Battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises: a housing having an open end; the pole group is arranged in the shell; the cover plate assembly is arranged at the opening end of the shell, the cover plate assembly comprises a cover plate body, and a mounting through hole is formed in the cover plate body; the detection device comprises a fixing piece and a mounting piece, the fixing piece is in a sleeve shape with one end open and the other end closed, the fixing piece is fixedly arranged in the mounting through hole in a penetrating mode, the closed end of the fixing piece extends into the shell, the mounting piece comprises a connecting unit and a detection part which are connected, the connecting unit detachably covers the open end of the fixing piece, and the detection part is connected with the connecting unit. The detection part extends into the inner cavity of the fixing piece when the connecting unit is connected with the fixing piece so as to detect the temperature in the shell. The detection part on the installation part extends into the position, close to the pole group, in the battery cell along with the fixing part, the heating condition of the pole group in the battery cell is accurately detected in the using process of the battery cell, and the internal temperature of the battery cell is collected in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to battery cells and battery packs. Background Art

[0002] With the widespread application of batteries in electric vehicles and energy storage fields, the performance and safety of batteries have received more and more attention. For traditional square battery cells, they are mainly composed of a shell, a cover assembly and a pole group, wherein the cover body and the shell in the cover assembly are sealed and welded, and the pole group is encapsulated in a closed space composed of the cover body and the shell. The lower plastic in the cover assembly is against the pole group to limit the pole group. The cell temperature is an important parameter that reflects the safety status of the cell. The cell in the prior art can usually only collect the temperature of the outer surface of the cell, and cannot collect the temperature inside the cell in real time during the use of the cell. Therefore, when the battery is thermally runaway, it is impossible to effectively detect and warn the internal temperature of the cell; it is also impossible to monitor the performance status of the cell in real time when it is used in the vehicle, and it is impossible to confirm the cell performance and optimization direction by collecting a large amount of data statistics. Summary of the invention

[0003] In view of this, the present invention provides a battery cell and a battery pack to solve the problem that the internal temperature of the battery cell cannot be collected in real time during the use of the battery cell.

[0004] In the first aspect, the present invention provides a battery cell, comprising: a shell having an open end; a pole group arranged inside the shell; a cover assembly arranged at the open end of the shell, the cover assembly comprising a cover body, and a mounting hole is opened on the cover body; a detection device, comprising a fixing member and a mounting member, the fixing member is in the shape of a sleeve with one end open and the other end closed, the fixing member is fixedly inserted into the mounting hole and the closed end of the fixing member extends into the interior of the shell, the mounting member comprises a connected connecting unit and a detection part, the connecting unit is detachably covered on the open end of the fixing member, and the detection part extends into the inner cavity of the fixing member when the connecting unit is connected to the fixing member, so as to detect the temperature inside the shell.

[0005] Beneficial effect: by arranging the fixing part of the detection device to extend into the interior of the shell after passing through the installation through hole opened on the cover body, and arranging the installation part to be detachably covered on the open end of the fixing part, after the installation part and the fixing part are assembled, the detection part on the installation part extends into the inner cavity of the fixing part, and then the detection part extends into the position close to the pole group inside the battery cell together with the fixing part, so that the heating condition of the pole group inside the battery cell can be more accurately detected during the use of the battery cell, the internal temperature of the battery cell can be collected in real time, the detection and early warning of the temperature rise inside the battery cell and the feedback of the battery cell performance can be realized, which is beneficial to the further optimization of the battery cell, and the closed end of the fixing part extends into the interior of the shell. On the one hand, the closed end can protect the detection part, and on the other hand, it also plays a role in isolating the inside of the battery cell from the outside, thereby ensuring the sealing of the battery cell and improving the safety of the battery cell.

[0006] In an optional embodiment, the connecting unit includes a plate body and a connecting portion, wherein the connecting portion is formed by extending downward from a partial area of ​​the lower surface of the plate body; the open end of the fixing member protrudes from the upper surface of the cover body, the fixing member is provided with an external thread, the connecting portion is tubular and is provided with an internal thread, and the fixing member is threadedly connected to the connecting portion.

[0007] Beneficial effects: By providing a connecting unit including a plate body and a connecting portion protruding from the lower surface of the plate body, and providing an opening end of the fixing piece protruding from the upper surface of the cover plate body, it is convenient to connect the connecting portion with the fixing piece, and by providing the connecting portion to be tubular and to be configured with an internal thread, and at the same time configuring an external thread on the fixing piece, the threaded connection between the connecting portion and the fixing piece is achieved through the cooperation of the internal thread and the external thread, and the threaded connection is stable and reliable, convenient for disassembly and assembly, easy to operate, and low in cost.

[0008] In an optional embodiment, the detection portion is arranged on the center line of the fixing member, and the shortest distance between the lower end of the detection portion and the lowest point of the bottom wall of the fixing member along the up and down direction is c, wherein 0≤c≤5mm; and / or, the distance between the lower end of the fixing member and the lower surface of the cover plate body is L1, and the distance between the lower surface of the cover plate body and the upper surface of the pole group is L2, wherein -3mm≤L2-L1≤10mm.

[0009] Beneficial effect: By arranging the detection part to be located on the center line of the fixing part, it is ensured that after the installation part and the fixing part are assembled, the detection part can smoothly reach the position close to the lowest point of the bottom wall of the fixing part, thereby avoiding interference between the detection part and the side wall of the fixing part, and by limiting the shortest distance c between the lower end of the detection part and the lowest point of the bottom wall of the fixing part in the up and down direction to be between 0 and 5 mm, it is avoided that the distance between the detection part and the bottom wall of the fixing part is too large, resulting in poor temperature sensing effect, thereby ensuring the accuracy of the internal temperature of the battery cell detected by the detection part.

