Single cell battery

Abstract

This application provides a single-cell battery, including an electrode assembly. The electrode assembly includes a main body and multiple first tabs and multiple second tabs extending from the main body. The multiple first tabs are stacked and connected to form a first welding area connected to a first electrode post. The multiple second tabs are stacked and connected to form a second welding area connected to a second electrode post. Multiple spaced-apart first recesses and second recesses are formed in the first and second welding areas. The material of the multiple first tabs includes a first metal, and the material of the multiple second tabs includes a second metal. The thickness of the multiple first tabs is greater than the thickness of the multiple second tabs, and the projected area of ​​each first recess in the stacking direction of the first tabs is greater than the projected area of ​​each second recess in the stacking direction of the second tabs. The above technical solution can at least reduce the risk of tab breakage.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a single-cell battery. Background Technology

[0002] In the field of new energy power batteries, secondary batteries refer to rechargeable batteries, also known as renewable batteries or accumulators. Unlike primary batteries, secondary batteries can undergo multiple charge-discharge cycles through reverse charging for reuse. A power battery consists of several individual battery cells, whose electrode assemblies typically have multiple tabs stacked and welded together. However, existing battery cells still require further improvement in certain aspects (such as tab welding). Utility Model Content

[0003] In view of the problems existing in the related technologies, the purpose of this application is to provide a single cell battery to at least reduce the risk of tab breakage.

[0004] To achieve the above objectives, this application provides a single-cell battery, comprising: a housing; a first electrode post and a second electrode post disposed on the housing; and an electrode assembly housed within the housing. The electrode assembly includes a main body and multiple first electrode tabs and multiple second electrode tabs extending from the main body. The multiple first electrode tabs and multiple second electrode tabs are spaced apart. The multiple first electrode tabs are stacked and connected to form a first welding area connected to the first electrode post, and the multiple second electrode tabs are stacked and connected to form a second welding area connected to the second electrode post. Multiple spaced first recesses are formed in the first welding area, and multiple spaced second recesses are formed in the second welding area. The material of the multiple first electrode tabs includes a first metal, the material of the multiple second electrode tabs includes a second metal, the thickness of the multiple first electrode tabs is greater than the thickness of the multiple second electrode tabs, and the projected area of ​​each first recess in the stacking direction of the first electrode tab is greater than the projected area of ​​each second recess in the stacking direction of the second electrode tab.

[0005] In some embodiments, the hardness of the first metal of the first electrode tab is less than the hardness of the second metal of the second electrode tab, and the thickness of the single-layer first electrode tab is greater than the thickness of the single-layer second electrode tab.

[0006] In some embodiments, the first electrode includes a first electrode body made of a first metal and a first metal oxide layer on the surface of the first electrode body, and the second electrode includes a second electrode body made of a second metal and a second metal oxide layer on the surface of the second electrode body, wherein the first metal oxide layer is denser or thicker than the second metal oxide layer.

[0007] In some embodiments, the second depth of each second recess is less than the first depth of each first recess.

[0008] In some embodiments, the first depth is greater than 50% of the thickness of the plurality of first tabs, and the second depth is greater than 50% of the thickness of the plurality of second tabs.

[0009] In some embodiments, the number of the plurality of first recesses is less than the number of the plurality of second recesses.

[0010] In some embodiments, each first electrode tab has a first top edge away from the body, and each second electrode tab has a second top edge away from the body. In the stacking direction of the first electrodes tabs, the plurality of first electrodes tabs include a bottom first electrode tab and a top first electrode tab, the first top edge of the top first electrode tab being closer to the body than the first top edge of the bottom first electrode tab. In the stacking direction of the second electrodes tabs, the plurality of second electrodes tabs include a bottom second electrode tab and a top second electrode tab, the second top edge of the top second electrode tab being closer to the body than the second top edge of the bottom second electrode tab. In the direction from the first top edge of the top first electrode tab to the first top edge of the bottom first electrode tab, a portion of the first welding area is located between the first top edge of the top first electrode tab and the first top edge of the bottom first electrode tab. In the direction from the second top edge of the top second electrode tab to the second top edge of the bottom second electrode tab, a portion of the second welding area is located between the second top edge of the top second electrode tab and the second top edge of the bottom second electrode tab.

