Researchers at Stanford University have made fully transparent batteries, the last missing component needed to make transparent displays and other electronic devices.

Stanford materials science professor Yi Cui, who led the work, says a tremendous amount of research goes into making batteries store more energy for longer, but little attention has been paid to making them "more beautiful, and fancier."

Researchers have previously made transparent variations on other major classes of electronics, including transistors and the components used to control displays, but not yet batteries. "And if you can't make the battery transparent, you can't make the gadget transparent," says Cui.