[0010] By setting the minimum distance between the closed end of the fixing part and the electrode group to a value within the range of -3mm to 10mm, it can be ensured that the fixing part will not crush the electrode group, thereby ensuring the safety of the battery cell, and the temperature sensing effect of the detection part can be ensured, thereby improving the accuracy of the detection result.

[0011] In an optional embodiment, the fixing member is welded to the cover plate body, and a weld mark is formed between the outer peripheral wall of the fixing member and the cover plate body.

[0012] Beneficial effect: By welding the outer peripheral wall of the fixing part to the cover body, a fixed connection between the fixing part and the cover body is achieved, the connection is stable and reliable, and the weld mark surrounds the outer periphery of the fixing part to seal the gap between the outer peripheral wall of the fixing part and the inner wall of the mounting through hole, thereby ensuring the sealing between the fixing part and the cover body, thereby ensuring the sealing of the entire battery cell and improving the safety of the battery cell.

[0013] In an optional embodiment, the depth of penetration of the weld mark on the cover plate body along the up-down direction is h1, and the width of penetration of the weld mark on the cover plate body along the radial direction of the mounting through hole is w1, wherein 0.2mm≤h1≤1.0mm, 0.2mm≤w1≤1.0mm; the depth of penetration of the weld mark on the fixing part along the radial direction of the fixing part is h2, and the width of penetration of the weld mark on the fixing part along the up-down direction is w2, wherein 0.2mm≤h2≤1.0mm, 0.3mm≤w2≤2.0mm.

[0014] Beneficial effects:

[0015] In an optional embodiment, the mounting through hole includes a first hole segment and a second hole segment, the first hole segment is connected above the second hole segment, and the diameter of the first hole segment is larger than the diameter of the second hole segment; the fixing member includes a first barrel segment and a second barrel segment, the first barrel segment is connected above the second barrel segment, the outer diameter of the first barrel segment is larger than the outer diameter of the second barrel segment, the first barrel segment cooperates with the first hole segment, and the second barrel segment cooperates with the second hole segment.

[0016] Beneficial effects: It can ensure the welding strength and the sealing effect between the fixing parts and the cover body, and can also save resources and control costs.

[0017] In an optional implementation, a dimension k of the cover plate body in the up-down direction has a value range of 1 mm ≤ k ≤ 5 mm; and a wall thickness e of the first barrel section has a value range of 1 mm ≤ e ≤ 10 mm.

[0018] Beneficial effect: By limiting the dimension k of the cover body in the up-down direction to be within the range of 1mm to 5mm, it is possible to ensure that the cover body has sufficient strength to avoid deformation when the battery cell is subjected to mechanical force, thereby improving the reliability and safety of the battery cell, and to avoid the cover body being too heavy, thereby controlling the cost and ensuring the energy density of the battery cell; by limiting the wall thickness e of the first barrel section to be within the range of 1mm to 10mm, it is possible to ensure that the first barrel section of the fixing has sufficient wall thickness to ensure the strength of the threaded connection, and to avoid the fixing being too heavy, thereby controlling the production cost.

[0019] In an optional embodiment, the depth of penetration h1 of the weld mark on the cover plate body along the up and down direction and the dimension k of the cover plate body along the up and down direction satisfy: 0.2≤h1 / k≤0.8; the depth of penetration h2 of the weld mark on the fixing part along the radial direction of the fixing part and the wall thickness e of the first barrel section satisfy: 0.2≤h2 / e≤0.8.

[0020] Beneficial effect: By limiting the ratio h1 / k of the penetration depth h of the weld mark on the cover plate body along the up-down direction to the dimension k of the cover plate body along the up-down direction to be within the range of 0.2 to 0.8, the welding strength of the weld mark on the cover plate body can be guaranteed, and the damage to the lower surface of the cover plate body caused by the precipitation of molten beads on the lower surface of the cover plate body can be avoided, thereby ensuring the safety of the cover plate body; by limiting the ratio h2 / e of the penetration depth h of the weld mark on the fixing part along the radial direction of the fixing part to the wall thickness e of the first barrel section to be within the range of 0.2 to 0.8, the welding strength of the weld mark on the fixing part can be guaranteed, and the damage to the inner wall of the first barrel section caused by the precipitation of molten beads on the wall surface can be avoided, thereby ensuring the safety of the fixing.

[0021] In an optional embodiment, a support surface is formed between the lower end of the first hole segment and the upper end of the second hole segment, the radial dimension of the support surface along the mounting through hole is b, and the dimension of the second hole segment along the up-down direction is d, wherein 0.3mm≤b≤10mm, 0.2mm≤d≤4.5mm; and / or, the wall thickness of the second barrel segment is a, wherein 0.2mm≤a≤5mm; and / or, the distance between the lower end of the connecting unit and the upper side of the weld mark along the up-down direction is g, wherein 0.5mm≤g≤10mm.

[0022] Beneficial effect: By setting the radial dimension b of the support surface along the mounting through hole to be in the range of 0.3mm to 10mm, and the dimension d of the second hole segment along the up and down direction to be in the range of 0.2mm to 4.5mm, it can be ensured that the mounting through hole can provide sufficient supporting force and positioning effect to the fixing part to ensure reliability, and the space on the cover body can be reasonably utilized to avoid affecting other structures on the cover body.

