Composite current collector, pole group and battery cell

Abstract

The invention relates to the technical field of batteries, and discloses a composite current collector, a pole group and a battery cell. The composite current collector comprises a current collector body, the current collector body comprises an insulating layer and first metal layers, the first metal layers are arranged on the two opposite sides of the insulating layer in the thickness direction of the insulating layer, and the orthographic projection of the insulating layer in the thickness direction of the insulating layer falls into the range of any first metal layer; and the metal tab is positioned on one side in the length direction or the width direction of the insulating layer and is connected with the pair of first metal layers. According to the invention, the first metal layer is connected with the metal tab, so that the current collector body can be directly welded with other structures such as a pole in a battery cell by virtue of the metal tab, and the welding difficulty and the assembly difficulty are reduced.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a composite current collector, electrode assembly, and battery cell. Background Technology

[0002] The primary function of a current collector is to provide support for the electrode active material and to conduct current during charging and discharging. An ideal current collector should possess good conductivity, sufficient mechanical strength, excellent chemical stability, and good adhesion to the active material. Therefore, metals are generally chosen for current collector fabrication. However, metal current collectors suffer from being heavy and having lower safety. To address these issues, an insulating layer is currently incorporated into the metal current collector. While this effectively solves the technical problems, the non-metallic insulating layer increases the difficulty of subsequent welding of the current collector to other structures within the battery cell. Summary of the Invention

[0003] In view of this, the present invention provides a composite current collector, electrode assembly and battery cell to solve the problem that the addition of an insulating layer to existing current collectors affects the welding of the current collector to other structures of the battery cell.

[0004] In a first aspect, the present invention provides a composite current collector, comprising: The current collector body includes an insulating layer and a first metal layer. Along the thickness direction of the insulating layer, the first metal layer is disposed on opposite sides of the insulating layer, and the orthographic projection of the insulating layer in its thickness direction falls within the range of either of the first metal layers. Metal tabs are located on one side of the insulation layer along its length or width and are connected to a pair of the first metal layers.

[0005] Beneficial Effects: Compared to pure metal current collectors in the prior art, the composite current collector of the present invention, after introducing an insulating layer, has at least the following advantages: 1. Under the same volume, the composite current collector of the present invention can have a relatively small weight, which not only helps to reduce the weight of the battery cells and battery packs subsequently assembled with the composite current collector of the present invention, but also helps to improve the energy density of the battery cells and battery packs; 2. The addition of the insulating layer reduces the dependence of the composite current collector on metal materials, reduces the amount of metal materials used, and thus reduces the manufacturing cost of the composite current collector; 3. The addition of the insulating layer can reduce the risk of short circuits under extreme conditions such as puncture or compression, prevent dangerous conditions such as thermal runaway inside the battery cell, and improve the safety of the battery cell during charging and discharging. Furthermore, by setting a first metal layer on opposite sides of the insulating layer, the present invention allows the composite current collector of the present invention to retain the high conductivity and good mechanical strength characteristics of pure metal current collectors. At the same time, setting a pair of first metal layers on opposite sides of the insulating layer can also make the current relatively uniformly distributed on the surface of the current collector, reducing the heating phenomenon caused by excessive local current density and reducing resistance loss. Furthermore, by connecting the first metal layer to the metal tab, the present invention enables the current collector body to be directly welded to other structures in the battery cell, such as the terminal block, through the metal tab, thereby reducing the difficulty of welding and assembly. In one alternative embodiment, the thickness of the first metal layer ranges from 0.5 μm to 12 μm, the thickness of the insulating layer ranges from 0.5 μm to 10 μm, and the total thickness of the current collector body ranges from 3 μm to 15 μm.

[0006] Beneficial effects: By limiting the thickness of the first metal layer to between 0.5 μm and 12 μm, this invention not only ensures sufficient conductivity and mechanical strength of the composite current collector but also avoids the problem of increased weight due to excessive thickness. Furthermore, by controlling the insulation layer thickness to between 0.5 μm and 10 μm, this invention effectively isolates the first metal layers on both sides, preventing short circuits, and also reasonably limits the amount of insulating material used, avoiding the problem of reduced overall conductivity of the composite current collector due to excessive insulation layer thickness. Controlling the total thickness of the current collector body to between 3 μm and 15 μm allows for a more compact overall structure, adapting to the internal space layout requirements of various battery cells, thus facilitating the integration of the composite current collector into battery cells and battery packs of different specifications. Moreover, this thickness range ensures that the materials in each layer work synergistically, enabling the composite current collector to meet the performance requirements of lightweight, conductivity, and insulation, avoiding insufficient mechanical strength due to excessive thinness or unnecessary weight and cost increases due to excessive thickness.

