A modified coating separator for lithium batteries and a method for preparing the same

Abstract

The application provides a lithium battery modified coating diaphragm and a preparation method thereof, and relates to the technical field of diaphragms.The lithium battery modified coating diaphragm comprises the following components: 10-15 parts of SiO2;30-50 parts of Al2O3;2-7 parts of a solvent;and 3-9 parts of an additive.The inside of the silicon dioxide is hollow, the semi-paste mixture formed by mixing and stirring Al2O3, the solvent and the additive is added to the inside of the silicon dioxide, and then shearing is performed, so that the semi-paste mixture formed by mixing and stirring Al2O3, the solvent and the additive is wrapped outside, the middle is the hollow mesoporous silicon dioxide, the inside is the semi-paste mixture formed by mixing and stirring Al2O3, the solvent and the additive, and a sandwich cookie shape is formed, the stability of the outside and the inside is maintained, and the lithium battery modified coating diaphragm with good ion conductivity and easy regulation is formed.

Description

Technical Field

[0001] This invention relates to the field of separator technology, and in particular to a modified coating separator for lithium batteries and its preparation method. Background Technology

[0002] Ultrafine alumina is currently the most widely used inorganic powder in the modification of lithium-ion battery separators. The method for modifying lithium-ion battery separators with alumina typically involves coating alumina particles onto the surface of a polyolefin separator with the assistance of a polymer binder to improve the separator's thermal stability, mechanical strength, and wettability. As a ceramic coating for lithium-ion battery separators, it offers the following advantages:

[0003] Alumina coatings have high temperature resistance, maintaining the integrity of the separator at 180℃; they can neutralize free HF in the electrolyte, improving the battery's acid resistance and safety performance; they can increase the micropore tortuosity, resulting in lower self-discharge than ordinary separators; nano-alumina can form a solid solution in lithium batteries, improving rate performance and cycle performance; it has good wettability and a certain ability to absorb and retain liquid, but its properties are not easy to control.

[0004] Silica (SiO2) is a common thermally stable inorganic powder filler, widely used in polymer filling and modification. Due to its large specific surface area and ease of generating a large number of silanol groups (Si—OH), it improves the hydrophilicity of the separator while enhancing its electrolyte wettability, thereby improving lithium-ion transport performance and enhancing the battery's electrochemical performance. Simultaneously, SiO2 particles can act as an inorganic material to strengthen the mechanical strength of the separator, preventing the continued growth and puncture of lithium dendrites in the negative electrode, thus avoiding thermal short circuits in the battery. Compared to Al2O3, AlOOH, and TiO2, the microstructure of SiO2 is easier to control. SiO2 nanospheres, SiO2 submicron spheres, and SiO2 nano-coatings are readily obtained and realized. However, silica suffers from insufficient ion conductivity and a tendency to agglomerate in organic solvents.

[0005] There is a current need for a modified coating separator for lithium batteries that is easy to control and has good ion conduction properties. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies, such as good controllability but insufficient ionicity, and good conductivity of ions but difficulty in regulation.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a lithium battery modified coating separator, comprising the following components:

[0008] SiO2: 10-15 parts; Al2O3: 30-50 parts; Solvent: 2-7 parts; Additives: 3-9 parts.

[0009] In a preferred embodiment, the solvent comprises the following components:

[0010] Deionized water: 6-8 parts; acetic acid: 7-9 parts; nano metal powder: 1-3 parts; ceramic particles: 2-4 parts.

[0011] In a preferred embodiment, the additive comprises the following components:

[0012] Thickener: 1-1.5 parts; binder: 1-1.5 parts; dispersant: 1-1.5 parts.

[0013] A method for preparing a modified coating separator for lithium batteries includes the following steps:

[0014] 1) Prepare the solvent and store it at room temperature for later use;

[0015] 2) Prepare the additive and store it at room temperature for later use;

[0016] 3) Preparation of Al2O3 powder;

[0017] 4) Mix Al2O3 with solvent and additives to obtain a mixture;

[0018] 5) Prepare SiO2 nanospheres and use them to encapsulate the mixture obtained in step 4;

[0019] 6) Drying and packaging.

[0020] By adopting the above technical solution, a modified coating separator for lithium batteries that is easy to control and has good ion conduction properties is manufactured.

[0021] In a preferred embodiment, the solution preparation includes the following steps:

[0022] 1.1) Add deionized water and acetic acid to a stirring device and stir. Use a commonly used laboratory stirring device. Stir at a speed of 3215 r / min and at a pressure of standard atmosphere for 20 min.

