Lithium ion battery cell and battery pack

Abstract

The utility model provides a lithium ion battery cell and a battery pack. The lithium ion battery cell comprises an outer shell; the inner shell is located in the outer shell, the outer shell and the inner shell are both cylindrical, a containing gap is formed between the outer shell and the inner shell, and a positive electrode cover plate and a negative electrode cover plate which are used for sealing are arranged at the two ends of the containing gap; the roll core is located in the containing gap, and the roll core is wound on the inner shell; the technical scheme provided by the utility model at least has the beneficial effects that the explosion-proof valve is arranged on the inner shell, and the distance from the explosion-proof valve to each part in the battery cell is far smaller than the distance from the explosion-proof valve to the farthest leakage point in the battery cell in the prior art; and the distance difference between the explosion-proof valve on the inner shell and each part in the battery cell is small, so that when the battery cell is in thermal runaway, the efficiency of discharging high-pressure gas from the explosion-proof valve of the inner shell is higher, thermal runaway management is better carried out, and heat spreading is reduced.

Description

Technical Field

[0001] This application relates to the technical field of lithium batteries, and particularly to a lithium-ion battery cell and a battery pack. Background Art

[0002] Cylindrical lithium-ion batteries have advantages such as large monomer energy density, high consistency, and high production efficiency, and are widely used in fields such as new energy passenger vehicles, electric two-wheel vehicles, and electric tools. Under the background of carbon peaking and carbon neutrality, new energy passenger vehicles have developed rapidly, and the requirements for the charging speed and cycle life warranty of vehicle-grade power batteries for battery packs have gradually increased.

[0003] Existing lithium-ion battery cells use carbonate organic solvents, whose viscosity increases and conductivity decreases at low temperatures, resulting in a decline in discharge performance at low temperatures. At the same time, the organic solvents in the electrolyte are flammable and volatile, and a large amount of heat will be generated during thermal runaway, and even catch fire and explode in severe cases. The explosion-proof valve is set on the cover plate at the top of the battery cell. When thermal runaway occurs at the bottom of the battery cell, the heat dissipation path is too long, resulting in slow heat dissipation and inability to discharge heat in time, which is likely to cause safety problems. Summary of the Utility Model

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present utility model is to provide a lithium-ion battery cell and a battery pack, which are used to solve the problem that when thermal runaway occurs at the bottom of the battery cell, the heat dissipation path of the explosion-proof valve set on the cover plate at the top of the battery cell is too long, resulting in slow heat dissipation and inability to discharge heat in time.

[0005] To achieve the above purpose and other related purposes, the present utility model provides a lithium-ion battery cell, including:

[0006] An outer housing;

[0007] An inner housing, the inner housing is located inside the outer housing, both the outer housing and the inner housing are cylindrical, a receiving gap is formed between the outer housing and the inner housing, and a positive electrode cover plate and a negative electrode cover plate for sealing are provided at both ends of the receiving gap;

[0008] A wound core, the wound core is located in the receiving gap, and the wound core is wound around the inner housing;

[0009] Wherein, an explosion-proof valve is further provided on the inner housing.

[0010] Optionally, the explosion-proof valve is located at the axial middle of the inner housing.

[0011] Optionally, a weak area is provided on the inner housing to form the explosion-proof valve;

[0012] The wall thickness of the inner housing is D1, the wall thickness of the weak area is D2, and D2 < D1.

[0013] Optionally, a first guiding groove is further provided on the weak area, and the first guiding groove is arranged along the height direction of the inner housing.

[0014] Optionally, a second guiding groove is further provided on the weak area. One end of the second guiding groove is connected to the boundary of the weak area, and the other end of the second guiding groove is connected to the first guiding groove.

[0015] Optionally, both the positive electrode cover plate and the negative electrode cover plate are of an annular structure, and a liquid injection hole is provided on the positive electrode cover plate.

[0016] Optionally, the wall thickness of the inner housing is 0.05 mm to 3 mm.

[0017] Optionally, both the positive electrode cover plate and the negative electrode cover plate are detachably and sealingly connected to both ends of the accommodation gap.

[0018] The present application further provides a battery pack, including the lithium-ion battery cell as described above, and further including:

[0019] A temperature regulation component, the temperature regulation component includes a conveying pipe group, and the conveying pipe group is arranged through the inner housing of each battery cell.

[0020] Optionally, the height of the outer housing is H1, and the outer diameter of the outer housing is D3;

[0021] Wherein, the H1 is greater than or equal to 50 mm and less than or equal to 200 mm;

[0022] The D3 is greater than or equal to 20 mm and less than or equal to 200 mm.

