Accurate electrolyte transport data are essential for predictive battery modeling, yet obtaining them experimentally remains one of the most persistent challenges in electrochemistry. Properties such as ionic conductivity, diffusivity, and transference number are difficult to measure reliably, and reported values in the literature can differ significantly. Even established experimental methods can produce contradictory results due to measurement artifacts, electrode interface effects, or inconsistencies in data interpretation. This uncertainty poses a significant barrier to building high-fidelity battery models. Continuum models like the Doyle-Fuller-Newman pseudo-2D (P2D) formulation rely on a self-consistent set of electrolyte transport parameters to describe ion movement, concentration gradients, and voltage response under various operating conditions. When these parameters are inaccurate or incomplete, model predictions quickly lose reliability, particularly for thick electrodes, high C-rates, or low-temperature operation.
Molecular dynamics (MD) simulations offer an alternative path forward. Instead of relying solely on often complicated experiments, MD can directly predict key electrolyte transport properties from atomic-level interactions, delivering a physically grounded and internally consistent data set. We have previously reported excellent agreement of ionic conductivity, salt diffusion coefficient, thermodynamic factor, and cationic transference number with carefully performed experiments reported in the scientific literature, and demonstrated the combination of MD simulations and P2D modeling in single-cell lithium and sodium-ion batteries.
In this collaborative work between the Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg and Compular, we generalize this workflow to full multilayer cells (in this case, a 21700 NMC811 cylindrical lithium-ion cell) by adding a thermal and a full-cell electrical model, coupled with the P2D electrochemical model, which in turn is fed by the predicted electrolyte transport properties from Compular Lab MD simulations and analysis.
By comparing results under different operating conditions and electrode designs, we showed how detailed electrolyte transport properties can significantly impact the simulated voltage behavior, particularly in demanding regimes such as low temperature, high C-rates, and thick electrodes.
