Battery assembly method and battery

Abstract

The present invention belongs to the field of battery technology and discloses a battery assembly method and a battery. The method includes: S1, installing a protective end plate on a pole group; S2, coating an insulating film on the outer side of multiple side surfaces of the pole group, and hot-melting the insulating film and the protective end plate to form a pole group unit; S3, installing a second cover plate module on either side of the pole group; S4, installing the pole group equipped with the second cover plate module into a battery shell; S5, installing the first cover plate module; S6, final welding the battery shell with the first cover plate module and the second cover plate module; S7, welding the composite pole column to the first cover plate module; S8, achieving current conduction between the composite pole column and the tab. By finally achieving current conduction between the tab on either side of the pole group and the composite pole, the influence of other welding processes on the connection quality of the tab on that side and the composite pole is avoided, and the tab on that side is extended out of the battery shell to achieve current conduction with the composite pole column, thereby reducing the occupation of internal space and achieving high space utilization.

Description

Technical Field

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

[0002] The traditional assembly process of blade batteries is usually to first install the pole assembly into the battery shell, then weld the pole to the pole ear of the corresponding polarity, and then install the lower plastic and plain aluminum plate in sequence, and make part of the pole pass through the lower plastic and plain aluminum plate and extend out of the battery shell. After the assembly of the plain aluminum plate is completed, the plain aluminum plate is welded to the battery shell, and then the upper plastic, seal and rivet block are installed in sequence on the outside of the plain aluminum plate corresponding to the part of the pole extending out, and the rivet block is welded to the plain aluminum plate, and the rivet block is riveted to the pole extending out of the plain aluminum plate, thereby completing the assembly of the blade battery.

[0003] However, for blade batteries assembled using this method, on the one hand, it is necessary to complete the welding of the pole ears and the poles first, and then complete the welding of the bare aluminum plate and the battery shell, the welding of the rivet block and the bare aluminum plate, and the riveting of the rivet block and the poles. As a result, the pole ears and poles that have been welded will be affected by adverse factors such as high temperature and vibration during the welding of the bare aluminum plate and the battery shell, the welding of the rivet block and the bare aluminum plate, and the riveting of the rivet block and the poles, thereby reducing the welding quality between the poles and the pole ears and reducing the product yield. On the other hand, since this method also requires that space be reserved inside the battery shell for accommodating the poles and the connection between the poles and the pole ears, the pole ears and poles will occupy a larger space inside the battery shell, limiting the volume of the pole group and resulting in a low energy density. Summary of the Invention

[0004] The object of the present invention is to provide a battery assembly method and a battery with high product yield and energy density.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In one aspect, a battery assembly method is provided, wherein the battery assembled by the battery assembly method includes a battery housing, an electrode group, a first cover plate module, a composite electrode, a protective end plate, and a second cover plate module;

[0007] The battery assembly method comprises the following steps:

[0008] S1. The electrode group includes a first surface and a second surface with electrode tabs, and multiple side surfaces perpendicular to the first and second surfaces. The protective end plate is provided with a first through-structure. The protective end plate is installed on the first surface and / or the second surface of the electrode group, and the electrode tabs pass through the first through-structure.

[0009] S2, covering the outer side of the electrode group with an insulating film so that the insulating film covers the outer sides of the plurality of side surfaces, and hot-melting the insulating film and the protective end plate to form an electrode group unit;

[0010] S3. The second cover plate module includes an independent pole. The second cover plate module is installed on either side of the pole group where the pole lug is provided, and the pole lug on that side passes through the first penetrating structure and is welded to the independent pole.

[0011] S4, the battery housing is a double-sided open structure with a cavity, the electrode group unit equipped with the second cover plate module is installed in the cavity of the battery housing, the second cover plate module closes the opening on one side of the battery housing, and the second cover plate module is pre-welded to the battery housing at a plurality of first pre-welding points arranged at intervals;

[0012] S5. The first cover plate module includes a second penetration structure for the tab to extend and a first insulating layer for isolating the first cover plate module from the tab. The first cover plate module is assembled into the opening on the other side of the battery housing. The tab passing through the first penetration structure passes through the second penetration structure. The first cover plate module and the battery housing are pre-welded at a plurality of second pre-welding points arranged at intervals.

[0013] S6, final welding the battery housing to the first cover plate module and the second cover plate module;

[0014] S7. A receiving groove is further provided on a side of the first cover plate module facing away from the electrode group. The composite electrode is installed in the receiving groove and welded to the first cover plate module.

[0015] S8. Enabling current conduction between the composite pole and the tab.

[0016] Optionally, in step S2, the following steps are further included:

[0017] S21, the battery further includes at least one protective side plate, and at least one protective side plate is pre-heat-fused to a set position of the insulating film;

[0018] S22, covering the plurality of side surfaces of the electrode group with the insulating film, and making at least one of the protective side plates cover one of the side surfaces of the electrode group;

[0019] S23, hot-melt the overlapping area between the insulating film and the protective end plate.

[0020] Optionally, in step S21, the following steps are further included:

[0021] S211, opening a positioning hole at a set position of the insulating film;

[0022] S212, the protective side plate is provided with a positioning structure that cooperates with the positioning hole, the protective side plate is arranged at a set position of the insulating film, and the positioning structure is aligned with the positioning hole;

[0023] S213, hot-melt the assembled protective side plate and the insulating film.

[0024] Optionally, in step S23, the following steps are further included:

[0025] S231, pre-installing the first cover plate module and / or the second cover plate module on a side of the protective end plate facing away from the electrode group;

[0026] S232, measuring the distance L1 between the insulating film and the first cover module, and / or the second cover module and the nearest point therebetween, and determining whether L1 satisfies 0.5 mm ≤ L1 ≤ 3 mm. If so, proceed to step S233; otherwise, proceed to step S234;

[0027] S233: After removing the pre-installed first cover plate module and / or the second cover plate module, heat-seal the overlapping area between the insulating film and the protective end plate to form the electrode group unit;

[0028] S234 , after removing the pre-installed first cover module and / or the second cover module, cutting the insulating film. After the cutting is completed, execute step S231 .

