Statistical Characterization of 18650-Format Lithium-Ion Cell Thermal Runaway Energy DistributionsEffective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing vs. through the ejecta material. A unique calorimeter was utilized to examine the TR behavior of a statistically significant number of 18650-format Li-ion cells with varying manufacturers, chemistries, and capacities. The calorimeter was designed to contain the TR energy in a format conducive to discerning the fractions of energy released through the cell casing vs. through the ejecta material. Other benefits of this calorimeter included the ability to rapidly test of large quantities of cells and the intentional minimization of secondary combustion effects. High energy (270 Wh/kg) and moderate energy (200 Wh/kg) 18650 cells were tested. Some of the cells had an imbedded short circuit (ISC) device installed to aid in the examination of TR mechanisms under more realistic conditions. Other variations included cells with bottom vent (BV) features and cells with thin casings (0.22 1/4m). After combining the data gathered with the calorimeter, a statistical approach was used to examine the probability of certain TR behavior, and the associated energy distributions, as a function of capacity, venting features, cell casing thickness and temperature.
Document ID
20170011599
Acquisition Source
Johnson Space Center
Document Type
Presentation
Authors
Walker, William Q. (NASA Johnson Space Center Houston, TX, United States)
Rickman, Steven (NASA Johnson Space Center Houston, TX, United States)
Darst, John (NASA Johnson Space Center Houston, TX, United States)
Finegan, Donal (National Renewable Energy Lab. Golden, CO, United States)
Bayles, Gary (Science Applications International Corp. Houston, TX, United States)
Darcy, Eric (NASA Johnson Space Center Houston, TX, United States)