Novel Iron Oxyhydroxide Lepidocrocite Nanosheet as Ultrahigh Power Density Anode Material for Asymmetric Supercapacitors. Issue 18 (22nd May 2014)

• Record Type: Journal Article
• Authors: Chen, Ying‐Chu; Lin, Yan‐Gu; Hsu, Yu‐Kuei; Yen, Shi‐Chern; Chen, Kuei‐Hsien; Chen, Li‐Chyong
• Is Part Of: Small. Volume 10:Issue 18(2014:Sep.)
• Page Start: 3803
• Page End: 3810
• Publication Date: 2014-05-22
• Subjects: Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201400597
• Languages: English
• ISSNs: 1613-6810

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>A simple one‐step electroplating route is proposed for the synthesis of novel iron oxyhydroxide lepidocrocite (γ‐FeOOH) nanosheet anodes with distinct layered channels, and the microstructural influence on the pseudocapacitive performance of the obtained γ‐FeOOH nanosheets is investigated via in situ X‐ray absorption spectroscopy (XAS) and electrochemical measurement. The in situ XAS results regarding charge storage mechanisms of electrodeposited γ‐FeOOH nanosheets show that a Li<sup>+</sup> can reversibly insert/desert into/from the 2D channels between the [FeO<sub>6</sub>] octahedral subunits depending on the applied potential. This process charge compensates the Fe<sup>2+</sup>/Fe<sup>3+</sup> redox transition upon charging–discharging and thus contributes to an ideal pseudocapacitive behavior of the γ‐FeOOH electrode. Electrochemical results indicate that the γ‐FeOOH nanosheet shows the outstanding pseudocapacitive performance, which achieves the extraordinary power density of 9000 W kg<sup>−1</sup> with good rate performance. Most importantly, the asymmetric supercapacitors with excellent electrochemical performance are further realized by using 2D MnO<sub>2</sub> and γ‐FeOOH nanosheets as cathode and anode materials, respectively. The obtained device can be cycled reversibly at a maximum cell voltage of 1.85 V in a mild aqueous electrolyte, further delivering a maximum power density of 16 000 W kg<sup>−1</sup> at an energy density of 37.4 Wh kg<sup>−1</sup>.</p> </abstract>