Battery cell and battery cell group

Abstract

The utility model relates to the technical field of batteries, and discloses a battery cell and a battery cell group, the battery cell comprises a shell, at least one outer surface of the shell is sunken to form a groove part; the heat conduction pad is arranged in the groove part and is attached to the shell; the isolating membrane covers the outer sides of the shell and the heat conducting pad; the heat-conducting pad comprises a heat-conducting body and a heat-conducting lead-out part formed by extending the heat-conducting body; and the isolating membrane is provided with a lead-out notch corresponding to the heat conduction lead-out part, so that the external cooling device is communicated with the heat conduction lead-out part. According to the battery cell provided by the utility model, the heat conduction pad is arranged in the groove part, and the heat conduction pad is attached to the shell, so that the heat of the shell can be quickly transferred to the heat conduction pad. Heat is collected through the heat conduction body and led out through the heat conduction leading-out part, the heat of the shell can be rapidly transferred, heat exchange is achieved, the temperature of the shell is effectively controlled, and potential safety hazards are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a battery cell and a battery cell group. Background Art

[0002] In the related art, the shell of the battery cell mostly adopts an aluminum shell structure. Although the aluminum shell is lighter in weight, its mechanical strength is weaker than that of the steel shell structure. In addition, in order to ensure the insulation performance of the battery cell, a blue film is often coated on the outside of the battery cell to meet the insulation requirements of the battery cell. However, the thermal conductivity of the battery cell coated with the blue film is very small (about 0.15W / mK~0.24W / mK), which makes it impossible to transfer the heat of the shell to the surrounding cooling device in a timely and rapid manner; thus, it is easy to cause thermal runaway of the battery cell, and even safety accidents such as heat spread, fire and explosion.

[0003] How to improve the structural strength of the battery cell shell while achieving rapid heat dissipation from the shell has become an urgent problem to be solved. Utility Model Content

[0004] In view of this, the utility model provides a battery cell and a battery cell group to solve the problem of how to improve the structural strength of the battery cell shell and realize the rapid heat dissipation of the shell.

[0005] In a first aspect, the utility model provides a battery cell, comprising:

[0006] A housing, wherein at least one outer surface of the housing is recessed to form a groove;

[0007] A thermal pad is disposed in the groove and is fitted with the housing;

[0008] An isolation film, covering the outer sides of the housing and the thermal pad;

[0009] The heat-conducting pad comprises a heat-conducting body and a heat-conducting lead-out portion extending from the heat-conducting body; the isolation film is provided with a lead-out notch corresponding to the heat-conducting lead-out portion so that the external cooling device is connected to the heat-conducting lead-out portion.

[0010] Beneficial effect: The large surface of the shell is concave to form a groove, which is preferably located in the middle area of ​​the large surface of the shell, which is also the area where heat is concentrated. By arranging the thermal pad in the groove and the thermal pad and the shell are arranged in a close relationship, the heat of the shell can be quickly transferred to the thermal pad. The thermal pad includes a thermal conductive body and a thermal conductive lead-out portion formed by extending the thermal conductive body; the heat is collected by the thermal conductive body and the heat is led out through the thermal conductive lead-out portion, so that the heat of the shell can be quickly transferred, heat exchange can be achieved, the temperature of the shell can be effectively controlled, and safety hazards can be reduced.

[0011] In an optional embodiment, the outer surface of the shell forming the groove portion is defined as the heat dissipation surface, and in the direction perpendicular to the heat dissipation surface, it satisfies: T≤S, wherein T is the thickness of the thermal pad in the direction perpendicular to the heat dissipation surface, and S is the depth of the groove portion in the direction perpendicular to the heat dissipation surface.

[0012] Beneficial effect: By making the thickness of the thermal pad in the direction perpendicular to the heat dissipation surface less than or equal to the depth of the groove in the direction perpendicular to the heat dissipation surface, it can be ensured that the thermal pad does not protrude from the groove, thereby facilitating the arrangement of the thermal pad and avoiding increasing the thickness of the battery cell, and facilitating the coating of the isolation film and avoiding local irregularities in the isolation film.

[0013] In an optional implementation, the thickness T of the thermal pad in a direction perpendicular to the heat dissipation surface satisfies: 0.1 mm≤T≤0.55 mm.