[0023] 1.2) After mixing in step 1.1), turn on the stirring device, add the nano metal powder and ceramic particles into the stirring device, and stir at a speed of 1680 r / min. The stirring pressure is two standard atmospheres, until a uniform paste is formed.

[0024] By adopting the above technical solution, a solution can be prepared in which deionized water, acetic acid, nano-metal powder, and ceramic particles are mixed to form a base liquid, which can achieve good conductivity.

[0025] In a preferred embodiment, the preparation of the additive includes the following steps:

[0026] Thickener, binder and dispersant are added to a stirring device and stirred at a speed of 1200 r / min and a stirring pressure of standard atmospheric pressure until a uniform paste is formed.

[0027] By adopting the above technical solution, the solutions can be bonded together, ensuring the stability of the base liquid.

[0028] In a preferred embodiment, the preparation of Al2O3 powder includes the following steps:

[0029] 3.1) Calcination precursors, the precursors include: gibbsite, boehmite, boehmite, ammonium aluminum carbonate and ammonium aluminum sulfate;

[0030] 3.2) Ultrafine powder can be obtained by calcining the precursor and then wet grinding, drying and pulverizing and classifying it.

[0031] By adopting the above technical solution, Al2O3 powder can be obtained simply and effectively and kept for later use.

[0032] In a preferred embodiment, the mixing and stirring of Al2O3 with solvent and additives includes the following steps:

[0033] 4.1) Add the ultrafine powder obtained in step S4 into the stirring device, and at the same time add the solvent and additives into the stirring device;

[0034] 4.2) Heat the stirring device in a water bath to a temperature of 60-80 degrees Celsius. Use the stirring device at a speed of 1200 r / min for 15 minutes, and then cool it to room temperature.

[0035] 4.3) After cooling to room temperature, stir at a stirring speed of 3600 r / min until it becomes a semi-paste.

[0036] By adopting the above technical solution, the solvent formed by Al2O3 can effectively protect the SiO2 nanospheres both inside and outside, maintain the properties of Al2O3, and allow it to penetrate well into the SiO2 nanospheres.

[0037] In a preferred embodiment, the preparation of SiO2 nanospheres, which involves encapsulating the mixture obtained in step 4 with SiO2 nanospheres, includes the following steps:

[0038] 5.1) Add ammonia to the polyacrylic acid aqueous solution, stir evenly, add anhydrous ethanol, stir at room temperature for 1 hour, add tetraethyl orthosilicate dropwise, continue to stir at room temperature in a sealed container for 12 hours, centrifuge and wash the resulting solution, and dry it in an oven at 50°C to obtain hollow mesoporous silica.

[0039] 5.2) Add deionized water to the semi-paste mixture formed by mixing Al2O3 with solvent and additives to form a solution.

[0040] 5.3) Stir the hollow mesoporous silica and the solution to allow the solution to enter the hollow mesoporous silica, forming a saturated silica solution;

[0041] 5.4) Add the saturated silica solution to the high-speed shear disperser for nano-GTO dispersion and shear it.

[0042] By adopting the above technical solution: the interior of the silica is made into a hollow shape, and a semi-paste mixture formed by mixing Al2O3 with solvents and additives is added into the interior of the silica. Then, it is sheared to form an outer layer of the semi-paste mixture formed by mixing Al2O3 with solvents and additives, with hollow mesoporous silica in the middle and the semi-paste mixture formed by mixing Al2O3 with solvents and additives inside, forming a sandwich shape, thus maintaining the stability of its exterior and interior.

[0043] In a preferred embodiment, the drying and packaging process includes the following steps:

[0044] 6.1) Dry the product obtained in step S5) and allow it to cool naturally to room temperature;

[0045] 6.2) Then use a packaging machine to package it.

[0046] By adopting the above technical solution:

[0047] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0048] In this invention, the interior of silica is made hollow. A semi-paste mixture formed by mixing Al2O3 with solvents and additives is added to the interior of silica. Then, it is sheared to form an outer layer of the semi-paste mixture formed by mixing Al2O3 with solvents and additives, with hollow mesoporous silica in the middle and the semi-paste mixture formed by mixing Al2O3 with solvents and additives inside, forming a sandwich shape. This maintains the stability of both the exterior and interior, forming a lithium battery modified coating membrane that is easy to control and has good ion conductivity. Alumina improves rate performance and cycle performance, has good wettability, and has a certain liquid absorption and retention capacity. The microstructure of SiO2 is easier to control. SiO2 is located in the middle part of the nanospheres, and the microstructure of SiO2 is easier to control. The entire external microstructure is easy to control. Detailed Implementation

[0049] 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.

