  Supercapacitors, based on the fast ion transportation, are specialized to
provide high power, long stability, and efficient energy storage with highly
porous electrode materials. However, their low energy density and specific
capacitance prevent them from many applications that require long duration.
Using a scalable nanoporous graphene synthesis method involving a simple
annealing process in hydrogen, here we show graphene supercapacitors capable of
achieving a high energy density comparable to what Li-ion batteries can offer,
but a much higher power density. Ultra-high specific gravimetric and volumetric
capacitances are achieved with highly porous graphene electrodes. Moreover, the
supercapacitors assembled with graphene electrodes show excellent stability.
Our results demonstrate that by synthesizing graphene materials with an ideal
pore size, uniformity, and good ion accessibility, the performance of
supercapacitors can be revolutionized.