[0014] In an optional embodiment, a lead-out groove is formed on the heat dissipation surface corresponding to the heat-conducting lead-out portion, and the lead-out groove is connected to the groove portion and is suitable for accommodating the heat-conducting lead-out portion;

[0015] The heat dissipation surface includes a large surface of the shell, wherein the large surface of the shell is a surface defined by the length direction and the height direction of the shell;

[0016] Along the length direction of the shell, the length of the shell is defined as F, and the length of the lead-out groove in the direction parallel to the length of the shell is defined as W, satisfying:

[0017] 20mm≤W<1 / 3F.

[0018] Beneficial effect: By limiting the lower limit of the length W of the lead-out groove in the length direction parallel to the shell, the cross-sectional size of the heat-conducting lead-out portion can be effectively guaranteed, and the heat exchange efficiency can be guaranteed. By limiting the upper limit of the length W of the lead-out groove in the length direction parallel to the shell, and associating the upper limit of the length W of the lead-out groove in the length direction parallel to the shell with the length F of the shell, the length W of the lead-out groove in the length direction parallel to the shell can be well referenced, avoiding the excessive size of the lead-out notch opened in the heat-conducting lead-out portion of the isolation membrane due to the excessive length W, preventing the isolation membrane from being loosely bonded to the shell, and reducing the probability of the isolation membrane being torn from the position of the lead-out notch.

[0019] In an optional embodiment, in a direction perpendicular to the heat dissipation surface, a region of the housing where the recessed portion is formed is defined, and a dimension of the projection toward the interior of the housing is L, satisfying: 0.25 mm ≤ L ≤ 0.6 mm.

[0020] Beneficial effect: Since the area where the recessed portion of the shell is formed is convex toward the inside of the shell, the area fits more closely with the pole group inside the shell, thereby ensuring smooth heat transfer.

[0021] In an optional implementation, the material of the thermal pad includes: imide resin, carbon fiber reinforced plastic or polyamide.

[0022] Beneficial effect: The thermal pad adopts the above-mentioned material, which can take into account the characteristics of insulation performance and high thermal conductivity, thereby improving the heat dissipation efficiency without adding additional safety hazards such as short circuits.

[0023] In an optional implementation, the thermal conductivity of the thermal pad is λ, and satisfies 2W / mK≤λ≤20W / mK.

[0024] In a second aspect, the utility model further provides a battery cell group, comprising the battery cell as described above; the number of the battery cells is multiple, and the multiple battery cells are stacked in a direction perpendicular to the large surface of the shell;

[0025] The large surface of the shell is a surface defined by the length direction and the height direction of the shell.

[0026] In an optional embodiment, the groove portion is formed on a large surface of the housing, and the groove portions of every two adjacent battery cells are arranged opposite to each other;

[0027] The isolation film is provided with a lead-out notch corresponding to the heat-conducting lead-out portion, and the lead-out notch is located at the bottom of the shell along the height direction.

[0028] Beneficial effect: In order to facilitate the grouping of battery cells, multiple battery cells are stacked in a direction perpendicular to the large surface of the shell, but at the same time, the large surface area of ​​the shell is a concentrated area of ​​heat generation, and the heat of the large surface of the stacked shell cannot be quickly dissipated. In this embodiment, a groove is formed on the large surface of the shell, and a thermal pad is arranged in the groove, and the thermal pad is arranged in affixed with the shell. After the battery cell group is formed, the thermal pad can quickly export the heat of the large surface of the shell, and then quickly transfer the heat of the shell, realize heat exchange, effectively control the temperature of the shell, and reduce safety hazards.

[0029] In an optional embodiment, the battery cell group further includes: a connecting portion, the connecting portion is connected to the heat conductive lead-out portion of each battery cell; or the connecting portion is connected to the heat conductive lead-out portions of every two adjacent battery cells at the same time.

[0030] Beneficial effect: The connection part is connected with the heat-conducting lead-out part of the battery cell, so that the heat-conducting lead-out part can be connected to an external cooling device, which facilitates the heat to be led out to the outside to achieve heat exchange. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a schematic diagram of the battery cell of the utility model;

[0033] Figure 2 This is an exploded schematic diagram of the battery cell of the utility model;

[0034] Figure 3 It is a front view of the battery cell of the utility model;

[0035] Figure 4 for Figure 3 Schematic diagram of the AA section;

[0036] Figure 5 for Figure 4 The enlarged view of point B in the middle;

[0037] Figure 6 A schematic diagram of two adjacent battery cells arranged side by side;

[0038] Figure 7 for Figure 6 Enlarged view of point C in the middle;

[0039] Figure 8 for Figure 6 The enlarged view of point D in the middle;

[0040] Fig. 9 It is a schematic diagram of the connection between the heat conduction lead-out part and the connection part.

