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CN-122000621-A - Composite separator and electrochemical device including the same

CN122000621ACN 122000621 ACN122000621 ACN 122000621ACN-122000621-A

Abstract

The present invention relates to a composite separator including a porous substrate, and a coating layer formed on at least one side of the substrate and including organic particles, the coating layer satisfying the following formula 1, the composite separator ensuring excellent heat resistance, adhesion, fusion force with an electrode, and preventing a blocking phenomenon even at a thin thickness. [ 1] 4000≤A.times.D 2 )/T≤5500 (in said formula 1, A, D and T are as described in the specification).

Inventors

  • Jin Dongzai
  • Yin Zhemin
  • LI CHUNBAO

Assignees

  • SK新技术株式会社
  • 爱思开高新信息电子材料株式会社

Dates

Publication Date
20260508
Application Date
20251031
Priority Date
20241107

Claims (19)

  1. 1. A composite separator includes a porous substrate, and a coating layer formed on at least one side of the substrate and including organic particles, The coating layer satisfies the following formula 1, [ 1] 4000≤(A×D 2 )/T≤5500 In the above-mentioned formula (1), A is the number of organic particles per unit area of the coating surface in units of per mm 2 ; D is the average particle size of the organic particles observed at the surface of the coating in μm; t is the total thickness of the coating in μm.
  2. 2. The composite separator according to claim 1, wherein the organic particles have a coated surface average particle diameter D of 1 μm to 10 μm.
  3. 3. The composite separator of claim 1 wherein the total thickness of the coating is from 1 to 20 μιη.
  4. 4. The composite separator of claim 1 wherein the organic particles have a glass transition temperature T g of 40 ℃ to 80 ℃.
  5. 5. The composite separator of claim 1 wherein the organic particles comprise one or more selected from the group consisting of acrylic-based polymers, urethane-based polymers, and fluorine-based polymers.
  6. 6. The composite separator of claim 5 wherein the acrylic-based polymer comprises a copolymer comprising polymerized units of an alkyl (meth) acrylate-based monomer and polymerized units of one or more selected from polymerized units of a styrene-based monomer, polymerized units of a butadiene-based monomer, and polymerized units of a vinyl monomer.
  7. 7. The composite separator of claim 1 wherein the coating further comprises inorganic particles and a binder.
  8. 8. The composite separator of claim 7 wherein the inorganic particles are present in an amount of 96 to 99 wt% relative to the total weight of the coating.
  9. 9. The composite separator of claim 7 wherein the weight ratio of binder to organic particles comprised is from 5:5 to 7:3.
  10. 10. The composite separator of claim 7 wherein the content of the organic particles is in the range of greater than 1 wt% and 2 wt% or less relative to the total weight of the coating.
  11. 11. The composite separator of claim 7 wherein the inorganic particles have an equivalent spherical diameter Dv50 of 0.01 μιη to 1 μιη.
  12. 12. The composite separator of claim 7 wherein the inorganic particles comprise one or more selected from boehmite, pseudo-boehmite 、BaSO 4 、CeO 2 、MgO、CaO、ZnO、Al 2 O 3 、SiO 2 、TiO 2 、BaTiO 3 、HfO 2 、SrTiO 3 、SnO 2 、NiO、ZrO 2 、Y 2 O 3 , and SiC.
  13. 13. The composite separator of claim 7 wherein the binder comprises one or more selected from the group consisting of (meth) acrylic-based polymers, fluoro-based polymers, styrene-based polymers, vinyl alcohol-based polymers, vinyl ester-based polymers, vinyl pyrrolidone-based polymers, cellulose-based polymers, polyimide-based polymers, polyamide-based polymers, and polyalkylene glycols.
  14. 14. The composite separator of claim 7 wherein the binder comprises polyacrylamide, carboxymethyl cellulose, or a combination thereof.
  15. 15. The composite separator of claim 7 wherein the binder comprises carboxymethyl cellulose having a weight average molecular weight of 180000g/mol or more and a degree of substitution of 0.6 to 1.2.
  16. 16. The composite separator of claim 1 wherein the porous substrate is hydrophilic surface treated.
  17. 17. The composite separator of claim 7 wherein the composite separator has anti-blocking properties, Anti-blocking Properties The two composite separators were disposed such that the coatings faced each other and were pressed at a temperature of 25 ℃ and a pressure of 15kgf/cm 2 for 1 hour, then peeled off at 180 ° according to ASTM D903, whether the organic particles and/or the inorganic particles were desorbed or not was confirmed by a Scanning Electron Microscope (SEM), any 10 positions were designated, and the number of desorbed organic particles and/or inorganic particles per unit area was counted, and the average value of 10 points was less than 10 -4 /μm 2 , or neither the organic particles nor the inorganic particles were desorbed.
  18. 18. The composite separator according to claim 1, wherein when the degree of adhesion of the foreign matter to the cardboard surface is evaluated after the cardboard test of the composite separator, the proportion of the area occupied by the adhered foreign matter to the cardboard area is 5% or less, Paperboard testing A black cardboard having a size of 2cm×10cm and a rubber pad were placed in this order on a coating layer of a composite separator sample having a size of 5cm×10cm, and the cardboard was horizontally pulled out at a speed of 0.1 m/sec in a state where a force of 10N was applied to the rubber pad by a pressing device, and the degree of adhesion of foreign matters to the cardboard surface was tested.
  19. 19. An electrochemical device, wherein the electrochemical device is an electrochemical device comprising a positive electrode, a negative electrode and a composite separator, The composite separator includes a porous substrate, and a coating layer formed on at least one side of the substrate and including organic particles, The coating layer satisfies the following formula 1, [ 1] 4000≤(A×D 2 )/T≤5500 In the above-mentioned formula (1), A is the number of organic particles per unit area of the coating surface in units of per mm 2 ; D is the average particle size of the organic particles observed at the surface of the coating in μm; t is the total thickness of the coating in μm.

