A complete non story. The phone was damaged before the battery went up. Could be a shard of glass from the screen punctured the battery causing it to fail entirely.
I watched a science show recently about batteries, the Lithium-ion will all explode if crushed or punctured. This is nothing iPhone specific.
An inventor they featured has come up with an alternative that can be cut or punctured with no issues. I assume it will make its way to the marketplace soon.