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CN-122025819-A - Electrolyte and battery

CN122025819ACN 122025819 ACN122025819 ACN 122025819ACN-122025819-A

Abstract

The invention relates to the field of batteries, in particular to electrolyte and a battery. The electrolyte is used in a solvent formula with a specific proportion, the additive is preferentially used in a battery activation stage to form a solid electrolyte interface film on the surface of an electrode in preference to the solvent, wherein the first additive can be preferentially used for contacting trace water in the electrolyte, the content of HF in the circulation process is reduced, meanwhile, the electrolyte can be matched with other additives to form a CEI film rich in inorganic components on the surface of the electrode, and the stable CEI film can be used for reducing side reactions on the surface of the electrode, prolonging the cycle life of the battery, and meanwhile, the ionic conductivity in the electrolyte is improved due to the addition of a low-viscosity solvent, so that the ohmic resistance of the battery is reduced, and meanwhile, the electrolyte can meet the working condition under high multiplying power due to the uniformity of the CEI film and low interface impedance.

Inventors

  • DAI CHANGSONG
  • SHI CHAOQUN
  • ZHAO LI
  • YANG YIRAN
  • ZHANG WEI
  • ZHANG YANJIANG
  • CHEN DAOMING
  • CHEN YAN

Assignees

  • 哈尔滨工业大学

Dates

Publication Date
20260512
Application Date
20260403

Claims (10)

  1. 1. The electrolyte is characterized by comprising lithium salt, an organic solvent and an additive, wherein the additive comprises a first additive and a second additive, and the first additive comprises at least one of compounds shown as the following formulas I-eight; Wherein M is N, P, C or S, A is P or S, n and M are each independently integers of 0-1, R 1 ~R 4 is each independently a hydrogen atom, a halogen atom, an alkyl group of 1-8 carbon atoms, an alkoxy group, a cycloalkyl group or an amino group, and R 5 is a hydrogen atom, an alkyl group of 1-8 carbon atoms, an alkoxy group, a cycloalkyl group or an amino group.
  2. 2. The electrolyte according to claim 1, wherein the volume content of the first additive is 0.1% -5% based on the total volume of the electrolyte; and the volume content of the second additive is 1% -5% based on the total volume of the electrolyte.
  3. 3. The electrolyte of claim 1 wherein the second additive comprises at least one of fluoroethylene carbonate and vinylene carbonate.
  4. 4. The electrolyte of claim 1 wherein the additives further comprise a third additive; The third additive comprises a phosphorus-containing additive, wherein the phosphorus-containing additive comprises at least one of hexamethylphosphazene, hexamethylphosphoric triamide, trimethyl phosphite, triethyl phosphite and lithium dihydrogen phosphate.
  5. 5. The electrolyte according to claim 4, wherein the volume content of the third additive is 0.1% -5% based on the total volume of the electrolyte.
  6. 6. The electrolyte according to claim 1, wherein the volume content of the organic solvent is 85% -98% based on the total volume of the electrolyte.
  7. 7. The electrolyte of claim 1, wherein the organic solvent comprises at least two of a first organic solvent, a second organic solvent, and a third organic solvent; the first organic solvent comprises dimethyl carbonate and/or ethylmethyl carbonate; The second organic solvent comprises ethylene carbonate; the third organic solvent includes at least one of methyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl butyrate, methyl pivalate, ethyl lactate, methyl benzoate, acetonitrile, acrylonitrile, propionitrile, isobutyronitrile, succinonitrile, glutaronitrile, adiponitrile, 3- (trifluoromethyl) adiponitrile, and 1,3, 6-hexanetricarbonitrile.
  8. 8. The electrolyte according to claim 1, wherein the concentration of the lithium salt is 1 to 1.5mol/L based on the total volume of the electrolyte.
  9. 9. The electrolyte of claim 1 wherein the lithium salt comprises at least one of lithium hexafluorophosphate, lithium bis-fluorosulfonyl imide, and lithium bis-trifluoromethanesulfonyl imide.
  10. 10. A battery comprising the electrolyte according to any one of claims 1 to 9; The battery comprises a lithium ion battery.

