Published on Friday August 18, 2006
Drexel University researchers and colleagues from the Université Paul Sabatier in France have published the first ever paper in Science magazine related to supercapacitors (J. Chmiola, G. Yushin, Y. Gogotsi, C. Portet, P. Simon, and P. L. Taberna, "Anomalous Increase in Carbon Capacitance at Pore Sizes Less Than 1 Nanometer," Published online 17 August 2006).
As scientists look to tomorrow to find the problems that need to be addressed today, one clearly stands at the top of the list: energy. Increasing the efficiency of energy storage devices is the driving force behind Chmiola, et al’s work.
Supercapacitors, most commonly used in backup power applications where their indefinite lifespan makes them the most attractive candidates, are also finding increased usage in personal electronic devices, mobile phones, and hybrid electric/fuel cell vehicles for their improved power over batteries. Other benefits, such as short charging times and low performance fading at low temperatures, could open up new applications such as electric buses that recharge at predetermined stops.
Chmiola is a Ph.D. student and a National Science Foundation Integrative Graduate Education and Research Traineeship (IGERT) and Graduate Research Fellow. He is advised by Dr. Yury Gogotsi, Professor of Materials Science & Engineering and Director of the A.J. Drexel Nanotechnology Institute.Though supercapacitors are already an emerging industry, improvements are continually being made. Specifically, the work reported in Science deals with the design of porous carbon material which can be used as electrodes in supercapacitors. Careful design of the pore size of this material, according to lead author John Chmiola, “may be the key to realizing all of these goals.”
“Unlike batteries and fuel cells that harvest energy stored in chemical bonds,” Chmiola explained, “supercapacitors exploit the electrostatic separation between electrolyte ions and high surface area electrodes, typically carbon. Finding the optimal pore size to maximize surface area while minimizing the effect of constricting ions in too small pores has remained the holy grail of electrode research, however. Historically, the design protocol for supercapacitor carbons was to produce the largest surface area with the largest pore size possible.”
“Our recent results challenge this long-standing practice,” Chmiola continued. “When we realized that we could improve performance further by looking at the lower end of the pore size spectrum, into a range thought to be previously inaccessible, we knew that we stumbled onto something very special."
According to this work, decreasing the electrode pores below 1 nm can lead to smaller, lighter, more powerful supercapacitor devices. “Supercapacitors stand to become a new means to power the world,” Gogotsi said. “This work may also have implications for understanding ionic transport in narrow channels in many other systems, including cells in human bodies.”
Reference to this work also appeared in a number of print and online publications including the "News of the Week" section of Science,Financial Times Deutschland, Nature,EuroNanotechNews.com, and Nanotechweb.org