Battery cell assembly and battery pack
Through the design of split pole group and end plate group, the problem of limited cell structure length and high cost of multi-cell series connection is solved, and the capacity increase, cost reduction and safety performance of cell components are improved.
Patent Information
- Application Number
- CN202422229362.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2034-09-11
AI Technical Summary
In the prior art, the battery cell structure is shorter, resulting in limited capacity lifting space, and the special battery cell is prone to bending and deforming, and the yield is reduced; the multi-cell series connection method increases structural parts, resulting in increased costs and waste of space.
A split-type pole group structure is adopted, and the pole group is set side by side, and the relative position and guide pole ear path are fixed through the end plate group to reduce the length of a single pole group. Combined with the insulating film and cover plate design, the assembly process is simplified and the number of pole ear overlaps and structural parts are avoided.
It realizes capacity-increasing and cost-reducing of battery cell components, improves safety performance and energy density, reduces process requirements, reduces material materials, reduces costs, and avoids the increase in structural parts.
Smart Images
Figure CN223181339U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of batteries, in particular to a battery cell assembly and a battery pack. Background Art
[0002] In the related art, the structure of a battery cell is generally short in length, and the overall capacity increase space is limited by process conditions. For a battery cell with a very long length, due to the problem of the strength of the electrode group, it often bends and deforms, resulting in a reduction in the yield rate; especially for a very long battery cell, the forming process has high requirements and great support difficulty.
[0003] When adopting the method of connecting multiple battery cells in series, although the capacity can be increased, since structural components such as cover plates need to be provided for each battery cell, the number of structural components increases, the cost increases, and there is a large amount of space waste. Content of the Utility Model
[0004] In view of this, the utility model provides a battery cell assembly and a battery pack to solve the problems that when the battery cell structure increases the capacity by increasing the length, the yield rate is likely to be low; and when adopting the method of connecting multiple battery cells in series to increase the capacity, the number of structural components is likely to increase.
[0005] In a first aspect, the utility model provides a battery cell assembly, comprising:
[0006] At least two electrode groups arranged side by side along the length direction; it is defined that two adjacent electrode groups are respectively a first electrode group and a second electrode group, a first electrode tab extends from one end of the first electrode group close to the second electrode group, and a second electrode tab extends from one end of the second electrode group close to the first electrode group; the first electrode tab and the second electrode tab are welded and connected to form a welding mark.
[0007] An end plate group is arranged between the first electrode group and the second electrode group, and the end plate group is suitable for fixing the relative positions of the first electrode group and the second electrode group and guiding the extending paths of the first electrode tab and the second electrode tab.
[0008] Beneficial effects: The battery cell assembly of this embodiment includes at least two pole groups arranged side by side along the length direction. By adopting a plurality of pole groups with split structures, at least two pole groups arranged side by side along the length direction are connected, thereby shortening the length of a single pole group and reducing defects such as wrinkles, deformation, layer crossover, and fracture caused by excessive pole piece length. It is possible to increase the capacity of the battery cell assembly and connect adjacent pole groups by setting an end plate group. Since the first pole ear and the second pole ear are both flexible structures, after the pole ear is bent, if a bump occurs, it is easy for the pole ear to overlap with other charged structures, resulting in insufficient protection for the pole ear. In this embodiment, an end plate group is set between the first pole group and the second pole group. The end plate group is suitable for guiding the extension path of the first pole ear and the second pole ear, thereby constraining the first pole ear and the second pole ear, and protecting the place where the two pole ears are connected, avoiding accidental overlap, and improving the safety performance of the battery cell assembly.
[0009] By using multiple split-structure electrode groups, the length of individual electrode sheets can be reduced, lowering the process requirements for manufacturing extra-long cells and reducing the difficulty of supporting them. Furthermore, there is no need to install structural parts such as covers for each cell, avoiding the cost increase caused by the increase in structural parts and achieving cost reduction. Compared with the method of connecting multiple complete cells in series, it is more space-saving. The cell size can be longer, achieving the goal of increasing capacity and reducing costs.
