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PEM URFC

A good catalyst for the bifunctional hydrogen electrode is platinum, and for the bifunctional oxygen electrode the most promising catalyst material is a mixture of platinum and iridium oxide. The use of thin catalyst layers in the electrode helps to minimize mass transport and ohmic limitations [57]. In addition to the catalyst composition, the ionomer content, the catalyst layer thickness, and the PTFE content are varied and the influence of these variations on performance has been described [58-63]. The highest efficiency can be achieved using a catalyst with a high amount of platinum and a low amount of iridium [58, 60]. [Pg.231]

Another approach is the investigation of catalyst deposition. It is possible to apply different catalysts to the active area of the cell in single layers or as a mixture or in segmented areas [64]. A new technique is the chemical deposition of platinum nanoparticles on iridium oxide for oxygen electrodes [65]. [Pg.231]

Current (Acm ) Voltage Ely (V) Voltage FC (V) Efficiency Ely Efficiency FC Efficiency round trip [Pg.232]

The scale-up from laboratory cells to a 10-ceU URFC stack with 250 cm per cell was demonstrated by Kato et al. [66]. In this stack, the performance is as high as in the laboratory cells and at the same level as that of cells optimized for electrolysis or FC operation. The manufacture and design of electrodes (Pt Ir) and the test of a seven-cell URFC stack with 256 cm active area for each cell was described by Grigoriev and co-workers [67, 68]. In this stack, the maximum power in electrolysis mode is 1.5 kW and the efficiency is 72% at 0.5 A cm . An efficiency of 44% can be achieved in FC operation. [Pg.232]

Some values for the voltage and efficiency with Pt Ir 85 15 for the electrolyzer and FC modes are given as an example in Table 8.9. [Pg.232]


In the 1990s, the development of PEM URFCs started [18]. The advantages of the PEM compared with the AFC are its simplicity and safe operation without a liquid electrolyte. At the same time, RFCs were tested for the seasonal storage of regeneratively produced electricity in various test plants [19, 20). In 2003, an RFC system powered the autonomous unmanned solar aircraft Helios [21, pp. 175-176). [Pg.223]

Optimization of Ptir electrocatalyst for PEM URFC. Int. J. Hydrogen Energy, 30, 1345-1350. [Pg.241]

PEM fuel cells, with appropriate catalysts (e.g., Pt for the H2 electrode and Pt—Ir for the O2 electrode), can be operated as unitized (reversible) regenerative fuel cells (URFCs) (Figure 15.22), i.e., they can be used for storing electricity produced by renewable, but intermittent, resources such as solar cells and windmills, much like a... [Pg.467]

If an RFC system has a separate FC and electrolyzer, it is possible to choose different materials for the electrolyzer and for the FC electrodes. The materials can be adapted in terms of ideal performance and high durabihty. If a URFC system is considered, the electrodes have to be suitable for both hydrogen consumption and evolution or oxygen consumption and evolution. This bifunctional operation subjects the electrodes to considerable stress and can reduce their performance and durability. In addition to the type of operation (conventional or bifunctional), the composition of the electrodes is greatly dependent on the electrolytes used. In the following subsections, the different electrolytes (alkaline, PEM, SOE) are described and also suitable electrodes for each type of operation. [Pg.226]


See other pages where PEM URFC is mentioned: [Pg.222]    [Pg.231]    [Pg.215]    [Pg.222]    [Pg.231]    [Pg.215]    [Pg.468]    [Pg.385]   


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