Membrane/ionomer proton conductivity water content

FIGURE 13.14 (a) Comparison between estimated proton conductivities on Pt whiskers and measured conductivities of the ionomer in a bulk membrane and in a conventional electrode with ionomer-to-carbon content of 0.97, at 80°C as a function of RH. For comparison, the conductivity of distilled water at 25°C is also shown, (b) ORR current density distributions across the (0.23- om-thick) NSTF cathode at i= with high stoichiometric flows of ECS. 

The group of GKSS Research Center Germany extensively researched the effect of a variety of inorganic nanoparticles on the properties of aromatic ionomer membranes [86-93]. Composite membranes were prepared from silicates and sulfonated poly(ether ketone)s or sulfonated poly(ether ether ketone)s. For DMFC applications, the composite membranes showed promising properties with lower methanol and water permeability and comparable (or higher) proton conductivity compared to the parent polymer membranes. The flux of water and methanol decreased with the increase in content of silicates. 

Water management is arguably the most critical component of fuel cell operation. The currently available membranes and catalyst layer ionomers require a high water content to maintain proton conductivity. However, the presence... 

---