Samsung is working on "denser" mobile batteries due out by 2017

With this announcement Samsung is projecting 700Wh/l (Watt-hours per liter), moving to 750Wh/l by year's end for consumer electronic phone batteries and 780 Wh/L by 2017. They will be able to provide more battery life in the same sized device which is critical for portable electronics. The article states that they're achieving this by moving to higher voltage 4.3 to 4.4 to 4.5V  and that it will give better battery life. Don't confuse the author's term battery life for calendar lifespan but it is time needed between charges. Higher voltage systems may put more strain on the materials within which may cause damage and shorten the lifespan.

http://www.phonearena.com/news/Samsung-is-working-on-denser-mobile-batteries-and-slimmer-camera-sensors-due-out-by-2017_id69681