End cover assembly, battery monomer and energy storage device

Abstract

The invention provides an end cover assembly, a battery cell and an energy storage device. The end cover assembly comprises a top cover, the top cover is provided with a first surface and a second surface which are oppositely arranged in the thickness direction of the top cover, the top cover is further provided with a mounting hole, a sinking groove and a groove, the mounting hole penetrates through the first surface and the second surface, the sinking groove is formed around the periphery of the mounting hole, and the sinking groove penetrates through the second surface and communicates with the mounting hole; the groove is formed in the bottom wall of the sinking groove; the upper plastic cement is arranged in the sinking groove and partially arranged in the mounting hole in a penetrating manner, and a through hole is formed in the position, corresponding to the groove, of the upper plastic cement; the pressing ring is arranged on the side, away from the top cover, of the upper plastic and abuts against the upper plastic, and a blind hole is formed in the position, corresponding to the through hole, of the surface, facing the upper plastic, of the pressing ring; the limiting piece is arranged in the through hole in a penetrating mode, part of the limiting piece is located in the groove, and part of the limiting piece is located in the blind hole; in the thickness direction of the top cover, the distance between the bottom wall of the groove and the bottom wall of the blind hole is larger than the height of the limiting piece.

Description

Technical Field

[0001] The present application relates to the field of energy storage, and in particular to an end cover assembly, a battery cell and an energy storage device. Background Art

[0002] The end cap assembly of the battery cell needs to use an upper plastic part to insulate the pole and the pressure ring from the top cover. In addition, a sealing ring needs to be set between the top cover and the pole, and the sealing ring is compressed through the cooperation of the upper plastic, the pole and the top cover to prevent the battery cell from leaking (i.e., electrolyte leakage). However, the upper plastic is made of resin. When the battery cell has thermal runaway, the temperature of the battery cell increases, which easily causes the upper plastic to melt, and the pole is easy to sink and shrink into the upper plastic, resulting in a reduction in the compression of the sealing ring, making the battery cell prone to electrolyte leakage, reducing the safety performance of the battery cell. Summary of the invention

[0003] A first aspect of the present application provides an end cap assembly, comprising:

[0004] A top cover, wherein the top cover has a first surface and a second surface that are arranged opposite to each other along a thickness direction thereof, and the top cover also has a mounting hole, a sink and a groove, wherein the mounting hole passes through the first surface and the second surface respectively, the sink is arranged around the outer circumference of the mounting hole, the sink passes through the second surface and communicates with the mounting hole, and the groove is located on the bottom wall of the sink;

[0005] An upper plastic, the upper plastic is arranged in the sink groove and partially penetrates the mounting hole, and the upper plastic has a through hole at a position corresponding to the groove;

[0006] A pressure ring, the pressure ring is arranged on a side of the upper plastic away from the top cover and abuts against the upper plastic, the pressure ring faces the surface of the upper plastic and has a blind hole at a position corresponding to the through hole; and

[0007] A limiting member, wherein the limiting member is passed through the through hole, and the limiting member is partially located in the groove and partially located in the blind hole; wherein, along the thickness direction of the top cover, the distance between the bottom wall of the groove and the bottom wall of the blind hole is greater than the height of the limiting member.

[0008] In some embodiments, along the thickness direction of the top cover, the spacing between the bottom wall of the groove and the bottom wall of the blind hole is s1, and the height of the limiting member is h1, then 0.05mm≤s1-h1≤0.15mm.

[0009] In some embodiments, the range of the distance s1 between the bottom wall of the groove and the bottom wall of the blind hole is: 0.7 mm≤s1≤3.1 mm; the range of the height h1 of the limiting member is: 0.6 mm≤h1≤3.0 mm.

[0010] In some embodiments, along the thickness direction of the top cover, the depth h2 of the groove is in the range of 0.2 mm ≤ h2 ≤ 1.5 mm.

[0011] In some embodiments, along the thickness direction of the top cover, the depth h3 of the blind hole is in the range of 0.3 mm ≤ h3 ≤ 1.6 mm.

[0012] In some embodiments, the limiting member abuts against the bottom wall of the groove, and along the thickness direction of the top cover, the range of the length L of the limiting member embedded in the blind hole is: 0.2mm≤L≤1.5mm.

[0013] In some embodiments, the upper plastic includes a first insulating portion, a second insulating portion, and a third insulating portion that are bent and connected in sequence, the first insulating portion is located in the mounting hole, the second insulating portion is bent in a direction away from the pole compared to the first insulating portion and is located in the sink, the second insulating portion has the through hole, the third insulating portion is bent in a direction away from the first insulating portion compared to the second insulating portion, the first insulating portion is an annular structure, and the radial dimension of the inner side wall of the first insulating portion is d1,

[0014] The end cover assembly also includes a pole, which includes a flange portion and a penetration portion, the flange portion is located on the first surface side of the top cover, the penetration portion is protruding on the flange portion, the penetration portion is penetrated through the top cover, the upper plastic and the pressure ring in sequence, and the penetration portion is connected to the pressure ring; the radial dimension of the portion of the penetration portion that penetrates the first insulating portion is d2, then: 0.12mm≤d1-d2≤0.3mm.

[0015] In some embodiments, the radial dimension of the outer wall of the first insulating portion is d3, and the radial dimension of the mounting hole is d4, then 0<d4-d3≤0.17mm.

[0016] In some embodiments, the pressure ring is made by a stamping process, the inner wall of the pressure ring is cylindrical, and the outer wall of the pressure ring is a regular hexagonal prism.

[0017] In some embodiments, the number of the grooves and the through holes are both three, the grooves and the through holes are evenly distributed and correspond one to one, the number of the limiting members is three, each limiting member is respectively disposed in a group of grooves and through holes, and the number of the blind holes is six.

[0018] In some embodiments, the top cover assembly further includes a sealing ring, which is arranged around the outer circumference of the penetration portion, the sealing ring is partially located in the mounting hole, and the sealing ring is also partially located between the top cover and the flange portion;

[0019] The top cover assembly also includes a lower plastic, which includes a main body, a first convex ring and a second convex ring. The main body is located on the surface of the top cover away from the upper plastic. The main body includes a first through hole and a second through hole that are spaced apart. The first convex ring is disposed on the surface of the main body away from the top cover and surrounds the outer periphery of the first through hole. The second convex ring is disposed on the surface of the main body away from the top cover and surrounds the outer periphery of the second through hole. The first convex ring and the second convex ring are different in size.

[0020] A second aspect of the present application provides a battery cell, which includes:

[0021] case;

[0022] The end cover assembly according to the first aspect of the present application, wherein the end cover assembly and the shell form a receiving cavity; and

[0023] An electrode assembly is disposed in the receiving cavity and is electrically connected to the pole of the end cap assembly.

[0024] A third aspect of the present application provides an energy storage device, comprising:

[0025] A box body having a containing cavity; and

[0026] A plurality of battery cells as described in the second aspect of the present application are contained in the accommodating cavity.

[0027] The end cap assembly of the embodiment of the present application comprises a top cover, an upper plastic, a pressure ring and a stopper. The top cover has the groove, the upper plastic has the through hole, the pressure ring has a blind hole, the stopper is inserted into the through hole, and the stopper is partially located in the groove and partially located in the blind hole; wherein, along the thickness direction of the top cover, the spacing between the bottom wall of the groove and the bottom wall of the blind hole is greater than the height of the stopper. Thus, after the end cap assembly is assembled, the pressure ring is supported by the upper plastic, and the sealing ring can be made to have a stable compression amount through the cooperation of the pressure ring, the lower plastic, the top cover and the pole; when the battery cell has thermal runaway, the temperature of the pole and the pressure ring rises, causing the upper plastic to melt, the rebound force of the sealing ring is released, and the pole will sink. When the pole sinks to a certain distance, the stopper will resist and support the pressure ring, thereby preventing the pressure ring and the pole from sinking and preventing the rebound force of the sealing ring from being completely released, thereby better avoiding leakage of the battery cell and improving the safety of the battery cell.

