Thermal runaway in lithium-ion batteries is a significant safety concern, particularly in large-scale energy storage systems. In such scenarios, the release of combustible gases and ejected particles can lead to fire propagation. Although these phenomena have been studied extensively, the interaction between electric arcing resulting from the opening and closing of switches or contacts through relays or fuses, and vented gases, remains an important and unexplored safety issue.

This study therefore investigates the conditions under which electric arcs may ignite the vented gas mixture during thermal runaway events. Specifically, the interaction between electric arcing and the gases released during cell venting are examined, taking into account factors such as battery chemistry, gas concentration, distance and gas temperature. To facilitate this investigation, our in-house testing setup has been adapted to incorporate a device for simulating electric arcs at user-defined moments.
Test results show that no ignition of vented gases was achieved despite extensive parameter modifications. The gas volume was increased by a factor of four, reaching the upper explosion limit. In addition, the fuse position was systematically varied to assess arc–gas interaction; however, no observable effects were detected with respect to distance variation or the associated increase in gas temperatures. Furthermore, neither different gas stratification nor the expected species hotspots, such as an H₂-rich hotspot at the highest point of the test bench, showed any influence. The results were further validated using cells from a second manufacturer, with the number of cells scaled to achieve a comparable energy level.

To further probe these results, future work will aim to increase gas temperature and reactivity and to quantitatively analyze the gas composition. Moreover, investigations will be extended to NMC cells, with a particular focus on overcoming the challenge of initiating thermal runaway directly. Together with additional safety-oriented measures, these efforts have the potential to contribute to further improvements in the overall safety of lithium-ion battery systems.