Imagine a smartphone that looks like a piece of clear plastic, lighting up to display contacts, a game, the weather, or email from a friend. That future may be upon us thanks to a new, transparent and flexible lithium-ion battery.
Lithium-ion batteries are the type of energy storage devices that power consumer electronics such as smartphones.
Transparent components of gadgets such as touch screens, displays, and optical circuits have been fabricated, but until now, batteries have prevented fully see-through gadgets from entering the marketplace because the materials used to make batteries are not see-through.
"If you look at a battery electrode, it is black, it is not transparent," Yi Cui, a nanomaterials science and engineering researcher at Stanford University, told me today.
Cui, who has used nanoscale manufacturing techniques for other battery breakthroughs, and his colleagues overcame this hurdle by fabricating a battery with visible parts below the resolution of human eyes.
To do this, they spin-coated a silicon substrate with nanoscale-sized, grid-like trenches that were filled with an active electrode material via capillary forces.
"When the line widths of this grid is smaller than the size that your eye can resolve, they will look transparent," Cui said.
A paper describing the battery was published today in Proceedings of the National Academy of Sciences.
The authors add that by aligning multiple batteries together in a series, the overall energy stored can be increased without sacrificing transparency. The battery is also fully flexible, broadening its potential applications.
That futuristic smartphone, Cui said, is possible today. "There is no barrier going forward," he said. "You have a cell phone case that is transparent and then everything inside is transparent including the battery."
More on batteries and transparency:
A revolution in batteries