Dark arts

SINCE their invention two centuries ago, batteries have been made from many things. The first were of copper and zinc. Today, lithium is preferred for a lot of applications. Lead, nickel, silver and a host of other materials have also been used. Until recently though, no one had tried melanin, the pigment that darkens skin and protects it against ultraviolet light. But, as he reported this week at a meeting of the American Chemical Society in Philadelphia, Christopher Bettinger of Carnegie Mellon University, in Pittsburgh, has now done just that. His purpose is to create a battery safe for use in the human body.

Melanin is not, at first sight, an obvious battery ingredient. It is a complicated molecule composed of carbon, oxygen, nitrogen and hydrogen. To synthesise it on an industrial scale would surely require biotechnology rather than conventional chemistry. But it does have the ability to capture and release positively charged ions, known as cations. Batteries depend on the movement of ions, so this property is a good start. On top of that, being a normal ingredient of bodies, melanin is not toxic. This is in contrast to many conventional battery…Continue reading
Source: Economist