Roll core assembly, cylindrical battery and power battery pack
By setting a busbar between the end surface of the core and the positive electrode ear group/negative electrode ear group in the core assembly, and controlling the welding energy, the problems of welding through and welding slag entering the core during welding are solved, and the effects of safety improvement and short-circuit prevention are achieved.
Patent Information
- Application Number
- CN202311686360.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-08
- Publication Date
- 2025-06-10
AI Technical Summary
In the prior art, welding energy fluctuations during welding process cause welding to penetrate the positive and negative electrode ear groups, causing welding slag generated by welding to penetrate and cause short circuits within the core, and even causing safety accidents.
A core roll assembly is designed, wherein the busbar is arranged between the end surface of the core roll and the positive electrode ear group/negative electrode ear group, and is connected by bending and welding, using the thickness of the busbar to control welding energy and prevent welding from passing through.
Effectively prevent welding through the busbar during welding, prevent welding slag from entering the core and causing short circuits, and avoid causing safety accidents.
Smart Images
Figure CN120127189A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of power batteries, and particularly relates to a core assembly, a cylindrical battery and a power battery pack. Background Art
[0002] The battery core is formed by winding a positive electrode sheet, a separator and a negative electrode sheet stacked in sequence. A plurality of positive electrode tabs and a plurality of negative electrode tabs for leading out current are respectively provided on the positive electrode sheet and the negative electrode sheet. After winding, a plurality of stacked positive electrode tab groups and negative electrode tab groups are formed at both ends of the core. In the prior art, after the positive electrode tab groups and the negative electrode tab groups at both ends of the core are respectively pressed flat, bent and covered on the opposite two end faces of the core, and then the bus bars are respectively covered on the positive electrode tab groups and the negative electrode tab groups and welded to the positive electrode tab groups and the negative electrode tab groups. However, during the welding process, if there is a fluctuation in the welding energy, it will cause the welding energy to be too large. The thickness of the positive and negative electrode tab groups is smaller than the thickness of the bus bar. Excessive welding energy will cause the positive and negative electrode tab groups to be welded through, and then the welding slag generated by welding will penetrate through the positive and negative electrode tab groups and fall into the core, causing a short circuit inside the core and even triggering a safety accident. Summary of the Invention
[0003] In view of this, the present invention provides a core assembly, a cylindrical battery and a power battery pack to solve the above technical problems.
[0004] The core assembly provided by the present invention includes:
[0005] A core, on opposite ends of which are respectively provided a plurality of positive electrode tab groups and a plurality of negative electrode tab groups. Each positive electrode tab group includes a plurality of positive electrode tabs stacked, each negative electrode tab group includes a plurality of negative electrode tabs stacked, and blank areas are respectively provided on the end faces of opposite ends of the core;
[0006] Two bus bars, which are respectively abutted against the two blank areas. After each positive electrode tab group and each negative electrode tab group are bent, they are respectively welded to the surface of the corresponding bus bar facing away from the core.
[0007] Optionally, a plurality of placement grooves are respectively formed on the surface of each bus bar facing away from the core. After each positive electrode tab group and each negative electrode tab group are bent, they are respectively inserted into one placement groove and welded to the bus bar in the placement groove.
[0008] Optionally, the depth of the placement groove is 0.2 - 1.5 mm.
[0009] Optionally, each placement groove includes a first placement groove and a second placement groove that are communicated, and the width of the first placement groove is greater than the width of the second placement groove;
[0010] Each of the positive electrode tabs includes a connected first bent portion and a first welding portion, and the width of the first welding portion is greater than the width of the first bent portion. The first welding portion is disposed in the first placement groove on the same side and is welded to the current collector plate. The first bent portion is connected to the core and is disposed in the second placement groove on the same side.
[0011] Each of the negative electrode tabs includes a connected second bent portion and a second welding portion, and the width of the second welding portion is greater than the width of the second bent portion. The second welding portion is disposed in the first placement groove on the same side and is welded to the current collector plate. The second bent portion is connected to the core and is disposed in the second placement groove on the same side.
[0012] Optionally, one side surface of each positive electrode tab group facing away from the core after bending is covered with a polymer composite film; and / or,
[0013] One side surface of each negative electrode tab group facing away from the core after bending is covered with a polymer composite film.
[0014] Optionally, the thickness of the polymer composite film is 0.5 - 2 mm.
