Cover plate assembly, battery cell and battery pack

Abstract

The present application relates to the technical field of battery, disclose a cover plate assembly, battery cell and battery pack, the cover plate assembly includes: cover plate body, has the pole hole, the pole includes the column and the bottom plate, the column is worn in the pole hole, the annular groove is set up on the column, the annular groove is located in the middle position of the column along Z direction, and the annular groove is set along the circumference of the column in XY plane, the cross-sectional area of the column segment that the column is not set annular groove in XY plane is S, the column segment that the column is located on the side away from the bottom plate of annular groove is the first column segment, the cross-sectional area of the first column segment in XY plane is S1, wherein, S and S1 between satisfy the relationship formula: 0.15≤(S‑S1) / S≤0.6;The first plastic piece includes a plastic piece body and a convex ring, the plastic piece body is annularly sleeved on the column, and the plastic piece body is connected with the cover plate body, the convex ring is connected on the inner ring of the plastic piece body, and the convex ring is connected with the annular groove. The connection stability between the first plastic piece and the pole is improved.

Description

Technical Field

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

[0002] The cover plate assembly mainly consists of a cover plate body, terminals, an upper plastic part, and a lower plastic part. The terminals are mounted on the cover plate body, the lower plastic part is located on the side of the cover plate body facing the inner cavity of the cell housing, and the upper plastic part is located on the side of the cover plate body away from the inner cavity of the cell housing, between the terminals and the cover plate body. Existing technologies include cover plate assemblies where the upper plastic part is directly injection molded between the terminals and the cover plate body. However, during cell use, when subjected to external forces, the terminals and plastic part are prone to loosening, resulting in poor connection reliability between the plastic part and the terminals. This affects the airtightness between the terminals and the plastic part, and may even lead to terminals detaching, seriously impacting the safety of the cell. Summary of the Invention

[0003] This invention provides a cover plate assembly, a battery cell, and a battery pack to solve the problem of poor connection reliability between the plastic part and the terminal post.

[0004] In a first aspect, the present invention provides a cover plate assembly, comprising: a cover plate body having an electrode post hole; an electrode post, including a column body and a base plate, the column body passing through the electrode post hole, the column body having an annular groove, the annular groove being located at the middle position of the column body along the Z direction, and the annular groove being arranged circumferentially along the column body in the XY plane, a column segment on the side of the column body located away from the base plate from the annular groove being a first column segment, the cross-sectional area of ​​the first column segment in the XY plane being S, and the cross-sectional area of ​​the column segment with the annular groove in the XY plane being S1, wherein S and S1 satisfy the relationship: 0.15≤(S-S1) / S≤0.6; and a first plastic part, including a plastic part body and a convex ring, the plastic part body being annularly sleeved on the column body, and the plastic part body being connected to the cover plate body, the convex ring being connected to the inner ring of the plastic part body, and the convex ring being engaged with the annular groove.

[0005] Beneficial effects: By creating an annular groove on the outer circumference of the electrode post, and connecting the first plastic part around the outer circumference of the electrode post with a protruding ring on the first plastic part, the first plastic part and the electrode post are axially limited by the engagement of the protruding ring and the annular groove. Simultaneously, by limiting the ratio between the cross-sectional area of ​​the annular groove and the cross-sectional area of ​​the first column segment to within the range of 0.15 to 0.6 in the XY plane, a reasonable ratio is achieved between the engagement area of ​​the protruding ring and the electrode post and the cross-sectional area of ​​the first column segment. This prevents the protruding ring from detaching from the annular groove, ensuring the stability and reliability of the connection between the electrode post and the first plastic part, guaranteeing the airtightness between the first plastic part and the electrode post, and preventing cracking and damage to the first plastic part. Furthermore, it avoids excessive resistance in the column segment with the annular groove due to an excessively large cross-sectional area, thus preventing excessive temperature difference between the upper and lower surfaces of the electrode post. This ensures the accuracy of temperature acquisition by the temperature acquisition device located on the upper surface of the electrode post, which is beneficial to improving the safety of the battery cell.

[0006] In one alternative embodiment, the orthographic projection of the cylinder along the Z direction in the XY plane is circular.

[0007] Beneficial effects: The column is cylindrical, with a simple structure, easy to process and shape, and facilitates smooth assembly.

[0008] In one alternative embodiment, the annular groove is circular in the orthographic projection of its Z-direction onto the XY plane.

[0009] Beneficial effects: By setting the annular groove to be circular, it is easier to process and form the annular groove, and it can ensure that the interaction force between the convex ring and the pole post is evenly distributed along the circumference of the pole post, avoiding the problem of local stress concentration, further preventing the convex ring from cracking and damaging, and ensuring the sealing and connection stability between the first plastic part and the pole post.

[0010] In one optional embodiment, the diameter of the first column segment is G, wherein the value of G ranges from 8 mm to 20 mm.

