A method for supplementing glue for lithium ion battery negative electrode slurry sinking

Abstract

The application belongs to the technical field of lithium ion batteries, and provides a lithium ion battery negative electrode slurry sinking and glue supplementing method, which is suitable for lithium ion batteries and comprises the following operation steps: S01, CMC powder is added into a solvent and uniformly stirred to obtain a solid-liquid mixture; S02, the solid-liquid mixture obtained in step S01 is added into lithium ion battery negative electrode slurry while stirring to obtain a mixed slurry; and S03, the mixed slurry in step S02 is subjected to mechanical stirring until uniform. In the application, the CMC powder is added into a solvent which is miscible with water and insoluble with CMC, so that the agglomeration of the CMC powder caused by swelling when the CMC powder directly contacts with water can be effectively reduced, and the time for fully dispersing the CMC in the slurry can be reduced. After the glue supplementing, the fineness and viscosity of the slurry can reach normal levels after sufficient stirring, and the subsequent coating process is not affected. The application is simple in operation, and has a significant effect on improving production efficiency and increasing economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and particularly relates to a method for filling and gluing lithium-ion battery negative electrode slurry. Background Technology

[0002] Lithium-ion batteries are characterized by high voltage, high specific energy, and long lifespan, and are widely used in industries such as new energy vehicles, energy storage, and portable electronic devices. The material preparation process, as a crucial step in lithium-ion battery manufacturing, directly affects coating performance and plays a vital role in electrode quality, battery quality, and consistency.

[0003] Currently, the binder system for lithium-ion battery anode slurries is mainly sodium carboxymethyl cellulose (CMC) plus styrene-butadiene rubber (SBR). CMC possesses excellent properties such as thickening, dispersing, suspending, binding, and film formation, playing a role in dispersing graphite and improving slurry viscosity and stability. However, CMC is a brittle material and easily breaks after rolling, requiring the use of flexible SBR. CMC in its liquid state has poor stability and is affected by pH, temperature, stirring speed, and stirring time, leading to structural changes, decreased binding force, and slurry sedimentation. When slurry sedimentation occurs, to avoid waste, and without affecting subsequent processes and lithium-ion battery performance, the slurry viscosity and dispersibility are improved by adding CMC (i.e., adding CMC liquid), restoring the slurry's function.

[0004] Existing glue-addition methods require the preparation of materials for the negative electrode of the battery, which is divided into dry mixing and wet mixing processes. Dry mixing requires the glue solution to be prepared separately and then added to the mixture for stirring, which is time-consuming and labor-intensive. The wet mixing process involves reserving glue solution in advance, but if there is no sedimentation and no glue addition is needed, reserving glue solution can easily lead to material waste. Furthermore, if the reserved glue solution is stored for too long, its adhesiveness and stability will also decrease. Summary of the Invention

[0005] Based on this, embodiments of the present invention provide a method for filling and adding adhesive to lithium-ion battery negative electrode slurry, which aims to solve a series of technical problems in the existing CMC adhesive filling process, such as the need to prepare the adhesive separately and the tendency for the adhesive to become unstable due to long-term storage, thereby affecting the subsequent coating process.

[0006] To achieve the above objectives, embodiments of the present invention provide a method for preparing and applying a negative electrode slurry for lithium-ion batteries, applicable to lithium-ion batteries, comprising the following steps:

[0007] S01. Add CMC powder to the solvent and stir until homogeneous to obtain a solid-liquid mixture;

[0008] S02. While stirring, add the solid-liquid mixture obtained in step S01 to the negative electrode slurry of the lithium-ion battery to obtain a mixed slurry;

[0009] S03. Mechanically stir the mixed slurry in step S02 until it is uniform.

[0010] In step S01,

[0011] In a preferred embodiment, the solvent is an aqueous solution of ethanol or a solvent that is miscible with water but immiscible with CMC.