[0028] In addition, after the end cover assembly is assembled on the battery cell, when the battery cell is used in the energy storage device, it is necessary to electrically connect multiple battery cells through a bar sheet (i.e., an electrical connector, such as an aluminum sheet), and the bar sheet is welded to the surface of the through-set portion of the pole away from the flange portion by laser welding. However, there are inevitably some defects in the welding of the bar sheet. When the welding of the bar sheet has defects and needs to be reworked, the old bar sheet needs to be removed from the pole. When the bar sheet is removed, it is usually removed by twisting (or torsion) the bar sheet. The twisting of the bar sheet will apply a torsional force to the pole. When the torsional force is too large, it is easy to cause the sealing ring to fail, causing the battery cell to leak. In the embodiment of the application, by setting a limiter, when the bar sheet is twisted, the torsional force generated on the pole will be transmitted to the top cover through the limiter, thereby improving the torsional strength of the pole, thereby better preventing the sealing ring from failing, reducing the risk of leakage of the battery cell, and improving the safety of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a schematic structural diagram of an energy storage device according to an embodiment of the present application.

[0031] Figure 2 It is a schematic structural diagram of a battery cell according to an embodiment of the present application.

[0032] Figure 3The battery cell of one embodiment of the present application is Figure 2 Schematic diagram of the cross-sectional structure in the AA direction.

[0033] Figure 4 It is a schematic structural diagram of an end cover assembly according to an embodiment of the present application.

[0034] Figure 5 It is a schematic diagram of the exploded structure of the end cover assembly provided in one embodiment of the present application.

[0035] Figure 6 It is a schematic diagram of the structure of a top cover provided in one embodiment of the present application.

[0036] Figure 7 It is a schematic diagram of the structure of a pressure ring provided in one embodiment of the present application.

[0037] Figure 8 It is a schematic diagram of the structure of a pole provided in one embodiment of the present application.

[0038] Fig. 9 It is a schematic diagram of the planar structure of an end cover assembly provided in one embodiment of the present application.

[0039] Fig.10 The end cap assembly provided in one embodiment of the present application is Fig. 9 Schematic diagram of the cross-sectional structure in the BB direction.

[0040] Fig.11 yes Fig.10 Enlarged view of the dotted box I in the middle.

[0041] Fig.12 yes Fig.10 Enlarged view of the dashed box II.

[0042] Fig.13 It is a structural schematic diagram of the end cover assembly from another perspective of an embodiment of the present application.

[0043] Fig.14 It is a schematic diagram of the exploded structure of the end cover assembly of one embodiment of the present application from another perspective.

[0044] Fig.15 Schematic diagram of the structure of the lower plastic provided by an embodiment of the present application.

[0045] Description of reference numerals:

[0046] 300-energy storage device, 310-box, 311-accommodating cavity, 200-battery cell, 210-shell, 220-electrode assembly, 221-positive electrode plate, 222-diaphragm, 223-negative electrode plate, 230-accommodating cavity, 100-end cover assembly, 10-top cover, 11-first surface, 12-second surface, 13-mounting hole, 14-sink, 15-groove, 16-cover body, 17-mounting part, 20-upper plastic, 21-first insulating part, 22-second insulating part, 23-third insulating part , 201-through hole, 30-pressure ring, 30a-positive pressure ring, 30b-negative pressure ring, 31-blind hole, 40-limiting piece, 50-pole, 50a-positive pole, 50b-negative pole, 51-flange portion, 52-penetrating portion, 521-first penetrating sub-portion, 5211-step surface, 522-second penetrating sub-portion, 523-protruding sub-portion, 60-sealing ring, 70-lower plastic, 71-main body, 711-first through hole, 712-second through hole, 72-first convex ring portion, 73-second convex ring portion. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0049] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0050] It should be noted that, for the convenience of explanation, in the embodiments of the present application, the same figure marks represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0051] At present, the generation of green electricity generally relies on photovoltaics, wind power, and hydropower, etc. However, wind and solar energy generally have problems of strong intermittency and large volatility, which will cause instability in the power grid, insufficient electricity during peak hours, and too much electricity during valley hours. Unstable voltage will also cause damage to electricity. Therefore, insufficient electricity demand or insufficient grid acceptance capacity may cause the problem of "abandoning wind and solar power". To solve these problems, we must rely on energy storage. That is, converting electrical energy into other forms of energy through physical or chemical means and storing it, and converting energy into electrical energy and releasing it when needed. In simple terms, energy storage is like a large "power bank". When photovoltaic and wind energy are sufficient, electrical energy is stored and the stored electricity is released when needed.

[0052] Taking electrochemical energy storage as an example, this solution provides an energy storage device, which is equipped with a chemical battery cell. The chemical elements in the battery cell are mainly used as energy storage media. The charging and discharging process is accompanied by chemical reactions or changes in the energy storage medium. Simply put, the electricity generated by wind and solar energy is stored in chemical battery cells. When the use of external electricity reaches a peak, the stored electricity is released for use, or transferred to places where electricity is scarce for use.

[0053] See also Figure 1 The embodiment of the present application provides an energy storage device 300 , which includes a box body 310 and a plurality of battery cells 200 , wherein the box body 310 has a receiving cavity 311 ; and the plurality of battery cells 200 are received in the receiving cavity 311 .

[0054] The energy storage device 300 of the embodiment of the present application may be, but is not limited to, at least one of an energy storage module, an energy storage cabinet, an energy storage box, an energy storage container, etc. The energy storage device 300 of the embodiment of the present application may be applied to power grids, homes, industrial applications, vehicles, etc., to store electrical energy and provide electrical energy to electrical loads when needed.

[0055] Optionally, there may be a plurality of accommodating cavities 311 , and each accommodating cavity 311 is used to accommodate one group of battery modules or multiple groups of battery modules.

[0056] Optionally, the battery cell 200 may be, but is not limited to, a secondary battery (rechargeable battery), a primary battery, or the like.

[0057] Optionally, the battery cell 200 may be, but is not limited to, a lithium ion secondary battery, a lithium ion primary battery, a lithium sulfur battery, a sodium lithium ion battery, a sodium ion battery, a magnesium ion battery, or the like.

[0058] A secondary battery, also known as a rechargeable battery or storage battery, is a battery that can be recharged to activate the active material after being discharged and continue to be used. The recyclable nature of secondary batteries has made them gradually become the main power source for electrical equipment.

[0059] Optionally, a plurality of battery cells 200 may be connected in series, in parallel, or in mixed connection.

[0060] Optionally, the plurality of battery cells 200 may be arranged in an array or stacked. In a specific embodiment, the plurality of battery cells 200 are divided into a plurality of battery modules, each battery module includes a plurality of battery cells 200, and the plurality of battery cells 200 of each battery module are arranged in an array or stacked, and the plurality of battery modules are arranged or stacked at intervals.

[0061] See also Figures 2 to 5 The embodiment of the present application also provides a battery cell 200, which includes a shell 210, an end cover assembly 100 and an electrode assembly 220, wherein the end cover assembly 100 and the shell 210 enclose a receiving cavity 230; the electrode assembly 220 is disposed in the receiving cavity 230, and the electrode assembly 220 is electrically connected to the pole 50 of the end cover assembly 100.

[0062] It can be understood that the top cover 10 of the end cover assembly 100 is connected to the shell 210. Optionally, the top cover 10 is connected to the shell 210 by welding.

[0063] Optionally, the material of the housing 210 may be, but is not limited to, aluminum.

[0064] Optionally, the battery cell 200 may be, but is not limited to, at least one of a blade battery, a cylindrical battery, a square battery, and the like.

[0065] Optionally, the electrode assembly 220 includes a positive electrode sheet 221, a separator 222 and a negative electrode sheet 223. The separator 222 is located between the positive electrode sheet 221 and the negative electrode sheet 223, and is used to insulate the positive electrode sheet 221 from the negative electrode sheet 223. The electrode assembly 220 may be, but is not limited to, a winding structure, a laminated structure, etc.

