Cover plate assembly and battery cell

Abstract

The invention 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 having a mounting hole; the post comprises a post part and a plate part, the post part is arranged in the mounting hole in a penetrating manner, the plate part is located on the lower side of the cover plate body in the Z direction, the post part is provided with a peripheral surface deviating from the axis of the post part in the radial direction, a limiting groove is formed in the peripheral surface of the post part, the concave depth of the limiting groove in the radial direction is L, the height of the limiting groove in the Z direction is H1, and L and H1 meet the relational expression that L / H1 is larger than or equal to 1 / 2 and smaller than or equal to 2 / 3; the injection molding part is formed between the column part and the cover plate body in an injection molding mode, the injection molding part comprises a plastic part main body and a limiting convex part, the column part is sleeved with the plastic part main body, at least part of the plastic part main body is located on the upper side of the cover plate body and connected with the upper surface of the cover plate body, and the limiting convex part is fixedly connected with the plastic part main body and inserted into the limiting groove. According to the cover plate assembly, the cost is reduced, the production efficiency and the production yield are improved, and the pole is prevented from falling off.

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. Current cover plate assemblies primarily utilize riveted covers and include components such as the cover plate body, terminals, riveting blocks, upper plastic, lower plastic, and sealing rings. The terminals pass through terminal mounting holes on the cover plate body and employ a riveting structure. The riveting block is located on one side of the cover plate assembly and riveted to the terminal. The upper and lower plastics are located on opposite sides of the cover plate body, with at least a portion of the upper plastic located between the riveting block and the cover plate body to ensure insulation between them. However, riveted cover plate assemblies have the following drawbacks: the need for a riveting block for the terminal riveting adds to the cost; and welding is required after the riveting block and terminal are riveted, increasing the processing steps and reducing production efficiency and yield. Summary of the Invention

[0003] This invention provides a cover plate assembly and a battery cell to solve the problems of high cost, low production efficiency and low yield of cover plate assemblies.

[0004] In a first aspect, the present invention provides a cover plate assembly, comprising: a cover plate body having a mounting hole; a pole post including a pole portion and a plate portion, the pole portion passing through the mounting hole, the plate portion being located on the lower side of the cover plate body along the Z direction, the pole portion having an outer peripheral surface radially away from the axis of the pole portion, a limiting groove being formed on the outer peripheral surface of the pole portion, the limiting groove having a radial recess depth of L, and a limiting groove having a height of H1 along the Z direction, wherein L and H1 satisfy the relationship: 1 / 2≤L / H1≤2 / 3; and an injection molded part, injection molded between the pole portion and the cover plate body, the injection molded part including a plastic part body and a limiting protrusion, the plastic part body being sleeved on the pole portion, at least a portion of the plastic part body being located on the upper side of the cover plate body and connected to the upper surface of the cover plate body, the limiting protrusion being fixedly connected to the plastic part body, and the limiting protrusion being inserted into the limiting groove.

[0005] Beneficial effects: An injection molded part is formed between the electrode post and the cover plate body. The plastic part is molten and injected into the gap between the electrode post and the cover plate body through injection molding. After cooling, a sealed connection is achieved between the electrode post and the cover plate body. This eliminates the need for traditional riveting blocks, reducing costs and improving production efficiency and yield. Furthermore, by creating a limiting groove on the electrode post, the injection molded part forms a limiting protrusion embedded in the limiting groove, as well as a plastic body surrounding the outer periphery of the post and connected to the cover plate body. The injection molded part achieves a continuous connection with the electrode post through the limiting protrusion. The mutual restraint in the Z direction, and by limiting the ratio of the radial recess depth L of the restraining groove to the height H1 of the restraining groove in the Z direction to be within the range of 1 / 2 to 2 / 3, can ensure the structural strength of the restraining protrusion, the connection strength between the injection molded part and the electrode, and thus ensure the reliability of the connection between the injection molded part and the electrode, preventing the electrode from falling off. At the same time, it can also prevent the opening of the restraining groove from having an excessive impact on the internal resistance of the electrode, thereby preventing the electrode from having an excessive temperature rise during the charging and discharging process of the battery cell, thus improving the safety of the battery cell.

[0006] In one optional embodiment, the radial recess depth L of the limiting groove is in the range of 1.2 mm ≤ L ≤ 2.0 mm.

[0007] Beneficial effects: It can ensure that the limiting groove and the limiting protrusion have sufficient matching dimensions in the radial direction, ensure the injection molding strength of the limiting protrusion, avoid cracking of the limiting protrusion, and ensure the connection strength between the terminal and the injection molded part. It can also avoid the opening of the limiting groove from having too much impact on the current carrying capacity of the terminal, thereby avoiding excessive temperature rise of the terminal during the charging and discharging process of the battery cell and improving the safety performance of the battery cell.

