Polymer electrolyte membrane fuel cells characteristics

Cho E.A., Jeon U.-S., Fla H.Y., Hong S.-A., Oh I.-H. Characteristics of composite bipolar plates for polymer electrolyte membrane fuel cells. Journal of Power Sourses 125 (2004) 178-182. 

Sun H, Zhang G, Guo LJ, Dehua S, Liu H (2007) Effects of humidification temperatures on local current characteristics in a PEM fuel cell. J Power Sources 168 400-407 Park SK, Cho EA, Oh IH (2005) Characteristics of membrane humidifiers for polymer electrolyte membrane fuel cells. Korean J Chem Eng 22 877-881... 

Polymer electrolyte fuel cells, also sometimes called SPEFC (solid polymer electrolyte fuel cells) or PEMFC (polymer electrolyte membrane fuel cell) use a proton exchange membrane as the electrolyte. PEEC are low-temperature fuel cells, generally operating between 40 and 90 °C and therefore need noble metal electrocatalysts (platinum or platinum alloys on anode and cathode). Characteristics of PEEC are the high power density and fast dynamics. A prominent application area is therefore the power train of automobiles, where quick start-up is required. 

N. Rajalakshmi, T. T. Jayanth, R. Thangamuthu, G. Sasikumar, P. Sridhar, and K. S. Dhathathreyan, Water Transport Characteristics of Polymer Electrolyte Membrane Fuel Cell, International Journal of Hydrogen Energy, 29, 1009 (2004). 

The largest progress was made in the area of membrane fuel cells. Today s membrane fuel cells differ widely from the prototypes of the 1960s in their design and characteristics. Improved polymer electrolyte membrane fuel cells of medium-size power output are widely used and produced on a large commercial scale. 

There exist a variety of fuel cells. For practical reasons, fuel cells are classified by the type of electrolyte employed. The following names and abbreviations are frequently used in publications alkaline fuel cells (AFC), molten carbonate fuel cells (MCFC), phosphoric acid fuel cells (PAFC), solid oxide fuel cells (SOFC), and proton exchange membrane fuel cells (PEMFC). Among different types of fuel cells under development today, the PEMFC, also called polymer electrolyte membrane fuel cells (PEFC), is considered as a potential future power source due to its unique characteristics [1-3]. The PEMFC consists of an anode where hydrogen oxidation takes place, a cathode where oxygen reduction occurs, and an electrolyte membrane that permits the transfer of protons from anode to cathode. PEMFC operates at low temperature that allows rapid start-up. Furthermore, with the absence of corrosive cell constituents, the use of the exotic materials required in other fuel cell types is not required [4]. 

Tabe, Y, M. Saito, K. Kukui, and T. Chikahisa. 2012. Cold start characteristics and freezing mechanism dependence on start-up temperature in a polymer electrolyte membrane fuel cell.. Power Sources 208 366-373. 

Tabe, Y, Kikuta, K., Chikahisa, T. Kozakai, M. Basic evaluation of separator type specific phenomena of polymer electrolyte membrane fuel-cell by the measurement of water condensation characteristics and current density distribution. J. Power Sources 193 (2009a), pp. 416-424. 

Since the type of electrolyte material dictates operating principles and characteristics of a fuel cell, a fuel cell is generally named after the type of electrolyte used. For example, an alkaline fuel cell (AFC) uses an alkaline solution such as potassium hydroxide (KOH) in water, an acid fuel cell such as phosphoric acid fuel cell (PAFC) uses phosphoric acid as electrolyte, a solid polymer electrolyte membrane fuel cell (PEMFC) or proton exchange membrane fuel cell uses proton-conducting solid polymer electrolyte membrane, a molten carbonate fuel cell (MCFC) uses molten lithium or potassium carbonate as electrolyte, and a solid oxide ion-conducting fuel cell (SOFC) uses ceramic electrolyte membrane. 

The required properties of solid polymer electrolyte membranes may be divided into interfacial and bulk properties [9]. As described above, the interfacial characteristics of these membrane materials are important for the optimum formation of the three-phase boundary. Hence, flow properties, gas solubility, wetting of carbon supported catalyst surfaces by the polymer, etc. are of paramount importance. The bulk properties concern proton conductivity, gas separation, and mechanical properties. This whole ensemble of properties has to be considered and balanced in the development of novel proton-exchange membranes for fuel cell application. 

ILs— tetraethyl and tetrabutyl ammonium nitrate— were used as additives for protein refolding. Pure liquid tetra-alkyl ammonium nitrates were utilized to denature the protein. EAN is a colorless to slightly yellow-colored IL having no characteristic odor and works as an amphoteric solvent. EAN is a liquid electrolyte at room temperamre and involves dissociable protons thus, it is also called as protic IL [79-82], which can be used as medium electrolytes for fuel cells [83] and polymer membrane separators [84]. The properties and apphcations of EAN were recently reviewed in the literature [85], EAN is miscible with water to form mixtures at aity composition, and both the component ions favorably form hydrogen bonds with water [86]. 

Fuel cells are currently at the early commercial stage for some applications. There are increasing numbers of units deployed in field trials for an increasing number of applicahons. The polymer electrolyte membrane (PEM) fuel cell is one of the most common types of fuel cells under development today. (They also are commonly referred to as proton exchange membrane fuel cells based on the key characteristic of the solid electrolyte membrane to transfer protons from the anode to the cathode.) With the experience gained through... 

Shim, J., Ha, H. Y., Hong, S. and Oh, I. 2002. Characteristics of the Nation ion-omer-impregnated composite membrane for polymer electrolyte fuel cells. Journal of Power Sources 109 412-417. 

Another characteristic of the proton-conducting membrane is that it has low permeability to oxygen and hydrogen in the gas phase so that a high coulombic efficiency exists [7], In addition, in this fuel cell type, the electrodes are normally formed on a thin layer on each side of a protonconducting polymer membrane used as an electrolyte, and platinum catalysts are required for both the anode and the cathode for the proper operation of this fuel cell [9],... 

Figure 5.32. Impedance plots for single cells at ambient temperature, a Nation 117. Cell voltage and ohmic drop corrected potential (in parenthesis) ( ) 0.9 V (0.9 V) ( ) 0.8 V (0.81 V) (A) 0.70 V (0.76 V) ( ) 0.6 V (0.74 V) ( ) 0.5 V (0.74 V). b Nafion 112. Cell voltage and ohmic drop corrected potential (in parenthesis) ( ) 0.9 V (0.9 V) ( ) 0.8 V (0.81 V) (A ) 0.70 V (0.73 V) ( ) 0.6 V (0.67 V) ( ) 0.5 V (0.61 V). Plots were corrected for the high-frequency resistances. Left detail of the high-frequency regions [29]. (Reprinted from Journal of Electroanalytical Chemistry, 503, Freire TJP, Gonzalez ER. Effect of membrane characteristics and humidification conditions on the impedance response of polymer electrolyte fuel cells, 57-68, 2001, with permission from Elsevier.)...

Freire TJP, Gonzalez ER (2001) Effect of membrane characteristics and humidification conditions on the impedance response of polymer electrolyte fuel cells. J Electroanal Chem 503 57-68... 

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