[0007] In one alternative embodiment, along the thickness direction of the insulating layer, the two side surfaces of the metal tab are respectively flush with the surface of the corresponding first metal layer.

[0008] Beneficial effects: The two sides of the metal tab are flush with the surface of the corresponding first metal layer. On the one hand, this makes the structure of the composite current collector more compact and reduces the space occupied inside the cell. On the other hand, it reduces stress concentration caused by height difference and lowers the risk of damage to the composite current collector due to stress during use.

[0009] In one alternative embodiment, the metal tab is located on one side of the insulation layer along its length, and the length of the metal tab is less than the length of the current collector body, with the ratio between the two ranging from 0.05 to 0.2.

[0010] Beneficial effects: This invention controls the ratio of the length of the metal tab to the length of the current collector body between 0.05 and 0.2. On the one hand, this avoids the problems of increased resistance and space occupation caused by excessively long tabs; on the other hand, it avoids the defects of insufficient welding area caused by insufficient tab length. In addition, the reasonable size ratio can also optimize the cost of the tabs, thereby reducing the manufacturing cost of the composite current collector.

[0011] In one alternative embodiment, along the length direction of the insulating layer and / or along the width direction of the insulating layer, a second metal layer connected to a pair of first metal layers is provided on opposite sides of the insulating layer, and the first metal layer and the second metal layer together form the mounting space of the insulating layer.

[0012] Beneficial Effects: This invention, by providing a second metal layer connected to the first metal layer on the periphery of the insulating layer, forms a "reinforced framework" on the surface of the insulating layer, enhancing the structural strength of the current collector. Furthermore, compared to a current collector with the insulating layer directly exposed on the periphery, the presence of a second metal layer reduces resistance, decreases energy loss during current transmission, and improves power transmission efficiency. The specific reasons are as follows: Without the second metal layer, current must bypass the edges of the insulating layer or other non-conductive areas, leading to increased resistance in localized areas. Connecting the second metal layer to the first metal layer not only increases the effective conductive area and shortens the transmission path but also reduces the overall resistance of the current collector from multiple dimensions by utilizing the low-resistance contact characteristics between metals, thereby reducing current transmission energy consumption and improving power transmission efficiency.

[0013] In one alternative embodiment, the first metal layer and the second metal layer are integrally formed, and the metal tab is integrally formed with one of the second metal layers.

[0014] Beneficial effects: Whether the first and second metal layers are integrally molded, or the metal tabs and the second metal layer are integrally molded, both processes avoid gaps and loose connections that may occur in traditional splicing or welding processes. This eliminates stress concentration points and creates a robust and continuous integral structure between the first and second metal layers, and between the second metal layer and the metal tabs, improving the mechanical strength and deformation resistance of the current collector. Furthermore, the integral molding process not only reduces contact resistance caused by interface connections, lowers current transmission losses, and enhances conductivity, but also simplifies the process flow and improves production efficiency.

[0015] Secondly, the present invention also provides an electrode assembly, comprising: In the aforementioned composite current collector, a portion of the composite current collector has a positive electrode active material coated on its first metal layer to form a positive electrode sheet; another portion of the composite current collector has a negative electrode active material coated on its first metal layer to form a negative electrode sheet; and a plurality of the positive electrode sheets and a plurality of the negative electrode sheets are stacked together. An insulating membrane is located between the positive electrode and the negative electrode to separate the positive electrode and the negative electrode.

[0016] Beneficial effects: The aforementioned composite current collector provides a high-strength, low-resistance conductive substrate for both the positive and negative electrodes. This not only enhances the stability of the electrode structure but also reduces the internal impedance of the cell, improving its charge and discharge efficiency. Furthermore, by placing an insulating membrane between the positive and negative electrodes, short circuits are prevented while allowing ions to freely move between them, ensuring the smooth progress of the electrochemical reactions within the cell.

[0017] In one alternative embodiment, the metal tabs in the positive electrode and the metal tabs in the negative electrode are disposed on opposite sides.

[0018] Beneficial effects: By setting the metal tabs of the positive electrode and the negative electrode on opposite sides, the present invention enables the positive current and the negative current to be output from different sides, reducing cross-interference of current within the electrode group, lowering circuit impedance, and improving charging and discharging efficiency.