[0011] Beneficial effects: It can ensure that the first column has sufficient structural strength, thereby ensuring the reliability of the electrode and improving the safety of the battery cell. It can also avoid excessive weight of the electrode, which is conducive to improving the energy density of the battery cell and saving costs.

[0012] In one optional embodiment, the dimension of the annular groove along the Z direction is h, and the dimension of the first plastic part along the Z direction is H, wherein h and H satisfy the relationship: 1 / 3≤h / H≤2 / 3.

[0013] Beneficial effects: It can ensure that there is sufficient fitting height between the annular groove and the convex ring along the Z direction, improve the stability of the connection between the first plastic part and the electrode post, and make the convex ring have sufficient structural strength, thereby ensuring the airtightness between the first plastic part and the electrode post. It can also avoid excessive temperature difference between the upper and lower surfaces of the electrode post, ensure the accuracy of the temperature monitoring device set on the upper surface of the electrode post, and improve the safety of the battery cell.

[0014] In one optional embodiment, the dimension H of the first plastic part along the Z direction ranges from 3 mm to 8 mm.

[0015] Beneficial effects: It can ensure sufficient creepage distance between the terminal and the cover plate body, and ensure the insulation between the terminal and the cover plate body. It can also prevent the first plastic part from exceeding the upper surface of the terminal, thereby avoiding interference between the first plastic part and components such as busbars and temperature detection devices set on the upper surface of the terminal. This facilitates the arrangement of the battery cell in the battery pack and helps to ensure the volumetric energy density of the battery cell.

[0016] In one alternative embodiment, the cover plate assembly further includes a sealing ring fitted onto the column and located between the first plastic part and the base plate, with at least a portion of the sealing ring sandwiched between the cover plate body and the base plate.

[0017] Beneficial effect: Further ensures the sealing between the pole and the cover plate body.

[0018] In one alternative embodiment, the first plastic part is injection molded between the cover plate body and the pole post.

[0019] Beneficial effects: Injection molding is a relatively simple and easy-to-operate method with low cost. The first plastic part can fully fill the gap between the pole and the cover plate body. After the first plastic part solidifies, it is tightly connected to the pole and the cover plate body, which helps to ensure the sealing and insulation between the pole and the cover plate body and has high reliability.

[0020] Secondly, the present invention also provides a battery cell, comprising: a housing having an open end; an electrode assembly disposed within the inner cavity of the housing; and the aforementioned cover plate structure, the cover plate structure covering the open end of the housing. Since the battery cell includes the cover plate structure and has the same effect as the cover plate structure, it will not be described in detail here.

[0021] Thirdly, the present invention also provides a battery pack, comprising: the aforementioned battery cell. Since the battery pack includes the battery cell and has the same effects as the battery cell, it will not be described further here. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a cover plate assembly according to an embodiment of the present invention; Figure 3 for Figure 2 An exploded view of the cover plate assembly shown; Figure 4 for Figure 2 Top view of the cover plate assembly shown; Figure 5 for Figure 4 A cross-sectional view along the AA direction; Figure 6 for Figure 4 Cross-sectional view along the BB direction; Figure 7 for Figure 2 A structural schematic diagram of the cover plate assembly as shown from a bottom view; Figure 8 This is a schematic diagram of the structure of a pole post according to an embodiment of the present invention; Figure 9 for Figure 8 The front view of the pole column is shown; Figure 10 This is a schematic diagram of the structure of a first plastic part according to an embodiment of the present invention; Figure 11 for Figure 10 The diagram shows the structure of the first plastic part from a bottom-view perspective.

[0024] Explanation of reference numerals in the attached figures: 1. Cover plate body; 11. Pole post hole; 12. Injection hole; 13. Pressure relief hole; 14. Protrusion; 2. Pole post; 21. Post body; 211. Annular groove; 212. First post section; 213. Slotted section; 214. Second post section; 22. Base plate; 3. First plastic part; 31. Plastic part body; 311. Recessed part; 32. Raised ring; 4. Sealing ring; 5. Second plastic part; 51. Mounting hole; 6. Pressure relief valve; 7. Pressure relief valve patch; 8. Housing. Detailed Implementation

[0025] 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.

