Composite current collector, battery cell and lithium battery

Abstract

The present application relates to a kind of composite current collector, battery and lithium battery, the composite current collector includes a polymer insulating layer and a metal layer, one side surface of the polymer insulating layer is attached with the one side surface of the metal layer;The surface of the metal layer and the polymer insulating layer attached is first surface, the surface of the polymer insulating layer and the metal layer attached is second surface, the first surface extends to the outside of the second surface in the first direction.This application improves the mechanical properties of current collector by using polymer insulating layer, on the other hand, using single-sided composite metal layer, can reduce the cutting burr of metal layer, improve the safety of battery;In addition, the first connecting end of the present application extending out of the metal layer is directly used as tab or connected with external tab, solves the welding difficulty problem of composite current collector and tab, realizes the lightweight of battery, and reduces the cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a composite current collector, a battery cell and a lithium battery. BACKGROUND

[0002] The current collector in the existing lithium ion battery is mainly divided into two categories. One is to use pure metal foil as the current collector, such as using aluminum foil for the positive electrode sheet and using copper foil for the negative electrode sheet to realize the collection of electric current. However, the pure metal foil has reached a high level in the improvement of battery energy density, that is, the mass ratio of the foil in the total mass of the battery cell cannot be further reduced, resulting in that the electrode sheet is difficult to be further improved to a thinner thickness, otherwise it will be difficult to control the cost and quality.

[0003] The other is a composite current collector, the structure of which is shown in Figure 1 The composite current collector includes a polymer material layer 01 and a metal material layer 02 which is respectively compounded on both sides of the polymer material layer 01. This composite current collector can reduce the mass of the current collector per unit area, realize high energy density and light weight of the lithium battery. However, the existing composite current collector is suitable for double-sided coating electrode sheet technology, and when thermal runaway or failure occurs, it is easy to cause a chain reaction, and the safety is low. In addition, the intermediate polymer material layer 01 also causes great difficulty in welding of the electrode lug of the battery cell. SUMMARY

[0004] The present application provides a composite current collector, a battery cell and a lithium battery to solve the problems of low safety and difficult lug welding of the existing composite current collector.

[0005] To solve the above technical problems, the present application provides a composite current collector, which includes a polymer insulating layer and a metal layer, one side surface of the polymer insulating layer is attached to one side surface of the metal layer; the surface of the metal layer attached to the polymer insulating layer is a first surface, the surface of the polymer insulating layer attached to the metal layer is a second surface, and the first surface extends to the outside of the second surface in a first direction.

[0006] Preferably, the part of the first surface extending to the outside of the second surface is a first extension surface, the first extension surface corresponds to a first connecting end of the metal layer, and the first connecting end is used as an electrode lug.

[0007] Preferably, the part of the first surface extending to the outside of the second surface is a first extension surface, the first extension surface corresponds to a first connecting end of the metal layer, and the first connecting end is connected to an external electrode lug.

[0008] Preferably, the length of the first connecting end in the first direction is 0.3cm-10cm.

[0009] Preferably, in the second direction, the second surface extends to the outside of the first surface, and the second direction is opposite to the first direction.

[0010] Preferably, the part of the second surface extending to the outside of the first surface is a second extending surface, and the second extending surface corresponds to a second connecting end of the polymer insulating layer, and the second connecting end is used for packaging.

[0011] Preferably, the polymer insulating layer is made of one or more monomers of polyethylene terephthalate, polypropylene, polyacrylonitrile, polyethylene, polytetrafluoroethylene, polyvinylidene fluoride, polyamide, polyimide, polyvinyl chloride or polystyrene.

[0012] Preferably, the thickness of the polymer insulating layer is 2-15 μm.

[0013] Preferably, the metal layer is made of a metal foil or coated on the surface of a non-metal layer, and the metal foil includes one or more of aluminum foil, copper foil, nickel foil, titanium foil, silver foil, nickel-copper alloy foil, aluminum-zirconium alloy foil and stainless steel foil.

[0014] Preferably, the thickness of the metal layer is 1-15 μm.

[0015] The application further provides a battery cell, which includes a positive electrode sheet and a negative electrode sheet, the positive electrode sheet is obtained by coating a positive electrode slurry on the composite current collector as described above, the negative electrode sheet is obtained by coating a negative electrode slurry on the composite current collector as described above, and a diaphragm is arranged between the positive electrode sheet and the negative electrode sheet.

[0016] The application further provides a lithium battery, which includes the battery cell as described above.

[0017] Compared with the prior art, the composite current collector, the battery cell and the lithium battery provided by the application have the following advantages:

[0018] 1. On one hand, the polymer insulating layer improves the mechanical properties of the current collector, and on the other hand, the single-sided composite metal layer can reduce the cutting burrs of the metal layer and improve the safety of the battery.

[0019] 2. In the application, the first connecting end extending from the metal layer can be directly used as a tab or connected with an external tab, which solves the welding difficulty problem of the composite current collector and the tab and further improves the connection reliability and electrochemical performance of the composite current collector.

