Multifunctional conductive agent and preparation method and application thereof

Abstract

The invention relates to the field of batteries, in particular to a multifunctional conductive agent and a preparation method and application thereof. In the aspect of a three-dimensional structure, mesoporous alumina takes a three-dimensional communicated pore channel network as a skeleton and is uniformly embedded between metal organic framework materials to form a space interpenetrating conductive ion-conductive electron dual-channel system. Mesoporous alumina is used as a rigid framework, displacement and agglomeration of the metal organic framework material are effectively inhibited, through pore channels of the mesoporous alumina and a microporous structure of the metal organic framework material form multistage pore size distribution, the wettability of an electrolyte is improved, and the interface impedance is reduced. The metal organic framework material is rich in nitrogen functional groups, so that a lithium ion diffusion energy barrier in the electrolyte can be reduced, and the transmission rate of lithium ions is increased. The chemical inertness of mesoporous alumina can inhibit the side reaction between the surface of the negative electrode and an electrolyte, promote the uniform embedding of lithium, and reduce the formation of lithium dendrites.

Description

Technical Field

[0001] This invention relates to the field of batteries, and more particularly to a multifunctional conductive agent, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries, as outstanding representatives of modern electrochemical energy storage, have revolutionized the traditional model of energy storage and use. Based on the reversible insertion and extraction of lithium ions between the positive and negative electrodes, they achieve the conversion of chemical energy into electrical energy. They possess significant performance advantages, including high energy density, low self-discharge rate, no memory effect, and long cycle life, and are widely used in electric vehicles, laptops, energy storage products, and other fields. A lithium-ion battery consists of positive and negative electrodes, a separator, and an electrolyte.

[0003] Currently, common conductive agents for lithium-ion batteries mainly consist of conductive carbon black and carbon nanotubes. However, conductive carbon black and carbon nanotubes have several shortcomings as commonly used conductive agents. Conductive carbon black, due to its large specific surface area and high surface energy, is prone to agglomeration in electrode slurries, exhibiting poor dispersibility. Furthermore, its strong oil absorption leads to the adsorption of large amounts of binders and solvents, interfering with the synergistic effect between the conductive agent, active material, and binder. Its granular structure relies on point contact for conductivity, resulting in low efficiency and difficulty meeting the demands of high-power batteries. Carbon nanotubes, on the other hand, have complex preparation processes and high raw material costs, increasing battery costs on a large scale. Their small diameter and large aspect ratio make them prone to entanglement and agglomeration due to van der Waals forces and π-π stacking effects, resulting in difficult dispersion and poor stability. In addition, their surface properties are not well-matched with other materials in the electrode system, leading to interfacial compatibility issues. During cycling, agglomerates may damage the electrode structure, accelerating battery capacity decay. Therefore, designing a conductive agent with high efficiency and good dispersibility is essential. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a multifunctional conductive agent, its preparation method, and its applications.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of this invention is to provide a method for preparing a multifunctional conductive agent, comprising the steps of:

[0007] S1. Add polyvinylpyrrolidone to the mesoporous alumina solution, stir to disperse, then add metal-organic framework material and stir evenly to obtain metal-organic framework / mesoporous alumina material.

[0008] S2. The metal-organic framework / mesoporous alumina material is sintered and cooled to obtain the precursor material.

[0009] S3. The precursor material is subjected to ultrasonic washing and drying treatment in sequence to obtain the conductive agent.

[0010] Preferably, in step S1, the mass ratio of polyvinylpyrrolidone, mesoporous alumina and metal organic framework material is (2-3):(0.05-0.1):1.

[0011] Preferably, in step S1, the metal organic framework material is ZIF-8.

[0012] More preferably, the preparation step of the metal organic framework material comprises: mixing a zinc acetate solution and a 2-methylimidazole solution, centrifuging and drying after standing for 5h of reaction, to obtain the metal organic framework material.

[0013] More preferably, the mass ratio of the zinc acetate solution and the 2-methylimidazole solution is (0.5-1):2.

