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CN-122000632-A - Separator for rechargeable lithium battery and rechargeable lithium battery including the same

CN122000632ACN 122000632 ACN122000632 ACN 122000632ACN-122000632-A

Abstract

A separator for a rechargeable lithium battery includes a porous substrate and a coating layer on at least one surface of the porous substrate. The coating layer includes a binder including a copolymer including a first structural unit including a unit derived from an aromatic unsaturated monomer, a second structural unit derived from a (meth) acrylic monomer including an alkyl group having 4 or more carbon atoms in a main chain of an ester portion, and a third structural unit derived from a sulfonic acid group-containing monomer. The first structural unit is included in an amount ranging from about 5mol% to about 80mol%, the second structural unit is included in an amount ranging from about 10mol% to about 40mol%, and the third structural unit is included in an amount ranging from about 5mol% to about 80mol%, based on 100mol% of the copolymer.

Inventors

  • XU DONGWAN
  • Jin Jiaren
  • JU ZIYAN

Assignees

  • 三星SDI株式会社

Dates

Publication Date
20260508
Application Date
20251107
Priority Date
20241107

Claims (15)

  1. 1. A separator for a rechargeable lithium battery, the separator comprising: a porous substrate, and A coating layer on at least one surface of the porous substrate, Wherein the coating layer comprises a binder, The binder includes a copolymer including a first structural unit including a unit derived from an aromatic unsaturated monomer, a second structural unit derived from a (meth) acrylic monomer including an alkyl group having 4 or more carbon atoms in a main chain of an ester moiety, and a third structural unit derived from a sulfonic acid group-containing monomer, and The first structural unit is included in an amount ranging from 5mol% to 80mol%, the second structural unit is included in an amount ranging from 10mol% to 40mol%, and the third structural unit is included in an amount ranging from 5mol% to 80mol%, based on 100mol% of the copolymer.
  2. 2. The separator of claim 1, wherein the binder is a particulate binder.
  3. 3. The separator of claim 1, wherein the binder has an average particle size D50 in the range of 500nm to 700 nm.
  4. 4. The separator of claim 1, wherein the copolymer is an adhesive binder.
  5. 5. The separator of claim 1, wherein the binder has a glass transition temperature in the range of 60 ℃ to 80 ℃.
  6. 6. The separator of claim 1, wherein the binder is included in an amount in the range of 1wt% to 100wt% of the coating layer.
  7. 7. The separator according to claim 1, wherein a sum of contents of the first structural unit, the second structural unit, and the third structural unit is 95mol% or more based on the copolymer.
  8. 8. The separator according to claim 1, wherein the unit derived from an aromatic unsaturated monomer is represented by the following chemical formula 1: Chemical formula 1: ; In the chemical formula 1, the chemical formula is shown in the drawing, R 1 and R 2 each independently comprise hydrogen or a substituted or unsubstituted C1 to C5 alkyl group, and Ar comprises a substituted or unsubstituted monocyclic or polycyclic C6 to C20 aryl group, The second structural unit is represented by the following chemical formula 4: Chemical formula 4: ; in the chemical formula 4, the chemical formula is shown in the drawing, R 7 and R 8 each independently comprise hydrogen or methyl, and L 2 comprises a substituted or unsubstituted, linear or branched C4 to C30 alkyl group, and The third structural unit is represented by any one of the following chemical formulas 5 to 7: Chemical formula 5: ; chemical formula 6: ; Chemical formula 7: ; in the chemical formulas 5 to 7, R 9 、R 10 、R 11 、R 12 、R 13 and R 14 each independently comprise hydrogen or C1 to C3 alkyl, Each of L 3 、L 5 and L 7 independently includes-C (=o) -, -C (=o) O-, -OC (=o) -, -O-, or-C (=o) NH-, L 4 、L 6 and L 8 each independently comprise a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C3 to C20 cycloalkylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C3 to C20 heterocyclyl group, A. b, c, d, e and f are each independently an integer in the range of 0 to 2, and In the chemical formula 6, the chemical formula is shown in the drawing, M comprises an alkali metal.
  9. 9. The separator of claim 1, wherein the first structural unit further comprises a unit derived from a (meth) acrylic monomer containing an alkyl group having 1 to 3 carbon atoms in the backbone of the ester moiety.
  10. 10. The separator according to claim 9, wherein the unit derived from a (meth) acrylic monomer containing an alkyl group having 1 to 3 carbon atoms in a main chain of an ester moiety is represented by the following chemical formula 3: Chemical formula 3: ; In the chemical formula 3, the chemical formula is shown in the drawing, R 5 and R 6 each independently comprise hydrogen or methyl, and L 1 comprises a substituted or unsubstituted, linear or branched C1 to C3 alkyl group.
  11. 11. The separator according to claim 9, wherein the unit derived from an aromatic unsaturated monomer and the unit derived from a (meth) acrylic monomer containing an alkyl group having 1 to 3 carbon atoms in the main chain of an ester moiety are included in a molar ratio in the range of 1:0.5 to 1:2.
  12. 12. The separator according to claim 9, wherein the unit derived from an aromatic unsaturated monomer is included in an amount ranging from 5mol% to 35mol%, the unit derived from a (meth) acrylic monomer containing an alkyl group having 1 to 3 carbon atoms in the main chain of an ester moiety is included in an amount ranging from 5mol% to 35mol%, the second structural unit is included in an amount ranging from 20mol% to 30mol%, and the third structural unit is included in an amount ranging from 10mol% to 60mol%, based on 100mol% of the copolymer.
  13. 13. The separator of claim 9, wherein the copolymer comprises: The units derived from aromatic unsaturated monomers are derived from one or more of styrene, alpha-methylstyrene, 4-butylstyrene, 4-butoxystyrene, halostyrenes, vinyltoluene and vinylnaphthalene; The unit derived from a (meth) acrylic monomer containing an alkyl group having 1 to 3 carbon atoms in the main chain of the ester moiety, is derived from one or more of methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and isopropyl (meth) acrylate; The second structural unit derived from one or more of 2-ethylhexyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate and isodecyl (meth) acrylate, and The third structural unit is derived from at least one of vinylsulfonic acid, allylsulfonic acid, styrenesulfonic acid, anetholsulfonic acid, (meth) acrylamidoalkanesulfonic acid, sulfoalkyl (meth) acrylate, and salts thereof.
  14. 14. The separator of claim 1, wherein the coating layer has a thickness in the range of 0.1-1.5 μιη.
  15. 15. A rechargeable lithium battery, the rechargeable lithium battery comprising: A positive electrode; a negative electrode, and The separator for a rechargeable lithium battery according to claim 1, interposed between the positive electrode and the negative electrode.

