Cover plate assembly of battery cell, battery cell and battery pack

Abstract

The application relates to the technical field of batteries and discloses a cover plate assembly of a battery cell, the battery cell and a battery pack. The cover plate assembly of the battery cell comprises a cover plate body, the cover plate body comprises an assembly section and a chamfer section along the thickness direction of the cover plate body, the assembly section is suitable for being assembled into a shell of the battery cell, the bottom surface of the assembly section is limited by abutting against a supporting structure of the inner wall of the shell of the battery cell, and the top surface of the assembly section is flush with the open end surface of the shell of the battery cell; the cover plate body is a continuous die punching and cutting forming product, the punching direction is the thickness direction of the cover plate body; the assembly section comprises a first bright band and a blanking band which are sequentially formed in the punching process, and the chamfer section is a second bright band; the thickness h of the cover plate body, the thickness h3 of the chamfer section and the thickness h2 of the first bright band satisfy preset conditions. The application can ensure that the cover plate body is smoothly assembled into the shell, avoid metal chips from falling into the shell, ensure the performance of the battery cell and the service life and punching quality of the die.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a cover plate assembly for a battery cell, a battery cell, and a battery pack. 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 cover plate 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 cover plate assembly consists of the cover plate body, which is currently manufactured by continuous die punching, using an upper and lower die structure, and completed by the cooperation of punches and die sleeves.

[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 this processing technology, the blanking band is difficult to avoid. The surface of the blanking band is relatively rougher than the bright band. Therefore, during assembly, because the cover plate body and the housing have a zero-clearance fit along the length of the cover plate assembly, the assembly resistance between the cover plate body and the housing is relatively large. The cover plate body is prone to friction with the housing, causing scratches on both the housing and the cover plate body, and generating metal shavings that enter the housing, resulting in cell malfunctions. Summary of the Invention

[0005] In view of this, the present invention provides a cover plate assembly for a battery cell, a battery cell, and a battery pack to solve the problems of high assembly resistance between the cover plate body and the housing, surface scratches, or metal shavings entering the housing and causing abnormalities in the battery cell.

[0006] In a first aspect, the present invention provides a cover plate assembly for a battery cell, comprising a cover plate body, the cover plate body including an assembly section and a chamfered section along its thickness direction, the assembly section having a bottom surface and a top surface disposed opposite to each other along the thickness direction of the cover plate body, the assembly section being adapted to be assembled into the housing of the battery cell, and the bottom surface of the assembly section abutting and limiting the connection with a support structure of the inner wall of the battery cell housing, the top surface of the assembly section being flush with the open end face of the battery cell housing; the cover plate body is a product formed by continuous die stamping, the stamping direction being the thickness direction of the cover plate body; the assembly section includes a first bright strip and a blanking strip formed sequentially during the stamping process, the chamfered section being a second bright strip; the thickness of the cover plate body is h (mm), the thickness of the chamfered section is h3 (mm), the thickness of the first bright strip is h2 (mm), satisfying:

[0007] 0.6≤h2 / (h-h3)≤0.9.

[0008] Beneficial effects: By precisely controlling the ratio of the thickness of the first bright strip to the thickness of the assembly section within the range of 0.6 to 0.9, it is possible to ensure that the cover plate body is smoothly installed into the housing, and to avoid surface scratches on both, prevent metal shavings from falling into the housing, and ensure the performance of the battery cell. At the same time, it can also ensure the life of the mold and the quality of the punching.

[0009] If h2 / (h-h3) < 0.6, the first bright band is narrower, which means that the thickness of the blanking band is wider. The surface of the blanking band is rough. Along the length of the cover plate assembly, since the cover plate body and the housing are in a zero-clearance fit, the assembly resistance between the cover plate body and the housing is large, and the two rub against each other, resulting in surface scratches and metal chips falling into the housing, causing cell abnormalities.

[0010] Therefore, h2 / (h-h3)≥0.6 can ensure that the assembly section has a sufficiently thick first bright band, ensure that the cover plate body is smoothly installed into the housing, and avoid surface scratches on both, prevent metal shavings from falling into the housing, and ensure the performance of the battery cell.

[0011] If h2 / (h-h3) > 0.9, this means that the first bright band occupies most of the assembly section, while the blanking band is too narrow, requiring an excessively small die clearance. 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.

[0012] Therefore, h2 / (h-h3)≤0.9 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.

