A negative electrode current collector with a three-dimensional spherical-like surface morphology, a preparation method and application thereof

Abstract

The application discloses a negative electrode current collector with a three-dimensional spherical-like surface pattern and a preparation method and application thereof, and the method comprises the following steps: S1, carbon nanotube-graphene and an additive are added into water, and ultrasonic dispersion is carried out to uniformly obtain a carbon nanotube-graphene water suspension; S2, the carbon nanotube-graphene water suspension is taken and added into a metal electroplating solution to form a mixed solution, and ultrasonic dispersion is carried out to uniformly obtain the mixed solution; S3, the same metal ions in the metal electroplating solution are taken as an anode, the negative electrode current collector is taken as a cathode, and the mixed solution obtained in the step S2 is taken as an electrolyte, and the negative electrode current collector with the three-dimensional spherical-like surface pattern is obtained through electrodeposition. The negative electrode current collector prepared by the application has a uniform spherical-like surface structure, good conductivity and a high specific surface area, is beneficial to enhancing the adhesion between the current collector and the loaded active material, and has the advantages of a simple preparation method and suitability for large-scale industrial production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electrochemical power supply current collector processing, and particularly relates to a negative electrode current collector with a three-dimensional spherical-like surface morphology and a preparation method and application thereof. BACKGROUND

[0002] A lithium ion battery mainly comprises active substances, a battery shell, a current collector, a separator, an electrolyte and the like. The current collector is one of important components of the lithium ion battery, and carries active substances on the surface and contacts with the electrolyte, and meanwhile, the current collector collects the electrons generated by the positive and negative active substances to the external circuit to form an electric current.

[0003] Copper has sufficient mechanical strength, good electrical conductivity, and is not easy to alloy with lithium, and the like, and thus is commonly used as the current collector of the negative electrode of the lithium ion battery. However, the copper current collector still has some problems: (1) the copper current collector is easy to generate an oxide film on the surface, and the oxide film is a semiconductor, thus affecting the electrical conductivity of the current collector; (2) the copper current collector is easy to react with the solvent and impurities of the electrolyte and to dissolve during the charging and discharging process of the battery, thus making the copper unstable; meanwhile, the oxide on the surface of the copper is easy to react with lithium ions to cause volume expansion and contraction, thus causing the active substance coating on the surface of the copper to fall off; (3) in addition, high-capacity negative electrode materials represented by silicon have a huge volume change during the charging and discharging cycle, thus causing the separation of the electrode material and the copper current collector.

[0004] In order to solve the above problems, researchers have made a lot of efforts. Among them, growing a carbon film on the surface of the current collector to improve the surface roughness of the current collector is a common method in the art. At present, there are mainly gas phase deposition method, coating method and electrodeposition method. Among them, the gas phase deposition method has harsh conditions and complex technology, and is difficult to mass produce; the coating method is to coat the carbon material mixed with a binder on the base material, and the introduction of the binder reduces the electrical conductivity of the surface of the copper foil, and the binding force is not high; the electrodeposition method is a commonly used co-deposition method, but there are still problems such as uneven deposition morphology on the surface of the current collector, and no effective formation of a three-dimensional conductive network with lines and surfaces. SUMMARY

[0005] In order to solve the above problems, the purpose of the present application is to provide a negative electrode current collector with a three-dimensional spherical-like surface morphology and a preparation method and application thereof. The negative electrode current collector prepared by the present application has a uniform spherical-like structure on the surface, has good electrical conductivity and high specific surface area, is beneficial to enhancing the adhesion between the current collector and the loaded active material, exhibits good electrochemical performance, and the preparation method is simple, suitable for mass industrial production and popularization and application.

[0006] In order to achieve the above purpose, the present application first provides a preparation method of a negative electrode current collector with a three-dimensional spherical-like surface morphology, comprising the following steps:

[0007] S1, adding carbon nanotube-graphene and additives into water, ultrasonic dispersion to obtain carbon nanotube-graphene water suspension;

[0008] S2, adding the carbon nanotube-graphene water suspension obtained in step S1 into metal electroplating solution to form a mixed solution, and ultrasonic dispersion to obtain a mixed solution;

[0009] S3, using the metal ions in the metal electroplating solution as the same kind of metal as anode, using negative current collector as cathode, using the mixed solution prepared in step S2 as electrolyte, and through electrodeposition to obtain the negative current collector with surface in three-dimensional spherical morphology.

[0010] In step S1, the carbon nanotube-graphene is a mixture of carbon nanotube and graphene; the mass ratio of carbon nanotube to graphene is 1:(0.1-100).

