Contribution of nanoclays to the barrier properties of a model proton exchange membrane for fuel cell application

Abstract

Direct methanol fuel cells (DMFCs) that use a proton exchange membrane (PEM) as electrolyte, is a promising alternative source of energy for the future. However, methanol crossover from the anodic side to the cathodic one is a major problem in DMFC. Proper dispersion of layered silicates within the fuel cell membrane has been proposed as a strategy for improving the barrier properties of the membrane. The validity of this approach has been tested in case of a model membrane consisting of phosphotungstic acid doped poly(vinyl alcohol). A solvent casting technique has been used, which allows the nanofiller to be delaminated by an ultrasonic pretreatment, as confirmed by TEM and XRD analysis. The layered silicates have a favourable impact on the methanol permeability, whose the decrease overcompensates some loss in ionic conductivity.

Beneficial effect of carbon nanotubes on the performances of Nafion membranes in fuel cell applications

“…PBI membranes are remarkable because they do not need to be humidified for exhibiting high ionic conductivity, which allows for operation at temperature higher than 100°C. The second strategy relies on the modification of ion-conducting polymers by inorganic fillers, such as silica [11,12], heteropolyacid [13,14], zirconium phosphate [15][16][17] and multi-layered silicates (montmorillonite) [18][19][20][21][22][23][24]. The main reason for the addition of these inorganic fillers is to reduce the methanol permeability while keeping the ionic conductivity as high as possible.…”

Polymer-Layered Silicate Nanocomposite Membranes for Fuel Cell Application

“…22.10) [116]. However, the methanol permeability of the PVOH-clay nanocomposites was noted to increase with the clay content beyond 7 wt% clay content due to the increased aggregation of clays (or reduced number of individual sheets) [110]. Hence, exfoliated clay morphology and better polymer-clay interaction can reduce the permeability of both water and methanol to a significant extent and vice versa.…”

“…Similarly, water was chosen for the water soluble polymer like poly(vinyl alcohol) (PVOH). The as-prepared PVOH-clay membrane was immersed in HPW solution in water (0.66 wt%) to improve the proton conductivity [110].…”

Non-fluorinated proton-exchange membranes based on melt extruded SEBS/HDPE blends

“…Generally, inorganic fillers must be proton conducting, such that methanol permeation is decreased without overly compromising proton conductivity. The inorganic proton-conducting moieties that have been considered range from weakly acidic silica [16] and neutral titanium oxides [17] and clays [18], through common acids such as phosphoric acids, to super acids such as the heteropolyacids [19] and zirconium phosphonates [20].…”