[0026] The battery cell mainly consists of a casing, a cover assembly, and electrode assemblies. The cover assembly covers the open end of the casing to form a sealed space for accommodating the electrode assemblies. The cover assembly includes a cover body, electrode posts, an upper plastic part, and a lower plastic part. The electrode posts pass through electrode post holes in the cover body, and the upper plastic part connects the electrode posts and the cover body to ensure the sealing and insulation between the electrode posts and the cover body. The electrode posts protrude from the surface of the cover body, and a busbar is usually welded to the side of the electrode posts facing away from the casing. The busbar is used to realize the electrical connection between battery cells or between the battery cells and external circuits. The upper plastic part is sleeved on the outer periphery of the terminal post. The connection stability between the plastic part and the terminal post is poor. When the battery cell is subjected to external forces during use, the bus and other structures will exert forces on the terminal post, making it easy for the terminal post and the plastic part to loosen. In particular, the force along the Z direction will pull the terminal post, causing the terminal post and the plastic part to move relative to each other. This will cause the plastic part to fall off the terminal post along the axial direction, affecting the airtightness and connection stability between the plastic part and the terminal post, and thus seriously affecting the safety of the battery cell.

[0027] The following is combined with Figures 1 to 11 The following describes embodiments of the present invention.

[0028] According to an embodiment of the present invention, a cover plate assembly is provided, comprising: a cover plate body 1, an electrode post 2, and a first plastic part 3. The cover plate body 1 has an electrode post hole 11; the electrode post 2 includes a column body 21 and a base plate 22, the column body 21 passing through the electrode post hole 11, and an annular groove 211 formed on the column body 21. The annular groove 211 is located at the middle of the column body 21 along the Z direction, and is arranged circumferentially along the column body 21 in the XY plane. A column segment on the side of the column body 21 located away from the base plate 22 from the annular groove 211 is a first column segment 212, and the first column segment 212 has a cross section in the XY plane... The cross-sectional area of ​​the column segment with an annular groove 211 on the column 21, with area S, in the XY plane is S1, where S and S1 satisfy the relationship: 0.15≤(S-S1) / S≤0.6; the first plastic part 3 includes a plastic part body 31 and a convex ring 32. The plastic part body 31 is annularly fitted on the column 21 and is connected to the cover plate body 1. The convex ring 32 is connected to the inner ring of the plastic part body 31 and is engaged with the annular groove 211. The units of S and S1 are both mm. 2The "middle position" mentioned is not the absolute midpoint. The middle position is a small area formed around the midpoint. This setting can achieve the locking and limiting of the annular groove 211 and the convex ring 32 along the Z direction, while taking into account different assembly and usage requirements. It is beneficial to reduce assembly requirements and improve the applicability and practicality of the battery cell.

[0029] It should be noted that the cover plate assembly has two perpendicular X, Y, and Z directions to form a Cartesian coordinate system. The X and Y directions intersect to form the XY plane. Here, the X direction refers to... Figures 1 to 2 The direction indicated by the middle arrow ("X") is the direction of the Y direction. Figures 1 to 2 The direction indicated by the middle arrow (Y) is the same as the direction indicated by the Z arrow (Z). Figures 1 to 2 The direction indicated by the middle arrow "Z" is specifically: the X direction is the length direction of the cover plate assembly, the Y direction is the width direction of the cover plate assembly, and the Z direction is the thickness direction of the cover plate assembly.

[0030] It should be noted that the axis of column 21 extends along the Z direction, and column 21 has an outer peripheral surface arranged around the axis. The annular groove 211 is formed by a recess in a part of the outer peripheral surface of column 21. The annular groove 211 is arranged around column 21. The column segment with the annular groove 211 is called the slotted segment 213. The upper end of the slotted segment 213 along the Z direction is lower than the upper end surface of column 21, and the lower end of the slotted segment 213 along the Z direction is higher than the lower end surface of column 21. The column segment on the side of column 21 located away from the bottom plate 22 of the slotted segment 213 is the first column segment 212. The column segment on column 21 located between the slotted segment 213 and the bottom plate 22 is the second column segment 214. The first column segment 212 and the second column segment 214 do not have the annular groove 211 and are the main body segments of column 21. The cross-sectional area of ​​the slotted segment 213 is smaller than the cross-sectional area of ​​the first column segment 212 and the second column segment 214. The plastic body 31 is annular and has an inner ring surface facing the column 21. The shape and size of the inner ring of the plastic body 31 are the same as the outline shape and size of the column segment on the column 21 without the annular groove 211 in the XY plane. At least a portion of the inner ring surface of the plastic body 31 along the Z direction is in contact with the outer peripheral surface of the first column segment 212. The convex ring 32 is formed by a portion of the inner peripheral surface of the plastic body 31 protruding radially along the column 21. The outer ring of the convex ring 32 coincides with the inner ring of the plastic body 31. The inner ring size of the convex ring 32 is smaller than the inner ring size of the plastic body 31. The convex ring 32 is inserted into the annular groove 211 to achieve axial positioning between the first plastic part 3 and the pole post 2.

