Composite current collector with heterostructure and preparation method thereof
By designing a heterostructured layered composite material in the composite fluid collection, and using the alternating layered structure of the hard layer and the soft layer, the shortcomings of the composite fluid collection in terms of bending resistance are solved, and the mechanical properties and electrical conductivity of the material are significantly improved.
Patent Information
- Application Number
- CN202411725072.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-02-25
AI Technical Summary
There is room for improvement in the bending resistance performance of composite liquid collecting, which affects the safety and reliability of lithium-ion batteries.
A composite fluid-collection design with a heterostructure is adopted. A hard layer and a soft layer are laminated in sequence on both sides of the flexible substrate. The hardness range of the soft layer is 15-100HB and the hardness range of the hard layer is 20-200HB. A layered structure is formed by sputtering.
The soft and hard spaced layered structure produces the Baosinger effect and high heterogeneous deformation-induced stress during non-uniform deformation, which significantly improves the mechanical properties, ductility and electrical conductivity of the layered conductive layer, and overcomes the defect of insufficient bending resistance of pure copper conductive layer.
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Figure CN119517992A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of current collectors, and in particular relates to a composite current collector with a heterogeneous structure and a preparation method thereof. Background Art
[0002] Lithium-ion batteries play a vital role in modern technology, and the current collector is one of its core components. As a key material, the current collector not only needs to carry positive and negative electrode materials, but also must effectively collect and transmit electrons to ensure the efficient operation of the battery.
[0003] Composite current collectors are made of multilayer structures, designed to reduce manufacturing costs while maintaining good conductivity. These new materials combine metals with excellent conductivity with other materials to form a more stable and efficient structure. Therefore, composite current collectors are considered to be one of the most promising current collector materials in lithium-ion batteries.
[0004] Although composite current collectors have many advantages, further research and innovation are still needed to improve their bending resistance to ensure the safety and reliability of batteries.
[0005] It should be noted that the above information disclosed in this background technology section is only used to understand the background technology of the present application concept, and therefore, the above description is not considered to constitute information of the prior art. Summary of the invention
[0006] The embodiments of the present disclosure at least provide a composite current collector with a heterogeneous structure and a preparation method thereof.
[0007] In a first aspect, an embodiment of the present disclosure provides a composite current collector with a heterogeneous structure, comprising: a flexible substrate, wherein a plurality of groups of hard layers and soft layers stacked in sequence are arranged on both sides of the flexible substrate; wherein the hardness range of the soft layer is 15-100HB; and the hardness range of the hard layer is 20-200HB.
[0008] In an optional embodiment, the material of the soft layer includes any one of copper, aluminum, titanium, silver, and gold.
[0009] In an optional embodiment, the single layer thickness of the soft layer is 50-500 nm.
[0010] In an optional embodiment, the material of the hard layer includes any one of copper, aluminum, silver, and gold as the main metal and any one or two of chromium, nickel, zirconium, indium, strontium, magnesium, manganese, titanium, cobalt, cerium, tungsten, antimony, germanium, and molybdenum as the alloy layer of doped diffusion metal; wherein
[0011] The mass proportion of the main metal in the alloy layer is not less than 80%.
[0012] In an optional embodiment, the single layer thickness of the hard layer is 50-500 nm.
[0013] In an optional embodiment, the ratio of the single layer thickness of the hard layer to the single layer thickness of the soft layer is 0.7-1.2.
[0014] In an optional embodiment, the ratio of the hardness of the hard layer to the soft layer is 1.2-2.0.
[0015] In an optional embodiment, the total thickness of the soft layer and the hard layer on any side of the flexible substrate is in the range of 500-5000 nm.
[0016] In an optional embodiment, the flexible substrate includes any one of a biaxially oriented polypropylene film, a cast polypropylene film, a polyethylene terephthalate film, a polyimide film and a polyethylene naphthalate film; and the thickness of the flexible substrate is 3-20 μm.
