Ultrafast and efficient recovery of valuable metals from spent LiCoO₂ cathode via organic ferrous assisted reductive...

Efficient and environmentally sustainable recovery of valuable metals from spent lithium cobalt oxide (LiCoO₂, LCO) cathodes is crucial for the lithium-ion batteries recycling. While ammonia leaching offers a promising pathway for green closed-loop recycling, its conventional application suffers from slow kinetics. To address this limitation, this study introduced ferrous glycinate (Gly-Fe) as a novel reductant, alongside FeCl₂ for comparison, into an NH₃-based system, which enabled ultra-rapid reductive dissolution of LCO. A systematic investigation of key parameters, including temperature, ammonia concentration, and Fe/Co molar ratio, revealed Gly-Fe's superior performance. It was found that nearly complete leaching efficiencies of Li⁺ (∼100.0%) and Co²⁺ (96.2% ± 2.1%) was achieved within just 60 min using Gly-Fe. In contrast, FeCl₂ attained Li⁺ leaching of ∼ 100.0% but only 83.5% ± 2.6% for Co²⁺ within 30 mins under comparable conditions, highlighting the kinetic advantage and effectiveness of the glycine-based complex. Noticeably, Fe²⁺ from both reagents precipitated spontaneously in the alkaline ammonia medium without additional additives, facilitating the direct recovery of high-purity leach products. This approach preserved the intrinsic purity advantages of ammonia leaching while accelerating metal extraction rates and significantly enhancing metal recovery rates, thereby establishing a solid foundation for the development of efficient closed-loop recycling for spent lithium-ion batteries.