Continuous preparation method of large-area single crystal (100) copper foil

Abstract

The present invention discloses a continuous preparation method of a large-area (100) single-crystal copper foil, wherein a polycrystalline copper foil is connected to a roll-to-roll device, a carbon-based substrate is placed under the copper foil, and a large-area (100) single-crystal copper foil is prepared by applying stress during a heat treatment process in a reducing / protective atmosphere and in an environment with a temperature gradient. The present invention applies stress to the copper foil for the first time, accurately controls its strain energy, and makes the strain energy the main influencing factor of grain boundary migration and lattice rotation, thereby achieving the control of the strain energy dominating in the growth process of the single-crystal copper foil, and a large-area (100) single-crystal copper foil can be prepared by heat treatment in a reducing atmosphere.

Description

Technical Field

[0001] The invention relates to the field of material science and electrochemical technology, and in particular to a continuous preparation method for large-area (100) single-crystal copper foil. Background Art

[0002] Single crystal copper foil has important application prospects in many fields such as selective catalysis, battery current collector, power transmission, and crystal epitaxial growth due to its excellent intrinsic electrical and thermal conductivity and single crystal orientation.

[0003] The traditional method for preparing single crystal copper foil is relatively complicated. First, a single crystal copper ingot is prepared by a pulling method, and then a single crystal copper foil is obtained by mechanical cutting. This method has high energy consumption, high cost, single crystal orientation, is difficult to prepare on a large scale, and the thickness cannot be controlled to the micron level. The emerging method for preparing single crystal copper foil promotes the rotation of the lattice and the migration of the grain boundaries through heat treatment, thereby obtaining a single crystal copper foil that exposes the crystal plane with the lowest Gibbs free energy. At present, there are literature reports on the successful preparation of single crystal copper foil, such as CN115896912A discloses a method and equipment for preparing a large area single crystal copper foil, which prepares a large area (111) single crystal copper foil by heat treatment. However, this method cannot prepare a large area single crystal (100) copper foil. Summary of the invention

[0004] The purpose of the present invention is to provide a continuous preparation method for large-area (100) single crystal copper foil in view of the technical defect that only the (111) crystal plane can be prepared controllably in the prior art.

[0005] The technical solution adopted to achieve the purpose of the present invention is:

[0006] A continuous preparation method for large-area single-crystal copper foil comprises connecting a polycrystalline copper foil to a roll-to-roll device, placing a carbon-based substrate under the copper foil, and preparing a large-area (100) single-crystal copper foil by applying stress during a heat treatment process in a reducing / protective atmosphere and in an environment with a temperature gradient.

[0007] The present invention discovers for the first time that stress needs to be applied to the copper foil to control the strain energy to dominate during the growth of the single crystal copper foil, so that the strain energy becomes the main influencing factor of grain boundary migration and lattice rotation, in order to prepare a large area of ​​(100) single crystal copper foil.

[0008] In the above technical solution, the thickness of the polycrystalline copper foil is 10-100 microns.

[0009] In the above technical solution, the temperature gradient is 1-10°C / cm.

[0010] In the above technical solution, the applied stress ranges from 80 to 100 N / cm2 (cross-sectional area).

[0011] In the above technical solution, the preparation method comprises the following steps:

[0012] Step 1, pre-treating the polycrystalline copper foil to remove an organic layer, an oxide layer and impurities;

[0013] Step 2, connecting the pretreated polycrystalline copper foil to a roll-to-roll device and sending it into a multi-temperature zone tube furnace, with the copper foil supported by a carbon-based substrate placed on a corundum plate or a quartz plate;

[0014] Step 3, evacuate the interior of the multi-temperature zone tubular furnace to a vacuum, and introduce reducing / protective gas to a predetermined pressure;

[0015] Step 4, heating the copper foil while continuously introducing reducing / protective gas until the maximum temperature at the center of the copper foil is 980-1070°C, applying stress, maintaining for 10-30 minutes, and at the same time keeping warm for 4-15 hours, and naturally cooling to room temperature to obtain (100) single crystal copper foil.

