Battery assembly method and battery

Abstract

The invention belongs to the technical field of batteries, and discloses a battery assembly method and a battery, and the method comprises the following steps: S1, installing a protection end plate on any side, provided with a tab, of a pole group; s2, coating the outer side of the pole group with an insulating film which is in hot melting with the protective end plate; s3, installing a cover plate module on any side of the pole group; s4, loading the pole group unit with the cover plate module into the composite shell; s5, the cover plate module and the composite shell are welded; s6, welding the composite pole and the composite shell; and S7, realizing current conduction between the composite pole and the tab. The current conduction between the composite pole and the tabs is finally realized, so that the tabs on the side extend out of the composite shell while the influence of other welding procedures on the connection quality of the tabs and the composite pole is avoided, the occupied space is reduced, the space utilization rate is improved, the welding workload of the tabs on one side is reduced, and the production efficiency is improved. The influence of high temperature on the microstructure of the tab on the side is reduced, and the discharge performance and the cycle life are improved.

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 a 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, weld the plain aluminum plate to the battery shell, and then install the upper plastic, seal and welding table in sequence on the outer side of the plain aluminum plate corresponding to the part of the pole extending out, and complete the welding of the welding table and the plain aluminum plate, as well as the welding of the welding table and 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 ear and the pole first, and then complete the welding of the bare aluminum plate and the battery shell, the welding of the welding platform and the bare aluminum plate, and the welding of the welding platform and the pole. As a result, the pole ear and the pole 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 welding platform and the bare aluminum plate, and the welding of the welding platform and the pole, thereby reducing the welding quality between the pole and the pole ear and reducing the product yield. On the other hand, since this method also requires that the pole and the pole ear be connected inside the battery shell, This causes the pole lug and pole post to occupy a larger space inside the battery casing, limiting the volume of the pole group and resulting in a low energy density. In addition, since one side of the pole lug involves welding of the bare aluminum plate to the battery casing, welding of the welding platform to the bare aluminum plate, welding of the welding platform to the pole post, and welding of the pole lug to the pole post, a large number of welding operations are concentrated on the pole lug side, causing the microstructure of the pole lug material to undergo adverse changes due to the high temperature generated by a large number of welding operations, thereby affecting the electrical and mechanical properties of the pole lug itself, increasing the resistance of the pole lug, and reducing the discharge performance and cycle life of the blade battery. Summary of the invention

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

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

[0006] On the one hand, a battery assembly method is provided, wherein the battery assembled by the battery assembly method comprises a composite housing, an electrode group, a cover plate module, a composite electrode column and a protective end plate;

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

[0008] S1, the electrode group includes a first surface and a second surface with electrode ears, and a plurality of side surfaces perpendicular to the first surface and the second surface, the protective end plate is provided with a first penetration structure, the protective end plate is installed on the first surface and / or the second surface of the electrode group, and the electrode ears pass through the first penetration structure;

[0009] S2, coating the outer side of the electrode group with an insulating film, so that the insulating film is coated on 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 cover plate module includes an independent pole, and the cover plate module is installed on any one side of the two sides of the pole group provided with the pole lug, and the pole lug on this side passes through the first penetration structure and is welded to the independent pole;

[0011] S4, the composite shell is a single-side open structure with a cavity, a second through-structure for the pole ear to extend is provided on the wall surface opposite to the open side, and a first insulating layer for isolating the composite shell from the pole ear is injection-molded on the wall surface, the pole group unit equipped with the cover plate module is installed in the cavity of the composite shell, and the pole ear on the other side of the pole group that passes through the first through-structure passes through the second through-structure, and the cover plate module closes the opening of the composite shell;

[0012] S5, welding the cover plate module to the composite shell;

[0013] S6, a receiving groove is provided on a side of the composite shell away from the electrode group, the composite pole is placed in the receiving groove, and the composite pole is welded to the composite shell;

[0014] S7, achieving current conduction between the composite pole and the pole lug.

[0015] Optionally, in step S2, the following steps are also included:

[0016] 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;

[0017] 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;

[0018] S23, hot-melt the overlapping area between the insulating film and the protective end plate.

[0019] Optionally, in step S21, the following steps are also included:

[0020] S211, opening a positioning hole at a set position of the insulating film;

[0021] S212, a positioning structure cooperating with the positioning hole is provided on the protective side plate, the protective side plate is arranged at a set position of the insulating film, and the positioning structure is aligned with the positioning hole;

[0022] S213, hot-melt the assembled protective side plate and the insulating film.

[0023] Optionally, in step S23, the following steps are also included:

[0024] S231, pre-installing the cover plate module on a side of the protective end plate away from the pole group;

[0025] S232, measuring the distance L1 between the closest points of the cover module and the insulating film, and determining whether L1 satisfies 0.5 mm ≤ L1 ≤ 3 mm, if yes, executing step S233, if not, executing step S234;

[0026] S233, after removing the pre-installed cover plate module, hot-melt the overlapping area between the insulating film and the protective end plate to form the pole group unit;

[0027] S234, after removing the pre-installed cover module, cutting the insulating film, after the cutting is completed, executing step S231.

[0028] Optionally, a plurality of thermal melting points are arranged at intervals in the overlapping region between the insulating film and the protective end plate, and the distance between the boundary of each thermal melting point away from the electrode group and the boundary of the overlapping region away from the electrode group is L2, and satisfies 0.5mm≤L2≤3mm;

[0029] 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.

