Battery cell and electric equipment
By using a negative electrode tab composed of copper-plated nickel sheets and aluminum sheets in the battery cell, combined with an appropriate ratio and sealing design, the problems of insufficient energy density and rate performance of the battery cell are solved, achieving lightweighting and improved reliability of the battery cell.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-16
- Publication Date
- 2026-03-24
AI Technical Summary
The existing battery cells have insufficient mass energy density and rate performance, and the copper-plated nickel material is expensive, dense, and difficult to weld, which affects the weight and reliability of the battery cells and electrical equipment.
The negative electrode tab is composed of a copper-plated nickel sheet and an aluminum sheet. The copper-plated nickel sheet is electrically connected to the negative electrode plate. The end of the aluminum sheet away from the copper-plated nickel sheet extends out of the encapsulation part. The area and thickness of the aluminum sheet are designed to meet a certain ratio range. Combined with the welding of the aluminum sheet and the copper-plated nickel sheet and the setting of the sealing component, the weight of the electrode tab is reduced and the conductivity is improved.
It improves the mass energy density and rate performance of the battery cells, reduces the weight of the battery cells and electrical equipment, enhances welding reliability and reduces the risk of leakage, and extends the service life of the battery cells.
Smart Images
Figure CN121726486A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of battery, in particular to an electric core and an electric device. BACKGROUND
[0002] At present, with the rapid development of new energy technology, the electric core has been widely applied in the fields of electronic devices, electric vehicles, electric two-wheel vehicles, electric tools and the like. With the more and more wide application of the electric core, higher requirements are put forward for the quality energy density of the electric core. SUMMARY
[0003] The present application provides an electric core and an electric device, which can improve the rate performance and the quality energy density of the electric core.
[0004] In a first aspect, the present application provides an electric core, which comprises a packaging bag, an electrode assembly and a negative electrode tab. The packaging bag comprises a main body part and a sealing part. The electrode assembly is accommodated in the main body part, and the electrode assembly comprises a positive electrode tab and a negative electrode tab. The negative electrode tab comprises a copper-nickel plated sheet and an aluminum sheet. In a first direction, one end of the copper-nickel plated sheet is electrically connected to the negative electrode tab, the other end of the copper-nickel plated sheet is welded to the aluminum sheet, and one end of the aluminum sheet away from the copper-nickel plated sheet protrudes out of the sealing part. The cross-sectional area of the copper-nickel plated sheet perpendicular to the first direction is S1, and the cross-sectional area of the aluminum sheet perpendicular to the first direction is S2, and 1.6≤S2 / S1≤3.3.
[0005] In the above technical solution, since the density of aluminum is smaller than that of copper, compared with the negative electrode tab prepared by the copper-nickel plated sheet as a whole, by making the negative electrode tab comprise the copper-nickel plated sheet and the aluminum sheet, in the first direction, one end of the copper-nickel plated sheet is electrically connected to the negative electrode tab, the other end of the copper-nickel plated sheet is welded to the aluminum sheet, and one end of the aluminum sheet away from the copper-nickel plated sheet protrudes out of the sealing part, the weight of the negative electrode tab can be reduced, which is conducive to improving the quality energy density of the electric core. In addition, the components for connecting with the negative electrode tab in the electric device can also be made of aluminum material, which can reduce the weight of the electric device, and the aluminum material has lower welding difficulty and higher welding reliability.
[0006] When S2 / S1 is greater than or equal to 1.6, the conductive capacity of the aluminum sheet can be not lower than that of the copper-nickel plated sheet, so that the conductive capacities of the aluminum sheet and the copper-nickel plated sheet are matched, and then the internal resistance of the electric core is smaller, which is conducive to improving the rate performance of the electric core. When S2 / S1 is less than or equal to 3.3, the weight of the aluminum sheet is smaller than that of the copper-nickel plated sheet, so that the weight of the electric core is reduced, which is conducive to improving the quality energy density of the electric core. Therefore, when 1.6≤S2 / S1≤3.3, the conductive capacities of the aluminum sheet and the copper-nickel plated sheet are matched, and then the internal resistance of the electric core is smaller, which is conducive to improving the rate performance of the electric core, and the weight of the electric core is reduced, which is conducive to improving the quality energy density of the electric core.
[0007] In some embodiments of the present application, 1.6≤S2 / S1≤1.9.
[0008] In the above technical solution, when S2 / S1 is greater than or equal to 1.6, the conductive ability of the aluminum sheet can be made not lower than that of the copper-nickel-plated sheet, so that the conductive abilities of the aluminum sheet and the copper-nickel-plated sheet are matched, thereby making the internal resistance of the battery cell smaller, which is beneficial to improving the rate performance of the battery cell; when S2 / S1 is less than or equal to 1.9, the weight of the aluminum sheet can be further made smaller than that of the copper-nickel-plated sheet, thereby further playing a role in reducing the weight of the battery cell, which is beneficial to further improving the mass energy density of the battery cell; therefore, when 1.6≤S2 / S1≤1.9, the conductive abilities of the aluminum sheet and the copper-nickel-plated sheet can be matched, thereby making the internal resistance of the battery cell smaller, which is beneficial to improving the rate performance of the battery cell, and the weight of the battery cell can be further reduced, which is beneficial to further improving the mass energy density of the battery cell.
[0009] In some embodiments of the present application, the battery cell comprises a sealing member, the sealing member is arranged between the negative tab and the packaging portion. The copper-nickel-plated sheet and the aluminum sheet are welded to form a welded area, and along the first direction, the welded area is located on the side of the sealing member away from the electrode assembly.
