Battery

Abstract

The utility model provides a battery which comprises a shell, a battery cell, a battery cell tab, an adapter tab and an expansion protection piece, the battery cell, the battery cell tab and the expansion protection piece are all located in the shell, the battery cell tab is connected to the battery cell, and the overlapped parts of the adapter tab and the battery cell tab are welded and connected, so that a welding area is formed at the overlapped part of the adapter tab and the battery cell tab; the welding area comprises at least one welding mark; the expansion protection part comprises a first expansion protection part, the first expansion protection part is connected to one surface, deviating from the switching tab, of the battery cell tab, or the first expansion protection part is connected to one surface, deviating from the battery cell tab, of the switching tab, and the projection of the first expansion protection part in the welding area is at least partially overlapped with the welding mark. According to the battery disclosed by the invention, the first expansion protection piece can eliminate the gap between the battery cell and the shell, so that the battery cell is prevented from vibrating during use, the welding marks and the battery cell are isolated, and residues of the welding marks are prevented from falling into the battery cell.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery. Background Art

[0002] At present, lithium-ion batteries are widely used in various electronic devices and mechanical devices. In related technologies, lithium-ion batteries may include a battery case, a battery cell and a tab assembly. The battery cell may include a pole piece and a diaphragm. The pole piece is coated with an active material. The pole piece and the diaphragm are stacked and wound to form a cylindrical battery cell or an elliptical battery cell. Correspondingly, the battery case may adopt a cylindrical case or a square case. The tab assembly may include a soft tab and a hard tab. The soft tab is welded to the positive pole piece and the negative pole piece, and the hard tab is welded to the soft tab. Part of the hard tab is located outside the battery case to conduct the current of the battery cell.

[0003] In order to improve the energy density of lithium-ion batteries, sealing welding can be used for packaging. However, after packaging in this way, there is still some gap between the battery cell and the battery cell shell. During subsequent use, it is easy to cause the battery cell to vibrate, which in turn causes the electrode to lose powder, thereby affecting the performance of the lithium-ion battery. Utility Model Content

[0004] Based on this, the present application provides a battery to solve the deficiencies in the related art.

[0005] The battery provided in the present application comprises a housing, a battery cell, a battery cell tab, a transfer tab and an expansion protection member, wherein the battery cell, the battery cell tab and the expansion protection member are all located in the housing, the battery cell tab is connected to the battery cell, and the overlapping portion of the transfer tab and the battery cell tab is welded and connected, so that the overlapping portion of the transfer tab and the battery cell tab forms a welding area, and the welding area comprises at least one weld mark;

[0006] The expansion protection piece includes a first expansion protection piece, which is connected to the side of the battery cell tab away from the adapter tab, or the first expansion protection piece is connected to the side of the adapter tab away from the battery cell tab, and the projection of the first expansion protection piece in the welding area at least partially overlaps with the weld mark.

[0007] In a possible implementation, the battery provided in the present application further includes a plastic part, the battery cell is cylindrical, the plastic part is located between the adapter tab and the inner wall of the shell, and the first expansion protection part is located between the adapter tab and the plastic part.

[0008] In a possible implementation, the expansion protection member further includes a second expansion protection member, which includes a first connection portion and a second connection portion connected to each other, wherein the first connection portion is connected to the outer peripheral wall of the battery cell, and the second connection portion is connected to the end surface of the battery cell.

[0009] In a possible implementation, an extension length of the first connecting portion along the axial direction of the battery cell is greater than or equal to 1 mm and less than or equal to 20 mm.

[0010] In a possible implementation, the housing is square, and the first expansion protection member is located between the battery cell tab and the battery cell;

[0011] Alternatively, the first expansion protection member is located between the battery cell tab and the housing.

[0012] In a possible implementation manner, the first expansion protection member and the second expansion protection member are integrally formed, or the first expansion protection member and the second expansion protection member are separately provided.

[0013] In a possible implementation, the expansion protection element includes a substrate layer, an adhesive layer and an expansion layer, the two opposite sides of the expansion layer are connected to the adhesive layer, at least one side of the substrate layer is connected to the adhesive layer, and the substrate layer and the expansion layer are connected via the adhesive layer.

[0014] In a possible implementation manner, the expansion layer has pores, and a porosity of the pores is greater than or equal to 10% and less than or equal to 90%.