[0011] In some embodiments, the projection of each first recess in the stacking direction of the first tab is circular, and the projection of each second recess in the stacking direction of the second tab is circular.

[0012] In some embodiments, a plurality of first recesses are arranged in one to four rows in the first welding area, with the first recesses in each row spaced apart in a direction parallel to the first top edge of the first electrode tab, and a plurality of second recesses are arranged in one to four rows in the second welding area, with the second recesses in each row spaced apart in a direction parallel to the second top edge of the second electrode tab.

[0013] In some embodiments, the first electrode is a positive electrode and the first metal is aluminum; the second electrode is a negative electrode and the second metal is copper.

[0014] The above technical solution, by forming a first recess with a large projected area in the first welding area of ​​the thicker first electrode tab, can reduce the risk of breakage of the first electrode tab and improve the yield by increasing the contact area; by forming a second recess with a smaller projected area in the second welding area of ​​the second electrode tab, it can avoid loss of conductive cross-sectional area due to excessive deformation of the second electrode tab. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of an electronic device for a vehicle according to an embodiment of this application.

[0017] Figure 2A A perspective view of a secondary battery according to an embodiment of this application is shown.

[0018] Figure 2B A cross-sectional schematic diagram of a secondary battery according to an embodiment of this application is shown.

[0019] Figure 2C yes Figure 2B A cross-sectional schematic diagram of the electrode assembly of the secondary battery.

[0020] Figure 2D yes Figure 2B A top view of the electrode assembly of the secondary battery.

[0021] Figure 3A and Figure 3B These are partial schematic diagrams of the first tab and the second tab of an electrode assembly according to an embodiment of this application.

[0022] Figure 4 This is a cross-sectional schematic diagram of the first recess of the first electrode tab and the second recess of the second electrode tab according to an embodiment of this application.

[0023] Figure 5A and Figure 5B These are partial schematic diagrams of the first tab and the second tab of an electrode assembly according to another embodiment of this application. Detailed Implementation

[0024] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0025] Embodiments of this application will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are indicated by similar reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative and diagrammatic in nature and are intended to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.

[0026] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate small variations, such as variations within the tolerance range of a manufacturing process. When used in conjunction with an event or situation, the terms may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately.

[0027] In this specification, unless otherwise specified or limited, relative terms such as “central,” “longitudinal,” “lateral,” “front,” “rear,” “right,” “left,” “inner,” “outer,” “lower,” “higher,” “horizontal,” “vertical,” “above,” “below,” “above,” “below,” “top,” “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to the directions described in the discussion or depicted in the accompanying drawings. These relative terms are used for descriptive convenience only and do not require that this application be constructed or operated in a particular orientation.

[0028] For ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0029] The electrode assembly of a single battery cell consists of multiple tabs stacked and welded together. Typically, the same welding equipment and process parameters are used to weld the positive and negative tabs. However, the positive and negative tabs differ in material and thickness, and existing welding methods easily lead to differences in welding strength between the positive and negative tabs and the adapter plates or terminals, or localized stress concentration, resulting in the tab foil breaking. To address this technical problem, this application provides a single-cell battery.

[0030] Single-cell batteries can be used, for example, in electronic devices, such as... Figure 1 In the electronic device 1000 shown. For ease of explanation, the following embodiments will use a vehicle as an example for the electronic device 1000. See also Figure 1The vehicle has a battery pack 1002 installed inside, which can be located at the bottom, front, or rear of the vehicle body 1001. The battery pack 1002 can be used to power the vehicle; for example, it can serve as the vehicle's operating power source. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain electrical power. The vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, but are not limited thereto. The working part is the vehicle body, and the battery pack 1002 is located at the bottom of the vehicle body, providing electrical power for the vehicle's movement or the operation of its internal electrical components. However, in some other embodiments, the electronic device 1000 can also be a mobile phone, portable device, laptop, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working part can obtain electrical energy from the battery pack 1002 and perform corresponding functions, such as a fan blade rotation unit or a vacuum cleaner's suction unit. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the aforementioned electronic device 1000.

