I don't really care about the frequency, but like, you don't think that a bonded thermistor connected to a powder ejection charge would catch it? Thermocouple maybe?
I watched videos on youtube and it looks like the spew quite a bit of flames and rocket around, the C-whatever cylinderical ones, but I have no idea what surface temperature looks like before it happens.
I imagine the cells seated in sections of tubing protected by one way rejection leaf springs and some kind of curtain in kao-wool or other high temperature insulator, basically with a normally closed slit over each battery, so if one shoots out, it can rocket around in the trench behind the battery wall with most of its thermal energy being deflected by the high temperature insulation material towards the walls, which would need to be built to withstand quite a blast indeed, I am imagining something like 3/8 inch or more welded steel subsections. The whole box would vent to the outside incase a massive chemical fire ignited in it. I guess it would need to be tested with a few KG of fast thermite (copper etc)
It would need to be carefully designed not to function as a bomb, perhaps joule equivalent quantities of black powder can provide a worst case ovepressure event, since powder would burn much quicker then the batteries could explode even with the perfect storm, I think.