[0010] In an optional embodiment, the end plate assembly includes:
[0011] The first end plate and the second end plate are buckled and connected to each other along the thickness direction;
[0012] The first end plate and the second end plate extend toward opposite sides to form a first partition and a second partition respectively. The first partition and the second partition are spaced apart along the length direction to form a clearance gap. After the first tab and the second tab are connected, at least a portion is inserted into the clearance gap.
[0013] Beneficial effect: The end plate group can simplify the assembly process by adopting a method in which the first end plate and the second end plate are interlocked and connected with each other along the thickness direction. After the first pole ear and the second pole ear are welded, the first end plate and the second end plate are interlocked toward the middle position on both sides of the thickness direction, which does not interfere with the normal connection between the first pole ear and the second pole ear, and can guide the bending path of the first pole ear and the second pole ear.
[0014] In an optional embodiment, the first end plate is formed with a first boss at both ends of the first partition along the height direction; the second end plate is formed with a second boss at both ends of the second partition along the height direction; the first boss and the second boss abut against each other to protect the first pole ear and the second pole ear along the height direction.
[0015] Beneficial effect: By forming boss structures at both ends of the end plate in the height direction, a symmetrical design can be achieved, which facilitates the force balance of the pole group support after the first end plate is connected to the second end plate, thereby reducing the risk of damaging the pole group.
[0016] In an optional embodiment, one of the corresponding first boss and second boss is provided with a latch hole, and the other is extended to form a buckle, and the latch hole and the buckle cooperate to fix the first boss and the second boss together.
[0017] Beneficial effect: The card hole and the buckle cooperate to facilitate installation and disassembly.
[0018] In an optional embodiment, the battery cell assembly further includes: an insulating film covering the outer side of the whole formed by the first electrode group, the end plate group and the second electrode group.
[0019] Beneficial Effects: Wrapping the insulating film around the outer surface of the first electrode group, end plate group, and second electrode group allows them to form a single integrated structure, facilitating subsequent assembly and providing insulation protection. This integral coating eliminates the need for separate coatings for the first, end plate, and second electrode groups, reducing material usage and costs while also increasing the overall energy density of the battery assembly.
[0020] In an optional embodiment, the end plate group is connected to the first pole group by adhesive bonding or thermal melting; and / or the end plate group is connected to the second pole group by adhesive bonding or thermal melting.
[0021] Beneficial Effects: By fixing the end plate assembly to the first and second pole groups, respectively, the three can be ensured to form a whole, preventing the first and second pole groups from approaching each other and squeezing the pole tabs, and preventing the first and second pole groups from moving away from each other and pulling the pole tabs. This meets the requirement of connecting the first and second pole groups via the pole tabs, improves energy density, and achieves cell capacity expansion. At the same time, it provides a safety protection for the connection between the first and second pole tabs and can ensure the relative position of the first and second pole groups, making it easier for the first and second pole groups to connect to the external circuit as a whole.
[0022] In an optional embodiment, the battery cell assembly further includes: a first cover plate, covering an end of the first electrode group away from the first electrode tab along the length direction;
[0023] The second cover plate is arranged to cover an end of the second pole group away from the second pole ear along the length direction.
[0024] Beneficial effects: By providing a first cover plate and a second cover plate at both ends of the battery cell assembly in the length direction, and directly connecting the tab ears between the internal electrode groups, the number of structures is reduced. There is no need to provide structural components such as cover plates for each battery cell, avoiding cost increase caused by the increase of structural components, achieving cost reduction, and reducing the internal resistance of the battery cell.
[0025] In an alternative embodiment, the distance between the two end faces of the first electrode group in the length direction is W1, and the distance between the two end faces of the second electrode group in the length direction is W2, satisfying: 0.5 ≤ W1 / W2 ≤ 1.
[0026] In an alternative embodiment, the dimension of the first boss in the thickness direction is H2, and the dimension of the second boss in the thickness direction is H1, satisfying: 0.6 ≤ H1 / H2 ≤ 1.
[0027] In a second aspect, the present invention also provides a battery pack, including: the battery cell assembly as described above.
