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 pole group is provided with internal tabs, and the internal tabs comprise a positive tab and a negative tab which are respectively arranged at two ends of the pole group; the width of the positive tab is b, the unit is mm, the number of pole piece layers of the positive tab is m, the thickness of a pole piece foil of the positive tab is t1, and the unit is mu m; the width of the negative tab is c, the unit is mm, the number of pole piece layers of the negative tab is n, the thickness of a pole piece foil of the negative tab is t2, and the unit is mu m; mbt1 / nct2 is greater than or equal to 1.5 and less than or equal to 2.2. The battery cell provided by the invention can ensure that the positive tab and the negative tab are reasonably matched in size, and the positive tab and the negative tab are equivalent in overcurrent capability in the charging and discharging process of the battery cell; and meanwhile, when the heat of the large surface of the pole group flows towards the tab along the length direction of the battery cell, the heat at the root part of the tab cannot be excessively concentrated, so that the temperature rise at the tab is not too high, and the temperature of the whole battery cell at the large surface and the tab is ensured to be transferred in a balanced manner, thereby ensuring the performance of the battery cell.

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 that the local temperature rise of the battery cell is large and affects the performance of the battery cell.

[0005] In a first aspect, the present invention provides a battery cell, including an electrode group. The electrode group is provided with internal electrode ears, and the internal electrode ears include positive electrode ears and negative electrode ears respectively arranged at both ends of the electrode group; the width of the positive electrode ear is b, in mm, the number of electrode sheets of the positive electrode ear is m, and the thickness of the electrode sheet foil of the positive electrode ear is t1, in μm; the width of the negative electrode ear is c, in mm, the number of electrode sheets of the negative electrode ear is n, and the thickness of the electrode sheet foil of the negative electrode ear is t2, in μm; and the following conditions are satisfied: 1.5≤mbt1 / nct2≤2.2.

[0006] Beneficial effects: The battery cell provided by the present invention can ensure that the sizes of the positive and negative ears are reasonably matched by controlling the ratio of the relevant parameters of the positive and negative ears within the range of 1.5 to 2.2, and the current carrying capacity of the positive and negative ears during the charging and discharging process of the battery cell is equivalent; at the same time, when the heat of the large surface of the electrode group flows toward the ear along the length direction of the battery cell, the heat at the root of the ear will not cause excessive temperature rise at the ear due to excessive concentration, thereby ensuring that the temperature of the entire battery cell is evenly transferred at the large surface and the ear, thereby ensuring the performance of the battery cell.

[0007] In an optional implementation, the number of electrode sheet layers m of the positive electrode tab satisfies: 20≤m≤55; and the thickness t1 of the electrode sheet foil of the positive electrode tab satisfies: 12 μm≤t1≤13 μm.

[0008] In an optional implementation, the number of electrode sheet layers n of the negative electrode tab satisfies: 21≤n≤56; and the thickness t2 of the electrode sheet foil of the negative electrode tab satisfies: 4.5 μm≤t2≤6 μm.

[0009] In an optional implementation, the pole group has two large surfaces that are arranged opposite to each other, and the length of the large surfaces is a, in mm, and 0.25≤b / a≤0.35.

[0010] In an optional embodiment, the width c of the negative electrode ear and the length a of the large surface satisfy: 0.35≤c / a≤0.50.

[0011] In an optional implementation, the length a of the large surface satisfies: 20 mm ≤ a ≤ 100 mm.

[0012] In an optional embodiment, it also includes an electrode sheet and a packaging film, wherein two electrode sheets are provided and are respectively welded to the positive electrode ear and the negative electrode ear; the packaging film is sealed and coated on the outer surface of the electrode group, and one end of the electrode sheet is exposed from the packaging film.

[0013] In an optional embodiment, it also includes an insulating member arranged on the electrode sheet, one end of the electrode sheet is exposed from the packaging film, the packaging film and the insulating member are sealed and connected by hot pressing fusion, and the other end of the electrode sheet is welded to the internal electrode ear.

[0014] In an optional embodiment, the material of the positive electrode ear is aluminum foil, and the flow coefficient is σ1,5A / mm 2 ≤σ1≤8A / mm 2 ; The material of the negative electrode ear is copper foil, and the current coefficient is σ2,8A / mm 2 ≤σ2≤12A / mm 2 .

[0015] In a second aspect, the present invention further provides a battery pack, comprising the battery cell in the above technical solution.

