Residual Li Compounds-Selective Washing Process for Ni-Rich Layered Oxide Cathode Materials for Li-Ion Batteries

Abstract

The industrial manufacturing process for Ni-rich layered oxides for Li-ion batteries includes a washing step to remove residual Li compounds, such as LiOH and Li 2 CO 3, from the oxide surface. However, Ni-rich layered oxides are deformed during a conventional water-based washing process, leading to the degradation of the oxide surface. In this regard, a significant challenge for Ni-rich layered oxides is to remove residual Li compounds without surface damage during a washing process. Herein, the residual Li compounds-selective washing process is introduced as a promising strategy for LiNi 0.945 Co 0.04 Al 0.015 O 2 to suppress the degradation of the oxide surface during washing. The selectively hydrophobic LiNi 0.945 Co 0.04 Al 0.015 O 2 powders are obtained through selective coating only on the LiNi 0.945 Co 0.04 Al 0.015 O 2 surface with hydrophobic polydimethylsiloxane, leaving residual Li compounds uncoated. For this reason, the oxide surface is hydrophobic, whereas the residual Li compounds surface is hydrophilic. As a result, only residual Li compounds are selectively exposed to water and removed during washing, mitigating contact between the oxide surface and water. Eventually, this method suppresses the degradation of the LiNi 0.945 Co 0.04 Al 0.015 O 2 surface during washing, resulting in the improved electrochemical performance compared to LiNi 0.945 Co 0.04 Al 0.015 O 2 obtained through a conventional washing technique.