Composite current collector, pole piece and battery cell

Abstract

The utility model discloses a composite current collector, a pole piece and a battery cell, the composite current collector comprises a base material layer, a first conducting layer and two second conducting layers, and the first conducting layer is arranged on at least one surface of the base material layer; the two second conducting layers are oppositely arranged on the two surfaces of the base material layer and cover the first conducting layer; the conductivity of the first conductive layer is greater than that of the second conductive layer. Through the structural arrangement, on the basis that the base material layer and the second conductive layer are compounded, the first conductive layer with high conductivity is additionally arranged between the base material layer and the second conductive layer, so that the impedance of the composite current collector can be reduced, and the internal resistance of the battery can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and particularly relates to a composite current collector, a pole piece and an electric core. Background Art

[0002] With the continuous development of mobile energy storage technology, the reliability and safety of its compatible batteries are required to be extremely high. It is expected that the batteries can broaden the usage scenarios and reduce geographical restrictions while ensuring safety. Based on this, the conventional metal foil current collectors used in batteries can no longer meet the above requirements at the same time, and composite current collectors emerge as the times require. They integrate the advantages of metal foils and polymers and can meet the comprehensive performance requirements of batteries.

[0003] A composite current collector is a new type of current collector composed of a polymer material and a metal, and its structure is similar to a "sandwich" structure. The inner layer is a substrate layer made of a polymer (such as polymer materials like PP / PET / PI, etc.), and the outer two layers are metal conductive layers (such as Al or Cu). Generally, the thickness of the substrate layer is in the range of 4um - 6um, and the thickness of the metal conductive layer is generally in the range of 50nm - 1um. However, the composite current collectors with the above structure usually have problems of large impedance and high internal resistance of the battery. Summary of the Utility Model

[0004] The main purpose of the utility model is to propose a composite current collector, aiming to solve the problem of large impedance of the composite current collector.

[0005] To achieve the above purpose, the utility model proposes a composite current collector, which includes:

[0006] A substrate layer;

[0007] A first conductive layer disposed on at least one surface of the substrate layer;

[0008] Two second conductive layers disposed on two opposite surfaces of the substrate layer and covering the first conductive layer; the conductivity of the first conductive layer is greater than that of the second conductive layer.

[0009] In some embodiments, the first conductive layer includes a plurality of sub-conductive layers, and each of the sub-conductive layers is sequentially and spaced apart along the length direction of the substrate layer on the surface of the substrate layer.

[0010] In some embodiments, an active material coating area is provided on the surface of the second conductive layer facing away from the substrate layer, and the active material coating areas are sequentially and spaced apart along the length direction of the substrate layer on the surface of the second conductive layer corresponding to each of the sub-conductive layers.

[0011] In some embodiments, the layer thicknesses in the composite current collector satisfy at least one of the following conditions:

[0012] The thickness of the substrate layer is 2 μm to 3 μm;

[0013] The thickness of the first conductive layer is 0.5 μm to 2 μm;

[0014] The thickness between the surface of the second conductive layer facing away from the first conductive layer and the joint surface with the surface of the first conductive layer facing away from the substrate layer is 1 μm to 2 μm.

[0015] In some embodiments, the selection of the layers in the composite current collector satisfies at least one of the following conditions:

[0016] The substrate layer is selected from polymer substrate layers;

[0017] The first conductive layer is selected from any one of a carbon nanotube material layer, a graphene material layer, and a composite layer of both;

[0018] The second conductive layer is selected from an aluminum layer or a copper layer.

[0019] In some embodiments, the polymer substrate layer is selected from one or more composites of a PET layer, a PE layer, a PP layer, and a PI layer.

[0020] In some embodiments, the first conductive layer is disposed on two opposite surfaces of the substrate layer, and the second conductive layer is disposed on the surface of the first conductive layer facing away from the substrate layer.

[0021] In some embodiments, the substrate layer is provided with through holes, and conductive fillers are provided in the through holes, and the conductive fillers are connected to the first conductive layer and / or the second conductive layer on both sides of the substrate layer.

[0022] The present invention also provides an electrode tab, which includes a current collector and an active material layer. The current collector uses the composite current collector as described above; the active material layer is disposed on the surface of the second conductive layer facing away from the substrate layer.

