Influence of charge conditions on the deformation of fresh and aged cylindrical cells

The electrification of transport and the integration of stationary storage systems in electrical networks hinge on the performance and longevity of lithium-ion batteries. However, severe charging conditions, such as fast and/or low temperature raise significant challenges as degradation becomes difficult to predict. In this paper, the mechanical deformation of a cylindrical NMC-Graphite/SiOx cell is studied. We investigate the influence of charging conditions on mechanical deformation in both fresh and aged cells considering an aged cell previously subjected to cold cycling. Thanks to incremental capacity analysis (ICA) interpretation, charge at a standard rate shows that cell deformation is an image of Li-ion insertion/extraction processes. Experimental results demonstrate that mechanical deformation during charging is amplified under high rates. Additionally, deformation evolution is smoothed during fast charge and low temperature charge, indicating heterogeneous lithiation which can promote localised degradation mechanisms. By comparing two fresh cells with an aged cell under identical charging conditions, this works highlights the lasting effects of prior exposure to lithium-plating conditions applied on the aged cell. The aged cell exhibits a 2 times higher amplified mechanical deformation and abnormal temperature increase ( + 13 ° C) during 0.7C fast charge at 25 ° C. This behaviour likely indicates parasitic reactions associated to plating-related degradation mechanisms. These findings highlight the importance of monitoring deformation in both fresh and aged cells under various charging conditions to detect potential abnormal behaviours. • The mechanical deformation of cylindrical NMC-Graphite/SiOx cell is studied during charge. • Cell deformation is driven by phase transition in electrode material. • High charging rates amplify cell deformation and heterogeneous lithiation. • Abnormal deformation on the aged cell is observed at 0.7C.