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US-20260128469-A1 - SEPARATOR AND ELECTROCHEMICAL DEVICE INCLUDING THE SAME

US20260128469A1US 20260128469 A1US20260128469 A1US 20260128469A1US-20260128469-A1

Abstract

Separator and electrochemical devices including separators are disclosed. In an embodiment, a separator includes: a substrate; an inorganic particle layer formed on at least one surface of the substrate; and an adhesive layer formed on the inorganic particle layer, wherein an adhesive strength Fx) is defined as a force measured between a probe and a surface of the separator at a stage temperature of x° C. using an atomic force microscope (AFM) equipped with the probe having a spring constant of 40 N/m, an average radius of 8 nm, and a scanning speed of 0.5 Hz, wherein F40 is in a range of 1 nN to 30 nN, and wherein the separator satisfies the following Formula 1: F75/F40≥5.

Inventors

  • Dong Jae Kim
  • Cheol Min Yun
  • Dong Il Jang
  • Soon Bo LEE

Assignees

  • SK INNOVATION CO., LTD.
  • SK IE TECHNOLOGY CO., LTD.

Dates

Publication Date
20260507
Application Date
20251021
Priority Date
20241107

Claims (20)

  1. 1 . A separator for an electrochemical device including a battery comprising: a substrate; an inorganic particle layer formed on at least one surface of the substrate; and an adhesive layer formed on the inorganic particle layer, wherein an adhesive strength (Fx) is defined as a force measured between a probe and a surface of the separator at a stage temperature of x° C. using an atomic force microscope (AFM) equipped with the probe having a spring constant of 40 N/m, an average radius of 8 nm, and a scanning speed of 0.5 Hz, wherein F40 representing the adhesive strength measured at 40° C. is in a range of 1 nN to 30 nN, and wherein the separator satisfies the following Formula 1: F ⁢ 75 / F ⁢ 40 ≥ 5. [ Formula ⁢ 1 ]
  2. 2 . The separator of claim 1 , wherein the adhesive layer includes a particulate polymer binder.
  3. 3 . The separator of claim 1 , wherein the adhesive layer includes an acryl-based polymer binder.
  4. 4 . The separator of claim 2 , wherein the particulate polymer binder has a core-shell structure that includes a core and a shell.
  5. 5 . The separator of claim 4 , wherein a glass transition temperature of a polymer included in the core of the particulate polymer binder is 30° C. to 70° C.
  6. 6 . The separator of claim 4 , wherein a glass transition temperature of a polymer included in the shell of the particulate polymer binder is 70° C. to 110° C.
  7. 7 . The separator of claim 4 , wherein a glass transition temperature (Tg,c) of the polymer included in the core and the glass transition temperature (Tg,s) of the polymer included in the shell satisfy the following Formula 2: 50 ⁢ ° ⁢ C . ≤ ( Tg , c + Tg , s ) / 2 ≤ 90 ⁢ ° ⁢ C . [ Formula ⁢ 2 ]
  8. 8 . The separator of claim 1 , wherein the adhesive layer includes: a first copolymer including a repeating unit derived from an acryl-based monomer; and a second copolymer including a repeating unit derived from an acryl-based monomer and styrene.
  9. 9 . The separator of claim 1 , wherein the adhesive layer includes a particulate acryl-based polymer binder having an average particle diameter (D50) of 400 nm to 800 nm.
  10. 10 . The separator of claim 1 , wherein the F75 is 40 nN to 300 nN.
  11. 11 . The separator of claim 1 , wherein Formula 1 satisfies F75/F40≥10.
  12. 12 . The separator of claim 1 , wherein the adhesive layer includes a particulate acryl-based polymer binder including a repeating unit derived from a compound represented by Chemical Formula 1: wherein R 1 is hydrogen or a C 1-10 alkyl group; and R 2 is hydrogen or a C 1-20 hydrocarbon group.
  13. 13 . The separator of claim 1 , wherein the inorganic particle layer includes inorganic particles and a polymer binder.
  14. 14 . The separator of claim 1 , wherein the inorganic particle layer includes inorganic particles having an average particle diameter (D50) of 100 nm to 1500 nm, where in 50% of the inorganic particles have particle diameters less than the average particle diameter (D50).
  15. 15 . The separator of claim 1 , wherein the inorganic particle layer includes first inorganic particles having an average particle diameter (D50) of 100 nm to 500 nm and second inorganic particles having an average particle diameter (D50) of 500 nm to 1500 nm, wherein 50% of the inorganic particles have particle diameters less than the average particle diameter (D50).
  16. 16 . The separator of claim 1 , wherein the inorganic particle layer includes inorganic particles and a polymer binder, and a weight ratio between the inorganic particles and the polymer binder is 90:10 to 99:1.
  17. 17 . The separator of claim 1 , wherein the inorganic particle layer has a thickness of 0.5 μm to 3.0 μm.
  18. 18 . The separator of claim 1 , wherein the adhesive layer has a thickness of 0.05 μm to 2.0 μm.
  19. 19 . An electrochemical device comprising a separator including: a substrate; an inorganic particle layer formed on at least one surface of the substrate; and an adhesive layer formed on the inorganic particle layer, wherein an adhesive strength (Fx) is defined as a force measured between a probe and a surface of the separator at a stage temperature of x° C. using an atomic force microscope (AFM) equipped with the probe having a spring constant of 40 N/m, an average radius of 8 nm, and a scanning speed of 0.5 Hz, wherein F40 representing the adhesive strength measured at 40° C. is in a range of 1 nN to 30 nN, and wherein the separator satisfies the following Formula 1: F ⁢ 75 / F ⁢ 40 ≥ 5. [ Formula ⁢ 1 ]
  20. 20 . An electrochemical device comprising a separator including: a substrate; an inorganic particle layer formed on at least one surface of the substrate; and an adhesive layer formed on the inorganic particle layer, wherein the electrochemical device exhibits a cycle number (C), defined as a number of charging and discharging cycles at which an internal resistance value of the electrochemical device increases by 30% compared to an initial internal resistance of the electrochemical device before staring the charging and discharging cycles, wherein C is 300 or more, and wherein each of the charging and discharging cycles is performed by: discharging the electrochemical device to 2.5 V; charging the electrochemical device from 2.5 V to 4.2 V at a current rate of 0.5 C; and discharging at a current rate of 0.5 C.

