title: A nanostructured electrochromic supercapacitor.
abstract: We report the first successful application of an ordered bicontinuous double-gyroid vanadium pentoxide network in an electrochromic supercapacitor. The freestanding vanadia network was fabricated by electrodeposition into a voided block copolymer template that had self-assembled into the double-gyroid morphology. The highly ordered structure with 11.0 nm wide struts and a high specific surface to bulk volume ratio of 161.4 μm(-1) is ideal for fast and efficient lithium ion intercalation/extraction and faradaic surface reactions, which are essential for high energy and high power density electrochemical energy storage devices. Supercapacitors made from such gyroid-structured vanadia electrodes exhibit a high specific capacitance of 155 F g(-1) and show a strong electrochromic color change from green/gray to yellow, indicating the capacitor's charge condition. The nanostructuring approach and utilizing an electrode material that has intrinsic electrochemical color-change properties are concepts that can be readily extended to other electrochromic intercalation compounds.
authors.affiliation: Nokia Research Center, Broers Building, J. J. Thomson Avenue, CB3 0FA, Cambridge, United Kingdom. di.wei@nokia.com
authors.forename: Di
authors.initials: D
authors.lastname: Wei
authors.forename: Maik R J
authors.initials: MR
authors.lastname: Scherer
authors.forename: Chris
authors.initials: C
authors.lastname: Bower
authors.forename: Piers
authors.initials: P
authors.lastname: Andrew
authors.forename: Tapani
authors.initials: T
authors.lastname: Ryhänen
authors.forename: Ullrich
authors.initials: U
authors.lastname: Steiner