In-Depth Interfacial Chemistry and Reactivity Focused Investigation of Lithium-Imide- and Lithium-Imidazole-Based Electrolytes.
A comparative and in-depth investigation on the reactivity of various Li-based electrolytes and of the solid electrolyte interface (SEI) formed at graphite electrode is carried out using X-ray photoelectron spectroscopy (XPS), chemical simulation test, and differential scanning calorimetry (DSC). The electrolytes investigated include LiX (X = PF6, TFSI, TDI, FSI, and FTFSI), dissolved in EC-DMC. The reactivity and SEI nature of electrolytes containing the relatively new imide (LiFSI and LiFTFSI) and imidazole (LiTDI) salts are evaluated and compared to those of well-researched LiPF6(-) and LiTFSI-based electrolytes. The thermal reactivity of LixC6 in the various electrolytes is found to be in the order of LiFSI > LiTDI > LiTFSI > LiFTFSI > LiPF6 and LiFSI > LiFTFSI > LiPF6 > LiTFSI > LiTDI in terms of onset exothermic temperature and total heat generated, respectively. Surface and depth-profiling XPS analysis of the SEI formed with the diverse electrolyte formulations provide insight into the differences and similarities (composition, thickness, and evolution, etc.) emanating from the structure of the various salt anions.
Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU) , Helmholtzstraße 11, D-8908 Ulm, Germany.|Karlsruhe Institute of Technology (KIT) , P. O. Box 3640, 76021 Karlsruhe, Germany.
Gebrekidan Gebresilassie
GG
Eshetu
Institute of Surface Chemistry and Catalysis, Ulm University , Albert-Einstein-Allee 47, D-89081 Ulm, Germany.
Thomas
T
Diemant
Laboratoire de Réactivité et de Chimie des Solide (LRCS) CNRS UMR7314, Réseau sur le Stockage Electrochimique de l'Energie, CNRS RS2E FR3459 33 rue Saint Leu, 80039 Amiens, France.
Sylvie
S
Grugeon
Institute of Surface Chemistry and Catalysis, Ulm University , Albert-Einstein-Allee 47, D-89081 Ulm, Germany.
R Jürgen
RJ
Behm
Laboratoire de Réactivité et de Chimie des Solide (LRCS) CNRS UMR7314, Réseau sur le Stockage Electrochimique de l'Energie, CNRS RS2E FR3459 33 rue Saint Leu, 80039 Amiens, France.
Stephane
S
Laruelle
CIC Energigune, Parque Tecnologico de Alava , Albert Einstein 48, ED. CIC, 01510 Minano, Spain.
Michel
M
Armand
Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU) , Helmholtzstraße 11, D-8908 Ulm, Germany.|Karlsruhe Institute of Technology (KIT) , P. O. Box 3640, 76021 Karlsruhe, Germany.
Stefano
S
Passerini
Li-ion battery; SEI layer; XPS; electrolyte; imidazole; imide; solid−electrolyte interphase