Proton Conduction Properties of Sulfonicacid Type Polymer Gel Electrolytes

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• 作者：Yuria Saito*^† ; ; Tatsuya Umecky^† ; ; Hiromasa Omukai^† ; ; Seiji Maeda^‡ ; ; Toshikatsu Kojima^† ; ; Tetsuo Sakai^† ;
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：February 19, 2009
• 年：2009
• 卷：113
• 期：7
• 页码：3021-3028
• 全文大小：289K
• 年卷期：v.113,no.7(February 19, 2009)
• ISSN：1932-7455

文摘

Conduction properties of the proton conductive polymer gel electrolytes were investigated by the measurements of the sulfonicacid site concentration, proton concentration after the dissociation from the site, proton conductivity, and diffusion coefficient of the ¹H species. The proton mobility, μ_H+, estimated from the conductivity and proton concentration, as a function of the water fraction of the gel, showed a change with a maximum. At the higher water content over the maximum point, μ_H+ converged to the proton mobility in the bulk water. This changing feature reveals that there is an optimum concentration of the gel ([H⁺]/[H₂O]) responsible for the μ_H+ maximum. A specific region at the interface between the polymer chains and water molecules could be formed which permits the efficient proton hopping. This is confirmed by the measurement of the ¹H relaxation time, T₁. Correlated with the μ_H+ increase with increasing the water content of the gel, T₁’s increase is restricted, showing the T₁-flat region. This anomalous region would be associated with the structural features of the polymer. One is the nanolevel feature, concentration of the acid site at which the sulfonate group after the proton dissociation would play the part of the base for keeping the water molecules close to the chains. The other is the macroscopic aspect of the polymer, the free volume space of the polymer molecules. Associated with the size and form of the space, the layered region of the water molecules around the polymer chains could be formed, which is effective for proton hopping transport taking advantage of the mobile water and sulfonate groups.