LiFePO4／石墨烯纳米复合材料的制备与化学性能研究

摘要

LiFePO4/graphene( GR) electrode materials were synthesized by a solvothermal approach using EtOH/H2 O as a solvent and oleic acid( OA) as a surfactant.LiFePO4/GR nano composite electrode materials were prepared by ball milling method.Effect of GR on microstructure and electrochemical performances of LiFePO4/GR composite electrode materials have been investigated using X⁃ray diffraction ( XRD ) , scanning electron microscopy ( SEM ) and transmission electron microscopy ( TEM ) , electrochemical impedance spectroscopy ( EIS) and cyclic voltammetry ( CV) measurements.The results show that all the samples have the crystal structure of olivine.In addition, the ball⁃milling is an effective method to reduce the particle size of LiFePO4 electrode materials, the particles of synthesized LiFePO4/GR composite electrode materials are about 50 nm with 5% GR.Coating GR by ball⁃milling could further improve the maximum discharge capacity and the dynamics performance with lower charge transfer resistance.%在EtOH／H2 O溶剂体系中，以油酸为表面活性剂，合成了橄榄石型结构的LiFePO4锂离子电池正极材料，采用球磨方法获得石墨烯（ GR）处理的LiFePO4／GR纳米复合电极材料，并通过XRD、SEM、TEM、EIS以及CV等方法研究了LiFePO4／GR纳米复合电极材料的微观结构和电化学性能。微观结构分析表明LiFePO4均具有橄榄石型结构，表面活性剂油酸可有效调控LiFePO4晶胞参数，抑制样品的团聚；通过球磨技术可获得分散均匀的LiFePO4／GR纳米复合材料，粒径约为50 nm。测试结果表明，LiFePO4／GR纳米复合材料的最大放电容量、动力学性能得到提高和改善，电荷转移电阻显著减小。