[0031] The annular groove 211 has a bottom surface in the XY plane near the axis of the column, and two sidewalls opposite each other along the Z direction. The inner surface of the convex ring 32 is in contact with the bottom surface of the groove, and the upper and lower surfaces of the convex ring 32 along the Z direction are in contact with one sidewall of the groove. S-S1 is equal to the area of ​​the annular groove 211 in the XY plane, which is the contact area in the XY plane between the pole post 2 and the first plastic part 3. When the first plastic part 3 is an injection molded part, S-S1 is the injection area reserved on the pole post 2 for the injection molded part, which is equal to the cross-sectional area of ​​the convex ring 32 in the XY plane. S1 is the cross-sectional area of ​​the remaining solid part in the XY plane after the annular groove 211 is opened on the column 21.

[0032] It should be noted that the first plastic part 3 restricts the movement of the pole post 2 relative to the first plastic part 3 in the Z direction through the snap-fit ​​engagement between the convex ring 32 and the annular groove 211. In the XY plane, the ratio K = (S-S1) / S of the cross-sectional area of ​​the annular groove 211 to the cross-sectional area of ​​the first column segment 212 is less than 0.15. If K is too small relative to the cross-sectional area of ​​the annular groove 211, the engagement area between the convex ring 32 and the annular groove 211 in the XY plane is insufficient. The convex ring 32 is prone to dislodging from the annular groove 211 when subjected to external forces, making it difficult to play an effective limiting role. The airtightness between the first plastic part 3 and the pole post 2 is compromised. Damage may occur, even leading to cracking and damage to the first plastic part 3. If K is greater than 0.6, the cross-sectional area of ​​the annular groove 211 will be too large relative to the cross-sectional area of ​​the first column segment 212. After the annular groove 211 is opened on the column 21, the cross-sectional area of ​​the remaining solid part in the XY plane will be too small, resulting in excessive resistance and temperature rise of the slotted segment 213. This leads to an excessive temperature difference between the upper and lower surfaces of the electrode post 2 during normal charging and discharging of the battery cell. A temperature acquisition device is installed on the upper surface of the electrode post 2 to collect the temperature of the battery cell for temperature monitoring. If the temperature difference between the upper and lower surfaces of the electrode post 2 is too large, the temperature monitoring will be inaccurate, which is not conducive to ensuring the safety of the battery cell. Here, the upper surface refers to the upper surface along the Z direction, that is, the surface away from the housing 8 along the Z direction, and the lower surface refers to the lower surface along the Z direction, that is, the surface facing the inner cavity of the housing 8 along the Z direction.

[0033] In the cover plate assembly of this embodiment, an annular groove 211 is formed on the outer peripheral surface of the pole post 2. A first plastic part 3 is connected around the outer peripheral side of the pole post 2, and a protruding ring 32 is provided on the first plastic part 3. The convex ring 32 and the annular groove 211 engage with each other to limit the axial positioning between the first plastic part 3 and the pole post 2. At the same time, by limiting the ratio between the cross-sectional area of ​​the annular groove 211 and the cross-sectional area of ​​the first column segment 212 in the XY plane to be within the range of 0.15 to 0.6, the engagement area between the protruding ring 32 and the pole post 2 is equal to the cross-sectional area of ​​the first column segment 212. The reasonable ratio between the areas can prevent the convex ring 32 from coming out of the annular groove 211, ensuring the stability and reliability of the connection between the pole post 2 and the first plastic part 3, ensuring the airtightness between the first plastic part 3 and the pole post 2, and preventing the first plastic part 3 from cracking and being damaged. It can also prevent the cross-sectional area of ​​the annular groove 211 from being too large, which would lead to excessive resistance of the column segment with the annular groove 211, thereby preventing excessive temperature difference between the upper and lower surfaces of the pole post 2, ensuring the accuracy of the temperature acquisition device on the upper surface of the pole post in acquiring the pole post temperature, and helping to improve the safety of the battery cell.

[0034] Optionally, the value of (S-S1) / S is any one of 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6 or a value between any two values.

[0035] It should be noted that the base plate 22 of the pole post 2 is connected to the lower end of the pole body 21 along the Z direction, and the base plate 22 is located on the lower side of the cover plate body 1. Here, "lower end" refers to the lower end along the Z direction, that is, the end of the cover plate assembly facing the inner cavity of the housing 8 along the Z direction after assembly; "lower side" refers to the lower side along the Z direction, that is, the side facing the inner cavity of the housing along the Z direction. The dividing line between the base plate 22 and the pole body 21 is as follows: Figure 6 As shown by the dashed line; the pole hole 11 is a through hole that penetrates the cover plate body 1 along the Z direction. The cross-sectional dimension of the base plate 22 in the XY plane is larger than the opening size of the pole hole 11, ensuring that the base plate 22 will not pass through the pole hole 11. The base plate 22 cooperates with the first plastic part 3 to realize the axial positioning of the pole 2.

[0036] In one embodiment, the orthographic projection of the column 21 along the Z direction in the XY plane is circular. The first column segment 212 of the column 21 and the second column segment 214 are both circular in their orthographic projections along the Z direction in the XY plane. Before the annular groove 211 is formed, the column 21 is cylindrical, which is simple in structure, easy to process and shape, and facilitates the smooth assembly process.