[0015] In a possible implementation, the material of the substrate layer includes at least one of polyethylene terephthalate, polypropylene and polyimide, and the material of the expansion layer includes at least one of oriented polystyrene film, biaxially stretched polypropylene film, biaxially stretched nylon film and biaxially stretched polyester film.

[0016] In a possible implementation, the thickness of the expansion protection element is greater than or equal to 0.02 mm and less than or equal to 10 mm.

[0017] In a possible implementation, a ratio of a thickness of the first expansion protection member to a thickness of the second expansion protection member is greater than or equal to 1 and less than or equal to 10;

[0018] Alternatively, the ratio of the thickness of the second expansion protection member to the thickness of the first expansion protection member is greater than 1 and less than or equal to 10.

[0019] In one possible implementation, the adapter tab includes a first busbar, the outer shell includes a shell and a shell cover, the shell cover is connected to one end of the shell, the first busbar is connected to an end of the battery cell away from the shell cover, and the thickness of the first expansion protection piece gradually decreases from the center of the battery cell to the outside of the battery cell.

[0020] In a possible implementation, a ratio of a thickness of the first expansion protection member at a side away from the center of the battery cell to a thickness of the first expansion protection member at a side close to the center of the battery cell is greater than or equal to 1 / 5 and less than 1.

[0021] In a possible implementation manner, a ratio of an area of ​​the welding zone to a projection area of ​​the first expansion protection component on the welding zone is greater than or equal to 1 and less than or equal to 5.

[0022] The battery provided in the present application includes a shell, a battery cell, a battery cell tab, a transfer tab and an expansion protection member, wherein a welding area is provided between the battery cell tab and the transfer tab, the welding area includes a weld mark, and the expansion protection member includes a first expansion protection member. The first expansion protection member can be provided on the side of the transfer tab away from the battery cell tab, or the first expansion protection member can be provided on the side of the battery cell tab away from the transfer tab, so that the first expansion protection member expands along its own thickness direction after being infiltrated by the electrolyte to increase its own thickness, thereby reducing or eliminating the gap between the battery cell and the shell, thereby reducing the possibility of vibration of the battery cell during subsequent use. At the same time, the projection of the first expansion protection member in the welding area covers the weld mark to isolate the weld mark and the battery cell, thereby preventing the residue of the weld mark from falling into the battery cell, thereby protecting the battery cell.

[0023] In addition to the technical problems solved by the embodiments of the present application described above, the technical features that constitute the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions, other technical problems that can be solved by the battery provided by the present application, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail in the specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of the structure of the battery provided in the embodiment of the present application Figure 1 ;

[0026] Figure 2 for Figure 1 A partial enlarged view of the middle part;

[0027] Figure 3 for Figure 1 A partial enlarged view of point B in the middle;

[0028] Figure 4 for Figure 1 Exploded diagram of

[0029] Figure 5 Schematic diagram of the structure of the battery provided in the embodiment of the present application Figure 2 ;

[0030] Figure 6 for Figure 5 A partial enlarged view of point C in the middle;

[0031] Figure 7 for Figure 5 Exploded diagram of

[0032] Figure 8 A schematic diagram of the structure of the transfer tab in the battery provided in the embodiment of the present application;

[0033] Fig. 9 Schematic diagram of the structure of the battery provided in the embodiment of the present application Figure 3 ;

[0034] Fig.10 Schematic diagram of the structure of the battery provided in the embodiment of the present application Figure 4 ;

[0035] Fig.11 Schematic diagram of the structure of the first expansion protection member and the weld mark in the battery provided in the embodiment of the present application Figure 1 ;

[0036] Fig.12 Schematic diagram of the structure of the first expansion protection member and the weld mark in the battery provided in the embodiment of the present application Figure 2 ;

[0037] Fig.13 Schematic diagram of the structure of the expansion protection member in the battery provided in the embodiment of the present application Figure 1 ;

[0038] Fig.14 Schematic diagram of the structure of the first connecting portion of the battery provided in the embodiment of the present application Figure 1 ;

[0039] Fig.15 Schematic diagram of the structure of the first connecting portion in the battery provided in the embodiment of the present application Figure 2 ;

[0040] Fig.16 Schematic diagram of the structure of the first connecting portion of the battery provided in the embodiment of the present application Figure 3 ;

[0041] Fig.17 Schematic diagram of the structure of the expansion protection member in the battery provided in the embodiment of the present application Figure 2 .

