Mechanism of Lithium and Cobalt Recovery from Spent Lithium-ion Batteries by Sulfation Roasting Process

Diflerent from the traditional pyTometallurgical recovery process of Li and Co from spent lithium-ion batteries,a new recovery method for Li and Co was established by converting LiCoO2 into water-soluble metal sul-fates by roasting a mixture of LiCoO2 and NaHSO4-H2O.The evolution law of the mixture with increased roasting temperature was investigated by thennogravimetry-diflerential scamiing calorimetry(TG-DSC),in situ X-ray diflrac-tion(XRD),XRD,and X-ray photoelectron spectroscopy(XPS).The results show that the phase transition of LiCoO2 mixed with NaHSO4 H2O with increased temperature proceeded as follows:LiCoO2,NaHSO4 H2O→LiCo02,NaHSO4→Lil-xCo02,LiNaSO4,Na2S2O7,Na2SO4→Li1-xCoCO2,Co3O4,LiNaSO4,Na2SO4→Co3O4,LiNaSO4.The reaction mechanism of this roasting process may be as follows:LiCoO2+NaHSO4-H2O→l/2Li2SO4+l/2Na2SO4+l/3Co3O4+l/12O2+3/2H2O,Li2SO4+Na2SO4=2LiNaSO4.