Lithium pre-supplementing negative electrode plate, battery cell and preparation method of lithium pre-supplementing negative electrode plate

Abstract

The invention provides a lithium pre-supplementing negative plate, a battery cell and a preparation method of the battery cell, and belongs to the technical field of lithium secondary battery manufacturing. The lithium pre-supplementing negative plate comprises a negative polymer base material layer, a negative conductive metal layer, a first protective layer, a lithium pre-supplementing layer, a second protective layer and a negative active layer which are sequentially laminated and distributed; wherein the material of the first protective layer can conduct electrons and can form an alloy with lithium metal; the material of the second protective layer can conduct electrons and ions, and / or the material of the second protective layer can be decomposed in the operation process of the battery, and the lithium pre-supplementing negative plate can improve the problems that dead lithium is easily formed on the surface of the negative electrode by the lithium pre-supplementing negative plate, the timeliness of the lithium pre-supplementing layer is poor and the like; and therefore, the corresponding battery cell has relatively excellent discharge capacity.

Description

Technical Field

[0001] The present application relates to the technical field of lithium secondary battery manufacturing, and in particular to a pre-supplemented lithium negative electrode sheet, a battery cell and a preparation method thereof. Background Art

[0002] With the rapid development of the new energy field, the performance requirements for lithium batteries are increasing. During the use of lithium batteries, the first charge and discharge will form a solid electrolyte interface film (SEI film) on the surface of the negative electrode. This process consumes a large amount of lithium ions from the positive electrode, resulting in battery capacity loss and reduced Coulomb efficiency. In order to make up for this loss, pre-lithium replenishment technology came into being. In addition, with the continuous improvement of the performance and safety requirements for lithium batteries, traditional battery manufacturing technology has gradually revealed its limitations in some aspects. Against this background, the continuous coating technology of magnetron coating has attracted attention due to its unique advantages.

[0003] Conventional direct contact lithium replenishment is difficult to control the degree of pre-lithiation, insufficient lithiation cannot effectively improve the first coulombic efficiency, excessive lithium replenishment may form metallic dead lithium on the surface of the negative electrode, and the conventional negative electrode active material has a time limit for the outer Li replenishment protective layer. In addition, the traditional battery cell manufacturing process often has problems such as cumbersome steps, low efficiency, and difficulty in ensuring consistency. Magnetron sputtering is an advanced thin film preparation method that can be used for coating a variety of materials. Combining the advantages of magnetron sputtering and process structure design, a continuous and automated production process can be achieved, which greatly improves production efficiency and ensures the consistency and stability of product quality.

[0004] Patent CN115312774A discloses a method for determining and controlling the pre-lithium amount of the negative electrode lithium replenishment pole piece, which can accurately replenish lithium for the entire battery, effectively avoiding insufficient lithiation that cannot effectively improve the first coulomb efficiency, or excessive lithium replenishment that may form metallic dead lithium on the negative electrode surface, but its structural design does not take into account the fact that the lithium replenishment layer is prone to form dead lithium on the surface of the negative electrode material. Patent CN113809391B discloses a method for preparing a high ionic conductivity oxide solid electrolyte film, which improves its ionic conductivity, but does not solve the problem of the preservation of the solid electrolyte and the problem of poor bonding with the pole piece. Patent CN115207269A discloses a method for making a composite electrode sheet, and uses a vacuum magnetron sputtering method to form a solid electrolyte layer on the surface of the electrode sheet, which solves the problem of pores in the solid electrolyte layer of the traditional electrode sheet and effectively prevents the growth of lithium dendrites, but does not propose an effective process method for how the positive and negative electrode sheets form a battery cell.

[0005] Therefore, it is urgent to optimize the structure of the pre-supplemented lithium negative electrode sheet at this stage, so as to improve the problem of dead lithium and time-limited protective layer in the pre-supplemented lithium negative electrode sheet from the structural level, so as to effectively improve the discharge capacity of the battery. In addition, it is also necessary to apply magnetron coating technology in the continuous production of lithium battery cells, so as to continuously improve the performance and safety requirements of lithium batteries and meet the industrial needs of large-scale, high-efficiency and high-quality production. Summary of the invention

[0006] The purpose of the present application is to provide a pre-replenished lithium negative electrode sheet, a battery cell and a preparation method thereof, wherein the pre-replenished lithium negative electrode sheet can improve the problems of dead lithium easily forming on the negative electrode surface and poor timeliness of the pre-replenished lithium layer, thereby enabling the corresponding battery cell to have a relatively excellent discharge capacity.

[0007] The embodiment of the present application is implemented as follows:

[0008] In a first aspect, an embodiment of the present application provides a pre-lithium supplemented negative electrode sheet, comprising a negative electrode polymer substrate layer, a negative electrode conductive metal layer, a first protective layer, a pre-lithium supplemented layer, a second protective layer and a negative electrode active layer stacked in sequence; wherein the material of the first protective layer can conduct electrons and can form an alloy with lithium metal; the material of the second protective layer can conduct electrons and ions, and / or the material of the second protective layer can be decomposed during battery operation.

[0009] In the above technical solution, the pre-replenished lithium layer is arranged between the negative electrode conductive metal layer and the negative electrode active layer, and the first protective layer and the second protective layer are arranged between the negative electrode conductive metal layer and the pre-replenished lithium layer, and between the pre-replenished lithium layer and the negative electrode active layer, respectively. The material of the first protective layer can conduct electrons and can form an alloy with lithium metal. By forming an alloy, the difference in interfacial energy between lithium metal and the conductive metal can be reduced to improve the problem of dead lithium being easily formed on the negative electrode surface due to the large difference in interfacial energy between lithium metal and the conductive metal in the pre-replenished lithium negative electrode sheet. At the same time, with the help of its conductivity, the generated current can be better transferred to the negative electrode conductive metal layer, so that the negative electrode conductive metal layer can better play the role of collecting current. The provision of the second protective layer can effectively block the pre-replenished lithium layer from contacting with moisture in the air, etc., thereby reducing the probability of failure of the pre-replenished lithium layer due to reaction with water, etc., and thus improving the problem of poor timeliness of the pre-replenished lithium layer in the pre-replenished lithium negative electrode sheet; at the same time, the second protective layer has a wide range of applicable materials (including materials that can conduct electrons and ions and / or materials that can be gradually decomposed during battery operation), which can provide more feasible implementation plans, thereby facilitating the promotion and application of the technical solutions provided in this application. This application can improve the problems of the pre-replenished lithium negative electrode sheet easily forming dead lithium on the negative electrode surface and the poor timeliness of the pre-replenished lithium layer by designing a pre-replenished lithium negative electrode sheet with a specific structure, so that the corresponding battery cell has a relatively excellent discharge capacity.

