Composite current collector, composite pole piece, lithium battery and manufacturing method thereof

Abstract

The present disclosure provides a composite current collector, a composite pole piece, a lithium battery and a manufacturing method thereof, wherein the composite current collector comprises: a substrate; a plurality of first linear conductive structures, wherein the plurality of first linear conductive structures extend along the substrate surface in parallel and at a preset interval; a first coating layer, which continuously wraps around a side of the plurality of first linear conductive structures away from the substrate and a side surface of each first linear conductive structure, so that the first coating layer overlaps with the substrate in an orthographic projection on the substrate; a plurality of second linear conductive structures, wherein the plurality of second linear conductive structures extend along the substrate surface in parallel and at a preset interval; a second coating layer, which continuously wraps around a side of the plurality of second linear conductive structures away from the substrate and a side surface of each second linear conductive structure, so that the second coating layer overlaps with the substrate in an orthographic projection on the substrate; wherein the plurality of first linear conductive structures and the plurality of second linear conductive structures are symmetrically arranged relative to the substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to Chinese Patent Application No. 202310798526.8 filed in China on June 30, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the technical field of lithium batteries, and in particular to a composite current collector, a composite pole piece, a lithium battery and a manufacturing method thereof. Background Art

[0004] Lithium-ion batteries, or lithium batteries for short, are widely used in people's daily lives as a highly efficient energy storage device. Traditional lithium-ion battery cells contain pairs of positive and negative electrodes, which are stacked in multiple layers or wound together to create battery cells of different capacities. In traditional lithium-ion batteries, aluminum foil is used as the positive current collector metal material, and copper foil is used as the negative current collector metal material. On the one hand, this wastes copper resources. On the other hand, due to the thick thickness of the copper foil, the overall size of the lithium battery is larger, and the surface of the copper foil is easily corroded, which increases the internal resistance of the battery. Summary of the invention

[0005] The purpose of the present disclosure is to provide a composite current collector, a composite pole piece, a lithium battery and a method for manufacturing the same, which can at least solve the current technical problem of surface oxidation or corrosion of lithium batteries.

[0006] The present disclosure provides a composite current collector for a lithium battery, comprising:

[0007] substrate;

[0008] A plurality of first linear conductive structures, wherein the plurality of first linear conductive structures extend substantially in parallel along the surface of the substrate at a preset interval;

[0009] A first cladding layer is continuously wrapped around a side of the plurality of first linear conductive structures away from the substrate, and is continuously wrapped around a side surface of each of the first linear conductive structures, so that an orthographic projection of the first cladding layer on the substrate overlaps with the substrate;

[0010] A plurality of second linear conductive structures, wherein the plurality of second linear conductive structures extend substantially in parallel along the surface of the substrate at the preset interval;

[0011] A second cladding layer is continuously wrapped around a side of the plurality of second linear conductive structures away from the substrate, and is continuously wrapped around a side surface of each of the second linear conductive structures, so that an orthographic projection of the second cladding layer on the substrate overlaps with the substrate;

[0012] Wherein, the plurality of first linear conductive structures and the plurality of second linear conductive structures are symmetrically arranged relative to the substrate.

[0013] In some embodiments, the composite current collector further comprises:

[0014] A first bonding layer is disposed between the plurality of first linear conductive structures and the substrate by physical vapor deposition, and is configured to stably bond the plurality of first linear conductive structures and the substrate;

[0015] The second bonding layer is disposed between the plurality of second linear conductive structures and the substrate by physical vapor deposition, and is configured to stably bond the plurality of second linear conductive structures and the substrate.

[0016] In some embodiments, the physical vapor deposition is selected from at least one of the following: vacuum sputtering, vacuum ion plating or vacuum evaporation.

[0017] In some embodiments, the first coating layer comprises:

[0018] A first isolation layer is disposed on a side of the first coating layer away from the substrate;

[0019] A first intermediate layer, disposed on a side of the first cladding layer close to the substrate, configured to prevent diffusion between the first isolation layer and the first linear conductive structure;

[0020] A first anti-oxidation layer is disposed on a side of the first isolation layer away from the substrate and is configured to prevent oxidation of the first isolation layer; and

[0021] The second coating layer comprises:

[0022] A second isolation layer is disposed on a side of the second coating layer away from the substrate;

[0023] a second intermediate layer, disposed on a side of the second cladding layer close to the substrate, and configured to prevent diffusion between the second isolation layer and the second linear conductive structure;

[0024] The second anti-oxidation layer is disposed on a side of the second isolation layer away from the substrate and is configured to prevent the second isolation layer from being oxidized.

[0025] In some embodiments, the orthographic projections of the first isolation layer, the first intermediate layer, and the first anti-oxidation layer on the substrate overlap; and

[0026] The orthographic projections of the second isolation layer, the second intermediate layer, and the second anti-oxidation layer on the substrate overlap.

[0027] In some embodiments, the tensile strength of the material of the substrate is ≥150 MPa; or,

[0028] The thermal shrinkage rate of the substrate material after being treated at 150° C. for 30 minutes is ≤3%; or,

[0029] The thickness of the substrate is 1-10 μm.

[0030] In some embodiments, the thickness of the first linear conductive structure and / or the second linear conductive structure is 0.1-2 μm respectively; or,

[0031] The bonding force between the first linear conductive structure and / or the second linear conductive structure and the substrate is ≥ 0.5 N / 15 mm;

[0032] The resistivity of the first linear conductive structure and / or the second linear conductive structure is ≤8 μΩ·cm.

[0033] In some embodiments, the material of the first linear conductive structure and / or the second linear conductive structure is Al, and the material of the first isolation layer and / or the second isolation layer is Cu.

[0034] In some embodiments, the thickness of the first isolation layer and the second isolation layer are 1-1500 nm respectively; or,

[0035] The bonding force between the first isolation layer and the first conductive layer and / or the bonding force between the second isolation layer and the second conductive layer is ≥ 0.5 N / 15 mm.

[0036] In some embodiments, the first isolation layer and the second isolation layer are made of the same material, the first linear conductive structure and the second linear conductive structure are made of the same material; the first intermediate layer and the second intermediate layer are made of the same material; the first isolation layer, the first linear conductive structure and the first intermediate layer are made of different materials.

[0037] In some embodiments, the first anti-oxidation layer and / or the second anti-oxidation layer is selected from at least one of the following: a chromium passivation solution, a chromium-free passivation solution, or an organic passivation solution.

[0038] The present disclosure also provides a composite pole piece, which includes the composite current collector as described in any one of the above items.

[0039] The present disclosure also provides a lithium battery, comprising the composite pole piece as described above.

