Battery

Abstract

The utility model provides a battery, the battery comprises a battery cell, a battery cell tab and an adapter tab, the battery cell comprises a pole piece, the battery cell tab is connected to the pole piece, a metal layer is arranged between the battery cell tab and the adapter tab, and the battery cell tab and the adapter tab are welded and connected through the metal layer; the ratio of the melting point of the battery cell tab to the melting point of the metal layer is greater than or equal to 3 and less than or equal to 12; and / or the ratio of the melting point of the transfer tab to the melting point of the metal layer is greater than or equal to 3 and less than or equal to 12. According to the battery provided by the invention, the welding performance of the battery cell tabs and the switching tabs is relatively good.

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] However, when welding the soft pole ear and the hard pole ear, if the welding energy is low, the input will cause a cold weld and the soft pole ear and the hard pole ear cannot be completely connected. If the welding energy input is high, the soft pole ear will be welded cracked. 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 includes a battery cell, a battery cell tab and a transfer tab, the battery cell includes a pole piece, the battery cell tab is connected to the pole piece, and a metal layer is provided between the battery cell tab and the transfer tab, so that the battery cell tab and the transfer tab are welded and connected through the metal layer;

[0006] The ratio of the melting point of the battery cell tab to the melting point of the metal layer is greater than or equal to 3 and less than or equal to 12; and / or the ratio of the melting point of the transfer tab to the melting point of the metal layer is greater than or equal to 3 and less than or equal to 12.

[0007] In a possible implementation, the battery cell tabs and the adapter tabs are made of the same material.

[0008] In a possible implementation, the battery cell further includes a diaphragm, and a ratio of a melting point of the diaphragm to a melting point of the metal layer is greater than or equal to 1 / 3 and less than or equal to 3.

[0009] In a possible implementation, the thickness of the metal layer is greater than or equal to 10 μm and less than or equal to 1 mm.

[0010] In one possible implementation, the metal layer is connected to at least one side of the battery cell tab, and along the width direction of the electrode sheet, the ratio of the extended length of the metal layer to the extended length of the battery cell tab is greater than or equal to 1 / 10 and less than or equal to 4 / 5.

[0011] In a possible implementation, the pole piece includes a current collector and an active material layer coated on the surface of the current collector, the battery cell tab is connected to the current collector, and there is a gap between the metal layer and the active material layer along the width direction of the pole piece.

[0012] In a possible implementation, the gap is greater than 0 and less than or equal to 3 mm.

[0013] In a possible implementation, it also includes a shell, which is square in shape, and the pole pieces are wound to form a battery cell. The battery cell has multiple winding layers, and the winding layers include arc segments and straight segments. The battery cell pole ears are arranged corresponding to the straight segments, and the multiple battery cell pole ears are stacked along their own thickness direction, and there is a metal layer between at least two adjacent battery cell pole ears.

[0014] In a possible implementation, the pole piece is wound to form a cylindrical battery cell, and a plurality of battery cell tabs are arranged in sequence along the winding direction of the pole piece, and the battery cell tabs are bent toward the central axis of the battery cell;

[0015] Along the radial direction of the battery cell, at least two adjacent battery cell tabs overlap each other, and the metal layer is connected to at least one of the two adjacent battery cell tabs;

[0016] And / or, along the circumferential direction of the battery cell, there is a gap between two adjacent battery cell pole ears, and the metal layer is connected to at least one of the two adjacent battery cell pole ears;

[0017] And / or, along the circumferential direction of the battery cell, at least two adjacent battery cell pole ears overlap each other, and the metal layer is connected to non-overlapping portions of the two adjacent battery cell pole ears.

[0018] In a possible implementation, the metal layer is located on a side of the transfer tab facing away from the battery cell.

[0019] In a possible implementation, a welding area is formed at a location where the cell tab and the transfer tab overlap each other, and the welding area includes at least one welding mark, and the metal layer is arranged around the outer periphery of the welding mark;

[0020] The projection area of ​​the metal layer on the welding area is less than or equal to the area of ​​the welding area, and the projection area of ​​the weld mark on the welding area is less than or equal to the area of ​​the welding area;

[0021] The ratio of the projected area of ​​the metal layer on the welding zone to the projected area of ​​the welding mark on the welding zone is greater than or equal to 0.5 and less than or equal to 10.

[0022] In a possible implementation, the cell tab includes a first cell tab and a second cell tab with opposite polarities, the adapter tab includes a first adapter tab and a second adapter tab with opposite polarities, the metal layer includes a first metal layer and a second metal layer, the first cell tab is welded to the first adapter tab through the first metal layer, and the second cell tab is welded to the second adapter tab through the second metal layer;

[0023] The melting point of the first metal layer is greater than or equal to 100° C. and less than or equal to 700° C., and the melting point of the second metal layer is greater than or equal to 100° C. and less than or equal to 1100° C.