[0015] Optionally, the light transmittance of the polymer composite film is greater than 90%.
[0016] Optionally, the current collector plate is evenly divided into a plurality of welding areas, and each welding area of the same current collector plate is welded to the corresponding positive electrode tab group or negative electrode tab group.
[0017] The present invention also provides a cylindrical battery, including a housing, and further including the core assembly according to any one of the above, and the core assembly is disposed in the housing.
[0018] The present invention also provides a power battery pack, including the cylindrical battery described above.
[0019] The above technical solutions provided by the present invention, compared with the prior art, at least have the following beneficial effects:
[0020] By using the core assembly, cylindrical battery and power battery pack of the present invention, the current collector plate is disposed between the core end face and the positive electrode tab group / negative electrode tab group, which can effectively prevent the current collector plate from being penetrated during the welding process, and further prevent the welding slag from entering the core interior to cause a short circuit, avoiding the occurrence of safety accidents. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic diagram of the core according to an embodiment of the present invention;
[0022] Figure 2 Schematic diagram of placing a bus bar plate at the end of the core shown Figure 1 in
[0023] Figure 3 Schematic diagram of welding connection between the positive and negative tab groups and the bus bar plate after bending in Figure 2 ;
[0024] Figure 4 Schematic diagram of the positive electrode plate in the core shown in Figure 1 ;
[0025] Figure 5 Schematic diagram of the negative electrode plate in the core shown in Figure 1 ;
[0026] Figure 6 Schematic diagram of covering the positive tab with a polymer composite film.
[0027] Reference numerals:
[0028] 1: Core; 2: Bus bar plate; 201: Placement groove; 2011: First placement groove; 2012: Second placement groove; 3: Positive tab group; 301: Positive tab; 3011: First bending part; 3012: First welding part; 4: Negative tab group; 401: Negative tab; 4011: Second bending part; 4012: Second welding part; 5: Polymer composite film; 6: Positive electrode plate; 7: Negative electrode plate. Detailed implementation manners
[0029] The embodiments of the present invention will be further described below with reference to the drawings. In the description of the present invention, 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 simplifying the description of the present invention, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.
[0030] Figure 1 Schematic diagram of the core according to an embodiment of the present invention; Figure 2 Schematic diagram of placing a bus bar plate at the end of the core shown in Figure 1 ; Figure 3 Schematic diagram of welding connection between the positive and negative tab groups and the bus bar plate after bending in Figure 2 .
[0031] As shown in Figures 1 - 3As shown, the core assembly includes a core 1 and two busbars 2. Multiple positive tab groups 3 and multiple negative tab groups 4 are respectively arranged at opposite ends of the core 1. Each positive tab group 3 includes multiple positive tabs 301 stacked together, and each negative tab group 4 includes multiple negative tabs 401 stacked together. Moreover, blank areas are respectively arranged on the end faces of opposite ends of the core 1. The two busbars 2 are respectively abutted against the two blank areas. After each positive tab group 3 and each negative tab group 4 are bent, they are respectively welded to the surface of the corresponding busbar 2 on the side facing away from the core 1.
[0032] During the manufacturing process, the positive tabs 301 are cut at intervals on the positive electrode sheet by die-cutting, and the negative tabs 401 are cut at intervals on the negative electrode sheet. After cutting, the positive electrode sheet, the separator, and the negative electrode sheet are sequentially stacked and wound by a winding machine to produce the core 1. There is a blank section of 1 - 4 m for the positive electrode sheet and the negative electrode sheet at the feeding stage, that is, the positive tabs 301 and the negative tabs 401 are not retained within this length range. Thus, after winding into the core 1, there are no tabs arranged within a certain range at the centers of the opposite end faces of the core 1, forming blank areas for placing the busbars 2. After the two busbars 2 are respectively placed on the opposite two end faces of the core 1, each positive tab group 3 and each negative tab group 4 are bent and flattened, so that each bent positive tab group 3 abuts against the busbar 2 on the same side, and each positive tab group 3 is welded to the busbar 2. At the same time, each bent negative tab group 4 abuts against the busbar 2 on the same side, and each negative tab group 4 is welded to the busbar 2. Thus, the busbar 2 is clamped between the core 1 and the positive tab group 3 / negative tab group 4. The thickness of the busbar 2 is greater than the thickness of the positive tab group 3 and the negative tab group 4. When welding the busbar 2 to the positive tab group 3 / negative tab group 4 using a laser, the laser first passes through the positive tab group 3 / negative tab group 4 with a smaller thickness, and then passes through the busbar 2 with a larger thickness. Therefore, a smaller welding energy can be used to achieve the welding connection between the positive tab group 3 / negative tab group 4 and the busbar 2. Even if the welding energy fluctuates, it is not sufficient to penetrate the busbar 2 with a larger thickness, which is equivalent to adding a protective plate at both ends of the core 1 and can prevent welding slag from entering the core 1.
