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KR-20260066517-A - A SEPARATOR FOR AN ELECTROCHEMICAL DEVICE AND AN ELECTROCHEMICAL DEVICE COMPRISING THE SAME

KR20260066517AKR 20260066517 AKR20260066517 AKR 20260066517AKR-20260066517-A

Abstract

The present invention provides a separator for an electrochemical device comprising: a porous polymer substrate; a first coating layer disposed on one side of the porous polymer substrate and comprising a polymer binder and inorganic particles; and a second coating layer disposed on the remaining side of the porous polymer substrate and comprising nylon-n nanofibers, wherein the cross-sectional diameter of the nylon-n nanofibers is 0.3 μm or more and 1.5 μm or less. The present invention provides a separator for an electrochemical device having excellent electrolyte wettability and low resistance.

Inventors

  • 김경태
  • 김도형
  • 오윤지

Assignees

  • 주식회사 엘지에너지솔루션

Dates

Publication Date
20260512
Application Date
20241104

Claims (10)

  1. porous polymer substrate; A first coating layer disposed on one side of the above-mentioned porous polymer substrate and comprising a polymer binder and inorganic particles; and It comprises a second coating layer disposed on the remaining surface of the porous polymer substrate and comprising nylon-n nanofibers, A separator for an electrochemical device having a cross-sectional diameter of the above nylon-n nanofiber of 0.3 μm or more and 1.5 μm or less.
  2. In paragraph 1, A separator for an electrochemical device, wherein n is at least one of 5 or 11.
  3. In paragraph 1, A separator for an electrochemical device, wherein the thickness of the second coating layer is 0.5 μm or more and 2 μm or less.
  4. In paragraph 1, A separator for an electrochemical device, wherein the average pore size of the second coating layer is 0.5 μm or more and 3 μm or less.
  5. In paragraph 1, A separator for an electrochemical device, wherein the weight-average molecular weight of the nylon-n nanofiber is 100 g/mol or more and 1000 g/mol or less.
  6. In paragraph 1, A separator for an electrochemical device, wherein the crystalline phase of the above nylon-n nanofiber is of the γ type.
  7. In paragraph 1, A separator for an electrochemical device, wherein the dielectric constant of the above nylon-n nanofiber is 1 or greater and 5 or less.
  8. In paragraph 1, A separator for an electrochemical device, wherein the loading amount of the second coating layer is 0.5 g/ m² or more and 3.0 g/ m² or less.
  9. In paragraph 1, A separator for an electrochemical device, wherein the thickness ratio of the first coating layer and the second coating layer is 1:0.25 to 1:2.
  10. An electrochemical device comprising an anode, a cathode, a separator disposed between the anode and the cathode, and an electrolyte, wherein The above-mentioned separator is an electrochemical device according to any one of claims 1 to 9.

Description

A separator for an electrochemical device and an 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. Among the components of an electrochemical device, the separator comprises a porous polymer substrate with a porous structure located between the anode and cathode. It serves to isolate the anode and cathode, prevent electrical short circuits between the two electrodes, and allow the passage of electrolytes and ions. Although the separator itself does not participate in electrochemical reactions, its physical properties, such as wettability to the electrolyte, degree of porosity, and thermal shrinkage rate, affect the performance and safety of the electrochemical device. Accordingly, various methods are being attempted to modify the physical properties of a coating layer by adding a coating layer to a porous polymer substrate to enhance the physical properties of the separation membrane, and by adding various materials to the coating layer. For example, inorganic materials may be added to the coating layer to improve the mechanical strength of the separation membrane, or inorganic materials or hydrates may be added to the coating layer to improve the flame retardancy and heat resistance of the porous polymer substrate. Although it is possible to coat both sides of the separator with the aforementioned coating layer, there are concerns regarding increased resistance due to the increased thickness and rising process/manufacturing costs resulting from the addition of the coating layer. Accordingly, from a cost perspective, a coating layer containing inorganic particles is applied to only one side of the separator. However, the remaining side, to which the coating layer is not applied, exhibits inferior electrolyte wettability, raising concerns about reduced capacity development due to non-uniform activation of the anode during the activation process or, in the case of the cathode, lithium deposition. 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. In this specification, the term "comprising" is used when listing materials, compositions, devices, and methods useful for the present invention, and is not limited to the examples listed. In this specification, "electrochemical device" may refer to a primary battery, a secondary battery, a supercapacitor, etc. In this specification, "permittivity" refers to the magnitude of polarization produced by a dielectric in response to an external electric field, and its unit is F/m. The unit of permittivity will be omitted below. Specifically, permittivity may be measured at a temperature of 25°C using the ASTM D150 standard test method. In this specification, "pore size" may mean the diameter of the pore. One embodiment of the present invention provides a separator for an electrochemical device comprising: a porous polymer substrate; a first coating layer disposed on one side of the porous polymer substrate and comprising a polymer binder and inorganic particles; and a second coating layer disposed on the remaining side of the porous polymer substrate and comprising nylon-n nanofibers, wherein the cross-sectional diameter of the nylon-n nanofibers is 0.3 μm or more and 1.5 μm or less. According to one embodiment of the present invention, the separator for the electrochemical device comprises the porous polymer substrate. The porous polymer 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 polymer 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 polymer substrate, and a fluid may pass through the porous polymer substrate through the pores. The porous polymer 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 polymer substrate may include, but is not limited to, resins such as polyolefins including polyethylene, polypropylene, and polybutylene, polyvinyl chloride, polyethylene terephth