Composite current collector manufacturing method, current collector and battery manufacturing method

Abstract

The invention relates to a current collector manufacturing method, a current collector and a battery manufacturing method. The method comprises the following steps: carrying out surface roughening treatment on a polymer base material; preparing a metal layer on the polymer base material subjected to surface roughening treatment; and carrying out water plating thickening on the metal layer, and slitting and packaging to obtain the composite current collector. The method can improve the safety performance of the battery.

Description

Technical Field

[0001] This application relates to the field of battery processing technology, and in particular to a method for manufacturing a current collector, a current collector, and a battery manufacturing method. Background Technology

[0002] With the continuous development of lithium-ion battery technology, current collectors, as one of the key components of batteries, directly affect the overall performance and safety of the battery. Traditional current collectors mainly use pure metal materials, such as copper foil and aluminum foil, but these materials have problems such as heavy weight, high cost, and insufficient safety performance. To solve these problems, composite current collector technology has emerged.

[0003] Composite current collectors typically consist of a polymer substrate and a metal conductive layer, offering advantages such as light weight, low cost, and good safety performance. However, insufficient bonding between the metal layer and the organic polymer substrate in composite current collectors can lead to interfacial delamination between the metal layer and the base film during long-term electrolyte immersion and charge-discharge cycles. This results in the conductive layer detaching and failing, severely impacting battery safety performance. Summary of the Invention

[0004] Therefore, it is necessary to provide a method for manufacturing a current collector, a current collector, and a battery manufacturing method that can improve battery safety performance in response to the above-mentioned technical problems.

[0005] In a first aspect, this application provides a method for manufacturing a current collector, comprising:

[0006] Surface roughening treatment is applied to the polymer substrate;

[0007] A metal layer is prepared on a polymer substrate after surface roughening treatment;

[0008] The metal layer is thickened by water plating, and then slit and packaged to obtain a composite current collector.

[0009] In one embodiment, forming a metal layer on the roughened polymer substrate includes:

[0010] A metal layer is formed on a roughened polymer substrate by sputtering or vapor deposition.

[0011] In one embodiment, the surface roughening treatment of the polymer substrate includes:

[0012] The surface roughening treatment of the polymer substrate is carried out sequentially through bulk ionization, surface treatment, and cross-linking enhancement.

[0013] In one embodiment, the surface roughness after the surface roughening treatment ranges from 0.3 μm to 0.5 μm.

[0014] Secondly, this application also provides a composite current collector, which is manufactured based on the method described in any one of the above embodiments.

[0015] In one embodiment, the metal layer is an aluminum layer;

[0016] The thickness of the aluminum layer in the current collector ranges from 1 μm to 4 μm.

[0017] In one embodiment, the thickness of the current collector ranges from 8 μm to 14 μm.

[0018] In one embodiment, the metal layer is a copper layer;

[0019] The thickness of the copper layer in the current collector ranges from 0.5 μm to 2 μm.

[0020] In one embodiment, the thickness of the current collector ranges from 4 μm to 8 μm.

[0021] Thirdly, this application also provides a method for manufacturing a battery, the method comprising:

[0022] Preparation of positive electrode slurry and negative electrode slurry;

[0023] The positive electrode slurry is coated onto the first composite current collector to obtain a positive electrode sheet roll; the first composite current collector is made based on the method described in any one of the above embodiments, and the metal layer of the first composite current collector is an aluminum layer;

[0024] The negative electrode slurry is coated onto the second composite current collector to obtain a negative electrode sheet roll; the second composite current collector is made based on the method described in any one of claims 1 to 4, and the metal layer of the second composite current collector is a copper layer;

[0025] The positive electrode roll and the negative electrode roll are rolled and slit to obtain pre-welded electrode sheets;

[0026] The empty foil areas of each of the pre-welded electrode sheets are subjected to ultrasonic pressure roll welding to obtain the electrode sheets before assembly.

[0027] Each of the pre-assembly electrode sheets is wound or stacked to obtain a battery core;

[0028] The battery core is then subjected to post-processing to obtain the battery.

