A top cover assembly of an electric cell and a forming method thereof

Abstract

The application relates to the technical field of secondary batteries, and provides a battery core top cover assembly and a forming method thereof, the battery core top cover assembly comprising a metal cover plate and a metal pole, the metal cover plate being provided with a mounting hole for the metal pole to pass through, the hole wall of the mounting hole and / or the outer peripheral surface of the metal pole being provided with a nano micropore layer; the battery core top cover assembly further comprises an insulating sealing body, the insulating sealing body being injection molded by engineering plastic in the gap between the metal pole and the mounting hole and being integrated with the nano micropore layer. The battery core top cover assembly and the forming method thereof have the advantages that the nano micropore layer and the insulating sealing body are anchored and combined, insulation and sealing between the pole and the cover plate are realized, the structure is simplified, the combination is firm, the sealing is reliable, the performance stability under high and low temperature cycles and corrosion environment can be improved, the electrical safety can be enhanced, and the service life can be prolonged.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, specifically to a cell top cover assembly and its molding method. Background Technology

[0002] In power battery manufacturing, the cell top cover assembly is a core component for battery safety and sealing. The cell top cover typically includes a metal cover plate, positive and negative terminals (posts), seals, insulation components, and functional components such as explosion-proof valves and electrolyte filling holes. The posts pass through mounting holes in the metal cover plate to connect to the bare battery cell inside. Electrical insulation and sealing must be achieved simultaneously between the posts and the metal cover plate to prevent electrolyte leakage and the intrusion of external moisture / gas.

[0003] Currently, the electrode sealing solution used in related technologies involves placing an independent sealing ring (such as fluororubber or EPDM) between the electrode and the metal cover plate, achieving a seal through mechanical compression. However, this solution has at least the following shortcomings: First, there's the issue of sealing ring aging and stress relaxation. Sealing rings are constantly under pressure, and creep and stress relaxation inevitably occur during the battery's lifespan, leading to a gradual decrease in compression and a decline in sealing performance. Especially in high-temperature environments (above 60°C), the accelerated aging of the rubber material will significantly shorten the seal's lifespan.

[0004] Secondly, the project involves numerous components and complex assembly. The proposed solution requires multiple discrete components such as independent sealing rings, upper insulating parts, lower insulating parts, and pressure plates. This results in numerous assembly steps, significant challenges in automation, and stringent requirements for tolerance control between components. Furthermore, the mounting holes between the pole and the cover plate are mostly straight holes, which lack sufficient axial positioning capability for the pole, further increasing the assembly difficulty.

[0005] Third, the sealing interfaces are numerous and the potential leakage paths are long. Since the sealing ring only forms a contact seal under a certain amount of compression, the microscopic unevenness of the metal-rubber interface may lead to micro-leakage channels. The thermal expansion and contraction effect caused by temperature changes may further aggravate the micro-leakage at the interface. At the same time, in related schemes, the creepage distance between the exposed section of the upper part of the pole and the metal cover plate is often short, which can easily cause high-voltage creepage risk and affect electrical safety.

[0006] Fourth, limitations in resistance to electrolyte corrosion. Although fluororubber has good resistance to carbonate electrolytes, it still swells after long-term immersion, affecting the dimensional stability and sealing reliability of the sealing ring. Furthermore, different electrode materials have different compatibility requirements for sealing materials.

[0007] Fifth, reliability risks under high and low temperature cycling. The battery cell may experience temperature changes from -40℃ to 85℃. Due to the large difference in the coefficient of thermal expansion between the sealing ring and the metal cover / terminal, repeated thermal cycling may lead to fretting wear at the interface and seal failure.

[0008] Therefore, there is an urgent need for a solution that can overcome the above-mentioned defects in order to achieve efficient sealing and insulation between the metal pole and the metal cover. Summary of the Invention

[0009] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a battery cell top cover assembly and its molding method, which solves the technical problems of easy aging and loosening of the sealing ring, large number of parts, complex assembly, and easy sealing failure in the prior art.

[0010] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a battery cell top cover assembly, including a metal cover plate and a metal electrode post. The metal cover plate is provided with a mounting hole for the metal electrode post to pass through. The wall of the mounting hole and / or the outer peripheral surface of the metal electrode post are provided with a nanoporous layer. The battery cell top cover assembly further includes an insulating sealing body, which is injection molded from engineering plastic in the gap between the metal electrode post and the mounting hole, and is integrated with the nanoporous layer.

[0011] In some embodiments, the nanoporous layer includes a plurality of uniformly distributed nanoporous pores; the engineering plastic is configured to be in a molten state during injection molding and to penetrate into the plurality of nanoporous pores, and to be anchored to the metal surface on which the nanoporous layer is located.

[0012] In some embodiments, the diameter of the nanopores is 20-50 nm and the depth is 30-100 nm; the shear strength of the interface between the insulating seal and the nanopore layer is greater than or equal to 35 MPa.

[0013] In some embodiments, the diameter of the mounting hole is larger than the outer diameter of the metal pole, so that an annular injection gap is formed between the hole wall of the mounting hole and the metal pole; the insulating sealant fills the annular injection gap and completely seals the annular injection gap.

[0014] In some embodiments, one end of the insulating seal extends axially along the mounting hole to the outside of the mounting hole and protrudes from the surface of the corresponding side of the metal cover to form a sealing lip.