[0029] Optionally, a plurality of thermal melting points are provided in the overlapping region between the insulating film and the protective end plate, and a distance L2 is provided between a boundary of each thermal melting point facing away from the electrode group and a boundary of the overlapping region facing away from the electrode group, and 0.5 mm ≤ L2 ≤ 3 mm is satisfied;

[0030] And / or, the distance between the boundary of each of the thermal melting points facing the pole group and the boundary of the overlapping area facing the pole group is L3, and satisfies 0.5mm≤L3≤3mm.

[0031] Optionally, the first cover plate module includes a cover plate body and the first insulating layer;

[0032] The receiving groove is provided on the cover body, and the cover body is further provided with a plug-in through hole arranged in the receiving groove;

[0033] The first insulating layer is injection molded on the cover body and includes an upper insulating portion, a lower insulating portion and a plug-in portion. The upper insulating portion is provided on the side of the cover body away from the pole group and is located in the accommodating groove. The lower insulating portion is provided on the side of the cover body facing the pole group and is located between the cover body and the protective end plate. The plug-in portion is inserted in the plug-in through hole and is used to connect the upper insulating portion and the lower insulating portion. The second penetrating structure penetrates the upper insulating portion, the plug-in portion and the lower insulating portion and is connected to the first penetrating structure.

[0034] Optionally, in step S7, the following steps are further included:

[0035] S71. A mounting groove is formed on a side of the upper insulating portion facing away from the cover body, and the battery further includes a connecting piece, and the connecting piece is installed in the mounting groove;

[0036] S72, bending the portion of the electrode tab extending out of the second penetrating structure, and welding the bent electrode tab to the connecting piece;

[0037] S73: The battery further includes a sealing ring, and the sealing ring is installed in the receiving groove;

[0038] S74, placing the composite pole into the receiving groove, with the sealing ring being sandwiched between the composite pole and the first cover plate module;

[0039] S75: Welding the composite pole and the first cover plate module.

[0040] Optionally, in step S8, the following steps are further included:

[0041] S81. A connecting boss is provided on a side of the connecting piece facing the composite pole, and is protruding along the composite pole. The composite pole is pre-welded and positioned on the connecting boss by a plurality of third pre-welding points arranged at intervals.

[0042] S82, fully welding the composite pole and the connecting boss.

[0043] Optionally, in step S75, the following steps are further included:

[0044] S751. The composite pole includes a pole body, a welding ring, and a second insulating layer for achieving an insulated connection between the pole body and the welding ring, wherein the welding ring is pre-welded and positioned in the receiving groove through a plurality of fourth pre-welding points arranged at intervals.

[0045] S752, fully weld the welding ring in the receiving groove.

[0046] On the other hand, a battery is provided, which is assembled using any of the battery assembly methods described above.

[0047] Beneficial effects of the present invention:

[0048] The present invention provides a battery assembly method, which provides a first cover plate module with a second penetrating structure on either side of a pole group provided with a pole lug, so that the pole lug on this side can achieve current conduction with a composite pole located outside the battery shell by extending out of the battery shell, thereby eliminating the space occupied by the pole lug on one side being connected to the composite pole and the composite pole extending into the battery shell. On the one hand, this reduces the occupation of the internal space and improves the utilization rate of the space. On the other hand, it provides space for increasing the pole group and improves the energy density. In addition, a protective end plate with a first penetrating structure is provided on the first surface and / or the second surface of the pole group provided with the pole lug, so as to gather and support the pole lug, prevent the pole lug from being skewed, and ensure the reliability of the structure. In addition, when the pole lug on this side and the composite pole are achieved through current conduction, the battery assembly method is performed after the welding of the first cover plate module to the battery shell and the welding of the composite pole to the first cover plate module, thereby effectively avoiding the influence of other welding processes on the connection quality between the pole lug and the composite pole that have achieved current conduction, thereby achieving a higher product yield.

[0049] The present invention also provides a battery, which is assembled by applying the above-mentioned battery assembly method, so that the volume of the electrode group can be further increased, thereby improving the energy density of the battery and increasing the power supply capacity of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a flow chart of the battery assembly method provided by the present invention;

[0051] Figure 2 This is an exploded view of the structure of the battery provided by the present invention;

[0052] Figure 3 This is a structural cross-sectional view of the first cover module side of the battery provided by the present invention;

[0053] Figure 4 This is a schematic diagram of the structure of the thermal fusion of the insulating film and the protective side plate in the battery provided by the present invention;

[0054] Figure 5 This is a schematic diagram of the distribution of hot melting points of the protective end plate and the insulating film in the battery provided by the present invention;

[0055] Figure 6 yes Figure 5 A magnified view of the structure of part A;

[0056] Figure 7This is a schematic diagram of the distribution of pre-welding points between the first cover plate module and the battery housing in the battery provided by the present invention;

[0057] Figure 8 This is an assembly diagram of the second cover module in the battery provided by the present invention;

[0058] Figure 9 This is a structural cross-sectional view of the second cover plate module in the battery provided by the present invention;

[0059] Figure 10 This is a schematic diagram of the structure of the cover plate body in the battery provided by the present invention;

[0060] Figure 11 Schematic diagram of the structure of the first insulating layer in the battery provided by the present invention;

[0061] Figure 12 It is a structural schematic diagram of the protective end plate in the battery provided by the present invention.

[0062] In the picture:

[0063] 100, second pre-welding point;

[0064] 1. Battery casing;

[0065] 2. Pole group; 21. Pole ear; 22. First surface; 23. Second surface; 24. Side surface;

[0066] 3. First cover module; 31. Cover body; 311. Accommodation slot; 312. Insertion hole; 32. First insulation layer; 321. Upper insulation portion; 322. Lower insulation portion; 323. Insertion portion; 324. Mounting slot; 325. Second penetration structure;

[0067] 4. Composite pole; 41. Pole body; 42. Welding ring; 43. Second insulating layer;

[0068] 5. Protective end plate; 51. First penetrating structure; 52. Shaping structure;

[0069] 6. Second cover plate module; 61. Independent pole; 62. Plain aluminum plate; 63. First plastic part; 64. Second plastic part; 65. Sealing part; 66. Riveting block;

[0070] 7. Insulating film; 71. Positioning hole; 72. Thermal melting point;

[0071] 8. Protective side panels;

[0072] 9. Connecting piece; 91. Connecting boss;

[0073] 10. Sealing ring. DETAILED DESCRIPTION

[0074] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0075] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0076] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0077] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0078] In order to improve product yield, reduce additional space occupation, and improve space utilization and energy density, this embodiment provides a battery assembly method. The battery assembled using this battery assembly method includes a battery casing 1, an electrode group 2, a first cover module 3, a composite electrode 4, a protective end plate 5 and a second cover module 6.

