Current collector, method for manufacturing the same, battery electrode sheet, and battery

Abstract

The application provides a current collector and a preparation method thereof, a battery pole piece and a battery, and belongs to the technical field of battery materials. The current collector comprises an insulating layer and a conductive layer; the conductive layer covers at least one surface in the thickness direction of the insulating layer. The material of the insulating layer is a substance containing a carbon-hydrogen bond; the conductive layer is used for carrying an electrode active material, the conductive layer has a spatial net structure formed by metal nanowires being interlaced and stacked with each other, and the surface of the metal nanowires has a nano-level thorn-like structure. The current collector provided by the application comprises the insulating layer and the conductive layer covering at least one surface in the thickness direction of the insulating layer, and the energy density of the battery can be effectively improved; the conductive layer has a pore structure, the water contact angle of the surface of the conductive layer is small, and the thorn-like structure can be inserted into an active material layer, so that the peeling strength between the current collector and the electrode active material layer can be improved, the stability of the battery pole piece can be further improved, and the efficiency and performance of the prepared battery can be improved.

Description

Technical Field

[0001] This application relates to the field of battery materials technology, and more specifically, to a current collector and its preparation method, battery electrodes, and a battery. Background Technology

[0002] In recent years, with the continuous development of the new energy industry, lithium-ion batteries have been increasingly used in mobile phones, new energy vehicles, and many other products. The advantages of lithium-ion batteries lie in their high energy density, high output power, and long cycle life. However, safety incidents involving lithium-ion batteries have also intensified, exacerbating public concerns about their safety and hindering their further development.

[0003] For lithium-ion batteries, the positive and negative current collectors in the battery electrodes (including current collectors and electrode active materials loaded on the surface of the current collectors) play a crucial role. In recent years, flexible metal-polymer current collectors have gradually become a hot topic, replacing traditional pure metal current collectors. This new type of flexible metal-polymer current collector consists of a non-conductive polymer in the middle layer and metal materials covering both sides of the middle layer. For example, aluminum or copper can be plated on both sides of a PP (polypropylene) film or a PET (polyethylene terephthalate) film as the positive and negative current collectors, respectively. This can effectively improve the energy density of lithium-ion batteries while also effectively reducing the weight of the current collectors, thereby improving the safety of lithium-ion batteries.

[0004] However, in the existing technology, it is difficult to control the surface uniformity of the current collector. The water contact angle of the surface where the current collector contacts the electrode active material is large, which causes uneven coating of the slurry containing the electrode active material on the surface of the current collector or coating gaps (i.e., poor wettability of the slurry on the surface of the current collector). This makes it easy to cause large internal stress in the battery electrode during the drying and rolling process after coating the electrode active material. This can lead to cracking of the electrode active material layer on the surface of the current collector or peeling of the electrode active material layer relative to the current collector, which is not conducive to improving the efficiency and performance of the battery. Summary of the Invention

[0005] The purpose of this application is to provide a current collector and its preparation method, battery electrode and battery, which can improve the technical problem that the electrode active material layer on the surface of the existing current collector is prone to cracking or peeling off relative to the current collector.

[0006] In a first aspect, this application provides a current collector, which includes an insulating layer and a conductive layer; the conductive layer covers at least one surface of the insulating layer in the thickness direction.

[0007] The insulating layer is made of a substance containing carbon-hydrogen bonds; the conductive layer is used to support the electrode active material. The conductive layer has a spatial network structure formed by interlaced stacked metal nanowires, and the surface of the metal nanowires has a nanoscale spike structure.

[0008] In the above technical solution, the conductive layer used to support the electrode active material includes multiple interconnected metal nanowires stacked in an interlaced manner to form a spatial network structure. This gives the conductive layer a porous structure, allowing for sufficient contact between the conductive layer and the electrode active material during the subsequent formation of the battery electrode. The surface of the metal nanowires has nanoscale spike-like structures, which increases the specific surface area of ​​the entire metal nanowire and reduces the water contact angle of the conductive layer surface; furthermore, the spike-like structures on the surface of the conductive layer can be inserted into the electrode active material layer.

[0009] Therefore, the current collector provided in this application can improve the peel strength between the conductive layer and the electrode active material layer, which helps to avoid uneven coating or coating gaps of the slurry containing electrode active material on the surface of the current collector. It also reduces the high internal stress in the battery electrode sheet that is easily caused during the drying and rolling processes after coating the electrode active material. This, in turn, helps to prevent cracking or peeling of the electrode active material layer from the current collector, improving the stability of the battery electrode sheet and enhancing its ion and electron conductivity, thereby improving the efficiency and performance of the manufactured battery. Furthermore, the current collector includes an insulating layer and a conductive layer covering at least one surface of the insulating layer in the thickness direction, which can effectively improve the energy density of the battery.

[0010] In conjunction with the first aspect, in optional embodiments of this application, the water contact angle of the surface of the conductive layer is ≤75°; and / or, the porosity of the conductive layer is 10-35%.

[0011] With the conductive layer having interlocked stacked metal nanowires and the surface of the metal nanowires having a nanoscale spiky structure, the water contact angle of the conductive layer surface is ≤75°, which can make the bonding force between the conductive layer and the electrode active material layer better.

[0012] With the conductive layer having interlocked stacked metal nanowires and the surface of the metal nanowires having a nanoscale spiky structure, the porosity of the conductive layer is 10-35%, which can make the bonding force between the conductive layer and the electrode active material layer better, and make the conductive layer more stably cover the surface of the insulating layer.

[0013] In conjunction with the first aspect, in an optional embodiment of this application, the surface of the metal nanowire has multiple spiky structures.

[0014] In the above technical solution, the number of spike structures is multiple, which can further increase the specific surface area of ​​the entire metal nanowire, reduce the water contact angle on the surface of the conductive layer, and help to further improve the stability of the battery electrode and further enhance the ion and electron conductivity of the battery electrode.

[0015] In conjunction with the first aspect, in optional embodiments of this application, a plurality of spike-like structures are sequentially distributed along the axial direction of the metal nanowire; and / or, a plurality of spike-like structures are sequentially distributed along the circumferential direction of the metal nanowire.

[0016] In the above technical solution, the distribution of the spike structure on the surface of the metal nanowire can be made more uniform, which can further increase the specific surface area of ​​the entire metal nanowire and reduce the water contact angle on the surface of the conductive layer. This is beneficial to further improve the stability of the battery electrode, thereby further improving the efficiency and performance of the battery.

