Cover plate structure and battery cell

Abstract

The application relates to the technical field of batteries and discloses a cover plate structure and a battery cell, the cover plate structure comprising: a cover plate body provided with a pole hole; a pole comprising a pole body and a bottom plate, the bottom plate being located on one side of the cover plate body along a Z direction, the pole body being arranged in the pole hole, the pole body having a first axis extending along the Z direction and an outer circumferential surface radially away from the first axis, a groove being arranged on the outer circumferential surface of the pole body, the groove being at least part of an annular groove surrounding the first axis, the inner ring of the annular groove having a diameter of g, the pole body comprising a first pole segment located on the side of the groove away from the bottom plate, the first pole segment having a diameter of G, wherein the relationship between g and G satisfies the formula: 0.7 <= g / G <= 0.9; a first plastic part comprising a plastic part body and a protruding part, the plastic part body being sleeved on the pole body and connected with the cover plate body, the protruding part being connected to the inner ring of the plastic part body and inserted into the groove. The connection stability between the first plastic part and the pole is improved.

Description

Technical Field

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

[0002] The battery cell mainly consists of a casing, a cover structure, and electrode assemblies. The cover structure covers the open end of the casing, and after assembly, the casing and cover structure form a sealed space to accommodate the electrode assemblies. The cover structure includes components such as the cover body, electrode posts, upper plastic parts, and lower plastic parts. The electrode posts pass through electrode post holes on the cover body, and the upper plastic parts connect the electrode posts and the cover body to ensure the sealing and insulation between the electrode posts and the cover body.

[0003] However, the upper plastic part is connected around the outer periphery of the electrode post. The connection stability between the plastic part and the electrode post is poor. When the battery cell is subjected to external force during use, the connection between the electrode post and the plastic part is prone to loosening, causing the plastic part to fall off the electrode post along the electrode post axis. This affects the airtightness and connection stability between the plastic part and the electrode post, and thus seriously affects the safety of the battery cell. Summary of the Invention

[0004] This invention provides a cover plate structure and a battery cell to solve the problem of poor connection stability between the plastic part and the electrode post.

[0005] In a first aspect, the present invention provides a cover plate structure, comprising: a cover plate body having an electrode post hole; an electrode post, comprising a column body and a base plate, the base plate being located on one side of the cover plate body along the Z direction, the column body passing through the electrode post hole, the column body having a first axis extending along the Z direction and an outer peripheral surface radially away from the first axis, a groove being formed on the outer peripheral surface of the column body, the groove being at least a portion of an annular groove surrounding the first axis, the diameter of the inner ring of the annular groove being g, the column body including a first column segment located on the side of the groove away from the base plate, the diameter of the first column segment being G, wherein g and G satisfy the relationship: 0.7≤g / G≤0.9; a first plastic part, comprising a plastic part body and a protrusion, the plastic part body being sleeved on the column body and connected to the cover plate body, the protrusion being connected to the inner ring of the plastic part body, and the protrusion being inserted into the groove.

[0006] Beneficial effects: By creating grooves on the outer circumference of the electrode post and providing corresponding protrusions on the first plastic part, the protrusions and grooves are interlocked, achieving axial mutual positioning between the first plastic part and the electrode post, thus improving the connection stability between them. Simultaneously, by limiting the ratio between the inner ring diameter g of the annular groove and the diameter G of the first segment of the post to within the range of 0.7 to 0.9, the groove has a reasonable radial depth. This prevents the protrusion from detaching from the groove, thus avoiding relative displacement between the first plastic part and the electrode post, preventing cracking and damage to the first plastic part, and ensuring airtightness between them. Furthermore, it avoids excessive influence of the groove on the internal resistance of the electrode post, thus preventing excessive temperature differences between the upper and lower surfaces of the electrode post. This ensures the accuracy of temperature acquisition by the temperature sensing device on the upper surface of the electrode post, thereby improving the safety of the battery cell.

[0007] In one optional implementation, the diameter G of the first column segment is in the range of 8 mm ≤ G ≤ 20 mm.

[0008] Beneficial effects: It can ensure that the terminal has sufficient structural strength, thereby ensuring the reliability of the terminal and improving the safety of the battery cell. It can also avoid excessive weight of the terminal, which is conducive to improving the energy density of the battery cell and saving costs.

[0009] In one alternative embodiment, the number of grooves is one, or the number of grooves is multiple, and the multiple grooves are distributed circumferentially along the column in the XY plane.

