IMO, the climate of the location for storage is more important than if they are in a safety bag/box. There are storage boxes you can buy, but you'll want to keep them in a cool, dry (moisture free) location. I've heard of some people storing them in freezers but that seems silly with lipos. That was what people did in the 80's with alkaline batteries. That being said, no reason not to store them in something secure and safe.