Battery cell and battery pack

Abstract

The utility model relates to the technical field of battery cells, and discloses a battery cell and a battery pack, and the battery cell comprises a packaging film, at least two pole groups and external pole lugs, at least two stages of grooves are formed in the packaging film on at least one side in the thickness direction of the battery cell, the total depth of all the grooves is increased, the limitation of the depth of a single groove can be broken through, pole groups with thicker total thickness can be accommodated in all the grooves, and the capacity of the battery can be effectively improved; meanwhile, the outer surface area of the battery cell is increased through the stepped battery cell structure, the heat dissipation effect of the battery cell is improved, and the safety performance of the battery cell is guaranteed. Moreover, the tabs of all the pole groups of the battery cell are welded and connected through the external tabs, so that compared with the mode that the tabs of the pole groups on the inner side extend outwards and are welded with the tabs on the outer side, the length of the internal tabs can be reduced, the material consumption of the internal tabs is saved, the area of the pole pieces cut off when the pole pieces are cut to form the tabs is reduced, and the utilization rate of the material can be improved; and the manufacturing cost of the battery cell is reduced.

Description

Technical Field

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

[0002] Pouch batteries have advantages such as high energy density, small size, and light weight, and have a large application market. Existing pouch batteries include tabs, electrode arrays, and a sealing film. The sealing film encapsulates the electrode arrays and tabs, and then seals them using a heat-pressing process. The sealing film has grooves, and the electrode arrays are placed within these grooves. The sealing film is folded along its symmetry line to enclose and seal the electrode arrays within the sealing film. Currently, existing sealing films have only one groove on one side of the symmetry line. These grooves are formed by stamping, and due to the limited extensibility of the sealing film, the depth of a single groove is also limited, resulting in a limitation on the thickness of the pouch battery and affecting the cell capacity. Utility Model Content

[0003] In view of this, the present invention provides a battery cell and battery pack to solve the problem that the capacity of the battery cell in the prior art is affected by the limitation of the encapsulation film groove.

[0004] In a first aspect, this utility model provides a battery cell, comprising:

[0005] The encapsulation film has at least two levels of grooves on at least one side of the cell thickness direction, and the at least two levels of grooves are arranged in a stepped manner from the inside to the outside.

[0006] At least two electrode groups are stacked vertically along the thickness direction of the cell in a stepped manner and are correspondingly disposed in the groove; the ends of the electrode groups are provided with internal tabs, and the internal tabs of the upper electrode group are attached to the large surface of the lower electrode group.

[0007] The external tab includes a connecting end and an extending end. The connecting end is stepped, and the stepped surface of the connecting end is sequentially welded to all the internal tabs. One end of the extending end extends outside the encapsulation film.

[0008] Beneficial effects: This cell structure features at least two levels of grooves on the encapsulation film on at least one side of the cell's thickness direction. These grooves are formed by stamping. While maintaining the depth of individual grooves and effectively ensuring the strength of the encapsulation film around each groove, the total depth of all grooves is increased, overcoming the limitations of individual groove depth. This allows for the inclusion of thicker electrode groups within all grooves, effectively increasing battery capacity. Simultaneously, the stepped cell structure increases the outer surface area of ​​the cell, improving heat dissipation and ensuring cell safety. Furthermore, all electrode groups' tabs are welded together via external tabs. Compared to the method where the tabs of inner electrode groups extend outwards and are welded to the outer tabs, this reduces the length of the internal tabs, saving material and reducing the area of ​​electrode sheets cut away during tab formation. This improves material utilization and reduces cell manufacturing costs.

[0009] In one optional embodiment, the two ends of the electrode group are respectively provided with an internal positive electrode tab and an internal negative electrode tab, and the external electrode tab includes an external positive electrode tab and an external negative electrode tab. The external positive electrode tab is sequentially welded to all the internal positive electrode tabs, and the external negative electrode tab is sequentially welded to all the internal negative electrode tabs.

[0010] Beneficial effects: Only a positive or negative electrode tab is provided on one side of the electrode assembly. The length of the internal and negative electrode tabs can be extended as needed, increasing the welding area between the internal and external electrode tabs and improving the current carrying capacity of the battery cell.

[0011] In one optional embodiment, one end of the electrode assembly is provided with an internal positive electrode tab and an internal negative electrode tab, and the external electrode tab includes an external positive electrode tab and an external negative electrode tab. The external positive electrode tab is sequentially welded to all of the internal positive electrode tabs, and the external negative electrode tab is sequentially welded to all of the internal negative electrode tabs.

[0012] In one optional embodiment, along the thickness direction of the battery cell, the depths of each of the grooves from top to bottom are H1, H2...H... n H1≥H2……≥H n .

