A ceramic-coated separator containing a solid-state electrolyte and a method of making the same

Abstract

The application relates to the technical field of lithium ion battery separators, and discloses a ceramic-coated separator containing a solid electrolyte and a preparation method thereof. The ceramic-coated separator comprises a base film and a ceramic coating arranged on the surface of the base film. The raw material of the ceramic coating comprises the following components in parts by weight: 30-50 parts of ceramic powder, 40-50 parts of solid electrolyte and 100-200 parts of solvent. The above technical scheme solves the problem of poor heat resistance and ionic conductivity of the lithium ion battery separator in the related art.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery separator technology, specifically to a ceramic-coated separator containing a solid electrolyte and its preparation method. Background Technology

[0002] With the rapid development of lithium-ion battery technology, market demands for battery performance are constantly increasing. As a key component of the battery, the performance of the separator, especially its heat resistance and ionic conductivity, directly affects the battery's safety, cycle life, and energy density.

[0003] Traditional lithium-ion battery separators are mostly made of polyethylene or polypropylene. These separators have poor heat resistance and high thermal shrinkage, which can easily lead to internal short circuits in lithium-ion batteries, making it difficult to provide protection. Furthermore, traditional liquid electrolyte separators face challenges in processing and have limited ionic conductivity. Therefore, to meet market demands, there is an urgent need to develop a lithium-ion battery separator that combines excellent heat resistance and ionic conductivity. Summary of the Invention

[0004] This invention proposes a ceramic-coated separator containing a solid electrolyte and its preparation method, which solves the problems of poor heat resistance and ionic conductivity of lithium-ion battery separators in related technologies.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention proposes a ceramic-coated separator containing a solid electrolyte, comprising a base membrane and a ceramic coating disposed on the surface of the base membrane;

[0007] The raw materials for the ceramic coating include the following components in parts by weight: 30-50 parts ceramic powder, 40-50 parts solid electrolyte, and 100-200 parts solvent.

[0008] As a further technical solution, the base film is a polyolefin film, preferably a polyethylene film.

[0009] As a further technical solution, the thickness of the base film is 8~10μm, preferably 9μm.

[0010] As a further technical solution, the thickness of the ceramic coating is 2~4μm, preferably 3μm.

[0011] As a further technical solution, the ceramic powder includes one or more of alumina, boehmite, silicon dioxide, and magnesium oxide.

[0012] In this invention, the type of ceramic powder can be freely selected according to the actual application scenario. For example, alumina ceramic powder can be selected for power equipment such as electric vehicles; boehm ceramic powder can be selected for electronic products that are more sensitive to battery weight, such as laptops and smartphones; and silica ceramic powder can be selected for products that require fast charging and discharging.

[0013] As a further technical solution, the solid electrolyte includes one of NASICON-type solid electrolyte and garnet-type solid electrolyte; the NASICON-type solid electrolyte is preferably lithium titanium aluminum phosphate; the garnet-type solid electrolyte is preferably lithium lanthanum zirconium oxide.

[0014] As a further technical solution, the median particle size of the ceramic powder is 1~1.5μm.

[0015] As a further technical solution, the solid electrolyte is a nanoscale solid electrolyte.

[0016] In this invention, by adding a nanoscale solid electrolyte, the problem of poor interfacial contact of the solid electrolyte is improved by utilizing the strong adsorption properties of nanoparticles, thereby further enhancing the ionic conductivity of the ceramic-coated membrane.

[0017] As a further technical solution, the median particle size of the nanoscale solid electrolyte is 100~200nm.

[0018] As a further technical solution, the nanoscale solid electrolyte is a modified nanoscale solid electrolyte obtained by modification with a modifier;

[0019] The modifiers include 3,5-di-tert-butylsalicylic acid and lauric acid.

