Busbar, battery cell and battery

Abstract

Disclosed are a busbar, a battery cell and a battery. The busbar comprises a busbar body (1) and a surface aluminum layer (2), wherein the busbar body (1) is a copper layer, and the surface aluminum layer (2) covers the outer surface of the busbar body (1).

Description

Busbar, battery cell and battery

[0001] The present application claims priority to Chinese Patent Application No. 202311750512.5, filed on December 18, 2023, and Chinese Patent Application No. 202421568432.8, filed on July 3, 2024, with the Chinese Patent Office, the contents of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a busbar, a battery cell and a battery. BACKGROUND

[0003] The busbar structure is a component of the battery cell and is commonly used in various batteries, such as lithium-ion batteries. In the related art, the busbar is usually laser-welded to the exposed tab of the jelly-roll. The busbar is generally divided into a positive busbar and a negative busbar. SUMMARY

[0004] In the related art, the base material of the busbar is aluminum. The busbar made of aluminum has a high resistance, which results in a high internal resistance of the battery cell and a high internal heat generation of the battery cell. Some busbars are made of other materials with low resistance, but the surface of these busbars is easily corroded by the electrolyte, resulting in performance defects.

[0005] The present application provides a busbar. The busbar includes a busbar body and a surface aluminum layer. The busbar body is a copper layer, and the surface aluminum layer covers the outer surface of the busbar body.

[0006] The present application also provides a battery cell. The battery cell includes the busbar described above.

[0007] The present application also provides a battery. The battery includes the battery cell described above. ADVANTAGEOUS EFFECTS

[0008] The busbar provided by the application, the battery cell and the battery, mainly by changing the busbar body from the aluminum material used in the traditional busbar to the copper material, so as to reduce the internal resistance of the busbar during work, greatly reduce the probability of heat generation of the busbar during work, and then the copper busbar body is coated with a surface aluminum layer on the outer side, so that when the busbar body is welded as part of the battery cell, the high temperature condition generated by welding can be used to make the surface aluminum layer react with oxygen in the air to generate a dense oxide film layer on the welding area of the busbar body. The dense oxide film layer has good corrosion resistance and is not easy to react with electrolyte, so that during the production and working process of the battery cell, the busbar in the battery cell and the electrolyte are in contact, and the electrolyte directly contacts the dense oxide film layer in the welding area, so that the electrolyte is not easy to directly corrode the welding area, thereby improving the corrosion of the welding area of the busbar after welding. BRIEF DESCRIPTION OF DRAWINGS

[0009] Fig. 1 is a cross-sectional structure schematic diagram of the busbar provided by some embodiments of the application;

[0010] Fig. 2 is a structure schematic diagram of the busbar provided by some embodiments of the application;

[0011] Fig. 3 is a cross-sectional schematic diagram of the busbar in Fig. 2;

[0012] Fig. 4 is a structure schematic diagram of the battery cell provided by some embodiments of the application;

[0013] Fig. 5 is a structure schematic diagram of part A in Fig. 4.

[0014] The drawings are described as follows:

[0015] 1, busbar body; 11, liquid inlet hole; 2, surface aluminum layer; 5, winding core; 7, dense oxide film layer. Embodiments of the application

[0016] In the description of the application, it should be understood that the words "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more features. In the description of the application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0017] The busbar is a component for collecting the electrical energy of the battery cell to the powered device to realize power transmission or to deliver the electrical energy to the battery cell when charging the battery cell. The busbar is usually connected with the winding core to form the battery cell.

[0018] The busbar is generally connected with the tab of the core, and the connection mode can be welding. In the related art, laser welding is generally used to ensure welding strength and welding efficiency.

[0019] However, in the related art, the base material of the busbar is aluminum. However, when aluminum is used as the base material of the busbar, the internal resistance of the battery cell is too high, and the internal heat generation of the battery cell is relatively serious. Not only the electric energy is wasted, but also the battery cell can be burned due to abnormal heating, thereby causing the battery to malfunction. Although other materials with low internal resistance can be used to manufacture the busbar in the related art, the surface of the busbar manufactured by most materials with low internal resistance is prone to corrosion with the electrolyte.

[0020] In a first aspect, referring to FIG. 1, which is a schematic diagram of a cross-sectional structure of a busbar provided by an embodiment of the present application, the present application provides a busbar, which includes a busbar body 1 and a surface aluminum layer 2. The busbar body 1 is a copper layer, and the surface aluminum layer 2 covers the outer surface of the busbar body 1.

[0021] It should be understood that the busbar body 1 can be externally covered with the surface aluminum layer 2 in a manner of being attached or being fixed tightly.

[0022] It can be understood that the busbar in the related art is a sheet-shaped object made of aluminum material, and the surface of the busbar is generally not provided with a composite layer structure. Since the busbar made of aluminum material is economical but has high internal resistance, when the busbar is in a working state, the busbar is prone to generate heat when inputting and outputting electric energy due to its own high internal resistance, thereby wasting electric energy and easily burning the components near the busbar, and thereby shortening the service life of the battery cell.