[0028] Since the battery pack includes the battery cell assembly and has the same effects as the battery cell assembly, it will not be elaborated here. Description of the Drawings
[0029] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0030] Figure 1 It is the front view of the battery cell assembly of the present invention;
[0031] Figure 2 It is Figure 1 the schematic diagram of the A-A cross-section in
[0032] Figure 3 It is Figure 2 the enlarged view at C in
[0033] Figure 4 It is Figure 1 the schematic diagram of the B-B cross-section in
[0034] Figure 5 It is Figure 4 the enlarged view at D in
[0035] Figure 6 It is the schematic diagram of the end plate group of the present invention;
[0036] Figure 7 It is the front view of the battery cell assembly of the present invention after removing the end plate group;
[0037] Figure 8 This is the top view of the end plate group of the present utility model;
[0038] Figure 9 is Figure 8 the schematic diagram of the E-E cross-section in
[0039] Figure 10 is Figure 8 the schematic diagram of the F-F cross-section in
[0040] Explanation of the reference numerals in the drawings:
[0041] 1. First pole group; 2. Second pole group; 11. First pole tab; 12. Second pole tab; 13. Welding mark;
[0042] 3. End plate group; 31. First end plate; 311. First partition part; 312. First boss; 32. Second end plate; 321. Second partition part; 322. Second boss; 323. Buckle; 324. Locking hole; 33. Relief notch;
[0043] 4. First cover plate; 5. Second cover plate. Detailed implementation manners
[0044] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.
[0045] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model 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 thus should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.
[0046] In the description of the present utility model, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "coupling" 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 directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.
[0047] In addition, the technical features involved in different embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.
[0048] The capacity of the battery cell refers to the amount of electric charge that the battery cell can store, that is, milliampere-hour (mAh), which determines the usage time of the battery cell. When the length of the battery cell increases, the effect of increasing the capacity of the battery cell is obvious. In the related art, the structure of the battery cell is generally short in length, and the overall space for increasing the capacity is limited by process conditions. Due to the strength problem of the electrode group, for a battery cell with a very long length, bending deformation often occurs, resulting in a decrease in the yield rate; especially for a very long battery cell, the forming process requirements are high and the support difficulty is great. And by adopting the method of connecting multiple battery cells in series, although the capacity can be increased, since each battery cell needs to be provided with structural components such as a cover plate, the number of structural components increases, the cost increases, and there is a large amount of space waste.
[0049] The following Figures 1 to 10 , describes the embodiments of the present utility model.
[0050] According to an embodiment of the present utility model, on the one hand, a battery cell assembly is provided, including:
[0051] At least two electrode groups, arranged side by side along the length direction; it is defined that two adjacent electrode groups are respectively the first electrode group 1 and the second electrode group 2. One end of the first electrode group 1 close to the second electrode group 2 extends out a first electrode tab 11, and one end of the second electrode group 2 close to the first electrode group 1 extends out a second electrode tab 12; the first electrode tab 11 and the second electrode tab 12 are welded and connected to form a welding mark 13;
[0052] An end plate group 3, arranged between the first electrode group 1 and the second electrode group 2, and the end plate group 3 is adapted to fix the relative positions of the first electrode group 1 and the second electrode group 2, and guide the extending paths of the first electrode tab 11 and the second electrode tab 12.
[0053] The battery cell assembly of this embodiment includes at least two electrode groups arranged side by side along the length. By adopting multiple split-structure electrode groups, the at least two electrode groups arranged side by side along the length are connected, thereby shortening the length of a single electrode group and reducing defects such as wrinkling, deformation, layer cross-linking, and fracture caused by excessive electrode length. This can achieve an increase in the capacity of the battery cell assembly, and the connection of adjacent electrode groups is achieved by providing an end plate group 3. The battery cell assembly of this embodiment is described below using the example of a battery cell assembly including two electrode groups arranged side by side along the length.
[0054] It should be noted that the length direction refers to the direction in which the longest side of each side of the electrode group extends, the thickness direction refers to the direction perpendicular to the large surface of the electrode group, wherein the large surface of the electrode group is the surface with the largest external surface area in the electrode group, and the height direction refers to the direction perpendicular to both the length direction and the thickness direction. In this embodiment, the height direction can be parallel to the vertical direction. In addition, the length direction, thickness direction, and height direction are as shown in the attached figure. Figure 1 、 Figure 2 Directions shown are for reference only.
