锂离子电池LiFePO4/Li3V2(PO4)3复合正极材料的制备及性能研究

Preparation and properties of LiFePO4/Li3V2(PO4)3 composite cathode material for lithium-ion batteries

为了提高LiFePO4正极材料的离子导电性,采用液相共沉淀法与碳热还原法制备一系列质量配比的LiFePO4/Li3V2(PO4)3复合材料,通过X-射线衍射、扫描电镜、恒流充放电测试仪等分析测试手段测试样品。研究发现,m(LiFePO4):m(Li3V2(PO4)3)=6:4时复合材料形貌较为规则且结晶度较高,在0.1C,1.0C,2.0C,5.0C,10.0C倍率下放电比容量可达148,136,130.5,121.5,112.3 mA·h·g-1,1C倍率下循环100次容量保持率仍可达98.5%,有效地解决了LiFePO4离子电导率低的问题,推动了该复合正极材料在动力型锂离子电池中的应用。

LiFePO4/Li3V2(PO4)3 composite cathode materials with a series of mass ratios were synthesized using the liquid-phase co-precipitation method and carbon thermal-reduction process to improve the electronic conductivity of LiFePO4 cathodes.X-ray diffraction,scanning electron microscopy,constant-current charge and discharge testing,and other analytical methods were used to analyze the phase composition,morphology,and electrochemical performance of the composites.When the mass ratio of LiFePO4 and Li3V2(PO4)3 was 6:4,the composite exhibited regular morphology,higher crystallinity,and the best electrochemical performance:the discharge capacity was 148,130.5,121.5,and 112.3 mA·h·g-1 at rates of 0.1C,1.0C,2.0C,5.0C,and 10.0C,respectively,and the capacity remained above 98.5%after 100 cycles at 1C.This effectively solves the problem of low conductivity of the LiFePO4 material and will accelerate its application in power lithium-ion batteries.