[0042] Description of reference numerals:

[0043] 100-shell; 110-shell; 120-shell cover; 200-battery cell; 300-battery cell pole ear; 400-adapter pole ear; 410-first busbar; 420-second busbar; 500-expansion protection piece; 510-first expansion protection piece; 520-second expansion protection piece; 521-first connecting part; 5211-incision; 522-second connecting part; 530-base material layer; 540-adhesive layer; 550-expansion layer; 600-welding area; 610-weld mark; 700-plastic part; 800-pole. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiment of the present application will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals throughout represent the same or similar parts or parts with the same or similar functions. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. The embodiments of the present application are described in detail below in conjunction with the drawings.

[0045] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, or it can be 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 this application can be understood according to specific circumstances.

[0046] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are orientations or positional relationships based on the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0047] The terms "first", "second", "third" (if any) in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0048] In addition, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or display comprising a series of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such process, method, product, or display.

[0049] At present, lithium-ion batteries are widely used in various electronic devices and mechanical devices. In related technologies, lithium-ion batteries may include a battery case, a battery cell and a tab assembly. The battery cell may include a pole piece and a diaphragm. The pole piece is coated with an active material. The pole piece and the diaphragm are stacked and wound to form a cylindrical battery cell or an elliptical battery cell. Correspondingly, the battery case may adopt a cylindrical case or a square case. The tab assembly may include a soft tab and a hard tab. The soft tab is welded to the positive pole piece and the negative pole piece, and the hard tab is welded to the soft tab. Part of the hard tab is located outside the battery case to conduct the current of the battery cell.

[0050] In order to improve the energy density of lithium-ion batteries, sealing welding can be used for packaging. However, after packaging in this way, there is still some gap between the battery cell and the battery cell shell. During subsequent use, it is easy to cause the battery cell to vibrate, which in turn causes the electrode to lose powder, thereby affecting the performance of the lithium-ion battery.

[0051] In view of this, an embodiment of the present application provides a battery, by arranging a first expansion protective piece on the side of the battery cell tab facing away from the adapter tab, or by connecting the first expansion protective piece to the side of the adapter tab facing away from the battery cell tab, so that the first expansion protective piece expands after being infiltrated by the electrolyte, thereby reducing or eliminating the gap between the battery cell and the outer shell in its height direction, thereby preventing the battery cell from vibrating due to the gap during subsequent use. In addition, the projection of the first expansion protective piece in the welding area covers the weld mark, so that the first expansion protective piece can also have the function of protecting the weld mark, thereby preventing residues, wire drawing or protrusions on the surface of the weld mark from falling into the charged battery cell.

[0052] The specific implementation of the battery provided in the embodiments of the present application is described in detail below with reference to the accompanying drawings.

[0053] Reference Figures 1 to 12As shown, the battery provided in the embodiment of the present application includes a shell 100, a battery cell 200, a battery cell tab 300, a adapter tab 400 and an expansion protection member 500, the battery cell 200, the battery cell tab 300 and the expansion protection member 500 are all located in the shell 100, the battery cell tab 300 is connected to the battery cell 200, and the overlapping portion of the adapter tab 400 and the battery cell tab 300 is welded and connected to form a welding area 600 at the overlapping portion of the adapter tab 400 and the battery cell tab 300, and the welding area 600 includes at least one weld mark 610.

[0054] The expansion protection piece 500 includes a first expansion protection piece 510, which is connected to the side of the battery cell tab 300 facing away from the adapter tab 400, or the first expansion protection piece 510 is connected to the side of the adapter tab 400 facing away from the battery cell tab 300, and the projection of the first expansion protection piece 510 in the welding area 600 at least partially overlaps with the weld mark 610.

[0055] It can be understood that the battery cell 200 is used to react with the electrolyte to generate current, the battery cell tab 300 is used to extract the current of the battery cell 200, and the adapter tab 400 is connected to the battery cell tab 300, thereby extracting the current out of the housing 100 to supply it to the device to be powered.

[0056] Among them, the battery cell 200 may include a pole piece, the pole piece may include a current collector and an active material layer, the battery cell tab 300 may be integrally formed with the current collector, or the battery cell tab 300 may also be welded to the current collector, which is not limited in the embodiment of the present application.

