Two newly discovered Apple patents reveal how the company may be working to improve the battery life of its devices. One seeks to eliminate potential wasted space inside an iPhone while the other would utilize smart technologies to control battery swelling.
https://www.notebookcheck.net/Apple-patent-points-to-larger-batteries-in-future-iPhones-by-eliminating-wasted-space-and-using-anti-swelling-tech.527549.0.html