[0010] Beneficial effects: The number of grooves is only one, the structure is simple, it is easy to process and form the grooves, and improves production efficiency; or, by setting multiple grooves and distributing them circumferentially around the column, the force on the column in the circumferential direction can be more uniform, avoiding the local structural strength of the column from decreasing due to a single groove, thereby ensuring the reliability of the pole. At the same time, the cooperation of multiple grooves and multiple protrusions in the circumferential direction can also effectively prevent circumferential rotation between the first plastic part and the column, further improving the reliability and firmness of the connection between the two.

[0011] In one optional embodiment, the perimeter of the column in the XY plane is M, and the total arc length of the opening side of the groove in the XY plane is m, wherein m and M satisfy the relationship: 0.6≤m / M≤1.

[0012] Beneficial effects: It ensures the reasonable arc length of the groove along the circumference of the column, guarantees sufficient fit between the first plastic part and the pole post along the circumference of the column, prevents the protrusion from coming out of the groove, thereby preventing relative displacement between the first plastic part and the pole post, improving the torsional resistance of the pole post, preventing cracking and damage to the first plastic part, ensuring the airtightness between the first plastic part and the pole post, and ensuring the stability of the connection between the first plastic part and the pole post.

[0013] In one optional implementation, the perimeter M of the cylinder in the XY plane is in the range of 25 mm ≤ M ≤ 63 mm.

[0014] Beneficial effects: It enables the pole to have reasonable circumferential dimensions, which can ensure that the pole has sufficient structural strength, thereby ensuring the reliability of the pole and improving the safety of the cell. It can also avoid excessive weight of the pole, which is conducive to improving the energy density of the cell and saving costs.

[0015] In one optional embodiment, the height of the groove along the Z direction is h, wherein the value of h ranges from 0.5 mm to h to 2 mm.

[0016] Beneficial effects: The groove has a reasonable height along the Z direction, which 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 groove provides sufficient fitting height for the protrusion of the first plastic part, ensuring that the protrusion has sufficient structural strength, improving the stability of the connection between the first plastic part and the electrode post, thereby ensuring the airtightness between the two and improving the safety of the battery cell.

[0017] In one alternative implementation, the number of grooves is N, where 1 ≤ N ≤ 4.

[0018] Beneficial effects: It facilitates the processing and shaping of grooves, improves processing efficiency, and avoids the individual grooves being too small in circumferential dimension along the pole post, thereby ensuring that the protrusions that mate with the grooves have sufficient structural strength and improving the connection stability between the first plastic part and the pole post.

[0019] In one alternative embodiment, the pole post and the cover plate body are spaced apart, and the first plastic part is injection molded between the pole post and the cover plate body.

[0020] Beneficial effects: Injection molding is a relatively simple and easy-to-operate method with low cost. The first plastic part can fully fill the gap between the pole and the cover plate body. After the first plastic part solidifies, it is tightly connected to the pole and the cover plate body, which helps to ensure the sealing and insulation between the pole and the cover plate body and has high reliability.

[0021] In one optional embodiment, the cover plate structure further includes a sealing ring, which is sleeved on the column and located below the first plastic part along the Z direction, with at least a portion of the sealing ring sandwiched between the cover plate body and the bottom plate.

[0022] Beneficial effect: Further ensures the sealing between the pole and the cover plate body.

[0023] Secondly, the present invention also provides a battery cell, comprising: a housing having an open end; an electrode assembly disposed within the inner cavity of the housing; and the aforementioned cover plate structure, the cover plate structure covering the open end of the housing. Since the battery cell includes the cover plate structure and has the same effect as the cover plate structure, it will not be described in detail here. Attached Figure Description

[0024] 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.

[0025] Figure 1 This is a schematic diagram of a cover plate structure according to an embodiment of the present invention; Figure 2 for Figure 1 The diagram shown is an exploded view of the cover plate structure. Figure 3 for Figure 1 The top view of the cover plate structure shown; Figure 4 for Figure 3 A cross-sectional view along the AA direction; Figure 5 for Figure 3 Cross-sectional view along the BB direction; Figure 6 for Figure 1 A schematic diagram of the cover plate structure shown from a bottom view. Figure 7 This is a schematic diagram of the structure of a pole post according to an embodiment of the present invention; Figure 8 for Figure 7 The front view of the pole column is shown; Figure 9 This is a schematic diagram of the structure of a first plastic part according to an embodiment of the present invention; Figure 10 for Figure 9 A structural schematic diagram of the first plastic part shown from a bottom-view perspective; Figure 11This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures: 1. Cover plate body; 11. Pole post hole; 12. Injection hole; 13. Pressure relief hole; 2. Pole post; 21. Post body; 211. Groove; 212. First post section; 213. Slotted section; 214. Second post section; 22. Base plate; 3. First plastic part; 301. First through hole; 31. Plastic part body; 32. Protrusion; 4. Sealing ring; 5. Second plastic part; 51. Second through hole; 6. Pressure relief valve; 7. Pressure relief valve patch; 8. Housing. Detailed Implementation

[0027] 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.

