High energy density cylindrical secondary battery

Abstract

The application provides a high-energy-density cylindrical secondary battery, which comprises a shell and a cap assembly; the cap assembly comprises a top cover and a sealing ring. The top cover is in an in-mold injection structure with the sealing ring, and the sealing ring wraps around the edge of the top cover. During injection, the plastic fills the assembly gap caused by the stacked assembly, effectively realizes the sealed connection between the top cover and the sealing ring, and is easier to achieve a sealing effect when the cap assembly and the shell are assembled and packaged. The application solves the problem of liquid leakage risk caused by stacked assembly, reduces the process of assembling the sealing ring, improves the assembly efficiency, and improves the adhesion and connection strength of the sealing ring and the top cover. The structure is simple, compact and has high structural strength.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a high-energy-density cylindrical secondary battery. Background Technology

[0002] The existing cap assembly for cylindrical batteries consists of four stacked parts: a top cover, a sealing ring, a PTC element, and an explosion-proof sheet. When too many parts are stacked, gaps can easily form between them, resulting in poor battery sealing and a risk of leakage. The stacking of the top cover, PTC element, explosion-proof sheet, and sealing ring along the Y-axis also occupies space in the height direction, hindering improvements in battery energy density. Furthermore, the assembly process is cumbersome and inefficient, failing to meet market and customer demands. Summary of the Invention

[0003] This invention provides a high-energy-density cylindrical secondary battery that is easy to assemble, has high structural strength, and improves energy density.

[0004] This invention provides a high-energy-density cylindrical secondary battery, including a shell and a cap assembly; the shell is cylindrical, with one end closed and the other end open; a roller groove structure is provided on the side wall of the shell, and the roller groove structure is an annular concave shape arranged around the outer periphery of the shell;

[0005] The cap assembly is disposed at the opening end of the outer shell, and includes a top cover and a sealing ring. The top cover has perforations at its four edges. The sealing ring is in-mold injection molded around the four edges of the top cover and includes a first sealing wall, a second sealing wall, a third sealing wall, and a connecting post. The second sealing wall is disposed around the periphery of the top cover and is connected between the first sealing wall and the third sealing wall. The four edges of the top cover are sandwiched between the first sealing wall and the third sealing wall. The connecting post passes through the perforations and its two ends are respectively connected to the first sealing wall and the third sealing wall.

[0006] The first sealing wall abuts against the roller groove structure, and the open end of the outer shell is bent inward to form a rolled edge, which abuts against the third sealing wall.

[0007] The perforations are multiple and arranged around the edge of the top cover.

[0008] Wherein, the perforation is a through hole and is spaced apart from the circumferential surface of the top cover; and / or,

[0009] The perforation is a notch located on the circumference of the top cover, and the connecting post is connected to the second sealing wall.

[0010] Wherein, the outer periphery of the connection between the first sealing wall and the second sealing wall has a convex arc-shaped structure in the axial section, and the inner wall of the connection between the roller groove structure and the opening end of the outer shell has a concave arc-shaped structure in the axial section. The convex arc-shaped structure and the concave arc-shaped structure complement each other.

[0011] Both the convex arc-shaped structure and the concave arc-shaped structure are provided with hot melt adhesive, and the two are bonded together.

[0012] The rolled edge is directly attached to the third sealing wall.

[0013] The inner wall diameter of the roller groove structure and the inner side diameter of the rolled edge are both smaller than the circumferential diameter of the top cover.

[0014] The top cover has a groove on the side facing away from the outer shell. The groove is formed by stamping the top cover and is an annular shape extending along the edge of the top cover. The third sealing wall extends into the groove, and the inner edge of the rolled edge is bent toward the groove.

[0015] The top cover includes a cover plate and a boss, the boss being connected to the center of the cover plate and protruding toward the side opposite to the outer shell;

[0016] The cover plate is provided with a pressure relief hole, which is located between the boss and the sealing ring; the axial cross-section of the pressure relief hole is T-shaped, and an explosion-proof plate is welded to the larger diameter end; or,

[0017] An explosion-proof line is provided on the side of the cover plate facing the inside of the outer shell. The explosion-proof line is an annular groove structure surrounding the boss. In the horizontal projection, the explosion-proof line is located between the boss and the sealing ring.

