In a previous publication I have introduced the interaction function Λ in the form of a potential law (Eq. 13a) which exhibits several desirable features as it can describe infinitely high coverages while growing very slowly. At small overpotentials one should be able to use a Langmuir isotherm (see also Fig. ), which can be a good approximation for fast pseudocapacitive processes such as the H-upd, but the details of its mathematics are beyond the scope of this work. Using the potential law, combined with previous expressions one obtains the implicit Eq. 13b.