利用控制结晶法制备了粒径约为1、5、10μm球形FePO4,以此为前驱体通过碳热还原法合成不同粒径的球形LiFePO4正极材料.采用XRD、SEM以及恒流充放电测试等手段对材料的结构、形貌和电化学性能进行表征,并比较了不同粒径产物的振实密度.合成的材料较好地保持了球形形貌,大粒径的样品振实密度高达2.03 g/cm3,但电化学性能不佳.小粒径的样品不同倍率下质量比容量最优,0.1C下达160.6mAh/g;中粒径的样品具有较高的体积比容量,0.1C下为230.4mAh/cm3.大倍率下小粒径与中粒径的样品之间的体积比容量差距越来越小,说明随着充放电倍率的增加,锂离子扩散速率已成为控制步骤,因此需要根据实际的使用环境选择最合适的LiFePO4材料.
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