[0028] The battery cell mainly consists of a casing, a cover structure, and electrode assemblies. The cover structure covers the open end of the casing, and after assembly, the casing and cover structure form a sealed space to accommodate the electrode assemblies. The cover structure includes a cover body, electrode posts, an upper plastic part, and a lower plastic part. The electrode posts pass through electrode post holes on the cover body, and the upper plastic part connects the electrode posts and the cover body to ensure the sealing and insulation between the electrode posts and the cover body. The electrode posts protrude from the surface of the cover body, and a busbar is usually welded to the side of the electrode posts facing away from the casing. The busbar is used to realize the electrical connection between battery cells or between the battery cells and external circuits. The upper plastic part is sleeved on the outer periphery of the terminal post. The connection stability between the plastic part and the terminal post is poor. When the battery cell is subjected to external forces during use, the bus and other structures will exert forces on the terminal post, making it easy for the terminal post and the plastic part to loosen. In particular, the force along the Z direction will pull the terminal post, causing the terminal post and the plastic part to move relative to each other. This will cause the plastic part to fall off the terminal post along the axial direction, affecting the airtightness and connection stability between the plastic part and the terminal post, and thus seriously affecting the safety of the battery cell.

[0029] The following is combined with Figures 1 to 11 The following describes embodiments of the present invention.

[0030] According to an embodiment of the present invention, in one aspect, a cover plate structure is provided, such as... Figures 1 to 10As shown, the cover plate structure 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 11; the electrode post 2 includes a post body 21 and a base plate 22. The base plate 22 is located on one side of the cover plate body 1 along the Z direction. The post body 21 passes through the electrode post hole 11. The post body 21 has a first axis extending along the Z direction and an outer peripheral surface radially away from the first axis. A groove 211 is formed on the outer peripheral surface of the post body 21. The groove 211 is at least a part of an annular groove surrounding the first axis. The diameter of the inner ring of the annular groove is g. The post body 21 includes a positioning... The first column segment 212 on the side of the groove 211 away from the bottom plate 22 has a diameter of G, where g and G satisfy the relationship: 0.7≤g / G≤0.9, and the units of g and G are both mm; the first plastic part 3 includes a plastic part body 31 and a protrusion 32. The plastic part body 31 is sleeved on the column 21 and connected to the cover plate body 1. The protrusion 32 is connected to the inner ring of the plastic part body 31 and is inserted into the groove 211.

[0031] It should be noted that the cover plate structure has three perpendicular directions (X, Y, and Z) to form a rectangular coordinate system. The intersection of the X and Y directions forms the XY plane. Here, the X direction refers to... Figure 1 The direction indicated by the middle arrow ("X") is the direction of the Y direction. Figure 1 The direction indicated by the middle arrow (Y) is the same as the direction indicated by the Z arrow (Z). Figure 1 The direction indicated by the middle arrow "Z" specifically refers to the length direction of the cover plate structure, the width direction of the cover plate structure, and the thickness direction of the cover plate structure. Column 21 is a cylinder, and its orthographic projection along the Z direction in the XY plane is a circle. Radial refers to the radial direction of the cylinder, that is, the direction perpendicular to the Z direction and passing through the first axis of column 21.

