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

Abstract

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.