Current-voltage curve, electrolytic cell

Otherwise it has been shown that the accumulation of electrolytes by many cells runs at the expense of cellular energy and is in no sense an equilibrium condition 113) and that the use of equilibrium thermodynamic equations (e.g., the Nemst-equation) is not allowed in systems with appreciable leaks which indicate a kinetic steady-state 114). In addition, a superposition of partial current-voltage curves was used to explain the excitability of biological membranes112 . In interdisciplinary research the adaptation of a successful theory developed in a neighboring discipline may be beneficial, thus an attempt will be made here, to use the mixed potential model for ion-selective membranes also in the context of biomembrane surfaces. 

Figure 2. Typical current-voltage curves of Mg-air cell (Sair - 80 cm2 Mg - MA8M06) operating in 1N, 2 N and 4 NNaCl-electrolyte.

Several types of experimental magnesium-air cells were tested. These cells varied in their size (the working area of the air electrodes used) [10]. The current-voltage curves of an experimental Mg-air cell with two air electrodes (Sair = 80 cm2) with pyrolyzed CoTMPP catalyst and sandwich-type Mg anode (MA8M06) operating in NaCl-electrolytes with different concentrations are presented by Figure 2. 

To use Faraday s law for the purpose at hand, the generator electrode reaction must be limited to the one of interest to assure that the charge consumed by the desired electron transfer reaction is essentially equal to the charge applied to the cell. Difficulties arise because it is not possible to control independently both the current and the electrode potential, and because only the current applied to the cell can be known directly in the experiment. A knowledge of the current-voltage curves for the precursor and the supporting electrolyte will provide valuable information for the design of practical experiments. 

The shape of the current-voltage curve at the cathode of the cell illustrates the two cases, as shown in Figure 12.4. Two domains can be observed (i) the A-B interval corresponds to the case 1 (the reduction of oxygen takes place within the electrolytic... 

Electrolytic cells, p. 447 Current-voltage curves, p. 448 Supporting electrolytes, p. 450 Amperometric electrodes, p. 451 Chemically modified electrodes, p. 452 Ultramicroelectrodes, p. 454... 

Figure 4. Current-voltage curves for 50 50 mm anode-supported single cells with a YSZ electrolyte applied by sol-gel technique and with an LSCF-type cathode as a function of the temperature (fuel gas H2 (3% H2O) = 1000 ml/min, oxidant air = 1000 ml/min).

The current bypass in the multiple-channel Ru02A SZ cell was estimated by the following indirect method.Two series of current-voltage curves were determined under the same conditions, one before and another after deposition of the catalyst. Measurements were made at various gas compositions and at different temperatures, the same in both cases. It was assumed that coating the support with the catalyst does not change the cnrrent distribntion in the solid electrolyte, but simply opens new parallel conduction pathways. The current bypass was then calculated from the currents measured at a same cell potential,... 

Misono et al. have reported ° similar reactions in diglyme (1,2-dimethoxyethane) at a mercury cathode with Bu4NBr electrolyte and added water. In a divided cell, substantial yields of 1,4-dihydrobenzene and 2,5-dihydrotoluene are produced from benzene and toluene respectively. No 1,4-dihydrotoluene or 1,2-dihydrobenzene were found although a little cyclohexene was detected. The current-voltage curves are essentially unaffected by the presence of the aromatic substance in the system, indicating the intermediacy of the solvated electron and the relatively slow nature of the reduction process. 

Bistability is also observed in physiological systems, and the phenomenon has a formal similarity with electro-kinetic phenomenon. In nerve physiology, the so-called switching mechanism in nerve cells from a rest to action potential corresponds to the above phenomena. Current-voltage curves [44, 45] similar to the above are obtained in biological systems where we have different concentrations of electrolytes across the cell membranes. 

Similar current-voltage curves were reported [27] for the hydrogen-oxygen fuel cell with different solid solutions of Ce03—La2 03 as electrolyte. However, the solid electrolytes possessed some electronic conductance. Although the addition of Th02 reduced the electronic conductance, it led to an undesirable decrease in performance. 

Current-voltage curves (a, b) for the oxidation of converted propane are shown in Fig. 89 together with a curve (c) for the oxidation of hydrogen. The curves were taken [5] at 1000°C in a cell with Zro.gs Cao.15 Oi.ss as solid electrolyte and porous platinum electrodes. The oxygen pressure was 1 atm. The curves for the oxidation of converted propane are linear and parallel to the curve for the oxidation of hydrogen in a wide potential... 

The commonest form of data on electrode processes is that of current-voltage curves. When there is an electrolytic cell made of one polarizable and one non-polarizable electrode and a potential difference is imposed between them, it can be safely assumed that the potential of the non-polarizable electrode remains constant, the imposed voltage changes the potential of the polarizable (working) electrode alone. Thus, when dealing with the reaction... 

With existing experimental data the four current-voltage curves obtained for the same working conditions were selected. The thickness of the electrolyte was examined for the following size 4, 8, 15 and 20 pm. Experimental data of the electrolyte thickness dependence on sohd oxide fuel cell performance were taken... 

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