Formulation of organic electrode materials for Li-ion batteries with low environmental impact
This project delas with the development of Li-ion battery prototype with a capacity of 500mAh only based on the use of organic elecrode materials (PTCLi4 for the negative electrode and MgLi2pDHT for the positive electrode) combined with a polymer electrolyte developped by CNRS/LEPMI. It will focus on the issues related to material implementation in order to prepare électrodes containing low carbon ration (2mAh/cm2)
Polymeric reversible conductive adhesive for recyclable electronics
Electronic devices contain valuable and noxious metals that are today hardly recovered. While the demand for electronics is still growing, the urge for recyclable electronics development grows stronger. Printed Circuit Boards (PCB) are the core of electronics and contain electronic component that are fixed onto metal tracks through conductive adhesives. Such adhesives contain generally a metallic filler and a polymeric binder that is generally a polymerizable thermoset formulation.
With the increasing topics on material circularity, self-immolative polymers (SIP), polymer systems that have the ability to undergo depolymerization with a stimulus, have emerged in the recent years as viable systems to bring recyclability to polymer materials.
The current post-doc will develop a polymerizable SIP binder to be used in conductive adhesive in PCB applications. After the selection of adequate chemistries, the post-doc will synthesize SIP and evaluate their thermal and mechanical properties and their ability to depolymerize under stimulus. In a second step, the most promising SIP will be formulated as a conductive adhesive and will be applied to a PCB. The recyclability of the final object will be studied.
Post-Doc - Research Engineer In-situ characterization coupled with electro-reduction of CO2
This project concerns the Circular Carbon Economy program. It proposes mature solutions for industrial decarbonization based on electrochemical CO2 recovery. The candidate will be in charge of developing an electrolyzer for optimized conversion of CO2 into CO; a key molecule in the synthesis of many carbon-based products; by integrating in-situ characterization resources (UV-Vis, Infra-Red). The development of customized cells coupled with this local characterization, should enable to gain a better understanding of reaction phenomena, determine the diffusion mechanisms of species in the electrolytic medium, and extend the analysis to the entire electrochemical system. Studies and experiments will allow to optimize not only the catalytic system, but also the various cell components (membrane, electrode, Gas Diffusion Layer / Gas Diffusion Electrode, electrolyte, CO2 routing), in order to propose innovative, high-performance electrolyzer designs.
Design and fabrication of magnetic cores having permeability gradient using additive manufacturing
As a major technological research institute, the CEA-Liten plays a decisive role in the development of future technologies for the energy transition and the limitation of greenhouse gas emissions. The laboratory develops magnetic components working at high frequency (> 100 kHz) for an integration in compact power electronics converters. Today, the discrete magnetic components are among the most bulky parts in the power converters (~30-40%) and they are responsible of almost 40-50% of the heat losses. The advent of wide band gap semiconductors (SiC or GaN) increases the switching frequency to values above 100 kHz. This strategy helps to reduce, theoretically, the dimensions of the passives but the thermal constraints (due to the losses produced at a higher frequency) and the electromagnetic compatibility (EMC; due to the noise emerging from faster switching commutations) may constitute an issue (in a system approach). In this sense, the developments of new architectures (based on advanced core geometries or clever magnetic materials arrangements) may constitute a breakthrough. The diversity of present cores and fabrication technologies permit small incremental gains on these magnetic components integrations. Additive manufacturing is a very emerging fabrication process that allow not only developing new core geometry but also, the adjustment of core composition (by allowing the deposition of layers containing different ferrite powder composition). The post-doctoral fellow will work on the design of a core having a permeability gradient and on its electrical and thermal characterizations. The post-doctoral fellowship is of 2 years duration located in the city of Grenoble (France) with a minimum wage of 40 k€ per year. If you want to have more detail please use the following link: https://liten.cea.fr/cea-tech/liten/Documents/Postdoc-Carnot-EF/AMbassador.pdf
Thermodynamic study of the Nb-O-Zr system for the nuclear fuel elements recycling
The first step of nuclear material recycling consists in a section-cutting process of the fuel assemblies leading to shells.
Nuclear materials in the cut sections are dissolved in acid solutions whilst structural as well as cladding materials are rinsed and then compacted in CSD-C containers for a final storage in CIGEO.
The REGAIN project aims at studying the feasibility of an alternative solution: the objective is to investigate the possibility to optimize the nuclear and cladding materials management by reducing the radiological source term. The idea is to proceed to a sequence of decontamination steps in order to minimize the waste volume: The first step consists in removing minor actinides and fission products and the second one in the separation of zirconium from structural activation products.
In order to feed the industrial process study, a part of the REGAIN project aims at collecting raw data, which will be used by the other work packages of the project.
In this framework, CEA proposes a post-doctoral position with the purpose of developing a thermodynamic database for the Nb-O-Zr system starting from literature data as well as using experimental informations obtained within the first stages of the project. It will be also possible to include a selection of key fission products into the existing database. The candidate may also be asked to complete the existing data by an experimental campaign to obtain a complete set of data for the modelling. The scientific approach will be based on the CALPHAD method: this method allows developing a thermodynamic database by the definition of an analytical formulation of the thermodynamic potential, which will be used to calculate phase diagrams as well as thermodynamic properties of multi-components systems.