[0066] Optionally, the electrode 50 may be a positive electrode 50a or a negative electrode 50b. When the electrode 50 is a positive electrode 50a, the positive electrode 50a is electrically connected to the positive electrode plate 221; when the electrode 50 is a negative electrode 50b, the negative electrode 50b is electrically connected to the negative electrode plate 223.

[0067] Optionally, the end cap assembly 100 includes a positive electrode column 50a and a negative electrode column 50b, and the positive electrode column 50a is insulated from the negative electrode column 50b.

[0068] Optionally, the battery cell 200 further includes an electrolyte, and the electrolyte is disposed in the receiving cavity 230 .

[0069] Optionally, the electrolyte includes an electrolyte salt and an organic solvent. The electrolyte salt may be, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalatoborate) (LiBOB), lithium difluorobis(oxalatophosphate) (LiODFP), lithium difluorobis(oxalatoborate) (LiODFB), lithium difluorophosphate (LiPO2F2), lithium trifluoromethanesulfonate (CF3SO3Li), etc.

[0070] In the related art, the end cap assembly of the battery cell needs to use an upper plastic part to insulate the pole and the pressure ring from the top cover. In addition, a sealing ring needs to be set between the top cover and the pole, and the sealing ring is compressed through the cooperation of the upper plastic, the pole and the top cover to prevent the battery cell from leaking (i.e., electrolyte leakage). However, the upper plastic is made of resin. When the battery cell has thermal runaway, the temperature of the battery cell increases, which easily causes the upper plastic to melt, and the pole is easy to sink and shrink into the upper plastic, thereby reducing the compression of the sealing ring, making the battery cell prone to electrolyte leakage, reducing the safety performance of the battery cell.

[0071] See also Figures 4 to 7The embodiment of the present application provides an end cover assembly 100, which includes a top cover 10, an upper plastic 20, a pressure ring 30 and a stopper 40. The top cover 10 has a first surface 11 and a second surface 12 that are arranged opposite to each other along the thickness direction thereof. The top cover 10 also has a mounting hole 13, a sink 14 and a groove 15. The mounting hole 13 passes through the first surface 11 and the second surface 12 respectively. The sink 14 is arranged around the outer periphery of the mounting hole 13. The sink 14 passes through the second surface 12 and is connected to the mounting hole 13. The groove 15 is located on the bottom wall of the sink 14. The upper plastic 20 is arranged in the sink 14 and partially penetrates the mounting hole 13. The upper plastic 20 corresponds to the The groove 15 has a through hole 201; the pressure ring 30 is arranged on the side of the upper plastic 20 away from the top cover 10 and abuts against the upper plastic 20, and the pressure ring 30 faces the surface of the upper plastic 20 and has a blind hole 31 at the position corresponding to the through hole 201; the limiting member 40 is penetrated by the through hole 201, and the limiting member 40 is partially located in the groove 15 and partially located in the blind hole 31; wherein, along the thickness direction of the top cover 10, the distance between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 is greater than the height of the limiting member 40.

[0072] It should be noted that when the pole 50 is a positive pole 50a, the pressure ring 30 is a positive pole pressure ring 30a; when the pole 50 is a negative pole 50b, the pressure ring 30 is a negative pole pressure ring 30b. It can be understood that the end cap assembly 100 includes a positive pole 50a, a negative pole 50b, a positive pole pressure ring 30a and a negative pole pressure ring 30b.

[0073] It should be noted that when the end cap assembly 100 is assembled to the battery cell 200, the first surface 11 is closer to the interior of the battery cell 200 than the second surface 12. In other words, the second surface 12 is closer to the outer surface of the battery cell 200 than the first surface 11. In some embodiments, the second surface 12 serves as a partial appearance surface of the battery cell 200.

[0074] It should be noted that the groove 15 is located on the bottom wall of the sink 14 . It can be understood that the groove 15 is formed by a depression of a part of the bottom wall of the sink 14 .

[0075] See also Figure 6Optionally, the top cover 10 includes a connected cover body 16 and a mounting portion 17, the cover body 16 is arranged around the periphery of the mounting portion 17, the cover body 16 has a first surface 11 and a second surface 12 arranged opposite to each other, the mounting portion 17 has the mounting hole 13, the surface of the mounting portion 17 connected to the first surface 11 is flush with the first surface 11, the surface of the mounting portion 17 away from the first surface 11 is recessed in the second surface 12 to form the sink 14, and the mounting portion 17 also has the groove 15 located on the surface away from the first surface 11. The mounting portion 17 is used to carry the upper plastic 20 and to install the limiter 40.

[0076] Optionally, the material of the top cover 10 may be but is not limited to aluminum, such as a plain aluminum sheet.

[0077] Optionally, the pressing ring 30 is partially embedded in the upper plastic 20 .

[0078] Optionally, the number of the grooves 15 may be one or more. When the number of the grooves 15 is more than one, the plurality of grooves 15 are spaced apart on the bottom wall of the sink 14. Specifically, the plurality of grooves 15 may be evenly distributed. Optionally, the groove 15 also penetrates the inner side wall of the mounting hole 13, that is, the groove 15 is connected to the mounting hole 13. In other embodiments, the groove 15 does not penetrate the inner side wall of the mounting hole 13, that is, the groove 15 is not connected to the mounting hole 13.

[0079] It is understandable that the upper plastic 20 is partially located in the sink 14 and partially located in the mounting hole 13. It is also understandable that the upper plastic 20 is carried by the sink 14 of the top cover 10. In other words, the upper plastic 20 is located on the second surface 12 side of the top cover 10 and is partially embedded in the top cover 10.

[0080] It can be understood that the upper plastic 20 is used to insulate the top cover 10 from the pole 50 , and the upper plastic 20 is also used to insulate the top cover 10 from the pressure ring 30 .

[0081] Optionally, the number of the through holes 201 may be one or more. When the number of the through holes 201 is multiple, the multiple through holes 201 are arranged at intervals around the circumference of the upper plastic 20. Specifically, the multiple through holes 201 may be evenly distributed. Optionally, the number of the through holes 201 is arranged in a one-to-one correspondence with the number of the grooves 15.

[0082] It can be understood that the blind hole 31 penetrates the surface of the pressure ring 30 facing the top cover 10. Optionally, the number of the blind holes 31 can be one or more. When the number of the blind holes 31 is multiple, the multiple blind holes 31 are arranged around the circumference of the pressure ring 30 at intervals.

[0083] Optionally, the number of the limiting members 40 may be one or more. When the number of the limiting members 40 is multiple, the multiple limiting members 40 are arranged at intervals around the outer circumference of the mounting hole 13. Specifically, the multiple limiting members 40 may be evenly distributed. Optionally, the number of the limiting members 40 is arranged in a one-to-one correspondence with the number of the grooves 15.

[0084] Optionally, the number of the limiting members 40 may be 1 to 8. Specifically, the number of the limiting members 40 may be, but is not limited to, 1, 2, 3, 4, 5, 6, 7, 8, and the like.

[0085] Optionally, the limiting member 40 is fixed to the upper plastic 20 by interference fit.

[0086] Please also see Figure 5 and Figure 8 In some embodiments, the end cap assembly 100 further includes a pole 50 and a sealing ring 60. The pole 50 includes a flange portion 51 and a penetration portion 52, wherein the flange portion 51 is located on the first surface 11 side of the top cover 10, and the penetration portion 52 is convexly arranged on the flange portion 51. The penetration portion 52 is sequentially penetrated through the top cover 10, the upper plastic 20 and the pressure ring 30, and the penetration portion 52 is connected to the pressure ring 30. The sealing ring 60 is arranged around the outer periphery of the penetration portion 52, and the sealing ring 60 is partially located in the mounting hole 13, and the sealing ring 60 is also partially located between the top cover 10 and the flange portion 51.