[0032] It should be noted that the groove 211 is formed by a radially recessed area on a portion of the outer circumferential surface of the column 21. The groove 211 has a groove bottom surface that is radially close to the first axis and two groove sidewalls that are arranged opposite each other along the Z direction. The groove sidewall located at the top along the Z direction is spaced apart from the upper surface of the column 21. Preferably, the groove 211 is located in the middle part of the column 21 along the Z direction. The column segment on the column 21 with the groove 211 is called the slotted segment 213. The column segment on the column 21 connected to the side of the slotted segment 213 away from the bottom plate 22 is called the first column segment 212. The column segment on the column 21 connected between the slotted segment 213 and the bottom plate 22 is called the second column segment 214. Define the orthographic projection of the annular groove along the Z direction in the XY plane as the first annulus. The side of the first annulus closest to the first axis is the inner ring. At least a portion of the first annulus along its circumference is a segment on the circular ring. At least a portion of the inner ring of the first annulus is an arc segment, and the diameter of the circle containing the arc segment is g. That is, at least a portion of the annular groove is a circular segment, and the diameter of the circle containing the inner ring of the circular segment is g. At least a portion of the groove 211 is located on the circular segment of the annular groove. g is also the radial portion of the remaining portion after the groove 211 is opened on the column 21 and the annular groove. The diameter of the corresponding position of the annular segment; the first column segment 212 is a cylindrical segment, and G is the diameter of the first column segment 212 without the groove 211; the plastic body 31 is annular, and the plastic body 31 has a first through hole 301. The inner ring of the plastic body 31 is the hole wall of the first through hole 301. The protrusion 32 is formed by a part of the hole wall of the first through hole 301 extending radially toward the center of the first through hole 301. The protrusion 32 of the first plastic part 3 is inserted and matched with the groove 211 to realize the axial positioning between the first plastic part 3 and the pole post 2.

[0033] When the pole post 2 is subjected to an external force along the Z direction, the first plastic part 3 restricts the movement of the pole post 2 relative to the first plastic part 3 along the Z direction through the engagement of the protrusion 32 and the groove 211. If g / G is greater than 0.9, the diameter of the slotted section 213 of the column 21 is too large relative to the diameter of the first column section 212, the radial depth of the groove 211 is too small, and the radial fit between the protrusion 32 and the groove 211 is too small. The protrusion 32 is prone to dislodging from the groove 211 when subjected to external force, making it difficult to play an effective limiting role. The airtightness between the parts is compromised, and even cracking and damage to the first plastic part 3 may occur. The greater the radial depth of the groove 211, the smaller g becomes. If g / G is less than 0.7, the diameter of the slotted section 213 is too small relative to the diameter of the first column section 212, resulting in excessive resistance and temperature rise in the slotted section 213. This leads to an excessive temperature difference between the upper and lower surfaces of the terminal post 2 during normal charging and discharging of the battery cell. The battery pack will set a temperature sensor on the upper surface of the battery cell terminal post to collect the temperature. If the temperature difference between the upper and lower surfaces of the terminal post 2 is too large, it will lead to inaccurate temperature monitoring, which is not conducive to ensuring the safety of the battery cell. Here, the upper surface refers to the upper surface along the Z direction, that is, the surface on the side away from the housing 8 along the Z direction, and the lower surface refers to the lower surface along the Z direction, that is, the surface on the side facing the inner cavity of the housing 8 along the Z direction.

[0034] By applying the cover plate structure of this embodiment, a groove 211 is formed on the outer peripheral surface of the pole post 2, and a corresponding protrusion 32 is provided on the first plastic part 3. The protrusion 32 and the groove 211 are inserted into each other, thereby achieving axial mutual positioning between the first plastic part 3 and the pole post 2 and improving the connection stability between the first plastic part 3 and the pole post 2. At the same time, by limiting the ratio between the diameter g of the inner ring of the annular groove where the groove 211 is located and the diameter G of the first column segment 212 on the side of the column body 21 located away from the bottom plate 22 of the groove 211 to be in the range of 0.7 to 0.9. The inner value is selected so that the groove 211 has a reasonable recess depth in the radial direction. This can prevent the protrusion 32 from falling out of the groove 211, thereby preventing relative displacement between the first plastic part 3 and the pole post 2, preventing the first plastic part 3 from cracking and being damaged, and ensuring the airtightness between the first plastic part 3 and the pole post 2. It can also prevent the opening of the groove 211 from having an excessive impact on the internal resistance of the pole post 2, thereby preventing an excessive temperature difference between the upper and lower surfaces of the pole post 2, ensuring the accuracy of the temperature acquisition device on the upper surface of the pole post in acquiring the pole post temperature, and thus improving the safety of the battery cell.

[0035] Optionally, the value of g / G is any one of 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9 or a value between any two of these values.

[0036] In one embodiment, the diameter G of the first post segment 212 is in the range of 8 mm ≤ G ≤ 20 mm. If G is less than 8 mm, the diameter of the first post segment 212 is too small, resulting in insufficient structural strength and easy deformation and damage during use. If G is greater than 20 mm, the diameter of the first post segment 212 is too large, leading to excessive weight, which is detrimental to achieving lightweighting of the battery cell and improving its energy density, while also increasing costs. Therefore, by limiting G to the range of 8 mm to 20 mm, it is possible to ensure that the first post segment 212 has sufficient structural strength, thereby ensuring the reliability of the electrode post 2 and improving the safety of the battery cell. Simultaneously, it is possible to avoid excessive weight of the electrode post 2, which is beneficial for improving the energy density of the battery cell and saving costs.

