Battery assembly method and battery

Abstract

The invention belongs to the technical field of batteries, and discloses a battery assembly method and a battery, the method comprises the following steps: S1, installing a protective end plate on a first surface and / or a second surface of a pole group; s2, the outer sides of a plurality of side faces of the pole group are coated with insulating films, and the insulating films and the protection end plates are subjected to hot melting to form pole group units; s3, loading the pole group unit into the cavity of the composite shell; s4, the composite cover plate is arranged at the opening of the composite shell; s5, the composite cover plate and the composite shell are welded; s6, welding the composite pole and the composite cover plate, and welding the composite pole and the composite shell; and S7, realizing current conduction between the composite pole and the tab. Current conduction is realized by finally connecting the tab and the composite pole, so that the influence of other welding procedures on the connection quality of the tab and the composite pole is avoided, and the occupation of the internal space of the composite shell is reduced and the utilization rate of the space is improved as the tab extends out of the composite shell to realize the current conduction.

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 column to the pole ear of the corresponding polarity, and then install the lower plastic and cover plate in sequence, and make a part of the pole column pass through the lower plastic and cover plate and extend out of the battery shell. After the cover plate is assembled, weld the cover plate to the battery shell, and then install the upper plastic, sealing ring and welding platform in sequence on the outer side of the cover plate corresponding to the part of the pole column, and complete the welding of the welding platform and the cover plate, as well as the welding of the welding platform and the pole column extending out of the cover 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 column first, and then complete the welding of the cover plate and the battery shell, the welding of the welding platform and the cover plate, and the welding of the welding platform and the pole column. As a result, the pole ear and the pole column that have been welded will be affected by adverse factors such as high temperature and vibration during the welding of the cover plate and the battery shell, the welding of the welding platform and the cover plate, and the welding of the welding platform and the pole column, thereby reducing the welding quality between the pole column and the pole ear and reducing the product yield. On the other hand, since this method also requires that the pole column and the pole ear be connected inside the battery shell, the pole ear and the pole column will occupy a larger space inside the battery shell, limiting the volume of the pole group and having a low energy density. In addition, since one side of the pole ear involves the welding of the cover plate and the battery shell, the welding of the welding platform and the cover plate, the welding of the welding platform and the pole column, and the welding of the pole ear and the pole column, a large number of welding operations are gathered on the pole ear side, resulting in adverse changes in the microstructure of the pole ear material due to the high temperature generated by a large number of welding operations, thereby affecting the electrical and mechanical properties of the pole ear itself, resulting in an increase in the resistance of the pole ear, 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 composite cover plate, 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 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 is installed in the cavity of the composite shell, and the pole ear passing through the first through-structure passes through the second through-structure;

[0011] S4, the composite cover plate is provided with a third penetration structure for the tab to extend out and a second insulating layer for isolating the composite cover plate from the tab, the composite cover plate is arranged at the open portion of the composite housing, and the tab that passes through the first penetration structure passes through the third penetration structure;

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

[0013] S6, a first receiving groove is formed on the side of the composite shell away from the electrode group, and a second receiving groove is formed on the side of the composite cover plate away from the electrode group, the composite pole is installed in the first receiving groove and the second receiving groove, and the composite pole is welded to the composite cover plate 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 composite cover plate on the side of the protective end plate away from the electrode group, and allowing the electrode lug passing through the first penetration structure to pass through the third penetration structure;

[0025] S232, measuring the distance L1 between the closest points of the composite cover plate 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 composite cover plate, 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 composite cover plate, 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 composite cover plate 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 composite cover plate 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, the plurality of second wall surfaces are arranged around the first wall surface to form a hollow shell structure with a single side open, the first receiving groove is opened on a side of the first wall surface away from the pole group, and the first wall surface is also provided with a first plug-in through hole arranged in the first receiving groove;

[0035] The first insulating layer is injection molded on the first wall, and includes a first upper insulating portion, a first lower insulating portion and a first plug-in portion. The first upper insulating portion is arranged on the side of the first wall facing away from the pole group and is located in the first accommodating groove. The first lower insulating portion is arranged on the side of the first wall facing the pole group. The first plug-in portion is inserted in the first plug-in through hole and is used to connect the first upper insulating portion and the first lower insulating portion. The second through-structure penetrates the first upper insulating portion, the first plug-in portion and the first lower insulating portion.