[0010] In the above technical solution, by arranging the sealing member between the negative tab and the packaging portion, the sealing between the negative tab and the packaging portion can be achieved, and the risk of liquid leakage of the battery cell is reduced. By arranging the welded area on the side of the sealing member away from the electrode assembly along the first direction, the aluminum sheet is located outside the packaging bag, the risk of contact failure of the aluminum sheet with the electrolyte in the packaging bag is reduced, and the service life of the battery cell is prolonged.
[0011] In some embodiments of the present application, the battery cell comprises a sealing member, the sealing member is arranged between the negative tab and the packaging portion. The copper-nickel-plated sheet and the aluminum sheet are welded to form a welded area, and the sealing member covers at least part of the welded area.
[0012] In the above technical solution, by arranging the sealing member between the negative tab and the packaging portion, the sealing between the negative tab and the packaging portion can be achieved, and the risk of liquid leakage of the battery cell is reduced. By arranging the sealing member to cover at least part of the welded area, the sealing member can play a protective role on the welded area, the risk of the copper-nickel-plated sheet or the aluminum sheet being separated from the welded area due to stress is reduced, and the service life of the battery cell is prolonged.
[0013] In some embodiments of the present application, along the first direction, the aluminum sheet has a first edge close to the electrode assembly, and along the thickness direction of the negative tab, the sealing member covers the first edge.
[0014] In the above technical solution, by making the seal cover the first edge along the thickness direction of the negative electrode tab, the seal covers the part of the aluminum sheet located inside the packaging bag, reducing the risk of contact failure between the aluminum sheet and the electrolyte inside the packaging bag, which is beneficial to extending the service life of the battery cell.
[0015] In some embodiments of this application, the thickness of the copper-plated nickel sheet is H1, where 0.1 mm ≤ H1 ≤ 2 mm.
[0016] In the above technical solution, when H1 is greater than or equal to 0.1mm, the thickness of the copper-plated nickel sheet is not too small, the current-carrying area of the copper-plated nickel sheet is not too small, and the conductivity of the copper-plated nickel sheet is strong, which can reduce the internal resistance of the battery cell and is beneficial to improving the rate performance of the battery cell. When H1 is less than or equal to 2mm, the thickness of the copper-plated nickel sheet is not too large, the space occupied by the copper-plated nickel sheet is reduced, which is beneficial to improving the energy density of the battery cell. Therefore, when 0.1mm≤H1≤2mm, the conductivity of the copper-plated nickel sheet is strong, which can reduce the internal resistance of the battery cell and is beneficial to improving the rate performance of the battery cell. At the same time, the space occupied by the copper-plated nickel sheet is reduced, which is beneficial to improving the energy density of the battery cell.
[0017] In some embodiments of this application, the thickness of the aluminum sheet is H2, where 0.1mm ≤ H2 ≤ 2mm.
[0018] In the above technical solution, when H2 is greater than or equal to 0.1mm, the thickness of the aluminum sheet is not too small, the current-carrying area of the aluminum sheet is not too small, the conductivity of the aluminum sheet is strong, which can reduce the internal resistance of the battery cell and is beneficial to improving the rate performance of the battery cell. When H2 is less than or equal to 2mm, the thickness of the aluminum sheet is not too large, the space occupied by the aluminum sheet is reduced, which is beneficial to improving the energy density of the battery cell. Therefore, when 0.1mm≤H2≤2mm, the conductivity of the aluminum sheet is strong, the internal resistance of the battery cell is reduced, which is beneficial to improving the rate performance of the battery cell, and the space occupied by the aluminum sheet is reduced, which is beneficial to improving the energy density of the battery cell.
[0019] In some embodiments of this application, along the second direction, the width of the copper-plated nickel sheet is W1, and the width of the aluminum sheet is W2, where W2 ≥ W1. The first direction, the second direction, and the thickness direction of the negative electrode tab are perpendicular to each other.
[0020] In the above technical solution, since the current carrying capacity of aluminum is less than that of copper, by making the width of the aluminum sheet greater than or equal to that of the copper-plated nickel sheet along the second direction, the current-carrying area of the aluminum sheet can be increased, so that the conductivity of the aluminum sheet and the copper-plated nickel sheet are matched, thereby making the internal resistance of the battery cell smaller and improving the rate performance of the battery cell. In some embodiments of this application, along the thickness direction of the negative electrode tab, a portion of the copper-plated nickel sheet overlaps and is welded with a portion of the aluminum sheet, and the area of the overlapping portion of the copper-plated nickel sheet and the aluminum sheet is S3, where 1.6≤S3 / S1≤3.3.
[0021] In the above technical solution, along the thickness direction of the negative electrode tab, the portion of the copper-plated nickel sheet overlaps and is welded with the portion of the aluminum sheet, so that the current is transmitted between the copper-plated nickel sheet and the aluminum sheet through the overlapping portion of the copper-plated nickel sheet and the aluminum sheet. At this time, the overcurrent area on the aluminum sheet is S3. When S3 / S1 is greater than or equal to 1.6, the conductivity of the overlapping portion of the aluminum sheet and the nickel-plated copper sheet is not lower than that of the nickel-plated copper sheet, ensuring that the conductivity of the overlapping portion matches that of the nickel-plated copper sheet. This results in a lower internal resistance of the battery cell, which is beneficial for improving the rate performance of the battery cell. When S3 / S1 is less than or equal to 3.3, the length of the nickel-plated copper sheet and / or aluminum sheet along the first direction remains unchanged, resulting in a lower weight of the nickel-plated copper sheet and / or aluminum sheet. This reduces the weight of the battery cell and is beneficial for improving the mass energy density of the battery cell. Therefore, when 1.6≤S3 / S1≤3.3, the conductivity of the aluminum sheet and the nickel-plated copper sheet is matched, resulting in a lower internal resistance of the battery cell, which is beneficial for improving the rate performance of the battery cell. It also reduces the weight of the battery cell, which is beneficial for improving the mass energy density of the battery cell.
