锂离子电池正极材料Li_3V_2(PO_4)_3-MCNTs的合成及电化学性能

Research on lithium-ion battery cathode material Li_3V_2(PO_4)_3/MCNTs synthesis and electrochemical performance

采用溶胶凝胶一固相法制备LijV2（P04）3-MCNTs复合材料，并研究了多壁碳纳米管（MWCNTs）对其物理性能及电化学性能的影响。采用X射线衍射光谱法（XRD）、扫描电子显微镜法（SEM）和热重分析法（TGA）对其晶型结构、形貌特征等物理性能进行了表征；采用循环伏安、交流阻抗、恒流充放电测试等方法对其电化学性能进行了测试。研究发现。磷酸钒锂在800oc高温处理后为单斜结构，三维网络结构MWCNT负载磷酸钒锂[Li3V2（P04）3-MCNTs]复合材料具有良好的电化学性能。在充放电倍率为0．1C。电压窗口为3～4．4V时首次放电比容量为130．5mAh／g，库仑效率为99.7％。倍率性能测试显示。在0．5C、1．0C、2C下，Lj3V2（PO4）3/VICNTs仍保持优越的循环稳定性。由此可见，Li3V2（P04）3-MCNTs复合材料对正极材料的容量、倍率性能及循环稳定性都具有明显影响。

Monoclinic Li3V2（PO4）3 cathode materials were synthesized by sol gel-solid phase method, precursor was ultrasonic dispersion with the MWCNTs and Acetylene Black separately, which was obtained by sol-gel method. The effect of MWCNTs on the performance of synthesized cathode materials was investigated. The crystal structure and the electrochemical performance were characterized by XRD, FE-SEM, TG/DGA and electrochemical performance testing. The results show that the cathode material synthesized with MWCNTs is the most excellent electrochemical performances due to the MWCNTs with three-dimensional net structure. The initial discharge specific capacity was 130.5 mAh/g in the voltage range of 3.0-4.4 V at 0.1 Crate, coulomb efficiency was 99.7%, even at 0.5 C, 1.0 C and 2 C rates, excellent electrochemical performance was also exhibited.