Three-dimensional carbon-coated aluminum fiber current collector, preparation method and application thereof

Abstract

The application discloses a kind of three-dimensional carbon-coated aluminum fiber current collector and its preparation method and application, belong to battery current collector material and its preparation technical field.The application solves the problems of complex preparation process and poor cycle stability existing in the prior art three-dimensional porous aluminum current collector.The application first lays out metal aluminum fiber into net shape, then after pressure treatment, carbon coating is carried out on its surface by adopting gas deposition or physical coating method combined with calcination method, point contact is formed between metal fibers by pressure treatment, and then the fusion effect of physical contact points between metal aluminum fibers occurs during calcination process, so that the three-dimensional aluminum fiber is coated with carbon and forms an integrated network structure, so that it has strong mechanical strength and conductive network, and significant optimization is realized in terms of resistivity, electrolyte permeability, rate performance and the like.In addition, the preparation method provided by the application is simple, which is conducive to reducing production cost and realizing industrial large-scale production.

Description

Technical Field

[0001] The present invention relates to a three-dimensional carbon-coated aluminum fiber current collector and a preparation method and application thereof, belonging to the technical field of battery current collector materials and their preparation. Background Art

[0002] Aluminum-based materials are widely used as current collectors in lithium-ion and sodium-ion batteries due to their low cost, high conductivity, and high stability. However, the currently widely used aluminum foil has a small surface area and relatively few active sites, limiting its performance in applications requiring high specific surface area and good ion distribution. Furthermore, due to structural limitations, two-dimensional aluminum foil cannot provide the ability to mitigate volume changes.

[0003] Compared with two-dimensional aluminum foil, the three-dimensional porous aluminum current collector has a tightly packed three-dimensional porous structure, which provides a larger surface area and more active sites. At the same time, the special structure of three-dimensional porous aluminum makes the distribution of metal ions more uniform, and effectively alleviates the volume change of the metal during the deposition and dissolution process through confinement. In addition, the porous structure of the three-dimensional porous aluminum current collector may further reduce its weight, making it more advantageous in battery applications that pursue higher energy density and lower weight. However, the preparation of three-dimensional porous aluminum current collectors usually involves complex processes, such as chemical etching, electrochemical dealloying, etc. These methods are cumbersome, difficult to operate, and have a high risk factor, resulting in high manufacturing costs and making it difficult to put into mass production. At the same time, because the porous aluminum manufactured by these methods has a smooth aluminum wire skeleton, when in contact with the electrode material, it has poor contact and high resistance, which is not conducive to improving the energy density of the device. For example, Chinese patent CN112201793A involves "a method for preparing a three-dimensional current collector for the negative electrode of an aqueous zinc-ion battery," which uses natural carbon fibers as the current collector and performs a surface coating treatment. The current collector formed by the natural carbon fibers involved in the patent is physically stacked, and there is no strong connection between the fibers, so there is a large contact resistance. Chinese patent CN102473925A involves "a method for manufacturing a metal porous body, an aluminum porous body, a battery electrode material containing a metal porous body or an aluminum porous body, and an electrode material for an electric double-layer capacitor." In this method, porous aluminum is obtained by attaching aluminum to the surface of a resin porous body and then dissolving the resin porous body. This method relies on the pore structure of the resin, and the resulting porous aluminum lacks flexibility. At the same time, the size of the dissolved aluminum is difficult to control. Chinese patent CN117680657A involves the technology of "a production line for preparing foamed aluminum by a melt foaming method and its production process", which invents a production line for preparing foamed aluminum by a foaming method and its production process. However, due to its excessive weight, foamed aluminum will reduce the energy density of the electrode during use. At the same time, due to the cumbersome process, the cost of foamed aluminum is relatively high, and therefore it is not suitable for large-scale use as a battery current collector. SUMMARY

[0004] The present application provides a carbon-coated aluminum fiber current collector, a preparation method thereof and an application thereof.

