A cylindrical battery

Abstract

The utility model relates to battery technology field, concretely relates to a cylindrical battery, disclose the cylindrical shell, first end cover and second end cover, winding core, winding core's first end and second end are provided with a plurality of pole lug respectively, first current collector and second current collector are correspondingly arranged with first end cover and second end cover, the pole lug of winding core second end is connected with second current collector, wherein, first end cover and first current collector are integrally formed, a plurality of first open hole is seted up on first current collector, the inner wall on first open hole is seted up with fixed groove, fixed groove is located the upper surface of first current collector, the tail end of at least part pole lug of winding core first end is embedded and fixed in fixed groove, the utility model can increase the filling space of electrode active material to improve the volume energy density of battery.

Description

Technical Field

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

[0002] With the continuous increase in the market penetration rate of new energy vehicles, high-energy-density cylindrical batteries have become a key development direction in the field of power batteries. In existing large cylindrical batteries, the current collector and end cap (or end cap) are separate structures, and a boss or peripheral bend is formed at the connection between the two to enable welding between the current collector and the end cap. At the same time, an annular hollow groove is opened on the current collector for the tab to pass through, and the tab that passes through the annular hollow groove is bent down and attached to the surface of the current collector. Then the tab is welded to the surface of the current collector to achieve connection.

[0003] However, existing large cylindrical batteries have the following drawbacks: the welding between the current collector and the end cap is achieved by forming a boss or a peripheral bend, which inevitably occupies the axial space of the battery and limits the height of the core. At the same time, when the tabs lying on the surface of the current collector are welded to the current collector, weld points will inevitably be formed on the current collector. The thickness of the weld points will further compress the filling space of the electrode active material, ultimately resulting in a low energy density of the battery. Utility Model Content

[0004] In view of this, the present invention provides a cylindrical battery to solve the problem of low energy density of batteries.

[0005] In a first aspect, this utility model provides a cylindrical battery, comprising: Cylindrical shell; The first end cap and the second end cap are respectively disposed at both ends of the cylindrical shell; A winding core is disposed inside the cylindrical housing, and a plurality of tabs are respectively provided at the first end and the second end of the winding core; The first collector plate and the second collector plate are respectively provided corresponding to the first end cap and the second end cap. The tab at the second end of the core is connected to the second collector plate. The first end cap and the first collector plate are integrally formed. The first collector plate has a plurality of first hollow holes. The inner wall of the first hollow holes has a fixing groove. The fixing groove is located on the upper surface of the first collector plate. At least a portion of the ends of the tabs at the first end of the core are embedded and fixed in the fixing groove.

[0006] Beneficial effects: The battery of this utility model adopts an integral molding of the first end cover and the first current collector, plus a mechanical limiting structure between the electrode tab and the first current collector. The first end cover and the first current collector are integrated, eliminating the design of the separate structure of the end cover and the current collector forming a boss or peripheral bend at the connection interface, which significantly increases the core height. The embedded mechanical limiting structure formed by the end of the electrode tab and the fixing groove opened in the first hollow hole avoids the need for the electrode tab to be bent and welded to the current collector, and the thickness of the weld point occupies the internal space of the battery, saving the internal space of the battery and indirectly increasing the filling space of the electrode active material, thereby improving the volumetric energy density of the battery.

[0007] In one optional embodiment, a step is formed between the inner wall of the fixing groove and the inner wall of the first hollow hole; At least a portion of the end of the tab at the first end of the core abuts against the stepped surface.

[0008] Beneficial effects: When the core is inserted into the cylindrical shell, the end of the electrode lug is first embedded in the first hollow hole and comes into contact with the end of the first hollow hole (that is, the end face of the first end cap). The end of the electrode lug is deformed by the force, bends, and is embedded in the fixing groove, so that one side of the end of the electrode lug fits against the step surface of the step, thus limiting the electrode lug along the axial direction of the cylindrical shell.

[0009] In one optional embodiment, at least a portion of the ends of the tabs at the first end of the core are provided with a plurality of legs, the legs being arranged around the ends of the corresponding tabs, and the ends of the tabs being embedded and fixed in the fixing grooves by the plurality of legs.

[0010] Beneficial effect: The support legs are arranged around the end of the electrode lug, which helps to limit the electrode lug in the circumferential direction.

[0011] In one alternative embodiment, the first perforation is a polygonal hole, and a plurality of the first perforations are arranged at intervals around the center of the first collector plate.