[0013] In one alternative implementation, the following condition is also met:

[0014] 0.8mm≤h2≤2.5mm.

[0015] In one alternative implementation, the following condition is also met:

[0016] 0.2mm≤h3≤0.5mm.

[0017] In one alternative implementation, the following condition is also met:

[0018] 1.4mm≤h≤3.5mm.

[0019] In one optional implementation, the thickness of the blanking strip is h1, in mm, and satisfies:

[0020] 0.2mm≤h1≤1mm.

[0021] Secondly, the present invention also provides a battery cell, including a housing, an electrode assembly, and a cover plate assembly for the battery cell described in the above technical solutions. The housing has an accommodating cavity and an open end communicating with the accommodating cavity; the housing includes two oppositely arranged large surfaces and two oppositely arranged narrow side surfaces, and the inner wall of the narrow side surfaces is provided with a support structure near the open end; the electrode assembly is disposed in the accommodating cavity of the housing; the assembly section of the cover plate body in the cover plate assembly is disposed in the accommodating cavity of the housing, the bottom surface of the assembly section abuts against the support structure, and the top surface of the assembly section is flush with the open end face of the housing; the cover plate body is welded to the housing to encapsulate the electrode assembly inside the housing.

[0022] Beneficial effects: Since the battery cell includes the cover plate assembly of the battery cell, it has the same effect as the cover plate assembly of the battery cell, which will not be elaborated here.

[0023] In one alternative embodiment, the narrow side of the housing includes a main body section and a mating section, the inner wall surface of the mating section being recessed into the inner wall surface of the main body section, and the stepped surface located between the main body section and the mating section forming a support structure.

[0024] In one optional implementation, the depth of the mating section is h4, in mm, satisfying:

[0025] h4 = h - h3.

[0026] In one alternative embodiment, the cover plate body has a short sidewall that mates with the narrow side of the housing and a long sidewall that mates with the large surface of the housing; the narrow side of the housing and the short sidewall of the cover plate body are in clearance fit, and the large surface of the housing and the long sidewall of the cover plate body are in zero clearance fit.

[0027] 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.

[0028] 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

[0029] 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.

[0030] Figure 1 This is a top view of a cover plate assembly for a battery cell according to an embodiment of the present invention;

[0031] Figure 2 for Figure 1 The front view of the cover plate assembly shown;

[0032] Figure 3 for Figure 2 A magnified view of part of C;

[0033] Figure 4 This is a top view of a battery cell according to an embodiment of the present invention;

[0034] Figure 5 For along Figure 4 Sectional view at point AA;

[0035] Figure 6 for Figure 5 A magnified view of a section at point E in the middle;

[0036] Figure 7 For along Figure 4 Sectional view at point BB;

[0037] Figure 8 for Figure 7 A magnified view of a section at point D;

[0038] Figure 9 for Figure 5 A magnified view of a portion of the middle cover plate assembly.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Cover plate assembly; 101. Cover plate body; 1011. Assembly section; 1012. Chamfer section; 1013. First bright strip; 1014. Material dropping strip; 1015. Long side wall; 1016. Short side wall; 1017. Second bright strip; 102. Terminal post; 103. First insulating component; 104. Second insulating component; 105. Sealing ring; 106. Explosion-proof valve; 107. Explosion-proof valve protective patch; 2. Housing; 201. Main body section; 202. Mating section; 203. Support structure; 204. Large surface; 205. Narrow side surface; 3. Electrode group; 100. Battery cell. Detailed Implementation

[0041] 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.

[0042] The following is combined Figures 1 to 9 The following describes embodiments of the present invention.

[0043] According to an embodiment of the present invention, a cover plate assembly 1 for a battery cell is provided, comprising a cover plate body 101. The cover plate body 101 includes an assembly section 1011 and a chamfered section 1012 along its thickness direction. The assembly section 1011 has a bottom surface and a top surface disposed opposite to each other along the thickness direction of the cover plate body 101. The assembly section 1011 is adapted to be assembled into a housing 2 of the battery cell, and the bottom surface of the assembly section 1011 abuts and limits the support structure 203 of the inner wall of the housing 2 of the battery cell, and the top surface of the assembly section 1011 is flush with the battery cell. The open end face of the shell 2 is flush; the cover plate body 101 is a product formed by continuous die punching, and the punching direction is the thickness direction of the cover plate body 101; the assembly section 1011 includes a first bright strip 1013 and a blanking strip 1014 formed sequentially during the punching process, and the chamfer section 1012 is a second bright strip 1017; the thickness of the cover plate body 101 is h (in mm), the thickness of the chamfer section 1012 is h3 (in mm), and the thickness of the first bright strip 1013 is h2 (in mm), satisfying:

[0044] 0.6≤h2 / (h-h3)≤0.9.