Description

PRIORITY CLAIM AND CROSS-REFERENCE TO RELATED APPLICATIONS This patent document claims the priority and benefits of Korean Patent Application No. 10-2024-0156730, filed on Nov. 7, 2024, the disclosure of which is incorporated herein by reference in its entirety. TECHNICAL FIELD The disclosed technology relates to a separator and an electrochemical device including the same. BACKGROUND In recent years, there has been a rapidly growing interest in electrochemical devices used in mobile phones, laptops, electric vehicles, and similar applications, along with their energy storage technologies. In particular, active research is being conducted on separators, which are key components that significantly influence the performance of secondary batteries, a common type of the electrochemical devices. Since the separator is impregnated with an electrolyte and functions as an ion channel, it plays a significant role in determining on the physical properties of the secondary batteries. SUMMARY The disclosed technology can be implemented in some embodiments to provide a separator in which the adhesive strength of a surface of the separator, measured using a probe of an atomic force microscope (AFM) capable of temperature adjustment, is maintained within a specific range. The disclosed technology can be implemented in some embodiments to provide an electrochemical device including the separator. In one general aspect, a separator comprises: a substrate; an inorganic particle layer formed on at least one surface of the substrate; and an adhesive layer formed on the inorganic particle layer, wherein an adhesive strength (Fx) is defined as a force measured between a probe and a surface of the separator at a stage temperature of x° C. using an atomic force microscope (AFM) equipped with the probe having a spring constant of 40 N/m, an average radius of 8 nm, and a scanning speed of 0.5 Hz, wherein F40 representing the adhesive strength measured at 40° C. is in a range of 1 nN to 30 nN, and wherein the separator satisfies the following Formula 1: F75/F40≥5. In another general aspect, an electrochemical device comprising a separator includes a substrate; an inorganic particle layer formed on at least one surface of the substrate; and an adhesive layer formed on the inorganic particle layer, wherein an adhesive strength (Fx) is defined as a force measured between a probe and a surface of the separator at a stage temperature of x° C. using an atomic force microscope (AFM) equipped with the probe having a spring constant of 40 N/m, an average radius of 8 nm, and a scanning speed of 0.5 Hz, wherein F40 representing the adhesive strength measured at 40° C. is in a range of 1 nN to 30 nN, and wherein the separator satisfies the following Formula 1: F75/F40≥5. In one general aspect, a separator includes: a substrate; an inorganic particle layer formed on at least any one surface of the substrate; and an adhesive layer formed on the at least one inorganic particle layer, wherein when adhesive strength between a probe and a surface of the separator, which is measured at a stage temperature of x° C. using the probe of an atomic force microscope having a spring constant of 40 N/m, an average radius of 8 nm, and a scanning speed of 0.5 Hz, is Fx,F40 is 1 nN to 30 nN, andthe separator satisfies the following Formula 1: F⁢75/F⁢40≥5.[Formula⁢ 1] In an example embodiment, the adhesive layer may include a particulate polymer binder. In an example embodiment, the adhesive layer may include an acryl-based polymer binder. In an example embodiment, the particulate polymer binder may have a core-shell structure. In an example embodiment, a glass transition temperature of a polymer included in a core of the particulate polymer binder may be 30° C. to 70° C., and/or a glass transition temperature of a polymer included in a shell of the particulate polymer binder may be 70° C. to 110° C. In an example embodiment, the glass transition temperature (Tg,c) of the polymer included in the core and the glass transition temperature (Tg,s) of the polymer included in the shell may satisfy the following Formula 2: 50⁢°⁢ C.≤(Tg,c+Tg,s)/2≤90⁢°⁢ C.[Formula⁢ 2] In an example embodiment, the adhesive layer may include a copolymer composed of a repeating unit derived from an acryl-based monomer; and a copolymer composed of a repeating unit derived from an acryl-based monomer and styrene. In an example embodiment, the adhesive layer may include a particulate polymer binder or a particulate acryl-based polymer binder having an average particle diameter (D50) of 400 nm to 800 nm. In an example embodiment, the F75 may be 40 nN to 300 nN. In an example embodiment, Formula 1 may satisfy F75/F40≥10. In an example embodiment, the adhesive layer may include a particulate polymer binder or a particulate acryl-based polymer binder including a repeating unit derived from a compound represented by the following Chemical Formula 1: In some implementations, R1 is hydrogen or