不同溶剂对LiFePO4阴极材料形貌和性能的影响

本文采用水-乙二醇作为溶剂，并使用溶剂热法制备出形态规则的磷酸铁锂（LFP）材料。采用X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）对不同溶剂合成的LFP前驱体的物相及形貌进行了表征。结果表明，不同溶剂合成的LFP均为纯相，且未改变LFP的橄榄石结构。当H2O: EG=1:1时，颗粒形貌规则且排列有序。电化学测试结果表明，当溶剂为H2O: EG=1:0、H2O: EG=1:1、H2O: EG=0:1时，LFP/C在1C条件下循环100次后容量分别为141.9、145.4、127.3 mAh·g-1。当溶剂比例为H2O: EG=1:1时，容量保持率达到99%。即使在2C的放电速率下，其初始放电比容量为134.4 mAh·g-1，明显优于其他LFP/C的电化学性能。此外，研究了混合溶剂中合成LFP的材料在不同温度下的形貌形成规律及机理过程。

Effect of solvents on the morphology and performance of LiFePO4 cathode material

The LFP material with regular form was prepared by solvothermal method using water-glycol as solvent. The physical properties and morphology of LFP precursors synthesized in different solvents were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results show that LFP synthesized in different solvents is pure phase and do not alter the olivine structure of LFP. When H2O:EG=1:1, the particle morphology is regular and orderly. The electrochemically test results show that the capacity of the LFP/C is 141.9, 145.4, and 127.3 mAh·g-1 capacity after 100 cycles at 1C when it is prepared with solvent H2O: EG=1:0, H2O: EG=1:1, and H2O: EG=0:1. The retention rate is 99%, when the solvent ratio is H2O: EG=1:1. In addition, the discharge capacity of 134.4 mAh·g-1 even at a rate of 2C, which better than that of other LFP/C. Additionally, the morphology and mechanism of LFP synthesized in mixed solvents at different temperatures were studied.