Lithium secondary battery electrolyte and lithium secondary battery thereof

Abstract

The invention relates to lithium secondary battery electrolyte and a lithium secondary battery thereof. The lithium secondary battery electrolyte comprises an organic solvent, conductive lithium salt,a benzonitrile compound and additives, the benzonitrile compound has a structure as shown in a formula I, and R is any one of F, substituted or unsubstituted C1-6 alkyl, substituted or unsubstitutedC6-26 aryl, C1-4 nitrile groups and C1-6 alkenyl. The benzonitrile compound as shown in the structural formula (I) is added into the electrolyte, transition metal ions can be combined, positive electrode material surfaces are improved, decomposition of the electrolyte is inhibited, bloating is further inhibited, and the high-temperature performance of the battery is improved. By adding the lithium-containing additives, the low-temperature performance of the battery can be improved, and the cycling performance of the battery can be remarkably improved.

Description

technical field [0001] The invention relates to the technical field of lithium secondary batteries, in particular to an electrolyte solution for lithium secondary batteries and the lithium secondary battery. Background technique [0002] Since the commercialization of lithium secondary batteries, due to its high specific energy and good cycle performance, it has been widely used in digital, energy storage, power, military aerospace and communication equipment and other fields. [0003] At present, commercial lithium secondary battery electrolytes mainly use linear and cyclic carbonates as solvents, LiPF 6 As an electrolyte, it provides the necessary guarantee for the shuttle of lithium ions between the positive and negative electrodes of the battery. However, LiPF 6 Poor thermal stability, prone to the following decomposition reactions: LiPF 6 →LiF+PF 5 , PF 5 +H 2 O→2HF+POF 3 . Generated PF 5 The reaction with trace impurities in the electrolyte causes the chroma o...

AI Technical Summary

Problems solved by technology

For example, the invention patent CN105140562A improves battery cycle and high-temperature performance by adding phthalonitrile derivatives to the electrolyte, and reduces flatulence, but most of the battery capacity retention and recovery rates after high-temperature storage are lower than 80%, indicating that battery damage is relatively serious. Big

CN104051786A uses halogenated benzonitrile compounds as electrolyte additives to improve the high-voltage cycle performance and high-low temperature performance of the battery, but does not specifically list the effect of the additive on the high-low temperature performance of the battery, and its cycle performance improvement effect is not ideal

Images