Oxide type solid electrolyte diaphragm as well as preparation method and application thereof

Abstract

The invention relates to a preparation method of an oxide type solid electrolyte diaphragm, which comprises the following steps: adding 10-60% by mass of oxide type solid electrolyte powder, 0.2-10% by mass of dispersing agent and zirconium oxide grinding beads into 30-80% by mass of deionized water by taking the total mass of oxide type solid electrolyte coating slurry as 100%, uniformly dispersing and grinding to obtain a mixed solution; sequentially adding 5%-20% by mass of a thickening agent and 3%-20% by mass of a binder into the mixed solution, and uniformly stirring to obtain premixed slurry; and adding 0.01-5% by mass of a wetting agent into the premixed slurry, stirring, defoaming, and filtering to obtain the oxide type solid electrolyte coating slurry, at least one surface of a base membrane is coated with the oxide type solid electrolyte coating slurry to form a coating, and the oxide type solid electrolyte diaphragm is formed after baking.

Description

Technical Field

[0001] The present application relates to the field of lithium battery technology, and in particular to an oxide-type solid electrolyte diaphragm and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries are used in various fields, including mobile communications, new energy vehicles, healthcare, and aerospace, due to their superior energy density, long cycle life, and no memory effect. However, traditional lithium-ion batteries use liquid electrolytes, and lithium dendrites can pierce the separator during use, causing a short circuit and posing a safety hazard. In addition, the separator, as a key component of lithium batteries, is used to physically isolate the negative electrode and the cathode to prevent battery short circuits while allowing the transmission of lithium ions. Commercial polyolefin-based separators have poor electrochemical performance due to their low porosity, poor mechanical strength, and poor thermal stability.

[0003] In order to solve these problems, most of the current research is to form a composite diaphragm by coating inorganic ceramic materials (such as SiO2, Al2O3, boehmite) or organic polymer materials (such as polyvinylidene fluoride, polyacrylate, etc.) on the surface of the diaphragm. Inorganic ceramic coatings have excellent thermal stability and chemical stability, but the ceramic material itself is brittle and easy to fall off when impacted by external forces. In addition, the uniformity of the coating thickness is difficult to control during the coating process, which will affect the performance consistency of the final battery. Compared with inorganic ceramic coatings, organic polymer coatings have good flexibility, but their thermal and chemical stability are poor. In addition, both inorganic ceramic materials and organic polymer materials do not have ionic conductivity themselves, which will increase the conductive resistance of lithium ions, resulting in a decrease in ionic conductivity and a slowdown in the migration rate of lithium ions, thereby affecting the charging and discharging efficiency and capacity of the battery. Summary of the invention

[0004] The present application provides an oxide-type solid electrolyte membrane and a preparation method and application thereof to solve the problems in the above-mentioned background technology.

[0005] In a first aspect, the present application provides a method for preparing an oxide-type solid electrolyte membrane, comprising: Based on the total mass of the oxide-type solid electrolyte coating slurry being 100%, 10%-60% by mass of oxide-type solid electrolyte powder, 0.2%-10% by mass of dispersant and zirconium oxide grinding beads are added into 30%-80% by mass of deionized water, dispersed and ground evenly to obtain a mixed solution; Add 5%-20% by weight of a thickener and 3%-20% by weight of a binder to the mixed solution in sequence and stir evenly to obtain a premixed slurry; Adding 0.01%-5% by mass of a wetting agent into the premixed slurry, stirring and defoaming, and filtering to obtain the oxide-type solid electrolyte coating slurry; The oxide-type solid electrolyte coating slurry is applied to at least one surface of a base film to form a coating, and then baked to form an oxide-type solid electrolyte separator.

[0006] Furthermore, the oxide-type solid electrolyte is one or more of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium phosphorus oxynitride, lithium zinc germanate, lithium lanthanum zirconium oxide, and lithium lanthanum zirconium titanium oxide, and the particle size of the oxide-type solid electrolyte is 100-700nm.

[0007] Furthermore, the dispersant is one or more of sodium polyacrylate, ammonium polyacrylate, ammonium acrylate copolymer salt, alkyl quaternary ammonium salt, and diaminodimethyl.

