Reuse, Recycle, and Regeneration of LiFePO4 Cathode from Spent Lithium-Ion Batteries for Rechargeable Lithium- and Sodium-Ion Batteries

Rechargeable lithium-ion batteries are dominating the energy storage market with a current market value of $50 billion. However, the exponential production of lithium-ion batteries is accompanied by an increased backflow as environmentally hazardous spent/end-of-life batteries, which need to be recycled efficiently. Herein, we demonstrate the possibility of reuse, recycle, and regeneration of a spent LiFePO4 (LFP) cathode for rechargeable lithium- and sodium-ion batteries. An approach of reusing the spent-LFP electrode in developing a new lithium-ion battery was initially explored. The refabricated LFP lithium-ion half-cells delivered excellent capacity and rate capability. Further, an unprecedented approach of using a spent-LFP electrode for sodium ion storage was investigated. The adopted low-temperature, rapid (15 min) microwave delithiation process could completely delithiate the LFP electrode, forming FePO4. This recycled FePO4 was tested for its sodium ion storage capability. Finally, an aspect of commercially viable, nearly zero-energy chemical lithiation/sodiation of microwave-derived FePO4 was also explored. Thus, regenerated LiFePO4 as lithium-ion half-cells exhibited a reversible capacity of 145 mAh/g at a current rate of 1C and 107 mAh/g at 10C and 96% capacity retention at 5C for 300 cycles. Similarly, the chemically sodiated FePO4 sodium-ion cell demonstrated a capacity close to 138 mAh/g at C/15, which is comparable to freshly prepared NaFePO4 (NFP) electrode's performances. Our electrochemical results confirm the potential of these rapid, sustainable, and energy-efficient methods for reutilization, recycling, and regeneration of failed LFP cathodes recovered from 32 650 cells for their proficient usage in both lithium- and sodium-ion storage.