水热法制备LiMnPO_4包覆的LiMn_2O_4正极材料及其改善的电化学特性

Improvement of Electrochemical Properties of LiMn_2O_4 Cathode Material by LiMnPO_4 Coating via Hydrothermal Method

通过水热合成的方法制备了不同质量百分比的LiMnPO4包覆LiMn2O4的复合材料,并且利用XRD、拉曼光谱、SEM、TEM以及充放电测试等手段,对其结构和电化学性能进行了表征。研究表明,适当量的LiMnPO4包覆,不仅可以增加材料的可逆比容量,还可以有效提高材料在55℃下的循环特性。1wt%LiMnPO4包覆的LiMn2O4在55℃下的可逆容量为109 mAh.g-1,是其初始容量的96%。此外,1wt%LiMnPO4包覆的LiMn2O4与未包覆的LiMn2O4相比,在倍率特性上也有明显的改善。

LiMnPO4 coated LiMn2O4 with different contents were prepared via hydrothermal method, and their structural and electrochemical properties were characterized by XRD, Raman, SEM, TEM and charge-discharge test. Generally, the modification of LiMnPO4 on the surface of the LiMn2O4 could not only increase the reversible capacity, but also upgrade its cyclic performances when cells were operated at 55 ℃. In the case of the 1wt% LiMnPO4 coated LiMn2O4, its reversible capacity is about 109 mAh·g^-1 when cell was operated at 55 ℃, which is about 96% of its initial capacity. Moreover, 1wt% LiMnPO4 coated LiMn2O4 exhibits an improved rate capability compared with that of the bare LiMn2O4.