Materials Scientist at CNRS INC-Section15 (France)
LRCS laboratoryRS2E network (Amiens)

My research topics focus on the development of new methods using Operando liquid-electrochemical TEM and X-ray synchrotron nano/µ-Computed Tomography to monitor electrochemical reactions and their impact on morphological & structural properties for studying new generations of batteries.

 

Image treatments using convolutional neural network, which are essential for statistical approach of big data, is also developed in my team to process 3D tomographic and dynamical dataset.

- RS2E Microscopy Platform Manager

- Animator of the LRCS transverse theme "Development of techniques and methodologies in situ & operando in Imaging and Diffraction"

Arnaud_Demortiere_2020_02.jpg

August 2020

This work demonstrates that the impedance spectra simulated from 3D microstructures may deviate from the conventional behavior simulated by a TLM or Newman’s P2D model in one of two scenarios: either the control volume is not large enough to be representative of the material, or the system is not conventionally homogeneous, e.g., the accessible interfacial area varies significantly with depth. As well as a qualitative comparison, it is possible to conceive of various metrics that could be used to quantify the degree of agreement between simulated EIS spectrum of the symmetric cell and TLM fit, thus providing a direct way to assess the degree to which porous electrode theory applies to a particular electrode microstructure. All of these concepts are to be applied to real electrode microstructural data in a follow-up study exploring optimal electrode design.

Operando Liquid-Electrochemical TEM

Operando X-ray Computed Tomography

Artificial Neural Network

Arnaud_Demortiere_2020_01.jpg

March 2020

We here report for the first time the characterization of Li−O2 battery cathodes by 3D tomography, allowing us to distinguish and localize Li2O2 from carbon material and pores. Such characterization, which coupled X-ray nano-CT with in- line Zernike phase contrast, was carried out on a few cathodes discharged independently until there are different depths of discharge. First and foremost, we demonstrated the feasibility of this technique theoretically onto the cathode of the Li−O2 system. In practice, at 8 keV this technique provides a high resolution (nm), contrast, and a large field of view (50 μm). Throughout the present paper, the X-ray Zernike phase contrast nanotomography for Li−O2 battery provides intuitive visualizations and valuable quantitative information. We successfully retrieved the pore size distribution and inter- connectivity in different cathode electrodes. The surface passivation has also been analyzed. In the studied material, the analysis shows a heterogeneous spatial distribution and inefficient occupation of Li2O2, probably due to the highly tortuous electrode and low diffusivity of oxygen. In addition, future work with this technique should be extended to other parts of the battery, such as a lithium anode, or a separator for investigating transport properties. Last but not least, the nondestructive property and nonvacuum requirement of this technique turn out to be robust for the development of the operando experiment. The investigation of the Li−O2 cathode kinetics should be carried out in future work.

© 2018 par Arnaud Demortière. Créé avec Wix.com

This site was designed with the
.com
website builder. Create your website today.
Start Now