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.

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.

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.

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.

Multiscale Modeling of the Degradation Mechanisms in Polymer Electrolyte Fuel Cells

In an attempt to provide a rigorous physical-based description of the physicochemical phenomena occurring in the PEFC environments, the Modeling Group at CEA-Grenoble/LCPEM has developed a novel physical multi-scale theory of the PEFC electrodes electro-catalysis,the MEMEPhys model, based on a combined non-equilibrium thermodynamics/electrodynamics approach. This postdoctoral research position will consist on actively contributing on the development of the model, including the implementation of a physical-based description of water transport phenomena and water condensation in the PEFC. Heterogeneities on the electrochemical and aging processes, induced by water transport, will be in particular addressed. The candidate will strongly combine theoretical and experimental data, obtained in our laboratory, in order to establish MEA microstructure-performance relationships and to elucidate the main MEA degradation and failure mechanisms. From a fundamental point of view, this work will provide a deeper understanding of the electrochemical mechanisms responsible of the PEFC active layers aging at different spatiotemporal scales.

Proton conducting interpenetrating polymer networks as new PEMFC membranes

This subject takes place in the frame of the development of proton exchange membrane fuel cells (PEMFC) and the main objective is to increase their performance and durability for operation above 100°C at low relative humidity.
The current standard membranes for use in PEMFC applications remain perfluorosulfonated ionomers such as Nafion® due their good proton conductivity and chemical stability. Nevertheless, their proton conductivity decreases for relative humidity below 70% especially at high temperature because of a too low density of proton conducting groups. This characteristic is a limitation for their use in the working conditions of the requirements for the automotive application. With these polymers, an increase of the proton conducting group density leads to a decrease of mechanical and dimensional stability. Yet, this stability is already quite low and decreases the PEMFC durability. The goal of this subject is to develop new membrane structures based on interpenetrating polymer networks that do not present this antagonism between good mechanical stability and proton conductivity. This strategy which has recently been patented by CEA (patent application number 08 06890) is based on the association of two entangled polymer networks, one sulfonated for proton conductivity and one fluorinated for mechanical and chemical stability.
The applicant will make the membranes and then will characterize their mechanical properties, proton conductivity as well as gas permeability. He will also quantify their performance and durability in a running fuel cell.

Couplings between the distributions of water and current density in operating Proton Exchange Membrane Fuel Cell (PEMFC)

The post-doc work will be focused on the measurement of the current density and of the water distributions in an operating fuel cell with a real design, in order to give a better understanding of PEMFC operation as a function of the operating parameters (Temperature, Gas hydration, Pressure, Gas composition). The measurement of the distribution of the current density will be performed using a reliable commercial setup on a full size cell. CEA developed a technique based on Small Angle Neutron Scattering (SANS) as a non-intrusive tool in order to quantify the water distribution during fuel cell operation within and without the membrane. CEA benefits for international recognition on this topic. These measurements will be conducted in high flux neutron reactors, such Institut Laue Langevin (ILL). Some specific high and low resolution neutron imaging experiments could be also be conducting additionally in order to have a complete 3D view of water repartition.

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.

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