Separator for lithium-ion cell and lithium-ion cell using the same

Abstract

This invention provides a separator for lithium-ion batteries, comprising a substrate and a coating covering at least a portion of the surface of the substrate. The coating comprises garnet-type ceramic powder, specifically a lithium lanthanum zirconium oxide ceramic powder, wherein the surface of the garnet-type ceramic powder has one or more chemical substances containing hydrophilic functional groups. This invention also provides a lithium-ion battery using this separator.

Description

Technical Field

[0001] This invention relates to a separator for lithium-ion batteries, and more specifically, to a separator comprising garnet-type ceramic powder. This invention also relates to a lithium-ion battery comprising the separator. Prior Technology

[0002] Solid-state electrolytes are a research hotspot for next-generation lithium-ion batteries. Garnet-type ceramic powders have become a highly anticipated solid-state electrolyte material for lithium-ion batteries due to their high lithium-ion conductivity, wide electrochemical window, and thermal stability. However, the surface of garnet-type ceramic powders readily forms lithium carbonate (Li₂CO₃), making it hydrophobic and difficult to disperse in aqueous media. Therefore, the application of garnet-type ceramic powders in aqueous batteries, aqueous coatings, and other fields has been limited. Summary of the Invention

[0003] This invention modifies the surface of garnet-type ceramic powder to give the surface one or more chemical substances containing hydrophilic functional groups, thereby changing the hydrophilicity and hydrophobicity of the garnet-type ceramic powder, thus improving its dispersibility and stability in aqueous solvents, and enhancing the possibility of garnet-type ceramic powder in water-based coatings and related fields.

[0004] Therefore, one object of the present invention is to provide a separator for lithium-ion batteries, comprising a substrate and a coating covering at least a portion of the surface of the substrate, the coating comprising garnet-type ceramic powder, the garnet-type ceramic powder being a lithium lanthanum zirconium oxide ceramic powder, wherein the surface of the garnet-type ceramic powder has one or more chemical substances containing hydrophilic functional groups.

[0005] In one embodiment of the present invention, the chemical substance containing hydrophilic functional groups is a silane.

[0006] In one embodiment of the present invention, the hydrophilic functional group is selected from the group consisting of amino, hydroxyl, carboxyl, sulfonic acid and combinations thereof.

[0007] In one embodiment of the present invention, the chemical substance containing the hydrophilic functional group is selected from the group consisting of: N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEPTS), N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, and 3-aminopropylmethyldiethoxysilane. propylmethyldiethoxysilane), and 3-aminopropyldiisopropylethoxysilane.

[0008] In one embodiment of the present invention, the lithium lanthanum zirconium oxide ceramic powder system is selected from the following group of ceramic powders: Li6.75La3Zr1.75Ta0.25O12 (LLZTO), Li6.4Al0.2La3Zr2O12 (LLZAO), Li6.4Ga0.2La3Zr2O12 (LLZGO), Li6.25Al0.20La3Zr1.85Nb0.15O12, and combinations thereof.

[0009] In one embodiment of the present invention, the garnet-type ceramic powder has a D50 particle size of greater than 0.3 micrometers and less than 1.0 micrometers.

[0010] In one embodiment of the present invention, the material of the substrate is selected from the group consisting of polyethylene, polypropylene, polytetrafluoroethylene, polyvinyl chloride, and combinations thereof.

[0011] In one embodiment of the present invention, the coating is prepared by impregnating or coating the substrate with an aqueous dispersion containing the garnet-type ceramic powder and drying the impregnated or coated substrate.

[0012] Another object of the present invention is to provide a lithium-ion battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator as described above.

[0013] In one embodiment of the present invention, the material of the positive electrode is selected from the group consisting of: lithium iron phosphate (LiFePO4, LFP), lithium cobalt oxide (LiCoO2, LCO), lithium nickel cobalt aluminum oxide (NCA), and lithium nickel cobalt manganese oxide (NCM).

[0014] In one embodiment of the present invention, the material of the negative electrode is selected from the group consisting of lithium metal, lithium indium alloy, lithium aluminum alloy, lithium silicon alloy, and combinations thereof.

[0015] In one embodiment of the present invention, the electrolyte is a liquid electrolyte, and the liquid electrolyte is an electrolyte containing lithium salts selected from the group consisting of: LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, and combinations thereof.