[0016] In the above technical solution, the pretreatment method in step 1 is: immerse the polycrystalline copper foil in dilute sulfuric acid or dilute hydrochloric acid, then wash it alternately with deionized water and anhydrous ethanol or anhydrous methanol or anhydrous acetone, and dry it with cold air or wipe it dry with dust-free paper. Preferably, the concentration of the dilute sulfuric acid or dilute hydrochloric acid is 0.2 to 1 mol / L.

[0017] In the above technical solution, the carbon-based substrate in step 2 can be commercial carbon paper, carbon cloth, carbon felt, or a flat substrate made from carbon materials through a series of methods such as pressing or film drawing. The multi-temperature zone tubular furnace is a tubular furnace with three or more temperature zones.

[0018] In the above technical solution, the predetermined pressure in step 3 is 1 atmosphere.

[0019] In the above technical solution, in step 3 and step 4, the reducing / protecting gas is hydrogen-argon or hydrogen-nitrogen mixed gas, the hydrogen accounts for 10-50%, and the total gas flow rate is 100-800sccm.

[0020] In the above technical solution, the polycrystalline copper foil is fed into a tube furnace by a roll-to-roll device and stress is applied, and the (100) single crystal copper foil obtained in step 4 can reach meter level;

[0021] The size of the (100) single crystal copper foil obtained in step 4 can be adjusted by improving the design of the multi-temperature zone tubular furnace.

[0022] In the above technical solution, a feeding reel and a collecting reel are provided in the multi-temperature zone tubular furnace. The feeding reel is used to wind the polycrystalline copper foil, and the collecting reel is used to wind the prepared single crystal copper foil. The feeding reel and the collecting reel are respectively located on the left and right sides of the heating zone. After the stress is applied, the copper foil can be moved forward one temperature zone. The moving speed of the copper foil is 0.1-1 cm / min, so as to realize the continuous preparation of meter-level (100) single crystal copper foil.

[0023] In another aspect of the present invention, a device for continuously preparing large-area (100) single crystal copper foil comprises a multi-temperature zone tubular furnace and a feeding reel and a receiving reel arranged in the multi-temperature zone tubular furnace, wherein the feeding reel is used for winding the polycrystalline copper foil and can be fixed or fed by program control, and the receiving reel is used for winding the single crystal copper foil and can control the rotation speed and clockwise or counterclockwise direction by program, and stress is applied to the copper foil by adjusting the tightening of the reel, and the stress magnitude can be accurately controlled in real time by a digital display screen, the feeding reel and the receiving reel are respectively located on the left and right sides of a heating zone, and the heating zone comprises at least three temperature zones, a quartz plate is provided at the bottom of the heating zone, a carbon-based substrate is fixedly provided on the quartz plate or the corundum plate, and when the copper foil moves, it is suspended in the air or the bottom surface is in contact with the carbon-based substrate.

[0024] The method and device for preparing single crystal copper foil of the present invention can also be used to prepare other metal single crystal foils, wherein the other metal foils, in addition to copper foil, can also include platinum foil, cobalt foil, nickel foil, nickel-platinum alloy, copper-nickel alloy and other foils.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention applies stress to the copper foil for the first time and precisely controls its strain energy, making the strain energy the main influencing factor of grain boundary migration and lattice rotation, thereby achieving the control of strain energy dominating the growth process of the single crystal copper foil. A large area of ​​(100) single crystal copper foil can be prepared by heat treatment in a reducing atmosphere.

[0027] 2. The present invention adopts a tube furnace with roll-to-roll function to realize controllable preparation of large-area (100) single crystal copper foil. The repeatability is high, and both the equipment and the single crystal copper foil can be mass-produced, which is convenient for promotion and application.

[0028] 3. The original commercial polycrystalline copper foil used in the present invention is easy to obtain, cheap and abundant, the single crystal process is simple to operate, and the product purity is high. Compared with the traditional pulling method, it reduces energy consumption and reduces the pollution introduced by the outside world during the preparation process.

