Stanford University researchers also are working with the common T-shirt, creating batteries and simple capacitors from ordinary textiles dipped in nanoparticle-infused ink. The conductive textiles, called “eTextiles,” represent a new class of integrated energy storage device, born from the synthesis of prehistoric technology with cutting-edge materials science.
While conventional batteries are made by coating metallic foil in a particle slurry and rolling it into compact form, the new eTextiles were manufactured using a simple dipping and drying procedure, in which a strip of fabric is coated with a special ink formula and dehydrated in the oven. The procedure works for manufacturing batteries or supercapacitors, depending on the contents of the ink: oxide particles such as LiCoO2 for batteries, and conductive carbon molecules (single-walled carbon nanotubes) for supercapacitors.
The lightweight, flexible, and porous character of natural and synthetic fibers has proven to be an ideal platform for absorbing conductive ink particles. That helps explain why treated textiles make such efficient energy storage devices. A piece of eTextile weighing about 10 ounces (the approximate weight of a T-shirt) could hold up to three times more energy than a cell phone battery.
The potential applications of wearable power range from health monitoring to moving-display apparel. Large companies have expressed an interest in developing reactive, high-performance sportswear using the new technology, and the U.S. military is looking at integrating energy textiles into its battle array, a move that may one day lighten a soldier’s carrying load.