Fiber-based MnO 2 /Carbon nanotube/polyimide asymmetric supercapacitor

Abstract With the development of wearable electronics, fiber-based supercapacitors with both high energy and power densities are under growing demand. Herein we discovered a high performance fiber-based asymmetric supercapacitor (FAS) based on two carbon nanotube (CNT) composite fibers. MnO 2 nanosheets were in situ grown on a CNT fiber to serve as the positive electrode, while polyimide was deposited onto another CNT fiber to form the negative electrode. The resulting aqueous FAS demonstrated broad operating voltage window (0–2.1 V), high areal energy density (36.4 μWh cm −2 at power density of 0.78 mW cm −2 ) and high power density (15.6 mW cm −2 at energy density of 30.2 μWh cm −2 ) with good rate performance, long cycling life and high flexibility.