[0022] In some embodiments of this application, the width of the copper-plated nickel sheet gradually decreases along the second direction, away from the aluminum sheet, in the first direction. S1 is the maximum cross-sectional area of the copper-plated nickel sheet. The first direction, the second direction, and the thickness direction of the negative electrode tab are perpendicular to each other.
[0023] In the above technical solution, by making the width of the copper-plated nickel sheet gradually decrease along the second direction in the first direction and away from the aluminum sheet, the volume and weight of the copper-plated nickel sheet can be reduced, thereby further reducing the weight of the negative electrode tab, which can reduce the weight of the battery cell and is beneficial to improving the mass energy density of the battery cell.
[0024] In some embodiments of this application, along a first direction, the copper-plated nickel sheet has a second edge close to the aluminum sheet and a third edge away from the aluminum sheet, the length of the second edge is L1, the length of the third edge is L2, and 1 < L1 / L2 ≤ 1.6.
[0025] In the above technical solution, by ensuring that 1 < L1 / L2 ≤ 1.6, the length of the third edge is not too small, and the cross-sectional area of the copper-plated nickel sheet at the third edge perpendicular to the first direction is not too small, which can reduce the internal resistance of the battery cell and improve the rate performance of the battery cell.
[0026] Secondly, this application provides an electrical device including a battery cell as described above, the battery cell being used to provide electrical energy. Attached Figure Description
[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings.
[0028] Figure 1 A three-dimensional structural schematic diagram of a battery cell provided in some embodiments of this application; Figure 2 Cross-sectional views of the battery cell provided in some embodiments of this application; Figure 3 A schematic diagram from one perspective of a portion of the structure of a battery cell provided in some embodiments of this application; Figure 4 A schematic diagram from another perspective of a portion of the battery cell structure provided in some embodiments of this application; Figure 5 Schematic diagram of a partial structure of a battery cell provided in other embodiments of this application; Figure 6 This is a schematic diagram of a partial structure of a battery cell provided in some other embodiments of this application.
[0029] Icons: 10-cell; 100-electrode assembly; 110-positive electrode sheet; 120-negative electrode sheet; 200-packaging bag; 210-body section; 220-encapsulation section; 300-negative electrode tab; 310-copper-plated nickel sheet; 310a-welding area; 311-second edge; 312-third edge; 320-aluminum sheet; 321-first edge; 400-sealant; 500-positive electrode tab; X-first direction; Y-thickness direction of negative electrode tab; Z-second direction. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.
[0031] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having" and any variations thereof in the specification, claims and foregoing description of the drawings are intended to cover non-exclusive inclusion.
[0032] The terms "first," "second," etc., in the specification, claims, or the accompanying drawings of this application are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.
[0033] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.
[0034] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.
[0035] With the development of the new energy industry, batteries are gradually moving towards higher energy density and higher power density, and the requirements for battery mass energy density are becoming increasingly stringent. Currently, the negative electrode current collector in the electrode assembly is usually made of copper foil, and the negative electrode tab is made of nickel-plated copper to facilitate welding with the negative electrode current collector. Nickel-plated copper has a high density, which affects the mass energy density of the battery cell, and it is also more expensive. Furthermore, to facilitate welding the negative electrode tab to components in electrical equipment (such as metal busbars and metal wires), these components also need to be made of copper, increasing the weight of the electrical equipment. Additionally, welding copper is more difficult and has lower reliability.
[0036] To improve the mass energy density of a battery cell, this application provides a battery cell comprising a packaging bag, an electrode assembly, and a negative electrode tab. The packaging bag includes a main body and a packaging section. The electrode assembly is housed within the main body and includes a positive electrode and a negative electrode. The negative electrode tab includes a nickel-plated copper sheet and an aluminum sheet. Along a first direction, one end of the nickel-plated copper sheet is electrically connected to the negative electrode, and the other end of the nickel-plated copper sheet is welded to the aluminum sheet. The end of the aluminum sheet away from the nickel-plated copper sheet extends out of the packaging section. The cross-sectional area of the nickel-plated copper sheet perpendicular to the first direction is S1, and the cross-sectional area of the aluminum sheet perpendicular to the first direction is S2, where 1.6 ≤ S2 / S1 ≤ 3.3.
