摘要:
磷酸钒锂因其具有较高的能量密度、良好的结构稳定性、安全性能以及低温性能而成为潜在的、最具有前途的锂离子电池正极材料。以LiOH·H2O作为Li源,以V2O5作为V源,以NH4H2PO4提供磷酸根,以柠檬酸为还原剂进行配料并球磨后通过碳热还原法制备Li3V2(PO4)3/C正极材料。通过XRD、恒电流充放电等测试手段研究了烧结温度和烧结时间对Li3V2(PO4)3正极材料结构及电化学性能的影响,通过多次试验获得制备性能优良的单斜Li3V2(PO4)3正极材料的最佳烧结工艺参数。结果表明850℃、10 h合成的Li3V2(PO4)3/C样品的结晶度最好,晶型最完整,结构最稳定,极化最低,放电比容量最高,循环性能最好。在电压范围3.0~4.3 V和0.1 C倍率下,其首次放电比容量为119 mAh/g,经过15次循环后其放电比容量为118.7 mAh/g,容量保持率为99.7%。
Abstract:
Lithium vanadium phosphate（Li3V2（PO4）3） has become a potential and promising lithium ion battery cathode material due to its high energy density,good structural stability,safety performance and low temperature performance.The Li3V2（PO4）3/C samples were synthesized by carbothermal reduction method from ball-milling mixture of stoichiometric LiOH·H2O,V2O5,NH4H2PO4 and citric acid.The effects of calcination temperature and time on the structure and electrochemical properties of Li3V2（PO4）3 cathode materials were investigated by XRD and galvanostatic charge/discharge measurement.The optimum calcination process parameters for monoclinic Li3V2（PO4）3 cathode materials with excellent performances were obtained by several experiments.The results show that the Li3V2（PO4）3/C sample synthesized at 850 ℃ for 10 h has the most stable structure and the best electrochemical properties,respectively with the discharge capacity of 119 mAh/g for initial cycle and 118.7 mAh/g after 15 cycles,at 0.1 C and 3.0 ～ 4.3 V.The retention rate of discharge capacity is about 99.7%.
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