Preparation method of uniform battery slurry, battery slurry and electrochemical energy storage device

Abstract

The invention discloses a preparation method of uniform battery slurry, battery slurry and an electrochemical energy storage device, and the method comprises the following steps: carrying out dry mixing on active substance powder, a first conductive agent and a binder to obtain a first mixed material; adding a second conductive agent to obtain a second mixed material, dispersing a solvent into the second mixed material, and stirring to obtain first mixed slurry with the solid content of 75-80 wt%; dispersing a second conductive agent and a solvent into the first mixed slurry, and stirring to obtain second mixed slurry with the solid content of 71-85 wt%; stirring the second mixed slurry at 35-80 DEG C; adding a solvent into the obtained second mixed slurry, and stirring to obtain third mixed slurry; and adding a dispersing agent into the third mixed slurry, and stirring, wherein the weight of the dispersing agent is 0.1-1% of the dry weight of the third mixed slurry. According to the invention, the solid content and viscosity standing retention capability of the slurry are improved.

Description

Technical Field

[0001] The invention relates to the technical field of battery preparation, and in particular to a method for preparing a battery uniform slurry, a battery slurry and an electrochemical energy storage device. Background Art

[0002] Since the 1990s, with the development of lithium battery research, it has been widely used in various fields. It has gradually replaced lead-acid batteries and nickel-chromium batteries. It has become the main force of power batteries. With the development of the industry, the pursuit of higher specific capacity and volume energy density has led to the nano-size of positive and negative electrode powder materials, and the application of conductive materials such as carbon nanotubes and graphene has increased. This has posed a great challenge to the dispersion ability of the homogenization stage.

[0003] The positive electrode materials of lithium batteries mainly include: active materials, conductive agents, binders and solvents. Taking lithium iron phosphate as an example, the solid content of conventional homogenization process is basically around 47%-52% in wet method and around 52%-56% in dry method.

[0004] Conventional homogenization processes have the problems of low solid content and low static viscosity retention. Therefore, it is urgent to develop a method for preparing a uniform battery slurry, a battery slurry and an electrochemical energy storage device. Summary of the invention

[0005] In view of the above problems, the present invention provides a method for preparing a uniform battery slurry, a battery slurry and an electrochemical energy storage device, which improve the solid content of the slurry and the static viscosity retention capacity.

[0006] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a uniform battery slurry, comprising:

[0008] Step 1, dry-mixing the active material powder, the first conductive agent and the binder to obtain a first mixed material;

[0009] Step 2, adding a second conductive agent to the first mixed material to obtain a second mixed material, dispersing a solvent into the second mixed material, stirring the second mixed material, and obtaining a first mixed slurry with a solid content of 75wt% to 80wt%;

[0010] Step 3, dispersing the second conductive agent and the solvent into the first mixed slurry, stirring to obtain a second mixed slurry, wherein the second mixed slurry has a solid content of 71wt%-85wt%;

[0011] Step 4, stirring the second mixed slurry at 35-80° C.;

[0012] Step 5, adding a solvent to the second mixed slurry obtained in step 4, and stirring to obtain a third mixed slurry;

[0013] Step 6: Add a dispersant to the third mixed slurry and stir. The weight of the dispersant is 0.1%-1% of the dry weight of the third mixed slurry.

[0014] In a preferred embodiment, the stirring in step 6 is specifically: first stirring at a revolution speed of 30±10RPM and a rotation speed of 25±10m / s for 30-80 minutes, and then stirring at a revolution speed of 20±10RPM and a rotation speed of 10±5m / s for 10-30 minutes.

[0015] In a preferred embodiment, the solid content of the third mixed slurry in step 5 is 57wt%-70wt%.

[0016] In a preferred embodiment, the weight ratio of the second conductive agent added in step 3 to the weight ratio of the second conductive agent added in step 2 is 3:7 to 7:3.

[0017] In a preferred embodiment, the stirring speed in step 3 is 30±10 RPM, the rotation speed is 10±5 m / s, and the stirring time is 50-110 minutes.