[0023] In the present application, the busbar body 1 is changed from aluminum material to copper material, thereby reducing the internal resistance of the busbar when the busbar is working, and greatly reducing the probability of generating heat when the busbar is working. Then, the copper busbar body 1 is externally covered with the surface aluminum layer 2. When the busbar body 1 is welded to become a part of the battery cell, the high-temperature condition generated by welding can be used to make the surface aluminum layer 2 chemically react with oxygen in the air, thereby generating a dense oxide film layer 7 in the welding area of the busbar. The dense oxide film layer 7 has good corrosion resistance and is not prone to chemical reaction with the electrolyte. Therefore, during the production and working process of the battery cell, the electrolyte directly contacts the dense oxide film layer 7 in the welding area when the busbar in the battery cell contacts the electrolyte, so that the electrolyte is not prone to directly corrode the welding area, thereby improving the corrosion of the welding area of the busbar caused by the contact between the surface of the busbar after welding and the electrolyte.

[0024] In some embodiments of the present application, referring to FIG. 2 and FIG. 3, FIG. 2 is a structural schematic diagram of a busbar provided by an embodiment of the present application, and FIG. 3 is a cross-sectional schematic diagram of the busbar in FIG. 2, which is a positive busbar as an example. The busbar body 1 is provided with a liquid inlet hole 11 on the surface thereof for injecting electrolyte into the inside of the shell of the battery cell. The surface aluminum layer 2 also covers the hole wall of the liquid inlet hole 11.

[0025] It can be understood that, in the production process of the battery cell, the busbar body 1 is plated with an aluminum material layer by electroplating or chemical plating, and then the busbar body 1 plated with the material layer is oxidized under high-temperature conditions generated in the welding process of the winding core to form a dense oxide film layer 7 on the material layer. Then, the busbar is assembled with the shell of the battery cell. After the assembly is completed, electrolyte needs to be injected from the liquid inlet hole 11 provided on the surface of the positive busbar. In the process of injecting the electrolyte, the electrolyte inevitably contacts the liquid inlet hole 11.

[0026] It can be understood that the busbar can be generally divided into a positive busbar and a negative busbar. The positive busbar is generally provided with a liquid inlet hole 11 for injecting electrolyte into the battery cell. Generally, the electrolyte is easy to corrode the liquid inlet hole 11 in the process of injecting the electrolyte. In the present application, when the busbar is a positive busbar, the liquid inlet hole 11 is also coated with a surface aluminum layer 2. A dense oxide film layer 7 is generated on the surface of the surface aluminum layer 2 under high-temperature conditions generated in the welding process. Thus, the liquid inlet hole 11 can resist the corrosion of the electrolyte in the process of injecting the electrolyte.

[0027] It should be noted that, under normal temperature conditions, the surface of the surface aluminum layer 2 reacts with oxygen to generate a thin dense oxide film layer 7. Under high-temperature conditions, the surface aluminum layer 2 reacts rapidly with oxygen to generate a thick dense oxide film layer 7. The high temperature generated by welding can meet the high-temperature conditions. At least part of the surface aluminum layer 2 reacts rapidly with oxygen to generate a dense oxide film layer 7.

[0028] In some embodiments of the present application, the surface aluminum layer 2 is a plating layer.

[0029] It can be understood that the combination between the surface aluminum layer 2 and the busbar body 1 can be a composite structure formed by extruding the surface aluminum layer 2 on the busbar body 1 by extrusion, or can be a plated layer structure formed by plating the surface aluminum layer 2 on the busbar body 1 by electroplating or chemical plating, or can be a thin film deposition structure formed by depositing the surface aluminum layer 2 on the busbar body 1 by thin film deposition. Among them, the plated layer structure formed by plating the surface aluminum layer 2 on the busbar body 1 by electroplating or chemical plating has a more uniform thickness than the composite structure formed by extruding the surface aluminum layer 2 on the busbar body 1 by extrusion, and is more economical and practical than the thin film deposition structure formed by depositing the surface aluminum layer 2 on the busbar body 1 by thin film deposition.

[0030] Exemplarily, the surface aluminum layer 2 can be a chemical plating layer.

[0031] It can be understood that the surface of the busbar body 1 is plated with a plated layer, which can be electroplated as an electroplated layer by electroplating, or can be plated as a chemical plated layer by chemical plating. Since the thickness of the plated layer is small, although the electroplated layer is generated faster than the chemical plated layer by electroplating, the generation effect of the chemical plated layer is more uniform than that of the electroplated layer. Therefore, forming the surface aluminum layer 2 into a chemical plated layer by chemical plating can make the thickness of the surface aluminum layer 2 on the surface of the busbar body 1 uniform, which is more conducive to improving the anti-electrolyte corrosion effect of the surface of the busbar body 1.

[0032] In some embodiments of the present application, the thickness of the busbar body 1 is 0.1 mm to 0.5 mm. Alternatively, the thickness of the busbar body 1 can be 0.15 mm to 0.25 mm, for example, 0.15 mm, 0.20 mm, 0.25 mm, etc. Within this thickness range, the busbar body 1 has better structural strength and stability, thereby ensuring the welding quality of the battery cell formed by welding, while reducing the amount of material used and saving material costs.

