Porous composite electrodes

Gas-diffusion electrode (GDE) is a porous composite electrode developed for fuel cell technology, usually composed of Teflon bonded catalyst particles and carbon black. GDEs have been ap-... [Pg.176]

Fig. 11.11 Cycle life of porous composite electrode consisting of p-Si (1 jxm) + MCMB 6-28 (1 1 by weight). Cycling performed at constant capacities 500, 600, and 700 mA h g K Load density approximately 1 mA cm , amount of the binder (SBR + CMC mass) 16 wt%, Coulombic efficiency over the first cycle around 70%, for the next cycles 98-99% vs. lithium metal, electrolyte 1-M LiPFg in MEC/EC 3 7...

Levi, M. D. and D. Aurbach (2004). Impedance of a single intercalation particle and of non-homogeneous, multilayered porous composite electrodes for Li-ion batteries. The Journal of Physical Chemistry B 205(31), 11693-11703. [Pg.93]

Tanner, C. W., Fung, K.-Z., and Virkar, A. V. (1997). The effect of porous composite electrode structure on solid oxide fuel cell performance. 1. Theoretical analysis. J Electrochem. Soc 144 21-30. [Pg.98]

The main structural components in modem PEFCs are the porous composite electrodes. The primary purpose of utilizing porous electrodes is to enhance the active surface area of the catalyst by several orders of magnitude in comparison to planar electrodes with the same in-plane geometrical area. In the CLs, the fluxes of reactant gases, protons, and electrons meet at the catalyst particle surface. Active catalyst nanoparticles are located at spots that are connected simultaneously to the percolating phases of proton, electron, and gas transport media. An important implication of the electrode s finite thickness is the necessity to provide transport of neutral molecules and protons through the depth of the porous electrode. Additional overhead is caused by the transport of neutral reactants through FF, GDL, and MPL. This leads to specific potential losses in the electrodes, which will be considered in detail in Chapter 4. ... [Pg.7]

In this chapter, connections will be established between electrocatalytic surface phenomena and porous media concepts. The underlying logics appear simple, at least at first sight. Externally provided thermodynamic conditions, operating parameters, and transport processes in porous composite electrodes determine spatial distributions of reaction conditions in the medium, specifically, reactant and potential distributions. Local reaction conditions in turn determine the rates of surface processes at the catalyst. This results in an effective reactant conversion rate of the catalytic medium for a given electrode potential. [Pg.163]

Directly measuring intercalation stress in battery electrode materials is difficult because of the multiple phases of composite electrodes and also because it is usually associated with other stresses [29, 35]. In the case of cathode and anode materials, intercalation-induced stress is believed to be one of the main factors causing battery degradation, since it results in damage to reversible interaction sites and structural fatigue [14]. The active material of each electrode is usually embedded inside a binder and conductive matrix to form a porous structure as shown in Figure 26.4 (modified from [5, 6]). This combination of binder and conductive matrix provides electron conduction paths and integrates all active particles into one piece of porous composite electrode, which is then wetted by electrolyte. [Pg.885]

Charge measurements, as mentioned above, were also performed using the porous Pt electrodes required by the on-line MS technique. At low methanol concentrations (10 2 M), the charge ratio QaJQm, near 1 indicates that (C,0, H) must be the predominant adsorbate composition [14,47], This result is in good agreement with that of Heitbaum and co-workers [15] who used Eq. 1.2 to determine the number of electrons, n, per C02 produced from methanol adsorbate. They found for n a value of 3, which would be in agreement with reactions 2.1 or 2.2 for methanol adsorption. [Pg.145]

Sonoelectrochemistry has also been used for the efficient employment of porous electrodes, such as carbon nanofiber-ceramic composites electrodes in the reduction of colloidal hydrous iron oxide [59], In this kind of systems, the electrode reactions proceed with slow rate or require several collisions between reactant and electrode surface. Mass transport to and into the porous electrode is enhanced and extremely fast at only modest ultrasound intensity. This same approach was checked in the hydrogen peroxide sonoelectrosynthesis using RVC three-dimensional electrodes [58]. [Pg.115]

Clearly, the effective conductivity of a porous cermet electrode with a given composition (Ni to YSZ ratio) and phase distribution changes with porosity. When NiO particle size was reduced, the porosity of the cermet would be decreased as well [31,32] Equation (2.1) suggests that the effective conductivity increases as the porosity is reduced [15],... [Pg.81]

Su-Il Pyun provide a comprehensive review of the physical and electrochemical methods used for the determination of surface fractal dimensions and of the implications of fractal geometry in the description of several important electrochemical systems, including corroding surfaces as well as porous and composite electrodes. [Pg.9]

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). [Pg.447]

Lagergren, C. Simonsson, D. The effects of oxidant gas composition on the polarization of porous LiCo02 electrodes for the molten carbonate fuel cell. J. Electrochem. Soc. 1997, 144 (11), 3813-3817. [Pg.1761]

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