Electrochemical supercapacitor performance of boron and nitrogen co-doped porous carbon nanowires

Abstract

Boron and nitrogen co-doped carbon (BNDC) nanowires supporting on carbon paper substrate are designed as binder-free electrode material for supercapacitor application. Boric acid-polyaniline is synthesized via electro-polymerization route using polyvinyl pyrrolidone as a structure-directing agent, showing the close-packing nanowire structure. BNDC is then formed by simultaneously doping boron and nitrogen during carbonization process of boric acid-polyaniline, showing nanowire-interconnected network structure. BNDC exhibits high specific capacitance of 504.0 F g-1 at 1.0 A g−1 in 1.0 M H2SO4 electrolyte. The superior capacity performance results from the porous structure with high surface area of 1022.4 m2 g−1 and the pseudocapacitance of boron, nitrogen and oxygen-containing functional groups. BNDC shows the cycling capacitance retention of 97.4% after 10000 cycles at 10.0 A g−1, presenting good cycling stability. A symmetrical solid-state BNDC supercapacitor is constructed using BNDC electrode and polyvinyl alcohol-H2SO4 gel electrolyte. This device reveals specific capacitance of 255.7 F g-1 at 1.0 A g−1, energy density of 22.7 W h kg−1 at power density of 0.2 kW kg−1, the capacity retention of 91.0% after 5000 cycles at 5.0 A g−1 and an output voltage of 1.6 V. BNDC supercapacitor with comparable capacitance performance presents the promising application in electrochemical energy storage devices.