[0036] Optionally, the composite cover plate includes a cover plate body and the second insulating layer;

[0037] The second receiving groove is formed on the cover body, and the cover body is also provided with a second plugging through hole disposed in the second receiving groove;

[0038] The second insulating layer is injection molded on the cover body and includes a second upper insulating portion, a second lower insulating portion and a second plug-in portion. The second upper insulating portion is arranged on a side of the cover body away from the pole group and is located in the second accommodating groove. The second lower insulating portion is arranged on a side of the cover body facing the pole group. The second plug-in portion is inserted in the second plug-in through hole and is used to connect the second upper insulating portion and the second lower insulating portion. The third penetrating structure penetrates the second upper insulating portion, the second plug-in portion and the second lower insulating portion.

[0039] Optionally, in step S6, the following steps are also included:

[0040] S61, a first mounting groove is further formed on a side of the first upper insulating portion facing away from the shell body, a second mounting groove is further formed on a side of the second upper insulating portion facing away from the cover body, the battery further comprises a connecting piece, and the connecting piece is installed in the first mounting groove and the second mounting groove;

[0041] S62, bending the portion of the electrode tab extending out of the second through-structure and the third through-structure, and welding the bent electrode tab to the connecting sheet;

[0042] S63: The battery further includes a sealing ring, and the sealing ring is installed in the first receiving groove and the second receiving groove;

[0043] S64, placing the composite pole into the first receiving groove and the second receiving groove;

[0044] S65, welding the composite pole and the composite cover plate, and welding the composite pole and the composite shell.

[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 first welds a composite cover plate to a composite shell, then welds a composite pole to the composite shell and the composite cover plate, and finally connects a pole ear to the composite pole to achieve current conduction, thereby avoiding the influence of other welding processes on the connection quality between the pole ear and the composite pole that have achieved current conduction, and enables the pole ear to achieve current conduction with the composite pole located outside the composite shell through a second penetration structure and a third penetration structure, eliminating the space occupied by the pole ear and the composite pole and the composite pole extending into the composite shell, thereby reducing the occupation of the internal space and improving the utilization of the space on the one hand, and providing space for increasing the pole group and improving the energy density on the other hand, and providing a first surface of the pole ear on the pole group, and / or providing a protective end plate with a first penetration structure on the second surface, thereby supporting the pole ear to be gathered, avoiding the pole ear from being skewed, and ensuring the reliability of the structure. In addition, by adopting a single-side open composite shell in combination with a single composite cover plate structure, the side of the pole ear extending through the second through-structure of the composite shell of the pole group has less welding work, thereby reducing the influence 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 3It is a partial structural cross-sectional view of the first wall surface of the composite shell of the battery provided by the present invention;

[0052] Figure 4 It is a partial structural cross-sectional view of the composite cover plate in the battery provided by the present invention;

[0053] Figure 5 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;

[0054] Figure 6 It is a schematic diagram of the distribution of hot melting points of the protective end plate and the insulating film at the composite cover plate of the battery provided by the present invention;

[0055] Figure 7 yes Figure 6 A magnified view of the structure of part A;

[0056] Figure 8 It is a schematic diagram of the distribution of pre-welding points of the composite cover plate and the composite shell in the battery provided by the present invention;

[0057] Fig. 9 It is a schematic structural diagram 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 schematic diagram of the structure of the cover plate body in the battery provided by the present invention;

[0060] Fig.12 is a schematic structural diagram of the second insulating layer in the battery provided by the present invention;

[0061] Fig.13 It is a structural schematic diagram of a protective end plate in a battery provided by the present invention.

