ELECTRONIC STRUCTURE OF IONIC LIQUID BASED ELECTROLYTE FOR LITHIUM ION BATTERY INVESTIGATED BY OPERANDO X-RAY PHOTOEMISSION SPECTROSCOPY
Jorge Morales (*)a,b,d, Anass Benayada,b, Catherine Santinic, Renaud Boucheta,d
a Univ. Grenoble Alpes, 38000 Grenoble, France
b CEA, LITEN, Department of Nanomaterials, MINATEC, 17 rue des martyrs, 38 054 Grenoble Cedex 09, France
c CNRS-UMR 5265, 43 Bd du 11 Novembre 1918, 69616 Villeurbanne Cedex, France
d LEPMI-INP, 1130 rue de La Piscine, 38402 St. Martin d’Hères, France
* firstname.lastname@example.org , Tel: (+33) 04 38 78 93 40
Besides the industrial challenges to enhance the material efficiency for energy storage, lithium ion batteries are under the spotlight as a potential candidate for powering many electronic devices such as computers, cameras and mobile phones. Furthermore, the intensive research in this field is allowing the development of next generation of electrical vehicles.
However, metallic lithium batteries based on polar electrolytes suffer from thermal runaway when dealing whit high energy-density battery system, limiting the choices for electrolyte//electrode combination. One of the approach is the replacement of conventional battery electrolytes with special solvents known as ionic liquids (ILs)  due to their thermal and electrochemical stability, flame retardant performance and high ionic conductivity.
The understanding of the structure and dynamics of ionic liquids (ILs) is the key of interest for the development of lithium battery system. Their behavior at the interfaces has been an important subject of study. Nevertheless, the poor cycling observed with IL-electrolytes based systems anode is a significant drawback for their implementation in industrial production. In order to develop new IL based electrolytes, understanding of their reactivity with anode surface is crucial.
X-ray photoelectrons spectroscopy (XPS), known as a non-destructive and powerful surface analysis tools has been extensively used to study solid electrolyte interface (SEI), which is one of the origin of battery failure . However, most of the developed experimental protocols are based on ex-situ studies. These process involves special handling of the samples and may significantly modify the stability of the electrochemical processes happening in the samples before each analysis.
The aim of this work is to design a new electrochemical cell adapted to the study of the interface electrode/electrolyte (IL) by mean of operando XPS mode. That allows to follow directly the chemical evolution of IL electrolyte at the surface of the electrodes during cycling. This new approach will be also devoted to study the degradation process occurring at the interface between ionic liquid electrolyte and lithium metal anode.
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