[0010] In some optional embodiments, the material of the first protective layer is selected from at least one of C, Sn, Zn, Au, Ag, Si, Sb and Bi; and / or the material of the second protective layer is selected from at least one of LiZn, ZrO2, LiSn, Li2O2, LiO2, Li3N, PMMA (polymethyl methacrylate), PEO (polyethylene oxide) and PVDF (polyvinylidene fluoride).

[0011] In the above technical solution, the material of the first protective layer is selected from a specific type. On the one hand, these specific materials have good conductivity, which helps the negative electrode conductive metal layer to collect the generated current; on the other hand, these specific materials can more effectively reduce the interface energy difference between lithium metal and conductive metal after forming an alloy with lithium metal, thereby more effectively improving the problem that the pre-supplemented lithium negative electrode sheet is prone to form dead lithium on the negative electrode surface. In addition, the material types of the second protective layer are relatively rich. Specifically, the materials that cannot be decomposed include LiZn, ZrO2 and LiSn. These specific types of materials can take into account the relatively excellent electron and ion conductivity, so that the pre-supplemented lithium negative electrode sheet has relatively excellent electrical properties after being assembled into a battery; the materials that can be decomposed during the operation of the battery include Li2O2, LiO2, Li3N, PMMA (polymethyl methacrylate), PEO (polyethylene oxide) and PVDF (polyvinylidene fluoride). These specific types of materials have the advantage of being easily decomposed during the operation of the battery cell, so it is not easy to affect the performance of the battery cell.

[0012] In some optional embodiments, the thickness of the first protective layer is 1 to 100 nm; and / or the thickness of the second protective layer is 10 to 100 nm.

[0013] In the above technical solution, the thickness of the first protective layer and the second protective layer are respectively limited to a specific range, so that each protective layer has a relatively suitable thickness, so that each protective layer can better play its role.

[0014] In some optional embodiments, the material of the pre-lithium replenishment layer is metallic lithium, and / or the thickness of the pre-lithium replenishment layer is 10 to 20 nm.

[0015] In the above technical solution, a pre-lithium replenishment layer of a specific material is selected and the thickness is limited to a specific range, which can play a better lithium replenishment role during the operation of the corresponding battery, thereby making the corresponding battery cell have a relatively excellent discharge capacity.

[0016] In some optional embodiments, the thickness of the negative electrode conductive metal layer is 500-1500 nm; and / or the thickness of the negative electrode active layer is 10-200 μm.

[0017] In the above technical solution, the thickness of the negative electrode conductive metal layer and the negative electrode active layer are respectively limited within specific ranges, so that both have relatively suitable thicknesses, thereby being able to better play the role of each functional layer.

[0018] In a second aspect, an embodiment of the present application provides a method for preparing a pre-supplemented lithium negative electrode sheet as provided in the embodiment of the first aspect, comprising the following steps:

[0019] A negative electrode current collector is provided, which includes a negative electrode polymer substrate layer and a negative electrode conductive metal layer which are stacked and distributed in sequence; a first protective layer, a pre-lithium supplement layer, a second protective layer and a negative electrode active layer are sequentially formed on the side of the negative electrode conductive metal layer away from the negative electrode polymer substrate layer, wherein the pre-lithium supplement layer and the second protective layer are sequentially and continuously completed under vacuum conditions in the same magnetron sputtering equipment, and the negative electrode active layer is formed by dry coating of negative electrode slurry.

[0020] In the above technical scheme, the above specific method is used to prepare the pre-lithium supplemented negative electrode sheet, wherein the pre-lithium supplemented layer and the second protective layer are completed sequentially and continuously under vacuum conditions in the same magnetron sputtering equipment, so that after the pre-lithium supplemented layer is formed and before it comes into contact with moisture in the air, it is protected by the formed second protective layer, thereby reducing the probability of failure of the pre-lithium supplemented layer during the preparation of the negative electrode sheet; in addition, the negative electrode active layer is formed by dry coating of the negative electrode slurry, which can further reduce the probability of the pre-lithium supplemented layer coming into contact with moisture, etc., thereby better protecting the pre-lithium supplemented layer during the preparation of the negative electrode sheet.

[0021] In a third aspect, an embodiment of the present application provides a battery cell, comprising a positive electrode sheet, a solid electrolyte layer, and a pre-lithium-supplemented negative electrode sheet as provided in the embodiment of the first aspect, which are stacked and distributed in sequence.

[0022] In the above technical solution, the battery cell includes the pre-replenished lithium negative electrode sheet provided by the first aspect embodiment. Since the pre-replenished lithium negative electrode sheet has a specific structural design, it can improve the problems of the pre-replenished lithium negative electrode sheet easily forming dead lithium on the negative electrode surface and the poor timeliness of the pre-replenished lithium layer, thereby making the battery cell have a relatively excellent discharge capacity.

[0023] In a fourth aspect, an embodiment of the present application provides a method for preparing a battery cell as provided in the embodiment of the third aspect, comprising the following steps:

[0024] S1 material preparation: provide positive electrode sheets and pre-replenished lithium negative electrode sheets.

[0025] Preparation of S2 half-cell: forming a part of the solid electrolyte layer on the surface of the positive electrode active layer in the positive electrode sheet by magnetron sputtering coating to obtain a positive electrode half-cell; and forming another part of the solid electrolyte layer on the surface of the negative electrode active layer in the pre-replenished lithium negative electrode sheet by magnetron sputtering coating to obtain a negative electrode half-cell.