[0062] In the figure:

[0063] 100, first pre-welding point;

[0064] 1. Composite housing; 11. Housing body; 111. First wall surface; 112. Second wall surface; 113. First receiving groove; 114. First plug-in through hole; 12. First insulating layer; 121. First upper insulating portion; 122. First lower insulating portion; 123. First plug-in portion; 124. Second penetration structure; 125. First mounting groove;

[0065] 2. pole group; 21. pole ear; 22. first surface; 23. second surface; 24. side surface;

[0066] 3. Composite cover plate; 31. Cover plate body; 311. Second receiving groove; 312. Second plug-in through hole; 32. Second insulating layer; 321. Second upper insulating portion; 322. Second lower insulating portion; 323. Second plug-in portion; 324. Third penetration structure; 325. Second mounting groove;

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

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

[0069] 6. Insulating film; 61. Positioning hole; 62. Thermal melting point;

[0070] 7. Protective side panels;

[0071] 8. Connecting piece; 81. Connecting boss;

[0072] 9. Sealing ring. DETAILED DESCRIPTION

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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 composite cover plate 3, a composite pole 4 and a protective end plate 5.

[0078] like Figures 1 to 13 As shown, the battery assembly method includes the following steps:

[0079] 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;

[0080] 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;

[0081] S3, 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 is installed in the cavity of the composite housing 1, and the pole ear 21 passing through the first through-structure 51 passes through the second through-structure 124;

[0082] S4, the composite cover plate 3 is provided with a third penetration structure 324 for the pole ear 21 to extend out and a second insulating layer 32 for isolating the composite cover plate 3 from the pole ear 21, the composite cover plate 3 is arranged at the open portion of the composite housing 1, and the pole ear 21 passing through the first penetration structure 51 passes through the third penetration structure 324;

[0083] S5, welding the composite cover plate 3 to the composite shell 1;

[0084] S6. A first receiving groove 113 is formed on the side of the composite housing 1 facing away from the pole group 2, and a second receiving groove 311 is formed on the side of the composite cover plate 3 facing away from the pole group 2. The composite pole 4 is installed into the first receiving groove 113 and the second receiving groove 311, and the composite pole 4 is welded to the composite cover plate 3 and the composite pole 4 is welded to the composite housing 1;

[0085] S7, achieving current conduction between the composite pole 4 and the pole ear 21.

[0086] The battery assembly method first welds the composite cover plate 3 to the composite shell 1, then welds the composite pole 4 to the composite shell 1 and the composite cover plate 3, and finally connects the pole ear 21 to the composite pole 4 to achieve current conduction, thereby avoiding the influence of other welding processes on the connection quality between the pole ear 21 and the composite pole 4 that have achieved current conduction, and enables the pole ear 21 to achieve current conduction with the composite pole 4 located outside the composite shell 1 through the second penetration structure 124 and the third penetration structure 324, eliminating the space occupied by the connection between the pole ear 21 and the composite pole 4 and the composite pole 4 extending into the composite shell 1, thereby reducing the occupation of the internal space and improving the utilization of the space on the one hand, and providing space for increasing the pole group 2 on the other hand, improving the energy density, and providing a first surface 22 of the pole ear 21 on the pole group 2, and / or a second surface 23 The protective end plate 5 with a first penetration structure 51 is provided, so that the pole ear 21 is supported and folded, and the pole ear 21 is prevented from being skewed, thereby ensuring the reliability of the structure. In addition, by adopting a single-sided open composite shell 1 in combination with a single composite cover plate 3, the side of the pole ear 21 of the pole group 2 extending through the second through 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.

[0087] In this embodiment, the first surface 22 and the second surface 23 of the pole group 2 are both equipped with protective end plates 5, and when the protective end plates 5 on both sides of the pole group 2 are assembled and the protective end plates 5 and the insulating film 6 on both sides are hot-melted, the two protective end plates 5 can be assembled and hot-melted at the same time, or the protective end plates 5 on one side can be assembled and hot-melted separately first, and then the protective end plates 5 on the other side can be assembled and hot-melted. The assembly method is freely selected according to the actual site conditions.

