We’re thinking steampunk for this new energy storage concept because it takes soft cotton fiber and hard wire, and welds them together into something startling and bizarre. That would be a new “capacitive yarn” under development at Drexel University in collaboration with the US Naval Academy. The new yarn can be used to make a variety of purpose-built fabrics, and so far the researchers see the most promise in energy storage.
If Drexel rings a bell, that’s because we are on a two-day Drexel binge. We were just talking about an EV battery under development at the university, so if everything pans out some day, you could be driving down the road in your EV without a care in the world because your whole outfit is a range extender. Just thinking ahead…
How To Make An Energy Storage Textile
Speaking of steampunk, Drexel’s new “energy textile” does have a DIY feel to it. Aside from cotton yarn (or other cellulose fiber) and stainless steel wire, all you need is molten salt and the secret ingredient — activated carbon.
Drexel describes the process as “Natural Fiber Welding.” It starts with bathing the yarn in molten salt, causing it to swell.
Once opened up, the yarn can receive activated carbon particles (you’ll need a syringe for this step). Wash away the molten salt with plain water to make the cotton shrink back down, and the carbon particles will cling to the surface. Twist it up with stainless steel “yarn” for conductivity, weld them together, and what you end up with is a flexible fiber that can store energy.
Figuring out the order of twisting the cotton with steel first and then welding them was one of the key challenges in developing the yarn.
The researchers are quite definite about the fashion angle (there’s that steampunk thing again). They chose carbon because it is less likely to be a skin irritant, and the process can be applied to practically any cellulose-based fiber. That includes rayon and viscose as well as naturey stuff like cotton, linen, and bamboo.
What Good Is Wearable Energy Storage?
We were just kidding about that EV thing, but if you’re wondering why the US Navy has a dog in this race, think about the weight you’d save if you could just weave your battery packs into whatever you’re wearing instead of carrying them around.
If your money is on divers, you’re partly on the right track, but we’re betting that the US Marine Corps — which is all about energy mobility — will get dibs on this.
Now combine your energy storage textile with wearable solar cells, and you’ve got a complete energy on-the-go system.
The Big Energy Storage Textile Question: Knitting Or Weaving?
By the way, all you knitters out there, the researchers are focusing on energy storage textiles that are knitted, not woven. So far they have found that cotton-based yarn has the best electro-chemical performance but it proved to be a bust for knitting because it broke too easily.
The team is having better luck with blends of bamboo, linen, and a viscose/nylon combo, possibly because these materials have longer fibers than cotton.
So, add knitwear to the growing field of wearable energy storage. We’re thinking that crochet can’t be far behind.
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Image Credits: Drexel University
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