[0020] 3. The structure of the composite current collector is convenient for stacking, and the composite current collector can be made into a thick electrode to improve the energy density. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Here is a schematic diagram of an existing composite current collector;

[0022] Figure 2 This is a schematic diagram of the composite current collector in Embodiment 1 of the present invention;

[0023] Figure 3 This is a schematic diagram of the composite current collector in Embodiment 2 of the present invention.

[0024] In the diagram: 01 - Polymer material layer; 02 - Metal material layer;

[0025] 10-Polymer insulating layer, 11-Second surface, 12-Second extension surface, 13-Second connection end, 20-Metal layer, 21-First surface, 22-First extension surface, 23-First connection end. Detailed Implementation

[0026] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description of the specific embodiments of the composite current collector, battery cell, and lithium battery proposed according to the present invention is provided in conjunction with the accompanying drawings and preferred embodiments.

[0027] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of preferred embodiments with reference to the accompanying drawings. Through the description of the specific embodiments, a more in-depth and specific understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the embodiments and accompanying drawings are for reference and illustration only and are not intended to limit the present invention.

[0028] Example 1

[0029] The composite current collector provided by this invention, such as Figure 2 As shown, the device includes a polymer insulating layer 10 and a metal layer 20. One surface of the polymer insulating layer 10 is bonded to one surface of the metal layer 20. The surface of the metal layer 20 bonded to the polymer insulating layer 10 is a first surface 21, and the surface of the polymer insulating layer 10 bonded to the metal layer 20 is a second surface 11. The first surface 21 extends to the outside of the second surface 11 in a first direction S1. This invention improves the mechanical properties of the current collector by utilizing the polymer insulating layer 10, and by employing a single-sided composite metal layer 20, it reduces cutting burrs on the metal layer 20, improving battery safety. Simultaneously, the first connecting end 23 extending from the metal layer 20 can be directly used as a tab or connected to an external tab, solving the welding difficulty between the composite current collector and the tab, further improving the connection reliability and electrochemical performance of the composite current collector. The structure of this composite current collector is easy to stack, allowing it to be fabricated as a thick electrode, thus increasing energy density.

[0030] In some embodiments, please continue to refer to Figure 2 , the part of the first surface 21 extending to the outside of the second surface 11 is a first extension surface 22, the first extension surface 22 corresponds to the first connecting end 23 of the metal layer 20, and the first connecting end 23 is directly used as a tab. In other embodiments, the part of the first surface 21 extending to the outside of the second surface 11 is a first extension surface 22, the first extension surface 22 corresponds to the first connecting end 23 of the metal layer 20, and the first connecting end 23 is connected with an external tab. Whether the first connecting end 23 is directly used as a tab or connected with an external tab, the problem of difficult welding of the composite current collector and the tab can be solved.

[0031] In some embodiments, the length of the first connecting end 23 along the first direction S1 is 0.3 cm to 10 cm, facilitating the connection or use of the tab.

[0032] In some embodiments, the high polymer insulating layer 10 can be made of one or more monomers of polyethylene terephthalate (PET), polypropylene (PP), polyacrylonitrile (PAN), polyethylene (PE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyamide (PA), polyimide (PI), polyvinyl chloride (PVC), or polystyrene (PS), etc. For example, the high polymer insulating layer 10 can be made of PET monomers, can be polymerized from PET and PVC monomers, or can be composed of PTFE, PA, and PET. In some embodiments, the thickness of the high polymer insulating layer 10 can be 2 to 15 μm, which can play a role in insulation and support.

[0033] In some embodiments, the metal layer 20 can be made of a metal foil or coated on the surface of a non-metal layer (such as a carbon structure layer), and the metal foil can include one or more of aluminum foil, copper foil, nickel foil, titanium foil, silver foil, nickel-copper alloy foil, aluminum-zirconium alloy foil, and stainless steel foil. In some embodiments, the thickness of the metal layer 20 can be 1 to 15 μm. For example, when the metal layer 20 is made of copper, the thickness of the metal layer 20 can be 1 to 12 μm; when the metal layer 20 is made of aluminum, the thickness of the metal layer 20 can be 1 to 15 μm, so as to better achieve the purpose of current collection.

[0034] Embodiment Two

[0035] In some embodiments, please refer to Figure 3In the second direction S2, the second surface 11 extends to the outside of the first surface 21, and the second direction S2 is opposite to the first direction S1. In other words, compared with the case that the first surface 21 is flush with the second surface 11 opposite to the first extension surface 22 in the first embodiment, the form adopted in the second embodiment is that the polymer insulating layer 10 and the metal layer 20 respectively protrude to both ends.

[0036] In some embodiments, please continue to refer to Figure 3 The part of the second surface 11 extending to the outside of the first surface 21 is a second extension surface 12, and the second extension surface 12 corresponds to a second connecting end 13 of the polymer insulating layer 10, and the second connecting end 13 is used for packaging and facilitating the process of the composite current collector in the subsequent steps.