[0045] Specifically, the thickness of the cover plate body 101 is h, the thickness of the chamfered section 1012 is h3, and h-h3 is the thickness of the assembly section 1011. The thickness of the first bright strip 1013 in the assembly section 1011 is h2, and h2 / (h-h3) is the thickness ratio of the first bright strip 1013 in the assembly section 1011. By precisely controlling the ratio of the thickness of the first bright strip 1013 to the thickness of the assembly section 1011 within the range of 0.6 to 0.9, it is possible to ensure that the cover plate body 101 can be smoothly installed into the housing 2, avoiding surface scratches on both, preventing metal shavings from falling into the housing 2, and ensuring the performance of the battery cell. Simultaneously, it also ensures the lifespan of the mold and the quality of the punching.

[0046] Specifically, during the punching process, the punch presses into the material, initially forming a first bright band 1013. As the punch continues to descend, the internal stress of the material reaches its limit, causing fracture and forming a blanking band 1014. The formation of the blanking band 1014 is essentially a rapid tearing process, generating intense friction and impact on the die cutting edge. If h2 / (h-h3) < 0.6, the first bright band 1013 is relatively narrow, meaning the blanking band 1014 is relatively thick. Since the blanking band 1014 has a rough surface, along the length of the cover plate assembly 1, the zero-clearance fit between the cover plate body 101 and the housing 2 results in high assembly resistance, causing friction and surface scratches. This generates metal shavings that fall into the housing 2, leading to cell malfunctions.

[0047] Therefore, h2 / (h-h3)≥0.6 can ensure that the assembly section 1011 has a first bright band 1013 of sufficient thickness, ensuring that the cover plate body 101 can be smoothly installed into the housing 2, and avoiding surface scratches on both, preventing metal shavings from falling into the housing 2, and ensuring the performance of the battery cell.

[0048] If h2 / (h-h3) > 0.9, this means that the first bright band 1013 occupies most of the assembly section 1011, while the blanking band is too narrow, requiring the die's punching clearance to 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. At the same time, the thinner material fracture surface causes more severe scraping of the die sidewalls when ejected from the die, exacerbating die wear.

[0049] Therefore, h2 / (h-h3)≤0.9 ensures that the blanking strip 1014 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.

[0050] In some embodiments, the following are also satisfied:

[0051] 0.8mm≤h2≤2.5mm.

[0052] By limiting h2 to ≥ 0.8 mm, an effective weld penetration depth can be ensured, thereby ensuring the connection strength and airtightness between the cover plate body 101 and the shell 2.

[0053] Laser welding is a high-energy-density, rapid melting and solidification process. The welding process requires melting a certain amount of base material to form a molten pool. After the laser energy penetrates the blanking strip 1014, it enters the first bright strip 1013. If the thickness of the first bright strip 1013 is too thin, less than 0.8 mm, the cover plate body 101 is extremely sensitive to parameters such as laser power, welding speed, and focal point position. The process window is very narrow, and even minor fluctuations during production can lead to welding failure and a decrease in yield. The most direct risk is insufficient penetration. The laser may only melt the shallow surface layer, failing to form a sufficiently deep metallurgical bond with the shell material. The mechanical strength (tensile and shear strength) and sealing performance (prevention of electrolyte leakage) of such a weld cannot meet the requirements for long-term use under high vibration and high pressure environments of power batteries, posing a significant safety hazard.

[0054] Therefore, setting the lower limit of h2 to 0.8 mm is to ensure sufficient material thickness to stably absorb laser energy and ensure that a weld with qualified penetration depth and strength is obtained.

[0055] By limiting h2 to 2.5mm, it is possible to achieve lightweighting and cost control while ensuring performance, thus avoiding the negative impact of over-design.

