Membrane electrode assembly testing

The cell resistance during fuel cell operation was measured for all membrane electrode assemblies tested. it was observed that when... 

This presentation reports some studies on the materials and catalysis for solid oxide fuel cell (SOFC) in the author s laboratory and tries to offer some thoughts on related problems. The basic materials of SOFC are cathode, electrolyte, and anode materials, which are composed to form the membrane-electrode assembly, which then forms the unit cell for test. The cathode material is most important in the sense that most polarization is within the cathode layer. The electrolyte membrane should be as thin as possible and also posses as high an oxygen-ion conductivity as possible. The anode material should be able to deal with the carbon deposition problem especially when methane is used as the fuel. 

Xie J, Wood DL, More KL, Atanassov P, Borup RL. 2005a. Microstructural changes of membrane electrode assemblies during PEFC durability testing at high humidity conditions. J Electrochem Soc 152 A1011-A1020. 

The membrane conductivity was measured in HCl(aq) solutions of different concentrations and in 2 M HC1 + 0.2 M CuCl solution to model the catholyte and anolyte solutions in the electrolyser. All membranes were equilibrated in the same solutions for 20 hours before starting the measurements. Detailed characterisation data for a number of commercial anion exchange membranes are published elsewhere (Gong, 2009). The AHA membrane, which demonstrated the highest conductivity in HC1 (12.61 mS/cm) compared to other membranes with similar IEC and water uptake, was selected to prepare a membrane electrode assembly (MEA) and carry out electrolysis tests with this MEA. The ACM membrane with lower conductivity values was also chosen for the electrolysis tests due to its proton blocking properties and high Cl- selectivity. 

The main advantage of the GDE technique is that the electrode structure is similar to the fuel cell membrane electrode assembly. Therefore, the obtained results may be closer to those tested in a real fuel cell. However, the GDE technique is still rarely used in fuel cell studies due to the complicated design of the electrochemical cell, as well as the instability and poor-repeatability of the results. Furthermore, prior to the electrochemical measurements, the GDE needs to... 

Long-Term Testing of Membrane/Electrode Assemblies. 241... 

Test the performance of ion-exchange membranes in a membrane electrode assembly (MEA). 

Cooperatively fabricate and test membrane electrode assembly (MEAs) using the most promising membranes. This is to be done in partnership with an external company specializing in fuel cells. 

In experiments performed with different membrane-electrode-assembly fabrication techniques, and containing a PSSA-PVOF membrane with different properties than the ones previously discussed, the overall performance was similar to that previously obtained, as shown in Fig. 1.80. However the MEA tested displayed distinctly different behavior in contrast to samples previously discussed in that it showed less sensitivity to oxygen flow rate, as illustrated in Fig. 1.81. This behavior can partly be rationalized by increased methanol crossover rates observed for this MEA, which can contribute to aid in proper hydration of the cathode. However, since the increase in methanol crossover compared with the earlier samples is not dramatic ( 25% greater), other factors such as the concentration of sulfonic acid groups present at the membrane surface available for participation in the interfacial reaction zone as well as the concentration of perfluorocarbon binder contribute to produce conditions less sensitive to water management problems. 

The PSSA-PVDF membranes were successfully fabricated into larger membrane electrode assemblies and tested in 2 x 2 (25 cm electrode area)... 

Further improvements to membrane and membrane-electrode-assembly fabrication techniques resulted in cells with superior electrical performance to those previously tested, as shown in Fig. 1.100. In attempt to improve the... 

J. Xie, D. L. Wood III, K. L. More, P. Atanassov, and R. L. Borup, Micro-structural Changes of Membrane Electrode Assemblies During PEFC Durability Testing at High Humidity Conditions, /. Electrochem. Soc., 12, AlOl 1 (2005). 

We describe here an experimental approach to design PEM fuel cell reactors where the complexities of macroscopic design parameters are chosen to obtain data in the least ambiguous form, not to optimize the overall power output. The fuel cell designs presented here can be used with virtually any membrane-electrode assembly these are fuel cell test stations. The fuel cell reactors described here can be thought of as building blocks for more complex fuel cells designs. 

The development of membranes for fuel cells is a highly complex task. The primary functionalities, (i) transport of protons and (ii) separation of reactants and electrons, have to be provided and sustained for the required operating time. Optimization of the composition and structure of the material to maximize conductivity and mechanical robustness involves careful balancing of synthesis and process parameters. The ultimate membrane qualification test is the fuel cell experiment. It is evident that the membrane is not a stand-alone component, but is combined with the electrodes in the membrane electrode assembly (MEA). Interfacial properties, influence on anode and cathode electrocatalysis, and water management are the key aspects to be considered and optimized in this ensemble. 

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