[0008] Furthermore, the thickener is one or more of carboxymethyl cellulose, sodium / lithium carboxymethyl cellulose, and methyl cellulose.

[0009] Furthermore, the binder is one or more of polyethylene glycol, styrene-butadiene rubber, styrene-propylene rubber, acrylic resin, acrylate copolymer, and acrylonitrile multi-polymer.

[0010] Furthermore, the wetting agent is one or more of acetylenic glycols, ethers, and polyvinyl alcohol.

[0011] Furthermore, the base film is any one of a polypropylene single-layer film, a polyethylene single-layer film, a polypropylene double-layer film, a polyethylene double-layer film, and a polypropylene / polyethylene double-layer film.

[0012] Furthermore, the coating method of the base film is at least one of gravure roller coating, dip coating, narrow coating, and spray coating, the coating thickness is 1-10 μm, the baking temperature is 30-80° C., and the baking time is 5-60 minutes.

[0013] In a second aspect, the present application provides an oxide-type solid electrolyte membrane, which is obtained based on the preparation method of the oxide-type solid electrolyte membrane as described above.

[0014] In a third aspect, the present application provides the use of the oxide-type solid electrolyte membrane as described above in the field of lithium batteries.

[0015] The above technical solution of the present application has the following advantages: The preparation method of the oxide-type solid electrolyte membrane provided in the first aspect of the present application is to form a coating by applying an oxide-type solid electrolyte coating slurry on at least one surface of a base film, and then baking to form an oxide-type solid electrolyte membrane. The oxide-type solid electrolyte has high ionic conductivity and a stable structural framework, which can provide a stable channel for the transmission of lithium ions and accelerate the transmission of lithium ions. In addition, the oxide-type solid electrolyte has good thermal stability and mechanical strength, which can effectively improve the thermal shrinkage performance and puncture resistance of the membrane at high temperatures, and improve the safety performance of the battery. The use of oxide-type solid electrolytes to prepare the membrane accelerates the ion conduction efficiency of the membrane and further improves the heat resistance and mechanical strength of the membrane.

[0016] It can be understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a scanning electron microscope image of Example 1 provided in this application. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0020] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0021] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0022] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0023] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also indicate the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as µg, mg, g, kg, etc.

[0024] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0025] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application but are not intended to limit the scope of the present application.

[0026] The present application provides a method for preparing an oxide-type solid electrolyte membrane, comprising: based on the total mass of the oxide-type solid electrolyte coating slurry being 100%, adding 10%-60% by mass of oxide-type solid electrolyte powder, 0.2%-10% by mass of dispersant and zirconium oxide grinding beads into 30%-80% by mass of deionized water, dispersing and grinding evenly to obtain a mixed solution; adding 5%-20% by mass of a thickener and 3%-20% by mass of a binder to the mixed solution in sequence and stirring evenly to obtain a premixed slurry; adding 0.01%-5% by mass of a wetting agent to the premixed slurry, stirring and defoaming, and filtering to obtain the oxide-type solid electrolyte coating slurry; applying the oxide-type solid electrolyte coating slurry on at least one surface of a base film to form a coating, and baking to form an oxide-type solid electrolyte membrane.

[0027] As a transition route from liquid batteries to solid-state batteries, semi-solid batteries retain the diaphragm and part of the liquid electrolyte, and introduce solid electrolyte components at the same time. As a new type of solid ion conductive material, oxide-type solid electrolyte has high ionic conductivity and lithium ion migration number, can quickly conduct lithium ions, effectively reduce the polarization phenomenon inside the battery, thereby improving the battery's charge and discharge efficiency and cycle performance. In addition, solid electrolytes instead of liquid electrolytes can prevent the problem of lithium dendrites piercing the diaphragm during growth and causing battery short circuits, thereby improving battery safety.

[0028] Therefore, the purpose of this application is to utilize the excellent ion conduction properties of oxide-type solid electrolytes, significantly reduce the resistance to lithium ion migration, improve the ion conduction efficiency of the diaphragm, and further improve the poor mechanical strength and thermal stability as well as uneven coating and missing coating in the coating process.