[0023] As described above, the beneficial effects brought by the technical solution in the present utility model at least include: In the present application, the explosion-proof valve is arranged on the inner housing, and the distance from the explosion-proof valve to each part inside the battery cell is much smaller than the distance from the explosion-proof valve to the farthest leakage point inside the battery cell in the prior art. The distance difference from the explosion-proof valve on the inner housing to each part inside the battery cell is small. When the battery cell is in thermal runaway, the high-pressure gas is discharged from the explosion-proof valve on the inner housing more efficiently, better thermal runaway management is carried out, and thermal spread is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Showing a vertical cross-sectional view of a battery cell according to an exemplary embodiment of the present utility model;

[0025] Figure 2 Showing a vertical and horizontal cross-sectional view of a battery cell according to an exemplary embodiment of the present utility model;

[0026] Figure 3 Showing a cross-sectional schematic view of an explosion-proof valve according to an exemplary embodiment of the present utility model;

[0027] Figure 4 Shown is a cross-sectional view of the first explosion-proof valve provided in the inner housing according to an exemplary embodiment of the present invention;

[0028] Figure 5 Shown is a cross-sectional view of the second explosion-proof valve provided in the inner housing according to an exemplary embodiment of the present invention;

[0029] Figure 6 Shown is a cross-sectional view of the third explosion-proof valve provided in the inner housing according to an exemplary embodiment of the present invention;

[0030] Figure 7 Shown is a first schematic structural view of the battery cell according to an exemplary embodiment of the present invention;

[0031] Figure 8 Shown is a second schematic structural view of the battery cell according to an exemplary embodiment of the present invention.

[0032] Description of part numbers

[0033] 1. Outer housing; 2. Inner housing; 3. Winding core; 4. Explosion-proof valve; 5. First guiding groove; 6. Second guiding groove. Detailed implementation manners

[0034] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0035] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components during actual implementation. The type, quantity, and ratio of each component during actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0036] In the following description, a large number of details are explored to provide a more thorough explanation of the embodiments of the present disclosure. However, it is obvious to those skilled in the art that the embodiments of the present disclosure can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present disclosure difficult to understand.

[0037] Please refer to Figure 1 and Figure 2The utility model provides a lithium-ion battery cell, comprising: an outer shell 1; an inner shell 2, the inner shell 2 is located inside the outer shell 1, the outer shell 1 and the inner shell 2 are both cylindrical, a receiving gap is formed between the outer shell 1 and the inner shell 2, and a positive electrode cover plate and a negative electrode cover plate for sealing are arranged at both ends of the receiving gap; a winding core 3, the winding core 3 is located in the receiving gap, and the winding core 3 is wound on the inner shell 2; wherein, an explosion-proof valve 4 is also arranged on the inner shell 2.

[0038] In one embodiment of the present application, specifically, the battery cell includes an outer shell 1, an inner shell 2 and a winding core 3, the outer shell 1 and the inner shell 2 are both circular structures, the inner shell 2 is arranged inside the outer shell 1, the outer shell 1 and the inner shell 2 are arranged concentrically, and a accommodating gap is formed between the outer shell 1 and the inner shell 2, and a positive electrode cover plate and a negative electrode cover plate for sealing are arranged at both ends of the accommodating gap. The accommodating gap is a closed annular cavity, and the accommodating gap is used to accommodate the winding core 3 (the winding core 3 is formed by winding a positive electrode sheet, a diaphragm and a negative electrode sheet), the winding core 3 is wound on the outer wall of the inner shell 2, and an explosion-proof valve 4 is arranged on the inner shell 2. The explosion-proof valve 4 on the inner shell 2 is closest to each part of the accommodating gap. When the battery cell is in thermal runaway, the high-pressure gas is discharged from the explosion-proof valve 4 of the inner shell 2 more efficiently, and the thermal runaway management is better performed to reduce the heat spread.

[0039] Furthermore, the explosion-proof valve 4 is located in the middle of the inner shell 2, and is at the same distance from the positive electrode cover plate and the negative electrode cover plate, so that the thermal runaway in various places in the accommodation gap can be discharged more quickly.

[0040] Furthermore, the inner shell 2 is a hollow structure, and when the battery cell is thermally runaway, it is easier for the high-pressure gas to be discharged from the explosion-proof valve 4 and then discharged through the internal channel of the inner shell 2 as an outlet.

