Electronic insulation paper, home made alternatives?
Thermal runaway in Li-ion batteries begins at temperatures around 120-130°C. At this temperature, the passivation layer breaks down, releasing more heat as it breaks, and cell decomposition process becomes self-sustained and irreversible.



There is really no point in the insulator which can withstand more than 120°C, since a charged battery will inevitably catch fire at this point, reaching temperatures of 600°C or more. If you need an insulator which would withstand a catastrophic battery failure, you should put your battery in a hot-stop bag.