[0037] Optionally, the value of G is any one of 8 mm, 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, or a value between any two of these values.

[0038] In one embodiment, the column segment located between the groove 211 and the base plate 22 on the column 21 is the second column segment 214. The diameter of the second column segment 214 is equal to the diameter of the first column segment 212, which facilitates the processing and forming of the column 21. The first column segment 212, the grooved segment 213, and the second column segment 214 are fixedly connected in sequence, and the dividing line between the first column segment 212, the grooved segment 213, and the second column segment 214 is as follows: Figure 5 As shown by the dashed line in the image.

[0039] In one embodiment, the number of grooves 211 is one, which is simple in structure, facilitates the processing and forming of grooves 211, and improves production efficiency.

[0040] In other embodiments, the number of grooves 211 is multiple, and the number of protrusions 32 on the first plastic part 3 is equal to and corresponds one-to-one with the number of grooves 211. The multiple grooves 211 are distributed circumferentially around the column 21 in the XY plane. By setting multiple grooves 211 circumferentially distributed around the column 21, the force on the column 21 in the circumferential direction can be more uniform, thereby ensuring the reliability of the pole post 2. Simultaneously, the circumferential cooperation between the multiple grooves 211 and the multiple protrusions 32 can effectively prevent circumferential rotation between the first plastic part 3 and the column 21, further improving the reliability and firmness of the connection. Preferably, the multiple grooves 211 are evenly distributed circumferentially around the column 21 in the XY plane to further improve the uniformity of force distribution. Here, "multiple" refers to two or more (including two).

[0041] In one embodiment, the perimeter of the column 21 in the XY plane is M, and the total arc length of the opening side of the groove 211 in the XY plane is m, where m and M satisfy the relationship: 0.6≤m / M≤1, and the units of m and M are both mm. It should be noted that the column 21 is a cylinder, M=π×G; the opening side of the groove 211 is located on the outer circumference of the column 21, and the arc length of the opening side of the groove 211 in the XY plane is at least a portion of the perimeter M of the column 21 in the XY plane; m will not be greater than M. When there is only one groove 211 and the groove 211 is an annular groove that completes a full circle around the column 21, m=M; when there are one or more grooves 211, when there is only one groove 211, m is the arc length corresponding to the opening side of that groove 211; when there are multiple grooves 211, m is equal to the sum of the arc lengths corresponding to the opening sides of each of the multiple grooves 211. If m / M is less than 0.6, the dimension of the groove 211 along the circumference of the column is too small relative to the circumference of the column 21. The fit dimension between the groove 211 and the protrusion 32 along the circumference of the pole post is too small, making it difficult to play an effective limiting role. The protrusion 32 is easy to come out of the groove 211 when subjected to external force, and the airtightness between the first plastic part 3 and the pole post 2 is damaged. In some cases, the first plastic part 3 may even crack and be damaged due to stress concentration.

[0042] Therefore, by limiting m / M to a value within the range of 0.6 to 1, the reasonableness of the arc length of the groove 211 along the circumference of the column 21 is ensured, guaranteeing sufficient fitting dimensions between the first plastic part 3 and the pole post 2 along the circumference of the column, preventing the protrusion 32 from coming out of the groove 211, thereby preventing relative displacement between the first plastic part 3 and the pole post 2, improving the torsional resistance of the pole post 2, preventing the first plastic part 3 from cracking and being damaged, ensuring the airtightness between the first plastic part 3 and the pole post 2, and ensuring the stability of the connection between the first plastic part 3 and the pole post 2.

[0043] Optionally, the value of m / M is any one of 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, or a value between any two values.

[0044] In one embodiment, the perimeter M of the column 21 in the XY plane ranges from 25 mm to 63 mm. If M is less than 25 mm, the perimeter of the column 21 in the XY plane is too small, resulting in insufficient cross-sectional area and structural strength, making it prone to deformation and damage during use. If M is greater than 63 mm, the perimeter of the column 21 in the XY plane is too large, resulting in excessive cross-sectional area, diameter, and weight, which is detrimental to achieving lightweighting and improving energy density of the battery cell, and also increases cost. Therefore, by limiting M to the range of 25 mm to 63 mm, the column 21 has a reasonable circumferential dimension. This ensures sufficient structural strength for the electrode post 2, thereby guaranteeing its reliability and improving the safety of the battery cell, while also preventing excessive weight, which is beneficial for improving the energy density of the battery cell and saving costs.

