A team of Stanford researchers is producing batteries and simple capacitors from ordinary textiles dipped in nanoparticle-infused ink. The conductive textiles – dubbed ‘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 – a capital-intensive process – the new energy textiles were manufactured using a simple ‘dipping and drying’ procedure, whereby a strip of fabric is coated with a special ink formula and dehydrated in an oven.
The procedure works for manufacturing batteries or supercapacitors, depending on the contents of the ink – oxide particles such as LiCoO2 for batteries; conductive carbon molecules (single-walled carbon nanotubes, or SWNTs) for supercapacitors. Up to now, the team has only used black ink, but Cui said it is possible to produce a range of colors by adding different dyes to the carbon nanotubes.
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.
The team had previously developed paper batteries and supercapacitors using a similar process, but the new energy textiles exhibited some clear advantages over their paper predecessors. With a reported energy density of 20 Watt-hours per kilogram, a piece of eTextile weighing 0.3 kilograms (about an ounce, the approximate weight of a T-shirt) could hold up to three times more energy than a cell phone battery.
Aside from enhanced energy storage capacity, eTextiles are remarkably durable and can withstand greater mechanical stress.
The potential applications of wearable power are manifold, ranging from health monitoring to moving-display apparel.
The team will continue its current research trajectory with two themes in mind: how best to introduce eTextiles into real markets, and the fundamental science behind what makes their product work so effectively.
The team's findings appear in the January online edition of Nano Letters, a publication of the American Chemical Society, under the title "Stretchable, Porous, and Conductive Energy Textiles."
Source: Aimee Miles for Stanford News Service
Photo: Stanford.edu
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