[0015] In some embodiments, the mounting hole is a stepped hole, which includes at least a first hole segment and a second hole segment distributed along its axial direction; an insulating ring is provided in the first hole segment, the end of the insulating ring away from the second hole segment extends to the outside of the mounting hole, and is configured to provide insulation between the exposed section of the metal pole and the adjacent surface of the metal cover plate; the insulating seal fills the second hole segment, and the sealing lip protrudes from the side of the metal cover plate opposite to the insulating ring.

[0016] In some embodiments, the cell top cover assembly further includes a plastic part disposed on one side of the metal cover plate. The side of the plastic part near the metal cover plate is provided with a positioning hole for passing through the metal electrode post. An overflow groove surrounding the metal electrode post is also provided on the outside of the positioning hole.

[0017] In some embodiments, the metal terminal includes a positive terminal and a negative terminal, the positive terminal being an aluminum terminal and the negative terminal including an upper aluminum segment and a lower copper segment connected to each other.

[0018] Secondly, the present invention also provides a method for molding a battery cell top cover assembly, for molding a battery cell top cover assembly as described in the first aspect, comprising the following steps: S1, performing nano-sizing treatment on the mounting hole wall of the metal cover plate and / or the outer peripheral surface of the metal electrode to form a nanoporous layer; S2, placing the metal electrode in the mounting hole to form a gap between the metal electrode and the mounting hole; S3, injecting molten engineering plastic into the gap to allow the engineering plastic to penetrate the nanoporous layer and fill the gap; S4, cooling and solidifying to form an insulating seal integrally bonded to the nanoporous layer.

[0019] In some embodiments, in step S4, the engineering plastic is any one of PPS-GF40, PBT-GF30, PA66-GF35, and PEEK; wherein the injection molding temperature corresponding to PPS-GF40 engineering plastic is 290-330℃, the injection molding temperature corresponding to PBT-GF30 engineering plastic is 250-270℃, the injection molding temperature corresponding to PA66-GF35 engineering plastic is 260-290℃, and the injection molding temperature corresponding to PEEK engineering plastic is 360-400℃.

[0020] Compared with the prior art, the present invention provides a battery cell top cover assembly and its molding method, which, by setting a nanoporous layer on the wall of the mounting hole and / or the outer peripheral surface of the electrode post, and injection molding engineering plastic into the gap between the electrode post and the mounting hole, allows the engineering plastic to penetrate into the nanoporous layer to form an integrally bonded insulating seal, eliminating the metal-rubber contact interface, avoiding sealing failure caused by aging of the sealing ring, stress relaxation and differences in thermal expansion coefficients, and improving sealing reliability; at the same time, by injection molding, multiple separate components such as independent sealing rings and insulating gaskets are eliminated, reducing the number of parts and assembly processes, which helps to improve production efficiency and reduce manufacturing costs. Attached Figure Description

[0021] Figure 1 This is an isometric view of the battery cell top cover assembly in one embodiment of the present invention; Figure 2 This is an exploded view of the battery cell top cover assembly in one embodiment of the present invention; Figure 3 This is a cross-sectional view of the battery cell top cover assembly in one embodiment of the present invention; Figure 4 yes Figure 3 A magnified view of part A in the middle; Figure 5 This is an isometric view of a plastic part in one embodiment of the present invention; Figure 6 This is a schematic diagram of the positive electrode post in one embodiment of the present invention; Figure 7 This is a schematic diagram of the negative electrode post in one embodiment of the present invention; Figure 8 This is a schematic flowchart of a method for forming a battery cell top cover assembly according to one embodiment of the present invention.

[0022] Explanation of reference numerals in the attached drawings: 10. Metal cover plate; 11. Mounting hole; 111. Positive electrode mounting hole; 111a. First hole section; 111b. Second hole section; 111c. Positioning step; 112. Negative electrode mounting hole; 12. Explosion-proof valve hole; 13. Explosion-proof valve protective plate; 14. Explosion-proof valve plate; 15. Injection hole; 20. Metal electrode; 21. Positive electrode; 211. Top section of positive electrode; 212. Shaft section of positive electrode; 213. Annular groove of positive electrode; 22. Negative electrode; 2 21. Upper aluminum section; 222. Lower copper section; 223. Top section of negative electrode post; 224. Annular groove of negative electrode post; 30. Plastic part; 31. Positive electrode support boss; 32. Negative electrode support boss; 33. Positioning hole; 331. Positive electrode post positioning hole; 332. Negative electrode post positioning hole; 34. Adapter plate support ridge; 35. Explosion-proof valve protective grille; 36. Matching injection hole; 37. Reinforcing rib; 38. Overflow groove; 40. Insulating sealing body; 41. Sealing lip; 50. Insulating ring. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] Please see Figure 1-2 This invention provides a battery cell top cover assembly, which includes a metal cover plate 10 and a metal terminal 20. The metal cover plate 10 is provided with a mounting hole 11 for the metal terminal 20 to pass through. A gap is formed between the hole wall of the mounting hole 11 and the metal terminal 20. The gap is filled with an insulating sealant 40. The inner side of the insulating sealant 40 is combined with the metal terminal 20. It can not only seal the gap between the hole wall of the mounting hole 11 and the metal terminal 20, but also provide insulation between the metal cover plate 10 and the metal terminal 20.

