I believe there might be an issue with capacitors requiring rare-earth materials so therefore can't scale. http://www.sciencedirect.com/science/article/pii/S02

I believe there might be an issue with capacitors requiring rare-earth materials so therefore can't scale. http://www.sciencedirect.com/science/article/pii/S0272884212004774 http://www.sciencedirect.com/science/article/pii/S0272884212... It sounds like the energy density still doesn't match batteries though there may be breakthroughs that might fix it: http://www.teslarati.com/supercapacitor-breakthrough-evs-charge-in-seconds/ http://www.teslarati.com/supercapacitor-breakthrough-evs-cha...