Battery cell cover plate assembly, battery cell, and battery pack

Abstract

The application relates to the technical field of batteries and discloses a battery cell cover plate assembly, a battery cell and a battery pack. The battery cell cover plate assembly comprises a cover plate body, the cover plate body comprises a convex section and an assembly section along the thickness direction of the cover plate body, a step surface is formed between the convex section and the assembly section, the cover plate body is adapted to be overlapped with an open end surface of a shell of a battery cell at the step surface and is welded by butt welding, and the assembly section is adapted to be assembled into the inside of the shell; the cover plate body is a continuous die punching molding product and is punched along the thickness direction of the cover plate body; the convex section comprises a first bright band and a blanking band which are sequentially formed in the punching process, and the assembly section is a second bright band; the thickness h1 of the convex section and the thickness h' of the blanking band satisfy a preset condition. The application can solve the problem that it is difficult for laser welding to identify the assembly gap between the shell and the cover plate body, thereby causing problems such as welding missing and welding deviation.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to cell cover assemblies, cells, and battery packs. Background Technology

[0002] With the increasing maturity of lithium-ion battery technology, lithium-ion batteries are widely used as power batteries in electric vehicles and energy storage, and the requirements for the performance and safety of lithium-ion batteries are becoming increasingly stringent.

[0003] The cell cover assembly is a key component in lithium-ion batteries. Its functions include welding with the casing to form a sealed cavity, leading out the positive and negative electrodes, and serving as an assembly carrier. The cell cover assembly consists of the cover body, which is currently manufactured by continuous die punching, using an upper and lower die structure, and completed by the cooperation of a punch and a die sleeve.

[0004] During the punching process of the cover plate body, the material is subjected to shear stress and compressive stress. The outer wall of the cover plate body forms two parts along its thickness direction: a bright band and a blanking band. Due to the influence of this processing technology, the blanking band is difficult to avoid. The surface of the blanking band is relatively rougher than that of the bright band. After the housing and the battery cell cover plate assembly are assembled, the gap trajectory between the housing and the cover plate body is affected by the blanking band, which makes laser welding positioning difficult, the welding trajectory is prone to deviation, resulting in poor welding, air leakage in the weld, and other problems. Summary of the Invention

[0005] In view of this, the present invention provides a cell cover assembly, a cell, and a battery pack to solve the problem of difficulty in identifying the assembly gap between the housing and the cover body by laser welding, which leads to defects such as incomplete welding and misaligned welding.

[0006] In a first aspect, the present invention provides a battery cell cover assembly, comprising a cover body, the cover body including a protruding section and an assembly section along its thickness direction, a stepped surface forming between the protruding section and the assembly section, the cover body being adapted to overlap and butt weld with the open end face of the battery cell housing at the stepped surface, and the assembly section being adapted to be assembled into the interior of the housing; the cover body is a continuously die-cut product, punched along the thickness direction of the cover body; the protruding section includes a first bright strip and a blanking strip formed sequentially during the punching process, and the assembly section is a second bright strip; the thickness of the protruding section is h1 in mm, and the thickness of the blanking strip is h' in mm, satisfying:

[0007] 0.5≤h' / h1≤0.8.

[0008] Beneficial effects:

[0009] By precisely controlling the ratio h' / h1 of the thickness h' of the blanking strip to the thickness h1 of the raised section to between 0.5 and 0.8, the die life and punching quality can be guaranteed. At the same time, it creates stable and reliable recognition conditions for the visual recognition system of the laser welding system, thereby fundamentally solving the problems of welding trajectory deviation and air leakage.

[0010] Specifically, during the punching process, the punch presses into the material, initially forming a bright band. As the punch continues to descend, the internal stress of the material reaches its limit, causing fracture and forming a blanking band. The formation of the blanking band is essentially a rapid tearing process, generating intense friction and impact on the die cutting edge. If h' / h1 < 0.5, the blanking band is narrow, while the thickness h1-h' of the first bright band is relatively wide, meaning the die's punching clearance may be too small. In this case, the stroke required for material fracture is extremely short, the fracture process is very violent, and the impact force on the cutting edge is enormous. Simultaneously, the thinner fracture surface causes more severe scraping of the die sidewalls as it exits the die, exacerbating die wear.

