Battery cell assembly method

Abstract

The invention relates to the technical field of power batteries, in particular to an assembling method of a single battery. The single battery comprises a shell and a battery cell, the shell comprises a shell body, a first cover plate and a second cover plate, the shell body is provided with a first opening and a second opening which are oppositely arranged in the first direction, the battery cell comprises an electrode assembly, a first tab and a second tab, and the first tab and the second tab are opposite in polarity and are arranged on the two sides of the electrode assembly in the first direction respectively. The assembly method comprises the following steps: before the electrode assembly is mounted in the shell, welding the first tab with the first electrode terminal of the first cover plate; inserting the electrode assembly into the shell from the first opening; the second tab extends out of the second opening, and the second tab is welded with the second electrode terminal of the second cover plate; and respectively welding and fixing the first cover plate and the second cover plate with the shell.

Description

Technical Field

[0001] This application relates to the technical field of power batteries, and particularly to an assembly method for a battery cell. Background Art

[0002] Currently, the battery cell adopts a design with double-sided tabs. If the tabs on both sides of the battery cell are welded to the cover plate respectively and then the battery cell is installed into the housing, it cannot be installed into the housing. If the battery cell is first installed into the housing and then the tabs on both sides of the battery cell are welded to the cover plate respectively, due to the blockage of the housing, a large welding space needs to be reserved when welding the tabs to the cover plate to ensure that the reserved welding position is sufficient. Therefore, the reserved length of the tabs needs to be relatively long. After the too-long tabs are placed into the housing, they not only occupy a large space, but also the tabs are likely to be inserted backwards into the separator, thus causing a short-circuit risk. Summary of the Invention

[0003] This application provides an assembly method for a battery cell, which can improve the space utilization rate and safety of the battery cell.

[0004] To achieve the above object, the main technical solutions adopted in this application include:

[0005] An embodiment of this application provides an assembly method for a battery cell. The battery cell includes a housing and a battery cell. The housing includes a housing body, a first cover plate, and a second cover plate. The housing body has a first opening and a second opening oppositely arranged along a first direction. The battery cell includes an electrode assembly, a first tab, and a second tab. The first tab and the second tab have opposite polarities and are respectively arranged on both sides of the electrode assembly in the first direction. The assembly method includes the following steps: Before the electrode assembly is installed into the housing body, weld the first tab to the first electrode terminal of the first cover plate; insert the electrode assembly into the housing body through the first opening; the second tab extends out through the second opening, and weld the second tab to the second electrode terminal of the second cover plate; weld and fix the first cover plate and the second cover plate to the housing body respectively.

[0006] In the assembly method for the battery cell proposed by the embodiment of this application, before the electrode assembly is installed into the housing body, the first tab is first welded to the first electrode terminal of the first cover plate. Since the first tab is welded to the first electrode terminal of the first cover plate before being installed into the housing body, the reserved welding length of the first tab is relatively small, thereby reducing the risk of short circuit caused by the first tab being inserted backwards and at the same time reducing the space occupied by the first tab. Description of the Drawings

[0007] To more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0008] Figure 1 It is a flowchart of the steps of the battery cell assembly method of the present application;

[0009] Figure 2 It is a schematic structural diagram of the battery cell of the present application;

[0010] Figure 3 For the present application Figure 2 It is a schematic structural diagram of the E-E cross-section in the present application;

[0011] Figure 4 It is an exploded view of the battery cell of the present application;

[0012] Figure 5 It is a schematic structural diagram of the cage of the present application.

[0013]

Explanation of the reference numerals

[0014] 1: Outer shell; 11: Housing; 110: First opening; 111: Second opening; 12: First cover plate; 13: Second cover plate;

[0015] 2: Battery core; 21: Electrode assembly; 22: First tab; 221: First tab connection part; 23: Second tab; 231: Second tab connection part;

[0016] 3: First adhesive layer;

[0017] 4: Cage; 41: Through hole;

[0018] A: First direction. Specific embodiments

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0020] Unless otherwise defined, all technical and scientific terms used in this application shall have the same meanings as those commonly understood by one of ordinary skill in the technical field to which this application pertains; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "comprising" and "having" and any variations thereof in the specification, claims and drawings of this application are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification, claims or drawings of this application are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship.

