Electrolyte and electrochemical device

An electrolyte comprising an additive A and an additive B, wherein the additive A is selected from one or more of the compounds of Formula I-1, Formula I-3;

• in which Formula I-1, Formula I-3:
• R1, R2, R3, R4 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C1-C12 alkoxy group, a substituted or unsubstituted C1-C12 amino group, a substituted or unsubstituted C2-C12 alkenyl group, a substituted or unsubstituted C2-C12 alkynyl group, a substituted or unsubstituted C6-C26 aryl group, and a substituted or unsubstituted C2-C12 heterocyclic group, wherein the substituent is selected from one or more of a halogen atom, cyano, a C1-C6 alkyl group, a C2-C6 alkenyl group, and a C1-C6 alkoxy group;
• x, y, and z are each independently selected from an integer of 0 to 8;
• m, n, and k are each independently selected from an integer of 0 to 2;
• and wherein the additive B is selected from one or more of a sulfate compound and a sulfite compound
• wherein the additive A is present in an amount of 0.01% to 10% by mass in the electrolyte;
• the additive B is present in an amount of 0.1% to 10% by mass in the electrolyte;
• and the electrolyte has a conductivity of 6 mS/cm to 10 mS/cm at 25° C.