[0011] In step S2, the mass fraction of carbon nanotube-graphene in the mixed solution is 0.01%-1%.

[0012] Preferably, in step S3, the current density of electrodeposition is 0.5-5 A / dm 2 , and the electrodeposition time is 30 s-3600 s; more preferably, the current density is 3 A / dm 2 , and the electrodeposition time is 600 s.

[0013] Preferably, in step S1, the mass fraction of carbon nanotube-graphene in the suspension is 0.01%-10%; more preferably, the mass fraction is 1.5%.

[0014] Preferably, the carbon nanotube-graphene is a mixture formed in situ, such as a carbon nanotube-graphene mixture formed by direct vapor deposition.

[0015] Preferably, in step S1, the additive is a water-based surfactant, including any one or a combination of more than one of Triton X-100, Tween 80, Tween 100, and polyoxyethylene lauryl ether.

[0016] Preferably, in step S1, the mass ratio of carbon nanotube-graphene to additive is: carbon nanotube-graphene: additive = 1:(2-50).

[0017] Preferably, in step S3, the negative current collector includes but is not limited to copper foil, stainless steel foil, carbon fiber, or carbon cloth.

[0018] Another aspect of the present application also provides a negative current collector with surface in three-dimensional spherical morphology prepared by the preparation method according to any one of the preceding aspects.

[0019] The application further provides an electrode comprising the negative electrode current collector with the three-dimensional spherical morphology as described above.

[0020] The application further provides a battery comprising the electrode as described above.

[0021] Compared with the prior art, the application has the following advantages:

[0022] 1. The negative electrode current collector prepared by the method has a uniform spherical structure morphology on the surface, which greatly improves the roughness and specific surface area of the current collector surface, improves the contact area and bonding force between the active material and the current collector, and effectively prevents the active material from falling off from the current collector.

[0023] 2. The negative electrode current collector prepared by the method has a network conductive channel with point (copper particles), line (carbon nanotubes) and surface (graphene) structures, which can effectively disperse the current density and improve the cycle life and rate performance of the battery.

[0024] 3. The preparation method provided by the application is simple in process, easy to control in conditions, and suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 SEM image of the surface of the current collector prepared in Example 1 of the application.

[0026] Figure 2 SEM image of the surface of the current collector prepared in Example 1 of the application.

[0027] Figure 3 SEM image of the surface of the current collector prepared in Example 2 of the application.

[0028] Figure 4 Comparison chart of the cycle performance of the battery prepared based on the current collector of Example 1 of the application and the battery of the comparative example. DETAILED DESCRIPTION

[0029] The technical solutions of the application will be further described below with reference to the drawings and examples.

[0030] As described above, in view of the deficiencies of the prior art, the application applicant finally first provides a preparation method of a negative electrode current collector with a three-dimensional spherical morphology, which comprises the following steps:

[0031] S1. The carbon nanotube-graphene and the additive are added to water and uniformly dispersed by ultrasonic, to obtain a carbon nanotube-graphene water-based suspension;

[0032] S2, adding the carbon nanotube-graphene aqueous suspension obtained in step S1 into a metal electroplating solution to form a mixed solution, and ultrasonically dispersing the mixed solution uniformly;

[0033] S3, taking the metal ions in the metal electroplating solution as the same kind of metal as an anode, taking a negative current collector as a cathode, and taking the mixed solution obtained in step S2 as an electrolyte, and obtaining the negative current collector with a three-dimensional spherical-like surface morphology by electrodeposition;

[0034] In step S1, the carbon nanotube-graphene is a mixture of carbon nanotubes and graphene; the mass ratio of carbon nanotubes to graphene is 1:(0.1-100); preferably, the mass ratio is 1:0.5.

[0035] Preferably, the mass fraction of carbon nanotube-graphene in the suspension is 0.01%-10%; more preferably, the mass fraction is 1.5%.

[0036] Preferably, the additive is an aqueous surfactant, including any one or a combination of more than one of Triton X-100, Tween 80, Tween 100, and polyoxyethylene lauryl ether; in some embodiments, the additive is Triton X-100.

[0037] Preferably, the mass ratio of carbon nanotube-graphene to additive is: carbon nanotube-graphene: additive = 1:(2-50); more preferably, the mass ratio is: carbon nanotube-graphene: additive = 1:5.

[0038] In some embodiments, the carbon nanotube-graphene is a physical mixture of carbon nanotubes and graphene.

[0039] In other embodiments, the carbon nanotube-graphene is a mixture formed in situ, such as a carbon nanotube-graphene mixture formed by direct vapor deposition. The carbon nanotube-graphene mixture formed in situ and having a coiled cross-linking structure is more likely to form a uniformly dispersed suspension, avoiding the problem of uneven surface distribution after deposition on the current collector.