[0041] See also Figure 1 and Figure 3 , a weak area is provided on the inner shell 2 to form an explosion-proof valve 4;

[0042] The wall thickness of the inner shell 2 is D1, and the wall thickness of the weak area is D2. <D1。

[0043] In one embodiment of the present application, specifically, the upper side wall of the inner shell 2 is thinned to form a weak area, the weak area is the explosion-proof valve 4, the wall thickness of the inner shell 2 is D1, the wall thickness of the weak area is D2, and the wall thickness D2 of the weak area is 0.1 to 0.9 times the wall thickness D1 of the inner shell 2.

[0044] Preferably, the wall thickness D2 of the weak area is one third of the wall thickness D1 of the inner shell 2 .

[0045] Optionally, the weak area is provided on the outer wall of the inner shell 2, that is, a groove notch is formed on the outer wall of the inner shell 2 to form a weak area; or it is provided on the inner wall of the inner shell 2, that is, a groove notch is formed on the inner wall of the inner shell 2 to form a weak area.

[0046] Preferably, the weak area is provided on the inner wall of the inner shell 2 to prevent the winding core 3 from being located at the concave notch of the weak area, which may cause the winding core 3 to be prone to phenomena such as wrinkles and bending.

[0047] Optionally, a transition area is provided between the side wall with the normal wall thickness of the inner shell 2 and the weak area. The wall thickness of the transition area gradually decreases from the side wall with the normal wall thickness towards the weak area until it transitions to the wall thickness of the weak area.

[0048] Please refer to Figure 3 、 Figure 4 、 Figure 5 and Figure 6 , in an embodiment of the present application, specifically, the shape of the weak area can be square, rectangular, oval, waist-shaped, etc. The present embodiment does not limit the shape of the weak area, and the above shapes are only for illustrative purposes.

[0049] A first guiding groove 5 is further provided on the weak area. The first guiding groove 5 is arranged along the height direction of the inner shell 2.

[0050] A second guiding groove 6 is also provided on the weak area. One end of the second guiding groove 6 is connected to the boundary of the weak area, and the other end of the second guiding groove 6 is connected to the first guiding groove 5.

[0051] In an embodiment of the present application, specifically, a first guiding groove 5 is formed on the weak area. The first guiding groove 5 is located on the side of the inner shell 2 where the weak area is formed and is arranged along the height of the inner shell 2, further reducing the resistance when the weak area releases pressure. The first guiding groove 5 plays a good guiding role; moreover, a plurality of second guiding grooves 6 are also provided on the weak area. One end of each second guiding groove 6 is connected to the boundary of the weak area, and the other end of each second guiding groove 6 is connected to the first guiding groove 5. The plurality of second guiding grooves 6 are respectively located in various directions of the weak area (for example, when the weak area is a square or rectangular structure, four second guiding grooves 6 are provided, and one end of each of the four second guiding grooves 6 is respectively located at the four corners of the weak area, and the other end of each of the four second guiding grooves 6 is respectively connected to an adjacent end of the first guiding groove 5), which is more convenient for the explosion-proof valve 4 to open, and the high-pressure gas is discharged from the explosion-proof valve 4 of the inner shell 2 more efficiently, better for thermal runaway management, and reducing heat spread.

[0052] Furthermore, the depths of the first guiding groove 5 and the second guiding groove 6 are the same.

[0053] Further, the remaining wall thickness of the first guiding groove 5 or the second guiding groove 6 provided in the weak area is D4, and the remaining wall thickness D4 is 0.1 to 0.9 times the wall thickness D2 of the weak area, preferably 0.5 times.

[0054] Further, the length of the first guiding groove 5 is 0.1 to 1 times the vertical length of the weak area, preferably 0.8 times.

[0055] In an embodiment of the present application, specifically, both the positive electrode cover plate and the negative electrode cover plate are annular structures, and a liquid injection hole is provided on the positive electrode cover plate, and the electrolyte is injected from the liquid injection hole.

[0056] The wall thickness of the inner housing 2 is 0.05 mm to 3 mm.

[0057] In an embodiment of the present application, specifically, the thicknesses of the outer housing 1, the inner housing 2, the positive electrode cover plate, and the negative electrode cover plate are all 0.05 mm to 3 mm, and preferably made of steel or aluminum as the material.

[0058] Further, the thicknesses of the outer housing 1, the inner housing 2, the positive electrode cover plate, and the negative electrode cover plate are all 0.2 mm to 0.5 mm.

