Electrolytes oxygen diffusion coefficient

Zhuiykov, S., Talanchuk, P., and Shmatko, B.A., Solid electrolyte sensor for measurement of the oxygen diffusion coefficients in melts, Herald of the Kiev Polytech. Inst. Instrumentation 22 (1992) 49-55. 

The oxygen diffusion coefficient, which was determined by the method of isotope exchange for thin electrolyte layers [6],... 

The CCL is a composition of carbon threads, catalyst particles, polymer electrolyte and voids for gas transport. An effective oxygen diffusion coefficient in this system is poorly known. Fortunately, modern catalyst layers are usually thin (typically less than 10 /xm). This enables us to assume that the variation of oxygen concentration across the CCL is not large (the limit of fast oxygen diffusion). In this limit, Eikerling and Komyshev obtained analytical solution in parametric form. However, their parametric solution is cumbersome and difficult to deal with. A transparent result, which reveals important features of CCL function can be obtained as follows. 

EC/DEC/DMC26). An adjuvant appropriate for oxygen transport is added into the electrolyte to increase the oxygen diffusion coefficients. The performances attained with low current densities (0.05 mA/cm ) are 2500 mAh/g and, at high current densities (2 mA/cm ), drop to 200 mAh/g (www.yardney.com) ... 

The diffusion coefficient of oxygen in solid silver was measured with a rod of silver initially containing oxygen at a conceim ation cq placed end-on in contact with a calcia-zirconia electrolyte and an Fe/FeO electrode. A constant potential was applied across dre resulting cell... 

Figure 28. Svensson s macrohomogeneous model for the i— 1/characteristics of a porous mixed-conducting electrode, (a) The reduction mechanism assuming that both surface and bulk diffusion are active and that direct exchange of oxygen vacancies between the mixed conductor and the electrolyte may occur, (b) Tafel plot of the predicted steady-state i— V characteristics as a function of the bulk oxygen vacancy diffusion coefficient. (Reprinted with permission from ref 186. Copyright 1998 Electrochemical Society, Inc.)...

Transport properties of oxygen are better in the fluorinated polymer than in aqueous electrolytes. Although the diffusion coefficient is lower than in water, the oxygen solubility is largely enhanced so that the transport parameter D + c02 is higher than in water (160, 161). 

We will see that in the steady state of the blocking cells, we can extract partial conductivities, and from the transients chemical diffusion coefficients (and/or interfacial rate constants). Cell 7 combines electronic with ionic electrodes here a steady state does not occur but the cell can be used to titrate the sample, i.e., to precisely tune stoichiometry. Cell 1 is an equilibrium cell which allows the determination of total conductivity, dielectric constant or boundary parameters as a function of state parameters. In contrast to cell 1, cell 2 exhibits a chemical gradient, and can be used to e.g., derive partial conductivities. If these oxygen potentials are made of phase mixtures212 (e.g., AO, A or AB03, B203, A) and if MO is a solid electrolyte, thermodynamic formation data can be extracted for the electrode phases. 

The exciton migration within aggregates of cyanine dyes and the possibility of oxygen diffusion into the porous dye film result in a bulk generation of photocurrent [80]. Photoholes produced due to the oxidation of excitons by molecular oxygen diffuse to the back contact. The diffusion coefficient of charge carriers in dye layer (Dc) can be evaluated from the potential-step chronoamperometric measurements in the indifferent electrolyte. Considering dye film as a thin-layer cell, the current vs. time dependence can be described as follows [81] ... 

Given that mullite is a defect structure, one would expect high ionic conductivity. Rommerskirchen et al. have found that mullite has ionic conductivity superior to that of the usual CaO-stabilized Zr02 solid electrolytes at temperatures from 1,400 to 1,600°C [52], The oxygen self diffusion coefficient in the range 1,100 single crystal of 3 2 mullite has been given by [53] ... 

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