http://news.rice.edu/2015/12/03/scientists-see-the-light-on-microsupercapacitors/
Its a laser-induced graphene (LIG). That is awesome, they produce it just by lasering polyimide. Hmm, I’ll actually have to buy the article to find out more. Not sure what power levels are needed, but you might be able to make the LIG with the glowforge. Doping it to make the positive and negative electrodes might be more difficult.
I’m very curious to see @volivaa take on this as well!
Edit: Looks like it might be a fiber laser. Not sure if that is necessary.