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)
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.
Development of high energy density hybrid positive electrodes for hybrid potassium supercapacitors
With the aim of increasing the capacity and therefore the energy density of hybrid potassium supercapacitors, a low-cost technology without dependence on critical and strategic materials, a Carnot project aims to develop a hybrid positive electrode integrating a capacitive material and a faradaic material.
The post-doctoral fellow will contribute, in close collaboration with the other people in the laboratory and the department, to the development of the hybrid electrode, from the material to the production of complete cells.
Among the processes used, the synthesis of faradic materials, the formulation and the coating of the hybrid electrode will be studied. Subsequently, prototype cells will be manufactured and then tested to assess the capacity reached and understand the charge storage mechanism resulting from the combination of the two materials. Button cells will first be produced, then “pouch” cells, similar to commercial cells. At each stage, specific characterizations of these electrodes will be carried out. For this research and development work, most of the tests take place in the chemistry laboratories and dry rooms of the battery platform.
New Sustainable Carbon Catalysts for PEMFC
The aim of the project is to develop and test for ORR, a mesoporous and graphitised graphene aerogel based material, presenting a hierarchical structuring allowing a better material transfer and graphitic domains increasing the durability and conductivity of the final material, and functionalised by Pt-NPs.
These graphene-based structures developed at IRIG/SyMMES possess surface chemistries and micro/meso/macro porosities that depend on the synthesis, functionalisation and drying methods used. The aim will be to increase their degree of graphitisation, and then to deposit Pt-NPs by chemical means. The electrocatalytic properties of these materials will then be tested.
Advanced meso-structural characterisation of these materials by scattering (X-ray or neutrons) methods will enable to investigate the structural properties of these new electro-catalysts. These properties will thenbe correlated to their electrocatalytic properties, and performances in fuel cell systems. This knowledge will be gained through ex-situ and operando analyses.
HPC simulation of electrode mechanical properties in Li-ion batteries
Li-ion batteries are complex multi-physics systems in which chemical reactions, transport phenomena, and mechanical deformation are strongly coupled. The battery electrodes are composed of micrometric granular materials (the microstructure) where the lithium can insert and disinsert, a process that creates internal mechanical stress and strain in the materials and subsequent volumic changes. While it is currently observed that the coupling between electrochemical reactions and mechanical deformation at the microstructure level strongly impacts the battery performances, lifespan and safety, the origin of this impact is poorly understood. The global objective of this position is to better understand the coupling between mechanical deformations of the microstructure and the local conditions of lithium transport in the electrode. The study should lead to practical applications such as recommendation on the electrode design to increase life capability of Li-ion batteries.
Postdoc in Multi-instrumented operando monitoring of Li-ion battery for ageing
Nowadays, the development of new battery technology requires increasing the knowledge of degradation mechanisms occur inside the cell and monitor the key parameter in real time during cycling to increase the performances, lifetime and safety of the cells. To achieve these goals development of new sensing technology and integration inside and outside the cell is needed. The goal of the SENSIGA project is used advanced sensing technology to improve the monitoring of the cell by acquiring useful data correlate to the degradation process and develop more efficient battery management system with accurate state estimators. SENSIGA is a part of PEPR Batteries lead by CNRS and CEA and funding by the French Research Programme FRANCE 2030 to accelerate the development of new battery technology.
You will have the opportunity to work in a stimulating scientific environment focusing on the characterisation of both state of the art and latest generations of battery materials. Based on the sensing technology developed at CEA and from the state of the art, the SENSIGA project will reach the objective of the BATTERY2030+ roadmap goals for smart cells (https://battery2030.eu/research/roadmap/). One of the objectives of the project is to use external sensors to monitor the key parameters of the cell related to performances, ageing and safety behaviours.
Simulation of PEMFC flooding phenomena
The proton exchange membrane fuel cell (PEMFC) is now considered as a relevant solution for carbon-free electrical energy production, for both transport and stationary applications. The management of the fluids inside these cells has a significant impact on their performance and their durability. Flooding phenomena due to the accumulation of liquid water are known to impact the operation of the cells, causing performance drops and also damages that can be irreversible. With the use of thinner channels in ever more compact stacks, these phenomena are becoming more and more frequent. The objective of this post-doc is to progress in the understanding of flooding in PEMFCs. The work will consist in analyzing the link between the operating conditions, the design of the channels and the materials used in the cell. It will be based on a two-phase flow modeling approach at different scales, from the local scale at the channel-rib level, up to, via an upscaling approach, the level of the complete cell. The study will also be based on numerous experimental results obtained at the CEA or in the literature.
HPC simulations for PEM fuel cells
The goal is to improve TRUST-FC software -a joint development between LITEN and DES institutes at CEA- for detailed full 3D simulation of hydrogene PEM fuel cells and to run simulations on whole real bipolar plate geometries. Funded by AIDAS virtual lab (CEA/Forshungs Zentrum Juelich), a fully coupled electro-chemical, fluidic and thermal model has been built, based on CEA software TRUST. The model has been benchmarked against its FZJ counterpart (Open fuelcell, based on OpenFoam). The candidate will adapt the software and toolchain to larger and larger meshes up to billion cells meshes required to model a full bipolar plate. Besides, he will introduce two phase flow models in order to address the current technological challenges (local flooding or dryout). This ambitious project is actively supported by close collaboration with CEA/DES and FZJ.
Optical sensor development for in-situ and operando Li-ion battery monitoring
To improve the battery management system, it is required to have a better knowledge of the physical and chemical phenomena inside the cells. The next generation of cells will integrate sensors for deepest monitoring of the cell to improve the performances, safety, reliability and lifetime of the battery packs. The main challenge is thus to measure relevant physico-chemical parameters in the heart of the cell to get a direct access to the real state of the cell and thus to optimize its management. To address this challenge, a research project will start at CEA at the beginning of 2020 to develop innovative optical sensors for Li-ion battery monitoring. He / She will participate, in a first step, to the development of optical probes and their integration on optical fibres. The work will focus on the synthesis of a photo-chemical probe (nanoparticle and/or molecule) as active part of the sensor. Then, theses probes will be put on the optical fibre surface to form the sensor. The candidate will also participate to the realization of an optical bench dedicated to the testing of the sensors. In a second step, he / she will work on integrating the sensors into the Li-ion cells and test them in different conditions. The objective is to demonstrate the proof of concept: validation of the sensors efficiency to capture the behaviour of the cell and correlate it to electrochemical measurements.
Electrochemical device for purifying hydrogen in a reformed gas
This project aims to establish a new research and development on purification devices for fuel reformers for hydrogen fuel cells. This work is of prime importance for fuel cell systems fed by different sources of hydrogen. Used in "power full" or "range extender" modes, the reformer and gas purification system are elements of the chain that have to be optimized.
Objective is to develop an electrochemical device for purifying the gas from a reformer whose basic principle is similar to that of a PEM electrolyzer. The gases from the reformer undergo a selective electrocatalytic oxidation to separate hydrogen and conventional pollutants directly power a fuel cell.
The project will focus on selection and characterization of catalysts electrocatalytic performance and the achievement of functional prototypes. These developments will assess the economic relevance of the device vis-à-vis other systems and identify areas of research to develop thereafter.