Recovery of valuable metal ions from the spent lithium-ion battery using aqueous mixture of mild organic acids as alternative to mineral acids

A well characterized cathode material (LiCoO2) recovered from spent lithium-ion battery is dissolved in aqueous mixture of citric acid (chelating agent) and ascorbic acid (reductant) at 80 °C. The dissolution proceeds with a reductive-complexing mechanism, and complete dissolution occurs in about 6 h when stoichiometric amount of C/A is used. The dissolution rate constants (k) are 3.1 × 10− 3 min− 1 for Li and 0.8 × 10− 3 min− 1 for Co ions as determined by ‘cubic rate law’ plots. The formation of Co(III)– to Co(II)–citrate during the dissolution is confirmed from the UV–Vis spectra. The dissolved solution was subjected for selective precipitation of cobalt as Co-oxalate and lithium as LiF using oxalic acid and NH4F, respectively. The present study has a merit when compared to literature reports as we make use of mild organic acids as alternatives to mineral acids.