Suppressing the coordination of ferric ions for efficient recycling of spent lithium iron phosphate

The increasing demand for lithium iron phosphate (LFP) batteries has raised concerns about the disposal of the cathode materials at the end of their functional lifespan, prompting significant interest in recycling waste LFP cathodes, particularly regarding the use of organic acids to minimize environmental impact and reduce acid mist during the process. However, the coordination of organic acids with Fe affects the distribution of ferric ions in the dissolution–precipitation equilibrium, which represents a significant challenge for the separation of Li and Fe. In this study, we propose an environmentally friendly and effective method for extracting Li from spent LFPs while retaining Fe in the precipitate. Lactic acid was selected in conjunction with H 2 O 2 , enabling Li recovery exceeding 99 % and producing Li 3 PO 4 with a purity of 99.2 %. Monitoring elemental concentrations during the leaching reaction confirms that the leaching process is dual-controlled by both of the internal-diffusion and the external surface reaction models. Comparative studies with oxalic acid and citric acid further demonstrated that the lactic acid-H 2 O 2 system offers superior separation of Li and Fe. Cost analysis indicates that this method yields a profit of 3.56 USD kg −1 , highlighting its economic viability and potential for sustainable recycling practices.