[0021] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appearing in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment 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.

[0022] In the description of this application, it should be noted that, unless otherwise clearly specified and defined, the terms "installed", "connected", "coupled", "attached" shall be construed broadly. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0023] The term "and / or" in this application is merely a description of the associated relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally represents an "or" relationship between the associated objects before and after.

[0024] The "plurality" referred to in this application means two or more (including two). Similarly, "multiple groups" means two or more groups (including two groups), and "multiple pieces" means two or more pieces (including two pieces).

[0025] At present, the battery cell adopts a design method with double-sided tabs. If the tabs on both sides of the battery cell are welded to the cover plate respectively and then the battery cell is installed into the housing, it cannot be installed into the housing. If the battery cell is first installed into the housing and then the tabs on both sides of the battery cell are welded to the cover plate respectively, due to the obstruction of the housing, a large welding space needs to be reserved when welding the tabs to the cover plate to ensure that the reserved welding position is sufficient. Therefore, a longer reserved length of the tabs is required. After the too-long tabs are placed into the housing, not only does it occupy a large space, but also the tabs are likely to be inserted backwards into the separator, thus causing a short-circuit risk. Therefore, it is necessary to improve the assembly method of the battery module to reduce the length of the tabs and improve the space utilization rate and safety of the battery module.

[0026] In view of this, referring to Figures 2 to 4 , an embodiment of the present application provides an assembly method for a battery module. The battery module includes a housing 1 and a battery cell 2. The housing 1 includes a housing body 11, a first cover plate 12 and a second cover plate 13. The housing body 11 has a first opening 110 and a second opening 111 oppositely arranged along a first direction A. The battery cell 2 includes an electrode assembly 21, a first tab 22 and a second tab 23. The first tab 22 and the second tab 23 have opposite polarities and are respectively arranged on both sides of the electrode assembly 21 in the first direction A.

[0027] Specifically, the first direction A may be the length direction of the housing body 11 or the width direction of the housing body 11. The first cover plate 12 covers the first opening 110 of the housing body 11, and the second cover plate 13 covers the second opening 111 of the housing body 11. The first tab 22 and the second tab 23 extend from the electrode assembly 21.

[0028] Referring to Figure 1 , the assembly method of the battery module includes the following steps:

[0029] Step S100: Before the electrode assembly 21 is installed into the housing body 11, weld the first tab 22 to the first electrode terminal of the first cover plate 12. Before the electrode assembly 21 is installed into the housing body 11, a certain length of the first tab 22 needs to be reserved for welding to the first electrode terminal of the first cover plate 12. Since the first tab 22 is welded to the first electrode terminal of the first cover plate 12 before the electrode assembly 21 is installed into the housing body 11, the reserved welding length of the first tab 22 is relatively small.

[0030] Step S200: Insert the electrode assembly 21 into the housing body 11 from the first opening 110. Insert the second tab 23 into the housing body 11 from the first opening 110 until the electrode assembly 21 is completely received in the housing body 11 and the first cover plate 12 is located at the first opening 110.

[0031] Step S300: The second tab 23 extends out from the second opening 111, and the second tab 23 is welded to the second electrode terminal of the second cover plate 13. A certain length needs to be reserved for the second tab 23 for welding with the second electrode terminal of the second cover plate 13.

[0032] Step S400: The first cover plate 12 and the second cover plate 13 are respectively welded and fixed to the housing 11.

[0033] Specifically, along the first direction A, the first cover plate 12 is placed on one side of the electrode assembly 21, the welding surface of the first cover plate 12 is stacked with the welding surface of the first tab 22, and the first tab 22 is welded to the electrode terminal of the first cover plate 12. Then the first cover plate 12 is flipped and covered on the electrode assembly 21.