[0016] To make the above-mentioned objectives, technical features and advantages of the present invention more apparent and understandable, the following detailed description is provided with reference to some specific embodiments. Simple Explanation of the Diagram

[0017] Figure 1 shows the X-ray diffraction spectra of garnet-type ceramic powders from Example 1 and Comparative Example 1. Figure 2 shows the Raman spectra of garnet-type ceramic powders from Example 1 and Comparative Example 1. Figure 3 shows the zeta potential spectra of garnet-type ceramic powders from Example 1 and Comparative Example 1. Figure 4 is a transmission electron microscope (TEM) photograph of the garnet-type ceramic powder of Example 1. Figure 5 is a TEM image of the garnet-type ceramic powder of Comparative Example 1. Figure 6 shows photographs of the dispersion stability test of garnet-type ceramic powders in Example 1 and Comparative Example 1. Figure 7 is a line graph showing the change in dispersion stability over time of garnet-type ceramic powders in Example 1 and Comparative Example 1. Implementation

[0018] The following will specifically describe some specific embodiments of the present invention; however, the present invention can be practiced in many different forms and the scope of protection of the present invention should not be limited to the specific embodiments described.

[0019] In the accompanying drawings, similar elements are represented by similar element symbols. For clarity, layers and areas may not be drawn to scale. Furthermore, unless otherwise stated, when a layer is described as being "on" another layer or substrate, the layer may be directly on that other layer or substrate, or there may be intervening layers(s) present.

[0020] Unless otherwise stated, the terms “a”, “the” and similar terms used in this specification and the claims shall be understood to include both singular and plural forms.

[0021] In this specification and the claims, the range of values ​​used (e.g., 5 to 100) should be understood to include all rational numbers in that range and any rational numbers in that range. Therefore, the range of values ​​used in this specification includes all possible combinations of values ​​between the listed minimum and maximum values.

[0022] Unless otherwise stated, in this specification and the scope of the claims, "positive electrode" refers to the cathode in the battery discharge state, and "negative electrode" refers to the anode in the battery discharge state.

[0023] Unless otherwise stated, in this specification and the scope of the patent application, "free of lithium carbonate" means that the lithium carbonate content of the garnet-type ceramic powder, as confirmed by Raman spectroscopy, is 0 or less than 0.1 ppm.

[0024] The advantage of this invention compared to existing technologies lies in its surface modification of garnet-type ceramic powder to alter its hydrophilicity and hydrophobicity, and its application of this garnet-type ceramic powder as a coating in the separator of lithium-ion batteries. This separator is particularly suitable for aqueous lithium-ion batteries, improving their ionic conductivity, electrochemical stability, and cycle stability. The following provides a detailed description of the separator of this invention and its related applications.

[0025] [1.] [Separator membrane used in lithium-ion batteries]

[0026] The separator for lithium-ion batteries of the present invention comprises a substrate and a coating, wherein the coating covers at least a portion of the surface of the substrate, preferably covering the entire surface of one side of the substrate, and more preferably covering the entire surface of both sides of the substrate. The substrate is, for example, a base film.

[0027] [1.1.] [coating]

[0028] In the separator for lithium-ion batteries of the present invention, the coating comprises garnet-type ceramic powder, and the garnet-type ceramic powder is a lithium lanthanum zirconium oxide ceramic powder, wherein the surface of the garnet-type ceramic powder has one or more chemical substances containing hydrophilic functional groups. In one embodiment of the present invention, the coating is substantially composed of garnet-type ceramic powder, or the coating is composed of garnet-type ceramic powder.

[0029] Garnet-type solid electrolytes are a type of oxide electrolyte, represented by Li7La3Zr2O12 (LLZO). Generally, garnet-type solid electrolytes exist in a high-temperature metastable cubic phase and a low-temperature / room-temperature stable tetragonal phase. In the tetragonal phase, lithium sites are 100% occupied, while the cubic phase has lithium vacancies, resulting in the ionic conductivity of tetragonal garnet being two orders of magnitude lower than that of cubic garnet. One method to stabilize cubic garnet is to directly dope and substitute Li+ to generate lithium vacancies. Another method is to use high-valence ions to substitute Zr4+, which can stabilize the cubic phase and achieve a high ionic conductivity close to 10⁻³ S / cm. In this invention, the garnet-type solid electrolyte powder system uses lithium lanthanum zirconium oxide ceramic powder. Examples of lithium lanthanum zirconium oxide ceramic powders include, but are not limited to, LLZTO, LLZAO, LLZGO, and Li6.25Al0.20La3Zr1.85Nb0.15O12. The aforementioned lithium lanthanum zirconium oxide ceramic powders can be used individually or in combination. In the appended examples, garnet-type solid electrolyte powder system LLZTO powder is used.

