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 is provided with a liquid injection hole, the liquid injection hole is a stepped hole, the stepped hole comprises a guide section and a sealing section which are sequentially reduced in inner diameter size along a liquid injection direction; the cover plate body is a punched product, the inner wall of the guide section is a first bright band; along the liquid injection direction, the inner wall of the sealing section comprises a second bright band and a blanking band which are sequentially formed in a punching process, and the depth h1 of the blanking band and the depth h2 of the second bright band satisfy the relationship: 0.5 <= h2 / (h1+h2) <= 0.8. The application optimizes the proportion of the depth of the second bright band in the depth of the sealing section, so that the sealing section has sufficient second bright band to ensure sealing and has a proper amount of blanking band to reduce mold loss.

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 lithium-ion battery cover 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 also integrates an injection hole. During cell assembly, electrolyte is precisely injected into the cell through this hole, ensuring that the electrolyte fully wets the electrodes and separator, forming an ion-conducting pathway. After injection, the injection hole is completely sealed with sealing nails, ensuring the cell's interior is isolated from the external environment and preventing leakage or oxidation.

[0004] Currently, the cover plate body is typically manufactured using progressive die punching, employing an upper and lower die structure, with the punch and die sleeve working together to complete the process. During punching, the material is subjected to shear stress and compressive stress, resulting in two parts at the injection hole: a bright band and a blanking band. Due to the nature of this manufacturing process, the blanking band is difficult to avoid. The surface of the blanking band is relatively rough, and in this section, the adhesion and sealing effect between the injection hole and the sealing nail is relatively poor, easily leading to poor sealing of the injection hole. 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 poor sealing of the material discharge strip at the injection hole.

[0006] In a first aspect, the present invention provides a battery cell cover assembly, including a cover body, the cover body having an injection hole, the injection hole being a stepped hole, including a guide section and a sealing section whose inner diameter decreases sequentially along the injection direction; the cover body is a product formed by a punching process, the inner wall of the guide section being a first bright band; along the injection direction, the inner wall of the sealing section includes a second bright band and a blanking band formed sequentially during the punching process, the depth of the blanking band being h1 (in mm), and the depth of the second bright band being h2 (in mm), satisfying:

[0007] 0.5≤h2 / (h1+h2)≤0.8.

[0008] Beneficial effects: By optimizing the ratio of the depth of the second bright band to the depth of the sealing section, the present invention ensures that the sealing section has enough second bright band to guarantee sealing performance, while also retaining an appropriate amount of material drop band to reduce mold wear.

[0009] Specifically, if the ratio of the depth h2 of the second bright band to the depth h1+h2 of the sealing section is less than 0.5, the proportion of the rough material strip (fracture surface) within the sealing section is too high. The fracture surface of this material strip contains burrs and microcracks. When the seal is pressed in, the rough surface cannot form a tight fit, resulting in poor sealing and increasing the risk of electrolyte leakage. Simultaneously, excessive fracture surfaces lead to increased fluctuations in the orifice size, affecting the interference fit accuracy of the seal and consequently the sealing effect of the sealing section. Therefore, by limiting h2 / (h1+h2) ≥ 0.5, a sufficient proportion of the second bright band is ensured in the sealing section to provide a precise mating surface, guaranteeing a tight fit after the seal is pressed in, thereby ensuring the sealing performance of the injection hole and reducing the risk of electrolyte leakage.

[0010] If the ratio of the depth h2 of the second bright band to the depth h1+h2 of the sealing section is greater than 0.8, the excessive proportion of the second bright band during punching will significantly increase the shear stress on the punching die, accelerate cutting edge wear, and shorten the die life. Therefore, by limiting h2 / (h1+h2) ≤ 0.8, it is possible to ensure that the sealing section has a sufficient material fracture area, disperse the punching force, reduce the continuous shear load on the die, and thus extend the die life.

[0011] In one alternative implementation, the following condition is also met:

[0012] 0.1mm≤h1≤0.8mm.

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

[0014] 0.6mm≤h2≤1.3mm.