[0017] In conjunction with the first aspect, in an optional embodiment of this application, the spiky structure extends toward the surface away from the metal nanowire, and the cross-sectional area gradually decreases.

[0018] In the above technical solution, the specific surface area of ​​the entire metal nanowire can be further increased and the water contact angle of the conductive layer surface can be reduced. It is also easier for the thorn-like structure located on the conductive layer surface to be inserted into the electrode active material layer. This helps to further avoid the phenomenon of the electrode active material layer peeling off from the conductive layer and the electrode active material layer cracking. This helps to further improve the stability of the battery electrode sheet, thereby further improving the efficiency and performance of the prepared battery.

[0019] Alternatively, the spiky structure may be cone-shaped.

[0020] Alternatively, the spiky structure may be conical.

[0021] Optionally, the spike structure is conical; the thickness of the conductive layer is 50-10000 nm, the length of the metal nanowire is 5-20 μm, the diameter of the metal nanowire is 50-500 nm, the length of the spike structure is 10-100 nm, and the diameter of the spike structure is 10-100 nm.

[0022] In conjunction with the first aspect, in optional embodiments of this application, the metal nanowires and spike structures are made of copper, aluminum, silver, or gold.

[0023] In conjunction with the first aspect, in an optional embodiment of this application, the material of the insulating layer includes a first polymer.

[0024] The above technical solution can make the current collector flexible, which is beneficial to broaden the application range of the current collector.

[0025] Optionally, the first polymer includes at least one of polyethylene, polystyrene, polyvinyl chloride, polypropylene, polypropylene, polytetrafluoroethylene, polyimide, and polyvinylidene fluoride.

[0026] In a second aspect, this application provides a battery electrode, which includes: an electrode active material and a current collector as provided in the first aspect above; the electrode active material is loaded on the surface of a conductive layer.

[0027] The battery electrode provided by this application has low internal stress, which helps to avoid cracking of the electrode active material layer and peeling of the electrode active material layer from the conductive layer. The battery electrode has high stability, which enhances the conductivity of ions and electrons in the battery electrode, thereby improving the efficiency and performance of the manufactured battery.

[0028] Thirdly, this application provides a battery, which includes the battery electrode provided in the second aspect above.

[0029] The battery provided in this application has high efficiency and performance.

[0030] Fourthly, this application provides a method for preparing the current collector provided in the first aspect above, comprising: immersing an insulating layer that has undergone plasma treatment in a solution containing metal nanowires, and then performing a drying process to form a conductive layer covering the surface of the insulating layer.

[0031] In the above technical solution, immersing the plasma-treated insulating layer in a solution containing metal nanowires allows the metal nanowires dispersed in the solution to fully contact the surface of the insulating layer. Since the insulating layer is made of a substance containing carbon-hydrogen bonds, plasma treatment of the insulating layer can break the weak carbon-hydrogen bonds on the surface of the insulating layer, giving the surface of the insulating layer "dangling bonds," which can significantly enhance the chemical activity at the surface of the insulating layer. This, in turn, can greatly improve the bonding force between the surface of the insulating layer and the metal nanowires, which is beneficial to improving the structural stability of the entire current collector. Moreover, this method is simple, easy to implement, and low in cost, making it suitable for industrial production.

[0032] In conjunction with the fourth aspect, in an optional embodiment of this application, the power of the plasma treatment is 5-100W.

[0033] The above technical solution not only helps to avoid thermal shrinkage of the insulating layer during plasma treatment, but also helps to improve the chemical activity of the insulating layer surface, thereby further improving the bonding force between the insulating layer surface and the metal nanowires.

[0034] Optionally, the power of the plasma treatment is 10-50W.

[0035] Optionally, the plasma treatment time is 5-30 minutes.

[0036] Alternatively, the gas used for plasma treatment may be argon, nitrogen, or oxygen.

[0037] In conjunction with the fourth aspect, in an optional embodiment of this application, the method for preparing metal nanowires includes: mixing a precursor solution with a reducing agent and reacting them, and then heat-treating at 80-200°C for at least 60 minutes.

[0038] The precursor solution is a mixed solution containing a first metal salt and ethylenediamine. The precursor solution is alkaline, and the metal ions in the first metal salt are the same as the metal components in the metal nanowires.

[0039] In the above technical solution, during the mixed reaction growth of metal nanowires, the precursor solution is alkaline, which promotes the reduction of metal ions in the first metal salt. The presence of ethylenediamine alters the crystal phase of the metal nanowires, facilitating the adsorption of metal ions that could not be reduced in time on the surface of the metal nanowires during the initial stage of the mixed reaction. These adsorbed metal ions can then be reduced as the reaction progresses. After the mixed reaction, heat treatment at 80-200℃ for at least 60 minutes allows the adsorbed metal ions on the surface of the metal nanowires to be effectively reduced, forming nanoscale spike-like structures.

[0040] Optionally, the molar ratio of the metal ion in the first metal salt to ethylenediamine is (1-10):1.

[0041] Optionally, the molar ratio of metal ions to reducing agent in the first metal salt is (2-4):1.

[0042] Optionally, the pH of the precursor solution is 8-12.

[0043] Optionally, the mixing reaction is carried out by stirring, with a stirring speed of 200-2000 rpm and a stirring time of 30-60 min.

[0044] Optionally, the reducing agent includes at least one of ascorbic acid, catechin, and acetone.

[0045] In conjunction with the fourth aspect, in an optional embodiment of this application, the method for preparing metal nanowires includes: forming a spindle by electrospinning; first oxidizing the spindle in an oxidizing atmosphere, then reducing the oxidized spindle under a reducing gas condition; performing surface grinding on the reduced spindle, and then cleaning the ground spindle.

[0046] The spinning solution that forms the spinneret is a solution containing a second metal salt and a second polymer, and the metal ions in the second metal salt are the same as the metal components in the metal nanowires; the oxidation treatment temperature is 150-250℃, and the reduction treatment temperature is 200-350℃.

[0047] In the above technical solution, the spinneret formed by electrospinning contains a second polymer and a second metal salt. Through the combination of oxidation and reduction treatment, the metal ions in the second metal salt in the spinneret can be reduced to form a metal nanowire structure and a nanoscale spiky structure can be formed on the surface of the metal nanowire. The polymer in the spinneret can be removed by grinding and cleaning, thereby obtaining the metal nanowire.

[0048] Optionally, the voltage for electrospinning is 5-30KV.

[0049] Optionally, the second polymer accounts for 5-20% of the mass fraction of the spinning solution.

[0050] Optionally, the ambient temperature for electrospinning is 15-25℃, and the ambient humidity for electrospinning is 10-20%.