[0014] Preferably, in step S2, the sintering treatment comprises: first low-temperature sintering at 250-300℃ for 1h, and then sintering at 900-950℃ for 3h with a temperature rising rate of 4-6℃ / min.

[0015] More preferably, the sintering treatment further comprises: using nitrogen as a protective atmosphere.

[0016] Preferably, in step S3, the washing liquid of the ultrasonic washing treatment is hydrochloric acid.

[0017] The second aspect of the present application provides a multifunctional conductive agent prepared by the above preparation method, comprising: a metal organic framework material and mesoporous alumina embedded between the metal organic framework material.

[0018] The third aspect of the present application provides a multifunctional conductive agent prepared by the above preparation method or the use of the above multifunctional conductive agent in a battery conductive agent slurry, the battery conductive agent slurry comprising: graphite, a multifunctional conductive agent and styrene-butadiene rubber; wherein the mass ratio of graphite, the multifunctional conductive agent and the styrene-butadiene rubber is (90-95):(2.5-5):(2.5-5).

[0019] Compared with the prior art, the present application has the following technical effects:

[0020] The present application constructs a unique continuous three-dimensional conductive network by topological interpenetration of mesoporous alumina and metal organic framework materials, which significantly improves the charge transport efficiency and structural stability of lithium ion batteries. In terms of three-dimensional structure, mesoporous alumina with its three-dimensional interconnected channel network as the skeleton is uniformly embedded between metal organic framework materials, forming a space interpenetrated ion-conducting and electron-conducting dual-channel system. Mesoporous alumina as a rigid skeleton effectively suppresses the displacement and agglomeration of metal organic framework materials, and its through channels and the microporous structure of metal organic framework materials form a multi-level pore size distribution, which improves the wettability of electrolyte and reduces the interface impedance. Secondly, metal organic framework materials are rich in nitrogen functional groups, which can reduce the lithium ion diffusion energy barrier in the electrolyte and improve the transmission rate of lithium ions. The chemical inertness of mesoporous alumina can inhibit the side reaction of the negative electrode surface and the electrolyte, promote the uniform intercalation of lithium, and reduce the formation of lithium dendrites. In addition, the structural stability of mesoporous alumina ensures the stability of the battery performance in the charge and discharge cycle. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The structural design diagram of the multifunctional conductive agent in an embodiment of the present application is shown in the figure.

[0022] Figure 2 The charge and discharge curve is shown in the figure. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0024] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0025] The present application will be further described below with reference to the drawings and specific embodiments, but is not limited by the present application.

[0026] Embodiment 1

[0027] The present embodiment provides a preparation method of a battery conductive agent slurry, comprising the following steps:

[0028] 0.5g of zinc acetate and 2g of 2-methylimidazole were dissolved in 5mL of aqueous solution, respectively, and then the zinc acetate was poured into the 2-methylimidazole solution, and after standing for 5h, it was centrifuged and dried several times to obtain ZIF-8.

[0029] Take 0.05 g of mesoporous alumina in 20 mL of water, add 2 g of polyvinylpyrrolidone (PVP) and stir to disperse, then add 10 mL of a solution containing 1 g of ZIF-8 to the mesoporous alumina solution and stir to form a ZIF-8 / mesoporous alumina material.

[0030] The ZIF-8 / mesoporous alumina material is then placed in a tube furnace with nitrogen flowing through it, first sintered at a low temperature of 300°C for 1 h, then sintered at a temperature of 900°C at a heating rate of 5°C / min for 3 h, and then collected as the furnace cools to obtain a precursor material.

[0031] The precursor is ultrasonically treated in hydrochloric acid, repeatedly washed and dried to obtain a multifunctional conductive agent.

[0032] Graphite, multifunctional conductive agent and styrene-butadiene rubber (SBR) are mixed in a ratio of 95:2.5:2.5 to form a slurry, and a battery conductive agent slurry is obtained.

[0033] Example 2

[0034] This example provides another method for preparing a battery conductive agent slurry, the amount of mesoporous alumina added is 0.1 g, and the rest is the same as in Example 1.

