LiMn2O4／Li4Ti5O12复合材料的制备与电化学性能

Synthesis and electrochemical properties of LiMn2O4/Li4Ti5O12 composite

以LiMn2O4、醋酸锂和钛酸四丁酯为原料，乙醇为溶剂，采用原位复合法制备LiMn2O4/Li4Ti5O12复合材料。采用X射线衍射分析、红外光谱、扫描电镜和电化学测试等手段对复合材料进行表征。结果表明，在LiMn2O4/Li4Ti5O12复合材料中晶态的LiMn2O4表面被无定形结构的Li4Ti5O12包覆，但Li4Ti5O12的存在并没有改变LiMn2O4的晶体结构。由于Li4Ti5O12的包覆，LiMn2O4的倍率性能和高温性能都得到显著提高：室温下2．0C放电时20次循环后LiMn2O4/Li4Ti5O12复合材料的可逆容量达到108．4mA·h/g，平均每次循环的容量损失只有0．053％；而55℃1．0C放电时，经60次循环后LiMn2O4/Li4Ti5O12的放电容量为109．9mA·h/g，平均每次循环的容量损失为0．036％。

LiMn2O4/Li4Ti5O12 composite was synthesized by in-situ composite technique using LiMn2O4, lithium acetate, tetrabutyl titanate as starting materials and was characterized by various electrochemical methods in combination with X-ray diffractometry （XRD）, infrared （IR） spectroscopy and scanning electron microscopy （SEM）. The results show that the amorphous Li4Ti5O12 is coated on the surface of crystalline LiMn2O4 to form the LiMn2O4/Li4Ti5O12 composite. The structure of LiMn2O4 does not change due to introduction of Li4Ti5O12. Coated with Li4Ti5O12, the rate capability and high temperature cyclability of LiMn2O4 are improved greatly. At room temperature, the discharge capacity of LiMn2O4/Li4Ti5O12 composite is more than 108.4 mA·h/g and the capacity loss per cycle is only 0.053% after cycling 20 times at 2.0C. While at 55 ℃, the discharge capacity of LiMn2O4/Li4Ti5O12 composite is more than 109.9 mA·h/g and the capacity loss per cycle is only 0.036% after cycling 60 times at 1.0C.