[0033] By adopting the core assembly of the present invention, the busbar 2 is arranged between the end face of the core 1 and the positive tab group 3 / negative tab group 4, which can effectively prevent the busbar 2 from being penetrated during the welding process, thereby preventing welding slag from entering the inside of the core 1 and causing a short circuit, and avoiding safety accidents.
[0034] As Figures 1 - 3As shown, in this embodiment, the central regions of the opposite end faces of the core 1 are flat blank areas, and no tabs are provided, so as to facilitate the placement of the current collector plate 2. The positive tab group 3 and the negative tab group 4 are respectively provided with three groups, and are equally spaced in the circumferential direction of the core 1 near the outer wall. Each positive tab group 3 / negative tab group 4 includes a plurality of stacked positive tabs 301 / negative tabs 401. The cross-section of the current collector plate 2 is circular, and the diameter is slightly smaller than the cross-section diameter of the core 1, so that after being placed in the blank area on the end face of the core 1, it will not interfere with the circumferential positive tab group 3 or negative tab group 4. After the current collector plate 2 is placed on the end face of the core 1, each positive tab group 3 / negative tab group 4 is bent and flattened towards the current collector plate 2, and finally abuts against the current collector plate 2 and is welded. As Figure 3 shown, after the positive tab group 3 / negative tab group 4 is bent and flattened to the current collector plate 2, the central region of the current collector plate 2 does not cover the positive tab group 3 / negative tab group 4, and a liquid injection hole can be provided through this region to inject electrolyte into the core 1. According to the actual application situation, the positive tab group 3 and the negative tab group 4 can be bent to abut against the current collector plate 2 by any process, the set number of the positive tab group 3 and the negative tab group 4 can be adjusted, and the range of the blank area and the specific specification dimensions of the current collector plate 2 can also be adjusted accordingly.
[0035] Optionally, a plurality of placement grooves 201 are provided on the surface of each current collector plate 2 facing away from the core 1. After each positive tab group 3 and each negative tab group 4 are bent, they are respectively inserted into one of the placement grooves 201 and are welded to the current collector plate 2 in the placement groove 201. With this setting, when welding the positive tab group 3 / negative tab group 4 to the current collector plate 2, the horizontal flow range of the molten metal can be restricted by the placement groove 201, and the horizontal spatter range of the welding slag can also be restricted, preventing the horizontal ejection range of the molten metal and the welding slag from being too large and harming the surrounding operators.
[0036] As Figure 2As shown, in this embodiment, three sets of positive electrode tab groups 3 and three sets of negative electrode tab groups 4 are respectively provided. Correspondingly, three placement grooves 201 are formed on the surface of each current collector plate 2 facing away from the core 1, and the shape and size of the placement grooves 201 match those of the positive electrode tab groups 3 and the negative electrode tab groups 4, so that the positive electrode tab groups 3 and the negative electrode tab groups 4 can be smoothly placed in the placement grooves 201 after being bent. The depth of the placement grooves 201 is slightly greater than the thickness of the positive electrode tab groups 3 and the negative electrode tab groups 4, so that the placement grooves 201 can effectively block the welding metal splash. The number of the placement grooves 201 and their specific opening positions on the current collector plate 2 are adjusted accordingly according to the number and position distribution of the positive electrode tab groups 3 and the negative electrode tab groups 4.
[0037] Optionally, the depth of the placement grooves 201 is 0.2 - 1.5 mm. With this setting, the positive electrode tab groups 3 and the negative electrode tab groups 4 can be completely placed in the placement grooves 201, so that when welding is performed, the molten metal and the horizontally splashing welding slag will not shoot out from the placement grooves 201, and at the same time, it can ensure that after the placement grooves 201 are opened, the current collector plate 2 has sufficient thickness, so that the current collector plate 2 will not be welded through during welding and the welding slag will not enter the core 1.