[0051] Optionally, the second polymer is selected from PVP, PAN, or PVA. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A schematic diagram of the current collector structure provided in an embodiment of this application.

[0054] Figure 2 This is a partial structural diagram of the conductive layer provided in an embodiment of this application.

[0055] Figure 3 This is a schematic diagram of the structure of the metal nanowires provided in the embodiments of this application.

[0056] Icons: 10 - conductive layer; 110 - metal nanowire; 111 - spike structure; 20 - insulating layer. Detailed Implementation

[0057] This application provides a current collector, Figure 1 This is a schematic diagram of the current collector structure provided in an embodiment of this application. Figure 2 This is a partial structural diagram of the conductive layer provided in an embodiment of this application. Figure 3 For a schematic diagram of the structure of the metal nanowires provided in the embodiments of this application, please refer to [link / reference]. Figures 1 to 3 The current collector includes a conductive layer 10 and an insulating layer 20; the conductive layer 10 covers at least one surface of the insulating layer 20 in the thickness direction.

[0058] The conductive layer 10 is used to support the electrode active material. The conductive layer 10 has a spatial network structure formed by interlaced stacking of metal nanowires 110, and the surface of the metal nanowires 110 has nanoscale spike structures 111. The insulating layer 20 is made of a substance containing carbon-hydrogen bonds.

[0059] The conductive layer 10 for supporting the electrode active material includes multiple interconnected metal nanowires 110, which are stacked in an interlaced manner to form a spatial network structure. This gives the conductive layer 10 a porous structure, allowing for sufficient contact between the current collector conductive layer 10 and the electrode active material during subsequent formation of the battery electrode. The surface of the metal nanowires 110 has nanoscale spike structures, which can increase the specific surface area of ​​the entire metal nanowires 110 and reduce the water contact angle of the conductive layer 10 surface; furthermore, the spike structures 111 on the surface of the conductive layer 10 can be inserted into the electrode active material layer.

[0060] Therefore, the current collector provided in this application can improve the peel strength between the conductive layer 10 and the electrode active material layer, which helps to avoid uneven coating or coating gaps of the slurry containing electrode active material on the surface of the current collector. It also reduces the high internal stress in the battery electrode sheet that is easily caused during the drying and rolling processes after coating the electrode active material. This helps to prevent cracking of the electrode active material layer or peeling of the electrode active material layer relative to the current collector, thus improving the stability of the battery electrode sheet and enhancing its ion and electron conductivity, thereby improving the efficiency and performance of the manufactured battery. Furthermore, the current collector includes an insulating layer 20 and a conductive layer 10 covering at least one surface of the insulating layer 20 in the thickness direction, which can effectively improve the energy density of the battery.

[0061] It should be noted that the conductive layer 10 can simultaneously cover two opposite surfaces of the insulating layer 20 in the thickness direction, or the conductive layer 10 can only cover one surface of the insulating layer 20 in the thickness direction.

[0062] In addition, it should be noted that, Figure 2 The conductive layer 10 shown is only a partial schematic diagram of the conductive layer 10. In fact, the entire structure of the conductive layer 10 is as shown. Figure 2 The structure shown.

[0063] In some alternative embodiments, the water contact angle of the surface of the conductive layer 10 is ≤75°.

[0064] With the conductive layer 10 having interlocked stacked metal nanowires 110 and the surface of the metal nanowires 110 having a nanoscale spiky structure 111, the water contact angle of the surface of the conductive layer 10 is ≤75°, which can make the bonding force between the conductive layer 10 and the electrode active material layer better.

[0065] As an example, the water contact angle of the surface of the conductive layer 10 can be any one of 65°, 66.5°, 66°, 67°, 68°, 69°, 70°, 71°, 72°, 72.5°, 73°, 74°, and 75° or a range between any two.

[0066] Furthermore, the water contact angle on the surface of the conductive layer 10 is 65-73°, which helps to further improve the peel strength between the conductive layer 10 and the electrode active material layer, thereby making the formed battery electrode sheet more stable.

[0067] In some alternative embodiments, the porosity of the conductive layer 10 is 10-35%.

[0068] With the conductive layer 10 having interlocked stacked metal nanowires 110 and the surface of the metal nanowires 110 having nanoscale spiky structures 111, the porosity of the conductive layer 10 is 10-35%. This allows for better adhesion between the conductive layer 10 and the electrode active material layer, and enables the conductive layer 10 to more stably cover the surface of the insulating layer 20. If the porosity of the conductive layer 10 is less than 10%, the peel strength between the conductive layer 10 and the electrode active material layer will be reduced; if the porosity of the conductive layer 10 is greater than 35%, it may cause the conductive layer 10 to fail to stably cover the surface of the insulating layer 20 during the fabrication of the current collector.

[0069] As an example, the porosity of the conductive layer 10 can be any one of 15%, 15.21%, 15.29%, 15.39%, 15.41%, 15.43%, 15.47%, 15.5%, 15.52%, 15.55%, 15.7%, 16%, 16.22%, 16.28%, 16.43%, 16.49%, 16.5%, 16.51%, 16.52%, 16.6%, 16.9%, and 17%, or a range between any two.

[0070] Furthermore, the porosity of the conductive layer 10 surface is 15-17%, which helps to further improve the peel strength between the conductive layer 10 and the electrode active material layer, thereby making the formed battery electrode sheet more stable.

[0071] In some alternative approaches, the porosity of the conductive layer 10 is 15-17%, and the water contact angle of the surface of the conductive layer 10 is 65-73°, which is beneficial to further improve the peel strength between the conductive layer 10 and the electrode active material layer, thereby making the formed battery electrode sheet more stable.

[0072] In this application, the surface of the metal nanowire 110 has multiple spiky structures 111, which can further increase the specific surface area of ​​the entire metal nanowire 110 and reduce the water contact angle on the surface of the conductive layer 10, which is beneficial to further improve the stability of the battery electrode and further enhance the ion and electron conductivity of the battery electrode.

[0073] Furthermore, multiple spike structures 111 are sequentially distributed along the axial direction of the metal nanowire 110; and multiple spike structures 111 are sequentially distributed along the circumferential direction of the metal nanowire 110; this can make the distribution of spike structures 111 on the surface of the metal nanowire 110 more uniform, which can further increase the specific surface area of ​​the entire metal nanowire 110 and reduce the water contact angle on the surface of the conductive layer 10, which is beneficial to further improve the stability of the battery electrode.