[0023] By setting the wall thickness a of the second barrel section to a value within the range of 0.2 mm to 5 mm, it can be ensured that the second barrel section has sufficient wall thickness to prevent the second barrel section from rupturing when the battery cell is subjected to mechanical force or under the gas pressure inside the battery cell, thereby improving safety, and it can also be ensured that the detection part located in the inner cavity of the fixing part has a good temperature sensing effect, thereby ensuring the accuracy of the temperature detection result.

[0024] By setting the distance g between the lower end of the connecting unit and the upper side of the weld mark in the range of 0.5 mm to 10 mm, it is possible to avoid damaging the weld mark when the connecting unit is screwed onto the fixing part, and control the size of the entire detection device in the vertical direction, thereby improving the structural stability of the detection device and facilitating the arrangement of the battery cells in the battery pack.

[0025] In a second aspect, the present invention further provides a battery pack, comprising: the above-mentioned battery cell. Since the battery pack comprises the battery cell and has the same effect as the battery cell, it will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A top view of a battery cell according to an embodiment of the present invention;

[0028] Figure 2 for Figure 1 Cross-sectional view in the MM direction;

[0029] Figure 3 for Figure 2 A partial enlarged schematic diagram of N in the figure;

[0030] Figure 4 A schematic diagram of the positional relationship between a cover plate assembly and a detection device before assembly according to an embodiment of the present invention;

[0031] Figure 5 This is a schematic structural diagram of a mounting member according to an embodiment of the present invention;

[0032] Figure 6 for Figure 5 a cross-sectional view of the mounting shown;

[0033] Figure 7 This is a schematic structural diagram of a fixing member according to an embodiment of the present invention;

[0034] Figure 8 for Figure 7 A cross-sectional view of the fixing member is shown.

[0035] Description of reference numerals:

[0036] 1. Shell; 2. Pole group; 3. Cover plate body; 310. Mounting through hole; 311. First hole section; 312. Second hole section; 320. Pole; 330. Explosion-proof valve; 4. Fixing piece; 401. First barrel section; 402. Second barrel section; 5. Mounting piece; 510. Connecting unit; 511. Plate body; 512. Connecting part; 520. Detecting part; 530. Suspension part; 6. Welding stamp; 7. Lower plastic part. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0038] Combine the following Figures 1 to 8 , describing an embodiment of the present invention.

[0039] According to an embodiment of the present invention, on the one hand, a battery cell is provided, comprising: a shell 1, a pole group 2, a cover assembly and a detection device. The shell 1 has an open end; the pole group 2 is arranged inside the shell 1; the cover assembly is arranged at the open end of the shell 1, and the cover assembly includes a cover body 3, and a mounting through hole 310 is opened on the cover body 3; the detection device includes a fixing member 4 and a mounting member 5, the fixing member 4 is in the shape of a sleeve with one end open and the other end closed, the fixing member 4 is fixedly inserted into the mounting through hole 310 and the closed end of the fixing member 4 extends into the inside of the shell 1, the mounting member 5 includes a connected connection unit 510 and a detection part 520, the connection unit 510 is detachably covered on the open end of the fixing member 4, and the detection part 520 extends into the inner cavity of the fixing member 4 when the connection unit 510 is connected to the fixing member 4, so as to detect the temperature inside the shell 1. Among them, the inside of the shell 1 refers to the inner cavity of the shell 1.

[0040] In the battery cell of the present embodiment, a fixing member 4 of the detection device is arranged to pass through the mounting through hole 310 provided on the cover body 3 and then extend into the interior of the shell 1, and a mounting member 5 is arranged to detachably cover the open end of the fixing member 4. After the mounting member 5 and the fixing member 4 are assembled, the detection portion 520 on the mounting member 5 extends into the inner cavity of the fixing member 4, and then the detection portion 520 extends into the position of the electrode group 2 inside the battery cell together with the fixing member 4, so that the heating condition of the electrode group 2 inside the battery cell can be more accurately detected during the use of the battery cell, the internal temperature of the battery cell can be collected in real time, and the detection and early warning of the temperature rise inside the battery cell and the feedback of the battery cell performance can be realized, which is beneficial to the further optimization of the battery cell. In addition, the closed end of the fixing member 4 extends into the interior of the shell 1. On the one hand, the closed end can protect the detection portion 520, and on the other hand, it also serves to isolate the inside of the battery cell from the outside, thereby ensuring the sealing of the battery cell and improving the safety of the battery cell.

[0041] It should be noted that the fixing member 4 is in the shape of a sleeve with one end open and the other end closed, and the orthographic projection of the fixing member 4 on the cross section passing through the center line thereof is in the shape of a "U", the open end of the fixing member 4 is its open end, and the closed end of the fixing member 4 is its closed end; the open end of the fixing member 4 is located at Figures 2 to 4 The closed end of the fixing member 4 is located at the end of the "upward" direction indicated by the middle arrow. Figures 2 to 4 The end in the direction of "down" indicated by the middle arrow; the inner cavity of the fixing part 4 refers to the space surrounded by the inner wall of the sleeve with a "U"-shaped cross-section; in the process of assembling the mounting part 5 and the fixing part 4 to form a detection device, the detection part 520 of the mounting part 5 is inserted from the open end of the fixing part 4 to the inner cavity of the fixing part 4; the mounting part 5 is used as a sensor, and the fixing part 4 is used as a sensor head. When the connecting unit 510 is assembled with the fixing part 4, the connecting unit 510 is covered on the open end of the fixing part 4 to close the open end of the fixing part 4. The inner cavity of the fixing part 4 and the connecting unit 510 together form a closed space. The detection part 520 is located in the closed space, which is beneficial to protecting the detection part 520 and improving the accuracy of the detection result.

