EP-4738514-A1 - GEL POLYMER ELECTROLYTE-SEPARATOR COMPOSITE AND ELECTROCHEMICAL DEVICE COMPRISING SAME

Abstract

The present invention relates to a gel polymer electrolyte - separator composite for an electrochemical device and an electrochemical device comprising the same. According to the present invention, there are provided a gel polymer electrolyte - separator composite for an electrochemical device and an electrochemical device comprising the same, which are capable of preventing the occurrence of internal short-circuiting caused by the growth of lithium dendrites.

Inventors

• LEE, SEONGSOO
• KIM, SU JUN
• JIN, SUN MI

Assignees

• LG Chem, Ltd.

Dates

Publication Date

20260506

Application Date

20250611

Claims (16)

1. A gel polymer electrolyte - separator composite for an electrochemical device, comprising: a porous polymer substrate, a plurality of porous coating layers stacked in sequence on the porous polymer substrate, and a gel polymer electrolyte impregnated into the porous polymer substrate and the porous coating layers; wherein the plurality of porous coating layers comprise: a porous coating layer comprising at least one type of first inorganic fine particles selected from the group consisting of lithium titanium phosphate (Li x Ti y (PO 4 ) 3 , 0<x<2, 0<y<3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO 4 ) 3 , 0<x<2, 0<y<1, 0<z<3), (LiAlTiP) x O y -based glass (0<x<4, 0<y<13), lithium lanthanum titanate (Li x La y TiO 3 , 0<x<2, 0<y<3), lithium germanium thiophosphate (Li x Ge y P z S w , 0<x<4, 0<y<1, 0<z<1, 0<w<5), and SiS 2 -based glass (Li x Si y S z , 0<x<3, 0<y<2, 0<z<4), and a porous coating layer comprising at least one type of second inorganic fine particles selected from the group consisting of SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , Y 2 O 3 , Al 2 O 3 , boehmite (AIO(OH)), Al(OH) 3 , TiO 2 , SiC, and BaTiO 3 .
2. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 1, wherein the first inorganic fine particles are angular particles, granular particles, or spheroidal particles, and the second inorganic fine particles are acicular particles having an aspect ratio in a range of 5 to 10.
3. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 1, comprising: the porous polymer substrate; a first porous coating layer stacked on the porous polymer substrate and comprising the first inorganic fine particles; a second porous coating layer stacked on the first porous coating layer and comprising the second inorganic fine particles; and the gel polymer electrolyte impregnated into the porous polymer substrate and the porous coating layers.
4. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 1, wherein the plurality of porous coating layers each comprise a polymer binder and inorganic fine particles dispersed in the polymer binder.
5. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 4, wherein the polymer binder is at least one compound selected from the group consisting of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), spandex, butyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, and polyvinyl acetate.
6. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 4, wherein the plurality of porous coating layers each comprise 1 to 90 wt% of the polymer binder and 10 to 99 wt% of the inorganic fine particles.
7. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 1, wherein the porous polymer substrate comprises at least one polymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyamide-imide, polyetherimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, and polyethylene naphthalate.
8. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 1, wherein the gel polymer electrolyte comprises a lithium salt, a matrix gel polymer, and a non-aqueous organic solvent.
9. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 8, wherein the lithium salt is at least one compound selected from the group consisting of LiBF 4 , LiPF 6 , LiSbF 6 , LiAsF 6 , LiOH, LiOH·H 2 O, LiBOB, LiAlO 4 , LiAlCl 4 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CF 3 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , LiC 4 BO 3 , LiTFSI, LiFSI, LiCl, Lil, LiB(C 2 O 4 ) 2 , and LiClO 4 .
10. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 8, wherein the matrix gel polymer is one formed into a three-dimensional gel network structure by polymerization among multifunctional acrylate-based compounds.
11. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 10, wherein the multifunctional acrylate-based compound is at least one compound selected from the group consisting of tetraethylene glycol diacrylate, trimethylolpropane ethoxylate triacrylate, trimethylolpropane propoxylate triacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyester dimethacrylate, trimethylolpropane trimethacrylate, ethoxylated bisphenol A dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxylate tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.
12. The gel polymer electrolyte - separator composite for an electrochemical device according to Claim 8, wherein the non-aqueous organic solvent is at least one compound selected from the group consisting of methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone, dibutyl ether, tetrahydrofuran, cyclohexanone, benzene, fluorobenzene, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, ethyl alcohol, isopropyl alcohol, dimethylformamide, 1,3-dioxolane, dimethyl sulfone, sulfolane, and triethylene glycol dimethyl ether.
13. An electrochemical device comprising the gel polymer electrolyte - separator composite according to claim 1.
14. The electrochemical device according to claim 13, comprising a cathode, an anode, and the gel polymer electrolyte - separator composite interposed between the cathode and the anode.
15. The electrochemical device according to claim 14, wherein the anode comprises lithium metal or an alloy of lithium metal.
16. The electrochemical device according to claim 13, wherein the electrochemical device is a lithium secondary battery.

