Application of binder-free TiOxN1-x nanogrid film as a high-power supercapacitor electrode

Binder-free TiOxN1-x nanogrid films with high conductance, high specific surface area, and high electrochemical stability can meet the demand for high-performance supercapacitor materials. A metalphase TiOxN1-x nanogrid film was prepared by a simple hydrothermal-nitrification method. The TiOxN1-x nanogrid film showed higher specific surface area (75.9 m(2) g(-1)) and lower impedance than nanosheet, nanowire, and nanoribbon films. As a result, the TiOxN1-x, nanogrid electrode showed the highest specific capacitance (8.28 mF cm(-2)), the highest capacitance retention (95.8%) after 10,000 galvanostatic charge/discharge cycles, and the highest operating frequency (398 Hz). To improve the power density and energy density of the supercapacitor, an organic electrolyte (1 mol L-1 tetraethylammonium tetrafluoroborate in acetonitrile, TEA-BNAN) and a room temperature ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, EMIM-TFSI) were applied to enlarge the voltage range to 0-2.5 V and 0-3.5 V, respectively, compared with the 0-0.8 V of a KCl aqueous electrolyte. The EMIM-TESI supercapacitor reached the highest energy density, 15.0 Wh kg(-1), while the highest power density with the TiOxN1-x nanogrid electrode, 166.1 kW kg(-1), was achieved by the TEA-BNAN supercapacitor, which is much larger than not only the 45.1 kW kg(-1) determined in 1 mol L-1 KCl aqueous electrolyte but also the 144.1 kW kg(-1) measured in EMIM-TESI. (C) 2015 Elsevier B.V. All rights reserved.