Roughly one 1 mm in diameter, the fiber shaped lithium-ion batteries are reported lightweight enough to create weavable and wearable textile batteries that could power various devices. The researchers say that the yarn is capable of delivering nearly 71 mAh/g of power, and can also be woven into existing textiles to create novel electronic fabrics.

To make the fiber batteries, the team had to develop functional cathode and anode composite yarns. Lithium manganate (LMO) particles were deposited on a carbon nanotube (CNT) sheet and scrolled up to create a CNT-LMO composite yarn which functions as the cathode. The anode composite yarns were made by sandwiching a CNT sheet between two silicon-coated CNT sheets and scrolling them up. When the two yarns, which are separated by a gel electrolyte for safety, are wound, it results in a CNT-based fiber shaped Li-ion battery (LIB).

"The two yarns can be twisted directly to form a battery, or can also be wound onto any commercial polymer fiber as they both have small diameters and good flexibility," Dr Wei Wang, the lead researcher, tells Gizmag. "The fiber battery can then be added into an existing textile or just woven into a textile directly."