[0037] In this type of battery cell, because the density of aluminum is lower than that of copper, compared to a negative electrode tab made entirely of copper-plated nickel sheets, this application reduces the weight of the negative electrode tab by having the negative electrode tab comprise both a copper-plated nickel sheet and an aluminum sheet. Along a first direction, one end of the copper-plated nickel sheet is electrically connected to the negative electrode plate, and the other end of the copper-plated nickel sheet is welded to the aluminum sheet. The end of the aluminum sheet away from the copper-plated nickel sheet extends out of the encapsulation portion. This reduces the weight of the negative electrode tab and improves the mass energy density of the battery cell. Furthermore, components in electrical equipment used to connect to the negative electrode tab can also be made of aluminum, reducing the weight of the equipment. Aluminum is also easier to weld and has higher welding reliability. When S2 / S1 is greater than or equal to 1.6, the conductivity of the aluminum sheet is not lower than that of the nickel-plated copper sheet, ensuring a match between their conductivity and resulting in lower internal resistance of the battery cell, which is beneficial for improving the rate performance of the battery cell. When S2 / S1 is less than or equal to 3.3, the weight of the aluminum sheet is less than that of the nickel-plated copper sheet, thus reducing the weight of the battery cell and improving its mass energy density. Therefore, when 1.6 ≤ S2 / S1 ≤ 3.3, both the conductivity of the aluminum sheet and the nickel-plated copper sheet are matched, resulting in lower internal resistance of the battery cell and improved rate performance, and the weight of the battery cell is reduced, which is beneficial for improving its mass energy density.
[0038] In other embodiments, the negative electrode sheet includes multiple die-cut or welded negative electrode tabs. After the negative electrode sheet is wound into an electrode assembly, the multiple negative electrode tabs can be stacked in the thickness direction of the electrode assembly and welded or glued together to form a tab bundle. Then, along the first direction, one end of the copper-plated nickel sheet is electrically connected to the tab bundle, and the other end of the copper-plated nickel sheet is welded to an aluminum sheet. The end of the aluminum sheet away from the copper-plated nickel sheet extends out of the encapsulation portion. In other embodiments, the positive electrode sheet can also adopt this arrangement, which will not be described in detail here.
[0039] The battery cell provided in this application embodiment can be a secondary battery, such as a lithium-ion battery, sodium-ion battery, or magnesium-ion battery, etc., and this application embodiment is not limited in this respect. The battery cell can be cylindrical, flat, cuboid, or other shapes, etc., and this application embodiment is not limited in this respect either.
[0040] This application provides an electrical device that uses battery cells as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc.
[0041] See Figure 1 and Figure 2 , Figure 1 A three-dimensional structural schematic diagram of a battery cell provided in some embodiments of this application; Figure 2 Cross-sectional views of battery cells provided for some embodiments of this application.
[0042] This application provides a battery cell 10, which includes an electrode assembly 100, a packaging bag 200, and an electrolyte. The electrode assembly 100 and the electrolyte are contained within the packaging bag 200. The electrode assembly 100 also includes a positive electrode 110, a negative electrode 120, and a separator. The battery cell 10 mainly operates by the movement of metal ions between the positive electrode 110 and the negative electrode 120. The positive electrode 110 includes a positive current collector and a positive active material layer, with the positive active material layer coated on the surface of the positive current collector. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary materials (such as lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, etc.), or lithium manganese oxide, etc. The negative electrode 120 includes a negative current collector and a negative active material layer, with the negative active material layer coated on the surface of the negative current collector. The material of the negative current collector can be copper, and the negative active material can be carbon material or silicon material, etc. The separator can be made of polypropylene (PP) or polyethylene (PE), etc. The electrolyte can include organic solvents, lithium salts, etc.
[0043] In some embodiments, the packaging bag 200 may be made of a flexible material, such as aluminum-plastic film, steel-plastic film, etc.
[0044] See Figures 1 to 4 , Figure 3 A schematic diagram from one perspective of a portion of the structure of a battery cell provided in some embodiments of this application; Figure 4 This is a schematic diagram of a portion of the battery cell structure provided in some embodiments of this application from another perspective.
[0045] In some embodiments, the packaging bag 200 includes a main body 210 and a packaging portion 220. An electrode assembly 100 is housed within the main body 210 and includes a positive electrode 110 and a negative electrode 120. The battery cell 10 includes a negative electrode tab 300, which includes a copper-plated nickel sheet 310 and an aluminum sheet 320. Along a first direction X, one end of the copper-plated nickel sheet 310 is electrically connected to the negative electrode 120, and the other end of the copper-plated nickel sheet 310 is welded to the aluminum sheet 320. The end of the aluminum sheet 320 away from the copper-plated nickel sheet 310 extends out of the packaging portion 220.
[0046] Because aluminum has a lower density than copper, compared to a negative electrode tab 300 entirely made of a copper-plated nickel sheet 310, this application reduces the weight of the negative electrode tab 300 by including a copper-plated nickel sheet 310 and an aluminum sheet 320. Along the first direction X, one end of the copper-plated nickel sheet 310 is electrically connected to the negative electrode plate 120, and the other end of the copper-plated nickel sheet 310 is welded to the aluminum sheet 320. The end of the aluminum sheet 320 away from the copper-plated nickel sheet 310 extends out of the encapsulation portion 220. This reduces the weight of the negative electrode tab 300 and helps improve the mass energy density of the battery cell 10. Furthermore, components in the electrical equipment used to connect to the negative electrode tab 300 can also be made of aluminum, reducing the weight of the electrical equipment. Aluminum is also easier to weld and has higher welding reliability.
[0047] Since copper sheet and aluminum sheet 320 are difficult to weld directly, by plating a nickel coating on the copper sheet to form a copper-nickel plated sheet 310, it is easier to weld the copper-nickel plated sheet 310 and aluminum sheet 320, so that the connection between the copper-nickel plated sheet 310 and aluminum sheet 320 is more reliable.
