Lithium battery pole piece infiltration method, lithium battery pole piece and lithium battery

Abstract

The invention discloses an infiltration method of a lithium battery pole piece, the lithium battery pole piece and a lithium battery, the infiltration method of the lithium battery pole piece comprises the following steps: S1, providing an infiltration agent solution: mixing an infiltration agent main material and an additive according to a mass part ratio of 7: 1-9: 1 to obtain the infiltration agent solution; s2, providing a positive electrode plate: coating, cutting and drying the positive electrode slurry to obtain the positive electrode plate, wherein a functional nano material is added into the positive electrode slurry; the addition amount of the functional nano material is 0.4%-0.6% of the total mass of the dry powder in the positive electrode slurry in percentage by mass; and S3, infiltration: infiltrating the positive pole piece obtained in the step S2 into the impregnating compound solution obtained in the step S1. According to the infiltrating method of the lithium battery pole piece, the infiltrating effect is uniform and rapid, and the performance of a lithium battery is improved; the lithium battery prepared from the lithium battery pole piece obtained by the infiltration method has higher energy density and longer cycle life.

Description

Technical Field

[0001] The present invention relates to the technical field of surface treatment methods for pole pieces, and in particular to an infiltration method for a lithium battery pole piece, a lithium battery pole piece and a lithium battery. Background Art

[0002] Lithium batteries have been widely used in electronic products such as electric vehicles and smart phones due to their high energy density, long cycle life and environmental protection. However, in the manufacturing process of lithium batteries, the wetting effect of the electrode interface directly affects the performance of the battery. At present, the traditional wetting method has problems such as uneven wetting and long wetting time, which leads to the decline of battery performance. In the prior art, the methods for improving the wetting effect of the interface of lithium battery pole pieces mainly include physical methods and chemical methods. The physical method mainly enhances the wetting effect by increasing the wetting temperature and pressure, or using physical means such as ultrasound. However, the physical method has the defects of high energy consumption, complex equipment and high cost; the chemical method improves the wetting effect by adding chemical additives such as surfactants, and the chemical method may introduce new impurities, affecting the performance and safety of the battery.

[0003] Therefore, it is very necessary to provide a lithium battery pole piece wetting method, a lithium battery pole piece and a lithium battery that can improve the interface wetting effect of the lithium battery pole piece and improve the performance of the lithium battery. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and provide a lithium battery pole piece impregnation method, a lithium battery pole piece and a lithium battery. The battery pole piece impregnation method can improve the impregnation performance of the battery pole piece, improve the impregnation efficiency and thus improve the performance of the lithium ion battery.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for wetting a lithium battery pole piece, comprising the steps of:

[0007] S1. Providing a wetting agent solution: mixing a main wetting agent material and an additive in a mass ratio of 7:1-9:1 to obtain a wetting agent solution; the additive comprises a surfactant and a dispersant, and the mass ratio of the surfactant to the dispersant is 3:1-5:1;

[0008] S2. Providing a positive electrode sheet: coating, cutting and drying the positive electrode slurry to obtain a positive electrode sheet, wherein the positive electrode slurry is added with a functional nanomaterial; in terms of mass percentage, the amount of the functional nanomaterial added is 0.4%-0.6% of the total mass of the dry powder in the positive electrode slurry;

[0009] S3, soaking: soaking the positive electrode sheet obtained in step S2 in the soaking agent solution obtained in step S1.

[0010] Optionally, the main ingredients of the wetting agent include lithium salt and solvent, wherein the lithium salt accounts for 11%-13% by mass.

[0011] Optionally, the functional nanomaterial includes one of aluminum oxide, graphene or carbon nanotubes.

[0012] Optionally, in step S3, the soaking temperature is 70-80° C., and the soaking time is 10-20 min.

[0013] Optionally, a pressure pulse is applied during the infiltration process in step S3.

[0014] Optionally, the immersion in step S3 is carried out in a closed container, and the applying of the pressure pulse includes the steps of: increasing the pressure in the container to a pressure setting value, maintaining the pressure at the pressure setting value for a first time, reducing the pressure, and increasing the pressure to the pressure setting value again, performing multiple cycles with reducing the pressure and increasing the pressure again as one cycle, and maintaining the pressure at the pressure setting value for a second time after the last cycle; the pressure setting value is 200kpa-500kpa.