[0030] Optionally, in step S5, the following steps are also included:

[0031] S51, the cover plate module and the composite shell are pre-welded and positioned at a plurality of first pre-welding points arranged at intervals;

[0032] S52, fully welding the cover plate module and the composite shell.

[0033] Optionally, the composite housing comprises a housing body and the first insulating layer;

[0034] The shell body includes a first wall surface and a plurality of second wall surfaces perpendicular to the first wall surface, wherein the plurality of second wall surfaces are arranged around the first wall surface to form a hollow shell structure with a single-side opening, and the receiving groove is provided on a side of the first wall surface away from the pole group, and the first wall surface is also provided with a plug-in through hole arranged in the receiving groove;

[0035] The first insulating layer is injection molded on the first wall, and includes an upper insulating portion, a lower insulating portion and a plug-in portion. The upper insulating portion is arranged on the side of the first wall facing away from the pole group and is located in the accommodating groove. The lower insulating portion is arranged on the side of the first wall facing the pole group. 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.

[0036] Optionally, in step S6, the following steps are also included:

[0037] S61, a mounting groove is further provided on a side of the upper insulating portion away from the housing body, and the battery further comprises a connecting piece, and the connecting piece is installed in the mounting groove;

[0038] S62, bending the portion of the electrode tab extending out of the second penetrating structure, and welding the bent electrode tab to the connecting sheet;

[0039] S63, the battery further includes a sealing ring, and the sealing ring is installed in the receiving groove;

[0040] S64, placing the composite pole into the receiving slot;

[0041] S65, welding the composite pole and the composite shell.

[0042] Optionally, in step S7, the following steps are also included:

[0043] S71, a connection boss protruding along the side of the connection piece facing the composite pole is provided, and the composite pole is pre-welded and positioned on the connection boss through a plurality of second pre-welding points arranged at intervals;

[0044] S72, fully welding the composite pole and the connecting boss.

[0045] On the other hand, a battery is provided, wherein the battery is assembled using any of the battery assembly methods described above.

[0046] Beneficial effects of the present invention:

[0047] The present invention provides a battery assembly method, which saves space for connecting the pole ear on one side with the composite pole and extending the composite pole into the composite shell by assembling the pole assembly into a composite shell provided with a second penetration structure and a first insulating layer, and making the pole ear on one side of the pole assembly extend out of the composite shell through the second penetration structure, and realize current conduction with the composite pole located outside the composite shell, thereby reducing the occupation of the internal space and improving the utilization rate of the space on the one hand, and providing space for increasing the pole assembly and improving the energy density on the other hand, and the battery assembly method is arranged after the welding of the composite pole and the composite shell when realizing current conduction between the pole ear on the side and the composite pole, thereby effectively avoiding the influence of other welding processes on the connection quality between the pole ear and the composite pole that have realized current conduction, thereby having a higher product yield, and a protective end plate with a first penetration structure is arranged on the first surface of the pole ear and / or the second surface of the pole assembly, so as to support the pole ear, avoid the pole ear from being skewed, and ensure the reliability of the structure. In addition, by adopting a single-side open composite shell with a single cover module structure, the side of the pole ear extending through the second through-structure of the composite shell has less welding work, thereby reducing the impact of the high temperature generated by the welding operation on the microstructure of the pole ear on this side, reducing the resistance of the pole ear on this side, and improving the discharge performance and cycle life of the overall battery.

[0048] 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

[0049] Figure 1 is a flow chart of a battery assembly method provided by the present invention;

[0050] Figure 2 is a structural exploded view of the battery provided by the present invention;

[0051] Figure 3 It is a structural cross-sectional view of the first wall side of the composite shell of the battery provided by the present invention;

[0052] Figure 4 It is a schematic diagram of the structure of hot melting of the insulating film and the protective side plate in the battery provided by the present invention;

[0053] Figure 5 It is a schematic diagram of the distribution of hot melting points of the protective end plate and the insulating film on the cover plate module side of the battery provided by the present invention;

[0054] Figure 6 It is a schematic diagram of the distribution of pre-welding points between the cover plate module and the composite shell in the battery provided by the present invention;

[0055] Figure 7 It is an assembly diagram of a cover plate module in a battery provided by the present invention;

[0056] Figure 8 is a structural cross-sectional view of a cover plate module in a battery provided by the present invention;

[0057] Fig. 9 It is a schematic diagram of the structure of the outer shell body of the battery provided by the present invention;

[0058] Fig.10 It is a schematic structural diagram of the first insulating layer in the battery provided by the present invention;

[0059] Fig.11 It is a structural schematic diagram of a protective end plate in a battery provided by the present invention.

