Lithium-ion secondary battery and electrolyte thereof

Abstract

The invention discloses a lithium-ion secondary battery and an electrolyte thereof. The electrolyte comprises a solvent, lithium salt and a film forming additive, wherein the solvent comprises a first solvent and a second solvent; the first solvent comprises linear carboxylic ester and ethylene carbonate; the second solvent is one or more of ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate and propylene carbonate; and the film forming additive is one or more of fluoroethylene carbonate, vinylene carbonate, 1,3-propane suhone, succinonitrile, adiponitrile, lithium bis(oxalato)borate, and lithium oxalyldifluoroborate. Due to the collocation of linear carboxylic ester and ethylene carbonate, a solvent system with a higher dielectric constant and low viscosity is obtained; the film forming additive improves poor compatibility between linear carboxylic ester and graphite; and finally the lithium-ion secondary battery adopting the electrolyte presents high-power discharge capacity, excellent high-temperature cycling stability and low-temperature charge and discharge properties.

Description

technical field [0001] The invention relates to a lithium-ion secondary battery, in particular to a non-aqueous lithium-ion secondary battery electrolyte with higher electrical conductivity and lower viscosity. Background technique [0002] Lithium-ion secondary batteries have become one of the most widely used secondary batteries due to their advantages such as high voltage and high energy density. However, with the continuous development of portable electronic devices towards miniaturization and long standby time, and the use of high-power and high-energy devices such as electric bicycles and electric vehicles, lithium-ion secondary batteries as power sources have low-temperature charge-discharge performance, power The need to increase density and energy density is becoming more and more urgent. [0003] As an important part of the lithium-ion secondary battery, the electrolyte plays the role of transmitting lithium ions and conducting current between the positive and neg...

AI Technical Summary

Problems solved by technology

High dielectric constant and low-viscosity solvents are necessary conditions for the preparation of high-conductivity electrolytes. Since the use of cyclic carbonates or linear carbonates alone as solvents cannot meet the requirements of high-conductivity electrolytes, the current commercial lithium The mixed solvent of these two types of carbonates is generally used in ion secondary batteries, and an electrolyte with a conductivity value of 6~7mS / cm can be obtained generally, but this cannot fully meet the requirements of lithium ion secondary batteries for the conductivity of the electrolyte. , especially the low temperature charge and discharge characteristics of the battery are poor

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