[0074] It should be noted that in other feasible embodiments, multiple spike structures 111 may be distributed sequentially along the axial direction of the metal nanowire 110; or, multiple spike structures 111 may be distributed sequentially along the circumferential direction of the metal nanowire 110.

[0075] In this application, the spike structure 111 extends toward the surface away from the metal nanowire 110 and the cross-sectional area gradually decreases; this can further increase the specific surface area of ​​the entire metal nanowire 110 and reduce the water contact angle on the surface of the conductive layer 10, and also make it easier for the spike structure 111 located on the surface of the conductive layer 10 to insert into the electrode active material layer, thereby helping to further avoid the phenomenon of the electrode active material layer peeling off from the conductive layer 10 and the electrode active material layer cracking, which is beneficial to further improve the stability of the battery electrode.

[0076] Furthermore, the spike structure 111 is cone-shaped; even further, the spike structure is conical. The above configuration can further increase the specific surface area of ​​the entire metal nanowire 110 and reduce the water contact angle on the surface of the conductive layer 10, and also make it easier for the spike structure 111 located on the surface of the conductive layer 10 to insert into the electrode active material layer of the battery electrode.

[0077] In this application, the conductive layer 10 has a thickness of 50-10000 nm, the metal nanowire 110 has a length of 5-20 μm, the metal nanowire 110 has a diameter of 50-500 nm, the spike structure 111 has a length of 10-100 nm, and the spike structure 111 (which is conical) has a diameter of 10-100 nm; this allows the conductive layer 10 to have a low water contact angle.

[0078] It should be noted that, in this application, the diameter of the spike structure 111 (which is conical) refers to the average diameter of the spike structure 111 in the direction along the metal nanowire 110 pointing to the spike structure 111.

[0079] Furthermore, the metal nanowires 110 have a length of 5-8 μm and a diameter of 50-150 nm, which is beneficial for electron collection in the current collector, thereby improving the current collector performance.

[0080] The length of the spike structure 111 is 10-30 nm, and the diameter of the spike structure 111 (which is conical) is 20-50 nm. If the size of the spike structure 111 is too small, it will hinder the electron transfer between the metal nanowires 110, thus impeding the current collector efficiency. If the size of the spike structure 111 is too large, it will hinder the wettability of the electrode active material coating and will not be conducive to ensuring the contact performance between the electrode active material and the current collector.

[0081] As an example, the conductive layer 10 has a thickness of 1000-1500 nm, and the metal nanowires 110 and the spike structure 111 are made of copper, aluminum, silver or gold.

[0082] In this application, the insulating layer 20 is made of a first polymer, which makes the current collector flexible and helps to broaden the application range of the current collector.

[0083] As an example, the first polymer may be selected from at least one of polyethylene, polystyrene, polyvinyl chloride, polypropylene, polypropylene, polytetrafluoroethylene, polyimide, and polyvinylidene fluoride.

[0084] This embodiment also provides a battery electrode (not shown), which includes: an electrode active material and the current collector described above; the electrode active material is loaded on the surface of the conductive layer 10.

[0085] The battery electrode provided by this application has low internal stress, which helps to avoid cracking of the electrode active material layer and peeling of the electrode active material layer from the conductive layer 10. The battery electrode has high stability, which enhances the conductivity of ions and electrons in the battery electrode, thereby improving the efficiency and performance of the manufactured battery.

[0086] This embodiment also provides a battery (not shown) having the battery electrodes described above. The battery provided in this application has high efficiency and performance.

[0087] In the prior art, the preparation process of metal (i.e. conductive layer)-polymer (i.e. insulating layer) current collectors is generally as follows: a metal layer is deposited on the surface of the insulating layer by chemical or physical vapor deposition, and a conductive layer is formed by electroplating to thicken it; or an adhesive layer is deposited on the insulating layer by magnetron sputtering, and then a conductive layer is deposited on the adhesive layer by thermal evaporation.

[0088] However, the above-mentioned processes involve physical or chemical vapor deposition, magnetron sputtering, electroplating, and thermal evaporation, which involve high temperatures. This can cause the insulation layer to undergo thermal deformation, resulting in high internal stress and wrinkles, leading to low production yield. Furthermore, physical or chemical vapor deposition, magnetron sputtering, electroplating, and thermal evaporation require significant investment in equipment, greatly increasing production costs.

[0089] Therefore, this application provides a method for preparing the current collector provided above, which can improve the bonding force between the insulating layer and the conductive metal layer while effectively reducing production costs and internal stress of the insulating layer. Moreover, this method is simple, easy to implement, and low in cost, which is conducive to industrial production.

[0090] The method for preparing the current collector provided in this application includes: immersing an insulating layer that has undergone plasma treatment in a solution containing metal nanowires, and then performing a drying process to form a conductive layer covering the surface of the insulating layer.

[0091] This application involves immersing a plasma-treated insulating layer in a solution containing metal nanowires, which allows the metal nanowires dispersed in the solution to fully contact the surface of the insulating layer. Since the insulating layer is made of a substance containing carbon-hydrogen bonds, plasma treatment can break the weak carbon-hydrogen bonds on the surface of the insulating layer, creating "dangling bonds" on the surface. This significantly enhances the chemical activity at the surface of the insulating layer, thereby greatly increasing the bonding force between the surface of the insulating layer and the metal nanowires. This is beneficial for improving the structural stability of the entire current collector. Furthermore, this method is simple, easy to implement, and low in cost, making it suitable for industrial production.

[0092] In this application, the plasma treatment power is 5-100W; this not only helps to avoid thermal shrinkage of the insulating layer during plasma treatment, but also helps to improve the chemical activity at the surface of the insulating layer, thereby further improving the bonding force between the surface of the insulating layer and the metal nanowires. If the plasma treatment power is less than 5W, the number of broken carbon-hydrogen bonds at the surface of the insulating layer will decrease, which will reduce the chemical activity at the surface of the insulating layer; if the plasma treatment power is greater than 100W, it may cause thermal shrinkage of the insulating layer during plasma treatment.

[0093] As an example, the power of the plasma treatment can be any one of 5W, 10W, 15W, 20W, 30W, 45W, 50W, 60W, 70W, 80W and 100W or a range between any two.

[0094] Furthermore, the plasma treatment power is 10-50W; this helps to significantly improve the chemical activity of the insulation layer surface while effectively avoiding thermal shrinkage of the insulation layer during plasma treatment.

[0095] In this application, the plasma treatment time is 5-30 minutes, which helps to ensure the number of carbon-hydrogen bonds that are broken on the surface of the insulating layer, thereby improving the bonding force between the surface of the insulating layer and the metal nanowires.

