Density, Electrode Potential, and Current Efficiency

Current Density, Electrode Potential, and Current Efficiency 

At a cathode, positive current flows from the electrolyte to the electrode. Therefore, by the above definition E for a cathode tends to be negative, and it is positive for an anode. 

If the electrode potential E is kept constant and the area of the electrode is doubled, the current passing between the electrode and electrolyte is also doubled. In other words, the current supported by an electrode is proportional to its area, other parameters remaining unchanged. This is why the current supported by unit area of electrode is a more fundamental property than the total current it is referred to as the current density (i). 

FIGURE 1.3. Region near an electrode interface. E = metal potential - solution potential. 

The current density for an electrochemical reaction is therefore equivalent to the rate of reaction. As we shall see in Chapter 3 when deriving 

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