Xiaodong Li and Lihong Bao from the University of South Carolina have published a paper in Advanced Materials on how to turn a cotton T-shirt into a source of electrical power, which could provide a way to charge mobile devices on the go.
Their flexible energy storage device was created by soaking a T-shirt in a solution of fluoride, then drying and baking it at a high temperature. The surfaces of the fibers were converted from cellulose to activated carbon, while retaining flexibility. The T-shirt could then act as a supercapacitor and was able to store an electrical charge.
But Li and Bao took the material even further than that. They then
coated the individual fibers in the activated carbon textile with
“nanoflowers” of manganese oxide. Just a nanometer thick, this layer of
manganese oxide greatly enhanced the electrode performance of the
fabric. "This created a stable, high-performing supercapacitor," said
This hybrid fabric, in which the activated carbon textile fibers are
coated with nanostructured manganese oxide, improved the energy storage
capability beyond the activated carbon textile alone. The hybrid
supercapacitors were resilient: even after thousands of charge-discharge
cycles, performance didn't diminish more than 5 percent.
"By stacking these supercapacitors up, we should be able to charge portable electronic devices such as cell phones," Li said.
Li is particularly pleased to have improved on the means by which
activated carbon fibers are usually obtained. "Previous methods used oil
or environmentally unfriendly chemicals as starting materials," he
said. "Those processes are complicated and produce harmful side
products. Our method is a very inexpensive, green process."