[0035] Comparative Example 1

[0036] This comparative example provides another method for preparing a battery conductive agent slurry, graphite, conductive carbon black (SP) and SBR are mixed in a ratio of 95:2.5:2.5 to form a slurry, and a battery conductive agent slurry is obtained.

[0037] Test Example

[0038] The battery conductive agent slurries of Examples 1-2 and Comparative Example 1 are coated on a copper foil, and the film is dried in a vacuum drying oven at 100°C for 2 h. The electrode film is punched into a circular sheet with a radius of 0.7 mm using a sheet puncher, and a CR2032 type button cell is assembled in a glove box using lithium metal as the counter electrode, 1 mol / L LiPF6 EC+DEC (1:1 vol%) as the electrolyte, and a PP separator. The battery is tested for charge and discharge on a Neware tester, and the test is performed at an ambient temperature of 25±3°C, with a test voltage range of 2-0.001 V and a current rate of 0.5C. The test results are shown in Table 1.

[0039] Table 1

[0040] 0.1 C activation capacity First cycle charge-discharge efficiency Capacity retention after 200 cycles Example 1 354 97％ 96％ Example 2 350 96.5％ 93％ Comparative Example 1 348 95.9％ 89％

[0041] From the results of Table 1, it can be seen that, compared with the comparative examples, the examples have better higher capacity, first circle charge-discharge efficiency, capacity retention rate, which is due to the structural advantages of the ZIF / mesoporous aluminum three-dimensional porous conductive material of the ZIF / mesoporous aluminum multifunctional conductive agent slurry, which can enable efficient transmission of electrons and ions, thereby enabling the battery to have good cycle stability.

[0042] The above description is merely preferred embodiments of the present application, and is not intended to limit the embodiments and protection scope of the present application. It should be noted that, for those skilled in the art, any equivalent replacements and obvious changes made according to the content of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a multifunctional conductive agent, characterized in that the steps include... include: S1. Add polyvinylpyrrolidone to the mesoporous alumina solution, stir to disperse, then add metal-organic framework material and stir evenly to obtain metal-organic framework / mesoporous alumina material. S2. The metal-organic framework / mesoporous alumina material is sintered and cooled to obtain the precursor material. S3. The precursor material is subjected to ultrasonic washing and drying treatment in sequence to obtain the conductive agent.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of polyvinylpyrrolidone, mesoporous alumina and metal-organic framework material is (2-3):(0.05-0.1):

1.

3. The preparation method according to claim 1, characterized in that, In step S1, the metal-organic framework material is ZIF-8.

4. The preparation method according to claim 3, characterized in that, The preparation steps of metal-organic framework materials include: mixing zinc acetate solution with 2-methylimidazole solution, allowing the mixture to stand for 5 hours, and then centrifuging and drying to obtain the metal-organic framework material.

5. The preparation method according to claim 4, characterized in that, The mass ratio of zinc acetate solution to 2-methylimidazole solution is (0.5-1):

2.

6. The preparation method according to claim 1, characterized in that, In step S2, the sintering process includes: first sintering at a low temperature of 250-300℃ for 1 hour, and then sintering at a heating rate of 4-6℃ / min to 900-950℃ for 3 hours.

7. The preparation method according to claim 6, characterized in that, The sintering process also includes using nitrogen as a protective atmosphere.

8. The preparation method according to claim 1, characterized in that, In step S3, the washing solution used in the ultrasonic washing process is hydrochloric acid.

9. A multifunctional conductive agent prepared by the preparation method according to any one of claims 1-8, characterized in that, include: Metal-organic framework materials and mesoporous alumina embedded between metal-organic framework materials.

10. The application of a multifunctional conductive agent prepared by the preparation method according to any one of claims 1-8, or the multifunctional conductive agent according to claim 9, in a battery conductive agent slurry, characterized in that, The battery conductive agent slurry includes: graphite, multifunctional conductive agent and styrene-butadiene rubber; wherein the mass ratio of graphite, multifunctional conductive agent and styrene-butadiene rubber is (90-95):(2.5-5):(2.5-5).

Images