[0018] The cylindrical secondary battery also includes an electrode core, which is disposed inside the outer casing. The electrode core is either wound or stacked. Both ends of the electrode core are provided with tabs, and the two tabs are welded to the top cover and the outer casing respectively for electrical connection.

[0019] This invention provides a high-energy-density cylindrical secondary battery. The top cover is injection molded to form an integrated cap assembly with a sealing ring. The sealing ring wraps around the edge of the top cover. During injection molding, the plastic fills the assembly gaps caused by stacked assembly, effectively achieving a sealed connection between the top cover and the sealing ring. This makes it easier to achieve a sealing effect when assembling the cap assembly with the outer shell, solving the problem of leakage risk associated with stacked assembly, reducing the number of sealing ring assembly steps, and improving assembly efficiency. During the injection molding of the sealing ring on the top cover, the plastic can fill the perforations to form connecting pillars. These pillars connect the first and third sealing walls, improving the adhesion and connection strength between the sealing ring and the top cover, resulting in higher structural strength. This simplifies the structure of the cap assembly, making its overall structure more compact, thereby increasing the battery's energy density. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments are briefly introduced below. The drawings described below are only the corresponding drawings of some embodiments of the present invention.

[0021] Figure 1 This is a longitudinal sectional view of the high-energy-density cylindrical secondary battery provided in the first embodiment of the present invention;

[0022] Figure 2 yes Figure 1 Enlarged view of the top of a medium-sized cylindrical secondary battery;

[0023] Figure 3 yes Figure 1 Top perspective sectional view of a medium-sized cylindrical secondary battery;

[0024] Figure 4 yes Figure 1 A perspective sectional view of the cap assembly of a medium-sized cylindrical secondary battery;

[0025] Figure 5 yes Figure 4 Exploded view of the middle cap assembly;

[0026] Figure 6 This is a schematic diagram of the cap assembly of a high-energy-density cylindrical secondary battery provided in the second embodiment of the present invention;

[0027] Figure 7 This is a schematic diagram of the cap assembly of a high-energy-density cylindrical secondary battery provided in the third embodiment of the present invention;

[0028] Figure 8 This is a schematic diagram of the structure of the cap assembly and the outer casing of the high-energy-density cylindrical secondary battery provided in the fourth embodiment of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] Please see Figures 1 to 3 A preferred embodiment of the present invention provides a high-energy-density cylindrical secondary battery, comprising a casing 1 and a cap assembly 2; the casing 1 is cylindrical, closed at one end and open at the other end; the cap assembly 2 is disposed at the open end of the casing 1 to form a sealed cavity between the cap assembly 2 and the casing 1, and an electrode core 3 and an electrolyte (not shown in the figure) are disposed within the sealed cavity. The cylindrical secondary battery referred to in this invention is a battery whose axial dimension is more than twice its diameter.

[0032] like Figure 1 , Figure 2 and Figure 3 As shown, a roller groove structure 10 is provided on the side wall of the outer shell 1. The roller groove structure 10 is an annular concave shape arranged around the outer periphery of the outer shell 1, so that the cap assembly can be supported and positioned by the roller groove structure 10.

[0033] Combination Figure 4 and Figure 5 As shown, the cap assembly 2 includes a top cover 21 and a sealing ring 22. The top cover 21 has perforations 210 at its four edges. The sealing ring 22 is molded and wrapped around the four edges of the top cover 21. It includes a first sealing wall 221, a second sealing wall 222, a third sealing wall 223, and a connecting post 224. The second sealing wall 222 surrounds the periphery of the top cover 21 and is connected between the first sealing wall 221 and the third sealing wall 223. The four edges of the top cover 21 are sandwiched between the first sealing wall 221 and the third sealing wall 223. The connecting post 224 passes through the perforations 210 and its two ends are connected to the first sealing wall 221 and the third sealing wall 223, respectively.

