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 and inner tabs, and the inner tabs comprise a positive tab and a negative tab which are arranged at the end part of the pole group; the thickness of the pole group is a, the unit is mm, the width of the positive tab is b, the unit is mm, the width of the negative tab is c, b / a is more than or equal to 2.5 and less than or equal to 12, and c / a is more than or equal to 2.5 and less than or equal to 12. According to the battery cell provided by the invention, the width of the positive tab, the thickness of the pole group and the width of the negative tab are controlled within a reasonable range, so that the width of the tabs meets the overcurrent requirement of the battery cell, and meanwhile, the overcurrent capability of the positive tab and the overcurrent capability of the negative tab of the battery cell can be basically consistent; meanwhile, when the heat of the large surface of the pole group flows towards the pole lug along the length direction of the pole group, the heat at the root part of the pole lug is not excessively concentrated, so that the temperature rise at the pole lug is not too high, and the temperature of the whole battery cell is ensured to be transferred in a balanced manner at the large surface and the pole lug.

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 soft-pack battery cells in the related art often have large local temperature rises due to unreasonable ear size design, and the overall temperature cannot quickly reach equilibrium, which affects the performance of the battery cells. Summary of the invention

[0004] In view of this, the present invention provides a battery cell and a battery pack to solve the problem of large local temperature rise of the battery cell and affecting the performance of the battery cell.

[0005] In a first aspect, the present invention provides a battery cell comprising a pole group and an inner pole ear, wherein the inner pole ear comprises a positive pole ear and a negative pole ear arranged at the end of the pole group; the thickness of the pole group is a, in mm, the width of the positive pole ear is b, in mm, and the width of the negative pole ear is c, satisfying: 2.5≤b / a≤12, 2.5≤c / a≤12.

[0006] Beneficial effect: The battery cell provided by the present invention controls the ratio of the width of the positive electrode ear to the thickness of the electrode group within the range of 2.5 to 12, and controls the ratio of the width of the negative electrode ear to the thickness of the electrode group within the range of 2.5 to 12, so as to ensure that the width of the electrode ear meets the overcurrent requirement of the battery cell. At the same time, the overcurrent capacity of the positive electrode ear and the negative electrode ear of the battery cell can be basically consistent. At the same time, when the heat of the large surface of the electrode group flows toward the electrode ear along the length direction of the electrode group, the heat at the root of the electrode ear will not cause excessive temperature rise at the electrode ear due to excessive concentration, thereby ensuring that the temperature of the entire battery cell is evenly transferred at the large surface and the electrode ear.

[0007] In an optional embodiment, the ratio of the width b of the positive electrode tab to the width c of the negative electrode tab satisfies: 0.75≤b / c≤0.90.

[0008] In an optional implementation, the thickness a of the pole group satisfies: 3.5 mm≤a≤11.5 mm.

[0009] In an optional implementation, the width b of the positive electrode tab satisfies: 15 mm ≤ b ≤ 40 mm.

[0010] In an optional implementation, the width c of the negative electrode ear satisfies: 20 mm ≤ c ≤ 45 mm.

[0011] In an optional embodiment, it further comprises a packaging film, wherein the packaging film has a containing cavity, and the electrode group is arranged in the containing cavity.

[0012] In an optional embodiment, two electrode sheets are further included, and the two electrode sheets are respectively welded to the positive electrode ear and the negative electrode ear, and the electrode sheets extend out of the packaging film.

[0013] In an optional embodiment, the electrode sheet includes an electrode sheet and an insulating member, one end of the electrode sheet is welded to the inner electrode ear, and the other end of the electrode sheet is exposed to the packaging film, and the packaging film and the insulating member are hot-pressed and fused to achieve a sealed connection.

[0014] In an optional implementation, the inner pole ear is located in the middle of the end surface of the pole group.

[0015] In a second aspect, the present invention further provides a battery pack comprising the battery cell described in any one of the above technical solutions.

[0016] 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

[0017] 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.

[0018] Figure 1 An exploded diagram of a battery cell according to an embodiment of the present invention;

[0019] Figure 2 for Figure 1 Schematic diagram of the structure of the pole group in;

[0020] Figure 3 for Figure 2 A top view of the pole group shown;

[0021] Figure 4 for Figure 2 A front view of the pole group shown;

[0022] Figure 5 Figure 2 is a schematic diagram of the locations of temperature test points.

[0023] Description of reference numerals:

[0024] 1. Pole group; 2. Positive electrode ear; 3. Negative electrode ear; 4. Electrode sheet; 5. Packaging film; 6. Insulating part. DETAILED DESCRIPTION

[0025] 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.

[0026] Combine the following Figures 1 to 5 , describing an embodiment of the present invention.

[0027] According to an embodiment of the present invention, in a first aspect, a battery cell is provided, comprising a pole group 1 and an inner pole ear, the inner pole ear comprising a positive pole ear 2 and a negative pole ear 3 arranged at the end of the pole group 1; the thickness of the pole group 1 is a, in mm, the width of the positive pole ear 2 is b, in mm, and the width of the negative pole ear 3 is c, satisfying: 2.5≤b / a≤12, 2.5≤c / a≤12.