[0015] In one optional embodiment, in the axial section of the injection hole, the inner wall of the sealing section is a straight line, and the inner wall of the guide section is an arc with a radius of r (in mm), satisfying the following:

[0016] 0.3mm≤r≤0.7mm.

[0017] In one optional implementation, the total depth of the injection hole along the injection direction is h, in mm, and satisfies:

[0018] h = h1 + h2 + r,

[0019] 1.2mm≤h≤2.5mm.

[0020] In one optional embodiment, along the injection direction, the cover plate body includes a first surface and a second surface disposed opposite to each other. The first surface of the cover plate body is provided with an annular receiving groove surrounding the injection hole. The inner diameter of the receiving groove is larger than the inner diameter of the guide section, and the inner cavity of the receiving groove communicates with the injection hole.

[0021] In one optional embodiment, along the injection direction, the sidewall of the injection hole protrudes from the second surface of the cover plate body to form a boss, and the height of the boss protruding from the second surface of the cover plate body is h4, in mm, satisfying: 0.5mm≤h4≤1mm.

[0022] In one alternative embodiment, the system further includes a seal and a sealing cap. The seal is disposed within the injection hole and is interference-fitted with the sealing section. The sealing cap is matched and disposed within the receiving groove and is welded to the cover plate body.

[0023] Secondly, the present invention also provides a battery cell, including a housing, an electrode assembly, and a battery cell cover assembly as described above. The housing has an accommodating cavity and an open end communicating with the accommodating cavity; the electrode assembly is disposed within the accommodating cavity; and the battery cell cover assembly is disposed at the open end of the housing and seals the electrode assembly within the housing.

[0024] Beneficial effects: Since the battery cell includes the battery cell cover assembly in the above technical solutions, it has all the technical effects of the battery cell cover assembly, which will not be elaborated here.

[0025] Thirdly, the present invention also provides a battery pack comprising multiple battery cells from more than one technical solution, wherein the battery cells are electrically connected to each other.

[0026] Beneficial effects: Since the battery pack includes the cells in the above technical solutions, it has all the technical effects of the cells, which will not be elaborated here. Attached Figure Description

[0027] 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.

[0028] Figure 1 This is an exploded view of a battery cell cover assembly according to an embodiment of the present invention;

[0029] Figure 2 for Figure 1 A top view of the battery cell cover assembly shown;

[0030] Figure 3 For along Figure 2 Sectional view at point AA;

[0031] Figure 4 for Figure 3 A magnified view of a section at point B in the middle;

[0032] Figure 5 This is a partial cross-sectional view of a battery cell according to an embodiment of the present invention;

[0033] Figure 6 for Figure 5 A magnified view of a section at point C.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Cover plate body; 101. Injection hole; 1011. Guide section; 1012. Sealing section; 1013. Boss; 102. Receiving groove; 103. First surface; 104. Second surface; 2. Sealing element; 3. Sealing cover; 4. Terminal post; 5. Riveting block; 6. First insulating element; 7. Second insulating element; 8. Sealing ring; 10. Cell cover plate assembly; 20. Housing; 30. Electrode group. Detailed Implementation

[0036] 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.

[0037] The following is combined Figures 1 to 6 The following describes embodiments of the present invention.

[0038] According to an embodiment of the present invention, in a first aspect, a battery cell cover assembly 10 is provided, including a cover body 1, the cover body 1 having an injection hole 101, the injection hole 101 being a stepped hole, including a guide section 1011 and a sealing section 1012 whose inner diameter decreases sequentially along the injection direction; the cover body 1 is a product formed by a punching process, the inner wall of the guide section 1011 being a first bright band; along the injection direction, the inner wall of the sealing section 1012 includes a second bright band and a blanking band formed sequentially during the punching process, the depth of the blanking band being h1 (in mm), and the depth of the second bright band being h2 (in mm), satisfying:

[0039] 0.5≤h2 / (h1+h2)≤0.8.