[0096] As an example, the plasma treatment time can be any one of 5 min, 10 min, 15 min, 20 min, 25 min, 27 min, and 30 min, or a range between any two.

[0097] In this application, the gas used for plasma treatment can be argon, nitrogen or oxygen, which can effectively destroy the carbon-hydrogen bonds on the surface of the insulating layer, causing the carbon-hydrogen bonds to break.

[0098] To further enhance the chemical activity of the insulating layer surface after plasma treatment, in some embodiments, the surface of the insulating layer can be ultrasonically cleaned before plasma treatment to remove oil stains.

[0099] As an example, ultrasonic cleaning can be performed using organic solvents such as anhydrous ethanol, isopropanol, or acetone, or inorganic solvents such as dilute hydrochloric acid, dilute sulfuric acid, nitric acid, or ammonia.

[0100] Furthermore, ultrasonic cleaning can be performed using anhydrous ethanol or dilute sulfuric acid; these substances are relatively mild and also help to remove oil stains and other contaminants from the surface of the insulation layer more thoroughly.

[0101] In this application, the time for immersing the plasma-treated insulating layer in a solution containing metal nanowires can be 30-60 minutes.

[0102] Metal nanowires can be prepared by hot solvent method or by a combination of electrospinning and thermal oxidation-reduction method. Both of these methods are simple, easy to implement and low in cost, which is conducive to industrial production.

[0103] The steps for preparing metal nanowires using a hot solvent method include: mixing a precursor solution with a reducing agent and reacting the mixture, followed by heat treatment at 80-200°C for at least 60 minutes. The precursor solution is a mixed solution containing a first metal salt and ethylenediamine, and the precursor solution is alkaline. Furthermore, the metal ions in the first metal salt are identical to the metal components in the metal nanowires.

[0104] In the process of growing metal nanowires via a hot solvent-based mixed reaction, the precursor solution is alkaline, which promotes the reduction of metal ions in the first metal salt. The presence of ethylenediamine alters the crystal phase of the metal nanowires, facilitating the adsorption of metal ions that could not be reduced in time on the surface of the nanowires during the initial stage of the mixed reaction. These adsorbed metal ions are then reduced as the reaction progresses. Heat treatment at 80-200℃ for at least 60 minutes after the mixed reaction effectively reduces the adsorbed metal ions on the nanowire surface, resulting in the formation of nanoscale spike-like structures.

[0105] If the heat treatment time is less than 60 minutes, the spiky structure may not form. As an example, the heat treatment temperature in the hot solvent method can be any one of 80°C, 100°C, 120°C, 140°C, 150°C, 180°C, and 200°C, or a range between any two; the heat treatment time can be any one of 60 minutes, 75 minutes, 90 minutes, 100 minutes, and 120 minutes, or a range between any two, or even longer. In this application, the heat treatment time is 60-120 minutes.

[0106] Furthermore, the heat treatment temperature in the hot solvent method is 80-100℃, which allows the metal ions adsorbed on the surface of the metal nanowires to be reduced and effectively form nanoscale spike structures.

[0107] In this application, the molar ratio of metal ions to ethylenediamine in the first metal salt is (1-10):1, and the molar ratio of metal ions to reducing agent in the first metal salt is (2-4):1; which can make more nanoscale spike structures form on the surface of metal nanowires.

[0108] As an example, the molar ratio of the metal ion to ethylenediamine in the first metal salt is any one of 1:1, 1.3:1, 2:1, 3:1, 5:1, 7:1, and 10:1, or any range between two; the molar ratio of the metal ion to the reducing agent in the first metal salt can be any one of 2:1, 2.2:1, 2.5:1, 2.67:1, 2.7:1, 3:1, 3.5:1, and 4:1, or any range between two.

[0109] Furthermore, the molar ratio of metal ions to ethylenediamine in the first metal salt is (1-5):1, which allows for the formation of more nanoscale spike structures on the surface of the metal nanowires.

[0110] As an example, in this application, the metal ion in the first metal salt is Cu. 2+ The first metal salt can be copper nitrate, copper sulfate, or copper acetate, etc., and the concentration of the first metal salt in the precursor solution is 0.5-1 mol / L.

[0111] In this application, the reducing agent may include at least one of ascorbic acid, catechin, and acetone. It should be noted that in other feasible embodiments, the reducing agent may be selected from other substances, as long as they enable the reduction of metal ions.

[0112] As an example, the concentration of the reducing agent in the mixed reaction system is 0.2-1 mol / L; further, the concentration of the reducing agent in the mixed reaction system is 0.2-0.5 mol / L, which is beneficial to improve the reduction effect.

[0113] In this application, the pH of the precursor solution is 8-12, which can further promote the reduction of metal ions in the first metal salt (i.e., the reduction effect is better).

[0114] As an example, the pH of the precursor solution can be any one of 8, 9, 10, 11 and 12 or a range between any two.

[0115] Furthermore, a precursor solution with a pH of 10-12 provides even better reduction.

[0116] To ensure thorough mixing of the various substances and improve the efficiency of the mixing reaction, this application employs stirring for mixing at a speed of 200-2000 rpm for a duration of 30-60 minutes. Further, the stirring speed is 500-1500 rpm.

[0117] As an example, the drying temperature can be 50-100°C.

[0118] The steps for preparing metal nanowires using a combined electrospinning and thermal oxidation-reduction method include: forming a spindle by electrospinning; first, oxidizing the spindle under an oxidizing atmosphere, then reducing the oxidized spindle under a reducing gas atmosphere; surface grinding the reduced spindle, and then cleaning the ground spindle. The spinning solution used to form the spindle is a solution containing a second metal salt and a second polymer, and the metal ions in the second metal salt are identical to the metal components in the metal nanowires; the oxidation temperature is 150-250℃, and the reduction temperature is 200-350℃.

[0119] The electrospinning process described above produces a second polymer and a second metal salt. Through a combination of oxidation and reduction treatments, the metal ions in the second metal salt can be reduced to form a metal nanowire structure, and nanoscale spiky structures can be formed on the surface of the metal nanowires. The polymer in the spinneret can be removed by grinding and cleaning, thereby obtaining the metal nanowires.

[0120] As an example, the oxidation temperature can be any one of 150°C, 180°C, 200°C, 220°C, and 250°C, or a range between any two; the reduction temperature can be any one of 200°C, 220°C, 250°C, 270°C, 300°C, 320°C, and 350°C, or a range between any two; the oxidation atmosphere can be a mixture of oxygen and nitrogen, and the reducing system can be hydrogen.

