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 breakdown of aggregated, structured regions that are systematically found in bulk ILs. This “destructuration”,¹ 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. Such approach could provide (i) a route to lower locally the viscosity of ILs, and (ii) an easier pathway for diffusion of charged species. Several types of ionogels demonstrate this effect, taking into account of fully inorganic, hybrid, polymeric or organic-inorganic host networks . This “all solid” approach can be applied to several electrochemical energy storage sources, including lithium batteries ^2,4 and supercapacitors.⁵

Herein we will emphasize the results of systematic studies of the effect of size of confinement, either within pores of solids or within meshes of polymers.^2,6 Besides the effect of the size of the confinement, the chemical nature of the host network is investigated. Several examples showed that the best properties were obtained on the basis of a good balance between features of host network and features of confined ionic liquid.

References:

[1] A. Guyomard-Lack et al., Phys. Chem. Chem. Phys., 16 (2014) 23639-23645.
[2] A. Guyomard-Lack et al., New J. Chem., 40 (2016) 4269-4276.
[3] C. V. Cerclier et al., Phys. Chem. Chem. Phys., 17 (2015) 29707—29713
[4] D. Aidoud et al., J. Power Sources, 330 (2016) 92-103
[5] M. Brachet et al., J. Mater. Chem. A, 4 (2016) 11835-11843.
[6] D. Aidoud et al., submitted.