[0040] Since the cover plate body 1 is formed by a punching process, material scrap is unavoidable. The surface of this scrap is relatively rough; if its proportion is too high, the contact surface roughness between the seal 2 and the inner wall of the injection hole 101 will be too large, easily forming micro-gaps, leading to poor sealing of the injection hole 101 and electrolyte leakage. The injection hole 101 mainly relies on the tight fit between the second bright strip and the seal 2 to ensure its sealing performance. This invention solves the problem of poor sealing of the injection hole 101 by controlling the proportion of the second bright strip.

[0041] This invention optimizes the proportion of the depth of the second bright strip in the depth of the sealing section 1012, so that the sealing section 1012 has enough second bright strip to ensure sealing performance, while retaining an appropriate amount of material drop strip to reduce mold wear.

[0042] Specifically, if the ratio of the depth h2 of the second bright band to the depth h1+h2 of the sealing section 1012 is less than 0.5, the proportion of the rough blanking band (fracture surface) within the sealing section 1012 is too high. The fracture surface of the blanking band contains burrs and microcracks. When the seal 2 is pressed in, the rough surface cannot form a tight fit, resulting in poor sealing and increasing the risk of electrolyte leakage. Simultaneously, excessive fracture surfaces lead to increased fluctuations in the orifice size, affecting the interference fit accuracy of the seal 2 and consequently the sealing effect of the sealing section 1012. Therefore, by limiting h2 / (h1+h2) ≥ 0.5, a sufficient proportion of the second bright band is ensured in the sealing section 1012 to provide a precise mating surface, guaranteeing a tight fit after the seal 2 is pressed in, thereby ensuring the sealing performance of the injection hole 101 and reducing the risk of electrolyte leakage.

[0043] If the ratio of the depth h2 of the second bright band to the depth h1+h2 of the sealing section 1012 is greater than 0.8, the excessive proportion of the second bright band during the punching process will significantly increase the shear stress of the punching die, accelerate the wear of the cutting edge, and shorten the die life. Therefore, by limiting h2 / (h1+h2) ≤ 0.8, it can be ensured that the sealing section 1012 has a sufficient material fracture area, disperse the punching force, reduce the continuous shear load on the die, and thus extend the die life.

[0044] The injection hole 101 is also provided with a guide section 1011. Since the guide section 1011 is formed before the sealing section 1012 during the punching process, the guide section 1011 is a bright band. The guide section 1011 can guide the assembly of the sealing element 2 and reduce the assembly resistance.

[0045] Specifically, in some embodiments, the cover plate body 1 is formed by continuous die punching.

[0046] Specifically, the proportion of the second bright band can be controlled by changing the punching gap between the die and the punch, so as to achieve the proportion range defined in this application.

[0047] In some embodiments, the following are also satisfied:

[0048] 0.1mm≤h1≤0.8mm.

[0049] In this embodiment, the depth h1 of the material drop strip is further defined.

[0050] If the depth h1 of the blanking strip is less than 0.1mm, then the ratio of the depth h2 of the second bright strip to the depth h1+h2 of the sealing section 1012 will be too large. This will significantly increase the shear stress of the punching die during the punching process, accelerate the wear of the cutting edge, and shorten the die life.

[0051] If the depth h1 of the material drop strip is greater than 0.8 mm, the proportion of rough material drop strip (fracture surface) in the sealing section 1012 is too high. The fracture surface of the material drop strip has burrs and micro-cracks. When the seal 2 is pressed in, the rough surface cannot form a tight fit, resulting in poor sealing and increasing the risk of electrolyte penetration.

[0052] In some embodiments, the following are also satisfied:

[0053] 0.6mm≤h2≤1.3mm.

[0054] In this embodiment, the range of values ​​for the depth h2 of the second bright band is further defined.

[0055] If the depth h2 of the second bright band is less than 0.6 mm, it will result in insufficient depth of the second bright band, preventing the seal 2 from being fully pressed together and significantly increasing the risk of electrolyte leakage. Furthermore, it will cause the depth ratio of the discharge band to be too high, further weakening the sealing effect. Therefore, by limiting h2 to ≥ 0.6 mm, it is possible to ensure that the sealing section 1012 has a sufficiently deep second bright band, ensuring a tight fit after the seal 2 is pressed in, guaranteeing the sealing performance of the injection hole 101, and reducing the leakage rate.

