Composite current collector and its manufacturing method, composite electrode plate and its manufacturing method, and lithium battery

Abstract

The present disclosure provides a composite current collector and a manufacturing method thereof, a composite electrode plate and a manufacturing method thereof, and a lithium battery, wherein the composite current collector includes a substrate layer, a first metallic material layer disposed on one side of the substrate layer, the first metallic material layer having a side remote from the substrate layer configured to be coated with a first active material, and a second metallic material layer disposed on the side of the substrate layer remote from the first metallic material layer, the second metallic material layer having a side remote from the substrate layer configured to be coated with a second active material, the second active material and the first active material having opposite polarities.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is based on and claims priority from a Chinese application having CN application number 202211667775.5 and filing date December 23, 2022, and a Chinese application having CN application number 202211665068.2 and filing date December 23, 2022, the disclosures of which are hereby incorporated in their entirety into this application.

[0002] The present invention relates to the technical field of lithium batteries, and more particularly to a composite current collector and its manufacturing method, a composite electrode plate and its manufacturing method, and a lithium battery. [Background technology]

[0003] Lithium-ion batteries, commonly referred to as lithium batteries, are highly efficient energy storage devices that are widely used in everyday life. A conventional lithium-ion battery core includes a pair of positive and negative plates, which are stacked in layers or wound together to create battery cores with different capacities. In conventional lithium-ion batteries, the volume of the active material that effectively stores energy is relatively small, while the volumes of the positive and negative current collectors in the positive and negative plates are relatively large, resulting in a low effective energy-to-volume ratio.

[0004] A bipolar current collector is a composite material in which a positive metal layer is deposited on one surface of a polymer film and a negative metal layer is deposited on the other surface. Currently, the positive metal layer in a bipolar current collector is generally aluminum, and the negative metal layer is generally copper. However, such bipolar current collectors generally have defects such as low volumetric energy density, poor ductility, and high areal density. Summary of the Invention [Problem to be solved by the invention]

[0005] A first objective of the present disclosure is to provide a composite current collector and a manufacturing method thereof, a composite electrode plate and a manufacturing method thereof, and a lithium battery, which can solve the technical problem of the low effective energy-to-volume ratio of current lithium batteries. [Means for solving the problem]

[0006] An embodiment of the present disclosure provides a composite current collector for use in a lithium battery, the composite current collector including a substrate layer, a first metallic material layer, and a second metallic material layer, the first metallic material being disposed on one side of the substrate layer, and a first active material being applied to a side of the first metallic material layer remote from the substrate layer, the second metallic material layer being disposed on a side of the substrate layer remote from the first metallic material layer, and a second active material being applied to a side of the second metallic material layer remote from the substrate layer, the second active material and the first active material having opposite polarities.

[0007] In some embodiments, the first metallic material layer includes a first sub-metallic material layer and a second sub-metallic material layer, the first sub-metallic material layer being disposed on one side of the substrate layer, the second sub-metallic material layer being disposed on a side of the first sub-metallic material layer away from the substrate layer, and the side of the second sub-metallic material layer away from the first sub-metallic material layer being configured to receive the first active material.

[0008] In some embodiments, an orthogonal projection of the first sub-metallic material layer on the substrate layer overlaps with an orthogonal projection of the second sub-metallic material layer on the substrate layer.

[0009] In some embodiments, the material of the substrate layer is selected from one or more of polyethylene terephthalate, o-phenylphenol, cast polypropylene, polyimide polyvinyl chloride, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-co-chlorotrifluoroethylene, silicone, vinylon, polypropylene, polyethylene, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, and polysulfone, and derivatives thereof.

[0010] In some embodiments, the thickness of the substrate layer is 4 to 8 μm.

[0011] In some embodiments, the material of any one of the first metallic material layer and the second metallic material layer is selected from one or more of Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, and Zn.

[0012] In some embodiments, the material of the first sub-metallic material layer includes Al and the material of the second sub-metallic material layer includes Cu.

[0013] In some embodiments, the thickness of the first sub-metallic material layer is 0.2 to 2 μm, and the thickness of the second sub-metallic material layer is 0.1 to 2 μm.

[0014] In some embodiments, the material of the second metallic material layer includes Al, and the thickness of the second metallic material layer is 0.3 to 4 μm.

[0015] In some embodiments, at least one of the first sub-metallic material layer and the second sub-metallic material layer is formed using one or more selected from evaporation, deposition, and sputtering.

[0016] In some embodiments, the second metallic material layer is formed using one or more selected from evaporation, deposition, and sputtering.

[0017] In some embodiments, the first active material comprises a negative electrode active material and the second active material comprises a positive electrode active material.

[0018] Some embodiments of the present disclosure provide a composite electrode plate, the composite electrode plate including the composite current collector of the above-described embodiments, a first active material layer, and a second active material layer, wherein the first active material layer is disposed on a side of the metallic material layer away from the substrate layer, and the second active material layer is disposed on a side of the second metallic material layer away from the substrate layer.

[0019] Some embodiments of the present disclosure provide lithium batteries that include the composite plates described in the previous embodiments.

[0020] Some embodiments of the present disclosure provide a method for manufacturing a composite current collector, the method including: providing a substrate layer; forming a first metallic material layer on the substrate layer, wherein a side of the first metallic material layer away from the substrate layer is configured to be coated with a first active material; and forming a second metallic material layer on a side of the substrate layer away from the first metallic material layer, wherein a side of the second metallic material layer away from the substrate layer is configured to be coated with a second active material, the second active material and the first active material having opposite polarities.

[0021] In some embodiments, forming the first metallic material layer on the substrate layer includes forming a first sub-metallic material layer on one side of the substrate layer and forming a second sub-metallic material layer on a side of the first sub-metallic material layer away from the substrate layer, the side of the second sub-metallic material layer away from the first sub-metallic material layer being configured to receive the first active material.

[0022] In some embodiments, an orthogonal projection of the first sub-metallic material layer on the substrate layer overlaps with an orthogonal projection of the second sub-metallic material layer on the substrate layer.

[0023] In some embodiments, forming the first sub-metallic material layer on one side of the substrate layer includes forming an Al-based first sub-metallic material layer on one side of the substrate layer using one or more selected from evaporation, deposition, and sputtering.

[0024] In some embodiments, forming the second sub-metallic material layer on the side of the first sub-metallic material layer away from the substrate layer includes: The method includes forming a second sub-metallic material layer made of Cu on the side of the first sub-metallic material layer away from the substrate layer by using one or more of evaporation, deposition, and sputtering.

[0025] In some embodiments, forming the second metallic material layer on the side of the substrate layer away from the first metallic material layer includes forming the Al-based second metallic material layer on the side of the substrate layer away from the first metallic material layer using one or more selected from evaporation, deposition, and sputtering.

[0026] Some embodiments of the present disclosure provide a method for manufacturing a composite electrode plate, the method including the method for manufacturing a composite current collector of any of the previous embodiments, and configuring the method to apply a first active material to a side of the first metallic material layer remote from the substrate layer, and to apply a second active material to a side of the second metallic material layer remote from the substrate layer.

