Research project develops novel supercapacitor fabricated in silicon

October 24, 2013 // By Paul Buckley
A novel supercapacitor design invented by material scientists at Vanderbilt University has raised the possibility of creating solar cells that produce electricity around the clock and not just when the sun is shining.

The supercapacitor claims to be the first that can be made in silicon alongside with the microelectronic circuitry that it powers; it could also equip mobile phones with built-in power cells that recharge in seconds and work for weeks between charges.

The research breakthrough achieved by researchers at Vanderbilt University led by Assistant Professor Cary Pint is described in a paper published in the October 22 issue of the journal Scientific.

The scientists suggest that it should be possible to construct the 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 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.

These properties have allowed commercial supercapacitors, which are made out of activated carbon, to capture niche markets, such as storing energy captured by regenerative braking systems on buses and electric vehicles and to provide the bursts of power required to adjust of the blades of giant wind turbines to changing wind conditions. Supercapacitors still lag behind the electrical energy storage capability of lithium-ion batteries, so they are too bulky to power most consumer devices. However, they have been catching up rapidly.

“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,” explained Assistant Professor