TSMC is the chip manufacture for all Apple chips and rumor has it Apple A18 processor for the iPhone 17 will make use of 3nm manufacturing process. This means the next generation of iPhone will have even better battery life even if battery size does not change.
This would also allow Apple to make iPhone 17 thinner by using a smaller battery size since the newer chip will be more efficient and powerful.
In fact, there are plans to switch to 2nm process in 2025. TSMC is building two facilities for the upcoming 2nm manufacturing process and Apple has asked them to make another one, brining total manufacturing units to three.
This also implies iPhone 18 will use 2nm while iPhone 17 will get to use 3nm, which is still praise-worthy.
Apple is the main customer of TSMC and gets higher priority over phone manufactures due to sheer volume of iPhone, iPad and Macintosh computers. With more facilities, TSMC would be able to produce a lot more chipsets for Apple. In fact, we are expecting it to shell out 50% more chipsets next year compare to what it produces right now.