[0005] The technical scheme of the present application is as follows:

[0006] One of the objectives of the present application is to provide a preparation method of a three-dimensional carbon-coated aluminum fiber current collector, which comprises the following steps:

[0007] Step one: surface oil removal treatment of aluminum fibers;

[0008] Step two: uniform dispersion and flat laying of the treated aluminum fibers into a net shape, and pressure setting treatment to obtain an aluminum fiber net with a porosity of 5% to 95%;

[0009] Step three: carbon coating on the surface of the aluminum fiber net by using a gas deposition one-step method or an organic precursor two-step method to obtain a three-dimensional carbon-coated aluminum fiber current collector.

[0010] Further limitation: the diameter of the aluminum fibers in step one is 1 to 100 microns, and the length is 0.001 to 500 meters.

[0011] Further limitation: the oil removal treatment in step one includes mechanical cleaning and solvent cleaning, the mechanical cleaning is cleaning the aluminum fibers using a brush, a spray gun or a spraying device, and the solvent is one or several of acetone, anhydrous ethanol and petroleum ether.

[0012] Further limitation: in step two, the treated aluminum fibers are uniformly dispersed and flat laid into a net shape by using a gas-assisted dispersion or liquid-phase ultrasonic dispersion method.

[0013] Further limitation: the pressure of the pressure setting treatment in step two is 1 to 50 MPa.

[0014] Further limitation: in step three, the operation process of carbon coating on the surface of the aluminum fiber net by using a gas deposition one-step method is as follows: calcination treatment of the aluminum fiber net under the condition of the presence of a carbon source gas and a protective gas; the carbon source gas is one or several of carbon monoxide, methane, acetylene and ethylene; the protective gas is one or several of argon, hydrogen and nitrogen; and the calcination temperature is 350 to 700 degrees Celsius.

[0015] Further limitation: in step three, the operation process of carbon coating on the surface of the aluminum fiber net by using an organic precursor two-step method is as follows: coating of the organic precursor on the surface of the aluminum fiber net by using an impregnation method, and then calcination treatment under the condition of the presence of a protective gas; and the calcination temperature is 350 to 700 degrees Celsius.

[0016] More specifically, the organic precursor is one or more of polydopamine, glucose, sucrose, polyaniline, polyvinylpyrrolidone, tannic acid, citric acid, polyvinyl alcohol, polypyrrole, vitamin C, polyethylene glycol, pitch, anthracene, aniline.

[0017] The second object of the present application is to provide a three-dimensional carbon-coated aluminum fiber current collector prepared by the above method, and more specifically, the thickness of the current collector is 3-200 microns, and the thickness of the carbon coating layer is 10-1000 nanometers.

[0018] The third object of the present application is to provide an application of the above three-dimensional carbon-coated aluminum fiber current collector, and more specifically, the application is used for the preparation of lithium ion batteries, sodium ion batteries or zinc ion batteries.

[0019] The present application has the following advantages:

[0020] The present application first lays the metal aluminum fibers into a net shape, then performs pressure treatment, and then performs carbon coating on the surface by combining calcination with gas deposition or physical coating. The pressure treatment forms point contacts between the metal fibers, and then the sintering effect between the physical contact points between the metal aluminum fibers during the calcination process forms an integrated network structure of the three-dimensional aluminum fiber coated with carbon, which has strong mechanical strength and a conductive network, and achieves significant optimization in terms of resistivity, electrolyte permeability, rate performance, etc. The surface of the aluminum wire skeleton of the three-dimensional current collector prepared by the present application is rough, which can improve the electrochemical stability of the assembled battery, and improve the rate performance, cycle life and safety of the battery. The aluminum fibers after roller pressing can ensure good point contact between the fibers, which avoids the complete coverage of the fiber surface by carbon during the subsequent carbon coating process, which leads to the inability of the fibers to be effectively sintered by sintering. Therefore, pressure forming is required before carbon coating and sintering. In addition, the preparation method of the three-dimensional current collector provided by the present application is simple and does not depend on complex equipment, which is beneficial to reduce energy consumption and production cost, and is easy to realize industrialized mass production. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The resistivity comparison chart of the current collectors prepared for Example 1 and Comparative Examples 1-2;

[0022] Figure 2 The cycle performance chart of the battery assembled for Example 1;

[0023] Figure 3 The actual photo of the current collector prepared for Example 3 after welding the tab. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used are conventional in the art and can be obtained commercially by those skilled in the art unless otherwise specified.

