Improved electrochemical performance at high rates of LiNi0.6Co0.2Mn0.2O2 cathode materials by pressure-treatment

Abstract

Layered LiNi0.6Co0.2Mn0.2O2 (NCM 622) cathode materials were synthesized through spray-drying method with different pressure treatments (0, 2, 3, 4 ​MPa). The results of XRD and XPS showed that the LiNi0.6Co0.2Mn0.2O2 with 3 ​MPa treated presented lower level of cation mixing. And it also led to the increase of lithium interlayer spacing and the decrease of transition metal interlayer slab. It exhibited high specific capacity of 168 ​mA ​h g-1 at 0.5 ​C and 130 ​mA ​h g-1 at 10 ​C. After 150 cycles at 10 ​C, the retention also maintained above 85.1%. The sample treated with 3 ​MPa possessed superior lithium-ion diffusion ability and lithium ion diffusion coefficient were nearly three times than that of the untreated sample. The results illustrated that pressure-treatment was a practical approach for LiNi0.6Co0.2Mn0.2O2 cathodes to improve the electrochemical performance.