[0040] The present disclosure also provides a method for manufacturing a composite current collector, the manufacturing method comprising:

[0041] providing a substrate;

[0042] Arranging a plurality of first linear conductive structures extending along the surface of the substrate substantially in parallel at a preset interval;

[0043] A first coating layer is provided to continuously coat the first linear conductive structures on a side away from the substrate and to continuously coat the side of each of the first linear conductive structures, so that the orthographic projection of the first coating layer on the substrate overlaps with the substrate;

[0044] Arrange a plurality of second linear conductive structures substantially parallel to and extending along the surface of the substrate at a preset interval;

[0045] A second coating layer is provided to continuously wrap around a side of the plurality of second linear conductive structures away from the substrate, and continuously wrap around a side surface of each of the second linear conductive structures, so that an orthographic projection of the second coating layer on the substrate overlaps with the substrate;

[0046] Wherein, the plurality of first linear conductive structures and the plurality of second linear conductive structures are symmetrically arranged relative to the substrate.

[0047] In some embodiments, the method further comprises:

[0048] At least a first bonding layer is provided between the plurality of first linear conductive structures and the substrate, so that the plurality of first linear conductive structures and the substrate are stably bonded;

[0049] A second bonding layer is disposed at least between the plurality of second linear conductive structures and the substrate, so as to stably bond the plurality of second linear conductive structures to the substrate.

[0050] In some embodiments, the method further comprises:

[0051] The first coating layer is arranged to continuously wrap around a side of the plurality of first linear conductive structures away from the substrate, and continuously wrap around a side surface of each of the first linear conductive structures, including:

[0052] Disposing a first intermediate layer on a side of the first isolation layer close to the first linear conductive structure;

[0053] A first isolation layer is disposed on a side of the first intermediate layer away from the substrate, wherein the first intermediate layer is configured to prevent diffusion between the first isolation layer and the first linear conductive structure, and

[0054] The second coating layer is arranged to continuously wrap around a side of the plurality of second linear conductive structures away from the substrate, and continuously wrap around a side surface of each of the second linear conductive structures, including:

[0055] Disposing a second intermediate layer on a side of the second isolation layer close to the second linear conductive structure;

[0056] A second isolation layer is disposed on a side of the second intermediate layer away from the substrate, wherein the second intermediate layer is configured to prevent diffusion between the second isolation layer and the second linear conductive structure.

[0057] In some embodiments, it also includes:

[0058] Disposing a first anti-oxidation layer on a side of the first isolation layer away from the substrate; and

[0059] A second anti-oxidation layer is disposed on a side of the second isolation layer away from the substrate.

[0060] In some embodiments, a method of providing a first anti-oxidation layer on a side of the first isolation layer away from the substrate and / or providing a second anti-oxidation layer on a side of the second isolation layer away from the substrate comprises at least one of the following:

[0061] Doctor coating, roller coating, spray coating, chemical vapor deposition, plasma vapor deposition, atomic layer deposition, pulsed laser deposition, vacuum evaporation, ion plating, radio frequency sputtering, magnetron sputtering or reactive sputtering.

[0062] In some embodiments, the method of providing a first anti-oxidation layer on a side of the first isolation layer away from the substrate and / or providing a second anti-oxidation layer on a side of the second isolation layer away from the substrate comprises:

[0063] forming an oxide layer of the first isolation layer on a side of the first isolation layer away from the substrate by spraying or immersing the first isolation layer with a chromium passivation solution, a chromium-free passivation solution or an organic passivation solution; and,

[0064] An oxide layer of the second isolation layer is formed on the side of the second isolation layer away from the substrate by spraying or immersing the second isolation layer with a chromium passivation solution, a chromium-free passivation solution or an organic passivation solution.

[0065] The present disclosure also provides a method for manufacturing a composite pole piece, including the method for manufacturing a composite current collector as described in any one of the above items.

[0066] The present disclosure also provides a method for manufacturing a lithium battery, including the method for manufacturing the composite pole piece as described above.

[0067] Compared with the related art, the present invention has the following technical effects:

[0068] 1. The negative electrode composite current collector provided in the present disclosure can replace traditional copper as the negative electrode current collector, saving copper resources and costs;

[0069] 2. The barrier layer in the present disclosure is a continuous and dense thin film structure, which can prevent the alloying of the negative electrode Li-Al material and improve the conductivity of the composite current collector;

[0070] 3. By providing a protective layer in the composite current collector, the interface resistance between the current collector and the active material can be reduced, thereby reducing the internal resistance of the lithium ion battery prepared using the composite current collector of the present disclosure, and improving the rate performance and cycle performance of the lithium ion battery;

[0071] 4. A covering layer is provided outside the discrete linear conductive structure in the negative electrode composite current collector disclosed in the present invention, which can prevent Li-Al end corrosion during cutting and application;

[0072] 5. The negative electrode composite current collector disclosed in the present invention can be made very thin, which can improve the effective energy volume ratio of the lithium battery;

[0073] 6. Use the PVD method to design a bonding layer structure between the polymer layer and the conductive layer to enhance the bonding force between the polymer layer and the conductive layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0075] Figure 1 A schematic diagram of a cross-sectional structure of a composite current collector provided in some embodiments of the present disclosure, cut along line N;

[0076] Figure 2 A schematic diagram of the cross-sectional structure of another side of a composite current collector provided in some embodiments of the present disclosure;

[0077] Figure 3 Schematic diagram of the cross-sectional structure of a composite current collector provided in some other embodiments of the present disclosure;

[0078] Figure 4 A flow chart of a method for manufacturing a composite current collector provided in some embodiments of the present disclosure;

[0079] Figure 5 A flow chart of a method for manufacturing a composite current collector provided for other embodiments of the present disclosure; and

[0080] Figure 6 A flow chart of a method for manufacturing a composite current collector provided in some other embodiments of the present disclosure. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0082] The terms used in the embodiments of the present disclosure are only for the purpose of describing specific embodiments, and are not intended to limit the present disclosure. The singular forms "a", "said" and "the" used in the embodiments of the present disclosure and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0083] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0084] It should be understood that although the terms first, second, third, etc. may be used to describe in the present disclosure, these should not be limited to these terms. These terms are only used to distinguish. For example, without departing from the scope of the present disclosure, the first may also be referred to as the second, and similarly, the second may also be referred to as the first.

[0085] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such product or device. In the absence of more restrictions, the elements defined by the sentence "comprises a" do not exclude the presence of other identical elements in the product or device including the elements.

