A Novel Layered Roasting Strategy for Spent LiCoO₂ Batteries: Toward Cleaner Lithium Extraction and Low Residue Processing

The green and efficient recycling of valuable metals from spent lithium-ion batteries (LIBs) is of great significance for ensuring the security of national strategic mineral resources and achieving sustainable development. Aiming at the technical bottlenecks of traditional roasting processes, such as high yield of water-leaching slag, low comprehensive recovery rate of valuable metals, and high risk of secondary pollution, this study developed a novel layered roasting process based on gradient isolation of raw materials. The results show that under the optimal conditions, the recovery rate of lithium can reach 84.10%, and the production of water-leaching slag is reduced by 66.71%. Li2CO3 products with a purity of 99.74% can be obtained from the water-leaching solution, meeting the purity standard (≥99.5%) for battery-grade Li2CO3. The pressurized leaching process of water-leaching slag can realize the recovery of cobalt and prepare CoSO4·6H2O products. This process not only reduces the production of water-leaching slag but also achieves high metal recovery rates, providing new ideas for the optimization of sulfide roasting processes.