Measurement of kinetic and thermodynamic electrode

In-situ electrochemical techniques may be conveniently used to analyse the fundamental thermodynamic and kinetic parameters which are responsible for the performance of electrodes. The methods are nondestructive and may be applied to the actual galvanic cell. The data may be easily determined as a function of the discharge state. 

A current through the galvanic cell changes the composition according to Faraday s law. The time integral of the current / dt is a very precise measure of the variation of the concentration of the electroactive component 

Also the activities of the electro-active and other components may be readily determined as a function of the stoichiometry. These values have to be within the stability range ( stability window ) of the electrolyte. 

The phase diagram of an electrode material may be determined from the slope of the coulometric titration curve. An electrode of N components shows activities which are independent of the composition as long as the maximum number of N phases are in equilibrium with each other. Relative changes in the amounts of the different phases do not change the activities of the components and therefore keep the cell voltage constant. This causes voltage plateaux for any region of the equilibrium of the maximum number of phases. 

The high resolution for controlling the stoichiometry allows us to determine even very narrow ranges of stoichiometry including that of so-called line phases. Non-stoichiometries of the order of 10 or lower may be readily resolved. Knowledge of the variation of the cell voltage 

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