[0013] Beneficial effects: The depth of each level of groove is the same or decreases progressively, thereby ensuring the strength of the groove walls at each level and ensuring the sealing effect of the encapsulation film.

[0014] In one optional embodiment, the encapsulation film on at least one side of the cell thickness direction has at least three levels of grooves. Along the length direction of the cell, the distance between the end of the upper groove and the end of the lower groove is L1, and the distance between the end of the middle groove and the end of the lower groove is L2. And / or,

[0015] Beneficial effects: This design allows the stepped surface on the outer side of the encapsulation film to be controlled within a suitable length range, preventing the stepped surface area from occupying too much space after the battery cell is assembled, thus improving the overall space utilization of the battery cell and battery pack. Simultaneously, it also prevents the distance between the ends of adjacent grooves from being too short, which could affect the strength of the encapsulation film after stamping.

[0016] In one alternative embodiment, the encapsulation film on at least one side in the cell thickness direction has two levels of grooves.

[0017] In one optional embodiment, at least two levels of grooves are provided on the encapsulation film on both sides of the cell thickness direction.

[0018] Beneficial effects: This setup can further increase the number of grooves and the total depth of all grooves, thereby further increasing the capacity of the battery cell.

[0019] In one alternative embodiment, the grooves are symmetrically arranged on both sides of the cell thickness direction.

[0020] In an optional embodiment, the device further includes tab adhesive, which is disposed on the protruding end and sealed between the protruding end and the encapsulation film.

[0021] Beneficial effect: The tab adhesive and the encapsulation film are heat-sealed together so that the tab adhesive is sealed between the protruding end and the encapsulation film, preventing electrolyte leakage inside the cell.

[0022] Secondly, this utility model also provides a battery pack, including the battery cell described in any of the above descriptions. The battery pack includes the battery cell and has the same technical effects as the battery cell, which will not be repeated here. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a three-dimensional structural diagram of a battery cell according to an embodiment of the present utility model;

[0025] Figure 2 This is a schematic diagram of the electrode assembly in a battery cell according to an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the interaction between the electrode group and the external tab in a battery cell according to an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the external negative electrode tab in a battery cell according to an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the external positive electrode tab in a battery cell according to an embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram of the electrode assembly in a battery cell according to an embodiment of the present invention;

[0030] Figure 7 This is a schematic diagram of a groove on the encapsulation film in a battery cell according to an embodiment of the present invention;

[0031] Figure 8 This is a side view of a battery cell according to an embodiment of the present utility model;

[0032] Figure 9 This is a side view of another type of battery cell according to an embodiment of the present utility model.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Encapsulation film; 11. Groove; 2. Electrode assembly; 3. Internal tab; 31. Internal positive tab; 32. Internal negative tab; 4. External tab; 41. Connecting end; 42. Protruding end; 5. Tab adhesive. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0036] Will Figure 1 The x-axis is called the length direction of the battery cell, the y-axis is called the width direction of the battery cell, and the z-axis is called the thickness direction of the battery cell.

[0037] The following is combined with Figures 1 to 9 The following describes embodiments of the present invention.

[0038] According to an embodiment of the present invention, a battery cell is provided, comprising an encapsulation film 1, at least two electrode groups 2, and external tabs 4. The encapsulation film 1 has at least two levels of grooves 11 on at least one side of the battery cell's thickness direction, the grooves 11 being arranged in a stepped manner from the inside to the outside. At least two electrode groups 2 are stacked vertically along the thickness direction of the battery cell in a stepped manner and are correspondingly disposed within the grooves 11. Internal tabs 3 are provided at the ends of the electrode groups 2, with the internal tabs 3 of the upper electrode group 2 attached to the large surface of the lower electrode group 2. The external tabs 4 include a connecting end 41 and an extending end 42. The connecting end 41 is stepped, and the stepped surface of the connecting end 41 is sequentially welded to all the internal tabs 3. One end of the extending end 42 extends beyond the encapsulation film 1.

[0039] In this battery cell structure, at least two levels of grooves 11 are provided on the encapsulation film 1 on at least one side of the cell thickness direction. The grooves 11 are formed by stamping. While maintaining the depth of each individual groove 11 and effectively ensuring the strength of the encapsulation film 1 around each individual groove 11, the total depth of all grooves 11 is increased, which can overcome the limitation of the depth of a single groove 11. A thicker electrode group 2 can be accommodated in all the grooves 11, which can effectively increase the battery capacity. At the same time, the stepped cell structure increases the outer surface area of ​​the cell, which is beneficial to improving the heat dissipation effect of the cell and ensuring the safety performance of the cell. Furthermore, the tabs of all electrode groups 2 of the cell are welded together by external tabs 4. Compared with the method of extending the tabs of the inner electrode group 2 outward and welding them to the outer tabs, the length of the inner tabs can be reduced, saving the material used for the inner tabs and reducing the area of ​​the electrode sheets cut off when forming the tabs. This can improve the material utilization rate and reduce the cost of cell manufacturing.

