Cover plate assembly and battery cell

Abstract

The application relates to the technical field of batteries and discloses a cover plate assembly and a battery cell. The cover plate assembly comprises a cover plate body provided with a pole hole, one side of the cover plate body along the Z direction is formed into a first surface, a reinforcing ring is arranged on the first surface, the reinforcing ring is arranged around the circumference of the pole hole, the reinforcing ring is formed by protruding from part of the first surface along the Z direction, and the ring width of the reinforcing ring in the XY plane is a; the pole comprises a pole body, the pole body is arranged in the pole hole; a first plastic part is injection molded between the pole body and the cover plate body, the first plastic part is annular and is sleeved on the pole body, at least part of the first plastic part is attached to the first surface, one side of the first plastic part facing the cover plate body is provided with a groove corresponding to the reinforcing ring, the reinforcing ring is embedded in the groove, and the ring width of the first plastic part in the XY plane is A, wherein the relationship between A and a satisfies the formula: 0.1 <= a / A <= 0.5. The problem that the first plastic part is prone to failure under external force is solved.

Description

Technical Field

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

[0002] The cover plate assembly is a crucial component of the battery cell. It includes a cover plate body, terminals, a first plastic component, and a second plastic component. The cover plate body is fitted over the opening of the housing and welded to it. The terminals pass through terminals in the terminals on the cover plate body. The first and second plastic components are located on opposite sides of the cover plate body along its height, with the first plastic component injection-molded between the terminals and the cover plate body. At least a portion of the first plastic component connects the cover plate body and the terminals to ensure insulation between them and to achieve relative fixation. However, during battery cell use, the terminals are also connected to structures such as busbars. These busbars connect different battery cells or connect the battery cell to an external circuit. External forces act on the terminals through the busbars and are transmitted to the first plastic component. In the prior art, the connection strength between the first plastic component and the cover plate body is low, and the first plastic component is prone to connection failure under external forces, seriously affecting the safety of the battery cell. Summary of the Invention

[0003] The present invention provides a cover plate assembly and a battery cell to solve the problem of low connection strength between the first plastic part and the cover plate body.

[0004] In a first aspect, the present invention provides a cover plate assembly, comprising: a cover plate body having an electrode post hole, the cover plate body forming a first surface along the Z direction, a reinforcing ring being disposed on the first surface, the reinforcing ring being circumferentially arranged around the electrode post hole, and the reinforcing ring being formed by a portion of the first surface protruding along the Z direction, the reinforcing ring having a ring width of a in the XY plane; an electrode post including a column body, the column body being inserted into the electrode post hole; a first plastic part being injection molded between the column body and the cover plate body, the first plastic part being annular and sleeved on the column body, and at least a portion of the first plastic part being in contact with the first surface, the first plastic part having a groove corresponding to the reinforcing ring on the side facing the cover plate body, the reinforcing ring being embedded in the groove, the first plastic part having a ring width of A in the XY plane, wherein A and a satisfy the relationship: 0.1≤a / A≤0.5.

[0005] Beneficial effects: By injection molding a first plastic part between the electrode post and the cover plate body, the first plastic part connects to both the electrode post and the cover plate body, achieving relative fixation between them. The first plastic part fully fills the gap between the electrode post and the cover plate body, ensuring a tight seal and insulation between them. A reinforcing ring is provided on the first surface of the cover plate body, and a corresponding groove is formed on the first plastic part, with the reinforcing ring inserted into the groove. This results in a non-planar contact surface between the cover plate body and the first plastic part, increasing the contact area and strengthening the connection between them. Furthermore, by limiting the width of the reinforcing ring... The ratio a / A between the reinforcing ring and the ring width A of the first plastic component is taken in the range of 0.1 to 0.5. This ensures that the reinforcing ring has sufficient structural strength, providing sufficient connection strength between the first plastic component and the cover plate body. This allows the reinforcing ring and the first plastic component to withstand large temporary external forces under extreme working conditions, thus enabling the cover plate assembly to meet the terminal ultimate torsional strength requirements. At the same time, it avoids the first plastic component's structural strength being too poor due to an excessively large ring width, ensuring that the first plastic component has sufficient structural strength and will not experience fatigue failure during long-term use of the battery cell. This meets the terminal fatigue torsional strength requirements, thereby ensuring the reliability and airtightness of the cover plate assembly and guaranteeing the safety of the battery cell.

[0006] In one optional embodiment, the circumference width A of the first plastic part in the XY plane is in the range of 3 mm ≤ A ≤ 8 mm.

[0007] Beneficial effects: It can ensure that the first plastic part has sufficient structural strength, thereby avoiding cracking and failure of the first plastic part during use, ensuring the airtightness of the cover plate assembly, avoiding the problem of the first plastic part loosening and causing the terminal to fall off, avoiding material waste, saving production costs, and avoiding the first plastic part from excessively affecting the heat dissipation of the terminal, thereby avoiding excessive temperature rise of the terminal and improving the safety of the battery cell.

[0008] In one optional embodiment, the height of the reinforcing ring along the Z direction is h, and the distance between the upper surface of the first plastic part and the first surface along the Z direction is H, wherein h and H satisfy the relationship: 0.15≤h / H≤0.85.

[0009] Beneficial effects: It can ensure that the reinforcing ring has sufficient structural strength, so that the connection between the first plastic part and the cover plate body is sufficient, thereby ensuring that the reinforcing ring and the first plastic part can withstand large temporary external forces, thus enabling the cover plate assembly to meet the terminal ultimate torque strength requirements. It can also avoid the reinforcing ring protrusion height being too large, which would cause the remaining solid part of the first plastic part in the Z direction to be too thin after the groove is made, thus ensuring that the first plastic part has sufficient structural strength, so that the first plastic part will not suffer fatigue failure during the long-term use of the battery cell, meeting the terminal fatigue torque strength requirements, thereby ensuring the reliability and airtightness of the cover plate assembly, and ensuring the safety of the battery cell.