Description

Composite separator and electrochemical device including the same Technical Field The present invention relates to a separator and an electrochemical device including the same. Background In recent years, with the increase in capacity and power of electrochemical devices, there has been an increasing demand for ensuring heat resistance and safety. In particular, the performance requirements of separators, which are very important elements for ensuring the heat resistance and safety of electrochemical devices, are also becoming higher, and for example, composite separators incorporating inorganic coatings comprising inorganic particles such as alumina (Al 2O3), silica (SiO 2), zirconia (ZrO 2), and a binder on a porous substrate are becoming an important technique. However, the existing composite separator has insufficient adhesion to the electrode, which results in separation of the separator from the electrode during the battery assembly process, thus causing distortion, deformation, etc. of the electrode assembly, and causing short circuits between the electrodes, thus having a problem of safety. In order to solve these problems, there has been proposed a method of introducing a coating layer or the like containing a separate fusing agent capable of generating a fusing force with an electrode, but the fusing effect is insufficient, and in the case of achieving a sufficient fusing force, problems such as occurrence of blocking (blocking) phenomenon of desorption of the fusing agent and a substance in the coating layer, or the like, occur. [ Prior Art literature ] [ Patent literature ] (Patent document 1) KR 10-2573567B1 (2023, 08, 29) Disclosure of Invention First, the technical problem to be solved One embodiment of the present invention relates to a composite separator incorporating a coating layer containing organic particles that can achieve fusion force with an electrode, and provides a composite separator that can secure excellent heat resistance, adhesion force, and fusion force with an electrode even at a thin thickness and can prevent a blocking phenomenon. Another embodiment of the present invention provides an electrochemical device using the composite separator. (II) technical scheme An embodiment of the present invention provides a composite separator including a porous substrate, and a coating layer formed on at least one side of the substrate and including organic particles, the coating layer satisfying the following formula 1. [ 1] 4000≤(A×D2)/T≤5500 (In the formula 1 described above, A is the number of organic particles per unit area of the coating surface (/ mm 2); D is the average particle size (μm) of the organic particles observed at the surface of the coating; t is the total thickness of the coating (μm). ) The organic particles may have a coating surface average particle diameter (D) of 1 μm to 10 μm. The total thickness of the coating may be 1 μm to 20 μm. The glass transition temperature (T g) of the organic particles may be 40 ℃ to 80 ℃. The organic particles may contain one or more selected from the group consisting of acrylic-based polymers, urethane-based polymers, and fluorine-based polymers. The acrylic-based polymer may comprise a copolymer including an alkyl (meth) acrylate-based monomer polymerized unit and one or more polymerized units selected from a styrene-based monomer polymerized unit, a butadiene-based monomer polymerized unit, and a vinyl-based monomer polymerized unit. The coating may further comprise inorganic particles and a binder. The inorganic particles may be contained in an amount of 96 to 99% by weight relative to the total weight of the coating layer. The binder and organic particles may be included in a weight ratio of 5:5 to 7:3. The content of the organic particles may be in a range of more than 1 wt% and 2 wt% or less with respect to the total weight of the coating layer. The inorganic particles may have an equivalent spherical diameter (Dv 50) of 0.01 μm to 1 μm. The inorganic particles may include one or more selected from boehmite (boehmite), pseudo-boehmite (pseudo-boehmite)、BaSO4、CeO2、MgO、CaO、ZnO、Al2O3、SiO2、TiO2、BaTiO3、HfO2、SrTiO3、SnO2、NiO、ZrO2、Y2O3, and SiC. The binder may include one or more selected from the group consisting of (meth) acrylic-based polymers, fluorine-based polymers, styrene-based polymers, vinyl alcohol-based polymers, vinyl ester-based polymers, vinyl pyrrolidone-based polymers, cellulose-based polymers, polyimide-based polymers, polyamide-based polymers, and polyalkylene glycols. The binder may include polyacrylamide, carboxymethyl cellulose, or a combination thereof. The binder may comprise carboxymethyl cellulose having a weight average molecular weight of 180000g/mol or more and a degree of substitution of 0.6 to 1.2. The porous substrate may be hydrophilic surface treated. The composite separator according to one embodiment may have the following anti-blocking properties. [ Anti-blocking Property ] The two composite sepa