Battery cell and battery pack

Abstract

The utility model relates to the technical field of batteries, in particular to a single battery and a battery pack. The battery pack comprises one or more single batteries, each single battery comprises a battery cell and a shell, the battery cell is provided with a tab, the shell is used for containing the battery cell and provided with a pole, the tab is connected to the pole, and the ratio S / V of the overcurrent area S of the pole to the volume V of the shell is larger than or equal to 0.5 * 10 <-4 >. According to the present invention, the switching sheet is canceled, and the pole is directly connected with the tab, such that the energy density of the battery is improved, the number of the heating components is reduced, the ratio of the overcurrent area S of the pole to the volume V of the battery is set in a certain range, the overcurrent capability of the pole is improved, and the overheating problem is relieved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a battery cell and a battery pack. Background Technology

[0002] The increasing demand for fast charging has placed higher requirements on battery capacity and current, while also demanding longer battery life and smaller size, thus requiring higher energy density. In related technologies, the battery cell's tabs are connected to the terminals via adapters, and then to a load or charging device for charging and discharging. As battery capacity and current increase, the heat generated by the terminals and adapters will increase, posing a safety hazard. Furthermore, current technologies cannot further improve energy density. Utility Model Content

[0003] The embodiments of this application provide a battery cell and a battery pack to improve the energy density and overcurrent capacity of the battery, while also addressing the battery heat generation problem.

[0004] In a first aspect, embodiments of this application provide a single battery cell, comprising:

[0005] The battery cell has tabs.

[0006] A housing for containing the battery cell and having terminals provided;

[0007] The electrode tab is connected to the electrode post, and the ratio of the current-flow area S of the electrode post to the volume V of the outer casing, S / V, is ≥ 0.5 × 10⁻⁶. -4 .

[0008] In one embodiment of this application, the battery cell includes a positive electrode active material, which comprises an olivine-type compound with a density of 5 × 10⁻⁶. -4 ≥S / V≥0.5×10 -4 .

[0009] In one embodiment of this application, the olivine-type compound comprises lithium iron phosphate.

[0010] In one embodiment of this application, the battery cell includes a positive electrode active material, which comprises a layered compound with a density of 6×10⁻⁶. -4 ≥S / V≥0.5×10 -4 .

[0011] In one embodiment of this application, the layered compound includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, high nickel oxide, lithium-rich manganese oxide, and lithium manganese oxide.

[0012] In one embodiment of this application, 3×10 4 mm3 ≤V≤15×10 8 mm 3 .

[0013] In one embodiment of this application, 50mm 2 ≤S≤2000mm 2 .

[0014] In one embodiment of this application, the electrode extends along the first direction and passes through the outer casing. The electrode has a first end face perpendicular to the first direction, and the first end face faces the side of the battery cell where the tab is provided for connection with the tab.

[0015] The projection of the electrode along the first direction falls within the range of the first end face.

[0016] In one embodiment of this application, the battery cell further includes:

[0017] An insulating element is disposed between the housing and the electrode post, and has at least two protrusions, the two protrusions being disposed opposite to each other, and a first end face being located between the two protrusions; the first end face is located away from the battery cell in a first direction relative to the protrusions, so as to form a receiving space between the two protrusions, the receiving space being used to receive the electrode tab.

[0018] Secondly, embodiments of this application provide a battery pack including battery cells as described in any of the embodiments of the first aspect.

[0019] The beneficial effects of the embodiments of this application are as follows:

[0020] This application improves the energy density of the battery and reduces the number of heat-generating components by eliminating the adapter piece and directly connecting the terminal post and the tab. In addition, the ratio of the current-carrying area S of the terminal post to the volume V of the battery is set within a certain range to improve the current-carrying capacity of the terminal post and alleviate the overheating problem. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the external structure of a battery cell provided in an embodiment of this application;

[0023] Figure 2 This is a schematic diagram of the internal structure of a battery cell provided in an embodiment of this application;

[0024] Figure 3 This is a schematic diagram of the structure of the first end face of the pole provided in an embodiment of this application.

[0025] Figure label:

[0026] 1. Outer shell; 11. Housing; 12. End cap; 2. Terminal post; 21. First end face; 3. Cell; 31. Tab; 4. Insulator; 41. Protrusion; 5. Accommodation space; X, First direction. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0028] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0029] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] In this application, "multiple" refers to two or more (including two), and similarly, "multiple groups" refers to two or more (including two), and "multiple pieces" refers to two or more (including two).

[0031] In this application, the battery cell may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application are not limited to these. The battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited to these. Battery cells are generally divided into three types according to their packaging method: cylindrical battery cells, cuboid / square battery cells, and pouch battery cells, and the embodiments of this application are not limited to these.

[0032] The development of battery technology must take into account multiple design factors, such as performance parameters like energy density, cycle life, discharge capacity, and charge / discharge rate, as well as battery safety.

[0033] The increasing demand for fast charging has placed higher requirements on battery capacity and current, while also requiring batteries to maintain high endurance and small size, thus also placing higher requirements on battery energy density.

