Electrolyte for lithium ion secondary battery and lithium ion secondary battery

The invention discloses an electrolyte capable of being used for a lithium ion secondary battery and the lithium ion secondary battery containing the electrolyte, the electrolyte contains a solvent, a lithium salt, a pyrocarbonate compound and a fluorobenzene compound, and the mass percent of additives in the electrolyte meets the following conditions: 0.2% < = k1 < = 1.2%, 1% < = k2 < = 5%, and 0.1 < = k1/k2 < = 0.3, k1 represents the mass percent of the pyrocarbonate compound in the electrolyte, and k2 represents the mass percent of the fluorobenzene compound in the electrolyte. The electrolyte provided by the invention can construct a low-impedance and high-stability SEI film, and effectively solves the problems of poor dynamic performance and short cycle life of a battery. 本发明公开了一种可用于锂离子二次电池的电解液及含有所述电解液的锂离子二次电池，所述电解液含有溶剂、锂盐、焦碳酸酯类化合物和氟苯类化合物，且电解液中添加剂质量百分数满足：0.2％≤k1≤1.2％，1％≤k2≤5％，0.1≤k1/k2≤0.3，其中，k1表示焦碳酸酯类化合物占电解液的质量百分数，k2表示氟苯类化合物占电解液的质量百分数。本发明的电解液能够构建低阻抗、高稳定性的SEI膜，有效解决电池动力学性能差和循环寿命短的问题。