disturbing information on lithium ion batterys

[billy_wizz 2]

Right then i phoned a local battery supplier about buying a 12 volt lithium ion battery and he said they could get me one in but don't stock them but what did i want it for after explaining it was for a lamp he suggested i use any thing but lithium ion first reason because if it gets damaged the lithium will combust with contact with the air and the second reason being its propensity to expand he was saying he had a 3 mil battery that had expanded to 15 mil and they where looking into why as it was a common fault! has anyone else herd anything like this or is he just having fun at my expense? I cant say he was trying to sell me something he had in stock because he told me to keep my old lead acid one never even tried to sell me a new one!