[0048] In some embodiments, the cross-sectional area of the copper-plated nickel sheet 310 perpendicular to the first direction X is S1, and the cross-sectional area of the aluminum sheet 320 perpendicular to the first direction X is S2, where 1.6 ≤ S2 / S1 ≤ 3.3. For example, S2 / S1 can be 1.6, 1.8, 2, 2.3, 2.5, 2.7, 3, 3.1, or 3.3, or any range of values formed by any two of the above values.
[0049] Where S1 = W1 × H1, S2 = W2 × H2.
[0050] When S2 / S1 is greater than or equal to 1.6, the conductivity of the aluminum sheet 320 is not lower than that of the copper-plated nickel sheet 310, ensuring a match between their conductivity. This results in a lower internal resistance for the battery cell 10, which is beneficial for improving its rate performance. When S2 / S1 is less than or equal to 3.3, the weight of the aluminum sheet 320 is less than that of the copper-plated nickel sheet 310, thus reducing the weight of the battery cell 10 and improving its mass energy density. Therefore, when 1.6 ≤ S2 / S1 ≤ 3.3, the conductivity of the aluminum sheet 320 and the copper-plated nickel sheet 310 is matched, resulting in a lower internal resistance for the battery cell 10 and improving its rate performance. This also reduces the weight of the battery cell 10 and improves its mass energy density.
[0051] Since the thickness of the nickel plating layer in the copper-nickel plated sheet 310 is very small compared to the size of the copper body, this application can ignore the nickel plating layer when calculating the conductivity of the copper-nickel plated sheet 310, and directly use the material properties of copper as the calculation standard for the conductivity of the copper-nickel plated sheet 310.
[0052] The current carrying capacity of copper material is 5 A / mm 2 The current carrying capacity of aluminum material is 8 A / mm. 2 When 5 A / mm 2 ×S2≥8A / mm 2 ×S1 enables the aluminum sheet 320 to have a conductivity greater than or equal to that of the copper-plated nickel sheet 310, i.e., S2 / S1≥1.6.
[0053] The density of copper is 8.96 g / cm³. 3 The density of aluminum is 2.7 g / cm³. 3 Along the first direction X, the length of the aluminum sheet 320 is L1, when 2.7 g / cm 3 ×S2×L1≤8.96 g / cm 3 ×S1×L1 enables the aluminum sheet 320 to weigh less than the copper-plated nickel sheet 310 of the same length that it replaces, i.e., S2 / S1≤3.3.
[0054] In some embodiments, 1.6 ≤ S2 / S1 ≤ 1.9. For example, S2 / S1 can be 1.6, 1.62, 1.65, 1.68, 1.7, 1.72, 1.75, 1.78, 1.8, 1.82, 1.85, 1.87 or 1.9, or a range of values consisting of any two of the above values.
[0055] When S2 / S1 is greater than or equal to 1.6, the conductivity of the aluminum sheet 320 is not lower than that of the copper-plated nickel sheet 310, ensuring a match between their conductivity. This results in a lower internal resistance for the battery cell 10, which is beneficial for improving its rate performance. When S2 / S1 is less than or equal to 1.9, the weight of the aluminum sheet 320 is less than that of the copper-plated nickel sheet 310, further reducing the weight of the battery cell 10 and improving its mass energy density. Therefore, when 1.6 ≤ S2 / S1 ≤ 1.9, the conductivity of the aluminum sheet 320 and the copper-plated nickel sheet 310 is matched, resulting in a lower internal resistance for the battery cell 10 and improving its rate performance. This also further reduces the weight of the battery cell 10, further improving its mass energy density.
[0056] In some embodiments, the battery cell 10 includes a seal 400 disposed between the negative electrode tab 300 and the encapsulation portion 220. A copper-plated nickel sheet 310 and an aluminum sheet 320 are welded to form a weld area 310a, and the seal 400 covers at least a portion of the weld area 310a.
[0057] By positioning the seal 400 between the negative electrode tab 300 and the encapsulation portion 220, a seal can be achieved between the negative electrode tab 300 and the encapsulation portion 220, reducing the risk of leakage from the battery cell 10. By covering at least a portion of the solder area 310a with the seal 400, the seal 400 can protect the solder area 310a, reducing the risk of the copper-plated nickel sheet 310 or aluminum sheet 320 separating from the solder area 310a under stress, thus extending the service life of the battery cell 10.
[0058] In some embodiments, along the first direction X, the aluminum sheet 320 has a first edge 321 close to the electrode assembly 100, and along the thickness direction Y of the negative electrode tab, the seal 400 covers the first edge 321.
[0059] By making the seal 400 cover the first edge 321 along the thickness direction Y of the negative electrode tab, the seal 400 covers the portion of the aluminum sheet 320 located inside the packaging bag 200, reducing the risk of the aluminum sheet 320 failing due to contact with the electrolyte inside the packaging bag 200, which is beneficial to extending the service life of the battery cell 10.
[0060] See Figure 5 , Figure 5 This is a schematic diagram of a partial structure of a battery cell provided in some other embodiments of this application.
[0061] In other embodiments, the battery cell 10 includes a seal 400 disposed between the negative electrode tab 300 and the encapsulation portion 220. A copper-plated nickel sheet 310 and an aluminum sheet 320 are welded to form a welding area 310a, which is located on the side of the seal 400 away from the electrode assembly 100 along the first direction X.
