[mdaEyebot]

I suppose a leak would be serious, but presumably these sorts of large-scale batteries would be buried in a containment unit.

Flywheel batteries are usually placed in small bunkers, because the failure mode of a giant rapidly-spinning concrete wheel jumping its bearings is not exactly pretty. Dams are usually designed with diversion channels and mechanisms to limit the damage if they burst. Etc.

Really, it's strange that we are so cavalier about lithium battery failures compared to the other sorts.