[0010] In one optional embodiment, the distance H between the upper surface of the first plastic part and the first surface along the Z direction is in the range of 2 mm ≤ H ≤ 5 mm.

[0011] Beneficial effects: It can ensure that the first plastic part has sufficient structural strength, avoid cracking and failure during use, ensure the airtightness of the cover assembly, avoid the problem of the first plastic part loosening and causing the terminal to fall off, avoid wasting materials, save production costs, and avoid the first plastic part interfering with the busbar and other structures that need to be connected on the terminal, which facilitates the layout of the cells in the battery pack.

[0012] In one alternative embodiment, in the XY plane, the distance between the outer ring of the reinforcing ring and the outer ring of the first plastic part is L, where L ≥ 0.3 mm.

[0013] Beneficial effects: It ensures that the solid part of the first plastic part wrapped around the outer ring of the reinforcing ring has sufficient structural strength, avoids deformation or cracking of the first plastic part during the use of the battery cell, thereby further ensuring the connection strength between the first plastic part and the cover plate body, ensuring the airtightness between the terminal post and the cover plate body of the cover plate assembly, and improving the reliability of the cover plate assembly.

[0014] In one optional embodiment, the column has a first axis extending along the Z direction and an outer peripheral surface surrounding the first axis, and a limiting groove is formed on the outer peripheral surface of the column; the first plastic part includes a plastic part body and a protrusion, the plastic part body is annular, the protrusion is connected to the inner ring of the plastic part body, and the protrusion is inserted into the limiting groove.

[0015] Beneficial effects: By opening a limiting groove on the outer circumference of the column and setting a plastic part body including a plastic part body and a protrusion connected to the inner ring of the plastic part body, and the protrusion is inserted into the limiting groove, the first plastic part and the column body are mutually limited through the insertion and cooperation of the protrusion and the limiting groove, the first plastic part is prevented from slipping off the pole in the Z direction, the connection strength between the first plastic part and the pole is further increased, the problem of pole loosening is avoided, and the airtightness of the cover plate assembly is guaranteed.

[0016] In one optional embodiment, the recess depth of the limiting groove in the XY plane is W, wherein the value of W ranges from 0.3 mm to W to 2.0 mm.

[0017] Beneficial effects: It can ensure that the limiting groove and the protrusion on the first plastic part have sufficient radial fitting dimensions, ensuring the injection molding strength of the protrusion, so that the protrusion and the limiting groove can play an effective limiting role after fitting, ensuring the reliability of the connection between the first plastic part and the electrode post. It can also avoid the setting of the limiting groove from having too much impact on the current carrying capacity of the electrode post, thereby avoiding excessive temperature rise of the electrode post during the charging and discharging process of the battery cell, avoiding excessive temperature difference between the upper and lower surfaces of the electrode post, ensuring the accuracy of the temperature collected by the temperature acquisition device set on the upper surface of the electrode post, and helping to improve the safety of the battery cell.

[0018] In one optional embodiment, the height of the limiting groove along the Z direction is h1, wherein the value of h1 is in the range of 1.0 mm ≤ h1 ≤ 5.0 mm.

[0019] Beneficial effects: It can avoid excessive temperature difference between the upper and lower surfaces of the electrode post, ensuring the accuracy of temperature monitoring of the electrode post by the temperature detection device set on the upper surface of the electrode post. It can also ensure that the limiting groove provides sufficient fitting height for the protrusion of the first plastic part, ensuring that the protrusion has sufficient structural strength and preventing the protrusion from coming out of the limiting groove, thereby improving the stability of the connection between the first plastic part and the electrode post, thus ensuring the airtightness between the two and improving the safety of the battery cell.

[0020] In one alternative embodiment, the cover plate assembly further includes a sealing ring fitted onto the column and located on the lower side of the first plastic part along the Z direction.

[0021] Beneficial effect: Further ensures the sealing between the pole and the cover plate body.

[0022] 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 assembly covering the open end of the housing. Since the battery cell includes the cover plate assembly and has the same effect as the cover plate assembly, it will not be described in detail here. Attached Figure Description

[0023] 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.

[0024] Figure 1 This is a schematic diagram of the structure of a cover plate assembly according to an embodiment of the present invention;

[0025] Figure 2 for Figure 1 An exploded view of the cover plate assembly shown;

[0026] Figure 3 for Figure 1 Top view of the cover plate assembly shown;

[0027] Figure 4 for Figure 3 Cross-sectional view along the BB direction;

[0028] Figure 5 for Figure 3 A cross-sectional view along the CC direction;

[0029] Figure 6 for Figure 1 A structural schematic diagram of the cover plate assembly as shown from a bottom view;

[0030] Figure 7 This is a schematic diagram of the structure of a cover plate body according to an embodiment of the present invention;

[0031] Figure 8 for Figure 7 A magnified view of part of E in the diagram;

[0032] Figure 9 This is a schematic diagram of the structure of a pole post according to an embodiment of the present invention;

[0033] Figure 10 for Figure 9 The front view of the pole column is shown;

[0034] Figure 11 This is a schematic diagram of the structure of a first plastic part according to an embodiment of the present invention;

[0035] Figure 12 for Figure 11 A structural schematic diagram of the first plastic part shown from a bottom-view perspective;

[0036] Figure 13 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention;

[0037] Figure 14 for Figure 13 The diagram shown is an exploded view of the battery cell.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1. Cover plate body; 101. Pole post hole; 102. Injection hole; 103. Pressure relief hole; 11. First surface; 12. Reinforcing ring; 2. Pole post; 21. Column body; 211. Limiting groove; 22. Base plate; 3. First plastic part; 301. Groove; 31. Plastic part body; 32. Protrusion; 4. Sealing ring; 5. Second plastic part; 51. Mounting hole; 6. Pressure relief valve; 7. Pressure relief valve patch; 8. Housing; 9. Pole assembly. Detailed Implementation

[0040] 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.

