A cylindrical battery cell with multiple tabs and its assembly method

Abstract

This invention relates to a fully tabbed cylindrical battery cell and its assembly method, belonging to the field of power battery technology. In the fully tabbed cylindrical battery cell disclosed in this invention, when connecting the cell terminal to the electrode assembly inside the cell housing, it is necessary to first weld the current collector to the cell tab, then weld the current collector to the cell terminal, and finally install the electrode assembly into the housing before fixing the cell terminal to the end wall of the housing. Currently, most fully tabbed cylindrical batteries have a double-ended tab structure, and the frequent welding processes significantly affect battery production efficiency. Furthermore, the numerous structural components occupy the effective internal space of the cell, reducing its energy density.

Description

Technical Field

[0001] This invention belongs to the field of power battery technology and relates to a cylindrical cell with multiple tabs and its assembly method. Background Technology

[0002] Traditional cylindrical batteries have undergone many years of development, and many technologies have matured. However, there are still many significant technical bottlenecks, mainly manifested in the following aspects:

[0003] (1) High internal resistance and large heat generation: The tab design of traditional cylindrical batteries results in a long electron migration path. When the current converges through the copper and aluminum foils, the resistance increases significantly, which in turn generates a lot of ohmic heat. For example, in high torque output scenarios of power tools (such as tightening bolts with an electric wrench or cutting wood with a chainsaw), traditional batteries generate a lot of heat due to their high internal resistance, making it difficult to meet the demand for continuous and efficient output.

[0004] (2) Heat dissipation problem: As the size of the battery cell increases and the proportion of active material increases, the system integration efficiency improves, but the heat generation also increases simultaneously. Traditional tab designs cannot effectively solve the heat dissipation problem of large-size battery cells, limiting their application in high-energy-density scenarios. For example, early Tesla models suffered from range reduction due to insufficient battery heat dissipation.

[0005] (3) The conflict between power and safety: high-power applications require batteries to support fast charging and discharging, but traditional designs are prone to overheating when increasing power, and may even cause safety hazards (such as fire or explosion). For example, when drones fly at high speeds, the battery needs to release a large current instantly, and traditional batteries cannot balance power and safety.

[0006] Traditional top-cover battery structures require: welding (riveting) of positive / negative cover plate terminals, welding of positive / negative electrode tabs to current collectors, welding of positive / negative current collectors to cover plate terminals (required for some structures), and sealing welding of positive / negative cover plates to the casing. A total of 6-8 welding processes are required. The positive / negative cover plate structure includes: current collectors, lower electrode posts, lower plastic parts, sealing gaskets, upper insulating pads, upper electrode posts, etc.

[0007] Therefore, it is necessary to develop technologies related to omni-tab cells, which can significantly reduce the internal resistance of batteries. Summary of the Invention

[0008] In view of this, one objective of the present invention is to provide an assembly method for a full-tab cylindrical battery cell; another objective of the present invention is to provide a full-tab cylindrical battery cell.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] 1. A method for assembling a fully tabbed cylindrical battery cell, the assembly method comprising the following steps:

[0011] (1) Place the core 11 into the cylindrical shell 10 with one end open;

[0012] (2) Weld the positive electrode tab of the core to the positive end cap at the bottom of the cylindrical shell 10 with full area welding;

[0013] (3) The negative electrode tab of the strong core is welded to the negative electrode current collector 6 in the whole circumference;

[0014] (4) The protrusion of the elastic full-circumference disk passes through the negative electrode cover plate 3 and is welded to the pressure ring in the full circumference.

[0015] (5) The negative electrode cover plate 3 and the opening of the cylindrical shell 10 are sealed and welded in the whole circumference.

[0016] Preferably, the first insulating pad 5 and the upper plastic part of the negative electrode cover plate assembly are provided with mounting holes for easy positioning and installation before the negative electrode cover plate, and a sealing gasket is provided between the first insulating pad 5 and the negative electrode cover plate 3 to increase the structural sealing performance. The negative electrode cover plate assembly is integrally connected.

[0017] The negative electrode cover plate 3 has a through hole structure. After the current collector plate part of the negative electrode current collector 6 is welded to the negative electrode tab, the electrode post 7 part passes through the through hole of the negative electrode cover plate 3 and connects with the pressure ring 1 to form a complete negative electrode electrode post terminal. The connection part is sealed by laser welding. The first insulating pad 5 and the second insulating pad 2 cooperate to make the metal parts of the negative electrode current collector 6 and the negative electrode cover plate 3 insulated.

