Electrolyte for electrochemical device

An electrolyte for an electrochemical device, said electrolyte comprising an ionic metal complex represented by the general formula (1):

• wherein M is a transition metal selected from the group consisting of Sc, Ti, V, Cr, Mn, Cu, Y, Zr, Nb, Mo, Tc, Ag, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Au, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr, 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 proton;
• provided that M is not B when Aa+ is Cs+;
• 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 3;
• n represents a number from 0 to 4;
• q is 0 or 1;
• X1 represents O, S or NR5R6;
• each of R1 and R2 independently represents H, a halogen, a C1-C10 alkyl group or C1-C10 halogenated alkyl group;
• R3 represents a C1-C10 alkylene group, C1-C10 halogenated alkylene group, C4-C20 aryl group or C4-C20 halogenated aryl group;
• R4 represents a halogen, C1-C10 alkyl group, C1-C10 halogenated alkyl group, C4-C20 aryl group, C4-C20 halogenated aryl group or X2R7;
• X2 represents O, S or NR5R6;
• each of R5 and R6 represents H or a C1-C10, alkyl group;
• and R7 represents a C1-C10 alkyl group, C1-C10 halogenated alkyl group, C4-C20 aryl group or C4-C20 halogenated aryl group.