[0041] The cover plate assembly is an important component of the battery cell. The cover plate assembly includes a cover plate body, a terminal post, a first plastic part, a second plastic part, etc. The cover plate body is covered on the opening end of the housing and welded to the housing. The terminal post is inserted into the terminal post hole on the cover plate body. The first plastic part and the second plastic part are respectively disposed on both sides of the cover plate body along its height direction. The first plastic part is injection molded between the terminal post and the cover plate body. At least a part of the first plastic part is connected between the cover plate body and the terminal post to ensure the insulation between the terminal post and the cover plate body, and at the same time to achieve relative fixation between the terminal post and the cover plate body. However, during the use of the battery cell, the terminal post is also connected to structures such as busbars. The busbars are used to connect different battery cells or between the battery cell and an external circuit. External forces act on the terminal post through the busbars and are transmitted to the first plastic part. In the prior art, the contact surface between the first plastic part and the cover plate body is a plane, and the connection strength between the first plastic part and the cover plate body is low. The first plastic part is prone to failure in connection with the cover plate body under external force. In addition, under external force, problems such as cracking of the first plastic part, damage to the airtightness of the cover plate assembly, and relative loosening between the terminal post and the first plastic part may occur, which seriously affect the safety of the battery cell.

[0042] The following is combined Figures 1 to 14 The following describes embodiments of the present invention.

[0043] According to embodiments of the present invention, in one aspect, a cover plate assembly is provided, such as... Figures 1 to 12As shown, the cover plate assembly includes: 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 101. A first surface 11 is formed on one side of the cover plate body 1 along the Z direction. A reinforcing ring 12 is provided on the first surface 11, surrounding the electrode post hole 101 circumferentially. The reinforcing ring 12 is formed by a portion of the first surface 11 protruding along the Z direction, and the ring width of the reinforcing ring 12 in the XY plane is a. The electrode post 2 includes a column 21, which passes through the electrode post hole 101. The first plastic part 3 is injection molded onto the column. Between the 21 and the cover plate body 1, the first plastic part 3 is ring-shaped and sleeved on the column 21, and at least a part of the first plastic part 3 is in contact with the first surface 11. The side of the first plastic part 3 facing the cover plate body 1 is provided with a groove 301 corresponding to the reinforcing ring 12. The reinforcing ring 12 is embedded in the groove 301. The ring width of the first plastic part 3 in the XY plane is A, where A and a satisfy the relationship: 0.1≤a / A≤0.5, and the units of a and A are both mm.

[0044] 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, Y, and Z directions refer to... Figure 1 The directions indicated by the middle arrows "X", "Y", and "Z" are specifically: X represents the length of the cover assembly, Y represents the width of the cover assembly, and Z represents the height of the cover assembly. The cover body 1 has a first surface 11 and a second surface arranged opposite each other along the Z direction. When the cover assembly is assembled with the housing 8, the first surface 11 is the side of the cover body 1 facing away from the housing 8 along the Z direction, and the second surface is the side of the cover body 1 facing the housing 8 along the Z direction. The reinforcing ring 12 is formed by a portion of the first surface 11 protruding upwards along the Z direction. Here, "upwards" refers to the direction along the Z direction, i.e., the direction from the second surface to the first surface.

[0045] It should be noted that the orthographic projection of the reinforcing ring 12 along the Z direction onto the XY plane is annular, denoted as the first annular ring. The first annular ring is arranged circumferentially around the pole post hole 101, and the inner ring size of the first annular ring is larger than the opening size of the pole post hole 101. The ring width of the first annular ring is a. At least a portion of the first plastic part 3 is located on the upper side of the cover plate body 1 and is attached to the first surface 11. The outer contour size of the first plastic part 3 in the XY plane is larger than the outer ring size of the annular ring formed by the reinforcing ring 12, that is, the first plastic part 3 covers the reinforcing ring 12. The orthographic projection of the first plastic part 3 along the Z direction onto the XY plane is annular, denoted as the second annular ring. The ring width of the second annular ring is A (e.g., ...). Figure 5As shown); the lower surface of the portion of the first plastic part 3 located on the upper side of the cover plate body 1 is constructed with a groove 301 corresponding to the reinforcing ring 12. The groove 301 is an annular groove, and the width of the groove 301 in the XY plane is equal to the annular width a of the reinforcing ring 12. Here, the "upper side" refers to the upper side along the Z direction, that is, the upper side of the cover plate body 1 is the side of the cover plate body 1 away from the shell 8 along the Z direction; the "lower surface" refers to the lower surface along the Z direction.

[0046] The contact area between the cover plate body 1 and the first plastic part 3 is increased by the cooperation between the reinforcing ring 12 on the cover plate body 1 and the groove 301 on the first plastic part 3, thereby strengthening the connection strength between the first plastic part 3 and the cover plate body 1. If a / A is less than 0.1, the ring width of the reinforcing ring 12 is too small relative to the ring width of the first plastic part 3, and the structural strength of the reinforcing ring 12 is insufficient, making it difficult to withstand large external forces. When the pole post 2 is subjected to a large external force, the large external force is transmitted to the reinforcing ring 12 through the pole post 2 and the first plastic part 3, which will cause damage to the reinforcing ring 12, and thus lead to the first plastic part 3 and the cover plate body 1 being damaged. The connection between the main body 1 fails, failing to meet the limit torque strength requirement of the pole; if a / A is greater than 0.5, the ring width of the reinforcing ring 12 is too large relative to the ring width of the first plastic part 3. Correspondingly, the groove width of the groove 301 on the first plastic part 3 is too large, resulting in insufficient structural strength of the first plastic part 3. Although the wider reinforcing ring 12 can withstand a large instantaneous external force, during the long-term use of the battery cell, the pole 2 will inevitably be subjected to continuous external force. Even under small external force conditions, after a certain number of external force applications, the first plastic part 3 will experience fatigue failure and fail to meet the fatigue torque strength requirement of the pole.

