Direct methanol fuel cell cathode impedance

For EIS measurements of a direct methanol fuel cell (DMFC), the anode is supplied with an aqueous solution of methanol at a concentration such as 1 M and using controlled flow rates. The cathode is operated on either air, oxygen, or hydrogen, with controlled flow rate and pressure [43], In order to measure the anode EIS, the DMFC is fed with hydrogen gas instead of air or oxygen, to eliminate the contributions of the cathode. This cathode is normally denoted as a dynamic hydrogen electrode (DHE). Thus, the anode impedance spectra between the anode and the DHE can be obtained in a complete fuel cell. 

Figure 5.39. Nyquist plots of a typical DMFC cathode impedance spectrum ( ), operation on air ( ), operation on oxygen [43], (Reprinted from Journal of Power Sources, 75, Muller JT, Urban PM. Characterization of direct methanol fuel cells by AC impedance spectroscopy, 139M3, 1998, with permission from Elsevier and the authors.)...

Figure 6.68. Impedance spectra of a DMFC cathode. Experimental conditions 75°C, air stoichiometric ratio 10, 69 mA cnT2, 0.879 V, and frequency range 10 kHz-0.1 Hz [57], (Reproduced by permission of ECS—The Electrochemical Society, from Piela P, Fields R, Zelenay P. Electrochemical impedance spectroscopy for direct methanol fuel cell diagnostics.)...

Furukawa K, Okajima K, Sudoh M (2005) Structural control and impedance analysis of cathode for direct methanol fuel cell. J Power Sources 139(1-2) 9-14... 

The construction of a cell permitting both FTIR measurements and electrochemical impedance measurements at buried polymer/metal interfaces has been described [266]. Ingress of water and electrolyte, oxidation (corrosion) of the aluminum metal layer, swelling of the polymer and delamination of the polymer were observed. A cell suitable for ATR measurements up to 80°C has been described [267]. The combination of a cell for ATR measurements with DBMS (see Sect. 5.8.1) has been developed [268]. It permits simultaneous detection of stable adsorbed species and relatively stable adsorbed reaction intermediates (via FTIR spectroscopy), quantitative determination of volatile species with DBMS and elucidation of overall reaction kinetics. An arrangement with a gas-fed electrode attached to the ATR element and operated at T = 60°C has been reported [269]. In this study, the establishment of mixed potentials at an oxygen consuming direct methanol fuel cell in the presence of methanol at the cathode was investigated. With infrared spec-... 

Diard, J.-R, Glandut, N., Landaud, R, Gorrec, B. Le, and MonteUa, C. 2003. A method for determining anode and cathode impedances of a direct methanol fuel cell running on a load. Electrochim. Acta. 48, 555-562. 

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