Description

Separator for rechargeable lithium battery and rechargeable lithium battery including the same The present application claims priority from korean patent application No. 10-2024-0157089 filed in the korean intellectual property office on day 11 and 7 of 2024, the entire disclosure of which is incorporated herein by reference. Technical Field The present disclosure relates to a separator for a rechargeable lithium battery and a rechargeable lithium battery including the same. Background With the increasing use of electronic devices using batteries (such as mobile phones, notebook computers, electric vehicles, etc.), the demand for secondary batteries having high energy density and high capacity is increasing. Therefore, it may be advantageous to improve the performance of rechargeable lithium batteries. Rechargeable lithium batteries generally include a positive electrode and a negative electrode containing an active material capable of intercalating and deintercalating lithium ions, and generate electric energy through a redox reaction that occurs when lithium ions are deintercalated from the positive electrode and intercalated into the negative electrode or deintercalated from the negative electrode and intercalated into the positive electrode. Disclosure of Invention The present disclosure describes a separator for a rechargeable lithium battery that improves the capacity of the rechargeable lithium battery due to its low film resistance. The present disclosure also describes a separator for a rechargeable lithium battery that improves safety and life of the rechargeable lithium battery due to its high adhesion. The present disclosure also describes a separator for a rechargeable lithium battery that improves resistance due to its high electrolyte wettability and improved flexibility. The present disclosure also describes a separator for a rechargeable lithium battery having a high capacity retention rate and a low direct current internal resistance (DC-IR) change rate at both room temperature and high temperature. The present disclosure also describes a rechargeable lithium battery including the separator for a rechargeable lithium battery described above. According to aspects of the present disclosure, a separator for a rechargeable lithium battery is described. A separator for a rechargeable lithium battery includes a porous substrate and a coating layer on at least one surface of the porous substrate. The coating layer includes a binder including a copolymer including a first structural unit including a unit derived from an aromatic unsaturated monomer, a second structural unit derived from a (meth) acrylic monomer including an alkyl group having 4 or more carbon atoms in a main chain of an ester portion, and a third structural unit derived from a sulfonic acid group-containing monomer. The first structural unit is included in an amount ranging from about 5mol% to about 80mol%, the second structural unit is included in an amount ranging from about 10mol% to about 40mol%, and the third structural unit is included in an amount ranging from about 5mol% to about 80mol%, based on 100mol% of the copolymer. According to another aspect of the present disclosure, a rechargeable lithium battery is described. A rechargeable lithium battery includes a positive electrode, a negative electrode, and the separator for the rechargeable lithium battery interposed between the positive electrode and the negative electrode. Drawings The above and other objects, features and advantages of the present disclosure will be more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments of the present disclosure with reference to the accompanying drawings. Fig. 1 to 4 are schematic views schematically illustrating a rechargeable lithium battery according to an example embodiment of the present disclosure. Fig. 5 is a cross-sectional view illustrating a separator for a rechargeable lithium battery according to an example embodiment. Detailed Description Hereinafter, example embodiments of the present disclosure are described in detail. However, the embodiments are presented as examples and the disclosure is not limited thereto, but only by the scope of the appended claims. When an element such as a layer, film, region, plate or the like is referred to as being disposed "on" another element, it includes not only the element being "directly on" the other element but also other elements being present therebetween, unless otherwise stated herein. Singular may also include plural unless stated otherwise herein. In addition, unless stated otherwise, the term "a or B" may mean "comprising a, comprising B, or comprising a and B". In this specification, "combination thereof" may mean a mixture, stack, compound, copolymer, alloy, blend or reaction product of components. Unless otherwise defined herein, "particle diameter D100" refers to the diameter of particles having a cumulative volume of 100% by volum