Combining operando synchrotron X-ray tomographic microscopy and scanning X-ray diffraction to study lithium ion batteries

Abstract

We present an operando study of a lithium ion battery combining scanning X-ray diffraction (SXRD) and synchrotron radiation X-ray tomographic microscopy (SRXTM) simultaneously for the first time. This combination of techniques facilitates the investigation of dynamic processes in lithium ion batteries containing amorphous and/or weakly attenuating active materials. While amorphous materials pose a challenge for diffraction techniques, weakly attenuating material systems pose a challenge for attenuation-contrast tomography. Furthermore, combining SXRD and SRXTM can be used to correlate processes occurring at the atomic level in the crystal lattices of the active materials with those at the scale of electrode microstructure. To demonstrate the benefits of this approach, we investigate a silicon powder electrode in lithium metal half-cell configuration. Combining SXRD and SRXTM, we are able to (i) quantify the dissolution of the metallic lithium electrode and the expansion of the silicon electrode, (ii) better understand the formation of the Li15Si4 phase, and (iii) non-invasively probe kinetic limitations within the silicon electrode. A simple model based on the 1D diffusion equation allows us to qualitatively understand the observed kinetics and demonstrates why high-capacity electrodes are more prone to inhomogeneous lithiation reactions.

Quantifying microstructural dynamics and electrochemical activity of graphite and silicon-graphite lithium ion battery anodes

“…Our analysis leads to two observations: (i) lithiation starts at the electrode–separator interfaces and progresses towards the current collectors and (ii) SOC gradients build-up immediately in the delithiating electrode, while they develop only during the second half of the experiment in the lithiating electrode. The first observation is consistent with our understanding from literature that lithiation kinetics within graphite electrodes are limited by ionic diffusion and conductivity rather than by electric conductivity 11 26 37 . The second observation can be understood by plotting the first electrochemical cycle of a lithium metal/graphite half cell that has been slowly operated at a galvanostatic C/10 rate ( Fig.…”

“…Synchrotron-based X-ray tomographic microscopy (XTM) has received widespread attention in the field of LIBs as it allows for non-invasive imaging of electrode microstructures with high spatial and temporal resolution. This technique has been used for ex-situ microstructure and morphological studies of pristine and cycled electrodes 3 4 5 6 7 8 9 10 , as well as to track battery materials and electrodes during electrochemical cycling in-situ or in-operando 2 11 12 13 14 15 .…”

In Situ Probing Multiple‐Scale Structures of Energy Materials for Li‐Ion Batteries

“…e) Sketch of electrochemical cell housing designed for in situ X‐ray tomographic microscopy experiment. Reproduced under the terms of the CC‐BY Creative Commons Attribution 4.0 International License . Copyright 2016, the Authors.…”

Experimental and Modeling Analysis of Graphite Electrodes with Various Thicknesses and Porosities for High-Energy-Density Li-Ion Batteries

“…15 Beside studies based on electrochemical techniques, imaging techniques of operando and in-situ cells were developed and allow to provide additional information on local state of charge (SoC) and salt concentration gradient across the cell. [16][17][18][19][20][21][22][23] However, the analysis turns out to be tedious when screening a large panel of electrode designs.Mathematical models represent a relevant alternative over experimental time-consuming methods. LIB models are a fast, low-cost and accurate tool to perform electrode design optimization.…”