Battery cell cover plate and battery cell

Abstract

This invention belongs to the field of battery technology, specifically disclosing a cell cover and a cell. The cell cover has a fixing groove on its body. The fixing assembly includes an injection molded part and a fixing ring. A fixing post is formed by hot-melting the side of the injection molded part opposite to the cover body. The fixing post fills the fixing groove to fix the injection molded part to the cover body. The injection molded part wraps around the circumference of the fixing ring and a portion of the end face of the fixing ring facing the cover body, thereby fixing the fixing ring to the injection molded part. The injection molded part insulates the cover body from the fixing ring. An explosion-proof valve is welded to the fixing ring to fix the explosion-proof valve to the fixing ring. Two sides of a first sealing member abut against the fixing ring and the cover body respectively to seal the gap between the cover body and the fixing ring. This invention also provides a cell including the above-mentioned cell cover.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a cell cover plate and a cell. Background Technology

[0002] In steel-cased battery cells, both the casing and the cover are made of stainless steel. Steel-cased cells offer high dimensional consistency after encapsulation and have strong impact resistance, effectively protecting the internal electrode assembly. Generally, an explosion-proof valve is installed on the cover to prevent explosions in the event of thermal runaway of the internal electrode assembly, thus ensuring the safety performance of the steel-cased battery cell.

[0003] Currently, one approach to manufacturing explosion-proof valves involves directly machining grooves onto the cover plate. While this ensures a high connection strength between the valve and the cover plate, its processing efficiency is low. When the cover plate is thick, etching a single valve can take several minutes or even tens of minutes, hindering mass production. Directly welding a steel explosion-proof valve to a steel cover plate avoids potential corrosion at the weld joint. However, stainless steel is very hard, making it difficult to machine steps onto the cover plate. This makes it impractical to use the same step features found in existing aluminum-cased batteries and aluminum explosion-proof valve connection structures. Furthermore, steel explosion-proof valves are difficult to machine and form, resulting in unstable detonation values ​​and potential safety hazards. Summary of the Invention

[0004] The purpose of this invention is to provide a battery cell cover plate and a battery cell, which can stably assemble an explosion-proof valve on the cover plate body. The explosion-proof valve has high processing precision and stable detonation value.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] On one hand, the present invention provides a battery cell cover plate, comprising:

[0007] The cover plate body has a first through hole and a fixing groove on the side of the cover plate body away from the electrode group. The fixing groove is located around the first through hole.

[0008] The fixing assembly includes an injection-molded part and a fixing ring arranged sequentially along a first direction on the side of the cover plate body away from the electrode group. The injection-molded part wraps around the circumference of the fixing ring and a portion of the end face of the fixing ring facing the cover plate body. The side of the injection-molded part opposite to the cover plate body is heat-melted to form a fixing post, which fills the fixing groove. A second through hole is formed at the center of the injection-molded part, and a third through hole is formed at the center of the fixing ring. A stepped portion is provided on the fixing ring in the circumference of the third through hole, and the stepped portion is located on the side of the fixing ring away from the electrode group.

[0009] A first sealing element is disposed in the second through hole. The first sealing element abuts against the fixing ring and the cover plate body on both sides along the first direction. A fourth through hole is formed at the center of the first sealing element. The third through hole, the fourth through hole and the first through hole are connected in sequence.

[0010] An explosion-proof valve, wherein the circumferential edge of the explosion-proof valve is embedded in the stepped portion, and the outer peripheral wall of the explosion-proof valve is welded to the peripheral side wall of the stepped portion.

[0011] Optionally, the injection molded part includes a first fixing part, a connecting part, and a pressing part. The first fixing part is sandwiched between the cover plate body and the fixing ring along a first direction, and the fixing post is provided on the side of the first fixing part facing the cover plate body. The connecting part is circumferentially disposed on the fixing ring and fits against the peripheral sidewall of the fixing ring. The two ends of the connecting part along the first direction are respectively connected to the first fixing part and the pressing part. The pressing part extends toward the center of the fixing ring and fits against the end face of the fixing ring away from the electrode group along the first direction.

[0012] Optionally, along the first direction, the thickness of the first fixing part is e, and the thickness of the pressing part is d; along the second direction, the thickness of the connecting part is c.

[0013] The value range of e is: 0.5mm ≤ e ≤ 1.5mm;

[0014] The range of values ​​for d is: 1.0mm ≤ d ≤ 2.0mm;

[0015] The value range of c is: 0.5mm≤c≤2.0mm.

[0016] Optionally, along the first direction, the thickness of the cover plate body is g, and the depth of the fixing groove is h;

[0017] The value of g is in the range of: 0.5mm ≤ g ≤ 1.2mm;

[0018] The value of h is in the range of 0.5mm≤h≤0.7g.

[0019] Optionally, the cross-section of the fixing groove in a first plane parallel to the first direction is an inverted trapezoid, and there is an included angle A between the bottom wall surface of the fixing groove and the side wall surface of the fixing groove;

[0020] The range of values ​​for A is: 45°≤A≤85°.

[0021] Optionally, the first sealing element includes a first sealing portion and a second sealing portion. The first sealing portion is disposed around the second sealing portion in the circumferential direction. The first sealing portion abuts against the cover plate body and the fixing ring on both sides along the first direction, respectively. The second sealing portion extends into the first through hole toward the side where the pole group is located and fits against the inner wall of the first through hole. The center of the second sealing portion forms the fourth through hole.

[0022] Optionally, along the second direction, the distance between the outer peripheral wall of the first sealing part and the inner wall of the first through hole is f;

[0023] The value range of f is: 0.5mm≤f≤1.5mm.