[0042] In one embodiment, the connection unit 510 includes a plate body 511 and a connection portion 512, wherein the connection portion 512 is formed by extending downward from a portion of the lower surface of the plate body 511; the opening end of the fixing member 4 protrudes from the upper surface of the cover body 3, the fixing member 4 is configured with an external thread, the connection portion 512 is tubular and configured with an internal thread, and the fixing member 4 is threadedly connected to the connection portion 512. Figures 2 to 6 The arrow in the middle points to the surface in the direction of "down"; down means toward Figures 2 to 6 The middle arrow points to the "down" direction; the upper surface refers to Figures 2 to 6The surface in the direction of "up" indicated by the middle arrow. By setting the connection unit 510 including the plate body 511 and the connection part 512 protruding from the lower surface of the plate body 511, and setting the opening end of the fixing member 4 protruding from the upper surface of the cover plate body 3, it is convenient to connect the connection part 512 with the fixing member 4, and by setting the connection part 512 to be tubular and configured with internal threads, and at the same time configuring external threads on the fixing member 4, the threaded connection between the connection part 512 and the fixing member 4 is achieved through the cooperation of the internal threads and the external threads. The threaded connection is stable and reliable, easy to disassemble and assemble, easy to operate, and low in cost.

[0043] It should be noted that the connecting portion 512 is tubular, and the internal thread on the connecting portion 512 is provided on the inner wall of the tubular connecting portion 512. Specifically, the internal thread on the connecting portion 512 is provided on at least a portion of the connecting portion 512 near its lower end, and at the same time, the external thread on the fixing member 4 is provided on a portion of the fixing member 4 near its open end, so as to facilitate the matching of the internal and external threads; after the connecting portion 512 is threadedly connected with the fixing member 4, in the up-down direction, at least a portion of the connecting portion 512 overlaps with a portion of the fixing member 4, so that the connecting unit 510 is covered on the open end of the fixing member 4, ensuring the sealing of the closed space between the connecting unit 510 and the inner wall of the fixing member 4, and further ensuring the accuracy of the detection result of the internal temperature of the battery cell by the detection unit 520. The detection unit 520 is located on the inner side of the tubular connecting portion 512, that is, the side of the connecting portion 512 facing its center line.

[0044] Preferably, the connecting portion 512 is in the shape of a round tube, and the fixing member 4 is in the shape of a cylinder with one end open and the other end closed, which is convenient for processing and assembly. Correspondingly, the mounting through hole 310 is a round hole.

[0045] In addition, in other embodiments (not shown in the figure), the fixing member 4 is configured with an internal thread, and the connecting portion 512 is configured with an external thread, and the threaded connection between the fixing member 4 and the connecting portion 512 can also be achieved. In this case, the connecting portion 512 can be configured as a column, and the outer peripheral wall of the column is configured with an external thread. The connecting portion 512 extends into the inner cavity of the fixing member 4, and the external thread on the connecting portion 512 cooperates with the internal thread on the inner wall of the fixing member 4, which is easy to process and has a high structural strength.

[0046] In one embodiment, the detection portion 520 is disposed on the center line of the fixing member 4, and the shortest distance between the lower end of the detection portion 520 and the lowest point of the bottom wall of the fixing member 4 in the vertical direction is c, where 0≤c≤5mm. Figures 2 to 3 The arrow in the middle points to the "down" end; the up and down directions refer to Figures 2 to 3The direction of "up and down" indicated by the arrow in the middle. By setting the detection part 520 to be located on the center line of the fixing part 4, it is ensured that after the installation part 5 and the fixing part 4 are assembled, the detection part 520 can smoothly reach the position close to the lowest point of the bottom wall of the fixing part 4, avoiding interference between the detection part 520 and the side wall of the fixing part 4, and by limiting the shortest distance c between the lower end of the detection part 520 and the lowest point of the bottom wall of the fixing part 4 along the up and down direction to be between 0 and 5 mm, it is avoided that the distance between the detection part 520 and the bottom wall of the fixing part 4 is too large, resulting in poor temperature sensing effect, thereby ensuring the accuracy of the internal temperature of the battery cell detected by the detection part 520.

[0047] It should be noted that the bottom wall of the fixing member 4 refers to the inner wall of the closed end of the fixing member 4, the inner wall of the closed end of the fixing member 4 is an arc surface, and the lowest point of the bottom wall of the fixing member 4 refers to the position on the inner wall of the closed end of the fixing member 4 that is closest to the pole group 2, that is, the intersection of the inner wall of the fixing member 4 and its center line.

[0048] In one embodiment, the detection unit 520 is a thermistor probe, which has high precision, fast response speed, small size, good stability, and high sensitivity. It can accurately detect the temperature inside the battery cell, and has mature technology and low cost.

[0049] In one embodiment, the mounting member also includes a hanging portion 530, one end of the hanging portion 530 is connected to the connecting unit 510 and the other end is connected to the detecting portion 520, the temperature detected by the detecting portion 520 is transmitted to the board 511 of the connecting unit 510 through the hanging portion 530, and the temperature collection device is connected to the board 511, thereby obtaining the temperature inside the battery cell detected by the detecting portion 520.

