2020 iPhone could have a slightly larger battery from small internal change
Despite having a probably more energy-efficient mobile operating system, iPhone owners have been begging Apple for a larger battery. Those prayers have been answered, to some extent, when Apple launched the larger iPhone 6 and iPhone 6s. Of course, the need for more hours of battery life never ends and Apple may be giving next year's iPhones just a wee bit more battery not by enlarging the iPhone yet again but by shrinking at least one part inside.
Smartphone batteries have always been a delicate balancing act. Put in too little and users will complain about short battery lives. You can't simply cram in too much either and risk compressing the battery or expanding the phone to be too big. Aside from increasing the size of the phone, the only other way to put in more battery capacity is either to improve battery technology or, more realistically, make room for it by pushing or shrinking other parts inside.
The latter might be the reason the 2020 iPhone might have a higher capacity battery than this year's models but don't expect too much. The difference might not be so big in the end. And Apple isn't really making an active effort to add more battery. It's just a side effect of a new and smaller component.
MacRumors reports that next year's iPhones will have a smaller battery protection module circuit, the part that keeps batteries from overcharging. Thanks to new technology from supplier ITM Semiconductor, that module shrinks almost by half, from 50 mm long and 1.80 mm thickness down to 26 mm length and 1.00 mm thickness. That, in turn, could help Apple push the limits of the battery just a small bit and, when it comes to batteries, every little bit counts.
The 2020 iPhones do seem to have a lot of nifty features expected for it, including having OLED on all models and even a fingerprint sensor. This early in the game, however, not all of those may make the cut but a larger battery might be more appreciated than other fancy features.