In-situ characterizations and mechanism analysis of mechanical inhomogeneity in a prismatic battery module

Inhomogeneity can accelerate performance degradation and reduce the lifetime of large-format batteries and battery modules. It is necessary to in-situ monitor the internal heterogeneous information and investigate the mechanical inhomogeneity of the batteries and modules. In this study, an in-situ measurement platform based on the integrating sensors and optical methods is developed. The internal stress and strain evolutions at the module-level are characterized and related to the deformation evolution at the cell-level. Both levels are suffering the serious mechanical inhomogeneity, which is quantitatively analyzed by the in-situ experiments and corresponding simulations, significantly affecting the long-term cyclic performance and consistency of the module. A new concept of mechanical consistency is introduced to correlate the mechanical inhomogeneity with module aging. This study can provide a basis for analyzing the aging mechanism and optimizing the structure of battery modules.