[0045] Optionally, the value of M is any one of 25 mm, 25.12 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 62.8 mm, 63 mm, or a value between any two of these values.

[0046] In one embodiment, further combination Figure 5 As shown, the height of the groove 211 along the Z direction is h, where the value of h ranges from 0.5 mm to 2 mm. It should be noted that h is the groove height on the electrode post 2. The groove height affects the temperature of the upper and lower surfaces of the electrode post 2 during normal charging and discharging of the battery cell. If h is greater than 2 mm... If h is less than 0.5 mm, the height of the groove 211 along the Z direction is too large, the cross-sectional area of ​​the grooved section 213 is small, the resistance is large, and the heat generated during charging and discharging is large. The excessive size of the grooved section 213 along the Z direction will lead to an excessive temperature difference between the upper and lower surfaces of the terminal post 2 during normal charging and discharging of the battery, which will result in inaccurate temperature collection by the temperature acquisition device set on the upper surface of the terminal post 2, which is not conducive to ensuring the safety of the cell. If h is less than 0.5 mm, the groove height is too small, the size of the groove 211 along the Z direction is insufficient, the fitting height with the protrusion 32 of the first plastic part 3 is insufficient, the size of the protrusion 32 along the Z direction is too small, the structural strength is insufficient, and it is easy for the terminal post 2 to deform or crack when subjected to force along the Z direction, or even detach from the groove 211, making it difficult to play an effective limiting role, causing the first plastic part 3 and the terminal post 2 to become relatively loose, making it difficult to ensure the airtightness between the first plastic part 3 and the terminal post 2.

[0047] Therefore, by limiting h to a value within the range of 0.5 mm to 2 mm, the 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 the temperature monitoring device installed on the upper surface of the electrode post 2, but also ensures that the 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, 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.

[0048] Optionally, the value of h is any one of 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, or a value between any two of these values.

[0049] In one embodiment, the dimension of the electrode post 2 along the Z direction is h0, that is, the distance between the upper and lower surfaces of the electrode post 2 along the Z direction is h0, where the value of h0 ranges from 5 mm to 10 mm. By limiting the dimension h0 of the electrode post 2 along the Z direction to a reasonable range, the electrode post 2 has a reasonable height along the Z direction, which can ensure that the electrode post 2 has sufficient structural strength and avoid excessive weight, thereby improving the reliability of the cover structure and the energy density of the battery cell.

[0050] Optionally, the value of h0 is any one of 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or a value between any two of these values.

[0051] In one embodiment, the dimension of the base plate 22 along the Z direction is h1, where the value of h1 ranges from 1 mm to 2 mm. If h1 is less than 1 mm, the base plate 22 is too thin, resulting in poor structural strength and making it prone to deformation when the pole post 2 is subjected to external forces along the Z direction, thus affecting the sealing between the pole post 2 and the cover plate body 1. If h1 is greater than 2 mm, the base plate 22 is too thick, occupying too much space inside the casing along the Z direction, which is not conducive to improving the energy density of the battery cell. Therefore, by limiting the dimension h1 of the base plate 22 along the Z direction to a range of 1 mm to 2 mm, it is possible to ensure that the base plate 22 has sufficient structural strength, preventing deformation during use and thus ensuring the sealing between the pole post 2 and the cover plate body 1, improving the reliability and safety of the battery cell. It is also possible to avoid the base plate 22 occupying too much internal space of the battery cell along the Z direction, thereby improving the energy density of the battery cell. It should be noted that the base plate 22 is fixedly connected to the pole body 21, and the boundary line between the base plate 22 and the pole body 21 is as follows: Figure 5 As shown by the dashed line.

[0052] Optionally, the value of h1 is any one of 1 mm, 1.2 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.8 mm, 2 mm, or a value between any two of these values.

[0053] In one embodiment, the number of grooves 211 is N, where 1 ≤ N ≤ 4, and N is a positive integer. If N is greater than 4, the number of grooves 211 is too large, the structure is relatively complex, the processing difficulty increases, which is not conducive to improving processing efficiency. Furthermore, it will result in a smaller circumferential dimension of each groove 211 along the pole post, and a smaller circumferential dimension of the protrusion 32 that mates with the groove 211, which is not conducive to ensuring the structural strength of the protrusion 32 and makes it prone to breakage during use. Therefore, by limiting the number of grooves 211 to between 1 and 4, it is easier to process and shape the grooves 211, improving processing efficiency, while avoiding an excessively small circumferential dimension of a single groove 211 along the pole post. This ensures that the protrusion 32 that mates with the groove 211 has sufficient structural strength, improving the connection stability between the first plastic part 3 and the pole post 2.

