Electron Beam-Induced Effects on a Ni-Rich Layered Cathode Material: A Comprehensive Investigation Using STEM and EELS

Abstract

Scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) are commonly used to study the structural properties of lithium-ion battery electrode materials. However, electron beam damage poses a challenge to the interpretation of data in electron beam-sensitive materials. In this study, we investigated electron beam effects on the cathode material Li1.05Ni0.88Co0.08Mn0.04O2 (Ni-rich NCM) by varying the electron probe currents. Using a low electron probe current of 5 pA (equivalent to an electron dose of 4 x 10(5) e(-)/& Aring;(2)), no significant changes were detected in the STEM images or EELS spectra. In contrast, at higher currents above 70 pA (electron dose: 6 x 10(6) e(-)/& Aring;(2)), significant sputtering damage was observed, along with changes in the O K-edge and Ni L-edge structures. These electron beam effects, such as sputtering damage and phase transition, occur under the moderate electron probe beam condition (similar to 10(6) e(-)/& Aring;(2)) near the surface of the Ni-rich NCM. This study establishes a crucial experimental framework for investigating radiation-sensitive materials while emphasizing the importance of the radiation-induced effects in energy materials.