[0026] S3 rolling and merging: rolling and merging the sides of the positive electrode half-cell and the negative electrode half-cell having the solid electrolyte layer to obtain a cell.

[0027] Among them, the preparation steps of the semi-cell and the calendering and merging steps are completed sequentially and continuously under vacuum conditions in the same magnetron sputtering equipment.

[0028] In the above technical scheme, in the process of preparing the battery cell, the preparation steps of the semi-battery cell and the calendering and merging steps are completed sequentially and continuously under the vacuum conditions in the same magnetron sputtering equipment. With the help of the vacuum preparation conditions with higher cleanliness and the advantages of the magnetron sputtering process, the prepared solid electrolyte layer has the advantages of uniform thickness, less impurities and surface defects, higher purity and density, and closer integration with the active material layer, so that the prepared battery cell has better discharge capacity and cycle performance.

[0029] Beneficial effects: This application designs the structure of the pre-supplemented lithium negative electrode sheet, which can improve the problem of dead lithium and time-limited protective layer in the pre-supplemented lithium negative electrode sheet from a structural level, thereby effectively improving the discharge capacity of the battery. In addition, the application of magnetron plating technology in the continuous production of lithium battery cells can improve the performance and safety requirements of lithium batteries and meet the industrial needs of large-scale, high-efficiency, and high-quality production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A schematic diagram of the structure of a pre-supplemented lithium negative electrode sheet provided in an embodiment of the present application;

[0032] Figure 2 A schematic diagram of the structure of a battery cell provided in an embodiment of the present application;

[0033] Figure 3 This is a schematic diagram of the structure of a positive electrode sheet according to an embodiment of the present application;

[0034] Figure 4 A chamber distribution diagram of a magnetron sputtering device provided in an embodiment of the present application;

[0035] Figure 5 A process flow chart of a method for preparing a battery cell provided in an embodiment of the present application.

[0036] Icons: 10-battery cell; 100-pre-lithium-supplemented negative electrode sheet; 110-negative electrode polymer substrate layer; 120-negative electrode conductive metal layer; 130-first protective layer; 140-pre-lithium-supplemented layer; 150-second protective layer; 160-negative electrode active layer; 200-solid electrolyte layer; 300-positive electrode sheet; 310-positive electrode polymer substrate layer; 320-positive electrode conductive metal layer; 330-positive electrode active layer; 400-coating chamber; 410-first coating chamber; 420-second coating chamber; 500-calendering chamber; 610-first unwinding chamber; 620-second unwinding chamber; 700-winding chamber. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0040] The following is a detailed description of a pre-supplemented lithium negative electrode sheet, a battery cell and a preparation method thereof provided in the present application.

[0041] See also Figure 1 In a first aspect, an embodiment of the present application provides a pre-replenished lithium negative electrode sheet 100, comprising a negative electrode polymer substrate layer 110, a negative electrode conductive metal layer 120, a first protective layer 130, a pre-replenished lithium layer 140, a second protective layer 150 and a negative electrode active layer 160 which are stacked in sequence; wherein the material of the first protective layer 130 can conduct electrons and can form an alloy with lithium metal; the material of the second protective layer 150 can conduct electrons and ions, and / or the material of the second protective layer 150 can be decomposed during battery operation.

[0042] In the present application, the pre-replenished lithium layer 140 is disposed between the negative electrode conductive metal layer 120 and the negative electrode active layer 160, and the first protective layer 130 and the second protective layer 150 are respectively disposed between the negative electrode conductive metal layer 120 and the pre-replenished lithium layer 140, and between the pre-replenished lithium layer 140 and the negative electrode active layer 160. Among them, the material of the first protective layer 130 can conduct electrons and can form an alloy with lithium metal. By forming an alloy, the difference in interfacial energy between lithium metal and the conductive metal can be reduced to improve the problem that dead lithium is easily formed on the negative electrode surface of the pre-replenished lithium negative electrode sheet 100 due to the large difference in interfacial energy between lithium metal and the conductive metal. At the same time, by virtue of its conductivity, the generated current can be better transferred to the negative electrode conductive metal layer 120, so that the negative electrode conductive metal layer 120 can better play the role of collecting current. The second protective layer 150 can effectively block the pre-replenished lithium layer 140 from contacting with moisture in the air, thereby reducing the probability of the pre-replenished lithium layer 140 failing due to reaction with water, etc., thereby improving the problem of poor timeliness of the pre-replenished lithium layer 140 in the pre-replenished lithium negative electrode sheet 100; at the same time, the material of the first protective layer 130 can be applied in many types, and can provide more feasible implementation plans, so as to facilitate the promotion and application of the technical solutions provided in this application. This application can improve the problems that the pre-replenished lithium negative electrode sheet 100 is easy to form dead lithium on the negative electrode surface and the poor timeliness of the pre-replenished lithium layer 140 by designing a pre-replenished lithium negative electrode sheet 100 with a specific structure, so that the corresponding battery cell has a relatively excellent discharge capacity.

[0043] As an example, the material of the first protective layer 130 is selected from at least one of C, Sn, Zn, Au, Ag, Si, Sb and Bi; and / or the material of the second protective layer 150 is selected from at least one of LiZn, ZrO2, LiSn, Li2O2, LiO2, Li3N, PMMA (polymethyl methacrylate), PEO (polyethylene oxide) and PVDF (polyvinylidene fluoride).

[0044] In this embodiment, the material of the first protective layer 130 is selected from a specific type. On the one hand, these specific materials have good electrical conductivity, which helps the negative electrode conductive metal layer 120 to collect the generated current; on the other hand, these specific materials can more effectively reduce the interface energy difference between lithium metal and conductive metal after forming an alloy with lithium metal, thereby more effectively improving the problem that the pre-supplemented lithium negative electrode sheet 100 is easy to form dead lithium on the negative electrode surface. In addition, the material types of the second protective layer 150 are relatively rich. Specifically, the materials that cannot be decomposed include LiZn, ZrO2 and LiSn. These specific types of materials can take into account the relatively excellent electron and ion conductivity, so that the pre-supplemented lithium negative electrode sheet 100 has relatively excellent electrical properties after being assembled into a battery; the materials that can be decomposed during the operation of the battery include Li2O2, LiO2, Li3N, PMMA (polymethyl methacrylate), PEO (polyethylene oxide) and PVDF (polyvinylidene fluoride). These specific types of materials have the advantage of being easily decomposed during the operation of the battery cell, so that it is not easy to affect the performance of the battery cell.

