Battery cell, battery module and electronic device

Abstract

The application belongs to the technical field of batteries, and discloses a battery cell, a battery module and an electronic device. The battery cell comprises an electrode assembly, a protective shell, a battery cell tab and a thermal expansion piece, the electrode assembly is placed in a battery cell shell, the protective shell is arranged on the lower wall of a battery cell cover plate, the protective shell has a containing cavity, one end of the battery cell tab is connected to the electrode assembly, the other end of the battery cell tab penetrates through the protective shell and is connected to a pole of the battery cell cover plate, the battery cell tab comprises an extension part arranged in the protective shell and capable of extending and retracting, and the thermal expansion piece is arranged in the protective shell, and when the temperature exceeds a preset temperature, the thermal expansion piece can expand and press the extension part, so that the length of the extension part is reduced. The battery cell can adapt to different ambient temperatures, thereby adjusting the direct current resistance of the battery cell, ensuring the charging and discharging performance of the battery cell under different ambient temperatures, and being safer to use.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a battery cell, battery module, and electronic device. Background Technology

[0002] With the development of new energy battery technology, higher requirements have been placed on the fast charging and fast discharging performance of batteries. When the battery cell is charged and discharged in a high-temperature environment, or when the cell temperature rises due to high-rate charging and discharging, it is necessary to reduce the DCR (Directive Current Resistance) to reduce the temperature rise. However, when the cell is charged and discharged in a low-temperature environment, the cell itself needs to maintain a higher temperature to improve the battery's capacity retention rate and energy retention rate. Therefore, a relatively high DCR is actually beneficial to improving cell performance.

[0003] In existing technologies, manufacturers can optimize cell DCR by improving the electronic and ionic conductivity of the electrodes, or by optimizing the connection methods between structural components. However, the optimized cell DCR is a fixed value and cannot simultaneously meet the low DCR requirements during high-temperature charging and discharging, and the high DCR requirements during low-temperature charging and discharging. Furthermore, during battery charging and discharging, the temperature rise at the connection between the cell tabs and terminals is significant, and this heat is difficult to dissipate, leading to excessively high localized temperatures within the cell and posing certain safety hazards.

[0004] Therefore, there is an urgent need to improve existing technologies to provide a new type of battery cell, thereby solving the aforementioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a battery cell that can adapt to different ambient temperatures to adjust the DC resistance of the battery cell, ensuring the charging and discharging performance of the battery cell under different ambient temperatures, and making it safer to use.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] The battery cell includes an electrode assembly, a battery tab, and a thermal expansion member. One end of the battery tab is connected to the electrode assembly, and the other end is connected to the electrode post. The battery tab includes a telescopic portion that can extend and retract, and the conductive path of the battery tab passes through the telescopic portion. The thermal expansion member is in thermal contact with the battery cell body. When the battery cell body exceeds a preset temperature, the thermal expansion member can expand along the telescopic direction of the telescopic portion, and the expansion path of the thermal expansion member at least partially overlaps with the telescopic portion.

[0008] Optionally, the telescopic part includes multiple bent portions that are connected end to end and bent at a preset angle along a preset crease. When the thermal expansion member squeezes the telescopic part, two adjacent bent portions change from being connected end to end to being in surface contact. Alternatively, the telescopic part includes multiple telescopic segments that can slide relative to each other along the telescopic direction. The thermal expansion member can squeeze the telescopic part along the telescopic direction.

[0009] Optionally, an elastic element is also sandwiched between two adjacent bends.

[0010] Optionally, an adapter piece is welded to the lower end of the aforementioned pole post, and the aforementioned bent portion at the uppermost end is attached to the aforementioned adapter piece.

[0011] Optionally, the battery cell further includes a battery cell cover plate, a protective shell is provided on the bottom surface of the battery cell cover plate, the thermal expansion member is provided at the lower end of the protective shell, and the battery cell tab further includes an extension portion passing through the thermal expansion member, the extension portion being connected to the electrode assembly.

[0012] Optionally, the lower wall of the protective shell is provided with a connecting seam, and the extension is inserted into the connecting seam.

[0013] Optionally, the aforementioned battery cell tabs include a positive tab and a negative tab, and two protective shells and thermal expansion elements are provided in a one-to-one correspondence, with the positive tab passing through one of the protective shells and the negative tab passing through the other.

[0014] Optionally, the aforementioned thermal expansion component is any one of a thermal expansion airbag, an epoxy resin component, an acrylic component, or a silicone rubber component.

[0015] Another object of the present invention is to provide a battery module comprising battery cells as described in any of the above embodiments. This battery module's charge / discharge performance is unaffected by ambient temperature, making it safer and more reliable to use.

