Membranes fuel cell tests

Our fuel cell test fixture was made from a commercially available membrane filter holder. We spot-welded electrode studs to the two halves of the fixture case, one for the hydrogen side and one for the oxygen (air) side. 

The stability and durability of Pt alloys, especially those involving a >d transition metal, are the major hurdles preventing them from commercial fuel cell applications. "" The transition metals in these alloys are not thermodynamically stable and may leach out in the acidic PEM fuel cell environment. Transition metal atoms at the surface of the alloy particles leach out faster than those under the surface of Pt atom layers." The metal cations of the leaching products can replace the protons of ionomers in the membrane and lead to reduced ionic conductivity, which in turn increases the resistance loss and activation overpotential loss. Gasteiger et al. showed that preleached Pt alloys displayed improved chemical stability and reduced ORR overpotential loss (in the mass transport region), but their long-term stability has not been demonstrated. " These alloys experienced rapid activity loss after a few hundred hours of fuel cell tests, which was attributed to changes in their surface composition and structure." ... 

Whether humidification of PBI in fuel cells is necessary remains an open question. Short-term fuel cell tests yielded no or small performance losses when dry fuels were used or humidification was reduced [167,168]. However, membrane conductivity does depend on the water activity as can be seen in Figure 27.71 taken from a presentation by Savinell, the conductivity of PBI (3 H3PO4/PBI repeat unit and 6.3 H3PO4/PBI repeat unit) depends considerably on relative humidity [169]. However, Celanese (PEMEAS) in their pubhcations state that no humidification is required for their PBI systems. 

A. Brinner et al. (1998). DLR s membrane Fuel Cell Test Facility for Stationary and Mobile XApplication, Proc. 12Th WHEC, Bolcich and T. N. Veziroglu, Buenos Aires, p. 1597. 

B. Sundholm, G. Sundholm, F. Jacobsson, P. Confocal raman spectroscopic investigations of fuel cell tested sulfonated styrene grafted poly (vinylidene fluoride) membranes. J. Electrochem. Soc. 2002, 149 (2), A206-A211. 

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. 

Fuel cell tests of membranes based on sulfonated PES showed [7] a cell voltage of 550 mV at a current density of 700 mAcm (atmospheric pressure, humidified gases, 70 C). No significant loss of membrane performance was observed after long-term operation (1000 h) under fuel cell conditions. 

In the preparation of MEA, there are two options. One is to coat the CL onto the DM such as carbon paper, or carbon cloth, the other is to coat the CL onto the PEM, as shown in Figure 3.17. The CL coated on the diffusion medium is called Catalyst-coated Diffusion Medium (CDM), and the CL coated on the membrane is called Catalyst Coated Membrane (CCM). Using a hot-press process, by sandwiching PEM between two CDMs, or CCM between two DMs, an MEA can be fabricated for fuel cell testing. 

Fuel cell performance was investigated for PAE-BP membranes it showed better performance than for Nafion 115 in initial fuel cell tests at 120 °C with no optimization. The maximum power density and current density at 0.5 V of PAE-BP were 30% and 43% higher, respectively, than those of Nafion 115 (Fig. 2.20). 

Griinert, W. (2011) A spectroscopic proton-exchange membrane fuel cell test setup allowing fluorescence X-ray absorption spectroscopy measurements during state-of-the-art cell tests. Rev. 

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