[0027] Compared with the related art, the embodiments of the present disclosure have the following technical advantages: a positive electrode active material and a negative electrode active material can be applied to both sides of the composite current collector described in the present disclosure, respectively, thereby forming a composite electrode plate, and the thickness of the composite current collector of the composite electrode plate can be made much thinner than the positive electrode current collector of the positive electrode plate and the negative electrode current collector of the negative electrode plate of conventional lithium batteries, which can be used to improve the available energy-to-volume ratio of lithium batteries.

[0028] A second object of the present invention is to provide a bipolar current collector, a manufacturing method thereof, a bipolar electrode, and a lithium battery, in order to solve the problems of conventional bipolar current collectors, such as low volumetric energy density, poor ductility, and high areal density.

[0029] To achieve the second object, a first aspect of the present invention provides a bipolar current collector, the current collector comprising a positive electrode metal layer, a negative electrode metal layer, and a substrate disposed between the positive electrode metal layer and the negative electrode metal layer, wherein the material of the positive electrode metal layer is selected from one or more of Ni, Ti, Ag, Au, Pt, Co, Cr, W, Mo, Al, Mg, Ba, Ge, Sb, In, and Zn, and the material of the negative electrode metal layer is selected from one or more of Ni, Ti, Cu, Ag, Au, Pt, Co, Cr, W, Mo, Mg, Ba, Si, Ge, Sb, In, and Zn. The bipolar current collector is a composite current collector.

[0030] A second aspect of the present invention provides a method for manufacturing the bipolar current collector of the first aspect of the present invention, the method comprising depositing a positive electrode metal layer and a negative electrode metal layer on two surfaces of a substrate, respectively, wherein the deposition method is selected from one or more of evaporation, sputtering, chemical vapor deposition, and electroless plating.

[0031] A third aspect of the present invention provides a bipolar electrode, the bipolar electrode comprising an active positive electrode material, an active negative electrode material, and the bipolar current collector of the first aspect of the present invention, wherein the active positive electrode material is disposed on a positive metal layer of the bipolar current collector, and the active negative electrode material is disposed on a negative metal layer of the bipolar current collector.

[0032] A fourth aspect of the present invention provides a lithium battery comprising a bipolar electrode according to the third aspect of the present invention.

[0033] The bipolar current collector according to the present invention has high electrical conductivity, good ductility, and low areal density, and can significantly improve the effective volumetric energy density of lithium batteries. The method for manufacturing the bipolar current collector according to the present invention has a simple manufacturing process, high manufacturing efficiency, low processing difficulty, and is suitable for widespread industrialization. [Brief explanation of the drawings]

[0034] The drawings herein are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, serve to explain the principles of the present disclosure. Obviously, the drawings described below are merely some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without creative work. [Figure 1] FIG. 1 is a structural schematic diagram of a composite current collector according to some embodiments of the present disclosure. [Figure 2] FIG. 2 is a structural schematic diagram of a composite electrode plate according to some embodiments of the present disclosure. [Figure 3] 1 illustrates a method for manufacturing a composite current collector according to some embodiments of the present disclosure. [Figure 4] 4 is a specific flowchart of step S20 in FIG. 3. [Figure 5] 1 is a flowchart of a method for manufacturing a composite electrode plate according to some embodiments of the present disclosure. [Figure 6] FIG. 2 is a structural schematic diagram of a bipolar current collector in one preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] In order to make the objectives, technical solutions and advantages of the present disclosure clearer, the present disclosure will be described in more detail below in conjunction with the drawings, and it is obvious that the described embodiments are only some of the embodiments of the present disclosure, and not all of the embodiments, and all other embodiments obtained by those skilled in the art based on the embodiments in the present disclosure without any creative effort are all within the scope of protection of the present disclosure.

[0036] The terms used in the embodiments of the present disclosure are merely for the purpose of describing particular embodiments and are not intended to limit the present disclosure. As used in the embodiments of the present disclosure and the appended claims, the singular forms "a," "the," and "the" are intended to include the plural forms as well, and "plurality" generally includes at least two, unless the context clearly dictates otherwise.

[0037] It should be understood that the term "and / or" used herein merely describes the relationship between related objects and indicates that three relationships may exist, for example, A and / or B may represent three cases: A exists alone, A and B exist together, and B exists alone. Also, the character " / " in this specification generally indicates that the related objects before and after it are in an "or" relationship.

[0038] It should be understood that although embodiments of the present disclosure may be described using terms such as first, second, third, etc., they should not be limited to these terms. These terms are used for distinction purposes only. For example, a first may be referred to as a second, and similarly, a second may be referred to as a first, without departing from the scope of embodiments of the present disclosure.

[0039] It should be further explained that the terms "comprise," "including," or any other variation thereof, are intended to cover a non-exclusive inclusion, whereby an article or device comprising a set of elements not only includes those elements, but also other elements not expressly listed or inherent in such article or device. In the absence of further limitations, an element qualified by the phrase "comprises one of" does not exclude the presence of other identical elements in the article or device comprising said element.

[0040] In the related art, lithium batteries generally include positive and negative electrode plates, which are stacked in layers or wound together to produce battery cores with different capacities. The positive electrode plate generally includes a positive electrode current collector and a positive electrode active material coated on both sides of the positive electrode current collector. The positive electrode current collector is generally made of aluminum foil, with a typical thickness of 10 to 15 microns. The negative electrode plate generally includes a negative electrode current collector and a negative electrode active material coated on both sides of the negative electrode current collector. The negative electrode current collector generally includes copper foil, with a typical thickness of 4.5 to 9 microns. The positive electrode active material is coated on both sides of aluminum foil, which is then fired, roll-pressed, slit, and die-cut to produce the positive electrode plate, and the negative electrode active material is coated on both sides of copper foil, which is then fired, roll-pressed, slit, and die-cut to produce the negative electrode plate. The negative electrode plate / separator / positive electrode plate are then stacked or wound in this order to produce the lithium battery core. In the battery core of a lithium battery, the positive and negative active materials play the role of energy storage, while the positive and negative current collectors only play the role of conductivity and do not play the role of energy storage.The positive and negative current collectors occupy a considerable volume, which reduces the effective energy-to-volume ratio of the lithium battery and is disadvantageous to miniaturization of the lithium battery.

[0041] An embodiment of the present disclosure provides a composite current collector for use in a lithium battery, the composite current collector including: a substrate layer; a first metallic material layer disposed on one side of the substrate layer, the first metallic material layer configured to have a first active material applied to a side of the first metallic material layer remote from the substrate layer; and a second metallic material layer disposed on the side of the substrate layer remote from the first metallic material layer, the second metallic material layer configured to have a second active material applied to a side of the second metallic material layer remote from the substrate layer, the second active material having an opposite polarity to the first active material.

[0042] Positive and negative active materials can be applied to both sides of the composite current collector described in the present disclosure, respectively, to form a composite electrode plate. The thickness of the composite current collector of the composite electrode plate can be much thinner than the positive electrode current collector of the positive electrode plate and the negative electrode current collector of the negative electrode plate, and can be used to improve the available energy-to-volume ratio of lithium batteries.

[0043] Selected embodiments of the present disclosure will now be described in detail in conjunction with the drawings.

