Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

•Composite membranes are prepared with different montmorillonites and nafion solution.•Proton conductivities of the composite membranes are between 36.0mS/cm and 38.5mS/cm.•Ethanol permeability is between 0.69×10−6cm2/s and 2.67×10−6cm2/s.•Water uptake is approximately 24.30mass%. The preparation of Nafion membranes modified with montmorillonites is less studied, and most relative works mainly applied in direct methanol fuel cells, less in direct ethanol fuel cells. Organic/inorganic composite membranes are prepared with different montmorillonites (Ca-montmorillonite, Na-montmorillonite, K-montmorillonite, Mg-montmorillonite, and H-montmorillonite) and Nafion solution via casting method at 293K in air, and with balance of their proton conductivity and ethanol permeability. The ethanol permeability and proton conductivity of the membranes are comparatively studied. The montmorillonites can well decrease the ethanol permeability of the membranes via inserted them in the membranes, while less decrease the proton conductivities of the membranes depending on the inserted amount and type of montmorillonites. The proton conductivities of the membranes are between 36.0mS/cm and 38.5mS/cm. The ethanol permeability of the membranes is between 0.69×10−6cm2/s and 2.67×10−6cm2/s.