[0020] In this invention, although the addition of nanoscale solid electrolytes can further improve the ionic conductivity of ceramic-coated membranes, the tendency of nanoscale solid electrolytes to aggregate limits the further improvement in ionic conductivity. The inventors discovered that modifying nanoscale solid electrolytes with 3,5-di-tert-butylsalicylic acid and lauric acid can further improve the ionic conductivity of ceramic-coated membranes. It is hypothesized that 3,5-di-tert-butylsalicylic acid and lauric acid can synergistically increase the steric hindrance of nanoscale solid electrolytes, reducing their aggregation tendency, thereby further improving the ionic conductivity of ceramic-coated membranes.

[0021] As a further technical solution, the weight ratio of 3,5-di-tert-butylsalicylic acid to lauric acid is 1~4:1.

[0022] In this invention, when the weight ratio of 3,5-di-tert-butylsalicylic acid to lauric acid is 1 to 4:1, the ionic conductivity of the ceramic-coated membrane can be further improved.

[0023] As a further technical solution, the modification includes the following steps: dissolving the modifier in ethanol, adding the nanoscale solid electrolyte, dispersing it evenly, and drying it to obtain the modified nanoscale solid electrolyte.

[0024] As a further technical solution, the weight ratio of the modifier to the nanoscale solid electrolyte is 5~10:100.

[0025] As a further technical solution, the solvent includes one of dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0026] As a further technical solution, the raw material of the ceramic coating also includes 1 to 5 parts of dispersant;

[0027] The dispersant includes one or more of fatty alcohol polyoxyethylene ether, sodium dodecylbenzenesulfonate, and perfluoroalkyl ethoxy ether alcohol.

[0028] In this invention, the addition of a dispersant helps to improve the mixing effect of the ceramic coating raw materials, thereby ensuring the uniformity of the ceramic coating and improving the overall performance of the ceramic coating diaphragm.

[0029] The present invention also proposes a method for preparing a ceramic-coated separator containing a solid electrolyte, comprising the following steps: mixing the raw materials of the ceramic coating evenly to obtain a ceramic coating slurry, coating the ceramic coating slurry onto the surface of a base membrane, and drying to obtain a ceramic-coated separator.

[0030] The working principle and beneficial effects of this invention are as follows:

[0031] In this invention, the raw materials for the ceramic coating include ceramic powder and a solid electrolyte. By using both together, the ceramic-coated separator not only possesses the excellent heat resistance of ceramic materials but also the high ionic conductivity of solid electrolytes. This improves the safety, stability, and adaptability to extreme environments of lithium-ion batteries, thereby broadening their application range. Furthermore, the raw materials for the ceramic coating are simple and readily available, enabling large-scale production. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise specified, the median particle size of alumina and boehmite in the following examples and comparative examples is 1 μm; the molecular formula of micron-sized lithium aluminum titanium phosphate is Li. 1.3 Al0.3 Ti l.7 P3O 12 The median particle size is 1 μm; the molecular formula of nano-sized lithium titanium aluminum phosphate is Li. 1.3 Al 0.3 Ti l.7 P3O 12 The median particle size is 200 nm; the molecular formula of the micron-sized lithium lanthanum zirconium oxide is Li7La3Zr2O. 12 The median particle size is 1 μm; the model number of the perfluoroalkyl ethoxy ether alcohol is S201.

[0034] Example 1

[0035] A method for preparing a ceramic-coated separator containing a solid electrolyte includes the following steps: mixing 30 parts by weight of alumina, 40 parts by weight of micron-sized lithium lanthanum zirconium oxide, 1 part by weight of perfluoroalkyl ethoxy ether alcohol and 100 parts by weight of dimethylformamide to obtain a ceramic coating slurry; coating the ceramic coating slurry onto the surface of a polyethylene membrane; and drying with hot air to obtain a ceramic-coated separator.

[0036] The polyethylene film has a thickness of 9 μm, and the ceramic coating has a thickness of 3 μm.

