Combining operando X-ray experiments and modelling to understand the heterogeneous lithiation of graphite electrodes

Abstract

Experimental measurement of lithium distribution across the depth of a thick porous graphite electrode using operando microXRD and numerical modelling provide an unprecedented view of the lithiation of graphite.

Strategies for the Analysis of Graphite Electrode Function

“…In a recent study by Tardif et al, the authors carried out an operando microfocused synchrotron X-ray diffraction experiment to obtain a spatially resolved microscale quantification of the lithiated graphite intercalation compounds formed across the electrode during delithiation. [62] The microdiffraction experimental setup is illustrated in Figure 9a, and the measurements were conducted on a half-cell consisting of an 80 µm thick graphite electrode, two 25 µm microporous Celgard 2500 separators, and a 250 µm metal lithium foil. Figure 9b shows the depth distribution (z-direction) within the cell of the different lithiated graphite intercalation compounds as function of time during delithiation determined from the variation in the observed scattering intensities at specific Q-ranges corresponding to characteristic Bragg reflections of the individual phases.…”

“…The five profiles shown correspond to reduced electrode depths of 0 (separator/electrode), 0.25, 0.5, 0.75, and 1 (electrode/current collector). Reproduced with permission [62]. Copyright 2021, Royal Society of Chemistry.…”

Accelerating Battery Characterization Using Neutron and Synchrotron Techniques: Toward a Multi‐Modal and Multi‐Scale Standardized Experimental Workflow

“…Synchrotron techniques ( Figure 2 ) can provide time‐resolved data with high spatial resolutions, chemical sensitivity, 2D/3D spatially resolved structural maps, and volume reconstructions. X‐ray diffraction (XRD), [ 25 ] absorption spectroscopy (XAS), [ 26 ] photoelectron spectroscopy (XPS), [ 27 ] and tomography (XRT) [ 28 ] have proven to be amongst the workhorse characterization techniques for battery materials and devices, while small angle X‐ray scattering (SAXS), [ 29 ] resonant inelastic X‐ray scattering (RIXS), [ 30 ] scanning transmission X‐ray microscopy (STXM), [ 31 ] X‐rays reflectivity (XRR), [ 32 ] and X‐ray Raman scattering (XRS) [ 33 ] have recently been added to the battery researcher's toolbox and as such have yet to provide their full potential. Spatially resolved techniques, including ultimate nanoscale resolution X‐ray tomography, [ 34 ] are nowadays becoming increasingly popular.…”

“…Spatially resolved operando diffraction experiments are crucial to studying structural evolutions such as homogeneity and phase distribution in battery electrodes during operation,for example, phase redistribution in zinc–air batteries, [ 62 ] lithiation heterogeneities in graphite, [ 25 ] and silicon‐graphite, [ 63 ] long‐term cycling stability of high voltage spinel cathode versus graphite, [ 48,64 ] degradation mechanisms in Li–S batteries up to 35 cycles, [ 65 ] or NPD mappings. [ 66,67 ] Computed tomography (CT) methods are able to describe the macrostructure, interconnectivity, and electronic percolation in the electrodes with a spatial resolution from <100 nm to several micrometers.…”

“…Microdiffraction cell from CEA/ESRF cell, reproduced with permission. [ 25 ] Copyright 2021, Royal Society of Chemistry. Imaging cell from ESRF/Mateis, reproduced with permission.…”