Transfer from experimental test cell to automotive pouch cell level: A combined experimental and modeling approach

Knowledge of the local electrode potentials within the battery cell is essential for a safe and optimal operating window, as well as innovative fast charging strategies of lithium-ion batteries. Three-electrode test cells facilitate measuring the individual electrode's behavior during operation. However, transferring test cell results to large-scale commercial (pouch) cells is not straightforward. In this paper, we investigate the comparison of an automotive 60 Ah pouch cell with three-electrode cells built out of extracted electrodes from the pouch cell and standard components for the separator and electrolyte, using a commercial test cell housing. We found that the measured voltage behavior of both cell types differs significantly for C-rates higher than C/4 and fast changing current loads, such as pulse profiles or Worldwide Harmonized Light Vehicles Test Procedure cycles. This discrepancy hinders the direct transfer of test cell results to large pouch cells. To address this issue, we introduced an equivalent circuit model that incorporates an ohmic correction factor to bridge the experimental data and pouch cell behavior. The model's parameters are derived from the half-cell impedance data measured, enabling the investigation of local potentials at the anode and cathode within the simulation framework. We achieved a good correlation and reproducibility for rapidly changing current loads. The methodology presented demonstrates a good potential for fast and significant parametrization of simulation models by utilizing the extracted electrode material of the pouch cell and easily obtainable standard separators and electrolytes with a very high reproducibility. • Efficient simulation of the voltage behavior of a pouch cell using three-electrode experimental cell parameterization • Model-based identification of safe and optimal operating windows of lithium-ion batteries and fast charging strategies • Alignment of pouch cell and experimental cell data with an ohmic correction factor in the impedance-based model • Inductive loops in the Nyquist plot of anode and cathode impedances are probably not caused by electrode processes