Goodbye Batteries, Hello Graphene Supercapacitors

Just when you had resigned yourself to never having a land speeder like Luke Skywalker's, here come some guys using a DVD drive to make you an energy source. They were laser scribing graphene on a sheet of plastic painted with a graphite solution when one of them realized that he could make a low cost sheet of supercapacitors with the same equipment. The fact that lasers similar to theirs are already in most homes and offices suggests that at least some of the challenges to production have already been met. The new device was made by Bor Jang of US-based Nanotek Instruments and some of his colleagues.

"Our goal is to make a supercapacitor that stores as much energy as the best lithium-ion batteries (for the same weight) but which can still be recharged in less than two minutes," said Jang.

If this system is scalable, it could whip the charging time problem that is killing long range electric car sales. Today, if you want to pay for enough lithium ion batteries, you can have a long-range electric vehicle. Charging it would take hours, though. Battery swaps have been discussed, but enough batteries to support a population of cars would probably be a prohibitive investment. On the other hand, supercapacitors with similar capacity could charge in a couple of minutes, so the power supply in your car wouldn't need to be changed.

So along come Jang and his friends making supercapacitors out of graphite, a sheet of plastic, and some acetylene black electrical flow enhancer. The capacitors will be cheap and biodegradable.  They'll also have comparable energy density to lithium-ion cells. Being capacitors, they will recharge in a few minutes. Is the battle for cheap, long range electrical transportation won?

Well, let's say we want to store 10,000 kilowatt hours of power in a supercapacitor. That's about 13 horsepower for an hour, enough energy to move a small car about 60 miles. If we cram that much energy into a small device during a two minute charge cycle, a lot of heat will have to go somewhere. Of course these biodegradable components are also flammable. In fact, carbon, thin plastic sheets, and the acetylene black additive are all pretty good kindling. When we expose this mix of heat and fuel to air, you might not want to be sitting in the driver's seat.

Before we give up, though, let's review a few details about early cars. The guys building and selling autos in 1910 didn’t have fuel pumps. They put gallons of fiercely flammable and volatile gasoline into a can and suspended it directly above a hot, spark ignition engine. Just to make sure the adventure could continue into the night, they mounted acetylene-powered headlights with flint strikers to the same frame that held the gas tank. Don't try this at home, kids.

There must have been accidents, but there were enough survivors to continue building and driving autos. In fact, today's fuel system isn't conceptually much different from the 1910 model. In fact, most of today's cars have electric fuel pumps submerged in the gas-filled fuel tank. How's that for a century of engineering applied to a fundamentally dangerous idea? By comparison the supercapacitors look like a walk in the park.

We'll probably still have to postpone the land speeder, but it looks to me as if we may have the power storage approach we need for practical, affordable electric cars. That's an exciting step in the right direction.


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