[0056] If the depth h2 of the second bright band is greater than 1.3mm, given that the total depth of the sealing section 1012 is fixed, the proportion of the second bright band will be too large during the punching process, which will significantly increase the shear stress of the punching die, accelerate the wear of the cutting edge, and shorten the die life.

[0057] In some embodiments, in the axial section of the injection hole 101, the inner wall of the sealing section 1012 is a straight line, and the inner wall of the guide section 1011 is an arc with a radius of r (in mm), satisfying the following:

[0058] 0.3mm≤r≤0.7mm.

[0059] In this embodiment, the range of values ​​for the arc radius r of the guide segment 1011 is further defined.

[0060] If the radius of the arc r < 0.3 mm, the edge of the guide section 1011 is close to a right angle, and the sharp entry edge is prone to interference with the sealing pin. This can cause pin jamming or misalignment, especially in automated assembly, leading to a decrease in assembly yield. Furthermore, the surface of the sealing pin may be scratched by the sharp edge, forming microcracks, increasing the risk of electrolyte penetration after long-term use. Therefore, by limiting r to ≥ 0.3 mm, it is possible to ensure that the guide for the seal 2 during assembly, reducing the insertion resistance of the seal 2 and improving the assembly yield.

[0061] If the radius of curvature r > 0.7 mm, excessive rounding of the guide section 1011 will encroach on the space of the sealing section 1012, resulting in a shortened sealing surface, weakened pressure area of ​​the sealing pin, poor sealing effect, and increased leakage rate. Therefore, by limiting r ≤ 0.7 mm, excessive rounding can be avoided, ensuring that the sealing section 1012 has sufficient effective contact area, thereby guaranteeing sealing performance.

[0062] In some embodiments, along the injection direction, the total depth of the injection hole 101 is h, in mm, satisfying:

[0063] h = h1 + h2 + r,

[0064] 1.2mm≤h≤2.5mm.

[0065] In this embodiment, the range of values ​​for the total depth h of the injection hole 101 is further defined.

[0066] If the total depth h of the injection hole 101 is less than 1.2 mm, the depth of the sealing section 1012 will be too small, resulting in insufficient effective contact length after the sealing pin is pressed in, leading to poor sealing performance and increased leakage rate. Therefore, by limiting h to ≥ 1.2 mm, sufficient sealing surface is ensured between the sealing section 1012 and the sealing element 2.

[0067] Limited by the maximum thickness of the cover plate of 2.5mm, the total depth of the injection hole 101 also does not exceed 2.5mm.

[0068] In some embodiments, along the injection direction, the cover plate body 1 includes a first surface 103 and a second surface 104 disposed opposite to each other. The first surface 103 of the cover plate body 1 is provided with an annular receiving groove 102 surrounding the injection hole 101. The inner diameter of the receiving groove 102 is larger than the inner diameter of the guide section 1011. The inner cavity of the receiving groove 102 communicates with the injection hole 101.

[0069] The annular receiving groove 102 is used to accommodate the installation of the sealing cover 3, and the sealing cover 3 does not protrude from the first surface 103 of the cover plate body 1, so as to avoid occupying the space in the thickness direction of the cover plate body 1.

[0070] In one embodiment, the receiving groove 102 is a tapered groove with a gradually decreasing inner diameter along the injection direction.

[0071] exist Figure 4 In the middle, the upper port diameter of the receiving groove 102 is large, and the lower port diameter is small. The lower end of the annular receiving groove 102 is connected to the upper end of the guide section 1011. This facilitates the welding of the sealing cover 3.

[0072] In some embodiments, along the injection direction, the sidewall of the injection hole 101 protrudes from the second surface 104 of the cover plate body 1 to form a boss 1013. The height of the boss 1013 protruding from the second surface 104 of the cover plate body 1 is h4, in mm, and satisfies:

[0073] 0.5mm≤h4≤1mm.

[0074] Since both the receiving groove 102 and the injection hole 101 are formed by die punching, the forming receiving groove 102 will punch the material of the cover plate body 1, causing it to run from the first surface 103 of the cover plate body 1 to the second surface 104 of the cover plate body 1. After the injection hole 101 is formed, a boss 1013 protruding from the second surface 104 of the cover plate body 1 is finally formed.

