title: Suppressing the Coffee-Ring Effect in Semitransparent MnO2 Film for a High-Performance Solar-Powered Energy Storage Window.
abstract: We introduce a simple and effective method to deposit a highly uniform and semitransparent MnO2 film without coffee-ring effect (CRE) by adding ethanol into MnO2 ink for transparent capacitive energy storage devices. By carefully controlling the amount of ethanol added in the MnO2 droplet, we could significantly reduce the CRE and thus improve the film uniformity. The electrochemical properties of supercapacitor (SC) devices using semitransparent MnO2 film electrodes with or without CRE were measured and compared. The SC device without CRE shows a superior capacitance, high rate capability, and lower contact resistance. The CRE-free device could achieve a considerable volumetric capacitance of 112.2 F cm(-3), resulting in a high volumetric energy density and power density of 10 mWh cm(-3) and 8.6 W cm(-3), respectively. For practical consideration, both flexible SC and large-area rigid SC devices were fabricated to demonstrate their potential for flexible transparent electronic application and capacitive energy-storage window application. Moreover, a solar-powered energy storage window which consists of a commercial solar cell and our studied semitransparent MnO2-film-based SCs was assembled. These SCs could be charged by the solar cell and light up a light emitting diode (LED), demonstrating their potential for self-powered systems and energy-efficient buildings.
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hung Hom, Hong Kong, China.
authors.forename: Huanyu
authors.initials: H
authors.lastname: Jin
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hung Hom, Hong Kong, China.
authors.forename: Jiasheng
authors.initials: J
authors.lastname: Qian
authors.affiliation: Department of Mechanical Engineering, The Hong Kong Polytechnic University , Hung Hom, Hong Kong, China.
authors.forename: Limin
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hung Hom, Hong Kong, China.
authors.forename: Jikang
authors.initials: J
authors.lastname: Yuan
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hung Hom, Hong Kong, China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Huang
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hung Hom, Hong Kong, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hung Hom, Hong Kong, China.
authors.forename: Wing Man
authors.initials: WM
authors.lastname: Tang
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hung Hom, Hong Kong, China.
authors.forename: Helen Lai Wa
authors.initials: HL
authors.lastname: Chan
keywords: MnO2 film; coffee-ring effect; energy storage; flexible; semitransparent