High performance fiber-shaped flexible asymmetric supercapacitor based on MnO2 nanostructure composited with CuO nanowires and carbon nanotubes

The demand for wearable electronics has greatly promoted the development of flexible supercapacitors. Herein, we develop a series of approaches to fabricate a fiber-shaped supercapacitor with flexibility. In the device, CuO@MnO2, carbon nanotube (CNT)@MnO2 and PVA-KOH are respectively used as inner electrode, outer electrode and gel electrolyte. The approaches including in-situ growth of CNTs, in-situ etching removal of SiO2 template and in-situ filling of gel electrolyte via hydrothermal process are explored to protect the device from structure damage caused by external forces and to maximize effective contact areas between active electrode materials and gel electrolyte. The optimized supercapacitor of copper wire@CuO@MnO2//PVA-KOH// CNT@MnO2 demonstrates a good capacitive performance (5.97 F cm(-3)) and exhibits a high energy density (0.38 mWh cm(-3)) at a power density of 25.5 mW cm(-3). In addition, it has perfect cycling stability (77% after 2000 cycles) with excellent flexibility. Therefore, this work will provide desirable processes to construct fiber-shaped supercapacitors as flexible and wearable energy storage devices.