[0045] As an example, the thickness of the first protective layer 130 is 1 to 100 nm, for example but not limited to the thickness of any point value among 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm and 100 nm, or a range value between any two of them; and / or, the thickness of the second protective layer 150 is 10 to 100 nm, for example but not limited to the thickness of any point value among 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm and 100 nm, or a range value between any two of them.

[0046] In this embodiment, the thickness of the first protective layer 130 and the second protective layer 150 are respectively limited within a specific range, so that each protective layer has a relatively suitable thickness, so as to better play its respective role.

[0047] As an example, the thickness of the first protective layer 130 is 10 to 20 nm, for example but not limited to the thickness of any point value among 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm and 20 nm or the range value between any two thereof; and / or, the thickness of the second protective layer 150 is 10 to 20 nm, for example but not limited to the thickness of any point value among 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm and 20 nm or the range value between any two thereof.

[0048] In this embodiment, the thickness of the first protective layer 130 and the second protective layer 150 are further limited to specific ranges, so that each protective layer has a more suitable thickness, thereby being able to better play their respective roles while better considering the preparation cost.

[0049] As an example, the material of the pre-lithium replenishment layer 140 is metallic lithium, and / or the thickness of the pre-lithium replenishment layer 140 is 10 to 20 nm, for example but not limited to a thickness of any one of 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm and 20 nm or a range between any two of them.

[0050] In this embodiment, the pre-lithium replenishment layer 140 is made of a specific material and its thickness is limited to a specific range, which can play a better lithium replenishment role during the operation of the corresponding battery, thereby making the corresponding battery cell 10 have a relatively excellent discharge capacity.

[0051] As an example, the material of the negative electrode polymer substrate layer 110 is selected from at least one of polyethylene terephthalate, polypropylene, polyethylene, polyimide, polyethylene naphthalate, polycarbonate, polyetheretherketone, cyclic polyolefin, polyarylate, polyethersulfone, polyetherimide and polyamideimide; and / or, the material of the negative electrode active layer 160 is selected from at least one of graphite, silicon nanowires, silicon nanoparticles, tin nanowires, tin nanoparticles, titanium oxide and titanium nitride.

[0052] In this embodiment, there are many types of applicable materials for the negative electrode polymer substrate layer 110 and the negative electrode active layer 160, which can provide more feasible implementation plans, thereby facilitating the promotion and application of the technical solutions provided in the embodiments of the present application.

[0053] As an example, the thickness of the negative electrode conductive metal layer 120 is 500-1500nm, for example but not limited to the thickness of any one of 500nm, 800nm, 1000nm, 1200nm and 1500nm or the range between any two thereof; and / or, the thickness of the negative electrode active layer 160 is 10-200μm, for example but not limited to the thickness of any one of 10nm, 50nm, 100nm, 150nm and 200nm or the range between any two thereof.

[0054] In this embodiment, the thickness of the negative electrode conductive metal layer 120 and the negative electrode active layer 160 are respectively limited within a specific range, so that both have a relatively suitable thickness, thereby being able to better play the role of each functional layer.

[0055] It should be noted that the material of the negative electrode conductive metal layer 120 can be selected according to conventional methods in the art, such as copper metal.

[0056] As an example, the thickness of the negative electrode conductive metal layer 120 is 1000-1200nm, for example but not limited to the thickness of any point value among 1000nm, 1050nm, 1100nm, 1150nm and 1200nm or the range value between any two thereof; and / or, the thickness of the negative electrode active layer 160 is 80-100μm, for example but not limited to the thickness of any point value among 80nm, 85nm, 90nm, 95nm and 100nm or the range value between any two thereof.

[0057] In this embodiment, the thicknesses of the negative electrode conductive metal layer 120 and the negative electrode active layer 160 are further limited within specific ranges, so that each functional layer has a more suitable thickness, thereby being able to better play its respective role while better considering the preparation cost.

[0058] It should be noted that the functional layers and parameter designs thereof not specifically described in the pre-lithium supplemented negative electrode sheet 100 may be set according to conventional selections in the art.

[0059] In a second aspect, an embodiment of the present application provides a method for preparing a pre-supplemented lithium negative electrode sheet as provided in the embodiment of the first aspect, comprising the following steps:

[0060] A negative electrode current collector is provided, which includes a negative electrode polymer substrate layer and a negative electrode conductive metal layer which are stacked and distributed in sequence; a first protective layer, a pre-lithium supplement layer, a second protective layer and a negative electrode active layer are sequentially formed on the side of the negative electrode conductive metal layer away from the negative electrode polymer substrate layer, wherein the pre-lithium supplement layer and the second protective layer are sequentially and continuously completed under vacuum conditions in the same magnetron sputtering equipment, and the negative electrode active layer is formed by dry coating of negative electrode slurry.

[0061] In the present application, the above-mentioned specific method is used to prepare a pre-lithium-supplemented negative electrode sheet, wherein the pre-lithium-supplemented layer and the second protective layer are completed sequentially and continuously under vacuum conditions in the same magnetron sputtering equipment, so that after the pre-lithium-supplemented layer is formed and before it comes into contact with moisture in the air, it is protected by the formed second protective layer, thereby reducing the probability of failure of the pre-lithium-supplemented layer during the preparation of the negative electrode sheet; in addition, the negative electrode active layer is formed by dry coating of the negative electrode slurry, which can further reduce the probability of the pre-lithium-supplemented layer coming into contact with moisture, etc., thereby better protecting the pre-lithium-supplemented layer during the preparation of the negative electrode sheet.