[0019] In one optional embodiment, the first metal layer in the positive electrode is made of aluminum, and the first metal layer in the negative electrode is made of copper.

[0020] Beneficial effects: The standard electrode potential of aluminum has a high degree of matching with positive electrode active materials (such as lithium cobalt oxide, lithium iron phosphate, etc.), which can reduce interfacial side reactions. In addition, aluminum has stable chemical properties at high potentials, which can effectively inhibit the corrosion of the current collector body and ensure the structural stability of the positive electrode sheet. When copper is paired with negative electrode active materials (such as graphite), the low electrode potential of copper can prevent lithium from depositing on the surface of the current collector body, reducing the risk of dendrite growth. At the same time, the high conductivity of copper also helps to improve the electron transport efficiency of the negative electrode.

[0021] Thirdly, the present invention also provides a battery cell, comprising: The housing has a cavity and an opening communicating with the cavity; A cover plate is provided to cover and seal the opening, and the cover plate is provided with a positive terminal and a negative terminal; In the aforementioned electrode assembly, the metal tab in the positive electrode plate is connected to the positive electrode post, and the metal tab in the negative electrode plate is connected to the negative electrode post.

[0022] Beneficial effects: The battery cell of the present invention includes the electrode group as described above, and has all the beneficial technical effects of the electrode group, which will not be repeated here. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a composite current collector according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a pole group according to an embodiment of the present invention; Figure 3 This is a comparison chart of voltage curves of the composite current collector of the present invention, the existing pure metal current collector, and the existing composite current collector; Figure 4 This is a comparison chart of the heat generation power of the composite current collector of the present invention, the existing pure metal current collector, and the existing composite current collector; Figure 5 This is a comparison diagram of the electrode current density of the composite current collector of the present invention, the existing pure metal current collector, and the existing composite current collector.

[0025] Explanation of reference numerals in the attached figures: 1. Current collector body; 101. Insulating layer; 102. First metal layer; 2. Metal tab; 3. Second metal layer; 4. Positive electrode active material; 5. Negative electrode active material; 6. Insulating membrane. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] To address the problem that adding an insulating layer to existing current collectors affects the welding of the current collector to other structures in the battery cell, this invention provides a composite current collector, electrode assembly, and battery cell.

[0028] The following is combined with Figures 1 to 5 The following describes embodiments of the present invention.

[0029] According to an embodiment of the present invention, in one aspect, such as Figure 1 As shown, a composite current collector is provided, comprising: a current collector body 1 and a metal tab 2.

[0030] Specifically, the current collector body 1 includes an insulating layer 101 and a first metal layer 102. Along the thickness direction of the insulating layer 101, the first metal layer 102 is disposed on opposite sides of the insulating layer 101, and the orthographic projection of the insulating layer 101 in its thickness direction falls within the range of either first metal layer 102. The metal tab 2 is located on one side of the insulating layer 101 in the length direction or the width direction of the insulating layer 101 and is connected to a pair of first metal layers 102.

[0031] Compared to pure metal current collectors in the prior art, the composite current collector of this invention has at least the following advantages after introducing the insulating layer 101: First, the composite current collector of this invention can have a relatively small weight in the same volume, which not only helps to reduce the weight of the battery cells and battery packs subsequently assembled with the composite current collector of this invention, but also helps to improve the energy density of the battery cells and battery packs; Second, the addition of the insulating layer 101 reduces the dependence of the composite current collector on metal materials, reduces the amount of metal materials used, and thus reduces the manufacturing cost of the composite current collector; Third, the addition of the insulating layer 101 can reduce the risk of short circuits that may occur under extreme conditions such as puncture or compression, prevent dangerous conditions such as thermal runaway inside the battery cell, and improve the safety of the battery cell during charging and discharging. Furthermore, by providing a first metal layer 102 on opposite sides of the insulating layer 101, the composite current collector of this invention can retain the high conductivity and good mechanical strength characteristics of pure metal current collectors. Meanwhile, by distributing a pair of first metal layers 102 on opposite sides of the insulating layer 101, the current can be distributed relatively evenly on the surface of the current collector, reducing heat generation caused by excessive local current density and lowering resistance loss. Furthermore, in this embodiment of the invention, connecting the first metal layers 102 to the metal tabs 2 allows the current collector body 1 to be directly welded to other structures in the battery cell, such as terminals, via the metal tabs 2, reducing welding and assembly difficulties.