[0079] like Figures 1 to 12 As shown, the battery assembly method includes the following steps:

[0080] S1, the electrode group 2 includes a first surface 22 and a second surface 23 with electrode tabs 21, and multiple side surfaces 24 perpendicular to the first surface 22 and the second surface 23. The protective end plate 5 is provided with a first through-structure 51. The protective end plate 5 is installed on the first surface 22 and / or the second surface 23 of the electrode group 2, and the electrode tabs 21 pass through the first through-structure 51.

[0081] S2, covering the outer side of the electrode group 2 with an insulating film 7, so that the insulating film 7 covers the outer sides of multiple side surfaces 24, and hot-melting the insulating film 7 and the protective end plate 5 to form an electrode group unit;

[0082] S3, the second cover plate module 6 includes an independent pole 61, and the second cover plate module 6 is installed on either side of the pole lug 21 of the pole group 2, and the second cover plate module 6 is passed through the pole lug 21 of the first penetrating structure 51 and welded to the independent pole 61;

[0083] S4. The battery housing 1 is a double-sided open structure with a cavity. The electrode group unit equipped with the second cover module 6 is installed in the cavity of the battery housing 1. The second cover module 6 closes the opening on one side of the battery housing 1, and the second cover module 6 and the battery housing 1 are pre-welded at a plurality of first pre-welding points arranged at intervals.

[0084] S5. The first cover plate module 3 includes a second penetration structure 325 for the tab 21 to extend and a first insulating layer 32 for isolating the first cover plate module 3 from the tab 21. The first cover plate module 3 is installed in the opening on the other side of the battery housing 1. The tab 21 passing through the first penetration structure 51 passes through the second penetration structure 325. The first cover plate module and the battery housing 1 are pre-welded at a plurality of second pre-welding points 100 arranged at intervals.

[0085] S6, final welding the battery housing 1, the first cover plate module 3, and the second cover plate module 6;

[0086] S7. A receiving groove 311 is further provided on the side of the first cover plate module 3 facing away from the electrode group 2. The composite electrode 4 is installed into the receiving groove 311 and the composite electrode 4 is welded to the first cover plate module 3.

[0087] S8. Make the current conduction between the composite pole 4 and the tab 21 possible.

[0088] The battery assembly method provides a first cover plate module 3 having a second through structure 325 on either side of the electrode group 2 provided with the electrode ear 21, so that the electrode ear 21 on this side can achieve current conduction with the composite electrode 4 located outside the battery shell 1 by extending out of the battery shell 1, thereby eliminating the need for the electrode ear 21 on one side to be connected to the composite electrode 4 and the space occupied by the composite electrode 4 extending into the battery shell 1. This reduces the internal space occupied and improves the space utilization rate, and provides space for increasing the electrode group 2 and improving the energy density. A protective end plate 5 with a first through structure 51 is provided on the first surface, and / or the second surface, so as to support the pole lug 21 and prevent the pole lug 21 from being skewed, thereby ensuring the reliability of the structure. In addition, when the battery assembly method realizes current conduction between the pole lug 21 and the composite pole 4 on this side, the sequence is after the welding of the first cover module 3 and the battery shell 1 and the welding of the composite pole 4 and the first cover module 3, thereby effectively avoiding the influence of other welding processes on the connection quality between the pole lug 21 and the composite pole 4 that have already achieved current conduction, thereby having a higher product yield.

[0089] In this embodiment, both the first surface 22 and the second surface 23 of the electrode group 2 are equipped with protective end plates 5 .

[0090] In this embodiment, the second cover plate module 6 is a traditional riveted cover plate, which includes, in addition to the independent pole 61, a plain aluminum plate 62, a first plastic part 63, a second plastic part 64, a seal 65 and a riveted block 66. Before assembling the battery, the second cover plate module 6, that is, the riveted cover plate, can be assembled in advance. After the assembly is completed, the pole ear 21 is directly welded to the independent pole 61 in the assembled second cover plate module 6.

[0091] The specific steps include:

[0092] Ⅰ. Use structural adhesive to bond the second plastic part 64 to the side of the bare aluminum plate 62 facing away from the electrode group 2;

[0093] II. Using structural adhesive to bond the first plastic part 63 to the side of the bare aluminum plate 62 facing the electrode group 2;

[0094] III. A positioning groove is provided on the side of the second plastic part 64 facing away from the plain aluminum plate 62, and the riveting block 66 is installed in the positioning groove;

[0095] IV. The independent pole includes a column portion and a limiting portion, and the seal 65 is sleeved on the column portion of the independent pole 61;

[0096] V. Install the independent pole 61 and make the body of the independent pole 61 pass through the first plastic part 63, the plain aluminum plate 62, and the second plastic part 64 in sequence, and finally insert it into the riveting block 66. At this time, the first plastic part 63 is clamped between the limit part of the independent pole 61 and the plain aluminum plate 62;

[0097] VI. Rivet the column body of the independent pole 61 to the riveting block 66 to complete the assembly of the second cover module 6 .

[0098] The type of the second cover plate module 6 is not limited to a traditional riveted cover plate. In other embodiments, the second cover plate module 6 can also be a traditional welded cover plate or a traditional minimalist cover plate.

