Researchers at The University of Texas at Austin's Cockrell School of Engineering have created a new porous, three-dimensional carbon that can be used as a greatly enhanced supercapacitor, holding promise for energy storage in everything from energy grids and electric cars to consumer electronics.
The findings of the group, led by materials science and mechanical engineering Professor Rodney S. Ruoff, will be published May 12 by Science magazine in its online publication ScienceXpress.
The significance of the discovery by Ruoff's team, which included postdoctoral fellow Dr. Yanwu Zhu and graduate students Shanthi Murali and Meryl Stoller, is the potential it offers for enabling supercapacitors to deliver significantly more charge, opening the doors to many potential unprecedented uses for this type of electrical energy storage device.
Supercapacitors are known as the "sprinters" among electrical energy storage devices, able to deliver energy much faster and more efficiently than batteries, but usually holding much less electrical charge, while batteries are like marathon runners, delivering energy slowly, but steadily.
"We synthesized a new sponge-like carbon that has a surface area of up to 3,100 square meters per gram (two grams has a surface area roughly equivalent to that of a football field). It also has much higher electrical conductivity and, when further optimized, will be superb for thermal management as well," Ruoff said. "The processes used to make this porous carbon are readily scalable to industrial levels.
"After we realized that we had a new carbon with a highly novel structure that showed superb performance as an electrode, we knew that this direction of research -- to create carbon materials that consist of a continuous three-dimensional porous network with single-atom-thick walls -- was likely to yield the optimum electrode material for supercapacitors."
The University of Texas at Austin's Office of Technology Commercialization has filed a patent with the U.S. Patent Office on behalf of the inventors.
"Rod and his team define what we mean when we talk about innovation to address grand challenges," said Gregory L. Fenves, dean of the Cockrell School of Engineering. "This team of students, researchers and faculty has discovered a way to improve the efficiency of supercapacitor energy storage."
Ruoff's research team of about 40 people collaborated with faculty and students from The University of Texas at Dallas, scientific staff at Brookhaven National Laboratory in New York and staff members at QuantaChrome Instruments in Florida.
The process used by the university team to synthesize the carbon material involved using microwaves to exfoliate graphite oxide, followed by treatment with potassium hydroxide, which created a carbon full of tiny holes -- essentially a sponge that, when combined with an electrolyte, can store a giant electrical charge. The team at Brookhaven then analyzed the atomic structure of the carbon material at the nanoscale using very high resolution electron microscopes. Their observations confirmed Ruoff's hypothesis that the carbon was a new three-dimensional material having highly curved, single-atom-thick walls that form tiny pores.