关键词: 锂离子电池, 正极, 复合材料, 高电压, LiNi_0.4Co_0.1Mn_1.5O₄

Abstract:

LiNi_0.5Mn_1.5O₄(LNMO) is a promising cathode material for the next generation of high energy density lithium ion batteries. However, the serious manganese ion dissolution and rapid capacity degradation impede their practical application. Here, ternary spinel type high voltage cathode material LiNi_0.4Co_0.1Mn_1.5O₄(LNCMO) was synthesized by hydrothermal-calcination method. The calcination temperature and heating rate were optimized and investigated. The sample was uniform rhomboid-like morphology feature with pure structure. The specific surface area of the sample was 3.72m²/g and the average pore size was 11.60nm. The discharge voltage of LNCMO was close to 4.75V, and the initial specific capacity was about 143.90mAh/g, which was close to the theoretical specific capacity of LNCMO(146.70mAh/g). According to the XRD and XPS results, the proportion of Mn⁴⁺ was higher than that of Mn³⁺ in this sample. At the same time, appropriate calcination temperature and heating rate could avoid the formation of Li _x Ni_1-x O impurity phase, and thus the structural stability was higher, the charge transfer resistance was lower and the electrical performance was better of this sample. Comparing the XRD and SEM results of cathode materials before and after the cycle, the phase was basically the same, but the morphology and structure collapse was serious under high current density, which limited the cycle stability. This paper provided an effective strategy for preparing ternary high voltage materials for higher capacity and discharge voltage.

Key words: lithium ion battery, cathode, composites, high voltage, LiNi_0.4Co_0.1Mn_1.5O₄