Ceramic coating diaphragm containing solid electrolyte and preparation method thereof

Abstract

The invention relates to the technical field of lithium ion battery diaphragms, and provides a solid electrolyte-containing ceramic coating diaphragm and a preparation method thereof, the ceramic coating diaphragm comprises a base membrane and a ceramic coating arranged on the surface of the base membrane; the ceramic coating is prepared from the following raw materials in parts by weight: 30 to 50 parts of ceramic powder, 40 to 50 parts of solid electrolyte and 100 to 200 parts of solvent. According to the technical scheme, the problems of poor heat resistance and ionic conductivity of the lithium ion battery diaphragm in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion battery diaphragms, and in particular to a ceramic coating diaphragm containing a solid electrolyte and a preparation method thereof. Background Art

[0002] As lithium-ion battery technology develops rapidly, the market's requirements for battery performance continue to rise. As one of the key components of the battery, the performance of the separator, especially its heat resistance and ion conductivity, is directly related to the safety, cycle life and energy density of the battery.

[0003] Traditional lithium-ion battery separators are mostly made of polyethylene or polypropylene. Such separators have poor heat resistance and high heat shrinkage, which can easily cause internal short circuits in lithium-ion batteries and make it difficult to play a protective role in applications. In addition, traditional liquid electrolyte separators face problems such as difficult processing and limited ion conductivity during application. In view of this, in order to meet market demand, it is urgent to develop a lithium-ion battery separator with both excellent heat resistance and ion conductivity. Summary of the invention

[0004] The present invention provides a ceramic coating diaphragm containing a solid electrolyte and a preparation method thereof, which solves the problem of poor heat resistance and ion conductivity of lithium ion battery diaphragms in the related art.

[0005] The technical solution of the present invention is as follows: The present invention provides a ceramic coating diaphragm containing a solid electrolyte, comprising a base film and a ceramic coating arranged on the surface of the base film; The raw materials of the ceramic coating include 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.

[0006] As a further technical solution, the base film is a polyolefin film, preferably a polyethylene film.

[0007] As a further technical solution, the thickness of the base film is 8-10 μm, preferably 9 μm.

[0008] As a further technical solution, the thickness of the ceramic coating is 2-4 μm, preferably 3 μm.

[0009] As a further technical solution, the ceramic powder includes one or more of alumina, boehmite, silica, and magnesium oxide.

[0010] In the present invention, the type of ceramic powder can be freely selected according to the actual usage scenario. For example, alumina ceramic powder can be selected for power equipment such as electric vehicles; boehmite ceramic powder can be selected for electronic products that are more sensitive to battery weight, such as laptops, smart phones, etc.; silica ceramic powder can be selected for products that require fast charging and discharging.

[0011] As a further technical solution, the solid electrolyte includes one of a NASICON-type solid electrolyte and a garnet-type solid electrolyte; the NASICON-type solid electrolyte is preferably lithium titanium aluminum phosphate; and the garnet-type solid electrolyte is preferably lithium lanthanum zirconium oxide.

[0012] As a further technical solution, the median particle size of the ceramic powder is 1-1.5 μm.

[0013] As a further technical solution, the solid electrolyte is a nanoscale solid electrolyte.

[0014] In the present invention, by adding nano-scale solid electrolyte and utilizing the strong adsorption property of nanoparticles, the problem of poor interface contact of solid electrolyte is improved, and the ion conductivity of the ceramic coating diaphragm is further improved.

[0015] As a further technical solution, the median particle size of the nanoscale solid electrolyte is 100-200 nm.

[0016] As a further technical solution, the nanoscale solid electrolyte is a modified nanoscale solid electrolyte modified by a modifier; The modifiers include 3,5-di-tert-butylsalicylic acid and lauric acid.

