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CN-122000629-A - Composite separator and electrochemical device including the same

CN122000629ACN 122000629 ACN122000629 ACN 122000629ACN-122000629-A

Abstract

The present invention relates to a composite separator including a porous substrate, and a ceramic layer formed on one or both sides of the porous substrate, and the ceramic layer including inorganic particles and a binder, wherein the binder includes carboxymethyl cellulose having a weight average molecular weight of 180000g/mol to 280000g/mol and a substitution degree of 0.6 to 1.2, and the composite separator can simultaneously satisfy excellent mechanical stability, thermal stability, and ion-conductive characteristics.

Inventors

  • Yin Zhemin
  • Jin Dongzai
  • WU ENZHI
  • DING XIJUN

Assignees

  • 爱思开高新信息电子材料株式会社

Dates

Publication Date
20260508
Application Date
20251107
Priority Date
20241107

Claims (14)

  1. 1. A composite separator includes a porous substrate, and a ceramic layer formed on one or both sides of the porous substrate, the ceramic layer including inorganic particles and a binder, Wherein the binder comprises carboxymethyl cellulose having a weight average molecular weight of 180000g/mol to 280000g/mol and a degree of substitution of 0.6 to 1.2.
  2. 2. The composite separator of claim 1 wherein the carboxymethyl cellulose has a weight average molecular weight of 200000g/mol to 250000g/mol.
  3. 3. The composite separator of claim 1 wherein the degree of substitution of the carboxymethyl cellulose is from 0.7 to 1.0.
  4. 4. The composite separator according to claim 1, wherein the binder is contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the inorganic particles.
  5. 5. The composite separator of claim 1 wherein the binder comprises 70 wt% or more of the carboxymethyl cellulose relative to the total weight of binder.
  6. 6. The composite separator of claim 1 wherein the binder consists of the carboxymethyl cellulose.
  7. 7. The composite separator according to claim 1, wherein the inorganic particles are one or two or more selected from boehmite 、BaSO 4 、CeO 2 、MgO、CaO、ZnO、Al 2 O 3 、TiO 2 、BaTiO 3 、HfO 2 、SrTiO 3 、SnO 2 、NiO、ZrO 2 、Y 2 O 3 and SiC.
  8. 8. The composite separator according to claim 1, wherein the inorganic particles have an average particle diameter of 0.1 μm to 1.0 μm.
  9. 9. The composite separator of claim 1 wherein the porous substrate is hydrophilic surface treated.
  10. 10. The composite separator of claim 1 wherein the ceramic layer has a total thickness of 0.5 to 10 μιη.
  11. 11. The composite separator according to claim 1, wherein the thermal shrinkage of the composite separator in both the mechanical direction and the transverse direction measured after the composite separator is left at 150 ℃ for 60 minutes is 4% or less.
  12. 12. 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, In the cardboard test, a black cardboard having a size of 2cm×10cm and a rubber pad were sequentially placed on a ceramic layer of a composite membrane 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.
  13. 13. A method for producing a composite separator, which comprises the steps of coating a ceramic layer-forming composition comprising a binder and inorganic particles on one or both sides of a porous substrate and drying to form a ceramic layer, Wherein the binder comprises carboxymethyl cellulose having a weight average molecular weight of 180000g/mol to 280000g/mol and a degree of substitution of 0.6 to 1.2.
  14. 14. An electrochemical device comprising a positive electrode, a negative electrode, and a composite separator, Wherein the composite separator comprises a porous substrate, and a ceramic layer formed on one or both sides of the porous substrate, and comprising inorganic particles and a binder, The binder comprises carboxymethyl cellulose having a weight average molecular weight of 180000g/mol to 280000g/mol and a degree of substitution of 0.6 to 1.2.

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, and in particular, for this reason, there has been an increasing demand for performance of separators which are very important elements. For example, as a means for securing heat resistance and safety of a separator, a composite separator including a porous substrate, a coating layer containing inorganic particles such as alumina (Al 2O3), silica (SiO 2), and zirconia (ZrO 2), and a binder is being introduced. However, in recent years, in order to achieve high capacity and high power characteristics of an electrochemical device, research is being conducted in the direction of achieving thinning of a separator, and an adhesive applied to a conventional composite separator is insufficient in adhesion to both sides of a substrate and inorganic particles, so that as the thickness of an inorganic particle coating layer becomes thinner, there occurs a problem that mechanical strength and/or heat resistance are lowered. In order to solve such problems, studies are being continued, but in the case of an adhesive material having improved heat resistance, there are disadvantages in adhesion or limitations in that characteristics such as air permeability and interface resistance are deteriorated and device performance is lowered when an attempt is made to improve adhesion of a separator. [ Prior Art literature ] [ Patent literature ] Korean laid-open patent publication No. 10-2015-0071733A Disclosure of Invention First, the technical problem to be solved One embodiment of the present invention relates to a composite separator including a porous substrate, and a ceramic layer formed on one or both sides of the porous substrate, inorganic particles being connected and fixed by an adhesive such that pores are formed between the inorganic particles, and a composite separator having both excellent heat resistance and adhesion. Another embodiment of the present invention provides an electrochemical device in which the composite separator is used, thereby having excellent battery performance and safety. (II) technical scheme An embodiment of the present invention provides a composite separator including a porous substrate, and a ceramic layer formed on one or both sides of the porous substrate, and including inorganic particles and a binder, wherein the binder includes carboxymethyl cellulose having a weight average molecular weight of 180000g/mol to 280000g/mol and a substitution degree of 0.6 to 1.2. The weight average molecular weight of the carboxymethyl cellulose may be 200000g/mol to 250000g/mol. The degree of substitution of the carboxymethyl cellulose may be 0.7 to 1.0. The ceramic layer may contain 0.1 to 10 parts by weight of a binder with respect to 100 parts by weight of the inorganic particles. The binder may contain 70 wt% or more of the carboxymethyl cellulose with respect to the total weight of the binder, or the binder may be composed of the carboxymethyl cellulose. The inorganic particles may be one or two or more selected from boehmite (boehmite)、BaSO4、CeO2、MgO、CaO、ZnO、Al2O3、TiO2、BaTiO3、HfO2、SrTiO3、SnO2、NiO、ZrO2、Y2O3 and SiC. The inorganic particles may have an average particle diameter of 0.1 μm to 1.0 μm. The porous substrate may be hydrophilic surface treated. The ceramic layer may have a total thickness of 0.5 μm to 10 μm. The thermal shrinkage of the composite separator according to one embodiment may be 4% or less in both a Mechanical Direction (MD) and a Transverse Direction (TD) measured after being left at 150 ℃ for 60 minutes. In the composite separator according to one embodiment, when the degree of adhesion of the foreign matter to the surface of the paperboard is evaluated after the paperboard test, the ratio of the area occupied by the adhered foreign matter to the area of the paperboard may be 5% or less. [ Cardboard test ] A black cardboard and a rubber pad having a size of 2cm×10cm were placed in this order on a ceramic 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 for 60mm 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. Another embodiment of the present invention provides a method for manufacturing a composite separator including a step of coating a ceramic layer forming composition including a binder and inorganic particles on one or both sides of a porous substrate and drying to form a ceramic layer, wherein the binder includes carboxymethyl cellulose having a weight average molecular weight of 180000g/mol to 280000g/mol and a substitution