An Effective Method to Reduce Residual Lithium on LiNi_0.8Co_0.1Mn_0.1O₂ Cathode Material Using a Reducing Agent

Among the various cathode materials used in LIBs (Lithium ion batteries), nickel rich cathode materials have attracted an increasing amount of interest due to their high capacity, relatively low cost, and low toxicity when compared to LiCoO₂. However, these materials always contain a large amount of residual lithium compounds such as LiOH and Li₂CO₃. The presence of lithium residues is undesirable because the oxidation of these compounds results in the formation of Li₂O and CO₂ gas at higher voltages, which lowers the coulombic efficiency between the charge and discharge capacities during cycling. In this study, using LiNi_0.8Co_0.1Mn_0.1O₂ as a starting material, a surface-modified cathode material was obtained by using reducing agent. The reducing agent not only plays the role of reducing the oxide conversion energy but also suppresses the side reaction with the electrolyte due to the surface modification. Residual lithium present on the cathode material surface was reduced from 11,702 ppm to 8,658 ppm, resulting in improved high temperature cycle performance and impedance characteristics.