Preparation of NCM811 from spent lithium-ion batteries and research on its modification

This study employed an ultrasound-assisted citric acid–sodium thiosulfate methodology for reclaiming target metals from discarded lithium-ion batteries. By systematically investigating parameters such as the concentrations of citric acid and sodium thiosulfate, the solid-to-liquid ratio, temperature and reaction time under optimal recovery conditions, recovery rates of Li, Ni, Co and Mn exceeding 94% were achieved. The leaching efficiency increased with increasing citric acid and sodium thiosulfate concentrations, as well as with higher temperature and longer reaction time, whereas it decreased with increasing solid-to-liquid ratio. The cathode material LiNi 0.8 Co 0.1 Mn 0.1 O 2 , hereafter referred to as NCM811, was subsequently synthesized and modified via aluminum oxide coating. It was found that the optimal application rate is 2% by weight. The resulting 2A@NCM composite exhibited the best electrochemical performance, with 95.24% capacity retention after 100 cycles at 0.5C within a voltage window of 2.8–4.3 V. This study provides new insights into the recycling and recovery of spent lithium-ion batteries.