[0041] Description of reference numerals:

[0042] 1. Shell; 11. Groove; 111. Lead-out groove; 2. Explosion-proof valve; 3. Cover plate; 41. Electrode group; 42. Bare cell insulation film; 43. Side plate;

[0043] 5. Thermal pad; 51. Thermal body; 52. Thermal lead-out portion; 6. Isolation film; 61. Lead-out notch; 7. Connecting portion. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0045] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0046] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] Combine the following Figures 1 to 9 , describing an embodiment of the utility model.

[0049] According to an embodiment of the present utility model, on the one hand, a battery cell is provided, comprising:

[0050] A housing 1, wherein at least one outer surface of the housing 1 is recessed to form a groove portion 11;

[0051] The thermal pad 5 is disposed in the groove 11 and is closely attached to the housing 1;

[0052] An isolation film 6 is coated on the outer sides of the housing 1 and the thermal pad 5;

[0053] The thermal pad 5 includes a thermal body 51 and a thermal lead-out portion 52 extending from the thermal body 51 . The isolation film 6 is provided with a lead-out notch 61 corresponding to the thermal lead-out portion 52 to connect the external cooling device to the thermal lead-out portion 52 .

[0054] Combination Figure 2 As shown, the battery cell includes a shell 1 and a pole group 41 arranged inside the shell 1, and the outer side of the pole group 41 is coated with a bare cell insulation film 42. The structural form of the battery cell can be a square shell battery cell, a blade battery cell, a short knife battery cell, etc. In this embodiment, the surface defined by the length direction and the height direction of the shell 1 is defined as the large surface, the surface defined by the length direction and the width direction of the shell 1 is defined as the long side surface, and the surface defined by the height direction and the width direction of the shell 1 is defined as the short side surface. As a variation, the shell 1 may not have a short side surface, but the cover plate 3 may replace the position of the short side surface.

[0055] In this embodiment, an explosion-proof valve installation hole is opened on the long side surface of the housing 1, and the explosion-proof valve installation hole is used to install the explosion-proof valve 2.

[0056] In this embodiment, the cover plate 3 is replaced and arranged at the position of the short side, and the cover plate 3 is provided with a pole, and the pole is electrically connected to the pole lug of the pole group 41. By arranging the explosion-proof valve 2 and the pole on different sides, electrical separation is achieved, thereby improving the safety of the battery cell.

[0057] The battery cell further includes a side plate 43 , which is disposed in the housing 1 and specifically located between the long side surface of the housing 1 and the pole group 41 .

[0058] In this embodiment, the shell 1 of the battery cell adopts an aluminum shell structure, which has the advantage of light weight. However, since the mechanical strength of the aluminum shell is weaker than that of the steel shell, in order to improve the mechanical strength of the aluminum shell, a groove portion 11 is formed by recessing at least one of the outer surfaces of the shell 1, so that the outer surface of the shell 1 forms a concave-convex structure, which plays the role of a reinforcing rib, thereby improving the structural strength of the shell 1 while ensuring the advantage of light weight.

[0059] In this embodiment, the outer surface of the shell 1 that is recessed and formed with the groove portion 11 is the large surface of the shell 1. Since the large surface of the shell 1 has the largest area and is most susceptible to structural deformation, the large surface of the shell 1 can be structurally strengthened by recessing the groove portion 11 on the large surface of the shell 1, thereby increasing the structural strength of the shell 1 without increasing the wall thickness of the shell 1.

[0060] In order to ensure the insulation performance of the battery cell, an isolation film 6 is coated on the outside of the shell 1 to meet the insulation requirements of the battery cell. Since at least one of the outer surfaces of the shell 1 of this embodiment is recessed to form a groove 11, and a thermal pad 5 is arranged in the groove 11, and the thermal pad 5 is fitted with the shell 1, the isolation film 6 is coated on the outside of the shell 1 and the thermal pad 5 to ensure that the thermal pad 5 is fitted with the shell 1 and to facilitate the restraint and fixation of the thermal pad 5.