[0044] FIG. 1 is a structural schematic diagram of a composite current collector according to some embodiments of the present disclosure. As shown in FIG. 1, embodiments of the present disclosure provide a composite current collector 100 for use in a lithium battery, which includes a substrate layer 30, a first metallic material layer 10, and a second metallic material layer 20.

[0045] Specifically, the substrate layer is, for example, a polymer substrate layer, which has good insulating properties and can be very thin. The first metallic material layer 10 is disposed on one side of the substrate layer 30, for example, the bottom side as shown in FIG. 1 , and the side of the first metallic material layer 10 away from the substrate layer 30 is configured to be coated with a first active material. The second metallic material layer 20 is disposed on the side of the substrate layer 30 away from the first metallic material layer 10, and the side of the second metallic material layer 20 away from the substrate layer 30 is configured to be coated with a second active material, the second active material and the first active material having opposite polarities. The first active material is, for example, one of a positive electrode active material and a negative electrode active material, and the second active material is, for example, the other of a positive electrode active material and a negative electrode active material.

[0046] The composite current collector described in the embodiments of the present disclosure can have a first metal material layer and a second metal material layer formed on both sides of a polymer substrate layer using a film formation process, respectively, and the composite current collector thus formed can have a very thin thickness. A composite electrode plate can be formed by coating a positive electrode active material and a negative electrode active material on both sides of the composite current collector, respectively, and the thickness of the formed composite electrode plate can be very thin, which is advantageous for increasing the volume ratio of the positive electrode active material and the negative electrode active material used for energy storage and improving the usable energy volume ratio of lithium batteries.

[0047] In some embodiments, as shown in Figure 1, the first metallic material layer 10 includes a stacked first sub-metallic material layer 11 and a second sub-metallic material layer 12. The first sub-metallic material layer 11 is disposed on one side of the substrate layer 30, for example, on the lower side as shown in Figure 1. The second sub-metallic material layer 12 is disposed on the side of the first sub-metallic material layer 11 away from the substrate layer 30, and the side of the second sub-metallic material layer 12 away from the first sub-metallic material layer 11 is configured to be coated with the first active material.

[0048] As described above, the first metallic material layer 10 may be formed using multiple metal film layers, for example, two or more layers. In some embodiments, the material of the first sub-metallic material layer 11 is, for example, Al, and the material of the second sub-metallic material layer 12 is, for example, Cu. The Cu-based second sub-metallic material layer 12 is typically used to apply a first active material, for example, a negative electrode active material. Due to the relatively high cost of Cu, forming the Cu-based second sub-metallic material layer 12 directly on the substrate layer 30 to a predetermined film thickness results in a relatively high cost. Therefore, it is possible to form the Al-based first sub-metallic material layer 11, which is relatively low cost, on the substrate layer 30, and then form the Cu-based second sub-metallic material layer 12 with a relatively low thickness on the side of the Al-based first sub-metallic material layer 11 away from the substrate layer 30, thereby reducing manufacturing costs. In some cases, the second sub-metallic material layer 12 for supporting the first active material may be difficult to form a film on some specific substrate layers 30. Therefore, it is possible to first form a first sub-metallic material layer 11, which is easier to form a film on, on the substrate layer 30, and then form a second sub-metallic material layer 12 on the side of the first sub-metallic material layer 11 away from the substrate layer 30, thereby ensuring the stability of the composite current collector structure.

[0049] 1, an orthogonal projection of the first sub-metallic material layer 11 on the substrate layer 30 overlaps with an orthogonal projection of the second sub-metallic material layer 12 on the substrate layer 30. The second sub-metallic material layer 12 almost completely covers the first sub-metallic material layer 11. The side of the second sub-metallic material layer 12 away from the first sub-metallic material layer 11 is used to apply a first active material.

[0050] In some embodiments, the material of the substrate layer 30 may be a polymeric material having insulating properties, and may form a thin, stable film layer. The material of the substrate layer 30 may be selected from one or more of polyethylene terephthalate, o-phenylphenol, cast polypropylene, polyimide polyvinyl chloride, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-co-chlorotrifluoroethylene, silicone, vinylon, polypropylene, polyethylene, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, and polysulfone, and derivatives thereof.

[0051] In some embodiments, the substrate layer 30 can be made of, for example, polyethylene terephthalate (PET) or o-phenylphenol (OPP), which can provide good insulating properties and structural stability, and low manufacturing costs.

[0052] In some embodiments, the thickness of the substrate layer 30 is 4 to 8 μm, for example, 5 to 7 μm. The substrate layer 30 should be as thin as possible while ensuring its insulating properties and structural stability, thereby improving the available energy-to-volume ratio of the lithium-ion battery.

[0053] In some embodiments, the material of either the first metallic material layer or the second metallic material layer is selected from one or more of Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, and Zn. The first metallic material layer and the second metallic material layer are coated with a first active material and a second active material, respectively, and both require good electrical conductivity to allow charges to flow smoothly thereover.

[0054] 1, the material of the first sub-metallic material layer 11 includes Al, and the material of the second sub-metallic material layer 12 includes Cu. A first active material, for example, a negative electrode active material, is applied to the surface of the second sub-metallic material layer 12 away from the first sub-metallic material layer 11.

[0055] Cu is an abundant resource, relatively inexpensive, and its film layer has a certain degree of ductility, which is advantageous for winding composite current collectors in the lithium battery manufacturing process. Cu is relatively stable in air and hardly reacts in dry air. However, its low oxidation potential makes it susceptible to oxidation at high potentials. Therefore, Cu is more suitable for application as a negative electrode active material, but not as a positive electrode active material. In some embodiments, the first metallic material layer 10 may be formed as a single film layer using Cu.

[0056] Al is more abundant and its price is lower than Cu. It also has good conductivity and can be closely stacked with Cu film. In some embodiments of the present disclosure, as shown in FIG. 1, the first metal material layer 10 adopts a two-layer structure to ensure the conductive effect and further reduce the cost.

[0057] In some embodiments, as shown in Figure 1, the thickness of the first sub-metallic material layer 11 is 0.2 to 2 µm, for example 1 µm. The thickness of the second sub-metallic material layer is 0.1 to 2 µm, for example 1 µm. The total thickness of the first metallic material layer 10 should be as thin as possible while ensuring its conductive properties, ductility, and structural stability, thereby improving the available energy-to-volume ratio of the lithium-ion battery.

[0058] In some embodiments, as shown in FIG. 1 , the second metallic material layer includes Al, and the thickness of the second metallic material layer is 0.3 to 4 μm, e.g., 2 μm. As mentioned above, Al is abundant and inexpensive, and its film layer has a certain degree of ductility, making it advantageous for winding the composite current collector in the lithium battery manufacturing process. Al is relatively stable in air, hardly reacts in dry air, and has a high oxidation potential, making it resistant to oxidation even at high potentials. Therefore, Al is suitable for coating the positive electrode active material. The second metallic material layer 20 may be formed as a single film layer using Al. The overall thickness of the second metallic material layer 20 should be as thin as possible while ensuring its conductive properties, ductility, and structural stability, thereby improving the effective energy-to-volume ratio of the lithium-ion battery.

[0059] 1, at least one of the first sub-metallic material layer 11 and the second sub-metallic material layer 12 is formed using one or more of evaporation, deposition, and sputtering, and the second metallic material layer 20 is formed using one or more of evaporation, deposition, and sputtering.