[0050] Preferably, the connecting portion 512 is tubular, and the hanging portion 530 is located inside the tube and connected to the lower surface of the plate body 511 .

[0051] In one embodiment, the distance between the lower end of the fixing member 4 and the lower surface of the cover body 3 is L1, and the distance between the lower surface of the cover body 3 and the upper surface of the electrode group 2 is L2, wherein -3mm≤L2-L1≤10mm. Figures 2 to 3 The lowest point on the side of the "down" direction indicated by the middle arrow; the lower surface refers to Figures 2 to 3 The arrow in the middle points to the surface in the "down" direction; the upper surface refers to Figures 2 to 3The surface in the direction of "up" indicated by the middle arrow. The difference between the distance L2 between the lower surface of the cover body 3 and the upper surface of the pole group 2 and the distance L1 between the lower end of the fixing member 4 and the lower surface of the cover body 3 is the distance f between the lower end of the fixing member 4 and the upper surface of the pole group 2. It should be noted that because the diaphragm wrapped around the upper surface of the pole group 2 can be softly compressed, the fixing member 4 and the pole group 2 can have a certain degree of interference, but the interference cannot be too large. When the value of L2-L1 (i.e., f) is negative, it means that the fixing member 4 and the pole group 2 have interference. If f is less than -3mm, the interference between the fixing member 4 and the pole group 2 is too large, which will crush the pole piece and even cause a short circuit, which is very dangerous. If f is greater than 10mm, the distance between the fixing member 4 and the pole group 2 is too large, resulting in poor temperature sensing effect of the detection unit 520 located in the inner cavity of the fixing member 4, and the temperature accuracy of the pole group inside the battery cell detected by the detection unit 520 is poor.

[0052] Therefore, by setting the minimum distance between the closed end of the fixing member 4 and the electrode group 2 to a value within the range of -3 mm to 10 mm, it can be ensured that the fixing member 4 will not crush the electrode group 2, thereby ensuring the safety of the battery cell, and the temperature sensing effect of the detection unit 520 can be ensured, thereby improving the accuracy of the detection result.

[0053] In one embodiment, the fixing member 4 is welded to the cover body 3, and a weld mark 6 is formed between the outer peripheral wall of the fixing member 4 and the cover body 3. By welding the outer peripheral wall of the fixing member 4 to the cover body 3, the fixing member 4 and the cover body 3 are fixedly connected, the connection is stable, and the reliability is high. The weld mark 6 surrounds the outer periphery of the fixing member 4, seals the gap between the outer peripheral wall of the fixing member 4 and the inner wall of the mounting through hole 310, ensures the sealing between the fixing member 4 and the cover body 3, thereby ensuring the sealing of the entire battery cell and improving the safety of the battery cell.

[0054] The cover body 3 is made of aluminum or steel, and the fixing member 4 is made of the same material to facilitate welding.

[0055] In one embodiment, the depth of the weld mark 6 on the cover plate body 3 along the vertical direction is h1, and the width of the weld mark 6 on the cover plate body 3 along the radial direction of the mounting through hole 310 is w1, wherein 0.2mm≤h1≤1.0mm, 0.2mm≤w1≤1.0mm; the depth of the weld mark 6 on the fixing part 4 along the radial direction of the fixing part 4 is h2, and the width of the weld mark 6 on the fixing part 4 along the vertical direction is w2, wherein 0.2mm≤h2≤1.0mm, 0.3mm≤w2≤2.0mm. The vertical direction refers to Figures 2 to 3 The mounting through hole 310 is a round hole, and the fixing member 4 is cylindrical. Figure 3 In the cross-sectional view shown, radial direction refers to Figure 3The arrow in the middle points to the direction of "left and right".

[0056] It should be noted that if h1 is less than 0.2 mm, the penetration depth of the weld mark 6 on the cover body 3 is insufficient. If w1 is less than 0.2 mm, the penetration width of the weld mark 6 on the cover body 3 is insufficient. Insufficient penetration depth or penetration width of the weld mark 6 on the cover body 3 will affect the welding strength, and the weld mark 6 is easy to fall off from the cover body 3 or the outer peripheral edge of the weld mark 6 is too close to the gap between the cover body 3 and the fixing part 4, affecting the sealing effect of the connection between the cover body 3 and the fixing part 4; if h2 is less than 0.2 mm , the penetration depth of the weld mark 6 on the fixing part 4 is insufficient; if w2 is less than 0.3 mm, the molten width of the weld mark 6 on the fixing part 4 is insufficient. Insufficient penetration depth or molten width of the weld mark 6 on the fixing part 4 will affect the welding strength, and the weld mark 6 is easy to fall off the fixing part 4 or the weld mark 6 is too small to penetrate into the upper surface of the cover body 3 in the up and down directions, affecting the sealing effect of the connection between the fixing part 4 and the cover body 3; if the penetration depth or molten width is too large, the required welding energy is too large, which wastes resources and is not conducive to reducing costs.

[0057] Therefore, by limiting the fusion depth h1 of the weld mark 6 on the cover plate body 3 along the up and down directions to be in the range of 0.2mm to 1.0mm, the fusion width w1 of the weld mark 6 on the cover plate body 3 along the radial direction of the mounting through hole 310 to be in the range of 0.2mm to 1.0mm, the fusion depth h2 of the weld mark 6 on the fixing part 4 along the radial direction of the fixing part 4 to be in the range of 0.2mm to 1.0mm, and the fusion width w2 of the weld mark 6 on the fixing part 4 along the up and down directions to be in the range of 0.3mm to 2.0mm, it is possible to ensure the welding strength and the sealing effect between the fixing part 4 and the cover plate body 3, and save resources and control costs.

