Direct and Sustainable Regeneration of Spent LiCoO₂ Cathodes Using an Eco-Friendly Deep Eutectic Solvent-Based Approach

Current recycling methods of spent lithium cobalt oxide cathodes, primarily for high-temperature roasting and metal leaching, are often energy-intensive and environmentally damaging. This paper introduces a novel, low-impact method using a deep eutectic solvent (DES) composed of glycerol and lithium chloride, which, instead of serving for metal ion leaching, serves as a lithium carrier and reductant. This approach directly supplements lithium ions and reduces Co⁴⁺ at mild conditions (80 °C) and ambient pressure, facilitating the direct regeneration of spent LiCoO₂ materials. The regenerated material exhibits an initial discharge capacity of 134.84 mAh g⁻¹ at 0.1 C, maintaining 95% capacity after 200 cycles. This DES-based method not only restores the original compositional and lattice structural integrity of LiCoO₂ materials but also allows for the reuse of DES with high efficiency. This method, in comparison to traditional hydrometallurgical and pyrometallurgical recycling, demonstrates lower energy consumption, reduced environmental impact, and delivers enhanced economic and environmental benefits. It offers an excellent environmental and economic approach for the recycling of various spent LiCoO₂ batteries.