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

•Mixture of ascorbic acid and citric acid at 80 °C is used to extract Co and Li ions from the spent Li-ion battery.•The dissolution follows a reductive-complexation mechanism under stoichiometric condition.•The dissolution rate constant k = 3.1 ´ 10-3 min−1 for Li and k = 0.8 ´ 10-3 min−1 for Co ions.•Formation of Co(III)- and Co(II)-citrate complex during the dissolution is confirmed.•A selective precipitation of Co as Co-oxalate and Li as LiF is carried out.

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.

Graphical abstractResource recycling from the spent lithium-ion battery through chemical extraction and precipitation.Figure optionsDownload full-size imageDownload as PowerPoint slide