[0029] The aforementioned current collector manufacturing method, current collector, and battery manufacturing method enable the polymer substrate in the composite current collector to effectively block the short circuit between the positive and negative electrodes when the battery is subjected to external forces such as impact or puncture, achieving the battery circuit breaking effect. Furthermore, the surface roughening process forms a rough structure on the surface of the polymer substrate, increasing the mechanical interlocking force and improving the bonding force between the polymer substrate and the metal layer. Finally, the preparation of a metal layer on the surface of the polymer substrate significantly improves the bonding force between the metal layer and the polymer substrate, ensuring its stability during long-term electrolyte immersion and charge-discharge cycles, thereby improving the battery's safety performance. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic flowchart of a composite current collector fabrication method in one embodiment;

[0032] Figure 2 This is a schematic diagram of the composite current collector in one embodiment;

[0033] Figure 3 This is a schematic flowchart of a composite current collector fabrication method in another embodiment;

[0034] Figure 4 This is a flowchart illustrating a battery manufacturing method in one embodiment.

[0035] Reference numerals: 10 - polymer substrate; 20 - metal layer. Detailed Implementation

[0036] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0038] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, parts, regions, layers, doping types, and / or portions, these elements, parts, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, part, region, layer, doping type, or portion from another element, part, region, layer, doping type, or portion.

[0039] Spatially relative terms such as "under," "beneath," "beneath," "under," "above," "above," etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, spatially relative terms also include different orientations of the device in use and operation. For example, if the device in the drawings is turned over, the element or feature described as "under" or "beneath" or "beneath" the other elements will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" can include both upper and lower orientations. In addition, the device can also include alternative orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0040] When used herein, the singular forms "a", "an", and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0041] In one exemplary embodiment, such as Figure 1 As shown, a method for manufacturing a composite current collector is provided, comprising:

[0042] Step S102: Surface roughening treatment is performed on the polymer substrate.

[0043] The polymer substrate, with polymer as its main component, is a base material possessing excellent flexibility and insulation properties, serving as the supporting structure for the composite current collector. In this embodiment, the polymer substrate is selected from at least one of PP (Polypropylene) and PET (Polyethylene terephthalate). Surface roughening treatment involves using physical or chemical methods to roughen the surface of an object, increasing surface roughness and altering its microstructure.

[0044] Specifically, the surface roughening treatment of polymer substrates can be based on the dual effects of physical bombardment and chemical activation by plasma. High-energy particles collide with contaminants on the material surface, achieving cleaning, activation, or etching effects. Plasma forms a micro-rough structure on the surface, increasing mechanical interlocking force. The surface roughness Ra is 0.3~0.5 μm, and the bonding force with the subsequently prepared metal layer is stable at 4.0 N-6.0 N / 15 mm.

[0045] Step S104: Prepare a metal layer on the polymer substrate after surface roughening treatment.

[0046] The metal layer is a layered structure formed by metallic materials, which plays a key role in the composite current collector, such as conducting electricity.

[0047] Specifically, such as Figure 2 As shown, a metal layer 20 is prepared on a polymer substrate 10, which has undergone surface roughening treatment to improve adhesion, by sputtering or vapor deposition. This step is crucial for constructing the conductive structure of the composite current collector, and the quality and uniformity of the metal layer 20 directly affect the conductivity of the composite current collector.

[0048] Step S106: The metal layer is thickened by water plating, and after slitting and packaging, a composite current collector is obtained.

[0049] Water-based thickening utilizes electrochemical principles to reduce and deposit metal ions in an aqueous solution, thereby increasing the thickness of the metal layer. Composite current collectors are a new type of current collector material, typically composed of a polymer substrate and a metal layer, combining the properties of both polymer and metal materials, and have important applications in fields such as batteries.

[0050] Specifically, in the water-plating thickening process, the polymer substrate with the metal layer is placed in an aqueous solution containing metal ions. By applying an electric current or other means, the metal ions are reduced and deposited on the surface of the metal layer, thereby increasing the thickness of the metal layer to meet the requirements of the composite current collector and further improving its conductivity. After the water-plating thickening is completed, the composite current collector is cut into appropriate sizes according to actual needs and finally packaged for storage and transportation.

[0051] The above-mentioned current collector manufacturing method can be summarized as follows: Figure 3 The steps outlined in this method demonstrate that when a battery encounters external forces such as impact or puncture, the polymer substrate in the composite current collector can effectively block the short circuit between the positive and negative electrodes, achieving a battery circuit-breaking effect. Furthermore, the surface roughening process creates a rough structure on the polymer substrate surface, increasing the mechanical interlocking force and improving the bonding force between the polymer substrate and the metal layer. Finally, the preparation of a metal layer on the polymer substrate surface significantly enhances the bonding force between the metal layer and the polymer substrate, ensuring its stability during long-term electrolyte immersion and charge-discharge cycles, thereby improving the battery's safety performance.