[0011] Therefore, h' / h1≥0.5 ensures that the blanking strip has sufficient thickness, reduces the instantaneous impact load and friction on the die cutting edge, and significantly delays the wear and chipping of the die.

[0012] In laser welding, a vision-based automatic recognition system is typically used to ensure precise weld seam positioning. This system uses a camera to capture the assembly gap (i.e., the "joint") between the cover plate body and the housing, and uses this as a basis to guide the trajectory of the laser welding torch.

[0013] If h' / h1 > 0.8, this means that the thickness h' of the blanking strip occupies most of the raised section, while the first bright strip area h1-h', which eventually contacts the end face of the shell and is welded together, is very narrow. Because the blanking strip has a rough, non-reflective, and dull color, while the first bright strip has a smooth, highly reflective, and bright color, the vision system needs a sufficiently wide first bright strip to form a clear and stable image feature to distinguish it from the blanking strip and the weld.

[0014] If the first bright band is too narrow, its imaging characteristics in the camera are weak, making it easy to confuse with the adjacent rough blanking band area, resulting in blurred boundaries and the vision system's inability to accurately locate the actual assembly gap. The vision system may mistakenly identify the edge of the blanking band as the gap to be welded, causing the laser welding gun trajectory to deviate and weld in the wrong position.

[0015] Therefore, h' / h1 ≤ 0.8 ensures that the first bright band has sufficient width (at least 20% of the total thickness of the raised section). This smooth, bright area provides the visual recognition system with a high-contrast, stable, and clear target area. The system can unambiguously distinguish the assembly gap between the end face of the housing and the cover plate body, thereby guiding the laser for precise welding and fundamentally avoiding welding defects and weld leaks caused by trajectory deviation.

[0016] In one alternative implementation, the following condition is also met:

[0017] 0.25mm≤h'≤0.7mm.

[0018] In one alternative implementation, the following condition is also met:

[0019] 0.5mm≤h1≤1.4mm.

[0020] In one optional implementation, the thickness of the assembly section is h2 (mm), and the total thickness of the cover plate body is H (mm), satisfying the following:

[0021] 0.3≤h2 / H≤0.6.

[0022] In one alternative implementation, the following condition is also met:

[0023] 0.5mm≤h2≤1.5mm.

[0024] In one alternative implementation, the following condition is also met:

[0025] 1.2mm≤H≤3mm.

[0026] In one alternative embodiment, along the thickness direction of the cover plate body, the cover plate body further includes a chamfered section, which is connected to the assembly section, and the chamfered section is a third bright band.

[0027] In one optional implementation, the thickness of the chamfered section is h3, in mm, satisfying:

[0028] H = h1 + h2 + h3,

[0029] 0.15mm≤h3≤0.4mm.

[0030] Secondly, the present invention also provides a battery cell, including a housing, an electrode assembly, and a battery cell cover plate assembly as described above. The housing has an accommodating cavity and an open end communicating with the accommodating cavity; the electrode assembly is disposed in the accommodating cavity of the housing; in the battery cell cover plate assembly, the assembly section of the cover plate body is disposed in the accommodating cavity of the housing, and the protruding section of the cover plate body is disposed outside the open end face of the housing; the housing and the cover plate body are welded together to encapsulate the electrode assembly within the housing.

[0031] Beneficial effects: Since the battery cell includes the battery cell cover assembly, it has the same effect as the battery cell cover assembly, so it will not be elaborated here.

[0032] Thirdly, the present invention also provides a battery pack comprising multiple battery cells from more than one technical solution, wherein each battery cell is electrically connected.

[0033] Beneficial effects: Since the battery pack includes battery cells, it has the same effects as the battery cells, which will not be elaborated here. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 This is an exploded view of a battery cell cover assembly according to an embodiment of the present invention;

[0036] Figure 2 for Figure 1 The diagram shows the assembled structure of the battery cell cover assembly.

[0037] Figure 3 for Figure 2 The front view of the battery cell cover assembly shown;

[0038] Figure 4 for Figure 3 A magnified view of a section at point A in the middle;

[0039] Figure 5 This is a partially enlarged view of a battery cell according to an embodiment of the present invention;

[0040] Figure 6 For along Figure 5 Sectional view at point BB;

[0041] Figure 7 for Figure 6 A magnified view of a section at point C.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Cell cover assembly; 101. Cover body; 1011. Protruding section; 1012. Assembly section; 1013. Chamfered section; 1014. First bright strip; 1015. Blanking strip; 1016. Second bright strip; 1017. Third bright strip; 102. Terminal post; 103. Riveting block; 104. First insulating component; 105. Second insulating component; 106. Sealing ring; 2. Housing; 3. Electrode assembly; 100. Cell; 200. Weld. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0045] The following is combined Figures 1 to 7 The following describes embodiments of the present invention.