[0050] Example 1

[0051] This invention provides a technical solution: a lithium battery modified coating separator, comprising the following components:

[0052] SiO2: 10 parts; Al2O3: 30 parts; Solvent: 2 parts; Additive: 3 parts.

[0053] The solvent consists of the following components:

[0054] Deionized water: 6 parts; acetic acid: 7 parts; nano metal powder: 1 part; ceramic particles: 2 parts.

[0055] The additive consists of the following components:

[0056] Thickener: 1 part; binder: 1 part; dispersant: 1 part.

[0057] A method for preparing a modified coating separator for lithium batteries includes the following steps:

[0058] 1) Prepare the solvent and store it at room temperature for later use;

[0059] 1.1) Add deionized water and acetic acid to a stirring device and stir. Use a commonly used laboratory stirring device. Stir at a speed of 3215 r / min and at a pressure of standard atmosphere for 20 min.

[0060] 1.2) After mixing in step 1.1), turn on the stirring device, add the nano metal powder and ceramic particles into the stirring device, and stir at a speed of 1680 r / min. The stirring pressure is two standard atmospheres, until a uniform paste is formed.

[0061] 2) Prepare the additive and store it at room temperature for later use;

[0062] Thickener, binder and dispersant are added to a stirring device and stirred at a speed of 1200 r / min and a stirring pressure of standard atmospheric pressure until a uniform paste is formed.

[0063] 3) Preparation of Al2O3 powder;

[0064] 3.1) Calcination precursors, the precursors include: gibbsite, boehmite, boehmite, ammonium aluminum carbonate and ammonium aluminum sulfate;

[0065] 3.2) Ultrafine powder can be obtained by calcining the precursor and then wet grinding, drying and pulverizing and classifying it.

[0066] 4) Mix Al2O3 with solvent and additives to obtain a mixture;

[0067] 4.1) Add the ultrafine powder obtained in step S4 into the stirring device, and at the same time add the solvent and additives into the stirring device;

[0068] 4.2) Heat the stirring device in a water bath to a temperature of 60-80 degrees Celsius. Use the stirring device at a speed of 1200 r / min for 15 minutes, and then cool it to room temperature.

[0069] 4.3) After cooling to room temperature, stir at a stirring speed of 3600 r / min until it becomes a semi-paste.

[0070] 5) Prepare SiO2 nanospheres and use them to encapsulate the mixture obtained in step 4;

[0071] 5.1) Add ammonia to the polyacrylic acid aqueous solution, stir evenly, add anhydrous ethanol, stir at room temperature for 1 hour, add tetraethyl orthosilicate dropwise, continue to stir at room temperature in a sealed container for 12 hours, centrifuge and wash the resulting solution, and dry it in an oven at 50°C to obtain hollow mesoporous silica.

[0072] 5.2) Add deionized water to the semi-paste mixture formed by mixing Al2O3 with solvent and additives to form a solution.

[0073] 5.3) Stir the hollow mesoporous silica and the solution to allow the solution to enter the hollow mesoporous silica, forming a saturated silica solution;

[0074] 5.4) Add the saturated silica solution to the high-speed shear disperser for nano-GTO dispersion and shear it.

[0075] 6) Drying and packaging.

[0076] 6.1) Dry the product obtained in step S5) and allow it to cool naturally to room temperature;

[0077] 6.2) Then use a packaging machine to package it.

[0078] Example 2

[0079] This embodiment is largely the same as the method in Embodiment 1, with the main difference being: SiO2: 12.5 parts; Al2O3: 40 parts; solvent: 4.5 parts; additives: 6 parts.

[0080] The solvent consists of the following components:

[0081] Deionized water: 7 parts; acetic acid: 8 parts; nano metal powder: 2 parts; ceramic particles: 3 parts.

[0082] The additive consists of the following components:

[0083] Thickener: 1.25 parts; binder: 1.25 parts; dispersant: 1.25 parts.

[0084] Example 3

[0085] This embodiment is largely the same as the method in Embodiment 1 provided, with the main difference being: SiO2: 15 parts; Al2O3: 50 parts; solvent: 7 parts; additives: 9 parts.