[0024] Optionally, the explosion-proof valve includes a second fixing part and a body part. The second fixing part is arranged around the circumference of the body part and is embedded in the step part. The outer peripheral wall of the second fixing part is welded to the peripheral side wall of the step part to form a welded part. The body part is provided with a scoring groove pointing from the center of the explosion-proof valve to its circumferential edge. The inner side of the scoring groove forms an opening part.

[0025] Along the first direction, the thickness of the second fixing part is a, and the penetration depth of the welded part is b;

[0026] Where the value of a is in the range of: 0.3mm≤a≤1mm;

[0027] The value of b is in the range of 0.3mm≤b≤1.5a.

[0028] Optionally, the cell cover includes a first insulating member, which is disposed on the side of the cover body near the electrode group. The first insulating member has a fifth through hole, which communicates with the first through hole.

[0029] On the other hand, the present invention provides a battery cell including the battery cell cover plate of any of the above embodiments.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention provides a battery cell cover plate, including a cover plate body, a fixing assembly, an explosion-proof valve, and a first sealing element. The cover plate body has a first through hole, and a fixing groove is provided on the side of the cover plate body away from the electrode assembly, the fixing groove being located circumferentially to the first through hole. The fixing assembly includes an injection-molded part and a fixing ring. A fixing post is formed by hot-melting the side of the injection-molded part opposite to the cover plate body, and the fixing post fills the fixing groove to fix the injection-molded part to the cover plate body. The injection-molded part wraps around the circumference of the fixing ring and a portion of the end face of the fixing ring facing the cover plate body, thereby fixing the fixing ring to the injection-molded part, while the injection-molded part insulates the cover plate body from the fixing ring. A stepped portion is provided on the side of the fixing ring away from the electrode assembly. The outer peripheral wall of the explosion-proof valve is welded to the peripheral side wall of the stepped portion, thereby fixing the explosion-proof valve to the fixing ring, realizing the assembly of the explosion-proof valve on the cover plate body. The two sides of the first sealing element abut against the fixing ring and the cover plate body respectively to seal the gap between the cover plate body and the fixing ring.

[0032] The present invention also provides a battery cell, including the aforementioned battery cell cover plate. This battery cell cover plate can stably fix an explosion-proof valve to the cover plate body. The explosion-proof valve has high processing precision, a stable detonation value, and good safety performance of the battery cell. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the battery cell cover plate provided in Embodiment 1 of the present invention;

[0034] Figure 2 This is a cross-sectional view of the battery cell cover plate provided in Embodiment 1 of the present invention;

[0035] Figure 3 yes Figure 2 A magnified view of a section at point I;

[0036] Figure 4 This is a partial exploded view of the battery cell cover plate provided in Embodiment 1 of the present invention;

[0037] Figure 5 This is a partial exploded view of the battery cell cover plate provided in Embodiment 1 of the present invention from another perspective;

[0038] Figure 6 This is a partial top view of the battery cell cover plate provided in Embodiment 1 of the present invention;

[0039] Figure 7 yes Figure 6 Sectional view of section II-II;

[0040] Figure 8 yes Figure 7 Enlarged view of a section at point III;

[0041] Figure 9 This is a schematic diagram of the battery cell structure provided in Embodiment 1 of the present invention;

[0042] Figure 10 This is a schematic diagram of the battery cell structure provided in Embodiment 2 of the present invention.

[0043] In the picture:

[0044] 100a, Positive electrode cover; 100b, Negative electrode cover; 100, Cover body; 101, First through hole; 110, Fixing groove; 111, Bottom wall surface; 112, Side wall surface; 200, Fixing assembly; 210, Injection molded part; 211, First fixing part; 2111, Fixing post; 2112, Second through hole; 212, Connecting part; 213, Pressing part; 220, Fixing ring; 221, Third through hole; 222, Stepped part; 223, Fixing flange; 300, Explosion-proof valve; 310, Second fixing part; 311, Welding part; 3 20. Body part; 321. Score groove; 322. Opening part; 400. First sealing element; 410. First sealing part; 420. Second sealing part; 421. Fourth through hole; 500. First insulating element; 501. Fifth through hole; 600. Conductive terminal assembly; 610. First terminal; 620. Second terminal; 621. Plate part; 622. Column part; 700. Second insulating element; 710. Plastic body; 720. Limiting plate; 721. Receiving groove; 800. Second sealing element; 900. Housing; 901. Opening. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0046] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0047] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0048] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0049] Example 1

[0050] like Figure 1 , Figure 4 and Figure 5 As shown, this embodiment provides a battery cell cover plate, which includes a cover plate body 100, a fixing component 200, an explosion-proof valve 300, and a first sealing element 400.

[0051] The cover plate body 100 has a first through hole 101, and a fixing groove 110 is provided on the side of the cover plate body 100 away from the electrode group. The fixing groove 110 is located circumferentially to the first through hole 101. The fixing assembly 200 includes an injection molded part 210 and a fixing ring 220 arranged sequentially along a first direction on the side of the cover plate body 100 away from the electrode group. The injection molded part 210 wraps around the circumference of the fixing ring 220 and a portion of the end face of the fixing ring 220 facing the cover plate body 100. A fixing post 2111 is formed by hot melting on the side of the injection molded part 210 opposite to the cover plate body 100, and the fixing post 2111 fills the fixing groove 110. Optionally, the injection molded part 210 is made of a plastic insulating material. For example, injection molded part 210 can be integrally injection molded on cover plate body 100 using materials such as PPS or PP. During injection molding, injection molded part 210 fixes cover plate body 100 and fixing ring 220 together, and at the same time, injection molded part 210 insulates and isolates fixing ring 220 from cover plate body 100.