[0059] The positive electrode cover plate and the negative electrode cover plate are respectively detachably and sealingly connected to both ends of the accommodation gap.

[0060] In an embodiment of the present application, specifically, the battery cell has a positive extreme and a negative extreme, the positive electrode cover plate is connected to the positive extreme of the battery cell, the negative electrode cover plate is connected to the negative extreme of the battery cell, a seal is provided between the positive electrode cover plate and the positive extreme, and a seal is also provided between the negative electrode cover plate and the negative extreme.

[0061] The present application also provides a battery pack, including the battery cell as described above, and further including:

[0062] A temperature regulation component, the temperature regulation component includes a delivery pipe group, and the delivery pipe group is arranged through the inner housing of each battery cell.

[0063] In an embodiment of the present application, specifically, a plurality of battery cells are stacked and arranged in a box to form a battery pack, and a temperature regulation component is further provided in the battery pack. The temperature regulation component includes a delivery pipe group, and the delivery pipe group delivers a coolant to reduce the temperature of the battery cells.

[0064] Further, the temperature regulation component further includes an infusion pipe group, and the infusion pipe group delivers a liquid with heat to heat the battery cells.

[0065] Optionally, the infusion pipe group and the delivery pipe group are the same pipe group, and different heating or cooling effects are achieved by delivering liquids at different temperatures.

[0066] The height of the outer housing 1 is H1, and the outer diameter of the outer housing 1 is D3;

[0067] Among them, H1 is greater than or equal to 50 mm and less than or equal to 200 mm;

[0068] D3 is greater than or equal to 20 mm and less than or equal to 200 mm.

[0069] Please refer to Figure 7 and Figure 8 , in an embodiment of the present application, specifically, because a temperature adjustment component is provided to quickly adjust the internal temperature of the battery cell, the shape and size of the battery cell can break through the previous shape limitations. The height H1 of the outer casing 1 ranges from 50 mm to 200 mm, and the diameter D3 of the outer casing 1 ranges from 20 mm to 200 mm. According to the needs of the product, it can be adjusted arbitrarily within the size range of the battery cell, and the diameter can be greater than the width, or the diameter can be less than the width.

[0070] The above embodiments merely illustrate the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A lithium-ion battery cell, characterized in that: include: outer shell; An inner shell, the inner shell is located inside the outer shell, the outer shell and the inner shell are both cylindrical, a receiving gap is formed between the outer shell and the inner shell, and a positive electrode cover plate and a negative electrode cover plate for sealing are arranged at both ends of the receiving gap; A winding core, the winding core is located in the accommodating gap and is wound on the inner shell; Wherein, an explosion-proof valve is also arranged on the inner shell.

2. A lithium-ion battery cell according to claim 1, characterized in that: The explosion-proof valve is located in the axial middle portion of the inner shell.

3. A lithium-ion battery cell according to claim 1, characterized in that: A weak area is provided on the inner shell to form the explosion-proof valve; The inner shell wall thickness is D1, the weak zone wall thickness is D2, and the D2 <D1。 4. A lithium-ion battery cell according to claim 3, characterized in that: The weak area is also provided with a first guide groove, and the first guide groove is arranged along the height direction of the inner shell.

5. A lithium-ion battery cell according to claim 4, characterized in that: The weak area is further provided with a second guide groove, one end of the second guide groove is connected to the boundary of the weak area, and the other end of the second guide groove is connected to the first guide groove.

6. A lithium-ion battery cell according to claim 1, characterized in that: The positive electrode cover plate and the negative electrode cover plate are both annular structures, and a liquid injection hole is arranged on the positive electrode cover plate.

7. A lithium-ion battery cell according to claim 1, characterized in that: The wall thickness of the inner shell is 0.05 mm to 3 mm.

8. A lithium-ion battery cell according to claim 1, characterized in that: The positive electrode cover plate and the negative electrode cover plate are both detachably sealed and connected to both ends of the accommodating gap.

9. A battery pack, characterized in that: The lithium-ion battery cell according to any one of claims 1 to 8 further comprises: A temperature regulating component includes a delivery pipe group, and the delivery pipe group is arranged through the inner shell of each battery core.

10. A battery pack according to claim 9, characterized in that: The height of the outer shell is H1, and the outer diameter of the outer shell is D3; Wherein, H1 is greater than or equal to 50 mm, and H1 is less than or equal to 200 mm; The D3 is greater than or equal to 20 mm, and the D3 is less than or equal to 200 mm.

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