[0018] Preferably, the cylindrical shell 10 has a semi-through hole structure;

[0019] The positive electrode tab and the positive end cap are directly welded using laser penetration.

[0020] 2. The all-tab cylindrical cell assembled using the above assembly method.

[0021] Preferably, the full-tab cylindrical battery cell includes a negative electrode cover plate 3, a negative electrode current collector 6, a core 11, and a cylindrical shell 10.

[0022] More preferably, the negative electrode cover plate assembly includes: a first insulating pad 5, a sealing ring 4, a negative electrode cover plate 3, a second insulating pad 2, and a pressure ring 1; the negative electrode current collector includes a negative electrode current collector disk and an electrode post 7.

[0023] A first insulating pad 5 is provided between the negative electrode current collector 6 and the negative electrode cover plate 3, and a second insulating pad 2 is provided between the pressure ring 1 and the negative electrode cover plate 3;

[0024] An explosion-proof valve 31 is provided on the negative electrode cover plate 3, and an explosion-proof valve protection plate 32 is provided on the explosion-proof valve 31.

[0025] The negative electrode current collector 6 is provided with centrally symmetrical curved welding notches, wherein a first hollow area 61 and a second hollow area 62 are provided between adjacent curved welding notches to reduce weight and increase elasticity;

[0026] A sealing ring 4 is provided between the first insulating pad 5 and the negative electrode cover plate 3;

[0027] The curved welding notch is inverted U-shaped and the opening faces the center of the negative electrode current collector 6. The opening size of the welding notch is smaller than the bottom size.

[0028] More preferably, the positive end cap of the full-tab cylindrical battery cell is provided with an annular welding thinning area 8, and the positive electrode tab of the core 11 is symmetrically and uniformly welded to the welding thinning area 8 along the center.

[0029] An injection hole 9 is provided at the center of the positive end cap.

[0030] The beneficial effects of this invention are as follows: This invention discloses a full-tab cylindrical battery cell, mainly comprising a negative electrode cover plate 3, a negative electrode current collector 6, a core 11, and a cylindrical shell 10. In this invention, when connecting the battery cell terminal to the electrode assembly inside the battery shell, the current collector needs to be welded to the battery cell tab first, then the current collector needs to be welded to the battery cell terminal, and finally the electrode assembly needs to be installed into the shell before fixing the battery cell terminal to the end wall of the shell. Currently, most full-tab cylindrical batteries have a double-ended tab structure, and the frequent welding processes significantly affect battery production efficiency. Furthermore, the numerous structural components occupy the effective internal space of the battery cell, reducing its energy density. In this invention, the positive electrode tab of the full-tab cylindrical battery cell is directly welded to the cylindrical shell 10, while the negative electrode terminal 7 extends elastically. This reduces the number of welding operations, increases the welding area while reducing the number of components, thereby improving battery production efficiency and increasing the battery cell energy density.

[0031] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0033] Figure 1 Front view of a fully tabbed cylindrical battery cell;

[0034] Figure 2 Exploded view of the structure of the negative electrode cover plate assembly of a cylindrical battery cell with multiple tabs;

[0035] Figure 3 It is a structure for the negative electrode current collector of a cylindrical battery cell with multiple tabs;

[0036] Figure 4 Diagram of the positive terminal structure of a cylindrical battery cell with multiple tabs;

[0037] Figure 5 Cross-sectional view of the negative electrode structure of a cylindrical battery cell with multiple tabs;

[0038] Figure 6 This is a cross-sectional view of the overall structure of a cylindrical battery cell with multiple tabs.

[0039] Among them, 1 is the pressure ring, 2 is the second insulating pad, 3 is the negative electrode cover plate, 31 is the explosion-proof valve, 32 is the explosion-proof valve protection plate, 4 is the sealing ring, 5 is the first insulating pad, 6 is the negative electrode current collector, 61 is the first hollow area, 62 is the second hollow area, 7 is the pole post, 8 is the welding thinning area, 9 is the liquid injection hole, 10 is the cylindrical shell, and 11 is the core. Detailed Implementation

[0040] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0041] Example 1

[0042] The specific method for preparing an all-tab cylindrical battery cell is as follows:

[0043] 1. Prepare the cylindrical shell 10 of the battery cell, the pressure ring 1, the second insulating pad 2, the negative electrode cover plate 3, the core 11 and other mechanical components, wherein one end of the cylindrical shell 10 of the battery cell is open, the diameter is 30mm to 70mm and the wall thickness is 0.3mm to 0.8mm.

