Synthesis of layered birnessite-type manganese oxide thin films on plastic substrates by chemical bath deposition for flexible transparent supercapacitors

Layered birnessite-type manganese oxide thin films are successfully fabricated on indium tin oxide coated polyethylene terephthalate substrates for flexible transparent supercapacitors by a facile, effective and inexpensive chemical bath deposition technology from an alkaline KMnO(4) aqueous solution at room temperature. The effects of deposition conditions, including KMnO(4) concentration, initial molar ratio of NH(3)center dot H(2)O and KMnO(4), bath temperature, and reaction time, on the electrochemical properties of MnO(2) thin films are investigated. Layered birnessite-type MnO(2) thin films deposited under optimum conditions display three-dimensional porous morphology, high hydrophilicity, and a transmittance of 77.4% at 550 nm. A special capacitance of 229.2 F g(-1) and a capacitance retention ratio of 83% are obtained from the films after 1000 cycles at 10 mV s(-1) in 1 M Na(2)SO(4). Compressive and tensile bending tests show that as-prepared MnO(2) thin film electrodes possess excellent mechanical flexibility and electrochemical stability. (C) 2011 Elsevier B. V. All rights reserved.