[0025] In some embodiments, such as Figure 2 As shown, the metal cover plate 10 can be the top cover substrate of the battery cell, which can be made of conductive metal materials such as aluminum alloy, and can be set as a rectangular, circular or pill-shaped plate. At the same time, the metal terminal 20 includes a positive terminal 21 and a negative terminal 22. The metal cover plate 10 is provided with two mounting holes 11 corresponding to the positive terminal 21 and the negative terminal 22 respectively (which can be referred to as positive terminal mounting hole 111 and negative terminal mounting hole 112 respectively). When the metal cover plate 10 is a rectangular plate, the two mounting holes 11 can be symmetrically arranged on both sides of the length direction of the metal cover plate 10, and the positive terminal 21 and the negative terminal 22 can be inserted into the positive terminal mounting hole 111 and the negative terminal mounting hole 112 respectively, forming a conductive path for electrical connection between the battery cell and the external circuit. In addition, an explosion-proof valve hole 12 is provided in the middle of the metal cover plate 10. An explosion-proof valve plate 14 and an explosion-proof valve protection plate 13 can be installed at the explosion-proof valve hole 12. An injection hole 15 is also provided on the side of the explosion-proof valve hole 12 near the positive electrode mounting hole 111.

[0026] Please see Figure 3-4 Taking any one of the mounting holes 11 as an example, the diameter of the mounting hole 11 can be larger than the outer diameter of the corresponding metal pole 20, so that an annular injection gap is formed between the hole wall of the mounting hole 11 and the metal pole 20; the aforementioned insulating sealant 40 can fill the annular injection gap and completely seal the annular injection gap. The radial width of the annular injection gap can be controlled within the range of 1.5 mm to 3.0 mm.

[0027] Furthermore, the wall of the mounting hole 11 and / or the outer peripheral surface of the metal electrode 20 are provided with a nanoporous layer. The nanoporous layer can be a microscopically rough structure with numerous nanoscale pores formed on the metal surface through nanoscale processes such as chemical etching, electrochemical anodizing, or laser surface treatment. In this embodiment, the nanoporous layer can be provided only on the outer peripheral surface of the metal electrode 20 (such as the positive electrode 21 or the negative electrode 22); it can also be provided only on the wall of the mounting hole 11; or it can be provided on both the outer peripheral surface of the metal electrode 20 and the wall of the mounting hole 11. The specific configuration can be flexibly set as needed and is not specifically limited.

[0028] Furthermore, the insulating seal 40 can be injection molded from engineering plastic into the gap between the metal electrode 20 and the mounting hole 11 (i.e., the aforementioned annular injection gap), and integrated with the nanoporous layer. The insulating seal 40 can be made of high-temperature resistant and electrolyte-resistant engineering plastics such as PPS (Polyphenylene Sulfide), PBT (Polybutylene Terephthalate), PA (Polyamide), and PEEK (Polyether Ether Ketone). During the molding process, molten engineering plastic is injected under high pressure into the annular injection gap between the metal electrode 20 and the mounting hole 11.

[0029] It should be noted that in this embodiment, the gap between the wall of the mounting hole 11 and the metal pole 20 is a full-circumferential annular gap. However, in some other embodiments, a full-circumferential annular gap may not be provided between the outer wall of the pole and the hole wall. For example, multiple longitudinal grooves or notches extending along the axial direction can be opened on the outer wall of the metal pole 20, and the insulating seal 40 can fill these grooves or notches to achieve anchoring and sealing. In this case, a transition fit or a small clearance fit can be used between the mounting hole 11 and the metal pole 20, which helps to reduce the amount of sealing material used, and the direct contact surface between the metal pole 20 and the wall of the mounting hole 11 can retain some mechanical support function.

[0030] Alternatively, an annular groove can be pre-set on the outer wall of the metal pole 20. The size of the annular groove can be flexibly set as needed; for example, the depth of the annular groove can be 0.5-2mm, and the width can be 2-5mm. In this case, the insulating seal 40 only fills the annular groove, and the mounting hole 11 and the ungrooved section of the metal pole 20 can be radially positioned by a small gap fit. This scheme facilitates pole centering, and the annular groove itself can constitute a first-level mechanical interlock. Furthermore, the gap between the metal pole 20 and the mounting hole 11 can also be a tapered gradual gap, with the gap width gradually changing from the upper surface to the lower surface of the metal cover plate 10 (it can be narrower at the top and wider at the bottom, or vice versa). After injection molding, the insulating seal 40 can form a tapered seal, which is beneficial for the unidirectional flow and venting of the melt during injection molding. At the same time, the tapered structure can also form a wedge-shaped self-locking effect in the axial direction, resulting in stronger pull-out resistance. In addition, the above gap can also be set as a spiral gap. For example, a spiral groove (similar to a thread) can be machined on the outer wall of the metal pole 20 so that the above gap extends spirally along the circumference. After the insulating seal 40 fills the spiral groove, a spiral joint interface can be formed, which changes the potential leakage path from a straight direction (axial direction) to a spiral path. The leakage path length can be extended several times, and the labyrinth effect significantly enhances the sealing reliability.

[0031] In some embodiments, taking the nanoporous layer on the metal electrode 20 as an example, the nanoporous layer at least covers a portion of the outer surface of the corresponding metal electrode 20. Simultaneously, the nanoporous layer comprises a plurality of uniformly distributed nanopores; during injection molding, the engineering plastic is in a molten state and can penetrate into each nanopore, anchoring and bonding with the metal surface where the nanoporous layer is located. During injection molding, when the high-temperature, high-pressure engineering plastic melt comes into contact with the nano-treated metal surface, the melt is forced into the interior of these nano-sized micropores under the drive of injection pressure. As the mold cools, the plastic penetrating into the micropores solidifies and crystallizes in situ, forming a dense physical anchoring array, enabling the insulating seal 40 to achieve a material-level integrated bond with the corresponding metal surface at the interface. It should be understood that the bonding mechanism between the insulating seal 40 and any of the objects in the positive electrode 21, negative electrode 22, and mounting hole 11 is the same, and will not be elaborated further here.

