Preparation method of boehmite slurry, boehmite slurry and application thereof

Abstract

The present application relates to a method for preparing a boehmite slurry, comprising the following steps: grinding aluminum hydroxide to a predetermined particle size and then preparing an aluminum hydroxide dispersion with water; subjecting the aluminum hydroxide dispersion to a hydrothermal reaction to obtain a boehmite dispersion; filtering the boehmite dispersion to obtain a filter residue, and mixing the filter residue with a dispersant to obtain a slurry. The method for preparing a boehmite slurry provided in an embodiment of the present application directly selects a single aluminum source of aluminum hydroxide, utilizes a hydrothermal reaction to convert aluminum hydroxide into a γ-phase monohydrated aluminum oxide to form boehmite, and then directly mixes the boehmite with a dispersant to obtain a slurry after filtering out the boehmite, thereby eliminating the step of drying. Therefore, the present application has the effects of low raw material cost, simple process, and no drying process.

Description

Technical Field

[0001] The present application relates to the field of lithium batteries, and in particular to boehmite slurry for lithium battery separators. Background Art

[0002] With the rapid development of lithium battery materials in recent years, in the upstream diaphragm field, the demand for ternary materials has driven the rapid increase in the demand for diaphragm coating to meet the strong demand for products from downstream customers. The main function of the diaphragm is to separate the positive and negative electrodes of the battery to prevent the two electrodes from contacting and causing a short circuit. In addition, it also acts as an electrolyte ion channel. At present, alumina and boehmite are one of the important raw materials for lithium-ion battery diaphragm coating materials, which will have an important impact on the properties of lithium-ion battery diaphragms.

[0003] Among the current boehmite preparation methods, there are mainly aluminum salt hydrolysis method, hydrothermal method, sol-gel method, etc. The existing preparation methods often require the selection of multiple aluminum sources such as aluminum-containing organic matter and aluminum hydroxide, and sometimes require the use of organic solvents such as N-methylpyrrolidone. The raw material cost is high and the process is complicated. In addition, the existing boehmite preparation methods ultimately obtain dried boehmite powder, and impurities may be introduced during the drying process. Summary of the invention

[0004] The embodiments of the present application provide a method for preparing boehmite slurry, boehmite slurry and applications thereof, in order to solve the technical problems existing in the preparation of boehmite slurry, such as high raw material cost, complex process and introduction of impurities in the drying process.

[0005] In a first aspect, an embodiment of the present application provides a method for preparing a boehmite slurry, and the method for preparing a boehmite slurry comprises the following steps:

[0006] Grinding aluminum hydroxide to a predetermined particle size and then mixing with water to prepare an aluminum hydroxide dispersion;

[0007] subjecting the aluminum hydroxide dispersion to a hydrothermal reaction to obtain a boehmite dispersion;

[0008] The boehmite dispersion is filtered to obtain a filter residue, and the filter residue is mixed with a dispersant to obtain a slurry.

[0009] In some embodiments of the present application, the predetermined particle size is D50=0.8-1.2 um.

[0010] In some embodiments of the present application, the particle size of the aluminum hydroxide is D50=2-5um.

[0011] In some embodiments of the present application, the mass concentration of the aluminum hydroxide dispersion is 200-300 g / L.

[0012] In some embodiments of the present application, the temperature of the hydrothermal reaction is 180-220° C.; and / or,

[0013] The hydrothermal reaction time is 1-5h.

[0014] In some embodiments of the present application, the dispersant is a polycarboxylate suspending agent.

[0015] In some embodiments of the present application, the filter residue is mixed with a dispersant, and the mixing is performed at a stirring rate of 3000-8000 r / min and lasts for 0.5-1 h.

[0016] In a second aspect, an embodiment of the present application provides a boehmite slurry, wherein the boehmite slurry is prepared by the method for preparing the boehmite slurry described in any embodiment of the first aspect.

[0017] In some embodiments of the present application, the concentration of the boehmite slurry is 45-50%.

[0018] In a third aspect, an embodiment of the present application provides an application of a boehmite slurry, wherein the boehmite slurry is the boehmite slurry described in any embodiment of the second aspect, and the boehmite slurry is applied to coating of a lithium battery separator.