[0028] The battery cell provided by the present invention controls the ratio of the width of the positive electrode ear 2 to the thickness of the electrode group 1 within the range of 2.5 to 12, and controls the ratio of the width of the negative electrode ear 3 to the thickness of the electrode group 1 within the range of 2.5 to 12, so as to ensure that the width of the electrode ear meets the overcurrent requirement of the battery cell, and at the same time, the overcurrent capacity of the positive electrode ear 2 and the negative electrode ear 3 of the battery cell can be basically consistent. At the same time, when the heat of the large surface of the electrode group 1 flows toward the electrode ear along the length direction of the electrode group 1, the heat at the root of the electrode ear will not cause excessive temperature rise at the electrode ear due to excessive concentration, thereby ensuring that the temperature of the entire battery cell is evenly transferred at the large surface and the electrode ear.

[0029] In some embodiments, the ratio of the width b of the positive electrode tab 2 to the width c of the negative electrode tab 3 satisfies: 0.75≤b / c≤0.90.

[0030] By controlling the ratio of the width b of the positive electrode ear 2 and the width c of the negative electrode ear 3 within the range of 0.75≤b / c≤0.90, it can be ensured that the current capacity of the positive electrode ear 2 and the negative electrode ear 3 are equivalent during the charge and discharge process of the battery cell; at the same time, it can be ensured that when the current of the electrode group 1 flows toward the electrode ear along the length direction of the battery cell, the heat at the root of the electrode ear will not be excessively concentrated, resulting in excessive temperature rise at the electrode ear, thereby ensuring that the temperature of the entire battery cell is evenly transferred, avoiding the temperature rise or unbalanced temperature transfer caused by overcurrent inside the battery cell due to unreasonable size design, resulting in local excessive temperature and affecting the overall performance of the battery cell.

[0031] In some embodiments, the thickness a of the electrode group 1 satisfies: 3.5 mm≤a≤11.5 mm.

[0032] Controlling the thickness a of the pole group 1 within the thickness range of 3.5 mm to 11.5 mm can optimize the electromagnetic performance, provide sufficient mechanical strength and stability, improve the heat dissipation performance of the pole group 1, reasonably control the material usage and manufacturing cost, ensure the efficiency, reliability and economy of the pole group 1 during use, and adapt to various application scenarios.

[0033] In some embodiments, the width b of the positive electrode tab 2 satisfies: 15 mm ≤ b ≤ 40 mm.

[0034] When the width b of the positive electrode ear 2 is too small and exceeds 15 mm, the temperature rise at the corresponding electrode ear will be higher. When the width b of the positive electrode ear 2 is too large and exceeds 40 mm, the electrode ear is prone to folding during the electrode ear die-cutting process, affecting the process yield.

[0035] In some embodiments, the width c of the negative electrode tab 3 satisfies: 20 mm≤c≤45 mm.

[0036] When the width c of the negative electrode ear 3 is too small and exceeds 20 mm, the temperature rise at the corresponding electrode ear will be higher. When the width c of the negative electrode ear 3 is too large and exceeds 45 mm, the electrode ear is prone to folding during the electrode ear die-cutting process, affecting the process yield.

[0037] In some embodiments, a packaging film 5 is further included, wherein the packaging film 5 has a receiving cavity, and the electrode group 1 is disposed in the receiving cavity.

[0038] Specifically, the aluminum-plastic film is molded into a cavity for accommodating the electrode group 1 by die stamping, thereby obtaining the packaging film 5, which includes a first shell and a second shell. In some embodiments, the first shell and the second shell are spliced ​​to form an accommodating cavity for accommodating the electrode group 1. After the electrode group 1 is placed in the accommodating cavity, the first shell and the second shell are sealed and connected by hot pressing and edge sealing.

[0039] In some embodiments, two electrode sheets 4 are further included. The two electrode sheets 4 are respectively welded to the positive electrode tab 2 and the negative electrode tab 3 , and the electrode sheets 4 extend out of the packaging film 5 .

[0040] In some embodiments, an insulating member 6 is further included, and the insulating member 6 is disposed on the electrode sheet 4. One end of the electrode sheet 4 is welded to the inner tab, and the other end of the electrode sheet 4 is exposed to the packaging film 5. The packaging film 5 and the insulating member 6 are hot-pressed and fused to achieve a sealed connection.

[0041] Specifically, during the sealing process of the packaging film 5, the insulating member 6 of the electrode sheet 4 is hot-pressed and fused with the packaging film 5 at the middle of the electrode sheet 4 to achieve the sealing of the battery cell. The middle of the electrode sheet 4 is isolated from the packaging film 5 by the insulating member 6, thereby leading out the current.

[0042] In some embodiments, the packaging film 5 is an aluminum-plastic film.

