The KGI Securities analyst has predicted a 5.8-inch iPhone X Plus or iPhone X2 introduced next year could boast a battery capacity between 2,900mAh and 3,000mAH.
The next-generation model is rumoured to have a similar industrial design to the iPhone X, with its edge-to-edge screen and vertically-aligned dual-camera.
However, the increased battery capacity may not necessarily be used to improve battery life on the device, the prominent analyst has speculated.
Instead Apple may need to use the extra capacity to power newer features in its phones.
For example, this year the Cupertino-based company added its new front-facing TrueDepth Camera system on the iPhone X, which combines an infrared camera, flood illuminator and dot projector to map the user’s facial features.
These advanced features often come at the expense of additional battery life.
In the past, Apple has not offered dramatic battery life increases between generations of iPhone.
According to Ming-Chi Kuo, the new iPhones will employ the same L-shaped battery design debuted in the iPhone X.