A one-pot process for selective lithium recovery and in-situ transformation of NCM523 cathodes into a high-performance photocatalyst

This study aimed to develop a dual-functional one-pot strategy for spent LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cathode scraps by integrating selective lithium recovery with the in-situ conversion of residual transition metals into value-added functional materials. A sodium persulfate (SPS)-assisted reaction system was constructed, and methylene blue (MB) was selected as a model organic pollutant to evaluate the photocatalytic performance of the converted products. The effects of calcination pretreatment, SPS dosage and initial pH were optimized, while reactive species and degradation pathways were investigated through mechanistic analysis and LC-MS/MS. Under the optimized conditions of calcination at 420 °C, SPS dosage of 1.0 g/L and initial pH 7.0, the lithium leaching efficiency reached 97.38%, lithium selectivity over co-leached Ni, Co and Mn reached 79.90%, and MB degradation efficiency in the one-pot system reached 91.50%. The delithiated residue was directly transformed into a ternary mixed-phase catalyst containing NiO, CoO and MnO 2 /MnO x , which achieved 98.29% MB degradation in an independent SPS-activation photocatalytic system. Mechanistic results indicated that photogenerated holes and multivalent Ni/Co/Mn redox cycles promoted the formation of singlet oxygen and superoxide radicals. Overall, this integrated route enables efficient lithium recovery, high-value utilization of residual metals and pollutant degradation, providing a promising waste-to-resource strategy for spent LIB cathode recycling and environmental remediation. Graphical abstract