Battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises a pole group. The pole group comprises a pole group and inner tabs arranged at the end part of the pole group, the inner tabs comprise a positive tab and a negative tab, the width of the pole group is A, the thickness of the pole group is B, the width of the positive tab is W1, the thickness of the positive tab is t1, the width of the negative tab is W2, the thickness of the negative tab is t2, and the parameters need to meet preset conditions. According to the battery cell provided by the invention, the sizes of the tabs are designed and improved, and the proportional relation between the cross sectional areas of the positive and negative tabs of the battery cell and the cross sectional area of the pole group and the proportional relation between the cross sectional areas of the positive and negative tabs are reasonably limited, so that the overcurrent capacities of the positive and negative tabs of the battery cell are basically consistent; and meanwhile, the heat of the electrode group flows towards the tab along the length direction of the battery cell and is transferred to an external circuit through the cross section of the tab, so that the temperature rise of the whole battery cell, including the electrode group and the tab, is balanced, and the problem that the use performance of the battery cell is influenced by over-high local temperature rise is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to battery cells and battery packs. Background Art

[0002] Soft-pack lithium batteries usually refer to lithium batteries whose outer shells are encapsulated with aluminum-plastic film. Due to their many advantages such as light weight, low mold cost, great structural flexibility, high energy density, and high battery safety performance, they have been widely used in various fields such as electric vehicles, drones, smart homes, and mobile power supplies.

[0003] The battery structure includes a packaging film, a pole group, an inner pole ear and an electrode sheet. An insulating member is provided on the electrode sheet. One end of the electrode sheet is fixed to the inner pole ear of the pole group by laser welding, and the other end of the electrode sheet is led out to the outside of the packaging film. The middle part of the electrode sheet is isolated from the shell by an insulating member, thereby leading out the current.

[0004] In the related art, due to the unreasonable design of the tab size, the local temperature rise of the battery cell is often large, and the overall temperature cannot quickly reach equilibrium, which affects the performance of the battery cell. Summary of the invention

[0005] In view of this, the present invention provides a battery cell and a battery pack to solve the problem that the local temperature rise of the battery cell is large and affects the performance of the battery cell.

[0006] In a first aspect, the present invention provides a battery cell, comprising a pole group and an inner pole ear. The inner pole ear is arranged at the end of the pole group, and the inner pole ear comprises a positive pole ear and a negative pole ear. The width of the pole group is A, the thickness of the pole group is B, the width of the positive pole ear is W1, the thickness of the positive pole ear is t1, the width of the negative pole ear is W2, the thickness of the negative pole ear is t2, and the unit of each parameter is mm; satisfying:

[0007]

[0008] Beneficial effect: The battery cell provided by the present invention has improved design on the size of the pole ear. By reasonably limiting the ratio of the cross-sectional area of ​​the positive and negative pole ear to the cross-sectional area of ​​the pole group, as well as the ratio of the cross-sectional area of ​​the positive and negative pole ear, the current carrying capacity of the positive and negative pole ear of the battery cell can be basically consistent. At the same time, when the heat of the pole group flows along the length direction of the battery cell toward the pole ear, it is transferred to the external circuit through the cross-sectional area of ​​the pole ear. The temperature rise of the entire battery cell (including the pole group and the pole ear) is balanced, and there will be no problem of excessive local temperature rise affecting the performance of the battery cell.

[0009] In an optional implementation, the width A of the pole group satisfies: 20 mm≤A≤100 mm.

[0010] In an optional implementation, the thickness B of the electrode group satisfies: 3.5 mm≤B≤11.5 mm.

[0011] In an optional embodiment, the width W1 of the positive electrode tab satisfies: 15 mm ≤ W1 ≤ 40 mm.

[0012] In an optional embodiment, the thickness t1 of the positive electrode tab satisfies: 0.4 mm≤t1≤0.8 mm.

[0013] In an optional embodiment, the width W2 of the negative electrode ear satisfies: 20 mm ≤ W2 ≤ 45 mm.

[0014] In an optional embodiment, the thickness t2 of the negative electrode ear satisfies: 0.18 mm≤t2≤0.35 mm.

[0015] In an optional embodiment, the ratio of the width of the positive electrode ear to the width of the electrode group satisfies: W1 / A≥20%, and the ratio of the width of the negative electrode ear to the width of the electrode group satisfies: W2 / A≥20%.