[0015] Optionally, the surfactant includes one or more of sodium lauryl sulfate, sodium polyoxyethylene fatty alcohol ether sulfate, polyethylene glycol octylphenyl ether or polyoxyethylene sorbitan monolaurate.

[0016] Optionally, the dispersant includes one or more of sodium silicate, phosphate, sodium polyacrylate or polyvinyl pyrrolidone.

[0017] In a second aspect, the present invention provides a lithium battery pole piece, wherein the lithium battery pole piece is obtained by impregnation using the lithium battery pole piece impregnation method as described above.

[0018] In a third aspect, the present invention provides a lithium battery, comprising the lithium battery pole piece as described above.

[0019] The beneficial effects produced by the present invention include at least:

[0020] The infiltration method of the lithium battery pole piece described in the present invention improves the physical contact of the lithium battery pole piece interface, reduces the interface resistance, and improves the cycle performance and safety of the battery by adding the functional nanomaterial during the preparation process of the positive electrode pole piece; the additive in the infiltration agent solution is used for the wettability and dispersibility of the infiltration agent solution; the infiltration effect is uniform and rapid, and the performance of the lithium battery is improved; the lithium battery prepared by the lithium battery pole piece obtained by the infiltration method of the present invention has higher energy density and longer cycle life, and is suitable for electronic products such as electric vehicles and smart phones. DETAILED DESCRIPTION

[0021] For ease of understanding of the present invention, preferred embodiments of the present invention are provided below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in the present invention. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0022] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0023] In the present invention, descriptions such as “first”, “second”, etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0024] The raw materials used in the present invention can be obtained from suppliers known in the art, or prepared by known methods.

[0025] In a first aspect, the present invention provides a method for wetting a lithium battery pole piece, comprising the steps of:

[0026] S1. Providing a wetting agent solution: mixing a main ingredient of the wetting agent with an additive in a mass ratio of 7:1-9:1 to obtain a wetting agent solution; the additive includes a surfactant and a dispersant, and the mass ratio of the surfactant to the dispersant is 3:1-5:1; specifically, the ratio of the amount of the wetting agent to the additive can be 7:1, 8:1 or 9:1. Specifically, the mass ratio of the surfactant to the dispersant can be 3:1, 4:1 or 5:1.

[0027] S2. Providing positive electrode sheets: coating, cutting and drying the positive electrode slurry to obtain positive electrode sheets, wherein the positive electrode slurry is added with functional nanomaterials; in terms of mass percentage, the amount of the functional nanomaterials added is 0.4%-0.6% of the total mass of the dry powder in the positive electrode slurry. Specifically, the amount of the functional nanomaterials added is 0.4%, 0.5% or 0.6% of the total mass of the dry powder in the positive electrode slurry.

[0028] S3, soaking: soaking the positive electrode sheet obtained in step S2 in the soaking agent solution obtained in step S1.

[0029] The infiltration method of the lithium battery pole piece described in the present invention improves the physical contact of the lithium battery pole piece interface, reduces the interface resistance, and improves the cycle performance and safety of the battery by adding the functional nanomaterial during the preparation process of the positive electrode pole piece; the additive in the infiltration agent solution is used for the wettability and dispersibility of the infiltration agent solution; the infiltration effect is uniform and rapid, and the performance of the lithium battery is improved; the lithium battery prepared by the lithium battery pole piece obtained by the infiltration method of the present invention has higher energy density and longer cycle life, and is suitable for electronic products such as electric vehicles and smart phones.

[0030] In step S2, during the preparation of the positive electrode sheet, the drying temperature is 95-100°C to obtain a positive electrode sheet with a smooth surface and no dust.

[0031] Optionally, in order to further remove impurities and oil stains on the surface of the positive electrode plate, ultrasonic cleaning may be used to clean the obtained positive electrode plate.

[0032] Optionally, the main material of the infiltrant includes a lithium salt and a solvent, wherein the lithium salt accounts for 11%-13% by mass. The lithium salt includes one or both of lithium hexafluorophosphate (LiPF6) or lithium tetrafluoroborate (LiBF4); the solvent includes cyclic and chain carbonate solvents, specifically including one or more of ethylene carbonate (EC), dimethyl carbonate (DMC) or diethyl carbonate (DEC).