[0047] In the cover plate assembly of this embodiment, a first plastic part 3 is injection molded between the pole post 2 and the cover plate body 1. The first plastic part 3 is simultaneously connected to both the pole post 2 and the cover plate body 1, achieving relative fixation between the pole post 2 and the cover plate body 1. Furthermore, the first plastic part 3 fully fills the gap between the pole post 2 and the cover plate body 1, ensuring the sealing and insulation between them. A reinforcing ring 12 is provided on the first surface 11 of the cover plate body 1, and a corresponding groove 301 is formed on the first plastic part 3. The reinforcing ring 12 is inserted into the groove 301, making the contact surface between the cover plate body 1 and the first plastic part 3 a non-planar structure. This increases the contact area between the cover plate body 1 and the first plastic part 3, thereby strengthening the connection strength between the first plastic part 3 and the cover plate body 1. Meanwhile, by limiting the ratio a / A between the ring width a of the reinforcing ring 12 and the ring width A of the first plastic part 3 to a value within the range of 0.1 to 0.5, it can be ensured that the reinforcing ring 12 has sufficient structural strength, so that the first plastic part 3 and the cover plate body 1 have sufficient connection strength. This ensures that the reinforcing ring 12 and the first plastic part 3 can withstand large temporary external forces under extreme working conditions, thereby enabling the cover plate assembly to meet the terminal ultimate torsional strength requirements. At the same time, it can also avoid the first plastic part 3 having insufficient structural strength due to an excessively large ring width of the reinforcing ring 12, ensuring that the first plastic part 3 has sufficient structural strength, so that the first plastic part 3 will not experience fatigue failure during long-term use of the battery cell, meeting the terminal fatigue torsional strength requirements, thereby ensuring the reliability and airtightness of the cover plate assembly and ensuring the safety of the battery cell.

[0048] Optionally, the value of a / A is any one of 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 or a value between any two values.

[0049] It should be noted that the pole post hole 101 is a through hole penetrating the cover plate body 1 along the Z direction. The pole post 2 also includes a base plate 22, which is connected to the lower end of the post 21. The cross-sectional area of ​​the base plate 22 in the XY plane is larger than the opening area of ​​the pole post hole 101. The base plate 22 is located on the lower side of the cover plate body 1 to restrict the pole post 2 from passing through the pole post hole 101 from bottom to top. Here, "lower end" refers to the lower end along the Z direction; "lower side" refers to the lower side along the Z direction, that is, the side of the cover plate body 1 away from the first surface 11 along the Z direction; "from bottom to top" refers to the direction along the Z direction from the second surface of the cover plate body 1 to the first surface 11.

[0050] In one embodiment, the circumference width A of the first plastic part 3 in the XY plane ranges from 3 mm to 8 mm. If A is less than 3 mm, the circumference width of the first plastic part 3 in the XY plane is too small, resulting in insufficient structural strength and susceptibility to cracking and damage during stress, which in turn affects the airtightness of the cover assembly or causes the electrode post to detach. If A is greater than 8 mm, the circumference width of the first plastic part 3 in the XY plane is too large, wasting material and increasing costs. Furthermore, since the first plastic part 3 wraps around the outer periphery of the post 21, an excessively large circumference width of the first plastic part 3 is not conducive to heat dissipation of the electrode post 2, leading to a higher temperature rise of the electrode post 2 during charging and discharging, which is detrimental to ensuring the safety of the battery cell.

[0051] Therefore, by limiting A to a value within the range of 3 mm to 8 mm, it is possible to ensure that the first plastic part 3 has sufficient structural strength, thereby preventing the first plastic part 3 from cracking and failing during use, ensuring the airtightness of the cover assembly, and preventing the problem of the first plastic part 3 loosening and causing the terminal 2 to fall off. It is also possible to avoid wasting materials, save production costs, and prevent the first plastic part 3 from excessively affecting the heat dissipation of the terminal 2, thereby preventing the terminal 2 from overheating and improving the safety of the battery cell.

[0052] Optionally, the value of A 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.

[0053] In one embodiment, further combination Figure 5 As shown, the height of the reinforcing ring 12 along the Z direction is h, and the distance between the upper surface of the first plastic part 3 and the first surface 11 along the Z direction is H. h and H satisfy the relationship: 0.15 ≤ h / H ≤ 0.85, where both h and H are in mm. It should be noted that h is the protrusion height of the reinforcing ring 12 relative to the first surface 11 along the Z direction; the lower surface of the portion of the first plastic part 3 located on the upper side of the cover plate body 1 is in contact with the first surface 11 of the cover plate body 1, and H is the height of the portion of the first plastic part 3 located on the upper side of the cover plate body 1 along the Z direction. The "upper surface" mentioned refers to the upper surface along the Z direction, that is, the upper surface of the first plastic part 3 is the surface of the first plastic part 3 on the side facing away from the cover plate body 1 along the Z direction.