[0057] In the present application, the adapter tab 400 and the battery cell tab 300 can be connected by laser welding, that is, the adapter tab 400 and the battery cell tab 300 are first overlapped to form a welding area 600, and then the laser beam is irradiated on the adapter tab 400 or the battery cell tab 300 located in the welding area 600. The laser heat melts the metal in the two, and then the adapter tab 400 and the battery cell tab 300 are connected together. After welding, a plurality of weld marks 610 will be formed in the welding area 600, and there will be residues such as residues, wire drawing or protrusions on the surface of the weld mark 610. In order to prevent the residue from falling into the battery cell 200, the projection of the first expansion protective component 510 in the welding area 600 can cover part or all of the weld mark 610, and then the weld mark 610 and the battery cell 200 can be isolated by the first expansion protective component 510, thereby protecting the battery cell 200 from the influence of the residue.

[0058] It should be noted that the use of the rolling groove sealing process in the prior art to package the battery will occupy more space in the battery, thereby affecting the battery volume and energy density. The sealing process occupies less space in the battery, thereby reducing the battery volume and increasing the battery energy density. However, the sealing process lacks the limitation of the battery cell 200 in the height direction, thereby causing the battery cell 200 to vibrate during use, thereby causing the active material in the active material layer to fall off, thereby reducing the active material content of the electrode, thereby affecting the performance of the battery.

[0059] The height direction of the battery cell 200 described in the above embodiment is the axial direction of the wound battery cell 200 .

[0060] When the battery is a cylindrical battery, the battery cell 200 is cylindrical, the battery cell tab 300 and the adapter tab 400 are located at the end of the battery cell 200, and a first expansion protective piece 510 can be provided on the side of the adapter tab 400 facing away from the battery cell tab 300. After the first expansion protective piece 510 is infiltrated by the electrolyte, the first expansion piece will expand along its own thickness direction, thereby making the first expansion piece thicker, thereby reducing or even eliminating the gap between the end of the battery cell 200 and the outer shell 100, thereby reducing the possibility of vibration of the battery cell 200 during subsequent use.

[0061] When the battery is a square battery, the battery shell 100 is square, and the battery cell can adopt a wound battery cell 200 or a stacked battery cell 200. For example, when the square battery adopts a wound battery cell 200, the wound battery cell 200 has an arc area and a straight area, and the battery cell tab 300 and the adapter tab 400 are located on one side of the height direction of the battery cell 200. The side of the battery cell tab 300 facing away from the adapter tab 400 is provided with a first expansion protective member 510. After the first expansion protective member 510 is infiltrated by the electrolyte, the first expansion protective member 510 will expand along its own thickness direction, thereby reducing or even eliminating the gap between the side of the battery cell 200 and the shell 100, thereby reducing the possibility of vibration of the battery cell 200 during subsequent use.

[0062] The battery provided in the embodiment of the present application includes a housing 100, a battery cell 200, a battery cell tab 300, a transfer tab 400 and an expansion protection member 500. A welding area 600 is provided between the battery cell tab 300 and the transfer tab 400. The welding area 600 includes a welding mark 610. The expansion protection member 500 includes a first expansion protection member 510. The first expansion protection member 510 can be provided on a side of the transfer tab 400 away from the battery cell tab 300, or the first expansion protection member 510 can be provided on a side of the battery cell tab 300 away from the transfer tab 400, so that the first expansion protection member 510 expands along its own thickness direction after being infiltrated by the electrolyte to increase its own thickness, thereby reducing or eliminating the gap between the battery cell 200 and the housing 100, thereby reducing the possibility of vibration of the battery cell 200 during subsequent use. At the same time, the projection of the first expansion protection member 510 on the welding area 600 covers the weld mark 610 to isolate the weld mark 610 and the battery cell 200 , thereby preventing the residue of the weld mark 610 from falling into the battery cell 200 , thereby protecting the battery cell 200 .

[0063] Reference Figure 2 , Figure 3 and Figure 6 As shown, in a possible implementation, the battery provided in the present application also includes a plastic part 700, the battery cell 200 is cylindrical, the plastic part 700 is located between the adapter tab 400 and the inner wall of the outer shell 100, and the first expansion protection part 510 is located between the adapter tab 400 and the plastic part 700.