[0029] In some embodiments, the oxide-type solid electrolyte is one or more of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium phosphorus oxynitride, lithium zinc germanate, lithium lanthanum zirconium oxide, and lithium lanthanum zirconium titanium oxide, and the particle size of the oxide-type solid electrolyte is 100-700nm.

[0030] In some embodiments, the dispersant is one or more of sodium polyacrylate, ammonium polyacrylate, ammonium acrylate copolymer, alkyl quaternary ammonium salt, and diaminodimethyl.

[0031] In some embodiments, the thickener is one or more of carboxymethyl cellulose, sodium / lithium carboxymethyl cellulose, and methyl cellulose.

[0032] In some embodiments, the binder is one or more of polyethylene glycol, styrene-butadiene rubber, styrene-propylene rubber, acrylic resin, acrylate copolymer, and acrylonitrile multipolymer.

[0033] In some embodiments, the wetting agent is one or more of acetylenic glycols, ethers, and polyvinyl alcohol.

[0034] In some embodiments, the base film is any one of a polypropylene single-layer film, a polyethylene single-layer film, a polypropylene double-layer film, a polyethylene double-layer film, and a polypropylene / polyethylene double-layer film.

[0035] In some embodiments, the base film is coated by at least one of gravure roller coating, dip coating, narrow coating, and spray coating, the coating thickness is 1-10 μm, the baking temperature is 30-80° C., and the baking time is 5-60 minutes.

[0036] The preparation method of the oxide-type solid electrolyte membrane provided in the present application is carried out according to the following steps: 1) Adding oxide solid electrolyte powder, dispersant and zirconium oxide grinding beads into deionized water, dispersing them evenly and grinding them to obtain a mixed solution; wherein the oxide solid electrolyte includes at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium phosphorus oxynitride, lithium zinc germanate, lithium lanthanum zirconium oxide, and lithium lanthanum zirconium titanium oxide, with a particle size of 100-700nm and a mass percentage of 10%-60%; the dispersant includes at least one of sodium polyacrylate, ammonium polyacrylate, ammonium acrylate copolymer, alkyl quaternary ammonium salt, and diaminodimethyl, with a mass percentage of 0.2%-10%; and the mass percentage of deionized water is 30%-80%.

[0037] 2) Adding a thickener and a binder to the mixed solution in sequence, stirring the mixture evenly, and obtaining a premixed slurry; wherein the thickener comprises at least one of carboxymethyl cellulose, sodium / lithium carboxymethyl cellulose, and methyl cellulose, with a mass percentage of 5%-20%; and the binder comprises at least one of polyethylene glycol, styrene-butadiene rubber, styrene-propylene rubber, acrylic resin, acrylic ester copolymer, and acrylonitrile multipolymer, with a mass percentage of 3%-20%.

[0038] 3) adding a wetting agent to the premixed slurry obtained in step 2), slowly stirring and defoaming, and filtering to obtain an oxide-type solid electrolyte coating slurry; wherein the wetting agent includes at least one of acetylenic glycols, ethers, and polyvinyl alcohol, with a mass percentage of 0.01%-5%.

[0039] 4) Applying the oxide-type solid electrolyte coating slurry on at least one surface of the base film to form a coating, and baking to form an oxide-type solid electrolyte coating diaphragm. The diaphragm substrate includes any one of a polypropylene single-layer film, a polyethylene single-layer film, a polypropylene double-layer film, a polyethylene double-layer film, and a polypropylene / polyethylene double-layer film; the diaphragm coating method includes at least one of gravure roller coating, dip coating, narrow coating or spray coating; the diaphragm baking temperature is 30-80°C, the baking time is 5-60 minutes; the coating thickness is 1-10μm.

