Green Phosphate Route of Regeneration of LiFePO₄ Composite Materials from Spent Lithium-Ion Batteries

Abstract

To develop efficient, viable, and promising routes to regenerate nano-LiFePO4 (nano-LFP) composite materials from spent LFP batteries, this paper studied phosphate approaches by taking Li3PO4 and FePO4 as raw materials. The crystalline structure, morphology, and physicochemical properties of regenerated LiFePO4 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 LiFePO4 owned a good olivine structure with a space group of Pnma. After being coated with carbon, rectangular-structured LiFePO4 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 Li3PO4 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 LiFePO4/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 LiFePO4 composite materials.

A Facile and Effective Method to Strip and Recycle Spent LiFePO4 Cathode Materials

“…These two kinds of carbon as electronic conductive skeleton, and LiF and Li 2 O as ionic conductive base, them forming a dual conductive network to facilitate lithium storage [31] . At the same time, it can be seen that there are flocculated carbon network connections between the particles, which is conducive to the transfer of electrons [1c] . Carbon coating on the surface helps to improve the electrochemical properties and prevent excessive grain growth [32] …”

A Comprehensive Review on Reductive Recycling of Cathode Materials of Spent Lithium‐Ion Batteries

“…Simultaneously, the nitrogen atoms derived from the amino group integrate into the carbon layer, creating additional active sites and enhancing the electrical conductivity of the LFP particles. The resultant regenerated LFP manifests commendable electrochemical performance, exhibiting an impressive capacity retention of 86 % even after 500 cycles at a high rate of 5 C. A large number of studies have conclusively demonstrated the feasibility of regenerating spent LFP directly from LiFePO 4 through various methods, including solid-phase sintering, molten-salt reduction, [71] hydrothermal reduction, [72] and electrochemical treatment. Despite these findings, the pragmatic application and economic viability of these techniques necessitate further scrutiny.…”

Co-recovery of spent LiCoO2 and LiFePO4 by paired electrolysis

“…The pyrometallurgy process of using high-temperature calcination benefits from the simplicity of the process and can be used on a large scale, but this method consumes a lot of energy and produces a large amount of greenhouse gases (GHGs). [15][16][17][18] The hydrometallurgy process uses chemicals such as mineral acids to selectively leach metal elements from the positive electrode material of LIBs and recover various elements through fractional precipitation. It is widely prevalent because of the high-purity products, but the hydrometallurgy process needs to consume a large amount of chemical reagents and water.…”