[0024] In one possible implementation, the metal layer includes an alloy solder, the mass ratio of the alloy solder in the metal layer is greater than or equal to 80% and less than or equal to 100%, wherein the alloy solder includes at least one of tin, lead, aluminum, silver, copper and bismuth.

[0025] The battery provided in the present application includes a battery cell, a battery cell tab, a transfer tab and a metal layer, and the battery cell includes a pole piece. By setting a pole piece for reacting with an electrolyte to generate current, by setting a cell pole ear for pole piece connection to lead out the current of the pole piece, by setting a transfer pole ear for connecting the cell pole ear to lead out the current from the battery, by setting a metal layer for welding and connecting the cell pole ear and the transfer pole ear, by setting the ratio of the melting point of the cell pole ear to the melting point of the metal layer between 3 and 12, and by setting the ratio of the melting point of the transfer pole ear to the melting point of the metal layer between 3 and 12, so that the welding temperature reaches the melting point of the metal layer through a lower heat input, and then the metal layer is fully melted, so that the metal layer is effectively connected to the cell pole ear and the transfer pole ear after cooling, thereby improving the welding strength between the cell pole ear and the transfer pole ear, while avoiding the problem of welding cracks of the cell pole ear or the transfer pole ear caused by excessive heat input, thereby avoiding the failure of the active material on the pole piece, and avoiding the heat shrinkage of the diaphragm and the inability to normally isolate the positive pole piece and the negative pole piece. Therefore, the welding performance of the cell pole ear and the transfer pole ear in the battery of the present application is good.

[0026] 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

[0027] 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.

[0028] Figure 1 Schematic diagram of the structure of the battery provided in the embodiment of the present application Figure 1 ;

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

[0030] Figure 3 A schematic diagram of the structure of the battery cell tab and the metal layer in the battery provided in the embodiment of the present application;

[0031] Figure 4 Schematic diagram of the structure of the battery cell tab, the transfer tab and the metal layer in the battery provided in the embodiment of the present application Figure 1 ;

[0032] Figure 5 A schematic diagram of the structure of the pole piece, the battery cell pole ear and the metal layer in the battery provided in the embodiment of the present application;

[0033] Figure 6 Schematic diagram of the structure of the pole piece and metal layer in the battery provided in the embodiment of the present application Figure 1 ;

[0034] Figure 7 Schematic diagram of the structure of the pole piece and metal layer in the battery provided in the embodiment of the present application Figure 2 ;

[0035] Figure 8 Schematic diagram of the structure of the pole piece and metal layer in the battery provided in the embodiment of the present application Figure 3 ;

[0036] Fig. 9 Schematic diagram of the structure of the pole piece and metal layer in the battery provided in the embodiment of the present application Figure 4 ;

[0037] Fig.10 Schematic diagram of the structure of the welding area and metal layer in the battery provided in the embodiment of the present application Figure 1 ;

[0038] Fig.11 Schematic diagram of the structure of the welding area and metal layer in the battery provided in the embodiment of the present application Figure 2 ;

[0039] Fig.12Schematic diagram of the structure of the battery cell tab, the transfer tab and the metal layer in the battery provided in the embodiment of the present application Figure 2 ;

[0040] Fig.13 Schematic diagram of the structure of the battery cell tab, the transfer tab and the metal layer in the battery provided in the embodiment of the present application Figure 3 ;

[0041] Fig.14 Schematic diagram of the structure of the battery cell tab, the transfer tab and the metal layer in the battery provided in the embodiment of the present application Figure 4 .

[0042] Description of reference numerals:

[0043] 100-battery cell; 110-pole piece; 200-battery cell tab; 210-notch; 300-transfer tab; 400-metal layer; 500-welding area; 510-weld mark. 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] However, when welding the soft pole ear and the hard pole ear, if the welding energy is low, the input will cause a cold weld and the soft pole ear and the hard pole ear cannot be completely connected. If the welding energy input is high, the soft pole ear will be welded cracked.

[0051] In view of this, an embodiment of the present application provides a battery, which connects the cell tab and the adapter tab by setting a metal layer between the cell tab and the adapter tab through welding of the metal layer, and the ratio of the melting point of the cell tab to the melting point of the metal layer is greater than or equal to 3 and less than or equal to 12, and the ratio of the melting point of the adapter tab to the melting point of the metal layer is greater than or equal to 3 and less than or equal to 12, so that the metal layer can achieve higher welding strength through lower welding heat, thereby solving the problems of cold welding and welding cracks in the related technology.

