Three-dimensional electrode and preparation method and application thereof

Abstract

The application discloses a three-dimensional electrode and a preparation method and application thereof, and the method comprises the following steps: mixing a swelling material with an aqueous slurry solution to obtain a mixed slurry; mixing the mixed slurry with an electrode active material, grinding to obtain a coating liquid; coating the coating liquid on a current collector, drying, cutting to obtain a three-dimensional electrode. Thus, the method of the application does not need to use a binder, and the method has the advantages of simple operation and low production cost, and can be used for industrial large-scale production. In addition, the three-dimensional electrode prepared by the method has high energy density, high conductivity and high mechanical strength.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of materials, and particularly relates to a three-dimensional electrode and a preparation method and application thereof. BACKGROUND

[0002] With the increasing popularity of smart grids and electric vehicles, people's requirements for high energy density and power density energy storage devices are increasing. Traditional lithium ion batteries have been unable to meet today's social needs due to their low energy density. Therefore, it is urgent to develop new lithium battery systems with higher energy density and power density and longer cycle life.

[0003] In order to solve these problems, researchers have developed various strategies, such as electrolyte additives; solid-state electrolytes; design of artificial interface layers; construction of three-dimensional self-supporting skeletons and various other technologies. Among them, three-dimensional electrode materials can optimize the structure, morphology, composition, ion diffusion kinetics, electrical conductivity and surface properties of electrode materials, and have unique physical and chemical properties, which have attracted widespread attention from researchers. However, the preparation process of existing three-dimensional electrodes is complicated, the reaction conditions are harsh, the production cost is high, and the structure is difficult to control, which restricts the progress of its practical application.

[0004] Therefore, it is necessary to improve the three-dimensional electrode. SUMMARY

[0005] In order to improve the above technical problems, the present application provides a method for preparing a three-dimensional electrode, which comprises:

[0006] mixing a swelling material with an aqueous slurry solution to obtain a mixed slurry;

[0007] mixing the mixed slurry with an electrode active material, grinding to obtain a coating liquid;

[0008] coating the coating liquid onto a current collector, drying, and cutting to obtain a three-dimensional electrode.

[0009] Therefore, the method of the present application does not need to use a binder, and the method of the present application has the advantages of simple operation and low production cost, and can be used for industrial large-scale production. In addition, the three-dimensional electrode prepared by the method has high energy density, high conductivity and high mechanical strength.

[0010] According to an embodiment of the present application, the swelling material comprises at least one of lithium magnesium silicate, montmorillonite and kaolin.

[0011] According to an embodiment of the present application, the electrode active material comprises at least one of silicon monoxide, silicon, lithium iron phosphate, NCM type ternary material and NCA type ternary material.

[0012] According to an embodiment of the present application, the aqueous slurry comprises at least one of a carbon nanotube aqueous solution, a MXene aqueous solution, a graphene aqueous solution, a superconducting carbon aqueous solution, a chitosan aqueous solution, a polyacrylamide aqueous solution; and the current collector comprises a copper foil.

[0013] According to an embodiment of the present application, the mass ratio of the solute in the aqueous slurry to the mass of the swelling material is 1:5 to 5:1.

[0014] According to an embodiment of the present application, the mass ratio of the electrode active material to the solute in the mixed slurry is 3:2 to 40:1.

[0015] According to an embodiment of the present application, the thickness of the three-dimensional electrode is 300 μm to 2000 μm.

[0016] According to an embodiment of the present application, the drying is performed in hydrogen, nitrogen or argon.

[0017] The present application also provides a three-dimensional electrode prepared by the method described above. Thus, the three-dimensional electrode has all the features and advantages of the method described above, which will not be repeated here.

[0018] The present application also provides the use of the three-dimensional electrode described above in a lithium ion battery. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A flow chart of the method for preparing a three-dimensional electrode;

[0020] Figure 2 XRD patterns of the three-dimensional electrode of Example 1 and lithium magnesium silicate;

[0021] Figure 3 SEM image of the three-dimensional electrode of Example 1.

[0022] Figure 4 Charge-discharge curve of the three-dimensional electrode of Example 1;

[0023] Figure 5 Long cycle test graph of the three-dimensional electrode of Example 1;

[0024] Figure 6 Morphology of the three-dimensional electrode of Example 2;

[0025] Figure 7 Long cycle test graph of the three-dimensional electrode of Example 2;

[0026] Figure 8 Symmetric battery test of the three-dimensional electrode of Example 3;

[0027] Figure 9 Long cycle test graph of the full battery of Example 3. DETAILED DESCRIPTION

[0028] The scheme of the present application will be explained below in combination with examples. Those skilled in the art will understand that the examples below are only for illustration of the present application and should not be regarded as limiting the scope of the present application. If no specific technique or condition is specified in the examples, the technique or condition described in the literature in the art or according to the product instruction is used. If no manufacturer of the reagent or instrument is specified, it is a conventional product that can be obtained by purchase in the market.