[0017] In the present invention, although the addition of nano-scale solid electrolytes can further improve the ionic conductivity of the ceramic coating membrane, the nano-scale solid electrolytes are easy to agglomerate, resulting in limited effect on further improving the ionic conductivity. The inventors found that the ionic conductivity of the ceramic coating membrane can be further improved by modifying the nano-scale solid electrolytes with 3,5-di-tert-butylsalicylic acid and lauric acid. It is speculated that 3,5-di-tert-butylsalicylic acid and lauric acid can synergistically improve the steric hindrance of the nano-scale solid electrolytes and reduce their agglomeration tendency, thereby further improving the ionic conductivity of the ceramic coating membrane.

[0018] As a further technical solution, the weight ratio of the 3,5-di-tert-butylsalicylic acid to lauric acid is 1-4:1.

[0019] In the present invention, when the weight ratio of 3,5-di-tert-butylsalicylic acid to lauric acid is 1-4:1, the ionic conductivity of the ceramic coating membrane can be further improved.

[0020] As a further technical solution, the modification includes the following steps: dissolving the modifier in ethanol, adding the nano-scale solid electrolyte, dispersing evenly, and drying to obtain a modified nano-scale solid electrolyte.

[0021] As a further technical solution, the weight ratio of the modifier to the nanoscale solid electrolyte is 5 to 10:100.

[0022] As a further technical solution, the solvent includes one of dimethylformamide, dimethylacetamide and N-methylpyrrolidone.

[0023] As a further technical solution, the raw material of the ceramic coating further includes 1 to 5 parts of a dispersant; The dispersant includes one or more of fatty alcohol polyoxyethylene ether, sodium dodecylbenzene sulfonate, and perfluoroalkyl ethoxy ether alcohol.

[0024] In the present invention, the addition of the dispersant helps to improve the mixing effect of the ceramic coating raw materials, thereby ensuring the uniformity of the ceramic coating and further improving the overall performance of the ceramic coating diaphragm.

[0025] The present invention also proposes a method for preparing a ceramic coating diaphragm containing a solid electrolyte, comprising the following steps: mixing the raw materials of the ceramic coating evenly to obtain a ceramic coating slurry, applying the ceramic coating slurry on the surface of a base film, and drying to obtain a ceramic coating diaphragm.

[0026] The working principle and beneficial effects of the present invention are: In the present invention, the raw materials of the ceramic coating include ceramic powder and solid electrolyte. By using the two together, the ceramic coating diaphragm can not only have the excellent heat resistance of the ceramic material, but also have the high ion conductivity of the solid electrolyte, thereby improving the safety, stability and adaptability of the lithium-ion battery to extreme environments, thereby broadening the application range of the lithium-ion battery. In addition, the raw materials of the ceramic coating are simple and easy to obtain, and large-scale production can be achieved. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In the following examples and comparative examples, unless otherwise specified, the median particle size of alumina and boehmite is 1 μm; the molecular formula of micron-sized lithium aluminum titanium phosphate is Li 1.3 Al 0.3 Ti l.7P3O 12 , the median particle size is 1 μm; the molecular formula of nano-scale lithium aluminum titanium phosphate is Li 1.3 Al 0.3 Ti l.7 P3O 12 , with a median particle size of 200nm; the molecular formula of micron-sized lithium lanthanum zirconium oxide is Li7La3Zr2O 12 , the median particle size is 1 μm; the model of perfluoroalkyl ethoxy ether alcohol is S201.

[0029] Example 1 A method for preparing a ceramic coating diaphragm containing a solid electrolyte comprises the following steps: according to weight parts, 30 parts of aluminum oxide, 40 parts of micron-sized lithium lanthanum zirconium oxide, 1 part of perfluoroalkyl ethoxy ether alcohol and 100 parts of dimethylformamide are mixed evenly to obtain a ceramic coating slurry, the ceramic coating slurry is coated on the surface of a polyethylene film, and hot air drying is performed to obtain a ceramic coating diaphragm; The thickness of the polyethylene film is 9 μm, and the thickness of the ceramic coating is 3 μm.