[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 4As shown, the battery provided in the present application includes a battery cell 100, a battery cell tab 200 and a transition tab 300, the battery cell 100 includes a pole piece 110, the battery cell tab 200 is connected to the pole piece 110, and a metal layer 400 is provided between the battery cell tab 200 and the transition tab 300 so that the battery cell tab 200 and the transition tab 300 are welded and connected through the metal layer 400.

[0054] The ratio of the melting point of the cell tab 200 to the melting point of the metal layer 400 is greater than or equal to 3 and less than or equal to 12, and / or the ratio of the melting point of the transfer tab 300 to the melting point of the metal layer 400 is greater than or equal to 3 and less than or equal to 12.

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

[0056] Among them, the battery cell 100 may include a pole piece 110, the pole piece 110 may include a current collector and an active material layer, the battery cell tab 200 may be integrally formed with the current collector, or the battery cell tab 200 may also be welded to the current collector, which is not limited in the embodiments of the present application.

[0057] In the present application, the adapter tab 300 and the battery cell tab 200 can be welded by laser welding, ultrasonic welding, reflow soldering and electromagnetic induction heating, and a metal layer 400 is provided between the adapter tab 300 and the battery cell tab 200. When the welding heat is input and reaches the melting point of the metal layer 400, the metal layer 400 melts into liquid and flows around. After cooling, the adapter tab 300 and the battery cell tab 200 are welded together.

[0058] For example, in the related art, the soft pole ear and the hard pole ear are made of the same material. When the soft pole ear and the hard pole ear are laser welded, the heat input of laser welding needs to make the soft pole ear and the hard pole ear reach their own melting point before the soft pole ear and the hard pole ear can be melted. When the heat input of laser welding is low, the soft pole ear and the hard pole ear cannot be effectively melted, which leads to the inability to completely weld the two, thereby causing the problem of cold welding of the soft pole ear and the hard pole ear. When the heat input of laser welding is high, the welding temperature is high. Although the metal in the soft pole ear and the hard pole ear can be completely melted, in this case, the soft pole ear is easily cracked, which will produce more metal debris. After these metal debris fall into the battery cell 100, it will seriously affect the safety performance of the battery.

[0059] In the present application, since the ratio of the melting point of the cell tab 200 to the melting point of the metal layer 400 is greater than or equal to 3 and less than or equal to 12, and / or the ratio of the melting point of the transition tab 300 to the melting point of the metal layer 400 is greater than or equal to 3 and less than or equal to 12. In other words, since the melting points of the cell tab 200 and the transition tab 300 are at least three times the melting point of the metal layer 400, the temperature during welding only needs to reach the melting point of the metal layer 400, so that the metal layer 400 is completely melted and diffused to the surroundings, so as to expand the connection area between the cell tab 200 and the transition tab 300, and then effectively connect the cell tab 200 and the transition tab 300, thereby improving the connection strength between the cell tab 200 and the transition tab 300. The welding temperature at this time is lower than the melting point of the cell tab 200 and the melting point of the adapter tab 300 , so that the cell tab 200 and the adapter tab 300 will not melt, thereby avoiding the problem of the cell tab 200 or the adapter tab 300 being welded and cracked.

[0060] For example, the ratio of the melting point of the cell tab 200 to the melting point of the metal layer 400 may be any one of 3, 4, 5, 8, and 12, or may be within any two numerical ranges. And / or, the ratio of the melting point of the transfer tab 300 to the melting point of the metal layer 400 may be any one of 3, 6, 9, 10, and 12, or may be within any two numerical ranges.

[0061] The battery provided in the embodiment of the present application includes a battery cell 100, a battery cell tab 200, a transfer tab 300 and a metal layer 400. The battery cell 100 includes a pole piece 110. The pole piece 110 is provided to react with an electrolyte to generate current, the battery cell tab 200 is provided to be connected to the pole piece 110 to conduct the current of the pole piece 110, the transfer tab 300 is provided to connect the battery cell tab 200 to conduct the current out of the battery, the metal layer 400 is provided to weld and connect the battery cell tab 200 and the transfer tab 300, the ratio of the melting point of the battery cell tab 200 to the melting point of the metal layer 400 is set between 3 and 12, and the transfer tab The ratio of the melting point of the metal layer 400 to the melting point of the metal layer 400 is set between 3 and 12, so that the welding temperature reaches the melting point of the metal layer 400 through a relatively low heat input, and then the metal layer 400 is fully melted, so that the metal layer 400 is cooled and effectively connects the cell tab 200 and the adapter tab 300, thereby improving the welding strength between the cell tab 200 and the adapter tab 300, and avoiding the problem of welding cracks of the cell tab 200 or the adapter tab 300 caused by excessive heat input. Therefore, the welding performance of the cell tab 200 and the adapter tab 300 in the battery of the embodiment of the present application is good.