[0012] In a preferred embodiment, the ethanol volume concentration of the aqueous ethanol solution is 5% to 99.5%. The lower the ethanol volume concentration, the more severe the swelling of CMC, the more dry powder will form inside the CMC, resulting in large solid agglomerations, making it difficult to obtain a uniform solid-liquid mixture.

[0013] In a preferred embodiment, the volume concentration of ethanol in the aqueous ethanol solution is 60% to 99%.

[0014] In a preferred embodiment, the mass ratio of the CMC powder to the ethanol-water solution is 1:(1-100). The more ethanol-water solution (ethanol), the less solids per unit volume, and the greater the dispersion (instantaneous uniform distribution) of the CMC powder.

[0015] In a preferred embodiment, the mass ratio of the CMC powder to the aqueous ethanol solution is 1:(4-49). This effectively improves the solubility of CMC, thereby forming a solid-liquid mixture (which is not a viscous liquid, but has no stickiness and is easy to stir and mix), thus ensuring the uniformity of the mixture.

[0016] In a preferred embodiment, the volume ratio of large solid agglomerates to the total volume of the solid-liquid mixture is ≤1 / 5.

[0017] In step S02,

[0018] In a preferred embodiment, the weight of the CMC powder is 0.1% to 5% of the weight of the negative electrode dry powder of the lithium-ion battery;

[0019] The stirring is done manually or by machine.

[0020] In step S03,

[0021] In a preferred embodiment, the mechanical stirring process conditions are consistent with those of the stirring process conditions of the negative electrode slurry of the lithium-ion battery before the addition of adhesive. This ensures that the performance of the slurry after adhesive addition is consistent with that of the original negative electrode slurry, thereby ensuring the consistency of the lithium-ion battery performance before and after adhesive addition. At the same time, it also facilitates instrument operation, eliminating the need to reset the rotation speed process.

[0022] The technical solution proposed in this invention has the following beneficial effects:

[0023] This application effectively solves the technical problems of inconvenient glue application in existing lithium-ion battery negative electrode slurry, such as the need for separate glue preparation, material waste due to pre-reserved glue, and the impact of glue adhesion and stability caused by excessive storage time. This application addresses these issues by adding CMC powder to a solvent miscible with water but immiscible with CMC, stirring, and then adding it to the slurry. After stirring for a period of time according to the specific battery negative electrode stirring process, the slurry properties are restored. This reduces the overall material preparation and stirring time without the need for separate glue preparation. Furthermore, this application effectively reduces the large agglomeration caused by the expansion of CMC powder upon direct contact with water, and reduces the time required for CMC to fully disperse in the slurry. After thorough stirring, the fineness and viscosity of the glued slurry reach normal levels, without affecting subsequent coating processes, which is of great significance for improving production efficiency and increasing economic benefits. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.

[0025] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, top, bottom, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0026] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0027] It should be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0028] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0029] Currently, the binder system for lithium-ion battery anode slurries is mainly sodium carboxymethyl cellulose (CMC) plus styrene-butadiene rubber (SBR). CMC possesses excellent properties such as thickening, dispersing, suspending, binding, and film formation, playing a role in dispersing graphite, increasing slurry viscosity, and preventing sedimentation. However, CMC in solution has poor stability and is affected by pH, temperature, stirring speed, and stirring time, leading to structural changes, decreased binding force, and slurry sedimentation. When slurry sedimentation occurs, to avoid waste, binder is added to improve slurry viscosity and dispersibility, restoring its function without affecting subsequent processes and lithium-ion battery performance. However, current binder addition processes have the following drawbacks: dry mixing processes require separate preparation of the binder solution before adding and stirring, which is time-consuming and labor-intensive; wet mixing processes reserve binder solution in advance, but the absence of sedimentation leads to material waste, and prolonged storage of the binder solution can affect adhesiveness and stability. To solve the above technical problems, this invention proposes a binder addition method for lithium-ion battery anode slurries.

[0030] Example 1

[0031] The lithium-ion battery negative electrode slurry in this embodiment is a negative electrode slurry that exhibits sedimentation after being dispersed for 0.5 hours at 25°C, 30 revolutions per minute, and 1500 rotations per minute.