[0054] It should be noted that if h / H is less than 0.15, the protrusion height of the reinforcing ring 12 is too small. Correspondingly, the groove depth of the groove 301 along the Z direction is too small, the mating dimension between the reinforcing ring 12 and the groove 301 along the Z direction is too small, the connection strength is insufficient, and it is difficult to withstand large external forces. The reinforcing ring 12 cannot effectively limit the movement of the first plastic part 3 in the XY plane. When the pole post 2 is subjected to a large external force, the large external force passes through the pole post 2 and the first plastic part 3, which will cause the groove 301 to disengage from the reinforcing ring 12. The connection between the reinforcing ring 12 of the cover plate body 1 and the groove 301 of the first plastic part 3 will fail. If a plastic part 3 falls off the cover plate body 1, it cannot meet the limit torque strength requirement of the pole post. If h / H is greater than 0.85, the height of the protrusion of the reinforcing ring 12 is too large relative to the height of the part of the first plastic part 3 located on the upper side of the cover plate body 1. Correspondingly, the height dimension of the solid part of the first plastic part 3 located above the groove 301 along the Z direction is too small, resulting in insufficient structural strength of the first plastic part 3. Although the higher reinforcing ring 12 can withstand the large instantaneous external force, during the long-term use of the battery cell, under the continuous action of external force, the first plastic part 3 will experience fatigue failure and cannot meet the fatigue torque strength requirement of the pole post.

[0055] Therefore, by limiting h / H to a value between 0.15 and 0.85, the reinforcing ring 12 has a reasonable protrusion height along the Z direction. This ensures that the reinforcing ring 12 has sufficient structural strength, providing sufficient connection strength between the first plastic part 3 and the cover plate body 1. This allows the reinforcing ring 12 and the first plastic part 3 to withstand larger temporary external forces, thus enabling the cover plate assembly to meet the terminal ultimate torque strength requirements. At the same time, it avoids the reinforcing ring 12 protruding too high, which would cause the remaining solid part of the first plastic part 3 to be too thin along the Z direction after the groove 301 is opened. This ensures that the first plastic part 3 has sufficient structural strength, preventing fatigue failure during long-term use of the battery cell and meeting the terminal fatigue torque strength requirements. This, in turn, ensures the reliability and airtightness of the cover plate assembly and guarantees the safety of the battery cell.

[0056] Optionally, the value of h / H is any one of 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, or a value between any two values.

[0057] In one embodiment, the distance H between the upper surface of the first plastic part 3 and the first surface 11 along the Z direction is in the range of 2 mm ≤ H ≤ 5 mm. If H is less than 2 mm, the portion of the first plastic part 3 located on the upper side of the cover plate body 1 has too small a dimension along the Z direction, the first plastic part 3 is too thin, the structural strength is too poor, and it is easy to crack and fail during use; if H is greater than 5 mm, the portion of the first plastic part 3 located on the upper side of the cover plate body 1 has too large a dimension along the Z direction, the first plastic part 3 is too thick, which wastes material, and there may be a phenomenon where the upper surface of the first plastic part 3 is higher than the upper surface of the pole post 2, the first plastic part 3 interferes with the busbar and other structures that need to be welded to the pole post 2, and it is not conducive to the layout of the cells in the battery pack.

[0058] Therefore, by limiting H to a value within the range of 2 mm to 5 mm, it is possible to ensure that the first plastic part 3 has sufficient structural strength, avoid cracking and damage during use, ensure the airtightness of the cover assembly, avoid the problem of the first plastic part 3 loosening and causing the terminal post 2 to fall off, avoid wasting materials, save production costs, and avoid interference between the first plastic part 3 and the busbar and other structures that need to be connected on the terminal post 2, which facilitates the layout of the cells in the battery pack.

[0059] Optionally, the value of H is any one of 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, or a value between any two of these values.

[0060] In one embodiment, further combination Figure 5 As shown, in the XY plane, the distance between the outer ring of the reinforcing ring 12 and the outer ring of the first plastic part 3 is L, where L≥0.3 mm. It should be noted that the reinforcing ring 12 is embedded in the groove 301 on the first plastic part 3. The groove 301 has a first side wall close to the column 21 along the radial direction of the column 21 and a second side wall away from the column 21. The distance L between the outer ring of the reinforcing ring 12 and the outer ring of the first plastic part 3 is also the distance between the outer peripheral wall of the first plastic part 3 and the second side wall of the groove 301. That is, the thickness of the solid part of the first plastic part 3 wrapped around the reinforcing ring 12 along the radial direction away from the column 21 in the XY plane. If L is less than 0.3 mm, the distance between the outer ring of the reinforcing ring 12 and the outer ring of the first plastic part 3 is too small, and the solid part of the first plastic part 3 located on the outer side of the reinforcing ring 12 along the radial direction is too small. The structural strength of this part is insufficient, and it is easy to deform or crack when subjected to external force, which leads to the failure of the connection between the first plastic part 3 and the cover plate body 1, and then the pole is loosened, and the airtightness of the cover plate assembly is destroyed.

[0061] Therefore, by limiting L to not less than 0.3 mm, it can be ensured that the solid part of the first plastic part 3 wrapped around the outer ring of the reinforcing ring 12 has sufficient structural strength, avoiding deformation or cracking of the first plastic part 3 during the use of the battery cell, thereby further ensuring the connection strength between the first plastic part 3 and the cover plate body 1, ensuring the airtightness between the pole post 2 of the cover plate assembly and the cover plate body 1, and improving the reliability of the cover plate assembly.

[0062] In one embodiment, the column 21 has a first axis extending along the Z direction and an outer peripheral surface surrounding the first axis. A limiting groove 211 is formed on the outer peripheral surface of the column 21. The first plastic part 3 includes a plastic part body 31 and a protrusion 32. The plastic part body 31 is annular, and the protrusion 32 is connected to the inner ring of the plastic part body 31 and inserted into the limiting groove 211. The limiting groove 211 is formed by at least a portion of the outer peripheral surface of the column 21 being recessed radially along the column 21. By opening a limiting groove 211 on the outer circumferential surface of the column 21, and setting a plastic body 31 including a plastic body 31 and a protrusion 32 connected to the inner ring of the plastic body 31, and inserting the protrusion 32 into the limiting groove 211, the first plastic part 3 and the column 21 are mutually limited through the insertion and cooperation of the protrusion 32 and the limiting groove 211, so as to prevent the first plastic part 3 from slipping off relative to the pole post 2 in the Z direction, further increasing the connection strength between the first plastic part 3 and the pole post 2, avoiding the problem of the pole post 2 loosening, and ensuring the airtightness of the cover plate assembly.