[0008] In one alternative embodiment, the distance between the upper surface of the column and the lower end face of the limiting groove along the Z direction is H2; Among them, H2 and H1 satisfy the following relationship: H1≥0.5×H2; And / or, H2 and H1 satisfy the relationship: H2-H1≥1 mm.

[0009] Beneficial effects: By limiting H1 to be no less than half of H2, the limiting groove has sufficient dimensions in the Z direction, thereby ensuring that the limiting protrusion and the limiting groove have sufficient mating dimensions in the Z direction, avoiding the limiting protrusion from breaking under stress, ensuring the mating strength between the pole and the injection molded part, and thus ensuring the mating strength between the pole and the cover plate body. And / or, by limiting H2-H1 to be greater than or equal to 1 mm, the column segment located above the limiting groove is guaranteed to have sufficient structural strength, thereby satisfying the fit strength between the pole post and the injection molded part, and further satisfying the fit strength between the pole post and the cover plate body, thus improving the reliability and safety of the cover plate assembly.

[0010] In one optional embodiment, the height of the column along the Z direction is H0, wherein H0 and H1 satisfy the relationship: 0.2≤H1 / H0≤0.6.

[0011] Beneficial effects: It can ensure that the limiting groove has sufficient groove height, thereby ensuring that the limiting protrusion that mates with the limiting groove has sufficient structural strength, avoiding cracking of the limiting protrusion, and ensuring the connection strength and stability between the injection molded part and the electrode post. It can also ensure that the electrode post itself has sufficient structural strength and current carrying capacity, thereby ensuring the reliability of the electrode post and the safety of the battery cell.

[0012] In one alternative embodiment, the limiting groove is an annular groove arranged around the axis of the column.

[0013] Beneficial effects: The annular groove structure is simple and easy to process, which helps to improve molding efficiency and molding yield. It also allows the interaction force between the pole and the injection molded part to be evenly distributed along the circumference of the pole, ensuring the uniformity of the force on the pole and further improving the service life of the pole and the injection molded part.

[0014] In one optional embodiment, the cover plate body forms a recessed platform around the circumferential edge of the mounting hole. The recessed platform is formed by a portion of the upper surface of the cover plate body recessed along the Z direction. The recessed depth of the platform along the Z direction is H3, wherein the value of H3 is in the range of 0.2 mm ≤ H3 ≤ 0.5 mm.

[0015] Beneficial effects: It can effectively improve the connection strength between the injection molded part and the cover plate body, and ensure that the cover plate body has sufficient structural strength, thereby improving the reliability of the cover plate assembly.

[0016] In one optional embodiment, the width of the sinking platform in the XY plane is W, wherein the value of W ranges from 0.9 mm to 1.2 mm.

[0017] Beneficial effects: It can ensure the smooth processing and molding of the sink, ensure the molding yield of the cover plate body, and effectively improve the connection strength between the injection molded part and the cover plate body. It can also ensure the structural strength of the corresponding position on the cover plate body and the injection molded part, thereby ensuring the reliability of the cover plate assembly.

[0018] In one optional embodiment, the cover plate body has a pole post area corresponding to the plate portion, and the thickness of the pole post area along the Z direction is H4, wherein the value of H4 is in the range of 1.8 mm ≤ H4 ≤ 2.0 mm.

[0019] Beneficial effects: It can ensure that the pole area has sufficient structural strength, prevent the pole from falling out of the mounting hole, ensure the reliability of the assembly between the cover plate body and the pole, and help improve the energy density of the cell.

[0020] In one alternative embodiment, the cover plate assembly further includes a sealing ring, the sealing ring being sleeved on the post portion, and the upper surface of the sealing ring being lower than the lower end face of the limiting groove, and the injection molded part being located above the sealing ring.

[0021] Beneficial effects: Ensures the sealing between the pole and the cover plate body, improves the reliability of the cover plate assembly, and avoids the sealing ring affecting the molding of the limiting protrusion by setting the upper surface of the sealing ring to be lower than the lower end surface of the limiting groove, thus ensuring the injection molding strength of the limiting protrusion.

[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; Figure 2 for Figure 1 Top view of the cover plate assembly shown; Figure 3 for Figure 2 A cross-sectional view along the AA direction; Figure 4 for Figure 3 A magnified view of part B in the diagram; Figure 5 for Figure 4 A magnified view of part of C; Figure 6 for Figure 1 The bottom view of the cover plate assembly shown; Figure 7 for Figure 1 The front view of the cover plate assembly shown; Figure 8 for Figure 1 Side view of the cover assembly shown.

[0025] Explanation of reference numerals in the attached figures: 1. Cover plate body; 101. Pole post area; 11. Mounting hole; 12. Recessed platform; 13. Injection hole; 2. Pole post; 21. Post part; 211. Limiting groove; 22. Plate part; 3. Injection molded part; 31. Plastic part body; 311. First convex ring; 312. Second convex ring; 32. Limiting protrusion; 4. Sealing ring; 5. Second plastic part; 6. Explosion-proof valve. Detailed Implementation

[0026] 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.

