There are two main advantages of high inorganic content membranes with smaller pore sizes. The first advantage is that when the pore size is small, the hydrophobicity is increased due to the original property of PE. As a result, hydrophilic solution permeation could be reduced. The second advantage is that the pore size is smaller, the surface area of the PE is larger, and the surface area of the ZrP filled in the PE is larger accordingly. Thus, the counter-ion on the ZrP surface, which efficiently conduct protons, can be increased. Previous studies proved that in ZrP crystals, the counter-ions on the surface are 10 4 times more likely to transport current than the ions inside . Therefore, if the substrate with a larger surface area, namely, with smaller pore sizes, can be filled with a higher concentration of ZrP, a higher conductivity could be achieved.