Effects of electrolyte, loading rate and location of indentation on mechanical integrity of li-ion pouch cells

The safety of lithium-ion batteries under mechanical abuse conditions is an essential feature where these cells are used in mobile applications such as electric vehicles. In recent publications, punch testing has been used as a benchmark to study the mechanical abuse tolerance of the cells. What has not been studied in depth is how various test conditions such as the loading rate or the location of indentation affect the response of the cell. This paper quantifies the effects of four important test variables on the results of mechanical indentation tests. The first factor studied was to what degree tests on dry dummy cells without electrolyte can predict the response of a production cell. Then the effects of loading location, center versus on the edge, was evaluated. The speed of the test, at quasi-static rates, was the third variable. The last test characteristic studied was the repeatability of punch loading experiments. After completing the test program, a finite element model was developed to simulate the response of all studied cases. The model showed good predictability of load-displacement response and the onset of short circuit under all loading scenarios studied in this research.