[0030] In this invention, the surface of the garnet-type solid electrolyte powder has one or more chemical substances containing hydrophilic functional groups. These hydrophilic functional groups can improve the dispersibility and stability of the garnet-type ceramic powder in aqueous solvents. Examples of the hydrophilic functional groups include, but are not limited to, amine, hydroxyl, carboxyl, and sulfonic acid groups, with amine groups being preferred.

[0031] In one embodiment of the present invention, the chemical substance containing a hydrophilic functional group is selected from silanes, preferably silanes containing an amino group. Examples of chemical substances containing a hydrophilic functional group include, but are not limited to, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEPTS), N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, and 3-aminopropyldiisopropylethoxysilane, wherein AEPTS, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and 3-aminopropyltriethoxysilane are preferred embodiments.

[0032] In a preferred embodiment of the present invention, the garnet-type ceramic powder, in addition to having one or more chemical substances containing hydrophilic functional groups, does not contain lithium carbonate, wherein the absence of lithium carbonate in the garnet-type ceramic powder is confirmed by Raman spectroscopy analysis.

[0033] Raman spectroscopy is commonly used for elemental analysis of ceramic materials, and compared to other elemental analysis methods such as X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence spectrometry (XRF), Raman spectroscopy has a lower analytical limit. Therefore, in this paper, a Raman spectrometer (model: DXR Raman Microscope; purchased from Thermo Fisher Scientific, USA) was used to confirm that garnet-type ceramic powder does not contain lithium carbonate. The analytical conditions were a 532 nm laser source and a laser power of 10 milliwatts (mW).

[0034] Using the Raman spectrometer described above under the aforementioned analytical conditions, the elemental composition of the sample can be detected up to a depth of approximately 0.1 micrometers from the surface, with a detection limit of 0.1 ppm. If no lithium carbonate signal is detected in the Raman spectroscopy analysis, it indicates that the lithium carbonate content of the garnet-type ceramic powder within the analytical depth is less than 0.1 ppm. Since lithium carbonate is generated by the reaction of carbon dioxide and water on the surface of the garnet-type ceramic powder, if no lithium carbonate is found from the surface of the garnet-type ceramic powder to the analytical depth, it can be confirmed that the garnet-type ceramic powder as a whole does not contain lithium carbonate, meaning that the overall lithium carbonate content of the garnet-type ceramic powder is less than 0.1 ppm.

[0035] The garnet-type ceramic powder containing a chemical substance with hydrophilic functional groups and free of lithium carbonate can be obtained by surface modification treatment of the garnet-type ceramic powder with an acidic solution containing a chemical substance with hydrophilic functional groups.

[0036] For example, an acidic solution can be prepared, and a chemical substance containing hydrophilic functional groups can be added to the acidic solution. The solution is then stirred at room temperature for 30 to 150 minutes to carry out a hydrolysis reaction, yielding a mixed solution. Garnet-type ceramic powder is added to the mixed solution, and the solution is stirred at 60°C to 80°C for 6 to 10 hours to perform surface modification. The acidic solution can be prepared by mixing an organic solvent with an acid, and the pH value of the acidic solution can be between 3.5 and 5.0. Examples of organic solvents include, but are not limited to, pure water, deionized water, ethanol, isopropanol, and acetone. The aforementioned organic solvents can be used alone or in combination. Examples of acids include, but are not limited to, acetic acid, phosphoric acid, carbonic acid, citric acid, boric acid, and formic acid. The aforementioned acids can be used alone or in combination. The concentration of the acidic solution can be from 0.1 M to 2.0 M. After surface treatment, the mixed solution containing the garnet-type ceramic powder is centrifuged in a centrifuge to obtain a precipitate of garnet-type ceramic powder that is free of lithium carbonate and contains hydrophilic functional groups. The centrifugation speed can be from 6000 rpm to 10000 rpm, and the centrifugation time can be from 5 minutes to 20 minutes.

[0037] In one embodiment of the present invention, the garnet-type ceramic powder system has a D50 particle size greater than 0.3 micrometers and less than 1.0 micrometers. For example, the D50 particle size of the garnet-type ceramic powder can be 0.3 micrometers, 0.4 micrometers, 0.5 micrometers, 0.6 micrometers, 0.7 micrometers, 0.8 micrometers, 0.9 micrometers, or 1.0 micrometers, or a range consisting of any two of the above values.