[0040] Preferably, the carbon nanotubes are single-layer carbon nanotubes.

[0041] Preferably, in step S2, the mass fraction of carbon nanotube-graphene in the mixed solution is 0.01%-1%; in some embodiments, the mass fraction of carbon nanotube-graphene in the mixed solution is 0.1%.

[0042] Preferably, in step S3, the current density of the electrodeposition is 0.5-5 A / dm 2 , and the electrodeposition time is 30 s-3600 s; more preferably, the current density is 3 A / dm 2electrodeposition time is 600s.

[0043] In step S3, the negative current collector includes, but is not limited to, copper foil, stainless steel foil, carbon fiber, or carbon cloth, and other conductive metal materials or other materials can also be selected.

[0044] The metal plating solution is a commonly used copper, nickel, iron, etc. plating solution on the market or in the laboratory, which can be commercially purchased or prepared and used according to the commonly used formula in the art.

[0045] Another aspect of the present application also provides a negative current collector with a surface in a three-dimensional spherical-like morphology prepared by the preparation method of any one of the preceding aspects.

[0046] Another aspect of the present application also provides an electrode comprising the negative current collector with a surface in a three-dimensional spherical-like morphology described above.

[0047] Another aspect of the present application also provides a battery comprising the electrode described above.

[0048] The technical features of the present application are described in detail below through examples and drawings. The instruments and materials described in the following examples can be obtained from commercial channels, unless otherwise specified.

[0049] Reagents and materials

[0050] The carbon nanotube-graphene powder used in the embodiments of the present application is purchased from Times Energy (Shanghai) Energy Technology Co., Ltd., model number: SY-GNH-1-1, and according to its instruction manual, the mass ratio of carbon nanotubes and graphene in the mixture is 1:1; in some embodiments, the in-situ grown carbon nanotube-graphene mixture with cross-linking structure can also be prepared by a gas deposition method.

[0051] The metal plating solution used in the embodiments of the present application is an acidic copper sulfate bright plating solution, and the formula is: copper sulfate CuSO4200g / L, sulfuric acid 60g / L, 2-mercaptobenzimidazole 0.001g / L, ethylene thiourea 0.006g / L, polydithiodipropyl sulfonic acid sodium 0.018g / L, polyethylene glycol 0.05g / L, and sodium dodecyl sulfate 0.08g / L.

[0052] Example 1

[0053] A preparation method of a negative current collector with a surface in a three-dimensional spherical-like morphology, comprising the following steps:

[0054] S1, 1g of carbon nanotube-graphene powder and 5g of Tween 100 are added to 61.6g of distilled water, and ultrasonic treatment is performed for 12h to obtain a carbon nanotube-graphene aqueous suspension with a mass fraction of 1.5%;

[0055] S2, 20g of the carbon nanotube-graphene aqueous suspension is added to 30g of the acidic copper sulfate bright plating solution to form a mixed solution, and ultrasonic dispersion is performed for 30min;

[0056] S3, the copper foil is used as an anode, the copper foil is used as a cathode, the mixed solution prepared in step S2 is used as an electrolyte, the current density is 0.5A / dm 2 The cathode obtained after rinsing with distilled water and blowing dry is the negative current collector with a surface in a three-dimensional spherical-like morphology.

[0057] Example 2

[0058] A preparation method of a negative current collector with a surface in a three-dimensional spherical-like morphology, comprising the following steps:

[0059] S1, 1g of carbon nanotube-graphene powder and 5g of Tween 100 are added to 61.6g of distilled water, and ultrasonic dispersion is performed for 12h to obtain a carbon nanotube-graphene aqueous suspension with a mass fraction of 1.5%;

[0060] S2, 20g of the carbon nanotube-graphene aqueous suspension is added to 30g of the acidic copper sulfate bright plating solution to form a mixed solution, and ultrasonic dispersion is performed for 30min;

[0061] S3, the copper foil is used as an anode, the copper foil is used as a cathode, the mixed solution prepared in step S2 is used as an electrolyte, the current density is 0.5A / dm 2 The cathode obtained after rinsing with distilled water and blowing dry is the negative current collector with a surface in a three-dimensional spherical-like morphology.

[0062] As Figures 1 to 3 shown, the current collectors prepared in Examples 1 and 2 are subjected to SEM electron microscope scanning, and it is shown that the surface of the current collector prepared in Example 1 presents a uniform spherical-like structure morphology Figure 1 and Figure 2 ); the surface of the current collector prepared in Example 2 also presents a uniform spherical-like structure morphology Figure 3 .