[0060] In the figure:

[0061] 100, first pre-welding point;

[0062] 1. Composite housing; 11. Housing body; 111. First wall surface; 112. Second wall surface; 113. Accommodating groove; 114. Insertion through hole; 12. First insulating layer; 121. Upper insulating portion; 122. Lower insulating portion; 123. Insertion portion; 124. Second penetration structure; 125. Mounting groove;

[0063] 2. pole group; 21. pole ear; 22. first surface; 23. second surface; 24. side surface;

[0064] 3. Cover plate module; 31. Independent pole; 32. First plastic part; 33. Light aluminum plate; 34. Second plastic part; 35. Sealing part; 36. Welding station;

[0065] 4. Composite pole; 41. Pole body; 42. Welding ring; 43. Second insulating layer;

[0066] 5. Protective end plate; 51. First penetration structure; 52. Shaping structure;

[0067] 6. Insulating film; 61. Positioning hole; 62. Thermal melting point;

[0068] 7. Protective side panels;

[0069] 8. Connecting piece; 81. Connecting boss;

[0070] 9. Sealing ring. DETAILED DESCRIPTION

[0071] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0072] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0073] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0074] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0075] In order to avoid the connection between the pole and the lug in advance, which may affect the connection quality between the pole and the lug in other subsequent processes, reduce the impact of high temperature generated by a large number of welding operations on the microstructure of the lug, and reduce additional space occupation, improve space utilization and energy density, this embodiment provides a battery assembly method, and the battery assembled by the battery assembly method includes a composite shell 1, a pole group 2, a cover plate module 3, a composite pole 4 and a protective end plate 5.

[0076] like Figures 1 to 11 As shown, the battery assembly method includes the following steps:

[0077] S1, the pole group 2 includes a first surface 22 and a second surface 23 provided with pole ears 21, and a plurality of side surfaces 24 perpendicular to the first surface 22 and the second surface 23, a first penetration structure 51 is provided on the protective end plate 5, the protective end plate 5 is installed on the first surface 22 and / or the second surface 23 of the pole group 2, and the pole ears 21 pass through the first penetration structure 51;

[0078] S2, coating the outer side of the electrode group 2 with an insulating film 6, so that the insulating film 6 is coated on the outer sides of multiple side surfaces 24, and hot-melting the insulating film 6 and the protective end plate 5 to form an electrode group unit;

[0079] S3, the cover plate module 3 includes an independent pole 31, and the cover plate module 3 is installed on any one side of the two sides of the pole lug 21 of the pole group 2, and the pole lug 21 on this side passes through the first penetration structure 51 and is welded to the independent pole 31;

[0080] S4, the composite housing 1 is a single-side open structure with a cavity, a second through-structure 124 for the pole ear 21 to extend is provided on the wall surface opposite to the open side, and a first insulating layer 12 for isolating the composite housing 1 from the pole ear 21 is injection-molded on the wall surface, the pole group unit equipped with the cover module 3 is installed in the cavity of the composite housing 1, and the pole ear 21 on the other side of the pole group 2 that passes through the first through-structure 51 passes through the second through-structure 124, and the cover module 3 closes the opening of the composite housing 1;

[0081] S5, welding the cover plate module 3 to the composite shell 1;

[0082] S6. A receiving groove 113 is provided on the side of the composite housing 1 away from the pole group 2. The composite pole 4 is placed in the receiving groove 113, and the composite pole 4 and the composite housing 1 are welded.

[0083] S7, achieving current conduction between the composite pole 4 and the pole ear 21.

[0084] The battery assembly method installs the electrode group 2 into the composite shell 1 provided with the second penetration structure 124 and the first insulating layer 12, and makes the electrode ear 21 on one side of the electrode group 2 extend out of the composite shell 1 through the second penetration structure 124, and realizes current conduction with the composite pole 4 located outside the composite shell 1, thereby eliminating the space occupied by the electrode ear 21 on one side connecting with the composite pole 4 and the composite pole 4 extending into the composite shell 1. Therefore, on the one hand, the occupation of the internal space is reduced and the utilization rate of the space is improved. On the other hand, space is provided for increasing the electrode group 2, thereby improving the energy density and Moreover, when the current conduction is realized between the pole ear 21 and the composite pole 4 on the side, the battery assembly method is in the order after the composite pole 4 is welded to the composite shell 1, thereby effectively avoiding the influence of other welding processes on the connection quality between the pole ear 21 and the composite pole 4 that have realized the current conduction, thereby having a higher product yield, and the pole group 2 is provided with a first surface 22 of the pole ear 21, and / or a second surface 23 is provided with a protective end plate 5 with a first penetration structure 51, so as to gather and support the pole ear 21, avoid the pole ear 21 from being skewed, and ensure the reliability of the structure. In addition, by adopting a single-side open composite shell 1 with a single cover plate module 3 structure, the pole ear 21 side of the pole group 2 extending through the second penetration structure 124 of the composite shell 1 has less welding work, thereby reducing the influence of the high temperature generated by the welding operation on the microstructure of the pole ear 21 on this side, reducing the resistance of the pole ear 21 on this side, and improving the discharge performance and cycle life of the overall battery.

[0085] In this embodiment, both the first surface 22 and the second surface 23 of the pole group 2 are equipped with protective end plates 5 .

[0086] In this embodiment, the cover plate module 3 is a traditional welding cover plate, which includes, in addition to the independent pole 31, a first plastic part 32, a plain aluminum plate 33, a second plastic part 34, a seal 35 and a welding platform 36. Before assembling the battery, the cover plate module 3, that is, the welding cover plate, can be assembled in advance. After the assembly is completed, the pole ear 21 is directly welded to the independent pole 31 in the assembled cover plate module 3.

