TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The ionic liquid comprises: as a cation, a core which comprises a nitrogen atom and which is imidazolium, pyridinium, pyrrolidinium or piperidinium, where the core is substituted on the nitrogen atom by one or more 1-8C alkyl groups and on the carbon atoms by one or more 1-30C alkyl groups; and as an anion, a halide, a perfluorinated anion, a phosphonate, a dicyanamide or a borate, preferably bis(trifluoromethanesulfonyl)imide. The ionic liquid is hydrophobic.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The ionogel further comprises inorganic nanofibers which form covalent bonds with the siloxane crosslinking bridges and which are predominantly anisotropic and mesoporous silica nanofibers. The ionogel has an average thickness of greater than or equal to 10 mu m and an ionic conductivity at 25 degrees C of greater than or equal to 0.7, preferably 1.5-5 mS.cm-1. The confinement matrix is devoid of any molecular precursor of sol-gel type derived from silane, such as an alkoxysilane. The polysaccharide is a cellulose derivative comprising hydroxyethyl cellulose, hydroxyethyl methylcellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, and/or hydroxypropyloxymethoxycellulose. The ionogel comprises the polysaccharide previously silanized by a silanization agent which is capable of forming the siloxane crosslinking bridges and which is a silane compound of formula (A-Si((OR1)(OR2))-OR3), (A-O-B1-Si((OR1)(OR2))-OR3), or (R3-((R2)(R1))Si-O-Si((R1)(R2))-R3), or bis-glycidoxypropyltetramethyldisilazane.A = 1-20C alkyl (optionally substituted by epoxy function) or halo;R1-R3 = straight or branched 1-20C or alkali metal; andB1 = 1-20C alkyl.Preferred Method: The method comprises preparing a hydrogel with a polysaccharide base i.e. silanized and crosslinked by sol-gel by polycondensation in an aqueous medium, then exchange reactions of solvents with increasing hydrophobicities, comprising: a first exchange of solvents exchanging an aqueous solvent containing at least one polysaccharide i.e. silanized and crosslinked by sol-gel, by a first non-aqueous solvent based on a hydrophilic ionic liquid, preferably 1,3-dimethylimidazolium methyl phosphonate; at least one intermediate exchange of solvents exchanging the first non-aqueous solvent by a hydrophilic non-aqueous intermediate solvent based on acetonitrile; and a final exchange of solvents exchanging the non-aqueous intermediate solvent by the hydrophobic ionic liquid. The method comprises mixing a first solution comprising the ionic liquid in an acid medium and a second solution containing the silanized and non-crosslinked polysaccharide in an aqueous basic medium, such that the crosslinking of the polysaccharide via the siloxane bridges takes place by mixing via polycondensation of the polysaccharide in an ionic liquid medium. The method further comprises the addition of inorganic nanofibers.