[0034] After the first tab 22 is welded to the first electrode terminal of the first cover plate 12, the electrode assembly 21 is inserted into the housing 11 from the first opening 110, and the second tab 23 extends out from the second opening 111, and the first cover plate 12 connected to the first tab 22 abuts against the first opening 110.

[0035] Along the first direction A, the second cover plate 13 is placed on the other side of the electrode assembly 21, the welding surface of the second cover plate 13 is stacked with the welding surface of the second tab 23, and the second tab 23 is welded to the electrode terminal of the second cover plate 13. The second cover plate 13 is flipped and covered on the electrode assembly 21, and the second cover plate 13 abuts against the second opening 111. Then, the first cover plate 12 is welded to the housing 11 at the first opening 110, and the second cover plate 13 is welded to the housing 11 at the second opening 111.

[0036] In the battery cell assembly method provided by the embodiment of the present application, before the electrode assembly 21 is inserted into the housing 11, the first tab 22 is first welded to the first electrode terminal of the first cover plate 12. Since the first tab 22 is welded to the first electrode terminal of the first cover plate 12 before being inserted into the housing 11, the welding length reserved for the first tab 22 is smaller, thereby reducing the risk of short circuit caused by the first tab 22 being inserted reversely, and at the same time reducing the space occupied by the first tab 22.

[0037] Optionally, referring to Figure 3 , the first tab 22 includes a plurality of first sub-tabs. Before the first tab 22 is welded to the first electrode terminal of the first cover plate 12, one end of the plurality of first sub-tabs connected to the electrode assembly 21 is folded, and one end of the plurality of first sub-tabs away from the electrode assembly 21 is welded to form a first tab connection portion 221.

[0038] A plurality of first sub-tab ears extend from the electrode assembly 21. After gathering the plurality of first sub-tab ears together, the plurality of first sub-tab ears are folded to reduce the length of the first sub-tab ears outside the electrode assembly 21, and shorten the distance between one end of the first sub-tab ears far from the electrode assembly 21 and the electrode assembly 21, thereby reducing the risk of reverse insertion of the first tab ear 22. One end of the plurality of first sub-tab ears far from the electrode assembly 21 is welded to form a first tab ear connection portion 221. Among them, the folding method of the plurality of first sub-tab ears can be V-shaped folding, Z-shaped folding, or other applicable methods, as long as the distance between one end of the first tab ear 22 far from the electrode assembly 21 and the electrode assembly 21 can be shortened.

[0039] In a specific embodiment, after folding the side of the first tab ear 22 close to the electrode assembly 21, it needs to be coated with a layer of glue to shape the folding area of the first tab ear 22, protect the first tab ear 22, and reduce the contact between the first tab ear 22 and the electrodes inside the electrode assembly 21, thereby reducing the risk of short circuit.

[0040] Optionally, refer to Figure 3 , a first glue layer 3 is provided on the surface of the first tab ear connection portion 221. By providing the first glue layer 3 on the first tab ear connection portion 221, the thickness of the first tab ear 22 is increased, the strength of the first tab ear 22 is improved, and the damage to the first tab ear 22 is reduced. And the first glue layer 3 has insulating properties, which can reduce the risk of short circuit caused by the reverse insertion of the first tab ear 22, and at the same time can reduce the risk of short circuit caused by the direct contact between one end of the first tab ear 22 far from the electrode assembly 21 and production devices such as machine tools.

[0041] Optionally, after the first tab ear connection portion 221 is welded to the first electrode terminal of the first cover plate 12 to form a first welding portion, a second glue layer is provided on the surface of the first welding portion.

[0042] Since the thickness of the first tab ear 22 is relatively thin and easy to be damaged, the first tab ear 22 is protected by providing a second glue layer on the first tab ear connection portion 221, reducing the damage to the first tab ear 22; at the same time, the second glue layer can play an insulating role and reduce the short circuit risk.

[0043] Optionally, after the first tab ear 22 is welded to the first electrode terminal of the first cover plate 12, the thickness direction of the first cover plate 12 is orthogonal to the first direction A; the minimum distance a along the first direction A between the first cover plate 12 and the electrode assembly 21 is detected, and it satisfies: 0.5 mm ≤ a ≤ 3 mm.