[0027] The cover plate assembly is a crucial component of the battery cell. Current cover plate assemblies primarily utilize riveted covers and include components such as the cover plate body, terminals, riveting blocks, upper plastic, lower plastic, and sealing rings. The terminals pass through terminal mounting holes on the cover plate body and employ a riveting structure. The riveting block is located on one side of the cover plate assembly and riveted to the terminal. The upper and lower plastics are located on opposite sides of the cover plate body, with at least a portion of the upper plastic located between the riveting block and the cover plate body to ensure insulation between them. However, riveted cover plate assemblies have the following drawbacks: the need for a riveting block for the terminal riveting adds to the cost; and welding is required after the riveting block and terminal are riveted, increasing the processing steps and reducing production efficiency and yield.

[0028] The following is combined with Figures 1 to 8 The following describes embodiments of the present invention.

[0029] According to an embodiment of the present invention, a cover plate assembly is provided, comprising: a cover plate body 1, an end post 2, and an injection molded part 3. The cover plate body 1 has a mounting hole 11; the end post 2 includes a post portion 21 and a plate portion 22, the post portion 21 passing through the mounting hole 11, the plate portion 22 being located on the lower side of the cover plate body 1 along the Z direction, the post portion 21 having an outer peripheral surface radially away from the axis of the post portion 21, a limiting groove 211 being formed on the outer peripheral surface of the post portion 21, the radial recess depth of the limiting groove 211 being L, and the height of the limiting groove 211 along the Z direction being H1, wherein the distance between L and H1 is... The following relationship is satisfied: 1 / 2 ≤ L / H1 ≤ 2 / 3; the injection molded part 3 is injection molded between the column 21 and the cover plate body 1. The injection molded part 3 includes a plastic body 31 and a limiting protrusion 32. The plastic body 31 is sleeved on the column 21, and at least a portion of the plastic body 31 is located on the upper side of the cover plate body 1 and connected to the upper surface of the cover plate body 1. The limiting protrusion 32 is fixedly connected to the plastic body 31 and is inserted into the limiting groove 211. Here, L and H1 are both in mm; the Z direction refers to... Figure 1 , Figures 3 to 5 , Figures 7 to 8 The direction indicated by the middle arrow "Z"; the axis of the column 21 extends along the Z direction; the radial direction is defined as the direction perpendicular to the Z direction and passing through the axis of the column 21; the "upper side" mentioned refers to the upper side along the Z direction, and the "lower side" mentioned refers to the lower side along the Z direction. The upper side and the lower side are the opposite sides of the cover plate body 1 along the Z direction.

[0030] It should be noted that the limiting groove 211 is formed by a portion of the outer peripheral surface of the column 21 recessed radially toward the axis of the column 21. The limiting groove 211 has a groove bottom surface radially toward the axis of the column and two groove sidewalls arranged opposite each other in the Z direction. The injection molded part 3 is injection molded between the column 21 and the cover plate body 1. The portion of the injection molded part 3 injected into the limiting groove 211 forms the limiting protrusion 32. The limiting protrusion 32 engages with the limiting groove 211, limiting the relative movement between the pole post 2 and the injection molded part 3 in the Z direction. L is the distance between the groove bottom surface and the outer peripheral surface of the column 21 in the XY plane, and H is the distance between the two groove sidewalls of the limiting groove 211 in the Z direction. The radial dimension of the limiting protrusion 32 of the injection molded part 3 is equal to L, and the Z-direction dimension of the limiting protrusion 32 is equal to H.

[0031] If L / H1 is less than 1 / 2, the radial depth of the limiting groove 211 is too small relative to the Z-direction opening height of the limiting groove 211. This results in the radial dimension of the limiting protrusion 32 embedded in the limiting groove 211 being too small relative to its Z-direction dimension. Consequently, the radial fit between the limiting protrusion 32 and the limiting groove 211 is too small, making the limiting protrusion 32 prone to detachment or damage from the limiting groove 211, leading to poor injection molding strength. If L / H1 is greater than 2 / 3, the radial depth of the limiting groove 211 is too large relative to the Z-direction opening height of the limiting groove 211. This results in excessive material removal from the pillar 21 due to the limiting groove 211, causing an excessive reduction in the cross-sectional area of ​​the remaining solid portion of the pillar 21 after the limiting groove 211 is opened. Consequently, the resistance of the pillar 21 becomes too high, and the temperature rise of the electrode 2 during the charging and discharging process of the battery cell becomes too high, affecting the safety of the battery cell.