[0018] In a preferred embodiment, the stirring speed in step 4 is 30±10 RPM for revolution, 15±5 m / s for rotation, and the stirring time is 90-220 minutes.

[0019] In a preferred embodiment, the active material is lithium iron phosphate powder, the first conductive agent is carbon black, and the second conductive agent is carbon nanotubes.

[0020] In a second aspect, the present invention provides a battery slurry, wherein the battery slurry is prepared by the method for preparing a battery uniform slurry according to the first aspect.

[0021] In a third aspect, the present invention provides an electrochemical energy storage device, wherein the electrochemical energy storage device comprises the battery slurry described in the second aspect.

[0022] In a preferred embodiment, the electrochemical energy storage device comprises a lithium-ion battery.

[0023] The effects of the method for preparing a uniform battery slurry, the battery slurry and the electrochemical energy storage device of the present invention are as follows: the present invention provides a new method for preparing a uniform battery slurry by controlling the solid content of the initial wetting in step 2, the solid content of the secondary wetting in step 3, the stirring temperature in step 4, and the amount of dispersant added in step 6, etc., and the method improves the slurry solid content and viscosity static retention ability. The slurry of the present invention has a high solid content, and the high solid content can improve the coating efficiency in the preparation of the electrochemical energy storage device, reduce the energy consumption of the oven in the preparation of the electrochemical energy storage device, and reduce the preparation cost of the electrochemical energy storage device. The good viscosity retention of the slurry of the present invention can improve the consistency of the coating surface density in the preparation of the electrochemical energy storage device and increase the yield rate of the electrochemical energy storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 The present invention is a flow chart of a method for preparing uniform battery slurry.

[0026] Figure 2 The present invention is a specific flow chart of a method for preparing a uniform battery slurry.

[0027] Figure 3 This is a comparison chart of the battery slurry prepared by the preparation method of the present invention and the slurry of the prior art. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0029] It should be noted that the descriptions involving "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0030] Below, a method for preparing a battery uniform slurry, a battery slurry, an electrochemical energy storage device and their technical effects are described.

[0031] This embodiment provides a method for preparing a uniform battery slurry. Figure 1 , including the following steps:

[0032] Step 1, dry-mixing the active material powder, the conductive agent and the binder to obtain a first mixed material;

[0033] Step 2, adding a second conductive agent to the first mixed material to obtain a second mixed material, dispersing a solvent into the second mixed material, stirring the second mixed material, and obtaining a first mixed slurry with a solid content of 75wt% to 80wt%;

[0034] Step 3, dispersing the second conductive agent and the solvent into the first mixed slurry, and stirring the first mixed slurry to obtain a second mixed slurry, wherein the solid content of the second mixed slurry is 71wt%-85wt%;

[0035] Step 4, stirring the second mixed slurry at 35-80° C.;

[0036] Step 5, adding a solvent to the second mixed slurry obtained in step 4, and stirring to obtain a third mixed slurry;

[0037] Step 6: Add a dispersant to the third mixed slurry and stir. The weight of the dispersant is 0.1%-1% of the dry weight of the third mixed slurry.

[0038] It should be understood that the first conductive agent and the second conductive agent can be the same conductive agent or different conductive agents. The solvents in different steps can also be different.

[0039] The following is a detailed description of a method for preparing a uniform battery slurry. As a preferred embodiment but not a limitation, the active material is lithium iron phosphate, the conductive agent is carbon nanotubes and SP (conductive carbon black), the binder is PVDF (polyvinylidene fluoride), the solvent is NMP (N-methylpyrrolidone), and the dispersant model of lithium iron phosphate is HA-02D.

[0040] See also Figure 2 , including the following steps:

[0041] Step 1: dry-mix lithium iron phosphate powder, conductive carbon black and polyvinylidene fluoride using a mixer to obtain a first mixed material.

[0042] Specifically, the solid content of lithium iron phosphate is 100wt%, the solid content of polyvinylidene fluoride is 100wt%, and the solid content of conductive carbon black is 100wt%, and the three are dry-mixed for 30-60 minutes.

