Analysis of Degradation Mechanisms and Durability Assessment of Graphene-Based MPLs for PEM Fuel Cells

Abstract

Novel graphene-based microporous layers (MPLs) have been developed as a possible alternative to conventional carbon black-based MPLs aiming to enhance electrical performance and durability of PEM fuel cell systems. Graphene nanoplatelets (GNPs) have been used as carbonaceous conductive phase in the ink formulation for MPL due to their low electrical resistance, high surface area and mechanical stability. The novel MPLs exhibited more homogeneous and less cracked surfaces compared to MPLs containing carbon black. Such enhanced MPL surface resulted in a better electrical contact between MPL and fuel cell electrode and a consequent lower ohmic resistance. Moreover, chemical and mechanical accelerated stress tests were developed in order to evaluate durability of the prepared samples and the most detrimental degradation mechanism. Fresh MPLs showed very similar electrochemical behaviors in running fuel cells while GNPs-based MPLs proved to be more resistant against both stress factors than conventional ones.

Characterization of novel graphene-based microporous layers for Polymer Electrolyte Membrane Fuel Cells operating under low humidity and high temperature

“…The carbon phase was alternatively CB, GNP-S, GNP-M and EG alone or a combination of CB with alternatively GNP-S, GNP-M and EG in a 1:1 weight ratio. All the mixes featured a 10 wt.% addition of CNTs that has been proved to improve the conductivity of the MPL [52][53].…”

Graphene-based microporous layers for enhanced performance in PEM fuel cells

“…The MPL was obtained by coating the GDL with a carbon-based ink. This featured: a main carbon phase, either Vulcan XC72R carbon black or graphene nanoplatelets (Sigma-Aldrich), multi-wall carbon nanotubes, that have proved to increase the conductivity of the GDL, deionized water as solvent, isopropyl alcohol as dispersing agent, FEP as hydrophobizing agent [17][18][19][20]. After mechanical stirring at 8000 rpm for 10 minutes, the ink was deposited via doctor blade-coating and heat treated to allow the evaporation of isopropyl alcohol and water.…”