Accurate determination of reaction rate constants for lithium-ion batteries by characteristic time-decomposed overpotential

Abstract

The reaction rate constant is a crucial kinetic parameter that governs the charge and discharge performance of batteries, particularly in high-rate and thick-electrode applications. However, conventional estimation or fitting methods often overestimate the charge transfer overpotential, leading to substantial errors in reaction rate constant measurements. These inaccuracies hinder the accurate prediction of voltage profiles and overall cell performance. In this study, we propose the characteristic time-decomposed overpotential (CTDO) method, which employs a single-layer particle electrode (SLPE) structure to eliminate interference overpotentials. By leveraging the distribution of relaxation times (DRT), our method effectively isolates the characteristic time of the charge transfer process, enabling a more precise determination of the reaction rate constant. Simulation results indicate that our approach reduces measurement errors to below 2%, closely aligning with theoretical values. Furthermore, experimental validation demonstrates an 80% reduction in error compared to the conventional galvanostatic intermittent titration technique (GITT) method. Overall, this study provides a novel voltage-based approach for determining the reaction rate constant, enhancing the applicability of theoretical analysis in electrode structural design and facilitating rapid battery optimization.