摘要
提出一个考虑了催化层中电压不均匀分布，可以在任意气体压力ｐ、输出电流密度Ｉ工作条件下，表征ＰＡＦＣ空气电极行为的数学模型．发现表征“气／液”相界面比表面的参数ＡＢ与Ｉ在不同的ｐ下呈不同的线性关系．其中在较低的压力下ＡＢ对Ｉ有较深的依赖关系，而在较高的压力ｐ下，ＡＢ趋向与Ｉ无关．表征“液／固”界面的参数ＡＩ在不同ｐ、Ｉ下基本保持不变．利用所构建的数学模型对ＰＡＦＣ空气电极中催化反应层内Ｏ２电化学还原速率进行了定量分析．结果表明，大电流下运行的空气电极，其主要的电极反应发生在“扩散层／催化层”交界处的催化反应层中，意味着厚的催化反应层是不必要的．
A mathematical model of the air electrode used in the phosphoric acid fuel cells(PAFC) was developed. This model accounts for the diffusion of oxygen and the distribution of electrode potential across the air electrode. The model was applied to simulate the cathode performance under a variety of conditions. Two parameters AB and AI were introduced into the model. They respectively reflect the effects of the interfacial surface area between the gas and liquid phases and those of the interfacial surface area between the liquid and solid phases, on the air electrode performance. AB and AI can be determined with the aid of the operating conditions and potential-current density curves of the air electrode. The main interface parameters of the air electrode can be predicted after the determination of AB and AL It is found that there is a linear relationship between the parameter AB and the current density but that parameter AI only oscillates in a very narrow range for all current densities. The reaction rate throughout the catalyst layer was calculated by means of the model, and the results show that the reduction of oxygen does not occur uniformly in the catalyst layer. The degree to which the reduction of oxygen takes place in the catalyst layer varies with current densities. The higher the operation current density, the more probability with which the reduction of oxygen takes place in the section of catalyst layer close to the diffusion layer.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2001年第10期892-897,共6页
Acta Physico-Chimica Sinica
基金
国家自然科学基金资助项目(2997604)
