半水溶剂热法合成LiFePO_4及其性能研究

Synthesis of LiFePO_4 by semi-aqueous thermal method and its performance

采用半水溶剂热法合成了亚微米级LiFePO4,X射线衍射分析发现溶剂对LiFePO4的晶型结构没有影响。对材料进行扫描电镜分析和充放电循环性能测试表明,有机溶剂的加入使得材料颗粒形貌更加规则,粒径更小,从而提高了材料的电化学性能。其中以丙三醇和水作为混合溶剂制备出的LiFePO4颗粒粒径最小,平均粒径达到200 nm,其电化学性能最佳。在0.1 C下的放电比容量为155 mAh/g,10 C达到103 mAh/g,20 C时仍有75 mAh/g,且循环稳定性良好。

The submicron-sized LiFePO4 was synthesized by semi-aqueous solvent thermal method. The XRD analysis of the samples shows that solvent has no effects on the structure of LiFePO4. The SEM and charge-discharge cycle performance tests indicate that： the addition of organic solvent makes the sample＇s morphology more regular and particle size smaller, thus enhances the discharge capacity of the samples rapidly. The sample made by glycerol-water as mixed solvents has the smallest particle size, with the average size of 200 nm. Furthermore, it also exhibits the best electrochemical performance, and the discharge specific capacity can reach 155 mAh/g at 0.1 C rate, keep 103 mAh/g even at a high current density of 10 C, and still maintain 75 mAh/g at 20 C, with an excellent cycle stability.