[0086] In the related art, lithium batteries usually include positive and negative electrodes, and the positive and negative electrodes are stacked in multiple layers or wound in positive and negative electrodes to realize battery cells of different capacities. The positive electrode usually includes a positive current collector and a positive active material coated on both sides of the positive current collector. Lithium-ion batteries generally use aluminum as the positive current collector metal material and copper as the negative current collector metal material. This is because the oxidation potential of metal aluminum is high, and the size of the lattice octahedral voids of metal aluminum is similar to that of lithium, making it very easy for metal aluminum to react with lithium to form alloys such as LiAl, Li3Al2, and Li4Al3, which not only consumes a large amount of Li+, but also destroys the structure and morphology of metal aluminum itself. Therefore, aluminum can be used as a current collector for the positive electrode of lithium-ion batteries, but not as a current collector for the negative electrode of lithium-ion batteries. Cu has only a small lithium insertion capacity during the battery charging and discharging process, and maintains the stability of the structure and electrochemical properties, so it can be used as a current collector for the negative electrode of ion batteries.

[0087] In traditional lithium-ion batteries, aluminum foil is used as the positive electrode current collector metal material, and copper foil is used as the negative electrode current collector metal material. On the one hand, copper resources are wasted. On the other hand, due to the thick thickness of the copper foil, the overall size of the lithium battery is larger, and the surface of the copper foil is easily corroded, which increases the internal resistance of the battery.

[0088] The embodiment of the present disclosure provides a composite current collector for lithium batteries, comprising: a substrate; a plurality of first linear conductive structures, the plurality of first linear conductive structures extending along the surface of the substrate in parallel and at a preset interval; a first coating layer continuously wrapped around a side of the plurality of first linear conductive structures away from the substrate and a side surface of each of the first linear conductive structures, so that the first coating layer overlaps with the substrate in an orthographic projection of the substrate; a plurality of second linear conductive structures, the plurality of second linear conductive structures extending along the surface of the substrate in parallel and at the preset interval; a second coating layer continuously wrapped around a side of the plurality of second linear conductive structures away from the substrate and a side surface of each of the second linear conductive structures, so that the second coating layer overlaps with the substrate in an orthographic projection of the substrate; wherein the plurality of first linear conductive structures and the plurality of second linear conductive structures are symmetrically arranged relative to the substrate.

[0089] The optional embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0090] Figure 1 A schematic diagram of a cross-sectional structure of a composite current collector provided in some embodiments of the present disclosure cut along line N;

[0091] Figure 2A schematic diagram of the cross-sectional structure of the other side of a composite current collector provided in some embodiments of the present disclosure; specifically, an embodiment of the present disclosure provides a negative electrode composite current collector 100 for a lithium battery, the negative electrode composite current collector 100 comprising: a substrate 1; a first conductive layer 2 formed by a plurality of first linear conductive structures, the first conductive layer 2 being disposed on one side of the substrate 1, the first conductive layer 2 comprising a plurality of discrete first linear conductive structures; a first bonding layer 8, the first bonding layer 8 being disposed between the first conductive layer 2 and the substrate 1, and configured to bond the first conductive layer 2 and the substrate 1; a first coating layer 30, continuously wrapped around a side of the plurality of first linear conductive structures away from the substrate 1 and a side surface of each of the first linear conductive structures, so that the first coating layer 30 overlaps with the substrate in its orthographic projection on the substrate 1; a second conductive layer 3 formed by a plurality of second linear conductive structures, the second conductive layer 3 being disposed on a side of the substrate 1 away from the first conductive layer 2, the second conductive layer 3 includes a plurality of discrete second linear conductive structures; a second bonding layer 9, which is arranged between the second conductive layer 3 and the substrate 1 and configured to bond the second conductive layer 3 and the substrate 1; a second cladding layer 20, which continuously wraps around the side of the plurality of second linear conductive structures away from the substrate 1 and the side of each of the second linear conductive structures, so that the second cladding layer 20 overlaps with the substrate in the positive projection of the substrate 1; wherein the plurality of discrete first linear conductive structures and the plurality of discrete second linear conductive structures are symmetrically arranged relative to the substrate 1, so that when cutting along a direction perpendicular to the substrate surface and along the gaps between the plurality of discrete first linear conductive structures or the plurality of discrete second linear conductive structures, the first linear conductive structure or the second linear conductive structure may not be cut, so that the first linear conductive structure or the second linear conductive structure can still be wrapped by the first cladding layer 30 or the second cladding layer 20 without being exposed, thereby avoiding corrosion of the end.

[0092] Specifically, Figure 2 As shown, the first conductive layer 2 includes a plurality of discrete first linear conductive structures, the second conductive layer 3 includes a plurality of discrete second linear conductive structures, the first linear conductive structure and the second linear conductive structure are respectively wrapped by the first coating layer 30 and the second coating layer 20, when a small area of ​​the negative electrode composite current collector 100 is cut out from a large area of ​​the negative electrode composite current collector 100, for example, when the negative electrode composite current collector 100 is used for the assembly of the lithium battery, it can be cut out along the first coating layer 30 and the second coating layer 20. Figure 2The M-line cutting is used, so that the ends of the first conductive layer 2 and the second conductive layer 3 will not be exposed, and the first conductive layer 2 and the second conductive layer 3 will not be oxidized or corroded due to exposure to the air. Among them, the first linear conductive structure and the second linear conductive structure can be straight-line or curved structures. As long as they are discretely and roughly arranged in parallel along the surface of the substrate 1, the problem of exposed ends due to cutting can be solved. The multiple discrete first linear conductive structures and the multiple discrete second linear conductive structures are symmetrically arranged relative to the substrate to ensure that when cutting, they can be cut from the groove on one side (without conductive layer) to the corresponding groove on the other side (without conductive layer), and avoid cutting the conductive layer to expose it. The linear conductive structure can be a regular rectangular parallelepiped structure or an irregular long strip structure. Its cross-section can be any structure such as a rectangle, square, ellipse, polygon, triangle, arc, etc., which will not be elaborated.

[0093] In some embodiments, Figure 2 As shown, the orthographic projection of the first cladding layer 30 on the substrate 1 covers the orthographic projection of the first conductive layer 2 on the substrate 1; and the orthographic projection of the second cladding layer 20 on the substrate 1 covers the orthographic projection of the second conductive layer 3 on the substrate 1. The projections of the first linear conductive structure and the second linear conductive structure on the substrate 1 are roughly overlapped, so that it can be ensured that as long as cutting is carried out between the linear conductive structures, the ends of the first conductive layer 2 and the second conductive layer 3 will not be exposed.