[0088] Alternatively, if Figure 2 , Figure 5 As shown, in step S2, the following steps are also included:

[0089] 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;

[0090] 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;

[0091] S23, hot-melt the overlapping area between the insulating film 6 and the protective end plate 5.

[0092] 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 the side surface 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.

[0093] 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.

[0094] Alternatively, if Figure 2 , Figure 5 As shown, in step S21, the following steps are also included:

[0095] S211, opening a positioning hole 61 at a set position of the insulating film 6;

[0096] 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;

[0097] S213, hot-melt the assembled protective side plate 7 and the insulating film 6.

[0098] 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.

[0099] Alternatively, if Figure 2 , Figure 6 , Figure 7 As shown, in step S23, the following steps are also included:

[0100] S231, pre-install the composite cover plate 3 on the side of the protective end plate 5 away from the electrode group 2, and make the electrode ear 21 passing through the first penetration structure 51 pass through the third penetration structure 324;

[0101] S232, measuring the distance L1 between the closest points of the composite cover plate 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;

[0102] S233, after removing the pre-installed composite cover plate 3, heat-melt the overlapping area between the insulating film 6 and the protective end plate 5 to form a pole group unit;

[0103] S234, after removing the pre-installed composite cover plate 3, the insulating film 6 is trimmed, and after the trimming is completed, step S231 is executed.

[0104] By pre-installing the composite cover plate 3 and determining that the distance dimension L1 between the composite cover plate 3 and the insulating film 6 satisfies the range of 0.5mm≤L1≤3mm, on the one hand, it is possible to avoid the distance dimension L1 between the composite cover plate 3 and the insulating film 6 being too small, which will affect the welding of the composite cover plate 3 and the composite shell 1 and easily cause problems such as welding explosion points. On the other hand, it is possible to avoid the distance dimension L1 between the composite cover plate 3 and the insulating film 6 being too large, which will increase the height dimension of the protective end plate 5 and increase the manufacturing cost.

[0105] In this embodiment, the spacing dimension L1 between the cut insulating film 6 and the composite cover plate 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.

[0106] Alternatively, if Figure 2 , Figure 6 , Figure 7 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.

[0107] 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.

[0108] Among them, the distance dimension L2 between the boundary of each thermal melting point 62 away from the pole group 2 and the boundary of the overlapping area toward the composite cover plate 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.

[0109] Alternatively, if Figure 2 , Figure 6 , Figure 7 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.

[0110] 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.

[0111] Among them, the distance dimension L3 between the boundary of each thermal melting point 62 toward the pole group 2 and the boundary of the overlapping area away from the composite cover plate 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.

[0112] Alternatively, if Figure 2 , Figure 8 As shown, in step S5, the following steps are also included:

[0113] S51, the composite cover plate 3 and the composite shell 1 are pre-welded and positioned at a plurality of first pre-welding points 100 arranged at intervals;

[0114] S52, fully welding the composite cover plate 3 and the composite shell 1.

[0115] By pre-welding the composite cover plate 3 and the composite shell 1 using a plurality of first pre-welding points 100 arranged at intervals, it is ensured that the relative position between the composite cover plate 3 and the composite shell 1 is 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.

[0116] 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;

[0117] 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. A first receiving groove 113 is provided on a side of the first wall surface 111 away from the pole group 2. The first wall surface 111 is also provided with a first plug-in through hole 114 arranged in the first receiving groove 113.

[0118] The first insulating layer 12 is injection molded on the first wall 111, and includes a first upper insulating portion 121, a first lower insulating portion 122 and a first plug-in portion 123. The first 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 first accommodating groove 113. The first lower insulating portion 122 is arranged on the side of the first wall 111 facing the pole group 2. The first plug-in portion 123 is inserted in the first plug-in through hole 114 and is used to connect the first upper insulating portion 121 and the first lower insulating portion 122. The second through structure 124 penetrates the first upper insulating portion 121, the first plug-in portion 123 and the first lower insulating portion 122.

