Li₃V₂(PO₄)₃: Synthesis by sol-gel method and performance

Cathode material Li₃V₂(P0₄)₃ was synthesized by Sol-gel method using appropriate amounts of LiOH·H₂O (LiF, Li₂CO₃, LiCH ₃COO ·2H₂O), NH₄VO₃, H ₃PO₄ and citric acid. Synthesized conditions including lithium sources, pH value of the sol, presintering conditions, and calcining temperature were optimized. Structure, morphology, and electrochemical performance of the synthesized materials were studied by XRD, SEM, charge-discharge tests and cycle voltammetry. The results show that Li ₃V₂(PO₄)₃ prepared under the condition of LiOH · H₂O as lithium source, pH value of 3 for the sol, presintering at 300 °C for 4 h follwed by heating at 600 °C for 8 h under Ar and H₂ (9:1, V/V) mixture atmosphere has typical monoclinic structure, better cycle stability, and high discharge capacity, which has 130 mAh·g^-1 and 129 mAh·g^-1 initial discharge capacity under 0.1C and 1C discharge rate, respectively, 127 mAh·g^-1 capacity after 40 cycles under 1C rate with 98.4 % capacity retention and after the following 10 cycles under 10C rate still has 105 mAh·g^-1 capacity with 98.1% capacity retention. Cycle voltammetry test shows that the Li₃V₂(PO₄) ₃ material has better electrochemical reversibility.