2D and 3D chemical imaging of Li-ion battery electrodes at nanoscale resolution

Abstract

A new chemical imaging technique, 3D XANES microscopy, combines the high resolution and large field of view (FOV) of full-field transmission X-ray microscopy (TXM) with the chemical speciation capabilities of X-ray absorption near edge structure (XANES) to visualize the sample’s chemistry in 2D and 3D. This technique is a powerful method to examine the relationship between morphology and chemical speciation in complex materials with hierarchical structure such as battery electrodes. 3D XANES TXM offers chemical speciation at the nanoscale in thick samples (up to 30 µm) with minimal preparation requirements. Further, because it is not a scanning technique, its high throughput allows the analysis of large areas in minutes to a few hours. Using the TXM on beam line 6-2 at the Stanford Synchrotron Radiation Lightsource (SSRL), which is capable of imaging from 4.5 to 14 keV with down to 30 nm resolution and up to 30 micron FOV, the 3D XANES microscopic technique has been used to construct chemical maps of various composite systems in 2D and 3D. Concepts of technique and data processing which involves the evaluation of up to 1 Million XANES spectra for a single 2D map will be discussed and results from XANES microscopy of Li-ion battery electrodes and other materials will be presented