The surface area of a single graphene sheet is 2630 m2
/g, substantially higher than values derived from BET surface area measurements of
activated carbons used in current electrochemical double layer capacitors. Our group has pioneered a new carbon material that we call
chemically modified graphene (CMG). CMG materials are made from 1-atom thick sheets of carbon, functionalized as needed, and here we
demonstrate in an ultracapacitor cell their performance. Specific capacitances of 135 and 99 F/g in aqueous and organic electrolytes, respectively,
have been measured. In addition, high electrical conductivity gives these materials consistently good performance over a wide range of
voltage scan rates. These encouraging results illustrate the exciting potential for high performance, electrical energy storage devices based
on this new class of carbon material.