[0019] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0020] The method for preparing boehmite slurry provided in the embodiment of the present application directly selects aluminum hydroxide as a single aluminum source, utilizes a hydrothermal reaction to convert aluminum hydroxide into γ-phase monohydrated aluminum oxide to form boehmite, and then filters the boehmite and directly mixes it with a dispersant to obtain a slurry, thereby eliminating the drying step. Therefore, the present application has the effects of low raw material cost, simple process, and no drying process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0023] Figure 1 A schematic flow chart of a method for preparing a boehmite slurry provided in an embodiment of the present application;

[0024] Figure 2This is a SEM image of the powder obtained by drying the boehmite slurry in Example 1 of the present application at a magnification of 2000;

[0025] Figure 3 This is a SEM image of the powder obtained by drying the boehmite slurry in Example 1 of the present application at a magnification of 10,000;

[0026] Figure 4 This is a table showing the viscosity changes of the boehmite slurries obtained in Example 3 and Comparative Example 1-2 of the present application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0028] Unless otherwise specified, the terms used herein should be understood as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. In the event of a conflict, this specification takes precedence.

[0029] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0030] The existing preparation of boehmite slurry has technical problems such as high raw material cost, complex process and introduction of impurities during the drying process.

[0031] The technical solution provided by the embodiments of the present application is to solve the above technical problems, and the overall idea is as follows:

[0032] In the first aspect, the present invention provides a method for preparing a boehmite slurry. Figure 1 , the preparation method of the boehmite slurry comprises the following steps:

[0033] S1: grinding aluminum hydroxide to a predetermined particle size and then mixing with water to prepare an aluminum hydroxide dispersion;

[0034] S2: subjecting the aluminum hydroxide dispersion to a hydrothermal reaction to obtain a boehmite dispersion;

[0035] S3: filtering the boehmite dispersion to obtain filter residue, and mixing the filter residue with a dispersant to obtain a slurry.

[0036] In step S2, the hydrothermal reaction can convert aluminum hydroxide into γ-phase aluminum oxide monohydrate, that is, the crystalline phase of boehmite.

[0037] The main function of the dispersant in step S3 is to make the boehmite in the form of microparticles more stably suspended in water. The dispersant can be a general surfactant.

[0038] The present application directly selects aluminum hydroxide as a single aluminum source, utilizes a hydrothermal reaction to convert aluminum hydroxide into γ-phase monohydrated aluminum oxide to form boehmite, and then filters out the boehmite and directly mixes it with a dispersant to obtain a slurry, thereby eliminating the drying step. Therefore, the present application has the effects of low raw material cost, simple process, and no drying process.

[0039] In some embodiments of the present application, the predetermined particle size is D50=0.8-1.2 um.

[0040] The beneficial effect of controlling the predetermined particle size to D50=0.8-1.2 um is that an aluminum hydroxide dispersion with good dispersion effect can be obtained without causing the particle size of boehmite in the boehmite dispersion to be too small, resulting in difficulty in filtering.

[0041] In some embodiments of the present application, the particle size of the aluminum hydroxide is D50=2-5um.

[0042] The beneficial effect of selecting the particle size of the aluminum hydroxide to be D50=2-5um is that the grinding effect can be easily controlled so that the grinding can reach a predetermined particle size.

[0043] In some embodiments of the present application, the mass concentration of the aluminum hydroxide dispersion is 200-300 g / L.

[0044] The beneficial effect of controlling the mass concentration of the aluminum hydroxide dispersion to 200-300 g / L is that it can maintain a good dispersion effect and ensure that the particle agglomeration phenomenon is less during the hydrothermal reaction, while not causing too long filtration time due to too low concentration.

[0045] In some embodiments of the present application, the temperature of the hydrothermal reaction is 180-220° C.; and / or,

[0046] The hydrothermal reaction time is 1-5h.

[0047] The hydrothermal reaction temperature of 180-220°C is conducive to the conversion of aluminum hydroxide into γ-phase monohydrated aluminum oxide.

[0048] The beneficial effect of controlling the hydrothermal reaction time to 1-5 hours is that it can ensure that the hydrothermal reaction proceeds fully without causing a large amount of particle agglomeration due to too long heating time.

[0049] In some embodiments of the present application, the dispersant is a polycarboxylate suspending agent.