[0034] The top cover 21 can be inserted into the mold of the sealing ring 22 for in-mold injection molding. After injection molding, a cap assembly 2 with a composite structure of top cover 21 and sealing ring 22 is obtained. The sealing ring 22 wraps around the edge of the top cover 21. During injection molding, the plastic fills the assembly gaps caused by the stacked assembly and effectively achieves a sealed connection between the top cover 21 and the sealing ring 22. When the cap assembly 2 is assembled and packaged with the outer shell 1, it is easier to achieve a sealing effect, solving the problem of leakage risk in stacked assembly, reducing the assembly process of the sealing ring 22, and improving assembly efficiency. When the sealing ring 22 is in-mold injected into the top cover 21, the plastic can fill the perforation 210 to form a connecting post 224. The connecting post 224 connects the first sealing wall 221 and the third sealing wall 223 together, improving the adhesion and connection strength between the sealing ring 22 and the top cover 21, resulting in higher structural strength. The structure of the cap assembly is simplified, making its overall structure more compact, thereby improving the battery energy density.

[0035] like Figure 2 and Figure 3 As shown, the first sealing wall 221 abuts against the roller groove structure 10, and the open end of the outer shell 1 is bent inward to form a rolled edge 11, which abuts against the third sealing wall 223. During assembly, the cap assembly 2 is placed into the open end of the outer shell 1, and the first sealing wall 221 of the sealing ring 22 abuts against the roller groove structure 10, so that the cap assembly 2 is supported on the roller groove. Then, the open end of the outer shell 1 is bent inward to form the rolled edge 11, thereby fixing the cap assembly 2 inside the outer shell 1. At the same time, the sealing ring 22 is used to seal the cap assembly 2 and the outer shell 1.

[0036] The top cover 21 is preferably made of aluminum alloy, or other hardware materials such as stainless steel. The top cover 21 includes a cover plate 211 and a boss 212. The boss 212 is connected to the center of the cover plate 211 and protrudes towards the side opposite to the outer casing 1. The boss 212 facilitates electrical connection with electrical equipment. A through hole 210 is provided on the cover plate 211.

[0037] In this embodiment, the perforation 210 is a through hole and is spaced apart from the circumference of the top cover 21, so that there is a certain distance between the perforation 210 and the edge of the top cover 21. After the perforation 210 is filled with glue, a connecting post 224 is formed. Because there is a certain distance between the perforation 210 and the edge of the top cover 21, the connecting post 224 is closer to the inner side of the first sealing wall 221 and the third sealing wall 223, which allows the inner side of the first sealing wall 221 and the third sealing wall 223 to be reliably connected by the connecting post 224, avoiding the separation and lifting of the inner side of the first sealing wall 221 or the third sealing wall 223 relative to the top cover 21, effectively ensuring that the sealing ring 22 and the top cover 21 are firmly and reliably connected. The shape of the perforation 210 can be circular, square, elliptical, star-shaped, or other irregular shapes. In this embodiment, a circular shape is preferred.

[0038] In other embodiments, the perforation 210 can be a notch on the circumferential surface of the top cover 21. The connecting post 224 is connected to the second sealing wall 222. The connecting post 224 is connected to all three sealing walls of the sealing ring 22, which can ensure that the plastic can effectively fill the perforation 210 during injection and ensure the tightness of the connection between the sealing ring 22 and the top cover 21.

[0039] Multiple perforations 210 are arranged around the edge of the top cover 21. Using multiple perforations 210 effectively ensures that the edge of the top cover 21 can reliably connect with the sealing ring 22 at all locations. In this embodiment, there are five perforations 210.

[0040] Among the multiple perforations 210, some perforations 210 may be the aforementioned through-hole structure, and some perforations 210 may be the aforementioned notch structure. That is, the perforations 210 are through holes and are spaced apart from the circumferential surface of the top cover 21; and / or, the perforations 210 are notches provided on the circumferential surface of the top cover 21, and the connecting post 224 is connected to the third sealing wall 223.