[0029] 4. The method and device involved in the present invention are universally applicable to the preparation of various single crystal metal foils. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the XRD pattern of the commercial polycrystalline copper foil used in the present invention;

[0031] Figure 2 is the XRD pattern of the (100) single crystal copper foil obtained by the present invention;

[0032] Figure 3 is the inverse pole figure of the (100) single crystal copper foil of Example 1 of the present invention;

[0033] Figure 4 This is the XRD diagram of the polycrystalline copper foil of Comparative Example 1 of the present invention;

[0034] Figure 5 is the XRD diagram of the polycrystalline copper foil of Comparative Example 2 of the present invention;

[0035] Figure 6 is the XRD diagram of the polycrystalline copper foil of Comparative Example 3 of the present invention;

[0036] Figure 7 is the XRD pattern of the (100) single crystal copper foil of Example 2 of the present invention;

[0037] Figure 8 is the inverse pole figure of the (100) single crystal copper foil of Example 2 of the present invention;

[0038] Fig. 9 A schematic diagram of the internal structure of a multi-temperature zone tubular furnace with roll-to-roll function according to Example 3 of the present invention;

[0039] Fig.10 is the XRD pattern of the (100) single crystal copper foil of Example 4 of the present invention;

[0040] Fig.11 : is the inverse pole figure of the (100) single crystal copper foil of Example 4 of the present invention. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] Example 1

[0043] A continuous preparation method for a large-area (100) single-crystal copper foil comprises the following steps:

[0044] Step 1: 10 μm thick commercial polycrystalline copper foil (XRD pattern as shown in Figure 1 As shown in the figure, soak it in 1 mol / L dilute hydrochloric acid, then wash it with deionized water and anhydrous acetone, and blow dry it with cold air;

[0045] Step 2, connected to the roll-to-roll device and sent into a three-temperature zone tube furnace, with the copper foil supported by a carbon cloth placed on a quartz plate;

[0046] Step 3, evacuate the interior of the tube furnace described in step 2, introduce reducing gas (hydrogen-argon mixture, hydrogen accounting for 40%) until the pressure of the tube furnace is 1 atmosphere, and set the temperature values ​​of the three temperature zones to 700 degrees Celsius, 1050 degrees Celsius and 700 degrees Celsius, respectively, so that the position of the copper foil reaches a predetermined temperature gradient;

[0047] Step 4: Continue to introduce reducing gas (hydrogen-argon mixture, hydrogen accounts for 40%) into the tube furnace of step 3 at a gas flow rate of 400 sccm. After heating the copper foil to 1050 degrees Celsius, apply 80N / cm 2 The stress was maintained for 10 minutes. The heating was maintained for 10 hours and then cooled naturally to room temperature to obtain a (100) single crystal copper foil.

[0048] Figure 2 : This is the XRD diagram of the (100) single crystal copper foil obtained in Example 1. It can be seen from the figure that the copper foil after heat treatment has only one peak, which corresponds to the (200) crystal plane of copper and belongs to the {100} crystal plane family. Figure 3 : is the inverse pole figure of the (100) single crystal copper foil obtained in Example 1. It can be seen from the figure that the copper foil obtained after heat treatment corresponds to the copper (100) crystal plane and no grain boundary exists.

[0049] Comparative Example 1

[0050] This comparative example is different from Example 1 in that no carbon paper is used, and other conditions are consistent with those of Example 1, specifically comprising the following steps:

[0051] Step 1, immerse a 10 μm thick commercial polycrystalline copper foil in 1 mol / L dilute hydrochloric acid, then wash it with deionized water and anhydrous acetone, and blow dry it with cold air;

[0052] Step 2, connected to the roll-to-roll device and sent into a three-temperature zone tube furnace, with a quartz plate as support under the copper foil;

[0053] Step 3, evacuate the interior of the tube furnace described in step 2, introduce reducing gas (hydrogen-argon mixture, hydrogen accounting for 40%) until the pressure of the tube furnace is 1 atmosphere, and set the temperature values ​​of the three temperature zones to 700 degrees Celsius, 1050 degrees Celsius and 700 degrees Celsius, respectively, so that the position of the copper foil reaches a predetermined temperature gradient;

[0054] Step 4: Continue to introduce reducing gas (hydrogen-argon mixture, hydrogen accounts for 40%) into the tube furnace of step 3 at a gas flow rate of 400 sccm. After heating the copper foil to 1050 degrees Celsius, apply 80N / cm 2The stress was maintained for 10 minutes. The heating was maintained for 10 hours and naturally cooled to room temperature to obtain a polycrystalline copper foil.