[0037] In one embodiment, the orthographic projection of the annular groove 211 along the Z direction in the XY plane is circular. The orthographic projection of the slotted section 213 along the Z direction in the XY plane is circular. By setting the annular groove 211 to be circular, it is easier to process and shape the annular groove 211, and it can ensure that the interaction force between the convex ring 32 and the pole post 2 is evenly distributed along the circumference of the pole post, avoiding the problem of local stress concentration, further preventing the convex ring 32 from cracking and being damaged, and ensuring the sealing and connection stability between the first plastic part 3 and the pole post 2.

[0038] It should be noted that the cross-sectional area of ​​the first column segment 212 in the XY plane is circular, with a diameter of G. Therefore, S = π × (G / 2). 2 The grooved section 213 of the column 21 with an annular groove 211 has a circular cross-sectional area in the XY plane with a diameter of g, where g < G. Then S1 = π × (g / 2). 2 The cross-sectional area (i.e., injection area) of the annular groove 211 is S2 = S - S1 = π × (G / 2). 2 -π×(g / 2) 2 .

[0039] In one embodiment, the diameter of the first post segment 212 is G, where the value of G ranges from 8 mm to 20 mm. If G is less than 8 mm, the diameter of the first post segment 212 is too small, resulting in insufficient structural strength and susceptibility to deformation and damage during use. If G is greater than 20 mm, the diameter of the first post segment 212 is too large, leading to excessive weight of the electrode post 2, which is detrimental to achieving lightweighting of the battery cell and improving its energy density, while also increasing costs. Therefore, by limiting G to a value within the range of 8 mm to 20 mm, it is possible to ensure that the first post segment 212 has sufficient structural strength, thereby guaranteeing the reliability of the electrode post 2 and improving the safety of the battery cell. Simultaneously, it is possible to avoid excessive weight of the electrode post 2, which is beneficial for improving the energy density of the battery cell and saving costs.

[0040] Optionally, the value of G is any one of 8 mm, 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, or a value between any two of these values.

[0041] In one embodiment, the diameter of the second column segment 214 is equal to the diameter of the first column segment 212, which facilitates the processing and forming of the column body 21. The first column segment 212, the slotted segment 213, and the second column segment 214 are fixedly connected in sequence, and the dividing line between the first column segment 212, the slotted segment 213, and the second column segment 214 is as follows: Figure 6 As shown by the dashed line in the image.

[0042] In other embodiments, the orthographic projection of the column 21 along the Z direction in the XY plane can also be a racetrack shape or a polygon such as a triangle or quadrilateral. The annular groove can also be a non-circular ring. It is only necessary to ensure that the ratio between the cross-sectional area of ​​the annular groove 211 in the XY plane and the cross-sectional area of ​​the column segment on the column 21 without the annular groove 211 is within the range of 0.15 to 0.6.

[0043] In one embodiment, the dimension of the annular groove 211 along the Z direction is h, and the dimension of the first plastic part 3 along the Z direction is H, wherein h and H satisfy the relationship: 1 / 3 ≤ h / H ≤ 2 / 3. It should be noted that the dimension of the convex ring 32 along the Z direction is equal to the dimension of the annular groove 211 along the Z direction. If h / H is less than 1 / 3, then the dimension of the annular groove 211 along the Z direction relative to the first plastic part 3 is too small, that is, the dimension of the convex ring 32 along the Z direction relative to the dimension of the first plastic part 3 along the Z direction is too small. The fitting height between the convex ring 32 and the annular groove 211 is insufficient, and the structural strength of the convex ring 32 is insufficient, making it prone to deformation or cracking during use, or even detachment from the annular groove 211. This makes it difficult to effectively perform the limiting function, causing relative misalignment between the first plastic part 3 and the pole post 2. Looseness makes it difficult to ensure the airtightness between the first plastic part 3 and the terminal post 2; h is the groove height on the terminal post 2. The groove height affects the temperature of the upper and lower surfaces of the terminal post 2 during normal charging and discharging of the battery cell. If h / H is greater than 2 / 3, the size of the annular groove 211 along the Z direction is too large, and the groove height is too large, that is, the height of the groove section 213 with a small cross-sectional area is too large. This results in an excessive temperature difference between the upper and lower surfaces of the terminal post 2 during normal charging and discharging of the battery. Consequently, the temperature collected by the temperature acquisition device set on the upper surface of the terminal post 2 is inaccurate, which is not conducive to ensuring the safety of the battery cell.

