Valorization of Cobalt from Waste LIB Cathode through Cobalt Oxalate and Cobalt Oxide Synthesis by Leaching-Solvent Extract-Precipitation Stripping

An ecoefficient, economical and sustainable valorization process for the synthesis of Co₃O₄ from waste lithium-ion battery (LIB) by leaching-solvent extract-scrubbing-precipitation stripping route has been developed. Through an optimization, the waste LIB cathode was leached using 2000 mole/m³ of H₂SO₄ and 5 Vol. % of the H₂O₂ at a pulp density of 100 kg/m³ under leaching time 60 minutes and temperature 75°C. From the separated leach liquor, cobalt was purified by saponified Cyanex 272. From cobalt, loaded Cyanex 272 impurities were scrubbed and the CoC₂O₄·2H₂O was recovered through precipitation stripping. Finally, the precipitate was calcined to synthesize Co₃O₄, which is a precursor for LIB cathode materials manufacturing. From TGA-DTA, followed by XRD analysis it was confirmed that at 200°C the CoC₂O₄·2H₂O can be converted to anhydrous CoC₂O₄ and at 350°C the anhydrous can be converted to Co₃O₄ and at 1100°C the Co₃O₄ can be converted to CoO. Through reported route waste LIB can back to LIB manufacturing process through a versatile and flexible industrial approach.