采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材料的结构形貌与电化学性能之间的关系.结果表明,在900℃下合成样品的电化学性能最好,首次放电容量达到133.0mA.h/g,经30周循环后,容量仍然保持在132.2 mA.h/g,容量保持率高达99.4%.采用恒电位间歇滴定法(PITT)和电化学阻抗谱法(EIS)测定了锂离子在LiNi0.5 Mn1.5 O4材料中的扩散系数.结果表明,在LiNi0.5Mn1.5O4材料放电过程中,在不同的电位下,锂离子扩散系数在10-10~10-11 cm2/s范围内变化.
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 was investigated.The results show that the sample synthesized at 900 ℃ has the best electrochemical performance.Its initial discharge capacity reaches 133.0 mA·h/g,and after cycled for 30 times,still maintains at 132.2 mA·h/g(capacity retention 99.4%).The chemical diffusion coefficient of Li+ ion in LiNi0.5M1.5O4 cathode material was measured by potentiostatic intermittent titration technique(PITT) and electrochemical impedance spectroscopy(EIS).The chemical diffusion coefficient of Li+ ion ranges in 10-10—10-11 cm2/s.