Cathode electrochemical equivalents

Corrosion Rate by CBD Somewhat similarly to the Tafel extrapolation method, the corrosion rate is found by intersecting the extrapolation of the linear poi tion of the second cathodic curve with the equihbrium stable corrosion potential. The intersection corrosion current is converted to a corrosion rate (mils penetration per year [mpy], 0.001 in/y) by use of a conversion factor (based upon Faraday s law, the electrochemical equivalent of the metal, its valence and gram atomic weight). For 13 alloys, this conversion factor ranges from 0.42 for nickel to 0.67 for Hastelloy B or C. For a qmck determination, 0.5 is used for most Fe, Cr, Ni, Mo, and Co alloy studies. Generally, the accuracy of the corrosion rate calculation is dependent upon the degree of linearity of the second cathodic curve when it is less than... 

The volume of the metal produced depends on the current density, the electrolysis time, the cathode area, and the electrochemical equivalent. Yt is usually expressed as a function of the current density. The interrelationship among Yt, the specific area of the cathode, As (m2/m3), i.e., the area of the cathode per unitvolume of the reactor (cathode area/volume of the cell), the fractional current efficiency, T, and the current density, I, is given by ... 

The equilibrium, I2 + I = Ia, exists in these solutions, but. this does not affect the stoichiometrical relations. After the electrolysis is completed, a delivery tube is connected to D, and the anode and cathode portions of the electrolytes are drawn over into separate flasks. The two portions are then titrated for iodine with arsenious acid solution which lias been standardized against carefully purified iodine. By comparison with the silver coulometer, Bates and Vinal8 found the electrochemical equivalent of iodine to be 0.00131505 gram per coulomb, leading to a value of the faraday of 96,514. The accuracy of the experimental work may be judged from the results for the different experiments given in Table I. 

Table9.12. Electrochemical equivalents of common anode and cathode materials used in primary and secondary cells (293.15 K and 101.325 kPa)...

In the particular case of lithiation or delithiation of cathode materials used in lithium secondary batteries, the calculation of the electrochemical equivalent involves an additional parameter related to the reaction of intercalation of lithium cations into the crystal lattice of the host cathode materials. Consider the theoretical reversible reaction of intercalation of lithium into a crystal lattice of a solid host material (e.g., oxide, sulfide) ... 

The two electrochemical equivalents of some selected solid host cathode materials and corresponding intercalated compounds used in rechargeable lithium batteries are presented in Table 9.13. 

The smnmary equation (10) is an electrochemical equivalent of the chemical reaction (1). However, this system does not take into account the fact that for reaction (9) to occur the Cl- anions obtained in proximity to the cathode surface by reaction (8)... 

Cathodic material Molecular weight Valences involved Specific gravity (gcm ) Electrochemical equivalent Calc, cell voltage (against Li) (V)... 

In this equation, which may be regarded as the electrochemical equivalent of the well-known Arrhenius expression with two exponential terms representing anodic (oxidation) and cathodic (reduction) currents [74], the current I observed at the electrode, when both A and B are soluble in solution, is related to the electrode area A, the standard rate constant (in m s"0> the surface concentrations [A] =o [ ]x=o>the transfer coefficient a, and the overpotential Further, n denotes the number of electrons transferred per... 

Faraday s laws provide the theoretical basis of electrodeposition (Antropov, 1977). The qrrantity of metal deposited (W) at the cathode surface can be expressed as the product of quantity of total coulombs passed (QJ and the electrochemical equivalent of the metal (z ) ... 

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