Description

Electrolyte and battery Technical Field The invention relates to the field of batteries, in particular to electrolyte and a battery. Background With the popularization of new energy power electric vehicles, the demand for fast-charging power batteries is increasing. The development of battery materials is rapid, but there are some problems, in which the problems of unstable electrode interface, poor thermal stability and the like caused by electrolyte affect the quick charge performance and the cycle life of the battery, so a series of challenges are presented for electrolyte modification. The traditional electrolyte adopts Ethylene Carbonate (EC) solvent, EC can help electrolyte to form solid electrolyte interface film (SEI film is formed at the interface of the electrode, CEI film is formed at the interface of the anode), but the electrolyte is easy to polarize in the circulation process due to the problems of non-uniform formed solid electrolyte interface film, poor oxidation stability and the like, and can induce non-uniform deposition of Li + ions to generate lithium dendrite, so that the battery is invalid and even short-circuit is ignited, meanwhile, the formed solid electrolyte interface film is unstable, and can also lead the electrolyte to be decomposed continuously to generate gas on the surface of the electrode, so that the cycle life of the battery is shortened, and secondly, the traditional carbonate-based electrolyte has low ionic conductivity so as to be difficult to meet the long-time charge and discharge work of the battery under high multiplying power. Therefore, how to reduce the viscosity of the electrolyte to achieve the fast charge requirement is affected by the viscosity of the solvent, how to form a stable solid electrolyte interface film is affected by the viscosity of the electrolyte solvent, the additive content and the additive content of the additive, and the additive content are different, so that the factors further determine the deposition of lithium at the electrode interface, and the problems of gas production, internal resistance change and the like of the battery are generated, so that the electrolyte formula needs to be further improved. Disclosure of Invention The invention provides an electrolyte and a battery, wherein the electrolyte can form a solid electrolyte interface film which is rich in inorganic matters and stable on the surface of an electrode, and can prolong the service life of the battery to meet the quick charge requirement. The invention provides an electrolyte, which comprises lithium salt, an organic solvent and an additive, wherein the additive comprises a first additive and a second additive, and the first additive comprises at least one of compounds shown in the following formulas I-eight; Wherein M is N, P, C or S, A is P or S, n and M are each independently integers of 0-1, R 1~R4 is each independently a hydrogen atom, a halogen atom, an alkyl group of 1-8 carbon atoms, an alkoxy group, a cycloalkyl group or an amino group, and R 5 is a hydrogen atom, an alkyl group of 1-8 carbon atoms, an alkoxy group, a cycloalkyl group or an amino group. In some embodiments, the first additive is present in an amount of 0.1% -5% by volume based on the total volume of the electrolyte. In some embodiments, the volume content of the second additive is 1% -5% based on the total volume of the electrolyte. In some embodiments, the second additive comprises at least one of fluoroethylene carbonate, vinylene carbonate. In some embodiments, the additive further comprises a third additive. In some embodiments, the third additive comprises a phosphorous-containing additive comprising at least one of hexamethylphosphazene, hexamethylphosphoric triamide, trimethyl phosphite, triethyl phosphite, and lithium dihydrogen phosphate. In some embodiments, the volume content of the third additive is 0.1% -5% based on the total volume of the electrolyte. In some embodiments, the organic solvent is present in an amount of 85% -98% by volume based on the total volume of the electrolyte. In some embodiments, the organic solvent comprises at least two of a first organic solvent, a second organic solvent, and a third organic solvent. In some embodiments, the first organic solvent comprises dimethyl carbonate (DMC) and/or ethylmethyl carbonate (EMC). In some embodiments, the second organic solvent comprises Ethylene Carbonate (EC). In some embodiments, the third organic solvent includes at least one of Methyl Formate (MF), methyl Acetate (MA), ethyl Acetate (EA), methyl Propionate (MP), ethyl Propionate (EP), ethyl Butyrate (EB), methyl pivalate (MEP), ethyl Lactate (EL), methyl Benzoate (MB), acetonitrile (AN), acrylonitrile (ACN), propionitrile (PN), isobutyronitrile (IBN), succinonitrile (SN), glutaronitrile (GN), adiponitrile (ADN), 3- (trifluoromethyl) adiponitrile (ADN-CF 3), and 1,3, 6-Hexanetrinitrile (HTN). In some embodiments, the concentration of the lithium salt is 1 to 1.5mo