CN-122000615-A - Composite separator and electrochemical device including the same

CN122000615ACN 122000615 ACN122000615 ACN 122000615ACN-122000615-A

Abstract

The present invention relates to a composite separator comprising a porous substrate, and a ceramic layer formed on one or both sides of the porous substrate, and the ceramic layer comprising inorganic particles and a binder, wherein the inorganic particles have an average particle diameter (D50) of 0.20 [ mu ] m to 0.40 [ mu ] m, and the ratio (A/B) of the area (A) on the small particle diameter side to the area (B) on the large particle diameter side based on the maximum peak in the particle size distribution map of the inorganic particles is 1.05 or more, and the composite separator can satisfy excellent mechanical stability, thermal stability and ion conductivity characteristics at the same time.

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 (15)

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 inorganic particles have an average particle diameter D50 of 0.20 to 0.40 μm, and a ratio A/B of an area A on a small particle diameter side to an area B on a large particle diameter side based on a maximum peak in a particle size distribution diagram of the inorganic particles is 1.05 or more.
2. The composite separator of claim 1 wherein in the particle size distribution of the inorganic particles the (D95-D50)/D50 value is from 1.8 to 2.5.
3. The composite separator according to claim 1, wherein in the particle size distribution diagram of the inorganic particles, a ratio a/B of an area a on a small particle size side to an area B on a large particle size side based on a maximum peak is 1.05 to 1.3.
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. 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.
6. The composite separator according to claim 1, wherein the binder is 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, polyalkylene glycols, and copolymers thereof.
7. The composite separator of claim 1 wherein the binder comprises polyacrylamide, carboxymethyl cellulose, or a combination thereof.
8. The composite separator of claim 1 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.
9. The composite separator of claim 1 wherein the porous substrate is hydrophilic surface treated.
10. The composite separator of claim 1 wherein the ceramic layer has a coating density of 1.2g/cm 3 to 1.8g/cm 3 .
11. The composite separator of claim 1 wherein the ceramic layer has a total thickness of 0.5 to 10 μιη.
12. The composite separator of claim 1, wherein the composite separator has a thickness of 1 μιη to 100 μιη.
13. 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.
14. 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.
15. 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 inorganic particles have an average particle diameter D50 of 0.2-0.4 [ mu ] m, and the ratio A/B of the area A on the small particle diameter side to the area B on the large particle diameter side based on the maximum peak in the particle size distribution diagram of the inorganic particles is 1.05 or more.

Description

Composite separator and electrochemical device including the same Technical Field The present invention relates to a composite 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, research is being conducted in the direction of achieving the thinning of the separator in order to achieve high capacity and high power characteristics of the electrochemical device, it is difficult to have sufficient heat resistance in the range of the thickness of the thin inorganic particle coating layer, and there is a limitation in that the adhesion and/or air permeability are deteriorated when the heat resistance is attempted to be improved. [ Prior Art literature ] [ Patent literature ] KR10-2023-0144943A (2023, 10, 17 days) 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 the ceramic layer including inorganic particles and a binder, wherein an average particle diameter (D50) of the inorganic particles is 0.20 μm to 0.40 μm, and a ratio (a/B) of an area (a) on a small particle diameter side to an area (B) on a large particle diameter side based on a maximum peak is 1.05 or more in a particle size distribution diagram of the inorganic particles. In the particle size distribution diagram of the inorganic particles, the (D95-D50)/D50 value may satisfy 1.8 to 2.5. In the particle size distribution diagram of the inorganic particles, the ratio (a/B) of the area (a) on the small particle size side to the area (B) on the large particle size side with respect to the maximum peak may satisfy 1.05 to 1.3. In the composite separator according to an embodiment, the binder may be contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the inorganic particles. 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 binder may be one or two 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, polyalkylene glycols, copolymers thereof, and the like. The binder may comprise 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 ceramic layer may have a coating density of 1.2g/cm 3 to 1.8g/cm 3. The ceramic layer may have a total thickness of 0.5 μm to 10 μm. The thickness of the composite separator according to an embodiment may be 1 μm to 100 μm. 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 ] (Placing a black cardboard and a rubber pad having a size of 2 cm. Times.10 cm in this order on a ceramic layer of a composite separator sample having a size of 5 cm. Times.10 cm, drawing the cardboard horizontally at a speed of 0.1 m/sec for 60mm in a state where a force of 10N is applied to the rubber pad by a pressing means, and testing the degree of adhesion of foreign matters to the cardboard surface.) The thermal shrinkage of the composite separator in both the Machine Direction (MD) and the Transverse Direction (TD) me