Electrolyte and electrochemical device

An electrochemical device, wherein the electrochemical device comprises electrodes and an electrolyte comprising a dinitrile compound, a trinitrile compound, and propyl propionate, wherein, based on the total weight of the electrolyte, the weight percentage of the dinitrile compound is X, the weight percentage of the trinitrile compound is Y and a weight percentage of the propyl propionate is Z;

• wherein,
• about 2.2 wt %≤(X+Y)≤about 8 wt %,
• about 0.1≤(X/Y)≤about 2.3,
• about 5 wt %≤Z≤20 wt % or 30 wt %≤Z≤50 wt %, and
• about 0.02≤(Y/Z)≤about 0.3;
• wherein the dinitrile compound is one or more compounds selected from the group consisting of butanedinitrile, adiponitrile, ethylene glycol bis(2-cyanoethyl) ether, and 1,4-dicyano-2- butene;
• and the trinitrile compound is one or more compounds selected from the group consisting of 1,3,6-hexanetricarbonitrile, 1,2,6-hexanetricarbonitrile and 1,2,3-tris(2- cyanoethoxy)propane;
• wherein the electrolyte further comprises a compound having a sulfur-oxygen double bond.

An electrolyte, comprising a dinitrile compound, a trinitrile compound, and propyl propionate, wherein, based on a total weight of the electrolyte, a weight percentage of the dinitrile compound is X, a weight percentage of the trinitrile compound is Y and a weight percentage of the propyl propionate is Z;

• wherein,
• about 2.2 wt %≤(X+Y)≤about 8 wt %,
• about 0.1≤(X/Y)≤about 6,
• 5 wt %≤Z≤20 wt % or 30 wt %≤Z≤50 wt %, and
• about 0.01≤(Y/Z)≤about 0.3;
• wherein the dinitrile compound comprises at least one selected from the group consisting of butanedinitrile, adiponitrile, ethylene glycol bis(2-cyanoethyl) ether, and 1,4-dicyano-2-butene;
• and the trinitrile compound is one or more compounds selected from the group consisting of 1,3,6-hexanetricarbonitrile , 1,2,6-hexanetricarbonitrile and 1,2,3-tris(2-cyanoethoxy)propane;
• wherein the electrolyte further comprises 1,3-propanesultone and fluoroethylene carbonate;
• wherein,
• based on the total weight of the electrolyte, a weight percentage of the 1,3-propanesultone is not less than 0.1 wt %, and not greater than 3 wt %.