Electrolyte for electrochemical device

An electrolyte for an electrochemical device, said electrolyte comprising a first compound that is an ionic metal complex represented by formula (1),

• wherein M is a transition metal selected from the group consisting of elements of groups 3-11 of the periodic table, or an element selected from the group consisting of elements of groups 12-15 of the periodic table;
• Aa+ represents a metal ion, onium ion or hydrogen ion;
• a represents a number from 1 to 3;
• b represents a number from 1 to 3;
• p is b/a;
• m represents a number from 1 to 4;
• n represents a number from 1 to 8;
• q is 0 or 1;
• R1 represents a C1-C10 alkylene group, C1-C10 halogenated alkylene group, C4-C20 arylene group or C4-C20 halogenated arylene group, the alkylene and arylene groups of said R1 optionally having substituents and hetero atoms, wherein optionally one of said R1 is bonded with another of said R1;
• R2 represents a halogen, C1-C10 alkyl group, C1-C10 halogenated alkyl group, C4-C20 aryl group, C4-C20 halogenated aryl group or X3R3, the alkyl and aryl groups of said R2 optionally having substituents and hetero atoms, wherein optionally one of said R2 is bonded with another of said R2 to form a ring;
• each of X1, X2 and X3 independently represents O, S or NR4;
• and
• each of R3 and R4 independently represents a halogen, C1-C10 alkyl group, C1-C10 halogenated alkyl group, C4-C20 aryl group, or C4-C20 halogenated aryl group, the alkyl and aryl groups of said R3 and R4 optionally having substituents and hetero atoms, wherein optionally one of is said R3 is bonded with another of said R3 to form a ring, and wherein optionally one of said R4 is bonded with another of said R4 to form a ring.