Now, researchers develop a transparent battery

Several companies have successfully created partially transparent gadgets such as digital photo frames and cellphones with see-through keyboards. However, fully transparent e-book readers or cell phones have remained largely in the realm of conceptual art due to a missing puzzle piece.

According to a press release, Stanford researchers have invented a transparent lithium-ion battery that is highly flexible and comparable in cost to regular batteries, with great potential for application in consumer electronics.

Since key active materials in batteries cannot be made transparent or replaced with transparent alternatives yet, researchers realised they had to find a way to design a battery with non-transparent components too small to be seen by the naked eye. They devised a mesh-like framework for the battery electrodes, with each 'line' in the grid approximately 35 microns wide. Light passes through the transparent gaps between the gridlines. Since the individual lines are so thin, the entire meshwork appears transparent.

The researchers came up with an ingenious three-step process that utilised low-cost, commonly available substances. First, since regular materials such as copper or aluminum were ruled out, a transparent alternative had to be found. The researchers settled on a transparent, slightly rubbery compound known as polydimethylsiloxane. It was poured into silicon molds to create grid-patterned trenches.