[0031] In this application, the battery cell may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application are not limited to these. The battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited to these. Battery cells are generally divided into three types according to their packaging method: cylindrical battery cells, square battery cells, and pouch battery cells, and the embodiments of this application are not limited to these.

[0032] Figure 2A A perspective view of a secondary battery according to an embodiment of this application is shown. Figure 2B A cross-sectional schematic diagram of a secondary battery according to an embodiment of this application is shown. Figure 2C yes Figure 2B A cross-sectional schematic diagram of the electrode assembly of the secondary battery. Figure 2D yes Figure 2B A top view of the electrode assembly of the secondary battery.

[0033] Combination Figures 1 to 2DAs shown, the single-cell battery 100 may include a housing 200, which includes a peripheral sidewall 109 and an end wall 111 connected to one end of the peripheral sidewall 109. An opening 205 is provided at the other end of the peripheral sidewall 109 opposite to the end wall 111. A top cover assembly 220 covers the opening 205 of the housing 200 to define a receiving cavity together with the housing 200, in which the electrode assembly 120 is located.

[0034] The direction from end wall 111 towards top cover assembly 220 is the height direction Z of single cell 100. In this embodiment, two electrode assemblies 120 are stacked in housing 200 along the thickness direction of electrode assembly 120. In other embodiments, more than two electrode assemblies 120 may be provided in housing 200. Single cell 100 may be a cuboid as shown, or it may be a cylinder, flattened, or other shapes.

[0035] In some embodiments, the electrode assembly 120 is a wound body formed by winding a first electrode 201, a second electrode 202, and a separator 204 located between the first electrode 201 and the second electrode 202. In other embodiments, the electrode assembly 120 may also be a stacked body formed by sequentially stacking the first electrode 201, the second electrode 202, and the separator 204 located between the first electrode 201 and the second electrode 202. The electrode assembly 120 may be flat. In some embodiments, the first electrode 201 may be a positive electrode, and the second electrode 202 may be a negative electrode.

[0036] The positive electrode may include a positive current collector and a positive active material layer, the positive active material layer being coated on a portion of the surface of the positive current collector. The negative electrode may include a negative current collector and a negative active material layer, the negative active material layer being coated on a portion of the surface of the negative current collector. In some embodiments, such as in a lithium-ion battery, the material of the positive current collector may be aluminum. The positive active material layer may include a positive active material, such as lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. For high-nickel ternary lithium batteries, the positive active material may be a ternary material composed of nickel, cobalt, and manganese (or aluminum). The material of the negative current collector may be copper. The negative active material layer may include a negative active material, such as carbon or silicon. The separator material may be, for example, PP (polypropylene) or PE (polyethylene).

[0037] The electrode assembly 120 may have a main body 124, from which a first tab 121 and a second tab 122 extend in the Z direction. The first tabs 121 and the second tabs 122 may be spaced apart along the width direction of the electrode assembly. The main body 124 may be formed by winding a positive current collector and a positive active material layer of a positive electrode, a negative current collector and a negative active material layer of a negative electrode, and a separator. A plurality of first tabs 121 of the first electrode 201 and a plurality of second tabs 122 of the second electrode 202 may be stacked in the thickness direction of the electrode assembly 120. The first tab 121 may be composed of a first current collector (such as a positive current collector), and the second tab 122 may be composed of a second current collector (such as a negative current collector).

