Thickness evolution of commercial Li-ion pouch cells with silicon-based composite anodes and NCA cathodes

It is significant to monitor the thickness change of commercial Li-ion pouch cells that are assembled from Si-based electrodes and layered cathodes since the volume variation is critically linked with kinetic reaction mechanism and chemomechanical degradation. In this work, the single-point and full-field measurements are conducted on the thickness evolution of SiO_x/C-graphite/lithium nickel-cobalt-aluminum oxide (SiO_x-G/NCA) batteries. It is found that an abnormal overshoot that has been rarely observed in the previous studies appears at the beginning of discharge, which is believed to be the combined results between the rapid expansion of NCA and the contraction of graphite related to the state of charge (SOC). Compared with the results of single-point measurement, the spatial displacement distribution obtained from three-dimensional (3D) scanning suggests the full-field thickness evolution of the entire cell scale, which is more feasible and efficient to provide full-field information for supporting pouch cell design and pack integration.