High-power ultrasound facilitation of the generality for LiFePO4 regeneration

Abstract

Renowned for its remarkable electrochemical performance, temperature stability, safety attributes, and long-lasting durability, the LiFePO4 battery has gained prominence in diverse applications, particularly within the electric vehicle sector. Despite not holding the top market position, approximately 69 % of global batteries comprise LiFePO4, raising concerns about a potential increase in discarded batteries. Present research predominantly concentrates on extracting valuable materials such as Co, Li, Ni, and Mn, frequently sidelining spent LiFePO4 batteries due to their perceived limited recoverable content compared to NMC and LCO batteries. However, LiFePO4 batteries removed from electric vehicles retain approximately 80 % of their initial capacity, with the cathode material sustaining a robust crystal structure. Here, direct recycling techniques employing a green reducing agent like ascorbic acid have shown promise in rectifying lithium vacancies and anti-sites in spent LiFePO4 through high power ultrasonic reactions. This work delves into exploring the influence of different lithium sources and Li + concentrations on the structure and electrochemical performance of regenerated LiFePO4. The direct regeneration of LiFePO4 showcases a favorable crystal structure that maintains stable phase transitions during charge and discharge processes. RLFP-0.2 M exhibits discharge specific capacity of 154.71 mAh∙g−1. It indicates RLFP-0.2 M maintains a discharge specific capacity of 132.89 mAh∙g−1 after 200 cycles at 1C current, retaining a remarkable capacity retention rate of 93.56 %. This study demonstrates that high-power ultrasonication is a universally applicable, low-energy, highly efficient, operationally simple, and environmentally friendly method for direct recycling of spent LiFePO4 batteries. Our research not only investigates the influence of various lithium sources and Li + concentration but also optimizes the recycling process for spent LiFePO4 batteries. Additionally, it provides an experimental foundation and reference for the recycling of other power batteries, contributing to achieving green direct recycling of various power batteries.