[0038] The top cover assembly 220 includes a top cover body 221 and a first terminal 223 and a second terminal 224 disposed on the top cover body 221. The first terminal 223 and the second terminal 224 can pass through the top cover body 221 and can be insulated from the top cover body 221. One of the first terminal 223 and the second terminal 224 is a positive terminal, and the other is a negative terminal. In this embodiment, a first tab 121 and a second tab 122 at one end of the electrode assembly 120 are respectively connected to the corresponding first terminal 223 and the second terminal 224. The first tab 121 and the second tab 122 can be directly or indirectly electrically connected to the first terminal 223 and the second terminal 224. In some embodiments, the first tab 121 and the first terminal 223, and the second tab 122 and the second terminal 224 can be electrically connected through corresponding adapter pieces 226. The first tab 121 and the second tab 122 can be bent and welded to the adapter piece 226, for example, by ultrasonic welding. In some other embodiments, the first tab 121 and the second tab 122 may also be directly welded to the corresponding first pole post 223 and the second pole post 224.

[0039] Figure 3A and Figure 3B These are partial schematic diagrams of the first tab 121 and the second tab 122 of an electrode assembly according to an embodiment of this application. (In conjunction with...) Figure 3A and Figure 3BAs shown, multiple (or multi-layered) first tabs 121 are stacked and connected to form a first welding area 410. The multiple first tabs 121 can be welded together in the first welding area 410. The first tabs 121 can be connected to the corresponding first pole 223 in the first welding area 410 via an adapter piece 226, or they can be directly connected to the first pole 223 in the first welding area 410. Multiple second tabs 122 are stacked and connected to form a second welding area 420. The multiple second tabs 122 can be welded together in the second welding area 420. The second tabs 122 can be connected to the corresponding second pole 224 in the second welding area 420 via an adapter piece 226, or they can be directly connected to the second pole 224 in the second welding area 420.

[0040] The first electrode 121 has a first top edge S1 that is away from the main body 124, and the second electrode 122 has a second top edge S2 that is away from the main body 124. The width of the first electrode 121 can gradually decrease in the direction from the main body 124 to the first top edge S1. The width of the second electrode 122 can gradually decrease in the direction from the main body 124 to the second top edge S2.

[0041] A plurality of spaced-apart first recesses 415 are formed in the first welding area 410. A plurality of spaced-apart second recesses 425 are formed in the second welding area 420. The first welding area 410 and the second welding area 420 may each be rectangular in shape.

[0042] The plurality of first recesses 415 and the plurality of second recesses 425 may be formed by welding teeth protruding from the welding head of the welding apparatus and pressing down on the tabs. In this embodiment, the plurality of first recesses 415 and the plurality of second recesses 425 may be formed by spherical welding teeth. In some embodiments, ultrasonic spherical welding may be used to form the first welding area 410 and the second welding area 420. In some cases, the total welding area of ​​the welding teeth is greater than 80% of the total area of ​​the welding teeth to avoid affecting the overcurrent calculation. The projection of each first recess 415 in the stacking direction of the first tab 121 is circular, and the projection of each second recess 425 in the stacking direction of the second tab 122 is circular. In other embodiments, the first recesses 415 and the second recesses 425 may also be formed by welding teeth of other shapes into other suitable shapes.

[0043] Each first electrode 121 is made of a first metal. Each second electrode 122 is made of a second metal. In some embodiments where the first electrode 121 is a positive electrode and the second electrode 122 is a negative electrode, the first metal of the first electrode 121 is aluminum, and the second metal of the second electrode 122 is copper. That is, the positive current collector is aluminum (the first metal), and the negative current collector is copper (the second metal).

[0044] In some embodiments, the thickness of a single-layer first electrode 121 is greater than the thickness of a single-layer second electrode 122. The thickness of the single-layer first electrode 121 formed of the first metal can be 10μm-15μm; for example, the thickness of a single-layer aluminum positive current collector for a positive electrode can be 10μm-15μm. The thickness of the single-layer second electrode 122 formed of the second metal can be 4μm-8μm; for example, the thickness of a single-layer copper negative current collector for a negative electrode can be 4μm-8μm. Typically, the number of layers of multiple first electrodes 121 is the same as the number of layers of multiple second electrodes 122; therefore, the total thickness of multiple first electrodes 121 is greater than the total thickness of multiple second electrodes 122.

