Ok so that rules out phones, laptops and other devices that tend to get roughed up over time but I would still consider using it as energy storage for the solar panel on my house for instance.
As you have it isolated from the house in a specially built enclosure or garden shed it's less likely to get damaged and even if it is the damage can be manageable.
Then again in these cases it's more of a matter of how cheap it is vs the amount of energy it can hold and size doesn't matter a much.
Where weight and energy density is not a concern, you'd just use regular old-fashioned lead-acid. Lots of charge cycles, easily recycled, simple, no overheating, existing infrastructure.
When the Powerwall was announced, weren't people explaining one of the benefits over lead-acid based systems as you don't have to worry about accidentally generating noxious or explosive gases if the system isn't well vented? I just found something regarding that[1], but I'm unqualified to know how much of a problem this is in reality.
Well, outside my house at a safe distance. But yes, better batteries as a utility company thing don't need to be as safe since they can be outdoors behind a fence like a propane tank.
As you have it isolated from the house in a specially built enclosure or garden shed it's less likely to get damaged and even if it is the damage can be manageable.
Then again in these cases it's more of a matter of how cheap it is vs the amount of energy it can hold and size doesn't matter a much.