均匀沉淀法制备LiFePO4/C及其电化学性能

摘要

以FeSO4·7H2O、H3PO4、H2O2和尿素为原料,采用均匀沉淀法制备LiFePO4的前驱体FePO4·xH2O,研究表面活性剂PEG对前驱体FePO4·xH2O形貌的影响.并将获得的FePO4·xH2O与Li2CO3及葡萄糖混合后合成LiFePO4/C.利用XRD、SEM、循环伏安测试、电化学性能测试、交流阻抗测试等手段对LiFePO4/C进行表征.结果表明:当不添加表面活性剂PEG时,FePO4·xH2O颗粒呈球形,但团聚现象严重:添加PEG后,颗粒较分散,形貌为多面体,合成的LiFePO4/C在0.1C时的首次放电比容量为151.0 mA·h/g,倍率性能好,振实密度达1.44g/cm3.%FePO4 xH2O precursor was synthesized by the homogenous precipitation method from FeSO4-7H2O, H3PO4, H2O2 and urea. The influence of surfactant PEG on the morphology of FePCyxH2O was studied. The LiFePCVC composites were synthesized with the as-prepared FePO4j:H2O, Li2CO3 and glucose as raw materials. The performance of LiFePOyC was characterized by XRD, SEM, cyclic voltammograms (CV), electrochemical performance and electrochemical impedance spectroscopy (EIS) tests. The results show that FePO4xH2O synthesized without surfactant PEG has spherical shape, but serious reunion phenomenon. The particles of FePO4xH2O synthesized with surfactant PEG disperse well and have polyhedron shape, the discharge specific capacity of LiFePCyC is 151 mA-h/g at 0.1C, showing good rate performance. The tap density reaches 1.44 g/cm3.