Abstract: Energy storage materials, and specifically, an electrolyte and an electrochemical device, where the electrolyte includes an additive A and an additive B, the additive A is selected from multi-cyano six-membered N-heterocyclic compounds represented by Formula I-1, Formula I-2 and Formula I-3, and combinations thereof, and the additive B is at least one sulfonate compound. The electrochemical device includes the above electrolyte. The electrolyte can effectively passivate surface activity of the positive electrode material, inhibit oxidation of the electrolyte, and effectively reduce gas production of the battery, meanwhile the electrolyte can be adsorbed on catalytically active sites of the graphite surface to form a stable SEI film, thereby effectively reducing side reactions. The electrochemical device using the electrolyte has good high temperature and high voltage cycle performance and storage performance.