Mechanical Homogenization Promoting Dual‐Directional Upcycling of Layered Oxide Cathodes

Abstract Upcycling is regarded as a sustainable and promising recycling solution for spent lithium‐ion batteries (LIBs). However, current upcycling strategies such as converting Ni‐lean to Ni‐rich cathodes struggle to change the composition of the spent cathodes to meet the diverse market demands. In addition, the commonly employed molten‐salts method requires tens of hours of high‐temperature treatment, restricting its sustainability. Herein, this study reports an efficient, flexible dual‐directional upcycling strategy to upcycle a broad family of layered oxide cathodes into fresh LiNi x Co y Mn z O 2 (NCM) cathodes with tailored Ni‐contents—either increased or decreased—in just 4 h via mechanical homogenization pretreatment. This study confirms that the bulk diffusion of transition metals (TMs) is the rate‐determining step in the resynthesis process, and the mechanical homogenization can shorten the diffusion pathway of TMs, thus reducing the sintering duration effectively. The as‐upcycled NCM cathodes can deliver electrochemical performance on par with commercial counterparts. Notably, a systematic technoeconomic analysis shows that upcycling spent LiCoO 2 into NCM622 can yield a profit up to 35 US$/kg, 30% higher than the conventional acid‐leaching resynthesis approach. This work provides an energy‐saving, widely adaptable, flexible, and cost‐efficient method for regenerating spent cathode materials, paving the way for the sustainable recycling of LIBs.