USB3 has charging standards which allow for much more power.
I don't think any manufactures have added support for it yet though.
Profile 1 - 5V @ 2A
Profile 2 - 5V @ 2A or 12V@1.5A
Profile 3 - 5V @ 2A or 12V@3A
Profile 4 - 20V@3A
Profile 5 - 12V or 20V at 5A (100W).
I believe the idea around profile 5 is so laptops can drop the custom power connector and use a USB3 port instead.
It makes things interesting if all laptop USB ports support all power profiles. You could charge one laptop from another and even make a figurative 'energy black hole' by looping the charge back again with another cable.