Decoupled measurement and modeling of interface reaction kinetics of ion-intercalation battery electrodes

TL;DR

This paper introduces a decoupled measurement method and a new interface ion-intercalation model to better understand and predict the ultrahigh rate performance of lithium-ion battery electrodes, overcoming limitations of traditional kinetics models.

Contribution

It develops a novel time-resolved potential measurement technique and an improved kinetic model that accurately describe interface reactions during ultrahigh-rate charging and discharging.

Findings

Classical Butler-Volmer equation deviates at ultrahigh C-rates.

The new model accurately predicts charge/discharge behavior.

Kinetic limitations from particles to electrodes are systematically revealed.

Abstract

Ultrahigh rate performance of active particles used in lithium-ion battery electrodes has been revealed by single-particle measurements, which indicates a huge potential for developing high-power batteries. However, the charging/discharging behaviors of single particles at ultrahigh C-rates can no longer be described by the traditional electrochemical kinetics in such ion-intercalation active materials. In the meantime, regular kinetic measuring methods meet a challenge due to the coupling of interface reaction and solid-state diffusion processes of active particles. Here, we decouple the reaction and diffusion kinetics via time-resolved potential measurements with an interval of 1 ms, revealing that the classical Butler-Volmer equation deviates from the actual relation between current density, overpotential, and Li+ concentration. An interface ion-intercalation model is developed which considers the excess driving force of Li+ (de)intercalation in the charge transfer reaction for ion-intercalation materials. Simulations demonstrate that the proposed model enables accurate prediction of charging/discharging at both single-particle and electrode scales for various active materials. The kinetic limitation processes from single particles to composite electrodes are systematically revealed, promoting rational designs of high-power batteries.