[0052] Furthermore, both the injection-molded part 210 and the retaining ring 220 are annular. A second through hole 2112 is formed at the center of the injection-molded part 210, and a third through hole 221 is formed at the center of the retaining ring 220. A step portion 222 is provided circumferentially on the retaining ring 220 at the third through hole 221, and the step portion 222 is located on the side of the retaining ring 220 away from the electrode assembly. The circumferential edge of the explosion-proof valve 300 is embedded in the step portion 222, and the outer peripheral wall of the explosion-proof valve 300 is welded to the peripheral side wall of the step portion 222. This fixes the explosion-proof valve 300 on the retaining ring 220, realizing the assembly of the explosion-proof valve 300 on the cover plate body 100. Optionally, both the explosion-proof valve 300 and the retaining ring 220 can be made of aluminum material, thereby avoiding electrochemical corrosion between them. Moreover, the explosion-proof valve 300 is made of aluminum material, which has high processing precision and stable detonation value. The cover plate body 100 can be made of steel. The cover plate body 100 has high mechanical strength, which is beneficial for protecting the electrode assembly.

[0053] The first sealing element 400 is disposed within the second through hole 2112. The first sealing element 400 abuts against the fixing ring 220 and the cover plate body 100 on both sides along the first direction, respectively, sealing the gap between the cover plate body 100 and the fixing ring 220. The aforementioned first direction is... Figure 1 The X-axis direction shown is also the thickness direction of the cover plate body 100. It is important to note that the installation positions of the cover plate body 100, the retaining ring 220, and the first sealing element 400 should be determined first. Then, the injection molded part 210 is integrally injection molded and fixed to the cover plate body 100 and the retaining ring 220. At this time, the first sealing element 400 is compressed along the first direction to ensure good sealing performance of the battery cell cover plate. Afterwards, the explosion-proof valve 300 is installed on the retaining ring 220, thereby avoiding the high temperature during injection molding of the injection molded part 210 from affecting the structure and shape of the explosion-proof valve 300, which helps to ensure the stability of the explosion-proof valve 300's detonation value.

[0054] In addition, in some embodiments, before the cover body 100 and the fixing ring 220 are integrally injection molded together using the injection molded part 210, the surfaces of the cover body 100 and the fixing ring 220 can be nano-treated to form nanopores on the surfaces of the cover body 100 and the fixing ring 220. The injection molded part 210 adopts a nano-injection molding process, so that the injection particles forming the injection molded part 210 can enter the nanopores on the surfaces of the cover body 100 and the fixing ring 220 at the contact position with the injection molded part 210. The nanopores on the surfaces of the cover body 100 and the fixing ring 220 at the contact position with the injection molded part 210 are filled with injection particles, thereby ensuring good airtightness between the cover body 100 and the injection molded part 210, and between the fixing ring 220 and the injection molded part 210, preventing gas from escaping between the cover body 100 and the injection molded part 210 or between the fixing ring 220 and the injection molded part 210, resulting in better sealing performance of the battery cell cover.

[0055] Furthermore, after the explosion-proof valve 300 is opened, a pressure relief channel is formed. This channel is sequentially connected to the third through hole 221 at the center of the fixing ring 220, the fourth through hole 421 at the center of the first sealing member 400, and the first through hole 101 on the cover plate body 100 to form an exhaust channel. If the gas inside the battery cell wants to be discharged, it can be discharged through the first through hole 101, the fourth through hole 421, the third through hole 221, and the pressure relief channel, and will not overflow from the second through hole 2112, ensuring good airtightness of the battery cell cover plate. In this embodiment, the explosion-proof valve 300 is located on the side of the cover plate body 100 away from the electrode assembly. When the electrode assembly inside the battery cell moves towards the battery cell cover plate with the airflow, the electrode assembly will not block the pressure relief channel of the explosion-proof valve 300, which helps to ensure smooth exhaust.

[0056] See Figures 4-8 In this embodiment, the injection molded part 210 includes a first fixing part 211, a connecting part 212, and a pressing part 213 that are interconnected. The first fixing part 211 is sandwiched between the cover plate body 100 and the fixing ring 220 along a first direction. A fixing post 2111 is provided on the side of the first fixing part 211 facing the cover plate body 100, and the fixing post 2111 corresponds one-to-one with the fixing groove 110 on the cover plate body 100. In some embodiments, multiple fixing grooves 110 can be provided on the cover plate body 100, and these multiple fixing grooves 110 are arranged circumferentially at intervals in the first through hole 101. Correspondingly, during injection molding of the injection molded part 210, fixing posts 2111 are formed in the corresponding fixing grooves 110, improving the connection strength between the injection molded part 210 and the cover plate body 100, and resulting in more balanced force distribution and good fixing effect on the injection molded part 210. The connecting part 212 is circumferentially disposed around the fixing ring 220 and fits against the peripheral sidewall of the fixing ring 220. The two ends of the connecting part 212 along the first direction are respectively connected to the first fixing part 211 and the clamping part 213. The clamping part 213 extends toward the center of the fixing ring 220 and fits against the end face of the fixing ring 220 away from the pole group along the first direction. Thus, through the cooperation of the connecting part 212, the clamping part 213 and the first fixing part 211, the injection molded part 210 can fix the fixing ring 220 to the cover plate body 100.

[0057] In some embodiments, the retaining ring 220 is provided with a retaining flange 223 in the circumferential direction. The retaining flange 223 is located on the side of the retaining ring 220 near the cover plate body 100. A relief groove is formed between the retaining flange 223 and the peripheral sidewall of the retaining ring 220. The clamping part 213 of the injection molded part 210 extends towards the center of the retaining ring 220 and fits against the bottom surface of the relief groove. The thickness of the clamping part 213 along the first direction is not greater than the depth of the relief groove along the first direction, so that the clamping part 213 will not protrude from the end face of the retaining ring 220 away from the cover plate body 100, resulting in high space utilization and a more regular structure of the fixing assembly 200.

