A novel cord-shaped supercapacitor with high stretchability

Cord-shaped stretchable supercapacitors have received much attention due to their high stretchability and three-dimensional flexibility. For coaxial supercapacitors, lower capacitive performance and the inextensibility of the separation layer have been the important factors hindering further developments. In this work, we developed an integration technology to fabricate multiple yarn-electrodes by a layer-to-layer braiding. Between the inner and outer electrodes there is a braided elastic separator by braiding multiple spandex yarns. The braided separator features not only a reliable separation of the inner and outer electrodes, but also a high stretchability and high porosity. The cord-shaped supercapacitor shows an excellent capacitive performance of 60.1 mF/cm2 with energy density of 5.4 μWh/cm2, power density of 0.52 mW/cm2 and extremely high capacitance retention of 99.8% under the strain of 100%, demonstrating the application value of this stretchable energy storage device.