Aluminum foil and aluminum fiber felt composite current collector and continuous preparation method and application thereof

Abstract

The invention provides an aluminum foil and aluminum fiber felt composite current collector and a continuous preparation method and application thereof, and belongs to the technical field of electrode materials. The aluminum foil and the aluminum fiber felt are compounded, a composite material is obtained through continuous rolling, and the aluminum foil and aluminum fiber felt composite current collector is prepared through continuous sintering-rolling in a protective atmosphere. The prepared aluminum foil and aluminum fiber felt composite current collector has high tensile strength and a three-dimensional porous structure, and the electrochemical performance of an electrode is improved. The preparation method is simple and low in cost, continuous preparation can be achieved, and large-scale production is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode materials, and particularly relates to a composite current collector of aluminum foil and aluminum fiber felt, a continuous preparation method thereof, and an application thereof. Background Art

[0002] With the development of new energy technologies, the performance requirements for battery electrode materials are getting higher and higher. For example, traditional aluminum foil has good tensile strength but insufficient electrochemical performance. On the other hand, aluminum fiber felt has excellent electrochemical performance, but its tensile strength is low, it is difficult to bend, and it is inconvenient for transportation. Therefore, how to effectively solve the problems of insufficient tensile strength or poor electrochemical performance of traditional current collector materials is an urgent problem to be solved in the prior art. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a preparation method of a composite current collector of aluminum foil and aluminum fiber felt, which can prepare a composite current collector of aluminum foil and aluminum fiber felt with strong tensile strength and a three-dimensional porous structure, and improve the electrochemical performance of battery electrodes.

[0004] To achieve the above purpose, the present application provides the following technical solutions.

[0005] A continuous preparation method of a composite current collector of aluminum foil and aluminum fiber felt, comprising the following steps:

[0006] Step 1: Continuously roll-press the aluminum fiber felt and the aluminum foil to obtain a composite material;

[0007] Step 2: Sinter and compact the composite material obtained in Step 1 by continuous sintering-roll-pressing under a protective atmosphere to obtain the composite current collector of aluminum foil and aluminum fiber felt.

[0008] Preferably, the thickness of the aluminum foil in Step 1 is 1-20 μm, and the thickness of the aluminum fiber felt is 1-200 μm; the porosity of the aluminum fiber felt is 60-120 PPI.

[0009] Preferably, the aluminum fiber felt and the aluminum foil in Step 1 are double-layer composite or triple-layer composite.

[0010] More preferably, the double-layer composite is a direct fit of the aluminum fiber felt and the aluminum foil; the triple-layer composite is to sandwich the aluminum foil between two aluminum fiber felts for composite.

[0011] Preferably, the roll-pressing pressure in the continuous roll-pressing process in Step 1 is 1-50 MPa, and the rotational speed of the roll is 1-1.5 m / s.

[0012] Preferably, the protective atmosphere in Step 2 is a mixture of nitrogen and hydrogen or a mixture of argon and hydrogen.

[0013] More preferably, the volume ratio of hydrogen in the protective atmosphere is 5-10%.

[0014] Preferably, the sintering temperature in step two is 500-650 °C, and the sintering time is 5-30 min.

[0015] Preferably, the pressure of the roll pressing in step two is 1-50 MPa, and the rotational speed of the roller is 1-1.5 m / s.

[0016] Another object of the present invention is to provide a composite current collector of aluminum foil and aluminum fiber felt prepared by the above method.

[0017] The composite current collector of aluminum foil and aluminum fiber felt prepared by the present invention is used for preparing a battery, and the battery is a lithium-ion battery or a sodium-ion battery.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a composite current collector of aluminum foil and aluminum fiber felt and its continuous preparation method and application. The present invention composites aluminum foil and aluminum fiber felt, obtains a composite material through continuous roll pressing, and prepares a composite current collector of aluminum foil and aluminum fiber felt through continuous sintering-roll pressing under a protective atmosphere. The composite current collector of aluminum foil and aluminum fiber felt prepared by the present invention has strong tensile strength and a three-dimensional porous structure, which is beneficial to improving the electrochemical performance of the electrode. The preparation method of the present invention is simple, low in cost, and can be continuously prepared to achieve large-scale production. Description of the Drawings

[0020] Figure 1 It is a scanning electron microscope image of the composite current collector of aluminum foil and aluminum fiber felt in Example 1;

[0021] Figure 2 It is a cyclic performance graph of the lithium-ion battery assembled with the current collector in Example 1, Comparative Example 1, and Comparative Example 3;

[0022] Figure 3 It is a cyclic performance graph of the sodium-ion battery assembled with the current collector in Example 2, Comparative Example 2, and Comparative Example 4;

[0023] Figure 4 It is a comparison graph of the tensile strength of the current collector in Example 1, Comparative Example 1, and Comparative Example 3. Detailed Embodiments

[0024] The present invention provides a continuous preparation method of a composite current collector of aluminum foil and aluminum fiber felt, including the following steps:

[0025] Step one: Continuously roll press the aluminum fiber felt and the aluminum foil to obtain a composite material;

[0026] Step 2: Sinter and compact the composite material obtained in Step 1 under a protective atmosphere by continuous sintering-rolling to obtain the composite current collector of aluminum foil and aluminum fiber felt.