[0044] Therefore, by limiting h / H to a value within the range of 1 / 3 to 2 / 3, it is possible to ensure that the annular groove 211 and the convex ring 32 have sufficient mating height along the Z direction, thereby improving the stability of the connection between the first plastic part 3 and the electrode post 2, and ensuring that the convex ring 32 has sufficient structural strength to guarantee the airtightness between the first plastic part 3 and the electrode post 2. At the same time, it is possible to avoid excessive temperature difference between the upper and lower surfaces of the electrode post 2, ensuring the accuracy of the temperature monitoring device installed on the upper surface of the electrode post 2, and improving the safety of the battery cell.

[0045] Optionally, the value of h / H is any one of 1 / 3, 2 / 5, 1 / 2, 3 / 5, 2 / 3, or a value between any two of these values.

[0046] In one embodiment, the dimension H of the first plastic part 3 along the Z direction ranges from 3 mm to 8 mm. It should be noted that H is the distance along the Z direction between the upper and lower surfaces of the first plastic part 3. The first plastic part 3 wraps around the outer periphery of the column 21, with its upper surface higher than the upper surface of the cover plate body 1 but not higher than the upper surface of the column 21, to ensure insulation between the electrode post 2 and the cover plate body 1. If H is less than 3 mm, the height of the first plastic part 3 along the Z direction is too low, resulting in insufficient creepage distance between the electrode post 2 and the cover plate body 1, which can easily lead to short circuits and seriously affect the safety of the battery cell. If H is greater than 8 mm, the height of the first plastic part 3 along the Z direction is too large, with its upper surface higher than the upper surface of the electrode post 2. This causes interference between the first plastic part 3 and the busbars, temperature detection devices, etc., located on the upper surface of the electrode post 2, and also results in an excessively large overall distance along the Z direction for the battery cell, which is detrimental to improving the volumetric energy density of the battery cell.

[0047] Therefore, by limiting H to a value within the range of 3 mm to 8 mm, the first plastic part 3 has a reasonable height, which can ensure sufficient creepage distance between the terminal post 2 and the cover plate body 1, ensuring the insulation between the terminal post 2 and the cover plate body 1, and also prevent the first plastic part 3 from exceeding the upper surface of the terminal post 2. This avoids interference between the first plastic part 3 and components such as the busbar and temperature detection device set on the upper surface of the terminal post 2, which facilitates the arrangement of the battery cell in the battery pack and helps to ensure the volumetric energy density of the battery cell.

[0048] Optionally, the value of H is any one of 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, or a value between any two of these values.

[0049] In one embodiment, the cover plate assembly further includes a sealing ring 4, which is sleeved on the post 21 and located between the first plastic part 3 and the base plate 22. At least a portion of the sealing ring 4 is sandwiched between the cover plate body 1 and the base plate 22. The lower surface of the sealing ring 4 abuts against the upper surface of the base plate 22, and the sealing ring 4 is press-fitted between the cover plate body 1 and the base plate 22 to further ensure the sealing between the post 2 and the cover plate body 1.

[0050] In one embodiment, the electrode post 2 and the cover plate body 1 are spaced apart, and the first plastic part 3 is injection molded between the cover plate body 1 and the electrode post 2. The injection molding method is relatively simple, easy to operate, and low in cost. Moreover, the first plastic part 3 can fully fill the gap between the electrode post 2 and the cover plate body 1. After the first plastic part 3 solidifies, it is tightly connected to the electrode post 2 and the cover plate body 1, which helps to ensure the sealing and insulation between the electrode post 2 and the cover plate body 1, resulting in high reliability.

[0051] In one embodiment, the dimension of the electrode post 2 along the Z direction is h0, where the value of h0 ranges from 5 mm to 10 mm. It should be noted that h0 is the distance between the upper and lower surfaces of the electrode post 2 along the Z direction. By limiting the dimension h0 of the electrode post 2 along the Z direction to a reasonable range, the electrode post 2 has a reasonable height along the Z direction. This ensures sufficient structural strength while preventing excessive weight, thereby improving the reliability of the cover plate assembly and the energy density of the battery cell.

[0052] Optionally, the value of h0 is any one of 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or a value between any two of these values.

[0053] In one embodiment, the base plate 22 has a dimension of 1 mm to 2 mm along the Z direction. This ensures sufficient structural strength for the base plate 22, preventing deformation during use and thus guaranteeing the seal between the electrode post 2 and the cover plate body 1, improving the reliability and safety of the battery cell. It also avoids the base plate 22 occupying excessive internal space in the battery cell along the Z direction, thereby contributing to increased energy density. It should be noted that the base plate 22 is fixedly connected to the post 21.

[0054] In one embodiment, the upper surface of the cover plate body 1 is further provided with a circumferentially arranged protrusion 14 surrounding the pole hole 11, and the protrusion 14 is spaced apart from the pole hole 11 in the XY plane; the lower surface of the plastic body 31 of the first plastic part 3 has a recess 311 corresponding to the protrusion 14, and the protrusion 14 is inserted into the recess 311, increasing the connection area between the cover plate body 1 and the first plastic part 3, and further improving the connection stability between the two.

