Deformed ButlerVolmer Models for Convex Semilogarithmic CurrentOverpotential Profiles of Liion Batteries
Abstract
The ButlerVolmer (BV) equation links the current flux crossing an electrochemical interface to the electric potential drop across it with the assumption of Arrhenius kinetics and the Boltzmann factor. Applying the semilogarithmic Tafel analysis in which the logarithm of current is plotted vs. the overpotential one expects straight lines from which the fundamental reaction rate of the kinetic process can be computed. However, some Liion battery data, which is the focus here, show nonlinear convex profiles that cannot be adequately fitted with the standard BV model. We propose instead two deformed BV models for the analysis of such types of behaviors constructed from the superposition of cells exhibiting only local equilibrium and thus giving rise to the powerlaw $q$exponential and $\kappa$exponential functions. NonBoltzmann distributions have been successfully employed for the modeling of a wide spectrum of physical systems in nonequilibrium situations, but not yet for batteries. We verify the validity of the deformed BV models on experimental data obtained from \ce{LiFePO4} and \ce{Li}\ce{O2} batteries.
 Publication:

arXiv eprints
 Pub Date:
 January 2022
 arXiv:
 arXiv:2201.03282
 Bibcode:
 2022arXiv220103282A
 Keywords:

 Physics  Applied Physics;
 Condensed Matter  Statistical Mechanics;
 Physics  Chemical Physics
 EPrint:
 25 pages, 5 figures