Sulfonated-perfluorocyclobutane polyelectrolyte membranes for fuel cells

Abstract

A process for preparing a polymer comprising sulfonating a perfluorocyclobutane polymer with a sulfonating agent to form a sulfonated perfluorocyclobutane polymer, wherein the sulfonating agent comprises oleum or SO₃ is provided. A process for preparing proton exchange membranes and fuel cells comprising the proton exchange membrane are also provided.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to electrochemical conversion cells, commonly referred to as fuel cells, which produce electrical energy by processing first and second reactants. For example, electrical energy can be generated in a fuel cell through the reduction (cathode reaction: O2+4H++4e−→2H2O) of an oxygen-containing gas and the oxidation (anode reaction: 2H2→4H++4e−) of a hydrogenous gas. By way of illustration and not limitation, a typical cell comprises a membrane electrode assembly positioned between a pair of flow fields accommodating respective ones of the reactants. More specifically, a cathode flowfield plate and an anode flowfield plate can be positioned on opposite sides of the membrane electrode assembly. The voltage provided by a single cell unit is typically too small for useful automotive power application so it is common to arrange a plurality of cells in a conductively coupled “stack” to increase the electrical output of the elec...

AI Technical Summary

Benefits of technology

[0003] Recently, proton exchange or polyelectrolyte membrane (PEM) fuel cells have attracted considerable interest as sources of non-polluting, high-density power for automotive propulsion. However, for widespread commercialization, low cost, high-performance PEMs with improved durability are still being sought. Presently, PEM fuel cells operate at temperatures up to 95° C. with external humidification being required to maintain proton conductivity that deteriorates rapidly as the membranes dry out. Perfluorosulfonic acid membranes have been the preferred materials for PEM, but they suffer from poor mechanical integrity and they are expensive. Consequently, new alternative PEM materials are continuously being sought.

Problems solved by technology

Perfluorosulfonic acid membranes have been the preferred materials for PEM, but they suffer from poor mechanical integrity and they are expensive.

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