Polymer/polymeric electrolyte fuel cell

Proton exchange membranes (PEM) fuel cells (or polymer electrolyte fuel cells - PEFCs), with H -conducting polymeric membranes, transports hydrogen (fuel) cations, generated at the anode, to an ambient air exposed cathode, where they are electro-oxidised to water at low temperatures. 

The idea of using an ion-conductive polymeric membrane as a gas-electron barrier in a fuel cell was first conceived by William T. Grubb, Jr. (General Electric Company) in 1955. - In his classic patent, Grubb described the use of Amber-plex C-1, a cation exchange polymer membrane from Rohm and Haas, to build a prototype H2-air PEM fuel cell (known in those days as a solid-polymer electrolyte fuel cell). Today, the most widely used membrane electrolyte is DuPont s Nation... 

The development of new polymeric materials for polymer electrolyte fuel cell is one of the most active research areas, aiming at the new energy sources for electric cars and other devices. The mainstream of the material research for fuel cell is perfluoroalkyl sulfonic acid membranes such as Nafion, Acipex, and Flemion. The most well-known one is Nafion of Du Pont, which is derived from copolymers of tetrafluoro-ethylene and perfluorovinyl ether terminated by a sulfonic acid group.Protons, when dissociated from the sulfonic acid groups in aqueous environment, become mobile and the membrane becomes a proton conducting electrolyte membrane. 

Proton exchange membrane fuel cell or Polymer eleetrolyte membrane fuel cell or Polymer electrolyte fuel eell or Polymeric fuel eell or Polymerie membrane fuel cell or Direct methanol fuel cell or DMFC... 

Polymer electrolyte fuel cells (PEFCs) have attracted much interest as one of the most promising nonpolluting power sources capable of producing electrical energy with high thermodynamic efficiencies. The key element of PEFCs is a polymer electrolyte membrane (PEM) that serves as proton conductor and gas separator [1, 2, 3,4], The membrane commonly employed in most PEFC developments is based on Nafion, which represents a family of comb-shaped ionomers with a perfiuorinated polymeric backbone and short pendant (side) chains having sulfonic acid end groups... 

The aforementioned polymeric electrolytes have been effectively used in polymer electrolyte fuel cells operating up to In order to study the single cell performance and apart from the high ionic conductivity of the membrane, several parameters residing the MEA constmction must be taken into account in order to have optimum performance of the cell. Some of these parameters are the amount of the catalyst the ionomer-binder used at the electrodes and its percentage, electrode surface and the preparation method, pressure and the temperature of the MEA assembling and design and constmction parameters of the cell. ... 

Fuel cells have been known as power sources since the times of Sir William R. Grove and Christian F. Schonbein around 1840. Since then huge leaps in technology occurred leading to different kinds of fuel cells classified upon the physicochemical properties of their electrolyte and their operating conditions. Polymer electrolyte fuel cells (PEFC) utilize the ionic conductivity, the gas separation ability, and the electronic insulation provided by polymeric materials. These properties led to solutions of various engineering problems in liquid electrolyte fuel cells (e.g., phosphoric acid FC, alkaline FC). 

Hydrocarbon Membranes for Polymer Electrolyte Fuel Cells, Fig, 1 BPSH/BPS block copolymer (A andB are the numbers of repeat unit of hydrophilic and hydrophobic blocks, respectively, n is the degree of polymerization)... 

Ogumi, Z. Uchimoto, Y. Takehara, Z. Kanamoii, Y. (1989). Preparation of Ultra-Thin Solid-State Lithium Batteries Utilizing a Plasma-Polymerized Solid Polymer Electrolyte. /, Chem. Soc., Chem. Commun., Vol. 21, pp. 1673-1674 Ohnishi, R. Katayama, M. Takanabe, K Kubota, J. Domen, K (2010). Niobium-Based Catalysts Prepared by Reactive Radio-Frequency Magnetron Spnitteiing and Arc Plasma Methods as Non-Noble Metal Cathode Catalysts for Polymer Electrolyte Fuel Cells. Electrochim. Acta, Vol. 55, pp. 5393-5400 Papadopoulos, N.D. Karayiarmi, H.S. Tsakiridis, P.E. Perraki, M. Hiistoforou, E. (2010). 

