Nickel electroplating for spent NCM cathodes: a multipurpose catalyst in direct recycling

초록

Regenerating degraded lithium nickel-cobalt-manganese oxide (NCM) cathodes from spent lithium-ion batteries (LIBs) remains challenging due to incomplete lattice recovery and the depletion of lithium, oxygen, and transition metals. In this study, we introduce a nickel electroplating strategy that serves multiple functions: catalyzing oxygen and nickel replenishment during regeneration, enhancing structural recovery, and forming a protective layer on the NCM surface after sintering. Electroplated nickel promotes electron transport, attracts oxygen to the surface, and fills nickel-deficient sites within the particle, contributing to the restoration of a stable layered structure. The optimized NP25NCM cathode, in which Ni0 was electrochemically plated on recycled NCM via cyclic voltammetry deposition (1 V to -2.5 V), achieved a specific capacity of 125.4 mAh g- 1 at 0.5C and retained 85.4 % capacity after 100 cycles, outperforming untreated recycled NCM (RNCM) and other samples. Structural analyses confirmed reduced cation mixing, enhanced lattice recovery, and superior lithium-ion transport kinetics, with NP25NCM exhibiting the highest lithium-ion diffusion coefficient of 5.12 x 10-14 cm2 s- 1. This strategy enhances direct recycling efficiency, offering an energy-efficient and cost-effective solution for cathode regeneration. Its scalability and adaptability provide a sustainable approach to LIB recycling, addressing key environmental and economic challenges in battery waste management.

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