Preparation and process optimization of LiNi0.5Co0.2Mn0.3O2 as cathode material for high capacity lithium-ion battery

Abstract:

The precursor Ni_0.5Co_0.2Mn_0.3(OH)₂ is synthesized by hydroxide co-precipitation method, further high temperature solid state method is used to obtain the LiNi_0.5Co_0.2Mn_0.3O₂ by mixing with lithium source. The quality change of the precursor and lithium source during the high temperature calcination process and the effect of calcination process on the structure and properties of materials are discussed. Thermal gravimetric analysis (TGA) shows that there is little change in the material quality during the calcination process after 750℃. X-ray diffraction (XRD) indicates that all samples, which are synthesized from 750℃ to 900℃, have good α-NaFeO₂ layered structure and small cation mixing degree. Scanning electron microscope shows that the material has a smooth surface and a uniform distribution of spherical structure. The material, calcined at 850℃, shows a initial discharge capacity of 193.7mA.h.g_-1 in the voltage range of 2.5?4.6V at 25℃ and 0.2C, with the capacity retention rate of 94.2% after 30 cycles, which delivers the best electrochemical properties, including the rate capability.

Key words:Lithium ion battery; calcination temperature; LiNi_0.5Co_0.2Mn_0.3O₂; Synthesis technology