Use of mild organic acid reagents to recover the Co and Li from spent Li-ion batteries

Abstract

New organic acid mixtures have been investigated to recover the valuable metal ions from the cathode material of spent Li-ion batteries. The cathodic active material (LiCoO2) collected from spent Li-ion batteries (LIBs) is dissolved in mild organic acids, iminodiacetic acid (IDA) and maleic acid (MA), to recover the metals. Almost complete dissolution occurred in slightly excess (than the stoichiometric requirement) of IDA or MA at 80°C for 6h, based on the Co and Li released. The reducing agent, ascorbic acid (AA), converts the dissolved Co(III)- to Co(II)-L (L=IDA or MA) thereby selective recovery of Co as Co(II)-oxalate is possible. The formation of Co(III)- and Co(II)-L is evident from the UV–Vis spectra of the dissolved solution as a function of dissolution time. Thus, the reductive-complexing dissolution mechanism is proposed here. These mild organic acids are environmentally benign unlike the mineral acids.