[0043] In some embodiments, the insulating member 6 is made of insulating glue.

[0044] In some embodiments, the inner pole ear is located in the middle of the end surface of the pole group 1 .

[0045] Placing the inner pole ear in the middle of the end face of pole group 1 helps to distribute the current more evenly throughout the battery cell, reduce local overheating, and improve the overall performance and safety of the battery cell. At the same time, the design of the middle position can effectively shorten the current path, thereby reducing the internal resistance of the battery cell, reducing energy loss, and improving the energy conversion efficiency of the battery cell.

[0046] In order to verify the technical solution of the present invention, several experimental cases are provided below. Actual temperature rise test is carried out on the battery samples of DOE with different sizes. The temperature test points are as follows: Figure 4 The five points A, B, C, D, and E shown in the figure are as follows: point A is located at the geometric center of pole group 1, points B and C are located at 1 / 4 and 3 / 4 of the width of pole group 1, respectively, and points D and E are located at the center of the pole ear. The test results are shown in Table 1

[0047] Table 1: Table 2:

[0048]

[0049] Table 3:

[0050]

[0051] From Tables 1 to 3, we can see that:

[0052] For Case 1 and Case 2, the b value is too small, and the verification results show that the width of the positive electrode ear is too small, and the temperature of the large surface of the battery cell and the positive electrode side is too high.

[0053] For Case 5, Case 6 and Case 8, the c value is too small. The verification results show that the width of the negative electrode ear is too small, and the temperature of the large surface of the battery cell and the negative electrode side is too high.

[0054] For Case 9, the a value is too small, the b value is too small, and the verification results show that electrode group 1 is thinner, the width of the positive electrode ear is too small, and the temperature of the large surface of the battery cell and the positive electrode side is too high.

[0055] For Case 12 and Case 15, the b value is too large. The verification result shows that the tabs are easily folded during the tab die-cutting process, which affects the process yield.

[0056] For Case 16, the a value is too large, and the verification result shows that the electrode group 1 is thicker and the temperature of the large surface of the electrode group 1 is higher; the c value is too large, and the verification result shows that the width of the negative electrode ear 3 is too large, and the ear is prone to folding during the ear die-cutting process, affecting the process yield.

[0057] The remaining cases satisfy 2.5≤b / a≤12, 2.5≤c / a≤12, and 0.75≤b / c≤0.90. The verification result shows that the overall temperature of the battery cell is relatively balanced.

[0058] The design of the size of the inner pole ear has a significant impact on the temperature rise of each part of the entire battery cell. When all parameters meet the preset conditions, it can ensure that the temperature of the entire battery cell in the positive pole ear 2, the negative pole ear 3 and the pole group 1 is uniform and the temperature transfer is balanced. Finally, the temperature of each part of the entire battery cell is equivalent, ensuring the overall performance of the battery cell.

[0059] The present invention can ensure that the current capacity of the positive electrode ear 2 and the negative electrode ear 3 of the battery cell is equivalent during the charge and discharge process by reasonably limiting the size relationship between the positive electrode ear 2 and the negative electrode ear 3 of the battery cell, as well as the proportional relationship between the thickness of the inner electrode ear and the electrode group 1; at the same time, it is ensured that when the current of the electrode group 1 flows toward the electrode ear along the length direction of the electrode group 1, the heat at the root of the electrode ear will not be excessively concentrated, resulting in excessive temperature rise at the electrode ear, thereby ensuring balanced temperature transfer of the entire battery cell and the electrode ear, and ensuring the overall performance of the battery cell.

[0060] According to an embodiment of the present invention, in a second aspect, a battery pack is further provided, comprising the battery cell described in any one of the above embodiments.

[0061] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be described in detail here.

[0062] 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; The inner pole ear comprises a positive pole ear and a negative pole ear arranged at the end of the pole group; the thickness of the pole group is a, in mm, the width of the positive pole ear is b, in mm, and the width of the negative pole ear is c, satisfying: 2.5≤b / a≤12, 2.5≤c / a≤12.

2. The battery cell according to claim 1, characterized in that: The ratio of the width b of the positive electrode tab to the width c of the negative electrode tab satisfies: 0.75≤b / c≤0.

90.

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

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

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

6. The battery cell according to claim 1 or 2, characterized in that: It also includes a packaging film, which has a containing cavity, and the electrode group is arranged in the containing cavity.

7. The battery cell according to claim 6, characterized in that: It also includes two electrode sheets, which are respectively welded to the positive electrode ear and the negative electrode ear, and the electrode sheets extend out of the packaging film.

8. The battery cell according to claim 7, characterized in that: It also includes an insulating member, which is arranged on the electrode sheet, one end of the electrode sheet is welded to the inner electrode ear, and the other end of the electrode sheet is exposed to the packaging film, and the packaging film and the insulating member are hot-pressed and fused to achieve a sealed connection.

9. The battery cell according to claim 1 or 2, characterized in that: The inner pole ear is located in the middle of the end surface of the pole 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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