[0017] In the second aspect, the embodiments of the present disclosure also provide a method for preparing a composite current collector with a heterogeneous structure as described above, comprising the following steps: step S1, pretreating a flexible substrate; step S2, sputtering to obtain a hard layer; step S3, sputtering to obtain a soft layer; step S4, repeating steps S2 and S3 until the film layer is thickened to a desired thickness, and after sputtering on both sides is completed, a composite current collector with a heterogeneous structure is obtained.
[0018] The beneficial effect of the present invention is that the heterogeneous structure composite current collector and its preparation method generate a larger Bauschinger effect and highly heterogeneous deformation-induced stress during non-uniform deformation by setting a layered structure with soft and hard intervals, thereby helping the layered conductive layer to obtain excellent mechanical properties, ductility and electrical conductivity, and overcoming the defect of insufficient bending resistance of the pure copper conductive layer.
[0019] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.
[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0022] Figure 1 A schematic diagram of the structure of a heterogeneous composite current collector provided in an embodiment of the present disclosure.
[0023] In the figure:
[0024] 1. Flexible substrate; 2. Hard layer; 3. Soft layer. DETAILED DESCRIPTION
[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0026] As used herein, the phrases "in one embodiment," "according to one embodiment," "in some embodiments," and the like generally refer to the fact that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure. Therefore, a particular feature, structure, or characteristic may be included in more than one embodiment of the present disclosure, so that these phrases do not necessarily refer to the same embodiment. As used herein, the terms "example," "exemplary," and the like are used to "serve as an example, instance, or illustration." Any implementation, aspect, or design described herein as "example" or "exemplary" is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. On the contrary, the use of the terms "example," "exemplary," and the like is intended to present concepts in a concrete manner.
[0027] Herein, example embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as "at least one of..." modify the entire list of elements when following a list of elements, rather than modifying individual elements in the list. For example, the expression "at least one of a, b, and c" should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.
[0028] The terms used herein are only used to describe specific exemplary configurations and are not intended to be limited. As used herein, the singular articles "one", "an" and "the" may also be intended to include plural forms, unless it is clearly indicated above that this is not the case. The terms "comprise", "include" and "have" are inclusive, and therefore specify the presence of features, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or combinations thereof. The method steps, processes and operations described herein should not be interpreted as necessarily requiring them to be performed in the specific order discussed or shown, unless specifically identified as an execution order. Additional or alternative steps may be adopted.
[0029] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.
[0030] like Figure 1 As shown, an embodiment of the present disclosure provides a composite current collector with a heterogeneous structure, including: a flexible substrate, wherein a plurality of groups of hard layers and soft layers stacked in sequence are arranged on both sides of the flexible substrate; wherein the hardness range of the soft layer is 15-100HB; and the hardness range of the hard layer is 20-200HB.
[0031] Specifically, this hard / soft layered structure can produce a large Bauschinger effect and high heterogeneous deformation induced (HDI) stress during inhomogeneous deformation, thereby helping the layered conductive layer to obtain an excellent combination of strength, ductility and conductivity. The mutual constraint between the soft layer and the hard layer will form a strain gradient near the layer interface, thereby promoting the generation and accumulation of geometrically required dislocations. This inhomogeneous deformation and dislocation accumulation ultimately lead to a strong back stress strengthening effect, which increases the yield strength of the material, and because the soft layer undergoes a larger plastic strain than the hard layer during the bending deformation, the development of plastic instability is delayed and the early strain localization in the nanostructured layer is suppressed. This microstructural difference leads to dislocation accumulation and strong reverse stress enhancement, which significantly improves the synergistic effect of the material's strength and ductility.
[0032] In some embodiments, specifically, the material of the soft layer includes any one of copper, aluminum, titanium, silver, and gold, preferably copper and aluminum with a purity of not less than 99.99%.
[0033] Specifically, the soft layer provides highly conductive regions that help improve the conductivity of the overall material. Since pure metal soft layers have high conductivity, the overall conductivity of the material can be significantly improved by designing heterostructures.
[0034] In some embodiments, specifically, the single layer thickness of the soft layer is 50-500 nm.
[0035] In some embodiments, specifically, the material of the hard layer includes any one of copper, aluminum, silver, and gold as the main metal and any one or two of chromium, nickel, zirconium, indium, strontium, magnesium, manganese, titanium, cobalt, cerium, tungsten, antimony, germanium, and molybdenum as an alloy layer of doped diffusion metals; wherein the mass proportion of the main metal in the alloy layer is not less than 80%.