[0058] In one embodiment, the mounting through hole 310 includes a first hole section 311 and a second hole section 312, the first hole section 311 is connected to the top of the second hole section 312, and the diameter of the first hole section 311 is greater than the diameter of the second hole section 312; the fixing member 4 includes a first barrel section 401 and a second barrel section 402, the first barrel section 401 is connected to the top of the second barrel section 402, the outer diameter of the first barrel section 401 is greater than the outer diameter of the second barrel section 402, the first barrel section 401 cooperates with the first hole section 311, and the second barrel section 402 cooperates with the second hole section 312. By setting the mounting through hole 310 as a stepped hole including the first hole section 311 and the second hole section 312, and the outer peripheral wall of the fixing member 4 is set to a stepped shape matching the mounting through hole 310, it is convenient to position and support the fixing member 4 when the fixing member 4 is welded to the cover plate body 3, thereby reducing the welding difficulty, improving the welding quality, and ensuring the sealing between the fixing member 4 and the cover plate body 3.

[0059] In one embodiment, the dimension k of the cover body 3 along the up-down direction is in the range of 1mm≤k≤5mm; the wall thickness e of the first barrel section 401 is in the range of 1mm≤e≤10mm. It should be noted that the dimension k of the cover body 3 along the up-down direction is the thickness of the cover body 3. If k is less than 1mm, the cover body 3 is too thin, the strength of the cover body 3 is insufficient, and it is easy to deform when the battery cell is mechanically stressed, and the stability and safety are poor; if k is greater than 5mm, the cover body 3 is too thick, the weight is too large, the cost is increased, and it is not conducive to improving the energy density of the battery cell; the first barrel section 401 is provided with a thread that matches the connecting portion 512. If the wall thickness e of the first barrel section 401 is less than 1mm, the side wall of the first barrel section 401 is too thin, which affects the strength of the threaded connection and has poor reliability; if e is greater than 10mm, the side wall of the first barrel section 401 is too thick, the weight is too large, and the cost is increased. Therefore, by limiting the dimension k of the cover body 3 in the up-down direction to be in the range of 1mm to 5mm, it is possible to ensure that the cover body 3 has sufficient strength to avoid deformation when the battery cell is subjected to mechanical force, thereby improving the reliability and safety of the battery cell, and to avoid the cover body 3 being too heavy, thereby controlling the cost and ensuring the energy density of the battery cell; by limiting the wall thickness e of the first barrel section 401 to be in the range of 1mm to 10mm, it is possible to ensure that the first barrel section 401 of the fixing part 4 has sufficient wall thickness to ensure the strength of the threaded connection, and to avoid the fixing part 4 being too heavy, thereby controlling the production cost.

[0060] In one embodiment, the depth of penetration h1 of the weld mark 6 on the cover plate body 3 along the vertical direction and the dimension k of the cover plate body 3 along the vertical direction satisfy: 0.2≤h1 / k≤0.8; the depth of penetration h2 of the weld mark 6 on the fixing member 4 along the radial direction of the fixing member 4 and the wall thickness e of the first barrel section 401 satisfy: 0.2≤h2 / e≤0.8. The units of h1, k, h2, and e are all mm. It should be noted that if h1 / k is less than 0.2, the distance that the weld mark 6 extends downward from the upper surface of the cover body 3 is too small, the welding strength is insufficient, and the sealing between the cover body 3 and the fixing part 4 is affected; if h1 / k is greater than 0.8, the distance that the weld mark 6 extends downward from the upper surface of the cover body 3 is too large, molten beads will appear on the lower surface of the cover body 3, causing damage to the lower surface of the cover body 3; if h2 / e is less than 0.2, the distance that the weld mark 6 extends from the outer peripheral wall of the first barrel section 401 of the fixing part 4 along the radial direction of the fixing part 4 toward the inner wall of the first barrel section 401 is too small, and the welding strength is insufficient; if h2 / e is greater than 0.8, the distance that the weld mark 6 extends from the outer peripheral wall of the first barrel section 401 of the fixing part 4 along the radial direction of the fixing part 4 toward the inner wall of the first barrel section 401 is too large, molten beads will appear on the inner wall of the first barrel section 401, causing damage to the inner wall.

[0061] Therefore, by limiting the ratio h1 / k of the fusion depth h1 of the weld mark 6 on the cover plate body 3 along the up and down directions to the dimension k of the cover plate body 3 along the up and down directions to be in the range of 0.2 to 0.8, it is possible to ensure the welding strength of the weld mark 6 on the cover plate body 3, and avoid the precipitation of molten beads on the lower surface of the cover plate body 3 and causing damage to the lower surface of the cover plate body 3, thereby ensuring the safety of the cover plate body 3; by limiting the ratio h2 / e of the fusion depth h2 of the weld mark 6 on the fixing part 4 along the radial direction of the fixing part 4 to the wall thickness e of the first barrel section 401 to be in the range of 0.2 to 0.8, it is possible to ensure the welding strength of the weld mark 6 on the fixing part 4, and avoid the precipitation of molten beads on the inner wall of the first barrel section 401 and causing damage to the inner wall of the first barrel section 401, thereby ensuring the safety of the fixing part 4.

