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KR-102963215-B1 - Composite separator and electrochemical device comprising the same

KR102963215B1KR 102963215 B1KR102963215 B1KR 102963215B1KR-102963215-B1

Abstract

The present disclosure relates to a composite separation membrane comprising: a porous substrate; and a ceramic layer formed on one or both sides of the substrate and comprising inorganic particles and a binder; wherein the average particle size (D50) of the inorganic particles is 0.20 μm to 0.40 μm, and the ratio (A/B) of the area on the small particle size side (A) and the area on the large particle size side (B) based on the maximum peak in the particle size distribution of the inorganic particles is 1.05 or greater, and can satisfy excellent mechanical and thermal stability and ion conductivity characteristics.

Inventors

  • 윤철민
  • 김동재
  • 오은지
  • 정희준

Assignees

  • 에스케이아이이테크놀로지주식회사

Dates

Publication Date
20260511
Application Date
20241107

Claims (15)

  1. A composite separation membrane comprising: a porous substrate; and a ceramic layer formed on one or both sides of the substrate and comprising inorganic particles and a binder, wherein A composite separation membrane having an average particle size (D50) of the inorganic particles of 0.20 μm to 0.40 μm, a ratio (A/B) of the area on the small particle size side (A) and the area on the large particle size side (B) based on the maximum peak in the particle size distribution of the inorganic particles of 1.05 or more, and a value of (D95-D50)/D50 of 1.8 to 2.5.
  2. delete
  3. In paragraph 1, A composite separation membrane in which the ratio (A/B) of the area on the small particle size side (A) and the area on the large particle size side (B) based on the maximum peak in the particle size distribution of the above inorganic particles is 1.05 to 1.3.
  4. In paragraph 1, A composite separation membrane comprising 0.1 to 10 parts by weight of a binder per 100 parts by weight of the above-mentioned inorganic particles.
  5. In paragraph 1, A composite separation membrane in which the above inorganic particles are one or more selected from boehmite, BaSO₄ , CeO₂ , MgO , CaO, ZnO , Al₂O₃ , TiO₂ , BaTiO₃ , HfO₂, SrTiO₃ , SnO₂ , NiO , ZrO₂, Y₂O₃ , and SiC.
  6. In paragraph 1, The above binder is a (meth)acrylic polymer, a fluorine polymer, a styrene polymer, a vinyl alcohol polymer, a vinyl ester polymer, a vinylpyrrolidone polymer, a cellulose polymer, A composite separation membrane comprising one or more selected from polyimide-based polymers, polyamide-based polymers, polyalkylene glycols, copolymers thereof, etc.
  7. In paragraph 1, A composite separation membrane in which the binder comprises polyacrylamide, carboxymethyl cellulose, or a combination thereof.
  8. In paragraph 1, A composite separation membrane comprising carboxymethyl cellulose having a weight-average molecular weight of 180,000 g/mol or more and a degree of substitution of 0.6 to 1.2, wherein the binder comprises carboxymethyl cellulose.
  9. In paragraph 1, The above porous substrate is a composite separation membrane that has a hydrophilic surface treatment.
  10. In paragraph 1, A composite separator having a coating density of 1.2 to 1.8 g/ cm³ of the ceramic layer.
  11. In paragraph 1, A composite separator having a total thickness of the ceramic layer of 0.5 μm to 10 μm.
  12. In paragraph 1, A composite separation membrane having a thickness of 1 to 100 μm.
  13. In paragraph 1, The above composite membrane is a composite membrane in which, when the degree of foreign matter adhering to the surface of the cardboard is evaluated after a cardboard test, the ratio of the area of the foreign matter adhering to the cardboard area to the area of the cardboard is 5% or less. [Cardboard Test] A black cardboard sheet measuring 2 cm x 10 cm and a rubber pad are placed sequentially on the ceramic layer of a composite membrane specimen measuring 5 cm x 10 cm, and while applying a pressure of 10 N to the rubber pad using a pressing device, the cardboard is pulled out horizontally at a speed of 0.1 m/s to test the extent of foreign matter adhering to the surface of the cardboard.
  14. In paragraph 1, A composite membrane having a thermal shrinkage rate in both the MD direction and the TD direction of the above composite membrane measured after being left at 150°C for 60 minutes, which is 4% or less.
  15. As an electrochemical device comprising an anode, a cathode, and a composite separator, The above composite separation membrane comprises a porous substrate and a ceramic layer formed on one or both sides of the substrate, the ceramic layer comprising inorganic particles and a binder. The electrochemical device, wherein the average particle size (D50) of the inorganic particles is 0.2 μm to 0.4 μm, the ratio (A/B) of the area on the small particle size side (A) and the area on the large particle size side (B) based on the maximum peak in the particle size distribution of the inorganic particles is 1.05 or higher, and the value of (D95-D50)/D50 satisfies 1.8 to 2.5.

