3. A capacitor stores charge between two plates, and discharges quickly; they are common in electronics and used to power camera flashes. Capacitors can store a lot of charge, and supercapacitors, which are typically made with layers of ordinary carbon, can store more. But capacitors still can't hold much power per unit of weight. That is why batteries are used for electronics.
Graphene could change that. It can be etched with a laser to create more surface area and in turn allow a capacitor to store way more energy than its ordinary carbon brethren. Capacitors can also go through many more cycles than batteries without failing. In the future, graphene supercapacitors could power electronics and even electric cars.