[0030] Example 2 A method for preparing a ceramic coating diaphragm containing a solid electrolyte comprises the following steps: mixing 50 parts of boehmite, 50 parts of micron-sized lithium aluminum titanium phosphate, 5 parts of perfluoroalkyl ethoxy ether alcohol and 200 parts of dimethylformamide in parts by weight to obtain a ceramic coating slurry, applying the ceramic coating slurry on the surface of a polyethylene film, and drying with hot air to obtain a ceramic coating diaphragm; The thickness of the polyethylene film is 9 μm, and the thickness of the ceramic coating is 3 μm.

[0031] Example 3 The only difference between this embodiment and embodiment 2 is that, in this embodiment, the micron-sized lithium aluminum titanium phosphate is replaced by an equal amount of nano-sized lithium aluminum titanium phosphate.

[0032] Example 4 The only difference between this embodiment and embodiment 3 is that in this embodiment, the nano-scale lithium aluminum titanium phosphate is modified nano-scale lithium aluminum titanium phosphate, and the modification method includes the following steps: dissolving 5 parts of 3,5-di-tert-butyl salicylic acid in 150 parts of ethanol, adding 100 parts of nano-scale solid electrolyte, dispersing evenly, and drying to obtain modified nano-scale lithium aluminum titanium phosphate.

[0033] Example 5 The only difference between this embodiment and embodiment 4 is that, in this embodiment, 3,5-di-tert-butylsalicylic acid is replaced by an equal amount of lauric acid.

[0034] Example 6 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 by 1 part of 3,5-di-tert-butylsalicylic acid and 4 parts of lauric acid.

[0035] Example 7 The only difference between this embodiment and embodiment 6 is that, in this embodiment, the weight portion of 3,5-di-tert-butylsalicylic acid is 4.5 parts, and the weight portion of lauric acid is 0.5 parts.

[0036] Example 8 The only difference between this embodiment and embodiment 6 is that, in this embodiment, the weight portion of 3,5-di-tert-butylsalicylic acid is 2.5 parts, and the weight portion of lauric acid is 2.5 parts.

[0037] Example 9 The only difference between this embodiment and embodiment 6 is that, in this embodiment, the weight portion of 3,5-di-tert-butylsalicylic acid is 4 parts, and the weight portion of lauric acid is 1 part.

[0038] Example 10 The only difference between this embodiment and embodiment 9 is that, in this embodiment, the weight parts of 3,5-di-tert-butylsalicylic acid is 8 parts, and the weight parts of lauric acid is 2 parts.

[0039] Comparative Example 1 A method for preparing a ceramic coating diaphragm containing a solid electrolyte comprises the following steps: uniformly mixing 30 parts of aluminum oxide, 1 part of perfluoroalkyl ethoxy ether alcohol and 100 parts of dimethylformamide by weight to obtain a ceramic coating slurry, coating the ceramic coating slurry on the surface of a polyethylene film, and drying with hot air to obtain a ceramic coating diaphragm; The thickness of the polyethylene film is 9 μm, and the thickness of the ceramic coating is 3 μm.

[0040] Comparative Example 2 A method for preparing a ceramic coating diaphragm containing a solid electrolyte comprises the following steps: mixing 40 parts by weight of micron-sized lithium lanthanum zirconium oxide, 1 part of perfluoroalkyl ethoxy ether alcohol and 100 parts of dimethylformamide to obtain a ceramic coating slurry, applying the ceramic coating slurry on the surface of a polyethylene film, and drying with hot air to obtain a ceramic coating diaphragm; The thickness of the polyethylene film is 9 μm, and the thickness of the ceramic coating is 3 μm.

[0041] Experimental Example 1 Heat Resistance Test The thermal shrinkage of the ceramic coating separators prepared in Examples 1 to 2 and Comparative Example 2 at 130° C. and 1 h was tested with reference to GB / T 36363-2018 “Polyolefin separators for lithium-ion batteries”. The test results are shown in Table 1 below.