[0058] See also Figure 7 and Figure 8 Along the first direction, the thickness of the first fixing part 211 is e, and the value of e ranges from 0.5mm to 1.5mm. For example, the value of e can be 0.5mm, 0.8mm, 1.0mm, 1.2mm, or 1.5mm, etc. Along the first direction, the thickness of the pressing part 213 is d, and the value of d ranges from 1.0mm to 2.0mm. For example, the value of d can be 1.0mm, 1.2mm, 1.5mm, 1.8mm, or 2.0mm, etc. Along the second direction, the thickness of the connecting part 212 is c, and the value of c ranges from 0.5mm to 2.0mm. The above-mentioned second direction is... Figure 7 The Y-axis direction shown is also the length direction of the cover plate body 100. By limiting the values ​​of e, d, and c to meet the above dimensional constraints, the mechanical strength of the injection molded part 210 can be ensured to support and fix the retaining ring 220 well. Of course, the values ​​of e, d, and c should not be too large, otherwise the design redundancy will be too large, increasing material costs.

[0059] Furthermore, along the first direction, the thickness of the cover plate body 100 is g, and the value of g ranges from 0.5mm to 1.2mm. For example, the value of g can be 0.5mm, 0.8mm, 1.0mm, or 1.2mm, etc. By limiting the value of g to the above range, the mechanical strength of the cover plate body 100 itself is high, which can stably fix the injection molded part 210 and the fixing ring 220. Otherwise, if the value of g is too small, the mechanical strength of the cover plate body 100 after machining the fixing groove 110 will be greatly affected, the cover plate body 100 will be prone to deformation, there is a risk of sealing failure, and there is a risk that the injection molded part 210 will fall off the cover plate body 100, reducing the reliability of the battery cell cover. Of course, the value of g should not be too large either, otherwise the battery cell cover will be too thick and heavy, which is not conducive to the lightweight design of the battery cell, and the material cost will be increased, resulting in poor economic efficiency.

[0060] Along the first direction, the depth of the fixing groove 110 on the cover plate body 100 is h, and the value of h is in the range of 0.5mm ≤ h ≤ 0.7g. For example, when the value of g is 1.5mm, the value of h can be 0.5mm, 0.8mm, 1.0mm, or 1.05mm, etc. When the value of g is 2.0mm, the value of h can be 0.8mm, 1.0mm, 1.2mm, or 1.4mm, etc. When the value of g is 3.0mm, the value of h can be 1.0mm, 1.5mm, 2.0mm, or 2.1mm, etc. By limiting the value of h to the above range, the mechanical strength of the cover plate body 100 is not excessively reduced after the fixing groove 110 is opened on the cover plate body 100, and deformation problems of the cover plate body 100 are avoided. At the same time, it ensures that the contact area between the fixing groove 110 and the fixing post 2111 is large, and the connection between the cover plate body 100 and the injection molded part 210 is firm and reliable. If the value of h is too small, the contact area between the fixing groove 110 and the fixing post 2111 will be too small, resulting in a weak connection between the cover plate body 100 and the injection molded part 210. The injection molded part 210 may easily detach from the cover plate body 100, and consequently, the injection molded part 210, carrying the fixing ring 220 and the explosion-proof valve 300, may fall off the cover plate body 100. Conversely, the value of h should not be too large. Otherwise, machining the fixing groove 110 on the cover plate body 100 will significantly weaken its mechanical strength, making it prone to deformation and reducing its support effect on the injection molded part 210, thus lowering its reliability.

[0061] See also Figure 8 The cross-section of the fixing groove 110 in a first plane parallel to the first direction is an inverted trapezoid. Correspondingly, the shape of the fixing post 2111 formed by the injection molding part 210 matches the shape of the fixing groove 110. This design ensures that the fixing post 2111, after cooling and solidification, is less likely to detach from the fixing groove 110, thus improving the connection strength between the injection molding part 210 and the cover plate body 100. Optionally, the bottom wall surface 111 and the side wall surface 112 of the fixing groove 110 form an angle A, where A ranges from 45° to 85°. For example, A can be 45°, 50°, 60°, 70°, 80°, or 85°. By limiting the value of A within this range, the fixing post 2111 is firmly anchored within the fixing groove 110, preventing it from detaching and ensuring a high connection strength between the injection molding part 210 and the cover plate body 100. Furthermore, the fixing groove 110 is easy to mold. Otherwise, if the value of A is too small, the fixing groove 110 will be difficult to form, resulting in a low yield of finished products; if the value of A is too large, the pinning effect will be weak, the fixing post 2111 will easily come out of the fixing groove 110, and the reliability of the connection between the injection molded part 210 and the cover plate body 100 will be reduced.

[0062] See also Figure 5 , Figure 7 and Figure 8In this embodiment, the first sealing element 400 includes a first sealing portion 410 and a second sealing portion 420. The first sealing portion 410 is circumferentially disposed around the second sealing portion 420. The two sides of the first sealing portion 410 along the first direction respectively abut against the cover plate body 100 and the fixing ring 220. The cross-section of the first sealing element 400 in the XY plane is L-shaped. The end face of the first sealing portion 410 away from the electrode group along the first direction abuts against the end face of the fixing ring 220 near the electrode group. The end face of the first sealing portion 410 near the electrode group along the first direction abuts against the end face of the cover plate body 100 away from the electrode group. The first sealing portion 410 seals the gap between the cover plate body 100 and the fixing ring 220. The second sealing portion 420 extends toward the side where the electrode group is located into the first through hole 101 and fits against the inner wall of the first through hole 101. By providing the second sealing part 420, the reliability of the first sealing member 400 can be increased, and the gas or electrolyte inside the battery cell can be prevented from overflowing from the second through hole 2112 of the injection molded part 210. The overall sealing effect of the first sealing member 400 is excellent.