[0087] like Figure 7 , Figure 8 As shown, the specific steps include:

[0088] Ⅰ. The second plastic part 34 is bonded to the side of the bare aluminum plate 33 away from the electrode group 2 by using structural adhesive;

[0089] II. The first plastic part 32 is bonded to the side of the bare aluminum plate 33 facing the electrode group 2 using a structural adhesive;

[0090] III. A positioning groove is provided on the side of the second plastic part 34 facing away from the light aluminum plate 33, and the welding platform 36 is installed in the positioning groove;

[0091] IV. The independent pole 31 includes a column part and a limiting part, and the sealing member 35 is sleeved on the column part of the independent pole 31;

[0092] V. Install the independent pole 31, and make the column part of the independent pole 31 pass through the first plastic part 32, the aluminum plate 33 and the second plastic part 34 in sequence, and finally insert it into the welding platform 36. At this time, the first plastic part 32 is clamped between the limit part of the independent pole 31 and the aluminum plate 33;

[0093] VI. Weld the column body of the independent pole 31 to the welding platform 36 to complete the assembly of the cover plate module 3.

[0094] The type of the cover plate module 3 is not limited to the traditional welded cover plate. In other embodiments, the cover plate module 3 can also be a traditional riveted cover plate or a traditional minimalist cover plate.

[0095] Alternatively, if Figure 2 , Figure 3 , Figure 4 As shown, in step S2, the following steps are also included:

[0096] S21, the battery further includes at least one protective side plate 7, and the at least one protective side plate 7 is pre-heat-fused to a set position of the insulating film 6;

[0097] S22, covering the insulating film 6 on multiple side surfaces 24 of the electrode group 2, and making at least one protective side plate 7 cover one of the side surfaces 24 of the electrode group 2;

[0098] S23, hot-melt the overlapping area between the insulating film 6 and the protective end plate 5.

[0099] By hot-melting the protective side plate 7 on the insulating film 6 before coating the insulating film 6, when the insulating film 6 is coated on the electrode group 2, the protective side plate 7 can cover one of the side surfaces 24 of the electrode group 2, so that when the electrode group 2 is put into the shell, the side surface 24 of the electrode group 2 is protected by the protective side plate 7 to avoid scratches when the electrode group 2 is put into the shell.

[0100] The number of the protective side plates 7 can be freely set according to the protection requirements. In the present embodiment, four protective side plates 7 are provided, corresponding to the four side surfaces 24 of the electrode group 2 one by one, so as to improve the protection performance of the electrode group 2.

[0101] Alternatively, if Figure 2 , Figure 3 , Figure 4 As shown, in step S21, the following steps are also included:

[0102] S211, opening a positioning hole 61 at a set position of the insulating film 6;

[0103] S212, a positioning structure cooperating with the positioning hole 61 is provided on the protective side plate 7, the protective side plate 7 is arranged at a set position of the insulating film 6, and the positioning structure is aligned with the positioning hole 61;

[0104] S213, hot-melt the assembled protective side plate 7 and the insulating film 6.

[0105] By opening a positioning hole 61 at a set position of the insulating film 6 and providing a positioning structure that cooperates with the positioning hole 61 on the protective side plate 7, the accuracy of the hot-melt position of the protective side plate 7 can be ensured, thereby avoiding the inaccurate position of the protective side plate 7 after hot-melting, which makes it impossible to provide effective protection when the insulating film 6 covers the pole group 2.

[0106] Alternatively, if Figure 2 , Figure 3 , Figure 5 As shown, in step S23, the following steps are also included:

[0107] S231, pre-installing the cover plate module 3 on the side of the protective end plate 5 away from the pole group 2;

[0108] S232, measuring the distance L1 between the closest points of the cover module 3 and the insulating film 6, and determining whether L1 satisfies 0.5 mm ≤ L1 ≤ 3 mm, if yes, executing step S233, if not, executing step S234;

[0109] S233, after removing the pre-installed cover plate module 3, heat-melt the overlapping area between the insulating film 6 and the protective end plate 5 to form a pole group unit;

[0110] S234 , after removing the pre-installed cover module 3 , the insulating film 6 is trimmed, and after the trimming is completed, step S231 is executed.

[0111] By pre-installing the cover module 3 and determining that the distance dimension L1 between the cover module 3 and the insulating film 6 satisfies the range of 0.5mm≤L1≤3mm, on the one hand, it is avoided that the distance dimension L1 between the cover module 3 and the insulating film 6 is too small, which affects the welding of the cover module 3 and the composite shell 1 and easily causes problems such as welding explosion points. On the other hand, it is avoided that the distance dimension L1 between the cover module 3 and the insulating film 6 is too large, which leads to an increase in the height dimension of the protective end plate 5 and an increase in manufacturing costs.

[0112] In this embodiment, the distance dimension L1 between the cut insulating film 6 and the cover module 3 after assembly 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.

[0113] Alternatively, if Figure 2 , Figure 3 , Figure 5 As shown, a plurality of spaced-apart thermal melting points 62 are provided in the overlapping area between the insulating film 6 and the protective end plate 5, and the distance between the boundary of each thermal melting point 62 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.

[0114] By setting a plurality of spaced hot melting points 62, hot melting between the insulating film 6 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 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 62 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 62 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 62 and the boundary of the overlapping area away from the pole group 2 maintain a suitable distance, on the one hand, avoiding the insufficient operable area during hot melting due to too small a distance, and on the other hand, avoiding the loose connection of the area on the side of the hot melting point 62 away from the pole group 2 due to too large a distance.

[0115] Among them, the distance dimension L2 between the boundary of each thermal melting point 62 away from the electrode group 2 and the boundary of the overlapping area toward the cover module 3 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.

