A phenomenological thermodynamic approach for evaluating the energetics involved in the discharge of lithium ion battery

Abstract

Processes involved in the discharge of a Li-ion battery are represented via thermochemical cycle, and the free energy involved in the process is expressed in terms of porosity, redox potential, energetics of solvation, diffusion, phase transition, and double-layer crossing of Li ions. In this study, the value of free energy involved in the discharge process of LiMn₂O₄ is evaluated. The maximum threshold of anode porosity and effect of Jahn–Teller distortion on the cathode material are predicted accurately. The maximum threshold of porosity for graphite anode is 0.4 to 0.5 and the Jahn–Teller distortion energy is predicted to be −0.84 eV. Phase transition is predicted to occur at 0.5 SoC of Li ions at the cathode. The predicted values are in satisfactory agreement with those reported in the literature.