[0032] A method for preparing and bonding a negative electrode slurry for lithium-ion batteries, applicable to lithium-ion batteries, includes the following steps:

[0033] S01. Add CMC powder to an ethanol aqueous solution with a volume concentration of 95%, wherein the mass ratio of CMC powder to ethanol aqueous solution is 1:4, and stir evenly to obtain a solid-liquid mixture.

[0034] S02. While stirring, add the solid-liquid mixture obtained in step S01 to the lithium-ion battery negative electrode slurry to obtain a mixed slurry.

[0035] S03. Stir the mixed slurry obtained in step S02 at 25°C, with an orbital speed of 30 rpm and a rotational speed of 1500 rpm for 1.5 hours.

[0036] In the solid-liquid mixture obtained in this embodiment, the CMC powder is relatively uniformly dispersed with almost no large agglomerates, and the stirring time required after adding the solid-liquid mixture to the negative electrode slurry is relatively short.

[0037] Example 2

[0038] The lithium-ion battery negative electrode slurry in this embodiment is a negative electrode slurry that exhibits sedimentation after being dispersed for 1 hour at 30°C, 40 revolutions per minute, and 4000 rotations per minute.

[0039] A method for preparing and bonding a negative electrode slurry for lithium-ion batteries, applicable to lithium-ion batteries, includes the following steps:

[0040] S01. Add CMC powder to an ethanol aqueous solution with a volume concentration of 99%, wherein the mass ratio of CMC powder to ethanol aqueous solution is 1:49, and stir evenly to obtain a solid-liquid mixture.

[0041] S02. While stirring, add the solid-liquid mixture obtained in step S01 to the lithium-ion battery negative electrode slurry to obtain a mixed slurry.

[0042] S03. Stir the mixed slurry obtained in step S02 at 30°C, 40 revolutions / min, and 4000 revolutions / min for 1 hour.

[0043] In the solid-liquid mixture obtained in this embodiment, the CMC powder is extremely uniformly dispersed with almost no large agglomerates, and the stirring time required after adding the negative electrode slurry to the solid-liquid mixture is relatively short.

[0044] Example 3

[0045] The lithium-ion battery negative electrode slurry in this embodiment is a negative electrode slurry that exhibits sedimentation after being dispersed for 0.5 hours at 25°C, 30 revolutions per minute, and 1500 rotations per minute.

[0046] A method for preparing and bonding a negative electrode slurry for lithium-ion batteries, applicable to lithium-ion batteries, includes the following steps:

[0047] S01. Add CMC powder to an ethanol aqueous solution with a volume concentration of 97%, wherein the mass ratio of CMC powder to ethanol aqueous solution is 1:23, and stir evenly to obtain a solid-liquid mixture.

[0048] S02. While stirring, add the solid-liquid mixture obtained in step S01 to the lithium-ion battery negative electrode slurry to obtain a mixed slurry.

[0049] S03. Stir the mixed slurry obtained in step S02 at 25°C, with an orbital speed of 30 rpm and a rotational speed of 1500 rpm for 1.5 hours.

[0050] In the solid-liquid mixture obtained in this embodiment, the CMC powder is extremely uniformly dispersed with almost no large agglomerates, and the stirring time required after adding the negative electrode slurry to the solid-liquid mixture is relatively short.

[0051] Comparative Example 1

[0052] The lithium-ion battery negative electrode slurry in this embodiment is a negative electrode slurry that exhibits sedimentation after being dispersed for 0.5 hours at 25°C, 30 revolutions per minute, and 1500 rotations per minute.

[0053] A method for preparing and applying a binder to a lithium-ion battery negative electrode slurry includes the following steps:

[0054] S01. Add CMC powder to deionized water at a mass ratio of 1:4, stir until homogeneous, and obtain the adhesive solution.