[0040] In some embodiments, such as Figure 1 As shown, the two ends of electrode group 2 are respectively provided with internal positive electrode tabs 31 and internal negative electrode tabs 32. External electrode tabs 4 include external positive electrode tabs and external negative electrode tabs. The external positive electrode tabs are sequentially welded to all the internal positive electrode tabs 31, and the external negative electrode tabs are sequentially welded to all the internal negative electrode tabs 32, thereby achieving the connection between the inside and outside of the battery. The internal positive electrode tabs 31 and internal negative electrode tabs 32 are located at both ends of electrode group 2, and the external positive electrode tabs and external negative electrode tabs are located at both ends of electrode group 2. One end of electrode group 2 is provided with only a positive electrode tab or a negative electrode tab. The length of the internal and negative electrode tabs can be extended as needed to increase the welding area between the internal and external electrode tabs 4 and improve the current carrying capacity of the cell. The solder marks of the internal and external electrode tabs 4 extend along the width direction of electrode group 2.

[0041] Optionally, in some embodiments, the inner positive electrode tab 31 and the inner negative electrode tab 32 are respectively disposed at both ends of the electrode group 2 along its length. The long sides of both the inner positive electrode tab 31 and the inner negative electrode tab 32 extend along the width direction of the electrode group 2. The stepped surface of the connecting end 41 of the outer positive electrode tab overlaps with and is welded to the inner positive electrode tab 31, and the stepped surface of the connecting end 41 of the outer negative electrode tab overlaps with and is welded to the inner negative electrode tab 32. The connecting end 41 is stepped, and the protruding end 42 extends horizontally.

[0042] Alternatively, in some embodiments, the connecting end 41 and the extending end 42 are integrally formed.

[0043] In other embodiments, one end of the electrode group 2 is provided with an internal positive electrode tab 31 and an internal negative electrode tab 32, and the external electrode tab 4 includes an external positive electrode tab and an external negative electrode tab. The external positive electrode tab is sequentially welded to all the internal positive electrode tabs 31, and the external negative electrode tab is sequentially welded to all the internal negative electrode tabs 32. The electrode tabs are on the same side of the battery cell. This arrangement facilitates the cutting and manufacturing of the internal electrode tabs, and also facilitates the hot-press sealing and encapsulation of the film 1 on the electrode tab side.

[0044] like Figure 7 and Figure 8 As shown, along the thickness direction of the battery cell, the cross-sectional area of ​​each groove 11 decreases sequentially from top to bottom. The top groove 11 has the largest cross-sectional area, and the remaining grooves 11 are sequentially arranged on the inner side of the circumference of the top groove 11. The bottom groove 11 has the smallest cross-sectional area, and the groove walls of each layer of grooves 11 are arranged to form a stepped structure.

[0045] In some embodiments, such as Figure 8 As shown, along the thickness direction of the battery cell, the depths of the grooves 11 from top to bottom are H1, H2...H... n H1≥H2……≥H n That is, from top to bottom, the depth of each groove 11 is the same or decreases progressively. When stamping the grooves 11, the top groove 11 is stamped first, then the bottom wall of the top groove 11 is stamped to form the second layer of grooves 11, and so on downwards for each level of groove 11. The bottom wall area of ​​the lower grooves 11 decreases, reducing the stampable area. If the stamping depth of the lower grooves 11 is too large, it is difficult to guarantee the strength of the encapsulation film 1 in the area surrounding the lower grooves 11. Therefore, the depth of each level of groove 11 is made the same or decreases progressively to ensure the strength of the groove walls at each level and to guarantee the encapsulation effect of the encapsulation film 1.

[0046] like Figure 2 and Figure 3 As shown, the sidewalls of each electrode group 2 are spaced apart to form a stepped structure around the electrode group 2. The encapsulation film 1 is wrapped around the electrode group 2, so that the four outer sidewalls of the cell form a stepped structure.

[0047] like Figure 7 and Figure 8 As shown, in some embodiments, at least three levels of grooves 11 are provided on at least one side of the encapsulation film 1 in the thickness direction of the battery cell. Along the length direction of the battery cell, the distance between the end of the upper groove 11 and the end of the lower groove 11 is L1, and the distance between the end of the middle groove 11 and the end of the lower groove 11 is L2. and / or This design allows the stepped surface on the outer side of the encapsulation film 1 to be controlled within a suitable length range, preventing the stepped surface area from occupying too much space after the battery cell is assembled, thus improving the overall space utilization of the battery cell and battery pack. Simultaneously, it also prevents the distance between the ends of adjacent grooves 11 from being too short, which could affect the strength of the encapsulation film 1 after stamping.