[0046] According to an embodiment of the present invention, in a first aspect, a battery cell cover assembly 1 is provided, comprising a cover body 101, the cover body 101 including a protruding section 1011 and an assembly section 1012 along its thickness direction, a stepped surface being formed between the protruding section 1011 and the assembly section 1012, the cover body 101 being adapted to overlap and butt weld with the open end face of the housing 2 of the battery cell 100 at the stepped surface, and the assembly section 1012 being adapted to be assembled into the interior of the housing 2; the cover body 101 is a continuously die-cut product, punched along the thickness direction of the cover body 101; the protruding section 1011 includes a first bright strip 1014 and a blanking strip 1015 formed sequentially during the punching process, and the assembly section 1012 is a second bright strip 1016; the thickness of the protruding section 1011 is h1 (mm), and the thickness of the blanking strip 1015 is h' (mm), satisfying:

[0047] 0.5≤h' / h1≤0.8.

[0048] By precisely controlling the ratio h' / h1 of the thickness h' of the blanking strip 1015 to the thickness h1 of the protruding section 1011 to between 0.5 and 0.8, the die life and punching quality can be guaranteed. At the same time, it creates stable and reliable recognition conditions for the visual recognition system of the laser welding system, thereby fundamentally solving the problems of welding trajectory deviation and air leakage.

[0049] Specifically, during the punching process, the punch presses into the material, initially forming a first bright band 1014. As the punch continues to descend, the internal stress of the material reaches its limit, causing fracture and forming a blanking band 1015. The formation of the blanking band 1015 is essentially a rapid tearing process, generating intense friction and impact on the die cutting edge. If h' / h1 < 0.5, the blanking band 1015 is relatively narrow, while the thickness h1-h' of the first bright band 1014 is relatively wide, meaning the die's punching clearance may be too small. In this case, the stroke required for material fracture is extremely short, the fracture process is very violent, and the impact force on the cutting edge is enormous. Simultaneously, the thinner fracture surface causes more severe scraping of the die sidewalls as it exits the die, exacerbating die wear.

[0050] Therefore, h' / h1≥0.5 ensures that the blanking strip 1015 has sufficient thickness, reducing the instantaneous impact load and friction on the die cutting edge, and significantly delaying the wear and chipping of the die.

[0051] During laser welding, a vision-based automatic recognition system is typically used to ensure the precise positioning of the weld seam 200. This system uses a camera to capture the assembly gap (i.e., the "joint") between the cover plate body 101 and the housing 2, and uses this as the basis to guide the trajectory of the laser welding torch. The position of the weld seam 200 is as follows: Figure 7 As shown.

[0052] If h' / h1>0.8, this means that the thickness h' of the blanking strip 1015 occupies most of the raised section 1011, while the area h1-h' of the first bright strip 1014 that eventually contacts and welds to the end face of the housing 2 is very narrow. Since the blanking strip 1015 has a rough, non-reflective, and dull color, while the first bright strip 1014 has a smooth, highly reflective, and bright color, the vision system needs a sufficiently wide first bright strip 1014 to form a clear and stable image feature to distinguish it from the blanking strip 1015 and the weld.

[0053] The first bright band 1014 is too narrow, resulting in weak imaging characteristics in the camera. It is easily confused with the adjacent rough blanking band 1015, leading to blurred boundaries and the vision system's inability to accurately locate the actual assembly gap. The vision system may mistakenly identify the edge of the blanking band 1015 as the gap to be welded, causing the laser welding gun trajectory to deviate and weld in the wrong position.

[0054] Therefore, h' / h1 ≤ 0.8 ensures that the first bright band 1014 has sufficient width (at least 20% of the total thickness of the raised section 1011). This smooth, bright area provides the visual recognition system with a high-contrast, stable, and clear target area. The system can unambiguously distinguish the assembly gap between the end face of the housing 2 and the cover body 101, thereby guiding the laser for precise welding and fundamentally avoiding poor welding and air leakage in the weld 200 due to trajectory deviation.

