consider this possibility... you are starting out with a false assumption and then trying to build on that.Yes insulation all around.
Is there documented reasoning why water would be a bad idea to cool cells down and prevent a thermal runaway from affecting other cells?
-Airlines use water
-Tesla says use a lot of water
-The Netherlands drops a smoking BMW in tank of water.
I am hoping for arguments less opinions.
First: Your assumption is that "water" will put out a fire due to oxygen isolation and temperature reduction(this is why water is great are putting out almost everything else that is "burning" (oxidation))...this is wrong for the lifepo4 chemistry.
neither oxygen nor external high temperature are needed once the runaway has started
second: Your assumption from tesla/others to use "water" on lithium battery fires is to put it out...this is wrong for life4 chemistry, they are NOT trying to put it out.
The battery discharge is self sustaining once you have reached the point of mechanical failure and internal shorting; water does nothing to stop that. The reason tesla recommends water, and a LOT of water, is just to contain the reaction and not allow it to spread...and by water they mean an insane amount of water, thousands of gallons. It does not stop the failed battery from the runaway reaction which will run until it is spent, anything touching that battery will go up as well.
My lithium batteries are on a cart (harbor freight steel hand cart!) and in the event of a runaway it is unplugged and rolled outside...