[0038] [1.2.] [Substrate]

[0039] The separator in a battery is used to isolate the positive and negative electrodes to prevent short circuits, while also allowing ions to pass through and retaining the electrolyte. Generally, the separator is a porous structure mainly composed of polymer films or non-woven fiber materials, exhibiting chemical and electrochemical stability to the electrolyte or electrode materials, and possessing a certain degree of mechanical strength. The substrate used in the separator of this invention is not particularly limited as long as it is a substrate applicable to separators in lithium-ion batteries within the technical field to which this invention pertains. For example, the substrate material can be selected from polyethylene, polypropylene, polytetrafluoroethylene, polyvinyl chloride, and any combination thereof.

[0040] [1.3.] [Preparation of the separating membrane]

[0041] In the release liner of the present invention, the coating can be prepared by impregnating or coating the substrate as described above with an aqueous dispersion containing the garnet-type ceramic powder as described above, and then drying the impregnated or coated substrate. The release liner of the present invention can be prepared as follows: First, the garnet-type ceramic powder is uniformly mixed with an aqueous dispersion medium to form an aqueous dispersion. Next, the aqueous dispersion is coated onto the substrate or the substrate is impregnated with the aqueous dispersion. Finally, the impregnated or coated substrate is subjected to a drying process to obtain the release liner. The method for coating the aqueous dispersion can be any coating method known in the art to which this invention pertains, examples of which include, but are not limited to, impregnation coating, slot coating, roller coating, and spin coating. The drying time and temperature are adjustable by those skilled in the art based on the type of solvent and process parameters, and will not be elaborated here.

[0042] Aqueous dispersion media may contain only water, or they may contain water and one or more water-soluble organic dispersion media (e.g., water-soluble organic compounds). Water-soluble organic dispersion media include, but are not limited to, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, tetrahydrofuran, and ethyl acetate.

[0043] [2.] [Lithium-ion battery]

[0044] The separator of the present invention can be used in batteries. Therefore, the present invention also provides a lithium-ion battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator as described above, wherein the separator is disposed between the positive electrode and the negative electrode.

[0045] The cathode material can be LFP, unary lithium cathode material, binary lithium cathode material, and ternary lithium cathode material. Examples of unary lithium cathode materials include, but are not limited to, LCO, lithium nickel oxide, and lithium manganese oxide. Examples of binary lithium cathode materials include, but are not limited to, lithium nickel cobalt oxide, LNMO, and lithium manganese cobalt oxide. Examples of ternary lithium cathode materials include, but are not limited to, NCA and NCM. In one embodiment of the present invention, the cathode material is selected from the following group: LFP, LCO, NCA, and NCM. Specific examples of NCA include, but are not limited to, LiNi0.8Co0.15Al0.05O2, LiNi0.8Co0.18Al0.02O2, and LiNi0.9Co0.05Al0.05O2. Specific examples of NCMs include, but are not limited to, LiNi0.33Co0.33Mn0.33O2 (NCM111), LiNi0.5Co0.2Mn0.3O2 (NCM523), LiNi0.6Co0.2Mn0.2O2 (NCM622), and LiNi0.8Co0.1Mn0.1O2 (NCM811). The aforementioned positive electrode materials can be used individually or in any combination. The negative electrode material can be selected from lithium metal, lithium-indium alloys, lithium-aluminum alloys, and lithium-silicon alloys. The aforementioned negative electrode materials can be used individually or in any combination.

[0046] The electrolyte used in the lithium-ion battery of this invention can be any electrolyte known in the art to which this invention pertains, including liquid electrolytes or solid electrolytes, with a preference for liquid electrolytes. Examples of liquid electrolytes include, but are not limited to, electrolytes containing lithium salts selected from the group consisting of: LiPF6, LiBF4, LiClO4, LiAsF6LiCF3SO3, and combinations thereof. Examples of solid electrolytes include, but are not limited to, Li3YCl6, Li3YBr6, Li6PS5Cl, LiGe2(PO4)3, Li10GeP2S12, Li7La3Zr2O12, and Li1.3Ti1.7Al0.3(PO4)3.

