The Apparent Capacitance of the Electrode “Charging” Process

We investigate simple models of the electrode charging (discharging) at constant current i, where the potential (E) is recorded as a function of time, or charge, q = i ? t . Our goal is to assess the advantages of a representation in terms of capacitance,C = dq / dE ,vs. E. Such a plot is related with cyclic voltammetry (c.v.) plot (ic.v. vs E) at a constant rate (? = dE / dt)since, under appropriate circumstances, we should have C = ic.v. / ? = dq / dE . We will discuss the following items: a) origins and suppression of the singularities in the capacitance plots, b) effects of the finite charging currents, c) comparison between c.v. and electrode charging experiments.