Sustainable reprocessing of lithium iron phosphate batteries: A recovery approach using liquid-phase method at reduced temperature

Abstract

Lithium iron phosphate batteries, known for their durability, safety, and cost-efficiency, have become essential in new energy applications. However, their widespread use has highlighted the urgency of battery recycling. Inadequate management could lead to resource waste and environmental harm. Traditional recycling methods, like hydrometallurgy and pyrometallurgy, are complex and energy-intensive, resulting in high costs. To address these challenges, this study introduces a novel low-temperature liquid-phase method for regenerating lithium iron phosphate positive electrode materials. By using N₂H₄·H₂O as a reducing agent, missing Li⁺ ions are replenished, and anti-site defects are reduced through annealing. This process restores nearly all missing Li⁺ ions at 80 °C/6h. After high-temperature sintering at 700 °C/2h, the regenerated LiFePO₄ matches commercial LiFePO₄ in terms of anti-site defects and exhibits excellent performance with a 97 % capacity retention rate after 100 cycles at 1C. Compared to high-temperature techniques, this low-temperature liquid-phase method is simpler, safer, and more energy-efficient, offering a blueprint for reclaiming discarded LiFePO₄ and similar materials.

Keywords: Battery recycling; Energy efficiency; LiFePO(4); Lithium iron phosphate batteries; Low-temperature liquid-phase method.