As manufacturers of smartphones and mobile devices strive to make their products increasingly portable, they repeatedly come up against the constraints of existing battery technology. However, Xiaodong Li, a professor at the University of South Carolina (USC) believes that we will soon be able to employ the clothes we wear to help overcome such challenges and to this end, Li has transformed T-shirt material into an energy storage medium which could one day be used to power portable devices.

Beginning with a standard T-shirt purchased from a local discount store, Li’s team soaked the garment in a solution of fluoride, then dried and baked the fabric at high temperature in an oven, which is designed to exclude oxygen in order to prevent the fabric from igniting. Following this process, the surfaces of the fibers of the T-shirt material were shown by infrared spectroscopy to have been converted from cellulose to activated carbon, while still retaining all their previous flexibility.

By making use of small swatches of the treated T-shirt fabric as electrodes, Li and his fellow researchers were able to prove that the flexible material, dubbed “activated carbon textile,” acts as a capacitor, a critical component of virtually every electronic device in use today. Further to this, Li reports that the new activated carbon textile material is actually capable of acting as a double-layer capacitor, (commonly called a supercapacitor) due to its high energy density. Supercapacitors have previously been utilized in the areas of aerospace and motorsport - for example, in Toyota's hybrid Le Mans challenger.

Finally, the team coated the individual fibers of the activated carbon textile with a layer of manganese oxide just a nanometer thick, increasing the electrode performance of the fabric yet further still. The newly manganese oxide-treated activated carbon textile fabric was able to maintain up to 95 percent of its energy storage performance even after thousands of charge-discharge cycles, convincing the USC researchers that the material could one day be implemented to charge low-power portable devices such as cell phones.

It's important to note that material which can store energy is by no means new but Li was keen to point out that the process pioneered at USC is both cost-effective and environmentally-friendly. "Previous methods used oil or environmentally unfriendly chemicals as starting materials," said Li. "Those processes are complicated and produce harmful side products. Our method is a very inexpensive, green process."

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