Search

CN-119954700-B - Dithioamino compound and its use in electrolytes

CN119954700BCN 119954700 BCN119954700 BCN 119954700BCN-119954700-B

Abstract

The application discloses a dithioamino compound and application thereof in electrolyte, and belongs to the technical field of batteries. The dithioamino compound provided by the application has lower reduction potential, can be decomposed and form a stable SEI film in preference to an organic solvent when being applied to electrolyte and a corresponding secondary battery, thereby helping to prevent the organic solvent from being reduced by a large amount of electrons on the surface of a negative electrode, and meanwhile, the unsaturated bond of the dithioamino compound can be polymerized and crosslinked to generate a polymer with a high polymer in the film forming process, thereby helping to form a more compact and stable film and improving the mechanical strength and chemical stability of the SEI layer. Therefore, when the dithioamino compound of the present application is used for preparing a secondary battery, the obtained secondary battery has excellent cycle performance and low-temperature storage performance.

Inventors

  • LI WEIQI
  • YU SHU
  • QIU ZHIJUN
  • LI MINGLIANG
  • CAI TAOTAO

Assignees

  • 欣旺达动力科技股份有限公司

Dates

Publication Date
20260508
Application Date
20250122

Claims (8)

  1. 1. A dithioamino compound, characterized in that the dithioamino compound comprises any one of formulas 1 to 10: 。
  2. 2. an electrolyte comprising a metal salt, an organic solvent, an additive, and the dithioamino compound of claim 1.
  3. 3. The electrolyte according to claim 2, wherein the mass percentage of the dithioamino compound is 1% -3% based on the electrolyte.
  4. 4. The electrolyte according to claim 3, wherein the mass ratio of the dithioamino compound to the additive is 1 (2-5).
  5. 5. The electrolyte according to claim 3, wherein the molar concentration of the metal salt in the electrolyte is 0.5mol/L to 2mol/L.
  6. 6. The electrolyte of claim 2, wherein the organic solvent comprises at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, methylethyl carbonate, propylene carbonate, methylpropyl carbonate; And/or the additive comprises at least one of fluoroethylene carbonate, ethylene glycol dimethyl ether, trifluoro-phosphate, vinylene carbonate, 1, 3-propane sultone and methyl methacrylate; And/or the metal salt comprises at least one of MClO 4 、MBF 4 、MPF 6 、MAsF 6 、MBOB、MFSI、MTFSI、MPF 2 O 2 、MCF 3 SO 3 、MCF 3 SO 3 、MPF 2 (C 2 O 4 ), wherein M comprises any one of Li, na and K.
  7. 7. A secondary battery comprising a positive electrode sheet, a negative electrode sheet, and the electrolyte according to any one of claims 2 to 6.
  8. 8. An electric device comprising the secondary battery according to claim 7.

Description

Dithioamino compound and its use in electrolytes Technical Field The application belongs to the technical field of batteries, and particularly relates to a dithioamino compound and application thereof in electrolyte. Background Film forming additives play a vital role in lithium ion batteries, and can improve the cycle life, capacity retention and safety of the battery by forming a stable SEI layer or CEI layer on the surface of an electrode. The most commonly used film forming additive today is fluoroethylene carbonate (FEC). However, FEC is poor in stability under high pressure (> 4.2V) and is prone to decomposition reaction on the surface of the positive electrode, resulting in increased decomposition of the electrolyte and formation of harmful by-products. In addition, HF is generated in the decomposition process, and the HF is taken as a substance with extremely strong acidity, so that the anode material is severely corroded, transition metal is dissolved out, and the stability of the battery is reduced. Meanwhile, the existing film forming additive cannot effectively improve the stability of the secondary battery at low temperature. Disclosure of Invention The application aims to solve the technical problem that the film forming additive in the prior art cannot effectively realize the excellent cycle performance and low-temperature storage performance of a secondary battery, and provides a dithioamino compound and application thereof in electrolyte. To achieve the above object, in a first aspect of the present application, there is provided a dithioamino compound having a structural formula as shown in formula a: Wherein R 1 and R 2 are each independently selected from any one of fluoroalkyl, fluoroaryl, sulfonamide, cyano, vinyl, pyrazolyl, ester, aldehyde, ketone, and ether. As an embodiment of the present application, the fluoroalkyl group includes any one of fluoromethyl group, fluoroethyl group, fluorobutyl group, fluoroisobutyl group. As an embodiment of the present application, the fluoroaromatic group includes a fluorophenyl group. As an embodiment of the present application, the ketone group includes an ethanone group. As an embodiment of the present application, the ether group includes a methyl ether group. As an embodiment of the present application, the dithioamino compound includes any one of the formulas 1 to 10: In a second aspect of the present application, there is provided an electrolyte comprising a metal salt, an organic solvent, an additive and a dithioamino compound of the present application. As an embodiment of the application, the mass percent of the dithioamino compound is 1% -3% based on the electrolyte. As an embodiment of the present application, the mass ratio of the dithioamino compound to the additive is 1: (2~5)。 as an embodiment of the application, the molar concentration of the metal salt in the electrolyte is 0.5 mol/L-2 mol/L. As an embodiment of the present application, the organic solvent includes at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, methylethyl carbonate, propylene carbonate, methylpropyl carbonate, methylethyl carbonate, and methylisobutyl carbonate. As an embodiment of the present application, the additive includes at least one of fluoroethylene carbonate, ethylene glycol dimethyl ether, trifluorophosphate, vinylene carbonate, 1, 3-propane sultone, and methyl methacrylate. As an embodiment of the application, the metal salt comprises at least one of MClO4、MBF4、MPF6、MAsF6、MBOB、MFSI、MTFSI、MPF2O2、MCF3SO3、MCF3SO3、MPF2(C2O4), wherein M comprises any one of Li, na and K. In a third aspect of the present application, there is provided a secondary battery comprising the above electrolyte. In a fourth aspect of the present application, there is provided an electric device including the above secondary battery. Compared with the prior art, the application has the beneficial effects that: The dithioamino compound provided by the application has a lower reduction potential in the first aspect, can be decomposed and form a stable SEI film in preference to an organic solvent when being applied to electrolyte and a corresponding secondary battery, thereby helping to prevent the organic solvent from being reduced by a large amount of electrons on the surface of a negative electrode, and can be polymerized and crosslinked to generate a polymer with a high polymer in the film forming process, so that a more compact and stable film is formed, the mechanical strength and the chemical stability of the SEI layer are improved, and in the third aspect, sulfur elements in the dithioamino compound provided by the application can generate a compound rich in sulfur and oxygen, so that the generated SEI film is more flexible. Under the action of the three aspects, when the electrolyte added with the dithioamino compound is used for preparing the secondary battery, the obtained secondary battery has excellent cycle performance and low-temperature stor