Résumé
Ionogels represent a route to biphasic materials, for the use of ionic liquids (ILs) for all solid devices. Confining ILs within host networks enhances their averaged dynamics, resulting in improved charge transport. Fragility, short relaxation times, low viscosity, and good ionic conductivity, all them appear to be related to the IL / host network interface. The presence of ILs at interface neighborhood leads to the lowering of cation-anion interaction, i.e. to the breakdown of aggregated and structured regions that are systematically found in bulk ILs.[1] This “destructuration”, as well as segregative interactions at interface,[2] coupled with percolation of the bicontinuous solid/liquid interface,[3] make these materials very competitive among the existing solid electrolytes. Herein we will present an in-depth study of coordination of TFSI anion with lithium or with sodium cations, in the presence of protic or non protic pyrrolidinium cations, confined within silica with well-controlled porosities. The coordination number of TFSI-cation is shown to decrease upon confinement, making the lithium of sodium cation more diffusive. Moreover, the cation-anion layering at the interface is studied by DFT and shows striking modifications when a lithium or sodium salt is added, thus highlighting the effect of the chemistry of the host network, similarly with previous study.[4] References 1) A. Guyomard-Lack, P.-E. Delannoy, N. Dupré, C. V. Cerclier, B. Humbert, J. Le Bideau, Phys. Chem. Chem. Phys., 16, (2014) 23639-23645 2) A. Guyomard-Lack, B. Said, N. Dupré, A. Galarneau, J. Le Bideau, New J. Chem., 40, (2016) 4269-4276 3) C. V. Cerclier, J.-M. Zanotti, J. Le Bideau, Phys. Chem. Chem. Phys., 17, (2015) 29707—29713 4) D. Aidoud, D. Guy-Buissou, D. Guyomard, B. Lestriez, J. Le Bideau, J. Electrochem. Soc., 165, (2018) A3179-A3185