Polymeric electrolyte membrane fuel cells

In recent years the concept of a fuel cell propulsion system has gained in attention as a result of the need to reduce the fossil fuel consumption and greenhouse gas emissions. Since the fuel cells suitable for vehicle application (polymeric electrolyte membrane fuel cells) are fuelled by hydrogen, and deliver power as long as fuel and air are supplied, they potentially can provide the range capabilities of an internal combustion engine when used in a power system, but with clean and quiet operation. Therefore, the fundamental benefit of this type of propulsion consists in the possibility to adopt pollution-free electric drive-trains, without the drive range limitations typical of traditional electric vehicles. 

PBI membranes have been the critical components in high temperature polymeric electrolyte membrane fuel cells. PBI fuel cells tolerate much more impurities in the Hj fuel compared to low temperature fuel cells. Therefore, they are preferred in fuel cell systems where the Hj supplies are from reformers converting other fuels to Hj. PBI fuel cells are also suitable for combined heat and power fuel cell systems. In other applications, PBI membranes have been successfully demonstrated to purify Hj while pumping it against a high pressure. The technology can be applied... 

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. 

In the Proton-Exchange Membrane Fuel Cell (or Polymer-Electrolyte Membrane Fuel Cell) the electrolyte consists of an acidic polymeric membrane that conducts protons but repels electrons, which have to travel through the outer circuit providing the electric work. A common electrolyte material is Nafion from DuPont , which consists of a fluoro-carbon... 

Chi, W.S., Patel, R., Hwang, H., Shul, Y.G., Kim, J.H., Preparation of poly(vinylidene fluoride) nanocomposite membranes based on graft polymerization and sol-gel process for polymer electrolyte membrane fuel cells, J. Solid State Electrochem., 2012, 16, 1405-1414. 

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). 

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... 

The membranes in polymeric proton-exchange membrane fuel cells (PEMFC) serve as a solid electrolyte. The membrane s conductivity comes about because in the presence of water it swells, a process leading to the dissociation of the acidic functional groups and formation of protons free to move about throughout the membrane. 

Proton-exchanging membrane fuel cells (PEMFC) are considered to be one of the most promising types of electrochemical device for power generation [1-10]. Low operation temperatures and the wide range of power make them attractive for portable, automotive, and stationary applications. However, advances made in these markets require further cost reduction and improved reliabiUty. These can be achieved through development and implementation of novel proton-exchange membranes with higher performance and lower cost as compared to the state of the art polymeric electrolytes. 

C. Manea and M. Mulder, New polymeric electrolyte membranes based on proton donor-proton acceptor properties for direct methanol fuel cells. Desalination 147, 179-182 (2002). 

One of the first attempts to use a polymeric ion exchange membrane as a solid electrolyte for fuel cells was described by Thomas Grubb of GE in 1959. Initially, between 1959 and 1961, polysulfuric sulfonic acid (PSSA) membranes were used. The early versions of the PEFC, as used in the NASA Gemini spacecraft, had a lifetime of only about 500 h because of membrane degradation, but that was sufficient for those limited early missions. The development program continued... 

Proton exchange membrane fuel cell (PEMFC), schematically shown in Figure 3.7, is using a polymeric proton exchange membrane (PEM) as an electrolyte at temperatures from ambient up to around 120°C. Nafion is used for PEM and Pt for electrodes. Both of these materials are very expensive. The durability of the PEMFC is still under studies for a wide implementation. This fuel cell is considered a first candidate for automotive applications. 

Two types of fuel cells that employ polymeric cation exchange membranes as the electrolyte material are the proton exchange membrane fuel cell (PEMFC) and the direct methanol fuel cell (DMFC). The membrane has a multifunchonal role in these devices ... 

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