Influence of the size and shape of silica nanoparticles on the properties and degradation of a PBI-based high temperature polymer electrolyte membrane

Efficient water management of composite membranes operated in polymer electrolyte membrane fuel cells under low relative humidity

“…The proton conductivity of the Nafion membrane is highly affected by the amount of water absorbed in the membrane, and the maximum proton conductivity is attained when the membrane is fully sa-Several effective approaches have been employed to improve the performance of the electrolyte membrane operated under low RH including introduction of anhydrous proton-conduction group into the membrane [12][13][14], discovery of new polyelectrolyte membrane which is less sensitive to RH [15,16], and incorporation of the hydrophilic materials to increase the water retention ability in the membrane [17][18][19]. Incorporation of the water retention fillers in the electrolyte membrane such as SiO 2 [20][21][22][23][24][25], TiO 2 [25][26][27][28][29][30][31][32][33][34][35][36][37][38], ZrO 2 [25,[39][40][41][42][43][44], and heteropolyacids [45][46][47] etc., which are both hygroscopic and proton conductors, is widely accepted strategy to improve the membrane performance operated under low RH. However, incorporating hygroscopic filler particularly nanoparticles in Nafion membrane does not enhance the fuel cell performance operated under fully humid conditions, owing to the serious aggregation of nanoparticles which yields insufficient both water electroosmotic drag and water back-diffusion through the membrane …”

Novel sulfonated poly (ether ether ketone)/phosphonic acid-functionalized titania nanohybrid membrane by an in situ method for direct methanol fuel cells

“…Such prepared membranes exhibit good interfacial compatibility as well as enhanced water retention property and mechanical stability [29,30]. As we know, acid-functionalized nanoparticles are favorable to increase proton conductivity due to their ability to bridge the hydrophilic domains of polymers [20], and their high surface area enables high loading of acid groups [33]. However, since too fast a rate of solegel reaction will cause heterogeneity in hybrid membranes, more controllable methods remain to be explored [34].…”

Improvement of Nafion®-sepiolite composite membranes for PEMFC with sulfo-fluorinated sepiolite

“…Yet it is not really adapted to operating temperatures higher than 90°C whereas this would decrease many constraints on the quality of hydrogen or the system cooling for instance. Metal oxides such as SiO 2 [16,17,18,19,20,21,22,23], ZrO 2 [24,25] or TiO 2 [26,27,28,29,30,31,32] have been used to simultaneously decrease the membrane hydrogen crossover and its sensitivity to relative humidity, without significantly impacting the membrane proton conductivity below roughly 10 wt.% loading. Acids [33,34,35,36,37,38], phosphates or phosphonates [39,40,41,42] have the additional advantage to increase the membrane ion exchange capacity with beneficial effect on its proton conductivity.…”