[0099] In addition, when the first cover plate module 3 and the second cover plate module 6 are pre-welded with the battery housing 1, the number of the first pre-welding points and the second pre-welding points 100 can be freely set according to demand. Taking the welding of the first cover plate module 3 and the battery housing 1 as an example, in this embodiment, since the first cover plate module 3 includes a large end face with a larger area and a small end face with a smaller area, the area of ​​the overlapping area formed by different end faces and the battery housing 1 is also different, wherein on the surface with a larger area, at least three second pre-welding points 100 are set, preferably five, and on the surface with a smaller area, at least three second pre-welding points 100 are set, preferably five, and on the surface with a smaller area, at least three second pre-welding points 100 are set. On the surface, at least one second pre-welding point 100 is set, preferably three. When there are multiple second pre-welding points 100, it is necessary to ensure that the multiple second pre-welding points 100 set at intervals are evenly distributed; and when the first cover plate module 3 and the second cover plate module 6 are finally welded to the battery shell 1, the first cover plate module 3 and the battery shell 1 can be finally welded first, and then the second cover plate module 6 and the battery shell 1 can be finally welded, or the first cover plate module 3 and the second cover plate module 6 can be simultaneously welded to the battery shell 1. The specific implementation method depends on the actual working environment.

[0100] Alternatively, as Figure 2 、 Figure 3 、 Figure 4 As shown, in step S2, the following steps are also included:

[0101] S21, the battery further includes at least one protective side plate 8, and the at least one protective side plate 8 is pre-heat-fused to a set position of the insulating film 7;

[0102] S22, covering the insulating film 7 on multiple side surfaces 24 of the electrode group 2, and making at least one protective side plate 8 cover one side surface 24 of the electrode group 2;

[0103] S23 , hot-melt the overlapping area between the insulating film 7 and the protective end plate 5 .

[0104] By hot-melting the protective side plate 8 on the insulating film 7 before coating the insulating film 7, the protective side plate 8 can cover one of the side surfaces 24 of the electrode group 2 when the insulating film 7 is coated on the electrode group 2. When the electrode group 2 is placed into the shell, the protective side plate 8 protects multiple side surfaces 24 of the electrode group 2 to avoid scratches when the electrode group 2 is placed into the shell.

[0105] The number of the protective side plates 8 can be freely set according to the protection requirements. In this embodiment, four protective side plates 8 are provided, corresponding one-to-one to the four side surfaces 24 of the electrode group 2, thereby improving the protection performance of the electrode group 2.

[0106] Alternatively, as Figure 2 、 Figure 3 、 Figure 4 As shown, in step S21, the following steps are also included:

[0107] S211, opening a positioning hole 71 at a set position of the insulating film 7;

[0108] S212, a positioning structure that cooperates with the positioning hole 71 is provided on the protective side plate 8, the protective side plate 8 is arranged at a set position of the insulating film 7, and the positioning structure is aligned with the positioning hole 71;

[0109] S213 , hot-melt the assembled protective side plate 8 and the insulating film 7 .

[0110] By opening a positioning hole 71 at a set position of the insulating film 7 and providing a positioning structure on the protective side plate 8 that cooperates with the positioning hole 71, the protective side plate 8 is ensured to have an accurate hot-melt position, thereby avoiding the protective side plate 8 being unable to provide effective protection when the insulating film 7 covers the electrode group 2 due to inaccurate position of the protective side plate 8 after hot-melt.

[0111] Alternatively, as Figure 2 、 Figure 3 、 Figure 5 、 Figure 6 As shown, in step S23, the following steps are also included:

[0112] S231, pre-installing the first cover plate module 3 and / or the second cover plate module 6 on the side of the protective end plate 5 facing away from the pole group 2;

[0113] S232, measuring the distance L1 between the closest points of the insulating film 7 and the first cover module 3, and / or the second cover module 6, and determining whether L1 satisfies 0.5 mm ≤ L1 ≤ 3 mm. If so, proceed to step S233; otherwise, proceed to step S234;

[0114] S233, after removing the pre-installed first cover plate module 3 and / or second cover plate module 6, heat-seal the overlapping area between the insulating film 7 and the protective end plate 5 to form a pole group unit;

[0115] S234 , after removing the pre-installed first cover module 3 and / or second cover module 6 , the insulating film 7 is trimmed. After the trimming is completed, step S231 is executed.

[0116] By pre-installing the first cover plate module 3 and / or the second cover plate module 6 on the side of the protective end plate 5 away from the electrode group 2, and determining whether the distance dimension L1 between the pre-installed first cover plate module 3 and / or the second cover plate module 6 and the insulating film 7 satisfies the range of 0.5mm≤L1≤3mm, on the one hand, it is avoided that the distance dimension L1 between the first cover plate module 3 and / or the second cover plate module 6 and the insulating film 7 is too small, affecting the welding of the first cover plate module 3 and / or the second cover plate module 6 and the battery casing 1, and easily causing problems such as welding explosion points; on the other hand, it is avoided that the distance dimension L1 between the first cover plate module 3 and / or the second cover plate module 6 and the insulating film 7 is too large, resulting in an increase in the height dimension of the protective end plate 5 and an increase in manufacturing costs.

[0117] In this embodiment, since protective end plates 5 are provided at the pole ears 21 on both sides of the pole group 2, it is necessary to pre-install the first cover plate module 3 and the second cover plate module 6 in order to determine whether the distance dimension L1 between the nearest point between each of the first cover plate module 3 and the second cover plate module 6 and the insulating film 7 meets the set range.

[0118] In other embodiments, if the protective end plate 5 is installed at only one side of the pole ear 21 of the pole group 2 , the first cover plate module 3 is preferably arranged on the side with the protective end plate 5 .

[0119] The distance dimension L1 after trimming can be any value between 0.5 mm and 3 mm or a range between any two values, such as 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc.

[0120] Alternatively, as Figure 2 、 Figure 3 、 Figure 5 、 Figure 6 As shown, a plurality of thermal melting points 72 are provided in the overlapping area between the insulating film 7 and the protective end plate 5 at intervals. The distance between the boundary of each thermal melting point 72 away from the pole group 2 and the boundary of the overlapping area away from the pole group 2 is L2, and satisfies 0.5mm≤L2≤3mm.