[0012] Beneficial effects: Since the first hollow hole is a polygonal hole, the bottom of the fixing groove will also form a folded surface corresponding to multiple vertices of the polygonal hole. That is, the bottom of the fixing groove is formed by multiple planes connected end to end, forming a regular polygonal groove bottom outline. In other words, the bottom surface of the fixing groove is a non-smooth surface composed of multiple planes. When the support leg is embedded in the fixing groove, the end of the support leg will form an angle with the bottom of the fixing groove, and the two adjacent planes will restrict the rotational freedom of the support leg, thereby avoiding loosening between the electrode tab and the first collector plate.

[0013] In one optional embodiment, the first collector plate is provided with a plurality of connecting grooves, which are spaced apart around the center of the first collector plate. The annular ring formed by the plurality of connecting grooves is located radially inside the annular ring formed by the plurality of first hollow holes. At least a portion of the end of the tab at the first end of the winding core is embedded in the connecting groove and abuts against the side or bottom surface of the connecting groove.

[0014] Beneficial effects: This design ensures that the feet of this part of the tabs form a dual function of "mechanical limit + electrical connection" after passing through the connecting groove, which has the effect of optimizing the current path and improving space utilization.

[0015] In one optional embodiment, the first collector plate is provided with a plurality of collector channels spaced apart around the center of the first collector plate, and the collector channels extend radially along the first collector plate, with the distance between two adjacent peaks of the collector channels being 1-3 mm.

[0016] Beneficial effects: The current collection channel can expand the current conduction area. The distance between two adjacent peaks of the current collection channel is 1-3mm, which is conducive to improving the current conduction efficiency.

[0017] In one optional embodiment, the inner wall of the cylindrical shell is provided with guide ribs, which are equal pitch helical ribs with a helix angle α of 30°-60°.

[0018] Beneficial effects: Setting the guide ribs as equal pitch spiral ribs is beneficial for guiding the electrolyte flow in a directional manner, and limiting the spiral angle α of the guide ribs to 30°-60° to ensure that the guide ribs guide the electrolyte flow at a more reasonable angle and with higher efficiency.

[0019] In one optional embodiment, a flow channel extending axially is provided on the inner wall of the cylindrical shell. The flow channel has a periodically undulating waveform on the inner wall of the cylindrical shell, and the spacing between adjacent peaks of the waveform is H, wherein the value of H gradually decreases from the first end to the second end. The height of the waveform is 0.5-2mm.

[0020] Beneficial effects: The flow channel can gradually decrease the spacing H between its waveform peaks from the first end to the second end, forming a strength difference design at both ends of the cylindrical shell on the inner wall. This can absorb the local stress peaks during charging and discharging, avoid fatigue cracking of the shell sidewall caused by long-term alternating stress, and limit the height of the waveform to 0.5-2mm, which can ensure that the flow channel absorbs the local stress peaks during charging and discharging most effectively.

[0021] In one alternative implementation, the height of the waveform at the first end is 1.5-2 mm, and the height of the waveform at the second end is 0.5-1 mm.

[0022] Beneficial effects: The height of the first end is 1.5-2mm, and the height of the waveform at the second end is 0.5-1mm. This more effectively absorbs local stress peaks at both ends of the inner wall of the cylindrical shell along the axial direction, thus better preventing fatigue cracking of the cylindrical shell.

[0023] In one optional embodiment, a plurality of contact pieces are arrayed on the second current collector, and the contact pieces are electrically connected to the tabs at the second end of the winding core. The second end cap is provided with a honeycomb support frame, which abuts against the contact piece.

