ultrahigh exothermic energy that is advantageous for the nucleation process. The subsequent sintering process at 600 °C for 4 h is sufficient to produce highly crystalline La-doped Li₃V₂(PO₄)₃/C composites. The as-prepared cathode materials display smaller particle size, lower electron-transfer resistance and faster Li ion migration, which is ascribed to enhanced Li-ion transfer because of the La doping. The resulting Li₃V_1.96La_0.04(PO₄)₃/C cathode has a stable specific capacity of 160 mA h g⁻¹ at low charge–discharge rates over 100 cycles, and retained a stable capacity of up to 116 mA h g⁻¹ at a rate of 5 C, which is 40% higher than the undoped pristine cathode.