Optimization of Li-Excess content on the performance of Lix(Ni0.3Mn0.5Co0.2)O2 cathode materials in Li-ion battery

In this study, the effect of excess lithium content on lithiated cathode in lithium ion battery and non-stoichiometric state has been investigated. For this purpose, the precursor was compounded with co-precipitation synthesized Ni0.3Mn0.5Co0.2 and subsequently lithiated with different amounts of LiOH to investigate the effect of excess lithium content on the Lix (Ni0.3Mn0.5Co0.2) O2 cathode. The results of ICP, XRD and SEM analysis showed that the samples were well synthesized and the compositions were layered and the particle size in the samples was less than 10 microns. The results of battery charge-discharge tests for all three samples at 0.5-5C showed that the sample of Li1.5 (Ni0.3Mn0.5Co0.2) O2 had the best electrochemical performance; such that at 1C discharge rate its capacity 200mAh/g and after 30 cycles, its capacity reached 138mAh/g at 5C discharge rate. The impedance analysis (EIS) revealed that the sample of Li1.5 (Ni0.3Mn0.5Co0.2) O2 had the lowest internal resistance. Finally, it can be concluded that increasing the amount of excess lithium has the optimum value for improving the battery performance, so that in non-stoichiometric mode, the increase of lithium up to Li1.5 is associated with improved performance and above this level will result in reduced battery performance.