Low-temperature direct regeneration of spent LiFePO4 cathodes via thiourea-assisted targeted PVDF degradation

Low-temperature liquid-phase strategy directly regenerates spent LFP. • Thiourea directionally degrades residual PVDF, promoting regeneration. • The regeneration strategy eliminates the need for autoclaves. • Delivers 131.9 mAh·g −1 at 5C, retaining 89.5% capacity after 700 cycles. The widespread use of lithium iron phosphate (LFP) batteries has led to an unprecedented surge in end-of-life cells, highlighting an urgent need for cost-effective recycling technologies. Although direct regeneration offers a promising solution, its practical effectiveness is often limited by residual impurities. Here, we report a low-temperature, liquid-phase regeneration strategy that uses thiourea to specifically degrade residual polyvinylidene fluoride (PVDF) binders. First, a mild elution process separates the spent LFP coating from the current collector. The purified powder is then regenerated in a liquid phase, using l -ascorbic acid as a reducing agent and thiourea to drive PVDF degradation. This method simultaneously restores the crystal structure and removes impurities without requiring energy-intensive high-temperature or high-pressure hydrothermal conditions, thereby streamlining the process and significantly cutting costs. The regenerated LFP cathode exhibits excellent electrochemical performance, delivering an initial discharge capacity of 160.4 mAh·g −1 at 0.1C, a strong rate capability of 131.9 mAh·g −1 at 5C, and 89.5% capacity retention over 700 cycles. These results demonstrate a scalable and economically viable approach for recycling spent LFP batteries. Download: Download high-res image (139KB) Download: Download full-size image