[0023] The present invention also provides an electric core, which includes a positive electrode tab, a negative electrode tab, and a separator. The separator is disposed between the positive electrode tab and the negative electrode tab;

[0024] Wherein, at least one of the positive electrode tab and the negative electrode tab uses the electrode tab as described above.

[0025] The composite current collector of the technical solution of the present utility model includes a substrate layer, a first conductive layer, and two second conductive layers. The two second conductive layers are separately disposed on the two surfaces of the substrate layer in opposite directions. There is a first conductive layer on at least one side of the substrate layer. Specifically, the first conductive layer is sandwiched between the substrate layer and the second conductive layer, and its conductivity is greater than that of the second conductive layer. Thus, on the basis of the composite of the substrate layer and the second conductive layer, a first conductive layer with high conductivity is added between the substrate layer and the second conductive layer, which can reduce the impedance of the composite current collector and the internal resistance of the battery. Brief Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of a composite current collector according to an embodiment of the present utility model;

[0027] Figure 2 It is a schematic structural diagram of an electrode sheet according to an embodiment of the present utility model.

[0028] Explanation of the reference numerals in the drawings:

[0029] Label Name Label Name 10 Base material layer 31 Active material coating area 20 First conductive layer 40 Active material layer 21 Sub-conductive layer 50 Tab position 30 Second conductive layer

[0030] The realization, functional characteristics, and advantages of the object of the present utility model will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiments

[0031] Next, the solutions in the embodiments of the present utility model will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

[0032] It should be noted that all the directional indications (such as up, down, left, right, front, back...) in the embodiments of the present utility model are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0033] It should also be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0034] In addition, the descriptions involving "first", "second", etc. in the present utility model are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments may be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0035] The present utility model provides a composite current collector. Referring to Figure 1 , the composite current collector includes a substrate layer 10, a first conductive layer 20, and two second conductive layers 30. The first conductive layer 20 is disposed on at least one surface of the substrate layer 10; the two second conductive layers 30 are disposed on the two opposite surfaces of the substrate layer 10 and cover the first conductive layer 20; the conductivity of the first conductive layer 20 is greater than that of the second conductive layer 30. Based on the conventional composite current collector structure in which the substrate layer 10 is combined with the second conductive layer 30, a first conductive layer 20 with high conductivity is further disposed between the substrate layer 10 and the second conductive layer 30 on at least one side of the substrate layer 10, which can reduce the impedance of the composite current collector, improve the electrical conductivity, and reduce the internal resistance of the battery.

[0036] Specifically, in some embodiments, the first conductive layer 20 may be disposed only on one surface of the substrate layer 10. Then, among the two second conductive layers 30, one second conductive layer 30 is disposed on the surface of the first conductive layer 20 facing away from the substrate layer 10, and the other second conductive layer 30 is disposed on the surface of the substrate layer 10 facing away from the first conductive layer 20. In addition, referring to Figure 1 , in some embodiments, the first conductive layer 20 is disposed on the two opposite surfaces of the substrate layer 10, and the second conductive layer 30 is disposed on the surface of the first conductive layer 20 facing away from the substrate layer 10; by disposing the first conductive layer 20 on both sides of the substrate layer 10, the impedance of the current collector can be effectively reduced.

[0037] Referring to Figure 1, the first conductive layer 20 may include a plurality of sub-conductive layers 21, and each sub-conductive layer 21 is sequentially and spaced apart along the length direction of the substrate layer 10 on the surface of the substrate layer 10, so as to form a segmented conductive layer, and the segmented conductive layer is clamped between the second conductive layer 30 and the substrate layer 10. Of course, in some embodiments, the first conductive layer 20 can also be designed as a complete layer structure; in addition, for the case where the first conductive layer 20 is provided on both surfaces of the substrate layer 10, the above-mentioned segmented conductive layer can be used on both sides, or a segmented conductive layer can be used on one side and a complete layer structure conductive layer can be used on the other side. If the segmented conductive layer is used on both sides, the sub-conductive layers 21 on the first conductive layers 20 on both sides can be correspondingly arranged or offset, and preferably, the sub-conductive layers 21 on the first conductive layers 20 on both sides are correspondingly arranged.