[0060] Specifically, vapor deposition may include vacuum deposition, ion plating, etc., deposition may include chemical vapor deposition, plasma vapor deposition, atomic layer deposition, pulsed laser deposition, etc., and sputtering may include radio frequency sputtering, magnetron sputtering, or reactive sputtering, etc.

[0061] Tests have shown that the sheet resistance of the first metal material layer 10 is 33 mΩ / sq, indicating that the first metal material layer 10 formed from the first sub-metal material layer 11 and the second sub-metal material layer 12 has good conductivity.

[0062] In some embodiments, the first active material comprises a negative electrode active material, and the second active material comprises a positive electrode active material, such as a lithium-containing transition metal oxide or phosphide, e.g., LiCoO2 or LiFePO4, and the negative electrode active material comprises a carbon material, such as artificial graphite, natural graphite, mesocarbon microbeads, petroleum coke, carbon fiber, or pyrolytic resin carbon.

[0063] 2 is a structural schematic diagram of a composite electrode plate according to some embodiments of the present disclosure. As shown in FIG. 2, some embodiments of the present disclosure provide a composite electrode plate 1000 including a composite current collector 100, a first active material layer 41, and a second active material layer 42 in the above-described embodiments.

[0064] The specific structure of the composite current collector 100 has already been described in detail in the above-mentioned embodiment, and therefore will not be described here.

[0065] The first active material layer 41 is disposed on the side of the first metallic material layer 10 away from the substrate layer 30, and is formed by, for example, applying an anode active material slurry to the side of the first metallic material layer 10 away from the substrate layer 30. Specifically, the anode active material slurry is formed on the side of the second sub-metallic material layer 12 away from the first sub-metallic material layer 11 using, for example, a coating process. The coating process may include, for example, spraying, printing, roll coating, spin coating, etc.

[0066] The second active material layer 42 is disposed on the side of the second metal material layer 20 that is remote from the substrate layer 30. It is formed by applying a positive electrode active material slurry to the side of the first metal material layer 20 that is remote from the substrate layer 30, for example.

[0067] In the composite electrode plate according to the present disclosure, the thickness of the composite current collector therein can be made much thinner than the positive electrode current collector of the positive electrode plate and the negative electrode current collector of the negative electrode plate of conventional lithium batteries, and can be used to improve the effective energy-to-volume ratio of the lithium battery.

[0068] The present disclosure further provides a lithium battery including a composite electrode plate according to the above-described embodiments, and the composite electrode plate can be laminated or wound to form a battery core of the lithium battery, and then covered with a protective case to form the lithium battery. The thickness of the composite current collector can be made much thinner than the positive electrode current collector of the positive electrode plate and the negative electrode current collector of the negative electrode plate of conventional lithium batteries, so that the lithium battery according to the present disclosure can have a better effective energy-to-volume ratio.

[0069] Some embodiments of the present disclosure further provide a method for manufacturing a composite current collector, and Figure 3 illustrates a method for manufacturing a composite current collector according to some embodiments of the present disclosure. As shown in Figure 3, the method for manufacturing a composite current collector includes the following steps:

[0070] S10: Provide a substrate layer.

[0071] Specifically, the material of the substrate layer may be a polymeric material having insulating properties, and may form a thin film layer with a stable structure. The material of the substrate layer may be selected from one or more of polyethylene terephthalate, o-phenylphenol, cast polypropylene, polyimide polyvinyl chloride, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-co-chlorotrifluoroethylene, silicone, vinylon, polypropylene, polyethylene, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, and polysulfone, and derivatives thereof. The substrate layer may be purchased or self-produced.

[0072] S20: A first metallic material layer is formed on the substrate layer, and a first active material is applied to the side of the first metallic material layer away from the substrate layer.

[0073] The material of the first metallic material layer may be selected from one or more of Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, and Zn. Specifically, in some embodiments, the first metallic material layer may be formed using a single film layer of Cu. Cu is abundant and relatively inexpensive, and its film layer has a certain ductility, which is advantageous for winding the composite current collector in the lithium battery manufacturing process. Cu is relatively stable in air and hardly reacts in dry air. However, due to its low oxidation potential and susceptibility to oxidation at high potentials, Cu is more suitable for coating negative electrode active materials and not suitable for coating positive electrode active materials.

[0074] S30: A second metal material layer is formed on the side of the substrate layer away from the first metal material layer, and the side of the second metal material layer away from the substrate layer is configured to be coated with a second active material, and the second active material and the first active material have opposite polarities.

[0075] The material of the second metallic material layer may be selected from one or more of Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, and Zn. Specifically, in some embodiments, the first metallic material layer may be formed using Al as a single film layer. Al is abundant and inexpensive, and its film layer has a certain ductility, which is advantageous for winding the composite current collector in the lithium battery manufacturing process. Al is relatively stable in air, hardly reacts in dry air, and has a high oxidation potential, making it resistant to oxidation even at high potentials. Therefore, Al is suitable for coating the positive electrode active material.

[0076] FIG. 4 is a specific flowchart of step S20 in FIG. 3, and in some embodiments, step S20 specifically includes the following steps:

[0077] S21: A first sub-metallic material layer is formed on one side of the base material layer.

[0078] Specifically, in some embodiments, the material of the first sub-metallic material layer includes Al, and the thickness of the first sub-metallic material layer is 0.2 to 2 μm, for example, 1 μm.

[0079] S22: A second sub-metallic material layer is formed on the side of the first sub-metallic material layer away from the substrate layer, and the side of the second sub-metallic material layer away from the first sub-metallic material layer is configured to be coated with the first active material.

[0080] Specifically, in some embodiments, the material of the second sub-metallic material layer includes Cu, and the thickness of the second sub-metallic material layer is 0.1 to 2 μm, for example, 1 μm.

[0081] Because Al resources are more abundant, its price is lower than Cu, and it also has good conductivity and can be tightly laminated with Cu film. Therefore, a double-layer film made of Al and Cu can be used to replace a single film layer made of Cu, further reducing costs.

[0082] The total thickness of the first metallic material layer should be as thin as possible while still ensuring its conductive properties, ductility, and structural stability, thereby improving the available energy-to-volume ratio of the lithium-ion battery.

[0083] In some embodiments, an orthogonal projection of the first sub-metallic material layer on the substrate layer overlaps with an orthogonal projection of the second sub-metallic material layer on the substrate layer, the second sub-metallic material layer substantially completely covers the first sub-metallic material layer, and the side of the second sub-metallic material layer away from the first sub-metallic material layer is used to apply a first active material.

[0084] In some embodiments, in step S21, an Al-based first sub-metallic material layer is formed on one side of the substrate layer using one or more selected from evaporation, deposition, and sputtering.

[0085] In some embodiments, in step S22, a second sub-metallic material layer made of Cu is formed on the side of the first sub-metallic material layer away from the substrate layer using one or more of evaporation, deposition, and sputtering.

[0086] In some embodiments, in step S30, an Al-based second metallic material layer is formed on the substrate layer on a side away from the first metallic material layer using one or more of evaporation, deposition, and sputtering.