[0087] It can be understood that the flange portion 51 and the penetration portion 52 are arranged along the thickness direction of the top cover 10. In the direction perpendicular to the thickness direction of the top cover 10, the radial dimension of the flange portion 51 is greater than the radial dimension of the penetration portion 52.

[0088] It is understandable that the flange portion 51 is located on the side of the top cover 10 away from the second surface 12 ; it is also understandable that the flange portion 51 is located on the side of the top cover 10 away from the pressure ring 30 .

[0089] It can be understood that the penetration portion 52 is penetrated through the mounting hole 13 of the top cover 10. The upper plastic 20 and the pressure ring 30 are both disposed around the outer circumference of the penetration portion 52. The penetration portion 52 is also penetrated through the sealing ring 60.

[0090] It can be understood that the sealing ring 60 is partially located between the penetration portion 52 and the top cover 10 .

[0091] Optionally, the pole 50 and the pressure ring 30 are both made of metal (such as aluminum). The pole 50 and the pressure ring 30 are welded to each other so that the pole 50 and the pressure ring 30 are electrically connected. Further, the penetration portion 52 is welded to the pressure ring 30.

[0092] It should be noted that the sealing ring 60 respectively abuts against the flange portion 51, the penetration portion 52, the first surface 11 of the top cover 10, the inner side wall of the mounting hole 13, and the upper plastic 20. Through the cooperation of the flange portion 51 of the pole 50, the pressure ring 30, the upper plastic 20 and the top cover 10, after the end cover assembly 100 is assembled, the sealing ring 60 has a certain amount of compression (that is, the sealing ring 60 has elasticity). That is, when the sealing ring 60 is assembled in the end cover assembly 100, the sealing ring 60 is in a compressed state. In this way, the gap between the top cover 10 and the pole 50 can be better sealed, so that leakage in the battery cell 200 can be better avoided.

[0093] The end cap assembly 100 of the embodiment of the present application comprises a top cover 10, an upper plastic 20, a pressure ring 30 and a stopper 40. The top cover 10 has the groove 15, the upper plastic 20 has the through hole 201, the pressure ring 30 has a blind hole 31, the stopper 40 is penetrated by the through hole 201, and the stopper 40 is partially located in the groove 15 and partially located in the blind hole 31; wherein, along the thickness direction of the top cover 10, the distance between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 is greater than the height of the stopper 40. Therefore, after the end cover assembly 100 is assembled, the pressure ring 30 is supported by the upper plastic 20, and the sealing ring 60 can be compressed stably by the cooperation of the pressure ring 30, the lower plastic, the top cover 10 and the pole 50; when the battery cell 200 has thermal runaway, the temperature of the pole 50 and the pressure ring 30 rises, causing the upper plastic 20 to melt, the rebound force of the sealing ring 60 to be released, and the pole 50 will sink. When the pole 50 sinks to a certain distance, the limiter 40 will resist and support the pressure ring 30, thereby preventing the pressure ring 30 and the pole 50 from sinking, and preventing the rebound force of the sealing ring 60 from being completely released, so as to better avoid leakage of the battery cell 200 and improve the safety of the use of the battery cell 200.

[0094] In addition, after the end cap assembly 100 is assembled on the battery cell 200, when the battery cell 200 is used in the energy storage device, the multiple battery cells 200 need to be electrically connected through the tab (i.e., electrical connector, such as aluminum sheet), and the tab is welded to the surface of the through-hole 52 of the pole 50 away from the flange portion 51 by laser welding. However, there are inevitably some defects in the welding of the tab. When the welding of the tab has defects and needs to be reworked, the old tab needs to be removed from the pole 50. When the tab is removed, it is usually removed by twisting (or torsion). The twisting of the tab will apply a torsional force to the pole 50. When the torsional force is too large, it is easy to cause the sealing ring 60 to fail, causing the battery cell 200 to leak. In the embodiment of the application, by setting a limit member 40, when the bar is twisted, the torsional force generated on the pole 50 will be transmitted to the top cover 10 through the limit member 40, thereby improving the torsional strength of the pole 50, thereby better preventing the sealing ring 60 from failing, reducing the risk of leakage of the battery cell 200, and improving the safety of the use of the battery cell 200.

[0095] See also Figures 9 to 11 In some embodiments, along the thickness direction of the top cover 10, the distance between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 is s1, and the height of the limiter 40 is h1, then 0.05mm≤s1-h1≤0.15mm.

[0096] It can be understood that the difference s1 - h1 between the distance s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 and the height h1 of the stopper 40 is in the range of 0.05 mm to 0.15 mm.

[0097] Specifically, the difference s1-h1 between the distance s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 and the height h1 of the limit member 40 can be but is not limited to 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, etc.

[0098] In this embodiment, the difference s1-h1 between the distance s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 and the height h1 of the stopper 40 is too small. Since there are usually errors in the manufacturing processes of the stopper 40, the top cover 10, the pressure ring 30 and the upper plastic 20, after the end cover assembly 100 is assembled, the stopper 40 is easy to abut against the pressure ring 30, thereby lifting the pressure ring 30, so that there is a gap between the pressure ring 30 and the upper plastic 20, thereby reducing the stability of the compression amount of the sealing ring 60, resulting in the upper plastic 20 and the sealing ring 60 of different end cover assemblies 100. The different compression amounts reduce the dimensional stability of the end cap assembly 100; if the difference s1-h1 between the spacing s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 and the height h1 of the limiter 40 is too large, then when the battery cell 200 has thermal runaway, the distance between the limiter 40 and the pressure ring 30 is too large, which reduces the supporting effect of the limiter 40 on the pressure ring 30, making it difficult to prevent the pressure ring 30 from excessively sinking, thereby reducing the compression amount of the sealing ring 60 and reducing the sealing performance of the sealing ring 60, thereby increasing the risk of leakage of the battery cell 200. When the difference s1-h1 between the distance s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 and the height h1 of the limiter 40 is in the range of 0.05mm to 0.15mm, after the end cover assembly 100 is assembled, the limiter 40 is not easy to lift the pressure ring 30, which can better ensure the stability of the compression amount of the sealing ring 60; at the same time, when the battery cell 200 has thermal runaway, the limiter 40 can support the pressure ring 30 to prevent the pressure ring 30 from sinking too much, thereby better preventing the battery cell 200 from leaking.

[0099] Furthermore, the range of the difference s1-h1 between the distance s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 and the height h1 of the stopper 40 is: 0.08mm≤s1-h1≤0.12mm. In this way, after the end cap assembly 100 is assembled, the stopper 40 is less likely to lift the pressure ring 30, which can better ensure the stability of the compression amount of the sealing ring 60; at the same time, when the battery cell 200 has thermal runaway, the stopper 40 can better support the pressure ring 30 and better prevent the pressure ring 30 from sinking too much, thereby better preventing the battery cell 200 from leaking.

[0100] In some embodiments, the distance s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 is in the range of 0.7 mm≤s1≤3.1 mm.

[0101] Specifically, the spacing s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 may be, but is not limited to, 0.7 mm, 0.8 mm, 1.0 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2.0 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3.0 mm, 3.1 mm, etc.

[0102] In this embodiment, if the spacing s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 is too small, the upper plastic 20 between the pressure ring 30 and the top cover 10 is too thin, which reduces the strength of the upper plastic 20. In addition, the limiter 40 easily lifts the pressure ring 30, so that there is a gap between the pressure ring 30 and the upper plastic 20, thereby reducing the stability of the compression amount of the sealing ring 60, resulting in different compression amounts of the upper plastic 20 and the sealing ring 60 of different end cover assemblies 100, thereby reducing the dimensional stability of the end cover assembly 100. If the spacing s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 is too large, the thickness of the end cover assembly 100 along the top cover 10 direction is too large, The material consumption of the end cover assembly 100 is increased, thereby increasing the cost of the end cover assembly 100. In addition, if the spacing s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 is too large, the depth of the groove 15 and the depth of the blind hole 31 are relatively large, thereby reducing the mechanical strength of the pressure ring 30 and the top cover 10. Furthermore, if the spacing s1 between the bottom wall of the groove 15 and the bottom wall of the blind hole 31 is too large, the pressure ring 30 may need to sink a large distance to abut against the limit member 40 when the battery cell 200 has thermal runaway, thereby reducing the limiting effect of the limit member 40, reducing the compression amount of the sealing ring 60, and increasing the probability of leakage of the battery cell 200.

