Sustainable regeneration of a spent layered lithium nickel cobalt manganese oxide cathode from a scrapped lithium-ion battery

Abstract

The ever-growing market of electric vehicles is likely to produce tremendous scrapped lithium-ion batteries (LIBs), which will inevitably lead to severe environmental and mineral resource concerns. Directly renovating spent cathodes of scrapped LIBs provides a promising route to address these intractable issues and has become an urgent task. Spent lithium nickel cobalt manganese oxides (LiNi_xCo_yMn_zO₂), one of the prevailing cathodes, exhibit more significant recycling value because of their enriched transition metal elements, and numerous research studies on direct regeneration strategies have been recently published. It is therefore highly critical and important to timely summarize the existing recycling strategies for spent LiNi_xCo_yMn_zO₂ cathodes for pushing forward the technical progress to the next stage, but such a summary is absent and nonsystematic. Herein, a comprehensive review focusing on the direct regeneration of spent LiNi_xCo_yMn_zO₂ cathodes is provided. The microstructure and degradation mechanism of layered LiNi_xCo_yMn_zO₂ cathodes are first studied, which is a prerequisite to design rational regeneration approaches. Next, the advances of various recycling strategies that are classified on the basis of relithiation steps are described in detail and comprehensively discussed. Lastly, the existing deficiencies and possible solutions are proposed to give guidance to the future recycling industry.