CN-122000633-A - Separator for rechargeable lithium battery and rechargeable lithium battery including the same

CN122000633ACN 122000633 ACN122000633 ACN 122000633ACN-122000633-A

Abstract

The present disclosure relates to a separator for a rechargeable lithium battery and a rechargeable lithium battery including the same. The separator includes a porous substrate, a first coating on a first surface of the porous substrate, and a second coating on a second surface of the porous substrate. The first and second coatings include a binder and a filler, the binder of the first coating includes a first binder, and the binder of the second coating includes a second binder. The first binder and the second binder each comprise a copolymer of a monomer mixture comprising a first structural unit comprising units derived from an aromatic-based unsaturated monomer, a second structural unit derived from a (meth) acrylic monomer, and a third structural unit derived from a sulfonic acid group-containing monomer.

Inventors

Jin Nanzhu
LI ZHENGCHENG
Cui Xianxuan
LI PEIXU
LI ZAIJUAN
XU DONGWAN

Assignees

三星SDI株式会社

Dates

Publication Date: 20260508
Application Date: 20251107
Priority Date: 20241107

Claims (15)

1. A separator for a rechargeable lithium battery, the separator comprising: a porous substrate; a first coating on a first surface of the porous substrate, and A second coating layer on a second surface of the porous substrate, Wherein the first coating comprises a first binder and a first filler and the second coating comprises a second binder and a second filler, The first binder and the second binder each include 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 the main chain in an ester moiety, and a third structural unit derived from a sulfonic acid group-containing monomer, Comprising 5 to 80mol% of the first structural unit, 10 to 40mol% of the second structural unit, and 5 to 80mol% of the third structural unit, relative to 100mol% of the copolymer, and The first filler and the second filler satisfy the following expression 1: Expression 1: (average particle size D50 of the second filler)/(average particle size D50 of the first filler). Gtoreq.3.
2. The separator of claim 1, wherein the first filler has an average particle size D50 of greater than 0nm and less than 100nm, and the second filler has an average particle size D50 of 100nm or greater and 300nm or less.
3. The separator of claim 1, wherein the first filler is amorphous and the second filler is cubic.
4. The separator of claim 1, wherein the first and second fillers have a pH of 7 or higher.
5. The separator of claim 1, wherein the first filler and the second filler each comprise at least one of Al 2 O 3 、SiO 2 、TiO 2 、SnO 2 、CeO 2 、MgO、NiO、CaO、GaO、ZnO、ZrO 2 、Y 2 O 3 、SrTiO 3 、BaTiO 3 、Mg(OH) 2 、 boehmite and combinations thereof.
6. The separator of claim 1, wherein the first and second binders each have a glass transition temperature in the range of 60 ℃ to 80 ℃.
7. The separator of claim 1, wherein the first binder and the first filler are included in a mass ratio in the range of 1:10 to 1:50, and the second binder and the second filler are included in a mass ratio in the range of 1:10 to 1:50.
8. The separator according to claim 1, wherein the unit derived from an aromatic-based 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: ; 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, and 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. 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 a main chain in an ester moiety.
10. The separator according to claim 9, wherein the unit derived from a (meth) acrylic monomer including an alkyl group having 1 to 3 carbon atoms in a main chain in 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. 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 in an ester moiety are included in a molar ratio in the range of 1:0.5 to 1:2.
12. The separator according to claim 9, wherein 5mol% to 35mol% of the unit derived from an aromatic unsaturated monomer, 5mol% to 35mol% of the unit derived from a (meth) acrylic monomer containing an alkyl group having 1 to 3 carbon atoms in the main chain in an ester moiety, 20mol% to 30mol% of the second structural unit, and 10mol% to 60mol% of the third structural unit are included with respect to 100mol% of the copolymer.
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 in 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 is 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; 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. The separator of claim 1, wherein the first and second coatings each have a thickness in the range of 0.1 μιη to 1.5 μιη.
15. A rechargeable lithium battery, the rechargeable lithium battery comprising: A positive electrode; a negative electrode, and The separator of any one of claims 1 to 14, 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. 10-2024-0157092 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 popularity of electronic devices using batteries, such as mobile phones, notebook computers, electric vehicles, etc., the demand for rechargeable lithium batteries having high energy density and high capacity continues to increase. Therefore, it may be advantageous to improve the performance of rechargeable lithium batteries. The rechargeable lithium battery includes a positive electrode and a negative electrode including an active material capable of intercalating and deintercalating lithium ions, and generates electric energy through a redox reaction when lithium ions are intercalated/deintercalated into/from the positive electrode. Disclosure of Invention The present disclosure is directed to a separator for a rechargeable lithium battery, which exhibits low film resistance when impregnated with an electrolyte. The present disclosure is also directed to a separator for a rechargeable lithium battery, which exhibits high electrolyte wettability, desired or improved gas permeability, and high adhesion to an electrode plate. The present disclosure is also directed to a separator for a rechargeable lithium battery, which exhibits desirable or improved heat resistance. The present disclosure is also directed to a separator for a rechargeable lithium battery, which exhibits high capacity retention and low direct current internal resistance (DC-IR) change rate at room temperature and high temperature. The present disclosure is also directed to a rechargeable lithium battery including the above separator for a rechargeable lithium battery. One aspect of the present disclosure includes a separator for a rechargeable lithium battery. A separator for a rechargeable lithium battery includes a porous substrate, a first coating layer on a first surface of the porous substrate, and a second coating layer on a second surface of the porous substrate. The first coating includes a binder and a filler, and the second coating includes a binder and a filler. The binder of the first coating layer comprises a first binder and the binder of the second coating layer comprises a second binder. The first binder and the second binder each include a copolymer including a first structural unit including a unit derived from an aromatic-based unsaturated monomer, a second structural unit derived from a (meth) acrylic monomer including an alkyl group having 4 or more carbon atoms in the main chain in the ester moiety, and a third structural unit derived from a sulfonic acid group-containing monomer. Comprising about 5mol% to about 80mol% of the first structural unit, about 10mol% to about 40mol% of the second structural unit, and about 5mol% to about 80mol% of the third structural unit, relative to 100mol% of the copolymer. The filler of the first coating layer includes a first filler, the filler of the second coating layer includes a second filler, and the first filler and the second filler satisfy the following expression 1: Expression 1: (average particle size D50 of the second filler)/(average particle size D50 of the first filler). Gtoreq.3. Another aspect of the present disclosure includes a rechargeable lithium battery. The rechargeable lithium battery includes a positive electrode, a negative electrode, and the above separator interposed between the positive electrode and the negative electrode. Drawings The above and other objects, features and advantages of the present disclosure may become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: FIG. 1 is a Scanning Electron Microscope (SEM) image of an amorphous filler; FIG. 2 is an SEM image of a cubic filler; fig. 3 is a schematic cross-sectional view of a separator for a rechargeable lithium battery according to an example embodiment, and Fig. 4 to 7 are schematic views of a rechargeable lithium battery according to example embodiments. Detailed Description Hereinafter, example embodiments of the present disclosure are described in detail. However, the embodiments are presented as examples, the disclosure is not limited thereto, and the disclosure is limited only by the scope of the appended claims. When an element such as a layer, film, region, plate or the like is described as being disposed "on" another element, unless otherwise specified herein, the element includes not only the element as being "directly on" the other element but also the element as being present there