[0119] By providing a first insulating layer 12 consisting of a first upper insulating portion 121, a first lower insulating portion 122 and a first plug-in portion 123, and making the first 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 first 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 first plug-in portion 123 inserted into the first plug-in through hole 114, and making the second penetrating structure 124 penetrate the first upper insulating portion 121, the first plug-in portion 123 and the first 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 first plug-in 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.

[0120] Alternatively, if Figure 2 , Figure 3 , Fig.11 , Fig.12 As shown, the composite cover plate 3 includes a cover plate body 31 and a second insulating layer 32;

[0121] The second receiving groove 311 is formed on the cover body 31 , and the cover body 31 is also formed with a second plugging through hole 312 disposed in the second receiving groove 311 ;

[0122] The second insulating layer 32 is injection molded on the cover body 31, and includes a second upper insulating portion 321, a second lower insulating portion 322 and a second plug-in portion 323. The second 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 second accommodating groove 311. The second lower insulating portion 322 is arranged on the side of the cover body 31 facing the pole group 2. The second plug-in portion 323 is inserted in the second plug-in through hole 312 and is used to connect the second upper insulating portion 321 and the second lower insulating portion 322. The third through-structure 324 penetrates the second upper insulating portion 321, the second plug-in portion 323 and the second lower insulating portion 322.

[0123] By setting a second insulating layer 32 composed of a second upper insulating part 321, a second lower insulating part 322 and a second plug-in part 323, and making the second upper insulating part 321 arranged on the side of the cover body 31 away from the pole group 2, and making the second lower insulating part 322 arranged on the side of the cover body 31 facing the pole group 2, the second plug-in part 323 is inserted into the second plug-in through hole 312, and the third penetrating structure 324 penetrates the second upper insulating part 321, the second plug-in part 323 and the second lower insulating part 322, the second insulating layer 32 is used to achieve insulation protection for both sides of the cover body 31 and the inside of the second plug-in through hole 312, and isolate the pole ear 21 and the cover body 31, so as 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.

[0124] In this embodiment, in order to verify the influence of distance dimension L1, distance dimension L2 and 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 the cover plate body 31 in the composite cover plate 3 is actually welded to the outer shell body 11, so the distance dimension L1 between the nearest point between the composite cover plate 3 and the insulating film 6 is essentially the distance between the cover plate body 31 and the boundary of the insulating film 6 away from the electrode group 2.

[0125] Table 1

[0126]

[0127] In Example 1, the distance L1 between the composite cover plate 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, 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] In Example 2, the distance L1 between the composite cover plate 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.

[0129] In Example 3, the distance L1 between the composite cover plate 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.

[0130] In Example 4, the distance L1 between the composite cover plate 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, 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.

[0131] In Example 5, the distance L1 between the composite cover plate 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, 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.

[0132] In Example 6, the distance L1 between the composite cover plate 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.

[0133] It can be seen from Examples 1 to 6 that when the distance dimension L1 between the composite cover plate 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.

[0134] In comparative example 1, the distance dimension L1 between the composite cover plate 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.

[0135] It can be seen from Comparative Example 1 that when the distance dimension L1 between the composite cover plate 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 cover plate body 31, 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.

[0136] In comparative example 2, the distance dimension L1 between the composite cover plate 3 and the insulating film 6 is set to 1mm, the distance dimension L2 between the boundary of the hot melting point 62 away from the pole group 2 and the boundary of the overlapping area away from the pole group 2 is set to 0.1mm, and the distance dimension L3 between the boundary of the hot melting point 62 toward the pole group 2 and the boundary of the overlapping area toward the pole group 2 is set to 1mm. At this time, the assembled battery is completed according to the above data, and it is verified that the insulating film 6 has fallen off. It can be seen from comparative example 2 that when the dimension L2 of the distance between the boundary of the hot melting point 62 away from the pole group 2 and the boundary of the overlapping area away from the pole group 2 is less than the minimum value of 0.5mm≤L2≤3mm, the hot melting point 62 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 6, resulting in insufficient hot melting area between the insulating film 6 and the protective end plate 5, thereby causing the problem of the insulating film 6 falling off, resulting in poor insulation protection performance of the assembled battery.

