KR-20260062376-A - SEPARATOR FOR ELECTROCHEMICAL DEVICE AND ELECTROCHEMICAL DEVICE COMPRISING THE SAME

Abstract

The present invention relates to a separator for an electrochemical device comprising a porous substrate and a coating layer formed on at least one surface of the porous substrate, wherein the coating layer comprises inorganic particles, a polymer binder, and a cyclodextrin comprising beta-cyclodextrin, gamma-cyclodextrin, or a mixture thereof, and wherein the cyclodextrin forms a composite.

Inventors

• 최인영
• 배원식
• 이소영
• 배경희
• 박병찬

Assignees

• 주식회사 엘지에너지솔루션

Dates

Publication Date

20260507

Application Date

20241029

Claims (8)

1. porous substrate; and It includes a coating layer formed on at least one surface of the above-mentioned porous substrate, and The above coating layer comprises inorganic particles, a polymer binder, and a cyclodextrin comprising beta-cyclodextrin, gamma-cyclodextrin, or a mixture thereof, and The above-mentioned cyclodextrin forms a complex, and is a separator for an electrochemical device.
2. In paragraph 1, The above composite is a separator for an electrochemical device having a particle size (D90) of 100 nm or more and 120 nm or less.
3. In paragraph 1, The above composite is a separator for an electrochemical device having a pore diameter of 7 nm or more and 15 nm or less.
4. In paragraph 1, A separator for an electrochemical device, wherein the weight ratio of the polymer binder to the cyclodextrin is 2:8 to 8:2.
5. In paragraph 1, A separator for an electrochemical device, wherein the coating layer comprises 2 to 10 weight percent of the cyclodextrin based on the total weight of the coating layer.
6. In paragraph 1, The above polymer binder is one or more selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, and polyvinylidene fluoride-trichloroethylene, a separator for an electrochemical device.
7. In paragraph 1, The above coating layer is a separator for an electrochemical device, wherein the content of the inorganic particles relative to the total weight of the coating layer is 80 to 95 weight%.
8. An electrochemical device comprising an anode, a cathode, and a separator disposed between the anode and the cathode, The above-mentioned separator is an electrochemical device, wherein the separator is a separator for an electrochemical device according to any one of claims 1 to 7.

Description

Separator for electrochemical device and electrochemical device comprising the same The present invention relates to a separator for an electrochemical device and an electrochemical device including the same. Electrochemical devices convert chemical energy into electrical energy using electrochemical reactions; recently, lithium-ion batteries, which offer high energy density and voltage, long cycle life, and applicability to various fields, are widely used. A lithium secondary battery may comprise an electrode assembly made of a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes, and may be manufactured by housing the electrode assembly together with an electrolyte in a case. The separator may comprise a porous coating layer comprising a polymer binder and inorganic particles on at least one surface of a porous substrate. The inorganic particles may be connected to other inorganic particles by the polymer binder to form an interstitial volume, and lithium ions may move through the interstitial volume. In addition to fixing the inorganic particles, the polymer binder may impart adhesion to the porous coating layer, and the porous coating layer may be adhered to the porous substrate and the electrode, respectively. However, a problem arose where the resistance of the separator increased if the pore structure within the coating layer was blocked by the polymer binder, hindering the movement of lithium ions. Conventional polymer binders do not contain their own internal pores, so once the spaces between inorganic particles are blocked, it becomes impossible to secure a pathway for lithium ion movement. Therefore, there is a need for research on separators incorporating a coating layer that can uniformly immobilize inorganic particles while maintaining the pore structure intact. Figure 1 shows the pore diameters of cyclodextrin complexes according to Examples 1, 3 and Comparative Example 2 measured by the BET method. Figure 2 shows the capacity retention rate after 100 cycles of electrochemical devices according to Examples 1 to 3 and Comparative Examples 1 and 2. Hereinafter, each component of the present invention is described in more detail so that a person skilled in the art to which the present invention pertains can easily implement it; however, this is merely an example, and the scope of the rights of the present invention is not limited by the following. The term “comprising” as used herein is used when listing materials, compositions, devices, and methods useful for the present invention, and is not limited to the examples listed. As used herein, "about" and "substantially" are used to mean a range of numerical values or degrees or approximations thereof, taking into account inherent manufacturing and material tolerances, and are used to prevent an infringer from unfairly exploiting the disclosure in which precise or absolute figures provided to aid in understanding the invention are mentioned. As used in this specification, "electrochemical device" may refer to a primary battery, a secondary battery, a supercapacitor, etc. Although the present invention has been described below by specific examples and embodiments, the present invention is not limited thereto and may include a combination of one or more of the specific examples and embodiments by those skilled in the art to which the present invention belongs, and various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below. One embodiment of the present invention provides a separator for an electrochemical device comprising a porous substrate and a coating layer formed on at least one surface of the porous substrate, wherein the coating layer comprises inorganic particles, a polymer binder, and a cyclodextrin comprising beta-cyclodextrin, gamma-cyclodextrin, or a mixture thereof, and wherein the cyclodextrin forms a composite. The porous substrate may be a porous membrane having a plurality of pores formed therein, which electrically insulates the positive electrode and the negative electrode to prevent a short circuit. For example, if the electrochemical device is a lithium secondary battery, the porous substrate may be an ion-conducting barrier that blocks electrical contact between the positive electrode and the negative electrode while allowing lithium ions to pass through. At least some of the pores may form a three-dimensional network communicating the surface and the interior of the porous substrate, and a fluid may pass through the porous substrate through the pores. The porous substrate described above may be a material that is physically and chemically stable with respect to an electrolyte, which is an organic solvent. For example, the porous substrate may include, but is not limited to, resins such as polyolefins including polyethylene, polypropylene, and polybutylene, pol