EP-4742418-A1 - SEPARATOR FOR ELECTROCHEMICAL DEVICE, MANUFACTURING METHOD THEREFOR, AND ELECTROCHEMICAL DEVICE COMPRISING SEPARATOR

Abstract

The present disclosure relates to a separator for an electrochemical device, a method for manufacturing the same and an electrochemical device including the separator, and more particularly, to a separator for an electrochemical device using different binders in a coating layer and patterning the coating layer, thereby reducing a difference between positive electrode adhesive strength and negative electrode adhesive strength, improving wetting and reducing resistance, a method for manufacturing the same and an electrochemical device including the separator.

Inventors

• BAE, DONG HUN
• SUNG, DONG WOOK
• KIM, JI EUN
• KIM, KYUNG TAE
• LEE, YONG HYEOK

Assignees

• LG Energy Solution, Ltd.

Dates

Publication Date

20260513

Application Date

20241029

Claims (14)

1. A separator for an electrochemical device, the separator comprising: a porous polymer substrate; and a coating layer provided on at least one surface of the porous polymer substrate and including a first polymer binder, a second polymer binder and inorganic particles, wherein a first surface portion including the first polymer binder and a second surface portion including the second polymer binder are alternately arranged on a surface of the coating layer.
2. The separator of claim 1, wherein the first polymer binder is a fluorine-based polymer binder.
3. The separator of claim 1, wherein the second polymer binder is a hybrid polymer of a fluorine-based polymer binder and an acryl-based polymer binder.
4. The separator of claim 1, wherein an area of the second surface portion is 40% or less based on a total surface area of the coating layer.
5. The separator of claim 1, wherein positive electrode adhesive strength of the first surface portion is greater than positive electrode adhesive strength of the second surface portion.
6. The separator of claim 1, wherein negative electrode adhesive strength of the second surface portion is greater than negative electrode adhesive strength of the first surface portion.
7. The separator of claim 1, wherein the coating layer has an average thickness of 0.5 µm or greater and 1.0 µm or less.
8. The separator of claim 1, wherein a content of the first polymer binder is 10 parts by weight or greater and 15 parts by weight or less with respect to 100 parts by weight of the coating layer.
9. The separator of claim 1, wherein a content of the second polymer binder is 10 parts by weight or greater and 15 parts by weight or less with respect to 100 parts by weight of the coating layer.
10. A method for manufacturing a separator for an electrochemical device, the method comprising: providing a coating layer by alternately coating a first slurry including a first polymer binder and a second slurry including a second polymer binder on at least one surface of a porous polymer substrate, wherein a first surface portion including the first polymer binder and a second surface portion including the second polymer binder are alternately arranged on a surface of the coating layer.
11. The method of claim 10, wherein the providing of a coating layer is performed using gravure coating, spray coating, slot die coating, bar coating or roll coating.
12. The method of claim 10, wherein a loading amount of the first slurry for a coating layer is greater than 7 g/m 2 and 10 g/m 2 or less.
13. The method of claim 10, wherein a loading amount of the second slurry for a coating layer is 4 g/m 2 or greater and 7 g/m 2 or less.
14. An electrochemical device comprising: a positive electrode; a negative electrode; and the separator of claim 1 interposed between the positive electrode and the negative electrode.

Description

Technical Field The present disclosure claims priority to and the benefits of Korean Patent Application Nos. 10-2023-0148006 and 10-2024-0148548 respectively filed with the Korean Intellectual Property Office on October 31, 2023 and October 28, 2024, the entire contents of which are incorporated herein by reference. The present disclosure relates to a separator for an electrochemical device, a method for manufacturing the same and an electrochemical device including the separator. In particular, the present disclosure relates to a separator for an electrochemical device using different binders in a coating layer and patterning the coating layer, thereby reducing a difference between positive electrode adhesive strength and negative electrode adhesive strength, improving wetting and reducing resistance, a method for manufacturing the same and an electrochemical device including the separator. Background Art Among components of an electrochemical device, a separator includes a polymer substrate having a porous structure located between a positive electrode and a negative electrode and separates the positive electrode and the negative electrode, and performs roles of preventing an electrical short-circuit between the two electrodes and allowing an electrolyte and ions to pass through. The separator itself does not participate in an electrochemical reaction, however, physical properties such as wetting for an electrolyte liquid, the degree of porosity and thermal shrinkage affect performance and safety of an electrochemical device. Accordingly, in order to strengthen physical properties of a separator, a coating layer is added to a porous polymer substrate, and various methods to change properties of the coating layer have been attempted by adding various materials to the coating layer. For example, inorganic substances may be added to the coating layer to improve mechanical strength of the separator, or inorganic substances or hydrates may be added to the coating layer to improve flame retardancy and heat resistance of the polymer substrate. A separator may be attached to an electrode through a lamination process, and in order to secure adhesive strength between the electrode and the separator, a polymer binder may be added to a composition for forming a coating layer of the separator. Meanwhile, adhesive strength with an electrode may vary depending on components of the polymer binder, and there is a problem in that a phenomenon of electrochemical device folding occurs due to asymmetry in adhesive strength between a positive electrode and a negative electrode. Furthermore, when adhesive strength with a positive electrode and adhesive strength with a negative electrode are both strong using an existing polymer binder, wetting for an electrolyte liquid decreases, and as a result, resistance of an electrochemical device may increase. Accordingly, there have been demands for studies on a technology capable of minimizing asymmetry in adhesive strength with a positive electrode and a negative electrode while maintaining adhesive strength with the positive electrode and the negative electrode at a certain level. DISCLOSURE Technical Problem The present disclosure is directed to providing a separator for an electrochemical device using binders having different adhesive strength for a positive electrode and a negative electrode in a coating layer and patterning the coating layer in order to prevent a phenomenon of separator folding caused by asymmetry in adhesive strength with the positive electrode and the negative electrode, and reduce resistance caused by a decrease in wetting, a method for manufacturing the same and an electrochemical device including the separator. However, problems to be solved by the present disclosure are not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. Technical Solution One embodiment of the present disclosure provides a separator for an electrochemical device, the separator including: a porous polymer substrate; and a coating layer provided on at least one surface of the porous polymer substrate and including a first polymer binder, a second polymer binder and inorganic particles, wherein a first surface portion including the first polymer binder and a second surface portion including the second polymer binder are alternately arranged on a surface of the coating layer. According to one embodiment of the present disclosure, the first polymer binder may be a fluorine-based polymer binder. According to one embodiment of the present disclosure, the second polymer binder may be a hybrid polymer of a fluorine-based polymer binder and an acryl-based polymer binder. According to one embodiment of the present disclosure, an area of the second surface portion may be 40% or less based on a total surface area of the coating layer. According to one embodiment of the present disclosure, posi