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);
• and
• at least one compound selected from the group consisting of compounds represented by formulas (2) to (7) or selected from the group consisting of compounds represented by the formulas Aa+(PF6−)a,Aa+(ClO4−)a,Aa+(BF4−)a, Aa+(AsF6−)a, and Aa+(SbF6−)a,
• 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;
• An+ represents a metal ion, hydrogen ion or onium 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;
• 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, these alkylene and arylene groups of said R1 optionally having substituents and hetero atoms, one of said R1 being optionally bonded with another of said R1;
• each of X1 and 2 independently represents O,S or NR2;
• R2 represents a hydrogen, C1-C10 alkyl group, C1-C10 halogenated alkyl group, C4-C20 aryl group or C4-C20 halogenated aryl group, these alkyl and aryl groups of said R2 optionally having substituents and hetero atoms, at least two of said R2 being optionally bonded together to form a ring;
• each of x, y and z independently represents a number from 1 to 8;
• each of Y1, Y2 and Y3 independently represents a SO2 group or CO group;
• and
• each of R3, R4 and R5 independently represents an electron-attractive organic substituent optionally having a substituent or a hetero atom, at least two of said R3, R4 and R5 being optionally bonded together to form a ring, at least one of said R3, R4 and R5 being optionally bonded with an adjacent molecule to form a polymer,
• and wherein when q=0.X1 is oxygen, X2 is oxygen, m=2. M is boron, and Aa+ is Li+ in said first compound, the at least one compound is selected from the group consisting of compounds represented by formulas (5), (6), (7), and Aa+(SbF6−)a,