[0075] By controlling the height h4 of the boss 1013 protruding from the second surface 104 of the cover plate body 1 to 0.5mm≤h4≤1mm, it is possible to ensure that the receiving groove 102 has sufficient depth to accommodate the sealing cover 3 and to form a sealing section 1012 of sufficient depth to ensure the sealing surface between the injection hole 101 and the sealing element 2, thereby ensuring the sealing performance.

[0076] In some embodiments, the system further includes a seal 2 and a sealing cap 3. The seal 2 is disposed in the injection hole 101 and is press-fitted with the sealing section 1012. The sealing cap 3 is matched and disposed in the annular receiving groove 102 and is welded to the cover plate body 1.

[0077] The seal 2 is adapted to the shape of the injection hole 101. The seal 2 is used to be inserted into the injection hole 101 after injection to seal the injection hole 101 and prevent electrolyte leakage. In some embodiments, the seal 2 is a sealing nail made of an electrolyte-resistant material.

[0078] The shape of the sealing cap 3 is adapted to the shape of the receiving groove 102. The sealing cap 3 serves to limit the sealing element 2 and ensure the sealing effect of the sealing element 2.

[0079] In some embodiments, the cell cover assembly 10 further includes a pole post 4, a riveting block 5, a first insulating element 6, a second insulating element 7, and a sealing ring 8.

[0080] The cover plate body 1, the riveting block 5, the first insulating component 6 and the second insulating component 7 are all provided with through holes for installing the pole post 4. The pole post 4 includes a pole post 4 base plate and a pole post 4 body. The riveting block 5 is located on the first surface 103 of the cover plate body 1, and the pole post 4 base plate is located on the second surface 104 of the cover plate body 1. The pole post 4 body passes through the second insulating component 7, the cover plate body 1, the first insulating component 6 and the riveting block 5 in sequence, and is then riveted and welded to the riveting block 5.

[0081] The first insulating member 6 and the second insulating member 7 together serve to provide an insulating connection between the cover plate body 1 and the pole post 4. In some embodiments, the first insulating member 6 and the second insulating member 7 are plastic parts.

[0082] The sealing ring 8 is fitted onto the pole post 4 and is located between the second insulating component 7 and the base plate of the pole post 4. It is used to seal the connection between the cover plate body 1 and the pole post 4 to ensure the sealing performance of the battery cell.

[0083] According to an embodiment of the present invention, in a second aspect, a battery cell is also provided, including a housing 20, an electrode group 30, and a battery cell cover assembly 10 as described in the above embodiments. The housing 20 has an accommodating cavity and an open end communicating with the accommodating cavity; the electrode group 30 is disposed within the accommodating cavity; and the battery cell cover assembly 10 is disposed at the open end of the housing 20 and seals the electrode group 30 within the housing 20.

[0084] Since the battery cell includes the battery cell cover assembly 10 in the above technical solution, it has all the technical effects of the battery cell cover assembly 10, which will not be described in detail here.

[0085] According to an embodiment of the present invention, a third aspect also provides a battery pack including a plurality of cells as described in the above embodiments, wherein the cells are electrically connected to each other.

[0086] Since the battery pack includes the cells from the above technical solutions, it has all the technical benefits of the cells, so it will not be elaborated here.

[0087] To verify the technical effects of the present invention, specific experimental cases are provided below, including embodiments and comparative examples.

[0088] Test sample: battery cell.

[0089] In this case, the liquid injection hole 101 of the cover plate body 1 is identical in structure and parameters except for the depth h1 of the material drop strip and the depth h2 of the second bright strip. The widths of the second bright strip and the material drop strip are detected by two-dimensional measurement; the one with a smooth and bright surface is the bright strip, and the one with a dark surface is the material drop strip.

[0090] Press the sealing pin (interference allowance 0.05mm) into the injection hole 101 and inject the electrolyte (1MPa pressure, 24h).

[0091] For each experimental case, the sealing performance of the injection hole 101 and the wear of the mold cutting edge were tested.