[0047] [3.] [Example]

[0048] [3.1.] Preparation of Garnet-type Ceramic Powder

[0049] [Example 1] Garnet-type ceramic powder containing a chemical substance with hydrophilic functional groups

[0050] First, an acidic solution was prepared by mixing 72 mL of ethanol, 4 mL of ultrapure water, and 2 mL of acetic acid at room temperature, with the pH value controlled between 3.5 and 5.0. Next, 1.02 g of AEPTS was added to the acidic solution, and the mixture was stirred at room temperature for 1 hour to carry out the hydrolysis reaction of silane, yielding a mixed solution. Then, 1 g of LLZTO powder was added to the mixed solution, and the mixture was stirred at 70°C for 8 hours to perform surface modification. Finally, the mixed solution was centrifuged at 8000 rpm for 10 minutes. The precipitate obtained after centrifugation was collected and dried under vacuum for 24 hours to obtain the garnet-type ceramic powder of Example 1.

[0051] [Comparative Example 1] Garnet-type ceramic powder without chemical substances containing hydrophilic functional groups

[0052] Prepare 1 gram of LLZTO powder used in Example 1 as the garnet-type ceramic powder of Comparative Example 1, but without performing the mixed solution treatment as in Example 1.

[0053] [3.2.] Analysis of Garnet-type Ceramic Powder

[0054] X-ray diffraction analysis was performed on the garnet-type ceramic powder of Example 1 and the garnet-type ceramic powder of Comparative Example 1 using an X-ray powder diffractometer (model: D2 PHASER, purchased from Bruker). The results are shown in Figure 1. As shown in Figure 1, compared with the garnet-type ceramic powder of Comparative Example 1, the characteristic peak positions, shapes, and relative intensities of the garnet-type ceramic powder of Example 1 are approximately the same, indicating that the garnet-type ceramic powder of Example 1 still maintains a pure garnet-type structure even after surface modification.

[0055] Raman analysis was performed on the garnet-type ceramic powders of Example 1 and Comparative Example 1 using a DXR Raman Microscope. The results are shown in Figure 2. As shown in Figure 2, the garnet-type ceramic powder of Comparative Example 1 showed a significant lithium carbonate signal peak at 1000 cm⁻¹. In contrast, the garnet-type ceramic powder of Example 1 did not show a significant signal peak at 1000 cm⁻¹, indicating that the garnet-type ceramic powder of Example 1 did not contain lithium carbonate. Furthermore, the garnet-type ceramic powder of Example 1 showed Si-O-Si stretching vibrations, CH₂ vibrations, and CH stretching vibrations in the propyl chain at approximately 900 cm⁻¹, 1500 cm⁻¹, and 2800 cm⁻¹ to 3000 cm⁻¹, respectively. This indicates that AEPTS has been successfully bonded to the surface of LLZTO and a stable Si-O-Si bond has been formed. In particular, the Si-O-Si peak at approximately 900 cm⁻¹ confirms that a stable covalent bond has been formed between the silane and the LLZTO surface.

[0056] The zeta potential of the garnet-type ceramic powder of Example 1 and Comparative Example 1 was analyzed using a Zetasizer Nano ZA analyzer (purchased from Malvern Panalytical). The results are shown in Figure 3. As shown in Figure 3, the zeta potential of the garnet-type ceramic powder of Comparative Example 1 is negative, indicating that its surface exhibits a signal of carbonate ions (CO32-) due to the presence of a large amount of lithium carbonate. In contrast, the zeta potential of the garnet-type ceramic powder of Example 1 is positive, indicating that its surface has indeed been successfully modified by AEPTS, as the amine functional groups are positively charged. Therefore, the positive zeta potential confirms that the surface of the garnet-type solid electrolyte of the present invention contains chemical substances with hydrophilic functional groups (amine groups).

[0057] TEM images of the garnet-type ceramic powder of Example 1 and Comparative Example 1 were taken using a TEM (model: JEM-2100F, purchased from JEOL Ltd.). The results are shown in Figures 4 and 5, respectively. As shown in Figure 4, the surface of the garnet-type ceramic powder of Example 1 lacks lithium carbonate and has a silane coating with a thickness of approximately 3 to 4 nanometers, indicating that its surface has indeed been successfully modified by AEPTS. This confirms that the surface of the garnet-type solid electrolyte of the present invention contains a chemical substance with hydrophilic functional groups (amine groups). As shown in Figure 5, the surface of the garnet-type ceramic powder of Comparative Example 1 has an uneven lithium carbonate layer with a thickness of approximately 20 to 40 nanometers. Without being limited by theory, it is believed that the lithium carbonate layer is the reason for the hydrophobicity of the garnet-type ceramic powder.