[0103] Optionally, along the thickness direction of the top cover 10 , the range of the height h1 of the limiting member 40 is: 0.6 mm≤h1≤3.0 mm.

[0104] Specifically, along the thickness direction of the top cover 10, the height h1 of the limiter 40 can be but is not limited to 0.6mm, 0.8mm, 1.0mm, 1.3mm, 1.5mm, 1.8mm, 2.0mm, 2.3mm, 2.5mm, 2.8mm, 3.0mm, etc.

[0105] In this embodiment, along the thickness direction of the top cover 10, the height h1 of the limiter 40 is too small. Then, when the battery cell 200 has thermal runaway, the pressure ring 30 needs to sink a large distance to abut against the limiter 40, thereby reducing the limiting effect of the limiter 40, reducing the compression amount of the sealing ring 60, and increasing the probability of leakage of the battery cell 200. Along the thickness direction of the top cover 10, if the height h1 of the limiter 40 is too large, the limiter 40 is easy to abut against the pressure ring 30, thereby lifting the pressure ring 30, so that the pressure ring 30 There is a gap between the ring 30 and the upper plastic 20, which reduces the stability of the compression amount of the sealing ring 60, resulting in different compression amounts of the upper plastic 20 and the sealing ring 60 of different end cover assemblies 100, reducing the dimensional stability of the end cover assembly 100; in addition, the thickness of the end cover assembly 100 along the direction of the top cover 10 needs to be made larger, which increases the material consumption of the end cover assembly 100, thereby increasing the cost of the end cover assembly 100; furthermore, the depth of the groove 15 and the depth of the blind hole 31 need to be made larger, which reduces the mechanical strength of the pressure ring 30 and the top cover 10.

[0106] See also Fig.11 In some embodiments, along the thickness direction of the top cover 10 , the depth h2 of the groove 15 is in the range of 0.2 mm ≤ h2 ≤ 1.5 mm.

[0107] Specifically, along the thickness direction of the top cover 10, the depth h2 of the groove 15 can be but is not limited to 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, etc.

[0108] Optionally, the limiting member 40 abuts against the bottom wall of the groove 15 , and the limiting member 40 is embedded in the groove 15 to a depth ranging from 0.2 mm to 1.5 mm.

[0109] In this embodiment, along the thickness direction of the top cover 10, the depth h2 of the groove 15 is too small, and the length of the limiter 40 embedded in the top cover 10 is too short. When the pole 50 is twisted, the limiter 40 is easy to escape from the groove 15 of the top cover 10, and the torsional force of the pole 50 cannot be transmitted to the top cover 10 through the limiter 40, which reduces the effect of the limiter 40 on improving the torsional strength of the pole 50; along the thickness direction of the top cover 10, the depth h2 of the groove 15 is too large, the top cover 10 needs to be made thicker, and the pole 50 also needs to be made higher, which increases the cost of the end cover assembly 100; when the top cover 10 and the pole 50 are not made thick, the bottom of the top cover 10 supporting the limiter 40 will be insufficiently strong and easily damaged.

[0110] Furthermore, along the thickness direction of the top cover 10 , the depth h2 of the groove 15 is in the range of 0.3 mm ≤ h2 ≤ 1 mm. This can better improve the torsional strength of the pole 50 , and can also make the end cover assembly 100 have a lower cost and better improve the mechanical strength of the top cover 10 .

[0111] Furthermore, along the thickness direction of the top cover 10, the depth h2 of the groove 15 is in the range of 0.3mm≤h2≤0.8mm. This can better improve the anti-torsion strength of the pole 50, and can also make the end cover assembly 100 have a lower cost and better improve the mechanical strength of the top cover 10.

[0112] In some embodiments, along the thickness direction of the top cover 10 , the depth h3 of the blind hole 31 is in the range of 0.3 mm ≤ h3 ≤ 1.6 mm.

[0113] Specifically, along the thickness direction of the top cover 10, the depth h3 of the blind hole 31 can be but is not limited to 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, etc.

[0114] In this embodiment, along the thickness direction of the top cover 10, the depth h3 of the blind hole 31 is too small, and the length of the limiter 40 embedded in the pressure ring 30 is too short. When the pole 50 is twisted, the limiter 40 is easy to come out of the blind hole 31 of the pressure ring 30, and the torsional force of the pole 50 cannot be transmitted to the top cover 10 through the limiter 40, thereby reducing the effect of the limiter 40 on improving the torsional strength of the pole 50; along the thickness direction of the top cover 10, the depth h3 of the blind hole 31 is too large, and the pressure ring 30 and the pole 50 need to be made thicker, increasing the cost of the end cover assembly 100, or when the pressure ring 30 and the pole 50 are not made, the mechanical strength of the pressure ring 30 will be reduced, making it easy for the pressure ring 30 to deform when being welded to the pole 50.

[0115] In some embodiments, the limiting member 40 abuts against the bottom wall of the groove 15 , and along the thickness direction of the top cover 10 , the length L of the limiting member 40 embedded in the blind hole 31 is in the range of: 0.2 mm≤L≤1.5 mm.

[0116] It can be understood that the limiting member 40 is spaced apart from the surface of the top cover 10 and the bottom wall of the blind hole 31 .

[0117] Specifically, the length L of the limit member 40 embedded in the blind hole 31 can be but is not limited to 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, etc.

[0118] In this embodiment, along the thickness direction of the top cover 10, the length L of the limit member 40 embedded in the blind hole 31 is too small, and the length of the limit member 40 embedded in the pressure ring 30 is too short. When the pole 50 is twisted, the limit member 40 is easy to fall out of the blind hole 31 of the pressure ring 30, and the torsional force of the pole 50 cannot be transmitted to the top cover 10 through the limit member 40, thereby reducing the effect of the limit member 40 on improving the torsional strength of the pole 50; if the length L of the limit member 40 embedded in the blind hole 31 is too large, both the pressure ring 30 and the pole 50 need to be made thicker, increasing the cost of the end cover assembly 100, or if the pressure ring 30 and the pole 50 are not made thicker, the mechanical strength of the pressure ring 30 will be reduced, making it easy for the pressure ring 30 to deform when being welded to the pole 50.

[0119] Furthermore, along the thickness direction of the top cover 10, the range of the length L of the stopper 40 embedded in the blind hole 31 is: 0.3mm≤L≤1mm. This can better improve the torsional strength of the pole 50, and can also make the end cover assembly 100 have a lower cost and better improve the mechanical strength of the pressure ring 30.

[0120] Furthermore, along the thickness direction of the top cover 10, the range of the length L of the stopper 40 embedded in the blind hole 31 is: 0.3mm≤L≤0.8mm. This can better improve the torsional strength of the pole 50, make the end cover assembly 100 have a lower cost, and better improve the mechanical strength of the pressure ring 30.

[0121] In some embodiments, the melting point of the stopper 40 is greater than the melting point of the upper plastic 20. The melting point of the upper plastic 20 of the end cap assembly 100 is lower than the melting point of the sealing ring 60, so that when thermal runaway occurs in the battery cell 200 and the upper plastic 20 melts, the stopper 40 and the sealing ring 60 will not melt, so that when the pressure ring 30 and the pole 50 sink, the stopper 40 can well support the pressure ring 30, prevent the pressure ring 30 and the pole 50 from continuing to sink, and prevent the rebound force of the sealing ring 60 from being completely released, so as to better avoid leakage of the battery cell 200 and improve the safety of the battery cell 200.

[0122] Optionally, the upper plastic 20 , the lower plastic and the sealing ring 60 are all made of resin.

