Proton exchange membrane direct hydrogen

Numerous functional electrochemical devices based on LbL films have been fabricated toward a variety of applications. The use of LbL films in such devices relies on the effective ion transport, that is, ionic conductivity, within the multilayered structure, which can be in both wet and dry states depending on the final application. For example, proton-exchange membranes in hydrogen and direct methanol fuel cells require a humid environment for ionic conductivity, while in lithium ion batteries, ion transport takes place in a dry environment. 

Ford Motor Company. (1997). Direct Ilydrogcn-Fuclcd Proton Exchange Membrane Fuel Cell System for Transportation Applications Hydrogen Vehicle... 

Ferrel, J., Kotar, A. and Stern, S. (1996). Direct Hydrogen Fuelled Proton Exchange Membrane (PEM) Fuel Cell System for Transportation Applications. Final report, Section 3 Hydrogen Infrastructure Report. Prepared for the Ford Motor Company and the Department of Energy. 

Ford Motor Co., Direct-hydrogen-fueled proton-exchange membrane fuel ceU system for transportation applications hydrogen vehicle safety report, D.T. Inc., ed., Arlington,VA (1997). 

Polyphosphazene-based PEMs are potentially attractive materials for both hydrogen/air and direct methanol fuel cells because of their reported chemical and thermal stability and due to the ease of chemically attaching various side chains for ion exchange sites and polymer cross-linking onto the — P=N— polymer backbone. Polyphosphazenes were explored originally for use as elastomers and later as solvent-free solid polymer electrolytes in lithium batteries, and subsequently for proton exchange membranes. 

DMFCs and direct ethanol fuel cells (DEFCs) are based on the proton exchange membrane fuel cell (PEM FC), where hydrogen is replaced by the alcohol, so that both the principles of the PEMFC and the direct alcohol fuel cell (DAFC), in which the alcohol reacts directly at the fuel cell anode without any reforming process, will be discussed in this chapter. Then, because of the low operating temperatures of these fuel cells working in an acidic environment (due to the protonic membrane), the activation of the alcohol oxidation by convenient catalysts (usually containing platinum) is still a severe problem, which will be discussed in the context of electrocatalysis. One way to overcome this problem is to use an alkaline membrane (conducting, e.g., by the hydroxyl anion, OH ), in which medium the kinetics of the electrochemical reactions involved are faster than in an acidic medium, and then to develop the solid alkaline membrane fuel cell (SAMFC). 

In addition to hydrogen as a fuel, methanol or ethanol can be directly converted into electricity in a DAFC, the great progress of which resulted from the use of a proton exchange membrane acting both as an electrolyte (instead of the aqueous electrolytes previously used) and as a separator preventing the mixing of fuel and oxidant. A DAFC can work at moderate temperatures (30-50 °C) for portable applications, but now the tendency is to look for new membranes that are less permeable to alcohol and... 

Boettner, D., Moran, M. (2004). Proton exchange membrane (PEM) fuel cell-powered vehicle performance using direct-hydrogen fueling and on-board methanol re-... 

Design, build and demonstrate a fully integrated, 50-kilowatt electric (kWe) catalytic autothermal fuel processor system. The fuel processor will produce a hydrogen-rich gas for direct use in proton exchange membrane (PEM) fuel cell systems for vehicle applications. 

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