[0094] In some embodiments, Figure 2 As shown, the orthographic projection of the first bonding layer 8 on the substrate 1 overlaps with the orthographic projection of the first conductive layer 2 on the substrate 1; and the orthographic projection of the second bonding layer 9 on the substrate 1 overlaps with the orthographic projection of the second conductive layer 3 on the substrate 1, so as to ensure that the first conductive layer 2 is completely bonded to the substrate 1, and the second conductive layer 3 is completely bonded to the substrate 1. In the formation process, for example, a mask can be set to deposit bonding materials in the mask gap by magnetron sputtering, ion plating, vacuum evaporation or in-situ reaction, and then a conductive layer is deposited, so as to form a structure in which the conductive layer and the bonding layer are stacked, so that the conductive layer can be stably bonded to the substrate through the bonding layer.

[0095] In some other embodiments, Figure 3As shown, the first bonding layer 8 overlaps with the substrate 1 in the orthographic projection of the substrate 1; and the second bonding layer 9 overlaps with the substrate 1 in the orthographic projection of the substrate 1, and then a first conductive layer 2 is formed on the first bonding layer 8, and a second conductive layer 3 is formed on the second bonding layer 9 to ensure that the first conductive layer 2 is completely bonded to the substrate 1, and the second conductive layer 3 is completely bonded to the substrate 1. In the formation process, for example, the bonding material can be deposited on both sides of the substrate 1 by magnetron sputtering, ion plating, vacuum evaporation or in-situ reaction, and then a conductive layer is deposited in the mask gap by magnetron sputtering, ion plating, vacuum evaporation or in-situ reaction by setting a mask, so as to form a structure in which the conductive layer and the bonding layer are stacked, so that the conductive layer can be stably bonded to the substrate through the bonding layer.

[0096] In some embodiments, the substrate 1 is selected from at least one of acrylonitrile-butadiene-styrene copolymer, polyterephthalate, polybutylene terephthalate, poly(p-phenylene terephthalamide), polyimide, polyamide, polyethylene, polystyrene, polyvinylidene fluoride, polyvinyl chloride, polytetrafluoroethylene, polypropylene, polypropylene, polycarbonate, polyoxymethylene, epoxy resin and phenolic resin. Compared with the traditional copper foil layer, the substrate is lighter and can be set thinner, which is conducive to reducing the volume of the lithium battery and improving the performance of the lithium battery.

[0097] In some embodiments, the tensile strength of the material of the substrate 1 is ≥150MPa, preferably 150-400MPa; the substrate 1 is used to support the entire negative electrode composite current collector. During the deposition process of the negative electrode composite current collector, the coating roller pressing process requires the support of a high tensile strength substrate to prevent the roll from breaking and deforming. Therefore, when the tensile strength is <150Mpa, it cannot meet the supporting function during the coating roller pressing process, and roll breaking and deformation are likely to occur. The thermal shrinkage rate of the material of the substrate 1 after being treated at 150°C for 30 minutes is ≤3%. If the thermal shrinkage rate of the substrate 1 is too large, it will also cause the negative electrode composite current collector to break and deform. Therefore, after experimental verification, the thermal shrinkage rate of the material of the substrate 1 after being treated at 150°C for 30 minutes should be less than or equal to 3% to meet the negative electrode composite current collector production process; the thickness of the substrate 1 is 1-15μm, preferably 1-10μm. If the substrate 1 is too thick, the volume of the negative electrode composite current collector and the internal resistance of the lithium battery will be increased. Therefore, the substrate 1 with the thickness in the above range is selected in the present disclosure. The substrate 1 has the characteristics of light weight, good ductility, high tensile strength, and low thermal shrinkage rate, which can effectively reduce the volume and weight of the lithium battery. Moreover, due to the presence of the substrate 1, even if the conductive layer is broken down, it will not form a short circuit of the battery, thereby improving the safety of the battery.

[0098] In some embodiments, the material of the first conductive layer 2 and / or the second conductive layer 3 is selected from at least one of the following: selected from a single metal with a purity of ≥98wt%: aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum or tungsten; preferably one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum and tungsten with a purity of 99-100wt%; or; selected from an alloy, wherein the metal in the alloy is selected from at least one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum, tungsten, manganese, magnesium and zinc, and / or the non-metal in the alloy is selected from silicon and / or carbon. Preferably, the alloy is selected from at least one of aluminum-copper alloy, aluminum-manganese alloy, aluminum-silicon alloy, aluminum-magnesium alloy, aluminum-magnesium-silicon alloy and aluminum-zinc alloy. The higher the purity of the conductive layer material, the better the conductivity, which is more conducive to enhancing the conductive efficiency.

[0099] In some embodiments, the first conductive layer 2 and / or the second conductive layer 3 are most preferably made of aluminum, which has the characteristics of good conductivity, light weight, low price, good flexibility, etc. Therefore, in this embodiment, aluminum is preferably used as the conductive material when preparing the first conductive layer 2 and / or the second conductive layer 3. Aluminum is selected as the material of the first conductive layer 2 and / or the second conductive layer 3, and an aluminum layer is deposited on the substrate 1 by PVD, which enhances the conductivity, and the aluminum layer is wrapped between the substrate and the coating layer, which overcomes the defect that aluminum cannot be used as a negative electrode in traditional lithium batteries, further reduces the thickness of the negative electrode without weakening the conductive performance of the negative electrode.

[0100] In some embodiments, the thickness of the first conductive layer 2 and / or the second conductive layer 3 is 0.1-2 μm, respectively; preferably 0.2-1.5 μm; vacuum equipment can achieve vacuum deposition at the micron level. The thicker the metal conductive layer, the lower the resistance. However, the thickening of the metal layer increases the difficulty of the process feasibility. In the experiment disclosed in this disclosure, a film of 800 nanometers to 2000 nm can be formed at one time. Through the optimization of process parameters, the resistivity of the metal film in the thickness range of 800 to 1500 nm is relatively stable. For the directional movement of free electrons in the conductive layer, as long as it is a continuous film (thickness ≥ 30 nm), a stable conductive effect can be formed. However, if the conductive layer is too thin, due to the excessive size effect of the metal film, the resistivity will be very high, affecting the internal resistance of the battery cell. Therefore, after experiments, the present disclosure selects a conductive layer with a thickness of more than 200 nm.

[0101] In some embodiments, the bonding force between the first conductive layer 2 and / or the second conductive layer 3 and the substrate 1 is ≥0.5N / 15mm to avoid the first conductive layer 2 and / or the second conductive layer 3 being peeled off from the substrate 1 during curling or application, thereby affecting conductivity.

[0102] In some embodiments, the resistivity of the first conductive layer 2 and / or the second conductive layer 3 is ≤8 μΩ·cm.