[0036] Specifically, the hard layer contains diffused alloy elements, which function to obtain a well-bonded transition interface by diffusing the alloy elements, which helps to reduce the resistance at the interface and thus improve the conductivity. The design of the heterogeneous hard / soft microstructure can effectively distribute stress and strain and reduce defects and dislocations inside the material, which usually hinder the flow of electrons and thus reduce the conductivity.
[0037] In some embodiments, specifically, the single layer thickness of the hard layer is 50-500 nm.
[0038] In some embodiments, specifically, the ratio of the single layer thickness of the hard layer to the single layer thickness of the soft layer is 0.7-1.2.
[0039] In some embodiments, specifically, the ratio of the hardness of the hard layer to the soft layer is 1.2-2.0.
[0040] In some embodiments, specifically, the total thickness of the soft layer and the hard layer on any side of the flexible substrate is in the range of 500-5000 nm.
[0041] In some embodiments, specifically, the flexible substrate includes any one of a biaxially oriented polypropylene film, a cast polypropylene film, a polyethylene terephthalate film, a polyimide film and a polyethylene naphthalate film; and the thickness of the flexible substrate is 3-20 μm.
[0042] The embodiment of the present disclosure also provides a method for preparing a composite current collector with a heterogeneous structure as described above, comprising the following steps: step S1, pretreating a flexible substrate; step S2, sputtering to obtain a hard layer; step S3, sputtering to obtain a soft layer; step S4, repeating steps S2 and S3 until the film layer is thickened to a desired thickness, and after sputtering is completed on both sides, a composite current collector with a heterogeneous structure is obtained.
[0043] Specifically, the conductive layer is preferably formed by processes such as evaporation, magnetron sputtering, CVD, and electrodeposition. Since the uniformity of the film formed by sputtering is better than that of the film formed by evaporation, CVD, and electrodeposition, magnetron sputtering is preferred when forming a film on a large substrate. The sputtering method can use alternating current (AC) magnetron sputtering, direct current (DC) magnetron sputtering, and radio frequency (RF) magnetron sputtering. Since the conductive layer is a conductor, direct current (DC) magnetron sputtering is preferred.
[0044] Preliminary preparation: In the chamber of the winding magnetron sputtering coating machine, place the processed flexible substrate on the unwinding roller of the unwinding chamber and wind it onto the winding roller; at the same time, place the required targets Z1 and Z2 on the cathode target positions corresponding to chambers C1 and C2 in turn. Chambers C1 and C2 are coating chambers, and the distance from the target to the substrate surface is adjusted to 10 cm; close all chamber doors, turn on the fore pump and molecular pump in turn, and wait until the vacuum degree of the chamber reaches 5×10 -4 When the pressure drops to 0.05 Pa, fill in process gas until the process vacuum is reached, open the cathode and drive roller to start coating, and control the winding speed at 5-12 m / min.
[0045] (1) (Pretreatment process of flexible substrate)
[0046] Argon gas was introduced into the vacuum chamber, and the argon gas was ionized by providing 800 W of power to the ion source, thereby cleaning the surface of the substrate.
[0047] (2) (Formation of hard layer)
[0048] A sputtering gas argon with a purity of not less than 99.99% is introduced into the chamber C1, and by controlling the production process parameters, such as the amount of argon, the chamber pressure, the substrate bias during the sputtering process, the sputtering power of the corresponding target material and the target-substrate distance, a hard layer of a certain thickness is sputtered by dual rotating cathode and DC magnetron sputtering; the dual rotating cathode and DC magnetron sputtering power is 1Kw-20Kw.
[0049] (3) (Formation of soft layer)
[0050] A sputtering gas argon with a purity of not less than 99.99% is introduced into the chamber C2, and by controlling the production process parameters, such as the amount of argon, the chamber pressure, the substrate bias during the sputtering process, the sputtering power of the corresponding target material and the target-substrate distance, a soft layer of a certain thickness is sputtered by dual rotating cathode and DC magnetron sputtering; the dual rotating cathode and DC magnetron sputtering power is 1Kw-20Kw.