[0062] In a possible implementation, the cell tab 200 and the adapter tab 300 are made of the same material. That is, in the above configuration, since the cell tab 200 and the adapter tab 300 are made of the same material, the melting points of the two are the same, and the melting points of the cell tab 200 and the adapter tab 300 are 3 to 12 times the melting point of the metal layer 400, during welding, when the welding temperature reaches the melting point of the metal layer 400, the metal layer 400 begins to melt due to heat, and when the welding temperature reaches 3 times the melting point of the metal layer 400, the cell tab 200 and the adapter tab 300 begin to melt due to heat.

[0063] For example, when the polarity of the cell tab 200 is positive, the cell tab 200 can be made of aluminum foil, and correspondingly, the adapter tab 300 also uses aluminum foil. When the polarity of the cell tab 200 is negative, the cell tab 200 can be made of copper foil, and correspondingly, the adapter tab 300 also uses copper foil.

[0064] In a possible implementation, the battery cell 100 further includes a separator, and the ratio of the melting point of the separator to the melting point of the metal layer 400 is greater than or equal to 1 / 3 and less than or equal to 3.

[0065] It should be noted that, for batteries in which the cell tabs 200 are not in close contact with the diaphragm, the ratio of the melting point of the diaphragm to the melting point of the metal layer 400 can be set to be smaller, the ratio of the melting point of the diaphragm to the melting point of the metal layer 400 can be less than 1 or equal to 1, the ratio of the melting point of the diaphragm to the melting point of the metal layer 400 can be between 1 / 3 and 1, that is, the melting point of the diaphragm can be slightly lower than the melting point of the metal layer 400, so that even if the welding temperature reaches the melting point of the metal layer 400, the diaphragm will not be overheated and shrink.

[0066] For batteries in which the cell tab 200 is in close contact with the diaphragm, the ratio of the melting point of the diaphragm to the melting point of the metal layer 400 can be set to be larger, and the ratio of the melting point of the diaphragm to the melting point of the metal layer 400 can be greater than 1, and the ratio of the melting point of the diaphragm to the melting point of the metal layer 400 can be between 1 and 3, that is, the melting point of the diaphragm can be slightly higher than the melting point of the metal layer 400 to avoid overheating and shrinkage of the diaphragm, thereby avoiding causing a short circuit in the battery cell 100.

[0067] For example, the ratio of the melting point of the membrane to the melting point of the metal layer 400 may be any one of 1 / 3, 2 / 3, 1, 2, and 3, or may be within any two value ranges.

[0068] In some embodiments, the thickness of the metal layer 400 is greater than or equal to 10 μm and less than or equal to 1 mm.

[0069] It is understandable that if the thickness of the metal layer 400 is too thin, the connection strength between the battery cell tab 200 and the adapter tab 300 will be reduced, which is not conducive to connecting the battery cell tab 200 and the adapter tab 300. If the thickness of the metal layer 400 is too thick, the ineffective volume of the battery will be increased, thereby reducing the energy density of the battery. Therefore, setting the thickness of the metal layer 400 between 10μm and 1㎜ is a more appropriate range.

[0070] Exemplarily, the thickness of the metal layer 400 may be any one of 10 μm, 20 μm, 40 μm, 80 μm, and 1 mm, or may be within any two value ranges.

[0071] Reference Figures 3 to 5 As shown, in some embodiments, the metal layer 400 is connected to at least one side of the battery cell tab 200, and along the width direction of the electrode piece 110, the ratio of the extension length of the metal layer 400 to the extension length of the battery cell tab 200 is greater than or equal to 1 / 10 and less than or equal to 4 / 5.

[0072] In the specific setting, along the width direction of the pole piece 110, if the extension length of the metal layer 400 is too small, the effective area of ​​the metal layer 400 is small, and the metal layer 400 cannot effectively cover the battery cell tab 200 and the transition tab 300. Therefore, the ratio of the extension length of the metal layer 400 to the extension length of the battery cell tab 200 should be greater than or equal to 1 / 10. If the extension length of the metal layer 400 is too large, the metal layer 400 may extend to the current collector of the pole piece 110. In order to avoid this situation, the ratio of the extension length of the metal layer 400 to the extension length of the battery cell tab 200 is less than or equal to 4 / 5.