[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 Zhongji group;

[0020] Figure 3 for Figure 2 A top view of

[0021] Figure 4 Schematic diagram of the test point locations.

[0022] Description of reference numerals:

[0023] 1. Pole group; 2. Positive electrode ear; 3. Negative electrode ear; 4. Electrode sheet; 5. Packaging film; 6. Insulating part. DETAILED DESCRIPTION

[0024] 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.

[0025] The existing battery cell structure is mainly composed of an electrode group 1, an electrode sheet 4, a packaging film 5 and an insulating member 6. The electrode group 1 includes an internal pole ear. The packaging film is punched out of the cavity that accommodates the electrode group 1 by die stamping. After the electrode group 1 is placed in the cavity, it is sealed by hot pressing the edge of the packaging film. At the same time, during the sealing process of the packaging film 5, the pole ear position is hot-pressed and sealed with the insulating member 6 to achieve the sealing of the battery cell. One end of the electrode sheet 4 is led out to the outside of the packaging film 5, and the middle part is isolated from the shell formed by the packaging film 5 by the insulating member 6, so as to lead out the current. The other end of the electrode sheet 4 is fixed to the internal pole ear of the electrode group 1 by laser welding.

[0026] Combine the following Figures 1 to 4 , 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 an electrode group 1. The electrode group 1 is provided with internal electrode ears, and the internal electrode ears include a positive electrode ear 2 and a negative electrode ear 3 respectively arranged at both ends of the electrode group 1; the width of the positive electrode ear 2 is b, in mm, the number of electrode sheet layers of the positive electrode ear 2 is m, and the thickness of the electrode sheet foil of the positive electrode ear 2 is t1, in μm; the width of the negative electrode ear 3 is c, in mm, the number of electrode sheet layers of the negative electrode ear 3 is n, and the thickness of the electrode sheet foil of the negative electrode ear 3 is t2, in μm; and the following conditions are satisfied: 1.5≤mbt1 / nct2≤2.2.

[0028] The battery cell provided by the present invention can ensure that the sizes of the positive electrode ear 2 and the negative electrode ear 3 are reasonably matched by controlling the ratio of the relevant parameters of the positive electrode ear 2 and the negative electrode ear 3 within the range of 1.5 to 2.2, and the current flow capacity of the positive electrode ear 2 and the negative electrode ear 3 during the charging and discharging process of the battery cell is equivalent; 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 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 at the large surface and the electrode ear, thereby ensuring the performance of the battery cell.

[0029] In some embodiments, the number m of electrode sheet layers of the positive electrode tab 2 satisfies: 20≤m≤55; the thickness t1 of the electrode sheet foil of the positive electrode tab 2 satisfies: 12 μm≤t1≤13 μm.

[0030] In some embodiments, the number of electrode sheet layers n of the negative electrode tab 3 satisfies: 21≤n≤56; the thickness t2 of the electrode sheet foil of the negative electrode tab 3 satisfies: 4.5 μm≤t2≤6 μm.

[0031] In some embodiments, the electrode group 1 has two large surfaces arranged opposite to each other, the length of the large surfaces is a, in mm, and 0.25≤b / a≤0.35.

[0032] Specifically, the electrode group 1 is substantially in a rectangular parallelepiped structure, and the large surface of the electrode group 1 is the surface with the largest area of ​​the electrode group 1. The length a of the large surface is the length of the electrode group 1.

[0033] By controlling the ratio of the width of the positive electrode ear 2 to the length a of the large surface of the electrode group 1 within the range of 0.25 to 0.35, it can be ensured that when the current of the electrode group 1 along the entire width direction flows toward the positive electrode ear 2 along the length direction of the battery cell, the heat at the root of the positive electrode ear 2 will not be excessively concentrated (the ratio of the width of the positive electrode ear 2 to the width of the electrode group 1 is too small) and cause the temperature at the positive electrode ear 2 to rise too high, ensuring that the temperature of the entire battery cell is evenly transferred on the large surface and the positive electrode ear 2, avoiding the temperature rise or unbalanced temperature transfer caused by overcurrent inside the battery cell due to unreasonable size design, resulting in excessive local temperature and affecting the overall performance of the battery cell. At the same time, it can ensure that the width of the positive electrode ear 2 is not too large to affect die cutting, thereby improving the die cutting yield.

[0034] In some embodiments, the width c of the negative electrode tab 3 and the length a of the large surface satisfy: 0.35≤c / a≤0.50.

