Spatially inhomogeneous delithiation in LiNiO2 positive electrode: the effect of X-rays dose

TL;DR

This paper introduces a method to correlate local X-ray dose with electrochemical activity in LiNiO2 electrodes, establishing dose limits for reliable operando measurements using full-field X-ray absorption spectroscopy.

Contribution

A novel approach linking X-ray dose to electrochemical changes, improving reliability of operando synchrotron X-ray techniques in battery research.

Findings

Identified a dose threshold for reliable measurements.

Demonstrated spatially resolved beam-induced effects.

Provided a diagnostic framework for operando experiments.

Abstract

Operando synchrotron X-ray techniques have become essential tools for investigating rechargeable batteries as they provide real-time insights into electrochemical processes. However, the high brilliance of synchrotron radiation can alter the electrochemical mechanisms within the battery, thereby compromising the reliability and reproducibility of operando measurements. In this study, we introduce a novel methodology that directly correlates the local X-ray dose with the Ni4+/Ni3+ redox activity in a LiNiO2 positive electrode. Full-field transmission X-ray absorption spectroscopy imaging (FFI-XAS) is employed to probe the charge-compensation mechanism during lithium extraction at the micrometre scale, using two beam configurations with different focal distances (far-focus and near-focus). While the spatially averaged XAS spectra exhibit sluggish reaction, regions exposed to lower dose rates exhibit the expected electrochemical evolution. This contrast enables the identification of a dose threshold for reliable operando measurements. This approach establishes a practical dose limit and provides spatially resolved insight into beam-induced effects, offering both a diagnostic framework and a pathway toward more reliable operando experiments.