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 18.88 μW h cm−2 is achieved for the stretchable FSS due to its high specific capacitance and extended potential window of 1.5 V. A stretchable asymmetric fiber‐shaped supercapacitor with a core‐sheath helical structure is fabricated. The supercapacitor exhibits a high areal specific capacitance of 60.435 mF cm−2, stable operating potential window of 1.5 V, and high energy density of 18.88 μW h cm−2. Furthermore, it demonstrates stable capacitive performance during repeated stretching to 20% strain.