Polymer electrolyte fuel cells component

Giilzow, E., Schulze, M., Wagner, N., Kaz, T., Reissner, R., Steinhilber, G., and Schneider, A. Dry layer preparation and characterization of polymer electrolyte fuel cell components. Journal of Power Sources 2000 86 352-362. 

M. Eikerling, A. A. Kornyshev and A. A. Kulikovsky, Physical modelling of polymer electrolyte fuel cell components, cells and stacks, in Encyclopaedia of Electrochemistry, 5 (D. Macdonald, Ed.), 2004 (in Press). 

Gulzow E, Schulze M, Wagner N, Kaz T, Reissner R, Steinhilber G, et al. Dry layer preparation and characterisation of polymer electrolyte fuel cell components. J Power Sources 2000 86(l-2) 352—62. 

Eberhardt SH, Marone F, Stampanoni M et al (2014) Quantifying phosphoric acid in high-temperature polymer electrolyte fuel cell components by X-ray tomographic microscopy. J Synchrotron Radiat 21 1319-1326... 

Table 5.14 Measured Thermal Conductivity of Polymer Electrolyte Fuel Cell Components.

The solid polymer electrolyte fuel cell is that on which the most development work was done in the 1990s because of its projected use in the development of an electrochemical engine for cars. The absence of a bulk liquid component while keeping to temperatures of 80 °C if pure H2 or H2 produced from methanol or gasoline on board a vehicle is available, signifies a great advantage. Conversely, the acid environment needs Pt. 

Fig. 2. Components of a single polymer electrolyte fuel cell used for laboratory investigations. In a stack, relatively thinner current collectors will become bipolar plates with the flow fields machined on both sides.

Polymer-electrolyte fuel cells (PEFC and DMFC) possess a exceptionally diverse range of applications, since they exhibit high thermodynamic efficiency, low emission levels, relative ease of implementation into existing infrastructures and variability in system size and layout. Their key components are a proton-conducting polymer-electrolyte membrane (PEM) and two composite electrodes backed up by electronically conducting porous transport layers and flow fields, as shown schematically in Fig. 1(a). 

Fig. 8.9 Polymer electrolyte fuel cell stack with 100 cells and graphite-based bipolar plates. Partly expanded view for one cell with electrochemical components.

The membrane in the polymer electrolyte fuel cell (PEFC) is a key component. Not by chance does the type of membrane brand the cell name - it is the most important component determining cell architecture and operation regime. Polymer electrolyte membranes are almost impermeable to gases, which is crucial for gas-feed cells, where hydrogen (or methanol) oxidation and oxygen reduction must take place at two separated electrodes. However, water can diffuse through the membrane and so can methanol. Parasitic transport of methanol (methanol crossover) severely impedes the performance of the direct methanol fuel cell (DMFC). 

Fig. 3 Components of the polymer electrolyte fuel cell (PEFC) membrane electrode assembly (MEA) on the left, including separator plates and gasket. A schematic of a PEFC stack is shown on the right, comprising a number of single cells in series...

The three components of the fuel cell, anode, cathode, and electrolyte form a membrane-electrolyte assembly, as, by analogy with polymer electrolyte fuel cells, one may regard the thin layer of solid electrolyte as a membrane. Any one of the three membrane-electrode assembly components can be selected as the entire fuel cell s support and made relatively thick (up to 2 mm) in order to provide mechanical stability. The other two components are then applied to this support in a different way as thin layers (tenths of a millimeter). Accordingly, one has anode-supported, electrolyte-supported, and cathode-supported fuel cells. Sometimes though an independent metal or ceramic substrate is used to which, then, the three functional layers are applied. 

Stack Components In collaboration with partners, research and develop technologies to overcome the most critical technical hurdles for polymer electrolyte fuel cell stack components for both stationary and transportation applications. Critical technical hurdles include cost, durability, efficiency, and overall performance of components such as the proton exchange membranes, oxygen reduction electrodes, advanced catalysts, bipolar plates, etc. 

Abstract The polymer electrolyte fuel cell (PEFC) consists of disparate porous media microstructures, e.g. catalyst layer, microporous layer, gas diffusion layer, as the key components for achieving the desired performance attributes. The microstmcture-transport interactions are of paramount importance to the performance and durability of the PEFC. In this chapter, a systematic description of the stochastic micro structure reconstmction techniques along with the numerical methods to estimate effective transport properties and to study the influence of the porous structures on the underlying transport behavior is presented. 

Akey performance limitation in the polymer electrolyte fuel cell (PEFC) originates from the multiple, coupled and competing, transport interactions in the constituent porous components. The suboptimal transport behavior resulting from the underlying complex and multifunctional microstmctures in the catalyst layer (CL), gas diffusion layer (GDL) and microporous layer (MPL) leads to water and thermal management issues and undesirable performance loss. Therefore, it is imperative to understand the profoimd influence of the disparate porous microstmctures on the transport characteristics. In this chapter, we highhght the stochastic microstmcture reconstmction technique and direct transport simulation in the CL, GDL and MPL porous stmctmes in order to estimate the effective transport properties and imderstand the microstmctural impact on the imderlying transport behavior in the PEFC. 

Figure 17.19 Schematic showing a polymer electrolyte fuel cell and the various components.

FIGURE 1.1 Layout of a polymer electrolyte fuel cell, showing functional components and processes. FF, DM, and CL abbreviate flow field, diffusion media, and catalyst layer, respectively. Note that throughout this book, DM will also be referred to as a GDL (gas diffusion layer). 

The history of research on polymer electrolyte fuel cells spans about 50 years. PEFCs appeared in the focus of scientific interest toward the end of the 1980s. Generally, PEFC design is simple and all the needed components are available on the market. Take two gas-diffusion electrodes separated by a polymer electrolyte membrane and clamp this membrane-electrode assembly between two graphite plates with channels for hydrogen and air supply—the cell is ready. 

The center of the fuel cell is the polymer electrolyte membrane, as it defines the properties needed for other components of the fuel cell. However, fuel cells efficiency and power density also strongly depend on the conductance of electrolytes, and only acidic electrolyte can be used to aid carbon dioxide rejection for DMFC. The performance of polymer electrolyte fuel cells is closely related to the... 

Polymer electrolyte fuel cell (PEFC) components generally have to fulfill the following four technical requirements to allow for an effective long-term fuel cell operation functionality, which is mostly determined by the product design service life which is influenced by the material as well as the design reliability, essentially determined by the manageability and process stability and sustainability, which is predominantly influenced by function integration and series production. 

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