Patent Publication Number: US 7629071 B2
Title: Gas diffusion electrode and method of making the same
Filing Date: December 20, 2004
Priority Date: September 29, 2004
Inventor(s): Han Liu, Robert C. McDonald, Thomas J. McCallum, Anthony B. LaConti, John Forchione, Jeanette O'Hara, Joerg Roth,
Original Assignee / Applicant(s): Giner Electrochemical Systems, Llc
Link to Patent: US7629071B2Summary:
The present invention discloses a gas diffusion electrode comprising a mechanically stable, electrically-conductive, gas porous support layer; an electrically-conductive, chemically-inert first cushioning layer positioned on top of the support layer; a second cushioning layer positioned on top of the first cushioning layer, and a catalyst layer positioned on top of the second cushioning layer. In this publication, it has been disclosed that an experiment was conducted to evaluate the effect of the cushioning layer of the present invention in preventing the supporting layer from puncturing a solid polymer electrolyte membrane. In the said experiment, the membrane electrode assembly of the present invention was sandwiched between two sets of gold-plated copper current collectors and a pair of thin GYLON® PTFE (Garlock Sealing Technologies, LLC, Palmyra, N.Y.) films, to form the set-up. The aforementioned set-up was then compressed using a hydraulic press, wherein a force was applied to the set-up, increasing stepwise from 100 to 2000 psi in 100-psi increments. For each step, the force was kept steady for 30 seconds before being increased to the next step. DC resistance between current collectors was continuously monitored throughout the test. If a puncture occurred, the resistance between the two current collectors dropped from >10 k? to 50-200 ?. The test was then performed again, with the membrane electrode assembly of the present invention being replaced first by a pair of Etek Elat® electrodes (Etek, Inc., Somerset, N.J.) and then by a pair of Johnson Matthey Plain HO60 electrodes (Johnson Matthey Plc, London, UK). The results revealed that the cushioning layer of the present invention substantially reduced the number of punctures of the membrane by the supporting layer of the electrode. In this experiment, prior to the testing, the hydraulic press was calibrated using pressure-sensitive color-changing Fujifilm Prescale® to ensure balanced compression on the membrane.
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