[0064] That is to say, in a cylindrical battery, in order to assemble the battery cell 200 and the adapter tab 400 and to normally realize the charging and discharging functions of the battery, a plastic part 700 is provided at one end of the battery where the pole 800 is provided. The plastic part 700 can be used to insulate and isolate the adapter tab 400 and the outer shell 100. Since the deformation degree of the plastic part 700 is reduced, when encountering a large assembly tolerance, there is still a gap between the plastic part 700 and the outer shell 100 or between the adapter tab 400 and the plastic part 700, and the first expansion protection part 510 is provided between the adapter tab 400 and the plastic part 700. When the first expansion protection part 510 expands, its thickness increases, and the opposite sides of the first expansion protection part 510 respectively exert an extrusion force on the adapter tab 400 and the plastic part 700, so that there is no gap between any two of the adapter tab 400, the first expansion protection part 510, the plastic part 700 and the outer shell 100.

[0065] Reference Figure 2 , Figure 3 and Figure 6As shown, in a possible implementation, the expansion protection member 500 also includes a second expansion protection member 520, and the second expansion protection member 520 includes a first connection part 521 and a second connection part 522 connected to each other, the first connection part 521 is connected to the outer peripheral wall of the battery cell 200, and the second connection part 522 is connected to the end face of the battery cell 200.

[0066] It should be noted that along the radial direction of the cylindrical battery cell 200, there is no battery cell tab 300 at the outermost and innermost sides of the battery cell 200, and the adapter tab 400 does not contact the outermost side of the battery cell 200. In order to protect the outermost side of the battery cell 200, the second expansion protection member 520 can be set to two parts, namely a first connection part 521 and a second connection part 522. The first connection part 521 is connected to the outer peripheral wall of the battery cell 200, so that after the first connection part 521 expands, the gap between the side wall of the battery cell 200 and the outer shell 100 is reduced or eliminated. The second connection part 522 is connected to the end face of the battery cell 200 to protect the outer part of the end face of the battery cell 200, and the projection of the second connection part 522 on the end face of the battery cell 200 is adjacent to or spaced from the projection of the first expansion protection member 510 on the end face of the battery cell 200.

[0067] Reference Figures 13 to 16 As shown, in a specific implementation, a plurality of cutouts 5211 can be arranged at intervals on the first connection portion 521 along the circumference of the battery cell 200 to avoid accumulation of the first connection portion 521 after being bonded to the outer wall of the battery cell 200, and the ratio of the area of ​​the cutout 5211 to the area of ​​the first connection portion 521 should be greater than or equal to 0.5 and less than or equal to 100.

[0068] When the outer diameter of the battery cell 200 is large, the cutout 5211 can be set smaller. When the outer diameter of the battery cell 200 is small, the cutout 5211 can be appropriately set larger, so as to prevent the expansion protection member 500 from wrinkling when it is bonded to the side wall of the battery cell 200.

[0069] When the cutout 5211 extends to the second connection portion 522 , after the second expansion protection member 520 is bonded to the side wall of the battery cell 200 and the adapter tab 400 , the second connection portions 522 on both sides of the cutout 5211 should be adjacent to or overlap each other to prevent the adapter tab 400 from being exposed.

[0070] In some embodiments, the first connection portion 521 extends along the axial direction of the battery cell 200 by a length greater than or equal to 1 mm and less than or equal to 20 mm. In this way, the first connection portion 521 can have a sufficient height to protect the side wall of the battery cell 200 to prevent the battery cell 200 from moving relative to the housing 110 in its radial direction.

[0071] Reference Fig. 9 and 10As shown, in a possible implementation, the battery cell 200 includes adjacent straight areas and arc areas, and the first expansion protection member 510 is located between the battery cell tab 300 and the battery cell 200. Alternatively, the first expansion protection member 510 is located between the battery cell tab 300 and the housing 100.

[0072] That is to say, for square batteries, the first expansion protective member 510 is arranged on the side of the battery cell tab 300 away from the adapter tab 400. For some square batteries, the first expansion protective member 510 can be pasted on the battery cell tab 300, and when the battery cell tab 300 is bent toward the battery cell 200, the first expansion protective member 510 is located between the battery cell tab 300 and the battery cell 200, and then the battery cell tab 300 is welded to the adapter tab 400.

[0073] For other square batteries, after the battery cell tab 300 and the adapter tab 400 are welded, the first expansion protective member 510 can be pasted on the battery cell tab 300, and after the battery cell tab 300 is bent toward the battery cell 200, the first expansion protective member 510 is located between the battery cell tab 300 and the outer shell 100.