[0063] Furthermore, a fourth through hole 421 is formed at the center of the second sealing part 420. The fourth through hole 421 is connected to the first through hole 101 and the third through hole 221, so that when the internal pressure of the battery cell is too high, the gas inside the battery cell can be discharged from the battery cell through the first through hole 101, the fourth through hole 421, the third through hole 221 and the pressure relief channel of the explosion-proof valve 300, so as to ensure the safety of the battery cell and avoid the risk of explosion.

[0064] Optionally, along the second direction, the distance between the outer peripheral wall of the first sealing part 410 and the inner wall of the first through hole 101 is f, that is, the width of the portion of the first sealing part 410 pressed by the cover plate body 100 and the fixing ring 220 is f. The aforementioned second direction is... Figure 7The Y-axis direction shown is also the length direction of the cover plate body 100. The value range of f is: 0.5mm≤f≤1.5mm. For example, the value of f can be 0.5mm, 0.8mm, 1.0mm, 1.2mm or 1.5mm, etc. By limiting the value of f within the above range, the width of the contact surface between the first sealing part 410, the fixing ring 220 and the cover plate body 100 is larger, ensuring that the sealing performance of the first sealing element 400 meets the sealing level requirements of the battery cell cover plate. At the same time, the cover plate body 100 indirectly provides good support for the fixing ring 220, ensuring sufficient support strength for the fixing ring 220, and the explosion-proof valve 300 is well fixed on the cover plate body 100. Otherwise, if the value of f is too small, the width of the contact surface between the first sealing element 400 and the fixing ring 220 and the cover plate body 100 will be small, which may cause gas to overflow between them. In addition, the support strength of the cover plate body 100 for the fixing ring 220 will be weakened, which may cause more serious deformation when the explosion-proof valve 300 is impacted, and the stability of the explosion-proof valve 300's detonation value will be reduced. The value of f should not be too large either, otherwise the design redundancy will be too large, and the design size of the first through hole 101 and the pressure relief channel on the explosion-proof valve 300 will need to be reduced accordingly, which is not conducive to improving the exhaust efficiency of the explosion-proof valve 300.

[0065] See also Figure 4 , Figure 7 and Figure 8 In this embodiment, the explosion-proof valve 300 includes a second fixing part 310 and a body part 320. The second fixing part 310 is arranged around the circumference of the body part 320 and is embedded in the stepped part 222 on the side of the fixing ring 220 away from the electrode assembly. The outer peripheral wall of the second fixing part 310 is welded to the peripheral side wall of the stepped part 222 to form a welded part 311, thereby realizing the fixed connection between the fixing ring 220 and the explosion-proof valve 300. Since both the fixing ring 220 and the explosion-proof valve 300 are made of aluminum, the welding quality between them is good, the welding yield is high, and there is no electrochemical corrosion problem, resulting in a long service life. Furthermore, the body part 320 is provided with a groove 321 pointing from the center of the explosion-proof valve 300 to its circumferential edge, and the inner side of the groove 321 forms an opening part 322. After the explosion-proof valve 300 is opened, the body part 320 breaks at the groove 321, and a pressure relief channel is formed at the opening part 322. Even better, the groove 321 on the explosion-proof valve 300 is located inside the second sealing part 420 of the first sealing element 400, thereby preventing the pressure relief channel of the explosion-proof valve 300 from being blocked, which would affect the opening of the explosion-proof valve 300 and the exhaust situation after the explosion-proof valve 300 is opened.

[0066] Along the first direction, the thickness of the second fixing part 310 is 'a', and the value of 'a' ranges from 0.3mm to 1mm. For example, the value of 'a' can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, or 1.0mm, etc. By limiting the value of 'a' to the above range, the second fixing part 310 has high mechanical strength, and the explosion-proof valve 300 is not easily deformed, which helps to ensure the stability of the detonation value of the explosion-proof valve 300. Otherwise, if the value of 'a' is too small, the thickness of the second fixing part 310 will be too thin, the explosion-proof valve 300 will be easily deformed, the detonation value of the explosion-proof valve 300 will be unstable, and the reliability will be reduced; the value of 'a' should also not be too large, otherwise the stamping difference between the second fixing part 310 and the main body 320 will be large, and the processing accuracy will be difficult to guarantee.

[0067] Furthermore, the end face of the fixing ring 220 away from the electrode group is flush with the end face of the second fixing part 310 away from the electrode group. That is, the depth of the step portion 222 on the fixing ring 220 is equal to the thickness of the second fixing part 310, which helps improve the welding quality and yield during welding. Along the first direction, the penetration depth of the weld portion 311 is b, and the value of b ranges from 0.3mm to 1.5a. For example, when the value of a is 0.3mm, the value of b can be 0.3mm, 0.35mm, 0.4mm, or 0.45mm, etc. When the value of a is 0.5mm, the value of b can be 0.4mm, 0.5mm, 0.6mm, or 0.75mm, etc. When the value of a is 1mm, the value of b can be 0.8mm, 1.0mm, 1.2mm, or 1.5mm, etc. By limiting the value of b within the aforementioned range, the molten pool during the formation of the welded part 311 is ensured to be large enough to meet the connection strength requirements between the fixing ring 220 and the explosion-proof valve 300, guaranteeing a reliable connection and high welding strength. The value of b should not be too small; otherwise, the connection strength between the fixing ring 220 and the explosion-proof valve 300 will be insufficient, and the explosion-proof valve 300 may detach from the fixing ring 220. Conversely, the value of b should not be too large either; otherwise, the heat effect during welding of the fixing ring 220 and the explosion-proof valve 300 may cause the injection molded part 210 to melt and deform, which is detrimental to the stable fixation between the fixing ring 220 and the injection molded part 210. Furthermore, the molten volume at the second fixing part 310 on the explosion-proof valve 300 is relatively large, and the second fixing part 310 may also deform, leading to the stretching of the body part 320 of the explosion-proof valve 300. The groove 321 on the body part 320 is prone to deformation, ultimately resulting in unstable detonation values ​​for the explosion-proof valve 300 and reduced reliability.