[0032] In this embodiment, the cover plate assembly is injection molded between the pole post 2 and the cover plate body 1 to form an injection molded part 3. The plastic part is molten and injected into the gap between the pole post 2 and the cover plate body 1 through injection molding. After cooling, a sealed connection between the pole post 2 and the cover plate body 1 is achieved. This eliminates the need for traditional riveting blocks, reducing costs and improving production efficiency and yield. Simultaneously, by creating a limiting groove 211 on the pole post 2, the injection molded part 3 has a limiting protrusion 32 embedded in the limiting groove 211, and a plastic body 31 surrounding the outer periphery of the pole post 21 and connected to the cover plate body 1. The injection molded part 3 achieves a sealed connection through the limiting protrusion 32. The limiting groove 211 is mutually positioned along the Z-direction with the electrode post 2. By limiting the ratio of the radial recess depth L of the limiting groove 211 to the height H1 of the limiting groove 211 along the Z-direction to a value within the range of 1 / 2 to 2 / 3, the structural strength of the limiting protrusion 32 and the connection strength between the injection molded part 3 and the electrode post 2 can be guaranteed, thus ensuring the reliability of the connection between the injection molded part 3 and the electrode post 2 and preventing the electrode post 2 from falling off. At the same time, the opening of the limiting groove 211 can also prevent the opening of the limiting groove 211 from having an excessive impact on the internal resistance of the electrode post 2, thereby preventing the electrode post 2 from having an excessive temperature rise during the charging and discharging process of the battery cell, thus improving the safety of the battery cell.

[0033] Optionally, the value of L / H1 can be any one of 1 / 2, 8 / 15, 7 / 12, 3 / 5, 5 / 8, 2 / 3, or a value between any two of these values.

[0034] It should be noted that further integration Figures 1 to 8As shown, the cover assembly has two perpendicular X, Y, and Z directions forming a Cartesian coordinate system. The X and Y directions intersect to form the XY plane. Specifically, the X direction is the length direction of the cover assembly, the Y direction is the width direction of the cover assembly, and the Z direction is the thickness direction of the cover assembly. The cover body 1 has upper and lower sides arranged opposite to each other along the Z direction. When the cover assembly is assembled with the housing, the upper side of the cover body 1 is the side facing away from the housing along the Z direction, and the lower side of the cover body 1 is the side pointing towards the inner cavity of the housing along the Z direction.

[0035] Preferably, the orthographic projection of the column portion 21 along the Z direction in the XY plane is circular, that is, the column portion 21 is a cylinder before the limiting groove 211 is opened. The "radial" increase refers to the radial direction of the cylinder. The cylindrical column portion 21 has a simple and reliable structure and is easy to process.

[0036] In one embodiment, the radial recess depth L of the limiting groove 211 is in the range of 1.2 mm ≤ L ≤ 2.0 mm. If L is less than 1.2 mm, the radial depth of the limiting groove 211 is too small, resulting in an excessively small radial dimension of the limiting protrusion 32. The structural strength of the limiting protrusion 32 is poor, and the radial fit between the limiting protrusion 32 and the limiting groove 211 is insufficient. When the pole post 2 is subjected to an external force along the Z direction, the limiting protrusion 32 is easily damaged, causing cracks in the limiting protrusion 32, or even the limiting protrusion 32 may come out of the limiting groove 211, leading to the pole post 2 falling off and failing to play an effective limiting role. If L is greater than 2.0 mm, the radial depth of the limiting groove 211 is too large. After the limiting groove 211 is opened, the cross-sectional area of ​​the remaining solid part of the pole post 21 corresponding to the limiting groove 211 in the XY plane is too small, resulting in poor current carrying capacity, excessive resistance, and excessive temperature rise of the pole post 2 during the charging and discharging process of the battery cell.

[0037] Therefore, by limiting L to a value within the range of 1.2 mm to 2.0 mm, it is possible to ensure that the limiting groove 211 and the limiting protrusion 32 have sufficient matching dimensions in the radial direction, ensuring the injection molding strength of the limiting protrusion 32, preventing cracks in the limiting protrusion 32, and ensuring the connection strength between the electrode post 2 and the injection molded part 3. At the same time, it is possible to avoid the opening of the limiting groove 211 from having an excessive impact on the current carrying capacity of the electrode post 2, thereby avoiding excessive temperature rise of the electrode post 2 during the charging and discharging process of the battery cell and improving the safety performance of the battery cell.

[0038] Optionally, the value of L is any one of 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, or a value between any two of these values.

[0039] It should be noted that the main body 31 of the injection molded part 3 is annular and is sleeved on the outer periphery of the post 21. The main body 31 has an inner ring wall that fits against the outer periphery of the post 21 and an outer ring wall that is radially away from the outer periphery of the post 21. The limiting protrusion 32 is formed by a portion of the inner ring wall of the main body 31 protruding radially. The injection molded part 3 is connected to the pole post 2 at least through the inner ring wall and the limiting protrusion 32. At least a portion of the main body 31 is located on the upper side of the cover plate body 1 and is connected to the upper surface of the cover plate body 1, thereby realizing the fixed connection between the cover plate body 1 and the pole post 2 through the injection molded part 3.

