14 DAY TRIAL // University of California in Los Angeles (UCLA) investigators announce the development of a new type of electrodes, to be used in advanced power sources that combine the power performance of capacitors with the high energy density of batteries.
Such a power source is the goal of numerous studies being conducted around the world. Scientists say that electrochemical capacitors (EC) are capable of storing huge amounts of electricity, but at a very low density. Therefore, they cannot be used as power sources on their own.
These components, also known among experts as supercapacitors or ultracapacitors, have therefore been left largely unused in electronic equipment. Their main problem was that their energy density was nowhere near as high as that found in standard batteries.
What the UCLA team did was basically develop electrodes that enable higher energy density in EC. These electrodes also needed to be able to maintain high conductivity, while simultaneously providing higher and more accessible surface area than conventional EC.
In the past, electrochemical capacitors used activated carbon electrodes. The research group developed electrodes based on graphene, a 2D, single-atom-thick compound of carbon that is obtained from graphite (the material making up pencil lead).
Graphene exhibits remarkable physical and chemical properties. It is the world's toughest known material, and is able to transport electricity better than copper. Physicists are still investigating it, but it would appear that the compound could even replace silicon as the basis for all electronic devices.
Interestingly, the graphene electrodes were produced using a standard LightScribe DVD optical drive. Details of how this was achieved are published in the latest issue of the top journal Science.
The research was a joint effort by scientists at the Department of Chemistry and Biochemistry, the Department of Materials Science and Engineering, and the California NanoSystems Institute.
“Our study demonstrates that our new graphene-based supercapacitors store as much charge as conventional batteries, but can be charged and discharged a hundred to a thousand times faster,” UCLA professor of chemistry & materials science and engineering, Richard B. Kaner, explains.
“Here, we present a strategy for the production of high-performance graphene-based ECs through a simple all solid-state approach that avoids the restacking of graphene sheets,” concludes UCLA graduate student and lead paper author, Maher F. El-Kady.