Scientific direction Development of key enabling technologies
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PhD : selection by topics

Technological challenges >> Electrochemical energy storage incl. batteries for energy transition
12 proposition(s).

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Ecodesign methodology for new generations of batteries

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des Eco-procédés et EnVironnement

01-10-2020

SL-DRT-20-0535

elise.monnier@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

The development of the electrification of vehicles requires the design of cheaper and more efficient battery technologies. In response to this demand, many development paths are under study, such as new generations of Li-ion with reduced cobalt content or high energy density, all solid state lithium batteries or Li-Sulphur batteries, among other. Apart from the performance aspect, there is a real need to assess the environmental impact of these technologies over their entire life cycle (LCA), and to look at eco-design options for the development of the batteries of the future. The proposed thesis will aim at addressing these issues, using a multidisciplinary approach combining the skills of at least three laboratories from CEA LITEN. At the end of the thesis, the expected results will be: an environmental evaluation of the 3 new generation of battery technologies (advanced Li-Ion, Li-S and All-Solid), compared to reference battery technologies as well as an eco-design methodology to guide decision support in the development of low TRL battery technologies.

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Study of cathode materials for lithium-ion batteries by experimental and theoretical soft and hard X-ray photo-emission spectroscopy

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Nanocaractérisation et Nanosécurité

01-09-2020

SL-DRT-20-0722

anass.benayad@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

Photoemission spectroscopy (X-ray, XPS, or ultraviolet, UPS) is a direct probe of the electronic structure of materials and redox processes involved in batteries at the atomic scale. However, it is limited by the extreme surface sensitivity of the material's, with a typical photoelectron path length of a few nanometers to the energies usually available in the laboratory . In addition, spectrum interpretation requires the ability to accurately model this electronic structure, which is particularly delicate in the case of cathode materials that contain transition metals and are used in a wide range of lithium compositions. Indeed, the electronic structure of these materials has electronic correlation effects whose character depends in particular on the filling of the orbitals "d". In this thesis, we propose to use these limitations to our advantage to explore the electronic surface structure including the solid electrolyte interphase (SEI), and the core of the active cathode particle. To do this, we will take advantage of the first hard X-ray laboratory spectrometer in France (HAXPES), which will be installed at the NanoCharacterization Platform (NCPF) in spring 2020, and will probe materials up to about 20 nanometers , . The comparison between the XPS and HAXPES spectra, during battery operation (in operando) and/or post-mortem in the same area, will allow decoupling of the surface and core spectra for different chemical compositions and at different stages of the battery life cycle. The interpretation of the photo-emission spectra will be done by direct comparison with ab initio calculations combining density functional theory (DFT) with dynamic mean field theory (DMFT). This coupling will make it possible both to go beyond the usual techniques based on cluster models, which do not take into account metal shielding, and to validate the quality of theoretical predictions on the effects of electronic correlation (effective mass, potential transfer of spectral weight to Hubbard bands). The thesis will include an instrumental (in particular, calibration of effective surfaces on model systems) and theoretical (prediction of core photo-emission spectra based on DFT+DMFT calculations) development, then will compare the performance and ageing of different cathode materials (LiCoO2, NMC of different compositions) in combination with liquid and solid electrolytes and a Li metal anode. The candidate will be hosted in the L2N laboratories of the DTNM and LMP of the DEHT to conduct his work.

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Comparison of the safety of Li batteries with liquid electrolyte and solid state. Role of the different materials involved in the mechanisms of thermal runaway.

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Analyse électrochimique et Post mortem

01-09-2020

SL-DRT-20-0834

remi.vincent@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

Currently, the technology of all solid state batteries is very popular because it represents one of the credible ways to reach the 400Wh/Kg. By improving safety, this technology allows the integration of lithium metal and the most energetic cathode materials. Nevertheless, all-solid technologies are not totally inert. Thus, it has been demonstrate that the thermal runaway energy is equal to the sum of the energies of the chemical and electrochemical reactions contained in the cell. Based on this methodology, the thesis will identify the security potential of new all solid state technologies. For this, characterizations such as DSC, TGAMS and calorimetry will be implemented to identify the reactivity of the materials of a cell as well as their interactions (e.g. presence or absence of SEI). Based on these analyzes and the models developed at CEA, the PHD will propose a change of scale to predict the reaction kinetics of a cell and thus predict the state of safety of the technology before the realization of a real cell. This will bring elements for the emergence of a new technology.

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Study and Improvement of the formation step of next generation Li-Ion batteries

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Prototypage et Procédés Composants

01-10-2020

SL-DRT-20-0843

yvan.reynier@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

Electrical formation of Li-ion batteries is a little studied subject in academic circles, while it represents 30% of the cost of production of the cell and conditions its performance (life, resistance ...). Most studies remain empirical [1-5] or protected by industrial secrecy. The aim of the thesis is to establish a direct link between the parameters of the formation step and the resulting electrochemical performance, using a protocol coupling electrochemical measurements and physicochemical characterization. During his training, the student will develop the monitoring methodology and then determine the most influential parameters. Subsequently, he will apply these results to representative accumulators using design of experiment methodology to optimize the formation step.

