https://wccftech.com/future-iphones-ipads-and-macbooks-to-have-larger-space-for-batteries-as-apple-adopts-slimmer-chips/

While Apple uses competitive-sized batteries for its iPads and MacBooks, it does need to up the capacity for its iPhones, though its makes up that margin through software optimizations. Fortunately, that might change, with a new report claiming that Apple may adopt slimmer peripheral chips for its aforementioned product line.

Apple is expected to massively adopt IPDs or integrated passive devices for peripheral chips in future iPhones, iPads, and MacBooks, according to a DigiTimes report. Since the new chips will be smaller in size, these will also be designed in such a manner that allows for higher performance and deliver space conservation, which in turn will be highly useful, since the vacant area can be used for bigger batteries.