[0055] Figure 4 The XRD diagram of the polycrystalline copper foil obtained in Comparative Example 1 shows that the copper foil obtained after heat treatment has multiple crystal planes and is a polycrystalline copper foil. Compared with Example 1, Comparative Example 1 proves the necessity of carbon paper for preparing (100) single crystal copper foil.

[0056] Comparative Example 2

[0057] This comparative example is different from Example 1 in that the stress applied is different from that in Example 1, and other conditions are the same, and specifically includes the following steps:

[0058] Step 1, immerse a 10 μm thick commercial polycrystalline copper foil in 1 mol / L dilute hydrochloric acid, then wash it with deionized water and anhydrous acetone, and blow dry it with cold air;

[0059] Step 2, connected to the roll-to-roll device and sent into a three-temperature zone tube furnace, with the copper foil supported by a carbon cloth placed on a quartz plate;

[0060] Step 3, evacuate the interior of the tube furnace described in step 2, introduce reducing gas (hydrogen-argon mixture, hydrogen accounting for 40%) until the pressure of the tube furnace is 1 atmosphere, and set the temperature values ​​of the three temperature zones to 700 degrees Celsius, 1050 degrees Celsius and 700 degrees Celsius, respectively, so that the position of the copper foil reaches a predetermined temperature gradient;

[0061] Step 4: Continue to introduce reducing gas (hydrogen-argon mixture, hydrogen accounts for 40%) into the tube furnace of step 3 at a gas flow rate of 400 sccm. After heating the copper foil to 1050 degrees Celsius, apply 40N / cm 2 The stress was maintained for 10 minutes. The heating was maintained for 10 hours and naturally cooled to room temperature to obtain a polycrystalline copper foil.

[0062] Figure 5 The XRD diagram of the polycrystalline copper foil obtained in Comparative Example 2 shows that there are still many crystal planes on the surface of the copper foil after heat treatment, which is a polycrystalline copper foil. Compared with Example 1, it is proved that changing the stress applied to the copper foil will affect the dominant relationship of the crystal plane free energy, and then affect the growth of the (100) single crystal copper foil. It is concluded that appropriate stress is crucial to the growth of the (100) single crystal copper foil.

[0063] Comparative Example 3

[0064] This comparative example is different from Example 1 in that the stress applied is different from that in Example 1, and other conditions are the same, and specifically includes the following steps:

[0065] Step 1, immerse a 10 μm thick commercial polycrystalline copper foil in 1 mol / L dilute hydrochloric acid, then wash it with deionized water and anhydrous acetone, and blow dry it with cold air;

[0066] Step 2, connected to the roll-to-roll device and sent into a three-temperature zone tube furnace, with the copper foil supported by a carbon cloth placed on a quartz plate;

[0067] Step 3, evacuate the interior of the tube furnace described in step 2, introduce reducing gas (hydrogen-argon mixture, hydrogen accounting for 40%) until the pressure of the tube furnace is 1 atmosphere, and set the temperature values ​​of the three temperature zones to 700 degrees Celsius, 1050 degrees Celsius and 700 degrees Celsius, respectively, so that the position of the copper foil reaches a predetermined temperature gradient;

[0068] Step 4: Continue to introduce reducing gas (hydrogen-argon mixture, hydrogen accounts for 40%) into the tube furnace of step 3 at a gas flow rate of 400 sccm. After heating the copper foil to 1050 degrees Celsius, apply 150N / cm 2 The stress was maintained for 10 minutes. The heating was maintained for 10 hours and naturally cooled to room temperature to obtain a polycrystalline copper foil.

[0069] Figure 6 The XRD diagram of the polycrystalline copper foil obtained in Comparative Example 3 shows that there are still many crystal planes on the surface of the copper foil after heat treatment, which is a polycrystalline copper foil. Compared with Example 1, it is proved that excessive stress will cause a certain degree of tensile deformation of the copper foil, thereby affecting the growth of (100) single crystal copper foil. It is concluded that appropriate stress is crucial to the growth of (100) single crystal copper foil.

