Proton exchange membrane fuel cells electron conductivity

M.C. Lefebvre, Z. Qi, and P.G. Pickup, Electronically conducting proton exchange polymers as catalyst supports for proton exchange membrane fuel cells, J. Electrochem. Soc., 146, 2054-2058 999). 

In the Proton-Exchange Membrane Fuel Cell (or Polymer-Electrolyte Membrane Fuel Cell) the electrolyte consists of an acidic polymeric membrane that conducts protons but repels electrons, which have to travel through the outer circuit providing the electric work. A common electrolyte material is Nafion from DuPont , which consists of a fluoro-carbon... 

Polymer Electrolyte Membranes or Proton Exchange Membrane Fuel Cells (PEMFCs). PEMFGs use a proton conductive polymer membrane as an electrolyte. At the anode, the hydrogen separates into protons and electrons, and only the protons pass through the proton exchange membrane. The excess of electrons on the anode creates a voltage difference that can work across an exterior load. At the cathode, electrons and protons are consumed and water is formed. 

Figure 18.4. Transport of Pt from a smaller particle to a larger particle by coupled transport of Pt throu the liquid and/or ionomer and the transport of electrons through the carbon support when the Pt particles are in contact with electronically conducting carbon [32]. (Reproduced by permission of ECS— The Electrochemical Society, from Virkar AV, Zhou Y. Mechanism of catalyst degradation in proton exchange membrane fuel cells.)...

Du CY, Shi PF, Cheng XQ, Yin GP. Effective protonic and electronic conductivity of the catalyst layers in proton exchange membrane fuel cells. Electrochem Commun 2004 6 435-40. 

In PEFC, the membrane, together with the electrodes, forms the basic electrochemical unit, the membrane electrode assembly (MEA). Whereas the first and foremost function of the electrolyte membrane is the transport of protons from anode to cathode, the electrodes host the electrochemical reactions within the catalyst layer and provide electronic conductivity on the one hand, and pathways for reactant supply to and removal of products from the catalyst on the other hand. The components of the MEA need to be chemically stable for several thousands of hoius in the fuel cell imder the prevailing operating and transient conditions. PEFC electrodes are wet-proofed fibrous carbon sheet materials of a few 100 p,m thickness. The fimctionahty of the proton-exchange membrane extends to requirements of mechaiucal stabihty to ensure effective separation of anode and cathode, also under aggravated... 

The proton exchange membrane (PEM) is a key component of PEM fuel cells. It separates the anodic and cathodic compartments and at the same time acts as a proton conductor by transporting protons generated at the anode to the cathode. The protons in the membrane are the main charge carriers. Hence, the conductivity induced by this proton transport is called proton conductivity. Because protons can get transported in two directions, both across and through the membrane, there are two types of conductivity in-plane and through-plane conductivities. The two types are theoretically different unless the membrane is isotopic in these two dimensions. In reality, the PEM is not an absolute electronic isolator. The electronic conductivity, normally much smaller than the... 

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