Energy dispersive X-ray diffraction (EDXRD) for operando materials characterization within batteries

This perspective article describes the use of energy dispersive X-ray diffraction (EDXRD) to study the evolution of electrochemical energy storage materials. Using a synchrotron light source, EDXRD allows crystallographic changes in materials to be tracked from deep within large specimens, due to the use of highly penetrating X-rays and the ability to define a well-controlled diffraction gauge volume in space. Herein we provide an overview of battery work performed using the EDXRD technique, as developed at beamline X17B1 at the National Synchrotron Light Source (NSLS),6, and continued at beamline 6BM-A at the Advanced Photon Source (APS) and beamline I12 at the Diamond Light Source. The High Energy Engineering (HEX) beamline currently under construction at the National Synchrotron Light Source II (NSLS-II) by Brookhaven National Lab and the state of New York will further expand capability for and access to this technique. The article begins with a general introduction to the technique of EDXRD, including a description of the photon energy and d-spacing relationship and a discussion of the gauge volume. The primary topic of the review, battery characterization by EDXRD, includes discussion of batteries of differing materials chemistries (lithium-based batteries and aqueous batteries) which store energy by different mechanisms (insertion and conversion materials). A discussion of high temperature batteries is also included.