真空碳热还原固相合成磷酸铁锂的正交实验

Orthogonal experiments on preparation of LiFePO_4 under carbothermal reduction method in vacuum condition

采用真空条件下的碳热还原固相方法,以Fe2O3、LiOH和P2O5为原料、活性炭为还原剂,合成了锂离子电池正极材料LiFePO4;选择真空度、原料配比、反应温度、恒温保持时间(反应时间)和升温速率等5个影响因素,设计了一组5因素4水平(L1645)的正交实验,较系统地研究了LiFePO4的合成工艺参数及电化学性能。研究结果表明:真空碳还原合成LiFePO4工艺参数因素对材料电化学性能影响的大小顺序为:反应温度>原料配比>反应时间>真空度>升温速率;反应温度控制在600～650℃时所合成的LiFePO4材料的晶体结构和电性能较好;原料LiOH、Fe2O3、P2O5和活性炭比例为1.05∶1∶1∶1.8、反应时间为12～18h、真空度控制10-1～10Pa时,所得LiFePO4材料的综合电化学性能较好。

LiFePO4 samples were synthesized under vacuum condition using Fe2O3,LiOH and P2O5 as raw material and carbon as reduction reagent. The orthogonal experiments were carried out for studying the techniques of LiFePO4synthesis and the electrochemical performance choosing vacuum, material ratio, react temperature, and react time and heating rate as the five factors. The results indicate that the sequence of the main factors affecting the electrochemical performance of LiFePO4 were react temperature, material ratio, react time and vacuum and heating rate and the reaction temperature was the most important factor affecting the electrochemical performance of LiFePO4. LiFePO4samples displays better electrochemical performance when the proportion of LiOH, Fe2O3, P2O5 and carbon is 1.05∶1∶1∶1.8, the reaction temperature is 600-650 ℃, the reaction time is 12-18 h, and the vacuum pressure is 10-1-10 Pa.