5 V锂离子电池正极材料LiNi0.5Mn1.5O4的合成与Li+在材料中的扩散性能

使用草酸盐共沉淀法合成了5 V正极材料LiNi0.5Mn1.5O4，研究了不同温度下合成的材料结构形貌与电化学性能之间的关系。结果表明，在900℃下合成的样品电化学性能最好，可逆放电容量达到133.0 mAh?g-1，经30周循环后，容量仍然保持在132.2 mAh?g-1，容量保持率高达99.4%。使用恒电位间歇滴定法(PITT)测定了锂离子在LiNi0.5Mn1.5O4材料中的扩散系数。结果表明，在LiNi0.5Mn1.5O4材料放电过程中，在不同电位嵌锂量不同，发生反应的氧化还原电对也不同，锂离子的扩散系数在不同的电位下也会有差别，扩散系数在10e-10 cm2?s-1~10e-11 cm2?s-1范围内变

Preparation of LiNi_(0.5)Mn_(1.5)O_4 as 5 V Cathode Materials for Lithium Ion Battery and Diffusion Performance of Li~+ in the Materials

5 V cathode material LiNi0.5M1.5O4 was synthesized via an oxalate co-precipitation method, and the relationship between the structure, morphology and the electrochemical performance of the material were investigated. The results show that the sample synthesized at 900 ℃ has the best electrochemical performance, and its reversible capacity reaches 133.0 mAh?g-1. After 30 cycles, this LiNi0.5Mn1.5O4 sample maintains a discharge capacity of 132.2 mAh?g-1 with a capacity retention rate of 99.4%. The chemical diffusion coefficient of Li-ion in LiNi0.5M1.5O4 cathode material was measured by potentiostatic intermittent titration technique (PITT). It’s found that at the different voltage point of the discharge process, the change of Li content and the redox couple is also different, thus the chemical diffusion coefficient of Li-ion is various, it ranges in 10e-10 cm2?s-1~10e-11 cm2?s-1.