[0123] Optionally, the melting point of the sealing ring 60 is greater than the melting point of the upper plastic 20. In some embodiments, the melting point of the upper plastic 20 ranges from 280°C to 300°C, and the melting point of the sealing ring 60 is greater than or equal to 500°C.

[0124] Optionally, the melting point of the stopper 40 is greater than or equal to 500°C. Specifically, the melting point of the stopper 40 may be, but is not limited to, 500°C, 550°C, 600°C, 650°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C, etc. If the melting point of the stopper 40 is too low, the stopper 40 will soften or even melt when the battery cell 200 has thermal runaway, reducing the support effect of the stopper 40 on the pressure ring 30; the higher the melting point of the stopper 40, the better, but it may be difficult to achieve in terms of materials.

[0125] Please see again Figure 8 and Fig.11 Optionally, the penetration portion 52 includes a first penetration sub-portion 521, a second penetration sub-portion 522 and a protruding sub-portion 523 which are sequentially arranged and connected along the thickness direction of the top cover 10, the first penetration sub-portion 521 is connected to the flange portion 51 at one end away from the second penetration sub-portion 522, the first penetration sub-portion 521 penetrates the sealing ring 60, the top cover 10 and the upper plastic 20, the second penetration sub-portion 522 penetrates the pressure ring 30, and the protruding sub-portion 523 protrudes from the surface of the pressure ring 30 and the top cover 10. Along the direction perpendicular to the thickness direction of the top cover 10, the radial dimension of the first penetration sub-portion 521 is greater than the radial dimension of the second penetration sub-portion 522, and the radial dimension of the second penetration sub-portion 522 is greater than the radial dimension of the protruding sub-portion 523. The first penetration sub-portion 521 has a step surface 5211 away from the flange portion 51 . The step surface 5211 is arranged around the outer circumference of the second penetration sub-portion 522 . The step surface 5211 is clearance-matched with the pressure ring 30 .

[0126] It should be noted that the clearance fit between the step surface 5211 and the pressure ring 30 can be achieved in the following ways: (1) a clearance is provided between the step surface 5211 and the pressure ring 30; (2) an avoidance groove is provided on the portion of the pressure ring 30 that overlaps with the step surface 5211.

[0127] In the present embodiment, when there is no gap between the pressure ring 30 and the step surface 5211 (i.e., the pressure ring 30 and the step surface 5211 are in abutment with each other), after the pressure ring 30 is sleeved on the second penetration sub-portion 522 of the pole, before laser welding, the welding tooling will abut against the pressure ring 30 to prevent the pressure ring 30 from moving. At this time, if there is no gap between the pressure ring 30 and the step surface 5211, the pressure ring 30 and the step surface 5211 will interfere with each other, thereby deforming the pressure ring 30, affecting the stability of the compression amount of the upper plastic 20 and the sealing ring 60, resulting in different compression amounts of the upper plastic 20 and the sealing ring 60 of different end cover assemblies 100, thereby reducing the stability of the size of the end cover assembly 100.

[0128] Optionally, the gap w between the step surface 5211 and the pressure ring 30 ranges from 0.01 mm to 0.05 mm. Specifically, the gap w between the step surface 5211 and the pressure ring 30 may be, but is not limited to, 0.01 mm, 0.03 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, etc. In this embodiment, the gap w between the pressure ring 30 and the step surface 5211 is too small. After the pressure ring 30 is sleeved on the second penetration sub-portion 522 of the pole, before laser welding, the welding tooling will support the pressure ring 30 to prevent the pressure ring 30 from moving. At this time, if the gap between the pressure ring 30 and the step surface 5211 is too small, the pressure ring 30 and the step surface 5211 will interfere with each other, thereby deforming the pressure ring 30, affecting the stability of the compression amount of the upper plastic 20 and the sealing ring 60, resulting in different compression amounts of the upper plastic 20 and the sealing ring 60 of different end cover assemblies 100, thereby reducing the stability of the size of the end cover assembly 100. If the gap w between the pressure ring 30 and the step surface 5211 is too large, when the laser passes through the gap between the pressure ring 30 and the second penetration sub-portion 522 during welding and hits the step surface 5211, the laser is easily reflected by the step surface 5211 onto the upper plastic 20, thereby causing the upper plastic 20 to melt, and the effect of preventing welding explosion points cannot be achieved; in addition, if the gap between the pressure ring 30 and the step surface 5211 is too large, when the end cap assembly 100 is assembled on the battery cell 200, the metal particles generated by welding are easy to fall into the battery cell 200, thereby increasing the risk of short circuit of the battery cell 200. When the gap between the pressure ring 30 and the step surface 5211 is in the range of 0.01mm to 0.05mm, the upper plastic 20 and the sealing ring 60 of different end cap assemblies 100 can have a relatively consistent compression amount, and the welding explosion points can be well prevented, reducing the risk of short circuit of the battery cell 200.

[0129] See also Figures 10 to 12In some embodiments, the upper plastic 20 includes a first insulating portion 21, a second insulating portion 22 and a third insulating portion 23 which are bent and connected in sequence, the first insulating portion 21 is located in the mounting hole 13, the second insulating portion 22 is bent in a direction away from the pole 50 compared to the first insulating portion 21 and is located in the sink 14, the second insulating portion 22 has the through hole 201, the third insulating portion 23 is bent in a direction away from the first insulating portion 21 compared to the second insulating portion 22, the first insulating portion 21 is an annular structure, the radial dimension of the inner side wall of the first insulating portion 21 is d1, the radial dimension of the portion of the penetrating portion 52 penetrating the first insulating portion 21 is d2, then: 0.12mm≤d1-d2≤0.3mm.

[0130] It can be understood that the third insulating portion 23 is bent in a direction away from the first surface 11 compared to the second insulating portion 22 .

[0131] Optionally, the third insulating portion 23 protrudes from the second surface 12 of the top cover 10 . The pressure ring 30 also protrudes from the second surface 12 of the top cover 10 .

[0132] It can be understood that the second insulating portion 22 and the third insulating portion 23 are also ring structures.

[0133] In a specific embodiment, the first insulating part 21 is a cylindrical structure, the inner wall of the second insulating part 22 is a cylindrical structure, and the outer wall is a regular hexagonal prism structure, and the inner and outer walls of the third insulating part 23 are both regular hexagonal prism structures.

[0134] It should be noted that the inner side wall of the first insulating portion 21 refers to the surface of the first insulating portion 21 facing the penetration portion 52 .

[0135] It can be understood that the upper plastic 20 is supported on the bottom wall of the groove 14, the pressure ring 30 is supported on the second insulating part 22 (in other words, the pressure ring 30 is arranged against the second insulating part 22), and the third insulating part 23 is arranged around the outer circumference of the pressure ring 30 so that the pressure ring 30 is partially embedded in the third insulating part 23, and the surface of the through-setting part 52 facing away from the flange part 51 protrudes from the surface of the pressure ring 30 facing away from the top cover 10.

[0136] It can be understood that the first insulating portion 21 is spaced apart from the penetration portion 52 of the pole 50. The sum of the gaps on opposite sides of the first insulating portion 21 and the penetration portion 52 is in the range of 0.12 mm to 0.3 mm.

[0137] It can be understood that the radial dimension d1 of the inner wall of the first insulating portion 21 is 0.12 mm to 0.3 mm larger than the radial dimension d2 of the portion of the penetration portion 52 that penetrates the first insulating portion 21 .

[0138] Specifically, the difference d1-d2 between the radial dimension d1 of the inner wall of the first insulating part 21 and the radial dimension d2 of the portion of the penetrating part 52 penetrating the first insulating part 21 can be but is not limited to 0.12mm, 0.14mm, 0.16mm, 0.18mm, 0.20mm, 0.22mm, 0.24mm, 0.26mm, 0.28mm, 0.3mm, etc.

[0139] It should be noted that the portion of the penetration portion 52 that penetrates the first insulating portion 21 is the first penetration sub-portion 521 .

