Unveiling structural artifacts in in situ XRD analysis: Decoupling electron/ion transport pathways to mitigate localized electrochemical dead zones

Abstract

In situ X-ray diffraction (XRD) has been widely employed to probe the structural evolution of lithium-ion battery electrodes. However, electrodes with practically relevant high-energy densities often exhibit pronounced electrochemical inhomogeneities, which substantially hinder accurate structural interpretation. In this study, we systematically investigate the origin and characteristics of localized electrochemical dead zones (LEDZs) observed during in situ XRD measurements. Through comprehensive analyses using modified coin cells and pouch cells containing various cathode materials under diverse electrochemical conditions, we identify insufficient electron and ion conductivity as the primary cause of LEDZ formation. Crucially, our results demonstrate that decoupling electron and ion transport pathways from the X-ray beam direction-an effect inherently realized in pouch cell configurations-effectively mitigates LEDZs, thereby enabling artifact-free structural analysis. This work underscores the critical role of cell geometry and conductivity pathways in achieving accurate structural characterization, providing fundamental guidelines for the design and interpretation of high-energy-density lithium-ion battery electrodes. (c) 2025 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.