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Consideration of the risk of propagation of thermal runaway in the development of battery modules. Experimental approach and modeling tool taking into account gas generation.

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Analyse électrochimique et Post mortem

01-09-2020

SL-DRT-20-0846

remi.vincent@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

The PHD proposes to study the propagation of thermal runaway in a battery module. The different modes of heat transfer (radiation, conduction and convection) will be quantified and their impacts for the module design will be evaluated. For example, the energy shares released in the gases or the cell will be determined, as well as the probabilities of tearing the bucket and the impact of the thermal conductivity of the foils and welds. This study will deal with the realization of abusive tests on mini-module as well as with a modelization of CFD type (Start CCM + software). Both approaches will feed each other to obtain a predictive model of runaway. The first step will consist in validating that the simulation reproduces well the predominant phenomena to, in a second time, propose optimizations which will be validated in their turn by the experiment. Finally, the thesis will propose in addition to a fine evaluation of the main parameters in the propagation of the thermal runaway, innovative module designs with mitigation solutions specially adapted according to the cells and the targeted application.

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Modeling phase transitions in LIB active materials

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Modélisation multi-échelle et suivi Performance

01-09-2020

SL-DRT-20-0851

marion.chandesris@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

For Generation 3 lithium-ion batteries (LIB), the materials have reached a fair maturity level and current challenges focus on optimization of these technologies under various and most of the case antagonist constraints. Modeling and simulation numerical tools allow to tackle these optimization questions but suffer from a low knowledge of active materials physical and electrochemical properties. The aim of this thesis is to investigate the link between the crystallographic structures of LIB active materials and their thermodynamic properties at and out of equilibrium. In particular, this thesis work aims at modeling and simulating phase transitions occurring during lithium insertion in lamellar active materials (graphite at the negative and alloy of transition metal oxide at the positive) to understand (i) staging phenomena, which corresponds to periodic ordering of lithium and (ii) shift in the planes of the host materials. Progress in our understanding of these two phenomena and their coupling should bring a better comprehension of the main physical properties of a large majority of lamellar active materials.

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Reversible hydrogen storage material based on amine metal borohydrides: Synthesis and Regneration of spent fuel for a circular economy

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des Eco-procédés et EnVironnement

01-09-2020

SL-DRT-20-0860

philippe.capron@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

Hydrogen is considered as the energy carrier of tomorrow. However, in addition to the fact that the production and distribution chain is not yet operational, there are real scientific, technological and economic barriers to its storage for mobile or stationary applications. Although there are currently storage solutions in compressed or chemisorbed form in metal hydrides, the performance and associated costs of these solutions only partially fulfil the specifications of the various applications. Ammoniates of metal borohydrides have shown great promise as a higher capacity next generation chemical hydrogen storage medium. CEA/LITEN has developed several M-B-N-H systems that deliver more than 10 wt% practical hydrogen capacity below 250°C. Our novel and scalable synthesis approach for these materials allowed in-depth understanding of dehydrogenation process. The remaining challenge is the development of chemical rehydrogenation routes for the spent fuel (partially hydrogenated boron nitride) with high yield. Based on our preliminary investigation, the proposed thesis project will focus on the microwave-assisted digestion of boron nitride with anhydrous hydrochloric acid followed by hydrodechlorination process enabled via a catalyst-solvent mixture. Obtained diborane and ammonia products can become the synthesis precursors enabling the full recyclability. On the other hand, the development and optimization of these rehydrogenation processes will require chemical and structural analysis in order to understand and improve the role of hydrogenation catalyst-solvent mixture. In this context, in-operando experiments using large instruments will be conducted in collaboration with INAC.

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Study of heterogeneous damage in Li-ion batteries related to cell design and development of associate ageing model at cell level

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Analyse électrochimique et Post mortem

01-10-2020

SL-DRT-20-0867

olivier.raccurt@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

This thesis topic focuses on the study of Li-ion cell ageing and in particular on the impact of the internal architecture of the cell on the generation of localised degradation. Although Li-ion technology is undergoing strong development, cell formats are not standardized. A wide variety of designs are currently available on market (cylindrical, prismatic or laminate) with capacities ranging from a few Ah to several tens of Ah and a variety of assembly modes (winding, stacking). The architecture of the cells has an impact on degradation phenomena during operation, directly affecting the life and safety of the batteries. During ageing, heterogeneities at the electrode level have been observed but are still little studied. Moreover, current modelling at the cell scale considers the degradation to be homogeneous. The aim of this thesis will be first to identify the existing relationships between cell architectures and the generation of localized degradation on the internal components of the cell. This in order to integrate these inhomogeneities in the models developed by the CEA up to the cell scale. The work requested concerns both experimental studies and modelling. In order to carry out his thesis work, the candidate will be hosted at the Laboratory of Electrochemical and Postmortem Analysis of CEA LITEN where he will carry out electrochemical tests and post-mortem analyses and participate in the development and improvement of models in collaboration with the Laboratory of Process Modelling of CEA LITEN. During the thesis a collaboration with Pr. Dubarry's team from the University of Hawaii in the field of data processing based on the ICA (Incremental Capacity Analysis) method.