[0040] In one embodiment, further combination Figures 3 to 4 As shown, along the Z-direction, the distance between the upper surface of the column 21 and the lower end face of the limiting groove 211 is H2; where H2 and H1 satisfy the relationship: H1≥0.5×H2. It should be noted that the "upper surface" refers to the upper surface along the Z-direction, and the "lower end face" refers to the lower end face along the Z-direction. Specifically, the lower end face of the limiting groove 211 is the lower one of the two groove sidewalls of the limiting groove 211 arranged opposite each other along the Z-direction; therefore, the upper one of the two groove sidewalls is the upper end face of the limiting groove 211. The limiting groove 211 is formed on the outer peripheral surface of the column 21, and the upper end of the limiting groove 211 is lower than that of the column 21. On the upper surface of 1, H1 is the height of the limiting groove 211 along the Z direction, that is, the distance between the upper end face and the lower end face of the limiting groove 211. H2 is the distance between the upper surface of the column 21 and the lower end face of the limiting groove 211. If H1 is less than 0.5×H2, the groove height of the limiting groove 211 along the Z direction is relatively too small, the fitting dimension between the limiting protrusion 32 and the limiting groove 211 along the Z direction is insufficient, the structural strength of the limiting protrusion 32 along the Z direction is poor, and it is easy to break under stress.

[0041] Therefore, by limiting H1 to be no less than half of H2, the limiting groove 211 has sufficient dimensions along the Z direction, thereby ensuring that the limiting protrusion 32 and the limiting groove 211 have sufficient mating dimensions along the Z direction, avoiding the limiting protrusion 32 from breaking under stress, ensuring the mating strength between the pole post 2 and the injection molded part 3, and thus ensuring the mating strength between the pole post 2 and the cover plate body 1.

[0042] In one embodiment, H2 and H1 satisfy the relationship: H2-H1≥1 mm. It should be noted that H2-H1 refers to the section of the column 21 located above the limiting groove 211 without the limiting groove 211, called the first column section. If H2-H1 is less than 1 mm, the upper end face of the limiting groove 211 is too close to the upper surface of the column 21, the dimension of the first column section along the Z direction is too small, and the structural strength is too poor. The external forces experienced by the electrode post 2 during use include forces along the Z direction. When the electrode post 2 is subjected to a downward external force along the Z direction, there is an interaction force between the first column section and the limiting protrusion 32 along the Z direction. Under this force, the first column section is prone to deformation or breakage, seriously affecting the stability of the electrode post and the safety of the battery cell.

[0043] Therefore, by limiting H2-H1 to be greater than or equal to 1 mm, the column segment of the column 21 located above the limiting groove 211 is guaranteed to have sufficient structural strength, thereby satisfying the fit strength between the pole post 2 and the injection molded part 3, and further satisfying the fit strength between the pole post 2 and the cover plate body 1, thus improving the reliability and safety of the cover plate assembly.

[0044] In one embodiment, the height of the column 21 along the Z direction is H0, where H0 and H1 satisfy the relationship: 0.2≤H1 / H0≤0.6, and the units of H1 and H0 are both mm. If H1 / H0 is less than 0.2, the groove height of the limiting groove 211 is too small relative to the height of the column 21, resulting in insufficient groove height, insufficient dimension of the limiting protrusion 32 along the Z direction, insufficient structural strength, and easy breakage and damage during use; if H1 / H0 is greater than 0.6, the groove height of the limiting groove 211 is too large relative to the height of the column 21, affecting the structural strength of the column 21 itself and the flow capacity of the column 21. Therefore, by limiting the value of H1 / H0 to the range of 0.2 to 0.6, it is possible to ensure that the limiting groove 211 has sufficient groove height, thereby ensuring that the limiting protrusion 32 that cooperates with the limiting groove 211 has sufficient structural strength, avoiding cracking of the limiting protrusion 32, ensuring the connection strength and stability between the injection molded part 3 and the electrode post 2, and also ensuring that the electrode post 2 itself has sufficient structural strength and current carrying capacity, thereby ensuring the reliability of the electrode post 2 and the safety of the battery cell.

[0045] Optionally, the value of H1 / H0 can be any one of 0.2, 0.3, 0.4, 0.5, 0.6 or a value between any two of them.

[0046] In one embodiment, the limiting groove 211 is an annular groove arranged around the axis of the column portion 21. The orthographic projection of the limiting groove 211 along the Z direction in the XY plane is annular. The annular groove is arranged around the axis of the column portion 21. The annular groove structure is simple, easy to process, and conducive to improving molding efficiency and molding yield. It can also make the interaction force between the pole post 2 and the injection molded part 3 evenly distributed along the circumference of the column portion 21, ensuring the uniformity of the force on the column portion 21, and further improving the service life of the column portion 21 and the injection molded part 3. Correspondingly, the limiting protrusion 32 is a limiting protrusion ring arranged around the body of the plastic part 31.