[0092] Detection method:

[0093] 1. Sealing test:

[0094] The sealing performance of injection port 101 was tested using a helium leak detection method, employing a helium leak detector (helium mass spectrometer 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.

[0095] The sealing performance standard is: leakage rate ≤ 9.9 × 10⁻⁷ / Pa·m 3 / s.

[0096] 2. Detection of die edge wear:

[0097] The die edge wear should be ≤0.005mm, as determined by precision measuring instruments such as micrometers or coordinate measuring machines.

[0098] The actual measurement results are detailed in Table 1.

[0099] Table 1

[0100]

[0101] As can be seen from Table 1:

[0102] In Comparative Examples 1 and 2, h2 / (h1+h2) < 0.5. The depth h2 of the second bright band accounts for too small a proportion of the sum of the depth of the second bright band and the depth of the blanking band (h1+h2). Although the wear of the mold edge is qualified, the poor sealing effect between the injection hole 101 and the sealing nail due to the small depth of the second bright band results in a leakage rate exceeding the qualified range in the sealing test, which does not meet the requirements for battery cell use.

[0103] In Comparative Examples 3 and 4, h2 / (h1+h2) > 0.8, indicating that the depth h2 of the second bright band accounts for too large a proportion of the sum of the depth of the second bright band and the depth of the blanking band (h1+h2). The sealing effect between the injection hole 101 and the sealing nail is good, and the leakage rate is qualified in the sealing test. However, due to the excessively narrow blanking band, the wear of the mold cutting edge is too large, exceeding the qualified range, which affects the service life of the mold. Therefore, its use is not recommended.

[0104] In Examples 1 to 8, h2 / (h1+h2) is within the range of 0.5 to 0.8. The depth h2 of the second bright band has a suitable proportion in the sum of the depth of the second bright band and the depth of the blanking band (h1+h2). The leakage rate is qualified in the sealing test of the injection hole 101 and the sealing pin, and the wear of the die edge is qualified. That is, the present invention can guarantee the die life and punching quality of the injection hole 101, and at the same time, guarantee the matching and sealing between the injection hole 101 and the sealing element 2, thus solving the leakage problem.

[0105] 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 is formed by a punching process, an inner wall of the guide segment is a first bright band; In the axial section of the liquid injection hole, the inner wall of the sealing segment is a straight line, and the inner wall of the guide segment is a circular arc with a radius r (mm) that satisfies 0.3 mm≤r≤0.7 mm; In the axial section of the liquid injection hole, the inner wall of the sealing segment is a straight line, and the inner wall of the guide segment is a circular arc with a radius r (mm) that satisfies 0.3 mm≤r≤0.7 mm; The total depth of the liquid injection hole is h (mm) in the liquid injection direction, and h = h1+h2+r, 1.2 mm≤h≤2.5 mm. In the liquid injection direction, the cover plate body comprises a first surface and a second surface arranged oppositely, the first surface of the cover plate body is provided with an annular accommodating groove surrounding the liquid injection hole, the inner diameter of the accommodating groove is greater than the inner diameter of the guide segment, and an inner cavity of the accommodating groove is in communication with the liquid injection hole. The side wall of the liquid injection hole protrudes from the second surface of the cover plate body to form a boss, the height of the boss protruding from the second surface of the cover plate body is h4 (mm) that satisfies 0.5 mm≤h4≤1 mm. Further comprising: A sealing cover is matched and arranged in the accommodating groove and is welded with the cover plate body. Comprise: A shell has a containing cavity and an open end in communication with the containing cavity; A pole group is arranged in the containing cavity; The electric cell cover plate assembly in any one of claims 1 to 4 is arranged at the open end of the shell and seals the pole group in the shell.

2. The cell cover plate assembly of claim 1, wherein, Comprise a plurality of electric cells as claimed in claim 5, and each of the electric cells is electrically connected.

3. The cell cover plate assembly of claim 2, wherein, ​ ​ 4. The cell cover plate assembly of claim 2, wherein, ​ ​ ​ 5. An electric cell characterized by ​ ​ ​ ​ 6. A battery pack, characterized by, ​

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