title: Effects of Microstructure on Electrode Properties of Nanosheet-Derived Hx(Ni1/3Co1/3Mn1/3)O₂ for Electrochemical Capacitors.
abstract: Nanosheet-derived Hx(Ni1/3Co1/3Mn1/3)O₂ was prepared by restacking (Ni1/3Co1/3Mn1/3)O₂ nanosheets with large or small lateral sizes and their electrochemical properties in a 1 M KOH aqueous solution; microstructural factors were compared with those of bulk Hx(Ni1/3Co1/3Mn1/3)O₂ (HNCM). The electrodes composed of small nanosheets exhibited very large capacitances of 1241 F·g-1(395 mAh·g-1) at a current density of 50 mA·g-1, and 430 F·g-1(100 mAh·g-1) at a large current density of 1000 mA·g-1. These large capacitances resulted from a heterogeneous layer structure with a large surface area and pore volume. The electrodes of large nanosheets, with a strongly interconnected microstructure and a surface area slightly larger than that of HNCM, exhibited good cycle stability and capacitances larger than that of HNCM. Microstructural control through the restacking of (Ni1/3Co1/3Mn1/3)O₂ nanosheets improved the electrochemical properties of Hx(Ni, Co, Mn)O₂.
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan. masatoyano@crm.rcast.u-tokyo.ac.jp.
authors.forename: Masato
authors.initials: M
authors.lastname: Yano
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan. sin@crm.rcast.u-tokyo.ac.jp.
authors.forename: Shinya
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan. miyayama@rcast.u-tokyo.ac.jp.|Japan Science and Technology Agency, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan. miyayama@rcast.u-tokyo.ac.jp.
authors.forename: Masaru
authors.initials: M
authors.lastname: Miyayama
authors.affiliation: Yokohama Laboratory, Hitachi High-Tech Science Corporation, 1-18-2 Hakusan, Midori-ku, Yokohama, Kanagawa 226-0006, Japan. ogaki-masataka@hhs.hitachi-hitec.com.
authors.forename: Masataka
authors.initials: M
authors.lastname: Ohgaki
keywords: Co; Hx(Ni; Mn)O2; electrochemical capacitors; energy storage devices; layer-structured materials; nanosheets