Recycling of Lithium-Ion Batteries: Effect of Hydrogen Peroxide and a Dosing Method on the Leaching of LCO, NMC Oxides, and Industrial Black Mass

Abstract

The effect of hydrogen peroxide on the leachability of different reference cathode active materials used in lithium-ion batteries (LCO, NMC 111, NMC 622, and NMC 811) was investigated using 2 M H2SO4. An innovative method was used to monitor the consumption and residual concentration of hydrogen peroxide, which can help optimize its addition and improve the economy and resource yield of the process. The reducing effect of hydrogen peroxide was compared using two methods of adding it. Leaching with hydrogen peroxide significantly improved the dissolution and 100% yield was reached within 15 min for the NMC oxides (except NMC 811) and within 30 min for LCO. Co and Ni were more easily leached from NMC 811 compared to other NMC oxides. The dissolution of metals from LCO was in general slower. Cu and Al can also act as reducing agents and their presence increased the leaching yield of the transition metals, especially Mn, and resulted in less residual hydrogen peroxide. The H2O2 addition method (all at once or charged at multiple occasions) did not influence the maximum leachability (except for Mn/NMC 811) or the amount of consumed hydrogen peroxide, but the rate of dissolution was slower when charging at multiple times. The optimal conditions determined for the reference NMC 111 cathode material [3% v/v H2O2 (59% w/w), S/L 1:20 g/mL, 2 M H2SO4, 50 °C] were applied for an industrial black mass sample (Li1.09Ni0.31Mn0.39Co0.39O2). The result was 100% yield for Li, Mn, and Ni, after 15 min and 100% yield for Co after 60 min.