Composite membranes for fuel-cell applications

• Published in: AIChE journal 1992-01, Vol.38 (1), p.93-100
• Main Authors: Verbrugge, Mark W., Hill, Robert F., Schneider, Eric W.
• Format: Article
• Language: English
• Subjects: 30 DIRECT ENERGY CONVERSION; 300505 > Fuel Cells-- Electrochemistry, Mass Transfer & Thermodynamics; 400105 > Separation Procedures; 400201 > Chemical & Physicochemical Properties; Applied sciences; CHEMICAL COMPOSITION; COMPOSITE MATERIALS; DIRECT ENERGY CONVERTERS; ELECTROCHEMICAL CELLS; ELECTROLYTES; ELEMENTS; Exact sciences and technology; Exchange resins and membranes; Forms of application and semi-finished materials; FUEL CELLS; HYDROGEN; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MATERIALS; MATERIALS TESTING; MEMBRANES; NONMETALS; OXYGEN; Polymer industry, paints, wood; POLYMERS; SEPARATION PROCESSES; SOLID ELECTROLYTE FUEL CELLS; Technology of polymers; TESTING 300503 > Fuel Cells-- Materials, Components, & Auxiliaries
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.690380110

One of the major obstacles to overcome for the realization of economical hydrogen‐oxygen, polymer‐electrolyte fuel cells is the high capital cost of the inert perfluorosulfonic acid (PSA) membranes, which provide a pathway for ionic transport between the cell electrodes. It has recently been shown that composite polymer membranes can be synthesized by depositing PSA polymers onto porous poly(tetrafluoroethyene) (PTFE) substrates. The resulting membranes are mechanically durable and quite thin relative to traditional PSA membranes; we expect the composite membranes to be of low resistance and cost. In this experimental study, we examine the composite membrane properties as a function of the membrane composition. Our results allow us to form a conceptual model to explain both the equilibrium and transport characteristics of these materials. For high PSA contents, the membrane behavior is similar to that of the PSA polymer; the water permeability, however, is reduced significantly. For intermediate PSA contents, the membranes have a high porosity and match the thickness of the PTFE substrate (≈50 μm); membranes of this composition range are potentially useful candidates for fuel cells because of their high resistance to water transport and reduced ionic resistance. Composite membranes of very low PSA content demonstrate characteristics similar to the hydrophobic PTFE substrate and are not of interest for fuel cells.