Artillery shells (without the fuse installed) are about as inert as it gets.
These things have to survive getting launched in excess of 10,000 G’s initial acceleration.
Now, extended exposure to a high temperature fire is a different story. By that time the crew is already expired though.
I’ll pick munitions any day over lithium batteries.
https://avherald.com/h?article=4fbc119a&opt=0