[0121] By adopting the method of setting multiple spaced hot melt points 72, hot melting between the insulating film 7 and the protective end plate 5 is achieved, thereby ensuring that the scope of hot melting is wide enough and the firmness of hot melting is guaranteed. On the other hand, compared with the full hot melting method, the hot melting area is small, thereby shortening the time required for hot melting operation and improving the efficiency of hot melting operation. At the same time, by setting the distance dimension between the boundary of each hot melting point 72 away from the pole group 2 and the boundary of the overlapping area away from the pole group 2 as L2, and limiting the distance dimension L2 between the boundary of each hot melting point 72 away from the pole group 2 and the boundary of the overlapping area away from the pole group 2 to meet 0.5mm≤L2≤3mm, it is ensured that the hot melting point 72 and the boundary of the overlapping area away from the pole group 2 maintain an appropriate distance. On the one hand, it is avoided that the distance is too small, resulting in insufficient area for operation during hot melting, and on the other hand, it is avoided that the distance is too large, resulting in loose connection of the area on the side of the hot melting point 72 away from the pole group 2.

[0122] Among them, the distance dimension L2 between the boundary of each thermal melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 can be any value between 0.5mm and 3mm or a range between any two values, such as 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, etc.

[0123] Alternatively, as Figure 2 、 Figure 3 、 Figure 5 、 Figure 6 As shown, the distance between the boundary of each thermal melting point 72 facing the electrode group 2 and the boundary of the overlapping area facing the electrode group 2 is L3, and satisfies 0.5 mm≤L3≤3 mm.

[0124] By adopting the method of setting multiple spaced hot melt points 72, hot melting between the insulating film 7 and the protective end plate 5 is achieved, thereby ensuring that the scope of hot melting is wide enough and the firmness of hot melting is ensured. On the other hand, compared with the full hot melting method, the hot melting operation time is short and the hot melting operation efficiency is high. At the same time, by setting the distance dimension between the boundary of each hot melting point 72 facing the pole group 2 side and the boundary of the overlapping area facing the pole group 2 side as L3, and limiting the distance dimension L3 between the boundary of each hot melting point 72 facing the pole group 2 side and the boundary of the overlapping area facing the pole group 2 side to satisfy 0.5mm≤L3≤3mm, it is ensured that the hot melting point 72 and the boundary of the overlapping area facing the pole group 2 side maintain an appropriate distance, on the one hand, avoiding too small a distance, resulting in insufficient area for operation during hot melting, and on the other hand, avoiding too large a distance, resulting in loose connection of the area on the side of the hot melting point 72 facing the pole group 2 side.

[0125] Among them, the distance dimension L3 between the boundary of each thermal melting point 72 facing the pole group 2 side and the boundary of the overlapping area facing the pole group 2 side can be any value between 0.5mm and 3mm or a range between any two values, such as 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, etc.

[0126] Alternatively, as Figure 2 、 Figure 3 、 Figure 10 、 Figure 11 、 Figure 12 As shown, the first cover module 3 includes a cover body 31 and a first insulating layer 32, a receiving groove 311 is opened on the cover body 31, and a plug-in through hole 312 is opened on the cover body 31 and is arranged in the receiving groove 311. The first insulating layer 32 is injection molded on the cover body 31 and includes an upper insulating portion 321, a lower insulating portion 322 and a plug-in portion 323. The upper insulating portion 321 is arranged on the side of the cover body 31 away from the pole group 2 and is located in the receiving groove 311. The lower insulating portion 322 is arranged on the side of the cover body 31 facing the pole group 2 and is located between the cover body 31 and the protective end plate 5. The plug-in portion 323 is inserted in the plug-in through hole 312 and is used to connect the upper insulating portion 321 and the lower insulating portion 322. The second through-hole structure 325 penetrates the upper insulating portion 321, the plug-in portion 323 and the lower insulating portion 322 and is connected to the first through-hole structure 51.

[0127] By injection molding the first insulating layer 32 on the cover body 31, the first insulating layer 32 cooperates with the protective end plate 5 to achieve double insulation protection, thereby improving the safety and protection of the structure. In addition, by providing the first insulating layer 32 consisting of an upper insulating portion 321, a lower insulating portion 322 and a plug-in portion 323, the upper insulating portion 321 is provided on the side of the cover body 31 away from the pole group 2, the lower insulating portion 322 is provided on the side of the cover body 31 facing the pole group 2, and the plug-in portion 323 is inserted into the cover body 31. The plug-in through hole 312 is inserted, and the second penetrating structure 325 penetrates the upper insulating part 321, the plug-in part 323 and the lower insulating part 322 to communicate with the first penetrating structure 51, so that the first insulating layer 32 is used to achieve insulation protection for both sides of the cover body 31 and the inside of the plug-in through hole 312, and isolate the pole ear 21 and the cover body 31 to avoid direct contact between the pole ear 21 and the cover body 31 when passing through the cover body 31, resulting in a short circuit, thereby ensuring safety and protection.

[0128] In this embodiment, in order to verify the influence of the distance dimension L1, the distance dimension L2, and the distance dimension L3 on the quality of the assembled product in this battery assembly method, six groups of embodiments and six groups of comparative examples are provided for verification, as shown in Table 1. Among them, for the distance dimension L1 between the first cover plate module 3 and the insulating film 7, the distance dimension L1 is essentially the distance between the boundary of the side of the insulating film 7 facing away from the electrode group 2 and the surface of the cover plate body 31 facing the electrode group 2; for the distance dimension L1 between the second cover plate module 6 and the insulating film 7, the distance dimension L1 is essentially the distance between the boundary of the side of the insulating film 7 facing away from the electrode group 2 and the surface of the bare aluminum plate 62 facing the electrode group 2. The distance dimension L1 discussed in this experiment is the distance dimension L1 between the first cover plate module 3 and the insulating film 7, that is, the distance between the boundary of the cover plate body 31 and the side of the insulating film 7 facing away from the electrode group 2.

[0129] Table 1

[0130]

[0131] In Example 1, the distance L1 between the first cover module 3 and the insulating film 7 is set to 0.5 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 0.5 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 0.5 mm. At this time, the battery is assembled according to the above data. It is verified that no explosion points appear in the welds around the shell cover. After disassembling the battery, the insulating film 7 is not damaged and has not fallen off.