[0050] There are a large number of hydroxyl groups on the surface of boehmite, and polycarboxylate suspending agents can have a good suspension effect on boehmite.

[0051] In some embodiments of the present application, the filter residue is mixed with a dispersant, and the mixing is performed at a stirring rate of 3000-8000 r / min and lasts for 0.5-1 h.

[0052] In a second aspect, an embodiment of the present application provides a boehmite slurry, which is prepared by the method for preparing boehmite slurry described in any embodiment of the first aspect. Since the boehmite slurry is implemented based on the first aspect, it has all the beneficial effects of the first aspect, which will not be repeated here.

[0053] In some embodiments of the present application, the concentration of the boehmite slurry is 45-50%.

[0054] The boehmite slurry of the above concentration can not only maintain a relatively stable suspension state, but also have a good coating effect on the lithium battery separator.

[0055] In a third aspect, an embodiment of the present application provides an application of a boehmite slurry, wherein the boehmite slurry is the boehmite slurry described in any embodiment of the second aspect, and the boehmite slurry is applied to the coating of a lithium battery separator. Since the application of the boehmite slurry is implemented based on the second aspect, it has all the beneficial effects of the second aspect, which will not be repeated here.

[0056] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0057] Example 1

[0058] This embodiment provides a method for preparing boehmite slurry, comprising the following steps:

[0059] Sa: Add 200 g of aluminum hydroxide with a particle size of D50 = 2 um into 500 ml of water and stir to make it completely dispersed. Then grind the obtained liquid to the particle size of the aluminum hydroxide to D50 = 0.8 um, and add 500 ml of pure water to obtain an aluminum hydroxide dispersion.

[0060] Sb: The aluminum hydroxide dispersion was transferred to a hydrothermal reactor and reacted at 200° C. for 2 h.

[0061] Sc: The reactants were cooled to below 80° C. and filtered to obtain a boehmite filter cake. The filter cake was mixed with 200 ml of a dispersant under continuous stirring at a stirring rate of 5000 r / min for 1 h to obtain the boehmite slurry.

[0062] The dispersant is a polycarboxylate suspending agent.

[0063] Example 2

[0064] This embodiment provides a method for preparing boehmite slurry, comprising the following steps:

[0065] Sa: Add 200 g of aluminum hydroxide with a particle size of D50 = 5 um to 500 ml of water and stir to make it completely dispersed. Then grind the obtained liquid to the particle size of the aluminum hydroxide to D50 = 1.2 um, and add 500 ml of pure water to obtain an aluminum hydroxide dispersion.

[0066] Sb: The aluminum hydroxide dispersion was transferred to a hydrothermal reactor and reacted at 180° C. for 2 h.

[0067] Sc: The reactants are cooled to below 80° C. and filtered to obtain a boehmite filter cake. The filter cake is mixed with 100 ml of a dispersant under continuous stirring at a stirring rate of 3000-8000 r / min for 0.5-1 h to obtain the boehmite slurry.

[0068] The dispersant is a polycarboxylate suspending agent.

[0069] Example 3

[0070] This embodiment provides a method for preparing boehmite slurry, comprising the following steps:

[0071] Sa: Add 200 g of aluminum hydroxide with a particle size of D50 = 3 um into 500 ml of water and stir to make it completely dispersed. Then grind the obtained liquid to the particle size of the aluminum hydroxide to D50 = 0.9 um, and add 500 ml of pure water to obtain an aluminum hydroxide dispersion.

[0072] Sb: The aluminum hydroxide dispersion was transferred to a hydrothermal reactor and reacted at 200° C. for 5 h.

[0073] Sc: The reactants were cooled to below 80° C. and filtered to obtain a boehmite filter cake. The filter cake was mixed with 300 ml of a dispersant under continuous stirring at a stirring rate of 5000 r / min for 1 h to obtain the boehmite slurry.

[0074] The dispersant is a polycarboxylate suspending agent.

[0075] Comparative Example 1

[0076] This comparative example provides a method for preparing a boehmite slurry, comprising the following steps:

[0077] Sa: Add 200g of aluminum hydroxide with a particle size of D50=2-5um to 500ml of water and stir to make it completely dispersed. Then grind the obtained liquid to the particle size of the aluminum hydroxide to D50=0.8-1.2um, and add 500ml of pure water to obtain an aluminum hydroxide dispersion.

