Green Phosphate Route of Regeneration of LiFePO<sub>4</sub> Composite Materials from Spent Lithium-Ion Batteries
Zixuan Wang, Dandan Wu, Xi Wang, Ye Huang, Xu Wu
Abstract
To develop efficient, viable, and promising routes to regenerate nano-LiFePO 4 (nano-LFP) composite materials from spent LFP batteries, this paper studied phosphate approaches by taking Li 3 PO 4 and FePO 4 as raw materials. The crystalline structure, morphology, and physicochemical properties of regenerated LiFePO 4 nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and electrochemical measurement. Regenerated LiFePO 4 owned a good olivine structure with a space group of Pnma . After being coated with carbon, rectangular-structured LiFePO 4 prepared by hydrothermal synthesis exhibited high specific capacity, excellent rate capability, and good Li + diffusivity. When the pH value was around 8.0 and the amount of the Li 3 PO 4 raw material was 14 mmol, the discharge capacity at 0.1C was 158.6 mAh g –1 and the capacity retention rate was 99.19% at 1C after 300 cycles. Meanwhile, flake-like LiFePO 4 /C synthesized by the carbothermal method at 700 °C and a 14 wt % carbon mass fraction showed an initial discharge capacity of 159.0 mAh g –1 at 0.1C and a capacity retention rate of 97.45% after 300 cycles at 1C, exhibiting excellent electrochemical performance. Overall, this study provides a facile, feasible, and sustainable recovery method for the battery industry for recovering phosphate products from spent LFP cathode materials and subsequent large-scale regeneration of LiFePO 4 composite materials.