[0051] (4) Repeat the above preparation steps (2) and (3) to thicken the film layer to the required thickness.
[0052] Specifically, the parameters and properties of the composite current collector of the prepared heterogeneous structure are shown in Table 1 below.
[0053] Table 1
[0054]
[0055] Specifically, the elongation at break refers to the ratio of the elongation of a metal material when it breaks due to bending to its original length. The larger the value, the better the bending resistance.
[0056] Specifically, Comparative Examples 1 and 2 are pure copper layers and pure copper alloy layers. The pure copper layer has the best electrical conductivity, but poor tensile strength; the pure alloy layer has high tensile strength, but poor elongation at break and electrical conductivity.
[0057] Specifically, in Examples 1-5, pure copper layers and unit alloy layers are alternately stacked. Compared with Comparative Example 2, the elongation at break and the electrical conductivity are greatly improved, and most of the tensile strengths are also stronger than Comparative Example 2; compared with Comparative Example 1, the elongation at break and the tensile strength are greatly improved, and the electrical conductivity is also close to that of pure copper.
[0058] Specifically, embodiments 6-8 are pure copper layers and binary alloy layers stacked alternately, which have more excellent comprehensive properties in terms of tensile strength, elongation at break and electrical conductivity.
[0059] In summary, the heterostructured composite current collector and its preparation method produce a large Bauschinger effect and highly heterogeneous deformation-induced stress during non-uniform deformation by setting a layered structure with soft and hard intervals, thereby helping the layered conductive layer to obtain excellent mechanical properties, ductility and electrical conductivity, and overcoming the defect of insufficient bending resistance of the pure copper conductive layer.
[0060] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.
Claims
1. A composite current collector of a heterogeneous structure, characterized in that: include: A flexible substrate, wherein two sides of the flexible substrate are provided with a plurality of groups of hard layers and soft layers stacked in sequence; in The hardness of the soft layer ranges from 15 to 100 HB; The hardness of the hard layer ranges from 20 to 200 HB.
2. The heterostructured composite current collector according to claim 1, characterized in that: The material of the soft layer includes any one of copper, aluminum, titanium, silver and gold.
3. The heterostructured composite current collector according to claim 1, characterized in that: The single layer thickness of the soft layer is 50-500 nm.
4. The heterostructured composite current collector according to claim 1, characterized in that: The material of the hard layer includes any one of copper, aluminum, silver, and gold as the main metal and any one or two of chromium, nickel, zirconium, indium, strontium, magnesium, manganese, titanium, cobalt, cerium, tungsten, antimony, germanium, and molybdenum as the alloy layer of doped diffusion metal; The mass proportion of the main metal in the alloy layer is not less than 80%.
5. The heterostructured composite current collector according to claim 1, characterized in that: The single layer thickness of the hard layer is 50-500 nm.
6. The heterostructure composite current collector according to claim 1, characterized in that: The ratio of the single layer thickness of the hard layer to the single layer thickness of the soft layer is 0.7-1.
2.
7. The heterostructured composite current collector according to claim 1, characterized in that: The ratio of the hardness of the hard layer to the hardness of the soft layer is 1.2-2.
0.
8. The heterostructured composite current collector according to claim 1, characterized in that: The total thickness of the soft layer and the hard layer on any side of the flexible substrate is in the range of 500-5000 nm.
9. The heterostructured composite current collector according to claim 1, characterized in that: The flexible substrate includes any one of a biaxially oriented polypropylene film, a cast polypropylene film, a polyethylene terephthalate film, a polyimide film and a polyethylene naphthalate film; The thickness of the flexible substrate is 3-20 μm.
10. A method for preparing a heterostructure composite current collector according to any one of claims 1 to 9, characterized in that: The steps include: Step S1, pre-treating the flexible substrate; Step S2, sputtering to obtain a hard layer; Step S3, sputtering to obtain a soft layer; Step S4, repeating steps S2 and S3 until the film layer is thickened to a desired thickness, and sputtering is completed on both sides to obtain a composite current collector with a heterogeneous structure.