Electrowinning of Nickel from Lithium-Ion Batteries

The growing demand for lithium-ion batteries (LIBs) is driving a rapid increase in the volume of spent cells which-as hazardous waste-must be managed effectively in accordance with circular-economy principles. Hydrometallurgical recycling allows the recovery of critical metals at far lower environmental cost than primary mining. This paper presents a method for obtaining metallic nickel from sulfate leach solutions produced by leaching the so-called "black mass" derived from shredded LIBs. Nickel electrodeposition was performed on a stainless-steel cathode with Ti/Ru-Ir anodes at 60 °C and pH 3.0-4.5. Two process variants were examined. Variant A-with a decreasing Ni²⁺ concentration (49 → 25 g L^-1)-achieved a current efficiency of 60-88%, but the deposits were non-uniform and prone to flaking. Variant B-in which the bath was stabilized by the continuous dissolution of Ni(OH)₂ (maintaining Ni²⁺ at 35-40 g L^-1) and amended with PEG-4000, H₃BO₃ and Na₂SO₄-reached higher efficiency (78-93%) and produced uniform, bright deposits up to 0.5 mm thick with a purity >90%. The results confirm that keeping the nickel concentration constant and appropriately modifying the electrolyte significantly improve both the qualitative and economic aspects of recovery, highlighting electrolysis as an efficient way to process LIB waste and close the nickel stream within the material cycle.