Membrane electrode assembly ohmic resistance

In a H2/02 (air) fuel cell, in general, the spectra, i.e., the Nyquist plots obtained by EIS measurements, very often have three features, which are denoted as high-frequency, medium-frequency, and low-frequency. The high-frequency region of an impedance spectrum is associated with the internal ohmic resistance and the contact capacitance in the granular electrode structure of the membrane electrode assemblies, whereas the medium- and low-frequency regions represent the charge-... 

Aquivion E87-12S short-side chain perfluorosulfonic acid (SSC-PFSA) membrane with equivalent weight (EW) of 870 g eq and 120 pm thickness produced by Solvay Specialty Polymers was tested in a polymer electrolyte membrane water electrolyser (PEMWE) and compared to a benchmark Nation N115 membrane (EW 1100 g eq ) of similar thickness [27]. Both membranes were tested in conjunction with in-house prepared unsupported Ir02 anode and carbon-supported Pt cathode electrocatalyst. The electrocatalysts consisted of nanosized Ir02 and Pt particles (particle size 2-4 nm). The electrochemical tests showed better water splitting performance for the Aquivion membrane and ionomer-based membrane-electrode assembly (MEA) as compared to Nafion (Fig. 2.21). Lower ohmic drop constraints and smaller polarization resistance were observed for the electrocatalyst-Aquivion ionomer interface indicating a better catalyst-electrolyte interface. A current density of 3.2 A cm for water... 

The practical problem encountered in PEMFC is keeping the membrane wet under operating conditions. The balance of water with its transport determines the water content in the cell during the reactive mode of operation. Water-transport processes are a function of the current and the characteristics of both the membrane and the electrodes (Mosdale, 1996 Motupally, 2000). The temperature of operation ofthe cell has a significant influence on its performance. The performance of the PEMFC increases with temperature until 90°C, which reflects a lowering of the internal resistance of the cell. This decrease is due largely to the decrease in ohmic resistance of the electrolyte. Mass transport, which is limited (i) by diffusion of reactants through the PEMFC assembly to the active Pt sites. 

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