Insights into the thermodynamic and kinetics of selective recovery of lithium from spent lithium-ion batteries with gypsum waste

Abstract

With a purpose of selective extraction of lithium from spent lithium-ion batteries, the sulfation roasting of cathode material with gypsum waste followed by water leaching was proposed in the present study. The thermodynamics and kinetics of the sulfation roasting process were systematically studied. The activation energy, pre-exponential factor, and reaction mechanism function of the sulfation roasting reaction were determined to be 220.93 kJ/mol, 6.264 × 10², and g(α) = 1-(1-α)^2/3, respectively. The optimal parameters for the sulfation roasting process were identified as a roasting temperature of 750 °C, a mass ratio of graphite, gypsum, and cathode material at 0.4:0.8:1, and a roasting duration of 60 min. Under these conditions, the Li leaching rate reached 79 %, while the leaching rates of Ni, Co, and Mn remained near 0. Li from the cathode material preferentially reacted with CaSO₄ to form Li₂SO₄ and CaCO₃, while some Li also reacted with CaCO₃ to produce Li₂CO₃. Ni, Co, and Mn in the cathode material initially formed intermediate products such as Li_xNi_2-xO₂, Li_xCo_1-xO, and LiMn₂O₄. These intermediates eventually transformed into Ni, Ni₃S₂, Co, MnO, and Li₂CO₃ in the presence of graphite.