[0063] In one embodiment, the orthographic projection of the column 21 along the Z direction in the XY plane is circular, which is simple in structure and easy to process and shape.

[0064] In one embodiment, the limiting groove 211 is an annular groove arranged around the circumference of the column 21, which facilitates processing and can improve the circumferential force uniformity of the column 21. Correspondingly, the protrusion 32 is a convex ring that surrounds the circumference of the column 21.

[0065] In one embodiment, the column segment with a limiting groove 211 on the column 21 is a slotted segment. The outer circumferential surface of the slotted segment includes an arc surface and an anti-rotation surface. The arc surface is part of the outer circumferential surface of the column, and the anti-rotation surface is a plane parallel to the axis of the column 21. The arc surface and the anti-rotation surface are connected circumferentially. The protrusion 32 of the first plastic part 3 has an arc segment corresponding to the arc surface and a straight segment corresponding to the anti-rotation surface. The anti-rotation surface cooperates with the corresponding straight segment formed on the first plastic part 3 to restrict the relative rotation between the column 21 and the first plastic part 3 in the circumferential direction, thereby realizing the circumferential limiting between the pole post 2 and the first plastic part 3, and further improving the connection stability between the first plastic part 3 and the pole post 2.

[0066] In other embodiments, the limiting groove 211 may also be a partial section of an annular groove arranged around the circumference of the column 21, that is, the limiting groove 211 does not form a complete ring. The number of limiting grooves 211 may be one or multiple grooves arranged at intervals along the circumference of the column. Correspondingly, the protrusion 32 is a partial section of the protruding ring, and the protrusion 32 can also be inserted into the limiting groove 211 to achieve axial and circumferential limiting between the first plastic part 3 and the pole post 2.

[0067] In one embodiment, the recess depth of the limiting groove 211 in the XY plane is W, wherein the value of W ranges from 0.3 mm to 2.0 mm. The limiting groove 211 is formed by a radial indentation in the upper part of the outer peripheral surface of the column 21. W is the radial depth of the limiting groove 211. If W is less than 0.3 mm, the depth of the limiting groove 211 is too small, resulting in an insufficient radial dimension of the protrusion 32. This leads to poor structural strength of the protrusion 32 and insufficient radial fit between the protrusion 32 and the limiting groove 211. When the pole post 2 is subjected to external torque, the protrusion 32 is prone to detaching from the limiting groove 211, causing the pole post 2 to fall off and failing to provide effective limiting. The cross-sectional area of ​​the grooved section corresponding to the limiting groove 211 on the column 21 is smaller than that of the section without the limiting groove 211, reducing the flow area of ​​the grooved section. This reduction in flow area leads to increased resistance. If W is greater than 2.0 mm... If the depth of the limiting groove 211 is too large, the cross-sectional area of ​​the grooved section in the XY plane will be too small after the limiting groove 211 is opened, resulting in poor current carrying capacity, excessive resistance, and excessive heat generation during charging and discharging. The temperature rise of the electrode 2 during the charging and discharging process will be too high, and the temperature difference between the upper and lower surfaces of the electrode 2 will be too large, which is not conducive to ensuring the safety of the battery cell. In addition, a temperature acquisition device is set on the upper surface of the electrode 2 to collect the temperature and realize the temperature monitoring of the battery cell. If the temperature difference between the upper and lower surfaces of the electrode 2 is too large, it will lead to inaccurate temperature monitoring, which is not conducive to ensuring the safety of the battery cell.

[0068] Therefore, by limiting W to a value within the range of 0.3 mm to 2.0 mm, it is possible to ensure that the limiting groove 211 and the protrusion 32 on the first plastic part 3 have sufficient radial fitting dimensions, ensuring the injection molding strength of the protrusion 32, so that the protrusion 32 can play an effective limiting role after fitting with the limiting groove 211, ensuring the reliability of the connection between the first plastic part 3 and the electrode 2. At the same time, it is possible to avoid the setting of the limiting groove 211 having an excessive impact on the current carrying capacity of the electrode 2, thereby avoiding excessive temperature rise of the electrode 2 during the charging and discharging process of the battery cell, avoiding excessive temperature difference between the upper and lower surfaces of the electrode 2, ensuring the accuracy of the temperature collected by the temperature acquisition device set on the upper surface of the electrode 2, and improving the safety of the battery cell.

[0069] The upper surface of the pole post 2 refers to the surface of the pole body 21 facing away from the base plate 22 along the Z direction, and the lower surface of the pole post 2 refers to the surface of the base plate 22 facing away from the pole body 21 along the Z direction.

[0070] Optionally, the value of W is any one of 0.3 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2.0 mm, or a value between any two of these values.

[0071] In one embodiment, the height of the limiting groove 211 along the Z direction is h1, wherein the value of h1 is in the range of 1.0 mm ≤ h1 ≤ 5.0 mm. It should be noted that h1 is the groove height of the limiting groove 211. 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 h1 is greater than 5.0 mm, the height of the grooved section on the post 21 along the Z direction is too large, resulting 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 on the upper surface of the terminal post 2 will be inaccurate. If h1 is less than 1.0 mm, the groove height is too small. Correspondingly, the size of the protrusion 32 along the Z direction is too small, and the fitting height between the limiting groove 211 and the protrusion 32 is insufficient, making it difficult to play an effective limiting role. The protrusion 32 is prone to detach from the limiting groove 211 when the terminal post 2 is subjected to a force along the Z direction, causing relative loosening between the first plastic part 3 and the terminal post 2, making it difficult to ensure a stable connection and airtightness between the first plastic part 3 and the terminal post 2.

