Hydrophilic side-chain polymer, electrolyte membranes

Abstract

Exemplary methods for the characterization of proton dissociation and transport for hydrophilic components of hydrated Polymer Electrolyte Membranes (PEM's) is described. Disclosed features and specifications may be variously implemented, controlled, adapted or otherwise optionally modified to improve differential hydrophilicity of the sidechain of any ionomeric PEM material. A representative embodiment of the present invention generally provides for the amelioration of electro-osmotic drag of water by protons, for example, in Direct Methanol Fuel Cells.

Description

FIELD OF INVENTION [0001] The present invention generally concerns fuel cell technology; and more particularly, in one representative and exemplary embodiment, the characterization of proton dissociation and transport for hydrophilic components of Polymer Electrolyte Membranes (PEM's). A PEM material comprising a novel differential sidechain chemical composition is also disclosed as inter alia preventing or otherwise ameliorating electro-osmotic drag as the membrane material experiences increased swelling upon permeation with, for example, aqueous methanol. BACKGROUND [0002] Fuel cells are electrochemical cells in which a free energy change resulting from a fuel oxidation is converted into electrical energy. The earliest fuel cells were first constructed by William Grove in 1829 with later development efforts resuming in the late 1930's with the work of F. T. Bacon. In early experiments, hydrogen and oxygen gas were bubbled into compartments containing water that were connected by a...

AI Technical Summary

Benefits of technology

The present invention provides a system and method for characterizing and customizing ionomeric membranes that tend not to experience significant increases in electro-osmotic drag upon exposure to aqueous methanol. The invention involves modifying the sidechain of the membrane material to increase its hydrophilicity, which prevents or reduces the increase in electro-osmotic drag while maintaining good proton conductivity. The invention also provides a method for predicting the permittivity of water in the membrane pores, which can be used to model the dielectric saturation of the membrane. The invention has been found to be useful in predicting the behavior of ionomeric membranes and optimizing their performance.

Problems solved by technology

As a standard battery operates, various chemical components of the electrodes are depleted over time.

Until recently, however, no molecular-level understanding was available for electro-osmosis.

During operation of the fuel cell, protonic current within the membrane drags water (e.g., ‘electro-osmotic drag’) from the anode to the cathode, which reduces the efficiency of the fuel cell by hindering the reduction reaction at the cathode (e.g., ‘cathode flooding’).

This, in turn, generally requires the utilization of relatively expensive water management techniques typically involving capture or return of water to the anode side of the DMFC.

Accordingly, despite the efforts of the prior art, one problem warranting resolution is the characterization of the increased electro-osmotic drag of water by protons in membranes used in the manufacture of PEMFC's.

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