Not silly at all, and that might be exactly what they do!

If they could coat, or layer it, in a reactant or catalyst that made the hydrogen sulphide has less harmful or toxic it may work, so if the battery is damaged some of the toxic gas will be reduced to something less harmful.

Maybe a chemist would know if this is possible

The premise is that the enclosure is already somehow breeched. Squeezing a battery is bad and it makes bad situations worse.

The thing is, batteries can weight half a ton. At triple the energy density they could almost armor plate it to tank levels. I imagine most of us aren't under Javelin attack during road trips :-p

Funny but there's still corrosion, cracking, and holes to connect wires to the battery.