Anisotropic radio-chemically pore-filled anion exchange membranes for solid alkaline fuel cell (SAFC)

Abstract

Anion exchange pore-filled membranes based on meso-porous polyethylene support are fabricated through a radio-chemical grafting process. Vinylbenzylchloride (VBC) monomers are grafted onto porous polyethylene substrate by a simultaneous irradiation grafting method. The porous polyethylene substrate provides high chemical and mechanical stability. The pore-filled membranes are subsequently functionalized by trimethylamine (TMA) and ion exchange with sodium hydroxide, yielding alkaline anion exchange membranes that are capable of conducting hydroxide ions. The mesa-porous support structure contributes to a reduction in dimensional swelling while maintaining high water uptake, high ion exchange capacity, and enhanced mechanical strength of over 50 MPa. In particular, these radio-chemically pore-filled membranes exhibits anisotropic through-plane oriented ion conductive behavior due to the low resistance of the hydrated cross-sectional structure derived from the nonwoven porous substrate. As a result of reinforced mechanical strength and anisotropic electrochemical property, the membrane exhibits good membrane-electrode assembly (MEA) performance (at 0.6 V, max. current density=174 mA cm(-2) and max. power density=127 mW cm(-2)) in solid alkaline fuel cell.