Sadhir, R.K Schoch, K.F. (1996). Plasma-Polymerized Carbon Disulfide Thin-Film Rechargeable Batteries. Chem. Mater., Vol. 8, pp. 1281-1286 Saha, M.S. Gulla, A.F. Allen, R.J. Mukerjee, S. (2006). High Performance Polymer Electrolyte Fuel Cells with Ultra-Low Pt Loading Electrodes Prepared by Dual Ion-Beam Assisted Deposition. Electrochim. Acta, Vol. 51, pp. 4680-4692 Schieda, M. Roualdes, S. Durand, J. Martinent, A. Marsacq, D. (2006). Plasma-Polymerized Thin Films as New Membranes for Miniature Solid Alkaline Fuel Cells. Desalination, Vol. 199, pp. 286-288... 

By the time the next overview of electrical properties of polymers was published (Blythe 1979), besides a detailed treatment of dielectric properties it included a chapter on conduction, both ionic and electronic. To take ionic conduction first, ion-exchange membranes as separation tools for electrolytes go back a long way historically, to the beginning of the twentieth century a polymeric membrane semipermeable to ions was first used in 1950 for the desalination of water (Jusa and McRae 1950). This kind of membrane is surveyed in detail by Strathmann (1994). Much more recently, highly developed polymeric membranes began to be used as electrolytes for experimental rechargeable batteries and, with particular success, for fuel cells. This important use is further discussed in Chapter 11. 

Membrane-type fuel cells. The electrolyte is a polymeric ion-exchange membrane the working temperatures are 60 to 100°C. Such systems were first used in Gemini spaceships. These fuel cells subsequently saw a rather broad development and are known as (solid) polymer electrolyte or proton-exchange membrane fuel cells (PEMFCs). 

While the amount of electricity that can be conducted by polymer films and wires is limited, on a weight basis the conductivity is comparable with that of copper. These polymeric conductors are lighter, some are more flexible, and they can be laid down in wires that approach being one-atom thick. They are being used as cathodes and solid electrolytes in batteries, and potential uses include in fuel cells, smart windows, nonlinear optical materials, LEDs, conductive coatings, sensors, electronic displays, and in electromagnetic shielding. 

Many different kinds of fuel cells are presently known, most of them suitable for high-temperature applications— for details see Ref. [101]. The polymeric proton-conducting membranes (polymer electrolyte membranes PEM) are however suitable for low temperamre operations (<100°C) and have the advantage of low weight. 

The most diffused material for membranes is based on co-polymers of tetrafluoroethylene (TEE) with perfluorosulfonate monomers. The resulting co-polymer is constituted by polytetrafluoroethylene polymeric chain (PTFE, commercially known as Teflon) in which some fluorine atoms are substituted by sulfonated side chains. The monomer perfluoro-sulfonyfluoride ethyl-propyl-vinyl ether is used in membranes commercialized by Dupont with the registered trademark Nafion (Fig. 3.2), which is the most well-known material used as electrolyte in PEM fuel cells. 

The proton exchange membrane - also known as polymer electrolyte membrane (PEM) - fuel cell uses a polymeric electrolyte. The protonconducting polymer forms the heart of each cell electrodes, usually made of porous carbon with catalytic platinum incorporated into them, are bonded to either side of the electrolyte to form a one-piece membrane-electrode assembly (MEA). The following are some key advantages that make PEMs such a promising technology for the automotive market ... 

The temperature of operation of polymer electrolyte membrane fuel cells tends to get higher, because certain advantages are faced, such as improved tolerance of carbon monoxide, the improved ease of water and heat management, and increased energy efficiency. However, several commonly used polymeric membranes cannot withstand the high temperatures. Therefore, there is a need to look for alternative materials. 

Polymeric functional materials are of central importance for the polymer electrolyte membrane fuel cell (PEMFC) and DMFC technologies in particular. In addition to the expected cost reduction due to low-cost mass productimi, for example of polymeric bipolar plates (see Sect. 2.1), the polymeric membranes are irreplaceable in the PFMFC and DMFC technologies. 

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