Novel Proton Exchange Membrane with Long-Range Acid–Base-Pair Proton Transfer Pathways Based on Functionalized Polyethyleneimine

Abstract

Mass transport in proton exchange membrane fuel cells (PEMFCs) is critical to their efficiency and energy output, especially the transfer of protons and water that occurs in the PEM. Here, we describe designing and fabricating a novel composite PEM based on perfluorosulfonic acid (PFSA) and polyethyleneimine functionalized with methylphosphonic acid (PEIMPA), with the aim of constructing efficient mass transfer pathways using longrange acid−base pairs. Improvements in water absorption/ retention, proton conductivity, and single-cell performance resulted from these long-range transfer pathways, as the acid−base pairs and abundant water-retaining groups in the membrane enhanced the connectivity of the hydrophilic zone, forming new proton and water transport pathways. These improvements in water and proton transport also gave the PFSA/PEIMPA composite membranes higher reversal tolerance. Their excellent physical and chemical properties make these membranes promising candidates for PEMFC applications by reducing dependency on water content, enhancing fuel cell performance at low relative humidity, and improving the fuel cell's tolerance toward reversal.

Construction of Surface Sulfonic and Amino Acid–Base Pair Modified Graphene Oxide for Effectively Promoting the Selectivity of the Proton Exchange Membrane

“…5,27 So far, various basic group functionalized materials have been introduced into sulfonated polymer matrixes to build acid−base pair proton conductive routes. 28,29 Especially, incorporation of suitable amino functionalized materials into sulfonated polymer matrixes can construct effective sulfonic and amino (−SO 3 H and −NH 2 ) acid−base pairs for proton conduction. 30,31 This is mainly based on the following aspects of consideration.…”

“…So far, various basic group functionalized materials have been introduced into sulfonated polymer matrixes to build acid–base pair proton conductive routes. , Especially, incorporation of suitable amino functionalized materials into sulfonated polymer matrixes can construct effective sulfonic and amino (−SO 3 H and −NH 2 ) acid–base pairs for proton conduction. , This is mainly based on the following aspects of consideration. On one hand, the host sulfonated polymer matrixes possess good proton conducting abilities and simultaneously keep favorable dimensional stabilities under appropriate sulfonation degrees. , On the other hand, protons can readily dissociate from −SO 3 H of sulfonated polymer matrixes (losing protons easily to transform into −SO 3 – ) to jump to the adjacent −NH 2 (accepting protons easily to transform into −NH 3 + ) .…”

Design and development of nucleobase modified sulfonated poly(ether ether ketone) membranes for high-performance direct methanol fuel cells

“…25,26 Thus, blending of a basic polymer containing N-heterocycles with a sulfonic acid polymer is conducive to reducing membrane swelling, improving mechanical properties and decreasing the methanol crossover of membranes. [27][28][29][30][31] Various researches have been reported on composite membranes of SPEEK with imidazole-groupcontaining polymers, particularly poly(benzimidazole) (PBI), which showed low methanol crossover. [32][33][34] For example, Li et al reported that, by increasing the content of PBI from 2.5 to 15%, the methanol crossover of the membranes decreased from 7.92 Â 10 À7 to 3.10 Â 10 À7 cm 2 s À1 .…”

Interfacial and Internal Proton Conduction of Weak-acid Functionalized Styrene-based Copolymer with Various Carboxylic Acid Concentrations

“…[4][5][6][7][8][9] Many studies have published proton transport improvement in an anhydrous state using acid-base combinations of proton conductors. [10][11][12][13][14][15][16] In this system, proton donors are acid groups with low pK a values because protons are readily dissociated. By contrast, the basic groups act as proton acceptors, this proton reception and release continue the transportation.…”

“…By contrast, the basic groups act as proton acceptors, this proton reception and release continue the transportation. 16 The effects of acid and base functional group concentration on the proton conductivity across protein biopolymers have been reported. Improvement of proton conductivity was found in bovine serum albumin(BSA)-mat with hydroxyl, amine, and carboxylic acid functionalized carbon-dots addition.…”