[0047] In one embodiment, further combination Figure 5 As shown, the cover plate body 1 forms a recessed platform 12 around the circumferential edge of the mounting hole 11. The recessed platform 12 is formed by a portion of the upper surface of the cover plate body 1 recessed along the Z direction. The recessed depth of the recessed platform 12 along the Z direction is H3, where the value of H3 is in the range of 0.2 mm ≤ H3 ≤ 0.5 mm. It should be noted that a first protruding ring 311 corresponding to the recessed platform 12 is formed on the lower side of the plastic body 31. The first protruding ring 311 is injection molded on the recessed platform 12 to increase the contact area between the injection molded part 3 and the cover plate body 1, thereby improving the connection strength between the injection molded part 3 and the cover plate body 1. If H3 is less than 0.2 mm, the recess depth of the recessed platform 12 along the Z direction is too small, and the strengthening effect on the connection strength between the injection molded part 3 and the cover plate body 1 is limited. If H3 is greater than 0.5 mm, the recess depth of the recessed platform 12 along the Z direction is too large, resulting in the thickness of the remaining solid part corresponding to the recessed platform 12 along the Z direction on the cover plate body 1 being too small, resulting in poor structural strength of this part, and the cover plate body 1 is prone to deformation or breakage under stress.

[0048] Therefore, by limiting H3 to a value within the range of 0.2 mm to 0.5 mm, the connection strength between the injection molded part 3 and the cover plate body 1 can be effectively improved, and the cover plate body 1 can be guaranteed to have sufficient structural strength, thereby improving the reliability of the cover plate assembly.

[0049] Optionally, the value of H3 is any one of 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, or a value between any two of these values.

[0050] In one embodiment, the width of the countersunk platform 12 in the XY plane is W, where the value of W ranges from 0.9 mm to 1.2 mm. It should be noted that the countersunk platform 12 has an upward-facing countersunk surface, which is annular in the XY plane. W is the annular width of the countersunk surface, and the annular width of the countersunk platform 12 in the XY plane is W. If W is less than 0.9 mm, the countersunk platform 12 is too narrow, making processing difficult, resulting in a low molding yield, and having limited effect on strengthening the connection between the injection molded part 3 and the cover plate body 1. If W is greater than 1.2 mm, the countersunk platform 12 is too wide, significantly damaging the structural strength of the cover plate body 1. Therefore, by limiting W to the range of 0.9 mm to 1.2 mm, it is possible to ensure the smooth processing and molding of the countersunk platform 1, guarantee the molding yield of the cover plate body 1, effectively improve the connection strength between the injection molded part 3 and the cover plate body 1, and also ensure the structural strength of the corresponding position on the cover plate body 1 corresponding to the injection molded part 3, thereby ensuring the reliability of the cover plate assembly.

[0051] Optionally, the value of W is any one of 0.9 mm, 0.95 mm, 1.0 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.2 mm, or a value between any two of these values.

[0052] In one embodiment, the cover plate body 1 has an electrode post area 101 corresponding to the plate portion 22. The thickness of the electrode post area 101 along the Z direction is H4, where the value of H4 ranges from 1.8 mm to 2.0 mm. It should be noted that the electrode post area 101 is an annular region surrounding the mounting hole 11, and the annular width of the electrode post area 101 is greater than the annular width of the countersunk platform 12. The cross-sectional dimension of the plate portion 22 in the XY plane is greater than the cross-sectional dimension of the post portion 21 in the XY plane and the opening size of the mounting hole 11. The electrode post area 101 limits the plate portion 22 along the Z direction. The thickness of the electrode post area 101 along the Z direction is less than the thickness of other locations on the cover plate body 1, so as to make room for the plate portion 22, facilitating the positioning of the plate portion 22 during installation and reducing the space occupied by the plate portion 22 in the housing along the Z direction, thereby improving the energy density of the battery cell. If H4 is less than 1.8 mm, the thickness of the pole post area 101 along the Z direction is too small, resulting in insufficient structural strength. When the pole post 2 is subjected to external force, the pole post area 101 is easily squeezed and deformed, causing the pole post 2 to fall off the cover plate body 1. If H4 is greater than 2.0 mm, the thickness of the pole post area 101 along the Z direction is too large, causing the plate part 22 to occupy too much space inside the shell after the pole post 2 is assembled with the cover plate body 1, reducing the space for setting the pole group inside the shell, which is not conducive to improving the energy density of the cell.

[0053] Therefore, by limiting H4 to a value within the range of 1.8 mm to 2.0 mm, it is possible to ensure that the pole post area 101 has sufficient structural strength, prevent the pole post 2 from falling out of the mounting hole 11, ensure the reliability of the assembly between the cover plate body 1 and the pole post 2, and also improve the energy density of the battery cell.

