Structural Variation in the γ/β-MnO2 Series and Its Influence on Cathodic Cyclability
| Autor: | Mark R. Bailey, Scott W. Donne |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | ECS Transactions. 58:109-124 |
| ISSN: | 1938-6737 1938-5862 |
| DOI: | 10.1149/05825.0109ecst |
| Popis: | In this work the electrochemical behavior of a series of heat treated γ-MnO2 materials was investigated and related to the chemical and structural changes brought about by this process. Controlled current cycling revealed a progressive decrease in electrode cyclability with heat treatment and this was assigned to irreversible changes which occur within pyrolusite domains upon reduction. It was further shown that for materials with a pyrolusite content > 0.5 the host structure is no longer suitable for reversible electron-proton insertion, with electrodes prepared from these materials failing beyond the first cycle. By modelling the electrode response during step potential electrochemical spectroscopy studies the changes in proton diffusivity which result from heat treatment were also characterized. These studies were able to experimentally demonstrate that proton diffusion is progressively slower in materials with higher pyrolusite content, while being significantly enhanced by the presence of cation vacancies. |
| Databáze: | OpenAIRE |
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