Simultaneous anodic de-lithiation/cathodic lithium-embedded regeneration method for recycling of spent LiFePO4 battery

Abstract

The widespread use of lithium-ion batteries for energy storage will result in millions of tons of scrapped LiFePO4 (LFP) batteries. Current recycling technologies for LFP cathode materials require harsh acid treatments and are expensive. Hence, in this work, an ingenious electrochemical method is developed to recycle scrapped LFP. Specifically, through the charging/discharging process of an electrolytic system in which both the cathode and anode are scrapped LFP, the anode is de-lithiated to obtain FePO4 (FP), meanwhile, the Li+ from the anode is embedded into the cathode scrapped LFP to achieve regeneration. The experimental results show that the anode de-lithiation rate is 92 % and the cathode regeneration performance is closely related to the driving voltage. A voltage of 1 V converts the FP phase to LFP and effectively eliminates the LFP defect lattice. However, an excessive voltage (1.2 V) leads to an extremely fragile LFP crystal structure, resulting in the ineffective embedment of Li+ into the defective lattice and ineffective capacity restoration. The regenerated LFP exhibits a high restored capacity (136.5 mAh g−1 at 1 C) and excellent stability (95.32 % capacity retention after 300 cycles at 5 C). This novel method does not require an additional Li source, consumes low electrical energy (31.9 kWh t−1) and has a high current efficiency (>98 %), and it yields economic and environmental benefits that will contribute to the sustainable development of the LFP industry.