[0029] The present application provides a method for preparing a three-dimensional electrode, referring to Figure 1 , the method comprising:

[0030] S100, mixing a swelling material with an aqueous slurry solution to obtain a mixed slurry;

[0031] According to an embodiment of the present application, the swelling material comprises at least one of lithium magnesium silicate, montmorillonite and kaolin. The swelling material spontaneously swells in water, and by mixing the swelling material with the aqueous slurry solution, a three-dimensional skeleton structure can be obtained.

[0032] According to an embodiment of the present application, the aqueous slurry comprises at least one of a carbon nanotube aqueous solution, an MXene aqueous solution, a graphene aqueous solution, a superconducting carbon aqueous solution, a chitosan aqueous solution and a polyacrylamide aqueous solution.

[0033] According to an embodiment of the present application, the mass ratio of the solute in the aqueous slurry to the mass of the swelling material is 1:5 to 5:1, for example, it can be 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1 or 5:1. When the mass ratio of the solute in the aqueous slurry to the mass of the swelling material is within the above range, the viscosity of the slurry is suitable, the electrode active material can be effectively bonded, and the prepared electrode skeleton structure can be stable. If the mass ratio of the solute in the aqueous slurry to the mass of the swelling material is too low, the slurry will be too sticky, and the electrode will be difficult to coat uniformly. If the mass ratio of the solute in the aqueous slurry to the mass of the swelling material is too large, the three-dimensional skeleton pores of the electrode will be too large, the electrode structure strength will not be enough, and it will not be stable.

[0034] S200, mixing the mixed slurry with an electrode active material, grinding to obtain a coating liquid;

[0035] According to an embodiment of the present application, the electrode active material comprises at least one of silicon monoxide, silicon, lithium iron phosphate, NCM type ternary material and NCA type ternary material.

[0036] According to an embodiment of the present application, the mass ratio of the electrode active material to the solute in the mixed slurry is 3:2 to 40:1, for example, 3:2, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, 26:1, 27:1, 28:1, 29:1, 30:1, 31:1, 32:1, 33:1, 34:1, 35:1, 36:1, 37:1, 38:1, 39:1, 40:1. When the mass ratio of the electrode active material to the mixed slurry is within the above range, the electrode can provide superior energy density and good structural integrity. If the mass ratio is too small, the proportion of the electrode active material is too small, and the energy density is severely lost; if the mass ratio is too large, the overall electrode conductivity is reduced, which is not conducive to the utilization rate of active substances and the rate capability.

[0037] S300, coating the coating liquid onto the current collector, drying, cutting, and obtaining a three-dimensional electrode.

[0038] The current collector includes a copper foil.

[0039] According to an embodiment of the present application, the thickness of the three-dimensional electrode is 300 μm to 2000 μm. Thus, when the thickness of the three-dimensional electrode is within the above range, the electrode can be fully infiltrated, which is conducive to the rapid migration of lithium ions and good performance. If the thickness of the three-dimensional electrode is too small, the energy density cannot meet the requirements; if the thickness of the three-dimensional electrode is too large, it is not easy to be fully infiltrated by the electrolyte, which affects the deintercalation of lithium ions.

[0040] According to an embodiment of the present application, the drying is performed in hydrogen, nitrogen or argon.

[0041] The skilled in the art can adjust the electrode surface loading according to the experimental requirements, which is 1 mg·cm -2 to 20 mg·cm -2 . The electrode surface loading is the mass of the material with chargeable and dischargeable active substances, such as silicon, lithium iron phosphate and other electrode materials, coated on the current collector per unit area. High electrode surface loading can provide high surface capacity, and the energy density of the battery will be improved. Compared with the electrode surface loading of existing electrode materials, the electrode surface loading of the present application can be increased by 50%.

[0042] Thus, the method of the present application does not need to use a binder, and the method of the present application has the advantages of simple operation and low production cost, and can be used for industrial large-scale production. In addition, the three-dimensional electrode prepared by the method has high energy density, high conductivity and high mechanical strength.

[0043] The present application also provides a three-dimensional electrode prepared by the method described above. The three-dimensional electrode has all the features and advantages of the method described above, which will not be repeated here.

[0044] The present application also provides the use of the three-dimensional electrode described above in a lithium ion battery. Specifically, the three-dimensional electrode can be used to make electrodes for lithium ion batteries. The three-dimensional electrode can exhibit better cycle stability and higher surface loading and surface capacity when assembled into a lithium ion battery. Further, the lithium ion battery can be applied to electrochemical energy storage, 3C field and power supply, etc.