[0042] Table 1 Heat resistance test results

[0043] From the comparison between Example 1 and Comparative Example 2, it can be seen that the addition of ceramic powder can significantly increase the heat resistance of the ceramic coating diaphragm.

[0044] Experimental Example 2 Ion conductivity performance test The ionic conductivity of the ceramic coating membranes prepared in Examples 1 to 10 and Comparative Example 1 was tested with reference to GB / T 36363-2018 "Polyolefin separators for lithium ion batteries". The results were expressed in mS / cm with two decimal places retained. The test results are shown in Table 2 below.

[0045] Table 2 Ion conductivity performance test

[0046] Comparison between Example 1 and Comparative Example 1 shows that the addition of solid electrolyte can significantly improve the ionic conductivity of the ceramic coating diaphragm.

[0047] Comparison between Example 2 and Example 3 shows that the ionic conductivity of the ceramic coating diaphragm is further improved by adding nano-scale solid electrolyte.

[0048] Comparison between Examples 3 to 5 and Examples 6 to 9 shows that the ionic conductivity of the ceramic coating membrane can be further improved by modifying the nano-scale solid electrolyte with 3,5-di-tert-butylsalicylic acid and lauric acid. Comparison between Examples 6 to 7 and Examples 8 to 9 shows that 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 coating membrane can be further improved.

[0049] The above are only 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 in the protection scope of the present invention.

Claims

1. A ceramic coating diaphragm containing a solid electrolyte, characterized in that: It includes a base film and a ceramic coating disposed on the surface of the base film; The raw materials of the ceramic coating include 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.

2. A ceramic coating diaphragm containing a solid electrolyte according to claim 1, characterized in that: The ceramic powder includes one or more of alumina, boehmite, silica, and magnesium oxide; and / or The solid electrolyte includes one of a NASICON solid electrolyte and a garnet solid electrolyte.

3. A ceramic coating diaphragm containing a solid electrolyte according to claim 1, characterized in that: The solid electrolyte is a nanoscale solid electrolyte.

4. A ceramic coating diaphragm containing a solid electrolyte according to claim 3, characterized in that: The nanoscale solid electrolyte is a modified nanoscale solid electrolyte modified by a modifier; The modifiers include 3,5-di-tert-butylsalicylic acid and lauric acid.

5. A ceramic coating diaphragm containing a solid electrolyte according to claim 4, characterized in that: The weight ratio of the 3,5-di-tert-butylsalicylic acid to lauric acid is 1-4:

1.

6. A ceramic coating diaphragm containing a solid electrolyte according to claim 4, characterized in that: The modification comprises the following steps: dissolving a modifier in ethanol, adding a nano-scale solid electrolyte, dispersing the nano-scale solid electrolyte evenly, and drying the nano-scale solid electrolyte to obtain a modified nano-scale solid electrolyte.

7. A ceramic coating diaphragm containing a solid electrolyte according to claim 6, characterized in that: The weight ratio of the modifier to the nanoscale solid electrolyte is 5 to 10:

100.

8. A ceramic coating diaphragm containing a solid electrolyte according to any one of claims 1 to 7, characterized in that: The solvent includes one of dimethylformamide, dimethylacetamide and N-methylpyrrolidone.

9. A ceramic coating diaphragm containing a solid electrolyte according to any one of claims 1 to 7, characterized in that: The raw materials of the ceramic coating also include 1 to 5 parts of a dispersant; The dispersant includes one or more of fatty alcohol polyoxyethylene ether, sodium dodecylbenzene sulfonate, and perfluoroalkyl ethoxy ether alcohol.

10. The method for preparing a ceramic coating diaphragm containing a solid electrolyte according to any one of claims 1 to 9, characterized in that: The following steps are involved: The raw materials of the ceramic coating are mixed evenly to obtain a ceramic coating slurry, and the ceramic coating slurry is coated on the surface of the base film and dried to obtain a ceramic coating diaphragm.

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