[0038] In addition, for the case where the segmented conductive layer is provided on both sides of the substrate layer 10 and the sub-conductive layers 21 on the first conductive layers 20 on both sides are correspondingly arranged, in order to effectively reduce the internal resistance of the battery for further application of the composite current collector, it can be designed that an active material coating area 31 is provided on the surface of the second conductive layer 30 facing away from the substrate layer 10, and the active material coating areas 31 are sequentially and spaced apart along the length direction of the substrate layer 10 on the surface of the second conductive layer 30 corresponding to each sub-conductive layer 21. Then, when the composite current collector is subsequently applied to the preparation of the battery electrode, an active material layer is provided in the active material coating area 31 on the composite current collector, and the active material layer corresponds to the first conductive layer 20 to form a segmented active material layer. The active material layers corresponding to the sub-conductive layers 21 arranged at intervals can effectively utilize the highly conductive sub-conductive layers 21 to improve the conductive performance; and the position on the battery electrode corresponding to the position between adjacent sub-conductive layers 21 of the composite current collector can be used as the tab position, and the thickness of the second conductive layer 30 at the position between adjacent sub-conductive layers 21 is larger, which can improve the tab welding problem and is more conducive to realizing the automation of tab welding.

[0039] The substrate layer 10 serves as the basic support layer of the composite current collector and plays a role in support and connection. In order to reduce the weight of the composite current collector while ensuring the structural strength, the substrate layer 10 can adopt a polymer substrate layer, for example, it can adopt one or more composites of a polyethylene terephthalate (PET) layer, a polyethylene (PE) layer, a polypropylene (PP) layer, and a polyimide (PI) layer.

[0040] In some embodiments, the thickness of the substrate layer 10 is 2 μm to 3 μm, such as 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm. Compared with the thickness of the substrate layer in the conventional composite current collector of 4 μm to 6 μm, the substrate layer 10 in this composite current collector is thinned. At the same time, due to the addition of the first conductive layer 20 with high electrical conductivity, while ensuring safety, the current collector can be made thinner and lighter, and when applied to battery preparation, the energy density of the battery can be improved.

[0041] The conductivity of the first conductive layer 20 is greater than that of the second conductive layer 30. The first conductive layer 20 can specifically adopt a conductive material layer body with high conductivity. Specifically, the first conductive layer 20 can adopt a nanotube material layer, a graphene material layer, or a composite layer of both. The first conductive layer 20 can be configured by electroplating or other methods. In some embodiments, the thickness of the first conductive layer 20 can be controlled within 0.5 μm to 2 μm, such as 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 2 μm, etc. It is preferably to simultaneously control the thickness of the substrate layer 10 to be 2 μm to 3 μm and the thickness of the first conductive layer 20 to be 0.5 μm to 2 μm. Then, while thinning the thickness of the substrate layer, adding the first conductive layer 20 with high conductivity at the thinning position can reduce the impedance of the composite current collector and optimize the internal resistance of the battery.

[0042] The second conductive layer 30 is generally provided on the outermost layer of the composite current collector and can adopt an aluminum layer or a copper layer. Specifically, the composite current collector can be a positive current collector or a negative current collector. If the composite current collector is configured as a positive current collector, the second conductive layer 30 can be an aluminum layer. If the composite current collector is configured as a negative current collector, the second conductive layer 30 can be a copper layer.

[0043] In some embodiments, for the second conductive layer 30 provided on the surface of the first conductive layer 20, the thickness between the surface of the second conductive layer 30 facing away from the first conductive layer 20 and the joint surface of the second conductive layer 30 along the thickness direction of the substrate layer 10 and the first conductive layer 20 can be controlled within 1 μm to 2 μm, such as 1 μm, 1.3 μm, 1.5 μm, 1.6 μm, 1.8 μm, 2 μm, etc. Since the second conductive layer 30 has conductivity, the second conductive layer 30 and the first conductive layer 20 cooperate to form a composite conductive layer. As described above, if the thickness of the first conductive layer 20 is controlled within 0.5 μm to 2 μm, the thickness of the composite conductive layer formed by the second conductive layer 30 and the first conductive layer 20 is increased to 1.5 μm to 4 μm compared with the conventional thickness of the metal conductive layer of 0.5 μm to 1 μm. Then, it can improve the automatic welding of the current collector to the tab during the subsequent battery preparation process and make the composite current collector easier to process. In addition, for the case where the first conductive layer 20 is only provided on one side of the substrate layer 10, the thickness of the second conductive layer 30 provided on the surface of the substrate layer 10 facing away from the first conductive layer 20 can also be controlled within 1 μm to 2 μm.