[0034] In related technologies, a battery cell includes a battery cell, an electrolyte, and a casing. The battery cell generally consists of a positive electrode, a negative electrode, and an insulating separator. The casing encloses the battery cell and electrolyte. The battery cell primarily functions by the movement of metal ions between the positive and negative electrodes. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector. The current collector without the positive active material layer protrudes beyond the current collector with the positive active material layer, and serves as the positive electrode tab. Similarly, the negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector. The current collector without the negative active material layer protrudes beyond the current collector with the negative active material layer, and serves as the negative electrode tab.

[0035] The battery cell has multiple positive electrode tabs, which are formed into a single unit through stacking or flattening. Similarly, it has multiple negative electrode tabs, which are formed into a single unit through stacking or flattening. In addition, each battery cell includes terminals and adapter plates. The adapter plates connect the tabs to the terminals, and the terminals pass through the outer casing to connect to an external load or charger. The battery cell achieves input and output current through the tabs, adapter plates, and terminals.

[0036] Terminals and adapters are typically made of metal, such as copper or aluminum. When current flows through these metal components, heat is generated. As battery capacity and current increase, the heat generated by the terminals and adapters will also increase, posing a safety hazard. Furthermore, current technologies struggle to further improve battery energy density.

[0037] In view of this, this application provides a battery cell and a battery pack to improve the energy density and overcurrent capacity of the battery, meet the fast charging requirements, and at the same time, take into account the battery heat generation problem and ensure the safety of the battery.

[0038] Figure 1 A schematic diagram of the external structure of a single battery cell is shown, such as... Figure 1 As shown, the battery cell includes a casing 1.

[0039] The outer casing 1 includes a housing 11 and an end cap 12. The housing 11 has an opening, and the end cap 12 covers the opening, thereby forming a closed space inside the housing 1.

[0040] The outer casing 1 is provided with a pole post 2. Optionally, the pole post 2 is provided on the end cover 12.

[0041] Figure 2 This diagram shows the internal structure of a battery cell with the end cap 12 open. For ease of observation, the casing 11 is omitted. Figure 2 As shown, the battery also includes a battery cell 3, which is disposed inside the housing 1. The battery cell 3 is provided with tabs 31. Optionally, the tabs 31 are disposed on the side of the battery cell 3 facing the end cover 12.

[0042] Among them, the tab 31 is connected to the pole post 2, and the ratio of the flow area S of the pole post 2 to the volume V of the outer casing 1, S / V, is ≥ 0.5 × 10⁻⁶. -4 .

[0043] like Figure 1 As shown, pole post 2 extends along the first direction X, and the minimum cross-sectional area of ​​pole post 2 in the direction perpendicular to the first direction X is the flow area S of pole post 2.

[0044] The battery cell 3, which is used for electrochemical reactions, and the electrolyte are filled inside the casing 1. Therefore, the volume V of the casing 1 can be regarded as the volume of the battery. Generally speaking, the larger the battery capacity, the larger the volume, the larger the current generated, and the greater the heat generated in the adapter and terminal 2.

[0045] The technical solution provided in this application embodiment directly connects the terminal post 2 and the tab 31 by eliminating the adapter piece, thereby improving the energy density of the battery and reducing the number of heat-generating components. In addition, the ratio of the current-carrying area S of the terminal post 2 to the volume V of the battery is set within a certain range to improve the current-carrying capacity of the terminal post 2 and alleviate the overheating problem.

[0046] In some embodiments, the cell 3 includes a positive electrode active material. When the positive electrode active material includes an olivine-type compound, the ratio S / V of the current-carrying area S of the electrode post 2 to the volume V of the casing 1 satisfies: 5 × 10⁻⁶. -4 ≥S / V≥0.5×10 -4 .

[0047] In some embodiments, the olivine-type compound includes lithium iron phosphate.

[0048] In some embodiments, when the battery cell 3 includes a positive electrode active material, and the positive electrode active material includes a layered compound, the ratio S / V of the current-carrying area S of the electrode post 2 to the volume V of the casing 1 satisfies: 6 × 10⁻⁶. -4 ≥S / V≥0.5×10 -4 .

[0049] In some embodiments, the layered compound includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, high-nickel oxide, lithium-rich manganese oxide, and lithium manganese oxide.

[0050] In some embodiments, the volume V of the outer casing 1 satisfies: 3 × 10 4 mm 3 ≤V≤15×10 8 mm 3 .

[0051] In some embodiments, the flow area S of the electrode 2 satisfies: 50mm 2 ≤S≤2000mm 2 .

[0052] By setting the overcurrent area S of the terminal 2, the volume V of the housing 1, and the ratio S / V of the overcurrent area S of the terminal 2 to the volume V of the housing 1, the problem of overheating of the terminal 2 due to insufficient overcurrent is alleviated. At the same time, the problem of inconvenient assembly caused by the excessive size of the terminal 2 is avoided, and the problem of the terminal 2 occupying too much area on the surface of the housing 1 is avoided, which would cause the installation position of other components to be squeezed, such as making it impossible to set the traceability code of the explosion-proof valve and the battery cell.

