成果報告書詳細
管理番号20110000001107
タイトル*平成22年度中間年報 固体高分子形燃料電池実用化推進技術開発 次世代技術開発/次世代電解質膜の劣化特性評価シミュレータの開発
公開日2011/10/12
報告書年度2010 - 2010
委託先名国立大学法人東北大学
プロジェクト番号P10001
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等 本研究開発テーマでは、劣化特性を決定する要因として活性化酸素種(OHラジカル、過酸化水素)の物質移動に注目し、環境因子によって変化するこれらの物質移動量を予測することで、炭化水素系電解質膜の劣化挙動を評価できるミュレータ技術の研究開発を実施する。 平成22年度の目標は次のとおりである。 ・下記に示す(1)~(4)についてシミュレータのプロトタイプを完成させる。 ・(1)(2)について少なくとも1つの炭化水素系電解質について活性酸素種の膜中での拡散係数及びその分布を算出する。
英文要約Title: Development of Simulator for Prediction of Degradation Degree of Polymer Electrolyte (FY2010-FY2011) FY2010 Annual Report
Durability is a critical issue of polymer electrolyte in fuel cell. The aim of this project is to make the codes for theoretical prediction of degradation degree of polymer electrolyte using the data of atomistic structure of electrolyte. We carried out chemical reaction molecular dynamics (MD) for diffusion process of OH radicals in the perfluorinated sulfonic acid (Nafion) and sulfonated polyimides (SPI-8-p) membranes. The properties of membranes having different contents of water molecules were modeled to estimate the diffusivity of radical species through the membranes.
In the case of SPI-8-p, the calculated OH diffusivity increases as the increase in the water contents but decrease in the range over 15 water wt% showing the maximum. This trend is also observed for the case of Nafion. The diffusion lengths of OH radical during 10^-6 second, which is usual life time of OH radices, were estimated less than 40 nm for all models, which mean that the region where OH radicals exist is assumed to be the region where the OH radicals are generated. We also employed quantum chemical (QC) calculations based on density functional theory for revealing the reaction mechanism between OH radicals and the membranes. The energy profile analysis of reactions against OH radicals obtained by QC calculation reveals that the degradation favorably starts from the bond breaking in imide ring and side chain in the case of SPI-8-p. The degradation rate for each bond breaking is calculated as 9.6x10^11 - 9.7x10^11 1/s, which means the reactions are enough fast for the comparison of the time scale of diffusion of OH radicals. Thus it is concluded that degradation of SPI-8-p by oxidation can be described as the diffusion limited process. Thus the degree of degradation SPI-8-p is estimated if the amount of OH radicals generation is known, which will be investigated in the next financial year. The results were successfully presented in 4 domestic technical conferences.
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