[0061] The large surface of the shell 1 is concave to form a groove portion 11, which is preferably located in the middle area of ​​the large surface of the shell 1. This area is also a heat concentrated area. By arranging the thermal pad 5 in the groove portion 11 and the thermal pad 5 is arranged in close contact with the shell 1, the heat of the shell 1 can be quickly transferred to the thermal pad 5. In this embodiment, the thermal pad 5 includes a thermal conductive body 51 and a thermal conductive lead-out portion 52 formed by extending the thermal conductive body 51; the heat is collected by the thermal conductive body 51 and the heat is led out through the thermal conductive lead-out portion 52, so that the heat of the shell 1 can be quickly transferred, heat exchange can be achieved, the temperature of the shell 1 can be effectively controlled, and safety hazards can be reduced.

[0062] Since the thermal conductivity of the battery cell after being coated with the isolation film 6 is very small (about 0.15W / mK~0.24W / mK), it is impossible to transfer the heat of the shell 1 to the external cooling device in a timely and rapid manner; thus, it is easy to cause thermal runaway of the battery cell, or even safety accidents such as heat spread, fire and explosion. For ternary system batteries such as nickel-cobalt-aluminum and nickel-cobalt-manganese, the reaction is violent when thermal runaway occurs. The probability of heat spread is relatively high. In this embodiment, a lead-out notch 61 is provided at the position of the isolation film 6 corresponding to the heat-conducting lead-out portion 52, so that the external cooling device is connected to the heat-conducting lead-out portion 52. Therefore, after the heat of the shell 1 is gathered to the thermal pad 5, it is led out to the outside through the heat-conducting lead-out portion 52 to achieve heat exchange.

[0063] It should be noted that the isolation film 6 only needs to have a lead-out notch 61 in a part, and the other positions ensure that the isolation film 6 is normally covered on the outside of the housing 1 and the thermal pad 5 to play an insulating protection role. The lead-out notch 61 can be opened at a position that does not interfere with the stacking of the battery cells and avoids the opening position of the explosion-proof valve and the arrangement position of the pole.

[0064] In some embodiments, in combination Figure 4 , Figure 5 As shown, the outer surface of the housing 1 forming the groove 11 is defined as the heat dissipation surface, and in the direction perpendicular to the heat dissipation surface, it satisfies: T≤S, where T is the thickness of the thermal pad 5 in the direction perpendicular to the heat dissipation surface, and S is the depth of the groove 11 in the direction perpendicular to the heat dissipation surface.

[0065] By making the thickness of the thermal pad 5 in the direction perpendicular to the heat dissipation surface less than or equal to the depth of the groove 11 in the direction perpendicular to the heat dissipation surface, it can be ensured that the thermal pad 5 does not protrude from the groove 11, thereby facilitating the arrangement of the thermal pad 5 and avoiding increasing the thickness of the battery cell, and facilitating the covering of the isolation film 6 and avoiding local irregularities of the isolation film 6.

[0066] In some embodiments, in combination Figure 5 As shown, the thickness T of the thermal pad 5 in the direction perpendicular to the heat dissipation surface satisfies: 0.1 mm≤T≤0.55 mm.

[0067] As an optional implementation form, the thickness T of the thermal pad 5 in the direction perpendicular to the heat dissipation surface can be selected to be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.5 mm, 0.55 mm, etc.

[0068] In some embodiments, in combination Figure 2 As shown, a lead-out groove 111 is formed on the heat dissipation surface corresponding to the heat-conducting lead-out portion 52, and the lead-out groove 111 is connected to the groove portion 11 and is suitable for accommodating the heat-conducting lead-out portion 52;

[0069] The heat dissipation surface includes a large surface of the housing 1, wherein the large surface of the housing 1 is a surface defined by the length direction and the height direction of the housing 1;

[0070] Along the length direction of the shell 1, the length of the shell 1 is defined as F, and the length of the lead-out groove 111 in the length direction parallel to the shell 1 is defined as W, satisfying:

[0071] 20mm≤W<1 / 3F.

[0072] The lead-out groove 111 is connected to the groove portion 11 , and the overall groove structure formed by the lead-out groove 111 and the groove portion 11 matches the structural form of the thermal pad 5 , thereby facilitating the installation and positioning of the thermal pad 5 and ensuring the contact area between the thermal pad 5 and the groove portion 11 formed by the shell 1 .

[0073] In this embodiment, the lead-out groove 111 extends from the groove portion 11 to the edge of the large surface of the shell 1, thereby facilitating the heat conduction lead-out portion 52 to be led out from the lead-out groove 111 without occupying the dimension in the direction of battery cell stacking, thereby avoiding increasing the thickness of the battery cells after stacking.