[0032] Furthermore, to ensure the reliability of the above-mentioned anchoring bonding, the diameter of the nanopores can be 20-50 nm, and the depth can be 30-100 nm. Based on this, it is preferable to ensure that the shear strength of the interface between the insulating sealant 40 and the nanopore layer is greater than or equal to 35 MPa. It should be understood that if the diameter of the nanopores is less than 20 nm, due to the limitations of the radius of gyration of the engineering plastic molecular chains and the melt viscosity, the plastic molecules cannot effectively penetrate to the bottom of the pores, easily forming voids or unfilled areas at the interface, resulting in a significant reduction in the actual contact area, and the bonding strength cannot meet the stress requirements of the battery's entire life cycle. Conversely, if the micropore diameter exceeds 50 nm, although the melt is easy to fill, the number of micropores per unit area decreases, and the specific surface area of ​​a single micropore decreases, resulting in insufficient anchor point density and a significantly weakened ability of the interface to resist shear slip. At the same time, if the micropore depth is too shallow, it is insufficient to form an effective mechanical locking length, making it prone to debonding under thermal cycling stress; if the depth is too deep, gas at the bottom of the micropore may not be able to escape, forming cavitation defects, which can become the source of crack initiation.

[0033] Furthermore, in a preferred embodiment of this invention, by strictly controlling the etching process parameters, the average diameter of the nanopores can be maintained within the range of 30-40 nm, and the average depth within the range of 50-80 nm. Testing has verified that the shear strength of the interface between the insulating seal 40 and the nanopore layer consistently reaches over 35 MPa, with some optimized samples even reaching 42 MPa. This not only ensures the mechanical stability of the metal electrode 20 under assembly and vibration conditions but also prevents electrolyte leakage along the capillary channels of the metal-plastic interface, thereby guaranteeing the airtightness and long-term aging resistance of the insulating seal 40.

[0034] In some embodiments, such as Figure 4 As shown, the mounting hole 11 can be a stepped hole, which includes at least a first hole segment 111a and a second hole segment 111b distributed along its axial direction. Specifically, the first hole segment 111a can be located on the side of the metal cover plate 10 near the outside of the battery, and the second hole segment 111b can be located on the side of the metal cover plate 10 near the inside of the battery, and the diameter of the second hole segment 111b can be larger than the diameter of the first hole segment 111a; at the same time, a positioning step 111c for transition is formed between the first hole segment 111a and the second hole segment 111b. It should be noted that the mounting hole 11 can adopt a two-stage stepped hole structure, or it can contain three or more stages of hole segments, as long as it can form differentiated spaces for accommodating different functional components.

[0035] For example, an insulating ring 50 is provided in the first hole segment 111a. The end of the insulating ring 50 away from the second hole segment 111b can extend to the outside of the mounting hole 11 and protrude from the surface of the metal cover plate 10 near the outside of the battery to achieve insulation isolation between the exposed section of the metal terminal 20 and the adjacent surface of the metal cover plate 10. At the same time, the aforementioned insulating seal 40 can be filled in the second hole segment 111b, and its side near the first hole segment 111a can extend into the first hole segment 111a and abut against the insulating ring 50. In addition, since the second hole segment 111b is located below the positioning step 111c, the forming process of the insulating seal 40 can be confined within this area and will not overflow upwards into the first hole segment 111a, interfering with the assembly of the insulating ring 50 or contaminating the outer surface of the metal cover plate 10.

[0036] Specifically, the insulating ring 50 is installed in the first hole segment 111a, and its material can be high-temperature resistant, high CTI value engineering plastic or ceramic material. Simultaneously, the insulating ring 50 has a contour shape that matches the first hole segment 111a to ensure its precise positioning in the axial and radial directions. Furthermore, the end of the insulating ring 50 away from the second hole segment 111b (i.e., the end facing the outside of the battery) extends to the outside of the mounting hole 11 and can cover the periphery of the opening of the mounting hole 11. The fitting method between the insulating ring 50 and the first hole segment 111a is not limited to interference fit; it can also be achieved through insert injection molding, hot-melt fixing, or snap-fit ​​connection, etc., without specific limitations. In practical applications, the insulating ring 50 can effectively increase the surface creepage distance, preventing flashover or short circuit between the exposed terminal section and the surface of the metal cover plate 10 under extreme conditions such as humidity, condensation, or electrolyte splashing.

[0037] It should be noted that in this embodiment, the mounting hole 11 is a stepped hole, and the shape of the insulating ring 50 is adapted to the shape of the mounting hole 11. However, in some other embodiments, the mounting hole 11 can also be set as a straight hole, and the insulating ring 50 can be a C-shaped insulating ring 50 (i.e., the cross-section is C-shaped). In this case, the C-shaped opening of the insulating ring 50 can be inserted from the side between the metal pole 20 and the cover plate, and the insulating sealing body 40 can extend upward out of the mounting hole 11 and form a flange. This flange can cooperate with the end of the metal pole 20 to press and fix the insulating ring 50. Alternatively, the independent insulating ring 50 can be omitted, and an insulating cap can be extended above the cover plate during the injection molding of the insulating sealing body 40, so that the insulating cap covers the upper exposed section of the metal pole 20, thereby achieving both sealing and upper insulation. Furthermore, a ceramic insulating coating (such as Al2O3, ZrO2, or AlN coating, with a thickness of 50-200 μm) can be applied to the upper area of ​​the mounting hole 11 using plasma spraying or coating processes to replace the independent insulating ring 50. The tracking resistance of the ceramic coating is far superior to that of organic insulating materials. Similarly, the upper area of ​​the mounting hole 11 can be locally anodized (or the aluminum electrode post can be anodized as a whole, with only the oxide layer removed locally for NMT bonding) to generate a dense Al2O3 insulating layer of 20-50 μm. This insulating layer is integrally formed with the aluminum substrate, eliminating the risk of peeling. In addition, a heat-shrinkable insulating tube (such as PTFE or FEP material) can be inserted onto the upper part of the metal electrode post 20. After the heat-shrinkable insulating tube is heated and shrunk, it forms an insulating layer that adheres tightly to the outer wall of the electrode post. The metal electrode post 20 can then be installed into the metal cover plate 10. This method is simple, flexible, and suitable for small-batch or irregular electrode post shapes.