[0056] The core indicator of a power battery is its energy density (energy stored per unit volume or unit weight). If the assembly section 1011 is too thick, exceeding 2.5mm, it will result in an excessively thick cover plate body 101, increasing its overall weight and reducing the battery system's gravimetric energy density. It will also increase the space occupied by the cells, indirectly reducing the usable space inside the cells and lowering the volumetric energy density. Furthermore, increasing the cover plate body 101 will lead to increased raw material and processing (punching) costs, constituting unnecessary design redundancy.

[0057] In some embodiments, the following are also satisfied:

[0058] 0.2mm≤h3≤0.5mm.

[0059] The chamfered section 1012 is a beveled or rounded area formed at the bottom of the assembly section 1011 of the cover plate body 101. It serves as an assembly guide and helps the cover plate body 101 to easily align with the opening of the housing 2 during the process of pressing the cover plate body 101 into the housing 2, preventing jamming or deflection.

[0060] If h3 < 0.2mm, the thickness of the chamfered section 1012 is too small to effectively guide the assembly of the cover body 101 into the casing. Even a slight misalignment will cause rigid interference and jamming. When forcibly pressed in, the hard edge of the cover body 101 will violently scrape against the edge of the casing 2, scraping off metal fragments or particles (foreign objects). These foreign metal objects falling into the battery, between the positive and negative terminals, can easily puncture the separator during charging, discharging, and vehicle vibrations, causing internal short circuits and leading to battery thermal runaway—an extremely serious safety hazard.

[0061] Therefore, by limiting h3 to ≥ 0.2 mm, we can ensure that the chamfer has sufficient dimensions to perform its key guiding function, guarantee a smooth assembly process, avoid the generation of metal particles (foreign objects) due to scratching, and thus eliminate the risk of internal short circuits in the battery.

[0062] By limiting h3 to ≤ 0.5 mm, effective weld penetration can be ensured. If h3 > 0.5 mm, the thickness h3 of the chamfered section 1012 will be too large. Given a fixed total thickness h of the cover plate body 101, the excessively thick chamfered section 1012 will encroach on the thickness h-h3 of the assembly section 1011, resulting in insufficient weld penetration between the cover plate body 101 and the shell 2, thus affecting the weld strength.

[0063] In some embodiments, the following are also satisfied:

[0064] 1.4mm≤h≤3.5mm.

[0065] The thickness h of the cover plate body 101 determines the structural strength and rigidity of the cover plate body 101, and also directly affects the weight and cost of the battery.

[0066] During charge-discharge cycles, especially under abnormal conditions such as overcharging or thermal runaway, a large amount of gas is generated inside the battery, causing a sharp increase in pressure. The cover body 101 must have sufficient strength and rigidity to resist this pressure and prevent permanent deformation, bulging, or even bursting. If the cover body 101 is too thin, h < 1.4 mm, its bending strength and rigidity will be significantly reduced, making it prone to deformation under internal pressure, losing its sealing and protective functions, and causing safety accidents.

[0067] The connection between the cover plate body 101 and the shell 2 relies on a laser welding process. The strength of the weld depends not only on the penetration depth but also on the thickness of the base material (cover plate body 101). The cover plate body 101 has sufficient thickness, allowing the weld to withstand higher tensile and shear stresses, as well as the expansion forces inside the battery, external mechanical vibrations, and impacts.

[0068] Therefore, by limiting h to ≥ 1.4 mm, it is possible to ensure that the cover plate body 101 has sufficient mechanical strength to withstand internal pressure and provides sufficient material thickness to form a robust and reliable laser weld.

[0069] By limiting h to ≤ 3.5 mm, it is possible to avoid increased weight, higher costs, and reduced energy density due to over-design while meeting all performance requirements.

[0070] In some embodiments, the thickness of the blanking strip 1014 is h1, in mm, and satisfies:

[0071] 0.2mm≤h1≤1mm.

[0072] The blanking strip 1014 is the area formed when the material breaks and separates during the final stage of the continuous die punching process. The blanking strip 1014 has a rough surface, with obvious fracture slopes (also known as fracture zones), and may even have tiny burrs.

[0073] A stamping die consists of a punch and a die. If h1 < 0.2 mm, the die clearance selected in actual production should be as small as possible. If the clearance is too small, it will generate extremely large lateral extrusion forces and friction, causing the die cutting edge to wear out quickly, become dull, or even break.

[0074] Therefore, by limiting h1 to ≥ 0.2 mm, we can ensure that the punching die has a reasonable clearance, reduce die wear, extend its service life, and thus ensure production stability and economy.