[0048] In other embodiments, the encapsulation film 1 on at least one side of the cell thickness direction is provided with two levels of grooves 11. The total depth of the grooves 11 on the encapsulation film 1 is increased by the two levels of grooves 11 so that it can accommodate the electrode group 2 with a thicker total thickness, thereby increasing the capacity of the cell.

[0049] like Figure 9 As shown, in some embodiments, at least two levels of grooves 11 are provided on the encapsulation film 1 on both sides of the cell thickness direction. This arrangement can further increase the number of grooves 11 and the total depth of all grooves 11, thereby further improving the cell capacity.

[0050] In some embodiments, such as Figure 9 As shown, the grooves 11 on both sides of the cell thickness direction are symmetrically arranged, and the fold line of the encapsulation film 1 or the mating surface of the two encapsulation films is located in the middle of the cell thickness direction. The symmetrical arrangement of the grooves 11 on both sides of the cell thickness direction means that the electrode groups 2 are symmetrically arranged, resulting in a regular overall cell structure, which is beneficial to improving the stability of the cell structure.

[0051] like Figure 1 and Figure 3 As shown, the battery cell also includes tab adhesive 5, which is disposed on the protruding end 42. When the encapsulation film 1 is heat-sealed, the tab adhesive 5 and the encapsulation film 1 are heat-sealed together so that the tab adhesive 5 is sealed between the protruding end 42 and the encapsulation film 1 to prevent the electrolyte inside the battery cell from leaking.

[0052] In some embodiments, the encapsulation film 1 includes an aluminum-plastic film.

[0053] According to an embodiment of the present invention, another aspect provides a battery pack including the aforementioned battery cell.

[0054] This battery pack structure allows the cells to overcome the depth limitations of a single groove 11, accommodating a thicker electrode assembly 2 within all grooves 11, effectively increasing battery capacity. Simultaneously, the stepped cell structure increases the outer surface area of ​​the cells, improving heat dissipation for both the cells and the battery pack, thus enhancing the battery pack's safety performance. Furthermore, the tabs of all electrode assemblies 2 are welded together via external tabs 4, saving material used for internal tabs and reducing the area of ​​electrode sheets cut away during tab formation, thereby improving material utilization and reducing the manufacturing costs of the cells and battery pack.

[0055] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: The encapsulation film has at least two levels of grooves on at least one side of the cell thickness direction, and the at least two levels of grooves are arranged in a stepped manner from the inside to the outside. At least two electrode groups are stacked vertically along the thickness direction of the cell in a stepped manner and are correspondingly disposed in the groove; the ends of the electrode groups are provided with internal tabs, and the internal tabs of the upper electrode group are attached to the large surface of the lower electrode group. The external tab includes a connecting end and an extending end. The connecting end is stepped, and the stepped surface of the connecting end is sequentially welded to all the internal tabs. One end of the extending end extends outside the encapsulation film.

2. The battery cell according to claim 1, characterized in that, The electrode group has an internal positive electrode tab and an internal negative electrode tab at both ends. The external electrode tab includes an external positive electrode tab and an external negative electrode tab. The external positive electrode tab is sequentially welded to all the internal positive electrode tabs, and the external negative electrode tab is sequentially welded to all the internal negative electrode tabs.

3. The battery cell according to claim 1, characterized in that, One end of the electrode assembly is provided with an internal positive electrode tab and an internal negative electrode tab. The external electrode tab includes an external positive electrode tab and an external negative electrode tab. The external positive electrode tab is sequentially welded to all the internal positive electrode tabs, and the external negative electrode tab is sequentially welded to all the internal negative electrode tabs.

4. The battery cell according to any one of claims 1 to 3, characterized in that, Along the thickness direction of the battery cell, the depths of the grooves from top to bottom are H1, H2...H... n H1≥H2……≥H n .

5. The battery cell according to claim 4, characterized in that, At least three levels of grooves are provided on the encapsulation film on at least one side of the cell thickness direction. Along the length direction of the cell, the distance between the end of the upper groove and the end of the lower groove is L1, and the distance between the end of the middle groove and the end of the lower groove is L2. And / or, 6. The battery cell according to any one of claims 1 to 3, characterized in that, The encapsulation film on at least one side in the cell thickness direction has two levels of grooves.

7. The battery cell according to any one of claims 1 to 3, characterized in that, At least two levels of grooves are provided on the encapsulation film on both sides of the cell thickness direction.

8. The battery cell according to claim 7, characterized in that, The grooves on both sides of the cell thickness direction are symmetrically arranged.

9. The battery cell according to any one of claims 1 to 3, characterized in that, It also includes tab adhesive, which is disposed on the protruding end and sealed between the protruding end and the encapsulation film.

10. A battery pack, characterized in that, The battery cell includes any one of claims 1 to 9.

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