[0033] Optionally, the functional nanomaterial includes one of aluminum oxide, graphene or carbon nanotubes; the functional nanomaterial mainly plays the role of conductivity enhancement, structural support or interface modification in the preparation of lithium battery pole pieces; the functional nanomaterial has excellent electrical, mechanical or chemical properties and can significantly improve the performance of battery materials. The addition of the functional nanomaterial improves the physical contact of the pole piece interface, reduces the interface impedance, and thus improves the wetting effect.

[0034] Optionally, in step S3, the infiltration temperature is 70-80°C, and the infiltration time is 10-20min. Under the infiltration conditions of the present invention, the positive electrode plate can be quickly and fully infiltrated while taking into account both production cost and battery performance. If the infiltration temperature is too low, the penetration rate of the wetting agent is slow, which may lead to insufficient infiltration; if the infiltration temperature is too high, the crystal structure of the positive electrode material may be destroyed, affecting battery performance; at the same time, too high a temperature may also cause the wetting agent to decompose or volatilize, reducing the wetting effect. If the infiltration time is too short, the wetting agent fails to fully penetrate into the interior of the positive electrode material, resulting in poor infiltration effect; if the infiltration time is too long, it may increase production costs, and in some cases, it may also cause the wetting agent to form an excessively thick coating on the surface of the positive electrode material, affecting battery performance.

[0035] Furthermore, during the wetting process of step S3, a pressure pulse is applied to further improve the wetting effect. The operation mode of applying a pressure pulse helps to break the interfacial tension between the wetting agent and the positive electrode sheet, and accelerates the diffusion and penetration speed of the wetting agent.

[0036] Specifically, the infiltration in step S3 is carried out in a closed container, and the application of pressure pulses includes the steps of: increasing the pressure in the container to a pressure setting value, maintaining the pressure setting value for a first time, reducing the pressure, and increasing the pressure to the pressure setting value again, performing multiple cycles with reducing the pressure and increasing the pressure again as one cycle, and maintaining the pressure setting value for a second time after the last cycle; the pressure setting value is 200kpa-500kpa. It can be understood that the first time, the number of cycles of the pressure increase cycle after decompression, and the value of the second time can be specifically set according to actual conditions; for example, the first time is 5-10min, and the number of cycles of reducing the pressure and increasing the pressure again can be 2-5 times. If the pressure setting value is too low, the penetration speed of the infiltrant is slow, which may lead to insufficient infiltration; if the pressure is too high, the structure of the positive electrode material may be destroyed, resulting in performance degradation, and excessive pressure may also cause safety problems. During the infiltration process, a pressure pulse is applied, and the pressure is first increased to the pressure setting value, and the pressure is maintained at the pressure setting value for a first time, so that the infiltrant begins to penetrate into the interior of the positive electrode material under the action of pressure; then, the pressure is reduced, and pores or channel structures are formed during the decompression process. After the pressure is increased to the pressure setting value again, the infiltrant can penetrate into the interior of the positive electrode sheet along the formed pores or channel structures, thereby improving the penetration effect. After multiple cycles of increasing and reducing the pressure, the pressure setting value is maintained for a second time to further ensure that the infiltrant can fully penetrate into the interior of the positive electrode sheet.

[0037] Optionally, the surfactant includes one or more of sodium dodecyl sulfate (SDS), sodium polyoxyethylene alcohol ether sulfate (AES), polyethylene glycol octylphenyl ether (Tr iton X-100) or polyoxyethylene sorbitan monolaurate (Tween 20).

[0038] Optionally, the dispersant includes one or more of sodium silicate, phosphate, sodium polyacrylate or polyvinyl pyrrolidone (PVP).

[0039] In a second aspect, the present invention provides a lithium battery pole piece, wherein the lithium battery pole piece is obtained by infiltration using the lithium battery pole piece infiltration method as described above.

[0040] In a third aspect, the present invention provides a lithium battery, comprising the lithium battery pole piece as described above.

[0041] The preparation of the lithium battery comprises the following steps: drying the lithium battery pole piece obtained by the lithium battery pole piece impregnation method described above to remove the excess modified impregnant; then assembling the obtained lithium battery pole piece with the negative pole piece, the separator, etc. into a battery cell, and packaging the battery cell. The drying temperature is 90°C-100°C and the drying time is 1h-2h.

