This looks well advanced and could be a threat to many other storage technologies
"Currently the cost to manufacture a lithium battery is about $500 (USD) per/ kWh. Tesla recently announced a Super Factory to be built in Nevada, with a promise to get the price of lithium batteries down to $150 USD per kWh by 2020, our current cost estimated for this type of graphene base supercapacitor is about $100 per kWh today and we feel confident we should be able to cut this pricing in half by the end of 2015″[/font][/size]
http://revolution-green.com/sunvault-energy-graphene-based-supercapacitor/
Kind Regards
Mark