Functionalized Silica Composite Membranes for Direct Methanol Fuel Cells

Novel silica aerogels functionalized with sulfonic acid were synthesized and employed in the preparation of composite membranes for DMFC applications. The additives had an ionic conductivity on the order of 100 mS/cm at 60 degrees C and 100% relative humidity. An enhancement in ionic conductivity was observed when using the functionalized aerogels as inorganic fillers within an SPEEK matrix to prepare composite membranes. The addition of 10 wt% of the sulfonated silica aerogel to SPEEK doubled the conductivity of the membrane. The methanol permeability of the composite membranes was higher that pristine SPEEK membranes although the values measured for composite membranes with 10 wt% additive were still acceptable for use in DMFC applications.