[0116] Alternatively, if Figure 2 , Figure 3 , Figure 5 As shown, the distance between the boundary of each thermal melting point 62 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.

[0117] By setting a plurality of spaced hot melting points 62, hot melting between the insulating film 6 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, and 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 62 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 62 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 62 and the boundary of the overlapping area facing the pole group 2 side maintain a suitable distance, on the one hand, avoid too small a distance, resulting in insufficient operable area during hot melting, and on the other hand, avoid too large a distance, resulting in loose connection of the area on the side of the hot melting point 62 facing the pole group 2 side.

[0118] Among them, the distance dimension L3 between the boundary of each hot melting point 62 facing the pole group 2 and the boundary of the overlapping area away from the cover module 3 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.

[0119] In this embodiment, in order to verify the influence of the distance dimension L1, the distance dimension L2 and the distance dimension L3 in the battery assembly method on the quality of the assembled product, as shown in Table 1, six groups of embodiments and six groups of comparative examples are provided for verification, wherein since the cover plate module 3 is composed of an independent pole 31, a first plastic part 32, a bare aluminum plate 33, a second plastic part 34, a seal 35 and a welding platform 36, the distance dimension L1 is essentially the distance between the side boundary of the insulating film 6 away from the pole group 2 and the surface of the bare aluminum plate 33 facing the pole group 2.

[0120] Table 1

[0121]

[0122] In Example 1, the distance L1 between the cover module 3 and the insulating film 6 is set to 0.5 mm, the distance L2 between the boundary of the hot melting point 62 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 62 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 there is no explosion point in the peripheral weld of the shell cover. After disassembling the battery, the insulating film 6 is not damaged and does not fall off.

[0123] In Example 2, the distance L1 between the cover module 3 and the insulating film 6 is set to 1 mm, the distance L2 between the boundary of the hot melting point 62 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 62 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, and it is verified that there is no explosion point in the peripheral weld of the shell cover. After disassembling the battery, the insulating film 6 is not damaged and does not fall off.

[0124] In Example 3, the distance L1 between the cover module 3 and the insulating film 6 is set to 1.5 mm, the distance L2 between the boundary of the hot melting point 62 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 62 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, and it is verified that there is no explosion point in the peripheral weld of the shell cover. After disassembling the battery, the insulating film 6 is not damaged and does not fall off.

[0125] In Example 4, the distance L1 between the cover module 3 and the insulating film 6 is set to 2 mm, the distance L2 between the boundary of the hot melting point 62 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 62 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 there is no explosion point in the peripheral weld of the shell cover. After disassembling the battery, the insulating film 6 is not damaged and does not fall off.

[0126] In Example 5, the distance L1 between the cover module 3 and the insulating film 6 is set to 2.5 mm, the distance L2 between the boundary of the hot melting point 62 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 62 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 there is no explosion point in the peripheral weld of the shell cover. After disassembling the battery, the insulating film 6 is not damaged and does not fall off.

[0127] In Example 6, the distance L1 between the cover module 3 and the insulating film 6 is set to 3 mm, the distance L2 between the boundary of the hot melting point 62 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 62 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, and it is verified that there is no explosion point in the peripheral weld of the shell cover. After disassembling the battery, the insulating film 6 is not damaged and does not fall off.

[0128] It can be seen from Examples 1 to 6 that when the distance dimension L1 between the cover plate module 3 and the insulating film 6 satisfies the range of 0.5mm≤L1≤3mm, the distance dimension L2 between the boundary of the hot melting point 62 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 62 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 the battery assembly method has no explosion points in the weld around the shell cover, and after disassembling the battery, the insulating film 6 is not damaged or falls off, and has high product quality.

[0129] In comparative example 1, the distance dimension L1 between the cover plate module 3 and the insulating film 6 is set to 0.1 mm, the distance dimension L2 between the boundary of the hot melting point 62 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 dimension L3 between the boundary of the hot melting point 62 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 assembled according to the above data is verified to have explosion points during welding around the shell cover, and the insulating film 6 melts.

[0130] It can be seen from Comparative Example 1 that when the distance dimension L1 between the cover module 3 and the insulating film 6 is less than the minimum value of 0.5mm≤L1≤3mm, at this time, since the insulating film 6 is close to the bare aluminum plate 33, an explosion point occurs when welding the periphery of the shell cover, and since the insulating film 6 is too close to the welding position, the high temperature generated by the welding causes the insulating film 6 to melt, resulting in poor insulation protection performance of the assembled battery.

[0131] In comparative example 2, the distance L1 between the cover module 3 and the insulating film 6 is set to 1 mm, the distance L2 between the boundary of the hot melting point 62 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 62 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 6 has fallen off.

[0132] It can be seen from Comparative Example 2 that when the distance dimension L2 between the boundary of the hot melting point 62 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, since the hot melting point 62 is close to the upper edge of the overlapping area of ​​the protective end plate 5, part of the hot melting point exceeds the upper edge of the insulating film 6, resulting in insufficient hot melting area between the insulating film 6 and the protective end plate 5, which causes the problem of the insulating film 6 falling off, resulting in poor insulation protection performance of the assembled battery.

[0133] In comparative example 3, the distance L1 between the cover plate module 3 and the insulating film 6 is set to 1 mm, the distance L2 between the boundary of the hot melting point 62 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 62 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 assembled according to the above data is verified to have a melting phenomenon between the insulating film 6 and the protective end plate 5, resulting in a short circuit.