[0070] Example 2

[0071] A method for continuously preparing a large-area single-crystal copper foil comprises the following steps:

[0072] Step 1, immerse a 30 μm thick commercial polycrystalline copper foil in 1 mol / L dilute sulfuric acid, then wash it with deionized water and anhydrous methanol, and blow dry it with cold air;

[0073] Step 2, connecting the copper foil obtained in step 1 to a roll-to-roll device and sending it into a three-temperature zone tube furnace, with carbon paper placed on a quartz plate as support below the copper foil;

[0074] Step 3, evacuate the interior of the tube furnace described in step 2, introduce reducing gas (hydrogen-nitrogen mixture, hydrogen accounts for 30%) until the pressure of the tube furnace is 1 atmosphere, and set the temperature values ​​of the three temperature zones to 600 degrees Celsius, 1045 degrees Celsius and 600 degrees Celsius, respectively, so that the position of the copper foil reaches a predetermined temperature gradient;

[0075] Step 4: Continue to introduce reducing gas (hydrogen-argon mixture, hydrogen accounts for 40%) into the tube furnace of step 3 at a gas flow rate of 400 sccm. After heating the copper foil to 1050 degrees Celsius, apply 100N / cm2 of pressure to the copper foil through a roll-to-roll device. 2 The stress was maintained for 15 minutes. The heating was maintained for 8 hours and then cooled naturally to room temperature to obtain a (100) single crystal copper foil.

[0076] Figure 7 : This is the XRD diagram of the (100) single crystal copper foil obtained in Example 2. It can be seen from the figure that the copper foil after heat treatment has only one peak, which corresponds to the (200) crystal plane of copper and belongs to the {100} crystal plane family. Figure 8 : is the inverse pole figure of the (100) single crystal copper foil obtained in Example 2. It can be seen from the figure that the copper foil obtained after heat treatment corresponds to the copper (100) crystal plane and there is no grain boundary.

[0077] Example 3

[0078] like Fig. 9 As shown, a device for continuously preparing large-area (100) single-crystal copper foil comprises a sealed multi-temperature zone tubular furnace consisting of a heating zone 1 and a feeding reel 2 and a receiving reel 3 arranged on both sides of the heating zone 1, and the chamber where the reel is located is connected to the heating zone 1. The feeding reel 2 is used to wind the polycrystalline copper foil 4, and can be fixed or fed by program control. The receiving reel 3 is used to wind the single-crystal copper foil, and the rotation speed and clockwise and counterclockwise directions can be controlled by the program. Stress is applied to the copper foil by adjusting the tightening of the reel, and the stress magnitude can be accurately controlled in real time through a digital display screen. The heating zone 1 comprises at least three temperature zones, and a corundum plate 5 is provided at the bottom of the heating zone. Carbon paper 6 is fixed on the quartz plate or corundum plate. When the copper foil moves, it is suspended in the air or the bottom surface is in contact with the carbon-based substrate.

[0079] Preferably, the lengths of the corundum plate 5 and the carbon paper 6 are equal to the length of the heating zone 1 .

[0080] Example 4

[0081] This embodiment uses the equipment described in Example 3 to prepare a large-area (100) single-crystal copper foil. A continuous preparation method for a large-area (100) single-crystal copper foil includes the following steps:

[0082] Step 1, immerse a 10 μm thick commercial polycrystalline copper foil in 1 mol / L dilute sulfuric acid, then wash it with deionized water and anhydrous ethanol, and blow dry it with cold air;

[0083] Step 2, winding the polycrystalline copper foil obtained in step 1 on the feeding reel 1, so that part of the copper foil is supported by carbon paper and quartz plate and then connected to the collecting reel 2;

[0084] Step 3, evacuate the interior of the tube furnace described in step 2, introduce reducing gas (hydrogen-argon mixture, hydrogen accounts for 30%) until the pressure of the tube furnace is 1 atmosphere, and set the temperature values ​​of the three temperature zones to 700 degrees Celsius, 1050 degrees Celsius and 700 degrees Celsius, respectively, so that the position of the copper foil reaches a predetermined temperature gradient;

[0085] Step 4: Continue to introduce reducing gas (hydrogen-argon mixture, hydrogen accounting for 40%) into the tubular furnace of step 3 at a gas flow rate of 500 sccm, and heat the copper foil to 1050 degrees Celsius.

