That's not how batteries work. The charging time is measured in "C"s which is a weird unit where 1C means you can fully charge the battery of any size in 1 hour

That's not how batteries work. The charging time is measured in "C"s which is a weird unit where 1C means you can fully charge the battery of any size in 1 hour. 2C means half an hour. But it's already independent of the size of the battery. You don't really get any increase on the max charging speed by dividing it up differently, any more than you can create cake by cutting a whole cake into pieces. The way to improve it is with battery chemistry, and probably with more capable power electronics.