Most modern batteries like this are weatherproof and can be mounted outside the home. Most modern batteries use LiFePO4 chemistry, which while not perfect, is much less risky in terms of thermal runaway than older lithium ion batteries.

The Tesla Powerwall is only slightly larger than a pizza box and can be mounted directly on the wall. Most of the below images are outside the house, but some are also in the garage.

https://duckduckgo.com/?q=tesla+powerwall&ia=images&iax=imag...

This battery uses a safer type of lithium chemistry that is less prone to overheating, though no large battery is risk-free. Water is used by firefighters to cool battery fires (they can reignite tho).

Install it outdoors or in a detached garage, away from anything flammable. Never in a bedroom, hallway, or escape route.

There are newer batteries tech that can't inflame.