[0016] Another object of the present invention is to provide an electronic device comprising the battery module described above. When powered by the battery module, this electronic device exhibits better charging and discharging performance, is safer and more reliable in use, and is suitable for various ambient temperatures.

[0017] Beneficial effects:

[0018] The battery cell of this invention features a protective shell beneath the cell cover. Inside the protective shell are a thermal expansion element and a telescopic portion for the cell's tabs. When the ambient temperature of the thermal expansion element exceeds a preset temperature, the element expands, compressing the telescopic portion and causing it to deform and shorten. Simultaneously, the path of current flowing through the electrode assembly via the cell's tabs and terminals during charging and discharging is shortened, resulting in a smaller resistance of the cell's tabs. This reduces the temperature rise during charging and discharging, as well as the heat generated by the tabs, ensuring safe operation of the battery cell. Furthermore, the degree of expansion of the thermal expansion element is temperature-dependent; higher temperatures result in greater expansion, greater deformation of the telescopic portion, and lower resistance. Conversely, at lower temperatures, the thermal expansion element does not deform, and the resistance of the cell's tabs remains unchanged, ensuring that the battery cell generates sufficient heat during charging and discharging to maintain its original capacity and charging / discharging performance. The battery cell in this embodiment can adapt to different ambient temperatures, thereby adjusting the DC resistance of the battery cell, ensuring the charging and discharging performance of the battery cell under different ambient temperatures, and the heat generation of the battery cell tabs is controlled, making it safer and more reliable to use. Attached Figure Description

[0019] Figure 1 This is a top view schematic diagram of the battery cell provided in a specific embodiment of the present invention;

[0020] Figure 2 This is a side view schematic diagram of a battery cell provided in a specific embodiment of the present invention;

[0021] Figure 3 This is a side view of the battery cell after it has been heated, according to a specific embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram showing the changes in the electrode tabs of the battery cell before and after heating, provided in a specific embodiment of the present invention.

[0023] Figure 5 This is a top view schematic diagram of the battery cell provided in another embodiment of the present invention;

[0024] Figure 6 This is a side view schematic diagram of the battery cell in another embodiment of the present invention.

[0025] In the picture:

[0026] 10. Electrode assembly; 20. Cell housing; 30. Protective shell; 31. Connecting seam; 40. Cell cover plate; 50. Cell tab; 51. Telescopic part; 511. Bending part; 512. Elastic element; 52. Extension part; 501. Positive tab; 502. Negative tab; 60. Thermal expansion element; 70. Adapter piece. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0028] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0030] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, 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. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0031] Please refer to Figure 1 and Figure 2In this embodiment, the battery cell includes an electrode assembly 10, a protective shell 30, a battery cell tab 50, and a thermal expansion member 60. The electrode assembly 10 is placed in the battery cell housing 20. The protective shell 30 is disposed on the lower wall of the battery cell cover plate 40 and has a receiving cavity. One end of the battery cell tab 50 is connected to the electrode assembly 10, and the other end passes through the protective shell 30 and is connected to the electrode post of the battery cell cover plate 40. The battery cell tab 50 includes a telescopic part 51 disposed within the protective shell 30 and capable of telescoping. The conductive path of the battery cell tab 50 passes through the telescopic part 51. The thermal expansion member 60... The component 60 is disposed inside the protective shell 30. The thermal expansion component 60 is in thermal contact with the battery cell body (the battery cell body is a general term for the battery cell electrode assembly 10 and the battery cell tab 50, and includes the ambient heat source where the thermal expansion component 60 is located). When the battery cell body exceeds the preset temperature, the thermal expansion component 60 can expand along the expansion and contraction direction of the expansion and contraction portion 51, and the expansion path of the thermal expansion component 60 at least partially overlaps with the expansion and contraction portion 51. The thermal expansion component 60 can expand and compress the expansion and contraction portion 51 to reduce the length of the expansion and contraction portion 51, that is, to shorten the conductive path of the expansion and contraction portion 51.

[0032] In this embodiment, the battery cell has a protective shell 30 below the battery cell cover plate 40. The protective shell 30 contains a thermal expansion member 60 and a telescopic part 51 of the battery cell tab 50. When the ambient temperature of the thermal expansion member 60 exceeds the preset temperature, the thermal expansion member 60 can expand, thereby squeezing the telescopic part 51, causing the telescopic part 51 to deform and shorten. At this time, when the electrode assembly 10 is charged and discharged through the battery cell tab 50 and the electrode post, the path through which the current passes is also shortened as the telescopic part 51 shortens. That is, the resistance of the battery cell tab 50 decreases, thereby reducing the temperature rise during the charging and discharging of the battery cell and reducing the heat generation of the battery cell tab 50, ensuring the safe operation of the battery cell. Furthermore, the degree of expansion of the thermal expansion member 60 is temperature-dependent; the higher the temperature, the greater the expansion, the greater the deformation of the expansion joint 51, and the lower the resistance. At lower temperatures, the thermal expansion member 60 does not deform, and the resistance of the cell tab 50 remains unchanged, ensuring that the cell generates sufficient heat during charging and discharging to maintain its original capacity and charging / discharging performance. In this embodiment, the cell can adapt to different ambient temperatures, thereby adjusting its DC resistance and ensuring charging / discharging performance under varying ambient temperatures. Furthermore, the heat generation of the cell tab 50 is controlled, making its use safer and more reliable.