[0062] In one embodiment, a support surface is formed between the lower end of the first hole segment 311 and the upper end of the second hole segment 312, the radial dimension of the support surface along the mounting through hole 310 is b, and the vertical dimension of the second hole segment 312 is d, wherein 0.3mm≤b≤10mm, 0.2mm≤d≤4.5mm. Figures 2 to 3 The middle arrow points to the "up" end; the lower end refers to Figures 2 to 3 The end of the "downward" direction indicated by the middle arrow; the installation through hole 310 is radially Figure 3 The middle arrow indicates the "left and right" direction. A contact surface is formed between the lower end of the first barrel section 401 of the fixing member 4 and the upper end of the second barrel section 402. The contact surface is arranged downward, and the supporting surface is arranged upward, and the contact surface contacts the supporting surface. The supporting surface is annular, and the radial dimension of the supporting surface along the mounting through hole 310 is the annular ring width of the supporting surface. The larger the ring width, the larger the area of ​​the supporting surface. If b is less than 0.3 mm, the area of ​​the supporting surface is too small to provide effective support to the fixing member 4, and the relative stability of the fixing member 4 and the cover body 3 during welding is poor. If b is greater than 10 mm, the area of ​​the supporting surface is too large, occupying too much space on the cover body 3, affecting the design of other components on the cover body 3; the portion of the cover body 3 corresponding to the second hole section 312 is used to provide an upward supporting force to the fixing member 4. If the dimension d of the second hole section 312 along the up and down direction is less than 0.2 mm, the portion of the cover body 3 used to provide an upward supporting force to the fixing member 4 is too thin, the structural strength is weak, and the stability is poor. If d is greater than 4.5 mm, the portion of the cover body 3 used to provide an upward supporting force to the fixing member 4 is too thick, resulting in the dimension of the first hole section 311 along the up and down direction being too small, resulting in a poor positioning effect on the fixing member 4.

[0063] Therefore, by setting the radial dimension b of the support surface along the mounting hole 310 to be in the range of 0.3mm to 10mm, and the dimension d of the second hole section 312 along the up and down direction to be in the range of 0.2mm to 4.5mm, it can be ensured that the mounting hole 310 can provide sufficient supporting force and positioning effect to the fixing part 4 to ensure reliability, and the space on the cover body 3 can be reasonably utilized to avoid affecting other structures on the cover body 3.

[0064] In one embodiment, the wall thickness of the second barrel section 402 is a, where 0.2 mm ≤ a ≤ 5 mm. It should be noted that the second barrel section 402 extends into the battery cell after passing through the second hole section 312 and the lower plastic part 7. If the wall thickness a of the second barrel section 402 is less than 0.2 mm, the wall thickness of the second barrel section 402 is too small, and the second barrel section 402 will rupture when the battery cell is mechanically stressed or under the gas pressure inside the battery cell. If a is greater than 5 mm, the wall thickness of the second barrel section 402 is too large, and the temperature sensing effect of the detection part 520 located in the inner cavity of the fixing member 4 is poor. Therefore, by setting the wall thickness a of the second barrel section 402 to a value within the range of 0.2 mm to 5 mm, it can be ensured that the second barrel section has a sufficient wall thickness to prevent the second barrel section 402 from rupturing when the battery cell is mechanically stressed or under the gas pressure inside the battery cell, thereby improving safety, and it can also ensure that the detection part 520 located in the inner cavity of the fixing member 4 has a good temperature sensing effect, thereby ensuring the accuracy of the temperature detection result.

[0065] In one embodiment, the distance between the lower end of the connection unit 510 and the upper side of the weld mark 6 in the vertical direction is g, where 0.5 mm ≤ g ≤ 10 mm. Figure 3 On the side of the direction of "up" indicated by the middle arrow, that is, the position on the weld mark 6 that is farthest from the cover body 3 in the up-down direction, if g is less than 0.5 mm, the connection unit 510 is too close to the weld mark 6, and the weld mark 6 is easily crushed during the assembly of the connection unit 510 on the fixing part 4. If g is greater than 10 mm, the connection unit 510 is too far from the weld mark 6, and the overall size of the detection device in the up-down direction is too large, which is not conducive to the arrangement of the battery cell in the battery pack, and the stability of the entire detection device is poor. Therefore, by setting the distance g between the lower end of the connection unit 510 and the upper side of the weld mark 6 in the up-down direction to a value within the range of 0.5 mm to 10 mm, it is possible to avoid crushing the weld mark 6 when the connection unit 510 is screwed onto the fixing part 4, and the size of the entire detection device in the up-down direction can be controlled, thereby improving the structural stability of the detection device and facilitating the arrangement of the battery cell in the battery pack.

[0066] In one embodiment, the cover assembly also includes: a lower plastic part 7, which is arranged below the cover body 3 and supported between the upper surface of the pole group 2 and the lower surface of the cover body 3; a pole 320, which is inserted into a pole through hole opened on the cover body 3, and is electrically connected to the pole ear on the pole group 2 after passing through the lower plastic part 7; an explosion-proof valve 330, which is arranged on the cover body 3 and is suitable for opening when the internal air pressure of the battery cell reaches a preset value to prevent the battery cell from exploding.

[0067] In one embodiment, the mounting through hole 310 is disposed between the pole through hole and the explosion-proof valve, so as to reasonably utilize the space on the cover plate body 3 .