[0073] Exemplarily, the ratio of the extension length of the metal layer 400 to the extension length of the battery cell tab 200 is any one of 1 / 10, 1 / 5, 2 / 5, 3 / 5, and 4 / 5, or is within any two value ranges.

[0074] Reference Figure 5 As shown, in a possible implementation, the pole piece 110 includes a current collector and an active material layer coated on the surface of the current collector, the battery cell tab 200 is connected to the current collector, and there is a gap between the metal layer 400 and the active material layer along the width direction of the pole piece 110. The gap is greater than 0 and less than or equal to 3 mm.

[0075] In this way, there can be a gap between the metal layer 400 and the active material layer to avoid battery short circuit, and the area of ​​the metal layer 400 on the battery cell tab 200 can be effectively expanded, thereby making the connection area between the battery cell tab 200 and the adapter tab 300 larger, thereby improving the welding strength between the battery cell tab 200 and the adapter tab 300.

[0076] Reference Figures 6 to 9 As shown, the metal layer 400 can be formed together with the active material layer, that is, in the coating stage, a paste flow channel of the metal layer 400 is added to the coating grinding head, and coated together with the paste of the active material layer. The metal layer 400 can be continuously coated on both sides of the empty foil area, or continuously coated on one side of the empty foil area, or intermittently coated on one side of the empty foil area and the other side, and the metal layers 400 on both sides of the empty foil area are partially staggered or completely staggered. It should be understood that the above-mentioned several settings can be combined arbitrarily, and this embodiment is not limited to this.

[0077] Reference Figure 4 As shown, in a possible implementation, the battery may further include a shell, which is square in shape, and the pole piece 110 is wound to form a battery cell 100, the battery cell 100 has multiple winding layers, the winding layers include arc segments and straight segments, the battery cell tabs 200 are arranged corresponding to the straight segments, and multiple battery cell tabs 200 are stacked along their own thickness direction, and a metal layer 400 is provided between at least two adjacent battery cell tabs 200.

[0078] It should be understood that the battery cell tab 200 is connected to the side of the width direction of the electrode sheet 110. For square batteries, the battery cell 100 can be a stacked type or a wound type. For example, the battery cell 100 adopts a wound battery cell 100, and the electrode sheet 110 has multiple winding layers after winding. The straight section of each winding layer can be provided with a positive electrode battery cell tab 200 and a negative electrode battery cell tab 200. The battery cell tabs 200 of two adjacent winding layers can also be welded and connected by the metal layer 400. Thereafter, the battery cell tab 200 can also be welded and connected to the adapter tab 300 by the metal layer 400. In this embodiment, the metal layer 400 can be arranged not only between the battery cell tab 200 and the adapter tab 300, but also between adjacent battery cell tabs 200, that is, the metal layer 400 can be connected to one side or both sides of the battery cell tab 200.

[0079] Reference Figure 3 As shown, in a possible implementation, the pole piece 110 is wound to form a cylindrical battery cell 100 , a plurality of battery cell tabs 200 are arranged in sequence along the winding direction of the pole piece 110 , and the battery cell tabs 200 are bent toward the central axis of the battery cell 100 .

[0080] Along the radial direction of the battery cell 100, at least two adjacent battery cell tabs 200 overlap each other, and the metal layer 400 is connected to at least one of the two adjacent battery cell tabs 200. And / or, along the circumferential direction of the battery cell 100, there is a gap 210 between two adjacent battery cell tabs 200, and the metal layer 400 is connected to at least one of the two adjacent battery cell tabs 200. And / or, along the circumferential direction of the battery cell 100, at least two adjacent battery cell tabs 200 overlap each other, and the metal layer 400 is connected to the non-overlapping parts of the two adjacent battery cell tabs 200.

[0081] The shape of the notch 210 may be a triangle. For example, a part of the empty foil area is reserved on the side of the current collector, and the cell tab 200 is formed through a cutting process. During cutting, a triangular notch 210 may be formed between two adjacent cell tabs 200, and after the cell tab 200 is bent toward the central axis of the cell 100, the projection of the notch 210 on the end face of the cell 100 is still triangular.