[0134] It can be seen from Comparative Example 3 that when the distance dimension L3 between the boundary of the hot melting point 62 toward the side of the electrode group 2 and the boundary of the overlapping area toward the side of the electrode group 2 is less than the minimum value of 0.5mm≤L3≤3mm, since the hot melting point 62 is close to the lower edge of the overlapping area of ​​the protective end plate 5, part of the hot melting point 62 exceeds the lower edge of the protective end plate 5, resulting in melting through between the insulating film 6 and the protective end plate 5, thereby causing a short circuit problem, resulting in poor insulation protection performance of the assembled battery.

[0135] In comparative example 4, the distance L1 between the cover plate module 3 and the insulating film 6 is set to 4 mm, the distance L2 between the boundary of the hot melting point 62 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 62 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. It is verified 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.

[0136] It can be seen from Comparative Example 4 that when the distance dimension L1 between the cover plate module 3 and the insulating film 6 is greater than the maximum value of 0.5mm≤L1≤3mm, at this time, since the insulating film 6 is far away from the bare aluminum plate 33, the protective end plate 5 occupies a large internal space. Therefore, in order to complete the assembly, it is necessary to reduce the volume of the electrode group 2, thereby reducing the energy density of the assembled battery, and the power supply capacity is poor, which does not meet the use requirements.

[0137] In comparative example 5, the distance L1 between the cover module 3 and the insulating film 6 is set to 1 mm, the distance L2 between the boundary of the hot melting point 62 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 62 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 the insulating film 6 is located in the area between the hot melting point 62 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 6.

[0138] It can be seen from comparative example 5 that when the distance dimension L2 between the boundary of the hot melting point 62 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, since the hot melting point 62 is far away from the upper edge of the overlapping area of ​​the protective end plate 5, the insulating film 6 is located in the area between the hot melting point 62 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 6 being flanging, which does not meet the use requirements.

[0139] In comparative example 6, the distance dimension L1 between the cover module 3 and the insulating film 6 is set to 1 mm, the distance dimension L2 between the boundary of the hot melting point 62 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 dimension L3 between the boundary of the hot melting point 62 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 verified that the insulating film 6 is located in the area between the hot melting point 62 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 6 and the electrode group 2.

[0140] It can be seen from Comparative Example 6 that when the distance dimension L3 between the boundary of the hot melting point 62 toward the side of the pole group 2 and the boundary of the overlapping area toward the side of the pole group 2 is greater than the maximum value of 0.5mm≤L3≤3mm, since the hot melting point 62 is far away from the lower edge of the overlapping area of ​​the protective end plate 5, the insulating film 6 is located in the area between the hot melting point 62 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 6 to wrap the pole group 2, resulting in easy generation of gaps between the insulating film 6 and the pole group 2, which does not meet the use requirements.

[0141] Alternatively, if Figure 2 , Figure 3 , Figure 6 As shown, in step S5, the following steps are also included:

[0142] S51, the cover plate module 3 and the composite housing 1 are pre-welded and positioned at a plurality of first pre-welding points 100 arranged at intervals;

[0143] S52, fully welding the cover plate module 3 and the composite shell 1.

[0144] By pre-welding the cover module 3 and the composite shell 1 using a plurality of first pre-welding points 100 arranged at intervals, it is ensured that the relative positions of the cover module 3 and the composite shell 1 are positioned before full welding. Even if the initial positioning is incorrect, it is convenient to separate and reposition the two, thereby achieving recycling and reducing the scrap rate of the product.

[0145] In this embodiment, since the cover plate module 3 includes a large end face with a larger area and a small end face with a smaller area, the areas of the overlapping regions formed by different end faces and the composite shell 1 are also different, wherein at least three first pre-welding positions 100 are set on the surface with a larger area, preferably five, and at least one first pre-welding position 100 is set on the surface with a smaller area, preferably three, wherein the shape of the first pre-welding position 100 can be freely set according to demand, such as circular, elliptical or polygonal. Wherein, when there are multiple first pre-welding positions 100, it is necessary to ensure that the multiple first pre-welding positions 100 arranged at intervals are evenly distributed.

[0146] Alternatively, if Figure 2 , Figure 3 , Fig. 9 , Fig.10 As shown, the composite housing 1 includes a housing body 11 and a first insulating layer 12;

[0147] The housing body 11 includes a first wall surface 111 and a plurality of second walls 112 perpendicular to the first wall surface 111. The plurality of second walls 112 are arranged around the first wall surface 111 to form a hollow housing structure with one side open. The receiving groove 113 is provided on the side of the first wall surface 111 away from the pole group 2. The first wall surface 111 is also provided with a plug-in through hole 114 arranged in the receiving groove 113.

[0148] The first insulating layer 12 is injection molded on the first wall 111, and includes an upper insulating portion 121, a lower insulating portion 122 and a plug-in portion 123. The upper insulating portion 121 is arranged on the side of the first wall 111 away from the pole group 2 and is located in the accommodating groove 113. The lower insulating portion 122 is arranged on the side of the first wall 111 facing the pole group 2. The plug-in portion 123 is inserted in the plug-in through hole 114 and is used to connect the upper insulating portion 121 and the lower insulating portion 122. The second through structure 124 penetrates the upper insulating portion 121, the plug-in portion 123 and the lower insulating portion 122.

