Indirect electrochemical leaching and separation of cobalt and lithium from spent LiCoO₂ through recovery and reuse of sulfuric acid

Electrochemical technologies have great potential for extracting and recycling metals from spent lithium-ion batteries, but often rely on external acid use, require additional separation steps, or have low leaching rates. Herein, an innovative system combining electrochemical separation and chemical leaching was investigated to recover lithium and cobalt from spent LiCoO₂ (LCO) batteries. The system was able to generate and reuse sulfuric acids for multiple operational cycles by recovering SO₄^2-. Under the optimal conditions (0.25 M sulfuric acid, 80 ℃, 8 g/L solid-to-liquid ratio), 100 % of both Li⁺ and Co²⁺ were released within 0.5 h. Sulfuric acid recovery efficiency was 97.0 ± 4.5, 97.9 ± 13.1, and 94.1 ± 6.6 %, under an applied current of 150, 200 and 250 mA, respectively. Co²⁺ was mostly removed as solid precipitates and over 90 % Li⁺ remained in the soluble form in the catholyte, owing to their different behaviors in an alkaline solution. During the extended operation over ten cycles, Co and Li recovery efficiencies remained relatively stable until the cycle 7. When treating real spent LCO from the used batteries, the system achieved 94.6 % of sulfuric acid recovery, 100 % of Co²⁺ precipitated, and 92 % of Li⁺ retention. Those results encourage further exploration of electrochemical metal recovery from spent LCO batteries.