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CN-120718574-B - Adhesive, negative plate and secondary battery

CN120718574BCN 120718574 BCN120718574 BCN 120718574BCN-120718574-B

Abstract

The invention provides an adhesive, a negative plate and a secondary battery, wherein the adhesive comprises alkali metal ions, C5-C10 acrylic ester structural units, propenyl structural units containing polar groups and allyl ether structural units, and the glass transition temperature of the adhesive is 43-86 ℃. The binder can effectively improve the cycle stability of the secondary battery.

Inventors

  • WU LI
  • CHENG YIFENG
  • XU SIXI
  • JIA BAOQUAN
  • WANG JIAN

Assignees

  • 深圳好电科技有限公司

Dates

Publication Date
20260512
Application Date
20250827

Claims (7)

  1. 1. The adhesive is characterized by comprising alkali metal ions, C5-C10 acrylic ester structural units, polar group-containing propenyl structural units and allyl ether structural units, wherein the glass transition temperature of the adhesive is 43-86 ℃, the C5-C10 acrylic ester structural units are from C5-C10 acrylic ester monomers, the glass transition temperature of the C5-C10 acrylic ester monomers is-65-35 ℃, the polar group-containing propenyl structural units are from polar group-containing propenyl monomers, the glass transition temperature of the polar group-containing propenyl structural units is 80-180 ℃, the mass ratio of the alkali metal ions, the C5-C10 acrylic ester structural units, the polar group-containing propenyl structural units and the allyl ether structural units is (1-10): (40-60): (10-30): (5-20), the polar group-containing propenyl structural units are acrylamide structural units, and the adhesive is prepared by at least one of lithium ions: After the alkali metal ion source and the C5-C10 acrylic ester monomer are subjected to a first polymerization reaction, adding the propenyl monomer containing polar groups into a reaction system and initiating a second polymerization reaction, and then adding the allyl ether monomer into the reaction system and initiating a third polymerization reaction to obtain the adhesive.
  2. 2. The binder of claim 1 wherein the weight average molecular weight of the binder is 2 x 10 5 g/mol～5×10 5 g/mol.
  3. 3. The adhesive of claim 1, wherein the C5-C10 acrylate structural units comprise at least one of n-pentyl acrylate structural units, isopentyl acrylate structural units, hexyl acrylate structural units, 2-ethylhexyl acrylate structural units; And/or the allyl ether structural unit comprises at least one of a methyl allyl polyoxyethylene ether structural unit, an allyl ethoxy ether structural unit, a methoxy polyethylene glycol allyl ether-100 structural unit, a methoxy polyethylene glycol allyl ether-200 structural unit, a methoxy polyethylene glycol allyl ether-300 structural unit and a methoxy polyethylene glycol allyl ether-400 structural unit.
  4. 4. The adhesive of claim 3, wherein the acrylamide-based structural unit comprises at least one of an N, N-dimethylacrylamide structural unit, an N, N-diethylacrylamide structural unit, an N-isopropylacrylamide structural unit, an N- (2-hydroxyethyl) acrylamide structural unit, an acrylamide structural unit; and/or the acrylic structural unit comprises at least one of an acrylic structural unit, a methacrylic structural unit and an itaconic structural unit.
  5. 5. A negative electrode sheet, characterized in that the negative electrode sheet comprises the binder according to any one of claims 1 to 4.
  6. 6. The negative electrode sheet of claim 5, further comprising a negative electrode active material comprising natural graphite.
  7. 7. A secondary battery comprising the binder according to any one of claims 1 to 4, or the negative electrode sheet according to claim 5 or 6.

