Cobalt recovery from lithium cobalt oxide cathode scraps via green solvents: Process development and life cycle assessment

Abstract

ABSTRACT A recycling process for recovering cobalt from lithium-ion battery cathode production scraps is investigated using green solvents. The method combines electrode delamination with triethyl phosphate (TEP), dissolution of the recovered active material in a deep eutectic solvent (DES) composed of choline chloride and oxalic acid (1:1 molar ratio), and selective cobalt precipitation via controlled pH adjustment with KOH. The recovered black mass was characterized by Powder X-ray diffraction PXRD and Thermogravimetric analysis (TGA), confirming structural integrity of LiCoO 2 after TEP treatment and a purity of ~98.25%. Following DES leaching and precipitation at pH 12, a highly crystalline mixed cobalt oxide/hydroxide phase (CoO 2 /Co(OH) 2 ) was obtained with a purity of 99.12%. Microwave Plasma Atomic Emission Spectroscopy (MP-AES) analysis verified effective cobalt–lithium separation, with cobalt exclusively recovered in the solid phase. A cobalt recovery efficiency of 57% was achieved at lab scale, with losses primarily attributed to material handling at low Technology Readiness Level (TRL) rather than process inefficiency. A cradle-to-gate Life Cycle Assessment (LCA) was conducted using primary experimental inventory data. Environmental hotspot analysis identified DES preparation and the leaching step as the dominant contributors across most impact categories, driven respectively by solvent production (oxalic acid and choline chloride) and electricity consumption. Sensitivity and uncertainty analyses confirmed model robustness and highlighted renewable energy transition and solvent optimization as key levers for future improvement. This early-stage LCA provides a quantitative environmental baseline to support eco-design and scale-up of DES-based cobalt recovery from lithium cobalt oxide (LCO) cathode waste.