Recovery of valuable metals from LiNixCoyMnzO2 and LiFePO4 mixed leachate based on thermodynamic calculations and experimental optimization

The development of recycling processes for spent lithium-ion batteries had become a key factor for the sustainable development of the new energy vehicle industry due to their environmental risks and resource availability. This article presented a thermodynamic analysis of the synergistic leaching solution system and its subsystems of LiNi x Co y Mn z O 2 and LiFePO 4 lithium-ion battery cathode powders. Based on thermodynamic analysis, deep synergistic removal of Fe/P was achieved through solution regulation. The removal rate of Fe/P was close to 100 %, while the loss rate of metals such as Ni, Co, Mn, and Li was less than 1 %. The obtained Fe/P slag was subjected to hydrothermal recrystallization treatment, and battery grade FePO 4 ·2H 2 O was obtained through condition optimization. Subsequently, selective precipitation of Cu 2+ was achieved by controlling the pH of the solution and the amount of Na 2 S 2 O 3 added. The concentration of Cu 2+ was reduced to below 10 ppm while the loss rate of major metals was below 0.2 %. Finally, Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 was obtained from the deep purification solution through co-precipitation, achieving the separation of transition metals from Li + . The entire process ensured that the total loss rate of major metals was less than 1 % while obtaining high value-added products, providing technical and theoretical support for the gradient separation of major metal ions in the leachate.