Search

CN-116315105-B - Electrolyte, secondary battery and electric equipment

CN116315105BCN 116315105 BCN116315105 BCN 116315105BCN-116315105-B

Abstract

The invention relates to the technical field of batteries, in particular to electrolyte, a secondary battery and electric equipment. The electrolyte comprises an additive, wherein the structural formula of the additive is shown as formula I: R 1 is selected from substituted or unsubstituted C1-C5 alkyl; R 2 is selected from at least one of substituted or unsubstituted allyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl, R 3 is selected from substituted or unsubstituted allyl, And Wherein R 4 is selected from C3-C6 alkylene, R 5 is selected from C1-C4 alkyleneoxy, X comprises at least one of substituted or unsubstituted sulfonate, acrylate and fluorocarboxylate groups, and Y comprises at least one of amide, carboxylate and substituted or unsubstituted sulfonate groups. The additive can inhibit the impedance from increasing in the circulation process, and improve the circulation stability, circulation, high-temperature storage gas production and the like of the battery.

Inventors

  • LI MINGLIANG
  • FU JIALE
  • ZHANG JIANWEI
  • QIAO FEIYAN
  • CHU CHUNBO

Assignees

  • 欣旺达电动汽车电池有限公司

Dates

Publication Date
20260508
Application Date
20230426

Claims (10)

  1. 1. The electrolyte is characterized by comprising an additive, wherein the structural formula of the additive is shown as formula I: ; R 1 is selected from substituted or unsubstituted C1-C5 alkyl; R 2 is selected from at least one of substituted or unsubstituted C2-C5 alkenyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl; R 3 is selected from at least one of the following structural formulas: (1) ; (2) r 6 is selected from substituted or unsubstituted C1-C5 alkyl and substituted or unsubstituted aryl; (3) R 7 is selected from H and methyl; (4) R 9 and R 10 are each independently selected from C2-C4 alkenyl groups; wherein n is an integer of 3 to 6, and m is an integer of 1 to 4.
  2. 2. The electrolyte of claim 1 wherein in R 1 , the substituted group comprises a halogen atom; In R 2 , the substituted group comprises at least one of C1-C3 alkyl and halogen atoms.
  3. 3. The electrolyte of claim 1 wherein the additive comprises at least one of the following structural compounds: 、 、 、 、 、 、 。
  4. 4. the electrolyte according to any one of claims 1 to 3, wherein the additive is used in an amount of 0.2 to 6% by mass of the total mass of the electrolyte.
  5. 5. The electrolyte of claim 1, wherein the electrolyte has a conductivity of 7.5 to 9ms/cm at 25 ℃.
  6. 6. The electrolyte of claim 1 wherein the electrolyte comprises a solvent that satisfies at least one of the following conditions: (1) The solvent comprises fluoroethylene carbonate and ethylmethyl carbonate; (2) The mass of fluoroethylene carbonate is 5% -15% based on the total mass of the solvent; (3) The mass ratio of fluoroethylene carbonate to methyl ethyl carbonate is 1 (4-9).
  7. 7. A secondary battery comprising a positive electrode sheet, a negative electrode sheet, a separator, and the electrolyte of any one of claims 1 to 6.
  8. 8. The secondary battery according to claim 7, wherein the negative electrode sheet includes a negative electrode active material including a silicon-carbon composite material formed of a silicon-based material including at least one of elemental silicon, silicon oxygen, and a silicon metal compound, and a carbon-based material including graphite.
  9. 9. The secondary battery according to claim 7, wherein the positive electrode sheet includes a positive electrode active material having a chemical formula including Li a Ni x Co y Mn z M e O 2 , wherein 0.9≤a≤ 1.1,0.6≤x≤0.9, 0< y≤0.2, 0≤z≤0.2, 0≤e≤0.1, and x+y+z+e=1, m including at least one of Al, zr, sr, ti, B, mg, sn, W, Y, ba, nb, mo, ta, si, la, er, nd, gd, ce.
  10. 10. An electric device characterized by comprising the secondary battery according to any one of claims 7 to 9.