[0044] During the research process, the inventors conducted a large number of experiments, including preparing composite current collectors with different laminate thicknesses and investigating the effects of the laminate thickness in the composite current collector on impedance and automated welding processing. This included: using a PET base film as the substrate layer 10 and thinning its thickness to 3 μm, and using carbon nanotubes to set a first conductive layer 20 with a thickness of 1.5 μm on both sides of the substrate layer. The first conductive layer 20 includes a plurality of sub-conductive layers 21 arranged at intervals along the length of the substrate layer 10. Furthermore, a second conductive layer coated with aluminum is set on both sides of the substrate layer 10 to form a composite current collector with a thickness of about 6 μm. The impedance of this composite current collector can be reduced by about 70% compared to a composite current collector composed of a substrate layer with a thickness of 4 μm - 6 μm and metal conductive layers with a thickness of 50 nm - 1 μm set on both sides thereof, and the welding excellent rate for automated welding of the tab during battery preparation is about 95%.

[0045] During the specific production process, the thickness of the first conductive layer 20 can be adjusted within the range of 0.5 μm - 2 μm according to the actual battery requirements to improve the energy density of the battery, and the thickness range of the composite current collector can be adjusted specifically according to the safety simulation performance test, life evaluation test, and storage performance test of the battery. Through experimental research, when the thickness of the substrate layer 10 is controlled within the range of 2 μm - 3 μm, the thickness of the first conductive layer 20 is controlled within the range of 0.5 μm - 2 μm, and the thickness between the surface of the second conductive layer 30 facing away from the first conductive layer 20 and the joint surface with the first conductive layer 20 along the thickness direction of the substrate layer 10 is controlled within the range of 1 μm - 2 μm, the impedance can be reduced by 20%, and its safety performance can be comparable to that of a conventional composite current collector battery.

[0046] In addition, in order to effectively reduce the internal resistance, in some embodiments, the substrate layer 10 is provided with through holes, and conductive fillers are provided in the through holes. The conductive fillers are connected to the first conductive layer 20 and / or the second conductive layer 30 on both sides of the substrate layer 10.

[0047] Specifically, the through holes on the substrate layer 10 can be opened at the corresponding positions of the sub-conductive layers 21 and / or at the corresponding positions between adjacent sub-conductive layers 21.

[0048] For example, if only one side of the substrate layer 10 is provided with the first conductive layer 20 and the first conductive layer 20 is a complete continuous layer, the substrate layer 10 is provided with through holes, and one end of the conductive filler provided in the through holes is connected to the first conductive layer 20 and the other end is connected to the second conductive layer 30; if the first conductive layer 20 is provided on both sides of the substrate layer 10 and the first conductive layer 20 is a complete continuous layer, the substrate layer 10 is provided with through holes, and the conductive filler provided in the through holes is connected to the first conductive layer 20 on both sides of the substrate layer.

[0049] If the first conductive layer 20 is provided only on one side of the base material layer 10, the first conductive layer 20 is a segmented conductive layer, and the through holes are opened at the positions corresponding to the sub-conductive layers 21, then one end of the conductive filler disposed in the through holes is connected to the first conductive layer 20, and the other end is connected to the second conductive layer 30; if the through holes are opened at the corresponding positions between adjacent sub-conductive layers 21, the conductive filler disposed in the through holes is connected to the second conductive layers 30 on both sides of the base material layer 10; if through holes are opened at both the positions corresponding to the sub-conductive layers 21 and the corresponding positions between adjacent sub-conductive layers 21, the conductive fillers at different positions are connected to the second conductive layer 30 and the first conductive layer 20 on both sides of the base material layer 10 in the above manner respectively.

