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Atlanta, GA | Posted: December 11, 2013
Energy storage comes into play for many products: portable electronics, electric vehicles, power tools, military applications, spacecraft and satellites, as well as renewable energy. One way to provide improved storage capacity in energy storage devices is through the use of carbon nanomaterials, according to Dr. Billyde Brown, who spoke at a Nov. 4 Georgia Tech Manufacturing Institute Brown Bag Seminar.
Dr. Brown recently joined GTMI as a Research Associate with a focus on manufacturing deployment for nanotechnology. Carbon nanomaterials, he noted, are used in energy storage devices to improve energy storage capacity, provide faster recharge, minimize self-charge, provide lighter weight components and offer longer cycle life. In fact, Dr. Brown noted, research in carbon nanomaterials for energy storage is being driven by the environmental benefits offered by electric vehicles. “According to the U.S. Department of Energy, vehicle electrification reduces our dependency on foreign oil by more than 60 percent and greenhouse gases by 40 percent,” he said.
One focus of current research is the use of supercapacitors in electric vehicle powertrains. Supercapacitors bridge the gap between conventional capacitors and rechargeable batteries. “We are always trying to match the energy and power density of the internal combustion engine,” said Dr. Brown. “By developing hybrid storage systems consisting of supercapacitors and lithium batteries, we can help bridge that gap.”
“Batteries have electro-chemical reactions where charge is transferred across the electrode/electrolyte interface but, in supercapacitors, there is no chemical reaction, charge is simply accumulated at the interface,” Dr. Brown continued. “Batteries have problems with the decomposition of electrolyte and electrode corrosion, so the cycle life of a battery is much less than supercapacitors.”
The current electrode material for supercapacitors, Dr. Brown explained, is activated carbons, but research in new materials for supercapacitors is focused on advanced carbon nanomaterials (ACN). ACNs are not currently on the market because they have a much higher cost than activated carbons. But they offer many advantages over the current materials in that they provide an ultra-low resistivity, lower pore resistance, lower contact resistance, higher specific capacitance, and enhanced chemical stability. That is why there is a “trend toward using nanostructured carbons such as carbon nanotubes and graphenes in supercapacitors; and these same materials as supports for new sulfur and silicon electrodes in lithium batteries,” Dr. Brown said. “These materials can ultimately improve driving range, fuel economy, cost, performance, and reliability of electric vehicles.”
But moving these materials into mainstream manufacturing processes will take some time. “Tens of billions of dollars have been invested in nanomaterials because they offer great promise,” said Dr. Brown. “But they have shown little return. Scalability and manufacturing methods for easy incorporation into products are the two major stumbling blocks.”
Dr. Brown’s presentation was part of the GTMI Brown Bag Seminar Series, which takes place each Monday between noon and 1 p.m. in the Manufacturing Research Building, Room 114. Students and faculty are invited and are welcome to bring their lunch to the meeting. If you have questions or you want to be added to the reminder list for these events, please contact Tina Guldberg at tina.guldberg@gatech.edu.
