Electrochemical performance of carbon-coated Li3V2(PO4)3 cathode materials derived from polystyrene-based carbon-thermal reduction synthesis

Li₃V₂(PO₄)₃ cathode materials were synthesized by a simple carbon-thermal reduction method using polystyrene as a carbon source. The residual carbon produced by the pyrolysis of polystyrene produced fine particle sizes and uniform carbon distribution on the Li₃V₂(PO₄)₃ particle surface. By increasing the amount of polystyrene added in the range of 0-16 wt.%, the thickness of the carbon coating increased, and the coating thickness was found to influence the electrochemical performance of the Li₃V₂(PO₄)₃ significantly. Our results indicate that the 6 wt.% polystyrene added Li₃V₂(PO₄)₃ with a 0.5-1 nm thick carbon coating possesses the highest initial discharge capacity of 132.7 mAh g⁻¹ between 3.0 and 4.3 V at 0.1 C. However, at high current densities, the higher polystyrene added Li₃V₂(PO₄)₃/C with a thicker carbon coating shows better performance in terms of the discharge capacity and cycling stability than that with the thin carbon coating. The improved cycling performance at higher current densities is attributed to the relatively small particle size and the suppressed impedance increase because of the thicker carbon coating.