[0086] The solvent consists of the following components:

[0087] Deionized water: 8 parts; acetic acid: 9 parts; nano metal powder: 3 parts; ceramic particles: 4 parts.

[0088] The additive consists of the following components:

[0089] Thickener: 1.5 parts; binder: 1.5 parts; dispersant: 1.5 parts.

[0090] Comparative Example 1

[0091] This comparative example is largely the same as the method of Example 1 provided, the main difference being that SiO2 was not added.

[0092] Comparative Example 2

[0093] This comparative example is largely the same as the method of the provided Example 1, the main difference being that step S5 is not performed.

[0094] Comparative Example 3

[0095] This comparative example is largely the same as the method in Example 1 provided, the main difference being that step S5.4) is not performed.

[0096] Performance testing

[0097] Waste rates of equal amounts of the fabric raw materials provided in Examples 1-3 and Comparative Examples 1-3:

[0098] Regulation Electrical conductivity and ionic properties Example 1 99.6％ 99.9％ Example 2 99.9％ 99.9％ Example 3 99.2％ 99.9％ Comparative Example 1 99.9％ 88.9％ Comparative Example 2 80.0％ 83.9％ Comparative Example 3 96.9％ 96.9％

[0099] Analysis of the relevant data in the tables above shows that:

[0100] SiO2: 12.5 parts; Al2O3: 40 parts; Solvent: 4.5 parts; Additives: 6 parts.

[0101] The solvent consists of the following components:

[0102] Deionized water: 7 parts; acetic acid: 8 parts; nano metal powder: 2 parts; ceramic particles: 3 parts.

[0103] The additive consists of the following components:

[0104] Thickener: 1.25 parts; binder: 1.25 parts; dispersant: 1.25 parts.

[0105] 1) Prepare the solvent and store it at room temperature for later use;

[0106] 1.1) Add deionized water and acetic acid to a stirring device and stir. Use a commonly used laboratory stirring device. Stir at a speed of 3215 r / min and at a pressure of standard atmosphere for 20 min.

[0107] 1.2) After mixing in step 1.1), turn on the stirring device, add the nano metal powder and ceramic particles into the stirring device, and stir at a speed of 1680 r / min. The stirring pressure is two standard atmospheres, until a uniform paste is formed.

[0108] 2) Prepare the additive and store it at room temperature for later use;

[0109] Thickener, binder and dispersant are added to a stirring device and stirred at a speed of 1200 r / min and a stirring pressure of standard atmospheric pressure until a uniform paste is formed.

[0110] 3) Preparation of Al2O3 powder;

[0111] 3.1) Calcination precursors, the precursors include: gibbsite, boehmite, boehmite, ammonium aluminum carbonate and ammonium aluminum sulfate;

[0112] 3.2) Ultrafine powder can be obtained by calcining the precursor and then wet grinding, drying and pulverizing and classifying it.

[0113] 4) Mix Al2O3 with solvent and additives to obtain a mixture;

[0114] 4.1) Add the ultrafine powder obtained in step S4 into the stirring device, and at the same time add the solvent and additives into the stirring device;

[0115] 4.2) Heat the stirring device in a water bath to a temperature of 60-80 degrees Celsius. Use the stirring device at a speed of 1200 r / min for 15 minutes, and then cool it to room temperature.

[0116] 4.3) After cooling to room temperature, stir at a stirring speed of 3600 r / min until it becomes a semi-paste.

[0117] 5) Prepare SiO2 nanospheres and use them to encapsulate the mixture obtained in step 4;

[0118] 5.1) Add ammonia to the polyacrylic acid aqueous solution, stir evenly, add anhydrous ethanol, stir at room temperature for 1 hour, add tetraethyl orthosilicate dropwise, continue to stir at room temperature in a sealed container for 12 hours, centrifuge and wash the resulting solution, and dry it in an oven at 50°C to obtain hollow mesoporous silica.

[0119] 5.2) Add deionized water to the semi-paste mixture formed by mixing Al2O3 with solvent and additives to form a solution.

[0120] 5.3) Stir the hollow mesoporous silica and the solution to allow the solution to enter the hollow mesoporous silica, forming a saturated silica solution;

[0121] 5.4) Add the saturated silica solution to the high-speed shear disperser for nano-GTO dispersion and shear it.

[0122] 6) Drying and packaging.

[0123] 6.1) Dry the product obtained in step S5) and allow it to cool naturally to room temperature;

[0124] 6.2) Then use a packaging machine to package it.