[0024] Beneficial effects: By abutting the honeycomb support frame and the contact piece, a three-dimensional current collection interface can be formed, which improves the uniformity of current distribution and avoids local overcurrent. The current of traditional current collectors tends to concentrate near the solder joint of the tab, resulting in excessively high local current density, which can cause the tab to melt or the active material to de-embed. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is an exploded view along the axial direction of a cylindrical battery according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of the winding core in the cylindrical battery according to an embodiment of the present invention; Figure 3 for Figure 2 A schematic diagram showing another perspective of the winding core; Figure 4 This is a partial cross-sectional view of the cylindrical casing in the cylindrical battery according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the first current collector in a cylindrical battery according to an embodiment of the present invention; Figure 6 This is an assembly diagram of the first current collector, the winding core, and the second current collector in a cylindrical battery according to an embodiment of the present invention. Figure 7 for Figure 6 An enlarged schematic diagram of part A in the middle; Figure 8This is a schematic diagram of the second current collector and the second end cap in a cylindrical battery according to an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 1. Cylindrical shell; 11. Guide rib; 12. Guide channel; 2. Core; 21. Electrode; 22. Support foot; 3. First end cap; 4. Second end cap; 41. Honeycomb support frame; 5. First collector plate; 51. First hollow hole; 52. Fixing groove; 53. Connecting groove; 54. Collector channel; 55. Second hollow hole; 6. Second collector plate; 61. Contact piece; 7. Peripheral part. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0029] Cylindrical battery technologies commonly employ a process of creating annular slots in the current collector for the tabs to pass through and then weld. While this method helps reduce welding slag and improve energy density to some extent, the overall structure still has several drawbacks: First, it has low space utilization. Since the current collector and end cap are usually separate designs, they rely on mechanical interfaces such as bosses and peripheral bends for connection. These structures significantly encroach on the axial space inside the battery, thus limiting the effective increase in core height. Second, after passing through the slots, the tabs need to be bent over and attached to the surface of the current collector for welding. The thickness of the weld itself further compresses the volume that could be used to fill the electrode active material, limiting the potential for increasing energy density. In addition, this type of structure also results in a suboptimal current transmission path, leading to problems such as high conduction resistance and uneven heat dissipation. At the same time, it is difficult to balance the contradiction between the structural strength of the casing and the internal volume. Based on the aforementioned practical pain points, this utility model designs an integrated cylindrical battery structure, aiming to achieve comprehensive improvements in space efficiency, current path shortening, and structural strength enhancement by optimizing the tab connection method and the overall layout of the end cap-current collector.

[0030] Combination Figures 1 to 8 The following describes embodiments of the present invention.

[0031] According to embodiments of the present invention, see reference Figure 1 The cylindrical battery of this utility model includes a cylindrical shell 1, a first end cap 3, a second end cap 4, a core 2, a first current collector 5, and a second current collector 6.

[0032] The first end cap 3 and the first collector plate 5 are integrally stamped by a mold to form a single component with a continuous structure, eliminating the boss or peripheral bending part required for welding the traditional collector plate and end cap, thus freeing up axial space for the core 2.

[0033] It should be noted that the first end cap 3 and the first current collector 5, once integrally formed, constitute a unified conductor, which together serve as the positive terminal of the battery. Therefore, the first end cap 3 is positively charged. Furthermore, a reliable insulation is formed between the first end cap 3 and the battery casing (negative terminal), thereby ensuring battery safety and preventing short circuits.

[0034] The first collector plate 5 has a plurality of first hollow holes 51 arranged at intervals around its center. The inner wall of the first hollow hole 51 has a fixing groove 52, which is located on the upper surface of the first collector plate 5 (i.e. the surface near the first end cover 3).

[0035] Furthermore, the fixing groove 52 is an annular groove formed around the axis of the first hollow hole 51, and its groove depth is 0.2-0.5mm greater than its groove width to provide sufficient limiting depth.

[0036] Furthermore, the fixing groove 52 is an annular groove formed around the axis of the first hollow hole 51, and the groove depth of the fixing groove 52 is 0.2-0.5mm greater than the groove width. This design is more conducive to fixing the structure embedded in the fixing groove 52.

[0037] Furthermore, a step is formed between the inner wall of the fixing groove 52 and the inner wall of the first hollow hole 51; at least part of the end of the tab 21 at the first end of the core 2 abuts against the step surface.

[0038] See Figure 2 , Figures 5-7 In this embodiment, the first perforated hole 51 is a polygonal hole, such as a regular hexagonal hole, and a plurality of first perforated holes 51 are arranged at intervals around the center of the first collector plate 5.

[0039] Correspondingly, the bottom of the fixing groove 52, which is opened on the inner wall of the first hollow hole 51, will also form a regular polygonal outline composed of multiple planes connected end to end, that is, the bottom surface of the groove is a non-smooth polygonal surface.

[0040] Meanwhile, the end of the tab 21 at the first end of the core 2 is provided with multiple legs 22, which are arranged circumferentially around the end of the tab 21.

[0041] On the one hand, after the support leg 22 is inserted into the fixing groove 52, the support leg 22 of the electrode 21 is first inserted into the first hollow hole 51 and comes into contact with the end of the first hollow hole 51 (that is, the end face of the first end cover 3). The support leg 22 of the electrode 21 deforms due to the force, bends, and undergoes plastic deformation, and is inserted into the fixing groove 52, so that at least one side of the electrode 21 (that is, the support leg 22 of the electrode 21) fits against the step surface of the step, limiting the electrode 21 along the axial direction of the cylindrical shell 1, forming a dual function of "mechanical limiting + electrical connection", further optimizing the current path and improving space utilization.

[0042] On the other hand, when the support leg 22 is inserted into the fixing groove 52, the end of the electrode ear will be restricted by two adjacent planes forming an angle at the bottom of the fixing groove 52, thereby effectively preventing circumferential rotation between the electrode ear 21 and the first collector plate 5 and avoiding loosening of the connection.

