Bubble diffusion region resistance

The bubbles in the inter-electrode gap (bubble diffusion region and bulk region) increase the inter-electrode resistance, as they affect the electrical conductivity of the electrolyte. The parameter describing this increase is the gas void fraction e, defined as the fraction between the volume of gas and the total volume of liquid and gas. Several relations are used in the electrochemical literature to quantify this effect. The most widely used are the relations from Bruggeman [16] ... 

The expression for R(9) contains three contributions. The first is the resistance of the bulk electrolyte. The second is due to the bubble diffusion region. As discussed in Section 3.4, this contribution is almost constant. The third comes from the shielding effect of the bubbles growing on the electrode surface. This contribution is a function of 0. A possible ansatz for R(9) is (see also Fig. 3.11 and the corresponding discussion) ... 

Note that, in this description, the shadowing of the surface by the bubbles in the adherence region was not considered. With increasing bubble coverage fraction 6, the resistance in the diffusion region ff will also increase. A possible ansatz is to write (3.44) as ... 

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