Back in 2010, scientists Andre Geim and Konstantin Novoselov of the University of Manchester won the Nobel Peace Prize for discovering that graphene, an allotrpe, could be used as a basic component in the development of a “supercapacitor”, among other things. While graphene is considered to be one of the most versatile materials ever discovered, one of its abilities is storing and transferring high amounts of electrical energy. Due to single layered honeycomb crystal lattice structure, it can also be implemented into some of the smallest of spaces.
Moving ahead to 2012, UCLA’s Richard Kaner and Maher El-Kady discovered a very cheap, “home made” way of producing graphene by covering plastic discs with graphite oxide solution and running them through standard DVD burners to be bombarded by laser light. It was a huge discovery, not only because it was much cheaper to produce, but because they accidentally stumbled upon its ability to store high amounts of electric charge that could be used of a long and distributed period of time.
In simple terms, graphene is a much more efficient electrical energy storage material versus the more traditional chemical-based batteries such as lithium ion and lithium polymer units. What it does is take the longevity offered by regular batteries and combines it with the high energy output offered by capacitors.. It can be charged in 100-1000th the time it would take to charge a regular battery but still maintain a charge longer than said traditional storage units.
While the discovery was very important, back then they were limited to a smaller scale production of about 100 micro-supercapacitors in 30 min or less per disc. The same scientists have now announced via a UCLA press release that a far more efficient method of production has been found.
Kaner and El-Kady took advantage of a new structural design during the fabrication. For any supercapacitor to be effective, two separated electrodes have to be positioned so that the available surface area between them is maximized. This allows the supercapacitor to store a greater charge. A previous design stacked the layers of graphene serving as electrodes, like the slices of bread on a sandwich. While this design was functional, however, it was not compatible with integrated circuits.
In their new design, the researchers placed the electrodes side by side using an interdigitated pattern, akin to interwoven fingers. This helped to maximize the accessible surface area available for each of the two electrodes while also reducing the path over which ions in the electrolyte would need to diffuse. As a result, the new supercapacitors have more charge capacity and rate capability than their stacked counterparts.
Interestingly, the researchers found that by placing more electrodes per unit area, they boosted the micro-supercapacitor’s ability to store even more charge.
The new micro-supercapacitors are also highly bendable and twistable, making them potentially useful as energy-storage devices in flexible electronics like roll-up displays and TVs, e-paper, and even wearable electronics.
The researchers showed the utility of their new laser-scribed graphene micro-supercapacitor in an all-solid form, which would enable any new device incorporating them to be more easily shaped and flexible. The micro-supercapacitors can also be fabricated directly on a chip using the same technique, making them highly useful for integration into micro-electromechanical systems (MEMS) or complementary metal-oxide-semiconductors (CMOS).
This opens up the possibility of developing batteries for popular consumer electronics that so heavily depend on battery usage. Instead of having to wait for your phone to charge in 3 or more hours, you could be at full capacity in just a few minutes. The same technology could be applied to electrical cars, significantly cutting down charging times.
[Cover Photo: UCLA]