[0032] Specifically, the material of the first metal layer 102 can be, but is not limited to, metal foil and foamed metal. For example, the metal foil can be aluminum or stainless steel with silver surface treatment, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc.; the foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc.

[0033] Specifically, the material of the insulating layer 101 may be, but is not limited to, polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate, and polystyrene.

[0034] It should be noted that, in this embodiment, the first metal layer 102 being disposed on opposite sides of the insulating layer 101 means that the first metal layer 102 is attached to the surface of the insulating layer 101. Furthermore, the material of the metal tab 2 can be the same as or different from the material of the first metal layer 102; this invention does not impose specific limitations on this.

[0035] According to one embodiment of the present invention, the thickness of the first metal layer 102 ranges from 0.5 μm to 12 μm, the thickness of the insulating layer 101 ranges from 0.5 μm to 10 μm, and the total thickness of the current collector body 1 ranges from 3 μm to 15 μm.

[0036] In this embodiment of the invention, the thickness of the first metal layer 102 is limited to between 0.5 μm and 12 μm. This not only ensures sufficient conductivity and mechanical strength of the composite current collector but also avoids the problem of increased weight due to excessive thickness. Similarly, the thickness of the insulating layer 101 is controlled between 0.5 μm and 10 μm. This effectively isolates the first metal layers 102 on both sides, preventing short circuits, and also reasonably limits the amount of insulating material used, avoiding a decrease in overall conductivity due to excessive thickness of the insulating layer 101. Furthermore, controlling the total thickness of the current collector body 1 between 3 μm and 15 μm allows for a more compact overall structure, adapting to the internal space layout requirements of various battery cells, thus facilitating the integration of the composite current collector of this embodiment into battery cells and battery packs of different specifications. This thickness range also ensures that the materials in each layer work synergistically, enabling the composite current collector of this embodiment to meet the performance requirements of lightweight, conductivity, and insulation, avoiding insufficient mechanical strength due to excessive thinness or unnecessary weight and cost due to excessive thickness.

[0037] It is understood that the composite current collector of this embodiment can be used as the substrate of either the positive electrode or the negative electrode. For example, if the composite current collector of this embodiment is used as the substrate of the negative electrode, then the thickness of the first metal layer 102 is 0.5 μm to 5 μm, preferably 1 μm to 2 μm; the thickness of the insulating layer 101 is 0.5 μm to 10 μm, preferably 1 μm to 5 μm; and the total thickness of the composite current collector is 3 μm to 12 μm. If the composite current collector of this embodiment is used as the substrate of the positive electrode, then the thickness of the first metal layer 102 is 0.5 μm to 12 μm, preferably 1 μm to 5 μm; the thickness of the insulating layer 101 is 0.5 μm to 10 μm, preferably 1 μm to 5 μm; and the total thickness of the composite current collector is 5 μm to 15 μm.

[0038] According to one embodiment of the present invention, along the thickness direction of the insulating layer 101, the two side surfaces of the metal tab 2 are respectively flush with the surface of the corresponding first metal layer 102. This arrangement allows for a more compact structure of the composite current collector, reducing the space occupied inside the battery cell; it also reduces stress concentration caused by height differences, lowering the risk of stress-induced damage to the composite current collector during use.

[0039] According to one embodiment of the present invention, the metal tab 2 is located on one side of the insulating layer 101 along its length. The length of the metal tab 2 is less than the length of the current collector body 1, and the ratio between the two is in the range of 0.05 to 0.2. This embodiment of the present invention controls the ratio of the length of the metal tab 2 to the length of the current collector body 1 to be between 0.05 and 0.2. On the one hand, this avoids the problems of increased resistance and increased space occupation caused by excessive tab length; on the other hand, it avoids the defect of insufficient welding area caused by insufficient tab length. Furthermore, a reasonable size ratio can optimize the cost of the tab, thereby reducing the manufacturing cost of the composite current collector.

[0040] It should be noted that, in this embodiment, the ratio of the length of the metal tab 2 to the length of the current collector body 1 can be, but is not limited to, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, or 0.2.