[0140] In this embodiment, the difference d1-d2 between the radial dimension d1 of the inner wall of the first insulating portion 21 and the radial dimension d2 of the portion of the penetration portion 52 that penetrates the first insulating portion 21 is too small. Then, when the pressure ring 30 is sleeved on the penetration portion 52 and laser welding is used to weld the pressure ring 30 to the penetration portion 52 of the pole 50, when the laser passes through the gap between the penetration portion 52 and the pressure ring 30, it is easy to hit the first insulating portion 21, or the molten aluminum liquid on the penetration portion 52 is easy to heat the first insulating portion 21, so that the first insulating portion 21 softens or partially melts, thereby generating gas or smoke, and then the welding between the pole 50 and the pressure ring 30 has a welding explosion point, which affects the stability and reliability of the welding between the pole 50 and the pressure ring 30; In addition, the generation of gas or black smoke can easily cause black carbonization marks to appear on the surface of the pole 50 that is away from the first surface 11, affecting the appearance of the end cover assembly 100 and reducing the welding yield of the end cover assembly 100; the difference d1-d2 between the radial dimension d1 of the inner wall of the first insulating portion 21 and the radial dimension d2 of the portion of the penetration portion 52 that penetrates the first insulating portion 21 is too large, and when the pressure ring 30 is welded to the penetration portion 52 of the pole 50, welding slag can easily fall into the battery cell 200, increasing the probability of short circuit in the battery cell 200; in addition, if d1-d2 is too large, the upper plastic 20 needs to be made thinner, which reduces the strength of the upper plastic 20, or the overall size of the upper plastic 20 needs to be made larger, increasing the cost of the end cover assembly 100.

[0141] Furthermore, the difference d1-d2 between the radial dimension d1 of the inner wall of the first insulating portion 21 and the radial dimension d2 of the portion of the penetration portion 52 that penetrates the first insulating portion 21 is in the range of 0.16mm≤d1-d2≤0.25mm. This can avoid the probability of welding explosion points when the pressure ring 30 and the pole 50 are welded, and can better prevent welding slag from falling into the battery cell 200 during welding, thereby better reducing the probability of short circuit of the battery cell 200.

[0142] Please see again Fig.10 In some embodiments, the radial dimension of the outer wall of the first insulating portion 21 is d3, and the radial dimension of the mounting hole 13 is d4, then 0<d4-d3≤0.17mm.

[0143] It should be noted that the outer side wall of the first insulating portion 21 refers to the surface of the first insulating portion 21 away from the penetration portion 52 , that is, the surface of the side wall of the first insulating portion 21 facing the mounting hole 13 .

[0144] It can be understood that the radial dimension of the mounting hole 13 refers to the radial dimension of the side wall of the mounting hole 13 .

[0145] Optionally, the outer wall of the first insulating portion 21 is cylindrical, and the radial dimension of the outer wall of the first insulating portion 21 refers to the outer diameter of the first insulating portion 21. The mounting hole 13 is circular, and the radial dimension of the mounting hole 13 refers to the diameter of the mounting hole 13.

[0146] It can be understood that the difference d4-d3 between the radial dimension d4 of the mounting hole 13 and the radial dimension d3 of the outer side wall of the first insulating portion 21 is in the range of 0<d4-d3≤0.17mm.

[0147] Specifically, the difference d4-d3 between the radial dimension d4 of the mounting hole 13 and the radial dimension d3 of the outer wall of the first insulating part 21 can be but is not limited to 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.10mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, etc.

[0148] In this embodiment, if the difference d4-d3 between the radial dimension d4 of the mounting hole 13 and the radial dimension d3 of the outer side wall of the first insulating portion 21 is too small, the difficulty of assembling the upper plastic 20 is increased; if the difference d4-d3 between the radial dimension d4 of the mounting hole 13 and the radial dimension d3 of the outer side wall of the first insulating portion 21 is too large, the upper plastic 20 and the top cover 10 are not easily positioned when the upper plastic 20 is assembled, so that the first insulating portion 21 of the upper plastic 20 is easily in contact with the pole 50. When the pole 50 and the pressure ring 30 are welded, the temperature is easily transferred to the upper plastic 20, causing the upper plastic 20 to melt and generate gas or smoke, thereby causing welding explosion points in the welding between the pole 50 and the pressure ring 30, affecting the stability and reliability of the welding between the pole 50 and the pressure ring 30.

[0149] Furthermore, the difference d4-d3 between the radial dimension d4 of the mounting hole 13 and the radial dimension d3 of the outer wall of the first insulating portion 21 is in the range of 0.01 mm ≤ d4-d3 ≤ 0.17 mm. This makes it easier for the upper plastic 20 to pass through the mounting hole 13, and also allows for better positioning between the upper plastic 20 and the top cover 10, and during assembly, it can better ensure that there is a gap between the first insulating portion 21 of the upper plastic 20 and the pole 50.

[0150] Furthermore, the difference d4-d3 between the radial dimension d4 of the mounting hole 13 and the radial dimension d3 of the outer wall of the first insulating portion 21 is in the range of 0.08 mm ≤ d4-d3 ≤ 0.12 mm. This makes it easier for the upper plastic 20 to pass through the mounting hole 13, and allows for better positioning between the upper plastic 20 and the top cover 10, and during assembly, it is better to ensure that there is a gap between the first insulating portion 21 of the upper plastic 20 and the pole 50.

[0151] In some embodiments, the difference d1-d2 between the radial dimension d1 of the inner wall of the first insulating portion 21 and the radial dimension d2 of the portion of the penetration portion 52 penetrating the first insulating portion 21 is greater than the difference d4-d3 between the radial dimension d4 of the mounting hole 13 and the radial dimension d3 of the outer wall of the first insulating portion 21. That is, d1-d2>d4-d3.

[0152] It can be understood that the gap between the first insulating portion 21 and the penetration portion 52 is larger than the gap between the first insulating portion 21 and the top cover 10 .

[0153] The upper plastic 20 is positioned through the mounting hole 13 of the top cover 10. In the present embodiment, by making the gap between the first insulating portion 21 and the penetration portion 52 larger than the gap between the first insulating portion 21 and the top cover 10, it is possible to better avoid the upper plastic 20 contacting the pole 50 due to assembly errors, and effectively prevent the welding temperature from being transmitted to the upper plastic 20 when the pressure ring 30 is welded to the pole 50, causing the upper plastic 20 to melt and produce gas or smoke, thereby causing the welding between the pole 50 and the pressure ring 30 to have a welding explosion point, affecting the stability and reliability of the welding between the pole 50 and the pressure ring 30.

[0154] In some embodiments, the pressing ring 30 is made by a stamping process, the inner wall of the pressing ring 30 is cylindrical, and the outer wall of the pressing ring 30 is a regular hexagonal prism.

[0155] It can be understood that the surface of the pressure ring 30 facing the pole 50 is cylindrical, and the surface of the pressure ring 30 away from the pole 50 is a regular hexagonal prism.

[0156] In this embodiment, the pressure ring 30 is made of a whole piece of aluminum plate and is formed by a stamping process. The inner wall of the pressure ring 30 is cylindrical, and the outer wall of the pressure ring 30 is a regular hexagonal prism. The regular hexagonal prisms of the outer walls of multiple pressure rings 30 can be arranged more closely (i.e., in a honeycomb structure), so that the gap between adjacent pressure rings 30 is smaller, and less waste is generated during the stamping process of the pressure ring 30, thereby better improving the utilization rate of materials and reducing the preparation cost of the pressure ring 30.

[0157] In some embodiments, the number of the grooves 15 and the through holes 201 are both three, the grooves 15 and the through holes 201 are evenly distributed and correspond one to one, the number of the limiting members 40 is three, each limiting member 40 is respectively penetrated through a group of grooves 15 and through holes 201, and the number of the blind holes 31 is six.

[0158] Optionally, the outer side of the pressing ring 30 is in the shape of a regular hexagonal prism, and the six blind holes 31 are respectively arranged at the six corners of the regular hexagonal prism.

