Development of an innovative workflow to optimize the fast-charge capability of lithium-ion battery cells

Abstract

State-of-the-art design criteria for electrodes in lithium-ion battery cells focus mostly on an increase of the energy density. Optimizing the fast-charge capability of a cell, especially with respect to lithium-plating, contradicts to these conventional design criteria and are therefore often neglected. This study presents an innovative workflow to resolve this conflict. An extensive electrode and cell characterization with respect to porosity and coating thickness is carried out to determine the corresponding electrode inner resistance, which limits the fast-charge capability of a cell. An empirical model is derived from these results, where the parameters are fitted with measurements. This model is used to determine the optimal porosity and coating thickness for a graphite-anode to obtain the lowest ionic resistance for a given volumetric capacity and thus, the lowest risk of lithium-plating. If the fast-charge capability is one of the design criteria, then it is necessary to determine the optimum porosity and coating thickness as explained in this study. Otherwise, high coating thicknesses or low porosities can lead to unnecessary high ionic resistance in the case of non-optimized settings. The innovative workflow of this study can be used as a guideline to determine the optimal parameter setting of an anode design. • Study on the effect of porosity and thickness on inner resistances of electrodes. • Ionic resistance of the anode mostly affects fast-charge capability of Li-ion cells. • Model to calculate the ionic resistance based on porosity and thickness of anode. • Optimal parameter setting for low ionic resistance at desired volumetric capacity. • Workflow to optimize the fast-charge capability of a Li-ion cell.