[0027] In some embodiments of the present invention, the thickness of the aluminum foil in Step 1 is 1-20 μm, preferably 10-20 μm; the thickness of the aluminum fiber felt is 1-200 μm, preferably 30-50 μm; the porosity of the aluminum fiber felt is 60-120 PPI.

[0028] In some embodiments of the present invention, the aluminum fiber felt and the aluminum foil in Step 1 are double-layer composite or triple-layer composite; more preferably, the double-layer composite is a direct fit of the aluminum fiber felt and the aluminum foil; the triple-layer composite is to sandwich the aluminum foil between two aluminum fiber felts for composite.

[0029] In some embodiments of the present invention, the rolling pressure during the continuous rolling in Step 1 is 1-50 MPa, preferably 10-20 MPa; the rotational speed of the roller is 1-1.5 m / s.

[0030] In some embodiments of the present invention, the protective atmosphere in Step 2 is a mixture of nitrogen and hydrogen or a mixture of argon and hydrogen; the volume ratio of hydrogen in the protective atmosphere is 5-10%.

[0031] In some embodiments of the present invention, the sintering temperature during sintering in Step 2 is 500-650 °C, preferably 600-650 °C; the sintering time is 5-30 min, preferably 5-10 min.

[0032] In some embodiments of the present invention, the rolling pressure in Step 2 is 1-50 MPa; preferably 10-20 MPa; the rotational speed of the roller is 1-1.5 m / s.

[0033] The present invention prepares a composite current collector of aluminum foil and aluminum fiber felt by the above method.

[0034] The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments. In the specific embodiments of the present invention, unless otherwise specified, the raw materials are all raw materials purchased conventionally in the market or raw materials prepared by conventional methods, and the methods are all conventional methods in the art.

[0035] Example 1

[0036] A continuous preparation method of a composite current collector of aluminum foil and aluminum fiber felt, the steps are as follows:

[0037] Step 1: Place the aluminum fiber felt (30μm, 80PPI) on the rough surface (roughness 3.4μm) of the single-ground aluminum foil (10μm thick), and combine them through continuous roll pressing technology to obtain a composite material. The roll pressing pressure is 10MPa, and the rotational speed of the roller is 1m / s;

[0038] Step 2: Under a protective atmosphere (argon-hydrogen mixture with a hydrogen volume fraction of 10%), subject the composite material obtained in Step 1 to sintering-roll pressing treatment through a continuous sintering device to obtain the aluminum foil and aluminum fiber felt composite current collector; the sintering temperature is 600°C, the sintering time is 10min, the roll pressing pressure is 10MPa, and the rotational speed is 1m / s.

[0039] Use the composite current collector prepared in Example 1 for the battery electrode and test its electrochemical performance.

[0040] Mix the positive electrode active material LiMnFePO 4 with the conductive agent acetylene black and the binder polyvinylidene fluoride (pvdf) in a mass ratio of 8:1:1 in an N-methylpyrrolidone solution to obtain a positive electrode material slurry. Coat the positive electrode material slurry on the composite current collector prepared in Example 1 that has been cut and welded with aluminum tabs. After oscillating until the slurry is completely filled, dry it in an oven at 100°C for 12h to obtain a positive electrode sheet. Assemble a lithium-ion battery with the prepared positive electrode sheet, a lithium metal negative electrode, and a lithium-ion secondary electrolyte (LB-275), and test the cycling performance of the assembled lithium-ion battery.

[0041] Example 2

[0042] A continuous preparation method for an aluminum foil and aluminum fiber felt composite current collector, with the steps the same as in Example 1.

[0043] Use the composite current collector prepared in Example 2 for the battery electrode and test its electrochemical performance.

