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With this approach, PEM fuel cells have been shown to be capable of cold start processes from −20°C. [8] 3. Light mass and high power density (transport applications) PEM fuel cells have been shown to be capable of high power densities up to 39.7 kW/kg, compared to 2.5 kW/kg for solid oxide fuel cells. [9]
When determining the electrical efficiency of PEM electrolysis, the HHV can be used. [17] This is because the catalyst layer interacts with water as steam. As the process operates at 80 °C for PEM electrolysers the waste heat can be redirected through the system to create the steam, resulting in a higher overall electrical efficiency.
Whereas the common PEM fuel cell, also called Low Temperature Proton Exchange Membrane fuel cell (LT-PEM), must usually be operated with hydrogen with high purity of more than 99.9 % the HT-PEM fuel cell is less sensitive to impurities and thus is typically operated with reformate gas with hydrogen concentration of about 50 to 75 %.
The PEM is sandwiched between two electrodes which have the catalyst embedded in them. The electrodes are electrically insulated from each other by the PEM. These two electrodes make up the anode and cathode respectively. The PEM is typically a fluoropolymer (PFSA) proton permeable electrical insulator barrier. Hydrocarbon variants are ...
A proton-exchange membrane, or polymer-electrolyte membrane (PEM), is a semipermeable membrane generally made from ionomers and designed to conduct protons while acting as an electronic insulator and reactant barrier, e.g. to oxygen and hydrogen gas. [1]
Methanol cross-over and/or its effects can be alleviated by (a) developing alternative membranes (e.g. [6] [7]), (b) improving the electro-oxidation process in the catalyst layer and improving the structure of the catalyst and gas diffusion layers (e.g. [8]), and (c) optimizing the design of the flow field and the membrane electrode assembly ...
It is a superacid catalyst. The combination of fluorinated backbone, sulfonic acid groups, and the stabilizing effect of the polymer matrix make Nafion a very strong acid, with pK a ~ -6. [8] In this respect Nafion resembles the trifluoromethanesulfonic acid, CF 3 SO 3 H, although Nafion is a weaker acid by at least three orders of magnitude.
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