Dynamic impact tests on lithium-ion cells

This paper reports on dynamic abuse tests on Li-ion cells, namely investigations on local indentation/intrusion into these cells. Two different types of cells have been investigated, pouch cells and elliptic cells. The elliptic cells were tested in two different states, with and without liquid electrolyte. The cells have been loaded by a hemispherical punch with a diameter of 12.7 mm with velocities between 0.01 mm/s and 5000 mm/s. Intrusion force, intrusion depth and velocity, and cell voltage were measured with high time-resolution during the intrusion process. Significant changes in critical force were detected over the span of tested velocities. The critical force increased with an increase in test speed for the elliptic cells, while it decreased for the pouch cells. There were also differences associated with the presence of the electrolyte. These findings are of great importance especially for automotive applications where Li-ion battery packs are used in Hybrid or Electric Vehicles where intrusion at dynamic speeds is one of the main failure modes during a crash. The paper describes the experimental setup and test results in detail and discusses the implications.