[0103] Due to the different inherent properties of the materials between the substrate and the metal conductive layer, the interface bonding is not strong, because there is only van der Waals force between the two, and there is no chemical bond. Therefore, the desired composite current collector structure is a composite structure with high conductivity and high bonding strength. The greater the bonding force, the better, ≥0.5N / 15mm, with no upper limit. The resistivity of the bulk metal material ≤ the resistivity of the composite current collector ≤8uΩ·cm.

[0104] In some embodiments, the first coating layer 30 includes: a first isolation layer 4, which is disposed on the side of the first conductive layer 2 away from the substrate 1, a first intermediate layer 6, which is disposed on the side of the first isolation layer 4 close to the first conductive layer 2, and the first intermediate layer 6 is configured to prevent diffusion between the first isolation layer 4 and the first conductive layer 2; and the second coating layer 20 includes: a second isolation layer 5, which is disposed on the side of the second conductive layer 3 away from the substrate 1, a second intermediate layer 7, which is disposed on the side of the second isolation layer 5 close to the second conductive layer 3, and the second intermediate layer 7 is configured to prevent diffusion between the second isolation layer 5 and the second conductive layer 3. The first coating layer 30 and the second coating layer 20 completely wrap the first conductive layer 2 and the second conductive layer 3, making aluminum a feasible solution as a negative electrode, and due to the discrete structural design and the wrapping coating layer, the problem of exposing the end of the aluminum layer due to cutting when making a lithium battery is overcome.

[0105] In some embodiments, the material of the first isolation layer 4 and / or the second isolation layer 5 is selected from at least one of the following: selected from a single metal with a purity ≥98wt%: aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum or tungsten; preferably one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum and tungsten with a purity of 99-100wt%; or; selected from an alloy, wherein the metal in the alloy is selected from at least one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum and tungsten; further preferably, the alloy is selected from at least one of copper-aluminum alloy, copper-nickel alloy, copper-zinc alloy and copper-tin alloy.

[0106] In some embodiments, the thickness of the first isolation layer 4 and the second isolation layer 5 are respectively 1-1500nm, preferably 30-1000nm; compared with the traditional copper foil negative electrode, the first isolation layer 4 and the second isolation layer 5 can be deposited with a thinner copper layer by PVD, saving copper materials and reducing the overall thickness of the negative electrode sheet.

[0107] In some embodiments, the bonding force between the first isolation layer 4 and the first conductive layer 2 and / or the bonding force between the second isolation layer 5 and the second conductive layer 3 is ≥ 0.5N / 15mm. The strong bonding force prevents the first isolation layer 4 from peeling off from the first conductive layer 2 or the second isolation layer 5 from peeling off from the second conductive layer 3 during curling or application, thereby affecting the conductivity.

[0108] The function of the isolation layer is to prevent the exposure of the Al in the conductive layer. This operation can be achieved as long as the isolation layer is a continuous and dense film (for example, a thickness ≥ 30nm). Another function of the isolation layer is conductivity. However, if the isolation layer is too thin (tens of nanometers), it will diffuse with the conductive layer in a short period of time (a few days or weeks), exposing Al and losing the original function of the isolation layer. If the isolation layer is too thick, it will increase the process cost, material utilization efficiency, etc. Therefore, the isolation layer can be set between 1 and 1500nm, preferably 30-1000nm.

[0109] The conductive layer and the isolation layer will have a weak interface bonding phenomenon, because there is only van der Waals force between the two, and there is no chemical bond. In addition, an aluminum oxide film will naturally form on the aluminum surface of the conductive layer, resulting in a low bonding strength between Cu and Al. If CuAl is delaminated due to low bonding strength during the use of the battery, it will lose its conductive function. Therefore, it is hoped that the bonding strength between the two is ≥0.5N / 15mm.

[0110] Since aluminum is used as the conductive layer and the aluminum composite current collector is used as the negative electrode, it will undergo an alloying reaction with metallic lithium, resulting in failure of the conductive performance. Therefore, an isolation layer (Cu) is provided on the aluminum layer to form an aluminum-copper coating layer. This can isolate the alloying reaction between Li-Al without reducing the conductivity, thereby improving the stability of the lithium battery.

[0111] In some embodiments, when Al as a conductive layer and Cu as an isolation layer are both at the negative electrode, Al-Cu interdiffusion and galvanic corrosion may occur under the action of the electrolyte. Designing an intermediate layer between Al and Cu can prevent or slow down the interdiffusion and corrosion between Al and Cu, and at the same time can also play a conductive role and enhance the bonding force between aluminum and copper. Specifically, the material of the first intermediate layer 6 and / or the second intermediate layer 7 is selected from at least one of the following: a single metal, an alloy, an oxide semiconductor or a conductive compound.

[0112] In some embodiments, the material of the first intermediate layer 6 and / or the second intermediate layer 7 is selected from at least one of the following: the single metal is selected from one of Cu, Cr, Ta, Zn, Cd, In, Tl, Mn, Co, Mo, Fe, Sn, Ge, Bi, Sb, Re, Ti, V, Ni, Nb and Tc; the metal in the alloy is selected from at least one of Cu, Cr, Ta, Zn, Cd, In, Tl, Mn, Co, Mo, Fe, Sn, Ge, Bi, Sb, Re, Ti, V, Ni, Nb and Tc A method of manufacturing a semiconductor material comprising: the oxide semiconductor being selected from at least one of Cu2O, ZnO, SnO2, Fe2O3, TiO2, ZrO2, Co2O3, WO3, In2O3, Al2O3 and Fe3O4; and the conductive compound being selected from at least one of TiB2, TiC, TiN, ZrB2, ZrC, ZrN, VB2, VC, VN, NbB2, NbC, NbN, TaB2, TaC, CrB2, Cr3C2, CrN, Mo2C, Mo2B5, W2B5, WC and LaB6. Preferably, the first intermediate layer 6 and / or the second intermediate layer 7 are respectively selected from at least one of nickel, nickel-based alloy, copper-based alloy and titanium nitride, preferably titanium nitride.

[0113] In some embodiments, the thickness of the first intermediate layer 6 and / or the second intermediate layer 7 is 1-1000nm, preferably 5-500nm. The intermediate layer plays the role of conducting electricity, enhancing the bonding strength between CuAl, and preventing the mutual diffusion of the two. Generally, it will be thinner. As long as it plays the above role, it is as thin as possible to save raw materials and costs. Generally, the film will be 1-1000nm, preferably 5nm-100nm or 5nm-500nm.

[0114] In some embodiments, the first isolation layer 4 and the second isolation layer 5 are made of the same material, the first conductive layer 2 and the second conductive layer 3 are made of the same material; the first intermediate layer 6 and the second intermediate layer 7 are made of the same material; the first isolation layer 4, the first conductive layer 2, and the first intermediate layer 6 are made of different materials. In some embodiments, the material of the first conductive layer 2 and / or the second conductive layer 3 includes Al, and the material of the first isolation layer 4 and / or the second isolation layer 5 includes Cu.

