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Powering The Future

Turning A Plain White T-Shirt Into A Not-So-Plain Battery

A new process that lets cotton hold a charge could be the beginning of a world of flexible batteries.

Flexible electronics—from rollup cell phones to bendable laptops—lie just around the corner. But there is one major obstacle in the way of fully bendy gadgets: While we can build screens that bend without breaking, our batteries remain fairly rigid.

That could soon change. The journal Advanced Materials has reported a new way to create cheap, flexible fabrics that store significant amounts of energy. The experiment, led by the University of South Carolina’s Xiaodong Li, showed how a plain cotton T-shirt may also transmit and store energy.

"We wear fabric every day," says Li, a professor of mechanical engineering at USC, in a university release. "One day our cotton T-shirts could have more functions; for example, a flexible energy storage device that could charge your cell phone or your iPad."

Li devised a process that "converts insulating cotton T-shirt textiles into highly conductive and flexible activated carbon textiles." In other words, it changes the fibers that make up the fabric into wires and (energy-storing) capacitors. Li bought a T-shirt at a local discount store, soaked it in a fluoride solution, and heated it in an oxygen-free environment to change the cotton fibers’ cellulose into activated carbon. While this alone was enough to create a conductive material, Li’s team coated the activated carbon fibers with nano-layers of manganese oxide, which boosted the T-shirts performance.

While these new "hybrid fabrics" may not resemble anyone’s former white T-shirts (the process turns it black, for one), the material retains enough flexibility and charge to prove useful as a pliable battery. "By stacking these supercapacitors up, we should be able to charge portable electronic devices such as cell phones," Li says.