Effective regeneration of waste LiFePO4 cathode material by Cu doping modification

Abstract

The exponential growth of electric vehicles (EVs) will lead to the large-scale retirement of lithium iron phosphate (LFP) batteries in the future. This work proposes an environmentally friendly solid-phase strategy for regenerating waste LFP cathode materials. The regeneration mechanism is also investigated through characterizations. The method involves lithium supplementation, crystal structure repair and Cu doping. Glucose is used as a reducing agent to reduce a large amount of Fe3+ in waste LFP to Fe2+, while the addition of Li+ is used to fill the lithium vacancy in waste LFP. Notably, Cu doping increases the vibrational density and conductivity of the regenerated material and expands the ion diffusion channel, which significantly enhances the electrochemical performance of the regenerated LFP cathode. Moreover, the specific capacity of regenerated LFP (Cu@R-LFP) at 0.05C is 160.15 mAh/g, about 97.65 % of that of new LFP (N-LFP). The capacity retention rate of Cu@R-LFP can be as high as 81.19 % even after 1,000 cycles at 1C rate. The method proposed in this study provides a simple and scalable strategy for recycling waste LFP cathode materials.