[0040] In order to further understand the present application, the present application is described in detail below in conjunction with specific implementation methods. Example 1

[0041] The preparation method of the lithium titanium aluminum phosphate coating diaphragm of this embodiment is carried out according to the following steps. Taking the total mass of the coating slurry as 100%, 24.13% of lithium titanium aluminum phosphate powder with a particle size of 300nm, 0.36% of dispersant and an appropriate amount of zirconium oxide grinding beads are added to 63.51% deionized water, and the mixture is evenly dispersed and ground. Then, 7.95% of thickener and 4.0% of binder are added, and after being fully stirred, 0.05% of wetting agent is added, and the mixture is slowly stirred and defoamed, and the lithium titanium aluminum phosphate coating slurry is obtained after filtration. Finally, the obtained lithium titanium aluminum phosphate coating slurry is applied to one surface of a 12μm polypropylene base film by roller coating to form a 3μm coating, and then baked in an oven at 60°C for 10min to obtain a lithium titanium aluminum phosphate coating diaphragm. Example 2

[0042] The preparation method of the lithium titanium aluminum phosphate coating diaphragm of this embodiment is carried out according to the following steps. Taking the total mass of the coating slurry as 100%, 24.13% of lithium titanium aluminum phosphate powder with a particle size of 500nm, 0.36% of dispersant and an appropriate amount of zirconium oxide grinding beads are added to 63.51% deionized water, and the mixture is evenly dispersed and ground. Then, 7.95% of thickener and 4.0% of binder are added, and after being fully stirred, 0.05% of wetting agent is added, and the mixture is slowly stirred and defoamed. After filtering, the lithium titanium aluminum phosphate coating slurry is obtained. Finally, the obtained lithium titanium aluminum phosphate coating slurry is applied to one surface of a 12μm polypropylene base film by roller coating to form a 3μm coating, and then baked in an oven at 60°C for 10min to obtain a lithium titanium aluminum phosphate coating diaphragm. Example 3

[0043] The preparation method of the lithium germanium aluminum phosphate coating diaphragm of this embodiment is carried out according to the following steps. Taking the total mass of the coating slurry as 100%, 24.13% of lithium germanium aluminum phosphate powder with a particle size of 300nm, 0.36% of dispersant and an appropriate amount of zirconium oxide grinding beads are added to 63.51% deionized water, and the mixture is evenly dispersed and ground. Then, 7.95% of thickener and 4.0% of binder are added, and after fully stirring, 0.05% of wetting agent is added, and the mixture is slowly stirred and defoamed. After filtering, the lithium germanium aluminum phosphate coating slurry is obtained. Finally, the obtained lithium germanium aluminum phosphate coating slurry is applied to one surface of a 12μm polypropylene base film by roller coating to form a 3μm coating, and then baked in an oven at 60°C for 10min to obtain a lithium germanium aluminum phosphate coating diaphragm. Comparative Example

[0044] The difference between this comparative example and Example 1 is that the lithium titanium aluminum phosphate solid electrolyte is replaced by aluminum oxide, and the rest is the same as Example 1.

[0045] By testing the performance of the diaphragms prepared in Examples 1 to 3 and the comparative examples, the thickness, air permeability, puncture strength, thermal shrinkage and other properties of the diaphragms were determined. At least 10 data results were tested for each test, and the average value of the 10 data was used as the final test result for comparison. The thermal shrinkage performance of the products of Examples 1-3 at 130°C is significantly better than that of the comparative example, indicating that the products obtained in this application have better high temperature resistance and bring better safety performance to the battery. Compared with the base film and the comparative example, the puncture strength of the products of Examples 1-3 is significantly improved, indicating that the diaphragm products obtained in this application have good flexibility and elasticity, and can withstand certain deformation and stress. The air permeability increment of the products of Examples 1-3 is significantly smaller than that of the comparative example, indicating that the diaphragm products obtained in this application have good anti-blocking performance, which can effectively reduce the internal resistance of the battery and improve the ionic conductivity.

[0047] like Figure 1 As shown, the coating membrane prepared in Example 1 is microscopically scanned. From the SEM image, it can be seen that the coating is composed of nano-scale lithium aluminum titanium phosphate particles that are tightly packed, and there are certain pores between the particles. These pores are conducive to the penetration of electrolyte and the transmission of lithium ions, thereby improving the charge and discharge performance of the battery. In addition, the membrane prepared by this process has a more uniform coating thickness, no obvious interface defects, improves the large-area leakage phenomenon during the coating process, and is conducive to further processing.

