Sustainable Regeneration of Spent Layered Lithium Nickel Cobalt Manganese Oxide Cathode from Scrapped Lithium-ion Battery

Abstract

The ever-growing markets for electric vehicles would produce tremendous scrapped lithium-ion batteries (LIBs) in near future, which inevitably brings severe environmental hazards and mineral resources challenges. Sustainable recycling of the scrapped LIBs is a promising route for addressing these intractable issues and has also become an urgent task. As one of the prevailing cathode materials, the spent lithium nickel cobalt manganese oxides (LiNixCoyMnzO2, x+y+z=1) possess much significant recycling value because of their enriched transition metal elements. Recent years, some methodologies have been frequently proposed for recycling the spent LiNixCoyMnzO2 cathodes, including the hydrometallurgical, pyrometallurgical and direct regeneration approaches. Thereinto, the direct regeneration that represents the most advanced technique is capable of healing the spent cathodes without destroying the original microstructures, considerably reducing the secondary wastes and cost. Herein, we aim at pushing forward the technical progress of the direct regeneration strategy for spent LiNixCoyMnzO2 cathodes through a comprehensive and systematical review. The microstructure and degradation mechanism of layered LiNixCoyMnzO2 cathodes are first studied. Then, the advances of various direct regeneration strategies that are classified by the relithiation steps are detailly described and plenarily discussed. The existing deficiencies and possible solutions are also proposed to give a guidance future recycling industry.