[0037] Embodiment three

[0038] The application further provides a battery cell, which comprises a positive electrode sheet and a negative electrode sheet, the positive electrode sheet is obtained by coating a positive electrode slurry on the composite current collector as described above, and the negative electrode sheet is obtained by coating a negative electrode slurry on the composite current collector as described above, and a diaphragm is arranged between the positive electrode sheet and the negative electrode sheet. The battery cell provided by the application has high safety and high energy density.

[0039] Embodiment four

[0040] The application further provides a lithium battery, which comprises the battery cell as described above. The lithium battery provided by the application has high safety and high energy density.

[0041] In summary, the composite current collector, the battery cell and the lithium battery provided by the application, the composite current collector comprises a polymer insulating layer 10 and a metal layer 20, one side surface of the polymer insulating layer 10 is attached to one side surface of the metal layer 20; the surface of the metal layer 20 attached to the polymer insulating layer 10 is a first surface 21, the surface of the polymer insulating layer 10 attached to the metal layer 20 is a second surface 11, and the first surface 21 extends to the outside of the second surface 11 in a first direction S1. On the one hand, the mechanical properties of the current collector are improved by using the polymer insulating layer 10, and on the other hand, the cutting burr of the metal layer 20 can be reduced by using the single-sided composite metal layer 20, thereby improving the safety of the battery; at the same time, the first connecting end 23 of the metal layer 20 extending out can be directly used as a tab or connected with an external tab, thereby solving the welding difficulty problem of the composite current collector and the tab, further improving the connection reliability and electrochemical performance of the composite current collector; the structure of the composite current collector is convenient for stacking, and the composite current collector can be made into a thick electrode, thereby improving the energy density.

[0042] It should be noted that the foregoing description of the embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments of the application to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the embodiments of the application be limited not with this detailed description, but rather determined from the claims.

[0043] In some embodiments, numerical parameters should consider the prescribed significant digits and use ordinary rounding. Although the numerical ranges and parameters setting forth the broad scope of the embodiments of the application are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, can contain certain errors associated with the standard variation found in their respective testing measurements.

[0044] Finally, it should be understood that the embodiments of the application are illustrative only and not limiting of the scope of the application. Other embodiments of the application within the scope of the following claims can make their appearance and the foregoing description should not be interpreted as limiting the claimed application. Accordingly, all substitutions, modifications and alterations are intended to be considered equivalents of the terms thereof. The disclosures of this patent application are believed to be applicable to embodiments of the application, the scope of which is not limited to what has been presented in this summary section of the release. Other combinations and sub-combinations of features, functions, acts and / or steps disclosed in this patent application may be used in making or carrying out the embodiments of the application. Various changes can be made without departing from the spirit or scope of the application. Therefore, specific embodiments of the application are not to be construed as limiting and the same are believed to be applicable to other features, functions, acts and / or steps of embodiments of the application.

Claims

1. A composite current collector, characterized in that, It consists of a polymer insulating layer and a metal layer, with one side surface of the polymer insulating layer and one side surface of the metal layer attached together; the surface of the metal layer attached to the polymer insulating layer is a first surface, and the surface of the polymer insulating layer attached to the metal layer is a second surface; the first surface extends to the outside of the second surface in a first direction; the portion of the first surface extending to the outside of the second surface is a first extension surface, which corresponds to a first connecting end of the metal layer, and the first connecting end is used as a tab, or the first connecting end is connected to an external tab; In a second direction, the second surface extends to the outside of the first surface, and the second direction is opposite to the first direction; the portion of the second surface extending to the outside of the first surface is a second extension surface, and the second extension surface corresponds to the second connection end of the polymer insulating layer, the second connection end being used for encapsulation.

2. The composite current collector as described in claim 1, characterized in that, The length of the first connecting end along the first direction is 0.3cm to 10cm.

3. The composite current collector as described in claim 1, characterized in that, The polymer insulating layer is made of one or more monomers selected from polyethylene terephthalate, polypropylene, polyacrylonitrile, polyethylene, polytetrafluoroethylene, polyvinylidene fluoride, polyamide, polyimide, polyvinyl chloride, or polystyrene.

4. The composite current collector as described in claim 1 or 3, characterized in that, The thickness of the polymer insulating layer is 2–15 μm.

5. The composite current collector as described in claim 1, characterized in that, The metal layer is made of metal foil or is made by coating the surface of a non-metallic layer with the metal foil, wherein the metal foil includes one or more of aluminum foil, copper foil, nickel foil, titanium foil, silver foil, nickel-copper alloy foil, aluminum-zirconium alloy foil, and stainless steel foil.

6. The composite current collector as described in claim 5, characterized in that, The thickness of the metal layer is 1–15 μm.

7. A battery cell, characterized in that, It includes a positive electrode and a negative electrode, wherein the positive electrode is obtained by coating a positive electrode slurry onto a composite current collector as described in any one of claims 1 to 6, and the negative electrode is obtained by coating a negative electrode slurry onto a composite current collector as described in any one of claims 1 to 6, and a separator is provided between the positive electrode and the negative electrode.

8. A lithium battery, characterized in that, Including the battery cell as described in claim 7.

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