Upcycling Low-Nickel Li_xNi_0.5Co_0.2Mn_0.3O₂ (0<x<1) Scraps Toward High-Performance Single-Crystal Ni-Rich Cathodes

Lithium-ion battery manufacturing generates ≈335 000 tons of cathode material scrap annually, corresponding to an 8-10% process loss. Recycling this scrap is as crucial as recovering end-of-life batteries to achieve sustainable green cycling. However, current research has not sufficiently investigated the electrochemical degradation mechanisms of cathode materials following prolonged air exposure. Moreover, existing methods face challenges in directly regenerating heterogeneous scrap mixtures with diverse particle size distributions. In this study, multiscale characterization techniques are employed to systematically elucidate the degradation mechanisms of cathode scrap across various particle sizes during prolonged air exposure. A simple strategy is proposed, combining mechanical activation pretreatment with stoichiometric compensation via homogeneous liquid-phase Li/Ni/Co supplementation, to transform low-nickel mixed-phase Li_1-xNi_0.5Co_0.2Mn_0.3O₂ scrap (S-NCM523) into Ni-rich single-crystal Li_1.01Ni_0.8Co_0.1Mn_0.1O₂ particles (U-NCM811), featuring a gradient Ni distribution. Upcycled U-NCM811 delivers a high specific capacity of 202 mAh g^-1 at 0.1C, retaining 80.7% capacity after 200 cycles at 1C and 79.4% capacity at 5C, thereby outperforming the capacity of commercial single-crystal NCM811. Techno-economic analysis results confirm that the proposed strategy yields a seven-fold higher net profit than conventional methods. Overall, this strategy establishes a universal sustainable circular economy model for battery scrap.