[0038] In some embodiments, please continue reading Figure 4 The end of the insulating sealing body 40 away from the insulating ring 50 can extend axially along the mounting hole 11 to the outside of the mounting hole 11 and protrude from the surface of the corresponding side of the metal cover plate 10 to form a sealing lip 41. Specifically, the sealing lip 41 can protrude from the surface of the metal cover plate 10 opposite to the insertion direction of the metal pole 20, and its protrusion height relative to the corresponding surface of the metal cover plate 10 can be set to 1mm to 2mm. In addition, a plastic part 30 is also provided on the side of the metal cover plate 10 opposite to the insertion direction of the metal pole 20. The surface of the plastic part 30 near the metal cover plate 10 can fit with the sealing lip 41 to achieve end face sealing.

[0039] It should be noted that the sealing lip 41 in this embodiment can be a continuous annular protrusion, or it can be a discontinuous protrusion or a multi-stage stepped protrusion, etc., as long as it can achieve the functions of axial elastic compensation and end-face sealing, it falls within the protection scope of this invention. Based on this, the sealing lip 41 and the aforementioned insulating ring 50 can be located on opposite sides of the metal cover plate 10, thus forming a "top insulation + bottom sealing" structure. In this case, the sealing lip 41 can be used to solve the sealing problem inside the battery, utilizing the elasticity of engineering plastics to compensate for dimensional deviations caused by injection molding shrinkage and thermal expansion and contraction, blocking the path of electrolyte seepage outward along the outer wall of the metal electrode post 20; simultaneously, the insulating ring 50 can be used to solve the electrical safety problem outside the battery, providing stable insulation support and creepage distance protection. The two do not interfere with each other axially and complement each other functionally, jointly constituting a multi-level leakage protection and insulation protection system.

[0040] Of course, in some other embodiments, the end face of the insulating seal 40 away from the insulating ring 50 can also be flush with the lower surface of the cover plate, without a protruding structure, and instead rely on the large-area planar contact between the insulating seal 40 and the plastic part 30 to achieve end face sealing. Alternatively, the insulating seal 40 can be molded from composite materials. For example, the sealing lip 41 can be made of a flexible material (such as TPV or TPE), while the main body of the insulating seal 40 can be made of a rigid material (such as PPS), integrally molded by two-color injection molding or insert injection molding. In this case, the flexible lip can provide better elastic compensation and contact compliance, and the flatness tolerance requirements for the lower surface of the metal cover plate 10 and the upper surface of the plastic part 30 are lower. Furthermore, a snap-fit ​​structure can also be provided between the sealing lip 41 and the plastic part 30 to enhance the sealing member's ability to resist dislodgement under vibration conditions, which is suitable for vehicle power batteries.

[0041] In some embodiments, please refer to Figure 2 and Figure 5The aforementioned plastic part 30 can be a thin plate substrate injection molded from special engineering plastics such as PPS or modified PFA. This thin plate substrate can be configured as a long, symmetrical racetrack-shaped structure, with a positive electrode support boss 31 and a negative electrode support boss 32 respectively on both sides along its length. Furthermore, the plastic part 30 has two positioning holes 33 (which can be referred to as positive electrode positioning hole 331 and negative electrode positioning hole 332) corresponding to the positive electrode post 21 and the negative electrode post 22, respectively. These two positioning holes 33 can be used to pass through the positive electrode post 21 and the negative electrode post 22. Simultaneously, on the side of the plastic part 30 facing away from the metal cover plate 10, a multi-turn adapter support ridge 34 is also provided around each positioning hole 33. In addition, an explosion-proof valve protection grille 35 is provided in the middle of the plastic part 30 corresponding to the position of the explosion-proof valve plate 14. The explosion-proof valve protection grille 35 is also provided with a matching injection hole 36 corresponding to the injection hole 15 on the metal cover plate 10 on the side near the positive electrode positioning hole 331. Furthermore, multiple reinforcing ribs 37 can be provided between the explosion-proof valve protection grille 35 and the support bosses on both sides.

[0042] In a preferred embodiment of this example, such as Figure 2 As shown, the plastic part 30 near the metal cover plate 10 is also provided with an overflow groove 38 surrounding each metal pole 20. The overflow groove 38 is recessed relative to the surface of the plastic part 30 near the metal cover plate 10, and the aforementioned positioning hole 33 can be provided through the bottom surface of the corresponding overflow groove 38. At this time, when the metal pole 20 is inserted into the corresponding positioning hole 33, the sealing lip 41 of the insulating seal 40 can abut against the bottom surface of the overflow groove 38. It should be understood that the overflow groove 38 can be used to collect excess sealing material that overflows from the annular injection gap or from the venting channel during the injection molding process. It can prevent the overflow material from contaminating the exposed section of the lower part of the metal pole 20, and can also form an auxiliary mechanical lock for the metal pole 20 by solidifying the overflow material in the overflow groove 38.

