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CN-122000620-A - Composite separator and electrochemical device including the same

CN122000620ACN 122000620 ACN122000620 ACN 122000620ACN-122000620-A

Abstract

The invention relates to a composite membrane, which comprises a porous substrate and a ceramic layer formed on one or both sides of the porous substrate. Specifically, the ceramic layer including inorganic particles, a binder, and a particulate fusing agent, the ceramic layer satisfying the following formula 1, the binder being carboxymethyl cellulose having a weight average molecular weight of 180000g/mol to 280000g/mol, the composite separator according to the present invention can secure excellent heat resistance, adhesion, and fusing force with an electrode. [1] (In the above formula 1, T is the thickness (μm) of the ceramic layer, W1 is the content (wt%) of the binder with respect to the total weight of the ceramic layer, W2 is the content (wt%) of the particulate fusing agent with respect to the total weight of the ceramic layer, and D is the average particle diameter (μm) of the particulate fusing agent.)

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
20251030
Priority Date
20241107

Claims (15)

  1. 1. A composite separator includes a porous substrate, and a ceramic layer formed on one or both sides of the porous substrate, Wherein the ceramic layer contains inorganic particles, a binder and a particulate fusing agent, the ceramic layer satisfies the following formula 1, The binder is carboxymethyl cellulose having a weight average molecular weight of 180000g/mol to 280000g/mol, [ 1] In the above-mentioned formula (1), T is the thickness of the ceramic layer in μm; w1 is the content of the binder relative to the total weight of the ceramic layer in weight percent; W2 is the content of the particle type fusion agent relative to the total weight of the ceramic layer, and the unit is weight percent; D is the average particle diameter of the granular fusing agent, and the unit is mu m.
  2. 2. The composite separator of claim 1 wherein the particulate fusing agent has an average particle size D50 of from 1 μιη to 10 μιη.
  3. 3. The composite separator of claim 1 wherein the ceramic layer has a total thickness of 1 to 20 μιη.
  4. 4. The composite separator of claim 1 wherein the carboxymethyl cellulose has a degree of substitution of 0.6 to 1.2.
  5. 5. The composite separator according to claim 1, wherein the inorganic particles have an average particle diameter D50 of 0.01 μm to 1 μm.
  6. 6. The composite separator according to claim 1, wherein the inorganic particles are one or two 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.
  7. 7. The composite separator according to claim 1, wherein the content of the inorganic particles is 90 to 99 wt% with respect to the total weight of the ceramic layer.
  8. 8. The composite separator of claim 1 wherein the binder is present in an amount of 0.1 to 10 wt% relative to the total weight of the ceramic layer.
  9. 9. The composite separator of claim 1 wherein the particulate fusing agent is present in an amount of 0.1 to 10wt% relative to the total weight of the ceramic layer.
  10. 10. The composite separator of claim 1 wherein the weight ratio of the binder to the particulate fusing agent included is from 5:5 to 8:2.
  11. 11. The composite separator of claim 1 wherein the glass transition temperature T g of the particulate fusing agent is from 40 ℃ to 80 ℃.
  12. 12. The composite separator of claim 1 wherein the porous substrate is hydrophilic surface treated.
  13. 13. 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.
  14. 14. 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.
  15. 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, the ceramic layer comprising inorganic particles, a binder and a particulate fusing agent, the ceramic layer satisfying the following formula 1, the binder being carboxymethyl cellulose having a weight average molecular weight of 180000g/mol to 280000g/mol, [ 1] In the above-mentioned formula (1), T is the thickness of the ceramic layer in μm; w1 is the content of the binder relative to the total weight of the ceramic layer in weight percent; W2 is the content of the particle type fusion agent relative to the total weight of the ceramic layer, and the unit is weight percent; D is the average particle diameter of the granular fusing agent, and the unit is mu m.

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 causes separation of the separator from the electrode in the cell assembly process, thus causing distortion, deformation, etc. of the electrode assembly and causing short-circuiting between the electrodes, thus having a problem of safety. In order to solve these problems, a proposal has been made to introduce an adhesive layer alone, which can exert a fusion force with an electrode, on an inorganic coating layer. However, this scheme has problems in that it is difficult to apply to actual commercialization due to the increased process steps and the increased manufacturing costs, and the additional adhesive layer may increase the internal resistance of the battery, and thus may decrease the electrical properties. [ Prior Art literature ] [ Patent literature ] KR10-2573567B1 (2023, 08, 29) Disclosure of Invention First, the technical problem to be solved An embodiment of the present invention relates to a composite separator in which a particulate fusing agent is introduced into a ceramic layer, and provides a composite separator which can secure excellent heat resistance, adhesion force, and fusing force with an electrode and can prevent a blocking phenomenon even with a thin thickness. 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 ceramic layer formed on one or both sides of the porous substrate, wherein the ceramic layer includes inorganic particles, a binder, and a particulate fusing agent, the ceramic layer satisfies the following formula 1, and the binder is carboxymethyl cellulose having a weight average molecular weight of 180000g/mol to 280000 g/mol. [ 1] (In the above formula 1, T is the thickness (μm) of the ceramic layer, W1 is the content (wt%) of the binder with respect to the total weight of the ceramic layer, W2 is the content (wt%) of the particulate fusing agent with respect to the total weight of the ceramic layer, and D is the average particle diameter (μm) of the particulate fusing agent.) The average particle diameter (D50) of the particulate fluxing agent may be from 1 μm to 10 μm. The ceramic layer may have a total thickness of 1 μm to 20 μm. The carboxymethyl cellulose may have a degree of substitution of 0.6 to 1.2. The inorganic particles may have an average particle diameter (D50) of 0.01 μm to 1 μm. The inorganic particles may be one or two 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 content of the inorganic particles may be 90 to 99 wt% with respect to the total weight of the ceramic layer. The binder may be contained in an amount of 0.1 to 10 wt% with respect to the total weight of the ceramic layer. The particulate fusing agent may be contained in an amount of 0.1 to 10 wt% with respect to the total weight of the ceramic layer. The weight ratio of the binder to the particulate fluxing agent contained may be from 5:5 to 8:2. The glass transition temperature (T g) of the particulate fluxing agent may be from 40 ℃ to 80 ℃. The porous substrate may be hydrophilic surface treated. 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 ] (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 te