[0132] In Example 2, the distance L1 between the first cover module 3 and the insulating film 7 is set to 1 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 2 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 2 mm. At this time, the battery is assembled according to the above data. It is verified that no explosion points appear in the welds around the shell cover. After disassembling the battery, the insulating film 7 is not damaged and has not fallen off.

[0133] In Example 3, the distance L1 between the first cover module 3 and the insulating film 7 is set to 1.5 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 1 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 3 mm. At this time, the battery is assembled according to the above data. It is verified that no explosion points appear in the welds around the shell cover. After disassembling the battery, the insulating film 7 is not damaged and has not fallen off.

[0134] In Example 4, the distance L1 between the first cover module 3 and the insulating film 7 is set to 2 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 3 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 1 mm. At this time, the battery is assembled according to the above data. It is verified that no explosion points appear in the welds around the shell cover. After disassembling the battery, the insulating film 7 is not damaged and has not fallen off.

[0135] In Example 5, the distance L1 between the first cover module 3 and the insulating film 7 is set to 2.5 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 1.5 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 2.5 mm. At this time, the battery is assembled according to the above data. It is verified that no explosion points appear in the welds around the shell cover. After disassembling the battery, the insulating film 7 is not damaged and has not fallen off.

[0136] In Example 6, the distance L1 between the first cover module 3 and the insulating film 7 is set to 3 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 2.5 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 1.5 mm. At this time, the battery is assembled according to the above data. It is verified that no explosion points appear in the welds around the shell cover. After disassembling the battery, the insulating film 7 is not damaged and has not fallen off.

[0137] It can be seen from Examples 1 to 6 that when the distance dimension L1 between the first cover plate module 3 and the insulating film 7 satisfies the range of 0.5mm≤L1≤3mm, the distance dimension L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 satisfies the range of 0.5mm≤L2≤3mm, and the distance dimension L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 satisfies the range of 0.5mm≤L3≤3mm, the battery assembled by this battery assembly method has no explosion points in the weld around the shell cover, and after disassembling the battery, the insulating film 7 is not damaged or falls off, and has high product quality.

[0138] In Comparative Example 1, the distance L1 between the first cover module 3 and the insulating film 7 is set to 0.1 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 1 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 1 mm. At this time, the battery is assembled according to the above data. It is verified that explosion points appear during welding around the shell cover and the insulating film 7 melts.

[0139] It can be seen from Comparative Example 1 that when the distance dimension L1 between the first cover module 3 and the insulating film 7 is less than the minimum value of 0.5mm≤L1≤3mm, the insulating film 7 is close to the cover body 31, so an explosion point appears when welding the periphery of the shell cover. Moreover, since the insulating film 7 is too close to the welding position, the high temperature generated by the welding causes the insulating film 7 to melt, resulting in poor insulation protection performance of the assembled battery.

[0140] In Comparative Example 2, the distance L1 between the first cover module 3 and the insulating film 7 is set to 1 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 0.1 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 1 mm. At this time, the battery after assembly is completed according to the above data, and it is verified that the insulating film 7 has fallen off.

[0141] It can be seen from Comparative Example 2 that when the distance L2 between the boundary of the hot melting point 72 away from the side of the electrode group 2 and the boundary of the overlapping area away from the side of the electrode group 2 is less than the minimum value of 0.5mm≤L2≤3mm, the hot melting point 72 is close to the upper edge of the overlapping area of ​​the protective end plate 5, resulting in part of the hot melting point exceeding the upper edge of the insulating film 7, resulting in insufficient hot melting area between the insulating film 7 and the protective end plate 5, which causes the insulating film 7 to fall off, resulting in poor insulation protection performance of the assembled battery.

[0142] In comparative example 3, the distance L1 between the first cover plate module 3 and the insulating film 7 is set to 1 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 1 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 0.1 mm. At this time, the battery after assembly is completed according to the above data, it is verified that melting through occurs between the insulating film 7 and the protective end plate 5, resulting in a short circuit.

[0143] It can be seen from Comparative Example 3 that when the distance dimension L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is less than the minimum value of 0.5mm≤L3≤3mm, the hot melting point 72 is close to the lower edge of the overlapping area of ​​the protective end plate 5, resulting in a portion of the hot melting point 72 exceeding the lower edge of the protective end plate 5, causing melting through between the insulating film 7 and the protective end plate 5, thereby causing a short circuit problem, resulting in poor insulation protection performance of the assembled battery.

[0144] In Comparative Example 4, the distance L1 between the first cover plate module 3 and the insulating film 7 is set to 4 mm, the distance L2 between the boundary of the thermal melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 1 mm, and the distance L3 between the boundary of the thermal melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 1 mm. At this time, the battery is assembled according to the above data. It is found that the protective end plate 5 occupies a large internal space, resulting in the compression of the volume of the electrode group 2, thereby resulting in a lower energy density of the assembled battery.

[0145] It can be seen from Comparative Example 4 that when the distance dimension L1 between the first cover module 3 and the insulating film 7 is greater than the maximum value of 0.5mm≤L1≤3mm, the insulating film 7 is far away from the cover body 31, so the protective end plate 5 occupies a large internal space. Therefore, in order to complete the assembly, the volume of the electrode group 2 needs to be reduced, thereby reducing the energy density of the assembled battery, the power supply capacity is poor, and it does not meet the use requirements.

[0146] In comparative example 5, the distance L1 between the first cover plate module 3 and the insulating film 7 is set to 1 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 4 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 1 mm. At this time, the battery is assembled according to the above data. It is found that the insulating film 7 is located in the area between the hot melting point 72 and the upper edge of the overlapping area of ​​the protective end plate 5, and is not tightly connected to the protective end plate 5, resulting in flanging of the insulating film 7.

[0147] It can be seen from Comparative Example 5 that when the distance dimension L2 between the boundary of the hot melting point 72 away from the side of the pole group 2 and the boundary of the overlapping area away from the side of the pole group 2 is greater than the maximum value of 0.5mm≤L2≤3mm, the hot melting point 72 is far away from the upper edge of the overlapping area of ​​the protective end plate 5, resulting in the insulating film 7 being located in the area between the hot melting point 72 and the upper edge of the overlapping area of ​​the protective end plate 5, and is not tightly connected to the protective end plate 5, resulting in the insulating film 7 being flanging, which does not meet the use requirements.

