The company ibattz has created a battery pack made to fit easily on an iPhone case. Most of the battery packs for mobile devices tend to be bulky, making the case not convenient for the pocket. The Mojo Hi5 Power Bank Case has a 2500 mAh battery that increases battery life up to 150 percent.
Other features include pass through charging support which can charge both the power bank and the iPhone 5 at the same time. It can also charge other mobile devices that are powered by USB.
If you want to get in on this type of charging for the iPhone, head over to the ibattz site and pay about $79.90 for it.