[0038] Figure 4 is Figure 1 a schematic diagram of the positive electrode sheet in the shown core; Figure 5 is Figure 1 a schematic diagram of the negative electrode sheet in the shown core. As Figures 1 - 5As shown, optionally, each of the placement grooves 201 includes a first placement groove 2011 and a second placement groove 2012 that are connected, and the width of the first placement groove 2011 is greater than the width of the second placement groove 2012; each positive electrode tab 301 includes a connected first bent portion 3011 and a first welding portion 3012, and the width of the first welding portion 3012 is greater than the width of the first bent portion 3011. The first welding portion 3012 is disposed in the first placement groove 2011 on the same side and is welded to the bus bar 2, and the first bent portion 3011 is connected to the core 1 and is disposed in the second placement groove 2012 on the same side; each negative electrode tab 401 includes a connected second bent portion 4011 and a second welding portion 4012, and the width of the second welding portion 4012 is greater than the width of the second bent portion 4011. The second welding portion 4012 is disposed in the first placement groove 2011 on the same side and is welded to the bus bar 2, and the second bent portion 4011 is connected to the core 1 and is disposed in the second placement groove 2012 on the same side. With this arrangement, by welding the first welding portion 3012 / second welding portion 4012 with a larger width to the first placement groove 2011, the welding area between the positive electrode tab group 3 and the negative electrode tab group 4 and the bus bar 2 is increased, and the connection strength is enhanced. By means of the second placement groove 2012 with a smaller width, the horizontal movement of the molten metal and welding slag can be restricted within a smaller range, further preventing harm to surrounding personnel.
[0039] As Figure 4 shown, in this embodiment, the cross-sections of the first bent portion 3011 and the first welding portion 3012 of the positive electrode tab 301 are both set to be rectangular, and the width of the first welding portion 3012 is greater than the width of the first bent portion 3011, about twice the width of the first bent portion 3011, and the height of the first welding portion 3012 is slightly greater than the height of the first bent portion 3011. Similarly, as Figure 5 shown, the cross-sections of the second bent portion 4011 and the second welding portion 4012 of the negative electrode tab 401 are both set to be rectangular, and the width of the second welding portion 4012 is greater than the width of the second bent portion 4011, about twice the width of the second bent portion 4011, and the height of the second welding portion 4012 is slightly greater than the height of the second bent portion 4011. As Figure 2 、 Figure 3As shown, the size of the first placement groove 2011 matches that of the first welding part 3012 / second welding part 4012, and the size of the second placement groove 2012 matches that of the first bending part 3011 / second bending part 4011. To enable the positive electrode tab group 3 and the negative electrode tab group 4 to be smoothly and correspondingly arranged in the placement groove 201 after bending, the width and height of the first placement groove 2011 and the second placement groove 2012 can be slightly larger than those of the first welding part 3012 / second welding part 4012 and the first bending part 3011 / second bending part 4011 respectively. In addition, the positive electrode tabs 301 and the negative electrode tabs 401 adopt a "large head and small tail" design, which can also reduce the number of tabs arranged. 30 - 150 positive electrode tabs 301 and negative electrode tabs 401 are respectively arranged on the positive electrode plate 6 and the negative electrode plate 7. In this embodiment, the base material of the positive electrode tab 301 is aluminum foil or carbon-coated aluminum foil, the base material of the negative electrode tab 401 is copper foil, and the width range of the first bending part 3011 and the second bending part 4011 is 3 - 20 mm. According to the actual application situation, the first welding part 3012 and the second welding part 4012 can also be set in shapes such as circular, oval, triangular, and rhombic.
[0040] Figure 6 Schematic diagram of the polymer composite film covering the positive electrode tab. As Figure 1 , Figure 2 and Figure 6 shown, optionally, one side surface of each positive electrode tab group 3 facing away from the core 1 after bending is covered with a polymer composite film 5; and / or, one side surface of each negative electrode tab group 4 facing away from the core 1 after bending is covered with a polymer composite film 5. The polymer composite film 5 does not melt or decompose at high temperatures. With the above setting, it can effectively block the splashing of welding debris by means of the polymer composite film 5 and prevent the debris from splashing outwards during the welding process and causing harm to the surrounding personnel.