[0125] The interior of silica is made hollow. A semi-paste mixture formed by mixing Al2O3 with solvents and additives is added to the interior of the silica. Then, it is sheared to form an outer layer of the semi-paste mixture of Al2O3 with solvents and additives, with hollow mesoporous silica in the middle and the semi-paste mixture of Al2O3 with solvents and additives in the interior, forming a sandwich shape. This maintains the stability of both the exterior and interior, forming a lithium battery modified coating membrane that is easy to control and has good ion conductivity. Alumina improves rate performance and cycle performance, has good wettability, and has a certain liquid absorption and retention capacity. The microstructure of SiO2 is easier to control. SiO2 is located in the middle part of the nanospheres, and its microstructure is easier to control. The entire external microstructure is easy to control, which can effectively solve the background problems and greatly improve its controllability and ion conductivity.

[0126] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a modified coating separator for lithium batteries, characterized in that, Includes the following steps: 1) Prepare the solvent and store it at room temperature for later use; 2) Prepare the additive and store it at room temperature for later use; 3) Preparation of Al2O3 powder; 4) Mix Al2O3 with solvent and additives to obtain a mixture; 5) Prepare SiO2 nanospheres and use them to encapsulate the mixture obtained in step 4; 6) Drying and packaging; The solvent comprises the following components: Deionized water: 6-8 parts; Acetic acid: 7-9 parts; Nano metal powder: 1-3 parts; Ceramic particles: 2-4 parts; The additive comprises the following components: Thickener: 1-1.5 parts; Binder: 1-1.5 parts; Dispersant: 1-1.5 parts; The preparation of Al2O3 powder includes the following steps: 3.1) Calcination precursors, the precursors include: gibbsite, boehmite, boehmite, ammonium aluminum carbonate and ammonium aluminum sulfate; 3.2) Ultrafine powder can be obtained by calcining the precursor and then wet grinding, drying and pulverizing and classifying it; The preparation of SiO2 nanospheres, which involves encapsulating the mixture obtained in step 4 with SiO2 nanospheres, includes the following steps: 5.1) Add ammonia to the polyacrylic acid aqueous solution, stir evenly, add anhydrous ethanol, stir at room temperature for 1 hour, add tetraethyl orthosilicate dropwise, continue to stir at room temperature in a sealed container for 12 hours, centrifuge and wash the resulting solution, and dry it in an oven at 50°C to obtain hollow mesoporous silica. 5.2) Add deionized water to the semi-paste mixture formed by mixing Al2O3 with solvent and additives to form a solution. 5.3) Stir the hollow mesoporous silica and the solution to allow the solution to enter the hollow mesoporous silica, forming a saturated silica solution; 5.4) Add the saturated silica solution to the high-speed shear disperser for nano-GTO dispersion and shear it.

2. The method for preparing a modified coating separator for lithium batteries according to claim 1, characterized in that, Solution preparation includes the following steps: 1.1) Add deionized water and acetic acid to a stirring device and stir. Use a commonly used laboratory stirring device. Stir at a speed of 3215 r / min and at a pressure of standard atmosphere for 20 min. 1.2) After mixing in step 1.1), turn on the stirring device, add the nano metal powder and ceramic particles into the stirring device, and stir at a speed of 1680 r / min. Use two standard atmospheres for stirring until a uniform paste is formed.

3. The method for preparing a modified coating separator for lithium batteries according to claim 1, characterized in that, The additive is prepared by the following steps: Thickener, binder and dispersant are added to a stirring device and stirred at a speed of 1200 r / min and a stirring pressure of standard atmospheric pressure until a uniform paste is formed.

4. The method for preparing a modified coating separator for lithium batteries according to claim 1, characterized in that, The process of mixing and stirring Al2O3 with solvent and additives includes the following steps: 4.1) Add the ultrafine powder obtained in step S4 into the stirring device, and at the same time add the solvent and additives into the stirring device; 4.2) Heat the stirring device in a water bath to a temperature of 60-80 degrees Celsius. Use the stirring device at a speed of 1200 r / min for 15 minutes, and then cool it to room temperature. 4.3) After cooling to room temperature, stir at a stirring speed of 3600 r / min until it becomes a semi-paste.

5. The method for preparing a modified coating separator for lithium batteries according to claim 1, characterized in that, The drying and packaging process includes the following steps: 6.1) Dry the product obtained in step S5) and allow it to cool naturally to room temperature; 6.2) Then use a packaging machine to package it.