Electrode materials methods

Ethylene glycol can be produced by an electrohydrodimerization of formaldehyde (16). The process has a number of variables necessary for optimum current efficiency including pH, electrolyte, temperature, methanol concentration, electrode materials, and cell design. Other methods include production of valuable oxidized materials at the electrochemical cell s anode simultaneous with formation of glycol at the cathode (17). The compound formed at the anode maybe used for commercial value direcdy, or coupled as an oxidant in a separate process. 

An Li-Al Alloy was investigated for use as a negative electrode material for lithium secondary batteries. Figure 41 shows the cycle performance of a Li-Al electrode at 6% depth of discharge (DOD). The Li-Al alloy was prepared by an electrochemical method. The life of this electrode was only 250 cycles, and the Li-Al alloy was not adequate as a negative material for a practical lithium battery. 

The availability of high-intensity, tunable X-rays produced by synchrotron radiation has resulted in the development of new techniques to study both bulk and surface materials properties. XAS methods have been applied both in situ and ex situ to determine electronic and structural characteristics of electrodes and electrode materials [58, 59], XAS combined with electron-yield techniques can be used to distinguish between surface and bulk properties, In the latter procedure X-rays are used to produce high energy Auger electrons [60] which, because of their limited escape depth ( 150-200 A), can provide information regarding near surface composition. 

Kolbe electrolysis is a powerful method of generating radicals for synthetic applications. These radicals can combine to symmetrical dimers (chap 4), to unsymmetrical coupling products (chap 5), or can be added to double bonds (chap 6) (Eq. 1, path a). The reaction is performed in the laboratory and in the technical scale. Depending on the reaction conditions (electrode material, pH of the electrolyte, current density, additives) and structural parameters of the carboxylates, the intermediate radical can be further oxidized to a carbocation (Eq. 1, path b). The cation can rearrange, undergo fragmentation and subsequently solvolyse or eliminate to products. This path is frequently called non-Kolbe electrolysis. In this way radical and carbenium-ion derived products can be obtained from a wide variety of carboxylic acids. 

Most electrode materials are hydrophilic and readily wetted by aqueous solutions. Two methods are used to create and maintain an optimum gas/solution ratio in the electrode. The first method employs a certain excess gas pressure in the gas space. This causes the liquid to be displaced from the wider pores in finer pores the liquid continues to be retained by capillary forces. The second method employs partial wetproofing of tfie electrode by the introduction of hydrophobic materials (e.g., fine PTFE particles). Tfien the electrolyte will penetrate only those pores in the hydrophilic electrode material where the concentration of hydrophobic particles is low. 

Cathodic reduction is the most promising approach to the removal of carbon dioxide from a closed atmosphere. Methods developed so far provide for electrode materials, electrolytes, and electrolysis conditions where CO2 can be reduced to hquid organic products of low molecular weight such as formic acid. More complex systems are required to regenerate foodstuffs from the rejects of human vital activities during... 

The electrode material and its pretreatment considerably influence the course of the electrode process. The importance of non-electrochemical methods is constantly increasing as a result of the development of experimental techniques. 

From experimental measurements it was found that there was a fairly good linear relation between the SC capacitance and current, the slope being dependent on the electrode material and electrolyte. If the dependence is known, it can be used to make the Ragone plot calculations more accurate. Therefore, the following method was employed in our evaluations. 

If we assume a quasi-cylinder pore structure of the electrode material as in Fig. 1, an average effective pore radius r can be evaluated from the relationship r = 2V/A, where V is the total pore volume, and A is the total pore surface that can also be determined using the DFT method (see also [5]). Then the migration coefficients determined as shown in Fig. 5 can be plotted vs. the pr2 product - see, e.g., Fig. 7 for five electrodes, which were made of various porous carbons produced by Skeleton Technologies. 

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