[0054] Optionally, the value of H4 is any one of 1.8 mm, 1.85 mm, 1.9 mm, 1.95 mm, 2.0 mm, or a value between any two of them.

[0055] In one embodiment, the cover plate assembly further includes a sealing ring 4, which is sleeved on the post portion 21, with its upper surface lower than the lower end face of the limiting groove 211. The injection molded part 3 is located above the sealing ring 4. Here, "upper surface" refers to the upper surface along the Z-direction, and the upper surface of the sealing ring 4 refers to the surface of the sealing ring 4 facing away from the plate portion 22 along the Z-direction. The sealing ring 4 is disposed between the post portion 21 and the cover plate body 1 to ensure the sealing between the post 2 and the cover plate body 1, improving the reliability of the cover plate assembly. By setting the upper surface of the sealing ring 4 lower than the lower end face of the limiting groove 211, the sealing ring 4 is prevented from affecting the molding of the limiting protrusion 32, ensuring the injection molding strength of the limiting protrusion 32.

[0056] In one embodiment, the upper surface of the sealing ring 4 abuts against the lower surface of the pole post area 101. The body 31 of the injection molded part 3 also includes a second convex ring 312. The post 21 also has a second post segment located between the limiting groove 211 and the plate 22. The second convex ring 312 is injection molded in the gap between the hole wall of the mounting hole 11 and the outer peripheral wall of the second post segment. The lower surface of the second convex ring 312 abuts against the upper surface of the sealing ring 4, thereby further improving the connection strength between the injection molded part 3 and the cover plate body, as well as the sealing performance of the cover plate assembly.

[0057] In one embodiment, the injection molded part 3 is a first plastic part, at least a portion of which is located on the upper side of the cover body 1. The cover assembly further includes a second plastic part 5, which is disposed on the lower side of the cover body 1 along the Z direction and adheres to the lower surface of the cover body 1. That is, the second plastic part 5 is located on the side of the cover body 1 facing the inner cavity of the housing, to ensure the insulation between the cover body 1 and the electrode assembly. Specifically, the injection molded part 3 is the upper plastic part, and the second plastic part 5 is the lower plastic part.

[0058] In one embodiment, the cover plate body 1 is further provided with an injection hole 13, which extends through the cover plate body 1 in the Z direction and is used to inject electrolyte into the battery cell. When it is not necessary to inject electrolyte into the battery cell, the injection hole 13 is sealed by a plug.

[0059] In one embodiment, the cover plate body 1 is also provided with an explosion-proof hole, and an explosion-proof valve 6 is installed in the explosion-proof hole. The explosion-proof valve 6 is adapted to open when the gas pressure inside the battery cell reaches a preset value, so as to discharge the gas inside the battery cell and prevent the battery cell from exploding.

[0060] In this embodiment, during assembly, the pole post 2, the cover plate body 1, the second plastic part 5, and the sealing ring 4 are first positioned in a specified location by means of a mold. Then, the plastic is melted and injected into the gap between the pole post 2 and the cover plate body 1 by injection molding. After cooling, the injection molded part 3 is formed for sealing connection.

[0061] According to an embodiment of the present invention, in another aspect, a battery cell is also provided, comprising: a housing, an electrode assembly, and the aforementioned cover plate assembly. The housing has an open end; the electrode assembly is disposed within the inner cavity of the housing; the cover plate assembly covers the open end of the housing. 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 structure. Optionally, the battery cell is a lithium-ion battery cell.

[0062] The following examples and comparative examples verify the influence of different parameter values ​​on the performance of the battery cells. The parameter settings for the examples and comparative examples are shown in Table 1. Battery cells were produced using the parameters of the examples / comparative examples. Five battery cells were randomly selected from each example and comparative example group for terminal push-pull force testing. The detachment of the terminals and whether there were cracks in the injection molded parts were recorded after the test. The test results are shown in Table 2.

[0063] Table 1

[0064] Table 2

[0065] It should be noted that in Table 1, “√” indicates that H1 and H2 satisfy the relationship H1≥0.5×H2, and “×” indicates that H1 and H2 do not satisfy the relationship H1≥0.5×H2.

[0066] As can be seen from Tables 1 to 2, for the battery cells of Examples 1 to 6, all parameters are within the range defined in this application. Five battery cells were randomly selected from each set of examples for terminal push-pull force testing. No terminals fell off, indicating that the injection molding fit dimensions meet the battery cell safety push-pull force requirements.

[0067] For the battery cell of Comparative Example 1, the radial recess depth L of the limiting groove is 1 mm, which is less than the lower limit of L (1.2 mm) defined in this application and is not within the range defined in this application. Five battery cells were randomly selected from Comparative Example 1 for terminal push-pull force testing, and two of them showed cracks at the injection molding location. For the battery cell of Comparative Example 2, L is 2.5 mm, which is greater than the upper limit of L (2.0 mm) defined in this application and is not within the range defined in this application. Five battery cells were randomly selected from Comparative Example 2 for terminal push-pull force testing, and one of them showed cracks at the injection molding location. The injection molding fit dimensions of the battery cells of Comparative Example 1 and Comparative Example 2 do not meet the requirements for safe push-pull force of battery cells.