[0074] By limiting the lower limit of the length W of the lead-out groove 111 in the length direction parallel to the shell 1, the cross-sectional size of the heat-conducting lead-out portion 52 can be effectively guaranteed, and the heat exchange efficiency can be guaranteed. By limiting the upper limit of the length W of the lead-out groove 111 in the length direction parallel to the shell 1, and associating the upper limit of the length W of the lead-out groove 111 in the length direction parallel to the shell 1 with the length F of the shell 1, the length W of the lead-out groove 111 in the length direction parallel to the shell 1 can be well referenced, avoiding the excessive size of the lead-out notch 61 opened in the isolation film 6 corresponding to the heat-conducting lead-out portion 52 due to the excessive length W, preventing the isolation film 6 from being loosely bonded to the shell 1, and reducing the probability of the isolation film 6 being torn at the position of the lead-out notch 61.

[0075] In some embodiments, in combination Figure 5 As shown, in the direction perpendicular to the heat dissipation surface, the area of ​​the housing 1 where the groove portion 11 is formed is defined, and the dimension of the protrusion toward the inside of the housing 1 is L, satisfying: 0.25mm≤L≤0.6mm.

[0076] As an optional implementation form, the dimension L of the area of ​​the shell 1 where the groove 11 is formed and protrudes toward the inside of the shell 1 can be selected as 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.5 mm, 0.55 mm, 0.6 mm, etc.

[0077] The groove 11 of the shell 1 can be formed by stamping. Since the area of ​​the shell 1 where the groove 11 is formed is convex toward the inside of the shell 1, the area fits more closely with the pole group inside the shell 1, ensuring smooth heat transfer.

[0078] In some embodiments, the material of the thermal pad 5 includes imide resin, carbon fiber reinforced plastic or polyamide.

[0079] The thermal pad 5 adopts the above-mentioned material to have both insulation performance and high thermal conductivity, thereby improving heat dissipation efficiency without causing additional safety hazards such as short circuits.

[0080] In some embodiments, the thermal conductivity of the thermal pad 5 is λ, and satisfies 2W / mK≤λ≤20W / mK.

[0081] By properly selecting the thermal conductivity of the thermal pad 5 , the thermal conductivity of the thermal pad 5 can be guaranteed and the heat dissipation efficiency can be improved.

[0082] According to an embodiment of the present invention, on the other hand, a battery cell group is provided, comprising the battery cells as described above; the number of the battery cells is multiple, and the multiple battery cells are stacked in a direction perpendicular to the large surface of the housing 1;

[0083] The large surface of the shell 1 is a surface defined by the length direction and the height direction of the shell 1 .

[0084] In some embodiments, the groove portion 11 is formed on the large surface of the housing 1 , and the groove portions 11 of every two adjacent battery cells are arranged opposite to each other;

[0085] The isolation film 6 is provided with a lead-out notch 61 corresponding to the heat-conducting lead-out portion 52 , and the lead-out notch 61 is located at the bottom of the housing 1 along the height direction.

[0086] In order to facilitate the grouping of battery cells, multiple battery cells are stacked in a direction perpendicular to the large surface of the shell 1, but at the same time, the large surface area of ​​the shell 1 is a heat-concentrated area, and the heat of the large surface of the stacked shell 1 cannot be quickly dissipated. In this embodiment, a groove portion 11 is formed on the large surface of the shell 1, and a thermal pad 5 is arranged in the groove portion 11, and the thermal pad 5 is arranged in close contact with the shell 1. After the battery cell group is formed, the thermal pad 5 can quickly conduct the heat of the large surface of the shell 1, and then quickly transfer the heat of the shell 1, realize heat exchange, effectively control the temperature of the shell 1, and reduce safety hazards.

[0087] The isolation membrane 6 is provided with a lead-out notch 61 corresponding to the heat-conducting lead-out portion 52, and the lead-out notch 61 is located at the bottom of the shell 1 along the height direction, thereby avoiding the opening position of the explosion-proof valve and the arrangement position of the pole, avoiding the interference between the heat-conducting lead-out portion 52 and the explosion-proof valve, the pole, etc., and realizing thermal and electrical separation.