[0041] The sealing ring 22 is preferably made of PP, PI, PS, or other plastic materials, and its melting point is preferably between 100℃ and 500℃. The top cover 21 is placed into the mold of the sealing ring 22 for in-mold injection molding. After injection, the plastic material flows into the perforation 210 of the top cover 21 to form the connecting post 224. The first sealing wall 221, the second sealing wall 222, and the third sealing wall 223 of the sealing ring 22 are connected to form a "U" shape, wrapping around the edge of the top cover 21. The sealing ring 22 prevents direct contact between the top cover 21 and the outer casing 1, thus providing polarity insulation and sealing for the battery.

[0042] like Figure 2 , Figure 3 As shown, the outer periphery of the connection between the first sealing wall 221 and the second sealing wall 222 has a convex arc-shaped structure 220 in the axial section, and the inner wall of the connection between the roller groove structure 10 and the opening end of the outer shell 1 has a concave arc-shaped structure 110 in the axial section. The convex arc-shaped structure 220 and the concave arc-shaped structure 110 complement each other in shape. By utilizing the complementary shapes of the convex arc-shaped structure 220 and the concave arc-shaped structure 110, the assembly connection between the cap assembly 2 and the outer shell 1 can be facilitated. Furthermore, hot melt adhesive is provided on both the convex arc-shaped structure 220 and the concave arc-shaped structure 110, and the two are bonded together. Before assembling the cap assembly 2 and the outer shell 1, a layer of hot melt adhesive can be applied to the surfaces of both the convex arc-shaped structure 220 and the concave arc-shaped structure 110. After the cap assembly 2 is installed into the outer shell 1, the joint between the convex arc-shaped structure 220 and the concave arc-shaped structure 110 is hot-melted, so that the two are tightly bonded by the hot melt adhesive, which can ensure the tightness and sealing of the connection. Meanwhile, the cap assembly 2 can be fixed on the roller groove, so that when the open end of the outer shell 1 is rolled 11, the cap assembly 2 and the outer shell 1 will not be loose, ensuring the normal operation of the rolling 11.

[0043] The rolled edge 11 is directly attached to the third sealing wall 223, that is, no other parts are set between them, and the rolled edge 11 is directly used to press the second sealing wall 222 to facilitate processing and preparation.

[0044] like Figure 2 As shown, the inner wall diameter of the roller groove structure 10 and the inner side diameter of the rolled edge 11 are both smaller than the circumferential diameter of the top cover 21. The edge of the top cover 21 can clamp the roller groove structure 10 and the rolled edge 11 to ensure the reliability of the connection between the cap assembly 2 and the outer shell 1.

[0045] like Figure 4 , Figure 5 As shown, a pressure relief hole 213 is provided on the cover plate 211, located between the boss 212 and the sealing ring 22. The axial section of the pressure relief hole 213 is T-shaped, and an explosion-proof plate 214 is welded to the larger diameter end. The larger diameter end of the pressure relief hole 213 is closer to the outer side of the outer casing 1 than the other end. When the internal pressure of the battery exceeds a predetermined level, the pressure presses against the explosion-proof plate 214, accelerating its disengagement and thus enabling rapid gas discharge from the battery. The stepped structure formed by the T-shaped pressure relief hole 213 facilitates the connection between the explosion-proof plate 214 and the pressure relief hole 213. Simultaneously, the pressure relief hole 213 can also serve as an injection hole. After the cap assembly 2 is welded and assembled with the outer casing 1, electrolyte can be injected into the outer casing 1 through the pressure relief hole 213. After injection, the explosion-proof plate 214 is welded to the pressure relief hole 213, thereby sealing the pressure relief hole 213.

[0046] The electrode core 3 is disposed inside the outer casing 1. The electrode core 3 is either wound or stacked. Both ends of the electrode core 3 are provided with electrode tabs 31, which are welded to the top cover 21 and the outer casing 1 respectively for electrical connection. The welding method can be spot welding, resistance welding, double needle welding, laser welding and other welding processes.