[0026] Example 1

[0027] The process of preparing the three-dimensional carbon-coated aluminum fiber current collector in this embodiment is as follows:

[0028] Weigh 0.35 g of aluminum fiber with a diameter of 12 μm and a length of 10 mm, then use a spray device to rinse the metal surface, and then use 100 mL of acetone and 100 mL of anhydrous ethanol to degrease the surface, and dry it naturally at room temperature for use.

[0029] The dried aluminum fibers were stirred in 100 ml of ethylene glycol solution at 600 r / min and ultrasonically dispersed at a frequency of 40 kHz for 3 minutes. After being spread into a mesh, the ethylene glycol solution on the surface was removed with 200 ml of deionized water. The fibers were dried naturally at room temperature and then repeatedly rolled using a double-roller at a pressure of 10 MPa to obtain an aluminum fiber mesh with a porosity of 80%.

[0030] Dissolve 0.1576 g of tris(hydroxy)aminomethane in 100 mL of deionized water and adjust the pH to 8.5 using 0.5 M HCl solution. Then add 0.1 g of dopamine hydrochloride and stir to dissolve. Then soak the aluminum fiber mesh in the solution to react and let it stand for 24 hours to form a polydopamine coating. Take it out and wash it with deionized water, and dry it naturally at room temperature for later use.

[0031] The dried polydopamine-coated aluminum fiber mesh was calcined at 650°C in a circulating argon-hydrogen environment (hydrogen content was 10%) for 5 hours, with a heating rate of 5°C / min, to obtain a three-dimensional carbon-coated aluminum fiber current collector.

[0032] The process of assembling a battery using the three-dimensional carbon-coated aluminum fiber current collector prepared above in this embodiment is as follows:

[0033] First, the three-dimensional carbon-coated aluminum fiber current collector was cut into 5cm×10cm, and then laser welding was used with a laser wavelength of 1064nm and a laser power of 150W to weld an aluminum tab with a thickness of 0.2mm.

[0034] Then, the positive electrode active material LiMn0.5 Fe 0.5 PO4, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) were mixed and homogenized in an N-methylpyrrolidone solution at a mass ratio of 93.5:3:3.5 to obtain a positive electrode material slurry. The positive electrode material slurry was coated on the obtained current collector welded with an aluminum tab, shaken until the slurry was completely filled, and then dried in an oven at 100°C for 12 hours to obtain a positive electrode sheet.

[0035] Finally, the obtained positive electrode sheet was assembled with a metal lithium negative electrode and a lithium ion secondary electrolyte (LB-275) to assemble a lithium ion battery. The cycle performance of the assembled lithium ion battery was tested. The test results are as follows: Figure 2 As shown, Figure 2 It shows that after 300 cycles at a rate of 1C, there is still 130mAh·g -1 discharge capacity.

[0036] Example 2

[0037] The process of preparing the three-dimensional carbon-coated aluminum fiber current collector in this embodiment is as follows:

[0038] Weigh 3.5 kg of aluminum fiber with a diameter of 15 μm and a length of 2 m, then use a spray device to rinse the metal surface, and then use 1 L of acetone and 1 L of anhydrous ethanol to degrease the surface, and dry it naturally at room temperature for use.

[0039] The dried aluminum fibers were spread into a mesh shape by gas-assisted dispersion, with an air flow velocity of 20 m / s, an air flow temperature of 25°C, and a fiber concentration of 0.3 g / m 3 The pressure in the web-forming chamber was maintained at 300 Pa, and then a double-roller was used to repeatedly roll the web at a pressure of 20 MPa to obtain an aluminum fiber web with a porosity of 70%.