Description

[TECHNICAL FIELD] CROSS-REFERENCE TO RELATED APPLICATION(S) This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0077201 filed on June 13, 2024, and Korean Patent Application No. 10-2025-0075673 filed on June 10, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated as part of this specification. The present invention relates to a gel polymer electrolyte - separator composite and an electrochemical device comprising the same. [BACKGROUND OF ART] With the increasing functionality of mobile phones, notebook computers, tablet computers, mobile batteries, electric vehicles, personal mobility devices, and the like, the demand for electrochemical devices used as their driving power sources has been steadily increasing. In particular, lithium secondary batteries, which have a high operating voltage and high energy density per unit weight, are most widely used. A lithium secondary battery can generally be manufactured using a cathode and an anode comprising an electrode active material capable of inserting and extracting lithium ions, and an electrolyte that is a medium for transferring lithium ions. Conventionally, as the electrolyte, a liquid electrolyte, particularly an ion-conductive organic liquid electrolyte prepared by dissolving a salt in a non-aqueous organic solvent, has been mainly used. However, such a liquid electrolyte has a risk of leakage during operation, and the high flammability of the non-aqueous organic solvent used causes problems such as ignition and explosion. Moreover, the liquid electrolyte may decompose during the charge and discharge of a lithium secondary battery, or may cause side reactions with the electrodes to generate gas inside the battery. This phenomenon is further accelerated during high-temperature storage, so the amount of gas generated can increase. The continuously generated gas not only causes an increase in the internal pressure of the battery, leading to deformation of the battery such as swelling, but also causes local imbalance in adhesion on the electrode surfaces within the battery, leading to a problem where the electrode reaction does not occur uniformly over the entire electrode surface. To overcome these stability problems of the liquid electrolyte, a method of using a gel polymer electrolyte, which has a low risk of leakage, has been proposed. However, since the gel polymer electrolyte also contains a non-aqueous organic solvent, problems regarding the thermal stability of the electrochemical device are still being discussed. Meanwhile, in the case of an electrochemical device applying lithium metal as an anode, non-uniform lithium deposition occurs during repeated charge and discharge processes, and due to this, lithium dendrites grow on the surface of the lithium metal. However, abnormally grown lithium dendrites can penetrate the separator and cause an internal short-circuit with the cathode, leading to ignition and explosion. [DETAILED DESCRIPTION OF THE INVENTION] [Technical Problem] The present invention is intended to provide a gel polymer electrolyte - separator composite for an electrochemical device that can prevent the occurrence of an internal short-circuit due to the growth of lithium dendrites. In addition, the present invention is intended to provide an electrochemical device comprising the gel polymer electrolyte - separator composite for an electrochemical device. [Technical Solution] According to one embodiment of the invention, there is provided a gel polymer electrolyte - separator composite for an electrochemical device, comprising: a porous polymer substrate,a plurality of porous coating layers stacked in sequence on the porous polymer substrate, anda gel polymer electrolyte impregnated into the porous polymer substrate and the porous coating layers;wherein the plurality of porous coating layers comprise: a porous coating layer comprising at least one type of first inorganic fine particles selected from the group consisting of lithium titanium phosphate (LixTiy(PO4)3, 0<x<2, 0<y<3), lithium aluminum titanium phosphate (LixAlyTiz(PO4)3, 0<x<2, 0<y<1, 0<z<3), (LiAlTiP)xOy-based glass (0<x<4, 0<y<13), lithium lanthanum titanate (LixLayTiO3, 0<x<2, 0<y<3), lithium germanium thiophosphate (LixGeyPzSw, 0<x<4, 0<y<1, 0<z<1, 0<w<5), and SiS2-based glass (LixSiySz, 0<x<3, 0<y<2, 0<z<4), anda porous coating layer comprising at least one type of second inorganic fine particles selected from the group consisting of SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, boehmite (AIO(OH)), Al(OH)3, TiO2, SiC, and BaTiO3. According to another embodiment of the invention, there is provided an electrochemical device comprising the gel polymer electrolyte - separator composite. Hereinafter, a more detailed description will be given of the gel polymer electrolyte - separator composite for an electrochemical device and the electrochemical device comprising the same a