As advancements are made in wearable technology, including the development of portable devices that can function when stretched or bent, so too must the ways by which these devices generate and store power.1 For true portability of flexible smartphones, interactive bracelets and smart textiles for example, higher energy-density batteries need to be part of the ‘fabric’ of the device. Researchers from Fudan University in Shanghai demonstrated that a wire-shaped lithium-ion battery can be fabricated from a composite pairing of aligned yarns of active materials, sheathed in a heat-shrinkable tube.2
