Drexel University's Yury Gogotsi and colleagues recently needed an atom's-eye view of a promising supercapacitor material to sort out experimental results that were exciting but appeared illogical. That view was provided by a research team led by Oak Ridge National Laboratory (ORNL) computational chemists Bobby Sumpter and Jingsong Huang and computational physicist Vincent Meunier.
Gogotsi's team discovered you can increase the energy stored in a carbon supercapacitor dramatically by shrinking pores in the material to a seemingly impossible size—seemingly impossible because the pores were smaller than the solvent-covered electric charge-carriers that were supposed to fit within them. The team published its findings in the journal Science.
The mystery was not simply academic. Capacitors are an important technology that provides energy by holding an electrical charge. They have several advantages over traditional batteries—charging and discharging nearly instantaneously and recharging over and over again, almost indefinitely, without wearing out—but they also have drawbacks—most importantly, they hold far less energy.
An electric double-layer capacitor, or supercapacitor, represents an advance on the technology that allows for far greater energy density. While in traditional capacitors two metallic plates are separated by a nonconducting material known as a dielectric, in a supercapacitor an electrolyte is able to form an electric double layer with electrode materials that have very high surface areas.
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