Measurement of Energy Distributed Between Cell Mass and Hot Ejecta during Thermal Runaway of Lithium Ion Cells at Varying State of Charge

Thermal runaway propagation is a major concern in battery packs constructed with large numbers of small lithium ion cells. This is especially true for battery applications involving manned space flight.

This work by NASA presents a scientific study that evaluates the thermal energy release of these cells during thermal runaway.  Specifically, these experiments compare, as function of state of charge, the energy retained in the cell mass versus energy released in ejected materials and hot gasses. In addition, this study evaluates the effect of state of charge on thermal stability, including onset of self-heating and thermal runaway temperature for three types of commercial cells.

Tests are conducted utilizing accelerating rate calorimeter (ARC) equipment using a heat wait seek heating algorithm combined with unique cell containment fixtures and properly placed thermal sensors to allow the aforementioned energy calculations. This work seeks to inform the development of thermal abuse models and aid the engineering design and development of non-propagating battery pack designs utilizing small lithium ion cells.