Celgard/PIM-1 proton conducting composite membrane with reduced vanadium permeability

Renewable energy systems need efficient and cheap storage devices and vanadium redox flow batteries (VRB) may become one of them. However, better performance of VRB membranes yet should be achieved. Novel composite Celgard-based films coated with PIM-1 for aqueous electrolyte VRB applications are presented. Two types of the composites with different PIM-1 loadings are obtained. Their properties are studied and compared with the original Celgard films. The deposited PIM-1 forms a smooth layer on the outer Celgard surface and penetrates inside the porous matrix, thus significantly reducing the pores diameter and affecting the transport properties of the composite film. The nanoporous structure of PIM-1 permits size-screening of H3O+/hydrated vanadium ions when used in aqueous vanadium redox flow batteries applications, which allows to tailor the membrane permeability for the two types of ions and, therefore, to increase its selectivity from 4.3 x 10(6) to 1.3 x 10(7) mS min cm(-3), while maintaining high proton conductivity.