One of the key factors for anyone buying a smartphone is battery life. For some people, they can often justify having a slightly smaller battery if they know they’ll be at their desk or driving, so they can charge their phone during the course of the day. But for a many users, battery life is paramount. We’ve seen many companies globally continue to expand the size of their batteries, especially as second-generation Silicon Carbon technology enabled denser batteries without increasing thickness. But most of the devices on our current best phone battery life list max out at 5,000 mAh of…