Active materials electrochemical equivalent

K depends in a rather complex way on many parameters such as the mass niA of the active materials per unit electrode area, the current density j, the end voltages Vend upon charge and discharge, the current efficiency 7, which is a measure for the electrochemical side-reactions, the thickness d and the porosity P of the active part of the electrode, the temperature T, the solvent/electrolyte system (SES), etc. On the basis of Faraday s law, however, simple relationships for the so-called theoretical specific capacity Ts.th can be derived easily. /sTs,th is identical to the reciprocal electrochemical equivalent me. ... 

Now let us determine the electrochemical equivalent weights per Ah of the basic active materials in a lead—acid cell. 

Electrochemical Equivalent Weights of Active Materials in a Lead—Acid Cell per Ah of Electric Charge (Electricity)... 

Let us determine the electrochemical equivalent weight of Ph per Ah. We will denote as the electrochemical equivalent weight per Ah of a given active material (5, S04)-... 

Current Efficiency. The theoretical electrochemical equivalents representing the materials produced or consumed in the electrolysis of sodium chloride or potassium chloride brines are given in Table 4. In practice, the yield is ca. 95 - 97% of the theoretical value, owing to side reactions at the electrodes and in the electrolyte. With activated titanium anodes, the yield is largely independent of the distance between the electrodes. 

The theoretical capacity of a cell is determined by the amount of active materials in the cell. It is expressed as the total quantity of electricity involved in the electrochemical reaction and is defined in terms of coulombs or ampere-hours. The ampere-hour capacity of a battery is directly associated with the quantity of electricity obtained from the active materials. Theoretically 1 gram-equivalent weight of material will deliver 96,487 C or 26.8 Ah. (A gram-equivalent weight is the atomic or molecular weight of the active material in grams divided by the number of electrons involved in the reaction.)... 

The theoretical capacity of an electrochemical cell, based only on the active materials participating in the electrochemical reaction, is calculated from the equivalent weight of the reactants. Hence, the theoretical capacity of the Zn/Cl2 cell is 0.394 Ah/g, that is,... 

This study on the immobilization of glucose oxidase and the characterization of its activity has demonstrated that a bioactive interface material may be prepared from derivatized plasma polymerized films. UV/Visible spectrophotometric analysis indicated that washed GOx-PPNVP/PEUU (2.4 cm2) had activity approximately equivalent to that of 13.4 nM GOx in 50 mM sodium acetate with a specific activity of 32.0 U/mg at pH 5.1 and room temperature. A sandwich-type thin-layer electrochemical cell was also used to qualitatively demonstrate the activity of 13.4 nM glucose oxidase under the same conditions. A quantitatively low specific activity value of 4.34 U/mg was obtained for the same enzyme solution by monitoring the hydrogen peroxide oxidation current using cyclic voltammetry. Incorporation of GOx-PPNVP/PEUU into the thin-layer allowed for the detection of immobilized enzyme activity in 0.2 M sodium phosphate (pH 5.2) at room temperature. 

Lithium and sulfur are promising active electrode materials for batteries because of their low equivalent weight, low cost, and suitable electrochemical properties. The major question in the use of these active electrode materials is whether the electrodes will be able to provide sustained high performance. Until recently, capacity retention over an extended period has been difficult to achieve. 

As fully discussed in Chapter 2, the electrolyte has complex interactions with the electrode materials (active components) of electrochemical supercapacitors (ESs), which play an important role in the performance of ESs. Besides the active component of ESs, the compatibility or possible interaction between the electrolyte and inactive components such as current collectors, binders, and separators should also be considered. For example, the possible corrosion of current collectors in certain electrolytes could reduce the operative cell voltage and decrease the lifetime of ESs. Besides, the transfer of electrolyte ions across the separator could affect the equivalent series resistance (ESR) and the power performance of the ES. Therefore, the inactive components of ESs should be compatible with the electrolytes and electrode materials. 

LSV but the potential scan is reversed once potential limits are reached. Thus, CV is a reversal technique and is the potential scan equivalent of double potential step chrOTioamperometry [24]. CV is commonly used to diagnose the electrochemical activity of die catalyst spread on top of the electrodes. Typically, the catalyst for HT-PEMFC consists of platinum (Pt) carbon supported and a binder material such as phosphoric acid-doped PBI or other ionomers [55-58]. The binder serves to facilitate proton conduction between electrolyte membrane and the Pt active sites, whereas the carbon support enhances Pt dispersion through the catalyst layer and the electronic conductivity. Therefore, the electrochemical activity of the electrode catalyst layer strongly depends on the contact between catalyst active sites, reactants, and proton/elec-tron-conducting materials. 

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