[0041] According to one embodiment of the present invention, along the length direction and / or the width direction of the insulating layer 101, a second metal layer 3 connected to the first metal layer 102 is provided on opposite sides of the insulating layer 101. The first metal layer 102 and the second metal layer 3 together form the mounting space of the insulating layer 101. By providing the second metal layer 3 connected to the first metal layer 102 on the periphery of the insulating layer 101, this embodiment of the present invention can form a "reinforced frame" on the surface of the insulating layer 101, improving the structural strength of the current collector body 1. Furthermore, compared to the current collector body 1 with the insulating layer 101 directly exposed on the periphery, providing the second metal layer 3 on the periphery of the insulating layer 101 can reduce resistance, reduce energy loss during current transmission, and improve power transmission efficiency. The specific reason is as follows: without the second metal layer 3, the current needs to bypass through the edge of the insulating layer 101 or other non-conductive areas, which will lead to an increase in resistance in local areas. By connecting the second metal layer 3 to the first metal layer 102, not only can the effective conductive area be increased and the transmission path shortened, but also the overall resistance of the current collector body 1 can be reduced from multiple dimensions by taking advantage of the low resistance contact characteristics between metals, thereby reducing the energy consumption of current transmission and improving the efficiency of power transmission.

[0042] It should be noted that, in order to control the cost of the composite current collector in this embodiment, the second metal layer 3 may not be provided on the periphery of the insulating layer 101, or the second metal layer 3 may only be provided on one side of the insulating layer 101.

[0043] According to one embodiment of the present invention, the first metal layer 102 and the second metal layer 3 are integrally formed, and the metal tab 2 is integrally formed with one of the second metal layers 3. Whether the first metal layer 102 and the second metal layer 3 are integrally formed, or the metal tab 2 and the second metal layer 3 are integrally formed, problems such as gaps and incomplete connections that may occur in traditional splicing or welding processes can be avoided, stress concentration points can be eliminated, and a strong and continuous integral structure can be formed between the first metal layer 102 and the second metal layer 3, and between the second metal layer 3 and the metal tab 2, thereby improving the mechanical strength and deformation resistance of the current collector body 1. Furthermore, the integral forming process can not only reduce contact resistance caused by interface connections, reduce current transmission loss, and enhance conductivity, but also simplify the process flow and improve production efficiency.

[0044] Furthermore, combined Figures 3 to 5 This describes the effect of the composite current collector in the embodiments of the present invention.

[0045] Specifically, according to Figure 3 It is known that existing pure metal current collectors, such as pure copper current collectors, have the lowest voltage plateau, while existing composite current collectors have the highest voltage plateau. The voltage plateau of the composite current collector in this embodiment of the invention is in the middle, meaning that the polarization of the composite current collector in this embodiment of the invention is between that of existing pure metal current collectors and existing composite current collectors. It should be noted that... Figure 3 In this context, SOC refers to the state of charge.

[0046] Specifically, according to Figure 4 It is known that existing pure metal current collectors, such as pure copper metal current collectors, have the lowest heat generation power, while existing composite current collectors have the highest heat generation power. The heat generation power of the composite current collector in this embodiment of the invention is between the two.

[0047] Specifically, according to Figure 5 It is known that the electrode current density of existing pure metal current collectors, such as pure copper metal current collectors, is the lowest, while the electrode current density of existing composite current collectors is the highest. The current density of the composite current collector in the embodiments of the present invention is between the two.

[0048] According to an embodiment of the present invention, on the other hand, such as Figure 2 As shown, an electrode assembly is also provided, comprising: the aforementioned composite current collector and an insulating membrane 6. Specifically, a portion of the composite current collector has a first metal layer 102 coated with a positive electrode active material 4 to form a positive electrode sheet; another portion of the composite current collector has a first metal layer 102 coated with a negative electrode active material 5 to form a negative electrode sheet; multiple positive electrode sheets and multiple negative electrode sheets are stacked; the insulating membrane 6 is located between the positive electrode sheets and the negative electrode sheets to separate them.

[0049] The aforementioned composite current collector provides a high-strength, low-resistance conductive substrate for both the positive and negative electrodes. This not only enhances the stability of the electrode structure but also reduces the internal impedance of the cell, thereby improving its charge and discharge efficiency. Furthermore, by placing an insulating membrane 6 between the positive and negative electrodes, short circuits are prevented while allowing ions to freely move between them, ensuring the smooth progress of the electrochemical reactions within the cell.

[0050] Specifically, the positive electrode active material 4 may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material 4 of the battery may also be used. These positive electrode active materials 4 may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites. The negative electrode active material 5 may be a negative electrode active material 5 known in the art for use in battery cells. As an example, the negative electrode active material 5 may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The main material of the insulating separator 6 may be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride, and ceramics.