[0074] Reference Figure 4 As shown, in some embodiments, the first expansion protection member 510 and the second expansion protection member 520 are integrally formed, or, referring to Figure 7 As shown, in some embodiments, the first expansion protection member 510 and the second expansion protection member 520 are provided separately.

[0075] The integral molding of the first expansion protection piece 510 and the second expansion protection piece 520 is conducive to simplifying processing and assembly, while the separate arrangement of the first expansion protection piece 510 and the second expansion protection piece 520 can be flexibly arranged according to the position of the weld mark 610. In specific implementation, the integrated or split type can be selected according to the setting requirements of different batteries.

[0076] Reference Fig.17 As shown, in some embodiments, the expansion protection member 500 includes a substrate layer 530, an adhesive layer 540 and an expansion layer 550, the two opposite sides of the expansion layer 550 are connected to the adhesive layer 540, at least one side of the substrate layer 530 is connected to the adhesive layer 540, and the substrate layer 530 and the expansion layer 550 are connected by the adhesive layer 540.

[0077] In this way, the expansion protection member 500 can be bonded to the welding area 600 or the battery cell 200 through the adhesive layer 540. The expansion layer 550 is used to absorb the electrolyte to expand and thicken, and the substrate layer 530 is used to improve the strength of the expansion protection member 500. It should be noted that the expansion layer 550 can be provided with one layer or more than two layers, and the thickness of each expansion layer 550 can be consistent or inconsistent.

[0078] For example, when the expansion layer 550 is a single layer, the substrate layer 530, the adhesive layer 540, the expansion layer 550 and the adhesive layer 540 are stacked in sequence, or the adhesive layer 540, the substrate layer 530, the adhesive layer 540, the expansion layer 550 and the adhesive layer 540 are stacked in sequence; when the expansion layer 550 is two layers, the substrate layer 530, the adhesive layer 540, the expansion layer 550, the adhesive layer 540, the expansion layer 550 and the adhesive layer 540 are stacked in sequence; the adhesive layer 540, the substrate layer 530, the adhesive layer 540, the expansion layer 550, the adhesive layer 540, the expansion layer 550 and the adhesive layer 540 are stacked in sequence.

[0079] That is to say, the adhesive layer 540 can be set on the side of the substrate layer 530 facing the expansion layer 550 to connect the substrate layer 530 and the expansion layer 550 through the adhesive layer 540. The adhesive layer 540 can also be set on the opposite sides of the substrate layer 530 so that the opposite sides of the expansion protection member 500 have adhesion.

[0080] In a possible implementation, the expansion layer 550 has pores, and the porosity of the pores is greater than or equal to 10% and less than or equal to 90%. In this way, the pores can be used to store part of the electrolyte, provide space for the electrolyte to infiltrate, thereby realizing the expansion function of the first expansion protection member 510, and the pores can store more electrolyte, thereby improving the cycle life of the battery.

[0081] In a possible implementation, the material of the substrate layer 530 includes at least one of polyethylene terephthalate, polypropylene and polyimide, and the material of the expansion layer 550 includes at least one of oriented polystyrene film, biaxially oriented polypropylene film, biaxially oriented nylon film and biaxially oriented polyester film.

[0082] Thus, by using oriented polystyrene film, biaxially oriented polypropylene film, biaxially oriented nylon film and biaxially oriented polyester film as the material of the expansion layer 550, and then treating it with a pore-forming agent such as sodium bicarbonate, the expansion layer 550 can form uniformly distributed gaps, thereby making the expansion protection member 500 have a higher expansion rate. By using polyethylene terephthalate, polypropylene and polyimide as the substrate layer 530, the strength of the expansion protection member 500 can be improved, thereby making the substrate layer 530 less likely to deform when being infiltrated by the electrolyte, that is, the substrate layer 530 will not expand along its thickness direction, while the expansion layer 550 will expand along its thickness direction.

[0083] It is understood that the substrate layer 530 may be formed of one of ethylene terephthalate, polypropylene and polyimide, or a composite of two or three of ethylene terephthalate, polypropylene and polyimide. The expansion layer 550 may be formed of one of oriented polystyrene film, biaxially stretched polypropylene film, biaxially stretched nylon film and biaxially stretched polyester film, or a composite of two or more of oriented polystyrene film, biaxially stretched polypropylene film, biaxially stretched nylon film and biaxially stretched polyester film.