[0072] Therefore, by limiting h1 to a value within the range of 1.0 mm to 5.0 mm, the limiting groove 211 has a reasonable height along the Z direction. This not only avoids excessive temperature difference between the upper and lower surfaces of the electrode post 2, ensuring the accuracy of temperature monitoring of the electrode post by the temperature detection device installed on the upper surface of the electrode post 2, but also ensures that the limiting groove 211 provides sufficient fitting height for the protrusion 32 of the first plastic part 3, ensuring that the protrusion 32 has sufficient structural strength, preventing the protrusion 32 from coming out of the limiting groove 211, improving the stability of the connection between the first plastic part 3 and the electrode post 2, thereby ensuring the airtightness between the two and improving the safety of the battery cell.

[0073] Optionally, the value of h1 is any one of 1.0 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5.0 mm, or a value between any two of these values.

[0074] In one embodiment, the cover assembly further includes a sealing ring 4, which is sleeved on the post 21 and located on the lower side of the first plastic part 3 along the Z direction. The lower surface of the first plastic part 3 is in contact with the upper surface of the sealing ring 4, and the lower surface of the sealing ring 4 abuts against the upper surface of the base plate 22. At least a portion of the sealing ring 4 is press-fitted between the cover body 1 and the base plate 22 to further ensure the sealing between the post 2 and the cover body 1. Here, the lower surface refers to the lower surface along the Z direction, and the upper surface refers to the upper surface along the Z direction.

[0075] In one embodiment, the cover plate assembly further includes a second plastic part 5, which is disposed on the side of the cover plate body 1 facing away from the first plastic part 3 in the Z direction 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. Specifically, the first plastic part 3 is the upper plastic, and the second plastic part 5 is the lower plastic.

[0076] In one embodiment, the cover plate body 1 is further provided with an injection hole 102, 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 102 is sealed by a sealing plug.

[0077] In one embodiment, the cover plate body 1 is further provided with a pressure relief hole 103, and the cover plate assembly also includes a pressure relief valve 6, which is installed in the pressure relief hole 103. 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 103 to protect the pressure relief valve 6.

[0078] According to an embodiment of the present invention, in another aspect, a battery cell is also provided, such as... Figures 13 to 14 As shown, the battery cell includes: a housing 8, an electrode assembly 9, and the aforementioned cover plate assembly. The housing 8 has an open end; the electrode assembly 9 is disposed within the inner cavity of the housing 8; the cover plate assembly covers the open end of the housing 8. The electrode assembly 9 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.

[0079] The following examples and comparative examples verify the impact of different parameter values ​​on the battery cell. The parameter settings for the examples and comparative examples are shown in Table 1, and the corresponding verification results are shown in Table 2.

[0080] It should be noted that during the test, the terminals of the battery cell underwent both ultimate torque strength test and fatigue torque strength test. For the ultimate torque strength test, the terminal was required to withstand a torque of ≥6 N•M in the X / Y / Z directions. For the fatigue torque strength test, the terminal was required to withstand a force of 3 N•M in the X / Y / Z directions and undergo ≥50,000 fatigue cycles. During the test, failure was considered a failure if any of the following conditions were not met: no cracking of the first plastic part, airtightness of the cover assembly, or terminal height. The terminal height refers to the height of the terminal 2 protruding from the first surface 11 of the cover body 1 along the Z direction. For a given battery cell, the terminal height is constant after assembly. If a terminal becomes loose, it will manifest as a change in terminal height. Therefore, whether the terminal height meets the requirements can be used to determine if the terminal is loose.

[0081] Table 1

[0082]

[0083] Table 2

[0084]

[0085] In Table 2, OK indicates qualified and NG indicates unqualified.

[0086] As can be seen from Tables 1 to 2, for the battery cells of Examples 1 to 12, all parameters are within the range defined in this application, the ultimate torque strength of the pole is greater than 6 N•M, and the fatigue torque cycles of the pole are greater than 50,000, that is, the ultimate torque strength test and the fatigue torque strength test are both qualified, and the performance is good.

[0087] For the cell in Comparative Example 1, the a / A value is 0.093, which is less than the lower limit of a / A of 0.1 defined in this application. The terminal limit torque strength is 5.8 N•M, and the terminal fatigue torque cycles are 57,800. For the cell in Comparative Example 2, the a / A value is 0.048, which is less than the lower limit of a / A of 0.1 defined in this application. The terminal limit torque strength is 4.6 N•M, and the terminal fatigue torque cycles are 65,500. The a / A values ​​in Comparative Example 1 and Comparative Example 2 are both less than the lower limit of a / A of 0.1 defined in this application. Although the terminal fatigue torque cycles are both greater than 50,000, the terminal limit torque strength is less than 6 N•M, meaning the limit torque strength test is unqualified, and the cell fails during the limit torque strength test.

[0088] For the cell in Comparative Example 3, the a / A value is 0.509, which is greater than the upper limit of a / A of 0.5 defined in this application. The terminal limit torque strength is 7.8 N•M, and the terminal fatigue torque cycle is 45,300. For the cell in Comparative Example 4, the a / A value is 0.522, which is greater than the upper limit of a / A of 0.5 defined in this application. The terminal limit torque strength is 8.5 N•M, and the terminal fatigue torque cycle is 32,900. The a / A values ​​in Comparative Examples 3 and 4 are both greater than the upper limit of a / A of 0.5 defined in this application. Although the terminal limit torque strength is greater than 6 N•M, the terminal fatigue torque cycle is less than 50,000, meaning the fatigue torque strength test is unqualified, and the cell fails during the fatigue torque strength test.

[0089] It can be seen that when the value of a / A is in the range of 0.1 to 0.5, the cell terminal can pass both the ultimate torque strength test and the fatigue torque strength test. This indicates that the first plastic part 3 can withstand the large temporary external force under extreme working conditions and will not fail due to fatigue during long-term use of the cell, thereby ensuring the reliability and airtightness of the cover assembly and thus ensuring the safety of the cell.

