A kind of lithium ion battery electrolyte for removing water and reducing acid

Abstract

The invention relates to the technical field of lithium-ion battery electrolyte additives, in particular to lithium-ion battery electrolyte with the dehydration function and the acidity reduction function. The lithium-ion battery electrolyte with the dehydration function and the acidity reduction function comprises electrolyte lithium salt, a non-aqueous solvent and an additive, wherein the additive is any one of N,N'-diisopropylcarbondiimide and 1-(3-dimethyllaminopropyl)-3-ethyl carbodiimide or the mixture obtained by mixing the N,N'-diisopropylcarbondiimide and 1-(3-dimethyllaminopropyl)-3-ethyl carbodiimide in any proportion, and the mass of the added additive is 0.01%-1.0% of the total mass of the electrolyte. Compared with the prior art, the lithium-ion battery electrolyte with the dehydration function and the acidity reduction function has the advantages that water in the electrolyte and the acidity of the electrolyte can be effectively controlled, sediment is avoided during storage, and the quality of the electrolyte is guaranteed.

Description

technical field [0001] The invention relates to the technical field of electrolyte additives for lithium-ion batteries, in particular to a lithium-ion battery electrolyte for removing water and reducing acid. Background technique [0002] Non-aqueous secondary lithium-ion battery electrolytes are generally composed of electrolyte lithium salts, organic solvents, and additives. The quality of the electrolyte is crucial to the electrochemical performance of lithium-ion batteries. At present, the commercial electrolyte lithium salt is mainly LiPF 6 , which is very sensitive to water and can react with trace amounts of water in the electrolyte: LiPF 6 + H 2 O→LiF+HF+POF 3 , The working temperature of lithium batteries is generally -30-60°C, and the reaction becomes more intense in a high temperature environment. The generated HF not only corrodes the electrode material, but also destroys the solid electrolyte interface film, thereby rapidly deteriorating the performance of ...

AI Technical Summary

Problems solved by technology

[0003] The electrolyte additives that have been reported to have the effect of removing water and acid are as follows: 1) A12O3 , MgO, BaO and other oxides, which can react with a small amount of HF in the electrolyte to reduce the content of HF, but the removal rate of these substances is slow, and the solubility of these oxides in the electrolyte Small, so it is difficult to prevent HF from destroying battery performance; 2) Acid anhydride compounds, which can remove HF quickly, but at the same time produce other acidic substances that damage battery performance; 3) Silazane compounds, Such as hexamethyldisilazane (HMDS) and heptamethyldisilazane (H7DMS), which have a good effect on suppressing moisture and acidity in the electrolyte, for example, hexamethyldisilazane reacts with water It can generate trimethylsilanol, hexamethyldioxysilane and NH3, and the generated NH3 further interacts with HF to achieve the purpose of inhibiting moisture and reducing acidity , but the experiment found that the electrolyte using silazane compound as a stabilizer tends to have white precipitates during storage, especially under high temperature conditions

As another example, U.S. Patent (Patent No.: 6077628) discloses a new type of additive cyclohexylcarbodiimide (DCC), which is added to the electrolyte as an additive for removing water and reducing acid. acid effect, but the product N, N-dicyclohexylurea produced by the reaction is also insoluble in the electrolyte, and precipitation is also formed

The occurrence of this problem seriously shortens the storage time of the electrolyte and adversely affects the performance of the battery

Images