锂离子电池复合正极材料Li1+x(Mn0.6Ni0.2Co0.2)1−xO2(0≤x≤0.3)中锂含量对电化学性能的影响

摘要

为了确定具有固定比例的富锂锰基(Mn:Ni:Co=0.6:0.2:0.2)正极材料中的最优锂含量,制备了Li1+x(Mn0.6-Ni0.2Co0.2)1?xO2(x=0,0.1,0.2,0.3)复合物正极材料.XRD测试表明,富锂锰基复合材料具有典型的空间R3m和C2/m层状复合结构.SEM观察表明,颗粒粒度在0.4~1.1之间,并且粒度随锂含量的增加而增大.Li1.2(Mn0.6-Ni0.2Co0.2)0.8O2具有较好的首次放电容量,在电流密度为20 mA/g,电压为2.0~4.8 V下,其首次放电容量为275.7 mA·h/g.然而Li1.1(Mn0.6Ni0.2Co0.2)0.9O2表现出较好的循环性能,在0.2C、50次循环后,容量保持率为93.8%,在反应动力学中具有较好的锂离子脱嵌能力.%In order to confirm the optimal Li content of Li-rich Mn-based cathode materials (a fixed mole ratio of Mn to Ni to Co is 0.6:0.2:0.2), Li1+x(Mn0.6Ni0.2Co0.2)1?xO2 (x=0, 0.1, 0.2, 0.3) composites were obtained, which had a typical layered structure with R3m and C2/m space group observed from X-ray powder diffraction (XRD). Electron microscopy micrograph (SEM) reveals that the particle sizes in the range of 0.4?1.1μm increase with an increase ofx value. Li1.2(Mn0.6Ni0.2Co0.2)0.8O2 sample delivers a larger initial discharge capacity of 275.7 mA·h/g at the current density of 20 mA/g in the potential range of 2.0?4.8 V, while Li1.1(Mn0.6Ni0.2Co0.2)0.9O2 shows a better cycle performance with a capacity retention of 93.8% at 0.2C after 50 cycles, showing better reaction kinetics of lithium ion insertion and extraction.