[0068] Optionally, the cell cover includes a plate-shaped first insulating member 500, which is disposed on the side of the cover body 100 near the electrode assembly and abuts against the end face of the cover body 100 facing the electrode assembly. For example, the material of the first insulating member 500 can be PP. The first insulating member 500 insulates the cover body 100 from the electrode assembly, ensuring good electrical safety of the cell. The first insulating member 500 has a fifth through hole 501, which communicates with the first through hole 101, allowing gas to enter the first through hole 101 through the fifth through hole 501, ensuring smooth venting.

[0069] See also Figure 1 , Figure 2 and Figure 3 In this embodiment, the battery cell cover also includes a conductive terminal assembly 600 and a second insulating member 700. The second insulating member 700 is located on the side of the cover body 100 away from the electrode group. The conductive terminal assembly 600 includes a first terminal 610 and a second terminal 620. The first terminal 610 is located on the side of the first insulating member 500 closer to the electrode group. The second terminal 620 includes a plate portion 621 and a pillar portion 622 connected to each other. The plate portion 621 is located on the side of the second insulating member 700 away from the cover body 100. The pillar portion 622 passes through the second insulating member 700, the cover body 100, and the first insulating member 500 along a first direction and connects to the first terminal 610. After the second terminal 620 and the first terminal 610 are connected, they can be stably fixed to the cover body 100. The second insulating member 700 can be made of PPS material, which insulates the second terminal 620 from the cover body 100, ensuring electrical safety.

[0070] For example, the cover plate body 100 is provided with a first mounting hole, the first insulating member 500 is provided with a second mounting hole, the first terminal 610 is provided with a third mounting hole, and the second insulating member 700 is provided with a fourth mounting hole. The column portion 622 passes sequentially through the fourth mounting hole, the first mounting hole, the second mounting hole, and the third mounting hole from the side of the second insulating member 700 away from the electrode group, and is then peripherally welded to the inner wall of the third mounting hole to reduce the resistance value between the second terminal 620 and the first terminal 610, thereby alleviating the problem of severe overheating of the second terminal 620 and the first terminal 610 during charging and discharging of the battery cell. In some embodiments, a riveting step can be provided circumferentially in the third mounting hole so that the column portion 622 is riveted to the riveting step. A protrusion is formed at the end of the column portion 622 near the pole assembly at the riveting step. The protrusion cooperates with the plate portion 621 to achieve pre-fixation of the second terminal 620 and the first terminal 610 on the cover plate body 100. Then, the protrusion formed after riveting the column portion 622 is welded to the side wall of the riveting step on the first terminal 610. This assembly method has better fixing firmness.

[0071] Optionally, the second insulating member 700 includes a plastic body 710 and a limiting plate 720. The plastic body 710 is sandwiched between the plate portion 621 and the cover plate body 100 along a first direction, serving to insulate and isolate the cover plate body 100 and the plate portion 621 of the second terminal 620. The limiting plate 720 is disposed around the periphery of the plastic body 710 and extends away from the cover plate body 100. The plastic body 710 and the limiting plate 720 form a receiving groove 721 for mounting the plate portion 621. The setting of the limiting plate 720 ensures good positioning between the second terminal 620 and the second insulating member 700, which is beneficial to improving the assembly accuracy of the cell cover.

[0072] Furthermore, the post portion 622 of the second terminal 620 is fitted with an annular second sealing member 800, which seals the gap between the cover plate body 100 and the second terminal 620. In this embodiment, the second sealing member 800 extends partially into the second mounting hole of the first insulating member 500 to ensure excellent sealing performance between the cover plate body 100 and the second terminal 620.

[0073] Optionally, in this embodiment, two conductive terminal assemblies 600, two second insulating members 700, and two second sealing members 800 are provided, with each of the conductive terminal assemblies 600, second insulating members 700, and second sealing members 800 corresponding one-to-one. The two conductive terminal assemblies 600 and the two second insulating members 700 are respectively positioned on both sides of the fixing assembly 200 and the explosion-proof valve 300 along the second direction. Each second sealing member 800 is fitted over the cylindrical portion 622 of the second terminal 620 of one conductive terminal assembly 600.

[0074] See Figure 9 This embodiment provides a battery cell, which is a prismatic battery cell. The battery cell includes an electrode assembly, a housing 900, and the aforementioned battery cell cover plate. The housing 900 has an opening 901 at one end along a first direction, and the battery cell cover plate is connected to the opening 901 of the housing 900. The electrode assembly is encapsulated within the housing 900. Of the two conductive terminal assemblies 600 on the battery cell cover plate, one conductive terminal assembly 600 is the positive electrode of the battery cell and is electrically connected to the positive terminal lug of the electrode assembly; the other conductive terminal assembly 600 is the negative electrode of the battery cell and is electrically connected to the negative terminal lug of the electrode assembly. The material of the housing 900 is the same as the material of the cover plate body 100. This battery cell cover plate can stably fix an aluminum explosion-proof valve 300 onto the steel cover plate body 100. The explosion-proof valve 300 has high processing precision, a stable detonation value, and good safety performance of the battery cell.

[0075] The following uses samples from specific implementation cases to verify the value range of the relevant parameters e, d, c, and A of the above-mentioned battery cell cover plate. See Table 1 for details.