[0044] Specifically, along the first direction A, the first cover plate 12 is placed on one side of the electrode assembly 21. The thickness direction of the first cover plate 12 is orthogonal to the first direction A, and there is a spacing between the first cover plate 12 and the electrode assembly 21 to reduce the influence of welding heat on the electrode assembly 21. After the first tab 22 is welded to the first cover plate 12, along the first direction A, the minimum spacing a between the electrode assembly 21 and the first cover plate 12 satisfies: 0.5 mm ≤ a ≤ 3 mm. Along the first direction A, if the spacing between the electrode assembly 21 and the first cover plate 12 is too large, it means that the length of the first tab 22 reserved between the first cover plate 12 and the electrode assembly 21 is too long, which will cause the first tab 22 to occupy a large space; if the spacing between the electrode assembly 21 and the first cover plate 12 is too small, it means that the length of the first tab 22 reserved between the first cover plate 12 and the electrode assembly 21 is too small, which will cause the first cover plate 12 to be unable to flip and cover the electrode assembly 21.

[0045] Among them, along the first direction A, the minimum spacing a between the electrode assembly 21 and the first cover plate 12 can be 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm or 3.0 mm.

[0046] Optionally, after the first cover plate 12 is welded and fixed to the housing 11, along the first direction A, there is a gap b for accommodating the first tab 22 between the first cover plate 12 and the electrode assembly 21, satisfying: 1.2 mm ≤ b ≤ 1.8 mm.

[0047] After the first cover plate 12 is flipped, it is located on one side of the electrode assembly 21, and there is a gap between the first cover plate 12 and the electrode assembly 21 for accommodating the first tab 22. That is to say, after the first cover plate 12 is welded and fixed to the housing 11, there is a gap between the first cover plate 12 and the electrode assembly 21 for accommodating the first tab 22. Along the first direction A, there is a gap b for accommodating the first tab 22 between the first cover plate 12 and the electrode assembly 21, satisfying: 1.2 mm ≤ b ≤ 1.8 mm. Along the first direction A, if the gap between the first cover plate 12 and the electrode assembly 21 is too large, the space occupied by the electrode assembly 21 and the first cover plate 12 is large, reducing the space utilization rate; if the gap between the first cover plate 12 and the electrode assembly 21 is too small, it will squeeze the first tab 22, resulting in damage to the first tab 22.

[0048] Among them, along the first direction A, the gap b between the first cover plate 12 and the electrode assembly 21 can be 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm, 1.55mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm or 1.8mm.

[0049] In a specific embodiment, along the first direction A, there is a gap b between the first cover plate 12 and the electrode assembly 21 for accommodating the first electrode tab 22 , which can be calculated by the thickness of the battery cell 2 * 2.93 * 0.0045 * (1.5-3).

[0050] Optionally, refer to Figure 3 The second pole tab 23 includes a plurality of second sub-pole tabs, which are gathered and welded to form a second pole tab connecting portion 231 , and one end of the second pole tab 23 away from the electrode assembly 21 is cut.

[0051] A plurality of second sub-electrode tabs are extended from the electrode assembly 21, and the plurality of second sub-electrode tabs are gathered together and then welded. The second electrode tab 23 is then cut to reduce the length of the second electrode tab 23 outside the electrode assembly 21 and shorten the distance between the end of the second electrode tab 23 away from the electrode assembly 21 and the electrode assembly 21, thereby reducing the risk of the second electrode tab 23 being inserted upside down.

[0052] In a specific embodiment, the side of the second pole ear 23 close to the electrode assembly 21 needs to be covered with a circle of rubber layer to shape the side of the second pole ear 23 close to the electrode assembly 21 to protect the second pole ear 23 and reduce the contact between the second pole ear 23 and the electrode inside the electrode assembly 21, thereby reducing the risk of short circuit.

