Development of Measurement/Analysis Techniques to Bridge Microscopic and Macroscopic Electrochemical Phenomena in Energy Storage Devices

Abstract

The design of high-performance electrochemical devices requires a profound understanding of the mechanisms governing the electrochemical reactions within the device, ranging from microscopic one involving atoms and molecules to macroscopic one observed in cells/stacks of practical devices. While extensive efforts have been made to understand the microscopic and macroscopic electrochemical phenomena in these devices, understanding the interplay between micro- and macro-scale electrochemical phenomena has not necessarily been sufficient. One reason is that what connects the macroscopic and microscopic electrochemical phenomena is a complex electrochemical phenomenon involving the collective behavior of a large population of particles within an electrode under the influence of external fields such as stress. This comprehensive paper presents the research conducted by the authors to develop novel techniques for understanding the intricate electrochemical phenomena that bridge the micro and macro scales. The first part of this paper presents our work on the development of a technique to perform three-dimensional operando observation of heterogeneous electrochemical reactions occurring in a particle ensemble within solid state battery electrodes using computed-tomography with X-ray absorption near edge structure spectroscopy (CT-XANES). The latter part focuses on the development of a method to quantitatively evaluate stress-induced modulation of material properties of battery electrode materials (chemo-mechanical coupling phenomena).

Keywords

• heterogeneous electrochemical reactions
• ct-xanes
• chemo-mechanical coupling
• solid state batteries