Laure Cointeaux

Electrolyte based on fluorinated cyclic quaternary ammonium ionic liquids

Ionic liquids, ILs, based on fluorinated pyrrolidinium and piperidinium ammonium cations and imide anion were prepared and characterized. The physicochemical and electrochemical properties of these ILs including melting point, glass transition and degradation temperatures, viscosity, ionic conductivity, and electrochemical stability were determined and compared to alkyl pyrrolidinium and piperidinium ILs. The incorporation of a CF3 group instead of a CH3 induces an increase of the IL viscosity, thus a conductivity decrease. However, good ionic conductivity is obtained with fluorinated pyrrolidinium IL. Cyclic amine ILs with propyl alkyl chain or fluorinated ammonium exhibit very high electrochemical stability toward oxidation. The effect of the addition of LiTFSI on the IL properties was studied with the same methodology.

N-Hydroxy and N-acyloxy peptides: synthesis and chemical modifications

The preparation of a series of N-hydroxy peptides is described, along with their acylation on the oxygen of the pseudopeptide bond. Nineteen N-acyloxy peptides, first examples of this new class of pseudopeptides, were thus synthesized; they present a range of acyl groups, including N-protected amino acyl groups. Possibilities of elongation for these pseudopeptides were also investigated.

Electrolyte Based on Easily Synthesized, Low Cost Triphenolate–Borohydride Salt for High Performance Mg(TFSI)2-Glyme Rechargeable Magnesium Batteries

A new class of electrolyte based on TFSI- and triphenolate-borohydride anions was designed and produced which fulfill all requirements of easy synthesis, high ionic conductivity, wide potential window, and noncorrosion of Al current collector. The electrolyte composed of magnesium triphenolate borohydride and Mg(TFSI)2 in glyme simultaneously displays a high conductivity of 5.5 mS cm-1 at 25 °C and a reversible Mg plating/stripping with high current density and Coulombic efficiency at room temperature. By addition of a slight amount of MgCl2 to this electrolyte, a Coulombic efficiency of 90% in an SS/Mg cell, stable cycling performance, and a wide anodic potential of 3.4 V vs Mg2+/Mg on Al current collector can be reached. Reversible and efficient Mg insertion/deinsertion with a high capacity of 94 mAh g-1 and 96% Coulombic efficiency was obtained in a Mo6S8 Chevrel cathode phase.