[0040] 55.5 g of polyvinyl pyrrolidone (MW=40000) was dissolved in 1 L of ethanol, and the aluminum fiber mesh was immersed in the solution. After the ethanol was completely evaporated at 55° C., the aluminum fiber mesh coated with polyvinyl pyrrolidone was obtained and set aside.

[0041] The aluminum fiber mesh coated with polyvinyl pyrrolidone was calcined at 660° C. in a circulating argon environment for 4 hours with a heating rate of 5° C. / min to obtain a three-dimensional carbon-coated aluminum fiber current collector.

[0042] The process of assembling a battery using the three-dimensional carbon-coated aluminum fiber current collector prepared above in this embodiment is as follows:

[0043] Firstly, the three-dimensional carbon-coated aluminum fiber current collector is cut into 5m x 10m, and then laser welding is used, wherein the laser wavelength is 1064nm, the laser power is 150W, and the aluminum tab with a thickness of 0.2mm is welded.

[0044] Then, the positive active material LiFePO4 is mixed with the conductive agent acetylene black and the binder polyvinylidene fluoride (pvdf) in a mass ratio of 93.5:3:3.5 in an N-methylpyrrolidone solution to obtain a positive material slurry. The positive material slurry is coated on the obtained current collector with welded aluminum tabs, and after oscillation until the slurry is completely filled, it is dried in an oven at 100°C for 12h to obtain a positive tab.

[0045] Finally, the obtained positive tab is assembled with a metal lithium negative electrode and a lithium ion secondary electrolyte (LB-275) to form a lithium ion battery. The cycle performance of the assembled lithium ion battery is tested. The test results show that after 200 cycles at a rate of 1C, the discharge capacity is still 130mAh·g -1 .

[0046] Example 3

[0047] The process for preparing the three-dimensional carbon-coated aluminum fiber current collector in this example is as follows:

[0048] 0.7g of aluminum fibers with a diameter of 25μm and a length of 6mm are weighed, and then the metal surface is rinsed using a spraying device. Then, the surface is deoiled using 100mL of acetone and 100mL of anhydrous ethanol, respectively, and is naturally dried at room temperature.

[0049] The dried aluminum fibers are stirred in 100ml of ethylene glycol solution at 600r / min and ultrasonically dispersed at a frequency of 40kHz for 3min. After being laid flat into a net shape, the surface ethylene glycol solution is removed using 200ml of deionized water, and is naturally dried at room temperature. Then, the aluminum fiber net with a porosity of 60% is obtained by repeatedly rolling using a roller machine at a pressure of 30MPa.

[0050] 0.1576g of tris(hydroxy)aminomethane is dissolved in 100mL of deionized water, and the pH is adjusted to 8.5 using 0.5M HCl. Then, 0.1g of tannic acid is added, and the aluminum fiber net is soaked in the solution after stirring and dissolving. After standing for 24h, a tannic acid coating layer is formed. The aluminum fiber net is taken out, washed with deionized water, and naturally dried at room temperature.

[0051] The dried tannic acid-coated aluminum fiber net is calcined at 650°C in a flowing argon-hydrogen gas environment (hydrogen content is 5%) for 5h, with a heating rate of 10°C / min, to obtain a three-dimensional carbon-coated aluminum fiber current collector.

[0052] The process of assembling the battery using the three-dimensional carbon-coated aluminum fiber current collector prepared above in this example is as follows:

[0053] First, the three-dimensional carbon-coated aluminum fiber current collector is cut into 8 cm x 10 cm, and then laser welding is used, wherein the laser wavelength is 1064 nm and the laser power is 150 W, and the aluminum tab with a thickness of 0.2 mm is welded, as shown in Figure 3 .

