Direct preparation of efficient catalyst for oxygen evolution reaction and high-purity Li₂CO₃ from spent LiNi_0.5Mn_0.3Co_0.2O₂ batteries

The recovery of waste lithium-ion batteries (LIBs) is an intensively studied worldwide because of environmental pollution and the risk of undersupply of a strategic raw material. Traditional technologies have poor selectivity for lithium recovery from waste LIBs. Metallic Ni, Co, and Mn are usually recovered by leaching, precipitation, and solvent extraction. These recycling methods are costly and have a long recycling route and high potential for secondary waste generation. In this paper, a mechanochemical activation approach was proposed for the selective recycling of lithium and recovery of Ni_0.5Mn_0.3Co_0.2(OH)₂ from spent LiNi_0.5Mn_0.3Co_0.2O₂ batteries. The leaching efficiency and Li selectivity were found to be 95.10% and 100%, respectively. The structure of Ni_0.5Mn_0.3Co_0.2(OH)₂ was investigated using various characterisation techniques. The selective reaction mechanism of mechanochemical activation was identified. High-purity Li₂CO₃ (99.96 wt%) was obtained. Electrochemical tests showed that the performance of Ni_0.5Mn_0.3Co_0.2(OH)₂ was comparable to that of a commercial oxygen evolution reaction catalyst (IrO₂). This research demonstrates an effective and shorter route from waste to a functional material during recycling spent LIBs that incorporates the principles of green chemistry and shows great potential for practical application.