In response to the potential environment pollution and energy waste caused by the increasing spent lithium iron phosphate batteries (LFPs), many recycling methods have been developed. Among previous studies, the physical recycling method has attracted numerous attention due to its uncomplicated process and high efficiency. This work provides a regeneration mechanism of that the organic carbon layer is in situ coated on the surface of LiFePO₄ particles by the decomposition of binder so that improves the conductivity and rate capability. When serving as cathode material for lithium ion battery, the 3 h-regenerated lithium iron phosphate battery delivers an excellent electrochemical performance which shows a discharge specific capacity of 151.55 mAh g⁻¹ at 0.2C and delivers a discharge capacity of 120.44 mAh g⁻¹ even at 10C compared with pristine spent LFPs. It delivers a discharge capacity of 124.35 mAh g⁻¹ in first cycle and maintains 103.12 mAh g⁻¹ with a high capacity retention rate of 82.93% after 2000 cycles at 0.5C through 18,650 battery testing. Meaningfully, a facile and sustainable regeneration process has been demonstrated to re-synthesize LiFePO₄ from spent LFPs by our study which can be reused as cathode materials for lithium-ion batteries, indicating an economical and facile method to recycle spent LiFePO₄ materials in large scale.