[0053] Optionally, the second electrode tab connection portion 231 is welded to the second electrode terminal of the second cover plate 13 to form a second welding portion, and a third adhesive layer is disposed on the surface of the second welding portion.

[0054] Since the second pole lug 23 is thin and easily damaged, a third adhesive layer is provided at the second pole lug connecting portion 231 to protect the second pole lug 23 and reduce damage to the second pole lug 23 ; meanwhile, the third adhesive layer can play an insulating role and reduce the risk of short circuit.

[0055] Optionally, refer to Figures 3 to 5 Before the electrode assembly 21 is inserted into the housing 11 through the first opening 110 , a retainer 4 is disposed on the electrode assembly 21 to limit the bending range of the second electrode tab 23 .

[0056] Among them, the cage 4 is configured to have a through hole 41 extending along the first direction A inside; alternatively, the cage 4 includes a first part and a second part, the first part and the second part are detachably connected, and after the first part and the second part are assembled, a through hole 41 extending along the first direction A is formed between the first part and the second part.

[0057] The electrode assembly 21 is inserted between the shells 11 from the first opening 110, and the second tab 23 passes through the through hole 41 of the cage 4. The cage 4 can protect the second tab 23 and reduce the bending of the second tab 23. In addition, the cage 4 has insulating properties, which can reduce the contact between the second tab 23 and the outside, thereby reducing the risk of short circuit.

[0058] Optionally, an insulating film is coated on the outer peripheral surface of the electrode assembly 21 and the outer peripheral surface of the cage 4. Coating an insulating film on the outer peripheries of the electrode assembly 21 and the cage 4 can protect the electrode assembly 21 and the cage 4, reduce the damage to the electrode assembly 21 and the cage 4, and thereby reduce the risk of short circuit of the electrode assembly 21.

[0059] Optionally, the insulating film is welded to the outer peripheral surface of the cage 4.

[0060] Along the circumferential direction of the holding member, the insulating film is welded to the cage 4, and along the circumferential direction of the electrode assembly 21, the insulating film is welded to the electrode assembly 21 to enhance the connection strength between the electrode assembly 21 and the cage 4 and the insulating film.

[0061] Optionally, after the second tab 23 is welded to the second electrode terminal of the second cover plate 13, the thickness direction of the second cover plate 13 is orthogonal to the first direction A; the distance c between the second cover plate 13 and the electrode assembly 21 along the first direction A is detected and satisfies: 0.5 mm ≤ c ≤ 3 mm.

[0062] Specifically, along the first direction A, the second cover plate 13 is placed on one side of the electrode assembly 21, the thickness direction of the second cover plate 13 is orthogonal to the first direction A, and there is a spacing between the second cover plate 13 and the electrode assembly 21 to reduce the influence of the welding heat on the electrode assembly 21. After the second tab 23 is welded to the second cover plate 13, along the first direction A, the minimum spacing between the electrode assembly 21 and the second cover plate 13 is c, which satisfies: 0.5 mm ≤ c ≤ 3 mm. Along the first direction A, if the spacing between the electrode assembly 21 and the second cover plate 13 is too large, it means that the length of the second tab 23 reserved between the second cover plate 13 and the electrode assembly 21 is too long, which will cause the second tab 23 to occupy a large space; if the spacing between the electrode assembly 21 and the second cover plate 13 is too small, it means that the length of the second tab 23 reserved between the second cover plate 13 and the electrode assembly 21 is too small, which will cause the second cover plate 13 to be unable to be turned over and covered on the electrode assembly 21.

[0063] Among them, along the first direction A, the minimum distance c between the electrode assembly 21 and the second cover plate 13 can be 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm or 3.0 mm.

[0064] Optionally, after the second cover plate 13 is welded and fixed to the housing 11, along the first direction A, there is a gap d for accommodating the second tab 23 between the second cover plate 13 and the electrode assembly 21, satisfying: 1.2 mm ≤ d ≤ 1.8 mm.

