In Situ and Operando X-Ray Characterization of Battery Materials

Abstract

Synchrotron-based X-rays are a powerful characterization tool that can probe across many relevant length scales (from atomistic to millimeter) with different techniques that are sensitive to distinct features such as microstructure, chemistry, and morphology. Because of the high flux available and penetrating power of synchrotron-based X-rays, batteries can be probed under realistic ( operando ) conditions, which enables us to understand and overcome failure mechanisms of the next generation of battery materials. At the Stanford Synchrotron Radiation Lightsource at SLAC National Accelerator Laboratory, we have a suite of advanced X-ray characterization tools and have enabled a robust means of multimodal, operando characterization using a standard pouch cell geometry. With transmission X-ray microscopy (TXM), we capture morphology changes on either the cathode or anode during battery operation. Combined with absorption spectroscopy, the TXM provides maps of the local state of charge of active material particles. With high speed X-ray diffraction and X-ray absorption spectroscopy, we track the changes in crystallographic phases, local coordination, and chemistry both during battery operation or during material synthesis. Results from these techniques can be combined together to get a more complete picture of the key degradation pathways of active battery materials to develop mitigation strategies for longer lasting energy storage. Alternatively, by mapping out the crystalline and amorphous structures within synthetic pathways, we can understand how to guide a synthesis to the desired final product and achieve the product with lower energy and/or with less time.