Proton-conducting polymer membran

PEM Proton-exchange-membrane fuel cell (Polymer-electrolyte-membrane fuel cell) Proton- conducting polymer membrane (e.g., Nafion ) H+ (proton) 50-80 mW (Laptop) 50 kW (Ballard) modular up to 200 kW 25-=45% Immediate Road vehicles, stationary electricity generation, heat and electricity co-generation, submarines, space travel... 

Direct-methanol fuel cell Proton- conducting polymer membrane H+ (proton) 80-100... 

This chapter gives an overview of the state of affairs in physical theory and molecular modeling of materials for PEECs. The scope encompasses systems suitable for operation at T < 100°C that contain aqueous-based, proton-conducting polymer membranes and catalyst layers based on nanoparticles of Pt. 

Andreaus B, Scherer GG (2004) Proton-conducting polymer membranes in fuel cells— humidification aspects. Sohd State Ionics 168(3—4) 311—20... 

Using proton-conducting ceramics as an electrolyte for a steam electrolyzer involves the same reactions as for a low-temperature proton-conducting polymer membrane ... 

Kreuer, K.D., On the development of proton conducting polymer membranes for hydrogen and methanol fuel cells, J. Membr. Sci., 185, 29, 2001. 

FIGURE 27.20 Structure of Nation. The characteristic value of proton-conducting polymer membranes is the EW, which is defined as the weight of polymer that will neutralize one equivalent of base, and is inversely proportional to the lEC. The values n, m, n can he varied to produce materials with different equivalent weights. 

S.P. Nunes, B. Ruffmann, E. Rikowski, S. Vetter, and K. Richau. Inorganic modification of proton conductive polymer membranes for direct methanol fuel cells. Journal of Membrane Science 203, 215-225 2002. 

The state-of-the-art proton-conducting polymer membranes use water networks to conduct protons. Thus, they require sufficient membrane hydration for functioning, which limits operation of the present-day cells to temperatures lower... 

In proton exchange membrane fuel cells, perhaps the most divulgate type of fuel cells, a proton-conducting polymer membrane acts as the electrolyte separating the anode and cathode sides. Porous anaodic alumina (Bocchetta et al., 2007) and mesoporous anastase ceramic membranes have been recently introduced in this field (Mioc et al., 1997 Colomer and Anderson, 2001 Colomer, 2006). 

Proton exchange membrane fuel cell (PEMFC) Proton conductive polymer membrane H2 O2 (in air) 60-90 Transportation vehicles, stationary power plants, cogeneration plants, portable power supplies... 

The proton-conducting polymer membranes fulfill a number of functimis, which clearly influences the choice of materials ... 

FIGURE 21.17 Schematic representation of the microstructures of (a) Nafion and (b) an s-PEEK illustrating the less pronounced hydro-phobic/hydrophilic separation of the latter compared to the forma-. (Reprinted from J. Membr. Sci., On the development of proton conducting polymer membranes for hydrogen and methanol fuel cells, 185, 2001, 29, Kreuer, K.D. et al. With permission from Elsevier Kreuer, K.D., J. Membr. ScL, 185,29,2001.)... 

While a munber of alternative polymer membranes have been developed. Nation is still considered the benchmark of proton conducting polymer membranes, and has the largest body of research hterature devoted to its study. Alternative polymer membranes are almost invariably compared to Nation . Nation is a free radical initiated copolymer consisting of crystaUiz-able, hydrophobic tetrafluoroethylene and a perfluorinated vinyl ether terminated by perfluorosulfonic acid. Nation 117 possesses an equivalent weight of 1100 (EW = mass of dry ionized polymer (g) in the protonic acid form that would neutralize one equivalent of base). Thus, there are 13 perfluoro-methylene groups (-CF2-) ( = 6.5) between pendent ionic side chains. 

Many national and international research programs have recently initiated work on proton-conducting polymer membranes for fuel cell applications. The contributions in these two volumes aim to summarize some major efforts, without claiming to be exhaustive. 

A Proton-Conducting Polymer Membrane as Solid Electrolyte -Function and Required Properties... 

J. Won, Y. S. Kang, Proton-conducting polymer membranes for direct methanol fuel cells. Macromolecular Symposium 204 (2003) 79-91. 

Nunes, S., Ruffinann, B., Rikowski, E., Vetter, S. and Richau, K. 2002. Inorganic modification of proton conductive polymer membrane for direct methanol fuel cells. 

Gubler L, Kramer D, Belack J, Unsel O, Schmidt T J and Scherer G G (2008), A proton conducting polymer membrane as solid electrolyte - function and required properties , Adv Polym Sci, 215,1-14. 

PEMFGs use a proton-conducting polymer membrane as electrolyte. The membrane is squeezed between two porous electrodes [catalyst layers (CLs)]. The electrodes consist of a network of carbon-supported catalyst for the electron transport (soHd matrix), partly filled with ionomer for the proton transport. This network, together with the reactants, forms a three-phase boundary where the reaction takes place. The unit of anode catalyst layer (ACL), membrane, and cathode catalyst layer (CCL) is called the membrane-electrode assembly (MEA). The MEA is sandwiched between porous, electrically conductive GDLs, typically made of carbon doth or carbon paper. The GDL provides a good lateral delivery of the reactants to the CL and removal of products towards the channel of the flow plates, which form the outer layers of a single cell. Single cells are connected in series to form a fuel-cell stack. The anode flow plate with structured channels is on one side and the cathode flow plate with structured channels is on the other side. This so-called bipolar plate... 

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. 

Alexei R. Khokhlov s main research interests are polymer science, statistical physics of macromolecules, physical chemistry of polyelectrolytes and ionomers, microphase separation in polymer systems, polymer liquid crystals, polyelectrolyte responsive gels, topological restrictions in polymer systems, dynamics of concentrated polymer solutions and melts, coil-globule transitions, associating polymers, computer simulation of polymer systems, biomimetic polymers, and proton-conducting polymer membranes. 

---