Farhad Manjoo in Slate:
One approach for improving the battery is to forget about the battery and instead improve capacitors. A capacitor, like a battery, is a device that stores electrical energy. But capacitors charge and discharge their energy an order of magnitude faster than batteries. So if your phone contained a capacitor rather than a battery, you’d charge it up in a few seconds rather than an hour. But capacitors have a big downside—they’re even less energy dense than batteries. You can’t run a phone off a capacitor unless you wanted a phone bigger than a breadbox.
But what if you could make a dense capacitor, one that stored a lot of energy but also charged and discharged very quickly? Over the past few years, researchers at several companies and institutions around the world have been racing to do just that. They’re in hot pursuit of the perfect “supercapacitor,” a kind of capacitor that stores energy usingcarbon electrodes that are immersed in an electrolyte solution. Until recently, though, supercapacitors have been expensive to produce, and their energy densities have fallen far short of what’s theoretically possible. One of the most promising ways of creating supercaps uses graphene—a much-celebrated substance composed of a one-atom layer of carbon—but producing graphene cheaply at scale has proved elusive.
Then something unexpectedly amazing happened. Maher El-Kady, a graduate student in chemist Richard Kaner’s lab at UCLA, wondered what would happen if he placed a sheet of graphite oxide—an abundant carbon compound—under a laser. And not just any laser, but a really inexpensive one, something that millions of people around the world already have—a DVD burner containing a technology called LightScribe, which is used for etching labels and designs on your mixtapes. As El-Kady, Kaner, and their colleagues described in a paper published last year in Science, the simple trick produced very high-quality sheets of graphene, very quickly, and at low cost.