Kinetics and thermodynamical evaluation of electrode material of discarded lithium-ion batteries and its impact on recycling

Abstract

The investigation of decomposition thermodynamics and kinetics of active electrode materials is an important tool in the development of recycling techniques for discarded lithium-ion batteries. The knowledge of thermal decomposition kinetics and thermodynamics aids the understanding and improving thermal response and can provide guidelines for the design of the thermal recycling process. Evaluation of thermal response, kinetics parameter, and thermodynamic parameters, which include activation energy, change in Gibbs free energy (ΔG), change in enthalpy (ΔH), change in entropy (ΔS) were carried out using isoconversional kinetic methods employing thermogravimetric. Comparative analysis of thermal decomposition kinetics, experimental, and indigenous carbothermal reduction in the single (LiCoO2/C) and the mixed phases cathode (LiCoO2, LiMn2O4, LiNi0.5Mn1.5O4/C) active electrode material was also carried out. The average activation energy for the thermal dissociation of mixed cathode active material is estimated as 187.6 kJ mol−1, and ΔG, ΔH, ΔS are 243 kJ mol−1, 179.9 kJ mol−1, − 0.06 kJ mol−1 K−1, respectively. Thermal dissociation and carbothermal reduction in active electrode material was investigated in 600–1000 °C and found that active electrode material decomposes and reduces above 600 °C. A simple processing comprising reduction followed by water leaching and magnetic separation was used for metallic recovery. The optimum magnetic product of mix phase cathodeactive material comprises Co: 61%, Mn: 19%, Ni: 7%, O: 13%, and lithium was recovered as Li2CO3 with Li extraction ~ 80%.