Description

Electrolyte, secondary battery and electric equipment Technical Field The invention relates to the technical field of batteries, in particular to electrolyte, a secondary battery and electric equipment. Background With the increasing total loading of lithium ion power batteries in electric vehicles, higher requirements are being placed on the energy density of lithium ion power batteries. The silicon negative electrode system has the advantages of high gram capacity and low potential, and is one of specific directions for improving the energy density of the battery. However, practical applications of silicon anode systems still face problems such as large volume changes during cycling. Unlike the intercalation/deintercalation mechanism of the combination of graphite and lithium, the action mechanism of the silicon negative electrode and lithium is alloying/dealloying reaction, and simultaneously, the silicon negative electrode and lithium are accompanied by great volume change, so that the silicon particle structure is pulverized or destroyed, and the silicon negative electrode is separated from a conductive agent to cause the failure of a conductive network, thereby preventing the commercialized application process of a silicon negative electrode system. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide an electrolyte which can react with a silicon anode system to form a protective silicon ether net structure, form a stable interface layer on the surface of the anode, improve the circulation stability and inhibit gas production. Another object of the present invention is to provide a secondary battery comprising the above electrolyte. Still another object of the present invention is to provide an electric device, which includes the above secondary battery. In order to achieve the above object of the present invention, the following technical solutions are adopted: the electrolyte comprises an additive, wherein the structural formula of the additive is shown as formula I: R 1 is selected from substituted or unsubstituted C1-C5 alkyl; R 2 is selected from at least one of substituted or unsubstituted C2-C5 alkenyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl; R 3 is selected from substituted or unsubstituted C2-C5 alkenyl, AndAt least one of (a) and (b); wherein R 4 is selected from C3-C6 alkylene, R 5 is selected from C1-C4 alkyleneoxy, X comprises at least one of substituted or unsubstituted sulfonate, acrylate and fluorocarboxylate, and Y comprises at least one of amide, carboxylate and substituted or unsubstituted sulfonate. Further, in the R 1, the substituted group includes a halogen atom; in the R 2, the substituted group comprises at least one of C1-C3 alkyl and halogen atoms; in the X or the Y, the substituted group comprises at least one of C1-C3 alkyl, phenyl, fluorophenyl and halogen atoms. Further, the additive comprises at least one of the following structural compounds: further, the dosage of the additive is 0.2% -6% of the total mass of the electrolyte. Further, at 25 ℃, the conductivity of the electrolyte is 7.5-9 mS/cm. Further, the electrolyte includes a solvent including fluoroethylene carbonate and ethylmethyl carbonate. Further, in the electrolyte, the mass of fluoroethylene carbonate is 5% -15% based on the total mass of the solvent. Further, in the electrolyte, the mass ratio of fluoroethylene carbonate to methyl ethyl carbonate is 1 (4-9). The invention also provides a secondary battery, which comprises a positive plate, a negative plate, a diaphragm and the electrolyte. Further, the negative electrode sheet comprises a negative electrode active material, wherein the negative electrode active material comprises a silicon-carbon composite material formed by a silicon-based material and a carbon-based material, the silicon-based material comprises at least one of a silicon simple substance, silicon oxygen and a silicon metal compound, and the carbon-based material comprises graphite. Further, the positive electrode sheet includes a positive electrode active material having a chemical formula including Li aNixCoyMnzMeO2, wherein 0.9≤a≤ 1.1,0.6≤x≤0.9, 0< y≤0.2, 0≤z≤0.2, 0≤e≤0.1, and x+y+z+e=1, m including at least one of Al, zr, sr, ti, B, mg, sn, W, Y, ba, nb, mo, ta, si, la, er, nd, gd, ce. The invention also provides electric equipment, which comprises any one of the secondary batteries. Compared with the prior art, the invention has the beneficial effects that: (1) The electrolyte adopts a specific additive, on one hand, the electrolyte can chemically react with the surface of a silicon negative electrode system to form a protective silicon ether net structure, and a stable interface layer is formed on the surface of the negative electrode, so that the circulation stability is improved and the gas production is inhibited; (2) The silyl ether structure in the additive adopted in the electrolyte