[0045] The projected area of ​​each first recess 415 in the stacking direction of the first tab 121 is greater than the projected area of ​​each second recess 425 in the stacking direction of the second tab 122. Larger welding teeth can be used to form the first recess 415 with a larger projected area in the first welding area 410, and smaller welding teeth can be used to form the second recess 425 with a smaller projected area in the second welding area 420.

[0046] Because the first tab 121 and the second tab 122 are made of different metal materials and have different thicknesses (for example, when the number of layers of the first tab 121 and the second tab 122 is greater than 60, the difference in their thicknesses is significant), during the welding process of the tabs to the adapter plate or corresponding pole, if the same welding equipment and process parameters are used to weld the first tabs and the second tab, the welding teeth of the same size are prone to causing different welding strengths or local stress concentrations between the first and second tabs and the adapter plate or pole, leading to the breakage of the tab foil. For example, the thicker first tab 121 is prone to cracks or incomplete welds during welding.

[0047] The thicker first tab 121 is prone to cracking or incomplete welding during soldering. By using larger welding teeth to form a larger projected area first recess 415 in the first welding area 410, the larger welding teeth can reduce the risk of breakage of the first tab 121 through a larger contact area, thus improving yield. Since the thicker first tab 121 requires a larger welding energy input, using larger welding teeth to form the first welding area 410 allows the larger welding teeth to transmit more ultrasonic vibration energy through a larger contact area, while reducing energy loss and avoiding energy attenuation caused by the thickness of the first tab 121. On the other hand, for the thinner second tab 122, excessive indentation should be avoided. By using smaller welding teeth to form a smaller projected area second recess 425 in the second welding area 420, the indentation depth of the second recess 425 can be precisely controlled, avoiding loss of conductive cross-sectional area due to excessive deformation of the second tab 122. In addition, using smaller welding teeth to form the second welding area 420 also makes it easier to concentrate welding energy. Therefore, it meets the different welding requirements of electrode tabs with different materials and thicknesses. For example, this technical effect can be achieved when the total thickness of the aluminum foil of the first electrode tab 121 is 100μm and the total thickness of the copper foil of the second electrode tab 122 is 50μm.

[0048] Figure 4 This is a schematic cross-sectional view of the first recess of the first electrode tab and the second recess of the second electrode tab according to an embodiment of this application. See also Figure 4 As shown, the cross-sectional view of the first recess 415 is along... Figure 3A Line X1 in the diagram is taken at the first welding area 410, and the cross-sectional view of the second recess 425 is along... Figure 3B Line X2 is cut at the second welding area 420. In some embodiments, the second depth D2 of each second recess 425 is less than the first depth D1 of each first recess 415. That is, the depth of the first recess 415 with a larger projected area can also be greater. Specifically, in some embodiments, the first depth D1 can be greater than 50% of the thickness of the plurality of first tabs 121. The second depth D2 can be greater than 50% of the thickness of the plurality of second tabs 122. The thickness of the plurality of first tabs 121 is the sum of the thicknesses of each first tab 121, and the thickness of the plurality of second tabs 122 is the sum of the thicknesses of each second tab 122. By setting the thickness of the recess to be greater than 50% of the thickness of the corresponding tab, the problem of incomplete welding of the total thickness of the tab can be prevented.

[0049] In this embodiment, the plurality of first recesses 415 and the plurality of second recesses 425 may be formed by spherical welding teeth. The first recesses 415 and the second recesses 425 may each be spherical grooves. The projection shape of the first recess 415 in the stacking direction of the first tab 121 is circular, and the projection shape of the second recess 425 in the stacking direction of the second tab 122 is circular. The radius of the circular projection of the first recess 415 is larger than the radius of the circular projection of the second recess 425.

