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.

This study was attempted to study for recovery of Li as Li2CO3 from cathode active material, especially NCA (LiNiCoAlO2), recovered from spent lithium ion batteries. This consists of two major processes, carbonation using CO2 and water leaching. Carbonation using CO2 was performed at 600ºC, 700ºC and 800ºC, and NCA (LiNiCoAlO2) was phase-separated into Li2CO3, NiO and CoO. The water leaching process using the differences in solubility was performed to obtain the optimum conditions by using the washing time and the ratio of the sample to the distilled water as variables. As a result, NCA (LiNiCoAlO2) was phase-separated into Li2CO3 and NiO, CoO at 700ºC, and Li2CO3 in water was recovered through vacuum filtration after 1 hour at a 1:30 weight ratio of the powder and distilled water. Finally, Li2CO3 containing Li of more than 98 wt.% was recovered.