[0065] After the second cover plate 13 is flipped and located on one side of the electrode assembly 21, there is a gap between the second cover plate 13 and the electrode assembly 21 for accommodating the second tab 23. That is to say, after the second cover plate 13 is welded and fixed to the housing 11, there is a gap between the second cover plate 13 and the electrode assembly 21 for accommodating the second tab 23. Along the first direction A, there is a gap d for accommodating the second tab 23 between the second cover plate 13 and the electrode assembly 21, satisfying: 1.2 mm ≤ d ≤ 1.8 mm. If the gap between the second cover plate 13 and the electrode assembly 21 is too large along the first direction A, the space occupied by the electrode assembly 21 and the second cover plate 13 is large, reducing the space utilization rate; if the gap between the second cover plate 13 and the electrode assembly 21 is too small, the second tab 23 will be squeezed, resulting in damage to the second tab 23.

[0066] Among them, along the first direction A, the gap d between the second cover plate 13 and the electrode assembly 21 can be 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.55 mm, 1.6 mm, 1.65 mm, 1.7 mm, 1.75 mm or 1.8 mm.

[0067] Optionally, the first tab 22 is a negative tab and the second tab 23 is a positive tab.

[0068] Optionally, the first tab 22 is a positive tab and the second tab 23 is a negative tab.

[0069] That is to say, in this application, it is only required that the polarities of the first tab 22 and the second tab 23 are opposite.

[0070] Optionally, the first tab 22 is welded to the first cover plate 12 by resistance welding, and the second tab 23 is welded to the second cover plate 13 by resistance welding or laser welding.

[0071] Since the welding of the first pole tab 22 and the first cover plate 12 is before the electrode assembly 21 is installed in the shell 11, the welding of the first pole tab 22 and the first cover plate 12 is not affected by the shell 11, so the welding space reserved for the first pole tab 22 is small, and resistance welding can be used. The welding of the second pole tab 23 and the second cover plate 13 is after the electrode assembly 21 is installed in the shell 11, and the welding of the second pole tab 23 and the second cover plate 13 is affected by the shell 11, so the welding space reserved for the second pole tab 23 is large, and laser welding or resistance welding can be used.

[0072] In the present application, the assembly method of the battery cell is as follows: first, the first pole tab 22 is gathered, and the side of the first pole tab 22 close to the electrode assembly 21 is folded to reduce the distance between the end of the first pole tab 22 away from the electrode assembly 21 and the electrode assembly 21, thereby reducing the space occupied by the first pole tab 22. A plurality of first sub-pole tabs of the first pole tab 22 are welded to form a first pole tab connecting portion 221, and a first adhesive layer 3 is provided on the first pole tab connecting portion 221.

[0073] The second pole tab 23 is gathered and welded to form a second pole tab connecting portion 231. The end of the second pole tab 23 away from the electrode assembly 21 is cut to reduce the length of the second pole tab 23.

[0074] Along the first direction A, the first cover plate 12 is placed on one side of the electrode assembly 21, the thickness direction of the first cover plate 12 is orthogonal to the first direction A, and the first pole ear 22 is welded to the first electrode terminal of the first cover plate 12. After the first pole ear 22 is welded to the first electrode terminal of the first cover plate 12, along the first direction A, a CCD visual inspection device is used to detect the minimum spacing a between the electrode assembly 21 and the first cover plate 12. Along the first direction A, the minimum spacing a between the electrode assembly 21 and the first cover plate 12 needs to meet the following requirements: 0.5 mm ≤ a ≤ 3 mm.

[0075] The first electrode terminal of the first electrode tab connection portion 221 is welded to the first electrode terminal of the first cover plate 12 to form a first welding portion, and a second adhesive layer is disposed on the surface of the first welding portion. After the minimum spacing between the first cover plate 12 and the electrode assembly 21 is detected to be qualified along the first direction A, the first cover plate 12 is turned over and the first cover plate 12 is covered on the side of the electrode assembly 21.

[0076] The second pole tab 23 is extended into the holder 4, and the holder 4 protects the second pole tab 23 and reduces the bending amplitude of the second pole tab 23. The outer periphery of the electrode assembly 21 and the holder 4 is coated with an insulating film, and the insulating film is welded to the electrode assembly 21 and the holder 4.

