Users complained of overheating iPhone 15 models shortly after release, which Apple fixed via software, but the iPhone 16 is rumored to have a hardware solution, too.
Select iPhone 15 and iPhone 15 Pro models could overheat to the point of being uncomfortable to hold, at least until iOS 17.0.3. Apple blamed these conditions on poorly optimized software and issued a software fix, but more effective cooling may also help.
The iPhone 15 is already here and can't get a hardware change mid-cycle, but X user @KosutamiSan says Apple is working on a solution for iPhone 16. The company could switch to a graphene heat sink and a metal battery case to promote better heat transfer.
The iPhone is such a tiny object that there isn't much space for anything, especially thick or heavy heat sinks. Graphene is an excellent material for a heat sink because it has ten times more thermal conductivity than copper.
The iPhone has no fan, so heat has to be dissipated through the device frame into the air using passive heat transfer. Heat sinks do precisely what the name implies, they remove heat from undesirable areas by having a more efficient thermal conduction value than the materials around it.
Graphene would perform better than the existing cooling mechanism, thus allowing the iPhone to deal with more heat more efficiently.
Apple has investigated many ways to cool the iPhone down but hasn't changed much beyond using different heat sinks. Ming-Chi Kuo suggested Apple could use vapor chambers at one point, while a patent pointed to magnets as a solution.
However, those options are cost-prohibitive and require radical design changes. Graphene may be the perfect solution to keep the iPhone 16 from overheating if the rumor proves true.
Kosutami is a known leaker that collects design validation test products and other such pre-production items. The leaker has a short history with accurate leaks like USB-C components for iPhone 15, but also some misses like with a supposed iPhone 15 Pro Thunderbolt cable. So, we're rating this leak as possible.