[0055] Two adjacent electrode groups are defined as a first electrode group 1 and a second electrode group 2. A first electrode tab 11 extends from one end of the first electrode group 1 near the second electrode group 2, and a second electrode tab 12 extends from one end of the second electrode group 2 near the first electrode group 1. The two electrode groups are connected in series by welding the first electrode tab 11 and the second electrode tab 12. The polarities of the first electrode tab 11 and the second electrode tab 12 are opposite. A weld mark 13 is formed at the location where the first electrode tab 11 and the second electrode tab 12 are welded.
[0056] Since the first pole lug 11 and the second pole lug 12 are both flexible structures, after the pole lugs are bent, if a bump occurs, it is easy for the pole lugs to overlap with other charged structures, resulting in insufficient protection for the pole lugs. In this embodiment, an end plate group 3 is provided between the first pole group 1 and the second pole group 2. The end plate group 3 is suitable for guiding the extension path of the first pole lug 11 and the second pole lug 12, so as to restrain the first pole lug 11 and the second pole lug 12 and protect the place where the two pole lugs are connected, thereby avoiding accidental overlap and improving the safety performance of the battery cell assembly.
[0057] At the same time, the end plate group 3 is suitable for fixing the relative position of the first pole group 1 and the second pole group 2, playing an isolating and supporting role, and effectively fixing the two pole groups. It prevents the first pole group 1 and the second pole group 2 from getting close to each other and squeezing the pole ear, and prevents the first pole group 1 and the second pole group 2 from moving away from each other and pulling the pole ear. It meets the demand for the first pole group 1 and the second pole group 2 to be connected through the pole ear, improves the energy density, and realizes the capacity increase of the battery cell. At the same time, it plays a safety protection role for the connection between the first pole ear 11 and the second pole ear 12, and can ensure the relative position of the first pole group 1 and the second pole group 2, so that the first pole group 1 and the second pole group 2 are more easily connected to the external circuit as a whole.
[0058] The battery cell assembly provided by the embodiments of the present invention, by adopting multiple split-structure electrode groups, can reduce the length of a single electrode piece, lower the process requirements for manufacturing extra-long battery cells, and reduce the difficulty of supporting them. At the same time, it is not necessary to provide structural parts such as cover plates for each battery cell, avoiding the cost increase caused by the increase in structural parts, thus achieving cost reduction. Compared with the method of connecting multiple complete battery cells in series, it is more space-saving. The battery cell size can be longer, achieving the purpose of increasing capacity and reducing costs.
[0059] In addition, the pole group size of the battery cell assembly can be matched in a variety of ways, such as long and short size matching, equal size matching, to maximize adaptability to equipment production lines.
[0060] In some embodiments, combined Figure 3 、 Figure 6 As shown, the end plate group 3 includes:
[0061] The first end plate 31 and the second end plate 32 are buckled and connected to each other along the thickness direction;
[0062] The first end plate 31 and the second end plate 32 extend toward opposite sides to form a first partition 311 and a second partition 321 , respectively. The first partition 311 and the second partition 321 are separated by a clearance gap 33 along the length direction. After the first electrode tab 11 and the second electrode tab 12 are connected, at least a portion of them is inserted into the clearance gap 33 .
[0063] The end plate group 3 can simplify the assembly process by adopting a method in which the first end plate 31 and the second end plate 32 are interlocked and connected with each other along the thickness direction. After the first pole ear 11 and the second pole ear 12 are welded, the first end plate 31 and the second end plate 32 are interlocked toward the middle position along both sides of the thickness direction, which does not interfere with the normal connection between the first pole ear 11 and the second pole ear 12, and can guide the bending path of the first pole ear 11 and the second pole ear 12.
[0064] Combine Figure 3 、 Figure 9As shown, the first end plate 31 and the second end plate 32 extend toward opposite sides to form a first partition 311 and a second partition 321 respectively. The first partition 311 and the second partition 321 are spaced apart along the length direction to form a clearance gap 33, so as to facilitate the connected tabs to pass through the clearance gap 33.
