[ materials ] is the materials selection . Qualifying the right material means choosing something that usually excels in one of four areas : cost , durability , performance , and sustainability . And pretty much any material you choose is going to fall into one of those spectrums .
For example , for a given application , the attempts to improve the proton exchange membrane ( PEM ) transport properties ( performance ) will likely deteriorate its mechanical properties ( longevity ). And the advancements to the materials performance without compromising its durability will require understanding and refining of the phase-separated morphology typical for PFSAbased PEM .
Another interesting case is the fact that the conventional fuel cell materials have been
optimized only for the particular operating points , whereas their function in the electrochemical device means meeting the set of contradictory requirements .
Take diffusion media sandwiching catalyst coated membrane ; state-of-the-art gas diffusion layer ( GDL ) is responsible not only for the fine distribution of reactant gases , but also for the transport of product water , heat and electrical current . This implies the GDL materials must meet ( and in fact should be optimized towards ) the triple set of contradictory requirements : high diffusivity of the gas phase , high permeability of the water phase , and high thermal and electrical conductivity of the solid phase . Conventional GDLs have been optimized only for dry , hydrated or saturated conditions ( Figure 1 ).
Fig . 1 . Performance characteristics of conventional GDLs optimized for different operating points depending on GDLs hydrophobicity . Adapted from : Applied Energy 149 ( 2015 ): 186 – 193 .
Hydrogen Tech World | Issue 15 | April 2024 19