[0044] 2. Mounting holes are provided between the first insulating pad 5, the second insulating pad 2, and the negative electrode cover plate 3 for easy positioning and installation. A sealing ring 4 is provided between the first insulating pad 5 and the negative electrode cover plate 3 to increase the sealing performance of the structure. The negative electrode cover plate assembly is connected by injection molding. The thickness of the negative electrode cover plate 3 is 1.2mm~3mm. In addition, an explosion-proof valve 31 (the diameter of the explosion-proof valve 31 is 2mm~7mm) is provided on the negative electrode cover plate 3, and an explosion-proof valve protection plate 32 is covered on it. The explosion-proof pressure is 0.6Mpa~2.5Mpa.

[0045] 3. The negative electrode current collector 6 is provided with a pole post 7 above and welded to the battery cell tab below. A welding notch is provided to provide buffer space when the battery cell shakes, improve shock resistance, and reduce the tab tearing caused by stress. A first hollow area 61 and a second hollow area 62 are provided to reduce the weight of the structure and improve the overall energy density of the battery cell.

[0046] 4. The electrode post 7 passes through the first insulating pad 5, the sealing ring 4, the negative electrode cover plate 3, the second insulating pad 2, and the pressure ring 1 in sequence, and connects with the inner ring of the pressure ring 1. The connection part is sealed by laser welding. In some embodiments, a downward pressure is applied to the electrode post, causing the electrode post 7 to deform and making the fit between it and the other components tighter.

[0047] 5. The positive electrode tab is connected to the lower cover of the positive electrode. A welding thinning zone 8 is set to improve the welding quality and efficiency. The cylindrical shell 10 outside the cell carries the positive electrode charge, which can effectively prevent the cell shell from being oxidized and corroded. An injection hole 9 is set in the center to improve the injection efficiency and the wetting of the electrode by the electrolyte.

[0048] 6. Further helium leak testing of the battery cells and inspection of welding quality;

[0049] Figure 1 Front view of a fully tabbed cylindrical battery cell; Figure 2 Exploded view of the structure of the negative electrode cover plate assembly of a cylindrical battery cell with multiple tabs; Figure 3 It is a structure for the negative electrode current collector of a cylindrical battery cell with multiple tabs; Figure 4 Diagram of the positive terminal structure of a cylindrical battery cell with multiple tabs; Figure 5 Cross-sectional view of the negative electrode structure of a cylindrical battery cell with multiple tabs; Figure 6 This is a cross-sectional view of the overall structure of a cylindrical battery cell with multiple tabs; where 1 is the pressure ring, 2 is the second insulating pad, 3 is the negative electrode cover plate, 31 is the explosion-proof valve, 32 is the explosion-proof valve protection plate, 4 is the sealing ring, 5 is the first insulating pad, 6 is the negative electrode current collector, 61 is the first hollow area, 62 is the second hollow area, 7 is the electrode post, 8 is the welding thinning area, 9 is the liquid injection hole, 10 is the cylindrical shell, and 11 is the core.

[0050] In this invention, the cylindrical shell 10 of the battery cell has a semi-through hole structure. The positive electrode tab and the positive end cap are directly welded using laser penetration welding. The welding area is large, the process is simple, and the current carrying capacity is strong. During the welding process, due to the thickness of the positive end cap, problems such as incomplete welding or weld penetration are easily caused by the flatness of the positive electrode tab or welding power issues. Therefore, a welding thinning zone 8 is set in the welding area of ​​the positive end cap tab to avoid the above risks. Subsequently, the negative electrode cover plate 3 and its series components are sealed and welded to the cylindrical shell 10, and the overall assembly is completed.

[0051] This invention involves welding the positive electrode tab to the lower positive electrode cover, allowing a very dense aluminum oxide passivation film to rapidly form on the aluminum at the high potential of the positive electrode. This prevents the cylindrical casing 10 from being electrochemically corroded and oxidized during operation, thus extending the battery cell's lifespan.

[0052] Traditional top-cover battery structures require: welding (riveting) the positive / negative electrode cover terminals, welding the positive / negative electrode tabs to the current collector, welding the positive / negative electrode current collector to the cover terminals (required in some structures), and sealing welding of the positive / negative electrode cover to the casing, totaling 6-8 welding steps. Furthermore, the traditional positive / negative electrode cover structure includes: current collector, lower electrode post, first insulating pad, sealing gasket, upper insulating pad, upper electrode post, etc., resulting in numerous components. This invention patent provides a battery structure and assembly scheme requiring only 4 welding steps, reducing the number of structural components by half while retaining functionality. It maximizes the utilization of the effective internal space of the cell, improves the cell's energy density, and fully solves the technical problems existing in the prior art.