[0065] In this embodiment, the weld mark 13 is located in the area of the clearance notch 33 .
[0066] The projections of the first partition 311 and the second partition 321 along the length direction at least partially overlap, so that the first partition 311 and the second partition 321 intersect along the thickness direction, which better guides the tab and separates the tab from the external charged structure.
[0067] In some embodiments, combined Figure 6 As shown, the first end plate 31 is formed with a first boss 312 at both ends of the first partition 311 along the height direction; the second end plate 32 is formed with a second boss 322 at both ends of the second partition 321 along the height direction; the first boss 312 and the second boss 322 abut against each other to protect the first pole ear 11 and the second pole ear 12 along the height direction.
[0068] By forming boss structures at both ends of the end plate in the height direction, a symmetrical design can be achieved, which facilitates the balanced force of the pole group support after the first end plate 31 is connected to the second end plate 32, thereby reducing the risk of damaging the pole group.
[0069] In addition, after the first end plate 31 is connected to the second end plate 32, the first boss 312 and the second boss 322 abut against each other, so that the first partition 311 and the second partition 321 are shielded on both sides along the height direction, so as to protect the first pole ear 11 and the second pole ear 12 along the height direction and avoid damage to the pole ears.
[0070] In some embodiments, combined Figure 5 As shown, one of the corresponding first boss 312 and second boss 322 is provided with a latch hole 324 , and the other is extended to form a buckle 323 , and the latch hole 324 cooperates with the buckle 323 to fix the first boss 312 and the second boss 322 together.
[0071] In this embodiment, the first end plate 31 and the second end plate 32 adopt a split structure, and the first boss 312 and the second boss 322 are fixedly connected by the card hole 324 and the card buckle 323, thereby realizing the installation and fixation of the first end plate 31 and the second end plate 32, and facilitating disassembly.
[0072] In some embodiments, the battery cell assembly further includes: an insulating film covering the outer side of the whole formed by the first electrode group 1 , the end plate group 3 and the second electrode group 2 .
[0073] Wrap an insulating film around the outside of the whole formed by the first electrode group 1, the end plate group 3 and the second electrode group 2, which can make the first electrode group 1, the end plate group 3 and the second electrode group 2 form an integral structure, facilitating subsequent assembly and playing an insulating and protective role.
[0074] Through the overall wrapping of the insulating film, there is no need to wrap the first electrode group 1, the end plate group 3 and the second electrode group 2 separately, reducing the material consumption, saving costs, and at the same time increasing the overall energy density of the battery assembly.
[0075] In some embodiments, the end plate group 3 is adhesively connected or heat-melted to the first electrode group 1; and / or, the end plate group 3 is adhesively connected or heat-melted to the second electrode group 2.
[0076] By fixing the end plate group 3 to the first electrode group 1 and the second electrode group 2 respectively, it can ensure that the three form an integral body, preventing the first electrode group 1 and the second electrode group 2 from approaching each other and squeezing the electrode tabs, and preventing the first electrode group 1 and the second electrode group 2 from moving away from each other and pulling the electrode tabs. It meets the requirement of connecting the first electrode group 1 and the second electrode group 2 through the electrode tabs, increases the energy density, realizes the capacity increase of the battery cell, and at the same time plays a safety protection role for the connection of the first electrode tab 11 and the second electrode tab 12, and can ensure the relative positions of the first electrode group 1 and the second electrode group 2, making it easier for the first electrode group 1 and the second electrode group 2 to be connected to the external circuit as a whole.
[0077] In this embodiment, the end plate group 3 can be made of insulating material.
[0078] In some embodiments, as shown in Figure 1 the battery cell assembly further includes: a first cover plate 4, covering one end of the first electrode group 1 along the length direction away from the first electrode tab 11;
[0079] a second cover plate 5, covering one end of the second electrode group 2 along the length direction away from the second electrode tab 12.
