Characterizing PEM fuel cell catalyst layer properties from high resolution three-dimensional digital images, part III: Contact angle distribution.

The wettability properties of the porous components in a proton exchange membrane fuel cell (PEMFC) are a key factor in relation with the water management issue and a key information in order to predict the water retention curve, a crucial input data for the macro-homogeneous models. In this work, we propose an approach to construct the contact angle distribution in three-dimensional digital images of the cathode catalyst layer. Various reconstruction scales are considered, from the platinum particle scale to the pore scale and the scale of sub-blocks in the CCL. This leads to effective contact angle distributions depending on the scale of interest. The approach also allows to investigate the link between the pore size and the effective contact angle at the pore scale. The combined information of the pore size and the effective contact angle for each pore is used to get insights into the water retention curve. • Contact angle distributions are computed in the secondary pore space. • The impact of the ionomer coating thickness spatial variation is considered. • The effective contact angle is determined for each pore. • The water retention curve is obtained. [ABSTRACT FROM AUTHOR]