Li3V2(PO4)3/C复合正极材料的制备与性能

以CH3COOLi、V2O5、NH4H2PO4和碳凝胶为原料,采用溶胶-凝胶法合成了锂离子蓄电池Li3V2(PO4)3/C复合正极材料.对其前驱体和产品采用热重-差热分析(TG-DTA)、X射线衍射(XRD)以及元素分析分别进行了表征.考察了掺杂碳含量对材料充放电性能及其高倍率循环性能的影响.样品C的首次放电比容量达到128.4 mAh/g.样品B和C以0.2 C充放120次后容量几乎没有衰竭;继续以1 C充放电120次,其比容量仍基本恒定,比单一Li3V2(PO4)3材料具有更优良倍率性能和循环性能.交流阻抗测试表明碳掺杂可以形成碳包覆层,材料的电导率大幅提高,从而提高了材料的电化学性能.

Preparation and performance of Li3V2(PO4)3/C composite as cathode material for lithium ion battery

Composite cathode materials Li3V2(PO4)3/C were synthesized by sol-gel method with CH3COOLi, V2O5, NH4H2PO4 and C gel as the raw materials. The precursor and product were characterized by differential thermal-analysis thermogravimetry (TG-DTA), X-ray diffraction (XRD) measurements. Electrochemical properties of samples, changed by substitution of carbon, were investigated by charge-discharge cycle at different current densities. The first discharge capacity of the sample C was 128.4 mAh/g. After charge-discharge at 0.2 C rate for 120 cycles, the sample C retained a discharge specific capacity of 127.9 mAh/g, and its capacity seems to be constant during the later 120 cycles at 1 C rate, which showed a better cycle performance than pure materials of Li3V2(PO4)3. The results of electrochemical impedance spectroscopy (EIS) show that the coated carbon enhances the conductivity and electrochemical performance of materials.