Xbox Series X controller will continue to use AA batteries like it did with the Xbox One and Xbox 360 controllers, Microsoft has advised.
~Jason Ronald at Microsoft.What it comes down to is when actually talking to gamers, it’s kind of polarising and there is a strong camp that really want AAs.
As Ronald says, you get the best of both worlds; we recommend a battery pack that can be charged by USB-C, but would also recommend having a handful of rechargeable AAs on hand too.So just giving flexibility is the way to please both [sets of] people… You can use a rechargeable battery pack and it works just like it does on the Elite, [but] it is a separate thing.
The Xbox Series X is scheduled for Holiday 2020.