You'd want more than one cell. You'd be pulling 23amps from a 4.2v 18650 to give the same 100w at 20v power as you get from a top usbpd power supply.
There are 18650s that do 30 amps for short bursts, but it would get as hot as the iron and be empty in 5 min
I've got a Ts80p which is a qc3 usbc soldering iron for that. It's crazy powerful for it's size and runs off a pretty small anker powerbank. You could slide that into your sleeve to go portable and one handed