This particular battery will supposedly point to a larger capacity compared to the existing iPhone 6s, which means that Apple might have found a way to introduce even more battery capacity into a smaller frame, with the very real possibility of an all-new casing material.
The alleged iPhone 7 images and details claim that it was an Apple battery that will feature a 7.04Whr capacity. Should this rumor turn out to be true, then it would surely be larger compared to the 6.61Whr battery that sees action in the existing iPhone 6s. However, since we do not have the corresponding voltage, then it is difficult to determine the true capacity of the battery where milliampere-hours is concerned. Logic does dictate that a larger watt-hour rating might end up in a greater capacity battery. Ah well, as with all rumors, only time will be able to tell as to whether it is true or not.