Many phones do this. Both my iPhone 6 and my iPhone 6s do this and more (usually two days). The issue here is that your use case is likely different than mine. It isn't enough to just say, "full day" without specifying full day doing what.
12 hours with the screen and WiFi or 3g always on. That would be amazing, and it doesn't sound that unachievable. I don't need ultraquadHD resolutions, even 720p is enough.