[0043] See Figure 3 and Figure 5 The first collector plate 5 is also provided with multiple connecting grooves 53. The connecting grooves 53 are spaced around the center of the first collector plate 5, and the annular ring formed by them is located radially inside the annular ring formed by the first hollow hole 51.

[0044] The end of the partial tab 21 at the first end of the core 2 can be inserted into this connecting groove 53 and abut against the side or bottom of the groove to achieve electrical connection.

[0045] Furthermore, the length direction of the connecting groove 53 is arc-shaped, and multiple connecting grooves 53 are connected end to end to form a ring structure. The bottom of the connecting groove 53 also has a fixing groove 52. The support legs 22 at the ends of the electrode tabs 21 can be set on both sides of the length direction of the connecting groove 53, passing through the connecting groove 53 and embedding and fixing in the fixing groove 52. This design allows the support legs 22 to bend along the groove wall of the fixing groove 52 and undergo plastic deformation, forming a dual function of "mechanical limiting + electrical connection," further optimizing the current path and improving space utilization.

[0046] See Figure 5 To increase the current conduction area, the first current collector 5 is provided with multiple current collection channels 54 spaced around its center. The current collection channels 54 extend in a periodic, undulating waveform along the radial direction of the first current collector 5.

[0047] Furthermore, the spacing between two adjacent peaks of the waveform is 1-3 mm. This arrangement of the current collection channel 54 can expand the current conduction area, and the spacing between two adjacent peaks of the current collection channel 54 is 1-3 mm, which is beneficial to improving the current conduction efficiency.

[0048] See Figure 4To optimize electrolyte flow and shell mechanical properties, the inner wall of the cylindrical shell 1 is provided with guide ribs 11. The guide ribs 11 are helical ribs with equal pitch and a helix angle α of 30°-60°. Setting the guide ribs 11 as helical ribs with equal pitch is beneficial to guiding the electrolyte flow in a directional manner. Furthermore, limiting the helix angle α of the guide ribs 11 to 30°-60° ensures that the guide ribs 11 guide the electrolyte flow at a more reasonable angle and with higher efficiency.

[0049] Meanwhile, a flow guiding channel 12 extending axially is also formed on the inner wall of the cylindrical shell 1. The path of the flow guiding channel 12 is a periodically undulating waveform, and the spacing between adjacent peaks of the waveform is H, where the value of H gradually decreases from the first end to the second end (i.e., the period of the waveform gradually decreases from the first end to the second end), forming a variable spacing design. The height of the waveform is 0.5-2mm, which can ensure that the flow guiding channel absorbs the local stress peaks during charging and discharging most effectively.

[0050] Furthermore, the waveform height at the first end is 1.5-2mm, and the waveform height at the second end is 0.5-1mm. The waveforms are smoothly connected by 3-5 transition segments. These 3-5 transition segments are used to connect the first and second ends. The waveform height of the transition segments only needs to meet two conditions: periodic fluctuations and the spacing between adjacent peaks of the waveform gradually decreasing from the first end to the second end. The waveform height of the transition segments will not be elaborated on here.

[0051] The above structure can form an axial strength gradient on the inner wall of the cylindrical shell 1. Furthermore, the waveform height at the first end is 1.5-2 mm and the waveform height at the second end is 0.5-1 mm. This structure can more effectively absorb local stress peaks at both ends of the inner wall of the cylindrical shell in an axial direction, thus preventing the shell from fatigue cracking due to long-term alternating stress.

[0052] See Figure 8 The second collector plate 6 is arrayed with multiple contact pieces 61, which are electrically connected to the tabs 21 at the second end of the winding core 2. The second end cover 4 is provided with a honeycomb support frame 41.

[0053] Furthermore, the honeycomb support frame 41 has multiple arrayed regular hexagonal honeycomb holes. The side length of each hexagonal honeycomb hole is 1-3 mm, and the wall thickness is 0.1-0.3 mm. The upper end of the honeycomb hole wall abuts against the contact piece 61, together forming a three-dimensional current collection interface. By having the upper end of the regular hexagonal honeycomb hole wall abut against the contact piece 61 and forming a three-dimensional current collection interface, the uniformity of current distribution can be improved, avoiding local overcurrent. In traditional current collectors, the current tends to concentrate near the solder joint of the tab 21, resulting in excessively high local current density, which can cause the tab to melt or the active material to de-embed.

[0054] The edge of the second collector plate 6 has a peripheral portion 7, the height of which is 2-5mm. The second collector plate 6 is installed with the core 2 through the peripheral portion 7.

