Activated graphene makes superior supercapacitors for energy storage

According to researchers, the material can be incorporated into 'supercapacitor' energy storage devices with high storage capacity while retaining fast energy release, quick recharge time and a lifetime of at least 10,000 charge/discharge cycles. "These properties make this new form of carbon particularly attractive for meeting electrical energy storage needs that also require a quick release of energy," said Brookhaven materials scientist Eric Stach. "It could be used, for instance, in electric vehicles, or to smooth out power availability from intermittent energy sources, such as wind and solar power." Because most supercapacitors cannot hold nearly as much charge as batteries, their use has somewhat been limited to applications where smaller amounts of energy are needed quickly or where long life cycle is essential, such as in mobile electronic devices. The scientists say that this new material, which was developed at The University of Texas, Austin, could change that, adding that supercapacitors made from the material have an energy storage capacity, or energy density, approaching that of lead acid batteries. According to the researchers, they retain the high power density characteristic of supercapacitors. "This new material combines the attributes of both electrical storage systems," said University of Texas team leader Rodney Ruoff. "We were rather stunned by its exceptional performance. Our studies revealed that the material's three dimensional nanoscale structure consists of a network of highly curved, single atom thick walls forming tiny pores with widths ranging from 1 to 5nm, or billionths of a metre." The Berkeley team is still working to obtain a complete description of the material structure as well as adding computational studies to help understand how this three dimensional network forms. Once established, this can potentially tailor the pore sizes to be optimal for specific applications, including capacitive storage, catalysis and fuel cells. Meanwhile, the scientists say the processing techniques used to create the new form of carbon are readily scalable to industrial production. "This material - being so easily manufactured from one of the most abundant elements in the universe - will have a broad impact on research and technology in both energy storage and energy conversion," concluded Ruoff.