Electrolyte for lithium ion secondary battery and lithium ion secondary battery comprising the same

摘要

An electrolyte for a lithium ion secondary battery includes a non-aqueous organic solvent; a lithium salt; and a phosphonitrile fluoride trimer as an additive, and a lithium ion secondary battery comprising the same. The thickness increase rate of a lithium ion secondary battery including the electrolyte is reduced even when the battery is kept at a high temperature. Thus, the thermal stability and durability of the battery are prominently improved. The durability of the battery can be further improved by including a vinylene carbonate or ethylene carbonate group compound in the electrolyte.

主权项

1. An electrolyte for a lithium ion secondary battery comprising:
a non-aqueous organic solvent; a lithium salt; and a phosphonitrile fluoride trimer represented by a Chemical formula 1 below: wherein the amount of the phosphonitrile fluoride trimer of the Chemical formula 1 is 0.1 to 1 parts by weight based on 100 parts by weight of the total electrolyte, and the non-aqueous organic solvent comprises a carbonate compound and an aromatic hydrocarbon compound of the following Chemical formula 3: wherein, R is halogen or an alkyl group having 1 to 10 carbons and q is an integer of 0 to 6; wherein the amount of the compound of chemical formula 3 is 50 volume % or less; wherein the ratio of the carbonate compound to the aromatic hydrocarbon compound is 1:1 to 30:1 and wherein the carbonate compound is a mixture of a cyclic type carbonate and a chain type carbonate and the mixing ratio of the cyclic type carbonate to the chain type carbonate is 1:1 to 1:9 in volume ratio.