[0047] Insulating gaskets 32 are provided at both ends of the electrode core 3. The insulating gaskets 32 can be made of plastic materials such as PP, PI, and PS. The insulating gaskets 32 have through holes (not shown in the figure). The electrode tabs 31 are provided with through holes. The insulating gaskets 32 can prevent short circuits caused by electrical connection between the electrode core 3 and other parts of the battery.

[0048] The high-energy-density cylindrical secondary battery provided in this embodiment is assembled as follows.

[0049] The electrode core 3 is installed in the inner cavity of the outer shell 1. The process roller groove on the side wall of the outer shell 1 forms a roller groove structure 10. The electrode core 3 is limited between the closed section of the outer shell 1 and the roller groove structure 10.

[0050] The cap assembly 2 is inserted into the roller groove structure 10 at the top of the inner cavity of the housing 1, and then the electrolyte is dripped in.

[0051] Finally, the battery is encapsulated, and the open end of the casing 1 is rolled to form a rolled edge 11, thereby obtaining a rolled edge 11 fastening structure with reliable sealing and insulation, and an explosion-proof sheet 214 is welded on.

[0052] The pressure relief hole 213 of the top cover 21 can also be used as an injection hole. That is, the opening of the outer shell 1 can be rolled up to form a rolled edge 11, and then the electrolyte can be dripped in through the pressure relief hole 213.

[0053] The high-energy-density cylindrical secondary battery provided in the second embodiment of the present invention differs from that in the first embodiment in the structure of the top cover 21. Other structures can be the same as those in the aforementioned embodiments. The following mainly describes the differences in detail, and the similarities will not be repeated here.

[0054] like Figure 6 As shown, in this embodiment, the top cover 21 includes a cover plate 211 and a boss 212. The boss 212 is a hollow shell structure with one end open and the other end closed. The cover plate 211 is annular around the open end of the boss 212. The top cover 21 can be stamped from a plate-shaped metal material, which facilitates processing and manufacturing, saves materials, and reduces costs.

[0055] The high-energy-density cylindrical secondary battery provided in the third embodiment of the present invention differs from the first embodiment mainly in the structure of the top cover 21. Other structures can be the same as those in the aforementioned embodiments. The following mainly describes the differences in detail, and the similarities will not be repeated here.

[0056] like Figure 7 As shown, in this embodiment, the cover plate 211 does not have a pressure relief hole 213. Instead, an explosion-proof line 219 is provided on the side of the cover plate 211 facing inwards from the outer casing 1. The explosion-proof line 219 is an annular groove structure surrounding the boss 212. Projected onto the horizontal plane, the explosion-proof line 219 is located between the boss 212 and the sealing ring 22. The longitudinal cross-section of the explosion-proof line 219 is V-shaped, or it could be U-shaped or other shapes. The groove structure of the explosion-proof line 219 allows for thinning of the cover plate 211, making it easier to break, thereby achieving the effect of pressure relief and explosion prevention. In other embodiments, the explosion-proof line 219 can also be provided on the bottom wall of the outer casing 1, or the structure of the pressure relief hole 213 and the explosion-proof plate 214 can be provided on the bottom wall of the outer casing 1.

[0057] The high-energy-density cylindrical secondary battery provided in the fourth embodiment of the present invention differs from the previous embodiments mainly in the structure of the cap assembly 2 and the rolled edge 11. Other structures can be the same as those in the previous embodiments. The following mainly describes the differences in detail, and the similarities will not be repeated here.

[0058] like Figure 8As shown, a groove 218 is provided on the side of the top cover 21 facing away from the outer shell 1. The groove 218 is formed by stamping the top cover 21 and is an annular shape extending along the edge of the top cover 21. The annular groove 218 formed by stamping can improve the overall strength of the top cover 21, making it less prone to deformation, thereby keeping the four edges of the top cover 21 on the same plane for injection molding of the sealing ring 22.

[0059] The third sealing wall 223 extends into the groove 218, and the inner edge of the rolled edge 11 bends toward the groove 218, so that the rolled edge 11 can apply a downward force to the cap assembly 2, thereby making the third sealing wall 223 and the rolled edge 11 tightly connected to ensure sealing performance.