[0062] By positioning the seal 400 between the negative electrode tab 300 and the encapsulation portion 220, a seal between the negative electrode tab 300 and the encapsulation portion 220 can be achieved, reducing the risk of leakage from the battery cell 10. During the charging and discharging process of the battery cell 10, the voltage at the negative electrode tab 300 is low; if the aluminum sheet 320 comes into contact with the electrolyte, a chemical reaction will occur, causing the aluminum sheet 320 to corrode and fail. By positioning the welding area 310a along the first direction X on the side of the seal 400 away from the electrode assembly 100, the aluminum sheet 320 is positioned outside the packaging bag 200, reducing the risk of the aluminum sheet 320 failing due to contact with the electrolyte inside the packaging bag 200, thus extending the service life of the battery cell 10.
[0063] See Figure 4In some embodiments, the thickness of the copper-plated nickel sheet 310 is H1, where 0.1 mm ≤ H1 ≤ 2 mm. For example, H1 can be 0.1 mm, 0.2 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.7 mm, or 2 mm, or any range of two of the above values.
[0064] When H1 is greater than or equal to 0.1 mm, the thickness of the copper-plated nickel sheet 310 is not too small, the current-carrying area of the copper-plated nickel sheet 310 is not too small, and the conductivity of the copper-plated nickel sheet 310 is strong, which can reduce the internal resistance of the battery cell 10 and is beneficial to improving the rate performance of the battery cell 10. When H1 is less than or equal to 2 mm, the thickness of the copper-plated nickel sheet 310 is not too large, and the space occupied by the copper-plated nickel sheet 310 is reduced, which is beneficial to improving the energy density of the battery cell 10. Therefore, when 0.1 mm ≤ H1 ≤ 2 mm, the conductivity of the copper-plated nickel sheet 310 is strong, the internal resistance of the battery cell 10 is reduced, which is beneficial to improving the rate performance of the battery cell 10, and the space occupied by the copper-plated nickel sheet 310 is reduced, which is beneficial to improving the energy density of the battery cell 10.
[0065] In some embodiments, the thickness of the aluminum sheet 320 is H2, where 0.1mm ≤ H2 ≤ 2mm. For example, H2 can be 0.1mm, 0.2mm, 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.7mm, or 2mm, or any range of two of the above values.
[0066] When H2 is greater than or equal to 0.1 mm, the thickness of the aluminum sheet 320 is not too small, the current-carrying area of the aluminum sheet 320 is not too small, and the conductivity of the aluminum sheet 320 is strong, which can reduce the internal resistance of the battery cell 10 and improve the rate performance of the battery cell 10. When H2 is less than or equal to 2 mm, the thickness of the aluminum sheet 320 is not too large, and the space occupied by the aluminum sheet 320 is reduced, which is beneficial to improving the energy density of the battery cell 10. Therefore, when 0.1 mm ≤ H2 ≤ 2 mm, the conductivity of the aluminum sheet 320 is strong, which can reduce the internal resistance of the battery cell 10 and improve the rate performance of the battery cell 10, and the space occupied by the aluminum sheet 320 can also be reduced, which is beneficial to improving the energy density of the battery cell 10.
[0067] See Figure 3 In some embodiments, along the second direction Z, the width of the copper-plated nickel sheet 310 is W1, and the width of the aluminum sheet 320 is W2, where W2 ≥ W1. The first direction X, the second direction Z, and the thickness direction Y of the negative electrode tab are all perpendicular to each other. For example, W2 can be W1, 1.1W1, 1.2W1, 1.3W1, 1.4W1, 1.5W1, 1.6W1, 1.7W1, 1.8W1, 1.9W1, or 2W1, or a range of values formed by any two of the above values.
[0068] Since aluminum has a lower current-carrying capacity than copper, by making the width of the aluminum sheet 320 along the second direction Z greater than or equal to that of the copper-plated nickel sheet 310, the current-carrying area of the aluminum sheet 320 can be increased, so that the conductivity of the aluminum sheet 320 and the copper-plated nickel sheet 310 are matched, thereby making the internal resistance of the cell 10 smaller, which is beneficial to improving the rate performance of the cell 10. In some embodiments, along the thickness direction Y of the negative electrode tab, a portion of the copper-plated nickel sheet 310 overlaps and is welded to a portion of the aluminum sheet 320. The area of the overlapping portion of the copper-plated nickel sheet 310 and the aluminum sheet 320 is S3, where 1.6 ≤ S3 / S1 ≤ 3.3. For example, S3 / S1 can be 1.6, 1.8, 2, 2.3, 2.5, 2.7, 3, 3.1, or 3.3, or any range of values formed by any two of the above values.
[0069] Along the thickness direction Y of the negative electrode tab, a portion of the copper-plated nickel sheet 310 overlaps and is welded to a portion of the aluminum sheet 320, allowing current to flow between the copper-plated nickel sheet 310 and the aluminum sheet 320 through the overlapping portion. At this time, the current-carrying area on the aluminum sheet 320 is S3. When S3 / S1 is greater than or equal to 1.6, the conductivity of the overlapping portion of the aluminum sheet 320 and the copper-plated nickel sheet 310 is not less than the conductivity of the copper-plated nickel sheet 310, ensuring a conductivity match between the aluminum sheet 320 and the copper-plated nickel sheet 310. This results in a lower internal resistance for the battery cell 10, which is beneficial for improving the rate performance of the battery cell 10. When S3 / S1 is less than or equal to 3.3, the length of the negative electrode tab 300 along the first direction X remains constant, while the length of the copper-plated nickel sheet 310 and / or the aluminum sheet 320 along the first direction X is smaller. This results in a smaller weight for the copper-nickel plated sheet 310 and / or aluminum sheet 320, thereby reducing the weight of the battery cell 10 and improving its mass energy density. Therefore, when 1.6 ≤ S3 / S1 ≤ 3.3, the overlapping portion of the aluminum sheet 320 and the copper-nickel plated sheet 310 can be matched with the conductivity of the copper-nickel plated sheet 310, resulting in a smaller internal resistance of the battery cell 10, which is beneficial for improving the rate performance of the battery cell 10. It also reduces the weight of the battery cell 10 and improves its mass energy density.