Development of a simulation tool for the pitting process of a stainless steel used for the storage of nuclear waste
Structural nuclear waste is compacted in patties, stacked in a stainless steel container. In these compacting boxes are placed various metal-type materials with the addition of organic matter, including chlorinated waste. By radiolytic degradation, these can lead to the formation of hydrogen chloride HCl. During the storage phase, relative humidity may be present within the container, which, added to the HCl, may lead to a phenomenon of condensation, resulting, on the surface of the materials, of acid and concentrated into chloride ions condensates. In contact with this acid and chloride electrolyte, a pitting phenomenon is likely to begin on the surface of a stainless steel. This is a local phenomenon that can lead to the piercing of the material in extreme cases. The initiation of this phenomenon depends on several factors: the morphology of the electrolyte, its composition and its evolution over time.
If nowadays this phenomenon is well known, modeling it remains a major challenge because it is a coupled multi-physics and multi-parameter problem. Many questions remain open, particularly at the level of the physical and chemical laws to be used or how to represent the corrosion process?
The objective of the post-doctorate is to develop a tool under COMSOL capable of simulating the initiation and the evolution over time of a pit on the surface of a stainless steel. The approach will be based on a mechanistic modeling of the processes (material transport process and all the chemical and electrochemical reactions).
The post-doctorate will take place in several actions:
1- make a state of the art of the bibliography in order to understand the pitting phenomenon and to identify the laws necessary for modeling.
2-simulate the spread of the pit in a chloride environment in order to establish a propagation criterion.
3-the pitting initiation will be implemented in order to obtain a complete tool capable of simulating the pitting process
Post-doctorate in PEM Fuel cells development and characterizations
The objective of this post-doctoral position is to understand how a realistic manufacturing defect in the Membrane Electrode Assembly (MEA) can affect the performance loss and the degradation rate of PEMFC stacks. Among the most common defects, the lack/absence of active layer (particularly at the anode side where loadings are very low), the presence of agglomerates, cracks or excessive thickness in the active layers or in the microporous level of the GDL are often encountered locally (few cm²). Here, this work will rely on the expertise at CEA LITEN to produce MEA with a controlled structure (homogeneous deposits, good membrane|electrode interface, mapping of local catalyst loading). Both homogeneous and defective MEA with controlled properties, will be tested electrochemically.
The tests will notably include clever coupling between the different physical and electrochemical characterization methods possible ex-situ, operando or post-mortem. Among them, magneto-tomography, a technique based on measuring the magnetic field generated by the current passing through the stack, will continue to be developed. These measurements will make it possible to quantify the 3D effect of defects during operation. Finally, the post-doctoral fellow will use existing modeling tools to improve the prediction of the lifespan of PEMFCs related to the initial local properties of MEA.
All these experimental and simulation works will make it possible to correlate local operational heterogeneities and the degradation mechanisms associated with the defects depending on their nature or their positioning in the cell. Consequently, this study will provide some key-recommendations for the type and size of defects acceptable within MEA in relation with the operating and lifespan specifications of the PEMFC system.
Post doctoral position in solid state electrochemistry / ceramic materials / NH3 synthesis by electroreduction
Research into the electrochemical synthesis of NH3 focuses mainly on electrolysis cell configurations and materials, catalyst development, strategies for improving the selectivity of the N2 reduction reaction compared with that of water, and verification of the synthesis results. The post-doctorate proposed here will focus on high temperature (400-650°C) proton (H+) and anion (O2-) electrolysis processes offering the possibility of using H2O(g) and/or H2 to reduce N2.
The objectives of these studies will be as follows:
-identifying anionic O2- (SOEC for Solid Oxide Electrolysis Cell) and protonic H+ (PCEC for Proton Ceramic Electrolysis Cell) electrolysis cell materials suitable for NH3 synthesis,
-optimisation or development of these cells,
-quantification of the ammonia produced for each cell tested,
-identification of the first-order parameters needed to maximise NH3 production kinetics,
-drawing up a preliminary energy balance for comparison with the conventional Green Habor Bosch process.
Composition of shape memory alloys (SMA) by combinatorial synthesis and additive manufacturing
As part of the PEPR DIADEM program , the ARTEMIS consortium is focusing on 4D leveraging on accelerated discovery methods and the development of intelligent materials and active structures using 3D printing. The shaping of active materials using additive manufacturing to design intelligent structures capable of changing shape or properties in response to an energy stimulus is a game changer in the field of sensors and actuators. In this context, the MAPP technological platform at CEA Tech Metz is proposing to implement a low-pressure Cold Spray process equipped with multiple powder dispensers. Combinatorial deposition will enable rapid screening of shape memory alloy (SMA) compositions in response to various stimuli. Post-processing optimization should enable the alloy to be converted from the combinatorial deposition state. Comprehensive characterization of the materials is expected at each stage of the process. The collection of a large amount of data (experimental, theoretical or resulting from numerical simulation), together with the implementation of a rigorous methodology, will feed an Artificial Intelligence, ExpressIF®, which will provide an explanatory decision-making aid.
Innovative biobased vitrimer electrolytes for self-healable and recyclable Li metal batteries
This post-doctoral position is part of the « ELECTRIMER » project, which aims to reduce the environmental impact and to improve the safety of the future Li-metal batteries. In this contexte, the recruited researcher will develop a new self-healable and extrudable Gel Polymer Electrolyte (GPE). Biobased monomers of generations 2 and 3 (not in competition with the food industry) will be used to synthesize a new polymer, that will be swollen with green and safe solvents. A vitrimer chemistry will be integrated in the polymer structure, in order to improve the batterie durability, by introducing self-healing properties to the GPE. The reversible chemistru will also allow to improve the batterie recyclability.