[0050] The plurality of first recesses 415 and the plurality of second recesses 425 can be arranged in an array of multiple rows and columns, respectively. In some embodiments, the plurality of first recesses 415 can be arranged in one to four rows in the first welding area 410, and the plurality of second recesses 425 can be arranged in one to four rows in the second welding area 420. Figure 3A and Figure 3B The diagram shows two rows of first recesses 415 and second recesses 425 as examples. In each row, the first recesses 415 are spaced apart in a direction parallel to the first top edge S1 of the first tab 121, and in each row, the second recesses 425 are spaced apart in a direction parallel to the second top edge S2 of the second tab 122.

[0051] In some embodiments, the number of first recesses 415 is less than the number of second recesses 425. For example, in this embodiment, there are 16 first recesses 415 arranged in 2 rows and 8 columns; and 20 second recesses 425 arranged in 2 rows and 10 columns. Having more first recesses 415 with larger projected areas and fewer second recesses 425 with smaller projected areas ensures that the total welding area of ​​the welding teeth is greater than 80% of the total welding area, thus avoiding any impact on overcurrent calculations.

[0052] In some embodiments, the hardness of the first metal of the first tab 121 is less than the hardness of the second metal of the second tab 122. For example, in some embodiments where the first tab 121 is a positive tab and the second tab 122 is a negative tab, the first metal of the first tab 121 is aluminum, and the second metal of the second tab 122 is copper. The hardness of aluminum is approximately 25 HV (Vickers hardness), and the hardness of copper is approximately 90 HV. The hardness of the aluminum in the first tab 121 is lower than the hardness of the copper in the second tab 122. The lower hardness of the first tab 121 results in higher ductility and easier plastic deformation. By using larger welding teeth to form the first recess 415 of the first tab 121, the larger welding teeth can provide a more uniform contact area, avoiding local stress concentration in the first tab 121 that could lead to tearing or excessive deformation of the tab foil. On the other hand, the second tab 122 has higher hardness and better conductivity, requiring higher ultrasonic energy to achieve plastic flow. By using smaller welding teeth to form the second recess 425 of the second tab 122, the smaller welding teeth can increase the local pressure (i.e., higher pressure per unit area), thereby promoting the metallurgical bonding of the foil of the second tab 122 with the solder joint.

[0053] In some embodiments, the thermal conductivity of the first metal of the first electrode 121 is lower than that of the second metal of the second electrode 122, and the melting point of the first metal is lower than that of the second metal. For example, in some embodiments where the first electrode 121 is a positive electrode and the second electrode 122 is a negative electrode, the aluminum of the first electrode 121 has a thermal conductivity of approximately 237 W / m·K and a melting point of approximately 660°C, while the copper of the second electrode 122 has a thermal conductivity of approximately 401 W / m·K and a melting point of approximately 1085°C. In such embodiments, by using large-sized welding teeth to weld the first electrode 121, local heat accumulation can be reduced, preventing the first metal with a lower melting point from overheating and melting. Simultaneously, the ultrasonic mechanical energy can be distributed across the area. Furthermore, the second metal of the second electrode 122 requires a higher instantaneous energy density; by using small-sized welding teeth on the second metal with a higher melting point, the temperature can be rapidly raised to the welding temperature.

[0054] In some embodiments, different metal oxide layers are formed on the foil surfaces of the first tab 121 and the second tab 122. Specifically, the first tab 121 may include a first tab body made of a first metal (e.g., aluminum) and a first metal oxide layer located on the surface of the first tab body. The first metal oxide layer may be formed by oxidizing the first metal. The first metal layer may be, for example, an aluminum oxide (e.g., Al2O3) layer. The second tab 122 may include a second tab body made of a second metal (e.g., copper) and a second metal oxide layer located on the surface of the second tab body. The second metal oxide layer may be formed by oxidizing the second metal. The second metal layer may be, for example, a copper oxide (e.g., CuO or Cu2O) layer.