[0016] In an optional embodiment, the positive electrode tab and the negative electrode tab are respectively arranged in the middle of both ends of the electrode group.

[0017] In a second aspect, the present invention further provides a battery pack, comprising the battery cell in the above technical solution.

[0018] Beneficial effect: Since the battery pack includes the battery cell, it has the same effect as the battery cell and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the structural decomposition of a battery cell according to an embodiment of the present invention;

[0021] Figure 2 for Figure 1 The schematic diagram of the structure of the electrode group in the battery cell shown is from a first viewing angle;

[0022] Figure 3 for Figure 1 The schematic diagram of the structure of the electrode group in the battery cell shown in the second viewing angle;

[0023] Figure 4 Schematic diagram of the locations of the test temperature points.

[0024] Description of reference numerals:

[0025] 1. Pole group; 2. Inner pole ear; 21. Positive pole ear; 22. Negative pole ear; 3. Packaging film; 4. Electrode sheet; 5. Insulating part. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0027] Combine the following Figures 1 to 4 , describing an embodiment of the present invention.

[0028] According to an embodiment of the present invention, in a first aspect, a battery cell is provided, comprising an electrode group 1 and an inner electrode ear 2. The inner electrode ear 2 is arranged at the end of the electrode group 1, and the inner electrode ear 2 comprises a positive electrode ear 21 and a negative electrode ear 22. The width of the electrode group 1 is A, the thickness of the electrode group 1 is B, the width of the positive electrode ear 21 is W1, the thickness of the positive electrode ear 21 is t1, the width of the negative electrode ear 22 is W2, and the thickness of the negative electrode ear 22 is t2. The units of each parameter are mm; satisfying:

[0029]

[0030] The battery cell provided by the present invention has an improved design for the size of the pole ear. By reasonably limiting the proportional relationship between the cross-sectional area of ​​the positive and negative pole ears of the battery cell and the cross-sectional area of ​​the pole group 1, as well as the proportional relationship between the cross-sectional areas of the positive and negative pole ears, the current carrying capacity of the positive and negative pole ears of the battery cell can be made basically consistent. At the same time, when the heat of the pole group 1 flows toward the pole ear along the length direction of the battery cell, it is transferred to the external circuit through the cross-sectional area of ​​the pole ear. The temperature rise of the entire battery cell (including the pole group 1 and the pole ear) is balanced, and there will be no problem of excessive local temperature rise affecting the performance of the battery cell.

[0031] In some embodiments, the width A of the electrode group 1 satisfies: 20 mm ≤ A ≤ 100 mm.

[0032] By controlling the width A of the electrode group 1 within the range of 20 mm to 100 mm, the width of the electrode group 1 is made more reasonable, which can ensure that the current is distributed more evenly on the electrode sheet. When the width of the electrode group 1 is close to 100 mm, it helps to reduce hot spots caused by excessive local current density, thereby reducing local temperature rise. At the same time, it can provide a larger surface area, which is conducive to the diffusion and conduction of heat. This can better disperse the heat inside the battery, reduce the temperature gradient, make the overall temperature reach equilibrium faster, and improve the thermal management efficiency.

[0033] In some embodiments, the thickness B of the electrode group 1 satisfies: 3.5 mm≤B≤11.5 mm.

[0034] By controlling the thickness B of the electrode group 1 within the range of 3.5 mm to 11.5 mm, the appropriate thickness of the electrode group 1 can optimize the heat conduction path inside the battery. A larger thickness B of the electrode group 1 helps to conduct heat in the vertical direction, thereby reducing the formation of hot spots and distributing heat more evenly throughout the battery. At the same time, the internal resistance of the battery can be reduced. A smaller thickness B of the electrode group 1 can reduce the transmission distance of electrons in the electrode material, thereby reducing resistance heating, so that the internal temperature of the battery cell is balanced and the performance of the battery cell is guaranteed.

[0035] In some embodiments, the width W1 of the positive electrode tab 21 satisfies: 15 mm ≤ W1 ≤ 40 mm.