[0087] Specifically, vapor deposition may include vacuum deposition, ion plating, etc., deposition may include chemical vapor deposition, plasma vapor deposition, atomic layer deposition, pulsed laser deposition, etc., and sputtering may include radio frequency sputtering, magnetron sputtering, or reactive sputtering, etc.

[0088] Some embodiments of the present disclosure further provide a method for manufacturing a composite electrode plate, and Figure 5 is a flowchart of the method for manufacturing a composite electrode plate according to some embodiments of the present disclosure. The method for manufacturing the composite electrode plate specifically includes the following steps:

[0089] S510: Provide a composite current collector; Specifically, the composite current collector can be manufactured using the manufacturing method of the composite current collector according to the above-described embodiment, and the description thereof will be omitted here.

[0090] S520: Applying a first active material to the side of the first metallic material layer away from the substrate layer; Specifically, a first active material slurry, e.g., a negative electrode active material slurry, is applied to the side of the first metallic material layer away from the substrate layer to form a first active material layer, e.g., a negative electrode active material layer, and the application process can include, for example, spraying, printing, roll coating, spin coating, etc.

[0091] S530: A second active material is applied to the second metallic material layer on a side thereof away from the substrate layer.

[0092] Specifically, a second active material slurry, e.g., a positive electrode active material slurry, is applied to the second metallic material layer on the side away from the substrate layer to form a second active material layer, e.g., a positive electrode active material layer, and the application process can include, for example, spraying, printing, roll coating, spin coating, etc.

[0093] Experimental tests showed that the sheet resistance of the first metal material layer 10 was 33 mΩ / sq, indicating that the first metal material layer 10 formed of the first sub-metal material layer 11 and the second sub-metal material layer 12 has good conductivity.

[0094] The normal tensile strength of the composite current collector 100 is 27 N / 15 mm, which is greater than the 25 N / 15 mm of the conventional current collector, indicating that the composite current collector 100 has a relatively high tensile strength.

[0095] After welding the composite current collector 100 and the tab, the remaining rate of the welding mark on one side of the tab was 100%, which indicates that the welding effect was good.

[0096] The internal resistance (2000 mAh) of the battery core formed using the composite current collector 100 was 15 mΩ to 15.5 mΩ, while the internal resistance (2000 mAh) of the battery core of a conventional current collector was 13 mΩ. This indicates that the composite current collector, despite having a non-conductive substrate, still has a relatively small internal resistance of the battery core, which is only about 15% (less than 30%) higher than the internal resistance of a conventional metal battery core, and still meets good conductivity performance.

[0097] The weight of the battery core (5500 mAh) with the composite current collector is approximately 79 g, while the weight of the battery core (5500 mAh) with the conventional current collector is approximately 98 g. Therefore, the weight of the battery core with the composite current collector is lighter than the weight of the battery core with the conventional current collector.

[0098] Electrical performance test: The ternary system of the battery core with the composite current collector was cycled, and the discharge capacity retention rate after 1700 cycles was 75%, with no significant decrease. This was almost equal to the cycle performance of the ternary system of the battery core with the conventional current collector, and could meet the electrical performance demands.

[0099] A first aspect of the present invention provides a bipolar current collector, the current collector including a positive electrode metal layer, a negative electrode metal layer, and a substrate disposed between the positive electrode metal layer and the negative electrode metal layer, wherein the material of the positive electrode metal layer is selected from one or more of Ni, Ti, Ag, Au, Pt, Co, Cr, W, Mo, Al, Mg, Ba, Ge, Sb, In, and Zn, and the material of the negative electrode metal layer is selected from one or more of Ni, Ti, Cu, Ag, Au, Pt, Co, Cr, W, Mo, Mg, Ba, Si, Ge, Sb, In, and Zn.

[0100] Here, the structure of the bipolar current collector according to the present invention is shown in Figure 6, where 1 is a positive electrode metal layer, 2 is a negative electrode metal layer, and 3 is a substrate. In the present invention, when the positive electrode metal layer and the negative electrode metal layer are made of multiple types of materials, the multiple types of materials may be distributed in one layer, or may be provided in separate layers according to the type of material. In other words, each type of material is provided in one layer, and different materials are provided in a stacked configuration.

[0101] In one preferred embodiment, the substrate is selected from one or more of polyethylene terephthalate (PET), o-phenylphenol film (OPP film), biaxially oriented polypropylene film (BOPP), cast polypropylene, polyimide, polyvinyl chloride composite, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide (PPS), polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, polyvinylidene fluoride-hexafluoropropylene, poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, polyethylene, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, and polysulfone, and derivatives thereof.

[0102] In one preferred embodiment, the thickness of the substrate is 1-8 μm, for example, the thickness of the substrate may be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, and any value between two of these points.

[0103] In one preferred embodiment, the thickness of the positive electrode metal layer is 0.2 to 2 μm. For example, the thickness of the positive electrode metal layer may be 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.2 μm, 1.6 μm, 1.8 μm, 2 μm, or any value between two of these.

[0104] In one preferred embodiment, the thickness of the negative electrode metal layer is 0.1 to 2 μm. For example, the thickness of the negative electrode metal layer may be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.2 μm, 1.6 μm, 1.8 μm, 2 μm, or any value between two of these.

[0105] In one preferred embodiment, the total thickness of the positive electrode metal layer and the negative electrode metal layer is 0.3 to 4 μm. For example, the total thickness of the positive electrode metal layer and the negative electrode metal layer may be 0.3 μm, 0.5 μm, 0.7 μm, 0.8 μm, 1 μm, 1.5 μm, 1.8 μm, 2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.5 μm, 3.8 μm, 4 μm, or any value between two of these.

[0106] In one preferred embodiment, the bipolar current collector has high volumetric energy density, high electrical conductivity, good ductility, and low areal density.

[0107] A second aspect of the present invention provides a method for manufacturing a bipolar current collector according to the first aspect of the present invention, the method comprising depositing a positive electrode metal layer and a negative electrode metal layer on two surfaces of a substrate, respectively, wherein the deposition method is selected from one or more of evaporation, sputtering, chemical vapor deposition, and electroless plating.

[0108] Here, the deposition, sputtering, chemical vapor deposition, and electroless plating in the present invention are known methods in the art, and any deposition, sputtering, chemical vapor deposition, and electroless plating operating methods available in the art can be used in the present invention, and the present invention is not particularly limited. Preferably, the deposition can be vacuum deposition or ion plating, the sputtering can be radio frequency sputtering, magnetron sputtering, or reactive sputtering, and the chemical vapor deposition can be chemical vapor deposition, plasma vapor deposition, atomic layer deposition, or pulsed laser deposition.

[0109] A third aspect of the present invention provides a bipolar electrode, the bipolar electrode comprising a positive electrode active material, a negative electrode active material, and the bipolar current collector according to the first aspect of the present invention, wherein the positive electrode active material is disposed on a positive electrode metal layer of the bipolar current collector, and the negative electrode active material is disposed on a negative electrode metal layer of the bipolar current collector.

[0110] Here, the present invention is not particularly limited to the positive electrode active material and the negative electrode active material, and any positive electrode active material and negative electrode active material available in the art according to specific operating conditions can be used in the present invention.