[0080] Taking the battery cell assembly including two electrode groups arranged side by side along the length direction as an example, by arranging the first cover plate 4 and the second cover plate 5 at both ends of the battery cell assembly along the length direction and directly connecting the internal electrode groups with electrode tabs, the number of structural components is reduced. There is no need to set up structural components such as cover plates for each battery cell, avoiding the cost increase caused by the increase of structural components, realizing cost reduction, and reducing the internal resistance of the battery cell.
[0081] In some embodiments, as shown in Figure 7 the distance between the two end faces of the first electrode group 1 along the length direction is W1, and the distance between the two end faces of the second electrode group 2 along the length direction is W2, satisfying: 0.5 ≤ W1 / W2 ≤ 1.
[0082] In this embodiment, the value range of the distance W1 between the two end faces of the first pole group 1 in the length direction satisfies: 400 ≤ W1 ≤ 900 mm; the value range of the distance W2 between the two end faces of the second pole group 2 in the length direction satisfies: 400 ≤ W1 ≤ 900 mm.
[0083] In some embodiments, in combination with Figure 10 As shown, the dimension of the first boss 312 in the thickness direction is H2, and the dimension of the second boss 322 in the thickness direction is H1, satisfying: 0.6 ≤ H1 / H2 ≤ 1.
[0084] According to an embodiment of the present invention, on the other hand, a battery pack is further provided, including: the battery cell assembly as described above.
[0085] Obviously, the above embodiments are only examples clearly described and not limitations on the implementation manners. Although the embodiments of the present invention are 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 present invention.
Claims
1. A battery cell assembly, characterized in that, include: At least two electrode groups are arranged side by side along the length direction; the two adjacent electrode groups are defined as a first electrode group and a second electrode group, a first electrode tab extends from one end of the first electrode group close to the second electrode group, and a second electrode tab extends from one end of the second electrode group close to the first electrode group; the first electrode tab and the second electrode tab are welded to form a weld mark; The end plate group is arranged between the first pole group and the second pole group. The end plate group is suitable for fixing the relative positions of the first pole group and the second pole group and guiding the extension paths of the first pole tab and the second pole tab.
2. The cell assembly according to claim 1, wherein The end plate assembly comprises: The first end plate and the second end plate are buckled and connected to each other along the thickness direction; The first end plate and the second end plate extend toward opposite sides to form a first partition and a second partition respectively. The first partition and the second partition are spaced apart along the length direction to form a clearance gap. After the first electrode tab and the second electrode tab are connected, at least a portion is inserted into the clearance gap.
3. The cell assembly according to claim 2, wherein The first end plate is formed with a first boss at both ends of the first partition along the height direction; the second end plate is formed with a second boss at both ends of the second partition along the height direction; the first boss and the second boss abut against each other to protect the first pole ear and the second pole ear along the height direction.
4. The cell assembly according to claim 3, wherein One of the first boss and the second boss that are arranged correspondingly is provided with a latch hole, and the other is extended to form a buckle, and the latch hole cooperates with the buckle to fixedly connect the first boss and the second boss.
5. The cell assembly according to claim 1, characterized in that, The battery core assembly further includes an insulating film covering the outer side of the whole formed by the first pole group, the end plate group and the second pole group.
6. The cell assembly according to claim 1, wherein The end plate group is connected to the first pole group by adhesive bonding or thermal melting; and / or the end plate group is connected to the second pole group by adhesive bonding or thermal melting.
7. The cell assembly according to claim 1, characterized in that, The battery cell assembly further includes: a first cover plate, covering an end of the first electrode group away from the first electrode tab along the length direction; The second cover plate is arranged to cover one end of the second electrode group away from the second electrode tab along the length direction.
8. The battery cell assembly according to any one of claims 1 to 7, characterized in that, The distance between the two end surfaces of the first pole group along the length direction is W1, and the distance between the two end surfaces of the second pole group along the length direction is W2, satisfying: 0.5≤W1 / W2≤1.
9. The cell assembly according to claim 3, wherein, The dimension of the first boss along the thickness direction is H2, and the dimension of the second boss along the thickness direction is H1, satisfying the following: 0.6≤H1 / H2≤1.
10. A battery pack, characterized in that, The battery cell assembly comprises the battery cell assembly according to any one of claims 1 to 9.