Autocatalytic solid-state electrochemical reactions: a non-linear kinetic theory of batteries

Abstract

Autocatalysis is a nonlinear dynamic phenomenon that is believed to be involved in many natural phenomena. Herein, a mesoscopic kinetic model of solid-state electrochemical reactions based on autocatalysis is introduced, and two examples that are important for batteries, i.e., the Ni(OH)₂/NiOOH and Mn²⁺/MnO₂ systems, are presented. This model considers only interactions between the product and the reactant as phase transition takes place during galvanostatic, potentiostatic, or voltammetric charge–discharge. The kinetic theory presented here explains the recently observed charge–discharge asymmetry in phase-separating battery reactions (a possible source of hysteresis), the memory effect of the first cycle on subsequent cycles, and finally it shows that phase separation may be prevented at high charge–discharge rates.