[0063] Example 3

[0064] The current collectors prepared by the method are used for subsequent battery preparation, and the battery performance is detected. Among them, the current collectors of Example 1 and Example 2 are used as the current collectors, pure copper foil is used as a comparative example, SiOx-C is used as an active material, SP is used as a conductive agent, and PAAli is used as a binder, and the ratio is 8:1:1, the materials are mixed, coated, and three kinds of 2032 button batteries are made, and the performances of the three kinds of batteries are tested.

[0065] The results are shown in Figure 1As shown in Table 1, compared with the comparative examples, the batteries prepared based on the current collector fluid of the embodiments of the present application have more excellent performance, the first efficiency is increased by about 2%, and the cycle performance is obviously improved, the capacity retention rate (0.1C) at 45 cycles is increased by about 10%, mainly because the current collector with such structure increases the binding force between the active material and the current collector, provides more uniform conductive channels, reduces the apparent current density, and makes the silicon negative electrode capacity and life better.

[0066] Table 1 Performance comparison of batteries prepared based on the current collector fluid of embodiments 1 and 2 and pure copper foil

[0067] Battery No. Initial efficiency (%) Capacity retention rate at 45 cycles (%)(0.1 C) Example 1 (1#) 72.24 90.27 Example 1 (2#) 72.60 91.79 Example 2 (1#) 72.22 92.80 Example 2 (2#) 72.77 92.72 Comparative Example (1#) 70.13 83.00 Comparative Example (2#) 70.54 82.62

[0068] In summary, the current collector prepared by the preparation method of the present application has a uniform spherical structure on the surface, has good conductivity and high specific surface area, is beneficial to enhancing the adhesion between the current collector and the loaded active material, exhibits good electrochemical performance, and the preparation method is simple, suitable for large-scale industrial production and popularization and application.

[0069] Although the content of the present application has been described in detail by the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present application. After reading the above content, various modifications and alternatives of the present application will be obvious to those skilled in the art. Therefore, the protection scope of the present application should be defined by the appended claims.

Claims

1. A method for preparing a negative electrode current collector with a three-dimensional spherical surface morphology, characterized in that, Includes the following steps: S1, add carbon nanotube-graphene and additives to water, and disperse evenly by ultrasonication to obtain a carbon nanotube-graphene aqueous suspension. S2, take the carbon nanotube-graphene aqueous suspension obtained in step S1 and add it to the metal electroplating solution to form a mixed solution, and then ultrasonically disperse it evenly; S3, using the same metal ions in the metal electroplating solution as the anode, the negative electrode current collector as the cathode, and the mixed solution obtained in step S2 as the electrolyte, the negative electrode current collector with a three-dimensional spherical morphology on the surface is obtained by electrodeposition. In step S1, the carbon nanotube-graphene is a mixture of carbon nanotubes and graphene; the mass ratio of carbon nanotubes to graphene is 1:(0.1~100); the additive is a water-based surfactant, including any one or more combinations of Triton X-100, Tween 80, Tween 100, and polyoxyethylene lauryl ether; the mass ratio of carbon nanotube-graphene to additive is: carbon nanotube-graphene:additive = 1:(2~50). In step S2, the mass fraction of carbon nanotube-graphene in the mixture is 0.01% to 1%.

2. The method for preparing a negative electrode current collector with a three-dimensional spherical surface morphology as described in claim 1, characterized in that, In step S3, the current density of the electrodeposition is 0.5–5 A / dm³. 2 The electrodeposition time is 30s to 3600s.

3. The method for preparing a negative electrode current collector with a three-dimensional spherical surface morphology as described in claim 1, characterized in that, In step S1, the mass fraction of carbon nanotube-graphene in the suspension is 0.01% to 10%.

4. The method for preparing a negative electrode current collector with a three-dimensional spherical surface morphology as described in claim 1, characterized in that, The carbon nanotube-graphene mixture is formed by in-situ growth.

5. The method for preparing a negative electrode current collector with a three-dimensional spherical surface morphology as described in claim 1, characterized in that, In step S3, the negative electrode current collector includes copper foil, stainless steel foil, carbon fiber, or carbon cloth.

6. A negative electrode current collector with a three-dimensional spherical morphology on its surface, prepared by the preparation method according to any one of claims 1-5.

7. An electrode, characterized in that, The electrode includes the negative electrode current collector with a three-dimensional spherical morphology as described in claim 6.

8. A battery, characterized in that, The battery includes the electrodes as described in claim 7.

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