Determination of kinetic parameters from a new quadratic approximation of the Butler-Volmer equation
Zoltán Lukács, Tamás Kristóf
Abstract
The determination of the parameters of the Butler-Volmer equation is a typical nonlinear parameter fitting task. Linear approximations are feasible at high and very low polarizations. However, in both cases the intermediate (transition) potential range, carrying probably the most valuable information on the exchange or corrosion current of an electrochemical system, remains out of scope. The linearization of the Butler-Volmer equation in this intermediate potential range, enabling the determination of both the polarization resistance and the Tafel slopes, can provide a powerful evaluation tool in electrochemical kinetic studies. A simple, robust and accurate method to meet this challenge is proposed, linear in the Tafel slopes and quadratic in the polarization, providing all practical advantages of the linearized systems. The performance of the new model is tested on simulated and experimental data.