[0055] Specifically, the proportion of blanking strip 1015 can be controlled by changing the blanking clearance between the die and the punch, so as to achieve the proportion range defined in this application.

[0056] In one embodiment, the following is also satisfied:

[0057] 0.25mm≤h'≤0.7mm.

[0058] By limiting h' to ≥ 0.25 mm, the mold can be protected, and the stability and economy of the punching process can be maintained.

[0059] If h' < 0.25 mm, to form such a thin blanking strip 1015, the clearance between the punch and die usually needs to be set very small. The extremely small clearance will cause great lateral extrusion and friction between the die edge and the material, resulting in rapid wear, dulling, and even chipping of the cutting edge.

[0060] By limiting h' to ≤ 0.7 mm, the success rate of identification and the accuracy of welding trajectory can be improved, fundamentally eliminating welding deviation and air leakage caused by identification errors.

[0061] The thickness h' of the blanking strip 1015 determines the distance between the rough fracture surface and the housing assembly gap after assembly. If h' > 0.7 mm, the assembly gap between the blanking strip 1015 and the housing is too small, which will cause the visual recognition system to misjudge and generate incorrect welding trajectories, causing the laser welding gun to deviate, directly resulting in poor welding, off-center welding, and missed welding.

[0062] In one embodiment, the following is also satisfied:

[0063] 0.5mm≤h1≤1.4mm.

[0064] By limiting h1 to ≥ 0.5 mm, the strength and sealing of the welded structure can be guaranteed, and welding abnormalities can be avoided. Specifically, the protruding section 1011 is the area where the cover plate body 101 overlaps with the end face of the shell 2 and is laser-welded. Its total thickness h1 directly determines the penetration depth and strength of the weld joint.

[0065] If h < 0.5 mm, the material of the cover plate body 101 is too thin, and the control window for energy input during laser welding is very narrow. It is highly susceptible to burn-through or ablation due to slightly higher energy, affecting the sealing performance of the cover plate body 101. Furthermore, even if welding is successfully completed, the thin base material results in very small weld penetration and cross-sectional area, leading to low mechanical strength of the weld joint. This joint cannot withstand the pressure that may be generated inside the battery or external impacts, making it prone to cracking. Simultaneously, the sealing reliability is poor, making it difficult to guarantee against leakage during long-term use. Additionally, the protruding section 1011 needs to form an effective overlap with the end face of the casing 2. An excessively thin protruding section 1011 may deform due to assembly or welding stress, failing to form a stable butt joint.

[0066] By limiting h1 to 1.4mm, design redundancy is eliminated, and cost and weight are controlled.

[0067] If h1 > 1.4 mm, the cover plate body 101 is usually made of metals such as aluminum alloy. Increasing the thickness will directly lead to an increase in the material cost per piece. The additional material weight will reduce the energy density of the battery system.

[0068] Based on the above analysis, as long as the proportion of the blanking strip 1015 in the raised section 1011, h' / h1, and the thickness h' of the blanking strip 1015 are controlled within a reasonable range, the raised section 1011 only needs to be controlled within the range of 0.5mm to 1.4mm, which can fully meet the requirements of welding and quality identification. Increasing the thickness further would be a redundant design, leading to an increase in the cost and weight of the cover plate body 101.

[0069] In one embodiment, the thickness of the assembly section 1012 is h2 (mm), and the total thickness of the cover plate body 101 is H (mm), satisfying the following:

[0070] 0.3≤h2 / H≤0.6.

[0071] By limiting h2 / H to ≥ 0.3, it is possible to ensure that weld 200 has sufficient mechanical properties and long-term reliable sealing, thus meeting the requirements for use with power batteries.

[0072] Laser welding is a rapid melting and solidification process. The weld width and depth of weld 200 are crucial to the strength and sealing of the joint. If h2 / H < 0.3, the assembly section 1012 is relatively thin, resulting in insufficient weld width of weld 200. A narrow and thin weld 200 has an extremely small effective load-bearing cross-section and low mechanical strength (tensile and shear resistance), making it unable to effectively withstand the pressure generated inside the battery and prone to cracking. Furthermore, the narrow weld 200 has extremely low tolerance for microscopic defects such as porosity and cracks; any tiny defect may penetrate the entire weld 200 cross-section, causing sealing failure (air or liquid leakage).

