Direct Recycling of Degraded Ni-Rich Cathodes: Recent Advances in Regeneration and Upcycling

Sustainable end-of-life management is crucial for widely used lithium-ion batteries (LIBs), particularly those employing high-energy and expensive nickel-rich layered oxides (NRLOs). Unlike other cathode active materials, NRLOs face higher production costs and exhibit more complex, severe degradation—including phase evolution, stoichiometric imbalance, surface contamination, and morphological damage—necessitating the development of efficient and high-value recycling technologies. Direct recycling including direct regeneration and direct upcycling offers promising closed-loop solutions specifically tailored to address these intricate structural and chemical changes. Regeneration restores original performance, while upcycling enhances properties through methods like compositional tuning, morphological control, doping, and surface engineering. This review uniquely contextualizes recent advances in the direct recycling of NRLO by linking degradation analysis with recovery strategies. Despite significant progress, practical challenges in impurity management, process complexity, scalability, and economics remain. The discussion highlights future perspectives for developing efficient and sustainable NRLO direct recycling technologies.