[0052] In one exemplary embodiment, forming a metal layer on a roughened polymer substrate includes:

[0053] A metal layer is formed on a roughened polymer substrate by sputtering or vapor deposition.

[0054] Sputtering utilizes high-energy ions (such as argon ions) to bombard the target surface, causing target atoms to escape through momentum transfer and deposit on the substrate surface to form a thin film. Magnetic field confinement of electron trajectories can increase plasma density and significantly improve deposition efficiency. Evaporation, on the other hand, is performed in a vacuum environment by heating a metal material to evaporate or sublimate it, causing gaseous atoms to fly to the substrate surface and condense into a film.

[0055] Specifically, when forming a metal layer on a roughened polymer substrate, the deposition method must be selected based on the characteristics of the metal material and the process conditions. If sputtering is used, the polymer substrate must be fixed in a vacuum chamber, an inert gas (such as argon) is introduced, and a high-voltage electric field is applied to ionize the gas and generate high-energy ions that bombard the surface of the metal target. After being sputtered, the target atoms move in a straight line and deposit on the substrate surface. Since the substrate surface has been roughened, the sputtered atoms will preferentially fill the micropores or embed themselves in the uneven structure, forming a mechanical interlocking effect. At the same time, some atoms will chemically bond with the active groups on the substrate surface, further enhancing the interlayer bonding force. During the deposition process, parameters such as the chamber pressure and target power can be adjusted. The thickness uniformity and density of the metal layer are controlled by numerical control. If the vapor deposition process is used, the metal material (such as aluminum) needs to be placed in the evaporation source in the vacuum chamber. The metal is melted and evaporated by resistance heating or electron beam heating. After the metal vapor diffuses in the chamber, it condenses into a solid film on the surface of the cooled substrate. During the vapor deposition process, metal atoms will preferentially deposit on the raised parts of the substrate and then gradually cover the recessed areas to form a continuous film. In order to improve the adhesion, the substrate can be plasma cleaned before vapor deposition to remove surface contaminants and activate active groups, so that the metal atoms can form chemical bonds with the substrate during deposition. Both processes can be carried out at room temperature or low temperature to avoid thermal damage to the polymer substrate caused by high temperature.

[0056] In this embodiment, forming a metal layer on a roughened substrate by sputtering or vapor deposition can significantly improve the overall performance of the composite current collector: the micro-nano structure of the roughened substrate provides mechanical intercalation sites for the metal layer, and combined with the chemical bonding formed during sputtering or vapor deposition, the bonding strength between the metal layer and the substrate is greatly improved, effectively reducing the risk of metal layer peeling due to volume changes during battery charging and discharging; the sputtered metal layer has fine grains and a dense structure, with a short electron transport path and low impedance, which can reduce the internal resistance of the current collector and improve the battery charging and discharging efficiency; the vapor deposition process has a wide range of metal material selection and can flexibly adapt to the conductivity requirements of different battery systems (such as lithium-ion and sodium-ion batteries); the introduction of polymer substrate reduces the weight of the composite current collector by more than 60% compared with traditional metal current collectors, while maintaining conductivity, which helps to improve battery energy density and achieve a balance between lightweight and high performance.

[0057] In one exemplary embodiment, surface roughening treatment of the polymer substrate includes:

[0058] The surface roughening treatment of the polymer substrate is carried out sequentially through bulk ionization, surface treatment, and cross-linking enhancement.

[0059] Bulk ionization utilizes an electric field or plasma to ionize gas molecules, generating charged particles such as high-energy ions, electrons, and active free radicals. These particles can interact with the surface of the polymer substrate, inducing the breakage or activation of surface molecular chains. Surface treatment further alters the chemical composition or physical structure of the substrate surface through methods such as chemical etching, plasma bombardment, or ultraviolet irradiation, for example, by introducing polar groups, increasing surface energy, or forming microporous structures. Crosslinking enhancement utilizes chemical crosslinking agents or high-energy radiation (such as electron beams or gamma rays) to form covalent bonds or physical entanglements between polymer molecular chains, improving the surface layer's hardness, wear resistance, and thermal stability while maintaining the stability of the roughened structure.