[0073] By limiting h2 / H to ≤ 0.6, a smooth assembly process is ensured, and difficulties in press-fitting are avoided.

[0074] The assembly section 1012 needs to be inserted into the housing 2, with an interference or tight fit between them to ensure stability and alignment after assembly, providing a prerequisite for laser welding. If h2 / H>0.6, the assembly section 1012 is too thick, resulting in an excessively large proportion of the section inserted into the housing. This causes most of the thickness of the cover plate body 101 to be crammed into the housing 2, leaving very little space for the external welding protrusion section 1011. Simultaneously, the excessively long assembly section 1012 significantly increases the mating area, resulting in a marked increase in the required pressing resistance. During the pressing process, this may cause scratches on the cover plate body 101 or the housing 2, damaging surface quality and even generating metal debris that contaminates the inside of the battery cell. Assembly becomes difficult, yield decreases, and excessive resistance may even cause the cover plate body 101 to be improperly pressed in or tilted, thus affecting the precise alignment required for welding.

[0075] In one embodiment, the following is also satisfied:

[0076] 0.5mm≤h2≤1.5mm.

[0077] By limiting h2 to ≥ 0.5 mm, sufficient weld penetration and connection strength can be guaranteed.

[0078] In laser welding, the penetration depth of weld 200 is closely related to the thickness of the base material. The thickness h2 of assembly section 1012 directly determines the maximum usable material thickness that the laser energy can affect, thus limiting the maximum penetration depth that can be achieved.

[0079] If h2 < 0.5 mm, the material is too thin, and the laser can easily melt it completely, resulting in limited penetration depth and cross-section of weld 200. Shallow and thin weld 200 has poor tensile strength and fatigue resistance, and the risk of cracking of weld 200 increases significantly during battery charge-discharge cycles or when subjected to external impacts.

[0080] By limiting h2 to 1.5mm, over-design is avoided, achieving lightweighting and cost control.

[0081] If h2 > 1.5mm, according to the welding principle, once the material thickness reaches a certain level, further increasing the thickness will have a negligible contribution to improving the strength of the weld 200. Assembly section 1012 with a thickness exceeding 1.5mm is a redundant design, which will lead to an increase in the cost and weight of the cover plate body 101, and will also reduce the energy density of the entire battery pack.

[0082] In one embodiment, the following is also satisfied:

[0083] 1.2mm≤H≤3mm.

[0084] By limiting H to ≥ 1.2 mm, the cover plate body 101 is ensured to have sufficient strength, reducing assembly difficulty and guaranteeing welding yield.

[0085] If H < 1.2mm, the overall strength of the cover plate body 101 will be insufficient. An excessively thin cover plate body 101 has extremely poor resistance to bending and deformation. During battery assembly, handling, and use, even minor external forces can cause plastic deformation or warping of the cover plate body 101, affecting the internal sealing environment of the battery and even leading to internal short circuits. Furthermore, the assembly of the cover plate body 101 and the housing 2 typically requires a certain pressing force. Insufficient rigidity of the cover plate body 101 makes it prone to deformation when pressed into the housing 2, leading to assembly failure or uneven gaps after assembly. This, in turn, prevents stable energy absorption during laser welding, easily causing defects such as weld burn-through and incomplete fusion, resulting in a significant decrease in yield.

[0086] By limiting H to ≤ 3mm, the lightweight design and cost control of the cover plate body 101 can be guaranteed.

[0087] If H > 3mm, the design is redundant, which will increase the cost and weight of the cover plate body 101 and reduce the energy density of the entire battery pack.

[0088] In one embodiment, along the thickness direction of the cover plate body 101, the cover plate body 101 further includes a chamfered section 1013, which is connected to the assembly section 1012, and the chamfered section 1013 is a third bright band 1017.

[0089] The assembly section 1012 has an interference fit or tight fit with the inner wall of the battery casing 2, meaning that the diameter of the assembly section 1012 is slightly larger than the inner diameter of the casing 2. During the press-fit process, a certain force needs to be applied to press the cover plate body 101 into the casing 2. The chamfer forms a smooth conical transition. During press-fitting, even if there is a slight concentricity deviation between the cover plate body 101 and the casing 2, the chamfer design can easily guide the cover plate body 101 into the casing 2, greatly reducing the assembly difficulty. At the same time, the smooth bevel replaces the sharp right angle, and the contact between the cover plate body 101 and the inner wall of the casing 2 is gradual, effectively avoiding scratches and assembly damage. This fundamentally eliminates the risk of metal fragments generated during the assembly process, ensuring the internal safety of the battery cell.