[0045] The reagents used in the examples described below can be purchased from the market or prepared by the methods described in the present application, unless otherwise specified.

[0046] Example 1

[0047] 2 g of lithium magnesium silicate was added to 500 mL of carbon nanotube aqueous solution with a concentration of 4 mg / mL, stirred uniformly to prepare a slurry. 6 g of silicon was added to the above slurry, ground uniformly, coated with a doctor blade, and finally freeze-dried to obtain a three-dimensional electrode.

[0048] Figure 2 The XRD pattern of the three-dimensional electrode of Example 1 and lithium magnesium silicate is shown in FIG. 1. Figure 2 It can be seen that the characteristic peaks of lithium magnesium silicate disappear, proving that the bulk swells and forms a lamellar structure, participating in the construction of the three-dimensional skeleton.

[0049] Figure 3 The SEM image of the three-dimensional electrode of Example 1 is shown in FIG. 2. Figure 3 The SEM image of FIG. 2 can prove that the electrode is a three-dimensional porous structure.

[0050] The three-dimensional electrode obtained in Example 1 was subjected to charge-discharge test and long cycle test at a rate of 0.05C, Figure 4 The charge-discharge curve of the three-dimensional electrode of Example 1 is shown in FIG. 3. Figure 4 It shows that the three-dimensional electrode has very high initial capacity and initial coulombic efficiency.

[0051] Figure 5 The long cycle test graph of the three-dimensional electrode of Example 1 is shown in FIG. 4. Figure 5 It shows that the capacity attenuation is weak and the cycle stability is high in the long cycle test.

[0052] Example 2

[0053] 2 g of lithium magnesium silicate was added to 500 mL of MXene (Ti3C2T xThe silicon was stirred evenly in an aqueous solution to prepare a slurry. 6g of silicon was added to the slurry, ground evenly, coated with a doctor blade, and finally dried to obtain a three-dimensional electrode.

[0054] Figure 6 This is a three-dimensional electrode morphology diagram of Example 2. Figure 6 The SEM images prove that the electrode is a three-dimensional porous structure.

[0055] And long-cycle testing was conducted at a rate of 0.05C. Figure 7 This is a long-cycle test diagram of the three-dimensional electrode in Example 2. Figure 7 This indicates that the capacity decay is weak and the cycling stability is high during long-cycle testing.

[0056] Example 3

[0057] 2g of lithium magnesium silicate was added to 500mL of a 4mg / mL aqueous solution of carbon nanotubes and stirred until homogeneous to prepare a slurry. The slurry was then coated using a doctor blade and dried to obtain a three-dimensional electrode framework. The framework was then tested at 1mA cm⁻¹. -2 After lithium deposition at a certain current density, the sample was removed and subjected to symmetric cell testing. The test results are as follows: Figure 8 As shown, Figure 8 This indicates that the framework is a good lithium metal host material, which can reduce problems such as dendrite growth and volume expansion of lithium metal anodes and improve the lifespan of lithium metal.

[0058] The three-dimensional anode with lithium deposition prepared in Example 3 was matched and assembled with lithium iron phosphate to form a full cell. Long-term cycling tests were conducted at 10C. The test results are as follows: Figure 9 As shown, Figure 9 This indicates that the electrode exhibits good cyclic stability under high current density.

[0059] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction.

[0060] It should be noted that in this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0061] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method of preparing a three-dimensional electrode, characterized by, The method comprises: mixing a swelling material with an aqueous slurry solution to obtain a mixed slurry; mixing the mixed slurry with an electrode active material, grinding to obtain a coating liquid; coating the coating liquid onto a current collector, drying, cutting to obtain a three-dimensional electrode; the swelling material comprises at least one of lithium magnesium silicate, montmorillonite, kaolin; the aqueous slurry comprises at least one of carbon nanotube aqueous solution, MXene aqueous solution, graphene aqueous solution, superconducting carbon aqueous solution; the mass ratio of solute in the aqueous slurry to the mass of the swelling material is 1:5 to 5:

1.

2. The method of claim 1, wherein, the electrode active material comprises at least one of silicon monoxide, silicon, lithium iron phosphate, NCM type ternary material, NCA type ternary material.

3. The method of claim 1, wherein, the current collector comprises copper foil.

4. The method of claim 1, wherein, the mass ratio of the electrode active material to the solute in the mixed slurry is 3:2 to 40:

1.

5. The method of claim 1, wherein, the thickness of the three-dimensional electrode is 300 µm to 2000 µm.

6. The method of claim 1, wherein, the drying is carried out in hydrogen, nitrogen or argon.

7. A three-dimensional electrode, characterized by the three-dimensional electrode is prepared by the method of any one of claims 1-6.

8. Use of the three-dimensional electrode of claim 7 in a lithium ion battery.

Images