[0041] As Figure 1 , Figure 2 shown, in this embodiment, the polymer composite film 5 covers one side surface of the outermost positive electrode tab 301 / negative electrode tab 401 in each positive electrode tab group 3 / negative electrode tab group 4 facing away from the axis of the core 1, and the connection between the polymer composite film 5 and the positive electrode tab 301 / negative electrode tab 401 is realized by bonding or ultrasonic welding. As Figure 6 shown, specifically, the polymer composite film 5 covers the surface of the first welding part 3012 / second welding part 4012 of the outermost positive electrode tab 301 / negative electrode tab 401. The material used for the polymer composite film 5 is one or several of polyimide (PI), polymethyl methacrylate (PMMA), polystyrene (PS), and polycarbonate (PC).
[0042] Optionally, the thickness of the polymer composite film 5 is 0.5-2 mm. With this setting, the polymer composite film 5 is thick enough to play a blocking role, and during the welding process of the bus bar 2 and the positive electrode tab 301 / negative electrode tab 401, it will not melt or decompose, and can effectively block the splashing of welding debris. At the same time, the manufacturing cost of the polymer composite film 5 is reduced.
[0043] Optionally, the light transmittance of the polymer composite film 5 is greater than 90%. With this setting, when laser welding the bus bar 2 and the positive electrode tab 301 / negative electrode tab 401, the laser can pass through the polymer composite film 5 more fully, so that the welding operation can be carried out smoothly.
[0044] In this embodiment, the light transmittance of the polymer composite film 5 is greater than 90%, and under the welding conditions of a laser speed of 300 mm / s and a laser power of 1000 W, the polymer composite film 5 does not melt and does not decompose, and can effectively block and absorb metal splashes.
[0045] Optionally, the bus bar 2 is evenly divided into multiple welding areas, and each welding area of the same bus bar 2 is welded to the corresponding positive electrode tab group 3 or negative electrode tab group 4.
[0046] As Figure 2 、 Figure 3 shown, in this embodiment, each circular bus bar 2 is divided into three identical fan-shaped areas, each fan-shaped area corresponds to a welding area, and a placement groove 201 is opened in each welding area for the positive electrode tab group 3 or the negative electrode tab group 4 to be bent and embedded for welding operations. According to the actual application situation, the specific number of welding areas divided by the bus bar 2 can be adjusted.
[0047] The safety during the welding process of the core assembly is evaluated through two tests below.
[0048] Example 1: Use the core assembly in the prior art. After the positive electrode tab / negative electrode tab is bent, it covers the end face of the core, and the bus bar covers the positive electrode tab / negative electrode tab.
[0049] Example 2: Use the core assembly in the present invention as Figure 2 shown.
[0050] Test 1
[0051] Respectively select 300 core assemblies in Example 1 and Example 2, and perform single-mode laser welding on the bus bars of the two core assemblies respectively. The welding powers are selected as 200 W, 400 W, 600 W, and 800 W for welding respectively. Keep other parameters unchanged, perform a short-circuit test on the core, and count the defective ratio.
[0052] As shown in Table 1 of the test results, when using lasers with welding powers of 200W, 400W, and 600W to weld the bus bar and the positive / negative tab groups, for the core assembly in the prior art of Example 1, the proportion of short-circuited cores shows an upward trend, while for the core assembly in the present invention of Example 2, the proportion of short-circuited cores is 0; when using a laser with a welding power of 800W to weld the bus bar and the positive / negative tab groups, all the cores in the core assemblies of the prior art in Example 1 are short-circuited, while in the core assembly of the present invention in Example 2, although some cores are short-circuited, the proportion of short-circuited cores is much smaller than that of the core assemblies in the prior art. The test results show that the core assembly in the present invention can greatly improve the laser welding window, prevent welding debris from splashing into the core, and essentially eliminate internal short circuits in the core.
[0053] Table 1 Comparison Results of Test 1
[0054]
[0055] Test 2
[0056] Use white paper to cover the end faces of the core assemblies in Example 1 and Example 2 respectively, cover the bus bar and the positive / negative tab groups, and only leave the laser entrance. Use a laser with a welding power of 400W to perform welding operations on the bus bar and the positive / negative tabs, and count and compare the number of black spots splashed on the white paper after welding.
[0057] As shown in Table 2 of the test results, the number of black spots on the white paper reflects the degree of splashing of the welding metal around during the welding process. For the core assembly in the prior art of Example 1, the number of black spots corresponding to the white paper is relatively large, indicating that during the welding process, the welding metal splashes severely; while for the core assembly in the present invention of Example 2, the number of black spots on the white paper is 0, indicating that under the combined action of the placement groove 201 to limit the horizontal direction of the welding metal and the polymer composite film 5 to limit the longitudinal direction of the welding metal, it can effectively prevent the welding metal from splashing around.