[0090] In one embodiment, the thickness of the chamfered segment 1013 is h3 in mm, satisfying:

[0091] H = h1 + h2 + h3,

[0092] 0.15mm≤h3≤0.4mm.

[0093] By limiting h3 to ≥ 0.15 mm, effective guidance and protection functions can be ensured, and scratches can be prevented.

[0094] If h3 < 0.15 mm, the chamfer is too small or too steep, and the angle of the resulting guide slope is too large (close to a right angle), which cannot effectively play a guiding role. During the process of pressing the cover plate body 101 into the housing 2, it is still easy to scrape against the inner wall of the housing 2, and the risk of generating metal burrs (shavings) is extremely high.

[0095] By limiting h3 to 0.4mm, given a fixed total thickness H of the cover plate body 101, it is possible to ensure that the thickness h2 of the assembly section 1012 is within the reasonable range specified above, thus avoiding welding risks.

[0096] If h3 > 0.4 mm, since H = h1 + h2 + h3, with the total thickness H of the cover plate body 101 and the thickness h1 of the protruding section 1011 relatively fixed, an excessively large thickness h3 of the chamfered section 1013 will directly lead to a reduction in the thickness h2 of the assembly section 1012. As mentioned earlier, the thickness h2 of the assembly section 1012 is crucial for ensuring weld penetration and strength. If h2 is excessively compressed due to an excessively large chamfer, it will result in poor welding between the shell 2 and the cover plate body 101.

[0097] According to an embodiment of the present invention, in a second aspect, a battery cell 100 is also provided, including a housing 2, an electrode group 3, and a battery cell cover assembly 1 as described in the above embodiments. The housing 2 has an accommodating cavity and an open end communicating with the accommodating cavity; the electrode group 3 is disposed in the accommodating cavity of the housing 2; in the battery cell cover assembly 1, the assembly section 1012 of the cover body 101 is disposed in the accommodating cavity of the housing 2, and the protruding section 1011 of the cover body 101 is disposed outside the open end face of the housing 2; the housing 2 is welded to the cover body 101 to encapsulate the electrode group 3 within the housing 2.

[0098] Since the battery cell 100 includes the battery cell cover assembly 1, which has the same effect as the battery cell cover assembly 1, it will not be described in detail here.

[0099] Specifically, in some embodiments, the cell cover assembly 1 further includes a pole post 102, a riveting block 103, a first insulating element 104, a second insulating element 105, and a sealing ring 106.

[0100] The cover plate body 101, the riveting block 103, the first insulating component 104 and the second insulating component 105 are all provided with through holes for mounting pole posts 102. The pole post 102 includes a pole post base plate and a pole post body. The pole post base plate and the riveting block 103 are respectively provided on two opposite surfaces of the cover plate body 101. The pole post body passes through the second insulating component 105, the cover plate body 101, the first insulating component 104 and the riveting block 103 in sequence, and is then riveted and welded to the riveting block 103.

[0101] The first insulating element 104 is used to provide an insulating connection between the cover plate body 101 and the riveting block 103.

[0102] The second insulating element 105 is used to provide an insulating connection between the cover plate body 101 and the pole post 102.

[0103] The sealing ring 106 is used to seal the connection between the cover plate and the terminal post 102, ensuring the sealing performance of the battery cell.

[0104] In some embodiments, cell 100 includes blade cells.

[0105] According to an embodiment of the present invention, in a third aspect, a battery pack is also provided, including a plurality of battery cells 100 as described in the above embodiments, wherein each battery cell 100 is electrically connected.

[0106] Since the battery pack includes cell 100 and has the same effect as cell 100, it will not be described in detail here.

[0107] To verify the technical effects of the present invention, specific experimental cases are provided below, including embodiments and comparative examples.

[0108] Test sample object: battery cell. Among them, the cover plate body 101 has the same structure and parameters except for the thickness h1 of the raised section 1011 and the thickness h' of the material dropping strip 1015.