[0043] Of course, in some other embodiments, the overflow groove 38 may not be provided. Instead, a blind hole can be opened at the center of the bottom of the pole post, or an annular groove can be opened on the outer wall of the bottom of the pole post as a storage cavity. The overflowing sealing material enters the storage cavity through the gap between the metal pole post 20 and the plastic part 30, which helps to simplify the structure of the plastic part 30. Alternatively, an annular cavity can be provided on the lower surface of the metal cover plate 10, and the overflow groove 38 can be provided on the lower surface of the metal cover plate 10, in the annular area surrounding the mounting hole 11. This cavity is directly connected to the insulating seal 40. While the overflow material enters the cavity, it can also increase the contact area between the insulating seal 40 and the cover plate, thus serving the functions of collecting overflow material and strengthening the bond. Furthermore, the overflow groove 38 may not be provided in the product. Instead, an venting groove and an overflow well can be designed in the injection mold. The overflow material is discharged from the mold and solidified before being removed during the demolding process. In addition, the overflow material can be minimized from the source by precisely controlling the injection process parameters (precise metering of injection volume, step-wise optimization of holding pressure, etc.), thereby completely eliminating the design of the overflow groove 38.

[0044] Please see Figure 6 , Figure 6 This is a schematic diagram of the positive electrode post 21; where, Figure 6 (a) is an isometric view of the positive terminal 21. Figure 6 (b) is a front view of the positive terminal 21. Figure 6 (c) is a side view of the positive electrode post 21. In some embodiments, the positive electrode post 21 can be integrally formed from aluminum material to form an aluminum electrode post. The aluminum electrode post can maintain potential matching with the metal cover plate 10 made of aluminum alloy to avoid galvanic cell corrosion in the electrolyte environment. At the same time, aluminum has good conductivity and lightweight advantages, and its coefficient of thermal expansion is consistent with that of the metal cover plate 10, which is beneficial to maintaining the long-term stability of the nano-injection molded sealing interface.

[0045] For example, the positive electrode post 21 includes a top section 211 and a shaft section 212 along its axial direction from top to bottom (i.e., along the direction in which it is inserted into the corresponding mounting hole 11). The top section 211 can be configured as a disc-shaped structure, and the shaft section 212 is integrally formed with the top section 211 and can be configured as a hexagonal prism structure. Simultaneously, the shaft section 212 also has an annular groove 213, forming a cylindrical structure at the annular groove 213, and the positive electrode post 21 as a whole can form a multi-step structure along its axial direction. During injection molding, the injection molding material fills the annular groove 213, forming a structure similar to an O-ring on the inner side of the insulating seal 40. Based on this, the inner side of the insulating ring 50 fits against the positive electrode shaft section 212, and the shape of the inner wall of the insulating ring 50 can be adapted to the shape of the positive electrode shaft section 212; the outer side of the insulating ring 50 fits against the inner wall of the mounting hole 11, and the cross section of the mounting hole 11 perpendicular to its axis can also be a hexagon coaxial with the hexagonal prism portion on the positive electrode shaft section 212. In addition, the shape of the positioning hole 33 on the plastic part 30 can be adapted to the shape of the end of the positive electrode shaft section 212 away from the top section 211 of the positive electrode, that is, the positioning hole 33 can also be set as a hexagonal structure.

[0046] It should be noted that the positive terminal post shaft section 212 is mostly hexagonal prism in shape, which can form a circumferential anti-rotation structure with the outer insulating ring 50 and plastic part 30. When the positive terminal post 21 passes through the corresponding hexagonal hole on the insulating ring 50 or plastic part 30, it can effectively restrict the circumferential rotational freedom of the positive terminal post 21 relative to the metal cover plate 10. At the same time, in practical applications, a large tightening torque is often applied to the metal terminal post 20 during battery module assembly or external wiring. The hexagonal prism structure can reliably transfer this torque load to the insulating ring 50 and / or plastic part 30, preventing the torque from acting directly on the joint interface of the insulating seal 40 and avoiding excessive shear stress that could lead to seal failure. In addition, although a hexagonal prism is used as the anti-rotation structure for the positive terminal post 21 in this embodiment, in other embodiments, it can also adopt other geometric shapes that can achieve circumferential restraint, such as D-shaped cross-section, keyway, pin hole, or polygon, as long as it can prevent the positive terminal post 21 from rotating relative to the cover plate.

[0047] Please see Figure 7 , Figure 7 This is a schematic diagram of the negative electrode post 22; where, Figure 7 (a) is an isometric view of the negative terminal 22. Figure 7 (b) is a front view of the negative terminal 22. Figure 7(c) is a side view of the negative electrode post 22. In some embodiments, the overall structure of the negative electrode post 22 can be similar to that of the positive electrode post 21 described above, that is, it can also be configured as a multi-step structure along its axial direction. The difference is that the negative electrode post 22 includes an upper aluminum segment 221 and a lower copper segment 222 connected to each other along its axial direction. The upper aluminum segment 221 is provided with a negative electrode post top segment 223 at the end away from the lower copper segment 222. The negative electrode post top segment 223 can be configured as a disc-shaped structure and integrally formed with the upper aluminum segment 221. The combination of the upper aluminum segment 221 and the lower copper segment 222 corresponds to the positive electrode shaft segment 212 on the positive electrode post 21. The negative electrode post 22 is provided with a negative electrode post annular groove 224. The interface between the upper aluminum segment 221 and the lower copper segment 222 is located on the bottom surface of the negative electrode post annular groove 224 (i.e., the side surface of the negative electrode post annular groove 224 away from the top segment 223 of the negative electrode post along the axial direction of the negative electrode post 22). At the same time, the combination of the upper aluminum segment 221 and the lower copper segment 222 has a near-hexagonal prism structure, that is, its cross-section may not be a standard hexagon, but a near-hexagonal structure with an anti-rotation flattening part. This anti-rotation flattening part can prevent the negative electrode post 22 from being subjected to torque and rotating when assembling an external busbar. In addition, a connecting structure for connecting the busbar may be provided on the lower copper segment 222. This connecting structure can be a welding cavity (not shown in the figure) for laser penetration welding of the busbar.

