Temperature Dependence in Responses of Lithium-Ion Pouch Cells Under Mechanical Abuse

Abstract

Unveiling the role of environmental temperature in the overall response of lithium-ion batteries under mechanical abuse and the underlying mechanism is necessary for comprehensively assessing crash safety of electric cars. In this study, both fresh samples and aged samples of a pouch-type battery cell are subjected to hemispherical indentation test at five different temperatures. Mechanical-electrical-thermal responses of all the cases are analyzed and compared. The mechanical response data indicate that higher temperature tends to lower the stiffness and the peak force of the cell under indentation. Component level tests focusing on tensile and compression behavior of electrodes are carried out to help understanding the dominant mechanism. Regarding electrochemical activity of electrodes, an argon-protected testing method is developed to keep the electrode samples from air exposure so as to inspect the mechanical properties as close to the in situ state as possible. Analysis on the uniform compression and hemispherical indentation of the stacked anode samples reasonably addresses the temperature dependence of the cell level mechanical response. Besides, it can be concluded that coupling effect in the mechanical behavior is almost negligible for the two factors, i.e., the environmental temperature and the aging degree, no matter at cell level or component level.