[0149] By providing a first insulating layer 12 consisting of an upper insulating portion 121, a lower insulating portion 122 and an inserting portion 123, and making the upper insulating portion 121 disposed on the side of the first wall 111 of the shell body 11 away from the pole group 2, and making the lower insulating portion 122 disposed on the side of the first wall 111 of the shell body 11 facing the pole group 2, making the inserting portion 123 inserted into the inserting through hole 114, and making the second penetrating structure 124 penetrate the upper insulating portion 121, the inserting portion 123 and the lower insulating portion 122, the first insulating layer 12 is utilized to achieve insulation protection for both sides of the first wall 111 of the shell body 11 and the inside of the inserting through hole 114, and the pole ear 21 and the first wall 111 of the shell body 11 are isolated, so as to avoid direct contact between the pole ear 21 and the first wall 111 of the shell body 11 when passing through the first wall 111 of the shell body 11, resulting in a short circuit, thereby ensuring safety and protection.

[0150] In this embodiment, the housing body 11 is an aluminum shell, and the first insulating layer 12 is a plastic part directly molded on the first wall 111 of the housing body 11 by an injection molding process. Compared with the traditional cover assembly, the separate lower insulating part is eliminated, thereby reducing the number of parts and simplifying the assembly process. In addition, in this embodiment, the upper insulating part 121, the plug-in part 123 and the lower insulating part 122 are an integrated structural part formed simultaneously by an injection molding process. In other embodiments, the upper insulating part 121, the plug-in part 123 and the lower insulating part 122 can also be separately injection molded and then plugged into each other, so that the first insulating layer 12 is a split structural part.

[0151] Alternatively, if Figure 2 , Figure 3 , Fig. 9 , Fig.10 As shown, in step S6, the following steps are also included:

[0152] S61, a mounting groove 125 is further provided on a side of the upper insulating portion 121 away from the housing body 11, and the battery further comprises a connecting piece 8, and the connecting piece 8 is installed in the mounting groove 125;

[0153] S62, bending the portion of the electrode tab 21 extending out of the second penetrating structure 124, and welding the bent electrode tab 21 to the connecting sheet 8;

[0154] S63, the battery further includes a sealing ring 9, and the sealing ring 9 is installed in the receiving groove 113;

[0155] S64, placing the composite pole 4 into the receiving slot 113;

[0156] S65. Weld the composite pole 4 and the composite housing 1.

[0157] By providing the connecting piece 8 and welding the pole lug 21 to the connecting piece 8, the position of the pole lug 21 can be fixed in advance by using the connecting piece 8, thereby ensuring the accuracy of the position of the pole lug 21 during subsequent operations and avoiding the pole lug 21 from moving and affecting the conduction effect of the current between the pole lug 21 and the composite pole 4.

[0158] Alternatively, if Figure 2 , Figure 3 As shown, in step S7, the following steps are also included:

[0159] S71, a connecting boss 81 is provided on one side of the connecting piece 8 facing the composite pole 4 and protrudes along the composite pole 4, and the composite pole 4 is pre-welded and positioned on the connecting boss 81 through a plurality of second pre-welding points arranged at intervals;

[0160] S72, fully weld the composite pole 4 and the connecting boss 81.

[0161] By providing a connecting boss 81 on the side of the connecting piece 8 facing the composite pole 4, it is convenient to weld the connecting piece 8 to the composite pole 4. The size and shape of the connecting boss 81 can be freely set according to demand, and it is sufficient to ensure that there is a sufficient welding area between the connecting boss 81 and the composite pole 4. In this embodiment, the connecting boss 81 is a truncated cone.

[0162] In addition, the composite pole 4 is first pre-welded to the connecting boss 81 through a plurality of second pre-welding points arranged at intervals, so as to ensure that the relative position between the composite pole 4 and the connecting boss 81 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.

[0163] Alternatively, if Figure 2 , Figure 3 , Fig. 9 , Fig.10 As shown, in step S65, the following steps are also included:

[0164] S651, the composite pole 4 includes a pole body 41, a welding ring 42 and a second insulating layer 43 for achieving an insulating connection between the pole body 41 and the welding ring 42, and the welding ring 42 is pre-welded and positioned in the receiving groove 113 through a plurality of third pre-welding points arranged at intervals;

[0165] S652, fully weld the welding ring 42 into the receiving groove 113.

[0166] First, the welding ring 42 is pre-welded in the receiving groove 113 through a plurality of third pre-welding points arranged at intervals, so as to ensure that the relative position of the welding ring 42 in the receiving groove 113 is positioned before full welding. Even if the initial positioning is wrong, it is convenient to separate the welding ring 42 and reposition it, so as to achieve recycling and reduce the scrap rate of the product. The number, size and shape of the third pre-welding points used to achieve pre-welding of the welding ring 42 can be freely set according to actual needs.

[0167] Optionally, in step S62, after the connecting piece 8 is installed in the installation groove 125, the bent pole tab 21 is welded to the side of the connecting piece 8 facing the composite housing 1, or the bent pole tab 21 is welded to the side of the connecting piece 8 facing the composite pole 4. In order to adapt to various different working environments, it is convenient to perform welding operations on the bent pole tab 21 and the connecting piece 8. In this embodiment, the bent pole tab 21 is welded to the side of the connecting piece 8 facing the composite pole 4.