[0062] It should be noted that, for the functional layers not mentioned above in terms of specific preparation methods, the preparation methods are not limited and they can be prepared according to conventional processes in the art as long as the corresponding functional layers can be formed.

[0063] As an example, the negative electrode conductive metal layer is formed by magnetron sputtering coating, and / or the first protective layer is formed by magnetron sputtering coating.

[0064] In this embodiment, when the negative electrode conductive metal layer and the first protective layer are also prepared by magnetron sputtering coating, the negative electrode conductive metal layer, the first protective layer, the pre-lithium replenishment layer and the second protective layer can all be completed sequentially and continuously under vacuum conditions in the same magnetron sputtering equipment, thereby preparing a high-quality pre-lithium replenishment negative electrode sheet.

[0065] It should be noted that, after the preparation method of each functional layer is determined, the specific process parameters can be set according to the conventional selection in the art, and the embodiments of the present application do not make specific limitations.

[0066] It should be noted that the pre-supplemented lithium negative electrode sheet provided in the first aspect embodiment is applicable to any type of battery cells, for example, it can be a battery cell using a semi-solid electrolyte, a battery cell using an all-solid electrolyte, or a battery cell using an electrolyte. In the embodiment of the present application, a battery cell using an all-solid electrolyte is used as an example for explanation.

[0067] Thirdly, see Figure 2 The embodiment of the present application provides a battery cell 10, comprising a positive electrode sheet 300, a solid electrolyte layer 200 and a pre-supplemented lithium negative electrode sheet 100 as provided in the first aspect embodiment, which are stacked and distributed in sequence.

[0068] In the present application, the battery cell 10 includes the pre-replenished lithium negative electrode sheet 100 provided in the first aspect embodiment. Since the pre-replenished lithium negative electrode sheet 100 has a specific structural design, it can improve the problems of the pre-replenished lithium negative electrode sheet 100 easily forming dead lithium on the negative electrode surface and the poor timeliness of the pre-replenished lithium layer 140, thereby making the battery cell 10 have a relatively excellent discharge capacity.

[0069] As an example, the material of the solid electrolyte layer 200 is selected from LiPON, Li7La3Zr2O 12 , at least one of SnO2 and Bi2O3; and / or, the thickness of the solid electrolyte layer 200 is 1 to 10μm, for example but not limited to the thickness of any one of 1μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 6μm, 8μm and 10μm or a range between any two of them.

[0070] In this embodiment, the material and thickness of the solid electrolyte layer 200 are respectively limited within specific ranges, so that the solid electrolyte layer 200 has good ion transmission performance, safety performance and the function of effectively separating the positive and negative electrodes.

[0071] It should be noted that the form of the positive electrode sheet 300 is not limited and can be configured according to conventional selections in the art.

[0072] See also Figure 3 As an example, the positive electrode sheet 300 includes a positive electrode polymer substrate layer 310 , a positive electrode conductive metal layer 320 and a positive electrode active layer 330 which are stacked in sequence.

[0073] It should be noted that the positive electrode polymer substrate layer 310 may be specifically configured with reference to the negative electrode polymer substrate layer 110 .

[0074] It should be noted that the material of the positive electrode conductive metal layer 320 is Al, and the thickness can be set with reference to the negative electrode conductive metal layer 120 .

[0075] As an example, the material of the positive electrode active layer 330 is selected from at least one of lithium iron phosphide, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese oxide, lithium manganese nickel aluminum oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and lithium transition metal oxide, and the thickness of the positive electrode active layer 330 is 10 to 200 μm. Further, the thickness of the positive electrode active layer 330 is 80 to 100 μm.

[0076] It should be noted that the functional layers and designs thereof not specifically described or limited in the battery cell 10 may be arranged according to conventional selections in the art.

[0077] In a fourth aspect, an embodiment of the present application provides a method for preparing a battery cell as provided in the embodiment of the third aspect, comprising the following steps:

[0078] S1 material preparation: provide positive electrode sheets and pre-replenished lithium negative electrode sheets.

[0079] Preparation of S2 half-cell: forming a part of the solid electrolyte layer on the surface of the positive electrode active layer in the positive electrode sheet by magnetron sputtering coating to obtain a positive electrode half-cell; and forming another part of the solid electrolyte layer on the surface of the negative electrode active layer in the pre-replenished lithium negative electrode sheet by magnetron sputtering coating to obtain a negative electrode half-cell.

[0080] S3 rolling and merging: rolling and merging the sides of the positive electrode half-cell and the negative electrode half-cell having the solid electrolyte layer to obtain a cell.

[0081] Among them, the preparation steps of the semi-cell and the calendering and merging steps are completed sequentially and continuously under vacuum conditions in the same magnetron sputtering equipment.

[0082] In the present application, in the process of preparing the battery cell, the preparation steps of the semi-battery cell and the calendering and merging steps are completed sequentially and continuously under the vacuum conditions in the same magnetron sputtering equipment. By taking advantage of the vacuum preparation conditions with higher cleanliness and the advantages of the magnetron sputtering process, the prepared solid electrolyte layer has the advantages of uniform thickness, less impurities and surface defects, higher purity and density, and closer integration with the active material layer, thereby making the prepared battery cell have better discharge capacity and cycle performance.

[0083] It should be noted that the preparation of the positive electrode half-cell and the negative electrode half-cell can be carried out simultaneously or in sequence.

[0084] See also Figure 4 As an example, the chamber of the magnetron sputtering coating equipment includes a connected coating chamber 400 and a calendering chamber 500, and the coating chamber 400 includes a first coating chamber 410 and a second coating chamber 420 distributed side by side, and the first coating chamber 410 and the second coating chamber 420 are respectively connected to the calendering chamber 500; the preparation steps of the battery cell include: transporting the positive electrode sheet and the pre-lithium-supplemented negative electrode sheet to the first coating chamber 410 and the second coating chamber 420 respectively for magnetron sputtering coating to synchronously form a positive electrode half cell and a negative electrode half cell; then transporting the positive electrode half cell and the negative electrode half cell to the calendering chamber 500 for calendering and merging to obtain a battery cell.

