ZeroLemon is known for making battery cases, and they have one of the biggest we've seen yet for the Galaxy S7 Edge. This durable TPU and polycarbonate hard-shell case completely protects the phone, but then adds an extra 8,500 mAh of battery. As a comparison the Galaxy S7 Edge is 3,600 mAh so this case is more than double. Meaning users can go 2-3 days on a single charge.
The ZeroLemon case will charge your phone and can even recharge other devices with its huge built-in battery. The only downside is it's almost as big as a brick. Look at the picture, then decide if you'll be able to carry that around and if it's worth the $64.99 price.