Small and Wide Angle Scattering for Nanostructured Group-IV Materials in LiB

Abstract

The development of the Li-ion technologies has widely enabled the broad range of portable electronic devices seen everyday around us. Furthermore, these technologies are expected to play a significant role in the oncoming shift from internal combustion engine to electrical vehicles. Yet, many challenges still need to be addressed to improve the energy density, cyclability, cost or safety.
Group IV elements (C, Si, Ge, Sn) are interesting anode materials, and indeed graphite has been the anode material of choice for the past three decades, even though silicon (and to a lesser extent germanium and tin) offers a much larger theoretical specific capacity. The main limitation for the latter is a lithiation mechanism much different than from graphite. In graphite, lithium atoms reversibly intercalate in the galleries between the graphene sheets, with moderate volume changes (ca. 10%). In the other group IV elements, Li forms an amorphous or crystalline alloy with the host material, resulting in dramatic volume changes at the highest Li content (ca. 300% for Si). This translates in large strain in the anode materials, which, in fine, lead to electrode pulverization, exposing new surfaces and using up Li in newly-formed solid-electrolyte interphase, or disconnecting particles from the current collector.
The nanostructuration of Si or Ge particles as anode materials has been proposed as a way to circumvent this issue. A large number of designs have been proposed, using nanoparticles or nanowires, coatings or even hierarchical designs inspired by egg yolk or pomegranate. It is expected that high density electrodes will rely on composite systems, based on the combination of “robust” graphite and high-capacity Si or Ge-based nanoparticles, with the possible addition of stabilizing phases.
In order to test these new designs and validate the electrochemical models based on them, it appears necessary to develop the experimental techniques that can probe both the nanostructured, usually amorphous Si or Ge component, and the crystalline graphite part, in real time and real operation condition. Operando small and wide angle X-ray scattering (SAXS-WAXS) is the tool of choice to achieve this goal. SAXS is sensitive to changes at the nanoscale and offers insights in the volume changes in nanoparticles, while WAXS is sensitive to the atomic order and is well-suited to probe the lithiation state of graphite. Recent technological development have even offered the possibility to measure both at the same time on a synchrotron beamline, at an energy compatible with a standard electrochemical pouch cell design. In this talk, we will discuss how operando SAXS-WAXS helped unravel the lithiation mechanisms at play in advanced electrode materials, and the key role it may play in the future in the field.


References

1. Samuel Tardif, Nicolas Dufour, Jean-Francois Colin, Gerard Gebel, Manfred Burghammer, Andreas Johannes, Sandrine Lyonnard, Marion Chandesris, J. Mater. Chem. A 2021, 9, 4281-4290.
2. Christopher L Berhaut, Diana Zapata Dominguez, Praveen Kumar, Pierre-Henri Jouneau, Willy Porcher, David Aradilla, Samuel Tardif, Stéphanie Pouget, Sandrine Lyonnard ACS Nano 2019, 13, 11538-11551.
3. Samuel Tardif, Ekaterina Pavlenko, Lucille Quazuguel, Maxime Boniface, Manuel Maréchal, Jean-Sébastien Micha, Laurent Gonon, Vincent Mareau, Gérard Gebel, Pascale Bayle-Guillemaud, François Rieutord, Sandrine Lyonnard ACS Nano 2017, 11, 11306-11316.


Biography

Prof. Samuel Tardif received his Ph.D. in Nanophysics from the University Joseph Fourier, Grenoble in 2011, followed by work as a postdoctoral fellow successively at the SPring-8 and European Synchrotron Radiation Facility (ESRF) synchrotrons. Since then, he is a researcher at the Interdisciplinary Research Institute in Grenoble (CEA), working also on the French beamline “InterFace” (BM32) at the ESRF. His expertise is in the development of synchrotron radiation experiments based on X-ray diffraction to study crystalline phases and mechanical strain, including in operando conditions. Currently, Prof. Tardif is affiliated with Université Grenoble Alpes as well as leads a Nanostructures and Synchrotron Radiation group in the large-scale facility at CEA/DRF/IRIG/DEPHY/MEM/NRS for operando study of electrochemical devices.