[0037] Example 2

[0038] A method for preparing a ceramic-coated separator containing a solid electrolyte includes the following steps: mixing 50 parts by weight of boehmite, 50 parts by weight of micron-sized lithium titanium aluminum phosphate, 5 parts by weight of perfluoroalkyl ethoxy ether alcohol and 200 parts by weight of dimethylformamide to obtain a ceramic coating slurry; coating the ceramic coating slurry onto the surface of a polyethylene membrane; and drying with hot air to obtain a ceramic-coated separator.

[0039] The polyethylene film has a thickness of 9 μm, and the ceramic coating has a thickness of 3 μm.

[0040] Example 3

[0041] The only difference between this embodiment and Embodiment 2 is that, in this embodiment, the micron-sized lithium titanium aluminum phosphate is replaced with an equal amount of nano-sized lithium titanium aluminum phosphate.

[0042] Example 4

[0043] The only difference between this embodiment and Embodiment 3 is that in this embodiment, the nano-sized lithium titanium aluminum phosphate is modified nano-sized lithium titanium aluminum phosphate. The modification method includes the following steps: dissolving 5 parts of 3,5-di-tert-butylsalicylic acid in 150 parts of ethanol, adding 100 parts of nano-sized solid electrolyte, dispersing evenly, and drying to obtain modified nano-sized lithium titanium aluminum phosphate.

[0044] Example 5

[0045] The only difference between this embodiment and Embodiment 4 is that, in this embodiment, 3,5-di-tert-butylsalicylic acid is replaced with an equal amount of lauric acid.

[0046] Example 6

[0047] The only difference between this embodiment and Embodiment 4 is that in this embodiment, 5 parts of 3,5-di-tert-butylsalicylic acid are replaced with 1 part of 3,5-di-tert-butylsalicylic acid and 4 parts of lauric acid.

[0048] Example 7

[0049] The only difference between this embodiment and Embodiment 6 is that in this embodiment, the weight parts of 3,5-di-tert-butylsalicylic acid are 4.5 parts and the weight parts of lauric acid are 0.5 parts.

[0050] Example 8

[0051] The only difference between this embodiment and Embodiment 6 is that, in this embodiment, the weight parts of 3,5-di-tert-butylsalicylic acid are 2.5 parts and the weight parts of lauric acid are 2.5 parts.

[0052] Example 9

[0053] The only difference between this embodiment and Embodiment 6 is that in this embodiment, the weight parts of 3,5-di-tert-butylsalicylic acid are 4 parts and the weight parts of lauric acid are 1 part.

[0054] Example 10

[0055] The only difference between this embodiment and Embodiment 9 is that in this embodiment, the weight parts of 3,5-di-tert-butylsalicylic acid are 8 parts and the weight parts of lauric acid are 2 parts.

[0056] Comparative Example 1

[0057] A method for preparing a ceramic-coated separator containing a solid electrolyte includes the following steps: mixing 30 parts by weight of alumina, 1 part by weight of perfluoroalkyl ethoxy ether alcohol and 100 parts by weight of dimethylformamide to obtain a ceramic coating slurry; coating the ceramic coating slurry onto the surface of a polyethylene membrane; and drying with hot air to obtain a ceramic-coated separator.

[0058] The polyethylene film has a thickness of 9 μm, and the ceramic coating has a thickness of 3 μm.

[0059] Comparative Example 2

[0060] A method for preparing a ceramic-coated separator containing a solid electrolyte includes the following steps: mixing 40 parts by weight of micron-sized lithium lanthanum zirconium oxide, 1 part by weight of perfluoroalkyl ethoxy ether alcohol and 100 parts by weight of dimethylformamide to obtain a ceramic coating slurry; coating the ceramic coating slurry onto the surface of a polyethylene membrane; and drying with hot air to obtain a ceramic-coated separator.

[0061] The polyethylene film has a thickness of 9 μm, and the ceramic coating has a thickness of 3 μm.

