Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5363107 | Applied Surface Science | 2013 | 9 Pages |
Layered δ-MnO2 thin films with a three-dimensional nanostructure are successfully fabricated on stainless steel foil substrates for flexible electrochemical capacitors by a facile and effective chemical bath deposition technology from ethanol and potassium permanganate solution at 15 °C. The as-prepared thin films display nanoporous morphology and a water contact angle of 20°. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analyses reveal that the thin films are composed of δ-MnO2. Electrochemical data demonstrate that the δ-MnO2 thin film electrodes can deliver a high special capacitance of 447 F/g at 2 mV/s, and provide a good capacitance retention ratio of 87% after 1000 continuous cycles at 10 mV/s in 0.5 M Na2SO4. Compressive and tensile bending tests show that the as-prepared electrodes can steadily work over a wide range of applied curvatures between â2.5 cmâ1 (tension) and 2.5 cmâ1 (compression). Only a small decrease in special capacitance (0.9% at a curvature of 2.5 cmâ1 under compressive strain, or 1.2% at a curvature of â2.5 cmâ1 under tensile strain) is observed even after bending for 200 cycles, indicating the excellent mechanical flexibility and electrochemical stability of the δ-MnO2 thin film electrodes.
Graphical abstractDownload full-size imageHighlights⺠The δ-MnO2 thin films are obtained by a facile chemical bath deposition at 15 °C. ⺠The thin films exhibit 3D porous morphology and high hydrophilicity. ⺠The thin films display high capacitances of 447 F/g and 22.4 mF/cm2. ⺠The thin films show a good capacitance retention ratio of 83% after 1000 CV cycles. ⺠The thin films show excellent mechanical flexibility and electrochemical stability.