Application of Gibbs energy model to equilibrium potential for structural phase transition in lithium intercalation process

Structurally different solid phases can be observed for the charge/discharge process in the lithium intercalation electrodes. We present a new approach to describe the phase transition phenomena in the lithium-intercalated electrode. Equilibrium potential curves of lithium intercalation electrodes were estimated by the Nernst equation with the activity correction. In this work, the non-random two-liquid (NRTL) model and Redlich-Kister equation were used to represent the excess Gibbs energy for the potential of lithium intercalation electrodes. The equilibrium potentials of LiCoO2 and LiFePO4 electrodes calculated by the phase transition treatment were in good agreement with the experimental results.

► Modeling of equilibrium potential of LiCoO2 and LiFePO4.
► Activity correction for the Nernst equation of lithium intercalation reaction.
► Gibbs energy model for heterogeneous system.
► NRTL and Redlich-Kister equation are applied for the activity correction.
► Accurate simulation of equilibrium potential prediction is demonstrated.