[0050] If the first conductive layers 20 are provided on both opposite sides of the base material layer 10, the first conductive layers 20 on both sides are segmented conductive layers, and the sub-conductive layers 21 on the first conductive layers 20 on both sides are correspondingly arranged, the through holes are opened at the positions corresponding to the sub-conductive layers 21, and then the conductive filler disposed in the through holes is connected to the sub-conductive layers 21 on both sides of the base material layer 10; the through holes are opened at the corresponding positions between adjacent sub-conductive layers 21, and then the conductive filler disposed in the through holes is connected to the second conductive layers 30 on both sides of the base material layer; if through holes are opened at both the positions corresponding to the sub-conductive layers 21 and the corresponding positions between adjacent sub-conductive layers 21, the conductive fillers at different positions are connected to the second conductive layer 30 and the first conductive layer 20 on both sides of the base material layer 10 in the above manner respectively.

[0051] If the first conductive layers 20 are provided on both opposite sides of the base material layer 10, one of the first conductive layers 20 is a segmented conductive layer, and the other first conductive layer 20 is a complete continuous layer body, the through holes are opened at the positions corresponding to the sub-conductive layers 21, and the conductive filler disposed in the through holes is connected to the first conductive layers 20 at both ends of the base material layer 10, one end is connected to the sub-conductive layer 21 of the segmented conductive layer, and the other end is connected to the complete continuous first conductive layer 20; if the through holes are opened at the corresponding positions between adjacent sub-conductive layers 21, one end of the conductive filler disposed in the through holes is connected to the first conductive layer 20 (i.e., the complete continuous conductive layer), and the other end is connected to the second conductive layer 30; if through holes are opened at both the positions corresponding to the sub-conductive layers 21 and the corresponding positions between adjacent sub-conductive layers 21, the conductive fillers at different positions are connected to the second conductive layer 30 and the first conductive layer 20 on both sides of the base material layer 10 in the above manner respectively.

[0052] If the first conductive layers 20 are provided on both opposite sides of the base material layer 10, the first conductive layers 20 on both sides are segmented conductive layers, and the sub-conductive layers 21 on the first conductive layers 20 on both sides are arranged in a staggered manner, through holes are opened on the base material layer 10, and one end of the conductive filler disposed in the through holes is connected to the second conductive layer 30, and the other end is connected to the first conductive layer 20 (i.e., the sub-conductive layer 21).

[0053] By providing vias in the substrate layer 10 and filling the vias with conductive fillers, the second conductive layer 30 and the first conductive layer 20 on both sides of the substrate layer 10 can be electrically connected through the conductive fillers, thereby effectively solving the problems of large impedance of the composite current collector and large internal resistance of the battery.

[0054] An embodiment of the present invention further provides an electrode sheet. Refer to Figure 2 , the electrode sheet includes a current collector and an active material layer 40. The current collector adopts the composite current collector described in the foregoing embodiment, and the active material layer 40 is disposed on the surface of the second conductive layer 30 of the composite current collector facing away from the substrate layer 10. For the specific structure of the composite current collector, refer to the above embodiment. Since the electrode sheet adopts the composite current collector of the above embodiment, it has at least the technical effects corresponding to the technical solutions of the adopted embodiment, and will not be elaborated herein one by one.

[0055] The electrode sheet can be a positive electrode sheet or a negative electrode sheet. If the electrode sheet is configured as a positive electrode sheet, the second conductive layer 30 in the composite current collector can be an aluminum layer, and the active material layer 40 is a positive electrode active material layer; if the electrode sheet is configured as a negative electrode sheet, the second conductive layer 30 in the composite current collector can be a copper layer, and the active material layer 40 is a negative electrode active material layer.

