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Improved supercapacitors for better batteries, electric vehicles

Improved supercapacitors for better batteries, electric vehicles | Science, Technology, and Current Futurism |

Researchers at the University of California, Riverside have developed a new graphene-based nanoscale architecture that improves the performance of supercapacitors, a development that could mean faster acceleration in electric vehicles and longer battery life in portable electronics.


A supercapacitor is an energy storage device like a battery. The new design is based on ruthenium oxide anchored on a graphene foam electrode. It could deliver two times more energy and power compared to supercapacitors commercially available today.


The foam electrode was successfully cycled over 8,000 times with no fading in performance. The findings were outlined in the journal Nature Scientific Reports (open access).


Supercapacitors (also known as ultracapacitors) have ultra-high charge and discharge rate, excellent stability, long cycle life, and very high power density.


To achieve a higher power density, it is critical to have a large electrochemically accessible surface area, high electrical conductivity, short ion diffusion pathways, and excellent interfacial integrity, which are achieved by the new architecture.


These characteristics are desirable for many applications including electric vehicles and portable electronics. However, supercapacitors may only serve as standalone power sources in systems that require power delivery for less than 10 seconds because of their relatively low specific energy. Higher capacitance, or the ability to store an electrical charge, is critical to achieve higher energy density. This is also enabled by the new architecture.

Via Dr. Stefan Gruenwald
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New device to store electricity on silicon chips themselves

New device to store electricity on silicon chips themselves | Science, Technology, and Current Futurism |

All the things that define us in a modern environment require electricity,” said Pint. “The more that we can integrate power storage into existing materials and devices, the more compact and efficient they will become.” New device stores electricity on silicon chips.


Solar cells that produce electricity 24/7, not just when the sun is shining. Mobile phones with built-in power cells that recharge in seconds and work for weeks between charges. These are just two of the possibilities raised by a novel supercapacitor design invented by material scientists at Vanderbilt University that is described in a paper published in the Oct. 22, 2013 issue of the journal Scientific Reports.


It is the first supercapacitor that is made out of silicon so it can be built into a silicon chip along with the microelectronic circuitry that it powers. In fact, it should be possible to construct these power cells out of the excess silicon that exists in the current generation of solar cells, sensors, mobile phones and a variety of other electromechanical devices, providing a considerable cost savings.


“If you ask experts about making a supercapacitor out of silicon, they will tell you it is a crazy idea,” said Cary Pint, the assistant professor of mechanical engineering who headed the development. “But we’ve found an easy way to do it.”


Instead of storing energy in chemical reactions the way batteries do, “supercaps” store electricity by assembling ions on the surface of a porous material. As a result, they tend to charge and discharge in minutes, instead of hours, and operate for a few million cycles, instead of a few thousand cycles like batteries.


“The big challenge for this approach is assembling the materials,” said Pint. “Constructing high-performance, functional devices out of nanoscale building blocks with any level of control has proven to be quite challenging, and when it is achieved it is difficult to repeat.” 


With experience in growing carbon nanostructures, Pint’s group decided to try to coat the porous silicon surface with carbon. “We had no idea what would happen,” said Pint. “Typically, researchers grow graphene from silicon-carbide materials at temperatures in excess of 1400 degrees Celsius. But at lower temperatures – 600 to 700 degrees Celsius – we certainly didn’t expect graphene-like material growth.”



When the researchers pulled the porous silicon out of the furnace, they found that it had turned from orange to purple or black. When they inspected it under a powerful scanning electron microscope they found that it looked nearly identical to the original material but it was coated by a layer of graphene a few nanometers thick.



When the researchers tested the coated material they found that it had chemically stabilized the silicon surface. When they used it to make supercapacitors, they found that the graphene coating improved energy densities by over two orders of magnitude compared to those made from uncoated porous silicon and significantly better than commercial supercapacitors.


Via Dr. Stefan Gruenwald
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33rd Square: Inexpensive One-Atom-Thick Graphene Supercapcitors Created

33rd Square: Inexpensive One-Atom-Thick Graphene Supercapcitors Created | Science, Technology, and Current Futurism |
UCLA researchers have developed a groundbreaking technique that uses a DVD burner to fabricate micro-scale graphene-based supercapacitors — devices that can charge and discharge a hundred to a thousand times faster than standard batteries.
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