Cathodes of spent Li-ion batteries: Dissolution with phosphoric acid and recovery of lithium and cobalt from leach liquors

Abstract

This paper presents the study of an innovative process: the reductive dissolution of mixed lithium cobalt oxide contained in the cathodes of spent Li-ion batteries with phosphoric acid. The studied parameters were: reaction time, temperature, stirring speed, solid-liquid ratio and concentrations of the leaching agent (H3PO4) and the reducing agent (H2O2). Reactants and products were characterized by atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the reducing dissolution process with phosphoric acid is an efficient way for the extraction of lithium and cobalt, achieving dissolution values close to 100%. In addition, a recovery of 88% of Li + as Li3PO4 and 99% of Co+ 2 as CoC2O4, with purities of 98.3% and 97.8% was found respectively.