锂离子电池正极材料锰酸锂的改性研究

Modification of lithium manganate as cathode material for lithium ion batteries

用氟化锂对预先合成的锰酸锂(LiMn2O4)进行氟化处理,研究了处理温度对材料电化学比容量与高温下循环稳定性的影响。结果表明,氟化锂/锰酸锂混合体系在500℃以上开始反应,所形成材料的特性发生了明显的变化;氟化锂处理可以改善锰酸锂材料的结晶度,热处理温度越高,处理后材料的结晶度越好;随着处理温度的升高,锰酸锂材料经历了从"烧结型"到"结晶型"的转变,700℃以上烧结的材料形成了八面体的晶体颗粒;初始比容量与循环性能也随着处理温度的不同而变化,600℃条件下处理的材料初始比容量最低,但循环性能最好。

Presynthesized lithium manganate （LiMn2O4 ） was mixed with lithium fluoride （LiF） for fluorination. Influence of treatment temperature on material＇s electrochemical specific capacity and cycling stability at high temperature was studied. Results showed that mixture of LiF/LiMn2O4 started to react at above 500℃, and properties of the treated materials changed substantially. LiF treatment could improve crystallization of LiMn2O4 material, and the higher was the treating temperature, the better was crystallization of the material. Morphology of the materials changed from ＇ sintered ＇ type to ＇ crystallized ＇ type with the increasing of temperature, and product obtained at over 700℃showed octahedral crystallite. Initial capacity and cycling stability of the materials also changed with treating condition, and the treated material at 600℃ had the lowest initial capacity but the best cycling stability.