[0121] In this application, the voltage for electrospinning is 5-30KV. As an example, the voltage for electrospinning can be any one of 5KV, 7KV, 10KV, 12KV, 15KV, 20KV, 25KV, 27KV and 30KV or a range between any two.

[0122] Furthermore, the ambient temperature for electrospinning is 15-25℃, and the ambient humidity for electrospinning is 10-20%.

[0123] In this application, the mass fraction of the second polymer solution is 5-20%. As an example, the second polymer is selected from PVP, PAN, or PVA.

[0124] As an example, in this application, the metal ion in the second metal salt is Cu. 2+ The second metal salt can be copper nitrate, copper sulfate, or copper acetate, etc., and the concentration of the second metal salt in the spinning solution is 0.5-1 mol / L.

[0125] In some feasible implementations, after the metal nanowires are formed, they can be washed multiple times with deionized water.

[0126] This application also provides a method for preparing a battery electrode sheet, comprising: coating a slurry containing an electrode active material onto at least one surface in the thickness direction of the battery electrode sheet, and then performing a drying process.

[0127] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0128] Example 1

[0129] This embodiment provides a method for preparing a current collector, including the following steps:

[0130] (1) The polypropylene film was ultrasonically cleaned with anhydrous ethanol for 10 min, and then subjected to plasma treatment for 10 min using a plasma cleaner. The gas used for plasma treatment was argon, and the power of the plasma treatment was 15W.

[0131] (2) Prepare 10 mL of 1.6 mol / L copper nitrate trihydrate solution and 10 mL of 1.2 mol / L ethylenediamine solution. Add the prepared ethylenediamine solution dropwise to the copper nitrate trihydrate solution at a constant rate, stir for 5 min, and adjust the pH to 12. Add 1.74 g of catechin to the pH-adjusted system and sonicate for 10 min to ensure thorough mixing. Transfer the mixed solution with catechin to a constant temperature incubator and heat-treat at 80 °C for 1 h to obtain copper nanowires.

[0132] (3) The copper nanowires were repeatedly washed with deionized water, and then the washed copper nanowires were dispersed in the deionized water. The polypropylene film after plasma treatment in step (1) was placed in a beaker, and then the deionized water system containing the dispersed copper nanowires was introduced into the beaker containing the polypropylene film. After standing for 60 minutes, it was dried to obtain the current collector.

[0133] Example 2

[0134] This embodiment provides a method for preparing a current collector, including the following steps:

[0135] (1) The polyimide film was ultrasonically cleaned with isopropanol for 10 min, and the cleaned polypropylene film was plasma treated with a plasma cleaner for 10 min. The gas used for plasma treatment was argon, and the power of plasma treatment was 10W.

[0136] (2) Prepare 10 mL of 1.6 mol / L copper nitrate trihydrate solution and 10 mL of 1.2 mol / L ethylenediamine solution. Add the prepared ethylenediamine solution dropwise to the copper nitrate trihydrate solution at a constant rate, stir for 5 min, and adjust the pH to 10. Add 1.056 g of ascorbic acid to the pH-adjusted system and sonicate for 10 min to ensure thorough mixing. Transfer the mixed solution with ascorbic acid to a constant temperature oven and heat-treat at 100℃ for 1 h to obtain copper nanowires.

[0137] (3) The copper nanowires were repeatedly washed with deionized water, and then the washed copper nanowires were dispersed in the deionized water. The polypropylene film after plasma treatment in step (1) was placed in a beaker, and then the deionized water system with dispersed copper nanowires was introduced into the beaker containing the polypropylene film. After standing for 40 minutes, it was dried to obtain the current collector.

[0138] Example 3

[0139] This embodiment provides a method for preparing a current collector, including the following steps:

[0140] (1) The polypropylene film was ultrasonically cleaned with acetone for 10 min, and then plasma-treated with a plasma cleaner for 10 min. The gas used for plasma treatment was argon, and the power of the plasma treatment was 20W.

[0141] (2) Mix 10 mL of 1.6 mol / L copper acetate solution, followed by 5 mL of ethanol (purity 99.9%) and 5 mL of 7% polyvinylpyrrolidone (PVP) solution (solvent is ethanol) to obtain spinning solution.

[0142] Electrospinning was performed using a spinning solution, followed by oxidation treatment in a nitrogen-oxygen mixture (nitrogen to oxygen volume ratio of 2:1) for 30 min, and then reduction treatment with hydrogen for 60 min to obtain the reduced spun yarn. The electrospinning voltage was 15 kV, the ambient temperature was 20 °C, and the ambient humidity was 15%. The oxidation temperature was 200 °C, and the reduction temperature was 300 °C. The heating rate for both oxidation and reduction treatments was 2 °C / min.

[0143] The reduced spinneret was surface-ground and then ultrasonically cleaned in anhydrous ethanol to obtain copper nanowires.

[0144] (3) The copper nanowires were repeatedly washed with deionized water, and then the washed copper nanowires were dispersed in the deionized water. The polypropylene film after plasma treatment in step (1) was placed in a beaker, and then the deionized water system containing the dispersed copper nanowires was introduced into the beaker containing the polypropylene film. After standing for 45 minutes, it was dried to obtain the current collector.

[0145] Example 4

[0146] This embodiment provides a method for preparing a current collector, including the following steps:

[0147] (1) The polyimide film was ultrasonically cleaned with dilute hydrochloric acid for 10 min, and the cleaned polypropylene film was plasma treated with a plasma cleaner for 10 min. The gas used for plasma treatment was argon, and the power of plasma treatment was 15W.

[0148] (2) Mix 10 mL of 1.6 mol / L copper acetate solution, followed by 5 mL of ethanol (purity 99.9%) and 5 mL of 12% polyvinylpyrrolidone (PVP) solution (solvent is ethanol) to obtain spinning solution.

[0149] Electrospinning was performed using a spinning solution, followed by oxidation treatment in a nitrogen-oxygen mixture (nitrogen to oxygen volume ratio of 1.5:1) for 30 min, and then reduction treatment with hydrogen for 60 min to obtain the reduced spun yarn. The electrospinning voltage was 15 kV, the ambient temperature was 20 °C, and the ambient humidity was 15%. The oxidation temperature was 180 °C, and the reduction temperature was 250 °C. The heating rate for both oxidation and reduction treatments was 2 °C / min.

[0150] The reduced spinneret was surface-ground and then ultrasonically cleaned in anhydrous ethanol to obtain copper nanowires.