[0044] The positive electrode active material NaMn 0.33 Fe 0.33 Ni 0.33 O 2Mix the cathode material with carbon black as the conductive agent and polyvinylidene fluoride (PVDF) as the binder in a mass ratio of 8:1:1 in N-methylpyrrolidone solution to obtain a cathode material slurry. Coat the cathode material slurry on the composite current collector prepared in Example 2 that has been cut and welded with an aluminum tab. After oscillating until the slurry is completely filled, dry it in an oven at 100 °C for 12 h to obtain a cathode sheet. Mix the anode active material hard carbon with carbon black as the conductive agent and polyvinylidene fluoride (PVDF) as the binder in a mass ratio of 8:1:1 in N-methylpyrrolidone solution to obtain an anode material slurry. Coat the anode material slurry on the composite current collector prepared in Example 2 that has been cut and welded with an aluminum tab. After oscillating until the slurry is completely filled, dry it in an oven at 100 °C for 12 h to obtain an anode sheet. The prepared cathode sheet, anode sheet and electrolyte NaClO 4 Assemble a sodium-ion battery in the order of negative electrode case - cathode sheet - separator - anode sheet - gasket - spring sheet - electrolyte - positive electrode case, and test the cycling performance of the assembled sodium-ion battery.

[0045] Example 3

[0046] A continuous preparation method of an aluminum foil and aluminum fiber felt composite current collector is as follows:

[0047] Step 1: Clamp two aluminum fiber felts (50 μm, 85 PPI) on both sides of a double-ground aluminum foil (20 μm thick, surface roughness 3.4 μm), and combine them by continuous rolling technology to obtain a composite material. The rolling pressure is 20 MPa, and the rotational speed of the roller is 1.1 m / s;

[0048] Step 2: Under a protective atmosphere (argon-hydrogen mixture with a hydrogen volume fraction of 5%), sinter and roll the composite material obtained in Step 1 through a continuous sintering device to obtain the aluminum foil and aluminum fiber felt composite current collector; the sintering temperature is 650 °C, the sintering time is 5 min, the rolling pressure is 15 MPa, and the rotational speed is 1.1 m / s.

[0049] Use the composite current collector prepared in Example 3 for battery electrodes, and test its electrochemical performance. The preparation methods of the electrodes and the battery are the same as those in Example 1.

[0050] Example 4

[0051] A continuous preparation method of an aluminum foil and aluminum fiber felt composite current collector is as follows:

[0052] Step 1: Clamp two aluminum fiber felts (50 μm, 90 PPI) on both sides of a double-ground aluminum foil (20 μm thick, surface roughness 3.4 μm), and combine them by continuous rolling technology to obtain a composite material. The rolling pressure is 20 MPa, and the rotational speed of the roller is 1.1 m / s;

[0053] Step 2: Under a protective atmosphere (argon-hydrogen mixture with a hydrogen volume fraction of 10%), sinter and roll the composite material obtained in Step 1 through a continuous sintering device to obtain the aluminum foil and aluminum fiber felt composite current collector; the sintering temperature is 650°C, the sintering time is 5 minutes, the pressure of rolling is 20 MPa, and the rotation speed is 1.1 m / s.

[0054] Use the composite current collector prepared in Example 4 for the battery electrode, and test its electrochemical performance. The test method is the same as that in Example 2.

[0055] Comparative Example 1

[0056] Use an aluminum foil (12 μm thick) as the current collector without any composite treatment.

[0057] Test its electrochemical performance. The test method is the same as that in Example 1.

[0058] Comparative Example 2

[0059] Use an aluminum foil (12 μm thick) as the current collector without any composite treatment.

[0060] Test its electrochemical performance. The test method is the same as that in Example 2.

[0061] Comparative Example 3

[0062] Use an aluminum fiber felt (50 μm thick, 80 PPI) as the current collector without any composite treatment.

[0063] Test its electrochemical performance. The test method is the same as that in Example 1.

[0064] Comparative Example 4

[0065] Use an aluminum fiber felt (50 μm thick, 80 PPI) as the current collector without any composite treatment.

[0066] Test its electrochemical performance. The test method is the same as that in Example 2.

[0067] The scanning electron microscope image of the aluminum foil and aluminum fiber felt composite current collector in Example 1 is as Figure 1 , and from Figure 1 it can be seen that after the sintering-rolling treatment, some fibers have been sintered into one body, and the aluminum fibers on the surface of the composite aluminum fiber felt have a good sintering structure, which can increase the tensile strength of the fibers.

[0068] Figure 2 is the cycle performance diagram of the lithium-ion battery assembled with the aluminum foil and aluminum fiber felt composite current collector prepared in Example 1, the aluminum foil current collector without any composite treatment in Comparative Example 1, and the single aluminum fiber felt current collector without any composite treatment in Comparative Example 3; from Figure 2It can be known that the initial discharge capacity of the composite aluminum fiber current collector prepared in Example 1 is 138 mAh g at a current density of 2C -1 , and the capacity retention rate after 100 cycles is 98%. However, the initial discharge capacity of the traditional aluminum foil current collector in Comparative Example 1 is only 104 mAh g -1 , and the discharge retention rate is 95%. The initial discharge capacity of the aluminum fiber felt current collector in Comparative Example 3 is 120 mAh g -1 , and the capacity retention rate is 97%. It can be seen that the composite current collector has better initial lithium battery discharge capacity and capacity retention rate.