[0055] The first metal oxide layer of the first tab 121 can be denser or thicker than the second metal oxide layer of the second tab 122. Because the first metal oxide layer is denser or thicker (e.g., the natural oxide layer of aluminum is dense and insulating), it is more robust. By employing large-sized welding teeth, the first metal oxide layer can be broken more effectively through a larger frictional contact area and a longer ultrasonic treatment time, thus promoting weld bonding between pure first metals. Furthermore, because the second metal oxide layer of the second tab 122 is sparser or thinner, it is more easily damaged; for example, the natural oxide layer of copper (e.g., CuO or Cu2O) is thinner and more easily damaged and removed. The second metal oxide layer can be rapidly broken down using the high pressure (without an excessively large contact area) of small-sized welding teeth. Small-sized welding teeth can also concentrate energy to quickly break through the surface second metal oxide layer (e.g., CuO or Cu2O) and achieve efficient welding.

[0056] In some embodiments, different welding process parameters are used for the first tab 121 and the second tab 122, which are made of different materials and have different thicknesses. For example, for the first tab 121, which is made of aluminum and has a thicker thickness, the welding process parameters are: energy 450J, amplitude 40μm, and pressure 30PSI (pounds per square inch); for the second tab 122, which is made of copper and has a thinner thickness, the welding process parameters are: energy 450J, amplitude 45μm, and pressure 30PSI.

[0057] Figure 5A and Figure 5B These are partial schematic diagrams of the first electrode tab 121 and the second electrode tab 122 of an electrode assembly according to another embodiment of this application. Multiple first electrode tabs 121 and multiple second electrode tabs 122 can be stacked in a staggered manner, combined with... Figure 5A and Figure 5BAs shown, the bottommost first electrode 121t and bottommost first electrode 121b of multiple first electrode tabs 121 in the stacking direction are marked, as are the bottommost second electrode 122t and bottommost second electrode 122b of multiple second electrode tabs 122 in the stacking direction.

[0058] Each first electrode tab 121 has a first top edge S1 that is away from the main body 124. The first top edge S1 of the topmost first electrode tab 121t is closer to the main body 124 than the first top edge S1 of the bottommost first electrode tab 121b. Each second electrode tab 122 has a second top edge S2 that is away from the main body 124. The second top edge S2 of the topmost second electrode tab 122t is closer to the main body 124 than the second top edge S2 of the bottommost second electrode tab 122b.

[0059] In this embodiment, as Figure 5A As shown, in the direction from the first top edge S1 of the topmost first electrode tab 121t to the first top edge S1 of the bottommost first electrode tab 121b (i.e., the length direction of the first electrode tab), a portion of the first welding area 410 is located between the first top edge S1 of the topmost first electrode tab 121t and the first top edge S1 of the bottommost first electrode tab 121b. Specifically, at least a portion of the plurality of first recesses 415 in the first welding area 410 that are away from the main body 124 are located between the first top edge S1 of the topmost first electrode tab 121t and the first top edge S1 of the bottommost first electrode tab 121b.

[0060] like Figure 5B As shown, in the direction from the second top edge S2 of the topmost second electrode 122t to the second top edge S2 of the bottommost second electrode 122b (i.e., the length direction of the second electrode), a portion of the second welding area 420 is located between the second top edge S2 of the topmost second electrode 122t and the second top edge S2 of the bottommost second electrode 122b. Specifically, at least a portion of the plurality of second recesses 425 in the second welding area 420 that are away from the body 124 are located between the second top edge S2 of the topmost second electrode 122t and the second top edge S2 of the bottommost second electrode 122b.

[0061] The region between the first top edge S1 of the topmost first electrode tab 121t and the first top edge S1 of the bottommost first electrode tab 121b can be called the electrode tab misalignment region. Along the length direction of the first electrode tab 121, the distance between the first top edge S1 of the topmost first electrode tab 121t and the first top edge S1 of the bottommost first electrode tab 121b is <6mm, that is, the misalignment tolerance is less than 6mm.