[0115] In some embodiments, the first coating layer 30 further includes a first anti-oxidation layer 10, which is disposed on the side of the first isolation layer 4 away from the substrate 1; and the second coating layer 20 further includes a second anti-oxidation layer 11, which is disposed on the side of the second isolation layer 5 away from the substrate 1. For example, the isolation layer, such as Cu, will undergo oxidation discoloration during the coating and baking process of the electrode, and a reasonably designed anti-oxidation protective layer on Cu can prevent its oxidation discoloration.

[0116] In some embodiments, the first anti-oxidation layer 10, the first isolation layer 4 and the first intermediate layer 6 overlap in the orthographic projection of the substrate 1; and the second anti-oxidation layer 9, the second isolation layer 5 and the second intermediate layer 7 overlap in the orthographic projection of the substrate 1. Thus, the anti-oxidation layer can completely cover the isolation layer and the intermediate layer, thereby improving the anti-oxidation performance of the negative electrode composite current collector.

[0117] In some embodiments, the first anti-oxidation layer 10 and / or the second anti-oxidation layer 11 can be a PVD metal anti-oxidation layer, and the material of the metal anti-oxidation layer is selected from at least one of the following: a single metal or an alloy or a metal compound; wherein the single metal is selected from at least one of Ti, V, Cr, Mn, Fe, Co, and Ni; the alloy is at least one of a nickel-based alloy and a copper-based alloy; the metal compound is at least one of TiB2, TiC, TiN, ZrB2, ZrC, ZrN, VB2, VC, VN, NbB2, NbC, NbN, TaB2, TaC, CrB2, Cr3C2, CrN, Mo2C, Mo2B5, W2B5, WC, and LaB6.

[0118] The PVD anti-oxidation layer is a metal or alloy layer of the above-mentioned material vacuum deposited on the surface of the first isolation layer and / or the second isolation layer. The deposition method can be at least one of vacuum deposition such as vacuum sputtering, vacuum ion plating, vacuum evaporation, etc. The deposition thickness is 1nm-100nm. The function of the anti-oxidation layer is to inhibit oxidative discoloration in a nutrient-rich high-temperature environment. If it is obtained in the form of PVD, it needs to be deposited in an oxygen-rich high-temperature environment. The minimum thickness that does not discolor is generally set to 1nm-100nm, preferably 3nm-50nm. The anti-oxidation layer must meet the requirements of a vacuum oven of 100-150°C for 5-30min. During this process, the current collector does not undergo oxidative discoloration, and compared with the negative electrode current collector without an anti-oxidation layer, the anti-oxidation layer does not additionally reduce the conductivity of the negative electrode current collector.

[0119] In some embodiments, the first anti-oxidation layer 10 and / or the second anti-oxidation layer 11 may be a passivation layer, and the passivation layer is selected from at least one of the following passivation solutions: a chromium-containing passivation solution, a chromium-free passivation solution, or an organic passivation solution.

[0120] The method for forming a passivation layer includes spraying and / or soaking the above passivation liquid, and then rolling and drying the passivation layer. The spraying or soaking time is 1-60s, and the drying temperature is 50-120°C, until there is no solvent residue on the surface. There is no thickness requirement for the anti-oxidation layer of the passivation liquid type. The anti-oxidation layer of the passivation liquid type needs to be dried to obtain a uniform and dense anti-oxidation layer. Due to the difference in the type of reagents, the reaction film formation time is slightly different. For example, the time period of 1-60s can cover the reaction film formation time of the passivation liquid. The drying is determined according to the curing temperature of the reaction film of different passivation liquids.

[0121] The organic passivator can be modified benzotriazole, and its preparation method is as follows: prepare a composite solution of 0.5mmol / L BTA and 0.5mmol / L MBT, stir magnetically until completely dissolved, apply it on the copper current collector base film with a coater, dry it in a drying oven at 50-80°C for 30 minutes, and take it out.

[0122] Example:

[0123] Example 1: A 1 um thick Al layer was vacuum deposited on the upper and lower surfaces of a 6 um thick PET substrate, and a 300 nm thick Cu layer was vacuum evaporated on the upper and lower surfaces of the Al layer. A battery was prepared to characterize the initial efficiency and cycle performance of the battery, and to compare the corrosion of the battery pole after disassembly.

[0124] Example 2: An AlOx layer with a thickness of 10 nm was in-situ reacted on the upper and lower surfaces of a 6-um thick PET substrate, and an Al layer with a thickness of 1 um was continuously formed, and a Cu layer with a thickness of 300 nm was vacuum evaporated on the upper and lower surfaces of the Al layer. A battery was prepared, and the first efficiency and cycle performance of the battery were characterized, and the corrosion of the battery pole piece after disassembly was compared.

[0125] Example 3: An AlOx layer with a thickness of 10 nm was in-situ reacted on the upper and lower surfaces of a PET substrate with a thickness of 6 μm, and an Al layer with a thickness of 1 μm was continuously formed. A Ni layer with a thickness of 10 nm was sputtered on the upper and lower surfaces of the Al layer, and a Cu layer with a thickness of 300 nm was vacuum evaporated on the upper and lower surfaces of the Ni layer. A battery was prepared, and the initial efficiency and cycle performance of the battery were characterized, and the corrosion of the battery pole piece after disassembly was compared.

[0126] Example 4: An AlOx layer with a thickness of 10 nm was in-situ reacted on the upper and lower surfaces of a PET substrate with a thickness of 6 um, and an Al layer with a thickness of 1 um was continuously formed. A Ni layer with a thickness of 10 nm was sputtered on the upper and lower surfaces of the Al layer, a Cu layer with a thickness of 300 nm was vacuum evaporated on the upper and lower surfaces of the Ni layer, and a CuZn alloy with a thickness of 10 nm was magnetron sputtered on the upper and lower surfaces of the Cu layer. A battery was prepared, and the first effect and cycle performance of the battery were characterized, and the corrosion of the battery pole piece after disassembly was compared.

[0127] Example 5: An AlOx layer with a thickness of 10 nm was formed by in-situ reaction on the upper and lower surfaces of a PET substrate with a thickness of 6 μm, and an Al layer with a thickness of 1 μm was formed. A Ni layer with a thickness of 10 nm was sputtered on the upper and lower surfaces of the Al layer, and a Cu layer with a thickness of 300 nm was vacuum evaporated on the upper and lower surfaces of the Ni layer, and a modified BTA solvent was applied on the upper and lower surfaces of the Cu layer. A battery was prepared, and the first effect and cycle performance of the battery were characterized, and the corrosion of the battery pole piece after disassembly was compared.