[0076] Table 1

[0077]

[0078] As can be seen from the above results, the values ​​of parameters e, d, c, and A in Examples 1 to 5 all meet their corresponding dimensional limitations. The injection molded part 210 can stably fix the cover plate body 100 and the fixing ring 220, thereby firmly fixing the explosion-proof valve 300 to the cover plate body 100. The sealing performance between the fixing component 200 and the cover plate body 100 is good, the detonation value of the explosion-proof valve 300 is stable, and the product is of good quality.

[0079] In Comparative Example 1, the value of parameter e is less than the minimum value of its range of 0.5mm≤e≤1.5mm. The first fixing part 211 of the injection molded part 210 has insufficient mechanical strength and is prone to deformation. Moreover, if there is an injection molding defect in the injection molded part 210 during processing, a high-voltage arc will occur between the cover plate body 100 and the fixing ring 220, posing a risk that the cover plate body 100 will be punctured. The electrical safety of the battery cell is poor, resulting in defective products.

[0080] In Comparative Example 2, the value of parameter e is greater than the maximum value of its range of 0.5mm≤e≤1.5mm. The first fixing part 211 of the injection molded part 210 has higher mechanical strength, but the space occupied by the first fixing part 211 along the first direction is larger, the thickness of the battery cell cover plate increases, the space utilization rate is low, the cost increases, and the product is defective.

[0081] In Comparative Example 3, the value of parameter d is greater than the maximum value of its range of 1.0mm≤d≤2.0mm. The mechanical strength of the clamping part 213 of the injection molded part 210 is higher, but the space occupied by the injection molded part 210 along the first direction is larger, the thickness of the battery cell cover plate increases, the space utilization rate is low, the cost increases, and the product is defective.

[0082] In Comparative Example 4, the value of parameter d is less than the minimum value of its range of 1.0mm≤d≤2.0mm. The mechanical strength of the clamping part 213 of the injection molded part 210 is insufficient. When the pressure inside the battery cell is too high, the clamping part 213 is prone to deformation. Consequently, the seal between the injection molded part 210 and the fixing ring 220 is prone to failure, the explosion-proof valve 300 cannot open normally, the reliability is poor, and the product is defective.

[0083] In Comparative Example 5, the value of parameter c is less than the minimum value of its range of 0.5mm≤c≤2.0mm. The mechanical strength of the connecting part 212 of the injection molded part 210 is insufficient. When the pressure inside the battery cell is too high, the connecting part 212 is prone to deformation. Consequently, the sealing between the injection molded part 210 and the fixing ring 220 is prone to failure, the explosion-proof valve 300 cannot open normally, the reliability is poor, and the product is defective.

[0084] In Comparative Example 6, the value of parameter c is greater than the maximum value of its range of 0.5mm≤c≤2.0mm. The mechanical strength of the connecting part 212 of the injection molded part 210 is high, but the space occupied by the injection molded part 210 in its radial direction is large, which affects the arrangement of other structural parts on the cover plate body 100. Moreover, the width dimension of the cover plate body 100 needs to be increased, resulting in low space utilization, increased cost, and product defects.

[0085] In Comparative Example 7, the value of parameter A is less than the minimum value of its range 45°≤A≤85°, making it difficult to form the fixing groove 110 on the cover plate body 100, resulting in a low yield. The yield of the fixing column 2111 during injection molding is also low, leading to defective products.

[0086] In Comparative Example 8, the value of parameter A is greater than the maximum value of its range 45°≤A≤85°. The anchoring effect between the fixing post 2111 and the fixing groove 110 is small, the bonding strength between the fixing post 2111 and the fixing groove 110 is insufficient, the fixing post 2111 is easy to come out of the fixing groove 110, the connection strength between the injection molded part 210 and the cover plate body 100 is insufficient, and the product is defective.

[0087] The following uses samples from specific implementation cases to verify the range of values ​​for the relevant parameters g and h of the above-mentioned battery cell cover plate. See Table 2 for details.

[0088] Table 2

[0089]

[0090] As can be seen from the above results, the values ​​of parameters g and h in Examples 1 to 3 meet their size constraints, the fixing groove 110 on the cover plate body 100 is easy to form, and the fixing post 2111 on the injection molded part 210 can be firmly nailed into the fixing groove 110 and is not easy to come out of the fixing groove 110. The connection strength between the injection molded part 210 and the cover plate body 100 is high, the airtightness of the battery cell cover plate is good, the detonation value of the explosion-proof valve 300 is stable, and the product is good.

[0091] In Comparative Examples 1 and 2, the value of parameter h is less than the minimum value of its range 0.5mm≤h≤0.7g. The depth of the fixing groove 110 on the cover plate body 100 is too small, the connection strength between the fixing post 2111 and the fixing groove 110 is insufficient, the stability of the injection molded part 210 fixed on the cover plate body 100 is poor, there is a risk of falling off, the reliability is poor, and the product is defective.

[0092] In Comparative Examples 3 and 4, the value of parameter h is greater than 0.7g, which is greater than the maximum value of its range of 0.5mm≤h≤0.7g. After machining the fixing groove 110 on the cover plate body 100, the cover plate body 100 has problems of deformation and material accumulation hardening, resulting in low finished product yield and defective products.

[0093] Taking all factors into consideration, when the cell cover plate meets the above-mentioned size limitations, the injection molded part 210 can stably fix the cover plate body 100 and the fixing ring 220, thereby firmly fixing the explosion-proof valve 300 to the cover plate body 100. The sealing performance between the fixing component 200 and the cover plate body 100 is good, the detonation value of the explosion-proof valve 300 is stable, and the reliability of the cell cover plate is high.

[0094] Example 2

[0095] See Figure 10 This embodiment also provides a battery cell, which differs from the battery cell in Embodiment 1 in that the type of battery cell is different.