[0084] In a possible implementation, the thickness of the expansion protection member 500 is greater than or equal to 0.02 mm and less than or equal to 10 mm. For example, the thickness of the expansion protection member 500 before expansion is greater than or equal to 0.02 mm and less than or equal to 2 mm. The thickness of the expansion protection member 500 after expansion is greater than or less than 0.1 mm and less than or equal to 10 mm.

[0085] Therefore, when assembling the expansion protective member 500, the thickness of the expansion protective member 500 is relatively small and will not affect the normal assembly of the battery. After injecting the electrolyte and packaging, the thickness of the expansion protective member 500 soaked in the electrolyte increases to 0.1 mm to 10 mm, which can effectively reduce or eliminate the gap between the battery cell 200 and the outer shell 100.

[0086] In some embodiments, a ratio of the thickness of the first expansion protection member 510 to the thickness of the second expansion protection member 520 is greater than or equal to 1 and less than or equal to 10.

[0087] Since the first expansion protective member 510 is arranged between the adapter tab 400 and the plastic member 700, the thickness direction of the first expansion protective member 510 is consistent with the height direction of the battery. When the thickness of the first expansion protective member 510 is greater than the thickness of the second expansion protective member 520, and the ratio of the thickness of the first expansion protective member 510 to the thickness of the second expansion protective member 520 is between 1 and 10, the first expansion protective member 510 can better compensate for the tolerance of the height direction of the battery, so that the first expansion protective member 510 has a better limiting effect on the battery cell 200.

[0088] Alternatively, in other embodiments, the ratio of the thickness of the second expansion protection member 520 to the thickness of the first expansion protection member 510 is greater than 1 and less than or equal to 10, so that the first expansion protection member 510 can store more electrolyte.

[0089] Reference Figure 4 , Figure 7 and Figure 8As shown, in a possible implementation, the adapter tab 400 includes a first bus plate 410, the housing 100 includes a shell 110 and a shell cover 120, the shell cover 120 is connected to one end of the shell 110, the first bus plate 410 is connected to one end of the battery cell 200 away from the shell cover 120, and the thickness of the first expansion protection member 510 gradually decreases from the center of the battery cell 200 to the outside of the battery cell 200.

[0090] It can be understood that the cylindrical battery cell 200 adopts a full-ear approach, and the battery cell ear 300 is integrally formed with the current collector. After the current collector is wound, the battery cell ear 300 is located at the end of the battery cell 200. The battery cell ear 300 needs to be bent toward the battery cell 200 from the outside to the inside to form a circle of battery cell ears 300. The outer battery cell ear 300 will be higher than the inner battery cell ear 300. The first expansion protective member 510 with uniform thickness cannot effectively eliminate the gap between the battery cell 200 and the outer shell 100. Therefore, the thickness of the first expansion protective member 510 of the embodiment of the present application can be gradually reduced from the center of the battery cell 200 to the outside of the battery cell 200, so that the thickness of the inner side of the first expansion protective member 510 is larger, and the thickness of the outer side of the first expansion protective member 510 is smaller, thereby complementing the height of the battery cell ear 300.

[0091] It should be noted that the adapter tab 400 may further include a second busbar 420 disposed between the shell cover 120 and the housing 110. The battery may further include a pole 800, which is sleeved on the first busbar 410 and extends outside the housing 100.

[0092] In a possible implementation, a ratio of a thickness of the first expansion protection member 510 at a side away from the center of the battery cell 200 to a thickness of the first expansion protection member 510 at a side close to the center of the battery cell 200 is greater than or equal to 1 / 5 and less than 1.

[0093] Such a configuration can make the thickness variation of the first expansion protection member 510 conform to the height variation of the battery cell tab 300 , and can make the thickness of the first expansion protection member 510 gradually decrease from the center of the battery cell 200 to the outside of the battery cell 200 , thereby complementing the height of the battery cell tab 300 .

[0094] Reference Fig.11 and Fig.12 As shown, in some embodiments, the ratio of the area of ​​the welding zone 600 to the projected area of ​​the first expansion protection member 510 on the welding zone 600 is greater than or equal to 1 and less than or equal to 5.

