Proton Storage Properties of Manganese Oxides with Tunnel Structures

Tatsuki Dohkoh; Shinya Suzuki; Masaru Miyayama

doi:10.4028/www.scientific.net/KEM.566.145

Paper Titles

Synthesis and Characterization of Ramsdellite Type Lithium Titanate Anode Materials by Spray Pyrolysis
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Effect of Heat Treatment on Charge-Discharge Property of Fluoride Cathode Materials for Li Ion Secondary Batteries
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Preparation of Ce_0.8Sm_0.2O_1.9 Thin Films by Electrophoretic Deposition and their Fuel Cell Performance
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Microscopic Conduction Behavior Analysis on ZrO₂-Based Ion Conductors by Wideband Conductivity Measurement
p.141

Proton Storage Properties of Manganese Oxides with Tunnel Structures
p.145

The Microstructure of Titanium Oxide Films for Dye-Sensitized Solar Cells
p.149

Effects of Annealing Process on the Structure of Mn-Doped BiFeO₃ Thin Films
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Ferroelectric Properties Improvement of Mn-Doped 0.7BiFeO₃-0.3BaTiO₃ Thin Films Fabricated by Chemical Solution Deposition
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Fabrication of BiFeO₃-Bi(Zn_1/2Ti_1/2)O₃ Solid Solution Thin Films Using Perovskite-Type Oxide Interface Layer
p.163

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Proton Storage Properties of Manganese Oxides with Tunnel Structures

Abstract:

The electrochemical capacitors (ECs) have attracted a great attention as a rechargeable strage device with a high power density and high safety. An increase in specific capacity is demanded to use ECs in various applications. MnO₂ are expected as electrodes of ECs because of their large oxidation state change (Mn⁴⁺ Mn²⁺), low cost and environmental compatibility. When all manganese ions in the MnO₂ are completely reduced to Mn²⁺ from Mn⁴⁺ over a potential window of 1.1 V, the theoretical capacity is estimated to about 2000 Fg^-1. However, the reported capacity of MnO₂ electrodes are 100250 Fg^-1 [1-2] for powders and around 700 Fg^-1 [3] for thin films. Tunnel structured MnO₂ are expected to show high capacities by utilizing high ionic mobility in the tunnel and high surface area of tunnel walls. Fig. 1 shows crystal structures of (a) Pyrolusite (Tunnel size: 1×1), (b) Hollandite (Tunnel size: 2×2) and (c) OMS-5 (Tunnel size: 2×4) and (d) MnO₆ unit. In the present study, the relationship between the tunnel size and the specific capacity was investigated for those tunnel structured MnO₂. In addition, Hollandite /carbon composites were synthesized to improve the electrode properties of Hollandite.