[0109] Welding sealing and mold edge wear were tested for each experimental case.

[0110] Detection method:

[0111] 1. Sealing test:

[0112] The sealing performance of the battery cell casing and cell cover assembly welding is tested using a helium leak detector, specifically a helium mass spectrometer (helium leak detector). A helium leak detector is a high-precision instrument that uses helium as a tracer gas and combines it with mass spectrometry analysis to detect leaks. Its core principle is to utilize the inertness, low background noise, and small molecule properties of helium to inject or surround the workpiece under test, and then quantify the leak rate by detecting the amount of helium leakage.

[0113] The weld sealing performance qualification standard is: leakage rate ≤ 9.9 × 10⁻⁶. -7 / Pa·m 3 / s.

[0114] 2. Detection of die edge wear:

[0115] The die edge wear should be ≤0.005mm, as determined by precision measuring instruments such as micrometers or coordinate measuring machines.

[0116] The actual measurement results are detailed in Table 1.

[0117] Table 1

[0118]

[0119] As can be seen from Table 1:

[0120] In Comparative Examples 1 and 2, h' / h1 < 0.5, indicating that the width of the blanking strip in the raised section is too small, while the width of the first bright strip is too large. Although the leakage rate is qualified in the sealing test of the shell cover welding, the blanking strip is too narrow, resulting in excessive wear on the die edge, exceeding the qualified range and affecting the service life of the die. Therefore, its use is not recommended.

[0121] In Comparative Examples 3 and 4, h' / h1 > 0.8, indicating that the width of the blanking strip in the raised section is too large and the width of the first bright strip is too small. Although the wear of the mold edge is qualified, the welding quality between the shell and the cell cover plate assembly is poor due to the small width of the first bright strip. The leakage rate exceeds the qualified range in the sealing test after welding, which does not meet the requirements for cell use.

[0122] In Examples 1 to 8, h' / h1 is within the range of 0.5 to 0.8, the width ratio of the blanking strip in the raised section is appropriate, the leakage rate is qualified in the sealing test of the shell cover welding, and the wear of the die edge is qualified. That is, the present invention can guarantee the die life and punching quality, while ensuring the welding quality of the shell cover and solving the problem of air leakage.

[0123] Although embodiments of the 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 invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An electrochemical cell cover plate assembly, comprising: The cover plate body includes a raised section and a fitting section along the thickness direction thereof, a stepped surface is formed between the raised section and the fitting section, the cover plate body is adapted to be lapped and seam-welded with an open end surface of a shell of the battery cell at the stepped surface, and the fitting section is adapted to be fitted into the interior of the shell; The cover plate body is a continuous die punching molded product, and is punched along the thickness direction of the cover plate body; The raised section includes a first bright band and a blanking band formed in sequence during the punching process, and the fitting section is a second bright band; The thickness of the raised section is h1, in mm, The thickness of the blanking band is h', in mm, 0.5≤h' / h1≤0.8 is satisfied; 0.25mm≤h'≤0.7mm, 0.5mm≤h1≤1.4mm are further satisfied; The thickness of the fitting section is h2, in mm, The total thickness of the cover plate body is H, in mm, 0.3≤h2 / H≤0.6 is satisfied; 0.5mm≤h2≤1.5mm, 1.2mm≤H≤3mm are further satisfied. The cover plate body further includes a chamfer section along the thickness direction of the cover plate body, the chamfer section is connected with the fitting section, and the chamfer section is a third bright band. The thickness of the chamfer section is h3, in mm, and H=h1+h2+h3, 0.15mm≤h3≤0.4mm are satisfied. The battery cell includes: A shell having a receiving cavity and an open end communicating with the receiving cavity; A pole group arranged in the receiving cavity of the shell; The battery cell cover plate assembly of any one of claims 1 to 3, wherein the fitting section of the cover plate body is arranged in the receiving cavity of the shell, the raised section of the cover plate body is arranged outside the open end surface of the shell, the shell is welded with the cover plate body, and the pole group is encapsulated in the shell.

2. The cell cover plate assembly of claim 1, wherein, The battery cell includes a plurality of the battery cell of claim 4, and each of the battery cells is conductively connected.

3. The cell cover plate assembly of claim 2, wherein, ​ ​ ​ 4. An electric cell characterized by ​ ​ ​ ​ 5. A battery pack, characterized by, ​

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