[0069] Figure 3 Figure showing the cycling performance of the sodium-ion batteries assembled with the aluminum foil and aluminum fiber felt composite current collector prepared in Example 2, the traditional aluminum foil current collector without any composite treatment in Comparative Example 2, and the single aluminum fiber felt current collector without any composite treatment in Comparative Example 4; from Figure 3 It can be known that the initial discharge capacity of the composite aluminum fiber current collector prepared in Example 2 is 99 mAh g at a current density of 2C -1 , and the capacity retention rate after 1000 cycles is 95%. However, the initial discharge capacity of the traditional aluminum foil current collector in Comparative Example 2 is only 80 mAh g -1 , and the discharge retention rate after 750 cycles is 62.5%. The initial discharge capacity of the aluminum fiber felt current collector in Comparative Example 4 is 89 mAh g -1 , and the capacity retention rate is 94%. It can be seen that the composite current collector has better initial sodium battery discharge capacity and capacity retention rate.

[0070] Figure 4 Figure showing the comparison of the tensile strengths of the aluminum foil and aluminum fiber felt composite current collector prepared in Example 1, the traditional aluminum foil current collector without any composite treatment in Comparative Example 1, and the single aluminum fiber felt current collector in Comparative Example 3; from Figure 4 It can be known that the tensile strength of the composite current collector prepared in Example 1 is 65 MPa, while the tensile strength of the aluminum foil in Comparative Example 1 is 58 MPa, and the tensile strength of the aluminum fiber in Comparative Example 3 is 11 MPa, indicating that the composite current collector has better tensile strength.

[0071] In summary, compared with the single aluminum fiber felt current collector without any composite treatment and the traditional aluminum foil current collector without any composite treatment in the comparative examples, the aluminum foil and aluminum fiber felt composite current collector prepared by the method provided by the present invention in the examples has strong tensile strength and a three-dimensional porous structure, which is beneficial to improving the electrochemical performance of the electrode.

[0072] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A continuous preparation method of an aluminum foil and aluminum fiber felt composite current collector, characterized in that: The following steps are involved: Step 1: Continuously rolling the aluminum fiber felt and the aluminum foil to obtain a composite material; Step 2: The composite material obtained in step 1 is subjected to sintering and compacting treatment by continuous sintering-rolling in a protective atmosphere to obtain the aluminum foil and aluminum fiber felt composite current collector.

2. The continuous preparation method of the aluminum foil and aluminum fiber felt composite current collector according to claim 1, characterized in that: In step 1, the thickness of the aluminum foil is 1-20 μm, the thickness of the aluminum fiber felt is 1-200 μm; the porosity of the aluminum fiber felt is 60-120 PPI.

3. The continuous preparation method of the aluminum foil and aluminum fiber felt composite current collector according to claim 1, characterized in that: In step 1, the aluminum fiber felt and the aluminum foil are double-layered or triple-layered.

4. The continuous preparation method of the aluminum foil and aluminum fiber felt composite current collector according to claim 3, characterized in that: The double-layer composite is a direct bonding of aluminum fiber felt and aluminum foil; the three-layer composite is a composite of two pieces of aluminum fiber felt sandwiching aluminum foil.

5. The continuous preparation method of the aluminum foil and aluminum fiber felt composite current collector according to claim 1, characterized in that: In the continuous rolling process of step 1, the rolling pressure is 1-50 MPa, and the rotation speed of the roller is 1-1.5 m / s.

6. The continuous preparation method of the aluminum foil and aluminum fiber felt composite current collector according to claim 1, characterized in that: In step 2, the protective atmosphere is a mixture of nitrogen and hydrogen or a mixture of argon and hydrogen; the volume proportion of hydrogen in the protective atmosphere is 5-10%.

7. The method for continuously preparing a composite current collector of aluminum foil and aluminum fiber felt according to claim 1, characterized in that: The sintering temperature during the sintering in step 2 is 500-650° C., and the sintering time is 5-30 min.

8. The method for continuously preparing a composite current collector of aluminum foil and aluminum fiber felt according to claim 1, characterized in that: The roller pressing pressure in step 2 is 1-50 MPa, and the roller rotation speed is 1-1.5 m / s.

9. Aluminum foil and aluminum fiber felt composite current collector prepared according to the continuous preparation method of aluminum foil and aluminum fiber felt composite current collector according to any one of claims 1 to 8.

10. The use of the aluminum foil and aluminum fiber felt composite current collector according to claim 9, characterized in that: The aluminum foil and aluminum fiber felt composite current collector is used to prepare a battery, and the battery is a lithium ion battery or a sodium ion battery.

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