[0070] See Figure 6 , Figure 6 This is a schematic diagram of a partial structure of a battery cell provided in some other embodiments of this application.
[0071] In other embodiments, the width of the copper-plated nickel sheet 310 gradually decreases along the second direction Z, in the first direction X and away from the aluminum sheet 320. S1 is the maximum cross-sectional area of the copper-plated nickel sheet 310. The first direction X, the second direction Z, and the thickness direction Y of the negative electrode tab are all perpendicular to each other.
[0072] By making the width of the copper-plated nickel sheet 310 gradually decrease along the second direction Z in the direction away from the aluminum sheet 320 in the first direction X, the volume and weight of the copper-plated nickel sheet 310 can be reduced, thereby further reducing the weight of the negative electrode tab 300, which can reduce the weight of the battery cell 10 and is beneficial to improving the mass energy density of the battery cell 10.
[0073] In some embodiments, along the first direction X, the copper-plated nickel sheet 310 has a second edge 311 close to the aluminum sheet 320 and a third edge 312 away from the aluminum sheet 320. The length of the second edge 311 is L1, and the length of the third edge 312 is L2, where 1 < L1 / L2 ≤ 1.6. For example, L1 / L2 can be 1.01, 1.02, 1.05, 1.08, 1.1, 1.2, 1.3, 1.4, 1.5, or 1.6, or a range of values consisting of any two of the above values.
[0074] By ensuring that 1 < L1 / L2 ≤ 1.6, the length of the third edge 312 is not too small, and the cross-sectional area of the copper-plated nickel sheet 310 at the third edge 312 perpendicular to the first direction X is not too small. This reduces the internal resistance of the cell 10 and is beneficial to improving the rate performance of the cell 10.
[0075] See Figure 1 and Figure 2 In some embodiments, the battery cell 10 includes a positive electrode tab 500, which is made of aluminum. Along the first direction X, one end of the positive electrode tab 500 is electrically connected to the positive electrode plate 110, and the other end of the positive electrode tab 500 extends out of the encapsulation portion 220.
[0076] During the charging and discharging process of cell 10, the voltage at the positive electrode tab 500 is relatively high, and an aluminum oxide layer can be formed on the surface of the positive electrode tab 500, which plays a protective role for the positive electrode tab 500 and is less likely to produce a chemical reaction when in contact with the electrolyte.
[0077] Referring to Table 1, H1 is the thickness of the copper-nickel plated sheet 310; W1 is the width of the copper-nickel plated sheet 310; H2 is the thickness of the aluminum sheet 320; W2 is the width of the aluminum sheet 320; S1 is the cross-sectional area of the copper-nickel plated sheet 310 perpendicular to the first direction X; S2 is the cross-sectional area of the aluminum sheet 320 perpendicular to the first direction X; S3 is the area of the overlapping portion of the copper-nickel plated sheet 310 and the aluminum sheet 320 along the thickness direction Y of the negative electrode tab. The negative electrode tabs (i.e., tab-leads) of Comparative Example 1 are all copper-nickel plated sheets. The negative electrode tabs (i.e., tab-leads) of Comparative Examples 2-3 and Examples 1-8 all include a portion of copper-nickel plated sheets and another portion of aluminum sheets. The difference lies in the parameter changes in Table 1. The test data of Comparative Examples 1-3 and Examples 1-8 are listed in Table 1. Table 1 uses the tab-lead weight G0 of the battery cell in Comparative Example 1 as the benchmark. The tab-lead weight of the battery cell in other comparative examples and embodiments is G. The battery cell tab-lead weight ratio is (G-G0) / G0.
[0078] Table 1 Weight and internal resistance test of battery cell tab-lead
[0079] Methods for testing the internal resistance of battery cells: 1. Use the Xinwei CTE-4008D-5V30A charging and discharging equipment to adjust the cell voltage to 50% SOC; 2. The internal resistance of the battery cell was tested using a JK2520B battery internal resistance tester.
[0080] Based on Table 1, the following conclusions can be drawn: (1) Referring to Comparative Examples 1-3 and Examples 1-6, the negative electrode tab 300 is entirely made of copper-plated nickel sheet 310, which makes the negative electrode tab 300 heavy and affects the mass energy density of the battery cell 10. In this application, the negative electrode tab 300 includes a copper-plated nickel sheet 310 and an aluminum sheet 320. When S2 / S1 is greater than 3.3, the cross-sectional area of the aluminum sheet 320 is too large, causing the weight of the aluminum sheet 320 to exceed the weight of the copper-plated nickel sheet 310 of the same length that it replaces. This still results in a heavy negative electrode tab 300 and affects the mass energy density of the battery cell 10. When S2 / S1 is less than 1.6, the conductivity of the aluminum sheet 320 is worse than that of the copper-plated nickel sheet 310, which leads to a mismatch in conductivity between the aluminum sheet 320 and the copper-plated nickel sheet 310. This results in a large internal resistance of the battery cell 10 and affects the rate performance of the battery cell 10. When 1.6 ≤ S2 / S1 ≤ 3.3, the conductivity of the aluminum sheet 320 and the copper-plated nickel sheet 310 is matched, resulting in a lower internal resistance of the cell 10, which is beneficial for improving the rate performance of the cell 10. It also reduces the weight of the cell 10, which is beneficial for improving its mass energy density. Conversely, when 1.6 ≤ S2 / S1 ≤ 1.9, the conductivity of the aluminum sheet 320 and the copper-plated nickel sheet 310 is matched, resulting in a lower internal resistance of the cell 10. This is beneficial for improving the rate performance of the cell 10 and further reduces its weight, which is beneficial for further improving its mass energy density.