Description

Adhesive, negative plate and secondary battery Technical Field The invention belongs to the technical field of secondary batteries, and relates to an adhesive, in particular to an adhesive, a negative electrode plate and a secondary battery. Background Secondary batteries are widely used in consumer electronics, electric vehicles, energy storage systems, etc., such as sodium ion batteries, lithium ion batteries, potassium ion batteries, etc., due to their recyclable characteristics. However, in the cycle charge and discharge process of the secondary battery, the negative electrode active material undergoes a large volume change along with the intercalation and deintercalation of active ions, and if the mechanical strength of the binder is insufficient, the negative electrode active layer is peeled off to affect the cycle stability of the secondary battery, and in the application of the negative electrode active material, natural graphite is used as a common material, and in the charge and discharge process, the natural graphite may react irreversibly with active ions (such as sodium ions or lithium ions) to cause the loss of the active ions, the battery capacity is reduced, and the cycle life of the secondary battery is further affected. Disclosure of Invention In view of the above-described drawbacks, the present invention provides a binder that can effectively improve the cycle stability of a secondary battery. The invention provides a negative electrode plate, which is applied to a secondary battery because the negative electrode plate comprises the binder, so that the cycle stability of the secondary battery can be effectively improved. The invention provides a secondary battery, which comprises the binder or the negative plate and has high cycle stability. The first aspect of the invention provides a binder, which comprises alkali metal ions, a C5-C10 acrylic ester structural unit, a propenyl structural unit containing a polar group and an allyl ether structural unit, wherein the glass transition temperature of the binder is 43-86 ℃. The binder as described above, wherein the weight average molecular weight of the binder is 2x 10 5g/mol～5×105 g/mol. The adhesive is characterized in that the mass ratio of the alkali metal ion to the C5-C10 acrylic ester structural unit to the polar group-containing propenyl structural unit to the allyl ether structural unit is (1-10): (40-60): (10-30): (5-20). The adhesive is characterized in that the C5-C10 acrylic ester structural unit is from a C5-C10 acrylic ester monomer, and the glass transition temperature of the C5-C10 acrylic ester monomer is-65 ℃ to-35 ℃. The adhesive, wherein the polar group-containing propenyl structural unit is derived from polar group-containing propenyl monomers, and the glass transition temperature of the polar group-containing propenyl monomers is 80-180 ℃. A binder as described above, wherein the alkali metal ion is lithium ion or sodium ion; And/or the C5-C10 acrylic ester structural unit comprises at least one of n-amyl acrylate structural unit, isoamyl acrylate structural unit, hexyl acrylate structural unit and 2-ethylhexyl acrylate structural unit; and/or the propenyl structural unit containing polar groups comprises at least one of an acrylamide structural unit, an acrylonitrile structural unit and an acrylic structural unit; And/or the allyl ether structural unit comprises at least one of a methyl allyl polyoxyethylene ether structural unit, an allyl ethoxy ether structural unit, a methoxy polyethylene glycol allyl ether-100 structural unit, a methoxy polyethylene glycol allyl ether-200 structural unit, a methoxy polyethylene glycol allyl ether-300 structural unit and a methoxy polyethylene glycol allyl ether-400 structural unit. The adhesive as described above, wherein the acrylamide structural unit comprises at least one of an N, N-dimethylacrylamide structural unit, an N, N-diethylacrylamide structural unit, an N-isopropylacrylamide structural unit, an N- (2-hydroxyethyl) acrylamide structural unit, an acrylamide structural unit; and/or the acrylonitrile structural unit comprises at least one of an acrylonitrile structural unit, a methacrylonitrile structural unit and a 2-chloroacrylonitrile structural unit; and/or the acrylic structural unit comprises at least one of an acrylic structural unit, a methacrylic structural unit and an itaconic structural unit. A second aspect of the invention provides a negative electrode sheet comprising the binder of the first aspect. The negative electrode sheet as described above, wherein the negative electrode sheet further comprises a negative electrode active material comprising natural graphite. A third aspect of the present invention provides a secondary battery comprising the binder according to the first aspect, or the negative electrode sheet according to the second aspect. The binder comprises alkali metal ions, C5-C10 acrylic ester structural units, propenyl structural units contai