[0085] In this embodiment, the chamber of the magnetron sputtering coating equipment is divided and designed according to the above-mentioned specific form, so that the positive electrode half-cell and the negative electrode half-cell can be formed simultaneously during the preparation process. Compared with forming the two half-cells one after another, the time used in the entire preparation process can be reduced, thereby improving the preparation efficiency of the cell.

[0086] It should be noted that, considering the continuity of the production process, the structure of the magnetron sputtering coating equipment can also be optimized.

[0087] See also Figure 4 As an example, the chamber of the magnetron sputtering coating equipment also includes a first unwinding chamber 610, a second unwinding chamber 620 and a winding chamber 700. Along the conveying direction of the film material, the first unwinding chamber 610 is located upstream of the first coating chamber 410, and is used to convey the positive electrode sheet to the first coating chamber 410; the second unwinding chamber 620 is located upstream of the second coating chamber 420, and is used to convey the pre-replenished lithium negative electrode sheet to the second coating chamber 420; the winding chamber 700 is located downstream of the calendering chamber 500, and is used to wind up the battery cells after calendering and merging.

[0088] As an example, in the step of forming a positive electrode half-cell in the first coating chamber and / or forming a negative electrode half-cell in the second coating chamber, the target-substrate distance is 70-100 mm, for example but not limited to the target-substrate distance being any one of 70 mm, 80 mm, 90 mm and 100 mm or a range between any two of them; the sputtering power is 5-7 KW, for example but not limited to the sputtering power being any one of 5 KW, 5.5 KW, 6 KW, 6.5 KW and 7 KW or a range between any two of them; the vacuum degree is 0.2-0.5 Pa, for example but not limited to the vacuum degree being any one of 0.2 Pa, 0.3 Pa, 0.4 Pa and 0.5 Pa or a range between any two of them.

[0089] In this embodiment, during the preparation of the half-cell, the target-substrate distance, sputtering power and vacuum degree are limited to specific ranges, which helps to form a solid electrolyte layer of better quality, and further prepare positive and negative electrode half-cells of better quality.

[0090] As an example, in the calendering combined step, the calendering pressure is 1 to 20 MPa, for example but not limited to the calendering pressure being any one of 1 MPa, 5 MPa, 10 MPa, 15 MPa and 20 MPa or a range between any two of them; and / or, the film feeding speed is 1 to 10 m / min, for example but not limited to the film feeding speed being any one of 1 m / min, 2 m / min, 4 m / min, 6 m / min, 8 m / min and 10 m / min or a range between any two of them.

[0091] In this embodiment, in the calendering and merging step, the calendering pressure and the film speed are respectively limited to specific ranges, so that the positive electrode half-cell film material and the negative electrode half-cell film material can be fully in contact and tightly fitted to prepare a high-quality battery cell.

[0092] It should be noted that any process or step not specifically described or limited in the preparation of the battery cell may be performed according to conventional methods in the art.

[0093] Example 1

[0094] The present invention provides a method for preparing a battery cell, comprising the following steps:

[0095] Preparation of pre-supplemented lithium negative electrode sheet

[0096] A 4.5 μm thick polyethylene terephthalate (PET) was selected as the negative electrode polymer substrate layer and placed in the chamber of the magnetron coating equipment. The coating chamber was evacuated to a vacuum degree of 5x10 -3Pa, maintaining the temperature in the chamber at 25°C, introducing argon gas to maintain the air pressure in the chamber at 0.45Pa, and then setting the film speed to 10m / min, and successively plating the Cu layer (negative electrode conductive metal layer, power is 10KW, thickness is 1000nm), Sn layer (first protective layer, power is 1KW, thickness is 10nm), metal Li layer (pre-lithium supplement layer, power is 2KW, thickness is 10nm), and LiZn layer (second protective layer, power is 1KW, thickness is 10nm).

[0097] Then, the plated film was taken out, and the negative electrode active materials graphite, carbon nanotubes and PTFE were mixed evenly according to the mass ratio of 95.5:3.5:1 to obtain the negative electrode slurry; the negative electrode slurry was heated to 240 mg / cm 2 The coating amount is evenly coated on the side of the second protective layer away from the pre-lithium replenishment layer, and is rolled to form a pre-lithium replenishment negative electrode sheet with a total thickness of 148 μm.

[0098] Preparation of positive electrode

[0099] A 4.5 μm thick polyethylene terephthalate (PET) was selected as the positive electrode polymer substrate layer and placed in the chamber of the magnetron coating equipment. The coating chamber was evacuated to a vacuum degree of 5x10 -3 Pa, maintaining the temperature in the chamber at 25°C, introducing argon gas to maintain the air pressure in the chamber at 0.45Pa, and then setting the film walking speed to 12m / min to plate an Al layer (positive electrode conductive metal layer, power of 12KW, thickness of 1000nm) to obtain a positive electrode current collector.

[0100] The positive electrode active materials lithium iron phosphate, PVDF, carbon nanotubes and NMP were mixed uniformly according to a mass ratio of 98:1:1 to obtain a positive electrode slurry with a solid content of 78% and a viscosity of 8200mPa·s; the positive electrode slurry was heated to 530mg / cm 2 The coating amount is evenly coated on the side of the Al layer away from the positive electrode polymer substrate layer, and then rolled after drying to obtain a positive electrode sheet with a total thickness of 125 μm.

[0101] Preparation of battery cells

[0102] The positive electrode sheet and the pre-replenished lithium negative electrode sheet were placed in the unwinding chamber of the magnetron coating equipment, and then the coating chamber was evacuated to a vacuum degree of 5x10 -3 Pa, maintain the temperature in the chamber at 25 ° C, introduce argon gas to maintain the pressure in the chamber at 0.3 Pa, then set the film speed to 5m / min, the target substrate distance to 90mm, and the power to 6KW, and use Li-La-Zr alloy as the target material to simultaneously form Li7La3Zr2O with a thickness of 2μm on the surface of the active layer of the positive electrode sheet and the pre-supplemented lithium negative electrode sheet. 12(solid electrolyte layer), respectively obtain the positive half-cell and the negative half-cell. Then the positive half-cell and the negative half-cell are transported to the calendering chamber of the magnetron coating equipment for calendering and merging, so that the two parts of the solid electrolyte layer are closely attached, wherein the calendering pressure is 8MPa, and the cell is obtained, and then the calendered and merged film material is transported to the winding chamber for winding.