[0051] According to one embodiment of the present invention, the metal tab 2 in the positive electrode and the metal tab 2 in the negative electrode are arranged on opposite sides. This arrangement of the metal tab 2 in the positive electrode and the metal tab 2 in the negative electrode allows the positive and negative currents to be drawn from different sides, reducing cross-interference of currents within the electrode assembly, lowering circuit impedance, and improving charging and discharging efficiency.

[0052] According to one embodiment of the present invention, the first metal layer 102 in the positive electrode is made of aluminum, and the first metal layer 102 in the negative electrode is made of copper. It is understood that aluminum has a high degree of matching between its standard electrode potential and the positive electrode active material 4 (such as lithium cobalt oxide, lithium iron phosphate, etc.), which can reduce interfacial side reactions. Furthermore, aluminum is chemically stable at high potentials, effectively inhibiting corrosion of the current collector body 1 and ensuring the structural stability of the positive electrode. When copper is paired with the negative electrode active material 5 (such as graphite), its low electrode potential characteristic can prevent lithium deposition on the surface of the current collector body 1, reducing the risk of dendrite growth. At the same time, copper's high conductivity also helps to improve the electron transport efficiency of the negative electrode.

[0053] According to an embodiment of the present invention, another aspect provides a battery cell, comprising: a housing, a cover plate, and the aforementioned electrode assembly.

[0054] Specifically, the shell has a cavity and an opening connected to the cavity; a cover plate covers and seals the opening, and a positive electrode post and a negative electrode post are provided on the cover plate; the metal tab 2 in the positive electrode plate is connected to the positive electrode post, and the metal tab 2 in the negative electrode plate is connected to the negative electrode post.

[0055] The battery cell of this invention includes the electrode group as described above, and has all the beneficial technical effects of the electrode group, which will not be repeated here.

[0056] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A composite current collector, characterized by, The composite current collector comprises: a current collector body comprising an insulating layer and a first metal layer, the first metal layer being arranged on opposite sides of the insulating layer along the thickness direction of the insulating layer, and the orthogonal projection of the insulating layer in the thickness direction falling within the range of any of the first metal layers; a metal tab arranged on one side of the insulating layer in the length direction or the width direction and connected to a pair of the first metal layers.

2. The composite current collector of claim 1, wherein The thickness of the first metal layer ranges from 0.5 μm to 12 μm, the thickness of the insulating layer ranges from 0.5 μm to 10 μm, and the total thickness of the current collector body ranges from 3 μm to 15 μm.

3. The composite current collector of claim 1, wherein Along the thickness direction of the insulating layer, the two side surfaces of the metal tab are flush with the surfaces of the corresponding first metal layers.

4. The composite current collector of claim 1, wherein The metal tab is arranged on one side of the insulating layer in the length direction, the length of the metal tab is less than the length of the current collector body, and the ratio of the length of the metal tab to the length of the current collector body ranges from 0.05 to 0.

2.

5. The composite current collector of any one of claims 1 to 4, wherein, Along the length direction of the insulating layer and / or along the width direction of the insulating layer, opposite sides of the insulating layer are provided with a second metal layer connected to a pair of the first metal layers, and the first metal layers and the second metal layers jointly form a mounting space of the insulating layer.

6. The composite current collector of claim 5, wherein, The first metal layers and the second metal layers are integrally formed, and the metal tab is integrally formed with one of the second metal layers.

7. A pole assembly characterized by, The composite current collector comprises: a plurality of the composite current collectors according to any one of claims 1 to 6, wherein a portion of the first metal layers of the composite current collectors is coated with a positive active material to form positive electrode sheets, and another portion of the first metal layers of the composite current collectors is coated with a negative active material to form negative electrode sheets, and the positive electrode sheets and the negative electrode sheets are arranged in a stack; an insulating separator arranged between the positive electrode sheets and the negative electrode sheets to separate the positive electrode sheets and the negative electrode sheets.

8. The pole assembly of claim 7, wherein, The metal tabs in the positive electrode sheets and the metal tabs in the negative electrode sheets are arranged on opposite sides.

9. The pole assembly of claim 7, wherein, The material of the first metal layers in the positive electrode sheets is aluminum, and the material of the first metal layers in the negative electrode sheets is copper.

10. An electric cell characterized by The battery comprises: a shell provided with a cavity and an opening communicating with the cavity; a cover plate covering and sealing the opening, the cover plate being provided with a positive electrode column and a negative electrode column; the electrode group according to any one of claims 7 to 9, the metal tabs in the positive electrode sheets being connected to the positive electrode column, and the metal tabs in the negative electrode sheets being connected to the negative electrode column.

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