[0082] It should be noted that, for a cylindrical battery, the cylindrical battery cell 100 adopts a full-ear approach, and the cell ear 200 is integrally formed with the current collector. After the current collector is wound, the cell ear 200 is located at the end of the battery cell 100, and the cell ear 200 needs to be bent from the outside to the inside toward the central axis of the battery cell 100 to form circles of cell ears 200, and along the radial direction of the battery cell 100, the outer cell ear 200 and the inner cell ear 200 can overlap with each other, and the metal layer 400 can be connected to one of the outer cell ear 200 and the inner cell ear 200. Since the bending radius on the outside is larger and the bending radius on the inside is smaller during winding, after the cylindrical battery cell 100 is formed, a gap 210 is provided between two adjacent battery cell tabs 200 on the outside along the circumferential direction of the battery cell 100, and the metal layer 400 is connected to one or both of the two adjacent battery cell tabs 200, so that the battery cell tab 200 is connected to the transition tab 300 through the metal layer 400, and the metal layer 400 flows along the radial and circumferential directions of the battery cell 100 when melted, and the two adjacent battery cell tabs 200 on the inside overlap with each other, and the metal layer 400 is connected to the non-overlapping parts of the two adjacent battery cell tabs 200, so that the battery cell tab 200 is connected to the transition tab 300 through the metal layer 400.

[0083] In some embodiments, the metal layer 400 is located on the side of the adapter tab 300 away from the battery cell 100. That is, whether it is the battery cell tab 200 located on the outside or the battery cell tab 200 located on the inside, the metal layer 400 is connected to the side of the adapter tab 300 away from the battery cell 100, so that the metal layer 400 can be prevented from flowing toward the battery cell 100 after melting, thereby preventing the battery cell 100 from short-circuiting.

[0084] Reference Fig.10 and Fig.11 As shown, in a possible implementation, the overlapping portion of the cell tab 200 and the transfer tab 300 forms a welding area 500 , and the welding area 500 includes at least one welding mark 510 , and the metal layer 400 is disposed around the outer peripheral side of the welding mark 510 .

[0085] The projection area of ​​the metal layer 400 on the welding area 500 is less than or equal to the area of ​​the welding area 500, and the projection area of ​​the weld mark 510 on the welding area 500 is less than or equal to the area of ​​the welding area 500. The ratio of the projection area of ​​the metal layer 400 on the welding area 500 to the projection area of ​​the weld mark 510 on the welding area 500 is greater than or equal to 0.5 and less than or equal to 10.

[0086] In the above-mentioned configuration, the metal layer 400 can be formed by spraying, and the metal layer 400 can be arranged around the outer peripheral side of the weld mark 510 and does not exceed the range of the welding area 500. The weld mark 510 is also located in the welding area 500 and does not exceed the range of the welding area 500. In order to ensure the connection area between the battery cell tab 200 and the transfer tab 300, the ratio of the projected area of ​​the metal layer 400 in the welding area 500 to the projected area of ​​the weld mark 510 in the welding area 500 should be between 0.5 and 10. For example, the ratio of the projected area of ​​the metal layer 400 in the welding area 500 to the projected area of ​​the weld mark 510 in the welding area 500 can be between 1 and 4, thereby ensuring the connection strength between the two.

[0087] In some embodiments, the metal layer 400 can be arranged around the weld mark 510, or, in other embodiments, the metal layer 400 completely overlaps with the welding area 500, that is, the metal layer 400 can cover the entire welding area 500, so that a larger current carrying capacity can be provided between the battery cell tab 200 and the transfer tab 300.

[0088] Exemplarily, the ratio of the projected area of ​​the metal layer 400 on the welding area 500 to the projected area of ​​the welding mark 510 on the welding area 500 may be any one of 0.5, 1, 4, 6, and 10, or be within any two value ranges.

[0089] In some embodiments, the battery cell tab 200 includes a first battery cell tab and a second battery cell tab with opposite polarities, the adapter tab 300 includes a first adapter tab and a second adapter tab with opposite polarities, the metal layer 400 includes a first metal layer and a second metal layer, the first battery cell tab is welded to the first adapter tab through the first metal layer, and the second battery cell tab is welded to the second adapter tab through the second metal layer.

[0090] The melting point of the first metal layer is greater than or equal to 50°C and less than or equal to 700°C, and the melting point of the second metal layer is greater than or equal to 50°C and less than or equal to 1100°C.

[0091] For example, the polarity of the first battery cell pole ear and the first adapter pole ear is positive, and the first battery cell pole ear and the first adapter pole ear are both made of aluminum foil, wherein the melting point of aluminum is 660.4°C. At this time, the melting point of the first metal layer can be between 50°C and 700°C, and the polarity of the second battery cell pole ear and the second adapter pole ear is negative, and the second battery cell pole ear and the second adapter pole ear are both made of copper foil, wherein the melting point of copper is 1083.4°C. At this time, the melting point of the second metal layer can be between 50°C and 1100°C, thereby satisfying that the ratio of the melting point of the core pole ear to the melting point of the metal layer 400 is between 3 and 12, and satisfying that the ratio of the melting point of the adapter pole ear 300 to the melting point of the metal layer 400 is between 3 and 12.

