Synthesis and characterization of Li3V(2 − 2x/3)Mgx(PO4)3/C cathode material for lithium-ion batteries

Li₃V_{(2 − 2x/3)}Mg_x(PO₄)₃/C (x = 0, 0.15, 0.30, 0.45) composites have been synthesized by the sol-gel assisted solid state method, using adipic acid C₆H₁₀O₄ (hexanedioic acid) as carbon source. The particle size of the composites is ∼1 μm. During the pyrolysis process, Li₃V_{(2 − 2x/3)}Mg_x(PO₄)₃/C network structure is formed. The effect of Mg²⁺ doped on the electrochemical properties of Li₃V₂(PO₄)₃/C positive materials has been studied. Li₃V_1.8Mg_0.30(PO₄)₃/C as the cathode materials of Li-ion batteries, the retention rate of discharge capacity is 91.4% (1 C) after 100 cycles. Compared with Li₃V₂(PO₄)₃/C, Li₃V_{(2 − 2x/3)}Mg_x(PO₄)₃/C composites have shown enhanced capacity and retention rate capability. The long-term cycles and ex situ XRD tests disclose that Li₃V_1.8Mg_0.30(PO₄)₃ exhibits higher structural stability than the undoped system.