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KR-20260067661-A - A SEPARATOR FOR AN ELECTROCHEMICAL DEVICE AND AN ELECTROCHEMICAL DEVICE COMPRISING THE SAME

KR20260067661AKR 20260067661 AKR20260067661 AKR 20260067661AKR-20260067661-A

Abstract

The present invention relates to a separator for an electrochemical device equipped with an aramid coating layer. Due to the high heat resistance and mechanical strength of the aramid, the separator may have a low thermal shrinkage rate and excellent mechanical strength. Furthermore, since the aramid coating layer is subjected to an etching process using silica particles and thus has high permeability, the separator for an electrochemical device according to the present invention is characterized by having low resistance and excellent electrolyte impregnation properties.

Inventors

  • 김민규
  • 가경륜
  • 김민지
  • 김지현
  • 황선우

Assignees

  • 주식회사 엘지에너지솔루션

Dates

Publication Date
20260513
Application Date
20241106

Claims (10)

  1. porous polymer substrate; and A coating layer comprising aramid disposed on at least one surface of the above-mentioned porous polymer substrate, and The average pore diameter of the above coating layer is 30 nm or more and 250 nm or less, and A separator for an electrochemical device having a porosity of 10 volume% or more and 60 volume% or less of the coating layer.
  2. In paragraph 1, A separator for an electrochemical device, wherein the content of the aramid is 80 parts by weight or more and 95 parts by weight or less, based on 100 parts by weight of the total weight of the coating layer.
  3. In paragraph 1, The above aramid is a separator for an electrochemical device having a weight-average molecular weight of 100,000 g/mol or more and 200,000 g/mol or less.
  4. In paragraph 1, The above aramid is a para-aramid, a separator for an electrochemical device.
  5. In paragraph 4, The above para-aramid is one or more selected from the group consisting of poly(paraphenylene terephthalamide), poly(paraphenylene-4,4-biphenylene-dicarboxylic acid amide), poly(paraphenylene-2,6-naphthalene dicarboxylic acid amide), and poly(paraphenylenediamine)-co-poly(terephthaloyl chloride), for use as a separator for an electrochemical device.
  6. In paragraph 1, A separator for an electrochemical device having a coating layer thickness of 0.5 μm or more and 2 μm or less.
  7. A step (S10) of forming a coating layer on one surface of a porous polymer substrate using a composition for forming a coating layer comprising aramid and silica particles; and The method includes the step (S20) of applying an etching solution to the coating layer to etch the silica particles, and A method for manufacturing a separator for an electrochemical device, wherein the average particle size of the silica particles is 20 nm or more and 200 nm or less.
  8. In Paragraph 7, A method for manufacturing a separator for an electrochemical device, wherein the content of the aramid is 70 parts by weight or more and 90 parts by weight or less based on a total weight of 100 parts by weight of the composition for forming the coating layer.
  9. In Paragraph 7, A method for manufacturing a separator for an electrochemical device, wherein the content of the silica particles is 5 parts by weight or more and 15 parts by weight or less, based on a total weight of 100 parts by weight of the composition for forming the coating layer.
  10. A positive electrode; a negative electrode; and a separator for an electrochemical device according to any one of claims 1 to 6, comprising The above electrochemical device is an electrochemical device in which a separator is interposed between the anode and the cathode.

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 such an electrochemical device, the separator may comprise a polymer substrate having a porous structure located between the anode and the cathode. The separator isolates the anode and the cathode to prevent an electrical short circuit between the two electrodes, while simultaneously allowing the electrolyte and ions to pass through. Although the separator itself does not participate in electrochemical reactions, its physical properties, such as wettability to the electrolyte, porosity, and thermal shrinkage rate, can affect the performance and safety of the electrochemical device. Therefore, to enhance the physical properties of such separation membranes, various methods are being attempted to improve the properties of the coating layer by adding a coating layer to a porous polymer substrate and 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, organic, or hydrated materials may be added to the coating layer to improve the flame retardancy and heat resistance of the polymer substrate. As described above, inorganic particles can be used as the material for the coating layer; however, among organic materials, aromatic polyamide, specifically aramid, has the advantage of being suitable as a material for a coating layer to minimize thermal shrinkage of the porous polymer substrate due to its excellent mechanical properties and heat resistance. Accordingly, a separator for an electrochemical device in which an aramid coating layer is disposed on one side of a porous polymer substrate is attracting attention; however, due to the low air permeability of the aramid coating layer, the separator for an electrochemical device containing it has the disadvantage of high resistance and poor electrolyte impregnation. Accordingly, there is a need to develop a separator for electrochemical devices with an added aramid coating layer that can minimize thermal shrinkage of the separator by utilizing the high heat resistance of aramid, while simultaneously lowering the resistance of the separator through excellent air permeability. 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 to the present invention, and is not limited to the examples listed. In this specification, the terms “about” and “substantially” are used to mean a range of numerical or degree or an approximation 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. In this specification, when a component is described as being "on" one component, this means that, unless specifically stated otherwise, other components may be placed in between, without excluding the placement of other components. In this specification, "electrochemical device" may mean a primary battery, a secondary battery, or a supercapacitor, etc. More specifically, the electrochemical device may be a lithium-ion secondary battery and may be pouch-type, cylindrical-type, prismatic-type, or coin-type, but the specific shape is not limited thereto. In this specification, "electrode" collectively refers to "anode" and "cathode," and may mean a material having conductivity without causing chemical changes in an electrochemical device, on which an electrode active material is coated and dried. The types of the material and the electrode active material are not limited, as long as they can be used in an electrochemical device. In this specification, "separator" may generally refer to a functional separator in which a porous coating layer comprising an inorganic material, an organic material, a binder, or a combination thereof is formed on at least one surface of a porous polymer substrate, such as a polyolefin substrate or a nonwoven fabric, as a material to improve heat resistance. Additionally, the separator has porous characteristics containing a number of pores and acts as a porous ion-conducting barrier that blocks