[0042] The lithium battery pole piece obtained by the impregnation method with functional nanomaterials added in the present invention is assembled into a 50Ah battery cell, and a performance comparison test is conducted with a 50Ah battery cell assembled from a lithium battery pole piece without functional nanomaterials added in the prior art. The performance comparison test data is shown in Table 1. It should be noted that the difference between the battery cell made from the pole piece obtained by the impregnation method of the present invention and the battery cell made from the pole piece in the prior art is whether functional nanomaterials are added; the values ​​of the relevant performance tests of the battery cell made from the pole piece obtained by the impregnation method of the present invention in Table 1 are the average values ​​of the performance tests of the battery cell made by the technical solution of the present invention.

[0043] In Table 1, the battery ACR test refers to the battery capacity test, that is, to detect whether the actual capacity of the battery meets the nominal capacity; the battery cell DCR refers to the battery cell DC resistance test. As can be seen from Table 1, the performance of the battery cell made of the pole piece treated by the infiltration method of the present invention is better than the performance of the battery cell made of the pole piece in the prior art. This shows that the infiltration method of the lithium battery pole piece in the present invention improves the infiltration effect of the battery pole piece, thereby improving the performance of the lithium battery finally obtained.

[0044] Table 1 Battery performance test data test comparison table

[0045]

[0046] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0047] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those skilled in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for wetting a lithium battery pole piece, characterized in that: Includes steps: S1. Providing a wetting agent solution: mixing a main wetting agent material and an additive in a mass ratio of 7:1-9:1 to obtain a wetting agent solution; the additive comprises a surfactant and a dispersant, and the mass ratio of the surfactant to the dispersant is 3:1-5:1; S2. Providing a positive electrode sheet: coating, cutting and drying the positive electrode slurry to obtain a positive electrode sheet, wherein the positive electrode slurry is added with a functional nanomaterial; in terms of mass percentage, the amount of the functional nanomaterial added is 0.4%-0.6% of the total mass of the dry powder in the positive electrode slurry; S3, soaking: soaking the positive electrode sheet obtained in step S2 in the soaking agent solution obtained in step S1.

2. The method for wetting a lithium battery pole piece according to claim 1, characterized in that: The main ingredients of the wetting agent include lithium salt and solvent, wherein the lithium salt accounts for 11%-13% by mass.

3. The method for wetting a lithium battery pole piece according to claim 1, characterized in that: The functional nanomaterial includes one of aluminum oxide, graphene or carbon nanotube.

4. The method for wetting a lithium battery pole piece according to claim 1, characterized in that: In step S3, the soaking temperature is 70-80°C and the soaking time is 10-20 minutes.

5. The method for wetting a lithium battery pole piece according to claim 1, characterized in that: During the infiltration process in step S3, a pressure pulse is applied.

6. The method for impregnating a lithium battery pole piece according to claim 5, characterized in that: The immersion in step S3 is carried out in a closed container, and the applying of pressure pulses includes the steps of: increasing the pressure in the container to a pressure setting value, maintaining the pressure at the pressure setting value for a first time, reducing the pressure, and increasing the pressure to the pressure setting value again, performing multiple cycles with reducing the pressure and increasing the pressure again as one cycle, and maintaining the pressure at the pressure setting value for a second time after the last cycle; the pressure setting value is 200kpa-500kpa.

7. The method for impregnating a lithium battery pole piece according to claim 1, characterized in that: The surfactant includes one or more of sodium lauryl sulfate, sodium polyoxyethylene fatty alcohol ether sulfate, polyethylene glycol octylphenyl ether or polyoxyethylene sorbitan monolaurate.

8. The lithium battery pole piece impregnation method according to claim 1, characterized in that: The dispersant includes one or more of sodium silicate, phosphate, sodium polyacrylate or polyvinyl pyrrolidone.

9. A lithium battery pole piece, characterized in that: The lithium battery pole piece is obtained by infiltrating using the lithium battery pole piece infiltrating method as described in any one of claims 1 to 8.

10. A lithium battery, characterized in that: Including the lithium battery pole piece as described in claim 9.

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