[0053] In summary, this invention discloses a fully tabbed cylindrical battery cell, mainly comprising a negative electrode cover plate 3, a negative electrode current collector 6, a core 11, and a cylindrical shell 1. When connecting the battery cell terminals to the electrode assembly inside the battery shell, the current collector needs to be welded to the battery cell tabs first, then welded to the battery cell terminals, and finally, after the electrode assembly is installed into the shell, the battery cell terminals are fixed to the end walls of the shell. Currently, most fully tabbed cylindrical batteries have a double-ended tab structure, and the frequent welding processes significantly affect battery production efficiency. Furthermore, the numerous structural components occupy valuable internal space, reducing the battery's energy density.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for assembling a fully tabbed cylindrical battery cell, characterized in that, The assembly method includes the following steps: (1) Place the core (11) into the cylindrical shell (10) that is open at one end; (2) Weld the positive electrode tab of the core to the positive end cap at the bottom of the cylindrical shell (10) with full area; (3) The negative electrode tab of the strong core is welded to the negative current collector (6) in the whole circumference; (4) The protrusion of the elastic full-circumference disk passes through the negative electrode cover plate (3) and is then welded to the pressure ring in the full circumference. (5) The negative electrode cover plate (3) and the opening of the cylindrical shell (10) are sealed and welded in the whole circumference.

2. The assembly method of the all-tab cylindrical battery cell according to claim 1, characterized in that, The first insulating pad (5) and the upper plastic part of the negative electrode cover plate assembly are provided with mounting holes for easy positioning and installation before the negative electrode cover plate. A sealing gasket is provided between the first insulating pad (5) and the negative electrode cover plate (3) to increase the structural sealing performance. The negative electrode cover plate assembly is an integral connection. The negative electrode cover plate (3) has a through hole structure. After the current collector plate part of the negative electrode current collector component (6) is welded to the negative electrode tab, the pole post (7) part passes through the through hole of the negative electrode cover plate (3) and connects with the pressure ring (1) to form a complete negative electrode pole post terminal. The connection part is sealed by laser welding. The first insulating pad (5) and the second insulating pad (2) cooperate to make the negative electrode current collector component (6) and the metal parts of the negative electrode cover plate (3) insulated.

3. The assembly method of the all-tab cylindrical battery cell according to claim 1, characterized in that, The cylindrical shell (10) has a semi-through hole structure; The positive electrode tab and the positive end cap are directly welded using laser penetration.

4. The all-tab cylindrical cell assembled by the assembly method of any one of claims 1 to 3.

5. The all-tab cylindrical battery cell according to claim 4, characterized in that, The full-tab cylindrical battery cell includes a negative electrode cover plate (3), a negative electrode current collector (6), a core (11), and a cylindrical shell (10).

6. The all-tab cylindrical battery cell according to claim 5, characterized in that, The negative electrode cover plate assembly includes: a first insulating pad (5), a sealing ring (4), a negative electrode cover plate (3), a second insulating pad (2), and a pressure ring (1). The negative electrode current collector includes a negative electrode current collector plate and an electrode post (7). A first insulating pad (5) is provided between the negative electrode current collector (6) and the negative electrode cover plate (3), and a second insulating pad (2) is provided between the pressure ring (1) and the negative electrode cover plate (3). An explosion-proof valve (31) is provided on the negative electrode cover plate (3), and an explosion-proof valve protection plate (32) is provided on the explosion-proof valve (31). The negative electrode current collector (6) is provided with curved welding notches arranged symmetrically in the center, wherein a first hollow area (61) and a second hollow area (62) are provided between adjacent curved welding notches to reduce weight and increase elasticity. A sealing ring (4) is provided between the first insulating pad (5) and the negative electrode cover plate (3); The curved welding notch is inverted U-shaped and the opening faces the center of the negative current collector (6). The opening size of the welding notch is smaller than the bottom size.

7. The all-tab cylindrical battery cell according to claim 6, characterized in that, The positive end cap of the full-tab cylindrical battery cell is provided with an annular welding thinning area (8), and the positive electrode tab of the core (11) is symmetrically and uniformly welded on the welding thinning area (8) along the center. An injection hole (9) is provided at the center of the positive end cap.

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