[0060] The perforation 210 on the top cover 21 is set in the groove 218. During the process of forming the sealing ring 22 by injection molding in the mold, the plastic can flow into the groove 218 better, thereby filling the perforation 210 to form the connecting post 224, which is conducive to the processing and molding of the connecting post 224.

[0061] In summary, although the present invention has been disclosed above with reference to preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A high-energy-density cylindrical secondary battery, characterized in that, It includes an outer shell and a cap assembly; the outer shell is cylindrical, closed at one end and open at the other end; a roller groove structure is provided on the side wall of the outer shell, and the roller groove structure is an annular concave shape arranged around the outer periphery of the outer shell; The cap assembly is disposed at the opening end of the outer shell, and includes a top cover and a sealing ring. The top cover has perforations at its four edges. The sealing ring is in-mold injection molded around the four edges of the top cover and includes a first sealing wall, a second sealing wall, a third sealing wall, and a connecting post. The second sealing wall is disposed around the periphery of the top cover and is connected between the first sealing wall and the third sealing wall. The four edges of the top cover are sandwiched between the first sealing wall and the third sealing wall. The connecting post passes through the perforations and its two ends are respectively connected to the first sealing wall and the third sealing wall. The first sealing wall abuts against the roller groove structure, and the open end of the outer shell is bent inward to form a rolled edge, which abuts against the third sealing wall; A groove is provided on the side of the top cover facing away from the outer shell. The groove is formed by stamping the top cover and is an annular shape extending along the edge of the top cover. The third sealing wall extends into the groove, and the inner edge of the rolled edge is bent toward the groove. A perforation on the top cover is provided in the groove.

2. The high-energy-density cylindrical secondary battery according to claim 1, characterized in that, The perforations are multiple and are arranged around the edge of the top cover.

3. The high-energy-density cylindrical secondary battery according to claim 2, characterized in that, The perforation is a through hole and is spaced apart from the circumferential surface of the top cover; and / or, The perforation is a notch located on the circumference of the top cover, and the connecting post is connected to the second sealing wall.

4. The high-energy-density cylindrical secondary battery according to claim 1, characterized in that, The outer periphery of the connection between the first sealing wall and the second sealing wall has a convex arc-shaped structure in the axial section, and the inner wall of the connection between the roller groove structure and the opening end of the outer shell has a concave arc-shaped structure in the axial section. The convex arc-shaped structure and the concave arc-shaped structure complement each other.

5. The high-energy-density cylindrical secondary battery according to claim 4, characterized in that, Both the convex arc-shaped structure and the concave arc-shaped structure are provided with hot melt adhesive, and the two are bonded together.

6. The high-energy-density cylindrical secondary battery according to claim 5, characterized in that, The rolled edge is directly attached to the third sealing wall.

7. The high-energy-density cylindrical secondary battery according to claim 5, characterized in that, The inner wall diameter of the roller groove structure and the inner side diameter of the rolled edge are both smaller than the circumferential diameter of the top cover.

8. The high-energy-density cylindrical secondary battery according to any one of claims 1-7, characterized in that, The top cover includes a cover plate and a boss, the boss being connected to the center of the cover plate and protruding toward the side opposite to the outer shell; The cover plate is provided with a pressure relief hole, which is located between the boss and the sealing ring; the axial cross-section of the pressure relief hole is T-shaped, and an explosion-proof plate is welded to the larger diameter end; or, An explosion-proof line is provided on the side of the cover plate facing the inside of the outer shell. The explosion-proof line is an annular groove structure surrounding the boss. In the horizontal projection, the explosion-proof line is located between the boss and the sealing ring.

9. The high-energy-density cylindrical secondary battery according to any one of claims 1-7, characterized in that, The cylindrical secondary battery also includes an electrode core, which is disposed inside the outer casing. The electrode core is either wound or stacked. Both ends of the electrode core are provided with tabs, and the two tabs are welded to the top cover and the outer casing respectively for electrical connection.

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