Source: There are "fillers" between cells that are endothermic, heat absorbing. This reduces the risk of a complete pack event. There are "separators" within the cells that upon heating, block ion transfer, turning off energy release by the cell. As for relative risks: NMC/NCA - heat and fire LFP - toxic gas with a lot of explosive hydrogen I am leaning towards battery pack safety regulation that incorporates both the "filler" around the cells and "separators" within the cells. Not something that needs to be done instantly and should not specific the specific media. Rather, a performance based, benchmarked solution. Bob Wilson
I consider my Tesla battery pack safe, while poorly designed NCA/NMC can be unsafe. LFP is safer, but of course you can mis design the pack and the battery management system to be less safe.
My takeaway was an endothermic filler between the cells. The fire hazard of Sherman tanks was resolved by ‘wet’ storage. The tank round racks had thin, antifreeze filled walls. This greatly reduced ‘cook off’ giving crews time to get out and often leaving a tank that could be repaired. Bob Wilson