[0078] Sb: The aluminum hydroxide dispersion was transferred to a hydrothermal reactor and reacted at 200° C. for 2 h.

[0079] Sc: The reactants were cooled to below 80° C. and filtered to obtain a boehmite filter cake. The filter cake was mixed with 200 ml of water under continuous stirring at a stirring rate of 5000 r / min for 1 h to obtain the boehmite slurry.

[0080] The dispersant is a polycarboxylate suspending agent.

[0081] Comparative Example 2

[0082] This comparative example provides a method for preparing a boehmite slurry, comprising the following steps:

[0083] Sa: Add 200 g of aluminum hydroxide with a particle size of D50 = 7 um into 500 ml of water and stir to make it completely dispersed. Then grind the obtained liquid until the particle size of the aluminum hydroxide is D50 = 1.4 um, and add 500 ml of pure water to obtain an aluminum hydroxide dispersion.

[0084] Sb: The aluminum hydroxide dispersion was transferred to a hydrothermal reactor and reacted at 200° C. for 2 h.

[0085] Sc: The reactants were cooled to below 80° C. and filtered to obtain a boehmite filter cake. The filter cake was mixed with 200 ml of a dispersant under continuous stirring at a stirring rate of 5000 r / min for 1 h to obtain the boehmite slurry.

[0086] The dispersant is a polycarboxylate suspending agent.

[0087] Related experiments and effect data:

[0088] The boehmite slurry obtained in Example 1 was dried to obtain boehmite powder, and the boehmite powder was tested by scanning electron microscopy. The results are shown in Figure 2-Figure 3 . Figure 2 and Figure 3 This indicates that Example 1 obtained boehmite with a relatively uniform particle size.

[0089] The above boehmite powder was tested for laser particle size distribution. Please refer to the results. Figure 4 .

[0090] The newly prepared boehmite slurries of Examples 1-3 and Comparative Examples 1-2 were allowed to stand at 25° C., during which the viscosity was continuously tested. The results are shown in the following table.

[0091] Initial viscosity (mPa·s) Viscosity after 10 days (mPa·s) Suspension performance Example 1 20 18 good Example 2 57 98 generally Example 3 22 24 good Comparative Example 1 500 800 Difference Comparative Example 2 126 180 generally

[0092] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0093] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. refer to "including but not limited to". Moreover, the terms "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "including..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that any one of these three associated objects can exist alone, or any at least two of them exist at the same time. For example, for A, and / or B, and / or C, it can be represented that any one of A, B, and C exists alone, or any two of them exist at the same time, or three of them exist at the same time. In this article, "at least one" refers to one or more, and "multiple" refers to two or more. "At least one", "the following at least one (individual)" or similar expressions refer to any combination of these items, including any combination of single (individual) or plural (individual). For example, "at least one (individual) of a, b, or c", or "at least one (individual) of a, b, and c", can all represent: a, b, c, ab (i.e. a and b), ac, bc, or abc, wherein a, b, and c can be single or multiple, respectively.

[0094] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. An application of boehmite slurry, characterized in that: The boehmite slurry is applied to the coating of lithium battery separators, and the preparation method of the boehmite slurry comprises the following steps: Grinding aluminum hydroxide to a predetermined particle size and then mixing with water to prepare an aluminum hydroxide dispersion; subjecting the aluminum hydroxide dispersion to a hydrothermal reaction to obtain a boehmite dispersion; filtering the boehmite dispersion to obtain a filter residue, and mixing the filter residue with a dispersant to obtain a slurry; The predetermined particle size is D50=0.8-1.2 μm; The particle size of the aluminum hydroxide is D50=2-5 μm; The mass concentration of the aluminum hydroxide dispersion is 200-300 g / L; The temperature of the hydrothermal reaction is 180-220° C.; and / or, The hydrothermal reaction time is 1-5h; The dispersant is a polycarboxylate suspending agent; The filter residue is mixed with a dispersant, and the mixing is performed at a stirring rate of 3000-8000 r / min for 0.5-1 h; The concentration of the boehmite slurry is 45-50%.

Images