[0137] In comparative example 3, the distance dimension L1 between the composite cover plate 3 and the insulating film 6 is set to 1mm, the distance dimension L2 between the boundary of the hot melting point 62 away from the pole group 2 and the boundary of the overlapping area away from the pole group 2 is set to 1mm, and the distance dimension L3 between the boundary of the hot melting point 62 toward the pole group 2 and the boundary of the overlapping area toward the pole group 2 is set to 0.1mm. 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. It can be seen from comparative example 3 that when the dimension L3 of the distance between the boundary of the hot melting point 62 toward the pole group 2 and the boundary of the overlapping area toward the pole group 2 is less than the minimum value of 0.5mm≤L3≤3mm, the hot melting point 62 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 62 exceeding the lower edge of the protective end plate 5, resulting in a melting phenomenon 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.

[0138] In comparative example 4, the distance dimension L1 between the composite cover plate 3 and the insulating film 6 is set to 4mm, the distance dimension L2 between the boundary of the hot melting point 62 away from the pole group 2 and the boundary of the overlapping area away from the pole group 2 is set to 1mm, and the distance dimension L3 between the boundary of the hot melting point 62 toward the pole group 2 and the boundary of the overlapping area toward the pole group 2 is set to 1mm. At this time, the assembled battery is completed according to the above data. It is verified that the second insulating layer 32 occupies a large internal space, resulting in the compression of the pole group 2, which leads to a low energy density of the assembled battery. It can be seen from comparative example 4 that when the distance dimension L1 between the composite cover plate 3 and the insulating film 6 is greater than the maximum value of 0.5mm≤L1≤3mm, at this time, because the insulating film 6 is far away from the cover plate body 31, the second insulating layer 32 occupies a large internal space, so in order to complete the assembly, it is necessary to reduce the volume of the pole 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.

[0139] In comparative example 5, the distance dimension L1 between the composite cover plate 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 4 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 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. 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.

[0140] In comparative example 6, the distance dimension L1 between the composite cover plate 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, is not tightly connected to the protective end plate 5, and there is a gap between the insulating film 6 and the electrode group 2. 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 , Fig. 9 , Fig.11 As shown, in step S6, the following steps are also included:

[0142] S61, a first mounting groove 125 is further provided on a side of the first upper insulating portion 121 away from the housing body 11, a second mounting groove 325 is further provided on a side of the second upper insulating portion 321 away from the cover body 31, and the battery further includes a connecting piece 8, and the connecting piece 8 is installed in the first mounting groove 125 and the second mounting groove 325;

[0143] S62, bending the electrode tab 21 to extend out of the second penetrating structure 124 and the third penetrating structure 324, and welding the bent electrode tab 21 to the connecting sheet 8;

[0144] S63, the battery further includes a sealing ring 9, and the sealing ring 9 is installed in the first receiving groove 113 and the second receiving groove 311;

[0145] S64, placing the composite pole 4 into the first receiving groove 113 and the second receiving groove 311;

[0146] S65, welding the composite pole 4 and the composite cover plate 3 as well as the composite pole 4 and the composite housing 1.

[0147] 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.

[0148] Optionally, in step S7, the following steps are also included:

[0149] 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;

[0150] S72, fully weld the composite pole 4 and the connecting boss 81.

[0151] Alternatively, if Figure 2 , Figure 3 , Figure 4 As shown, in step S65, the following steps are also included:

[0152] S651, the composite pole 4 includes a pole body 41, a welding ring 42 and a third insulating layer 43 for achieving an insulated connection between the pole body 41 and the welding ring 42, and the welding ring 42 is pre-welded and positioned in the first receiving groove 113 and the second receiving groove 311 through a plurality of third pre-welding points arranged at intervals;

[0153] S652 , fully weld the welding ring 42 in the first accommodating groove 113 and the second accommodating groove 311 .