[0055] Specifically, the height of the peripheral portion 7 is 3mm, which facilitates the precise positioning and installation of the second collector plate 6 within the housing 1.

[0056] In this embodiment, during assembly, the core 2 is placed inside the cylindrical housing 1, such that the ends of a portion of the tabs 21 located at its first end are embedded in the first hollow hole 51, and the ends of the other portion of the tabs 21 are embedded in the connecting groove 53. After axial pressure is applied, the ends of a portion of the tabs 21 contact the end face of the first end cap 3 and undergo plastic deformation, resulting in a bend of up to 90°, thereby embedding and fixing them in the fixing groove 52. At this time, the stepped surface formed between the inner wall of the fixing groove 52 and the inner wall of the first hollow hole 51 abuts against the bent ends of the tabs 21, thereby achieving axial positioning of the tabs 21 and forming a stable and reliable mechanical and electrical connection.

[0057] Another part of the tab 21 contacts the side of the fixing groove 52 and undergoes plastic deformation, resulting in a bend of up to 90°, thereby embedding and fixing it in the fixing groove 52. At this time, the stepped surface formed between the inner wall of the fixing groove 52 and the inner wall of the first hollow hole 51 abuts against the bent end of the tab 21, realizing the axial positioning of the tab 21 and forming a stable and reliable mechanical and electrical connection. Then, electrode active material is filled into the cylindrical shell 1. After filling, the second current collector 6 is installed into the cylindrical shell 1 through the peripheral part 7 and detachably connected to the second end of the core 2, so that the tab 21 at the second end of the core 2 is pressed against the surface of the elastic contact piece 61. Then, the second end cap 4 is welded to the cylindrical shell 1 to complete the battery assembly.

[0058] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A cylindrical battery, characterized in that, include: Cylindrical shell; The first end cap and the second end cap are respectively disposed at both ends of the cylindrical shell; A winding core is disposed inside the cylindrical housing, and a plurality of tabs are respectively provided at the first end and the second end of the winding core; The first collector plate and the second collector plate are respectively provided corresponding to the first end cap and the second end cap. The tab at the second end of the core is connected to the second collector plate. The first end cap and the first collector plate are integrally formed. The first collector plate has a plurality of first hollow holes. The inner wall of the first hollow holes has a fixing groove. The fixing groove is located on the upper surface of the first collector plate. At least a portion of the ends of the tabs at the first end of the core are embedded and fixed in the fixing groove.

2. The cylindrical battery according to claim 1, characterized in that, A step is formed between the inner wall of the fixing groove and the inner wall of the first hollow hole; At least a portion of the end of the tab at the first end of the core abuts against the stepped surface.

3. The cylindrical battery according to claim 1, characterized in that, At least a portion of the electrode tabs at the first end of the core are provided with multiple support legs, which are arranged around the ends of the corresponding electrode tabs. The ends of the electrode tabs are embedded and fixed in the fixing grooves by the multiple support legs.

4. The cylindrical battery according to claim 2, characterized in that, The first perforation is a polygonal hole, and multiple first perforations are arranged at intervals around the center of the first collector plate.

5. The cylindrical battery according to claim 1, characterized in that, The first collector plate has multiple connecting slots, which are spaced apart around the center of the first collector plate. The annular ring formed by the multiple connecting slots is located radially inside the annular ring formed by the multiple first hollow holes. At least a portion of the end of the tab at the first end of the core is embedded in the connecting slot and abuts against the side or bottom surface of the connecting slot.

6. The cylindrical battery according to claim 1, characterized in that, The first collector plate has multiple collector channels that are spaced apart around the center of the first collector plate, and the collector channels extend radially along the first collector plate.

7. The cylindrical battery according to claim 1, characterized in that, The inner wall of the cylindrical shell is provided with guide ribs, which are equal pitch helical ribs with a helix angle α of 30°-60°.

8. The cylindrical battery according to claim 1, characterized in that, The inner wall of the cylindrical shell is provided with a flow channel extending along its axial direction. The flow channel has a periodic undulating waveform on the inner wall of the cylindrical shell. The distance between adjacent peaks of the waveform is H, where the value of H gradually decreases from the first end to the second end. The height of the waveform is 0.5-2mm.

9. The cylindrical battery according to claim 8, characterized in that, The height of the waveform at the first end is 1.5-2mm, and the height of the waveform at the second end is 0.5-1mm.

10. The cylindrical battery according to claim 9, characterized in that, The second current collector is arrayed with multiple contact pieces, which are electrically connected to the tabs at the second end of the winding core; The second end cap is provided with a honeycomb support frame, which abuts against the contact piece.

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