[0075] When the cover plate body 101 is pressed into the housing 2, its entire outer peripheral surface (including the smooth first bright band 1013 and the rough material strip 1014) will come into contact with and rub against the inner wall of the housing 2. If the material strip 1014 is too thick (h1>1mm), a wide area on the side wall of the cover plate body 101 will have a very rough surface. This rough surface will generate huge frictional resistance with the inner wall of the housing 2, which may require greater pressing force from the assembly equipment, or cause the cover plate body 101 to jam or stop during the pressing process, or cause it to scrape against the inner wall of the housing 2, generating metal debris (foreign objects). If these debris fall into the battery cell, they can easily cause an internal short circuit, leading to battery thermal runaway and posing a serious safety hazard.

[0076] Therefore, by limiting h1≤1mm, the width of the material drop strip 1014 can be controlled, the frictional resistance when the cover plate body 101 is pressed into the housing 2 can be reduced, ensuring smooth assembly and avoiding the generation of metal foreign objects due to scratching.

[0077] Specifically, in some embodiments, the cover plate assembly 1 further includes a pole post 102, a first insulating element 103, a second insulating element 104, a sealing ring 105, an explosion-proof valve 106, and an explosion-proof valve protective patch 107.

[0078] The cover plate body 101, the first insulating component 103, and the second insulating component 104 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 body passes through the second insulating component 104, the cover plate body 101, and the first insulating component 103 in sequence and is then riveted and fixed.

[0079] The first insulating element 103 and the second insulating element 104 together serve to provide an insulating connection between the cover plate body 101 and the pole post 102.

[0080] The sealing ring 105 is used to seal the connection between the cover plate body 101 and the pole post 102 to ensure the sealing performance of the battery cell.

[0081] The cover plate body 101 is also provided with an explosion-proof valve mounting hole. The explosion-proof valve 106 is located in the explosion-proof valve mounting hole. An explosion-proof valve protection patch 107 is provided on the cover plate body 101 at the position corresponding to the explosion-proof valve 106. The explosion-proof valve protection patch 107 covers most of the area of ​​the explosion-proof valve 106 and is used to protect the explosion-proof valve 106.

[0082] According to an embodiment of the present invention, in a second aspect, a battery cell is also provided, including a housing 2, an electrode assembly 3, and a cover plate assembly 1 of the battery cell in the above embodiments. The housing 2 has an accommodating cavity and an open end communicating with the accommodating cavity; the housing 2 includes two oppositely arranged large surfaces 204 and two oppositely arranged narrow side surfaces 205, and the inner wall of the narrow side surfaces 205 is provided with a support structure 203 near the open end; the electrode assembly 3 is disposed in the accommodating cavity of the housing 2; the mounting section 1011 of the cover plate body 101 in the cover plate assembly 1 is disposed in the accommodating cavity of the housing 2, the bottom surface of the mounting section 1011 abuts against the support structure 203, and the top surface of the mounting section 1011 is flush with the open end face of the housing 2; the cover plate body 101 is welded to the housing 2 to encapsulate the electrode assembly 3 inside the housing 2.

[0083] The bottom surface of the assembly section 1011 abuts against the support structure 203 of the inner wall of the shell 2, and the top surface is flush with the open end face of the shell 2, ensuring that the cover plate body 101 will not tilt or sink before welding.

[0084] As mentioned above, the thickness h2 of the first bright band 1013 of the cover plate body 101 and the thickness h3 of the chamfer section 1012 have been optimized to ensure the stability of the laser welding process, form a high-quality weld with sufficient penetration, continuous uniformity, and no defects, and ensure the long-term sealing of the battery to prevent electrolyte leakage and external moisture intrusion.

[0085] By controlling the thickness h3 of the chamfered section 1012 and the thickness h1 of the blanking strip 1014, the cover plate body 101 is pressed into the housing 2 smoothly without scraping, avoiding the risk of internal short circuit caused by metal particles (foreign objects) generated during the assembly process, and greatly improving the intrinsic safety of the battery cell.

[0086] By controlling the total thickness h of the cover plate body 101, it is made to have sufficient mechanical strength to resist the pressure expansion caused by gas generation inside the battery, and to prevent the cover plate body 101 from deforming or breaking.

[0087] Since the battery cell 100 includes the cover plate assembly 1 of the battery cell, it has all the effects of the cover plate assembly 1 of the battery cell, and other technical effects will not be described in detail here.