[0086] Step 5: Apply 90N / cm2 of pressure to the copper foil through a roll-to-roll device. 2 The stress was maintained for 10 minutes and the heating was maintained for 4 hours;

[0087] Step 6, after heating for 4 hours, set the copper foil moving speed described in step 2 to 1 cm / min and move 50 cm.

[0088] Step 7, repeating steps 5 and 6 until a roll of copper foil is completely transformed, and naturally cooling to room temperature to obtain meter-level (100) single crystal copper foil.

[0089] Fig.10 : This is the XRD diagram of the (100) single crystal copper foil obtained in Example 4. It can be seen from the figure that the copper foil after heat treatment has only one peak, which corresponds to the (200) crystal plane of copper and belongs to the {100} crystal plane family. Fig.11 : is the inverse pole figure of the (100) single crystal copper foil obtained in Example 4. It can be seen from the figure that the copper foil obtained after heat treatment corresponds to the copper (100) crystal plane and there is no grain boundary.

[0090] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A continuous preparation method for large-area (100) single-crystal copper foil, characterized in that: The commercial polycrystalline copper foil is connected to a roll-to-roll device, a carbon-based substrate is placed under the commercial polycrystalline copper foil, and stress is applied during the heat treatment process in a reducing / protective atmosphere and in an environment with a temperature gradient, so that the strain energy is controlled to dominate the growth process of the single crystal copper foil, making the strain energy the main influencing factor of grain boundary migration and lattice rotation, thereby preparing a large area (100) single crystal copper foil; The following steps are involved: Step 1, pre-treating the commercial polycrystalline copper foil to remove the organic layer, oxide layer and impurities; Step 2, the pre-treated commercial polycrystalline copper foil is connected to a roll-to-roll device and sent into a multi-temperature zone tube furnace, with the copper foil supported by a carbon-based substrate placed on a corundum plate or a quartz plate; Step 3, evacuate the interior of the multi-temperature zone tubular furnace to a vacuum, and introduce reducing / protective gas to a predetermined pressure; Step 4, under the condition of continuously introducing reducing / protective gas, the copper foil is heated to a maximum temperature of 980-1070°C at the center of the copper foil, and the reel of the roll-to-roll device is tightened to apply a stress of 80-100 N per square centimeter of cross-sectional area, maintained for 10-30 minutes, and at the same time kept warm for 4-15 hours, and naturally cooled to room temperature to obtain a (100) single crystal copper foil.

2. The preparation method according to claim 1, characterized in that: The commercial polycrystalline copper foil has a thickness of 10-100 μm.

3. The preparation method according to claim 1, characterized in that: The temperature gradient is 1-10°C per centimeter.

4. The preparation method according to claim 1, characterized in that: The applied stress ranged from 80-100 N per square centimeter of cross-sectional area.

5. The preparation method according to claim 1 is characterized in that the pretreatment method described in step 1 is to immerse the commercial polycrystalline copper foil in dilute sulfuric acid or dilute hydrochloric acid, then wash it alternately with deionized water and anhydrous ethanol or anhydrous methanol or anhydrous acetone, blow it dry with cold air or dry it with dust-free paper, and the concentration of the dilute sulfuric acid or dilute hydrochloric acid is 0.2~1mol / L.

6. The preparation method according to claim 1 is characterized in that the carbon-based substrate described in step 2 is commercial carbon paper, carbon cloth, carbon felt, or a flat substrate made from carbon material by pressing or film drawing.

7. The preparation method according to claim 1, characterized in that: The reducing / protecting gas in step 3 and step 4 is hydrogen-argon or hydrogen-nitrogen mixed gas, with the hydrogen ratio being 10-50% and the total gas flow rate being 100-800 sccm.

8. The preparation method according to claim 1, characterized in that: The predetermined pressure in step 3 is 1 atmosphere.

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