[0054] Optionally, the number of grooves 211 can be 1, 2, 3, or 4. When the number of grooves 211 is greater than 1, it is preferable that multiple grooves 211 are evenly distributed along the circumference of the pole post 2. Symmetrical slotting is preferred.

[0055] In one embodiment, the electrode post 2 and the cover plate body 1 are spaced apart, and the first plastic part 3 is injection molded between the electrode post 2 and the cover plate body 1. The injection molding method is relatively simple, easy to operate, and low in cost. Moreover, the first plastic part 3 can fully fill the gap between the electrode post 2 and the cover plate body 1. After the first plastic part 3 solidifies, it is tightly connected to the electrode post 2 and the cover plate body 1, which helps to ensure the sealing and insulation between the electrode post 2 and the cover plate body 1, resulting in high reliability.

[0056] In one embodiment, the upper surface of the cover plate body 1 is further provided with a plurality of protrusions arranged circumferentially around the pole hole, and the lower surface of the plastic body 31 of the first plastic part 3 has a recess corresponding to the protrusions. The protrusions are inserted into the recesses to achieve circumferential positioning between the first plastic part 3 and the cover plate body 1, thereby further improving the connection reliability between the first plastic part 3 and the cover plate body 1.

[0057] In one embodiment, the cover plate structure further includes a sealing ring 4, which is sleeved on the post 21 and located below the first plastic part 3 along the Z direction. At least a portion of the sealing ring 4 is sandwiched between the cover plate body 1 and the base plate 22. The lower surface of the sealing ring 4 abuts against the upper surface of the base plate 22, and the sealing ring 4 is press-fitted between the cover plate body 1 and the base plate 22 to further ensure the sealing between the pole post 2 and the cover plate body 1. The first plastic part 3 is injection molded between the pole post 2 and the cover plate body 1 and is located above the sealing ring 4.

[0058] In one embodiment, the cover plate structure further includes a second plastic part 5, which is disposed on the lower side of the cover plate body 1 and fits against the lower surface of the cover plate body 1 to ensure insulation between the cover plate body 1 and the electrode assembly. The second plastic part 5 has a second through hole 51 for the post 21 to pass through. The second plastic part 5 extends around the circumferential edge of the second through 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.

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

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

[0061] According to an embodiment of the present invention, in another aspect, a battery cell is also provided, such as... Figure 11 As shown, the battery cell includes: a housing 8, an electrode assembly, and the aforementioned cover plate structure. The housing 8 has an open end; the electrode assembly is placed in the inner cavity of the housing 8; the cover plate structure covers the open end of the housing 8. The electrode assembly includes an electrode assembly body and a tab, the tab being connected to one end of the electrode assembly body along the Z direction, and the tab being electrically connected to the terminal post in the cover plate structure.

[0062] Optionally, the battery cell is a lithium-ion battery cell.

[0063] The following examples and comparative examples verify the influence of different parameter values ​​on the cover plate structure. The parameter settings for the examples and comparative examples are shown in Table 1, and the corresponding verification results are shown in Table 2. The test items are as follows: 1. Thrust test of pole performance: 1) Perform a Z-direction ultimate thrust test on the pole post, requiring the Z-direction ultimate thrust of the pole post to be greater than 1500N; 2) Perform thrust tests on the pole in the X / Y / Z directions. The pole must be able to withstand a force of 1000 N / 10 cycles in each of the X / Y / Z directions. After the thrust test, the first plastic part should not crack, and the airtightness should meet the requirements (leakage rate < 1 × 10⁻⁷ / Pa.m). 3 / s); 2. Temperature rise: Simulation analysis of the temperature of the upper and lower surfaces of the terminals during constant current and constant voltage charging and discharging of the battery, requiring the temperature difference between the upper and lower surfaces to be within 5℃.

[0064] Table 1

[0065] Table 2

[0066] In Table 2, OK indicates qualified and NG indicates unqualified.

[0067] As can be seen from Tables 1 to 2, for the cover plate structures of Examples 1 to 12, all parameters are within the range defined in this application, meet the requirements of the pole thrust test, and the temperature difference between the upper and lower surfaces of the pole does not exceed 5°C, which meets the requirements. The cover plate structure is qualified and has good performance.