[0054] Then, the positive active material Na3V2(PO4)3, the conductive agent super P, and polyvinylidene fluoride (pvdf) are mixed in a mass ratio of 93.5:3:3.5 in an N-methylpyrrolidone solution to obtain a positive material slurry. The positive material slurry is coated on the current collector with the welded aluminum tab, and after oscillation until the slurry is completely filled, drying is performed in an oven at 100°C for 12 h to obtain a positive electrode sheet.

[0055] Finally, the positive electrode sheet is assembled with a metal sodium negative electrode and a NaPF6 (NP-005) electrolyte to obtain a sodium ion battery, and the cycle performance of the assembled sodium ion battery is tested. The test results show that after 200 cycles at a rate of 1C, the discharge capacity is still 90 mAh·g -1 .

[0056] Example 4

[0057] The process of preparing the three-dimensional carbon-coated aluminum fiber current collector in this example is as follows:

[0058] 7 kg of aluminum fibers with a diameter of 30 μm and a length of 1 m are weighed, and then the metal surface is rinsed using a spraying device. Then, 1 L of acetone and 1 L of anhydrous ethanol are used in sequence for surface oil removal treatment, and natural drying is performed at room temperature. The prepared aluminum fibers are ready for use.

[0059] The dried aluminum fibers are laid into a net shape by gas-assisted dispersion, wherein the airflow speed is 20 m / s, the airflow temperature is maintained at 25°C, and the fiber concentration is 0.3 g / m 3 . The netting chamber pressure is maintained at 300 Pa, and then a pair of rollers is used for repeated rolling at a pressure of 30 MPa to obtain an aluminum fiber net with a porosity of 50%.

[0060] The aluminum fiber net is heated to 600°C at a heating rate of 10°C / min under the condition that the argon flow rate is 1.2 L / min and the hydrogen flow rate is 0.3 L / min. After stabilization for 10 min, acetylene gas is introduced at a flow rate of 1.2 L / min, and after maintaining for 3 min, the aluminum fiber net is cooled to room temperature under the condition that the argon flow rate is 1 L / min to obtain an aluminum fiber net coated with carbon nanotubes, which is a three-dimensional carbon-coated aluminum fiber current collector.

[0061] The process of assembling the battery using the three-dimensional carbon-coated aluminum fiber current collector prepared above is as follows:

[0062] First, the three-dimensional carbon-coated aluminum fiber current collector is cut into 10 m x 10 m, and then laser welding is used, with a laser wavelength of 1064 nm and a laser power of 150 W, to weld the aluminum tab with a thickness of 0.2 mm.

[0063] Then, the positive active material Na3MnTi(PO4)3 is mixed with the conductive agent acetylene black and polyvinylidene fluoride (pvdf) in a mass ratio of 93.5:3:3.5 to obtain a positive material slurry. The positive material slurry is coated on the current collector with the welded aluminum tab, and after oscillation until the slurry is completely filled, it is dried in an oven at 100°C for 12h to obtain a positive electrode sheet.

[0064] Finally, the positive electrode sheet is assembled with a metal sodium negative electrode and a NaPF6 (NP-005) electrolyte to form a sodium ion battery. The cycle performance of the assembled sodium ion battery is tested. The test results show that after 200 cycles at a rate of 1C, the discharge capacity is still 120 mAh·g -1 .

[0065] Comparative Example 1

[0066] The process of preparing a three-dimensional unsintered aluminum fiber current collector in this comparative example is as follows:

[0067] 0.7g of aluminum fibers with a diameter of 20μm and a length of 6mm are weighed, then the metal surface is rinsed using a spraying device, then the surface is deoiled using 100mL of acetone and 100mL of anhydrous ethanol in sequence, and dried naturally at room temperature.

[0068] The dried aluminum fibers are stirred in 100ml of ethylene glycol solution at 600r / min, and ultrasonically dispersed at a frequency of 40kHz for 3min. After being laid flat into a net shape, the surface ethylene glycol solution is removed with 200ml of deionized water, and dried naturally at room temperature. Then, a counter-roller machine is used to repeatedly roll at a pressure of 30MPa to obtain a three-dimensional unsintered aluminum fiber current collector with a porosity of 60%.