[0111] In one preferred embodiment, the positive electrode active material is selected from a lithium-containing transition metal oxide and a lithium-containing transition metal phosphate phosphide. Preferably, the lithium-containing transition metal oxide is selected from one of a ternary positive electrode material, a nickel-manganese positive electrode material, and a lithium-rich manganese-based positive electrode material. More preferably, the ternary positive electrode material is a high-nickel ternary positive electrode material. Even more preferably, the positive electrode active material is selected from one or more of a lithium cobalt oxide, a lithium iron phosphate, and a lithium manganese iron phosphate.

[0112] In one preferred embodiment, the negative electrode active material is selected from one or more of artificial graphite, natural graphite, mesocarbon microbeads, hard carbon, petroleum coke, carbon fiber, pyrolytic resin carbon, silicon carbon material, and silicon oxygen material, where the silicon carbon material and silicon oxygen material are active materials known in the art and will not be described further in the present invention.

[0113] In one preferred embodiment, the method for manufacturing the bipolar electrode includes applying a positive electrode active material slurry to a positive electrode metal layer of a bipolar current collector, applying a negative electrode active material slurry to a negative electrode metal layer of a bipolar current collector, and then drying to obtain a bipolar electrode.

[0114] In one preferred embodiment, the positive electrode active material slurry includes a positive electrode active material and a solvent I, the solvent I being selected from one or more of water, a ketone solvent, and an alcohol solvent, and the mass content of the positive electrode active material in the positive electrode active material slurry is 50 to 70%, where the ketone solvent and the alcohol solvent may be common solvents in the art and are not particularly limited.

[0115] In one preferred embodiment, the negative electrode active material slurry includes a negative electrode active material and a solvent II, the solvent II being selected from one or more of water, a ketone solvent, and an alcohol solvent, and the mass content of the negative electrode active material in the negative electrode active material slurry is 40 to 60%.

[0116] In one preferred embodiment, the application method is selected from one or more of spraying, printing, roll coating, and spin coating.

[0117] A fourth aspect of the present invention provides a lithium battery, the lithium battery comprising a bipolar electrode according to the third aspect of the present invention.

[0118] The present disclosure further provides a lithium battery including a bipolar electrode according to the above-described embodiment, and preferably, the bipolar electrodes are arranged in a stacked or wound combination within the battery. By using the bipolar electrode, the battery according to the present invention has a relatively large reduction in volume, particularly thickness, compared to conventional lithium batteries, and has advantageous performance such as a higher effective volumetric energy density.

[0119] The present invention will be described in detail below with reference to examples. [Example]

[0120] Bipolar current collector manufacturing example (1) The surface of a 6 μm-thick PET film was cleaned and activated. After cleaning and activation, the PET film and industrial-grade pure aluminum were placed in a roll-to-roll vacuum deposition system and evaporated to a thickness of 3.5 × 10 -3 The vacuum was drawn to 100 Pa, and a plating speed of 10 cm / min was used to plate a single positive electrode metal layer with a thickness of 1 μm on one side of the PET film. (2) The film on which deposition was completed in step (1) and industrial-grade pure copper were placed in a roll-to-roll vacuum deposition device and deposition was carried out. -3 The other surface of the PET film was plated with a single negative electrode metal layer having a thickness of 1 μm at a plating speed of 10 cm / min to obtain a bipolar current collector. [Example]

[0121] (1) The surface of a 4 μm-thick PET film was cleaned and activated. After cleaning and activation, the PET film and industrial-grade pure aluminum were placed in a roll-to-roll vacuum deposition system and evaporated to a thickness of 3.5 × 10 -3 The vacuum was drawn to 100 Pa, and a plating speed of 10 cm / min was used to plate a single positive electrode metal layer with a thickness of 0.2 μm on one side of the PET film. (2) The film on which deposition was completed in step (1) and industrial-grade pure nickel were placed in a roll-to-roll vacuum deposition device and deposition was carried out.-3 The other surface of the PET film was plated with a single negative electrode metal layer having a thickness of 0.1 μm at a plating speed of 10 cm / min to obtain a bipolar current collector. [Example]

[0122] (1) The surface of an 8 μm thick PET film was cleaned and activated, and then the cleaned and activated PET film and industrial-grade pure titanium were placed in a roll-to-roll vacuum deposition system and evaporated to a thickness of 3.5 × 10 -3 The vacuum was drawn to 100 Pa, and a plating speed of 10 cm / min was used to plate a single positive electrode metal layer with a thickness of 2 μm on one side of the PET film. (2) The film on which deposition was completed in step (1) and industrial-grade pure copper were placed in a roll-to-roll vacuum deposition device and deposition was carried out. -3 The other surface of the PET film was plated with a single negative electrode metal layer having a thickness of 2 μm at a plating speed of 10 cm / min, to obtain a bipolar current collector. [Example]

[0123] (1) The surface of a 4 μm thick PPS film was cleaned and activated, and then the cleaned and activated PPS film and industrial-grade pure zinc were placed in a roll-to-roll vacuum deposition system and evaporated to a thickness of 3.5 × 10 -3 The vacuum was drawn to 100 Pa, and a plating speed of 10 cm / min was used to plate a single positive electrode metal layer with a thickness of 1 μm on one side of the PPS film. (2) The film on which deposition was completed in step (1) and industrial-grade pure magnesium were placed in a roll-to-roll vacuum deposition device and deposition was carried out. -3 The other surface of the PPS film was plated with a single negative electrode metal layer having a thickness of 1 μm at a plating speed of 10 cm / min to obtain a bipolar current collector. [Example]

[0124] (1) The surface of a 6 μm thick BOPP film was cleaned and activated. After cleaning and activation, the BOPP film and industrial-grade pure titanium were placed in a roll-to-roll vacuum deposition system and evaporated to a thickness of 3.5 × 10 -3 The vacuum was drawn to 100 Pa, and a plating speed of 10 cm / min was used to plate a single positive electrode metal layer with a thickness of 1 μm on one side of the BOPP film. (2) The film on which deposition was completed in step (1) and industrial-grade pure nickel were placed in a roll-to-roll vacuum deposition device and deposition was carried out. -3 The other surface of the BOPP film was plated with a single negative electrode metal layer having a thickness of 1 μm at a plating speed of 10 cm / min to obtain a bipolar current collector. [Example]

[0125] The differences from Example 1 are as follows: industrial grade pure aluminum is replaced with Al and Mg, and the weight ratio of Al to Mg is 1:1; industrial grade pure copper is replaced with Cu and Zn, and the weight ratio of Cu to Zn is 1:1. [Example]

[0126] The differences from Example 1 are as follows: industrial grade pure aluminum is replaced with Ni and Cr, and the weight ratio of Ni to Cr is 1:1; industrial grade pure copper is replaced with Cu and Ni, and the weight ratio of Cu to Ni is 1:1. [Example]

[0127] The differences from Example 1 are as follows: industrial grade pure aluminum is replaced with Ni and Al, and the weight ratio of Ni to Al is 1:1; industrial grade pure copper is replaced with Ti and Mo, and the weight ratio of Ti to Mo is 1:1. [Example]

[0128] The differences from Example 1 are as follows: industrial grade pure aluminum is replaced with Ni and Ti, and the weight ratio of Ni to Ti is 1:1; industrial grade pure copper is replaced with Ni and Cr, and the weight ratio of Ni to Cr is 1:1. [Example]

[0129] The differences from Example 1 are as follows: industrial grade pure aluminum is replaced with Mo and Ti, and the weight ratio of Mo to Ti is 1:1; industrial grade pure copper is replaced with Ni and Cr, and the weight ratio of Ni to Cr is 1:1. [Example]

[0130] The differences from Example 1 are as follows: industrial grade pure aluminum is replaced with Al, Zn, and Mg, and the weight ratio of Al, Zn, and Mg is 1:1:1; industrial grade pure copper is replaced with Ni and Cr, and the weight ratio of Ni and Cr is 1:1.