[0128] In the comparative example, 1um metal Al was directly evaporated on the upper and lower surfaces of a 6um thick PET substrate, and the composite current collector after film formation was used as the negative electrode current collector to prepare a battery. The initial efficiency and cycle performance of the battery were characterized, and the corrosion of the battery pole pieces after disassembly was compared.

[0129] Table 1 Comparison of composite current collector core performance

[0130]

[0131]

[0132] It can be seen from the performance comparison results of the composite current collectors in Table 1 that the square resistance values ​​of Examples 1 to 5 of the present application are relatively low, all lower than 27 mΩ / sq, while the square resistance value of the comparative example is higher than 32 mΩ / sq, indicating that the composite current collectors formed in the embodiments of the present application have good conductivity.

[0133] In Examples 2 to 5 of the present application, a bonding layer is added between the Al layer and the substrate, and the bonding force is increased from 4.36 N / 15 mm to more than 8 N / 15 mm, which greatly increases the bonding force of the composite current collector.

[0134] The first coulombic efficiency of Examples 1 to 5 of the present application is close to that of the comparative example, indicating that the composite current collector battery cells formed in the embodiments of the present application have good discharge performance.

[0135] Comparison of Examples 1 to 5 of the present application with the comparative example shows that the first effects of Examples 1 to 5 and the comparative example are substantially the same, while the internal resistance is significantly reduced. In addition, the number of cycles of Examples 1 to 5 is relatively high, indicating that the composite current collector is well applied as a negative electrode current collector.

[0136] It can be seen from the results in Table 1 that Examples 1 to 5 of the present invention can be used as negative electrode current collectors with good battery performance, among which the conductivity and bonding force of the material in Example 5 are better.

[0137] The present disclosure further provides a composite electrode sheet, which includes the negative electrode composite current collector 100 as described in the above embodiment.

[0138] The present disclosure also provides a lithium battery, comprising the composite pole piece as described in the above embodiment.

[0139] The present disclosure also provides a method for manufacturing a negative electrode composite current collector 100, such as Figure 4 As shown, the manufacturing method comprises the following steps:

[0140] Step S102: providing a substrate;

[0141] Step S104: arranging a plurality of first linear conductive structures extending along the surface of the substrate substantially in parallel at a preset interval;

[0142] Step S106: providing a first cladding layer to continuously wrap around a side of the plurality of first linear conductive structures away from the substrate and a side surface of each of the first linear conductive structures, so that an orthographic projection of the first cladding layer on the substrate overlaps with the substrate;

[0143] Step S108: arranging a plurality of second linear conductive structures extending along the surface of the substrate substantially in parallel at a preset interval;

[0144] Step S110: providing a second coating layer to continuously wrap around a side of the plurality of second linear conductive structures away from the substrate and a side surface of each of the second linear conductive structures, so that an orthographic projection of the second coating layer on the substrate overlaps with the substrate;

[0145] Wherein, the plurality of first linear conductive structures and the plurality of second linear conductive structures are symmetrically arranged relative to the substrate.

[0146] In some embodiments, the method further includes: setting a first bonding layer at least between the multiple first linear conductive structures and the substrate to stably bond the multiple first linear conductive structures to the substrate; and setting a second bonding layer at least between the multiple second linear conductive structures and the substrate to stably bond the multiple second linear conductive structures to the substrate.

[0147] In some embodiments, Figure 5 As shown, step S106 includes the following sub-steps:

[0148] Step S106-1: disposing a first intermediate layer on a side of the first isolation layer close to the first linear conductive structure;

[0149] Step S106 - 2 : disposing a first isolation layer on a side of the first intermediate layer away from the substrate, wherein the first intermediate layer is configured to prevent diffusion between the first isolation layer and the first linear conductive structure.

[0150] In some embodiments, Figure 6As shown, step S110 includes the following sub-steps:

[0151] Step S110 - 1 : disposing a second intermediate layer on a side of the second isolation layer close to the second linear conductive structure;

[0152] Step S110 - 2 : disposing a second isolation layer on a side of the second intermediate layer away from the substrate, wherein the second intermediate layer is configured to prevent diffusion between the second isolation layer and the second linear conductive structure.

[0153] In some embodiments, the method further includes: disposing a first anti-oxidation layer on a side of the first isolation layer away from the substrate; and disposing a second anti-oxidation layer on a side of the second isolation layer away from the substrate.

[0154] In some embodiments, the method of setting a first anti-oxidation layer on the side of the first isolation layer away from the substrate and / or setting a second anti-oxidation layer on the side of the second isolation layer away from the substrate includes at least one of the following: scraping, roller coating, spraying, chemical vapor deposition, plasma vapor deposition, atomic layer deposition, pulsed laser deposition, vacuum evaporation, ion plating, radio frequency sputtering, magnetron sputtering or reactive sputtering.

[0155] In some embodiments, the method of setting a first anti-oxidation layer on the side of the first isolation layer away from the substrate and / or setting a second anti-oxidation layer on the side of the second isolation layer away from the substrate includes: forming an oxide layer of the first isolation layer on the side of the first isolation layer away from the substrate by spraying or immersing a chromium passivation solution, a chromium-free passivation solution, or an organic passivation solution; and forming an oxide layer of the second isolation layer on the side of the second isolation layer away from the substrate by spraying or immersing a chromium passivation solution, a chromium-free passivation solution, or an organic passivation solution.

[0156] The present disclosure also provides a method for manufacturing a composite electrode sheet, including the method for manufacturing the negative electrode composite current collector 100 as described in any one of the above items.

[0157] The present disclosure also provides a method for manufacturing a lithium battery, including the method for manufacturing the composite pole piece as described above.

[0158] The thickness of the negative electrode composite electrode sheet formed by the negative electrode composite current collector disclosed in the present invention can be made very thin compared with the negative electrode sheet of a conventional lithium battery, and can be used to improve the effective energy volume ratio of the lithium battery; in addition, the negative electrode current collector provided in the present invention can replace the traditional copper as the negative electrode current collector, saving copper resources and costs and improving safety; the isolation layer in the present invention is a continuous and dense thin film structure, which can prevent the alloying of the negative electrode Li-Al material and can improve the conductivity of the composite current collector; the PVD method is used to design a bonding layer structure between the polymer layer and the conductive layer to enhance the bonding force between the polymer layer and the conductive layer; the negative electrode composite current collector disclosed in the present invention can prevent Li-Al end corrosion during the cutting application process.

