Low-cost and environmentally friendly physic-mechanical pre-treatments to recycle lithium iron phosphate cathodes

Abstract

Recycling Lithium Iron Phosphate (LFP) batteries is challenging, as their low economic value hinders the profitability of full-scale processes. Optimized pre-treatments are crucial for the overall efficiency and economic profitability of recycling processes. This study explored chemicals-free physic-mechanical pre-treatment processes aimed to detach waste LFP cathodes (production scraps and end-of-life, EoL) from aluminium current collectors. The technical performances of ultrasounds (35 kHz, in water at 25 °C for 5, 15, 30 min), ball milling (840–1080 rpm for 8, 16, 24 min), and thermal treatment (30 min at 200, 250, 300, 350,°C) coupled with ball milling (840 rpm for 5 min) have been compared. Environmental impacts and economic cost were calculated based on energy demand. The highest separation efficiency achieved were 95 ± 5% for Li, 99 ± 6% for Fe, and 80 ± 3% for P in scrap cathodes, treated at 200 °C for 30 min and ball milled at 840 rpm for 5 min; 93 ± 15% for Li, 97 ± 21% for Fe and 82 ± 20% for P in EoL cathodes, treated at 250 °C for 30 min and ball milled. The global warming impacts were: 3.33 ± 0.55 kg CO2 eq/kg of detached cathode for scraps and 3.08 ± 0.25 kg CO2 eq/kg for EoL cathodes; the costs were 1.45 ± 0.24 €/kg of detached cathode for production scraps samples and 1.34 ± 0.11 €/kg for EOL samples. In conclusion, chemicals-free mechanical detachment was effective both for production scraps and EoL cathodes, while thermal treatment was especially beneficial for EoL cathodes, and reducing milling time improved the environmental impacts and costs of the pre-treatment processes.