Phase-field model of ion transport and intercalation in lithium-ion battery

The unified 3D phase-field model for description of the lithium-ion cell as a whole is developed. The model takes into account the realistic distribution of particles in electrodes, percolative transport of ions, and difference in size of solute and solvent molecules. The model is based on the Cahn-Hilliard equation with spatially dependent interaction and dynamic parameters. The spatial dependences are determined through the order parameter field describing distribution of matter in nanostructured electrodes. The process of charging/discharging of a battery is simulated for constant chemical potential difference across the electrode/electrolyte interface, which naturally determines the electrochemical reaction. The proposed model is applied to study charging and discharging process in 3D lithium-ion cell with nanostructured electrodes. The current density over the cell depends linearly on the chemical potential difference. The obtained results indicate non-diffusive propagation of the concentration front during charging/discharging, nonuniform intercalation flux over the surface of electrode particles and violation of the equipartition of electric current density over the electrode surface. All these facts are not taken into account by most commonly used models.