Description

Composite separator and electrochemical device comprising the same The present disclosure relates to a composite separator and an electrochemical device including the same. Recently, as electrochemical devices are increasingly becoming larger in capacity and power, there is a growing demand for heat resistance and safety, and in particular, the required performance of separators, which act as a very important factor for this, is becoming more sophisticated. For example, composite membranes in which a coating layer containing inorganic particles such as alumina ( Al₂O₃ ), silica ( SiO₂ ), and zirconia ( ZrO₂ ) and a binder is introduced on a porous substrate have become an important technology for ensuring the heat resistance and safety of the membrane. However, research is currently being conducted in the direction of thinning the membrane to achieve high capacity and high power characteristics of electrochemical devices, but there are limitations in that it is difficult to achieve sufficient heat resistance within the thickness range of the thinned inorganic particle coating layer, and if heat resistance is improved, adhesion and/or air permeability deteriorates. Figure 1 is a particle size distribution of the inorganic particles used in Example 1. Unless otherwise defined in this specification, all technical and scientific terms have the same meaning as generally understood by those skilled in the art to which the present invention pertains. The terms used in the description herein are merely for the purpose of effectively describing specific embodiments and are not intended to limit the present invention. The singular form used in this specification is intended to include the plural form unless specifically indicated otherwise in the context. Throughout this specification, the terms “comprising,” “having,” “containing,” or “having” any component mean that, unless specifically stated otherwise, other components are not excluded but may be included, and do not exclude elements, materials, or processes not additionally listed. The numerical ranges used herein include lower and upper limits and all values within the range, increments logically derived from the form and width of the defined range, all of which are limited, and all possible combinations of upper and lower limits of the numerical range defined in different forms. Unless otherwise specifically defined in this specification, values outside the numerical range that may occur due to experimental error or rounding are also included in the defined numerical range. Unless otherwise specifically defined in this specification, “about” may be considered to be a value within 30%, 25%, 20%, 15%, 10%, or 5% of the specified value. The present disclosure will be described in detail below. However, this is merely illustrative and the present disclosure is not limited to the specific embodiments described illustratively. In conventional technology, a method of introducing inorganic particles of a size smaller than a certain threshold has been proposed to solve the problem of reduced heat resistance resulting from the thinning of composite separation membranes including a porous substrate and an inorganic coating layer. However, this method had limitations in that even if heat resistance was somewhat improved, the adhesion between inorganic particles and between inorganic particles and the substrate was reduced, air permeability deteriorated, and attempting to improve adhesion and/or air permeability again resulted in a deterioration of heat resistance. The inventors have discovered that a composite separation membrane comprising a porous substrate and a ceramic layer formed on one or both sides of the substrate and comprising inorganic particles and a binder can simultaneously satisfy heat resistance, adhesion, and air permeability characteristics even within a thin film thickness range when the inorganic particles satisfy an average particle size within a specific range and have specific particle size distribution characteristics. The present disclosure provides a composite membrane capable of simultaneously securing excellent mechanical and thermal stability and ion conductivity properties. A composite separation membrane according to one embodiment comprises a porous substrate; and a ceramic layer formed on one or both sides of the substrate and comprising inorganic particles and a binder; wherein the average particle size (D50) of the inorganic particles is 0.20 μm to 0.40 μm, and the ratio (A/B) of the area on the small particle size side (A) and the area on the large particle size side (B) based on the maximum peak in the particle size distribution of the inorganic particles may be 1.05 or higher. According to one embodiment, the composite separator has an average particle size of 0.20 μm to 0.40 μm and has a particle size distribution characteristic in which the ratio (A/B) of the area on the small particle side (A) and the area on the large particle si