[0048] It should be noted that the negative electrode post 22 adopts a split structure of copper-aluminum composite. The upper part of the negative electrode post 22 needs to pass through the metal cover plate 10 and form an NMT (Non-Mechanical Transmission) seal with it. Aluminum is one of the substrates with the highest bonding strength in the NMT process and can achieve good electrochemical compatibility with the aforementioned metal cover plate 10. The lower part of the negative electrode post 22 is made of copper, allowing it to be directly welded to the internal copper busbar, which helps to achieve a low-impedance, high-reliability electrical connection. Furthermore, the upper aluminum section 221 and the lower copper section 222 can be metallurgically bonded through solid-state joining processes such as friction welding, explosive bonding, or cold forging, ensuring extremely low interfacial resistance and sufficient mechanical strength to withstand assembly stress between the two materials.

[0049] Through the above technical solution, this application can form an integrated sealing structure on the top cover of the battery cell. Specifically, the insulating seal 40 directly fills the gap between the metal terminal 20 and the metal cover plate 10, and simultaneously forms a nanoscale anchoring bond with the outer peripheral surface of the metal terminal 20 and / or the hole wall of the mounting hole 11. The dense insulating seal 40 can block the flow channels of gas and liquid, achieving a highly reliable sealing function and effectively preventing electrolyte leakage and external moisture intrusion; at the same time, the excellent insulation properties of the engineering plastic itself achieve electrical isolation between the metal terminal 20 and the metal cover plate 10, avoiding the risk of short circuit; in addition, the high-strength bonding force generated by the nano-anchoring effect can firmly fix the metal terminal 20 to the metal cover plate 10, and can withstand the vibration, impact and thermal cycling stress during battery use. Thus, the top cover assembly provided by this application can eliminate the hidden danger of sealing failure caused by long-term pressure creep, high-temperature aging or swelling of rubber materials, and can also reduce the number of discrete components such as sealing rings and insulating sheets, simplify the assembly process, and help improve the overall reliability and production efficiency of the product.

[0050] Please see Figure 8 The present invention also provides a method for molding a battery cell top cover assembly, which is used to mold the above-mentioned battery cell top cover assembly. The molding method may include the following steps: Step S1 involves nano-sizing the walls of the mounting holes 11 in the metal cover plate 10 and / or the outer peripheral surface of the metal electrode post 20 to form a nanoporous layer. Specifically, processes such as chemical etching, electrochemical anodizing, or laser surface texturing can be used to generate a large number of nano-sized micropores in situ on the metal surface. For example, for the aluminum alloy metal cover plate 10 and the aluminum positive electrode post 21, a T treatment solution containing amine organic acids can be used for chemical etching, or an E treatment process (electrochemical anodizing plus chemical pore expansion) can be used; for the copper section of the copper-aluminum composite negative electrode post 22, a special NMT treatment solution suitable for copper can be selected. The treated metal surface needs to be thoroughly cleaned with deionized water and dried with hot air or vacuum to remove residual moisture in the micropores to prevent cavitation defects during injection molding. It should be understood that the morphological characteristics of the nanoporous layer (such as pore size 20-50nm, depth 30-100nm) directly determine the penetration depth and anchoring density of the subsequent plastic melt, which is the key microstructural basis for ensuring bonding strength.

[0051] In step S2, the metal electrode 20 is placed in the mounting hole 11, creating a gap between the metal electrode 20 and the mounting hole 11. This gap is the annular injection gap on the aforementioned top cover assembly, which not only provides a cavity space for the molten plastic to flow and fill, but also forms the main area of ​​the insulating seal 40. During assembly, the positioning inserts or tooling fixtures of the injection mold can be used to ensure the coaxiality of the metal electrode 20 (such as the positive electrode 21 or the negative electrode 22) and the corresponding mounting hole 11, thereby ensuring that the width of the annular injection gap is uniform in the circumferential direction.

[0052] Step S3: Inject molten engineering plastic into the gaps, allowing the engineering plastic to penetrate the nanoporous layer and fill the gaps. For example, the engineering plastic used can be any one of PPS-GF40 (40% glass fiber reinforced polyphenylene sulfide), PBT-GF30 (30% glass fiber reinforced polybutylene terephthalate), PA66-GF35 (35% glass fiber reinforced nylon 66), and PEEK (polyetheretherketone); wherein the injection molding temperature corresponding to PPS-GF40 engineering plastic can be 290-330℃, the injection molding temperature corresponding to PBT-GF30 engineering plastic can be 250-270℃, the injection molding temperature corresponding to PA66-GF35 engineering plastic can be 260-290℃, and the injection molding temperature corresponding to PEEK engineering plastic can be 360-400℃.