[0096] The battery cell in this embodiment is a blade battery cell. The battery cell includes an electrode assembly, a housing 900, a positive electrode cover plate 100a, and a negative electrode cover plate 100b. The housing 900 has an opening 901 at each end along a first direction. The positive electrode cover plate 100a and the negative electrode cover plate 100b are respectively connected to one opening 901 of the housing 900, and the electrode assembly is encapsulated within the housing 900. The positive electrode cover plate 100a uses the aforementioned battery cell cover plate. The material of the housing 900 is the same as that of the cover plate body 100. This positive electrode cover plate 100a can stably fix an aluminum explosion-proof valve 300 onto the steel cover plate body 100. The explosion-proof valve 300 has high processing precision, a stable detonation value, and good safety performance of the battery cell.

[0097] Furthermore, the positive electrode cover 100a is provided with two conductive terminal assemblies 600, both of which are electrically connected to the positive electrode tab of the electrode group, which can improve the current carrying capacity of the positive electrode cover 100a and meet the needs of high current transmission. The negative electrode cover 100b is also provided with conductive terminal assemblies 600, which are electrically connected to the negative electrode tab of the electrode group.

[0098] The remaining structure of the cell cover plate in this embodiment is the same as that in Embodiment 1, and will not be described again here.

[0099] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A battery cell cover plate, characterized in that, include: The cover plate body has a first through hole and a fixing groove on the side of the cover plate body away from the electrode group. The fixing groove is located around the first through hole. The fixing assembly includes an injection-molded part and a fixing ring arranged sequentially along a first direction on the side of the cover plate body away from the electrode group. The injection-molded part wraps around the circumference of the fixing ring and a portion of the end face of the fixing ring facing the cover plate body. The side of the injection-molded part opposite to the cover plate body is heat-melted to form a fixing post, which fills the fixing groove. A second through hole is formed at the center of the injection-molded part, and a third through hole is formed at the center of the fixing ring. A stepped portion is provided on the fixing ring in the circumference of the third through hole, and the stepped portion is located on the side of the fixing ring away from the electrode group. A first sealing element is disposed in the second through hole. The first sealing element abuts against the fixing ring and the cover plate body on both sides along the first direction. A fourth through hole is formed at the center of the first sealing element. The third through hole, the fourth through hole and the first through hole are connected in sequence. An explosion-proof valve, wherein the circumferential edge of the explosion-proof valve is embedded in the stepped portion, and the outer peripheral wall of the explosion-proof valve is welded to the peripheral side wall of the stepped portion.

2. The cell cover plate according to claim 1, characterized in that, The injection molded part includes a first fixing part, a connecting part, and a pressing part. The first fixing part is sandwiched between the cover plate body and the fixing ring along a first direction. The fixing post is provided on the side of the first fixing part facing the cover plate body. The connecting part is circumferentially disposed on the fixing ring and fits against the peripheral sidewall of the fixing ring. The two ends of the connecting part along the first direction are respectively connected to the first fixing part and the pressing part. The pressing part extends toward the center of the fixing ring and fits against the end face of the fixing ring away from the electrode group along the first direction.

3. The cell cover plate according to claim 2, characterized in that, Along the first direction, the thickness of the first fixing part is e, and the thickness of the pressing part is d; along the second direction, the thickness of the connecting part is c; The value range of e is: 0.5mm ≤ e ≤ 1.5mm; The range of values ​​for d is: 1.0mm ≤ d ≤ 2.0mm; The value range of c is: 0.5mm≤c≤2.0mm.

4. The cell cover plate according to claim 1, characterized in that, Along the first direction, the thickness of the cover plate body is g, and the depth of the fixing groove is h; The value of g is in the range of: 0.5mm ≤ g ≤ 1.2mm; The value of h is in the range of 0.5mm≤h≤0.7g.

5. The cell cover plate according to claim 1, characterized in that, The cross-section of the fixing groove in a first plane parallel to the first direction is an inverted trapezoid, and there is an included angle A between the bottom wall of the fixing groove and the side wall of the fixing groove. The range of values ​​for A is: 45°≤A≤85°.

6. The cell cover plate according to claim 1, characterized in that, The first sealing element includes a first sealing portion and a second sealing portion. The first sealing portion is disposed around the second sealing portion in the circumferential direction. The first sealing portion abuts against the cover plate body and the fixing ring on both sides along the first direction, respectively. The second sealing portion extends into the first through hole toward the side where the pole group is located and fits against the inner wall of the first through hole. The center of the second sealing portion forms the fourth through hole.

7. The cell cover plate according to claim 6, characterized in that, Along the second direction, the distance between the outer peripheral wall of the first sealing part and the inner wall of the first through hole is f; The value range of f is: 0.5mm≤f≤1.5mm.

8. The cell cover plate according to claim 1, characterized in that, The explosion-proof valve includes a second fixing part and a body part. The second fixing part is arranged around the circumference of the body part and is embedded in the step part. The outer peripheral wall of the second fixing part is welded to the peripheral side wall of the step part to form a welded part. The body part is provided with a scoring groove pointing from the center of the explosion-proof valve to its circumferential edge. The inner side of the scoring groove forms an opening part. Along the first direction, the thickness of the second fixing part is a, and the penetration depth of the welded part is b; Where the value of a is in the range of: 0.3mm≤a≤1mm; The value of b is in the range of 0.3mm≤b≤1.5a.

9. The cell cover plate according to claim 1, characterized in that, The cell cover plate includes a first insulating member, which is disposed on the side of the cover plate body near the electrode group. The first insulating member has a fifth through hole, which communicates with the first through hole.

10. A battery cell, characterized in that, The cell cover plate included in any one of claims 1-9.

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