The electrode microstructure influences the cell performance and therefore the applications inwhich a cell can be used. Our theoretical model predicts a possible effect, where either the porosityor the thickness of curved electrode coatings (e.g. in cylindrical cells) differ, compared to uncurvedstate (e.g. in stacked pouch cells). According to our model, the porosity possibly deviates by -2% (concave side of coating) to +2% (convex side of coating) compared to the unwound electrode.
By light microscopy, the behavior can be visualized in experiments. Experiments of pristine electrodes with a winding diameter of 0.25 mm show a thickness increase even above 20%, corresponding to a curvature of 4 mm-1. Interestingly, the predicted thickness change is in accordance with experiments for the concave coatings of anode and cathode, but not for the convex ones. The observations can most probably be explained by local relieve of tensile stress in form of cracks, rather than homogeneous thickness decrease, which was predicted for the convex case. In contrast, concave coatings showed increased thickness by pushed out particles, due to the compressive stress. Mechanical changes of the electrode microstructure of curved electrodes can also be detected in aged cells. Our study is completed by an electrode curvature evaluation of CT images found in literature, where different cell types (pouch, PHEV1, 21700) and the previous aging or abuse methods were considered.