Enhancement in proton conductivity and methanol cross-over resistance by sulfonated boron nitride composite sulfonated poly (ether ether ketone) proton exchange membrane

Abstract

Fuel cells are the promising new non-conventional power source for vehicles as well as portable devices. Direct methanol fuel cell (DMFC) is especially attractive since it uses low cost liquid methanol as a fuel. Proton exchange membrane is one of the most crucial part of DMFC. Herein, we synthesized the sulfonated boron nitride (SBN) based SPEEK composite membranes for the DMFC application. SBN was synthesized by covalent functionalization of hydroxylated BN by using 3-mercaptopropyl trimethoxysilane and sulfonated by subsequent oxidation of mercapto group. Sulfonated poly (ether ether ketone) is used as a polymer matrix for SBN. With well controlled content of SBN into SPEEK matrix exhibit high proton conductivity, IEC and water content along with excellent mechanical strength. Composite membranes show low methanol cross over and high selectivity, which makes them attractive candidate for proton exchange membrane for direct methanol fuel cells.