[0159] Optionally, the inner wall of the second insulating portion 22 is a cylindrical structure, and the outer wall is a regular hexagonal prism structure. The three through holes 201 are respectively located at three corners of the regular hexagonal prism of the second insulating portion 22 .

[0160] In this embodiment, there are three limit members 40, and the three limit members can form a more stable plane, so that when the battery cell has thermal runaway, the three limit members 40 can cooperate to better support the pressure ring 30, and can better ensure the compression of the sealing ring 60 to prevent the battery cell from leaking. When the pressure ring 30 is assembled, the blind hole 31 of the pressure ring 30 is installed upside down. By setting six blind holes 31 on the pressure ring 30, it is not necessary to identify the position characteristics of the limit members 40 during the assembly process of the pressure ring 30, thereby improving the assembly efficiency of the end cap assembly 100.

[0161] See also Figures 13 to 15 In some embodiments, the top cover 10 assembly further includes a lower plastic 70, the lower plastic 70 includes a main body portion 71, a first convex ring portion 72 and a second convex ring portion 73, the main body portion 71 is located on a surface of the top cover 10 away from the upper plastic 20 (i.e., the first surface 11), the main body portion 71 includes a first through hole 711 and a second through hole 712 arranged at intervals, the first convex ring portion 72 is arranged on the surface of the main body portion 71 away from the top cover 10 and is arranged around the outer periphery of the first through hole 711, the second convex ring portion 73 is arranged on the surface of the main body portion 71 away from the top cover 10 and is arranged around the outer periphery of the second through hole 712, and the first convex ring portion 72 and the second convex ring portion 73 have different sizes.

[0162] Optionally, when the pole 50 is assembled, the penetration portion 52 of the pole 50 is sequentially penetrated through the sealing ring 60, the lower plastic 70, the top cover 10, the upper plastic 20 and the pressure ring 30 from the side of the lower plastic 70 away from the top cover 10. The flange portion 51 of the pole 50 abuts against the surface of the lower plastic 70 away from the top cover 10 and the sealing ring 60.

[0163] It should be noted that the first through hole 711 is used to penetrate the positive electrode column 50a, and the second through hole 712 is used to penetrate the negative electrode column 50b. Optionally, the flange portion 51 of the positive electrode column 50a and the flange portion 51 of the negative electrode column 50b have different sizes.

[0164] In this embodiment, by providing a first convex ring portion 72 and a second convex ring portion 73 on the lower plastic 70, and making the size of the first convex ring portion 72 different from the size of the second convex ring portion 73, a better anti-mistake effect can be achieved to prevent the positive electrode column 50a and the negative electrode column 50b from being installed reversely during the assembly process, thereby causing the end cover assembly 100 to be scrapped.

[0165] Mentioning "embodiment" and "implementation method" in this application means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrases in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments. In addition, it should also be understood that the features, structures or characteristics described in the various embodiments of the present application can be arbitrarily combined to form another embodiment that does not deviate from the spirit and scope of the technical solution of the present application, provided that there is no contradiction between them.

[0166] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the above preferred implementation modes, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. An end cap assembly, characterized in that: include: A top cover, wherein the top cover has a first surface and a second surface that are arranged opposite to each other along a thickness direction thereof, and the top cover also has a mounting hole, a sink and a groove, wherein the mounting hole passes through the first surface and the second surface respectively, the sink is arranged around the outer circumference of the mounting hole, the sink passes through the second surface and communicates with the mounting hole, and the groove is located on the bottom wall of the sink; An upper plastic, the upper plastic is arranged in the sink groove and partially penetrates the mounting hole, and the upper plastic has a through hole at a position corresponding to the groove; A pressure ring, the pressure ring is arranged on a side of the upper plastic away from the top cover and abuts against the upper plastic, the pressure ring faces the surface of the upper plastic and has a blind hole at a position corresponding to the through hole; and A limiting member, wherein the limiting member is passed through the through hole, and the limiting member is partially located in the groove and partially located in the blind hole; wherein, along the thickness direction of the top cover, the distance between the bottom wall of the groove and the bottom wall of the blind hole is greater than the height of the limiting member.

2. The end cap assembly according to claim 1, characterized in that: Along the thickness direction of the top cover, the distance between the bottom wall of the groove and the bottom wall of the blind hole is s1, and the height of the limiting member is h1, then 0.05mm≤s1-h1≤0.15mm.

3. The end cap assembly according to claim 1, characterized in that: The range of the distance s1 between the bottom wall of the groove and the bottom wall of the blind hole is: 0.7mm≤s1≤3.1mm; the range of the height h1 of the limiting member is: 0.6mm≤h1≤3.0mm.

4. The end cap assembly according to claim 1, characterized in that: Along the thickness direction of the top cover, the depth h2 of the groove is in the range of 0.2 mm ≤ h2 ≤ 1.5 mm.

5. The end cap assembly according to claim 1, characterized in that: Along the thickness direction of the top cover, the depth h3 of the blind hole is in the range of 0.3 mm ≤ h3 ≤ 1.6 mm.

6. The end cap assembly according to claim 1, characterized in that: The limiting member abuts against the bottom wall of the groove, and along the thickness direction of the top cover, the range of the length L of the limiting member embedded in the blind hole is: 0.2mm≤L≤1.5mm.

7. The end cap assembly according to claim 1, characterized in that: The upper plastic includes a first insulating portion, a second insulating portion and a third insulating portion which are bent and connected in sequence, the first insulating portion is located in the mounting hole, the second insulating portion is bent in a direction away from the pole compared to the first insulating portion and is located in the sink, the second insulating portion has the through hole, the third insulating portion is bent in a direction away from the first insulating portion compared to the second insulating portion, the first insulating portion is an annular structure, and the radial dimension of the inner side wall of the first insulating portion is d1, The end cover assembly also includes a pole, which includes a flange portion and a penetration portion, the flange portion is located on the first surface side of the top cover, the penetration portion is protruding on the flange portion, the penetration portion is penetrated through the top cover, the upper plastic and the pressure ring in sequence, and the penetration portion is connected to the pressure ring; the radial dimension of the portion of the penetration portion that penetrates the first insulating portion is d2, then: 0.12mm≤d1-d2≤0.3mm.

8. The end cap assembly according to claim 1, characterized in that: The radial dimension of the outer wall of the first insulating portion is d3, and the radial dimension of the mounting hole is d4, then 0<d4-d3≤0.17mm.

9. The end cap assembly according to claim 1, characterized in that: The pressing ring is made by a stamping process, the inner side wall of the pressing ring is cylindrical, and the outer side wall of the pressing ring is a regular hexagonal prism.

10. The end cap assembly according to claim 1, characterized in that: The number of the grooves and the through holes are both three, the grooves and the through holes are evenly distributed and correspond one to one, the number of the limiting members is three, each limiting member is respectively penetrated through a group of grooves and through holes, and the number of the blind holes is six.

11. The end cap assembly according to claim 7, characterized in that: The top cover assembly further includes a sealing ring, which is arranged around the outer circumference of the penetration portion, the sealing ring is partially located in the mounting hole, and the sealing ring is also partially located between the top cover and the flange portion; The top cover assembly also includes a lower plastic, which includes a main body, a first convex ring and a second convex ring. The main body is located on the surface of the top cover away from the upper plastic. The main body includes a first through hole and a second through hole that are spaced apart. The first convex ring is disposed on the surface of the main body away from the top cover and surrounds the outer periphery of the first through hole. The second convex ring is disposed on the surface of the main body away from the top cover and surrounds the outer periphery of the second through hole. The first convex ring and the second convex ring are different in size.

12. A battery cell, characterized in that: include: case; The end cover assembly according to any one of claims 1 to 11, wherein the end cover assembly and the shell form a receiving cavity; as well as An electrode assembly is disposed in the receiving cavity and is electrically connected to the pole of the end cap assembly.

13. An energy storage device, characterized in that: include: A box body having a containing cavity; and A plurality of battery cells as claimed in claim 12, wherein the plurality of battery cells are accommodated in the accommodating cavity.

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