[0148] In comparative example 6, the distance L1 between the first cover plate module 3 and the insulating film 7 is set to 1 mm, the distance L2 between the boundary of the hot melting point 72 away from the electrode group 2 and the boundary of the overlapping area away from the electrode group 2 is set to 1 mm, and the distance L3 between the boundary of the hot melting point 72 toward the electrode group 2 and the boundary of the overlapping area toward the electrode group 2 is set to 4 mm. At this time, the battery is assembled according to the above data. It is found that the insulating film 7 is located in the area between the hot melting point 72 and the lower edge of the overlapping area of ​​the protective end plate 5, and is not tightly connected to the protective end plate 5. There is a gap between the insulating film 7 and the electrode group 2.

[0149] It can be seen from Comparative Example 6 that when the distance dimension L3 between the boundary of the hot melting point 72 toward the pole group 2 and the boundary of the overlapping area toward the pole group 2 is greater than the maximum value of 0.5mm≤L3≤3mm, the hot melting point 72 is far away from the lower edge of the overlapping area of ​​the protective end plate 5, resulting in the insulating film 7 being located in the area between the hot melting point 72 and the lower edge of the overlapping area of ​​the protective end plate 5, and is not tightly connected to the protective end plate 5, thereby weakening the strength of the insulating film 7 to wrap around the pole group 2, resulting in easy generation of gaps between the insulating film 7 and the pole group 2, which does not meet the use requirements.

[0150] Alternatively, as Figure 2 、 Figure 3 、 Figure 10 、 Figure 11 、 Figure 12 As shown, in step S7, the following steps are also included:

[0151] S71. A mounting groove 324 is formed on the side of the upper insulating portion 321 facing away from the cover body 31. The battery further includes a connecting piece 9. The connecting piece 9 is installed in the mounting groove 324.

[0152] S72, bending the electrode tab 21 extending out of the second penetrating structure 325, and welding the bent electrode tab 21 to the connecting piece 9;

[0153] S73: The battery further includes a sealing ring 10, which is installed in the receiving groove 311;

[0154] S74, inserting the composite pole 4 into the receiving groove 311, with the sealing ring 10 sandwiched between the composite pole 4 and the first cover plate module 3;

[0155] S75 , welding the composite pole 4 and the first cover plate module 3 .

[0156] By providing a connecting piece 9 and welding the pole tab 21 to the connecting piece 9, the position of the pole tab 21 can be fixed in advance by using the connecting piece 9, thereby ensuring the accuracy of the position of the pole tab 21 during subsequent operations and avoiding the displacement of the pole tab 21, which affects the conduction effect of the current between the pole tab 21 and the composite pole 4.

[0157] Alternatively, as Figure 3 As shown, in step S8, the following steps are also included:

[0158] S81. A connecting boss 91 is provided on the side of the connecting piece 9 facing the composite pole 4 and is raised along the side close to the composite pole 4. The composite pole 4 is pre-welded and positioned on the connecting boss 91 by a plurality of third pre-welding points arranged at intervals.

[0159] S82 , fully weld the composite pole 4 and the connecting boss 91 .

[0160] A connecting boss 91 is provided on the side of the connecting piece 9 facing the composite pole 4 to facilitate welding of the connecting piece 9 to the composite pole 4. The size and shape of the connecting boss 91 can be freely adjusted as needed, as long as sufficient welding area is ensured between the connecting boss 91 and the composite pole 4. In this embodiment, the connecting boss 91 is a frustum.

[0161] In addition, the composite pole 4 is first pre-welded to the connecting boss 91 through a plurality of third pre-welding points arranged at intervals, so as to ensure that the relative position between the composite pole 4 and the connecting boss 91 is preliminarily positioned before full welding, thereby ensuring the accuracy of the position of the two after welding during full welding, ensuring the welding quality, and even if the initial positioning is incorrect, it is convenient to separate and reposition the two, realize recycling, and reduce the scrap rate of the product.

[0162] Alternatively, as Figure 2 、 Figure 3 、 Figure 10 、 Figure 11 、 Figure 12 As shown, in step S75, the following steps are also included:

[0163] S751, the composite pole 4 includes a pole body 41, a welding ring 42, and a second insulating layer 43 for achieving an insulated connection between the pole body 41 and the welding ring 42, the welding ring 42 being pre-welded and positioned in the receiving groove 311 through a plurality of fourth pre-welding points arranged at intervals;

[0164] S752 , fully weld the welding ring 42 into the receiving groove 311 .

[0165] The welding ring 42 is first pre-welded in the receiving groove 311 through a plurality of fourth pre-welding points arranged at intervals, thereby ensuring that the relative position of the welding ring 42 in the receiving groove 311 is positioned before full welding. Even if the initial positioning is incorrect, it is convenient to separate and reposition the two, achieving recycling and reducing the scrap rate of the product. The number, size and shape of the fourth pre-welding points used to pre-weld the welding ring 42 can be freely set according to actual needs. In addition, the second insulating layer 43 is formed by injection molding to insulate the pole body 41 and the welding ring 42, thereby forming the pole body 41, the second insulating layer 43 and the welding ring 42 into a whole. Compared with the second cover plate module 6 using the traditional riveted cover plate, the separate upper insulating member and the riveted block are eliminated, thereby reducing the number of parts and simplifying the assembly process.

[0166] Alternatively, as Figure 3 As shown, a shaping structure 52 corresponding to the pole lug 21 is provided on the side of the protective end plate 5 facing the pole group 2. The shaping structure 52 is a trumpet-shaped structure whose opening gradually shrinks in the direction away from the pole group 2. Thus, in step S1, the multiple converged pole lugs 21 on the pole group 2 are better supported and fixed, the convergence state of the pole lugs 21 is improved, and the problem of short circuit inside the battery due to poor convergence effect of the pole lugs 21 is avoided.

[0167] In this embodiment, a battery is further provided, which is assembled using the above-mentioned battery assembly method. By applying the above-mentioned battery assembly method, the volume of the electrode group 2 is further increased, thereby improving the energy density of the battery and increasing the power supply capacity of the battery.