[0060] Specifically, when roughening the surface of a polymer substrate, the morphology and properties need to be simultaneously optimized through the synergistic effect of bulk ionization, surface treatment, and crosslinking enhancement: First, bulk ionization technology (such as plasma treatment) is used, placing the substrate in a low-pressure plasma environment and introducing process gases such as argon, oxygen, or nitrogen. Under the action of an electric field, the gas molecules ionize to generate high-energy ions and active free radicals. When these particles bombard the substrate surface, they break the chemical bonds in the polymer molecular chains, reducing the molecular weight of the surface layer and forming a large number of active sites. At the same time, some ions embed into the surface, causing local expansion and initially forming a micron-level uneven structure. Subsequently, surface treatment (such as chemical wet etching) is performed, immersing the bulk-ionized substrate in a specific solution (such as alkaline hydroxide). Sodium chloride solution or acidic chromic acid solution), the active components in the solution (such as hydroxide ions or oxidants) selectively attack the surface activation region, further expanding the micropore size and increasing the surface roughness through swelling, etching or oxidation reactions. At the same time, oxygen- or nitrogen-containing polar groups are introduced to increase the surface energy and enhance the wettability of the subsequent metal layer. Finally, cross-linking enhancement (such as electron beam radiation) is achieved by using a high-energy electron beam to penetrate the substrate surface layer and excite the polymer molecular chains to generate free radicals. These free radicals recombine to form a covalent cross-linked network, which increases the surface hardness. At the same time, the cross-linked structure can fix the roughened morphology and prevent the surface structure from collapsing due to thermal stress or mechanical friction in subsequent processes (such as metal deposition), ensuring the long-term stability of the roughening effect.

[0061] In this embodiment, the surface roughening treatment of the polymer substrate can significantly improve the overall performance of the composite current collector through the synergistic effect of bulk ionization, surface treatment, and cross-linking enhancement: the micron-level uneven structure generated by bulk ionization provides mechanical intercalation sites for the subsequent metal layer; the polar groups introduced by surface treatment and the chemical bonding further enhance the interlayer adhesion; and cross-linking enhancement avoids morphological damage during the metal deposition process by solidifying the surface structure, thereby improving the bonding strength between the metal layer and the substrate and effectively reducing the risk of metal layer peeling due to volume changes during battery charge-discharge cycles; the roughened surface increases the actual contact area between the substrate and the metal layer, which can reduce contact resistance and improve the conductivity of the current collector; the surface layer hardness is increased after cross-linking enhancement, which can resist thermal stress and mechanical friction during the metal deposition process and extend the service life of the composite current collector; this process does not require high-temperature treatment, is compatible with flexible polymer substrates, and provides key material support for the lightweight design of high-energy-density, long-life lithium-ion batteries.

[0062] In one exemplary embodiment, the surface roughness after surface roughening treatment ranges from 0.3 μm to 0.5 μm.

[0063] Among them, surface roughness is a parameter that characterizes the micro-geometric shape error of the material surface. It is usually represented by the arithmetic mean deviation Ra, which is the arithmetic mean of the absolute values ​​of the profile deviation within the sampling length. The larger the value, the more obvious the surface unevenness.

[0064] Specifically, after surface roughening treatment, the surface roughness of the polymer substrate is controlled within the range of 0.3μm-0.5μm. This range can avoid insufficient mechanical interlocking between the metal layer and the substrate due to excessively small roughness (e.g., <0.2μm), and can also prevent uneven surface coverage or local stress concentration during metal deposition due to excessively large roughness (e.g., >0.8μm), thus ensuring the compatibility between the roughening morphology and the metal layer deposition process.

[0065] In one exemplary embodiment, a composite current collector is also provided, which is manufactured based on any one of the methods described in the above embodiments.

[0066] Among them, composite current collectors are conductive materials composed of polymer substrates and metal layers. They are usually used as current collectors in lithium-ion batteries. Their core structure is "polymer support layer + metal conductive layer", which has the characteristics of being lightweight (high polymer content) and highly conductive (metal layer is responsible for electron transport).

[0067] In one exemplary embodiment, the metal layer is an aluminum layer;

[0068] The thickness of the aluminum layer in the current collector ranges from 1 μm to 4 μm.