[0048] Solid electrolytes, also known as fast ion conductors or super ion conductors, are widely used in electric vehicles and portable electronic devices because of their higher energy density, better safety and longer cycle life. Oxide-based solid electrolytes have high ionic conductivity (>10 at room temperature). -4 S / cm) and a stable structural framework can provide a stable channel for the transmission of lithium ions and accelerate the transmission of lithium ions. In addition, the oxide-type solid electrolyte has good thermal stability and mechanical strength, which can effectively improve the thermal shrinkage and puncture resistance of the diaphragm at high temperatures and improve the safety performance of the battery. The present application uses an oxide-type solid electrolyte to prepare a solid electrolyte coating diaphragm, which accelerates the ion conduction efficiency of the diaphragm and further improves the heat resistance and mechanical strength of the diaphragm.

[0049] The present application also provides an oxide-type solid electrolyte membrane, which is obtained based on the preparation method of the oxide-type solid electrolyte membrane as described above.

[0050] The present application also provides the use of the oxide-type solid electrolyte membrane as described above in the field of lithium batteries.

[0051] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present application is not limited to the specific methods described above and shown in the figures. In addition, for the sake of brevity, detailed descriptions of known methods and technologies are omitted here.

[0052] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for preparing an oxide-type solid electrolyte membrane, characterized in that: include: Based on the total mass of the oxide-type solid electrolyte coating slurry being 100%, 10%-60% by mass of oxide-type solid electrolyte powder, 0.2%-10% by mass of dispersant and zirconium oxide grinding beads are added into 30%-80% by mass of deionized water, dispersed and ground evenly to obtain a mixed solution; Add 5%-20% by weight of a thickener and 3%-20% by weight of a binder to the mixed solution in sequence and stir evenly to obtain a premixed slurry; Adding 0.01%-5% by mass of a wetting agent into the premixed slurry, stirring and defoaming, and filtering to obtain the oxide-type solid electrolyte coating slurry; The oxide-type solid electrolyte coating slurry is applied to at least one surface of a base film to form a coating, and then baked to form an oxide-type solid electrolyte separator.

2. The method for preparing an oxide-type solid electrolyte membrane according to claim 1, characterized in that: The oxide-type solid electrolyte is one or more of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium phosphorus oxynitride, lithium zinc germanate, lithium lanthanum zirconium oxide, and lithium lanthanum zirconium titanium oxide. The particle size of the oxide-type solid electrolyte is 100-700 nm.

3. The method for preparing an oxide-type solid electrolyte membrane according to claim 1, characterized in that: The dispersant is one or more of sodium polyacrylate, ammonium polyacrylate, ammonium acrylate copolymer salt, alkyl quaternary ammonium salt, and diaminodimethyl.

4. The method for preparing an oxide-type solid electrolyte membrane according to claim 1, characterized in that: The thickener is one or more of carboxymethyl cellulose, sodium / lithium carboxymethyl cellulose, and methyl cellulose.

5. The method for preparing an oxide-type solid electrolyte membrane according to claim 1, characterized in that: The binder is one or more of polyethylene glycol, styrene-butadiene rubber, styrene-propylene rubber, acrylic resin, acrylic ester copolymer, and acrylonitrile multi-polymer.

6. The method for preparing an oxide-type solid electrolyte membrane according to claim 1, characterized in that: The wetting agent is one or more of acetylenic glycols, ethers and polyvinyl alcohol.

7. The method for preparing an oxide-type solid electrolyte membrane according to claim 1, characterized in that: The base film is any one of a polypropylene single-layer film, a polyethylene single-layer film, a polypropylene double-layer film, a polyethylene double-layer film, and a polypropylene / polyethylene double-layer film.

8. The method for preparing an oxide-type solid electrolyte membrane according to claim 1, characterized in that: The coating method of the base film is at least one of gravure roller coating, dip coating, narrow coating and spray coating, the coating thickness is 1-10 μm, the baking temperature is 30-80° C., and the baking time is 5-60 minutes.

9. An oxide-type solid electrolyte membrane, characterized in that: The method for preparing the oxide-type solid electrolyte membrane is based on any one of claims 1 to 8.

10. Use of the oxide-type solid electrolyte membrane according to claim 9 in the field of lithium batteries.

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