I've used lithium sulphur dioxide batteries in the Army and...

I've used lithium sulphur dioxide batteries in the Army and they're dangerous as all hell. Very lightweight but they can vent sulphur dioxide gas, don't know if these new ones under development will be the same but I breathed that gas in and had to attend the emergency department. The sulphur dioxide gas turns into sulphuric acid on contact with moisture such as in your lungs and throat, and is quite damaging. Sulphur dioxide gas is half the formula of the chemical weapon mustard gas. Also I think these batteries were banned from most aircraft at the time, but my memory is hazy there and I could be wrong.