[0151] (3) The copper nanowires were repeatedly washed with deionized water, and then the washed copper nanowires were dispersed in the deionized water. The polypropylene film after plasma treatment in step (1) was placed in a beaker, and then the deionized water system with dispersed copper nanowires was introduced into the beaker containing the polypropylene film. After standing for 40 minutes, it was dried to obtain the current collector.

[0152] Example 5

[0153] This embodiment provides a method for preparing a current collector. The difference between Embodiment 5 and Embodiment 2 is that the power of the plasma treatment is 5W.

[0154] Example 6

[0155] This embodiment provides a method for preparing a current collector. The difference between Embodiment 6 and Embodiment 2 is that the power of the plasma treatment is 100W.

[0156] Example 7

[0157] This embodiment provides a method for preparing a current collector. The difference between Embodiment 7 and Embodiment 2 is that the power of the plasma treatment is 50W.

[0158] Example 8

[0159] This embodiment provides a method for preparing a current collector. The difference between Embodiment 8 and Embodiment 2 is that the plasma treatment time is 5 minutes.

[0160] Example 9

[0161] This embodiment provides a method for preparing a current collector. The difference between Embodiment 9 and Embodiment 2 is that the plasma treatment time is 30 minutes.

[0162] Example 10

[0163] This embodiment provides a method for preparing a current collector. The difference between Embodiment 10 and Embodiment 2 is that the plasma treatment time is 2 minutes.

[0164] Example 11

[0165] This embodiment provides a method for preparing a current collector. The difference between Embodiment 11 and Embodiment 1 is that the heat treatment temperature is 200°C.

[0166] Example 12

[0167] This embodiment provides a method for preparing a current collector. The difference between Embodiment 11 and Embodiment 3 is that the oxidation treatment temperature is 150°C.

[0168] Example 13

[0169] This embodiment provides a method for preparing a current collector. The difference between Embodiment 11 and Embodiment 3 is that the oxidation treatment temperature is 250°C.

[0170] Example 14

[0171] This embodiment provides a method for preparing a current collector. The difference between Embodiment 14 and Embodiment 3 is that the reduction treatment temperature is 200℃.

[0172] Example 15

[0173] This embodiment provides a method for preparing a current collector. The difference between Embodiment 14 and Embodiment 3 is that the reduction treatment temperature is 350°C.

[0174] Example 16

[0175] This comparative example provides a method for preparing a current collector. The difference between this comparative example and Example 1 is that in step (1), the polypropylene film is not subjected to plasma treatment.

[0176] Example 17

[0177] This comparative example provides a method for preparing a current collector. The difference between this comparative example and Example 3 is that in step (1), the polypropylene film is not subjected to plasma treatment.

[0178] Comparative Example 1

[0179] This comparative example provides a method for preparing a current collector, comprising the following steps:

[0180] (1) The polyethylene terephthalate film was ultrasonically cleaned with isopropanol for 10 min, and the cleaned polypropylene film was plasma treated with a plasma cleaner for 10 min. The gas used for plasma treatment was argon, and the power of plasma treatment was 10W.

[0181] (2) A 20 nm copper layer is deposited on the thin polypropylene surface after plasma treatment in step (1) by physical vapor deposition; then the copper layer is thickened by electroplating to obtain a copper layer with a thickness of 1000-1500 nm.

[0182] The electroplating solution was a copper sulfate solution, and the current density was 2 A / dm³. 2 The electroplating temperature is 25℃.

[0183] Comparative Example 2

[0184] This comparative example provides a method for preparing a current collector. The difference between this comparative example and Comparative Example 1 is that in step (1), the polypropylene film is not subjected to plasma treatment. Comparative Example 3

[0185] This comparative example provides a method for preparing a current collector. The difference between this comparative example and Example 1 is that the ethylenediamine in step (2) of Example 1 is replaced with polyvinylpyrrolidone.

[0186] Comparative Example 4

[0187] This comparative example provides a method for preparing a current collector. The difference between this comparative example and Example 1 is that the heat treatment temperature is 50°C.

[0188] Comparative Example 5

[0189] This comparative example provides a method for preparing a current collector. The difference between this comparative example and Example 1 is that the heat treatment time is 30 minutes.

[0190] Comparative Example 6

[0191] This comparative example provides a method for preparing a current collector. The difference between this comparative example and Example 3 is that the oxidation treatment temperature is 100°C.

[0192] Comparative Example 7

[0193] This comparative example provides a method for preparing a current collector. The difference between this comparative example and Example 3 is that the reduction treatment temperature is 150°C.

[0194] Experimental Example

[0195] The sheet resistance, peel strength, contact angle, and porosity of the current collectors provided in Examples 1-17 and Comparative Examples 1-7 were tested respectively, and the test results are shown in Table 1. The current collectors provided in Examples 1-17 and Comparative Examples 1-7 were used to prepare battery electrodes, and the sheet resistance and peel strength of the prepared electrode electrodes were tested respectively, and the test results are shown in Table 2.

[0196] The method for preparing the battery electrode sheet is as follows: the slurry-mixed negative electrode material graphite is coated on the surface of the current collector, and after drying, an electrode active material layer is formed.

[0197] The test method for sheet resistance is as follows: Connect and turn on the main power of the sheet resistance test equipment, after calibrating the standard parameters, place the current collector or battery electrode to be tested on the test platform, slowly press down the probe, ensure that the probe makes good contact with the battery electrode without penetration or deformation, and read the test results.

[0198] The peel strength test method is as follows: A 20mm*15mm (length*width) 3M double-sided tape is attached to the upper side of the tensile test plate. The current collector or battery electrode to be tested is attached to the double-sided tape on the tensile test plate, with its direction parallel to the plate. The lower end of the current collector or battery electrode to be tested is fixed to the clamp on the lower side, ensuring the sample is tightly attached to the steel plate surface. The maximum peel strength is then tested.

[0199] The porosity test method is as follows: Calculation is performed using the formula P = [(V0 - V) / V0] * 100% = [1 - V / V0] * 100%; where P is the porosity of the current collector to be tested, V0 is the total volume of the nanowire layer in its natural state, V is the dense volume of the current collector to be tested, and copper is 8.96 g / cm³. 3 .

[0200] Table 1

[0201]

[0202]

[0203] In Table 1, " / " indicates that there is no performance data available; the contact angle is the water contact angle.