[0154] Alternatively, if Figure 2 , Figure 3 , Figure 4 , Fig.13 As shown, a shaping structure 52 corresponding to the first penetrating structure 51 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 decreases in the direction away from the pole group 2, so as to better support and fix the multiple converged pole ears 21 on the pole group 2.

[0155] In this embodiment, if Figure 2 As shown, a battery is also provided, which is assembled by the above-mentioned battery assembly method, so that the volume of the electrode group 2 can be further increased, thereby improving the energy density of the battery and increasing the power supply capacity of the battery.

[0156] 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 composite cover plate, 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 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 is installed in the cavity of the composite shell, and the pole ear passing through the first through-structure passes through the second through-structure; S4, the composite cover plate is provided with a third penetration structure for the tab to extend out and a second insulating layer for isolating the composite cover plate from the tab, the composite cover plate is arranged at the open portion of the composite housing, and the tab that passes through the first penetration structure passes through the third penetration structure; S5, welding the composite cover plate to the composite shell; S6, a first receiving groove is formed on the side of the composite shell away from the electrode group, and a second receiving groove is formed on the side of the composite cover plate away from the electrode group, the composite pole is installed in the first receiving groove and the second receiving groove, and the composite pole is welded to the composite cover plate 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 composite cover plate on the side of the protective end plate away from the electrode group, and allowing the electrode lug passing through the first penetration structure to pass through the third penetration structure; S232, measuring the distance L1 between the closest points of the composite cover plate 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 composite cover plate, 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 composite cover plate, 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 composite cover plate and the composite shell are pre-welded and positioned at a plurality of first pre-welding points arranged at intervals; S52, fully welding the composite cover plate 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, the plurality of second wall surfaces are arranged around the first wall surface to form a hollow shell structure with a single side open, the first receiving groove is opened on a side of the first wall surface away from the pole group, and the first wall surface is also provided with a first plug-in through hole arranged in the first receiving groove; The first insulating layer is injection molded on the first wall, and includes a first upper insulating portion, a first lower insulating portion and a first plug-in portion. The first upper insulating portion is arranged on the side of the first wall facing away from the pole group and is located in the first accommodating groove. The first lower insulating portion is arranged on the side of the first wall facing the pole group. The first plug-in portion is inserted in the first plug-in through hole and is used to connect the first upper insulating portion and the first lower insulating portion. The second through-structure penetrates the first upper insulating portion, the first plug-in portion and the first lower insulating portion.

8. The battery assembly method according to claim 7, characterized in that: The composite cover plate comprises a cover plate body and the second insulating layer; The second receiving groove is formed on the cover body, and the cover body is also provided with a second plugging through hole disposed in the second receiving groove; The second insulating layer is injection molded on the cover body and includes a second upper insulating portion, a second lower insulating portion and a second plug-in portion. The second upper insulating portion is arranged on a side of the cover body away from the pole group and is located in the second accommodating groove. The second lower insulating portion is arranged on a side of the cover body facing the pole group. The second plug-in portion is inserted in the second plug-in through hole and is used to connect the second upper insulating portion and the second lower insulating portion. The third penetrating structure penetrates the second upper insulating portion, the second plug-in portion and the second lower insulating portion.

9. The battery assembly method according to claim 8, characterized in that: In step S6, the following steps are also included: S61, a first mounting groove is further formed on a side of the first upper insulating portion facing away from the shell body, a second mounting groove is further formed on a side of the second upper insulating portion facing away from the cover body, the battery further comprises a connecting piece, and the connecting piece is installed in the first mounting groove and the second mounting groove; S62, bending the portion of the electrode tab extending out of the second through-structure and the third through-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 first receiving groove and the second receiving groove; S64, placing the composite pole into the first receiving groove and the second receiving groove; S65, welding the composite pole and the composite cover plate, and welding the composite pole and the composite shell.

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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