[0088] In some embodiments, the narrow side 205 of the housing 2 includes a main body section 201 and a mating section 202, the inner wall surface of the mating section 202 is recessed into the inner wall surface of the main body section 201, and the stepped surface located between the main body section 201 and the mating section 202 constitutes a support structure 203.

[0089] The main body section 201 is the main part of the narrow side 205 of the shell 2. The mating section 202 is a section near the open end of the shell 2, and its inner wall surface is concave outward relative to the inner wall surface of the main body section 201, which slightly increases the width of the cavity at this point. Due to the concavity of the inner wall surface of the mating section 202, a step is naturally formed between the main body section 201 and the mating section 202. This step surface is the support structure 203 for supporting the bottom surface of the assembly section 1011 of the cover plate body 101.

[0090] The housing 2 has two oppositely arranged narrow sides 205, each with a support structure 203. After the cover plate body 101 is pressed into the housing 2, the bottom surfaces of the assembly sections 1011 at both ends along the length of the cover plate body 101 abut against the two support structures 203, ensuring that the cover plate body 101 is properly assembled and will not sink. Simultaneously, it ensures that the top surface of the cover plate body 101 is flush with the open end face of the housing 2, guaranteeing a smooth welding interface and thus forming a uniform weld, ensuring the cell's sealing performance.

[0091] In some embodiments, the depth of the mating segment 202 is h4, in mm, satisfying:

[0092] h4 = h - h3.

[0093] The total thickness h of the cover plate body 101, the thickness h3 of the chamfered section 1012 of the cover plate body 101, and the depth h4 of the mating section 202 of the shell 2, i.e. the vertical distance from the open end face to the step surface, are matched with the thickness h-h3 of the assembly section 1011 of the cover plate body 101.

[0094] This ensures that when the cover plate body 101 is installed in place, the top surface of the cover plate body 101 is flush with the open end face of the shell 2, which is beneficial to improving the performance of the weld.

[0095] In some embodiments, the cover body 101 has a short sidewall 1016 that mates with the narrow sidewall 205 of the housing 2 and a long sidewall 1015 that mates with the large surface 204 of the housing 2; the narrow sidewall 205 of the housing 2 and the short sidewall 1016 of the cover body 101 are in clearance fit, and the large surface 204 of the housing 2 and the long sidewall 1015 of the cover body 101 are in zero clearance fit.

[0096] Specifically, the short sidewall 1016 of the cover plate body 101 and the narrow sidewall 205 of the housing 2 are the two sides in the width direction of the battery cell, and are relatively short. The long sidewall 1015 of the cover plate body 101 and the large surface 204 of the housing 2 are the two sides in the length direction of the battery cell, and are relatively long.

[0097] The short sidewall 1016 of the cover plate body 101 is clearance-fitted with the narrow sidewall 205 of the housing 2, that is, there is a tiny gap between the mating surfaces of the two, such as... Figure 6As shown. This fit clearance, along with the chamfered section 1012, ensures that the cover body 101 can smoothly enter the shell, while preventing metal shavings from being generated between the cover body 101 and the shell 2 due to scratching.

[0098] The long sidewall 1015 of the cover plate body 101 and the large surface 204 of the shell 2 have a zero-clearance fit, meaning there is no gap between their mating surfaces, or it is an interference fit, which may involve slight compression. This ensures sufficient contact area and a tight connection between the cover plate body 101 and the large surface 204 of the shell 2. Simultaneously, laser welding is performed along the long side of the top surface of the cover plate body 101, resulting in a flush and tight contact between the cover plate body 101 and the shell 2, forming a stable and uniform mating interface, enabling the production of continuous, uniform, and defect-free high-quality welds.

[0099] In some embodiments, the battery cell includes a prismatic cell.

[0100] According to an embodiment of the present invention, in a third aspect, a battery pack is also provided, comprising a plurality of cells as described in the above embodiments, wherein each cell is electrically connected.

[0101] Since the battery pack includes cell 100 and has the same effect as cell 100, it will not be described in detail here.

[0102] To verify the technical effects of the present invention, specific experimental cases are provided below, including embodiments and comparative examples.

[0103] The sample being tested was from the cover plate assembly process. Except for the thickness h of the cover plate body 101 and the thickness h2 of the first bright band, the rest of the structure and parameters were identical.