[0204] Table 2

[0205]

[0206]

[0207] As can be seen from Tables 1 and 2, the comparison between Examples 1-15 and Comparative Example 1, and between Examples 16-17 and Comparative Example 2, shows that the current collector preparation method provided in this application does not significantly affect the sheet resistance and peel strength of the current collector. Furthermore, the current collector prepared by the current collector preparation method provided in this application can give the metal layer a porous structure and improve the bonding force between the insulating layer (e.g., polypropylene film or polyimide film) and the copper nanowires in the current collector. The current collector provided in this application does not affect the sheet resistance of the prepared electrode sheet, and the prepared electrode sheet has a high peel strength, indicating that the current collector provided in this application can improve the bonding force between the electrode active material layer and the current collector.

[0208] The comparison between Comparative Example 1 and Comparative Example 2 also shows that plasma treatment can improve the bonding force between the insulating layer and the conductive layer (i.e., the copper layer) inside the current collector.

[0209] As can be seen from the comparison between Example 16 and Example 1, and between Example 17 and Example 3, when the insulating layer (e.g., polypropylene film) is not subjected to plasma treatment, the bonding force between the insulating layer and the copper nanowire is reduced, which in turn leads to a decrease in the peel strength in the current collector.

[0210] The comparison between Comparative Examples 3-5 and Example 1 shows that when ethylenediamine is not used, the heat treatment temperature is low, or the heat treatment time is short, the bonding force between the electrode active material layer and the current collector is significantly reduced because the copper nanoparticle structure cannot be formed.

[0211] As can be seen from the comparison between Comparative Examples 6-7 and Example 3, when the oxidation treatment temperature or the reduction treatment temperature is low, the bonding force between the electrode active material layer and the current collector is significantly reduced because the copper nanoparticle structure cannot be formed.

[0212] In summary, the current collector provided in this application can improve the peel strength between the conductive layer and the electrode active material layer, thereby improving the stability of the battery electrode and enhancing the ionic and electronic conductivity of the battery electrode, thus improving the efficiency and performance of the fabricated battery. The current collector preparation method provided in this application can significantly improve the bonding force between the surface of the insulating layer and the metal nanowires (i.e., the conductive layer), which is beneficial to improving the overall structural stability of the current collector. Furthermore, this method is simple, easy to implement, and low in cost, making it suitable for industrial production.

[0213] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A current collector, characterized in that, include: Insulating layer and conductive layer; The conductive layer covers at least one surface of the insulating layer in the thickness direction; The insulating layer is made of a substance containing carbon-hydrogen bonds; The conductive layer is used to support the electrode active material. The conductive layer has a spatial network structure formed by interlaced stacking of metal nanowires. The surface of the metal nanowires has multiple nanoscale spike structures. The multiple spike structures are distributed sequentially along the axial and / or circumferential directions of the metal nanowires. The spike structures extend in a direction away from the surface of the metal nanowires and the cross-sectional area gradually decreases. The porosity of the conductive layer is 10%-35%.

2. The current collector of claim 1, wherein The water contact angle of the surface of the conductive layer is ≤75°.

3. The current collector of claim 1, wherein The thorn-like structure is cone-shaped.

4. The current collector of claim 1, wherein The thorn-like structure is conical in shape.

5. The current collector of claim 1, wherein The spike-like structure is conical; the thickness of the conductive layer is 50-10000 nm, the length of the metal nanowire is 5-20 μm, the diameter of the metal nanowire is 50-500 nm, the length of the spike-like structure is 10-100 nm, and the diameter of the spike-like structure is 10-100 nm.

6. The current collector of any one of claims 1-5, wherein, The metal nanowires and the spike-like structure are made of copper, aluminum, silver, or gold.

7. The current collector of any one of claims 1-5, wherein The insulating layer is made of a first polymer.

8. The current collector of claim 7, wherein The first polymer includes at least one of polyethylene, polystyrene, polyvinyl chloride, polypropylene, polypropylene, polytetrafluoroethylene, polyimide, and polyvinylidene fluoride.

9. A battery electrode sheet, characterized by, include: Electrode active material and current collector as described in any one of claims 1-8; The electrode active material is loaded on the surface of the conductive layer.

10. A battery, characterized in that, include: The battery electrode as described in claim 9.

11. A method of making a current collector as claimed in any one of claims 1 to 8, characterised in that, include: The plasma-treated insulating layer is immersed in a solution containing the metal nanowires and then dried to form the conductive layer covering the surface of the insulating layer.

12. The method of claim 11, wherein, The power of the plasma treatment is 5-100W.

13. The method of claim 12, wherein, The power of the plasma treatment is 10-50W.

14. The method of claim 12, wherein, The plasma treatment time is 5-30 minutes.

15. The preparation method according to claim 12, characterized in that, The gas used in the plasma treatment is argon, nitrogen, or oxygen.

16. The method of claim 11, wherein, The method for preparing the metal nanowires includes: mixing a precursor solution with a reducing agent and reacting them, and then heat-treating them at 80-200°C for at least 60 minutes; The precursor solution is a mixed solution containing a first metal salt and ethylenediamine. The precursor solution is alkaline, and the metal ions in the first metal salt are the same as the metal components in the metal nanowires.

17. The method of claim 16, wherein, The molar ratio of the metal ion in the first metal salt to the ethylenediamine is (1-10):

1.

18. The preparation method according to claim 16, characterized in that, The molar ratio of the metal ions in the first metal salt to the reducing agent is (2-4):

1.

19. The method of claim 16, wherein, The pH of the precursor solution is 8-12.

20. The method of claim 16, wherein, The mixing reaction is carried out by stirring, the stirring speed is 200-2000 rpm, and the stirring time is 30-60 min.

21. The method of claim 16, wherein, The reducing agent includes at least one of ascorbic acid, catechin, and acetone.

22. The method of claim 11, wherein, The method for preparing the metal nanowires includes: forming a spindle by electrospinning; first oxidizing the spindle in an oxidizing atmosphere, then reducing the oxidized spindle under a reducing gas condition; performing surface grinding on the reduced spindle, and then cleaning the ground spindle. The spinning solution forming the spun body is a solution containing a second metal salt and a second polymer, and the metal ions in the second metal salt are the same as the metal components in the metal nanowires; the oxidation treatment temperature is 150-250℃, and the reduction treatment temperature is 200-350℃.

23. The method of claim 22, wherein, The voltage for electrospinning is 5-30KV.

24. The method of claim 22, wherein, The second polymer accounts for 5-20% of the mass fraction of the spinning solution.

25. The preparation method according to claim 22, characterized in that, The ambient temperature for electrospinning is 15-25℃, and the ambient humidity for electrospinning is 10-20%.

26. The method of claim 22, wherein, The second polymer is selected from PVP, PAN or PVA.

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