[0043] Step 2: Add carbon nanotubes to the first mixed material to obtain a second mixed material, disperse the solvent into the second mixed material, and continue to stir the second mixed material with a stirrer to obtain a first mixed slurry with a solid content of 75wt% to 80wt%.

[0044] The second mixed material is stirred at a slow speed for 20-50 minutes, wherein the slow stirring speed is: revolution 20±10RPM, rotation linear speed 10±5m / s.

[0045] Step 3: Disperse carbon nanotubes and a solvent (capable of dissolving lithium iron phosphate and polymer electrolyte) into the first mixed slurry, and stir with a stirrer to obtain a second mixed slurry, wherein the second mixed slurry has a solid content of 71 wt%-85 wt%.

[0046] Specifically, the weight ratio of the carbon nanotubes added in step 3 to the weight ratio of the carbon nanotubes added in step 2 is in the range of 3:7 to 7:3.

[0047] The stirring time of step 3 is 50-110 minutes, specifically: slow stirring for 30-60 minutes, scraping, continuing slow stirring for 20-50 minutes, scraping. The slow stirring speed is 30±10RPM for revolution and 10±5m / s for rotation.

[0048] Step 4: Stir the second mixed slurry with a stirrer for 90-220 minutes. During stirring, the temperature of the second mixed slurry is controlled at 35-80 degrees Celsius.

[0049] The stirring in step 4 is medium speed stirring, and the speed is: revolution 30±10RPM, rotation linear speed 15±5m / s.

[0050] Step 5: Add a solvent to the second mixed slurry obtained in step 4, and stir with a stirrer to obtain a third mixed slurry. The solid content of the third mixed slurry is 57wt%-70wt%.

[0051] The stirring speed in step 5 is high speed, that is, the speed is 30±10RPM for revolution and 20±5m / s for rotation.

[0052] The ratio of the weight of the solvent added in step 5 to the weight of the solvent added in step 3 is not limited.

[0053] Step 6: Add a dispersant to the third mixed slurry and stir it with a stirrer. The weight of the added dispersant is 0.1%-1% of the dry weight of the third mixed slurry (the weight after removing all solvents).

[0054] In step 6, first disperse and stir at high speed for 30-80 minutes, and then stir at slow speed for 10-30 minutes, wherein the high speed is 30±10RPM for revolution and 25±10m / s for rotation, and the slow speed is 20±10RPM for revolution and 10±5m / s for rotation.

[0055] The stirring in step 6 is completed to obtain a uniform slurry.

[0056] Furthermore, the preparation method also includes step 7, which is: testing the viscosity, solid content, fineness, pH value, etc. of the fourth mixed slurry, and screening and removing the magnetic material after all meeting the standards.

[0057] Where the stirring temperature is not mentioned in this embodiment, it can be room temperature, which can be within the range of 15-30°C.

[0058] In this embodiment, the active material includes but is not limited to lithium iron phosphate, lithium iron manganese phosphate, ternary, layered oxide, graphite, etc.; the conductive agent includes but is not limited to carbon nanotubes, SP, graphene, KS-6, etc., which can be one or more (including two); the binder includes but is not limited to PVDF, CMC (sodium carboxymethyl cellulose), SBR (styrene-butadiene-styrene block copolymer), PAA (polyacrylic acid), LA132 (the main component is PAA), etc., which can be one or more; the solvent includes but is not limited to NMP and pure water, which can be one or more; the dispersant model includes but is not limited to HA-02D. The dispersant components include but are not limited to N-vinyl pyrrolidone and acrylamide and styrene-based polymer block copolymer solutions, and polymers with acidic groups.

[0059] This embodiment provides a battery slurry, which is prepared by the above-mentioned method for preparing a uniform battery slurry.

[0060] Figure 3 A comparison diagram of a battery slurry obtained by the preparation method of the present invention and a slurry of the prior art is exemplified in FIG. The main material is lithium iron phosphate (LFP). It can be seen that the battery slurry obtained by the preparation method of the present invention has a higher solid content, a lower initial viscosity, and better viscosity retention.

