Processing and surface modification of titanium open cell porous structures for PEM fuel cell bipolar plates

Abstract

Bipolar plate (BP) and porous transport layer (PTL) materials and designs are critical for the performance of a proton exchange membrane fuel cell (PEMFC) and electrolyser (PEMEC) due to their role as fluid distributor and electron transporter between cells. Designs based on open cell porous structures require a good control on the porosity features. The aim of this work is to use powder metallurgy to manufacture titanium porous structures and the use of suitable surface modification techniques that can improve the performance of the PEM systems, focusing on fuel cells. Using the space holder method, porous structures of up to 63% porosity and controlled pore size can be processed to tailor the characteristics for an optimal design and, through a simple gas nitriding treatment, the performance of the material in terms of interfacial contact resistance (below 10 mΩcm2 after corrosion) and corrosion resistance (below 1 μAcm−2) are improved for both dense and porous structures.