Ultra-high-temperature safe lithium ion battery electrolytic solution and lithium ion battery using electrolytic solution

Abstract

The invention discloses an ultrahigh-temperature safe lithium ion battery electrolytic solution and a lithium ion battery using the electrolytic solution. The electrolytic solution comprises 10-15% ofa lithium salt, 1-5% of a high-temperature film-forming additive, 1-10% of a flame-retardant additive and the balance of an organic solvent, wherein the lithium salt is one or a mixture of more thantwo of hexafluorophosphoric acid, lithium bis (fluorosulfonyl) imide or lithium bis (trifluoromethylsulfonyl) imide, the organic solvent is formed by mixing carbonic ester, carboxylic ester and a fluoroether solvent according to a certain proportion, the carbonic ester accounts for 30%-70% of the total amount of the lithium ion battery electrolytic solution, the carboxylic ester accounts for 0%-10% of the total amount of the lithium ion battery electrolytic solution, and the fluoroether accounts for 0%-10% of the total amount of the lithium ion battery electrolytic solution. According to the invention, the electrolytic solution disclosed by the invention is a high-temperature solvent and lithium salt with excellent thermal stability, and a film-forming additive with excellent film-formingthermal stability and a proper flame-retardant additive are added to realize the flame-retardant effect of the electrolytic solution; and the lithium ion battery disclosed by the invention can be normally used under the ultrahigh temperature condition of 100 DEG C while the battery has excellent safety performance.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to an ultra-high temperature safe lithium ion battery electrolyte and a lithium ion battery using the electrolyte. [0002] technical background [0003] In order to cope with the increasingly severe environmental pollution and energy crisis, people's calls for green energy are constantly rising. Among them, lithium-ion secondary batteries are widely used in various portable electronic applications due to their long working life, high working voltage and energy density, and low environmental pollution. With the expansion of the application field of lithium-ion batteries, in some application environments, it is required that the batteries can be used normally at a temperature of 80°C or higher. The current commercial lithium-ion batteries are limited by their solvent system, lithium salt stability, and additive film-forming instability. Long-term storage of ...

AI Technical Summary

Problems solved by technology

Patent application number 200710028835.8 passed in commercial carbonate-based electrolyte (1mol / L LiPF 6 , DMC:EC:EMC=1:1:1) to prepare a kind of flame retardant electrolyte by adding different contents of phosphorus-containing organic compounds. Since most of the phosphorus-containing compounds have relatively large molecular The amount will increase the viscosity of the lithium-ion electrolyte, thereby reducing the ion conductivity, which has a greater negative impact on the rate performance of the lithium-ion battery

[0007] In addition to adding additives, there is another type of research to improve battery safety by increasing the concentration of lithium salts. Patent application No. 201710141187.0 discloses a method of using high-concentration lithium salts (greater than 3.0mol / L LiTFSI) dissolved in ether solvents to prepare non-toxic lithium salts. Combustible lithium-sulfur battery electrolyte, this method can effectively reduce the content of flammable solvents, thereby improving the thermal stability of the electrolyte, but the viscosity of the high-concentration lithium salt system is relatively high, and the ion conductivity drops sharply at low temperatures, which cannot meet the discharge requirements. performance requirements

[0008] In summary, currently by partially replacing LiPF 6 The method to improve the thermal stability of the electrolyte is a commonly used method to improve the high temperature performance of the electrolyte. It is difficult to achieve normal use at 100°C only through this method.

At the same time, there are few reports on lithium-ion batteries that can achieve ultra-high temperature discharge performance and high safety.

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