[0056] Refer to Figure 2 , the electrode sheet adopts the composite current collector of the embodiment shown in Figure 1 . Segmented conductive layers are provided on both sides of the substrate layer 10, and the sub-conductive layers 21 on the first conductive layers 20 on both sides are correspondingly arranged. An active material coating area 31 is provided on the surface of the second conductive layer 30 facing away from the substrate layer 10. The active material coating areas 31 are arranged at intervals in the length direction of the substrate layer 10 on the surface of the second conductive layer 30 corresponding to each sub-conductive layer 21. Further, the active material layer 40 on the electrode sheet is specifically disposed in the active material coating area 31 on the second conductive layer 30 of the composite current collector, and the active material layer 40 is a segmented active material layer corresponding to the first conductive layer 20; and the position on the electrode sheet corresponding to the adjacent sub-conductive layers 21 of the composite current collector is used as the tab position, which can effectively reduce the internal resistance of the electrode sheet in further application in the battery.

[0057] An embodiment of the present invention further provides an electric core. The electric core includes a positive electrode sheet, a negative electrode sheet and a separator. The separator is sandwiched between the positive electrode sheet and the negative electrode sheet, and at least one of the positive electrode sheet and the negative electrode sheet adopts the electrode sheet described in the foregoing embodiment. For the specific structure of the electrode sheet, refer to the above embodiment. Since the electric core of the present invention adopts all the technical solutions of the above all embodiments, it has at least all the technical effects brought by the technical solutions of the above embodiments, and will not be elaborated herein one by one.

[0058] The above are only some or preferred embodiments of the present utility model. Neither the text nor the drawings can limit the scope of protection of the present utility model. Any equivalent structural transformation made by using the content of the specification and drawings of the present utility model under the overall concept of the present utility model, or any direct / indirect application in other related technical fields, is included in the scope of protection of the present utility model.

Claims

1. A composite current collector, characterized in that, Comprising: A substrate layer; A first conductive layer disposed on at least one surface of the substrate layer; Two second conductive layers disposed on opposite surfaces of the substrate layer and covering the first conductive layer; Wherein, the conductivity of the first conductive layer is greater than that of the second conductive layer.

2. The composite current collector according to claim 1, wherein The first conductive layer includes a plurality of sub-conductive layers, and each of the sub-conductive layers is sequentially and spaced apart along the length direction of the substrate layer on the surface of the substrate layer.

3. The composite current collector according to claim 2, wherein An active material coating area is provided on the surface of the second conductive layer facing away from the substrate layer, and the active material coating areas corresponding to each of the sub-conductive layers are sequentially and spaced apart along the length direction of the substrate layer on the surface of the second conductive layer.

4. The composite current collector according to any one of claims 1 to 3, characterized in that The layer thickness in the composite current collector satisfies at least one of the following conditions: The thickness of the substrate layer is 2 μm to 3 μm; The thickness of the first conductive layer is 0.5 μm to 2 μm; The thickness between the surface of the second conductive layer facing away from the first conductive layer and the bonding surface with the first conductive layer along the thickness direction of the substrate layer is 1 μm to 2 μm.

5. The composite current collector according to claim 4, wherein The layer selection in the composite current collector satisfies at least one of the following conditions: The substrate layer is selected from a polymer substrate layer; The first conductive layer is selected from any one of a carbon nanotube material layer, a graphene material layer, and a composite layer of the two; The second conductive layer is selected from an aluminum layer or a copper layer.

6. The composite current collector according to claim 5, wherein, The polymer substrate layer is selected from one or more composites of a PET layer, a PE layer, a PP layer, and a PI layer.

7. The composite current collector according to any one of claims 1 to 3, characterized in that, The first conductive layer is disposed on opposite surfaces of the substrate layer, and the second conductive layer is disposed on the surface of the first conductive layer facing away from the substrate layer.

8. The composite current collector according to any one of claims 1 to 3, wherein The substrate layer is provided with through holes, and conductive fillers are provided in the through holes, and the conductive fillers connect the first conductive layer and / or the second conductive layer on both sides of the substrate layer.

9. A pole piece, characterized in that, Comprising a current collector and an active material layer, the current collector is a composite current collector according to any one of claims 1 to 8; the active material layer is disposed on the surface of the second conductive layer facing away from the substrate layer.

10. A battery cell, characterized in that, Comprising a positive electrode plate, a negative electrode plate, and a separator, the separator is disposed between the positive electrode plate and the negative electrode plate; Wherein, at least one of the positive electrode plate and the negative electrode plate is a pole piece according to claim 9.

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