[0168] Alternatively, if Figure 2 , Figure 3 , Fig.11 As shown, a shaping structure 52 corresponding to the first through structure 51 is provided on the side of the protective end plate 5 facing the pole group 2, and the shaping structure 52 is a trumpet-shaped structure whose opening gradually decreases in the direction away from the pole group 2, so that in step S1, the multiple converged pole ears 21 on the pole group 2 are better supported and fixed, the convergence state of the pole ears 21 is improved, and the problem of short circuit inside the battery due to poor convergence effect of the pole ears 21 is avoided.

[0169] In this embodiment, if Figure 2 As shown, a battery is also provided, which is assembled by the above-mentioned battery assembly method. The battery is assembled by applying the above-mentioned battery assembly method, so that 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.

[0170] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A battery assembly method, characterized in that: The battery assembled by the battery assembly method comprises a composite shell, an electrode group, a cover plate module, a composite electrode column and a protective end plate; The battery assembly method comprises the following steps: S1, the electrode group includes a first surface and a second surface with electrode ears, and a plurality of side surfaces perpendicular to the first surface and the second surface, the protective end plate is provided with a first penetration structure, the protective end plate is installed on the first surface and / or the second surface of the electrode group, and the electrode ears pass through the first penetration structure; S2, coating the outer side of the electrode group with an insulating film, so that the insulating film is coated on 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 cover plate module includes an independent pole, and the cover plate module is installed on any one side of the two sides of the pole group provided with the pole lug, and the pole lug on this side passes through the first penetration structure and is welded to the independent pole; S4, the composite shell is a single-side open structure with a cavity, a second through-structure for the pole ear to extend is provided on the wall surface opposite to the open side, and a first insulating layer for isolating the composite shell from the pole ear is injection-molded on the wall surface, the pole group unit equipped with the cover plate module is installed in the cavity of the composite shell, and the pole ear on the other side of the pole group that passes through the first through-structure passes through the second through-structure, and the cover plate module closes the opening of the composite shell; S5, welding the cover plate module to the composite shell; S6, a receiving groove is provided on a side of the composite shell away from the electrode group, the composite pole is placed in the receiving groove, and the composite pole is welded to the composite shell; S7, achieving current conduction between the composite pole and the pole lug.

2. The battery assembly method according to claim 1, characterized in that: 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-melt the overlapping area between the insulating film and the protective end plate.

3. The battery assembly method according to claim 2, 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 arranged 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.

4. The battery assembly method according to claim 2, characterized in that: In step S23, the following steps are also included: S231, pre-installing the cover plate module on a side of the protective end plate away from the pole group; S232, measuring the distance L1 between the closest points of the cover module and the insulating film, and determining whether L1 satisfies 0.5 mm ≤ L1 ≤ 3 mm, if yes, executing step S233, if not, executing step S234; S233, after removing the pre-installed cover plate module, hot-melt the overlapping area between the insulating film and the protective end plate to form the pole group unit; S234, after removing the pre-installed cover module, cutting the insulating film, after the cutting is completed, executing step S231.

5. The battery assembly method according to claim 2, characterized in that: A plurality of thermal melting points are arranged at intervals in the overlapping region between the insulating film and the protective end plate, and the distance between the boundary of each thermal melting point away from the electrode group and the boundary of the overlapping region away from the electrode group is L2, and satisfies 0.5mm≤L2≤3mm; 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.

6. The battery assembly method according to claim 1, characterized in that: In step S5, the following steps are also included: S51, the cover plate module and the composite shell are pre-welded and positioned at a plurality of first pre-welding points arranged at intervals; S52, fully welding the cover plate module and the composite shell.

7. The battery assembly method according to claim 1, characterized in that: The composite housing comprises a housing body and the first insulating layer; The shell body includes a first wall surface and a plurality of second wall surfaces perpendicular to the first wall surface, wherein the plurality of second wall surfaces are arranged around the first wall surface to form a hollow shell structure with a single-side opening, and the receiving groove is provided on a side of the first wall surface away from the pole group, and the first wall surface is also provided with a plug-in through hole arranged in the receiving groove; The first insulating layer is injection molded on the first wall, and includes an upper insulating portion, a lower insulating portion and a plug-in portion. The upper insulating portion is arranged on the side of the first wall facing away from the pole group and is located in the accommodating groove. The lower insulating portion is arranged on the side of the first wall facing the pole group. 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.

8. The battery assembly method according to claim 7, characterized in that: In step S6, the following steps are also included: S61, a mounting groove is further provided on a side of the upper insulating portion away from the housing body, and the battery further comprises a connecting piece, and the connecting piece is installed in the mounting groove; S62, bending the portion of the electrode tab extending out of the second penetrating structure, and welding the bent electrode tab to the connecting sheet; S63, the battery further includes a sealing ring, and the sealing ring is installed in the receiving groove; S64, placing the composite pole into the receiving slot; S65, welding the composite pole and the composite shell.

9. The battery assembly method according to claim 8, characterized in that: In step S7, the following steps are also included: S71, a connection boss protruding along the side of the connection piece facing the composite pole is provided, and the composite pole is pre-welded and positioned on the connection boss through a plurality of second pre-welding points arranged at intervals; S72, fully welding the composite pole and the connecting boss.

10. A battery, characterized in that The battery is assembled using the battery assembly method according to any one of claims 1 to 9.

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