[0055] S02. While stirring, add the adhesive solution obtained in step S01 to the lithium-ion battery negative electrode slurry to obtain a mixed slurry.

[0056] S03. Stir the mixed slurry obtained in step S02 at 25°C, with an orbital speed of 30 rpm and a rotational speed of 1500 rpm for 1.5 hours.

[0057] Compared with Example 1, in this comparative example, the 95% ethanol aqueous solution was replaced with deionized water, while the other operating conditions remained unchanged. Instead of a solid-liquid mixture, a gel block was obtained. This gel block contained a large number of solid agglomerates, and the proportion of large solid agglomerates to the total solution volume was far greater than 1 / 5. At the same time, after adding the gel solution to the negative electrode slurry and operating under the conditions of Example 1, a uniform state could not be achieved. A longer stirring time (about 2-3 hours) was required to achieve uniformity, which was more time-consuming than Example 1.

[0058] This application effectively solves the technical problems of inconvenient glue application in existing lithium-ion battery negative electrode slurry, such as the need for separate glue preparation, material waste due to pre-reserved glue, and the impact of glue adhesion and stability on the adhesive properties caused by excessive storage time. This application addresses these issues by adding CMC powder to a solvent miscible with water but immiscible with CMC, stirring, and then adding it to the negative electrode slurry. After stirring for a period of time according to the specific battery negative electrode stirring process, the slurry properties are restored. This reduces the overall material preparation and stirring time without the need for separate glue preparation. Furthermore, this application effectively reduces the large agglomeration caused by the expansion of CMC powder upon direct contact with water, and reduces the time required for CMC to fully disperse in the slurry. After thorough stirring, the fineness and viscosity of the glued slurry reach normal levels, without affecting subsequent coating processes, which is of great significance for improving production efficiency and increasing economic benefits.

[0059] In the description of this specification, references to terms such as "an embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0060] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing and applying a slurry to the negative electrode of a lithium-ion battery, characterized in that, Applicable to lithium-ion batteries, including the following operating steps: S01. Add CMC powder to the solvent and stir until homogeneous to obtain a solid-liquid mixture; S02. While stirring, add the solid-liquid mixture obtained in step S01 to the negative electrode slurry of the lithium-ion battery to obtain a mixed slurry; S03. Mechanically stir the mixed slurry in step S02 until it is uniform; In step S01, the solvent is a solvent that is miscible with water and immiscible with CMC; the solvent that is miscible with water and immiscible with CMC is an aqueous ethanol solution. In step S01, the mass ratio of the CMC powder to the ethanol aqueous solution is 1:(1-100).

2. The method for settling and bonding lithium-ion battery negative electrode slurry as described in claim 1, characterized in that, The volume concentration of ethanol in the aqueous ethanol solution is 5% to 99.5%.

3. The method for settling and bonding lithium-ion battery negative electrode slurry as described in claim 1, characterized in that, The volume concentration of ethanol in the aqueous ethanol solution is 60% to 99%.

4. The method for settling and bonding lithium-ion battery negative electrode slurry as described in claim 1, characterized in that, In step S01, the mass ratio of the CMC powder to the ethanol aqueous solution is 1:(4-49).

5. The method for settling and bonding lithium-ion battery negative electrode slurry as described in claim 1, characterized in that, In step S01, the volume ratio of large solid agglomerates to the total volume of the solid-liquid mixture is ≤1 / 5.

6. The method for settling and bonding lithium-ion battery negative electrode slurry as described in claim 1, characterized in that, In step S02, the stirring is done manually or by machine.

7. The method for settling and bonding lithium-ion battery negative electrode slurry as described in claim 1, characterized in that, The weight of the CMC powder is 0.1% to 5% of the weight of the negative electrode dry powder of the lithium-ion battery.

8. The method for settling and bonding lithium-ion battery negative electrode slurry as described in claim 1, characterized in that, In step S03, the mechanical stirring process conditions are the same as those for the stirring process of the lithium-ion battery negative electrode slurry before the addition of adhesive.