[0036] Controlling the width W1 of the positive electrode tab 21 within the range of 15 mm to 40 mm can ensure uniform distribution of current on the electrode sheet. When the width of the positive electrode tab 21 is larger, it can provide a larger conductive area, reduce the current density, and thus reduce the risk of local overheating. At the same time, it can increase the number of conductive paths, reduce internal resistance, and reduce the generation of Joule heat, which helps to reduce local temperature rise and improve the overall performance and efficiency of the battery.

[0037] In some embodiments, the thickness t1 of the positive electrode tab 21 satisfies: 0.4 mm≤t1≤0.8 mm.

[0038] Controlling the thickness t1 of the positive electrode tab 21 within the range of 0.4 mm to 0.8 mm can ensure uniform distribution of current on the electrode sheet. When the thickness of the positive electrode tab 21 is larger, it can provide more conductive paths, reduce current density, and thus reduce the risk of local overheating. At the same time, it can increase the number of conductive paths, reduce internal resistance, and reduce the generation of Joule heat, which helps to reduce local temperature rise and improve the overall performance and efficiency of the battery.

[0039] In some embodiments, the width W2 of the negative electrode tab 22 satisfies: 20 mm≤W2≤45 mm.

[0040] Controlling the width W2 of the negative electrode ear 22 within the range of 20 mm to 45 mm can ensure uniform distribution of current on the electrode sheet. When the width of the negative electrode ear 22 is larger, it can provide a larger conductive area, reduce the current density, and thus reduce the risk of local overheating. At the same time, it can increase the number of conductive paths, reduce internal resistance, and reduce the generation of Joule heat, which helps to reduce local temperature rise and improve the overall performance and efficiency of the battery.

[0041] In some embodiments, the thickness t2 of the negative electrode tab 22 satisfies: 0.18 mm≤t2≤0.35 mm.

[0042] Controlling the thickness t2 of the negative electrode ear 22 within the range of 0.18 mm to 0.35 mm can ensure uniform distribution of current on the electrode sheet. When the thickness of the negative electrode ear 22 is larger, more conductive paths can be provided, and the current density can be reduced, thereby reducing the risk of local overheating. At the same time, the number of conductive paths can be increased, the internal resistance can be reduced, and the generation of Joule heat can be reduced, which helps to reduce local temperature rise and improve the overall performance and efficiency of the battery.

[0043] In some embodiments, the ratio of the width of the positive electrode tab 21 to the width of the electrode group 1 satisfies: W1 / A≥20%, and the ratio of the width of the negative electrode tab 22 to the width of the electrode group 1 satisfies: W2 / A≥20%.

[0044] This arrangement can ensure the contact area between the positive electrode ear 21 and the electrode group 1, as well as the contact area between the negative electrode ear 22 and the electrode group 1, thereby ensuring the heat dissipation effect of the electrode group 1 at the electrode ear, preventing local overheating of the battery cell at the electrode ear, and ensuring good current transmission and heat dissipation, thereby ensuring the performance of the battery cell.

[0045] In some embodiments, it also includes a packaging film 3 and an electrode sheet 4, the packaging film 3 is coated on the outer surface of the electrode group 1; the electrode sheet 4 includes an electrode sheet 4 and an insulating member 5 arranged in the middle of the electrode sheet 4, one end of the electrode sheet 4 is welded to the positive electrode ear 21 or the negative electrode ear 22, and the other end of the electrode sheet 4 extends to the outside of the packaging film 3, the packaging film 3 is heat-sealed, and at the position of the electrode sheet 4, the packaging film 3 and the insulating member 5 are hot-pressed and fused.

[0046] In some embodiments, the packaging film 3 is an aluminum-plastic film. Specifically, the aluminum-plastic film is punched out of the cavity containing the electrode group 1 by die stamping, and after the electrode group 1 is placed in the cavity, it is sealed by hot-pressing the edge of the aluminum-plastic film. At the same time, during the aluminum-plastic film sealing process, the insulating member 5 of the electrode sheet 4 is hot-pressed and sealed at the position of the pole ear to achieve the sealing of the battery cell. The aluminum-plastic film has good thermal conductivity and can effectively conduct the heat generated inside the battery to the outside. In addition, the design of the electrode sheet 4 also helps to dissipate heat, thereby reducing the temperature rise of the battery and improving its overall performance and life.

[0047] In some embodiments, the insulating member 5 is made of insulating glue.