[0062] Experiment Example 1: Heat Resistance Test

[0063] The thermal shrinkage rate of the ceramic-coated separators prepared in Examples 1-2 and Comparative Example 2 was tested at 130℃ for 1 hour in accordance with GB / T 36363-2018 "Polyolefin separators for lithium-ion batteries". The test results are shown in Table 1 below.

[0064] Table 1 Results of heat resistance test

[0065]

[0066] As can be seen from the comparison between Example 1 and Comparative Example 2, the addition of ceramic powder can significantly increase the heat resistance of the ceramic coating membrane.

[0067] Experiment Example 2: Ion Conductivity Test

[0068] The ionic conductivity of the ceramic-coated separators prepared in Examples 1-10 and Comparative Example 1 was tested in accordance with GB / T 36363-2018 "Polyolefin separators for lithium-ion batteries". The results are expressed in mS / cm and retained to two decimal places. The test results are shown in Table 2 below.

[0069] Table 2 Ion conductivity performance test

[0070]

[0071] The comparison between Example 1 and Comparative Example 1 shows that the addition of solid electrolyte can significantly improve the ionic conductivity of ceramic coated membranes.

[0072] A comparison of Examples 2 and 3 shows that the addition of nanoscale solid electrolytes further improves the ionic conductivity of the ceramic-coated membrane.

[0073] A comparison of Examples 3-5 and Examples 6-9 shows that modifying the nanoscale solid electrolyte with 3,5-di-tert-butylsalicylic acid and lauric acid can further improve the ionic conductivity of the ceramic-coated membrane. A comparison of Examples 6-7 and Examples 8-9 shows that when the weight ratio of 3,5-di-tert-butylsalicylic acid to lauric acid is 1-4:1, the ionic conductivity of the ceramic-coated membrane can be further improved.

[0074] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A ceramic-coated separator comprising a solid-state electrolyte, characterized in that, The ceramic coating is coated on the surface of the base film. The raw material of the ceramic coating comprises the following components by weight: ceramic powder 30-50 parts, solid electrolyte 40-50 parts, and solvent 100-200 parts. The solid electrolyte is a modified nano solid electrolyte modified by a modifier. The modifier comprises 3,5-di-tert-butyl salicylic acid and lauric acid.

2. The ceramic-coated separator with solid-state electrolyte according to claim 1, wherein The ceramic powder comprises one or more of alumina, boehmite, silica, and magnesium oxide; and / or The solid electrolyte comprises one of a NASICON-type solid electrolyte and a garnet-type solid electrolyte.

3. The ceramic-coated separator with solid-state electrolyte of claim 1, wherein, The weight ratio of the 3,5-di-tert-butyl salicylic acid and lauric acid is 1-4:

1.

4. The ceramic-coated separator with solid-state electrolyte of claim 1, wherein, The modification comprises the following steps: dissolving the modifier in ethanol, adding nano solid electrolyte, uniformly dispersing, and drying to obtain the modified nano solid electrolyte.

5. The ceramic-coated separator with solid-state electrolyte of claim 4, wherein, The weight ratio of the modifier and nano solid electrolyte is 5-10:

100.

6. The ceramic-coated separator with solid-state electrolyte according to any one of claims 1 to 5, wherein The solvent comprises one of dimethylformamide, dimethylacetamide, and N-methyl pyrrolidone.

7. The ceramic-coated separator with solid-state electrolyte according to any one of claims 1 to 5, wherein The raw material of the ceramic coating further comprises 1-5 parts of a dispersant. The dispersant comprises one or more of fatty alcohol polyoxyethylene ether, sodium dodecyl benzene sulfonate, and perfluoroalkyl ethoxy ether alcohol.

8. The method of claim 1-7, wherein the ceramic coating separator comprising solid state electrolyte is prepared by the steps of: The method comprises the following steps: The raw material of the ceramic coating is uniformly mixed to obtain a ceramic coating slurry, the ceramic coating slurry is coated on the surface of the base film, and drying is performed to obtain a ceramic coating separator.

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