Further understanding of reaction processes in electrolytic manganese dioxide electrodes for lithium cells

Miki Nagao, Cédric Pitteloud, Takashi Kamiyama, Toshiya Otomo, Keiji Itoh, Toshiharu Fukunaga, Ryoji Kanno

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Lithium insertion in interstitial space was investigated for electrolytic manganese dioxide (EMD), γ-MnO2, as a new cathode reaction in lithium battery. Its structure and proton dehydration mechanism were characterized by X-ray and neutron diffraction-pattern simulation. The heat-treatment process activated the EMD as insertion electrodes and caused dehydration with structural changes, which were described by modifications in stacking sequence of the ramsdellite (+R) to pyrolusite (+P), and their twinning types (-R and -P). By the heat-treatment of EMD, the -R ratio decreased and the -P increased with increasing temperature, and finally the structure transformed to +P above 400°C. The void size was determined by small-angle neutron scattering and decreased with the treatment temperature. The total neutron diffraction indicated two types of protons with H-O length of 1.0 and 1.9 Å, which corresponds to the "Ruetschi" and "Coleman" protons, respectively. The former proton situated in the Mn4+ vacant site and the latter in the center of the tunnel. Lithium insertion properties depended on both the structures and the amount of proton. Dehydration of the Ruetschi proton without destroying interstitial space improved the lithium insertion capacities as reversible cathodes.

Original languageEnglish
Pages (from-to)E230-E237
JournalJournal of the Electrochemical Society
Volume152
Issue number7
DOIs
Publication statusPublished - Aug 22 2005
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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