[0048] The packaging film 3 is coated on the outer surface of the electrode group 1 and connected by heat sealing, which can provide good sealing performance and prevent electrolyte leakage. At the position of the electrode sheet 4, the packaging film 3 and the insulating member 5 are connected by hot pressing fusion, which further enhances the sealing performance, ensures the stability of the internal environment of the battery, reduces failures caused by electrolyte leakage, overheating and mechanical damage, and thus improves the reliability and durability of the battery.

[0049] The insulating member 5 is disposed in the middle of the electrode sheet 4 , which can effectively isolate the direct contact between the electrode sheet 4 and the packaging film 3 , thereby avoiding the risk of short circuit.

[0050] In an optional embodiment, the positive electrode tab 21 and the negative electrode tab 22 are respectively arranged in the middle of both ends of the electrode group 1 .

[0051] Placing the positive electrode ear 21 and the negative electrode ear 22 in the middle of both ends of the electrode group 1 can ensure that the current is evenly distributed throughout the electrode group 1. This can reduce the local overheating problem caused by uneven current density and improve the overall performance of the battery. At the same time, the heat can be dissipated more evenly from both ends of the electrode group 1, avoiding the heat from being concentrated at a certain point. Uniform heat dissipation can effectively reduce local temperature rise and improve the thermal management performance of the battery.

[0052] In order to verify the technical effect of the present invention, battery cell samples with DOE of different sizes were arranged to carry out actual temperature rise test. The temperature test points were five points shown as A, B, C, D and E. Among them, point A was at the center of pole group 1, point B and point C were respectively 10 mm away from the end face of pole group 1, and point D and point E were at the center of the pole ear.

[0053] For the DOE cell sample, the width A of the electrode group 1 is 100 mm, and the thickness B of the electrode group 1 is 10 mm.

[0054] The test results are shown in Tables 1 to 3. Table 1:

[0055]

[0056] Table 2:

[0057]

[0058] Table 3:

[0059]

[0060] It can be seen from Tables 1 to 3 that the design of the tab size has a significant impact on the temperature rise of each part of the entire battery cell. The preset relationship must be satisfied at the same time to ensure that the temperature of the entire battery cell is uniform in the positive and negative tabs 22 and each part of the electrode group 1, and the temperature transfer is balanced. Finally, the temperature of each part of the entire battery cell is equivalent, ensuring the performance of the battery cell.

[0061] According to an embodiment of the present invention, in a second aspect, a battery pack is further provided, comprising the battery cell in the above embodiment.

[0062] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be described in detail here.

[0063] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that: include: Pole group; An inner pole ear, the inner pole ear is arranged at the end of the pole group, the inner pole ear includes a positive pole ear and a negative pole ear, the width of the pole group is A, the thickness of the pole group is B, the width of the positive pole ear is W1, the thickness of the positive pole ear is t1, the width of the negative pole ear is W2, the thickness of the negative pole ear is t2, and the unit of each parameter is mm; satisfying:

2. The battery cell according to claim 1, characterized in that: The width A of the pole group satisfies: 20mm≤A≤100mm.

3. The battery cell according to claim 1 or 2, characterized in that: The thickness B of the electrode group satisfies: 3.5 mm≤B≤11.5 mm.

4. The battery cell according to claim 1 or 2, characterized in that: The width W1 of the positive electrode ear satisfies: 15 mm ≤ W1 ≤ 40 mm.

5. The battery cell according to claim 1 or 2, characterized in that: The thickness t1 of the positive electrode ear satisfies: 0.4 mm ≤ t1 ≤ 0.8 mm.

6. The battery cell according to claim 1 or 2, characterized in that: The width W2 of the negative electrode ear satisfies: 20 mm ≤ W2 ≤ 45 mm.

7. The battery cell according to claim 1 or 2, characterized in that: The thickness t2 of the negative electrode ear satisfies: 0.18 mm ≤ t2 ≤ 0.35 mm.

8. The battery cell according to claim 1 or 2, characterized in that: The ratio of the width of the positive electrode ear to the width of the electrode group satisfies: W1 / A≥20%, and the ratio of the width of the negative electrode ear to the width of the electrode group satisfies: W2 / A≥20%.

9. The battery cell according to claim 1 or 2, characterized in that: The positive electrode tab and the negative electrode tab are respectively arranged at the middle of both ends of the electrode group.

10. A battery pack, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 9.

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