[0077] Insert the side of the electrode assembly 21 with the second tab 23 into the housing 11 through the first opening 110, and the second tab 23 extends out of the housing 11 from the second opening 111. The first cover plate 12 is covered at the first opening 110.

[0078] Along the first direction A, place the second cover plate 13 on one side of the electrode assembly 21. The thickness direction of the second cover plate 13 is orthogonal to the first direction A. Weld the second tab 23 to the second electrode terminal of the second cover plate 13. After the welding of the second tab 23 and the second electrode terminal of the second cover plate 13 is completed, along the first direction A, use a CCD vision inspection device to detect the minimum distance c between the electrode assembly 21 and the second cover plate 13. Along the first direction A, the minimum distance c between the electrode assembly 21 and the second cover plate 13 needs to satisfy: 0.5 mm ≤ c ≤ 3 mm. The second tab connection part 231 is welded to the second electrode terminal of the second cover plate 13 to form a second welding part, and a third adhesive layer is provided on the surface of the second welding part. Along the first direction A, after the inspection of the minimum distance between the second cover plate 13 and the electrode assembly 21 is qualified, turn over the second cover plate 13, and the second cover plate 13 is covered on the side of the electrode assembly 21.

[0079] At the first opening 110, weld the first cover plate 12 to the housing 11. Along the first direction A, a gap for accommodating the first tab 22 needs to be reserved between the first cover plate 12 and the electrode assembly 21, and a gap b for accommodating the first tab 22 needs to be reserved between the first cover plate 12 and the electrode assembly 21. Along the first direction A, the gap b for accommodating the first tab 22 between the first cover plate 12 and the electrode assembly 21 needs to satisfy: 1.2 mm ≤ b ≤ 1.8 mm.

[0080] At the second opening 111, weld the second cover plate 13 to the housing 11. Along the first direction A, a gap for accommodating the second tab 23 needs to be reserved between the second cover plate 13 and the electrode assembly 21, and a gap d for accommodating the second tab 23 needs to be reserved between the second cover plate 13 and the electrode assembly 21. Along the first direction A, the gap d for accommodating the second tab 23 between the second cover plate 13 and the electrode assembly 21 needs to satisfy: 1.2 mm ≤ d ≤ 1.8 mm.

[0081] The battery cell assembled by the assembly method of any of the above embodiments of the present application includes a housing 1 and an electrode core 2. The housing 1 includes a housing body 11, a first cover plate 12 and a second cover plate 13. The housing body 11 has a first opening 110 and a second opening 111 oppositely arranged along a first direction A. The first cover plate 12 is connected to the housing body 11 to block the first opening 110, and the second cover plate 13 is connected to the housing body 11 to block the second opening 111. The electrode core 2 includes an electrode assembly 21, a first tab 22 and a second tab 23. The first tab 22 and the second tab 23 have opposite polarities and are respectively arranged on both sides of the electrode assembly 21 in the first direction A. The first tab 22 is connected to the first electrode terminal of the first cover plate 12, and the second tab 23 is connected to the second electrode terminal of the second cover plate 13. Wherein, along the first direction A, the distance b between the electrode assembly 21 and the first cover plate 12 satisfies: 1.2 mm ≤ b ≤ 1.8 mm; the distance d between the electrode assembly 21 and the second cover plate 13 satisfies: 1.2 mm ≤ d ≤ 1.8 mm.

[0082] It should also be noted that the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, commodity or device including the said element.

[0083] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the differences between each embodiment and other embodiments are emphasized. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the description of the method embodiment.

