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PhD subjects

5 sujets IRAMIS

Dernière mise à jour : 18-12-2018


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• Physical chemistry and electrochemistry

 

Analysis and modeling the evolution of new active materials during the first charge-discharge cycles of a Li-Ion battery

SL-DRF-19-0490

Research field : Physical chemistry and electrochemistry
Location :

Service Nanosciences et Innovation pour les Materiaux, la Biomédecine et l'Energie

Laboratoire Edifices Nanométriques

Saclay

Contact :

Benoit MATHIEU

Nathalie HERLIN

Starting date : 01-10-2018

Contact :

Benoit MATHIEU

CEA - DRT/LITEN/DEHT/LMP

04 38 78 18 44

Thesis supervisor :

Nathalie HERLIN

CEA - DRF/IRAMIS/NIMBE/LEDNA

0169083684

Personal web page : http://iramis.cea.fr/nimbe/Phocea/Membres/Annuaire/index.php?uid=herlin

Laboratory link : http://iramis-i.cea.fr/nimbe/ledna/

More : https://www.researchgate.net/profile/Benoit_Mathieu

Facing the energy transition, the storage of energy is a major issue. However, it appears necessary to increase the battery storage capacity and one way could be the use of silicon in addition to graphite for the negative electrode of Li-ion accumulators. The development of accumulators based on these materials is however slowed by their instability, related to the swelling of silicon during the insertion of lithium. Thus, the understanding of the phenomena occurring during the first cycles of operation appear fundamental to master the operation over the long term.



This thesis project aims to understand and model the mechanical behavior of these new silicon-graphite electrodes. It is based on 3 teams: in Saclay, we will synthesize custom materials: silicon nanoparticles, silicon / germanium alloys, core @ shell where the shell will be carbon. Commercial silicon / graphite materials will also be used as reference. The behavior of materials will be studied in Grenoble using a laboratory diffractometer allowing in-situ and operando analyzes and large instruments such as ESRF or SOLEIL. These measurements will provide information on the stress inside the silicon but also on the state of lithiation of the graphite and will allow the modeling of the electrochemistry of the insertion of the lithium in the silicon, in particular the dependence in time of the hysteresis, still poorly understood. The aim of the thesis is to build a physics-based battery model allowing: "simple" experiments of swelling measurements, electrical cell performance measurements, early-life and model cycling and modelization, to deduce the mechanical and electrochemical behavior of cells at the scale of grains and agglomerates. This, in order to predict the aging of cells in the long term, in relation with their mechanical properties.

Multi-scale and conformation-resolved dynamics of the electronic relaxation in flexible molecules

SL-DRF-19-0512

Research field : Physical chemistry and electrochemistry
Location :

Service Laboratoire Interactions, Dynamique et Lasers

Saclay

Contact :

Lionel POISSON

Eric GLOAGUEN

Starting date : 01-10-2019

Contact :

Lionel POISSON

CNRS-UMR9222 - DSM/IRAMIS/LIDYL/DYR

01 69 08 51 61

Thesis supervisor :

Eric GLOAGUEN

CNRS - DSM/IRAMIS/LIDyL/SBM

01 69 08 35 82

Personal web page : http://iramis.cea.fr/Pisp/34/lionel.poisson.html

Laboratory link : http://iramis.cea.fr/LIDYL/index.php

More : http://iramis.cea.fr/Pisp/70/eric.gloaguen.html

Flexible molecules are ubiquitous in Nature (proteins, sugars, ...) and are at the origin of many applications (drugs, molecular machines, ...). By definition, these molecules exist in several conformations that each have physical, chemical or biological properties which can vary greatly from one conformation to another. Among these properties, photoexcitation and relaxation of the electronic states are particularly sensitive to conformation: for example, the lifetime of the first excited electronic state can vary with the conformation by several orders of magnitude. However, the experimental characterisation of such conformational effects on the excited states remains rare due to the difficulty to specifically study one conformation present in a conformational mixture. This thematic is still poorly documented despite i) a need for experimental results to help the development of theoretical models, and ii) a lack of knowledge in a field where fundamental (conical intersections, ultrafast phenomena) and application (photostability, energy transfer) issues are important.



In this context, the LIDYL laboratory brings together several experimental apparatus allowing an original multi-scale (ns-fs) and conformation-resolved study of the dynamics of the electronic relaxation in flexible molecular systems. The research program will focus on biologically-relevant systems and molecular complexes, and will target:



- the observation of conformer-dependent dynamic processes and their rationalisation.

- the characterization of species previously inaccessible to conventional detection techniques.

