Lithium-ion cell response to mechanical abuse: Three-point bend
Johanna K. Stark Goodman, J.T. Miller, Steven M. Kreuzer, Joel C. Forman, Sungun Wi, Jae‐Man Choi, Bookeun Oh, Kevin White
Abstract
Previous studies have investigated the conditions required to immediately initiate thermal run-away, however there is little information available about the development of internal cell defects in abused cells that lead to thermal run-away or failure as a result of continued cycling. In this study cells are subjected a three-point bending abuse at levels that physically damage the cells but do not cause immediate thermal run-away. The abused cells are then cycled at multiple temperatures for up to 1000 cycles. Samples were examined at 100, 200, 500 and 1000 cycles using techniques including electrical analysis, computed tomography X-ray imaging, destructive physical analysis, and cross-section analysis. The electrical performance (capacity, impedance) of the abused cells was not significantly different than that of the control group. The damage imposed during the abuse protocol did not lead to thermal runaway of the cells used in this study; instead, failures presented themselves as high resistance short circuits that were sometimes not apparent during cell cycling. It is hypothesized that these short circuits formed during cycling as a result of the natural expansion and contraction of the electrodes.