[0035] By controlling the ratio of the width of the negative electrode ear 3 to the length a of the large surface of the electrode group 1 within the range of 0.35 to 0.50, it can be ensured that when the current of the electrode group 1 along the entire width direction flows toward the negative electrode ear 3 along the length direction of the battery cell, the heat at the root of the negative electrode ear 3 will not be excessively concentrated (the ratio of the width of the negative electrode ear 3 to the width of the electrode group 1 is too small) and cause the temperature of the negative electrode ear 3 to rise too high, ensuring that the temperature of the entire battery cell is evenly transferred on the large surface and the negative electrode ear 3, avoiding the temperature rise or unbalanced temperature transfer caused by overcurrent inside the battery cell due to unreasonable size design, resulting in excessive local temperature and affecting the overall performance of the battery cell. At the same time, it can ensure that the width of the negative electrode ear 3 is not too large to affect die cutting, thereby improving the die cutting yield.

[0036] In some embodiments, the length a of the large surface satisfies: 20 mm ≤ a ≤ 100 mm.

[0037] In some embodiments, the battery cell further comprises an electrode sheet 4 and a packaging film 5. Two electrode sheets 4 are provided, which are respectively welded to the positive electrode tab 2 and the negative electrode tab 3. The packaging film 5 is sealed and coated on the outer surface of the electrode group 1, and one end of the electrode sheet 4 is exposed from the packaging film 5.

[0038] The packaging film 5 plays a role in protecting the internal battery core materials. In some embodiments, the packaging film 5 is an aluminum-plastic film.

[0039] In some embodiments, an insulating member 6 is also included on the electrode sheet 4, one end of the electrode sheet 4 is exposed to the packaging film 5, the packaging film 5 and the insulating member 6 are sealed and connected by hot pressing, and the other end of the electrode sheet 4 is welded to the internal tab.

[0040] The two ends of the electrode group 1 are respectively welded with electrode sheets 4 to realize the extraction of current. The electrode sheet 4 plays a conductive role, one end is led out to extract the current and the other end is welded to the internal pole ear. When the packaging film 5 is sealed, the insulating member 6 located on the electrode sheet 4 is hot-pressed and fused with the insulating member 6 to achieve a sealed connection, thereby achieving the sealing of the battery cell.

[0041] In some embodiments, the insulating member 6 is an injection-molded integral structure. In some embodiments, the insulating member 6 is made of insulating glue.

[0042] In some embodiments, the material of the positive electrode ear 2 is aluminum foil, and the flow coefficient is σ1,5A / mm 2 ≤σ1≤8A / mm 2 ; The material of the negative electrode ear 3 is copper foil, and the current coefficient is σ2,8A / mm 2 ≤σ2≤12A / mm 2 .

[0043] In some embodiments, the positive electrode tab 2 is disposed at one end of the electrode group 1 and located at the center along the width direction of the electrode group 1 , and the negative electrode tab 3 is disposed at the other end of the electrode group 1 and located at the center along the width direction of the electrode group 1 .

[0044] In some embodiments, the positive electrode tab 2 and the negative electrode tab 3 are located on the same side of the electrode group 1 .

[0045] In order to verify the technical effect of the battery cell provided by the present invention, specific experimental cases and comparative cases are provided below. The samples are DOE battery cells of different sizes, and actual temperature rise tests are performed on them. The temperature tests are performed at five points, A, B, C, D, and E. Figure 4 As shown. Point A is located at the geometric center of the electrode group 1. Points A, B, and C are collinear and located on the center line along the length direction of the electrode group 1. Along the width direction of the electrode group 1, the distance between points B and C on both sides of the electrode group 1 is 1 / 4 of the width. Point D and Point E are located at the geometric centers of the positive ear 2 and the negative ear 3, respectively.

[0046] The test results are shown in Table 1 and Table 2. Except for the parameters in the table which are variables, the other conditions are the same.

[0047] Table 1:

[0048]

[0049] Table 2:

[0050]

[0051] Table 3:

[0052]

[0053] From Table 1 we can see that:

[0054] In Case 1 and Case 2, the value of mbt1 / nct2 is less than the specified lower limit of 1.5, and the temperature rise on the positive electrode ear 2 side is too high.

[0055] In Case 7, the value of mbt1 / nct2 is greater than the specified upper limit of 2.2, and the temperature rise on the 3rd side of the negative electrode ear is too high.

