DNA-inspired, highly packed supercoil battery for ultra-high stretchability and capacity

Stretchable yarn/fiber energy storage devices with a high energy density are highly beneficial for use in wearable applications. Although some studies on stretchable fiber batteries have been conducted, the development of fiber batteries that combine outstanding stretchability with a high energy storage capacity has been restricted by the tradeoff between stretchability and the active material content. In the present study, a DNA-inspired supercoil battery is proposed and fabricated via the secondary twisting (i.e. supercoiling) of a fiber electrode consisting of an elastomeric core fiber and a conductive sheath containing nano-sized active materials. The structural changes induced by supercoiling facilitate the effective packing of the electrode into coil and supercoil loops that represent only 29% of the initial length. The resulting highly packed supercoil battery exhibits an outstanding stretchability (800%) and linear capacity (0.029 mAh/cm) compared to non-coil, coil, and previously reported stretchable yarn/fiber-based batteries.