Batteries based on lithium ion technology can be made into threads that stretches to almost 600 percent, a property that will be useful in the manufacture of flexible and elastic fabrics. Wearable technology, and by extension the smart clothes, stand to gain from this discovery. Scientist, Huishen Pengat, and colleagues at the Fudan University have been working on this technology, that, will enable manufacturers to make textiles woven from fiber shaped batteries.
The super elastic fiber shaped battery, developed at Fudan University, consists of an elastomeric substrate wound by two yarns of carbon nanotubes-lithium oxide composites. The arrangement is then covered with a gel electrolyte layer; the two yarns act as the positive and negative electrodes and provide the connections to the battery. The battery stability under the stretched conditions is due to the fiber electrodes’ twisted structure, together with the ability of the gel electrolyte and elastic substrate to stretch without affecting their electrochemical properties. The spring like structure of the yarn electrodes is maintained, as long as the battery is stretched to its safe limits.
However, there is a slight drop in its 91.3mAH/g specific capacity, which drops to about 90 percent when the battery is stretched to about 600 percent. The light battery weighing 0.08 grams fits on a 10 centimeter-long piece and produces enough power to light a number of LEDs for up to a minute.
Other stretchable batteries are already in the market, only that these are in planar format and it has been a challenge in developing suitable ones for the lightweight, small and wearable electronics. This elastic battery technology will now make it possible to make the ‘storage’ threads that can be woven into the smart clothes, and which will adapt to body movements while still powering the wearable electronics.