[0069] From a mechanical performance perspective, aluminum layers of 1μm-4μm exhibit good flexibility and excellent compatibility with polymer substrates. During battery charging and discharging, the positive electrode material undergoes volume changes, and aluminum layers within this thickness range can deform moderately along with the substrate, making them less prone to cracking or detachment. This effectively maintains the integrity of the current collector structure and extends battery life.

[0070] In one exemplary embodiment, the thickness of the current collector ranges from 8 μm to 14 μm.

[0071] Controlling the thickness of the current collector within the range of 8μm-14μm brings numerous benefits to the battery. In terms of mechanical properties, this thickness endows the current collector with sufficient strength and toughness, enabling it to effectively resist external forces during various stages of battery manufacturing, such as winding, stacking, and packaging, reducing the risk of breakage and deformation, ensuring the stability of the battery structure, and providing a solid foundation for the long-term stable operation of the battery.

[0072] From an energy density perspective, this thickness range meets the performance requirements of the current collector itself while minimizing its weight, allowing more space inside the battery to load active materials, thereby increasing the battery's energy density and enabling it to store more electrical energy to meet the needs of long-term device use.

[0073] In terms of charge and discharge performance, the appropriate thickness ensures that electrons can be conducted efficiently and smoothly in the current collector, reducing internal resistance, reducing energy loss and heat generation during charge and discharge, improving the charge and discharge efficiency of the battery, and also helping to extend the cycle life of the battery, reduce the cost of use, and improve the overall performance and reliability of the battery.

[0074] In one exemplary embodiment, the metal layer is a copper layer;

[0075] The thickness of the copper layer in the current collector ranges from 0.5 μm to 2 μm.

[0076] Setting the copper layer thickness in the current collector within the range of 0.5μm-2μm achieves a good balance between performance and cost. At this thickness, the copper layer forms a continuous and stable conductive path, ensuring efficient electron transport within the current collector and meeting the conductivity requirements during battery charging and discharging, enabling the battery to complete the charging and discharging process quickly. Simultaneously, a thinner copper layer effectively reduces the weight of the current collector, allowing for a larger loading of active material within the same battery volume, thereby increasing the battery's energy density. Furthermore, this thickness range avoids material waste and increased costs due to excessively thick copper layers, reducing the overall manufacturing cost of the battery and enhancing its market competitiveness.

[0077] In one exemplary embodiment, the thickness of the current collector ranges from 4 μm to 8 μm.

[0078] The thickness of the current collector, ranging from 4μm to 8μm, strikes a balance between mechanical strength and overall battery performance. On one hand, this thickness provides the current collector with sufficient strength and flexibility, enabling it to withstand external forces without cracking or deformation during battery manufacturing processes such as winding and stacking. This ensures the integrity and stability of the battery structure, providing reliable protection for long-term battery use. On the other hand, a thinner current collector helps reduce the space occupied inside the battery, increasing the amount of active material and improving the battery's energy density. Furthermore, an appropriate thickness can optimize the internal electron conduction path, reduce internal resistance, decrease energy loss during charging and discharging, and improve battery charging and discharging efficiency and cycle life.

[0079] In one exemplary embodiment, a battery manufacturing method is also provided, comprising:

[0080] Step S302: Prepare positive electrode slurry and negative electrode slurry;

[0081] Step S304: The positive electrode slurry is coated onto the first composite current collector to obtain a positive electrode roll;

[0082] Step S306: The negative electrode slurry is coated onto the second composite current collector to obtain a negative electrode roll;

[0083] Step S308: Roller-slit the positive electrode roll and the negative electrode roll to obtain pre-welded electrode sheets;

[0084] Step S310: Perform ultrasonic pressure rolling welding on the empty foil area of ​​each pre-welded electrode to obtain the electrode before assembly;

[0085] Step S312: Each pre-assembly electrode sheet is wound or stacked to obtain a battery core;

[0086] Step S314: Perform post-processing on the battery core to obtain the battery.

[0087] The first composite current collector is manufactured using any one of the methods described in the above embodiments, and the metal layer of the first composite current collector is an aluminum layer. The second composite current collector is manufactured using any one of the methods described in the above embodiments, and the metal layer of the second composite current collector is a copper layer. The electrode slurry is a mixture of materials used to manufacture the positive electrode of a battery. It typically contains positive electrode active materials, conductive agents, binders, and other components, and is mixed through a specific process. It is the key material basis for the electrochemical performance of the battery positive electrode.

