Effect of solution wash on the electrochemical performance of LiNi0.8Co0.1Mn0.1O2 cathode materials

Abstract

Solution wash is a key procedure in the recycling of cathode materials for lithium-ion batteries. It is well-known that Ni-rich ternary cathode material LiNi0.8Co0.1Mn0.1O2 (NCM-811) is sensitive to water, triggering the Li+/H+ exchange and increasing the cation disorder, which ultimately leads to a large capacity loss during the battery cycling. In this study, we investigated the structural/surface chemical stability as well as the capacity loss for NCM-811 ternary cathodes after washing in five different environmentally friendly and commercially available solutions (i.e., ethanol, methanol, sodium chloride aqueous solution, sodium hydroxide aqueous solution, and deionized water). It is discovered that the capacity decay rate during cycling is closely related to the Li+ ion loss after solution wash, the more the Li+ ion loss, the quicker the capacity decay during cycling. Among all the solution-washed samples, ethanol-washed samples show minimal Li+ ion loss and the best capacity retention. Where the Li+ ion loss is only 2%, and the specific capacity after 200 cycles is 2.6 times higher as compared to the water-washed counterparts. This study paves the way towards the practical applications of ethanol in the commercial recycling of NCM-based cathodes.