[0069] Comparative Example 2

[0070] The process of preparing a three-dimensional unsintered aluminum fiber current collector in this comparative example is as follows:

[0071] 0.7g of aluminum fibers with a diameter of 20μm and a length of 6mm are weighed, then the metal surface is rinsed using a spraying device, then the surface is deoiled using 100mL of acetone and 100mL of anhydrous ethanol in sequence, and dried naturally at room temperature.

[0072] The dried aluminum fibers were stirred in 100 ml of ethylene glycol solution at 600 r / min and ultrasonically dispersed at a frequency of 40 kHz for 3 minutes. After being spread into a mesh, the ethylene glycol solution on the surface was removed with 200 ml of deionized water. The fibers were dried naturally at room temperature and then repeatedly rolled at a pressure of 30 MPa using a double-roller machine to obtain an aluminum fiber mesh with a porosity of 60%.

[0073] The calcination treatment was carried out at 650°C in a circulating argon-hydrogen environment (hydrogen content was 5%) for 5 hours, with a heating rate of 10°C / min, to obtain a three-dimensional non-carbon-coated sintered aluminum fiber current collector.

[0074] The resistivity of the current collectors prepared in Example 1 and Comparative Examples 1-2 was compared, and the results were as follows: Figure 1 As shown by Figure 1 It can be seen that the resistivity of the aluminum fiber current collector without sintering treatment (Comparative Example 1) is 2 times and 4 times that of the aluminum fiber current collector without carbon coating but sintering treatment (Comparative Example 2) and the aluminum fiber current collector with carbon coating and sintering treatment (Example 1), respectively. This fully demonstrates that sintering and carbon coating treatment can effectively reduce the resistivity of the aluminum fiber current collector.

[0075] The above description is merely a preferred embodiment of the present invention. Given that those skilled in the art can make appropriate changes and modifications to the above embodiments, the present invention is not limited to the specific embodiments described above. Some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for producing a three-dimensional carbon-coated aluminum fiber current collector, characterized by, The specific steps are as follows: (1) 0.35 g of aluminum fibers with a diameter of 12 μm and a length of 10 mm are weighed, then the metal surface is washed using a spraying device, then surface oil removal treatment is performed using 100 mL of acetone and 100 mL of anhydrous ethanol in sequence, and natural drying is performed at room temperature, for standby; (2) the dried aluminum fibers are stirred in 100 ml of ethylene glycol solution at 600 r / min, and ultrasonic dispersion is performed at a frequency of 40 kHz for 3 min, then the surface ethylene glycol solution is removed using 200 ml of deionized water, and natural drying is performed at room temperature, then a pair of rollers is used to repeatedly roll at a pressure of 10 MPa, to obtain an aluminum fiber net with a porosity of 80%; (3) 0.1576 g of tris(hydroxy)aminomethane is dissolved in 100 mL of deionized water, and a 0.5M HCl solution is used to adjust the pH to 8.5, then 0.1 g of dopamine hydrochloride is added, the solution is stirred and dissolved, then the aluminum fiber net is immersed in the solution for reaction, and is left to stand for 24 h to form a polydopamine coating layer, then the aluminum fiber net is taken out, washed with deionized water, and naturally dried at room temperature, for standby; the dried polydopamine-coated aluminum fiber net is calcined at 650℃ in a flowing argon-hydrogen gas environment with a hydrogen content of 10% for 5 h, wherein the heating rate is 5℃ / min, to obtain a three-dimensional carbon-coated aluminum fiber current collector; The thickness of the current collector is 3-200 μm, and the thickness of the carbon coating layer is 10-1000 nm.

2. Use of the three-dimensional carbon-coated aluminum fiber current collector obtained by the production method according to claim 1, characterized in that, Preparation for a lithium ion battery, a sodium ion battery, or a zinc ion battery.

Images