Supercapacitor: Today's energy revolution

Supercapacitors are used on wind farms, like the one above.

Materials scientist Dr. Richard Kaner in his lab at UCLA. Just a $25 CD printer was enough to produce graphene-based supercapacitors this year; he didn’t need any of this stuff.

President Obama made it a priority to invest in advanced battery technology as an investment in the future. But another technology is revolutionizing energy storage today: the supercapacitor.

Your smartphone camera flash probably uses one, hybrid cars are using them to capture the energy when they brake, and in China they power some electric buses for short distances.

Supercapacitors are a new kind of energy storage with some big advantages. They charge up hundreds of times faster than a battery, never wear out and need replacing, and they don’t care about temperature extremes.

Inside a supercapacitor you’ll find what looks like a stack of black and white sheets of paper -- none of the chemicals inside a battery. That’s because it stores a static electricity charge and doesn’t rely on chemical reactions.

“It’s good for rapid, high-current events, both charging and discharging,” says Mike Sund, avice president at San Diego-based Maxwell Technologies, which sells over $100 million of them every year. While they make some smaller products, “The great bulk of our business is with the large-format styles that are used in windmills, transit buses, and automobiles.”

In the few years they’ve been on the market, supercapacitors have been getting better and smaller. Shrinking them down, or increasing their energy density to something approaching a battery’s, is the goal.

And there have been a couple of big breakthroughs this year. In Australia, Monash University materials scientist Dan Lee led a team that built one with the same energy density as a regular lead acid car battery.

What makes this possible is a new form of carbon called graphene. It’s only one atom thick -- practically 2-dimensional -- and they layered sheets of it very closely.

Over at UCLA, Dr. Richard Kaner and his grad student Maher El-Kady came up with a unique manufacturing process. “The method we used to produce graphene supercapacitors is as simple as we take a $25 device used for labeling CD discs.” They coat the disc; and then when it comes out they peel off a sheet of flexible supercapacitors!

“So you can literally print large supercapacitors, or we’ve printed on a single CD disc over a hundred micro-supercapacitors,” Kaner says. This could have almost immediate applications, like roll-up video displays, wearable electronics, or even pacemakers.

Kaner continues: “There are a lot of things that supercapacitors are being used for. My favorite is there’s a train station in Europe that has a revolving door connected to a supercapacitor that operates the restaurant next door.”

And this kind of creative use is only going to increase in the coming years. 

Materials scientist Dr. Richard Kaner in his lab at UCLA. Just a $25 CD printer was enough to produce graphene-based supercapacitors this year; he didn’t need any of this stuff.

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