[0053] like Figure 1 and Figure 2 As shown, the pole post 2 extends along the first direction X and passes through the outer casing 1.

[0054] The pole post 2 has a first end face 21 perpendicular to the first direction X. When the housing 1 and the cell 3 are assembled, the first end face 21 faces the side of the cell 3 where the tab 31 is provided, so that the first end face 21 can be connected to the tab 31.

[0055] The projection of the tab 31 along the first direction X falls within the range of the first end face 21, so that the first end face 21 of the pole post 2 fully covers the tab 31, avoiding the problem of overheating at the connection point due to the small connection area between the pole post 2 and the tab 31.

[0056] To improve the safety of individual battery cells, such as Figure 3 As shown, a battery cell generally also includes an insulating component 4, which is disposed between the outer casing 1 and the terminal post 2, and is used to insulate and isolate the outer casing 1 and the terminal post 2.

[0057] As an example of this application, a through hole (not shown in the figure) is provided on the end cap 12, the pole post 2 passes through the through hole along the first direction X, and the insulating member 4 covers the inner wall of the through hole and the side surface of the end cap 12 facing the cell 3.

[0058] The insulating element 4 is configured to have at least two protrusions 41, which are arranged opposite to each other, with a first end face 21 located between the two protrusions 41. Figure 3 As shown, the first end face 21 is rectangular, and two protrusions 41 are set on two opposite sides of the rectangle. The length of the protrusions 41 is greater than the side length of the rectangle to which they correspond, so that the first end face 21 is embedded between the two protrusions 41.

[0059] The first end face 21 is away from the battery cell 3 along the first direction X relative to the protrusion 41, so that the distance between the first end face 21 and the battery cell 3 is greater than the distance between the protrusion 41 and the battery cell 3, thereby forming a receiving space 5 between the two protrusions 41, and the receiving space 5 is used to receive the tab 31.

[0060] In other words, the first end face 21 is recessed relative to the protrusion 41 along the first direction X toward the outside of the outer casing 1 to avoid the tab 31, thereby improving the energy density of the battery.

[0061] In addition, the tab 31 is set in the receiving space 5. With the blocking effect of the protrusion 41, it can also prevent the tab 31 from falling over or folding back into the gap of the electrode of the cell 3, which would cause a short circuit problem, thereby further improving the safety of the battery cell.

[0062] In another aspect, embodiments of this application provide a battery pack including battery cells as provided in any of the foregoing embodiments.

[0063] The battery pack mentioned in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery pack mentioned in this application may include battery modules, pouch cells, or box-type batteries, etc.

[0064] The battery pack provided in this application embodiment has higher energy density and higher overcurrent capacity due to the presence of the battery cells provided in the aforementioned embodiments, and the terminal 2 is less prone to overheating, thus providing higher safety.

[0065] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A battery cell, characterized in that, include: The battery cell has tabs. A housing for containing the battery cell and having terminals provided; The electrode tab is connected to the electrode post, and the ratio of the current-flow area S of the electrode post to the volume V of the outer casing, S / V, is ≥ 0.5 × 10⁻⁶. -4 .

2. The battery cell according to claim 1, characterized in that, The battery cell includes a positive electrode active material, which comprises an olivine-type compound and has a structure of 5×10⁻⁶. -4 ≥S / V≥0.5×10 -4 .

3. The battery cell according to claim 2, characterized in that, The olivine-type compound includes lithium iron phosphate.

4. The battery cell according to claim 1, characterized in that, The battery cell includes a positive electrode active material, which comprises a layered compound with a structure of 6×10⁻⁶. -4 ≥S / V≥0.5×10 -4 .

5. The battery cell according to claim 4, characterized in that, The layered compound includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, high nickel, lithium-rich manganese-based, and lithium manganese oxide.

6. The battery cell according to any one of claims 1-5, characterized in that, 3×10 4 mm 3 ≤V≤15×10 8 mm 3 。 7. The battery cell according to claim 6, characterized in that, 50mm 2 ≤S≤2000mm 2 。 8. The battery cell according to claim 1, characterized in that, The electrode extends along a first direction and passes through the outer casing. The electrode has a first end face perpendicular to the first direction. The first end face faces the side of the battery cell where the tab is provided for connection with the tab. The projection of the electrode along the first direction falls within the range of the first end face.

9. The battery cell according to claim 8, characterized in that, The battery cell also includes: An insulating element is disposed between the outer shell and the pole post, and is provided with at least two protrusions, the two protrusions being disposed opposite to each other, and the first end face being located between the two protrusions; The first end face is positioned away from the cell along the first direction relative to the protrusion to form a receiving space between the two protrusions, the receiving space being used to receive the tab.

10. A battery pack, characterized in that, Includes the battery cell as described in any one of claims 1-9.

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