[0068] For the cover structure of Comparative Example 1, the g / G value is 0.639, which is less than the lower limit of 0.7 defined in this application and is not within the range defined in this application. Although it meets the requirements for the pole thrust test, the temperature difference between the upper and lower surfaces of the pole is 6.8℃, which is greater than 5℃, and therefore does not meet the requirements. For the cover structure of Comparative Example 2, the g / G value is 0.954, which is greater than the upper limit of 0.9 defined in this application and is not within the range defined in this application. Although the temperature difference between the upper and lower surfaces of the pole does not exceed 5℃, it does not meet the requirements for the pole thrust test and is therefore unqualified. It can be seen that when g / G is within the range of 0.7 to 0.9 defined in this application, the pole can meet the thrust test requirements, and the temperature difference between the upper and lower surfaces of the pole does not exceed 5℃, ensuring the connection stability between the pole 2 and the first plastic part 3 and the accuracy of temperature acquisition.

[0069] For the cover plate structures of Comparative Examples 3 and 4, the values ​​of m / M are 0.597 and 0.546, respectively, both less than the lower limit of 0.6 defined in this application. Therefore, they are outside the range defined in this application and do not meet the requirements for the pole thrust test, thus failing the test. It is evident that when m / M takes a value within the range of 0.6 to 1 defined in this application, the pole can be guaranteed to meet the thrust test requirements.

[0070] For the cover plate structure of Comparative Example 5, the value of h is 0.45 mm, which is less than the lower limit of h (0.5 mm) defined in this application and is outside the range defined in this application. Therefore, it does not meet the requirements for the pole thrust test and is unqualified. For the cover plate structure of Comparative Example 6, the value of h is 2.55 mm, which is greater than the upper limit of h (2 mm) defined in this application and is outside the range defined in this application. The temperature difference between the upper and lower surfaces of the pole is 5.7℃, which is greater than 5℃ and does not meet the requirements. It can be seen that when h is taken within the range of 0.5 mm to 2 mm defined in this application, the pole can meet the thrust test requirements, and the temperature difference between the upper and lower surfaces of the pole does not exceed 5℃, ensuring the connection stability between the pole 2 and the first plastic part 3 and the accuracy of temperature acquisition.

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

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

[0073] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A cover plate structure, characterized in that, include: The cover plate body has pole hole; An electrode post includes a post body and a base plate. The base plate is located on one side of the cover plate body along the Z direction. The post body passes through the electrode post hole. The post body has a first axis extending along the Z direction and an outer peripheral surface radially away from the first axis. A groove is formed on the outer peripheral surface of the post body. The groove is at least part of an annular groove surrounding the first axis. The diameter of the inner ring of the annular groove is g. The post body includes a first post segment located on the side of the groove away from the base plate. The diameter of the first post segment is G. Wherein, g and G satisfy the relationship: 0.7≤g / G≤0.

9. The first plastic part includes a plastic part body and a protrusion. The plastic part body is sleeved on the column and connected to the cover plate body. The protrusion is connected to the inner ring of the plastic part body and is inserted into the groove.

2. The cover plate structure according to claim 1, characterized in that, The diameter G of the first column segment is in the range of 8 mm ≤ G ≤ 20 mm.

3. The cover plate structure according to claim 1, characterized in that, The number of grooves is one, or the number of grooves is multiple, and the multiple grooves are distributed circumferentially along the column in the XY plane.

4. The cover plate structure according to claim 1, characterized in that, The perimeter of the column in the XY plane is M, and the total arc length of the opening side of the groove in the XY plane is m, wherein m and M satisfy the relationship: 0.6≤m / M≤1.

5. The cover plate structure according to claim 4, characterized in that, The perimeter M of the cylinder in the XY plane has the following range: 25 mm ≤ M ≤ 63 mm.

6. The cover plate structure according to claim 1, characterized in that, The height of the groove along the Z direction is h, where the value of h ranges from 0.5 mm to 2 mm.

7. The cover plate structure according to claim 3, characterized in that, The number of grooves is N, where 1≤N≤4.

8. The cover plate structure according to claim 1, characterized in that, The pole post and the cover plate body are spaced apart, and the first plastic part is injection molded between the pole post and the cover plate body.

9. The cover plate structure according to any one of claims 1 to 8, characterized in that, The cover plate structure further includes a sealing ring, which is sleeved on the column and located below the first plastic part along the Z direction. At least a portion of the sealing ring is sandwiched between the cover plate body and the bottom plate.

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

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