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
9 proposition(s).

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 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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Selection and optimisation of silicon anodes for all solid state batteries

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

Laboratoire Matériaux

01-01-2020

SL-DRT-20-0864

cedric.haon@cea.fr

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

The success of energy transition will depend strongly on mobility. Electric vehicles will reduce CO2 emissions but the deployment of e-cars is linked to improvements of actual Li-ion batteries in term of energy density, cycle life and safety. In general, conventional Li-ion batteries (LIB) contain a cathode (lithiated Ni-Mn-Co oxide), anode (graphite), liquid electrolyte (carbonate based solvents containing lithium salt) and separator (to avoid short-circuit and allow the shuttling of Li+ ions). LIBs raise safety issues due to their volatile and flammable electrolytes. In addition, low specific capacity of graphite (372 mAh g-1) also hampers the wider acceptance of current LIB, as in electric vehicles. In terms of safety, SSBs are an efficient and viable alternate to conventional LIBs as they do not contain any flammable organic electrolyte. Beside, SSE often show a wide electrochemical potential window, an advantage to increase the energy density of the battery. Many SSBs have been demonstrated using metallic lithium (Li) as anode for simplicity, but Li proved instable against nearly all developed solid-state electrolyte (SSE) and to form dendrites, and is difficult to plate in very thin films. As these detrimental issues are specific to Li metal, a replacement with alloy-based anodes sounds appropriate in developing SSBs. For example, silicon (Si) based anodes are handled in air and high temperature tolerant. Largely Earth abundant, Si can deliver a very high theoretical capacity of 3579 mAh.g-1 or 8303 mAh.cm-3 at an operating voltage of 0.4 V vs Li+/Li. However, the mechanical integrity of the electrodes in SSBs might get severely affected by the large volume changes (>300%) of Si during cycling, resulting in the formation of cracks, pulverization and delamination, which is a critical point. Thus, establishing and maintaining a good contact between electrode and electrolyte throughout cycling is the prerequisite for high energy density SSBs with Si anode. Research and development (R&D) of Si-based SSBs has focus on thin film form of Si as it is expected to address the mechanical issue and charge transfer resistance at interfaces. However, thin film anodes deliver a very low areal capacity (0.3 mAh.cm-2) compared to those of commercial anodes of LIBs (2-5 mAh.cm-2) due to the poor loading of active material. The proposed work deals with the research of silicon materials ? solid electrolytes couples and understanding of chemical and mechanical stability at the interfaces. Silicon materials will be tuned to change particle size and morphology and surface chemistry. Several types of silicon materials will be studied based on our know-how. One or several solid electrolytes will be selected at the beginning of the Ph.D. Understanding of reactivity and fracture mechanisms at the interfaces will be based on in-situ electrochemical characterizations and post-mortem analyses.

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Synthesis of silicon based alloys for Li-ion batteries negative electrode

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

Laboratoire Matériaux

01-10-2020

SL-DRT-20-0868

cedric.haon@cea.fr

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

Silicon appears today as a very promising negative electrode material for Li-ion batteries. Indeed, thanks to its high theoretical specific capacity (3579mAh/g), this material is an interesting alternative to graphite (372mAh/g) for high density energy applications. However, silicon presents an important electrochemical performances fading during charge and discharge cycles due to huge volume changes. Improvements are possible by reducing particles size around 100nm in order to limit the mechanical pulverization or by developing silicon-carbon composites with complex nanostructures. Another possible strategy is to trap silicon nano-domains in ionic and electronic conductive matrix to reduce interface with electrolyte. The interest of silicon ? germanium alloys has been demonstrated in CEA thanks to an original structure. The goal of the Ph.D. is to continue the work on Si-Ge alloys to understand the influence of Ge addition, its impact on the structure and substitute it. A collaboration with Laure Monconduit is proposed for her expertise on Si-Ge alloys obtained by milling. The work will start with the synthesis of selected compositions by laser pyrolysis and milling to understand (de)lithiation mechanisms. Then, substitution elements will be investigated. To finish, a morphological and microstructural optimization will be done based on electrochemical performances. Complementary characterizations (SEM, TEM, XPS) will help to correlate performances in batteries and materials properties.

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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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biomass-based hydrochar for hard carbon production for Na-ion batteries

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

Laboratoire Matériaux

01-09-2020

SL-DRT-20-0897

loic.simonin@cea.fr

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

Na-ion batteries have been the subject of intense research in recent years. Indeed, the criticality of lithium, which has been debated for more than a decade, has led to the search for alternatives to this element as a charge carrier in batteries. From this point of view, research on M-ion systems (M= Na, K, Mg, Ca, etc.) is growing considerably with the Na-ion both as a leading figure and as the most successful system. At CEA, the activity is booming and has made it possible to select very promising active materials in terms of power capability, cyclability, etc. Among these, hard carbon presents remarkable anode performance in terms of specific capacity and service life. Nevertheless, its production cost, 2 to 3 times higher than that of graphite, is a barrier to its commercialization. This high cost is partly explained by the cost of the precursors traditionally used. In this context, the proposed PhD project aims to produce negative electrode materials for Na-ion batteries from wet biomass-based carbon (e.g. sewage sludge, paper industry residues, digestates, microalgae gasification residues, etc.). Most of these wet biomasses are difficult to valorize and constitute low-cost precursors, or even negative cost. First, the hydrothermal synthesis step will be optimized from a limited number of biomasses. Then, the link between the compositional properties of biomasses and then performance of hard carbon will be studied.

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