<p>The recycling of spent LiFePO₄ is of great significance for the sustainable development of the battery industry and environmental protection. In this paper, a multifunctional organic lithium salt was used to repair spent LiFePO₄ in one step. As an inexpensive organic lithium salt, lithium ascorbate can not only serve as a Li supplement but also as a carbon source, achieving both Li supplementation and carbon coating simultaneously. The reducibility of lithium ascorbate can reduce Fe³⁺ in spent LiFePO₄ to Fe²⁺, reducing the concentration of Li/Fe anti-side defects. At the same time, lithium ascorbate can also be used as a carbon source to realize carbon coating on spent LiFePO₄ in annealing engineering to improve its conductivity. The R-LFP displays a discharge capacity of 154 mAh g⁻¹ at 0.5 C, compared to 130 mAh g⁻¹ for S-LFP. After 450 cycles, R-LFP retains 91.3% of its capacity, outperforming S-LFP at 80.3%. The method can repair the spent LiFePO₄ through a simple one-step annealing method, which has a short process, high efficiency, and large application prospects.</p>