[0088] Furthermore, the lead-out notch 61 is located at the bottom of the housing 1 in the height direction, so that the position where the lead-out notch 61 is opened does not interfere with the stacking of the battery cells, thereby ensuring that the battery cells are grouped smoothly.

[0089] In some embodiments, in combination Fig. 9 As shown, the battery cell group further includes: a connecting portion 7, which is connected to the heat-conducting lead-out portion 52 of each battery cell; or, the connecting portion 7 is connected to the heat-conducting lead-out portions 52 of every two adjacent battery cells at the same time.

[0090] By connecting the connecting portion 7 with the heat-conducting lead-out portion 52 of the battery cell, the heat-conducting lead-out portion 52 can be connected to an external cooling device, thereby conveniently leading the heat to the outside to achieve heat exchange.

[0091] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. Although the embodiments of the present utility model are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present utility model, and such modifications and variations are all within the scope defined by the present utility model.

Claims

1. A battery cell, characterized in that: include: A housing (1), wherein at least one outer surface of the housing (1) is recessed to form a groove portion (11); A thermal pad (5) is disposed in the groove portion (11) and is arranged in close contact with the housing (1); An isolation film (6) covering the outer sides of the housing (1) and the thermal pad (5); The thermal pad (5) comprises a thermally conductive body (51) and a thermally conductive lead-out portion (52) extending from the thermally conductive body (51); the isolation film (6) is provided with a lead-out notch (61) corresponding to the thermally conductive lead-out portion (52) so that an external cooling device is connected to the thermally conductive lead-out portion (52).

2. The battery cell according to claim 1, characterized in that: The outer surface of the housing (1) forming the groove portion (11) is defined as a heat dissipation surface, and in a direction perpendicular to the heat dissipation surface, satisfies the following condition: T≤S, wherein T is the thickness of the thermal pad (5) in a direction perpendicular to the heat dissipation surface, and S is the depth of the groove portion (11) in a direction perpendicular to the heat dissipation surface.

3. The battery cell according to claim 2, characterized in that: The thickness T of the thermal conductive pad (5) in a direction perpendicular to the heat dissipation surface satisfies: 0.1 mm≤T≤0.55 mm.

4. The battery cell according to claim 2, characterized in that: The heat dissipation surface is formed with a lead-out groove (111) corresponding to the heat-conducting lead-out portion (52), and the lead-out groove (111) is connected to the groove portion (11) and is suitable for accommodating the heat-conducting lead-out portion (52); The heat dissipation surface comprises a large surface of the shell (1), wherein the large surface of the shell (1) is a surface defined jointly by the length direction and the height direction of the shell (1); Along the length direction of the shell (1), the length of the shell (1) is defined as F, and the length of the lead-out groove (111) in the length direction parallel to the shell (1) is defined as W, satisfying: 20mm≤W<1 / 3F.

5. The battery cell according to claim 2, characterized in that: In a direction perpendicular to the heat dissipation surface, the area of ​​the housing (1) where the recessed portion (11) is formed is defined, and the dimension of the protrusion toward the inside of the housing (1) is L, satisfying the following: 0.25 mm ≤ L ≤ 0.6 mm.

6. The battery cell according to any one of claims 1 to 5, characterized in that: The material of the thermal conductive pad (5) includes: imide resin, carbon fiber reinforced plastic or polyamide.

7. The battery cell according to any one of claims 1 to 5, characterized in that: The thermal conductivity of the thermal pad (5) is λ, and satisfies 2W / mK≤λ≤20W / mK.

8. A battery cell group, characterized in that: Comprising the battery cell according to any one of claims 1 to 7 above; the number of the battery cells is multiple, and the multiple battery cells are stacked in a direction perpendicular to the large surface of the shell (1); The large surface of the shell (1) is a surface defined jointly by the length direction and the height direction of the shell (1).

9. The battery cell assembly according to claim 8, characterized in that: The groove portion (11) is formed on a large surface of the housing (1), and the groove portions (11) of every two adjacent battery cells are arranged opposite to each other; The isolation film (6) is provided with a lead-out notch (61) corresponding to the heat-conducting lead-out portion (52), and the lead-out notch (61) is located at the bottom of the shell (1) along the height direction.

10. The battery pack according to claim 9, characterized in that: The battery cell group further comprises: a connecting portion (7), the connecting portion (7) being connected to the heat-conducting lead-out portion (52) of each battery cell; or the connecting portion (7) being connected to the heat-conducting lead-out portions (52) of every two adjacent battery cells at the same time.

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