[0062] Similarly, the region between the second top edge S2 of the topmost second tab 122t and the second top edge S2 of the bottommost second tab 122b can be called the tab misalignment region. Along the length of the second tab 122, the distance between the second top edge S2 of the topmost second tab 122t and the second top edge S2 of the bottommost second tab 122b is <6mm, that is, the misalignment tolerance is less than 6mm.

[0063] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A single cell, characterized by, The single battery comprises: a housing; a first pole and a second pole provided on the housing, an electrode assembly accommodated in the housing, the electrode assembly comprising a main body, and a plurality of first tabs and a plurality of second tabs extending from the main body, the plurality of first tabs and the plurality of second tabs being arranged in a spaced manner, the plurality of first tabs being stacked and connected to form a first welding area connected to the first pole, the plurality of second tabs being stacked and connected to form a second welding area connected to the second pole, a plurality of first recesses being formed in the first welding area in a spaced manner, and a plurality of second recesses being formed in the second welding area in a spaced manner, wherein a material of the plurality of first tabs comprises a first metal, a material of the plurality of second tabs comprises a second metal, a thickness of the plurality of first tabs is greater than a thickness of the plurality of second tabs, and a projection area of each of the first recesses in a stacking direction of the first tabs is greater than a projection area of each of the second recesses in a stacking direction of the second tabs.

2. The single battery according to claim 1, wherein a hardness of the first metal of the first tab is less than a hardness of the second metal of the second tab, and a thickness of a single layer of the first tab is greater than a thickness of a single layer of the second tab.

3. The single battery according to claim 1, wherein the first tab comprises a first tab body composed of the first metal, and a first metal oxide layer on a surface of the first tab body, and the second tab comprises a second tab body composed of the second metal, and a second metal oxide layer on a surface of the second tab body, wherein the first metal oxide layer is denser or thicker than the second metal oxide layer.

4. The single battery according to claim 1, wherein a second depth of each of the second recesses is less than a first depth of each of the first recesses.

5. The single battery according to claim 4, wherein the first depth is greater than 50% of the thickness of the plurality of first tabs, and the second depth is greater than 50% of the thickness of the plurality of second tabs.

6. The single battery according to claim 1, wherein a number of the plurality of first recesses is less than a number of the plurality of second recesses.

7. The cell according to claim 1, wherein each of the first tabs has a first top edge away from the main body, and each of the second tabs has a second top edge away from the main body, in the stacking direction of the first tabs, the plurality of first tabs comprises a bottommost first tab and a topmost first tab, the first top edge of the topmost first tab being closer to the main body than the first top edge of the bottommost first tab, in the stacking direction of the second tabs, the plurality of second tabs comprises a bottommost second tab and a topmost second tab, the second top edge of the topmost second tab being closer to the main body than the second top edge of the bottommost second tab, wherein a part of the first welding region is located between the first top edge of the topmost first tab and the first top edge of the bottommost first tab in a direction from the first top edge of the topmost first tab to the first top edge of the bottommost first tab, a part of the second welding region is located between the second top edge of the topmost second tab and the second top edge of the bottommost second tab in a direction from the second top edge of the topmost second tab to the second top edge of the bottommost second tab. 8.The single cell according to any one of claims 1-7, wherein a projection of each of the first recesses in a stacking direction of the first tab is circular, and a projection of each of the second recesses in a stacking direction of the second tab is circular. 9.The single cell according to any one of claims 1-7, wherein a plurality of the first recesses are arranged in the first welding region as 1 to 4 rows, the first recesses in each row are arranged at intervals in a direction parallel to the first top edge of the first tab, a plurality of the second recesses are arranged in the second welding region as 1 to 4 rows, the second recesses in each row are arranged at intervals in a direction parallel to the second top edge of the second tab. 10.The single cell according to any one of claims 1-7, wherein the first tab is a positive electrode tab, and the first metal is aluminum; the second tab is a negative electrode tab, and the second metal is copper.

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