A High Performance Stretchable Asymmetric Fiber-Shaped Supercapacitor with a Core-Sheath Helical Structure

The emerging fiber-shaped supercapacitors (FSSs) have motivated tremendous research interest in energy storage devices. However, challenges still exist in the pursuit of combination of excellent electrochemical performance and mechanical stretchability. Here, a core-sheath asymmetric FSS is first made by wrapping gel electrolyte coated carbon nanotube (CNT)@MnO2 core fiber with CNT@PPy composite film. Then a stretchable helical structure is formed by over-twisting the FSS. The resulted stretchable asymmetric FSS exhibits a specific capacitance of 60.435 mF cm(-2) at the scan rate of 10 mV s(-1) and the capacitance performance is well maintained during repeated stretching to 20% strain. Furthermore, a high energy density of 18.88Wh cm(-2) is achieved for the stretchable FSS due to its high specific capacitance and extended potential window of 1.5 V.