KR-20260064611-A - SPERATOR FOR ELECTROCHEMICAL DEVICE, MANUFACTURING METHOD THEREOF AND ELECTROCHEMICAL DEVICE INCLUDING THE SAME

Abstract

A separator for an electrochemical device according to an exemplary embodiment of the present invention comprises a porous polymer substrate, and the total pore volume span of the porous polymer substrate is 0.65 or higher.

Inventors

• 이승현
• 이병규
• 김유배
• 가경륜
• 김혜원

Assignees

• 주식회사 엘지에너지솔루션

Dates

Publication Date

20260507

Application Date

20251029

Priority Date

20241030

Claims (15)

1. In a separator for an electrochemical device comprising a porous polymer substrate, A separator for an electrochemical device having a Total Pore Volume Span value of 0.65 or higher of the above-mentioned porous polymer substrate.
2. In claim 1, A separator for an electrochemical device, wherein the porosity of the above-mentioned porous polymer substrate is greater than 45%.
3. In claim 1, A separator for an electrochemical device, wherein the electrical resistance (ER) of the porous polymer substrate is 0.37 ohm or less.
4. In claim 1, A separator for an electrochemical device, wherein the pore size D10 of the porous polymer substrate is 0.037 μm or less.
5. In claim 1, A separator for an electrochemical device, wherein the pore size D90 of the porous polymer substrate is 0.075 μm or larger.
6. In claim 1, A separator for an electrochemical device, wherein the difference in pore size (D90-D10) of the above porous polymer substrate is 40 nm or more.
7. In claim 1, A separator for an electrochemical device, wherein the air permeability of the porous polymer substrate before compression is 75 s/100cc or less.
8. In claim 1, A separator for an electrochemical device, wherein the air permeability of the porous polymer substrate after compression is 120 s/100cc or less.
9. In claim 1, An electrochemical device separator having a resistance increase rate of 40% or less.
10. The method includes the step of forming a porous polymer substrate by stirring a polymer resin and a pore-forming agent; A method for manufacturing a separator for an electrochemical device, characterized by adding the above-mentioned pore-forming agent two or more times.
11. In claim 10, The stirring speed of the above polymer resin and pore-forming agent is A method for manufacturing a separator for an electrochemical device, wherein the stirring speed when the pore-forming agent is added once is greater than the stirring speed when the pore-forming agent is added twice.
12. In claim 10, The stirring speed of the above polymer resin and pore-forming agent is A method for manufacturing a separator for an electrochemical device, wherein the stirring speed when the pore-forming agent is added once is 1.5 times or more and 3 times or less the stirring speed when the pore-forming agent is added twice.
13. In claim 10, The stirring speed of the above polymer resin and pore-forming agent is When the above pore-forming agent is injected once, the speed is 100 RPM or more and 300 RPM or less, and A method for manufacturing a separator for an electrochemical device, wherein the above-mentioned pore-forming agent is 50 RPM or more and 150 RPM or less when added twice.
14. In claim 13, The stirring speed of the above polymer resin and pore-forming agent is A method for manufacturing a separator for an electrochemical device, wherein the above-mentioned pore-forming agent is 20 RPM or more and 80 RPM or less when added three times.
15. An electrochemical device comprising: an anode; a cathode; and a separator of claim 1 interposed between the anode and the cathode.

Description

Separator for an electrochemical device, manufacturing method thereof, and electrochemical device including the same This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0150855 filed on October 30, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification. The present invention relates to a separator for an electrochemical device, a method for manufacturing the same, and an electrochemical device including the same. Electrochemical devices convert chemical energy into electrical energy using electrochemical reactions. Recently, lithium-ion batteries, which are a type of electrochemical device characterized by high energy density and voltage, long cycle life, and applicability in various fields, are being widely used. A lithium secondary battery may include an electrode assembly manufactured by combining a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes, and the electrode assembly may be manufactured by housing it in a case together with an electrolyte. The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. Figure 1 shows a graph of the total pore volume span of a porous polymer substrate according to one embodiment of the present invention. In parts of the attached drawings, corresponding components are given the same reference numerals. Those skilled in the art understand that the drawings are intended to illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to aid in understanding various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated compared to others. Additionally, elements of known technology that are useful or essential in commercially viable embodiments may often be omitted so as not to hinder the spirit of the various embodiments of the present invention. In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. In this specification, "A and/or B" means "A and B, or A or B". In this specification, “about,” “approximately,” and “substantially” are used to mean a range of numerical or degree or an approximation thereof, taking into account inherent manufacturing and material tolerances (e.g., ± 5%), and are used to prevent an infringer from unfairly using the disclosure in which precise or absolute figures provided to aid in understanding the invention are mentioned. In this specification, when a component is described as being "on" one component, this means that, unless specifically stated otherwise, other components may be placed in between, without excluding the placement of other components. In this specification, the characteristic of having pores means that a gaseous and/or liquid fluid can pass from one side to the other side of the object through a structure in which the object includes a plurality of pores and said pores are interconnected. In this specification, the separator has porous characteristics including a plurality of pores and acts as a porous ion-conducting barrier that blocks electrical contact between the cathode and the anode in an electrochemical device while allowing ions to pass through. Among the components of an electrochemical device, the separator may comprise a polymer substrate having a porous structure located between the anode and the cathode. The separator isolates the anode and the cathode to prevent an electrical short circuit between the two electrodes, while simultaneously allowing the electrolyte and ions to pass through. Although the separator itself does not participate in electrochemical reactions, its physical properties, such as wettability to the electrolyte, porosity, and thermal shrinkage rate, can affect the performance and safety of the electrochemical device. The porous polymer substrate included in the separator uses a polyolefin (polyethylene, polypropylene, etc.) film. Such a separator can be manufactured through a wet manufacturing method in which pores are formed using a pore-forming agent, or through a dry manufacturing method in which a polymer material is melted, manufactured into a membrane form, and then stretched to form pores. The present invention improves the air permeability and resistance of a porous polymer substrate by controlling the size and distribution of pores formed in the porous polymer substrate. The present invention will be described in more detail below. An electroc