An Analysis of the Chemical Stress Field Under Potentiostatic Intermittent Titration Techniques for Interfacial Reaction-Controlled Systems

The potentiostatic intermittent titration technique (PITT) is widely used to determine the diffusion coefficient of ions in electrode materials for rechargeable batteries such as lithium-ion or sodium-ion batteries, predicated on the assumption that the insertion/extraction of ions in the host materials is governed by diffusion. However, in practical scenarios, the electrochemical process might be dominated by interfacial reaction kinetics rather than diffusion. The present work derives analytical equations for electric current by considering the finite interfacial reaction kinetics and small overpotentials during PITT measurements and further studies the chemical stress field induced by the interfacial reaction-controlled ion insertion. The exchange current density (\({j}_{0}\)) can be ascertained using the analytical equation, which dictates the magnitude and decay rate of the electric current during a PITT process. The electric current decays more rapidly, and consequently, the lithium concentration reaches equilibrium faster for larger values of \({j}_{0}\). The magnitude of the chemical stress is independent of \({j}_{0}\) but depends on the overpotential.