[0068] In the battery cell of this embodiment, during the assembly process, the fixing member 4 is first assembled and welded with the cover body 3, and then the mounting member 5 with the thermal probe is assembled with the fixing member 4 after the battery cell is assembled. The thermal probe is inserted into the inner cavity of the fixing member 4, and the mounting member 5 is threadedly connected and fixed with the fixing member 4. The detection device is detachably composed of the fixing member 4 and the mounting member 5, which is convenient for disassembly and assembly. The fixing member 4 serves as a sensor head, and the mounting member 5 is a thermal sensor. The thermal probe is lowered to the electrode group area with the sensor head, which can more accurately detect the heating condition of the internal electrode group when the battery cell is used and feedback the battery cell performance.

[0069] According to an embodiment of the present invention, in another aspect, a battery pack is provided, comprising: the above-mentioned battery cell, wherein the number of the battery cell is one or more.

[0070] In one embodiment, the battery cell is a lithium-ion battery cell.

[0071] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that: include: A housing (1) having an open end; A pole group (2) is arranged inside the housing (1); A cover plate assembly is arranged at the open end of the shell (1), the cover plate assembly comprising a cover plate body (3), and a mounting through hole (310) is provided on the cover plate body (3); A detection device comprises a fixing member (4) and a mounting member (5); the fixing member (4) is in the shape of a sleeve with one end open and the other end closed; the fixing member (4) is fixedly inserted into the mounting through hole (310) and the closed end of the fixing member (4) extends into the interior of the housing (1); the mounting member (5) comprises a connecting unit (510) and a detection part (520) connected to each other; the connecting unit (510) is detachably covered on the open end of the fixing member (4); and the detection part (520) extends into the inner cavity of the fixing member (4) when the connecting unit (510) is connected to the fixing member (4) to detect the temperature inside the housing (1).

2. The battery cell according to claim 1, characterized in that: The connection unit (510) comprises a plate body (511) and a connection portion (512), wherein the connection portion (512) is formed by extending downward from a partial area of ​​the lower surface of the plate body (511); the open end of the fixing member (4) protrudes from the upper surface of the cover plate body (3), the fixing member (4) is provided with an external thread, the connection portion (512) is tubular and is provided with an internal thread, and the fixing member (4) is threadedly connected to the connection portion (512).

3. The battery cell according to claim 1, characterized in that: The detection portion (520) is arranged on the center line of the fixing member (4), and the shortest distance between the lower end of the detection portion (520) and the lowest point of the bottom wall of the fixing member (4) in the vertical direction is c, where 0≤c≤5mm; And / or, the distance between the lower end of the fixing member (4) and the lower surface of the cover body (3) is L1, and the distance between the lower surface of the cover body (3) and the upper surface of the pole group (2) is L2, wherein -3mm≤L2-L1≤10mm.

4. The battery cell according to claim 1, characterized in that: The fixing member (4) is welded to the cover plate body (3), and a welding mark (6) is formed between the outer peripheral wall of the fixing member (4) and the cover plate body (3).

5. The battery cell according to claim 4, characterized in that: The weld depth of the weld mark (6) on the cover plate body (3) along the up-down direction is h1, and the weld width of the weld mark (6) on the cover plate body (3) along the radial direction of the mounting through hole (310) is w1, wherein 0.2 mm ≤ h1 ≤ 1.0 mm, and 0.2 mm ≤ w1 ≤ 1.0 mm; The penetration depth of the weld mark (6) on the fixing part (4) along the radial direction of the fixing part (4) is h2, and the penetration width of the weld mark (6) on the fixing part (4) along the up-down direction is w2, wherein 0.2 mm ≤ h2 ≤ 1.0 mm, and 0.3 mm ≤ w2 ≤ 2.0 mm.

6. The battery cell according to claim 5, characterized in that: The mounting through hole (310) comprises a first hole section (311) and a second hole section (312), the first hole section (311) is connected above the second hole section (312), and the diameter of the first hole section (311) is greater than the diameter of the second hole section (312); The fixing member (4) comprises a first barrel section (401) and a second barrel section (402); the first barrel section (401) is connected to the top of the second barrel section (402); the outer diameter of the first barrel section (401) is greater than the outer diameter of the second barrel section (402); the first barrel section (401) cooperates with the first hole section (311); and the second barrel section (402) cooperates with the second hole section (312).

7. The battery cell according to claim 6, characterized in that: The dimension k of the cover plate body (3) in the up-down direction has a value range of 1 mm ≤ k ≤ 5 mm; the wall thickness e of the first barrel section (401) has a value range of 1 mm ≤ e ≤ 10 mm.

8. The battery cell according to claim 7, characterized in that: The fusion depth h1 of the weld mark (6) on the cover plate body (3) in the vertical direction and the dimension k of the cover plate body (3) in the vertical direction satisfy the following: 0.2≤h1 / k≤0.8; The penetration depth h2 of the weld mark (6) on the fixing part (4) in the radial direction of the fixing part (4) and the wall thickness e of the first barrel section (401) satisfy the following: 0.2≤h2 / e≤0.

8.

9. The battery cell according to claim 6, characterized in that: A support surface is formed between the lower end of the first hole segment (311) and the upper end of the second hole segment (312), the radial dimension of the support surface along the mounting through hole (310) is b, and the vertical dimension of the second hole segment (312) is d, wherein 0.3 mm ≤ b ≤ 10 mm, and 0.2 mm ≤ d ≤ 4.5 mm; and / or, the wall thickness of the second barrel section (402) is a, wherein 0.2 mm ≤ a ≤ 5 mm; And / or, the distance between the lower end of the connecting unit (510) and the upper side of the welding mark (6) in the up-down direction is g, wherein 0.5 mm ≤ g ≤ 10 mm.

10. A battery pack, characterized in that: include: The battery cell according to any one of claims 1 to 9.

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