[0092] Exemplarily, the melting point of the first metal layer may be any one of 50° C., 100° C., 200° C., 320° C., 600° C., and 700° C., or within any two numerical ranges. The melting point of the second metal layer may be any one of 50° C., 100° C., 300° C., 450° C., 800° C., and 1100° C., or within any two numerical ranges.

[0093] In some embodiments, the metal layer 400 includes an alloy solder, the mass ratio of the alloy solder in the metal layer 400 is greater than or equal to 80% and less than or equal to 100%, wherein the alloy solder includes at least one of tin, lead, aluminum, silver, copper and bismuth.

[0094] In addition, the metal layer 400 may also include a soldering flux, which helps to increase the fluidity of the metal layer 400 when it is melted. During welding, part or all of the soldering flux is volatilized by heat, and the mass ratio of the alloy solder in the cooled metal layer 400 is between 80% and 100%, so that there is a sufficient volume of the metal layer 400 for connection between the battery cell tab 200 and the transfer tab 300. The soldering flux may include one or more of isopropyl alcohol, rosin and organic acid.

[0095] In a specific implementation, the melting point of the metal layer 400 can be adjusted by adjusting the ratio of tin, lead, aluminum, silver, copper and bismuth in the alloy solder so that the melting point of the metal layer 400 meets the requirements of the above embodiment, and the viscosity of the metal layer 400 can be 200 to 500 Pa*s.

[0096] It should be noted that when laser welding is used, the laser beam is irradiated on the adapter tab 300, and the heat of the laser beam is transferred along the adapter tab 300 to the metal layer 400 and the battery cell tab 200. When the temperature of the adapter tab 300 is greater than or equal to the melting point of the adapter tab 300 and the heat is conducted to the battery cell tab 200, the temperature of the battery cell tab 200 is greater than or equal to the melting point of the battery cell tab 200. At this time, the battery cell tab 200, the adapter tab 300 and the metal layer 400 will all melt, the battery cell tab 200 and the metal layer 400 will penetrate each other, the adapter tab 300 and the metal layer 400 will penetrate each other, and the metal layer 400 will flow along the circumference of the battery cell 100 into the notch 210. The interface between the battery cell tab 200 and the metal layer 400, and the interface between the adapter tab 300 and the metal layer 400 are as shown in FIG. Fig.12 shown.

[0097] When the temperature of the adapter tab 300 is greater than or equal to the melting point of the adapter tab 300 and the heat is conducted to the cell tab 200, the temperature of the cell tab 200 is less than or equal to the melting point of the cell tab 200. At this time, the adapter tab 300 and the metal layer 400 melt and penetrate each other, the cell tab 200 does not melt, and the metal layer 400 flows into the notch 210 along the circumference of the cell 100. The interface between the adapter tab 300 and the metal layer 400 is as shown in FIG. Fig.13 shown.

[0098] When the temperature of the adapter tab 300 is lower than the melting point of the adapter tab 300 and the heat is conducted to the cell tab 200, the temperature of the cell tab 200 is lower than the melting point of the cell tab 200. At this time, only the metal layer 400 melts, and neither the cell tab 200 nor the adapter tab 300 melts. The metal layer 400 flows into the notch 210 along the circumference of the cell 100. The interface between the adapter tab 300 and the metal layer 400 is as shown in FIG. Fig.14 shown.

[0099] It can be understood that the metal layer 400 melts, and the adapter tab 300 and the battery cell tab 200 do not melt, or the adapter tab 300 and the metal layer 400 melt, and the battery cell tab 200 does not melt. In these two methods, the battery cell tab 200 does not melt, and the problem of welding cracks of the battery cell tab 200 will not occur, thereby improving the current carrying capacity and safety performance of the battery cell tab 200.

[0100] When laser welding is used, there are high temperature areas and low temperature areas on both sides of the laser spot trajectory, wherein the width of the high temperature area can range from 0.3 to 3 mm. By properly arranging the laser spot trajectory, the high temperature areas of the two laser spot trajectories can overlap, thereby allowing the metal layer 400 to melt and cover the welding area 500.

[0101] When using welding methods such as reflow soldering and electromagnetic induction heating, the transfer tab 300, the cell tab 200, the metal layer 400 and the cell 100 can all be located in the high temperature zone. When the temperature of the high temperature zone reaches the melting point of the metal layer 400, the metal layer 400 can be melted, but the transfer tab 300, the cell tab 200 and the cell 100 will not melt. Alternatively, the ends of the transfer tab 300, the cell tab 200, the metal layer 400 and the cell 100 can all be located in the high temperature zone, and the middle of the cell 100 can be located in the low temperature zone.