[0104] For each experimental case, the resistance of the cover plate being inserted into the shell and the wear of the mold cutting edge were tested.

[0105] Detection method:

[0106] 1. Cover Plate Assembly Resistance Detection: During the cover plate assembly process, a resistance sensor is used to detect the resistance during cover plate assembly. The resistance is denoted as F, and the unit is N. F ≤ 50 N is required.

[0107] 2. Detection of die edge wear:

[0108] The die edge wear should be ≤0.005mm, as determined by precision measuring instruments such as micrometers or coordinate measuring machines.

[0109] The actual measurement results are detailed in Table 1.

[0110] Table 1

[0111]

[0112] As can be seen from Table 1:

[0113] In Comparative Examples 1 and 2, h2 / (h-h3) < 0.6, the first bright band is narrow. Although the wear of the mold edge is qualified, the thickness of the blanking strip is wide, the assembly resistance of the shell and cover is large, exceeding 50N, and the two rub against each other, resulting in surface scratches, which does not meet the requirements for use of the battery cell.

[0114] In Comparative Examples 3 and 4, h2 / (h-h3) > 0.9, indicating that the width of the first bright band in the assembly section is too large, while the blanking band is too narrow. Although the assembly resistance of the shell cover is small and meets the requirements, the wear of the die edge is large and exceeds the acceptable range, so it is not recommended to use it.

[0115] In Examples 1 to 8, h2 / (h-h3) is within the range of 0.6 to 0.9, the width ratio of the first bright band in the assembly section is appropriate, the shell cover assembly resistance test is qualified, and the die edge wear test is qualified. That is, the present invention can guarantee die life and punching quality, while reducing the shell cover assembly resistance and preventing surface scratches or metal shavings from entering the shell and causing cell abnormalities.

[0116] 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. A cover plate assembly for an electrical cell, characterized by The cover plate body includes an assembly section and a chamfer section along the thickness direction of the cover plate body, the assembly section has a bottom surface and a top surface oppositely arranged along the thickness direction of the cover plate body, the assembly section is adapted to be assembled into the shell of the battery cell, and the bottom surface of the assembly section is limited by abutting against the support structure of the inner wall of the shell of the battery cell, and the top surface of the assembly section is flush with the open end surface of the shell of the battery cell. The cover plate body is a continuous die cutting molded product, and the cutting direction is the thickness direction of the cover plate body. The assembly section includes a first bright band and a blanking band formed in sequence during the cutting process, and the chamfer section is a second bright band. The thickness of the cover plate body is h, in mm, The thickness of the chamfer section is h3, in mm, The thickness of the first bright band is h2, in mm, 0.6≤h2 / (h-h3)≤0.9 is satisfied. 0.8mm≤h2≤2.5mm, 0.2mm≤h3≤0.5mm, 1.4mm≤h≤3.5mm, The thickness of the blanking band is h1, in mm, and 0.2mm≤h1≤1mm is satisfied. The shell has a receiving cavity and an open end communicating with the receiving cavity; the shell includes two oppositely arranged large faces and two oppositely arranged narrow side faces, and the inner wall of the narrow side face is provided with a support structure near the open end; The pole group is arranged in the receiving cavity of the shell; The cover plate assembly of the battery cell of claim 1, wherein the assembly section of the cover plate body is arranged in the receiving cavity of the shell, the bottom surface of the assembly section abuts against the support structure, and the top surface of the assembly section is flush with the open end surface of the shell; and the cover plate body is welded to the shell to encapsulate the pole group in the shell.

2. An electric cell, characterized by The narrow side face of the shell includes a main section and a fitting section, the inner wall surface of the fitting section is recessed from the inner wall surface of the main section, and a stepped surface between the main section and the fitting section constitutes the support structure. The depth of the fitting section is h4, in mm, and h4=h-h3 is satisfied. The cover plate body has a short side wall matched with the narrow side face of the shell and a long side wall matched with the large face of the shell; the narrow side face of the shell and the short side wall of the cover plate body are gap-fitted, and the large face of the shell and the long side wall of the cover plate body are zero-gap-fitted. The plurality of battery cells of any one of claims 2 to 5 are electrically connected.

3. The electric cell of claim 2, wherein, ​ 4. The electric cell of claim 3, wherein, ​ ​ 5. The electric cell of any one of claims 2 to 4, wherein, ​ 6. A battery pack, characterized by, ​

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