[0088] Negative electrode slurry is a mixture of materials used to make the negative electrode of a battery. It is generally composed of negative electrode active material, conductive agent, binder, etc., and plays an important role in storing and releasing lithium ions during the charging and discharging process of the battery.

[0089] Positive electrode rolls are roll-shaped structures formed by uniformly coating positive electrode slurry onto a composite aluminum current collector and then processing it through a certain process. They are the initial formed products of battery positive electrodes.

[0090] A negative electrode roll is a roll-shaped structure made by uniformly coating a negative electrode slurry onto a composite copper current collector and then processing it through appropriate techniques. It represents the initial form of the battery's negative electrode.

[0091] Roll pressing and slitting is a processing step for positive and negative electrode rolls. The electrode is compacted by a rolling press to improve its density and uniformity. Then, the electrode is cut into pre-welded electrode sheets of a specified size using a slitting machine.

[0092] Pre-welded electrode sheets are electrode sheets with certain dimensions obtained after a roll forming and slitting process. The empty foil area of ​​the electrode sheet needs to be further processed.

[0093] The empty foil area is the region on the electrode sheet where no active material slurry is coated, and only the metal current collector is exposed. During battery assembly, this area is used to weld connecting pieces and other components to achieve circuit conduction inside the battery.

[0094] Ultrasonic pressure roll welding is a welding method that uses a combination of ultrasonic vibration energy and pressure to weld the empty foil area of ​​the pre-welded electrode, which can form a strong connection at the welded part and improve the connection reliability and conductivity of the battery electrode.

[0095] Before assembly, the electrode sheet has undergone ultrasonic pressure rolling welding, at which point the electrode sheet is ready for subsequent winding or stacking to assemble into a battery core.

[0096] Winding is a process of winding the pre-assembled electrode sheets together in a certain order and manner to form a battery core with a certain structure and shape. The winding method can make the internal structure of the battery compact, which is beneficial to improving the energy density of the battery.

[0097] Stacking is a process of stacking electrode sheets one by one before assembly to form a battery core. The stacking process can make the distribution of electrode sheets inside the battery more uniform, which helps to improve the performance and safety of the battery.

[0098] Battery core: The core component assembled from the pre-assembly electrode sheets through winding or stacking processes. It is the key structure for the battery to realize the functions of energy storage and release. It still needs to undergo post-processing to become a complete battery.

[0099] Post-processing refers to a series of subsequent processing steps performed on the battery core, which may include liquid injection, formation, aging, capacity testing, etc. These processes enable the chemical substances inside the battery core to fully react and stabilize, ultimately forming a high-performance battery.

[0100] Specifically, composite current collectors include two types: a second composite current collector with a copper metal layer and a first composite current collector with an aluminum metal layer. In battery manufacturing, positive and negative electrode slurries are first prepared. The positive electrode slurry is a key material mixture used to make the battery's positive electrode, containing positive active material, conductive agent, binder, etc.; the negative electrode slurry is a material mixture used to make the battery's negative electrode, composed of negative active material, conductive agent, binder, etc. Next, the prepared positive electrode slurry is uniformly coated onto the first composite current collector, and after specific processing, a positive electrode roll is obtained. Simultaneously, the negative electrode slurry is uniformly coated onto the second composite current collector to form a negative electrode roll. Afterward, the obtained positive and negative electrode rolls undergo a roll-pressing and slitting process. The roll-pressing equipment compacts the electrode sheets, improving their density and uniformity. Then, the slitting equipment cuts the electrode sheets into specified sizes, thus obtaining pre-welded electrode sheets. Subsequently, the empty foil areas (areas on the electrode where no active material slurry is coated and only the metal current collector is exposed) of each pre-welded electrode are subjected to ultrasonic pressure rolling welding. This utilizes a combination of ultrasonic vibration energy and pressure to create a strong connection at the welded joints, resulting in the pre-assembly electrode. Then, depending on actual needs, each pre-assembly electrode is either wound or stacked. Winding involves winding the electrodes together in a specific order and manner to form a compact battery core; stacking involves layering the electrodes one by one to achieve a more uniform distribution, ultimately resulting in the battery core. Finally, the battery core undergoes post-processing, including electrolyte injection, formation, aging, and capacity testing, to ensure the full reaction and stabilization of the chemical substances within the battery core, ultimately yielding a high-performance battery.