[0103] In order to better understand the complete preparation process of the battery cell, the process flow chart in Example 1 is used for auxiliary explanation. Figure 5 .

[0104] Example 2

[0105] The present embodiment provides a method for preparing a battery cell, which differs from the embodiment 1 only in that:

[0106] Preparation of negative electrode half-cell: oxide solid electrolyte Li7La3Zr2O 12 and PTFE are uniformly dispersed in deionized water at a mass ratio of 96.5:3.5 to obtain a mixed slurry with a solid content of 70%, and the mixed slurry is coated on the negative electrode active layer. After coating and drying, a solid electrolyte layer is formed to obtain a negative electrode half-cell.

[0107] Preparation of positive electrode half-cell: oxide solid electrolyte Li7La3Zr2O 12 and PVDF in a mass ratio of 99:1, and then NMP is added and mixed evenly to obtain a mixed slurry with a solid content of 70%. The viscosity of the mixed slurry is 8000 mPa·s, and the mixed slurry is coated on the positive electrode active layer. After coating and drying, a solid electrolyte layer is formed to obtain a positive electrode half-cell.

[0108] Then the positive electrode half-cell and the negative electrode half-cell are cut into 10*10 cm sheets respectively, and the cut negative electrode half-cell and the positive electrode half-cell with the side coated with the solid electrolyte are placed face to face, stacked together, and compacted to obtain a cell.

[0109] Example 3

[0110] The present embodiment provides a method for preparing a battery cell, which differs from the embodiment 1 only in that:

[0111] Preparation of negative electrode half-cell: Place the pre-filled lithium negative electrode sheet into the unwinding chamber of the magnetron coating equipment, and then evacuate the coating chamber to a vacuum degree of 5x10 -3 Pa, maintain the temperature in the chamber at 25 ° C, introduce argon gas to maintain the pressure in the chamber at 0.3 Pa, then set the film speed to 5m / min, the target substrate distance to 90mm, and the power to 6KW, and use Li-La-Zr alloy as the target to form Li7La3Zr2O on the surface of the active layer of the pre-supplemented lithium negative electrode sheet. 12(solid electrolyte layer) to obtain a negative electrode half-cell.

[0112] Preparation of positive electrode half-cell: oxide solid electrolyte Li7La3Zr2O 12 and PVDF in a mass ratio of 99:1, and then NMP is added and mixed evenly to obtain a mixed slurry with a solid content of 70%. The viscosity of the mixed slurry is 8000 mPa·s, and the mixed slurry is coated on the positive electrode active layer. After coating and drying, a solid electrolyte layer is formed to obtain a positive electrode half-cell.

[0113] Then the positive electrode half-cell and the negative electrode half-cell are cut into 10*10 cm sheets respectively, and the cut negative electrode half-cell and the positive electrode half-cell with the side coated with the solid electrolyte are placed face to face, stacked together, and compacted to obtain a cell.

[0114] Example 4

[0115] The present embodiment provides a method for preparing a battery cell, which differs from the embodiment 1 only in that:

[0116] Preparation of negative electrode half-cell: oxide solid electrolyte Li7La3Zr2O 12 and PTFE are uniformly dispersed in deionized water at a mass ratio of 96.5:3.5 to obtain a mixed slurry with a solid content of 70%, and the mixed slurry is coated on the negative electrode active layer. After coating and drying, a solid electrolyte layer is formed to obtain a negative electrode half-cell.

[0117] Preparation of positive half-cell: Place the positive electrode sheet into the unwinding chamber of the magnetron coating equipment, and then evacuate the coating chamber to a vacuum degree of 5x10 -3 Pa, maintain the chamber temperature at 25 ° C, introduce argon gas to maintain the chamber pressure at 0.3 Pa, then set the film speed to 5m / min, the target substrate distance to 90mm, and the power to 6KW, and use Li-La-Zr alloy as the target to form Li7La3Zr2O on the surface of the active layer of the positive electrode. 12 (solid electrolyte layer), and a positive electrode half-cell is obtained.

[0118] Then the positive electrode half-cell and the negative electrode half-cell are cut into 10*10 cm sheets respectively, and the cut negative electrode half-cell and the positive electrode half-cell with the side coated with the solid electrolyte are placed face to face, stacked together, and compacted to obtain a cell.

[0119] Example 5

[0120] The comparative example of the present application provides a method for preparing a battery cell, which differs from Example 1 only in that: after obtaining the positive electrode half-cell and the negative electrode half-cell respectively, the two are taken out and then cut into 10*10 cm sheets respectively, and the cut negative electrode half-cell and the positive electrode half-cell with the side coated with solid electrolyte are placed face to face, stacked together, and compacted to obtain a battery cell.

[0121] Comparative Example 1

[0122] The comparative example of the present application provides a method for preparing a battery cell, which is different from Example 1 only in that the first protective layer is not formed in the pre-supplemented lithium negative electrode sheet.

[0123] Comparative Example 2

[0124] The comparative example of the present application provides a method for preparing a battery cell, which is different from Example 1 only in that a second protective layer is not formed in the pre-supplemented lithium negative electrode sheet.

[0125] Comparative Example 3

[0126] The comparative example of the present application provides a method for preparing a battery cell, which is different from Example 1 only in that a pre-supplemented lithium layer is not formed in the pre-supplemented lithium negative electrode sheet.

[0127] Test example

[0128] Electrical performance test

[0129] Test method:

[0130] The battery cells prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were numbered respectively, and then each sample was hot-pressed and packaged to prepare a battery, and then the discharge capacity of each battery and the effective cycle number of the battery cells were tested and counted in Table 1, and when the capacity retention rate of the battery was lower than 80%, the battery was disassembled to observe whether there was lithium dendrite powder on the surface of the negative electrode plate and the area size of the negative electrode plate surface covered by the lithium dendrite powder was counted, and the results were counted in Table 1.

