Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PhD : selection by topics

Sciences pour l'ingénieur >> Chimie physique et électrochimie
1 proposition(s).

Study of silicon electrodes and their SEI by using surface analysis and isotopic labelling

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Nanocaractérisation et Nanosécurité

01-10-2016

SL-DRT-16-0909

eric.de-vito@cea.fr

We aim at developing a state-of-the-art method for characterization of the solid electrolyte interphase (SEI) on silicon electrodes and lithium life cycle. This SEI is the result of electrolyte reduction and degradation at the electrode surface, and is one of the main causes of performance loss and durability of Li-ion battery systems. Surface analysis methods such as X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) are particularly well-suited for such studies. In order to go even further, we also consider using isotopic labelling and benefit of the ToF-SIMS ability to separate elements and molecular fragments by their mass. There are still few studies described in literature. Cross-analysis protocols involving ToF-SIMS and XPS, and maybe also Auger spectroscopy, will be developed. This approach will allow a better description of the SEI structure developing on (or in) electrode materials during electrochemical cycling. This work will rely on the development of studies carried out in CEA Grenoble, in relation with 1) the prélithiation of silicon electrodes, which is a way to preempt the first irreversibility cycle and 2) the formation, which is the way to optimize the SEI before ageing. Prior and in parallel to these case studies, model cases such as thin silicon layers used in micro-batteries, will be considered in order to optimize the methodology. This work will take place at LITEN, in CEA Grenoble. Characterizations will be carried out at the Nanocharacterization Center at Minatec Campus, while battery cells and electrochemical analysis will be done in the Electricity and Hydrogen for Transport department. Complementary analysis will be considered as well, such as scanning or transmission electronic microscopy (SEM/TEM), nuclear magnetic resonance (NMR) or atomic force microscopy (AFM). By providing state-of-the-art materials, industrial partners will also be involved in this research project. The PhD student will have an excellent working environment with privileged access to various characterization techniques on state-of-the-art instruments. A strong interaction with different research teams is essential, so that communication and openness will be important assets for the success of this thesis work.

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