[0101] In this embodiment, the battery manufacturing method uses a composite current collector, combined with specific manufacturing processes, which can effectively improve the connection reliability and conductivity of the battery electrodes, make the internal structure of the battery more reasonable, and thus improve the overall performance and safety of the battery.

[0102] In one embodiment, a composite current collector is also provided, including a composite copper current collector and a composite aluminum current collector.

[0103] Composite copper current collectors are composed of organic polymers and copper metal, with a thickness of 4.0 μm to 8 μm. Composite aluminum current collectors are composed of organic polymers and aluminum metal, with a thickness of 8 μm to 14 μm.

[0104] The organic polymer is selected from at least one of polypropylene (PP) and polyethylene terephthalate (PET), with a thickness of 2.0 μm to 6.0 μm. In a preferred embodiment, the organic polymer is polypropylene (PP) with a thickness of 3.0 μm. In another preferred embodiment, the organic polymer is polyethylene terephthalate (PET) with a thickness of 4.0 μm. In yet another preferred embodiment, the organic polymer is a mixture of polypropylene (PP) and polyethylene terephthalate (PET) with a thickness of 5.0 μm.

[0105] Copper metal is formed by sputtering / evaporation, with a thickness of 0.5µm to 2µm. The copper metal can be one or more of the following: T1 copper (copper + silver content ≥99.95%), T2 copper (copper + silver content ≥99.9%), T3 copper (copper content ≥98%), or U1 / TU2 oxygen-free copper (oxygen content ≤0.001%). In a preferred embodiment, the copper metal is T1 copper, and the sputtering thickness is 0.8µm. In another preferred embodiment, the copper metal is U1 oxygen-free copper, and the sputtering thickness is 1.5µm.

[0106] Aluminum metal is formed by sputtering / evaporation, with a thickness of 1µm to 4µm. The aluminum metal can be selected from 1060, 1050, 1145, 1235 alloys, or recycled aluminum, etc., and can be in the following states: -O, H14, -H24, -H22, -H18, etc., with a purity ≥99.5%. In a preferred embodiment, the aluminum metal is 1060 aluminum alloy in the H14 state, and the vapor deposition thickness is 1.5µm. In another preferred embodiment, the aluminum metal is 1145 aluminum alloy in the -O state, and the vapor deposition thickness is 3.0µm.

[0107] The fabrication process of the composite current collector includes surface roughening treatment. Surface roughening is based on the dual effects of physical bombardment and chemical activation by plasma. Through collisions between high-energy particles and contaminants on the material surface, cleaning, activation, or etching effects are achieved. The plasma forms a micro-rough structure on the surface, increasing the mechanical interlocking force. The surface roughness Ra is 0.3~0.5 μm, and the bonding force with the aluminum / copper layer is stable at 4.0 N-6.0 N / 15 mm.

[0108] Surface roughening is achieved through bulk ionization, surface treatment, and cross-linking enhancement methods, with processing temperatures ranging from room temperature to 80°C. After treatment, the surface tension reaches 42-48 dyn / cm, the processing efficiency is 3-5 m / min, and the RF power supply power is 0-2000W. In a preferred embodiment, the processing temperature is 60°C, the surface tension is 45 dyn / cm, the processing efficiency is 4 m / min, and the RF power supply power is 1500W.

[0109] The preparation method of the composite copper current collector includes the following steps: feeding organic polymer film, surface roughening, sputtering / evaporation, water plating for thickening, slitting, and packaging to obtain the composite copper current collector.

[0110] The preparation method of composite aluminum current collector includes the following steps: feeding organic polymer film, surface roughening, sputtering / evaporation, water plating for thickening, slitting, and packaging to obtain composite aluminum current collector.

[0111] Composite copper current collectors and composite aluminum current collectors can be used in batteries. A method for manufacturing a battery using this composite current collector includes the following steps:

[0112] S1: Select the conventional method for making lithium batteries to make positive electrode slurry and negative electrode slurry. Use a coating machine to coat the positive electrode slurry onto the composite aluminum current collector and the negative electrode slurry onto the composite copper current collector to obtain positive electrode rolls and negative electrode rolls.