[0090] For the cell of Comparative Example 5, the h / H value is 0.146, which is less than the lower limit of h / H of 0.15 defined in this application. The terminal limit torque strength is 4.2 N•M, and the terminal fatigue torque cycle is 45,700 cycles. For the cell of Comparative Example 6, the h / H value is 0.129, which is less than the lower limit of h / H of 0.15 defined in this application. The terminal limit torque strength is 3.6 N•M, and the terminal fatigue torque cycle is 42,800 cycles. In both Comparative Examples 5 and 6, the h / H values ​​are less than the lower limit of h / H of 0.15 defined in this application. The terminal limit torque strength is less than 6 N•M, and the terminal fatigue torque cycle is less than 50,000 cycles. Both the limit torque strength test and the fatigue torque strength test are unqualified, and the cells fail.

[0091] For the cell of Comparative Example 7, the h / H value is 0.885, which is greater than the upper limit of h / H of 0.85 defined in this application. The terminal limit torque strength is 9.2 N•M, and the terminal fatigue torque cycle is 45,400 cycles. For the cell of Comparative Example 8, the h / H value is 0.864, which is greater than the upper limit of h / H of 0.85 defined in this application. The terminal limit torque strength is 8.6 N•M, and the terminal fatigue torque cycle is 32,900 cycles. In Comparative Examples 7 and 8, the h / H values ​​are both greater than the upper limit of h / H of 0.85 defined in this application. Although the terminal limit torque strength is greater than 6 N•M, the terminal fatigue torque cycle is less than 50,000 cycles. That is, the fatigue torque strength test is unqualified, and the cell fails in the fatigue torque strength test.

[0092] It can be seen that when the value of h / H is in the range of 0.15 to 0.85, the cell terminal can pass both the ultimate torque strength test and the fatigue torque strength test. This indicates that the first plastic part 3 can withstand the large temporary external force under extreme working conditions and will not fail due to fatigue during long-term use of the cell, thereby ensuring the reliability and airtightness of the cover assembly and thus ensuring the safety of the cell.

[0093] It should be noted that the torsional strength test of battery cells is divided into ultimate torsional strength test (static destructive test) and fatigue torsional strength test (dynamic durability test). Both are aimed at the torsional resistance of battery cells, modules, or packs. The core purpose is to verify the structural integrity of the battery cell under extreme operating conditions or long-term use, and to avoid safety problems such as internal short circuits, leakage, and fire caused by torsional deformation. Among them, the ultimate torsional strength test applies a gradually increasing static torque until the battery cell structure suffers irreversible damage (such as cracking of the first plastic part, failure of the cover assembly seal, or loosening of the terminal post), and determines the maximum torque value that the battery cell can withstand. This is a destructive test. The fatigue torsional strength test applies a torsional load below the ultimate torsional load to the battery cell in a cyclic torsional manner until the battery cell fails due to fatigue (such as cracking of the first plastic part, failure of the cover assembly seal, or loosening of the terminal post), and determines the torsional fatigue life of the battery cell. This is a durability test.

[0094] 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.

[0095] 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 an electrode post hole. A first surface is formed on one side of the cover plate body along the Z direction. A reinforcing ring is provided on the first surface. The reinforcing ring is arranged circumferentially around the electrode post hole. The reinforcing ring is formed by a portion of the first surface protruding along the Z direction. The ring width of the reinforcing ring in the XY plane is a. An electrode post includes a column body, the column body being inserted into the electrode post hole; A first plastic part is injection molded between the column and the cover plate body. The first plastic part is annular and sleeved on the column, and at least a portion of the first plastic part is in contact with the first surface. The side of the first plastic part facing the cover plate body is provided with a groove corresponding to the reinforcing ring, and the reinforcing ring is embedded in the groove. The ring width of the first plastic part in the XY plane is A, where A and a satisfy the relationship: 0.1≤a / A≤0.

5.

2. The cover plate assembly according to claim 1, characterized in that, The range of the ring width A of the first plastic part in the XY plane is: 3 mm ≤ A ≤ 8 mm.

3. The cover plate assembly according to claim 1, characterized in that, The height of the reinforcing ring along the Z direction is h, and the distance between the upper surface of the first plastic part and the first surface along the Z direction is H, wherein h and H satisfy the relationship: 0.15≤h / H≤0.

85.

4. The cover plate assembly according to claim 3, characterized in that, The value range of the distance H along the Z direction between the upper surface of the first plastic part and the first surface is: 2 mm ≤ H ≤ 5 mm.

5. The cover plate assembly according to claim 1, characterized in that, In the XY plane, the distance between the outer ring of the reinforcing ring and the outer ring of the first plastic part is L, where L≥0.3 mm.

6. The cover plate assembly according to claim 1, characterized in that, The column has a first axis extending along the Z direction and an outer peripheral surface surrounding the first axis, and a limiting groove is formed on the outer peripheral surface of the column. The first plastic part includes a plastic part body and a protrusion. The plastic part body is ring-shaped, and the protrusion is connected to the inner ring of the plastic part body and inserted into the limiting groove.

7. The cover plate assembly according to claim 6, characterized in that, The recess depth of the limiting groove in the XY plane is W, where the value of W ranges from 0.3 mm to 2.0 mm.

8. The cover plate assembly according to claim 6, characterized in that, The height of the limiting groove along the Z direction is h1, where the value of h1 is in the range of 1.0 mm ≤ h1 ≤ 5.0 mm.

9. The cover plate assembly according to any one of claims 1 to 8, characterized in that, The cover plate assembly further includes a sealing ring, which is sleeved on the column and located on the lower side of the first plastic part along the Z direction.

10. A battery cell, characterized in that, include: The shell has an open end; The electrode assembly is disposed within the inner cavity of the housing; The cover assembly according to any one of claims 1 to 9 is provided covering the opening end of the housing.

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