Alkali Metal Salt Catalyzed Carbothermic Reduction for Sustainable Recovery of LiCoO₂: Accurately Controlled Reduction and Efficient Water Leaching

Abstract

Recycling of spent lithium-ion batteries (LIBs) is essential for both environmental protection and natural resource conservation. Carbothermic reduction of active materials has been a research hotspot for spent LIB recycling. However, the high reaction temperature and the limited solubility of Li2CO3 in the reduced product seriously restricted its industrial application. Here, based on the catalytic effect of alkali metal salts on carbothermic reduction, a novel process that features lower reduction temperature, accurately controlled reduction products, high concentration of lithium containing solution, and facile-treated CoO product was developed. With the catalysis of 10% NaOH, LiCoO2 can be controllably reduced to Li2O and CoO through catalytic carbothermic reduction. Afterward, lithium in the reduction products can be leached by deionized water with leaching efficiency higher than 93%, leaving cobalt in the leaching residue in the form of CoO. The lithium concentration in the lixivium can be up to 14.99 g·L–1 through a three-stage cross-current water leaching. The catalytic carbothermic reduction process is more energy conserving and environmental friendly and will bring a bright prospective for sustainable recycling of spent LIBs.