[0113] S2: The electrode rolls are rolled and slit (punched) to obtain pre-welded electrode sheets;

[0114] S3: The empty foil area of ​​the electrode is ultrasonically pressure-welded to obtain the electrode before assembly;

[0115] S4: The front electrode is made into a battery core using a winding / Z-shaped stacked square sheet. It is then processed by ultrasonic welding / pressure welding, followed by adhesive application, casing, encapsulation, baking, electrolyte injection, pre-charging, degassing and double sealing, and capacity testing to obtain a soft pack, square or cylindrical battery.

[0116] In one specific embodiment, the composite copper current collector has a thickness of 6 μm, wherein the organic polymer is PET with a thickness of 4 μm, the copper metal is T2 copper, the sputtering thickness is 1 μm, and the water plating thickness is increased by 1 μm; the composite aluminum current collector has a thickness of 10 μm, wherein the organic polymer is PP with a thickness of 3 μm, the aluminum metal is 1060 alloy, H14 state, the vapor deposition thickness is 2 μm, and the water plating thickness is increased by 5 μm. The surface roughening treatment temperature is 50℃, the surface tension is 44 dyn / cm, the processing efficiency is 3.5 m / min, the RF power supply power is 1200W, the surface roughness Ra after treatment is 0.4 μm, and the adhesion to the metal layer is 5.0 N / 15 mm.

[0117] In another specific embodiment, the composite copper current collector has a thickness of 4.5 μm, wherein the organic polymer is PP with a thickness of 2.5 μm, the copper metal is U1 oxygen-free copper, the sputtering thickness is 0.5 μm, and the water plating thickness is increased by 1.5 μm; the composite aluminum current collector has a thickness of 12 μm, wherein the organic polymer is PET with a thickness of 5 μm, the aluminum metal is 1145 alloy in the -O state, the vapor deposition thickness is 3 μm, and the water plating thickness is increased by 4 μm. The surface roughening treatment temperature is 70℃, the surface tension is 47 dyn / cm, the processing efficiency is 4.5 m / min, the RF power supply power is 1800W, the surface roughness Ra after treatment is 0.35 μm, and the adhesion to the metal layer is 5.5 N / 15 mm.

[0118] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

Claims

1. A method for manufacturing a composite current collector, characterized in that, The method includes: Surface roughening treatment is applied to the polymer substrate; A metal layer is prepared on a polymer substrate after surface roughening treatment; The metal layer is thickened by water plating, and then slit and packaged to obtain a composite current collector.

2. The method according to claim 1, characterized in that, The process of forming a metal layer on a roughened polymer substrate includes: A metal layer is formed on a roughened polymer substrate by sputtering or vapor deposition.

3. The method according to claim 1, characterized in that, The surface roughening treatment of the polymer substrate includes: The surface roughening treatment of the polymer substrate is carried out sequentially through bulk ionization, surface treatment, and cross-linking enhancement.

4. The method according to claim 1, characterized in that, The surface roughness after the surface roughening treatment ranges from 0.3 μm to 0.5 μm.

5. A composite current collector, characterized in that, The composite current collector is made based on the method described in any one of claims 1 to 4.

6. The composite current collector according to claim 5, characterized in that, The metal layer is an aluminum layer; The thickness of the aluminum layer in the current collector ranges from 1 μm to 4 μm.

7. The composite current collector according to claim 6, characterized in that, The thickness of the current collector ranges from 8 μm to 14 μm.

8. The composite current collector according to claim 5, characterized in that, The metal layer is a copper layer; The thickness of the copper layer in the current collector ranges from 0.5 μm to 2 μm.

9. The composite current collector according to claim 8, characterized in that, The thickness of the current collector ranges from 4μm to 8μm.

10. A method for manufacturing a battery, characterized in that, The method includes: Preparation of positive electrode slurry and negative electrode slurry; The positive electrode slurry is coated onto the first composite current collector to obtain a positive electrode roll; the first composite current collector is made according to the method described in any one of claims 1 to 4, and the metal layer of the first composite current collector is an aluminum layer; The negative electrode slurry is coated onto the second composite current collector to obtain a negative electrode sheet roll; the second composite current collector is made based on the method described in any one of claims 1 to 4, and the metal layer of the second composite current collector is a copper layer; The positive electrode roll and the negative electrode roll are rolled and slit to obtain pre-welded electrode sheets; The empty foil areas of each of the pre-welded electrode sheets are subjected to ultrasonic pressure roll welding to obtain the electrode sheets before assembly. Each of the pre-assembly electrode sheets is wound or stacked to obtain a battery core; The battery core is then subjected to post-processing to obtain the battery.

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