Investigation by electrochemical microscopy of the multiphase transport within composite materials of a PEMFC

SL-DRF-19-0493

Research field : Physical chemistry and electrochemistry
Location :

Service Nanosciences et Innovation pour les Materiaux, la Biomédecine et l'Energie

Laboratoire Innovation, Chimie des Surfaces Et Nanosciences

Saclay

Contact :

Renaud CORNUT

Bruno JOUSSELME

Starting date : 01-09-2019

Contact :

Renaud CORNUT

CEA - DRF/IRAMIS/NIMBE/LICSEN

01 69 08 91 91

Thesis supervisor :

Bruno JOUSSELME

CEA - DRF/IRAMIS/NIMBE/LICSEN

0169 08 91 91

Personal web page : http://iramis.cea.fr/Pisp/renaud.cornut/

Laboratory link : http://iramis.cea.fr/nimbe/licsen/

The emergence of hydrogen as an energy vector must help to stop pollution issued from the use of carbon-based energy sources in transport. In vehicles the conversion to electricity is achieved with proton exchange membrane fuel cells.



The aim of the project is to make them compatible with mass market by providing competitive cathodes containing inexpensive catalytic nano-objects. A huge diversity of starting materials, combinations of materials and processing conditions are possible, and identifying the optimal strategy at each step is presently very challenging. To manage this, we first set up an electroanalytical platform to evaluate in routine the effective electrochemical properties of multifunctional materials used in fuel cells. We then produce many different materials in a combinatorial fashion, the analysis of which permits to understand the way nano-objects assemble into electrocatalytic materials. From this, we rationalize the different processing steps and optimize the performances, with special care to the ageing of the materials.

Investigating metal-oxygen batteries using in situ solid-state NMR spectroscopy

SL-DRF-19-0495

Research field : Physical chemistry and electrochemistry
Location :

Service Nanosciences et Innovation pour les Materiaux, la Biomédecine et l'Energie

Laboratoire Structure et Dynamique par Résonance Magnétique (LCF)

Saclay

Contact :

Alan WONG

Starting date : 01-10-2019

Contact :

Alan WONG

CNRS - DRF/IRAMIS/NIMBE/LSDRM

+33 1 69 08 41 05

Thesis supervisor :

Alan WONG

CNRS - DRF/IRAMIS/NIMBE/LSDRM

+33 1 69 08 41 05

Personal web page : http://iramis.cea.fr/Pisp/alan.wong/

Laboratory link : http://iramis.cea.fr/nimbe/lsdrm/index.php

More : http://iramis.cea.fr/nimbe/Pisp/magali.gauthier/

Rechargeable metal-O2 batteries have attracted much attention in recent years as a possible alternative to the widely used lithium-ion batteries. This is particularly the case for lithium and sodium-oxygen batteries, due to their potential high energy densit. However, great challenges remain in the development of M-O2 batteries and in the understanding of the underlying mechanisms taking placed inside M-O2 batteries. Clear identifications of the discharge electrochemical pathways and their products (MO2 or M2O2), as well as the reactivity of the electrolyte, are crucial. The thesis objective is to investigate the electrochemical and chemical reactions in M-O2 batteries under real-time potential cycling using recently emerged in situ solid-state NMR spectroscopy. The thesis will consist of (1) optimizing the recently developed in situ solid-state NMR facility at LSDRM for studying metal-O2 batteries; (2) understanding reaction mechanisms in M-O2 systems; and (3) exploring new routes for improving the battery performance at LEEL.

Photocatalytic nanohybrids in microfluidic chips for the recycling of carbon dioxide

SL-DRF-19-0507

Research field : Physical chemistry and electrochemistry
Location :

Service Nanosciences et Innovation pour les Materiaux, la Biomédecine et l'Energie

Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire

Saclay

Contact :

Florent Malloggi

Eric DORIS

Starting date : 01-09-2019

Contact :

Florent Malloggi

CEA - DSM/IRAMIS/NIMBE/LIONS

33.(0)1.69.08.23.55

Thesis supervisor :

Eric DORIS

CEA - DRF/JOLIOT/SCBM/LMT / Tritium

+33-169 08 80 71

Personal web page : http://iramis.cea.fr/Pisp/florent.malloggi/

Laboratory link : http://iramis.cea.fr/nimbe/lions/

Our fossil fuel based society is facing two major and interconnected problems:

i) the progressive depletion of fossil fuels, and

ii) the impact of their combustion on air pollution and global warming caused by large-scale emission of carbon dioxide (CO2).



To avoid the obvious consequences on climate changes, the concentration of such a greenhouse gas in the atmosphere must be stabilized but, as populations grow and economies develop, there is an increasing demand of fossil fuels from developing countries. The photocatalytic reduction of CO2 is considered as a highly promising strategy for the production of hydrocarbon fuels while simultaneously resolving energy crisis and greenhouse effect.



The goal of this project is to address the principles of an integrated H2O oxidation/CO2 reduction cycle, for efficient solar energy storage, and environment remediation. The ultimate target is to drive CO2 photo-reduction to liquid fuels such as methanol, methane or light hydrocarbons while using H2O as the primary, carbon-free, renewable source of reducing equivalents (e.g. electrons). This strategy goes beyond artificial photosynthesis by solar-powered water splitting yielding molecular H2. Instead, this project looks at the direct reduction of anthropo-genically produced CO2 to yield conventional hydrocarbon fuels by a renewable photocatalytic cycle.

 

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