title: A sodium manganese oxide cathode by facile reduction for sodium batteries.
abstract: A nonstoichiometric sodium manganese oxide (Na(x)MnO(2+δ)) cathode useful for sodium batteries was synthesized by an ambient-temperature strategy that involved facile reduction of aqueous sodium permanganate in sodium iodide and subsequent heat treatment at 600 °C. Combined powder X-ray diffraction and synchrotron X-ray diffraction analyses confirmed the annealed sample to belong to a Na(x)MnO2 phase with a P2-hexagonal structure. The ICP-AES results confirmed the stoichiometry of the sample to be Na0.53MnO(2+δ) . Electron microscopy studies revealed the particle size of the electrode to be in the range of a few hundred nanometers. The Na0.53MnO(2+δ) cathode delivered an average discharge capacity of 170 mA h g(-1) with a stable plateau at 2.1 V for the initial 25 cycles versus sodium. Ex situ XANES studies confirmed the reversible intercalation of sodium into Na0.53MnO(2+δ) and suggested the accommodation of over-stoichiometric Mn(4+) ions to contribute towards the performance of the electrode.
authors.affiliation: Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong dong, Buk-gu, Gwangju 500-757 (South Korea), Fax: (+82) 62-530-1699.
authors.forename: Jinju
authors.initials: J
authors.lastname: Song
authors.forename: Jihyeon
authors.initials: J
authors.lastname: Gim
authors.forename: Sungjin
authors.initials: S
authors.lastname: Kim
authors.forename: Jungwon
authors.initials: J
authors.lastname: Kang
authors.forename: Vinod
authors.initials: V
authors.lastname: Mathew
authors.forename: Docheon
authors.initials: D
authors.lastname: Ahn
authors.forename: Jaekook
authors.initials: J
authors.lastname: Kim
keywords: electrochemistry; electrodes; energy conversion; intercalation; sodium batteries