[0068] For the battery cell in Comparative Example 3, the height H1 of the limiting groove 211 along the Z direction is 0.8 mm, and the distance H2 between the upper surface of the post 21 and the lower end face of the limiting groove 211 is 1.7 mm. The difference between H2 and H1 is 0.9 mm, which is less than 1 mm, and H1 and H2 do not satisfy the relationship H1≥0.5×H2, which is outside the scope defined in this application. Five battery cells from Comparative Example 3 were sampled for terminal push-pull force testing. Three of these cells showed cracks at the injection molding area, indicating that the injection molding dimensions did not meet the battery cell safety push-pull force requirements.

[0069] For the battery cell of Comparative Example 4, the ratio L / H1 between the radial recess depth L of the limiting groove 211 and the height H1 of the limiting groove 211 in the Z direction is 0.4, which is less than 1 / 2 of the lower limit of L / H1 defined in this application and is not within the range defined in this application. Five battery cells were randomly selected from Comparative Example 4 for terminal push-pull force test. One of them had a crack in the injection molding part, and one terminal fell off. The injection molding fit dimensions did not meet the safety push-pull force requirements of the battery cell.

[0070] For the battery cell of Comparative Example 5, the value of H1 / H0 is 0.1, which is less than the lower limit of H1 / H0 of 0.2 as defined in this application and is not within the range defined in this application. Five battery cells were randomly selected from Comparative Example 5 for terminal push-pull force test. Three of them showed cracks in the injection molding part, and the injection molding fit dimensions did not meet the battery cell safety push-pull force requirements.

[0071] For the battery cell of Comparative Example 6, the thickness H4 of the terminal region 101 along the Z direction is 1 mm, which is less than the lower limit of H4 of 1.8 mm as defined in this application and is not within the range defined in this application. Five battery cells were randomly selected from Comparative Example 6 for terminal push-pull force test, and five of them fell off. The injection molding fit dimensions do not meet the safety push-pull force requirements of the battery cell.

[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 mounting holes; The pole includes a pole portion and a plate portion. The pole portion passes through the mounting hole, and the plate portion is located on the lower side of the cover plate body along the Z direction. The pole portion has an outer peripheral surface that is radially opposite to the axis of the pole portion. A limiting groove is formed on the outer peripheral surface of the pole portion. The radial depth of the limiting groove is L, and the height of the limiting groove along the Z direction is H1. The relationship between L and H1 is: 1 / 2≤L / H1≤2 / 3. An injection molded part is formed between the column and the cover plate body. The injection molded part includes a plastic part body and a limiting protrusion. The plastic part body is sleeved on the column. At least a portion of the plastic part body is located on the upper side of the cover plate body and connected to the upper surface of the cover plate body. The limiting protrusion is fixedly connected to the plastic part body and is inserted into the limiting groove.

2. The cover plate assembly according to claim 1, characterized in that, The radial recess depth L of the limiting groove is in the range of 1.2 mm ≤ L ≤ 2.0 mm.

3. The cover plate assembly according to claim 1, characterized in that, Along the Z direction, the distance between the upper surface of the column and the lower end face of the limiting groove is H2; Among them, H2 and H1 satisfy the following relationship: H1≥0.5×H2; And / or, H2 and H1 satisfy the relationship: H2-H1≥1 mm.

4. The cover plate assembly according to claim 1, characterized in that, The height of the column along the Z direction is H0, where H0 and H1 satisfy the relationship: 0.2≤H1 / H0≤0.

6.

5. The cover plate assembly according to claim 1, characterized in that, The limiting groove is an annular groove arranged around the axis of the column.

6. The cover plate assembly according to claim 1, characterized in that, The cover plate body forms a recessed platform around the circumferential edge of the mounting hole. The recessed platform is formed by a portion of the upper surface of the cover plate body recessed along the Z direction. The recess depth of the platform along the Z direction is H3, where the value of H3 is in the range of 0.2 mm ≤ H3 ≤ 0.5 mm.

7. The cover plate assembly according to claim 6, characterized in that, The width of the settling platform in the XY plane is W, where the value of W ranges from 0.9 mm to 1.2 mm.

8. The cover plate assembly according to claim 1, characterized in that, The cover plate body has a pole post area corresponding to the plate portion, and the thickness of the pole post area along the Z direction is H4, wherein the value of H4 is in the range of 1.8 mm ≤ H4 ≤ 2.0 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 portion, and the upper surface of the sealing ring is lower than the lower end face of the limiting groove, and the injection molded part is located above the sealing ring.

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.

Images