Direct recovery: A sustainable recycling technology for spent lithium-ion battery

The ever-growing amount of lithium (Li)-ion batteries (LIBs) has triggered surging concerns regarding the supply risk of raw materials for battery manufacturing and environmental impacts of spent LIBs for ecological sustainability. Battery recycling is an ideal solution to creating wealth from waste, yet the development of battery recycling technologies awaits considerable effort. Recently, direct recovery for spent LIBs makes the closed-loop circulation of electrode materials due to the direct use of degraded active materials as raw materials to produce fresh active materials. Thus its underlying sustainability of using less chemical agents and energy cost has increasingly acttracted attentions from battery community. In this review, we summarized a series of steps including separation pretreatment, precise relithiation and defect restoration that are executed sequentially for the regeneration of reycled electrode materials. More importantly, we specifically integrates the degradation mechanisms and regeneration strategies of different battery materials in order to reveal the influence of the degradation mechanism of electrode materials on the selection of regeneration strategies. The direct regeneration is to some extent a reversible process of structural decay for electroactive materials. Finally, perspectives are given to facilitate the uptake of direct recovery in practices.