[0131] The test steps for discharge capacity are as follows:

[0132] The test battery was placed in a test environment of (25±1)℃, charged to 3.8V at 0.5C constant current, then allowed to stand for 5 minutes, and then discharged to 2.5V at 0.5C constant current, then allowed to stand for 5 minutes. This is one charge and discharge cycle, and the discharge capacity this time is recorded as the discharge capacity of the battery in the first cycle.

[0133] The test steps for the effective cycle number of the battery are as follows:

[0134] The test battery was placed in a test environment of (25±1)℃, discharged at a constant current of 0.5C to 2.5V, left standing for 30 minutes, then charged at a constant current of 0.2C to a termination voltage of 4.2V, then switched to constant voltage charging with a charge termination current of 0.02C, and left standing for 30 minutes.

[0135] The charge and discharge steps are continuously cycled until the discharge capacity is less than 80% of the rated capacity. The number of cycles at this time is recorded, which is the effective cycle number of the lithium battery.

[0136] Table 1

[0137]

[0138]

[0139] Referring to Table 1, it can be seen from the test results of Example 1 and Comparative Examples 1 to 2 that the pre-replenished lithium negative electrode sheet has a specific structure provided in the embodiment of the present application. Compared with not providing the first protective layer or the second protective layer, the former can improve the problems of the pre-replenished lithium negative electrode sheet easily forming dead lithium on the negative electrode surface and the poor timeliness of the pre-replenished lithium layer, thereby making the corresponding battery cell have a relatively excellent discharge capacity.

[0140] It can be seen from the test results of Examples 1 and 2 to 4 that the solid electrolyte layer is formed on the positive electrode sheet and the pre-supplemented lithium negative electrode sheet respectively by magnetron sputtering coating, compared with the conventional wet coating method. Since the wet coating method requires a drying step, the vapor of the electrolyte will escape from the electrolyte layer to form pores during drying, resulting in a high interface resistance between the electrolyte layer and the electrode sheet and the negative electrode sheet is prone to lithium dendrites; while the magnetron sputtering electrolyte layer does not need to be dried, the interface resistance between the prepared solid electrolyte layer and the electrode sheet is low and it is not easy to cause the negative electrode sheet to generate lithium dendrites, thereby making the corresponding battery have a relatively excellent discharge capacity and cycle performance.

[0141] It can be seen from the test results of Example 1 and Example 5 that the production of the positive and negative electrode half-cells and the assembly of the positive and negative electrode half-cells are all completed in the vacuum chamber of magnetron sputtering. Due to the advantage of high cleanliness, compared with taking the positive and negative electrode half-cells out of the vacuum chamber and assembling them in the air, the cells prepared by the former have better discharge capacity and cycle performance.

[0142] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pre-supplemented lithium negative electrode sheet, characterized in that: It comprises a negative electrode polymer substrate layer, a negative electrode conductive metal layer, a first protective layer, a pre-lithium supplement layer, a second protective layer and a negative electrode active layer which are stacked and distributed in sequence; Wherein, the material of the first protective layer can conduct electrons and can form an alloy with lithium metal; The material of the second protective layer can conduct electrons and ions, and / or the material of the second protective layer can be decomposed during the operation of the battery.

2. The pre-lithium supplemented negative electrode sheet according to claim 1, characterized in that: The material of the first protective layer is selected from at least one of C, Sn, Zn, Au, Ag, Si, Sb and Bi; And / or, the material of the second protective layer is selected from at least one of LiZn, ZrO2, LiSn, Li2O2, LiO2, Li3N, polymethyl methacrylate, polyethylene oxide and polyvinylidene fluoride.

3. The pre-lithium supplemented negative electrode sheet according to claim 2, characterized in that: The thickness of the first protective layer is 1 to 100 nm; And / or, the thickness of the second protective layer is 10-100 nm.

4. The pre-lithium supplemented negative electrode sheet according to any one of claims 1 to 3, characterized in that: The material of the pre-lithium replenishment layer is metallic lithium, and / or the thickness of the pre-lithium replenishment layer is 10-20 nm.

5. The pre-lithium supplemented negative electrode sheet according to any one of claims 1 to 3, characterized in that: The thickness of the negative electrode conductive metal layer is 500 to 1500 nm; And / or, the thickness of the negative electrode active layer is 10 to 200 μm.

6. A method for preparing a pre-lithium supplemented negative electrode sheet as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: Providing a negative electrode current collector, the negative electrode current collector comprising the negative electrode polymer substrate layer and the negative electrode conductive metal layer which are stacked and distributed in sequence; The first protective layer, the pre-lithium replenishment layer, the second protective layer and the negative electrode active layer are sequentially formed on the side of the negative electrode conductive metal layer away from the negative electrode polymer substrate layer, wherein the pre-lithium replenishment layer and the second protective layer are sequentially and continuously completed under vacuum conditions in the same magnetron sputtering equipment, and the negative electrode active layer is formed by dry coating of negative electrode slurry.

7. A battery cell, characterized in that: The invention comprises a positive electrode sheet, a solid electrolyte layer and a pre-lithium supplemented negative electrode sheet as claimed in any one of claims 1 to 5 which are stacked and distributed in sequence.

8. A method for preparing a battery cell as claimed in claim 7, characterized in that: The following steps are involved: S1: preparing materials: providing the positive electrode sheet and the pre-lithium supplemented negative electrode sheet; Preparation of S2 half-cell: forming a part of the solid electrolyte layer on the surface of the positive electrode active layer in the positive electrode sheet by magnetron sputtering coating to obtain a positive electrode half-cell; and forming another part of the solid electrolyte layer on the surface of the negative electrode active layer in the pre-replenished lithium negative electrode sheet by magnetron sputtering coating to obtain a negative electrode half-cell; S3 rolling and merging: rolling and merging the positive electrode half-cell and the negative electrode half-cell on one side with the solid electrolyte layer to obtain the cell; The step of preparing the half-cell and the step of calendering and combining are completed sequentially and continuously under vacuum conditions in the same magnetron sputtering equipment.

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