[0053] Based on this, the material selection for the insulating sealant 40 can be specifically tailored to different application scenarios. For example, PPS-GF40, due to its excellent high-temperature resistance (continuous operating temperature 200-240℃) and electrolyte corrosion resistance, is suitable for harsh conditions such as high-energy-density power batteries; PBT-GF30, with its lower cost and wider processing window, is suitable for cost-sensitive large-scale energy storage batteries or two-wheeled vehicle batteries; PA66-GF35, with its good toughness and mechanical strength, can be used in mid-to-low-end consumer electronics batteries; and PEEK, as a special engineering plastic, possesses extremely high heat resistance (250-260℃) and dimensional stability, making it suitable for special batteries used in extreme environments such as aerospace. Furthermore, the injection pressure during the injection molding process can be controlled within the range of 50-100MPa; high-pressure drive is a necessary condition for forcing the high-viscosity melt to overcome capillary resistance and enter the nanopores. It should be understood that although this embodiment lists four specific engineering plastic systems that can be used and their corresponding temperature parameters, these are only exemplary preferred solutions. Other engineering plastic systems that can meet the requirements of high temperature resistance, electrolyte resistance and nano-anchoring bonding with metals are also within the protection scope of this invention, as long as their injection molding process parameters are adapted and adjusted to achieve the same technical effect.

[0054] Step S4 involves cooling and solidification to form an insulating sealant 40 integrally bonded with the nanoporous layer. It should be understood that cooling and solidification is not a simple temperature reduction process, but rather a thermodynamic process involving crystallinity control and internal stress management. For semi-crystalline engineering plastics (such as PPS, PBT, and PA66), mold temperature is a key factor affecting crystallinity. In this embodiment, the mold temperature can be controlled between 130-150°C. Simultaneously, appropriate holding pressure must be maintained during the cooling stage to compensate for the volume shrinkage of the plastic from the molten state to the solid state, ensuring that the insulating sealant 40 remains tightly bonded to the metal surface and ultimately forms an integrated structure with a shear strength ≥35MPa.

[0055] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A battery cell top cover assembly, comprising a metal cover plate and a metal terminal, wherein the metal cover plate has mounting holes for the metal terminal to pass through, characterized in that, The mounting hole wall and / or the outer peripheral surface of the metal electrode post are provided with a nanoporous layer; the battery cell top cover assembly also includes an insulating seal, which is injection molded from engineering plastic in the gap between the metal electrode post and the mounting hole, and is integrated with the nanoporous layer.

2. The cell top cover assembly according to claim 1, characterized in that, The nanoporous layer comprises a plurality of uniformly distributed nanoporous pores; the engineering plastic is configured to be in a molten state during injection molding and to penetrate into the plurality of nanoporous pores, and to be anchored to the metal surface on which the nanoporous layer is located.

3. The cell top cover assembly according to claim 2, characterized in that, The diameter of the nanopores is 20-50 nm and the depth is 30-100 nm; the shear strength of the interface between the insulating seal and the nanopore layer is greater than or equal to 35 MPa.

4. The cell top cover assembly according to claim 1, characterized in that, The diameter of the mounting hole is larger than the outer diameter of the metal pole, so that an annular injection gap is formed between the hole wall of the mounting hole and the metal pole; the insulating sealant fills the annular injection gap and completely seals the annular injection gap.

5. The cell top cover assembly according to claim 1, characterized in that, One end of the insulating seal extends axially along the mounting hole to the outside of the mounting hole and protrudes from the surface of the corresponding side of the metal cover to form a sealing lip.

6. The cell top cover assembly according to claim 5, characterized in that, The mounting hole is a stepped hole, which includes at least a first hole segment and a second hole segment distributed along its axial direction; an insulating ring is provided in the first hole segment, the end of the insulating ring away from the second hole segment extends to the outside of the mounting hole, and is configured to provide insulation between the exposed section of the metal pole and the adjacent surface of the metal cover plate; the insulating seal fills the second hole segment, and the sealing lip protrudes from the side of the metal cover plate opposite to the insulating ring.

7. The cell top cover assembly according to claim 1, characterized in that, It also includes a plastic part disposed on one side of the metal cover plate, wherein the side of the plastic part near the metal cover plate is provided with a positioning hole for inserting the metal pole post, and an overflow groove surrounding the metal pole post is also provided on the outside of the positioning hole.

8. The cell top cover assembly according to claim 1, characterized in that, The metal electrode includes a positive electrode and a negative electrode. The positive electrode is made of aluminum, and the negative electrode includes an upper aluminum section and a lower copper section that are connected to each other.

9. A method for molding a battery cell top cover assembly, characterized in that, The method for molding the cell top cover assembly as described in any one of claims 1-8 includes the following steps: S1. The mounting hole wall of the metal cover plate and / or the outer peripheral surface of the metal pole are nano-sized to form a nanoporous layer. S2. Place the metal electrode post in the mounting hole, so that a gap is formed between the metal electrode post and the mounting hole; S3. Inject molten engineering plastic into the gap, so that the engineering plastic penetrates into the nanoporous layer and fills the gap; S4. Cool and solidify to form an insulating sealant integrally bonded to the nanoporous layer.

10. The molding method according to claim 9, characterized in that, In step S4, the engineering plastic is any one of PPS-GF40, PBT-GF30, PA66-GF35, and PEEK; wherein the injection molding temperature corresponding to PPS-GF40 engineering plastic is 290-330℃, the injection molding temperature corresponding to PBT-GF30 engineering plastic is 250-270℃, the injection molding temperature corresponding to PA66-GF35 engineering plastic is 260-290℃, and the injection molding temperature corresponding to PEEK engineering plastic is 360-400℃.

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