[0058] Table 2 Comparison Results of Test 2
[0059] Category Number of black dots on white paper Example 1 11 Example 2 0
[0060] The present invention also provides a cylindrical battery, including a housing, and further including the core assembly according to any one of the above embodiments, and the core assembly is disposed inside the housing.
[0061] When the cylindrical battery of the present invention is adopted, the busbar plate 2 is arranged between the end face of the wound core 1 and the positive tab group 3 / negative tab group 4, which can effectively prevent the busbar plate 2 from being penetrated during the welding process, thereby preventing welding slag from entering the inside of the wound core 1 and causing a short circuit, and avoiding triggering a safety accident.
[0062] Connect the positive electrode terminal on the busbar plate 2 on the side where the positive tab group 3 is located, and connect the positive end cap. Connect the negative electrode terminal on the busbar plate 2 on the side where the negative tab group 4 is located, and connect the negative end cap. Then, the whole is installed in the outer shell, and the opening of the outer shell is sealed with a cover, exposing the positive electrode terminal and the negative electrode terminal, and assembling into the cylindrical battery.
[0063] The present invention also provides a power battery pack, including the cylindrical battery described in the above embodiment.
[0064] When the power battery pack of the present invention is adopted, the busbar plate 2 is arranged between the end face of the wound core 1 and the positive tab group 3 / negative tab group 4, which can effectively prevent the busbar plate 2 from being penetrated during the welding process, thereby preventing welding slag from entering the inside of the wound core 1 and causing a short circuit, and avoiding triggering a safety accident.
[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A core assembly, characterized in that, comprising: a core, with a plurality of positive tab groups and a plurality of negative tab groups respectively arranged at opposite ends of the core. Each positive tab group includes a plurality of positive tabs stacked together, each negative tab group includes a plurality of negative tabs stacked together, and blank areas are respectively arranged on the end faces of opposite ends of the core; two current collector plates, the two current collector plates are respectively abutted against the two blank areas. After each positive tab group and each negative tab group are bent, they are respectively welded and connected to the surface of the corresponding current collector plate facing away from the core.
2. The core assembly according to claim 1, characterized in that: A plurality of placement grooves are formed on the surface of each current collector plate facing away from the core. After each positive tab group and each negative tab group are bent, they are respectively inserted into one of the placement grooves and are welded and connected to the current collector plate in the placement groove.
3. The core assembly according to claim 2, characterized in that: The depth of the placement groove is 0.2 - 1.5 mm.
4. The core assembly according to claim 2 or 3, characterized in that: Each placement groove includes a first placement groove and a second placement groove that are communicated, and the width of the first placement groove is greater than the width of the second placement groove; Each positive tab includes a connected first bent portion and a first welded portion, and the width of the first welded portion is greater than the width of the first bent portion. The first welded portion is arranged in the first placement groove on the same side and is welded and connected to the current collector plate, and the first bent portion is connected to the core and is arranged in the second placement groove on the same side; Each negative tab includes a connected second bent portion and a second welded portion, and the width of the second welded portion is greater than the width of the second bent portion. The second welded portion is arranged in the first placement groove on the same side and is welded and connected to the current collector plate, and the second bent portion is connected to the core and is arranged in the second placement groove on the same side.
5. The core assembly according to any one of claims 1 - 3, characterized in that: A polymer composite film covers the surface of each positive tab group facing away from the core after being bent; and / or, A polymer composite film covers the surface of each negative tab group facing away from the core after being bent.
6. The core assembly according to claim 5, characterized in that: The thickness of the polymer composite film is 0.5 - 2 mm.
7. The core assembly according to claim 5, characterized in that: The light transmittance of the polymer composite film is greater than 90%.
8. The core assembly according to any one of claims 1 - 3, characterized in that: The current collector plate is evenly divided into a plurality of welding areas, and each welding area of the same current collector plate is welded and connected to the corresponding positive tab group or negative tab group.
9. A cylindrical battery, including a housing, characterized in that, It further includes the core assembly according to any one of claims 1 - 8, and the core assembly is arranged inside the housing.
10. A power battery pack, It is characterized in that including the cylindrical battery described in claim 9