[0061] This embodiment also provides an electrochemical energy storage device, which includes the battery slurry.

[0062] Specifically, the electrochemical energy storage device includes a lithium-ion battery.

[0063] The effects of the preparation method of a battery uniform slurry, the battery slurry and the electrochemical energy storage device of the present invention are as follows: the present invention provides a new preparation method of a battery uniform slurry by controlling the solid content of the initial wetting in step 2, controlling the solid content of the secondary wetting in step 3, controlling the stirring temperature in step 4 and controlling the amount of the dispersant added in step 6, etc. The method improves the slurry solid content and the viscosity static retention ability.

[0064] Compared with the prior art, the present invention has lower initial viscosity, improves fluidity, improves the dispersion effect of the homogenization process and the viscosity retention of the slurry in a static state, improves the efficiency and qualified rate of the subsequent coating operation, reduces energy consumption, and shortens the operation time.

[0065] The slurry of the present invention has a high solid content, which can reduce the amount of solvent used. The high solid content can improve the coating efficiency in battery preparation, reduce the energy consumption of the oven in battery preparation, and reduce the cost of battery preparation.

[0066] The slurry of the present invention has good viscosity retention, which can improve the consistency of coating surface density and increase the yield rate.

[0067] It should be noted that in the above embodiments, the description of each embodiment has its own emphasis, and for parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0068] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concept is known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a uniform battery slurry, characterized in that: include: Step 1, dry-mixing the active material powder, the first conductive agent and the binder to obtain a first mixed material; Step 2, adding a second conductive agent to the first mixed material to obtain a second mixed material, dispersing a solvent into the second mixed material, stirring the second mixed material, and obtaining a first mixed slurry with a solid content of 75wt% to 80wt%; Step 3, dispersing the second conductive agent and the solvent into the first mixed slurry, stirring to obtain a second mixed slurry, wherein the second mixed slurry has a solid content of 71wt%-85wt%; Step 4, stirring the second mixed slurry at 35-80° C.; Step 5, adding a solvent to the second mixed slurry obtained in step 4, and stirring to obtain a third mixed slurry; Step 6: Add a dispersant to the third mixed slurry and stir. The weight of the dispersant is 0.1%-1% of the dry weight of the third mixed slurry.

2. The method for preparing a uniform battery slurry according to claim 1, characterized in that: The stirring in step 6 is specifically as follows: first stirring at a revolution of 30±10RPM and a rotational speed of 25±10m / s for 30-80 minutes, and then stirring at a revolution of 20±10RPM and a rotational speed of 10±5m / s for 10-30 minutes.

3. The method for preparing a uniform slurry for lithium-ion batteries according to claim 1, characterized in that: The solid content of the third mixed slurry in step 5 is 57wt%-70wt%.

4. The method for preparing a uniform battery slurry according to claim 1, characterized in that: The weight ratio of the second conductive agent added in step 3 to the weight ratio of the second conductive agent added in step 2 is 3:7 to 7:

3.

5. The method for preparing a uniform battery slurry according to claim 1, characterized in that: The stirring speed in step 3 is 30±10 RPM for revolution, 10±5 m / s for rotation, and the stirring time is 50-110 minutes.

6. The method for preparing a uniform battery slurry according to claim 1, characterized in that: The stirring speed in step 4 is 30±10 RPM for revolution, 15±5 m / s for rotation, and the stirring time is 90-220 minutes.

7. The method for preparing a uniform battery slurry according to claim 1, characterized in that: The active material is lithium iron phosphate powder, the first conductive agent is carbon black, and the second conductive agent is carbon nanotubes.

8. A battery slurry, characterized in that: The battery slurry is prepared by the method for preparing a uniform battery slurry according to any one of claims 1 to 7.

9. An electrochemical energy storage device, characterized in that: The electrochemical energy storage device comprises the battery slurry according to claim 8.

10. The electrochemical energy storage device according to claim 9, characterized in that: The electrochemical energy storage device includes a lithium-ion battery.

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