The invention relates to the field of the lithium ion battery, and discloses additives, electrolyte and a ternary lithium ion battery. The additives comprise additive a and additive b; the additive ais one or mixture of two of a compound of the formula 1 chemical structural formula and a compound of the formula 2 chemical structure formula; the additive b is one or multiple of ethylene carbonate,vinylethylene carbonate, propylene sulfite and 4-ethyl methane-sulphonate. A novel additive is added in the electrolyte, and the electrolyte is added in the ternary lithium ion battery, the high-temperature cycling of the lithium ion battery and high-temperature storage performance can be obviously improved, and the gas output in the high-temperature storage process can be greatly reduced.