University of Texas Develops Wearable Fabric With Battery Power To Charge Your Gadgets
"Wall warts," more commonly known as outlets, are quickly becoming a thing of the past. The latest alternative: wearable energy. To create textiles that can generate energy that can be used to power your gadgets, scientists from the University of Texas at Dallas are developing a method of spinning yarn from powder-infused carbon nanotubes.
In case you're like me and don't know what a "nanotube" is, Wikipedia says it's a nanometer-scale, tube-like structure. In particular, a carbon nanotube (CNT), like the ones used by this group of scientists, is an allotrope of carbon with a cylindrical nano-structure. The novel properties of CNTs make them useful in many applications such as nanotechnology, electronics, and optics, as well as body armor. They have extraordinary strength, unique electrical properties, and efficient thermal conducting abilities.
The nanotubes that would potentially be used in the energy-generating clothing give superconducting particles, such as boron and magnesium powder, a more manageable form but sans the binders or lasers that are normally necessary. The scientists' goal is to weave energy-transmitting yarn into wearable, light-weight fabric that acts as a battery.
"Powders are very important functional materials because they have high surface area," says Ray Baughman, Director of the Nanotech Institute at University of Texas. "The problem is that powders without form are difficult to use." Battery electrodes and superconducting wires, as well as the catalysts in fuel cells, are dependent upon powdered particles such as boron and magnesium. Take for example, lithium-ion battery electrodes. Taking advantage of the high surface area of powders, this type of battery achieves greater storage density. Traditionally, they hold together the powders with binders, which add weight and solidity. However, according to Baughman, the technology this group of scientists is developing intends to make it easier to work with a wide range of powdered substances. He claims that almost any powder can be made into a "sewable, knittable, knotable, braidable yarn."
The process involves dragging a roller over an array of vertically aligned CNTs to create a "nano-web," a tangled up, stretchy ribbon of nanotubes. The webs act as a host for the powders and other nanoparticles. The surface of the web is then sprayed with the powder and finally twisted into an actual strand of yarn. According to Baughman, almost all the powder is retained even after washing the yarn.
This method is essentially "turning particles into fibers," according to Matteo Pasquali, professor of chemical and biomolecular engineering at Rice University. Although not involved in the work Baughman is developing, Pasquali says that the powders he's using retain the properties of the boron and magnesium that make them so useful.
Using lithium-iron-phosphate powders, Baughman's team made a battery electrode fabric that is almost 99 percent active material, which allows it to be used in creating lightweight batteries. The group intends to take their advancements in several directions. They're starting with lightweight uses such as clothing, but they've also made mention that someday we could be talking about use in airplanes.