[0033] like Figure 1 and Figure 2As shown, optionally, the thermal expansion member 60 is disposed at the lower end of the protective shell 30, and the battery cell tab 50 further includes an extension 52 passing through the thermal expansion member 60, the extension 52 being connected to the electrode assembly 10. Further, a connecting seam 31 is provided on the lower wall of the protective shell 30, and the extension 52 passes through the connecting seam 31. This configuration of the battery cell tab 50 ensures that its length meets the expansion and contraction requirements of the telescopic part 51, preventing the battery cell tab 50 from breaking when the thermal expansion member 60 expands, thus ensuring the mechanical strength and reliability of the battery cell tab 50.

[0034] contrast Figure 1 and Figure 2 During operation, when the temperature at the cell tab 50 rises, the thermal expansion member 60, located inside the protective shell 30, absorbs heat and expands, compressing the telescopic part 51 and reducing the distance between them. This shortens the electron transport path, reduces resistance and current density, and lowers overall heat generation, effectively reducing the risk of thermal runaway. Therefore, this cell can improve the stability of fast charging and fast discharging performance at high temperatures. Conversely, when the cell operates in a low-temperature environment, where the temperature is below the deformation temperature threshold of the thermal expansion member 60, the cell tab 50 is in its initial state. The overall resistance of the cell is relatively high, and the temperature rise during operation is relatively high, but it does not reach the thermal runaway temperature. This higher temperature rise helps improve the capacity and energy retention rate of the cell during low-temperature operation, ensuring normal operation.

[0035] Further, please refer to Figure 3 In this embodiment, the telescopic portion 51 includes multiple bent portions 511 connected end to end, bent along a preset crease, and arranged at a preset angle to each other. When the thermal expansion member 60 presses the telescopic portion 51, two adjacent bent portions 511 change from being connected end to end to being in surface contact. Alternatively, the telescopic portion 51 includes multiple telescopic segments that can slide relative to each other along the telescopic direction, and the thermal expansion member 60 can press the telescopic portion 51 along the telescopic direction. Specifically, in this embodiment, the telescopic portion 51 is a plurality of bent portions 511 connected end to end, and three bent portions 511 are provided, folded in a Z-shape. By setting the telescopic portion 51 as a plurality of bent portions 511, the manufacturing process of the telescopic portion 51 can be simplified. Furthermore, the telescopic portion 51 is integrally formed with the battery cell tab 50, and is formed by folding the upper half of the battery cell tab 50, thereby further simplifying the manufacturing process and reducing production costs.

[0036] In a preferred embodiment, an elastic element 512 is also sandwiched between two adjacent bends 511. The elastic element 512 can prevent two adjacent bends 511 from approaching each other when there is no force, thus separating the bends 511, and ensuring that when the thermal expansion member 60 returns to its original shape, the two adjacent bends 511 can return to their original state with a preset included angle, thus playing an elastic reset role.

[0037] pass Figure 3 The change in the telescopic portion 51 and the calculation of its resistance value reveal that, initially, the resistance of the telescopic portion 51 is Ra = ρ * 3L / (d * w); while after the thermal expansion member 60 compresses the telescopic portion 51 due to thermal expansion, the resistance of the telescopic portion 51 is Rb = ρ * 3d / (L * w); here, ρ is the resistivity of the battery tab 50, L is the length of the bent portion 511, d is the thickness of the battery tab 50, and w is the width of the battery tab 50. When the length of the battery tab 50 is greater than its thickness, it can be observed that the resistance of the telescopic portion 51 decreases after compression. Typically, the thickness d of the battery tab 50 is between 2μm and 20μm, and the length of the telescopic portion 51 only needs to exceed this value. Since the length of the tab usually far exceeds the thickness d, this will not be elaborated further here.

[0038] Furthermore, the aforementioned thermal expansion component 60 can be any one of a thermal expansion airbag, an epoxy resin component, an acrylic component, or a silicone rubber component. In this embodiment, the thermal expansion component 60 is made of a thermal expansion material and is insulating and resistant to electrolyte corrosion, which will not be elaborated further here. Since different temperature rises can cause different degrees of deformation in the thermal expansion component 60, and thus the cell resistance can be adjusted differently, the material, volume, and tab size of the thermal expansion component 60 can be designed according to actual needs. This embodiment does not impose specific limitations.

