Solid electrolyte for an electrochemical generator

A compound comprising at least one species of formula (I):

• wherein:
• Ax− is an anion of valency x equal to 1 or 2 chosen from sulfonate, sulfonylimide of —SO2—N−—SO2CyF2y+1 type with y being an integer between 0 and 4;
• borate, borane, phosphate, phosphinate, phosphonate, silicate, carbonate, sulfide, selenate, nitrate and perchlorate anions;
• Cx+ is a counter-cation of the anion Ax−, chosen from a proton H+ and alkali metal and alkaline-earth metal cations:
• p is an integer ranging from 1 to 10;
• E is an organic spacer comprising a linear sequence of at least two covalent bonds;
• n is an integer greater than or equal to 2;
• and
• G represents:
• (a) a group
• in which:
• X represents N, P or Si—R, with R representing a hydrogen atom or a C1-4-alkyl group,
• Ar represents a polycyclic group formed from 2 to 6 rings, at least one of which is aromatic, each ring being, independently of each other, 4- to 6-membered, said polycyclic group possibly including up to 18 heteroatoms;
• -□ represents a bond with the spacer E;
• and
• -* represents one or more bonds with said anions Ax−;
• or (b) a group
• in which:
• X1 and X2, which may be identical or different, represent NR, O or S, with R representing a hydrogen atom or a C1-4-alkyl group;
• -□ represents a bond with the spacer E;
• and
• -* represents one or more bonds with said anions Ax−;
• Ar is as defined previously;
• said anion(s) Ax− being covalently bonded to the polycyclic group Ar.