[0056] In cases 3 to 6, 1.5≤mbt1 / nct2≤2.2 is satisfied, and the overall temperature of the battery cell is relatively balanced. Therefore, the design of the tab size has a significant impact on the temperature rise of each part of the entire battery cell. Satisfying 1.5≤mbt1 / nct2≤2.2 can ensure that the temperature of the entire battery cell is uniform in the positive and negative tabs 3 and the large surface, and the temperature transfer is balanced, and finally the temperature of each part of the entire battery cell is equivalent.

[0057] From Table 2 we can see that:

[0058] In Case 8, the b / a value is less than the specified lower limit of 0.25, the width of the positive electrode ear 2 is too small, and the temperature of the large surface of the battery cell and the side of the positive electrode ear 2 is too high.

[0059] In Case 12, the value of b / a is greater than the specified upper limit of 0.35, which means that the overall temperature of the battery cell is relatively balanced, but the positive electrode ear 2 is wider and the die-cutting yield is low.

[0060] In Case 9 to Case 11, the following conditions are satisfied: 0.25≤b / a≤0.35, the overall temperature of the battery cell is relatively balanced, the width of the positive electrode ear 2 is appropriate, and the die-cutting is not affected, and the die-cutting yield is high.

[0061] From Table 3 we can see that:

[0062] In Case 15, the c / a value is less than the specified lower limit of 0.35, the width of the negative electrode ear 3 is too small, and the temperature of the large surface of the battery cell and the side of the negative electrode ear 3 is too high.

[0063] In Case 19, the c / a value is greater than the specified lower limit of 0.50, which means that the overall temperature of the battery cell is relatively balanced, but the negative electrode ear 3 is wide and the die-cutting yield is low.

[0064] In Case 16 to Case 18, the following conditions are met: 0.35≤c / a≤0.50, the overall temperature of the battery cell is relatively balanced, the width of the positive electrode ear 2 is appropriate, and the die-cutting is not affected, and the die-cutting yield is high.

[0065] 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.

[0066] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be described in detail here.

[0067] 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: A pole group, wherein the pole group is provided with internal pole ears, and the internal pole ears include a positive pole ear and a negative pole ear respectively provided at two ends of the pole group; The width of the positive electrode ear is b, in mm, the number of electrode layers of the positive electrode ear is m, and the thickness of the electrode foil of the positive electrode ear is t1, in μm; The width of the negative electrode ear is c, in mm, the number of electrode sheet layers of the negative electrode ear is n, and the thickness of the electrode sheet foil of the negative electrode ear is t2, in μm; Satisfies: 1.5≤mbt1 / nct2≤2.

2.

2. The battery cell according to claim 1, characterized in that: The number m of pole sheet layers of the positive electrode tab satisfies: 20≤m≤55; the thickness t1 of the pole sheet foil of the positive electrode tab satisfies: 12μm≤t1≤13μm.

3. The battery cell according to claim 1 or 2, characterized in that: The number of electrode sheet layers n of the negative electrode ear satisfies: 21≤n≤56; the thickness t2 of the electrode sheet foil of the negative electrode ear satisfies: 4.5μm≤t2≤6μm.

4. The battery cell according to claim 1 or 2, characterized in that: The pole group has two large surfaces arranged opposite to each other, the length of the large surfaces is a, in mm, 0.25≤b / a≤0.

35.

5. The battery cell according to claim 4, characterized in that: The width c of the negative electrode ear and the length a of the large surface satisfy: 0.35≤c / a≤0.

50.

6. The battery cell according to claim 4, characterized in that: The length a of the large surface satisfies: 20mm≤a≤100mm.

7. The battery cell according to claim 1 or 2, characterized in that: Also includes: An electrode sheet, wherein two electrode sheets are provided and are respectively welded to the positive electrode ear and the negative electrode ear; A packaging film is sealed and coated on the outer surface of the electrode group, and one end of the electrode sheet is exposed from the packaging film.

8. The battery cell according to claim 7, characterized in that: It also includes an insulating member arranged on the electrode sheet, one end of the electrode sheet is exposed from the packaging film, the packaging film and the insulating member are sealed and connected by hot pressing fusion, and the other end of the electrode sheet is welded to the internal tab.

9. The battery cell according to claim 1 or 2, characterized in that: The positive electrode ear is made of aluminum foil, and the flow coefficient is σ1,5A / mm 2 ≤σ1≤8A / mm 2 ; The negative electrode ear is made of copper foil, and the current coefficient is σ2,8A / mm 2 ≤σ2≤12A / mm 2 .

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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