[0039] like Figure 5 As shown, in another optional embodiment, the difference from the above embodiment is that both battery tabs 50 of the battery cell are expandable and contractible. Specifically, the battery tabs 50 include a positive tab 501 and a negative tab 502. Two protective shells 30 and two thermal expansion members 60 are provided, one with the positive tab 501 inserted inside and the other with the negative tab 502 inserted inside. The thermal expansion members 60 inside the two protective shells 30 can be the same or different. Alternatively, the two protective shells 30 can be integrally formed, ensuring that the thermal expansion members 60 can simultaneously compress the expansion portions 51 of the positive tab 501 and the negative tab 502. This embodiment does not impose specific limitations, thereby further improving the applicability of the battery tabs 50 at different temperatures and ensuring that the resistance of the battery cell is more sensitive to temperature changes.

[0040] Please continue to refer to this. Figure 6In another optional embodiment, the battery cell tab 50 is indirectly connected to the electrode post via an adapter piece 70. Specifically, the adapter piece 70 is welded to the lower end of the electrode post, and the uppermost bent portion 511 is attached to the adapter piece 70. The adapter piece 70 ensures that the bent portion 511 is firmly connected to the electrode post, preventing the battery cell tab 50 from falling off and ensuring the reliability of the battery cell. The connection method between the adapter piece 70 and the bent portion 511 can be riveting, welding, insertion, etc., and this embodiment does not impose any restrictions. During installation, the battery cell tab 50 is first pre-welded to the electrode assembly 10, then the battery cell tab 50 is passed through the connecting seam 31 and welded to the adapter piece 70. The adapter piece 70 is then welded to the lower end of the electrode post of the battery cell cover plate 40. Finally, the upper half of the battery cell tab 50 is folded to form the telescopic portion 51. The number of folding layers can be set according to the resistance value adjustment requirements, which will not be elaborated here.

[0041] This embodiment also provides a battery module comprising battery cells as described in any of the above solutions. The charging and discharging performance of this battery module is unaffected by ambient temperature, making it safer and more reliable to use.

[0042] This embodiment also provides an electronic device that includes the battery module described above. When powered by the battery module, this electronic device exhibits better charging and discharging performance, is safer and more reliable, and is suitable for various ambient temperatures.

[0043] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A battery cell, characterized in that, include: Electrode assembly (10); A battery tab (50) is provided, with one end connected to the electrode assembly (10) and the other end connected to the electrode post. The battery tab (50) includes a telescopic part (51) that can extend and retract, and the conductive path of the battery tab (50) passes through the telescopic part (51). Thermal expansion member (60) is in thermal contact with the battery cell body. When the battery cell body exceeds a preset temperature, the thermal expansion member (60) can expand along the expansion and contraction direction of the expansion and contraction part (51), and the expansion path of the thermal expansion member (60) at least partially overlaps with the expansion and contraction part (51). The telescopic part (51) includes a plurality of bent parts (511) that are connected end to end and bent into a preset angle along a preset crease. When the thermal expansion member (60) squeezes the telescopic part (51), two adjacent bent parts (511) change from being connected end to end to being in surface contact.

2. The battery cell according to claim 1, characterized in that, An elastic element (512) is also sandwiched between two adjacent bends (511).

3. The battery cell according to claim 1, characterized in that, The lower end of the pole is welded with an adapter plate (70), and the uppermost bent part (511) is attached to the adapter plate (70).

4. The battery cell according to claim 1, characterized in that, The battery cell also includes a battery cell cover plate (40), a protective shell (30) is provided on the bottom surface of the battery cell cover plate (40), the thermal expansion member (60) is provided at the lower end inside the protective shell (30), and the battery cell tab (50) also includes an extension (52) passing through the thermal expansion member (60), the extension (52) being connected to the electrode assembly (10).

5. The battery cell according to claim 4, characterized in that, The lower wall of the protective shell (30) is provided with a connecting seam (31), and the extension (52) passes through the connecting seam (31).

6. The battery cell according to claim 4 or 5, characterized in that, The battery cell tab (50) includes a positive tab (501) and a negative tab (502). The protective shell (30) and the thermal expansion member (60) are provided in two corresponding positions. The positive tab (501) is inserted inside one of the protective shells (30), and the negative tab (502) is inserted inside the other.

7. The battery cell according to any one of claims 1-5, characterized in that, The thermal expansion component (60) is any one of a thermal expansion airbag, an epoxy resin component, an acrylate component, or a silicone rubber component.

8. A battery module, characterized in that, Includes the battery cell as described in any one of claims 1-7.

9. An electronic device, characterized in that, Includes the battery module as described in claim 8.

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