Electrical behavior in the quasi-static state

we wish to describe the relation between the voltage U of the electrolyzer and its cnrrent I. Very often, this relation /(/) is called the polarization curve or 

In practice, it will be higher than this, because of the physico-chemical phenomena linked to the occurrence of the reaction of dissociation of water phenomena of activation, transport of species and charges. 

On the scale of a cell, the polarization curve has the following general equation  

Theoretically, it is possible to separate the contribution of each electrode. In practice, this is fairly tricky to do for a monocell, and very difficult on the scale of an entire stack. Hence, in our discussions, we shall quite deliberately adopt the policy of considering only the overall contribntion, in terms of voltage at the terminals of the electrolyzer, made by each of the phenomena which take place locally at the level of each electrode. 

In the case of an electrolyzer stack, the voltage at its terminals will be the sum of all the voltages of the cells which make up that stack and which are electrically coimected in a series  

---