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Reference : UMR5279-DIDDEV-001
Workplace : ST MARTIN D HERES
Date of publication : Monday, February 17, 2020
Scientific Responsible name : Didier Devaux
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 April 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Energy production and storage are great challenges to ensure the energetic transition. High energy density, low cost, with extended cycle life batteries must be developed to promote renewable stationary applications (solar and wind farm) and electrified transport. Nowadays, Lithium (Li)-ion batteries are the dominant solutions to power small electronic portable devices and are now used in most of the hybrid and full electric cars. However, for all of these applications this accumulator is not fully adequate because its energy density should be increased by factor two at minimum to answer the demand of the market. In addition, the presence of flammable liquid electrolyte is a strong safety issue (fire, explosion). To overcome these limitations a solution is to replace the unsafe liquid electrolyte by an inherently non-flammable solid polymer electrolyte. In addition to safety, the other advantage of polymer electrolytes resides in their chemical and electrochemical stability toward metallic Li. This material is ideally suited as negative electrode because of its high specific capacity. At the positive electrode side, an interesting active material is sulfur (S8). The specific capacity of sulfur is important and permits to envision Li-S8 batteries with a specific energy density in the order of 500 Wh/kg, roughly twice that of conventional Li-ion accumulator. However, many hurdles remain to be solved to favor this battery technology such as the lithium polysulfides dissolution into the electrolyte upon cycling (redox shuttle effect) which impairs the delivered capacity and the faradaic efficiency, and the prevention of dendrite growth at the negative electrode leading to short-cut issues.
In this context, the project proposes to design a Li-S8 battery with a polymer electrolyte. The goal is to develop a device based on a new generation of sulfur based accumulator in order to increase in the energy density and cyclability. One of the originality of the project corresponds to the investigation of the functioning and failure modes by operando analysis using X-ray tomography.
The PhD student will work at LEPMI laboratory and will perform physico-chemical and electrochemical characterizations of materials and interfaces of the sulfur based batteries. Many different techniques will be done to analyze the electrolyte transport properties, the electrochemical and thermal properties, the interface formed with the active materials, and the diffusion phenomena by electrochemical impedance spectroscopy. Battery test will map the power performances. In addition, the behavior of the interfaces will be monitor by X-ray tomography which is available on Grenoble campus (CMTC, SIMaP).
The LEPMI (Laboratory of Electrochemistry and Physico-Chemistry of Materials and Interfaces) is a mixed unit (UMR 5279) composed of scientist and professors of National Center for Scientific Research (CNRS), Grenoble Institute of Technology (Grenoble-INP), Grenoble Alpes University (UGA), and the University Savoy Mont Blanc (USMB). The main research activities of the laboratory deal with elaboration, physical and electrochemical characterizations of materials (polymers, salts, ionic liquids, ceramics) for energy related devices.
The PhD student will work within the MIEL (Materials Interfaces and ELectrochemistry) team located on Grenoble campus at Saint Martin d'Hères. The team is focusing on the design and physico-chemical and electrochemical characterizations of polymers, salts, ionic liquid, ionomers and electrolytes for energy conversion and storage (batteries : Li-polymer, Li-ion, Li-sulfur, Mg, Na; fuel cells: PEMFC and PAFC). In addition, the team has a big activity on coupling techniques to perform operando and in-situ measurements: electrochemistry/Raman, Electrochemistry/NMR, electrochemistry/synchrotron based technics. The MEIL team is composed of 17 permanents, 14 PhD students/year, 4 post-doctoral fellows/year, and 6 Masters/year.
Knowledge in electrochemical and physico-chemical characterizations are necessary. Some interest in battery systems is a plus. In addition, please apply with your resume and a cover letter.
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