[0033] In some embodiments of the present application, the thickness of the surface aluminum layer 2 is 0.3 microns to 3.5 microns, for example, 0.3 microns, 0.5 microns, 0.8 microns, 1 micron, 1.3 microns, 1.6 microns, 2 microns, 2.4 microns, 2.7 microns, 3 microns, 3.2 microns or 3.5 microns, etc. Within this thickness range, the surface aluminum layer 2 has better corrosion resistance and wear resistance, which can effectively prevent the outer surface of the busbar body 1 from being corroded by electrolyte or other media, while reducing the material cost of the surface aluminum layer 2.

[0034] In a second aspect, referring to FIG. 4, which is a structural schematic diagram of a battery cell provided in an embodiment of the present application, specifically, a structural schematic diagram of a battery cell including a negative electrode busbar, the present application further provides a battery cell including the busbar as introduced in any one of the embodiments of the first aspect.

[0035] Since the busbar in the present application can improve the situation that the surface of the busbar body 1 is in contact with the electrolyte during the working process, thereby causing the corrosion of the busbar body 1, i.e., the copper layer, the battery cell including the busbar also has the beneficial effects as described above.

[0036] In some embodiments of the present application, the battery cell includes the winding core 5 and the busbar, and the winding core 5 and the busbar are fixed by welding. In the welding area of the busbar, the surface aluminum layer 2 is oxidized to form the dense oxide film layer 7 during the welding process.

[0037] In the present application, the busbar body 1 is combined with the aluminum material, and the combination can be electroplating, chemical plating, extrusion, etc. The busbar obtained by the combination is subjected to high-temperature conditions generated by welding, so that the surface aluminum layer 2 of the aluminum material generates the dense oxide film layer 7 at least in the welding area. Since the dense oxide film layer 7 has good resistance to electrolyte corrosion, the welding area of the busbar is difficult to be directly corroded during contact with the electrolyte, thereby improving the overall resistance of the busbar to electrolyte corrosion.

[0038] In some embodiments of the present application, referring to FIG. 4 and FIG. 5, which is a structural schematic diagram of part A in FIG. 4 provided in an embodiment of the present application, the winding core 5 and the busbar are fixed by welding.

[0039] In some embodiments of the present application, the battery cell can include the winding core 5 and the busbar. In the related art, the busbar and the winding core 5 are often welded. The welding method can include electric welding and laser welding.

[0040] In some embodiments of the present application, the positive electrode tab of the winding core 5 is an aluminum foil, and the negative electrode tab of the winding core 5 is a copper foil.

[0041] It can be understood that the positive electrode tab of the winding core 5 is an aluminum foil, and the negative electrode tab of the winding core 5 is a copper foil, so that the internal resistance and the heat generation of the busbar are greatly reduced, and the service life of the battery cell can be greatly improved.

[0042] In a third aspect, the present application further provides a battery including the battery cell as introduced in any one of the embodiments of the second aspect.

[0043] Since the surface of the welding area of the battery cell and the busbar in the present application is in contact with the electrolyte after welding, and in the welding area, the surface aluminum layer 2 is oxidized to form a dense corrosion-resistant oxide film layer 7, so as to achieve the purpose that the welding area of the busbar is not easy to be corroded by the electrolyte, and therefore the battery including the battery cell also has the beneficial effects as above.

[0044] As an example, the battery includes at least one of a battery module, a battery pack, and an energy storage container.

Claims

1. A busbar, comprising a busbar body (1) and a surface aluminum layer (2), the busbar body (1) is a copper layer, and the surface aluminum layer (2) covers the outer surface of the busbar body (1).

2. The busbar of claim 1, wherein, The busbar is a positive busbar, the busbar body (1) is provided with a liquid inlet hole (11) on the surface, and the surface aluminum layer (2) also covers the hole wall of the liquid inlet hole (11).

3. The busbar of claim 1, wherein, The surface aluminum layer (2) is a plating layer.

4. The busbar of claim 1, wherein, The thickness of the busbar body (1) is 0.1-0.5 mm.

5. The busbar of claim 1, wherein, The thickness of the surface aluminum layer (2) is 0.3-3.5 μm.

6. The busbar of claim 1, wherein, The surface aluminum layer (2) is combined with the busbar body (1) by extrusion.

7. The busbar of claim 1, wherein, The surface aluminum layer (2) is a plating layer structure plated on the busbar body (1) by electroplating or chemical plating.

8. The busbar of claim 1, wherein, The surface aluminum layer (2) is a thin film deposition structure deposited on the busbar body (1) by thin film deposition.

9. An electric core comprising the busbar according to any one of claims 1-8.

10. The electric cell of claim 9, wherein, The busbar and the tab of the core (5) are welded and fixed, and the surface of the welding area of the busbar is formed with a dense oxide film layer (7) oxidized by at least part of the surface aluminum layer (2).

11. The electric cell of claim 10, wherein, The busbar and the tab of the core (5) are welded and fixed.

12. The electric cell of claim 11, wherein, The positive tab of the core (5) is an aluminum foil, and the negative tab of the core (5) is a copper foil.

13. A battery comprising the electric core according to any one of claims 9-12.

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