[0081] (2) Referring to Examples 2 and 5-8, when S3 / S1 is greater than 3.3, the overlapping area of the copper-nickel plated sheet 310 and the aluminum sheet 320 along the thickness direction Y of the negative electrode tab is too large. With the length of the negative electrode tab 300 along the first direction remaining unchanged, the length of the copper-nickel plated sheet 310 and / or the aluminum sheet 320 along the first direction is large, resulting in a large weight of the copper-nickel plated sheet 310 and / or the aluminum sheet 320, which affects the mass energy density of the cell 10. When S3 / S1 is less than 1.6, the conductivity of the overlapping part of the aluminum sheet 320 and the copper-nickel plated sheet 310 is worse than that of the copper-nickel plated sheet 310. This will cause a mismatch between the conductivity of the overlapping part of the aluminum sheet 320 and the copper-nickel plated sheet 310 and the conductivity of the aluminum sheet 320 and the copper-nickel plated sheet 310, resulting in a large internal resistance of the cell 10, which affects the rate performance of the cell 10. When 1.6≤S3 / S1≤3.3, the overlapping portion of the aluminum sheet 320 and the copper-plated nickel sheet 310 can be matched with the conductivity of the copper-plated nickel sheet 310, thereby reducing the internal resistance of the battery cell 10, which is beneficial to improving the rate performance of the battery cell 10. It can also reduce the weight of the battery cell 10, which is beneficial to improving the mass energy density of the battery cell 10.
[0082] This application provides an electrical device, including a battery cell 10 as described above, which is used to provide electrical energy.
[0083] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.
[0084] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A battery cell, characterized in that, The battery cell includes: The packaging bag includes a main body and a sealing part; An electrode assembly is housed within the main body, the electrode assembly comprising a positive electrode and a negative electrode; The negative electrode tab includes a nickel-plated copper sheet and an aluminum sheet. Along a first direction, one end of the nickel-plated copper sheet is electrically connected to the negative electrode plate, and the other end of the nickel-plated copper sheet is welded to the aluminum sheet. The end of the aluminum sheet away from the nickel-plated copper sheet extends out of the encapsulation portion. The cross-sectional area of the nickel-plated copper sheet perpendicular to the first direction is S1, and the cross-sectional area of the aluminum sheet perpendicular to the first direction is S2, where 1.6 ≤ S2 / S1 ≤ 3.
3.
2. The battery cell according to claim 1, characterized in that, 1.6≤S2 / S1≤1.
9.
3. The battery cell according to claim 1, characterized in that, The battery cell includes a sealing element disposed between the negative electrode tab and the encapsulation portion; The copper-plated nickel sheet and the aluminum sheet are welded to form a welding area, which is located on the side of the seal opposite to the electrode assembly along the first direction.
4. The battery cell according to claim 1, characterized in that, The battery cell includes a sealing element disposed between the negative electrode tab and the encapsulation portion; The copper-plated nickel sheet and the aluminum sheet are welded to form a welding zone, and the seal covers at least a portion of the welding zone.
5. The battery cell according to claim 4, characterized in that, Along the first direction, the aluminum sheet has a first edge close to the electrode assembly, and along the thickness direction of the negative electrode tab, the seal covers the first edge.
6. The battery cell according to claim 1, characterized in that, The thickness of the copper-plated nickel sheet is H1, 0.1mm ≤ H1 ≤ 2mm; and / or, The thickness of the aluminum sheet is H2, where 0.1mm ≤ H2 ≤ 2mm.
7. The battery cell according to claim 1, characterized in that, Along the second direction, the width of the copper-plated nickel sheet is W1, and the width of the aluminum sheet is W2, where W2 ≥ W1; The first direction, the second direction, and the thickness direction of the negative electrode tab are perpendicular to each other.
8. The battery cell according to claim 1, characterized in that, Along the thickness direction of the negative electrode tab, a portion of the copper-plated nickel sheet overlaps and is welded to a portion of the aluminum sheet. The area of the overlapping portion of the copper-plated nickel sheet and the aluminum sheet is S3, and 1.6≤S3 / S1≤3.
3.
9. The battery cell according to claim 1, characterized in that, Along the first direction and away from the aluminum sheet, the width of the copper-plated nickel sheet gradually decreases along the second direction; S1 is the maximum cross-sectional area of the copper-plated nickel sheet; The first direction, the second direction, and the thickness direction of the negative electrode tab are perpendicular to each other.
10. The battery cell according to claim 9, characterized in that, Along the first direction, the copper-plated nickel sheet has a second edge close to the aluminum sheet and a third edge away from the aluminum sheet, the length of the second edge is L1, the length of the third edge is L2, and 1 < L1 / L2 ≤ 1.
6.
11. An electrical appliance, characterized in that, Includes a battery cell as described in any one of claims 1-10, the battery cell being used to provide electrical energy.