[0131] <Comparative Example 1> The manufacturing steps of the bipolar current collector are the same as those in Example 1, with the following differences: the thickness of the obtained positive electrode metal layer is 3 μm, and the thickness of the negative electrode metal layer is 3 μm.

[0132] <Test Example 1> The bipolar current collectors obtained in the above examples and comparative examples of the present application were tested for ductility, areal density and sheet resistance, and the test results are shown in Table 1.

[0133] Longitudinal ductility: Refer to the national standard GBT1040.3-2006, Determination of Tensile Properties of Plastics, Part 3: Test conditions for thin plastics and sheets.

[0134] Surface density: China national standard GB / T 22638.10-2016 (Aluminum foil test method Part 10: Determination of surface density of coating).

[0135] Sheet Resistance: US ASTM F390 (Standard Test Method for Measuring Film Resistivity of Metallic Films by the Collinear Four-Probe Method).

[0136] [Table 1]

[0137] Bipolar electrode manufacturing example The bipolar current collectors obtained in the above examples and comparative examples were used to manufacture electrodes. Taking Example 1 as an example, the specific method is as follows: The bipolar current collector prepared in Example 1 was placed in a coating machine, and the coating speed was 16 m / min and the tension was 15 N. The positive electrode slurry was first coated on the positive electrode metal layer and dried at 100°C. Then, the negative electrode slurry was coated on the negative electrode metal layer and dried at 100°C. Then, the bipolar current collector was cut to obtain a bipolar electrode. The positive electrode slurry solvent is NMP, containing 96 wt% LiCoO, 2 wt% SP, 0.5 wt% CNTs, and 1.5 wt% PVDF, while the negative electrode slurry solvent is deionized water, containing 94.9 wt% artificial graphite, 1.5 wt% SP, 0.5 wt% CNTs, 1.8 wt% SBR, and 1.3 wt% CMC.

[0138] <Test Example 2> The bipolar electrodes in the examples were assembled into batteries, and then the electrochemical performance of the batteries was tested, and the test results are shown in Table 2.

[0139] Here, the battery ACR test method involves clamping the test jig of a Hioki BT3562A internal resistance tester between the positive and negative electrode tabs of the battery, and measuring the internal resistance.

[0140] K value test method: After the battery is manufactured, measure its voltage V1 with a voltage internal resistance meter at 70-80% SOC, leave it at a constant temperature of 25°C for 24 hours, and then measure its voltage V2 again. K value = (V1-V2) / 24.

[0141] Capacity retention test method: At room temperature, the battery was charged at 1C to the end-of-charge voltage, then switched to constant voltage charging. When the charging current dropped to 0.05C, charging was stopped and the battery was left for 30 minutes. The battery was then discharged at 1C to the end-of-discharge voltage, left for 30 minutes, and cycled. The test was stopped when the capacity retention reached 80%. Discharge capacity retention = (current discharge capacity / initial discharge capacity) x 100%.

[0142] Volumetric energy density test method: At room temperature, the battery was charged at a current of 0.5C to the end-of-charge voltage, then switched to constant voltage charging. When the charging current dropped to 0.05C, charging was stopped and the battery was left for 10 minutes before being discharged at a current of 0.5C until the end-of-charge voltage was reached. The discharge energy was recorded. Volumetric energy density = (discharge capacity / battery core volume) x 100%.

[0143] [Table 2]

[0144] As can be seen from Tables 1 and 2, the thicker the substrate, the lower the sheet resistance, but the corresponding volumetric energy density also becomes lower. The fact that the volumetric energy density is too low is an issue in the entire technical field, and is the subject of efforts and research and development in the entire technical field. It is also the technical problem that the present invention aims to solve, as described in the background art section of the present invention.

[0145] As can be seen from Table 2, the volumetric energy densities of the batteries manufactured using the bipolar current collector according to the present invention are all 530 Wh / L or higher. The volumetric energy density of the battery manufactured using the bipolar current collector of Comparative Example 1 is 526.9 Wh / L, while the volumetric energy density of the battery manufactured using the bipolar current collector of Example 1 is as high as 542.2 Wh / L. That is, the volumetric energy density of Example 1 is 15.3 Wh / L higher than that of Comparative Example 1, an improvement of about 3%. In the field of batteries, a 1% improvement in volumetric energy density is a huge advancement, and the improvement rate in Example 1 is as high as 3%.

[0146] It should be understood that the terms "first," "second," etc. in the specification and claims of this application are intended to distinguish between similar objects and not necessarily to describe a particular order or sequence. It should be understood that the terms so used are interchangeable where appropriate, so that the embodiments of the application described herein may, for example, be implemented in orders other than those described herein.

[0147] The above description is merely a preferred embodiment of the present invention, and is not intended to limit the present invention. Those skilled in the art can make various modifications and changes to the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention. [Explanation of symbols]

[0148] 100 Composite current collector 10 First metal material layer 11 First sub-metallic material layer 20 Second metal material layer 30 Base material layer 1000 composite plate 41 First active material layer 42 Second active material layer 1 Positive electrode metal layer 2 Negative metal layer 3 Base material

Claims

1. A composite current collector for use in a lithium battery, the composite current collector comprising: a substrate layer; a first metallic material layer disposed on one side of the base material layer, the side of the first metallic material layer away from the base material layer being configured to be coated with a first active material; a second metallic material layer disposed on a side of the substrate layer remote from the first metallic material layer, the side of the second metallic material layer remote from the substrate layer being configured to be coated with a second active material, and the second active material and the first active material having opposite polarities.

2. The first metallic material layer comprises: a first sub-metallic material layer disposed on one side of the base layer; 2. The composite current collector according to claim 1, further comprising: a second sub-metallic material layer disposed on a side of the first sub-metallic material layer away from the substrate layer, the side of the second sub-metallic material layer away from the first sub-metallic material layer being configured to be coated with the first active material.

3. The composite current collector according to claim 2 , wherein an orthogonal projection of the first sub-metallic material layer on the substrate layer overlaps with an orthogonal projection of the second sub-metallic material layer on the substrate layer.

