Optimization of calcination temperature in preparation of a high capacity Li-rich solid-solution Li[Li0.2Ni0.18Co0.03Mn0.58]O-2 material and its cathode performance in lithium ion battery

In our previous paper [12], it has been reported that Li[Ni0.208Li0.183Co0.033Mn0.575]O-2 Li-rich solid-solution layered oxide (LLO) cathode (Li2MnO3 (55%) - LiNi0.5Mn0.5O2 (35%) - LiNi1/3Co1/3Mn1/3O2 (10%)) possesses the best performance as cathode material among the examined LLO cathode materials of Li2MnO3-LiCo1/3Ni1/3Mn1/3O2-LiNi0.5Mn0.5O2 for lithium ion battery. In order to further improve its cathode performance, the calcination temperature was optimized in the range of 800-1100 degrees C. The cathode performance such as discharge capacity, discharge capacity retention and rate capability was improved with increasing the calcination temperature from 800 to 1000 degrees C, the best performance was obtained at 1000 degrees C and at more than 1000 degrees C, the cathode performance was degraded. The structural analysis with transmission electron microscope (TEM) and Rietveld analysis of XRD patterns indicated that the cation mixing between Li+ ions on the 3a site and Ni2+ ions on the 3b site of the layered oxide structure (R-3m) is reduced significantly in the case of the LLO calcinated at 1000 degrees C, resulting in the improvement of cathode performance. In addition, the other LLOs having different compositions were also prepared at different calcination temperatures and their cathode performance was tested. The discharge capacity of Li[Ni0.208Li0.183Co0.033Mn0.575]O-2 was found to be the highest among all the LLOs examined in this study. (C) 2018 Elsevier Ltd. All rights reserved.