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Study of transport mechanisms of lithium in hybrid electrolytes for solid-state batterie

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Nanocaractérisation et Nanosécurité

01-10-2020

SL-DRT-20-0872

thibaut.gutel@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

The replacement of liquid electrolyte by ionic conductive phase at solid state (polymer, inorganic or hybrid) is considered as the most promising way to increase electrochemical performances and safety of the next generation of lithium battery. However the improvement of ionic conductivity of these complex systems is still required. Indeed the understanding and modeling of the mechanisms which take place in lithium diffusion inside materials with various properties should be better known in order to develop and optimize solid-state battery. In this PhD, we propose to study a reference hybrid solid-state electrolytes formed by a dispersion of an inorganic material and a lithium salt inside a polymer matrix using approaches based on electrochemistry/characterization/simulation. Selectively labeled systems with 6Li/7Li isotopes will be electrochemically tested and analyzed with mass spectrometry (TOF-SIMS) and solid-state NMR in order to quantify the evolution of isotope ratio at local level and in the bulk in order to identify the transport mechanisms which occurs in these electrolytes with the help of physical model. Advanced characterization techniques used in this PhD will provide physical parameters as inputs for the model in order to predict electrochemical behavior of electrolyte media and consequently to propose some tools to select and modify materials and to optimize the formulation of hybrid electrolytes. Finally this work will lead to identify strategies to improve their performances (ionic conductivity and electrochemical stability).

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Understanding of the protective action of surface treatments on electrode materials

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Matériaux

01-09-2020

SL-DRT-20-0873

david.peralta@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

Next generations of Li-ion batteries will have to increase the driving range of future electric cars. To reach high electrochemical performances, active materials are used close to their theoretical limits. Both electrochemical and chemical stabilities could be affected because the active material/electrolyte interface is very reactive and results in poor battery cycle life. This material/electrolyte interface is also important in the case of solid state batteries where materials surface has to be stabilized before the cell manufacturing process because some materials are not stable in air atmosphere. One of the most interesting strategy to overcome these issues consists of treating the electrode materials surface to limit side reactions before and during cycling. Several coatings (AlF3, Al2O3, MgO, MnO2?) reported in literature highlight that a thin passivation layer at the material surface can enhance the electrochemical behavior by limiting side reactions (ex: Al2O3) and/or by improving the power behavior (AlF3). Despite the number of scientific publications in this field, no clear explanation is provided why such a treatment can enhance both the electrochemical behavior and the stability of the resulting material. The selected student will work at the Battery Components Laboratory of CEA. This laboratory is dedicated to the synthesis and characterization of new battery materials. The PhD student will be in charge of developing new surface treatments and will have to perform several fine characterizations in order to highlight phenomena which happen at materials interface. Candidate has to be a master student and has to be specialized in material chemistry (synthesis and/or characterization).

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In-situ visualization and quantification of microstructural evolutions in all-solid batteries

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Nanocaractérisation et Nanosécurité

01-10-2020

SL-DRT-20-0919

adrien.boulineau@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

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Study of the mechanical behaviour of Li-ion cell electrodes

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Modélisation multi-échelle et suivi Performance

01-09-2020

SL-DRT-20-1035

benoit.mathieu@cea.fr

Electrochemical energy storage incl. batteries for energy transition (.pdf)

In Li-ion cells, the negative electrode is currently mainly made of graphite particles. Using silicon could lead to significant improvements of the Energy Density but silicon suffers from very large volume changes upon cycling. This leads to fragmentation of particles, accelerated cell capacity loss, and possible safety issues. During this thésis, the student will investigate the mechanical behaviour of the particles in the electrode, especially the thickness changes during cycling and the stress/strain relations. He will build a numerical model to predict the mechanical properties of the electrode depending on the composition and particles morphology. The main target numerical method is the "descrete elements model" (DEM) but the student will also use other methods to bridge the gap between the electrode scale and the cell scale (homogenization methods) and the particles scale (finite elements). Input data will be obtained from dedicated experiments that will be conducted in the thesis: measurements on mechanical test Bench, morphological characterization by tomography or FIB-SEM 3D for example.

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