[0168] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. A person skilled in the art would be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A battery assembly method, characterized in that: The battery assembled by the battery assembly method includes a battery shell, an electrode group, a first cover plate module, a composite electrode, a protective end plate and a second cover plate module; The battery assembly method comprises the following steps: S1. The electrode group includes a first surface and a second surface with electrode tabs, and multiple side surfaces perpendicular to the first and second surfaces. The protective end plate is provided with a first through-structure. The protective end plate is installed on the first surface and / or the second surface of the electrode group, and the electrode tabs pass through the first through-structure. S2, covering the outer side of the electrode group with an insulating film so that the insulating film covers the outer sides of the plurality of side surfaces, and hot-melting the insulating film and the protective end plate to form an electrode group unit; S3. The second cover plate module includes an independent pole. The second cover plate module is installed on either side of the pole group where the pole lug is provided, and the pole lug on that side passes through the first penetrating structure and is welded to the independent pole. S4, the battery housing is a double-sided open structure with a cavity, the electrode group unit equipped with the second cover plate module is installed in the cavity of the battery housing, the second cover plate module closes the opening on one side of the battery housing, and the second cover plate module is pre-welded to the battery housing at a plurality of first pre-welding points arranged at intervals; S5, the first cover plate module includes a second through-hole structure for the tab to extend and a first insulating layer for isolating the first cover plate module from the tab, the first cover plate module is assembled into the opening on the other side of the battery housing, the tab passing through the first through-hole structure passes through the second through-hole structure, and the first cover plate module and the battery housing are pre-welded at a plurality of second pre-welding points (100) arranged at intervals; S6, final welding the battery housing to the first cover plate module and the second cover plate module; S7. A receiving groove is further provided on a side of the first cover plate module facing away from the electrode group. The composite electrode is installed in the receiving groove and welded to the first cover plate module. S8, achieving current conduction between the composite pole and the tab; In step S2, the following steps are also included: S21, the battery further includes at least one protective side plate, and at least one protective side plate is pre-heat-fused to a set position of the insulating film; S22, covering the plurality of side surfaces of the electrode group with the insulating film, and making at least one of the protective side plates cover one of the side surfaces of the electrode group; S23, hot-melting the overlapping area between the insulating film and the protective end plate; In step S23, the following steps are also included: S231, pre-installing the first cover plate module and / or the second cover plate module on a side of the protective end plate facing away from the electrode group; S232, measuring the distance L1 between the closest points of the insulating film and the first cover module, and / or the second cover module, and determining whether L1 satisfies 0.5 mm ≤ L1 ≤ 3 mm. If so, proceed to step S233; otherwise, proceed to step S234; S233: After removing the pre-installed first cover plate module and / or the second cover plate module, heat-seal the overlapping area between the insulating film and the protective end plate to form the electrode group unit; S234 , after removing the pre-installed first cover module and / or the second cover module, cutting the insulating film. After the cutting is completed, execute step S231 .

2. The battery assembly method according to claim 1, characterized in that: In step S21, the following steps are also included: S211, opening a positioning hole at a set position of the insulating film; S212, a positioning structure cooperating with the positioning hole is provided on the protective side plate, the protective side plate is provided at a set position of the insulating film, and the positioning structure is aligned with the positioning hole; S213, hot-melt the assembled protective side plate and the insulating film.

3. The battery assembly method according to claim 1, wherein: A plurality of thermal melting points are provided in the overlapping region between the insulating film and the protective end plate, and a distance L2 is provided between a boundary of each thermal melting point facing away from the electrode group and a boundary of the overlapping region facing away from the electrode group, and the distance L2 satisfies 0.5 mm ≤ L2 ≤ 3 mm; And / or, the distance between the boundary of each of the thermal melting points facing the electrode group and the boundary of the overlapping area facing the electrode group is L3, and satisfies 0.5mm≤L3≤3mm.

4. The battery assembly method according to claim 1, wherein: The first cover plate module includes a cover plate body and the first insulating layer; The receiving groove is provided on the cover body, and the cover body is further provided with a plug-in through hole provided in the receiving groove; The first insulating layer is injection molded on the cover body and includes an upper insulating portion, a lower insulating portion and a plug-in portion. The upper insulating portion is provided on the side of the cover body away from the pole group and is located in the accommodating groove. The lower insulating portion is provided on the side of the cover body facing the pole group and is located between the cover body and the protective end plate. The plug-in portion is inserted in the plug-in through hole and is used to connect the upper insulating portion and the lower insulating portion. The second penetrating structure penetrates the upper insulating portion, the plug-in portion and the lower insulating portion and is connected to the first penetrating structure.

5. The battery assembly method according to claim 4, characterized in that: In step S7, the following steps are also included: S71. A mounting groove is formed on a side of the upper insulating portion facing away from the cover body, and the battery further includes a connecting piece, and the connecting piece is installed in the mounting groove; S72, bending the portion of the electrode tab extending out of the second penetrating structure, and welding the bent electrode tab to the connecting piece; S73, the battery further includes a sealing ring, and the sealing ring is installed in the receiving groove; S74, placing the composite pole into the receiving groove, with the sealing ring being sandwiched between the composite pole and the first cover plate module; S75: Welding the composite pole and the first cover plate module.

6. The battery assembly method according to claim 5, characterized in that: In step S8, the following steps are also included: S81. A connecting boss is provided on a side of the connecting piece facing the composite pole, and is protruding along the composite pole. The composite pole is pre-welded and positioned on the connecting boss by a plurality of third pre-welding points arranged at intervals. S82, fully welding the composite pole and the connecting boss.

7. The battery assembly method according to claim 5, characterized in that: In step S75, the following steps are also included: S751. The composite pole includes a pole body, a welding ring, and a second insulating layer for achieving an insulated connection between the pole body and the welding ring, wherein the welding ring is pre-welded and positioned in the receiving groove through a plurality of fourth pre-welding points arranged at intervals. S752, fully weld the welding ring in the receiving groove.

8. A battery, characterized in that The battery is assembled using the battery assembly method according to any one of claims 1 to 7.

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