[0102] 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: The invention comprises a battery cell, a battery cell tab and a transfer tab, wherein the battery cell comprises a pole piece, the battery cell tab is connected to the pole piece, and a metal layer is provided between the battery cell tab and the transfer tab, so that the battery cell tab and the transfer tab are welded and connected through the metal layer; The ratio of the melting point of the battery cell tab to the melting point of the metal layer is greater than or equal to 3 and less than or equal to 12; and / or the ratio of the melting point of the transfer tab to the melting point of the metal layer is greater than or equal to 3 and less than or equal to 12.

2. The battery according to claim 1, characterized in that The battery cell tab and the adapter tab are made of the same material.

3. The battery according to claim 1, characterized in that The battery core further includes a diaphragm, and a ratio of a melting point of the diaphragm to a melting point of the metal layer is greater than or equal to 1 / 3 and less than or equal to 3.

4. The battery according to claim 1, characterized in that The thickness of the metal layer is greater than or equal to 10 μm and less than or equal to 1 mm.

5. The battery according to claim 1, characterized in that The metal layer is connected to at least one side of the battery cell tab, and along the width direction of the pole piece, the ratio of the extension length of the metal layer to the extension length of the battery cell tab is greater than or equal to 1 / 10 and less than or equal to 4 / 5.

6. The battery according to claim 5, characterized in that The pole piece includes a current collector and an active material layer coated on the surface of the current collector. The battery cell tab is connected to the current collector. Along the width direction of the pole piece, there is a gap between the metal layer and the active material layer.

7. The battery according to claim 6, characterized in that The gap is greater than 0 and less than or equal to 3 mm.

8. The battery according to any one of claims 1 to 7, characterized in that: It also includes a shell, which is square in shape. The pole pieces are wound to form the battery core, and the battery core has multiple winding layers. The winding layers include arc segments and straight segments. The battery cell pole ears are arranged corresponding to the straight segments. Multiple battery cell pole ears are stacked along their own thickness direction, and the metal layer is provided between at least two adjacent battery cell pole ears.

9. The battery according to any one of claims 1 to 7, characterized in that: The pole piece is wound to form the cylindrical battery cell, and a plurality of the battery cell pole tabs are arranged in sequence along the winding direction of the pole piece, and the battery cell pole tabs are bent toward the central axis of the battery cell; Along the radial direction of the battery cell, at least two adjacent battery cell tabs overlap each other, and the metal layer is connected to at least one of the two adjacent battery cell tabs; And / or, along the circumferential direction of the battery core, there is a gap between two adjacent battery core tabs, and the metal layer is connected to at least one of the two adjacent battery core tabs; And / or, along the circumferential direction of the battery cell, at least two adjacent battery cell pole tabs overlap each other, and the metal layer is connected to non-overlapping portions of two adjacent battery cell pole tabs.

10. The battery according to claim 9, characterized in that The metal layer is located on a side of the transfer tab that is away from the battery core.

11. The battery according to claim 9, characterized in that The overlapping portion of the cell tab and the transfer tab forms a welding area, the welding area includes at least one welding mark, and the metal layer is arranged around the outer periphery of the welding mark; The projection area of ​​the metal layer on the welding area is smaller than or equal to the area of ​​the welding area, and the projection area of ​​the weld mark on the welding area is smaller than or equal to the area of ​​the welding area; The ratio of the projected area of ​​the metal layer in the welding area to the projected area of ​​the weld mark in the welding area is greater than or equal to 0.5 and less than or equal to 10.

12. The battery according to any one of claims 1 to 7, characterized in that: The cell tab comprises a first cell tab and a second cell tab with opposite polarities, the adapter tab comprises a first adapter tab and a second adapter tab with opposite polarities, the metal layer comprises a first metal layer and a second metal layer, the first cell tab is welded to the first adapter tab via the first metal layer, and the second cell tab is welded to the second adapter tab via the second metal layer; The melting point of the first metal layer is greater than or equal to 50°C and less than or equal to 700°C, and the melting point of the second metal layer is greater than or equal to 50°C and less than or equal to 1100°C.

13. The battery according to any one of claims 1 to 7, characterized in that: The metal layer includes alloy solder, the mass ratio of the alloy solder in the metal layer is greater than or equal to 80% and less than or equal to 100%, wherein the alloy solder includes at least one of tin, lead, aluminum, silver, copper and bismuth.

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