Percolative model of proton conductivity of Nafion® membranes
- 作者：Paola Costamagna ; Simone Grosso ; Renzo Di Felice
- 关键词：Transport phenomena ; Modelling ; Nafion® ; ; Percolation theory ; Porous materials ; Fuel cells
- 刊名：Journal of Power Sources
- 出版年：2008
- 期刊代码：58_03787753
- 类别：ce
- 出版时间：1 April 2008
- 卷：178
- 期：2
- 页码：537-546
- 文件大小：726 K
摘要
A model is proposed for the simulation of Nafion® proton conductivity, where it is assumed that proton conduction occurs only in the water present in the membrane pores. Water is considered to be present in the pores due to two different phenomena: adsorption and capillary condensation. In the latter case, the pore is flooded and proton conduction occurs throughout the whole pore section. The conditions under which capillary condensation occurs are simulated in the model through the Kelvin–Cohan equation for condensation. The Kelvin–Cohan equation is a function of RH, temperature and the pore radius; the larger the pore, the higher the RH for which capillary condensation takes place. If the conditions for capillary condensation are not satisfied, then water is present in the pore due to adsorption under the form of a water layer which covers the pore walls and provides a path for proton conduction. In this case, the modified Brunauer–Emmet–Teller (BET) equation has been used in the model to simulate the thickness of the water layer.