Upcycling spent lithium-ion cathodes into gradient electrocatalysts for seawater electrolysis

There will be a rapid rise in manufacture and use of lithium-ion batteries (LIBs), largely driven by the electrification of transport, such as electric vehicles. However, end-of-life LIBs will pose major resource and environmental challenges without low-cost, effective recycling. Herein, we report an economically feasible kilogram-scale upcycling strategy to convert spent LIB cathode materials into NiCoMnFeP (NCMFP) electrocatalysts. These nanoparticles self-assemble into a gradient architecture, boosting stability in harsh direct seawater electrolysis, with an ultra-low oxygen evolution reaction (OER) overpotential increase rate (OIR) of 1.27 × 10 −4 V h −1 and excellent durability (OIR = 2.48 mV/°C) under 0–400 mA cm −2 , 30°C–90°C, and 8–13 pH. The NCMFP-based anion-exchange membrane electrolyzer achieves 500/1,000 mA cm −2 at 1.78/1.99 V, maintaining stability over 120 h. Economic analysis shows a high-value utilization cost of only 18.2 RMB g −1 , significantly lower than LiNi 1-x-y Co x Mn y O 2 (NCM) recycling/regeneration. This work provides new insights for battery upcycling and designing high-performance electrocatalysts for seawater splitting.