[0159] Finally, it should be noted that: the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0160] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A negative electrode composite current collector for a lithium battery, characterized in that: include: Substrate; the substrate is selected from at least one of acrylonitrile-butadiene-styrene copolymer, polyterephthalate, polybutylene terephthalate, poly(p-phenylene terephthalamide), polyimide, polyamide, polyethylene, polystyrene, polyvinylidene fluoride, polyvinyl chloride, polytetrafluoroethylene, polypropylene, polypropylene, polycarbonate, polyoxymethylene, epoxy resin and phenolic resin; A plurality of first linear conductive structures, wherein the plurality of first linear conductive structures extend substantially in parallel along the surface of the substrate at a preset interval; A first cladding layer is continuously wrapped around a side of the plurality of first linear conductive structures away from the substrate, and is continuously wrapped around a side surface of each of the first linear conductive structures, so that an orthographic projection of the first cladding layer on the substrate overlaps with the substrate; A plurality of second linear conductive structures, wherein the plurality of second linear conductive structures extend substantially in parallel along the surface of the substrate at the preset interval; A second cladding layer is continuously wrapped around a side of the plurality of second linear conductive structures away from the substrate, and is continuously wrapped around a side surface of each of the second linear conductive structures, so that an orthographic projection of the second cladding layer on the substrate overlaps with the substrate; The plurality of first linear conductive structures and the plurality of second linear conductive structures are symmetrically arranged relative to the substrate; and the first coating layer comprises: A first isolation layer is disposed on a side of the first coating layer away from the substrate; A first intermediate layer, disposed on a side of the first cladding layer close to the substrate, configured to prevent diffusion between the first isolation layer and the first linear conductive structure; A first anti-oxidation layer is disposed on a side of the first isolation layer away from the substrate and is configured to prevent oxidation of the first isolation layer; and The second coating layer comprises: A second isolation layer is disposed on a side of the second coating layer away from the substrate; a second intermediate layer, disposed on a side of the second cladding layer close to the substrate, and configured to prevent diffusion between the second isolation layer and the second linear conductive structure; a second anti-oxidation layer, disposed on a side of the second isolation layer away from the substrate, and configured to prevent oxidation of the second isolation layer; The materials of the first isolation layer and the second isolation layer are Cu.

2. The negative electrode composite current collector according to claim 1, characterized in that: The negative electrode composite current collector further comprises: A first bonding layer is disposed between the plurality of first linear conductive structures and the substrate by physical vapor deposition, and is configured to stably bond the plurality of first linear conductive structures and the substrate; The second bonding layer is disposed between the plurality of second linear conductive structures and the substrate by physical vapor deposition, and is configured to stably bond the plurality of second linear conductive structures and the substrate.

3. The negative electrode composite current collector according to claim 2, characterized in that: The physical vapor deposition is selected from at least one of the following: vacuum sputtering, vacuum ion plating or vacuum evaporation.

4. The negative electrode composite current collector according to claim 1, characterized in that: The orthographic projections of the first isolation layer, the first intermediate layer, and the first anti-oxidation layer on the substrate overlap; and The orthographic projections of the second isolation layer, the second intermediate layer, and the second anti-oxidation layer on the substrate overlap.

5. The negative electrode composite current collector according to claim 1, characterized in that: The tensile strength of the material of the substrate is ≥150MPa; or The thermal shrinkage rate of the substrate material after being treated at 150°C for 30 minutes is ≤3%; or, The thickness of the substrate is 1-10 μm.

6. The negative electrode composite current collector according to claim 1, characterized in that: The thickness of the first linear conductive structure and / or the second linear conductive structure is 0.1-2 μm respectively; or, The bonding force between the first linear conductive structure and / or the second linear conductive structure and the substrate is ≥ 0.5 N / 15 mm; The resistivity of the first linear conductive structure and / or the second linear conductive structure is ≤8 μΩ•cm.

7. The negative electrode composite current collector according to claim 1, characterized in that: The material of the first linear conductive structure and / or the second linear conductive structure is Al.

8. The negative electrode composite current collector according to claim 1, characterized in that: The thickness of the first isolation layer and the second isolation layer are 1-1500 nm respectively; or, A first conductive layer is formed by a plurality of first linear conductive structures, a second conductive layer is formed by a plurality of second linear conductive structures, and the bonding force between the first isolation layer and the first conductive layer and / or the bonding force between the second isolation layer and the second conductive layer is ≥0.5N / 15mm.

9. The negative electrode composite current collector according to claim 1, characterized in that: The first linear conductive structure and the second linear conductive structure are made of the same material; the first isolation layer, the first linear conductive structure and the first intermediate layer are made of different materials.

10. The negative electrode composite current collector according to claim 1, characterized in that: The first anti-oxidation layer and / or the second anti-oxidation layer is selected from at least one of the following: a chromium-containing passivation solution, a chromium-free passivation solution or an organic passivation solution.

11. A composite pole piece, characterized in that: The composite electrode sheet comprises the negative electrode composite current collector according to any one of claims 1 to 10.

12. A lithium battery, characterized in that: Including the composite pole piece as claimed in claim 11.

13. A method for manufacturing a negative electrode composite current collector according to any one of claims 1 to 10, characterized in that: The manufacturing method comprises: providing a substrate; Arranging a plurality of first linear conductive structures extending along the surface of the substrate substantially in parallel at a preset interval; The first coating layer is provided by a magnetron sputtering process so that it continuously wraps around the side of the plurality of first linear conductive structures away from the substrate, and continuously wraps around the side of each of the first linear conductive structures, so that the orthographic projection of the first coating layer on the substrate overlaps with the substrate; the thickness of the first coating layer is 50-200 nm; Arrange a plurality of second linear conductive structures substantially parallel to and extending along the surface of the substrate at a preset interval; Arranging a second coating layer by a magnetron sputtering process so that the second coating layer continuously wraps around a side of the plurality of second linear conductive structures away from the substrate, and continuously wraps around a side surface of each of the second linear conductive structures, so that an orthographic projection of the second coating layer on the substrate overlaps with the substrate; Wherein, the plurality of first linear conductive structures and the plurality of second linear conductive structures are symmetrically arranged relative to the substrate.

14. The method according to claim 13, characterized in that The method further comprises: At least a first bonding layer is provided between the plurality of first linear conductive structures and the substrate, so that the plurality of first linear conductive structures and the substrate are stably bonded; A second bonding layer is disposed at least between the plurality of second linear conductive structures and the substrate, so as to stably bond the plurality of second linear conductive structures to the substrate.

15. A method for manufacturing a composite pole piece, characterized in that: A method for manufacturing a negative electrode composite current collector comprising the steps of any one of claims 13 to 14.

16. A method for manufacturing a lithium battery, characterized in that: Including the method for manufacturing the composite pole piece as described in claim 15.

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