4. The material of the substrate layer is selected from one or more of polyethylene terephthalate, o-phenylphenol, cast polypropylene, polyimide, polyvinyl chloride, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-co-chlorotrifluoroethylene, silicone, vinylon, polypropylene, polyethylene, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, polysulfone, and derivatives thereof, or The material is selected from one or more of polyethylene terephthalate, o-phenylphenol, biaxially oriented polypropylene film, cast polypropylene, polyimide, polyvinyl chloride, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-co-chlorotrifluoroethylene, silicone, vinylon, polypropylene, polyethylene, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, and polysulfone, and derivatives thereof; The thickness of the substrate layer is 1 to 8 μm, preferably 4 to 8 μm, Optionally, the material of any one of the first metal material layer and the second metal material layer is selected from one or more of Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, and Zn; Optionally, the material of the first sub-metallic material layer includes Al, and the material of the second sub-metallic material layer includes Cu; Optionally, the thickness of the first sub-metallic material layer is 0.2 to 2 μm, and the thickness of the second sub-metallic material layer is 0.1 to 2 μm; Optionally, the material of the second metal material layer includes Al, and the thickness of the second metal material layer is 0.3 to 4 μm; Optionally, at least one of the first sub-metallic material layer and the second sub-metallic material layer is formed using one or more selected from evaporation, deposition, and sputtering; Optionally, the second metal material layer is formed using one or more selected from evaporation, deposition, and sputtering; 4. The composite current collector according to claim 1, wherein the first active material optionally includes a negative electrode active material, and the second active material optionally includes a positive electrode active material.

5. 5. The composite current collector according to claim 4, wherein the first metallic material layer is a positive electrode metallic layer, the second metallic material layer is a negative electrode metallic layer, the material of the positive electrode metallic layer is selected from one or more of Ni, Ti, Ag, Au, Pt, Co, Cr, W, Mo, Al, Mg, Ba, Ge, Sb, In, and Zn, and the material of the negative electrode metallic layer is selected from one or more of Ni, Ti, Cu, Ag, Au, Pt, Co, Cr, W, Mo, Mg, Ba, Si, Ge, Sb, In, and Zn.

6. the first metallic material layer is a positive electrode metallic layer, and the second metallic material layer is a negative electrode metallic layer; Preferably, the thickness of the positive electrode metal layer is 0.2 to 2 μm, Preferably, the thickness of the negative electrode metal layer is 0.1 to 2 μm, 6. The composite current collector according to claim 1, wherein the total thickness of the positive electrode metal layer and the negative electrode metal layer is preferably 0.3 to 4 μm.

7. A composite electrode plate, the composite electrode plate comprising: The composite current collector according to any one of claims 1 to 6; a first active material layer disposed on a side of the first metallic material layer away from the substrate layer; a second active material layer disposed on the second metallic material layer on a side thereof remote from the substrate layer.

8. 8. The composite electrode plate according to claim 7, wherein the composite electrode plate comprises a positive electrode active material, a negative electrode active material, and the composite current collector, wherein the first metal material layer is a positive electrode metal layer, the second metal material layer is a negative electrode metal layer, the positive electrode active material is disposed on the positive electrode metal layer, and the negative electrode active material is disposed on the negative electrode metal layer.

9. the first active material is a positive electrode active material, and the positive electrode active material is selected from a lithium-containing transition metal oxide, or the positive electrode active material is selected from one or more of a lithium-containing transition metal oxide, a lithium-containing transition metal phosphate, or a phosphide; Preferably, the lithium-containing transition metal oxide is selected from one of a ternary positive electrode material, a nickel-manganese positive electrode material, and a lithium-rich manganese-based positive electrode material; Preferably, the ternary positive electrode material is a high-nickel ternary positive electrode material; More preferably, the positive electrode active material is selected from one or more of lithium cobalt oxide, lithium iron phosphate, and lithium manganese iron phosphate, or the positive electrode active material is selected from LiCoO2 and / or LiFePO4.

10. The second active material is a negative electrode active material, and the negative electrode active material is selected from one or more of artificial graphite, natural graphite, mesocarbon microbeads, petroleum coke, carbon fiber, pyrolytic resin carbon, silicon carbon material, and silicon oxygen material; or 9. The composite electrode plate according to claim 7, wherein the negative electrode active material is selected from one or more of artificial graphite, natural graphite, mesocarbon microbeads, hard carbon, petroleum coke, carbon fiber, pyrolytic resin carbon, silicon carbon material, and silicon oxygen material.

11. 11. The composite electrode plate according to claim 8, wherein a method for manufacturing the composite electrode plate includes applying a positive electrode active material slurry to a positive electrode metal layer of the composite current collector, applying a negative electrode active material slurry to a negative electrode metal layer of the composite current collector, and then drying the resultant composite electrode plate.

12. the positive electrode active material slurry includes a positive electrode active material and a solvent I, the solvent I being selected from one or more of water, a ketone solvent, and an alcohol solvent, and the mass content of the positive electrode active material in the positive electrode active material slurry is 50 to 70%; 12. The composite electrode plate according to claim 8, wherein the negative electrode active material slurry contains a negative electrode active material and a solvent II, the solvent II being selected from one or more of water, a ketone solvent, and an alcohol solvent, and the mass content of the negative electrode active material in the negative electrode active material slurry is 40 to 60%.

13. A lithium battery comprising the composite electrode plate according to any one of claims 7 to 12.

14. A method for manufacturing a composite current collector, the method comprising: providing a substrate layer; forming a first metallic material layer on the substrate layer, the first metallic material layer being configured so that a first active material is applied to a side of the first metallic material layer away from the substrate layer; and forming a second metallic material layer on a side of the base material layer remote from the first metallic material layer, wherein the side of the second metallic material layer remote from the base material layer is configured to be coated with a second active material, and the second active material and the first active material have opposite polarities.

15. forming a first metallic material layer on the substrate layer; forming a first sub-metallic material layer on one side of the substrate layer; forming a second sub-metallic material layer on a side of the first sub-metallic material layer away from the substrate layer, the side of the second sub-metallic material layer away from the first sub-metallic material layer being configured to be coated with the first active material; Optionally, an orthogonal projection of the first sub-metallic material layer on the substrate layer overlaps with an orthogonal projection of the second sub-metallic material layer on the substrate layer; Optionally, forming a first sub-metallic material layer on one side of the substrate layer includes: forming an Al-based first sub-metallic material layer on one side of the base layer by using one or more selected from vapor deposition, deposition, and sputtering; Optionally, forming a second sub-metallic material layer on a side of the first sub-metallic material layer away from the substrate layer includes:

15. The manufacturing method of claim 14, further comprising forming a second sub-metallic material layer made of Cu on a side of the first sub-metallic material layer away from the substrate layer by using one or more of evaporation, deposition, and sputtering.

16. forming a second metallic material layer on the substrate layer away from the first metallic material layer; 16. The manufacturing method according to claim 14 or 15, comprising forming an Al-based second metallic material layer on a side of the substrate layer away from the first metallic material layer by using one or more selected from evaporation, deposition, and sputtering.

17. 15. The manufacturing method of claim 14, wherein the first metallic material layer is a positive electrode metallic layer and the second metallic material layer is a negative electrode metallic layer, and the method includes depositing the positive electrode metallic layer and the negative electrode metallic layer on two surfaces of the substrate, respectively, and wherein the deposition method is selected from one or more of evaporation, sputtering, chemical vapor deposition, and electroless plating.

18. A method for manufacturing a composite electrode plate, A method for producing a composite current collector according to any one of claims 14 to 17; applying a first active material to the first metallic material layer on a side thereof away from the substrate layer; and applying a second active material to the second metallic material layer on a side thereof remote from the substrate layer.

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