Characterization of Behavior of Lithium Ion Battery Under Vibration and Shock Conditions

Abstract

Electric vehicles are being developed to address environmental issues such as air pollution caused by vehicles that use fossil fuels. As a result, the efficiency and performance of the battery, which is a crucial component of an electric vehicle, have become increasingly important. Research on the electrical behavior and heat of the battery is currently being actively conducted. However, with the improvement of battery efficiency and the increase in mass production, safety issues have arisen.Numerous studies are being conducted on battery safety, such as thermal runaway resulting from the deformation and failure of battery components, including the cathode and anode, caused by loads acting on the battery. Recently, research on stress factors caused by random vibrations and shocks that reflect actual vehicle operating conditions has made significant progress. For instance, Brand et al. conducted random vibration and shock tests based on the UN 38.3 standard test, evaluating durability based on the increase in resistance that occurs during the test1). Similarly, Berg et al. tested cylindrical cells with random profiles, according to the SAE J2380 standard and an even more severe profile2). After the test, they mainly observed the deformation of the tab, rather than the jellyroll of the battery. Yun et al. created a numerical model with the Representative Volume Element (RVE) model at the module level, obtaining the effective elastic modulus from the RVE model of the cell level and applied it to the module, so that the behavior of the jellyroll was not described at the cell level3). However, previous studies have mainly analyzed battery degradation caused by vibration and shock tests based on electrical characteristics. Hence, further research on damage and numerical models of battery cell levels that cause degradation according to random vibration and shock tests is required.In this study, anode, cathode, and separator of a pouch cell were prepared in form of a rectangular specimen with notch to conduct vibration and shock tests using the UN 38.3 standard test. The three battery cell components were stacked on a vibration jig, as in a real pouch cell. Scanning electron microscope (SEM) was used to investigate whether a fracture like crack occurred due to a vibration test near the notch of the specimen with a. Additionally, a numerical model for the pouch cell was constructed using a representative sandwich (RS) model4), and the predicted fracture behavior of the battery components according to the vibration and shock test was analyzed. The RS model provided a simplified representation of the internal structure of a battery cell, and the mechanical parameters required to build the RS model were obtained through tensile tests of battery cell components. Brand, Martin J., et al. "Effects of vibrations and shocks on lithium-ion cells." Journal of Power Sources 288 (2015): 62-69.Berg, Philipp, et al. "Durability of lithium-ion 18650 cells under random vibration load with respect to the inner cell design." Journal of Energy Storage 31 (2020): 101499.Jin Chul Yun. "Study on mechanical behavior of lithium ion battery using multi-scale analysis.". (2017). Pohang University of Science and Technology, PhD dissertationZhang, Chao, et al. "A representative-sandwich model for simultaneously coupled mechanical-electrical-thermal simulation of a lithium-ion cell under quasi-static indentation tests." Journal of Power Sources 298 (2015): 309-321.