[0055] In one embodiment, the orthographic projection of the protrusion 14 in the XY plane is an annular shape, and the recess 311 is an annular groove, which facilitates processing and assembly.

[0056] In other embodiments, the protrusions 14 may be a plurality of protrusions spaced apart circumferentially along the pole hole 11, and the number of recesses 311 is equal to the number of protrusions 14 and corresponds one-to-one, which can realize circumferential positioning between the first plastic part 3 and the cover plate body 1, and further improve the connection reliability between the first plastic part 3 and the cover plate body 1.

[0057] In one embodiment, the cover plate assembly further includes a second plastic part 5, which is disposed on the lower side of the cover plate body 1 and fits against the lower surface of the cover plate body 1 to ensure insulation between the cover plate body 1 and the electrode assembly. The second plastic part 5 has a mounting hole 51 for the post 21 to pass through, and the second plastic part 5 extends around the circumferential edge of the mounting hole 51 between the cover plate body 1 and the base plate 22 to further ensure insulation between the post 2 and the cover plate body 1.

[0058] Specifically, the first plastic part 3 is the upper plastic, and the second plastic part 5 is the lower plastic.

[0059] In one embodiment, the cover plate body 1 is further provided with an injection hole 12, which extends through the cover plate body 1 in the Z direction for injecting electrolyte into the battery cell. When it is not necessary to inject electrolyte into the battery cell, the injection hole 12 is sealed by a sealing plug.

[0060] In one embodiment, the cover plate body 1 is further provided with a pressure relief hole 13, and the cover plate assembly also includes a pressure relief valve 6, which is installed in the pressure relief hole 13. The pressure relief valve 6 is adapted to open when the gas pressure inside the battery cell reaches a preset value to release the gas inside the battery cell and prevent the battery cell from exploding. A pressure relief valve patch 7 is attached to the upper side of the pressure relief hole 13 to protect the pressure relief valve 6.

[0061] According to an embodiment of the present invention, in another aspect, a battery cell is also provided, such as... Figure 1 As shown, the battery cell includes: a housing 8, an electrode assembly, and the aforementioned cover plate assembly. The housing 8 has an open end; the electrode assembly is placed in the inner cavity of the housing 8; the cover plate assembly covers the open end of the housing 8. The electrode assembly includes an electrode assembly body and a tab, the tab being connected to one end of the electrode assembly body along the Z direction, and the tab being electrically connected to a terminal post in the cover plate assembly. Optionally, the battery cell is a lithium-ion battery cell.

[0062] According to an embodiment of the present invention, in another aspect, a battery pack is also provided, including the aforementioned battery cells. The battery pack further includes a housing, in which the battery cells are placed. Optionally, the number of battery cells is multiple.

[0063] The following examples and comparative examples verify the impact of different parameter values ​​on the cover plate assembly. The parameter settings for the examples and comparative examples are shown in Table 1, and the corresponding verification results are shown in Table 2. The test items are as follows: 1. Thrust test of pole performance: 1) Perform a Z-direction ultimate thrust test on the pole post, requiring the Z-direction ultimate thrust of the pole post to be greater than 1500N; 2) Perform thrust tests on the pole in the X / Y / Z directions. The pole must be able to withstand a force of 1000 N / 10 cycles in each of the X / Y / Z directions. After the thrust test, the first plastic part should not crack, and the airtightness should meet the requirements (leakage rate < 1 × 10⁻⁷ / Pa.m). 3 / s); If both of the above tests are passed, the pole piece performance meets the requirements; if at least one of the above tests is failed, the pole piece performance does not meet the requirements.

[0064] 2. Temperature rise: Simulation analysis of the temperature difference between the upper and lower surfaces of the terminals during constant current and constant voltage charging and discharging of a battery is required, with the temperature rise difference between the upper and lower surfaces required to be within 5℃. The temperature rise difference refers to the difference between the temperature rise of the upper and lower surfaces of the terminals after charging and discharging; assuming that the temperatures of the upper and lower surfaces of the terminals are the same before charging and discharging, the temperature rise difference is equal to the temperature difference between the upper and lower surfaces of the terminals after charging and discharging.

[0065] Table 1

[0066] Table 2

[0067] In Table 1, K = (S-S1) / S; in Table 2, OK indicates qualified and NG indicates unqualified.

[0068] As can be seen from Tables 1 to 2, for the cover plate assemblies of Examples 1 to 12, all parameters are within the range defined in this application, meet the requirements of the pole thrust test, and the temperature rise difference between the upper and lower surfaces of the pole does not exceed 5°C, which meets the requirements. The cover plate assemblies are qualified and have good performance.

