Exploring a sustainable and eco-friendly high-power ultrasonic method for direct regeneration of lithium iron phosphate

The effective recycling of retired LiFePO4 batteries serves dual purposes: addressing the resource supply-demand contradiction and mitigating environmental pollution. However, the existing recycling methods for waste LiFePO4 batteries often entail high energy consumption, time consumption, complex procedures, or the use of substantial amounts of chemical raw materials, leading to increased recycling costs. Moreover, both methods generate toxic gases or discharge excessive pollutant-containing liquids during the recycling process, posing a risk of secondary pollution. Here, we introduce the application of ultrasound-assisted regeneration in waste LiFePO4 cathode material directly. Ultrasound waves generate localized high temperature, high pressure, and intense shock wave jets to repair the lithium vacancy defects and anti-site defects in the waste LiFePO4. Based on the experimental findings, the regeneration of LiFePO4 was achieved with impressive results. At an ultrasound power of 500 W and a duration of 50 min, the regenerated LiFePO4 displayed a discharge specific capacity of 135.1 mAh∙g−1 and an impressive capacity retention of 97 % after 100 cycles at a 1C (1C = 170 mA g−1) current density. This study presents a promising and environmentally friendly approach for recycling and regenerating retired LiFePO4 batteries.