[0095] That is to say, the first expansion protective piece 510 should cover part of the weld mark 610 in the welding area 600, or cover the entire weld mark 610. Setting the area of ​​the welding area 600 to 1 to 5 times the projection area of ​​the first expansion protective piece 510 in the welding area 600 can increase the overlapping area between the first expansion protective piece 510 and the weld mark 610, thereby enabling the first expansion protective piece 510 to effectively prevent the residue of the weld mark 610 from falling into the battery cell 200.

[0096] In addition, in the cylindrical battery cell 200 , the ratio of the contact area between the transfer tab 400 and the end surface of the battery cell 200 to the projected area of ​​the first expansion protection member 510 in the welding area 600 is greater than 0 or equal to 0.1 and less than or equal to 1.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery, characterized in that: It comprises a shell, a battery cell, a battery cell tab, a transfer tab and an expansion protection member, wherein the battery cell, the battery cell tab and the expansion protection member are all located in the shell, the battery cell tab is connected to the battery cell, and the overlapping portion of the transfer tab and the battery cell tab is welded to form a welding area at the overlapping portion of the transfer tab and the battery cell tab, and the welding area comprises at least one weld mark; The expansion protective piece includes a first expansion protective piece, which is connected to a side of the battery cell tab away from the adapter tab, or the first expansion protective piece is connected to a side of the adapter tab away from the battery cell tab, and a projection of the first expansion protective piece in the welding area at least partially overlaps with the weld mark.

2. The battery according to claim 1, characterized in that It also includes a plastic part, the battery core is cylindrical, the plastic part is located between the adapter lug and the inner wall of the shell, and the first expansion protection part is located between the adapter lug and the plastic part.

3. The battery according to claim 2, characterized in that It also includes a second expansion protection member, which includes a first connection portion and a second connection portion connected to each other, the first connection portion is connected to the outer peripheral wall of the battery core, and the second connection portion is connected to the end surface of the battery core.

4. The battery according to claim 3, characterized in that The extension length of the first connecting portion along the axial direction of the battery core is greater than or equal to 1 mm and less than or equal to 20 mm.

5. The battery according to claim 1, characterized in that The housing is square, and the first expansion protection member is located between the battery cell tab and the battery cell; Alternatively, the first expansion protection member is located between the battery cell tab and the housing.

6. The battery according to claim 3 or 4, characterized in that: The first expansion protection member and the second expansion protection member are integrally formed, or the first expansion protection member and the second expansion protection member are separately provided.

7. The battery according to any one of claims 1 to 5, characterized in that: The expansion protection member comprises a substrate layer, an adhesive layer and an expansion layer, the two opposite sides of the expansion layer are connected to the adhesive layer, at least one side of the substrate layer is connected to the adhesive layer, and the substrate layer and the expansion layer are connected via the adhesive layer.

8. The battery according to claim 7, characterized in that The expansion layer has pores, and the porosity of the pores is greater than or equal to 10% and less than or equal to 90%.

9. The battery according to claim 7, characterized in that The material of the substrate layer includes at least one of polyethylene terephthalate, polypropylene and polyimide, and the material of the expansion layer includes at least one of oriented polystyrene film, biaxially stretched polypropylene film, biaxially stretched nylon film and biaxially stretched polyester film.

10. The battery according to any one of claims 1 to 5, characterized in that: The thickness of the expansion protection member is greater than or equal to 0.02 mm and less than or equal to 10 mm.

11. The battery according to claim 3 or 4, characterized in that: The ratio of the thickness of the first expansion protection member to the thickness of the second expansion protection member is greater than or equal to 1 and less than or equal to 10; Alternatively, a ratio of a thickness of the second expansion protection member to a thickness of the first expansion protection member is greater than 1 and less than or equal to 10.

12. The battery according to any one of claims 2 to 4, characterized in that: The adapter tab includes a first busbar, the outer shell includes a shell and a shell cover, the shell cover is connected to one end of the shell, the first busbar is connected to one end of the battery cell away from the shell cover, and the thickness of the first expansion protection piece gradually decreases from the center of the battery cell to the outside of the battery cell.

13. The battery according to claim 12, characterized in that A ratio of a thickness of the first expansion protection member at a side away from the center of the battery cell to a thickness of the first expansion protection member at a side close to the center of the battery cell is greater than or equal to 1 / 5 and less than 1.

14. The battery according to any one of claims 2 to 4, characterized in that: The ratio of the area of ​​the welding zone to the projection area of ​​the first expansion protection member on the welding zone is greater than or equal to 1 and less than or equal to 5.

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