Direct upcycling of spent lithium-ion battery cathodes to efficient water oxidation catalysts

Addressing the dual challenges of sustainable energy conversion and battery waste management, this work develops a mechanochemistry-assisted strategy to upcycle spent lithium-ion battery cathodes. The approach directly converts them into highly efficient oxygen evolution reaction (OER) catalysts. Through controlled reconstruction, the cathode material becomes a defect-rich transition metal hydroxide phase with abundant charge transfer states. The resulting catalyst shows excellent OER performance, which achieves a low overpotential of 253 mV at 10 mA cm⁻²_geo and maintains high stability in alkaline media. In situ Raman and X-ray absorption spectroscopy reveal that the high activity comes from dynamically formed NiOOH species during operation condition. Meanwhile, the stable Co/Mn coordination and inherent defects ensure long-term durability. Compared with conventional Ni(OH)₂, the restructured catalyst exhibits better structural integrity under prolonged operation. This study presents a novel strategy for battery reclamation and the design of cost-effective, high-performance electrocatalysts for water splitting.