Electrolyte for flexible-package lithium ion secondary batteries and battery with electrolyte

Abstract

The invention belongs to the technical field of lithium ion secondary batteries, and particularly relates to electrolyte for flexible-package lithium ion secondary batteries. The electrolyte comprises organic solvent, lithium salt and additives. The additives include additive A, additive B and additive C. The additive A is tert-amylbenzene and / or tert-butylbenzene, and the weight percentage of the additives A in the electrolyte is 5-10%. The additive B is at least one of malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelaic dinitrile and sebaconitrile, and the weight percentage of the additive B in the electrolyte is 1-8%. The additive C is fluoroethylene carbonate, and the weight percentage of the additive C in the electrolyte is 2-10%. Compared with the prior art, the electrolyte has the advantages that the additive A, the additive B and the additive C are combined in the high-voltage-design flexible-package lithium ion secondary batteries, good circulating performance and high temperature storage performance of the batteries are guaranteed, and meanwhile, the batteries are enabled to have good anti-overcharge performance.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion secondary batteries, and in particular relates to an electrolyte solution for a soft-package lithium-ion secondary battery and a soft-package lithium-ion secondary battery containing the electrolyte. Background technique [0002] As an environmentally friendly secondary battery, lithium-ion secondary batteries have been widely used in portable devices such as mobile phones, video cameras, and notebook computers. However, with the development of modern society, many portable devices are moving toward intelligence and multi-function. In order to meet their capacity and power requirements and ensure their sufficient use time, the secondary battery as its power source must have more high energy density. [0003] In order to pursue high energy density, the flexible packaging lithium-ion secondary batteries currently on the market are mainly based on LiCoO 2 As the positive active material, some b...

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Problems solved by technology

[0005] Among the above three methods, the first two methods treat the symptoms but not the root cause, they only avoid battery overcharging from the circuit point of view, and the second method is mainly used in steel shell and aluminum shell batteries, and it is difficult to apply to soft-pack lithium-ion secondary batteries middle

The overcharge protection additives mentioned in the third method are currently commonly used biphenyl (BP) and cyclohexylbenzene (CHB). Although these two additives can improve the overcharge safety of lithium-ion secondary batteries to a certain extent However, it will seriously affect the rate performance and cycle performance of the battery, especially in the battery designed for high voltage. Further promotion and application of high-voltage flexible packaging lithium-ion secondary batteries

Although the technical solutions disclosed in these two patent applications can achieve the purpose of the invention to a certain extent, both of them sacrifice the rate performance, cycle performance or high-temperature storage performance of the battery

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