[0069] For the cover plate assemblies of Comparative Examples 1 and 2, the values ​​of K are 0.138 and 0.147, respectively, which are less than the lower limit of (S-S1) / S of 0.15 defined in this application and are not within the range defined in this application. Although the temperature rise difference between the upper and lower surfaces of the pole does not exceed 5°C, it does not meet the pole thrust test requirements and is therefore unqualified. For the cover plate assemblies of Comparative Examples 3 and 4, the values ​​of K are 0.609 and 0.649, respectively, which are greater than the upper limit of (S-S1) / S of 0.6 defined in this application and are not within the range defined in this application. Although they meet the pole thrust test requirements, the temperature rise difference between the upper and lower surfaces of the pole is greater than 5°C, which is not acceptable. It can be seen that when (S-S1) / S is within the range of 0.15 to 0.6 defined in this application, the pole can meet the thrust test requirements, and the temperature rise difference between the upper and lower surfaces of the pole does not exceed 5°C, ensuring the connection stability between the pole 2 and the first plastic part 3 and the accuracy of temperature acquisition.

[0070] For the cover plate assemblies of Comparative Examples 5 and 6, the h / H values ​​are 0.323 and 0.302, respectively, both less than 1 / 3 of the lower limit of h / H defined in this application, and outside the range defined in this application. Therefore, they do not meet the requirements for the pole thrust test and are unqualified. For the cover plate assemblies of Comparative Examples 7 and 8, the h / H values ​​are 0.681 and 0.850, respectively, greater than 2 / 3 of the upper limit of h / H defined in this application, and outside the range defined in this application. The temperature rise difference between the upper and lower surfaces of the pole is greater than 5℃, which does not meet the requirements. It can be seen that when h / H is within the range of 1 / 3 to 2 / 3 defined in this application, the pole can meet the thrust test requirements, and the temperature rise difference between the upper and lower surfaces of the pole does not exceed 5℃, ensuring the connection stability between the pole 2 and the first plastic part 3 and the accuracy of temperature acquisition.

[0071] It should be noted that the terminal performance thrust test is a routine test to verify the reliability of the connection between the terminal and the cover plate body and the first plastic part, as well as the ability to resist mechanical loads. It is mainly used to evaluate the pull-out strength and anti-detachment performance of the terminal, and to ensure that the battery does not experience problems such as terminal loosening or sealing failure during assembly, transportation and use.

[0072] Unless otherwise stated, the values ​​of all parameters mentioned in this application can be determined using testing methods commonly used in the art. Unless otherwise stated, the test temperature for all parameters is 25°C.

[0073] 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, characterized in that, include: The cover plate body has pole hole; An electrode post includes a column body and a base plate. The column body passes through the electrode post hole. An annular groove is formed on the column body. The annular groove is located at the middle of the column body along the Z direction and is arranged circumferentially along the column body in the XY plane. The column segment on the side of the column body located away from the base plate from the annular groove is a first column segment. The cross-sectional area of ​​the first column segment in the XY plane is S. The cross-sectional area of ​​the column segment with the annular groove in the XY plane is S1. S and S1 satisfy the relationship: 0.15≤(S-S1) / S≤0.

6. The first plastic part includes a plastic part body and a convex ring. The plastic part body is ring-shaped and sleeved on the column body. The plastic part body is connected to the cover plate body. The convex ring is connected to the inner ring of the plastic part body and is engaged with the annular groove.

2. The cover plate assembly according to claim 1, characterized in that, The orthographic projection of the cylinder along the Z direction in the XY plane is circular.

3. The cover plate assembly according to claim 2, characterized in that, The annular groove's orthographic projection along the Z-direction in the XY plane is circular.

4. The cover plate assembly according to claim 3, characterized in that, The diameter of the first column segment is G, where the value of G ranges from 8 mm to 20 mm.

5. The cover plate assembly according to claim 1, characterized in that, The dimension of the annular groove along the Z direction is h, and the dimension of the first plastic part along the Z direction is H, wherein h and H satisfy the relationship: 1 / 3≤h / H≤2 / 3.

6. The cover plate assembly according to claim 1, characterized in that, The dimension H of the first plastic part along the Z direction ranges from 3 mm to 8 mm.

7. The cover plate assembly according to claim 1, characterized in that, The cover plate assembly also includes a sealing ring, which is sleeved on the column and located between the first plastic part and the base plate, with at least a portion of the sealing ring sandwiched between the cover plate body and the base plate.

8. The cover plate assembly according to any one of claims 1 to 7, characterized in that, The first plastic part is injection molded between the cover plate body and the pole post.

9. A battery cell, characterized in that, include: The shell has an open end; The electrode assembly is placed inside the cavity of the housing; The cover assembly according to any one of claims 1 to 8, wherein the cover assembly covers the opening end of the housing.

10. A battery pack, characterized in that, include: The battery cell according to claim 9.

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