[0084] The above description is only for the embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

[0085] Although the embodiments of the present application are described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A method for assembling a battery cell, wherein the battery cell comprises a shell and a battery cell, wherein the shell comprises a shell, a first cover plate and a second cover plate, wherein the shell has a first opening and a second opening arranged opposite to each other along a first direction, wherein the battery cell comprises an electrode assembly, a first pole ear and a second pole ear, wherein the first pole ear and the second pole ear have opposite polarities and are respectively arranged on both sides of the electrode assembly in the first direction, wherein: The assembly method comprises the following steps: Before the electrode assembly is installed in the housing, welding the first electrode tab to the first electrode terminal of the first cover plate; Inserting the electrode assembly into the housing through the first opening; The second electrode tab extends out from the second opening, and the second electrode tab is welded to the second electrode terminal of the second cover plate; The first cover plate and the second cover plate are respectively welded and fixed to the shell.

2. The method for assembling a battery cell according to claim 1, characterized in that: The first pole tab includes a plurality of first sub-pole tabs. Before welding the first pole tab to the first electrode terminal of the first cover plate, one end of the plurality of first sub-pole tabs connected to the electrode assembly is folded, and one end of the plurality of first sub-pole tabs away from the electrode assembly is welded to form a first pole tab connection portion.

3. The method for assembling a battery cell according to claim 2, characterized in that: A first adhesive layer is disposed on the surface of the first electrode tab connecting portion.

4. The method for assembling a battery cell according to claim 1, characterized in that: The first electrode tab connecting portion is welded to the first electrode terminal of the first cover plate to form a first welding portion, and a second adhesive layer is disposed on a surface of the first welding portion.

5. The method for assembling a battery cell according to claim 1, characterized in that: After the first electrode tab and the first electrode terminal of the first cover plate are welded, the thickness direction of the first cover plate is orthogonal to the first direction; The minimum distance a between the first cover plate and the electrode assembly along the first direction is detected and meets the following conditions: 0.5 mm ≤ a ≤ 3 mm.

6. The method for assembling a battery cell according to claim 1, characterized in that: After the first cover plate is welded and fixed to the shell, a gap b for accommodating the first electrode tab is provided between the first cover plate and the electrode assembly along the first direction, and the gap b satisfies: 1.2 mm ≤ b ≤ 1.8 mm.

7. The method for assembling a battery cell according to claim 1, characterized in that: The second pole tab includes a plurality of second sub-pole tabs, which are gathered and welded to form a second pole tab connecting portion, and an end of the second pole tab away from the electrode assembly is cut.

8. The method for assembling a battery cell according to claim 7, characterized in that: The second electrode tab connecting portion is welded to the second electrode terminal of the second cover plate to form a second welding portion, and a third adhesive layer is disposed on a surface of the second welding portion.

9. The method for assembling a battery cell according to claim 1, characterized in that: Before inserting the electrode assembly into the shell through the first opening, a retaining frame is arranged on the electrode assembly to limit the bending range of the second electrode tab.

10. The method for assembling a battery cell according to claim 9, characterized in that: An insulating film is coated on the outer peripheral surface of the electrode assembly and the outer peripheral surface of the retainer.

11. The method for assembling a battery cell according to claim 10, characterized in that: The insulating film is welded to the outer peripheral surface of the retainer.

12. The method for assembling a battery cell according to claim 1, characterized in that: After the second electrode tab is welded to the second electrode terminal of the second cover plate, the thickness direction of the second cover plate is orthogonal to the first direction; The distance c between the second cover plate and the electrode assembly along the first direction is detected and meets the following condition: 0.5 mm ≤ c ≤ 3 mm.

13. The method for assembling a battery cell according to claim 1, characterized in that: After the second cover plate is welded and fixed to the shell, along the first direction, there is a gap d between the second cover plate and the electrode assembly for accommodating the second electrode tab, which satisfies: 1.2 mm ≤ d ≤ 1.8 mm.

14. The method for assembling a battery cell according to claim 1, characterized in that: The first electrode tab is a negative electrode tab, and the second electrode tab is a positive electrode tab.

15. The method for assembling a battery cell according to claim 1, characterized in that: The first electrode tab is a positive electrode tab, and the second electrode tab is a negative electrode tab.

16. The method for assembling a battery cell according to claim 1, characterized in that: The first electrode tab is welded to the first cover plate by resistance welding, and the second electrode tab is welded to the second cover plate by resistance welding or laser welding.

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