Description of the thesis topic

Next generations of rechargeable batteries will incorporate materials that will improve their performance, particularly for fast charge regimes. Before the fabrication of these future batteries, it is mandatory to understand and investigate the charge storage mechanisms of these electrode materials. Thin films technology is ideal model materials for studying their intrinsic properties and understanding the interactions between electrode materials and ions coming from an electrolyte. This thesis focuses on the development of thin films under vacuum in the vapor phase at IEMN, and the associated electrochemical, structural, electrical and chemical characterizations. These thin films will be integrated as electrodes or electrolyte in lithium based (micro-)batteries and (micro-) supercapacitors manufactured in the laboratory. The candidate will develop thin films electrodes and electrolyte by magnetron sputtering on different types of substrates (Si, glass, STO, MgO...). These films will be crystallized by annealing in tube furnaces at different temperatures and atmospheres (air, Ar, N2, N2/H2) or by flash annealing at high temperatures. A combinatorial sputtering approach will be used by the candidate to scan a large number of compositions, enabling the discovery of new functional materials, particularly in terms of electrolytes. The candidate will benefit from the IEMN environment to develop and characterize these materials, from the resources of the Chevreul federation for advanced characterization (TEM, XPS/TOFSIMS, DRX) and from the scientific support of the RS2E network and the PEPR battery. In parallel with this search for new materials, the candidate will finalize the development of operando FTIR and Van Der Pauw measurement benches at the IEMN under electrochemical stimulation, in order to characterize charge storage mechanisms in real time. These benches will complement the existing operando measurement benches (UV/Vis/IR spectroscopy, Raman, DRX, AFM), and massive measurement and data processing methodologies will be put in place. Operando characterizations in synchrotron radiation at Soleil or ESRF (X-ray absorption and X-ray diffraction) will be planned to complete fundamental understanding needs. Methodologies on these measurement test setups will be developed on “simple” thin films covering faradic materials (Nb2O5, LiFePO4, Li4Ti5O12...) and pseudocapacitive materials (RuN, VN, W2N, MoN...) for (micro-)supercapacitors. The mechanical properties of these materials will be investigated using near-field microscopy (AFM) and nanoindentation, as the mechanical strength of materials will determine the stability of future generations of batteries. Measurements will be carried out in an aqueous medium, an organic medium or a solid electrolyte in a glove box, depending on the needs of the study (Li ion battery in organic liquid electrolyte, Li or Li-ion all-solid battery, supercapacitor in aqueous medium). The candidate will also develop the methodology for characterizing these materials on large substrates (7 to 10 cm in diameter) using multimodal mapping techniques (structural (Raman and DRX), chemical (Fluorescence), electrical, mechanical, electrochemical).

Work Context

The IEMN has been a member of the RS2E since 2012, a member of the STOREX labex since 2018 and a partner in the "Batteries" PEPR since 2023. In this overall context, the research activities carried out as part of this thesis will be based on the CMNF's deposition resources (sputtering, ALD) as well as on the arrival of a thin film deposition cluster for batteries comprising 3 reactors and a mechanical characterisation tool (in a glovebox) for the materials developed. This equipment will pave the way for new materials using a combinatorial sputtering deposition approach coupled with high-speed characterisation techniques available at the IEMN (electrical, mechanical and electrochemical mapping) and at UCCS/Chevreul (chemical and structural mapping). The team has recognised expertise in developing materials for (micro-)batteries or (micro-)supercapacitors using thin-film magnetron sputtering or ALD technology.

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.