[0058] The garnet-type ceramic powder of Example 1 and the garnet-type ceramic powder of Comparative Example 1 were dispersed in water at a concentration of 0.5 mg / mL to form dispersions for dispersion stability testing. The dispersion stability test was conducted as follows: the dispersions were allowed to stand for 24 hours, and photographs were taken after 1 hour, 6 hours, 12 hours, and 24 hours to visually observe the changes in the dispersions. The results of the dispersion stability are shown in Figure 6. It can be seen that the dispersion formed by the garnet-type ceramic powder of Comparative Example 1 showed sedimentation after 1 hour, and almost complete sedimentation after 6 hours, indicating that the garnet-type ceramic powder of Comparative Example 1 has extremely poor dispersion stability. In contrast, the dispersion formed by the garnet-type ceramic powder of Example 1 showed almost no change in appearance after 24 hours (i.e., it still maintained a uniformly dispersed state), indicating that the garnet-type ceramic powder of Example 1 has excellent dispersion stability.

[0059] Furthermore, the dispersion stability results of the garnet-type ceramic powder of Example 1 and the garnet-type ceramic powder of Comparative Example 1 were plotted as a time-varying line graph, as shown in Figure 7. As shown in Figure 7, compared with the garnet-type ceramic powder of Comparative Example 1, the garnet-type ceramic powder of Example 1 exhibits significantly improved dispersion stability. This demonstrates that the garnet-type ceramic powder system of the present invention possesses excellent dispersibility and stability in aqueous solvents through surface modification with a chemical substance containing hydrophilic functional groups. Therefore, this garnet-type ceramic powder can be applied as a coating to the separator of an aqueous lithium-ion battery, thereby improving the ionic conductivity, electrochemical stability, and cycle stability of the lithium-ion battery.

[0060] The above embodiments are merely illustrative of the principles and effects of the present invention and to illustrate its technical features, and are not intended to limit the scope of protection of the present invention. Any changes or arrangements that can be easily made by those skilled in the art are within the scope of the present invention. Therefore, the scope of protection of the present invention is as set forth in the appended claims.

Claims

1. A separator for lithium-ion batteries, comprising a substrate and a coating covering at least a portion of the surface of the substrate, the coating comprising garnet-type ceramic powder, the garnet-type ceramic powder being a lithium lanthanum zirconium oxide ceramic powder, wherein the surface of the garnet-type ceramic powder has one or more chemical substances containing hydrophilic functional groups, wherein the chemical substances containing hydrophilic functional groups are silanes.

2. The separator as claimed in claim 1, wherein the hydrophilic functional group is selected from the group consisting of amino, hydroxyl, carboxyl, sulfonic acid, and combinations thereof.

3. The separator membrane as described in claim 1 or 2, wherein the chemical substance containing the hydrophilic functional group is selected from the group consisting of: N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEPTS), N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and 3-aminopropyltriethoxysilane. ilane), vinyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, and 3-aminopropyldiisopropylethoxysilane.

4. The separator as described in claim 1 or 2, wherein the lithium lanthanum zirconium oxide ceramic powder system is selected from the group consisting of ceramic powders of the following: Li6.75La3Zr1.75Ta0.25O12 (LLZTO), Li6.4Al0.2La3Zr2O12 (LLZAO), Li6.4Ga0.2La3Zr2O12 (LLZGO), Li6.25Al0.20La3Zr1.85Nb0.15O12, and combinations thereof.

5. The isolation membrane as claimed in claim 1 or 2, wherein the garnet-type ceramic powder has a D50 particle size greater than 0.3 micrometers and less than 1 micrometer.

6. The separator as claimed in claim 1 or 2, wherein the material of the substrate is selected from the group consisting of polyethylene, polypropylene, polytetrafluoroethylene, polyvinyl chloride, and combinations thereof.

7. The isolation membrane as claimed in claim 1 or 2, wherein the coating is prepared by impregnating or coating the substrate with an aqueous dispersion containing the garnet-type ceramic powder and drying the impregnated or coated substrate.

8. A lithium-ion battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator as described in any one of claims 1 to 7.

9. The lithium-ion battery as claimed in claim 8, wherein the material of the positive electrode is selected from the group consisting of lithium iron phosphate (LiFePO4, LFP), lithium cobalt oxide (LiCoO2, LCO), lithium nickel cobalt aluminum oxide (NCA), and lithium nickel cobalt manganese oxide (NCM).

10. The lithium-ion battery as claimed in claim 8 or 9, wherein the material of the negative electrode is selected from the group consisting of lithium metal, lithium indium alloy, lithium aluminum alloy, lithium silicon alloy, and combinations thereof.

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