Secondary battery and electric device
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-27
- Publication Date
- 2026-08-13
Smart Images
Figure CN2024084015_13082026_PF_FP_ABST
Abstract
Description
Secondary batteries and electrical appliances Technical Field
[0001] This application relates to the field of energy storage technology, and in particular to a secondary battery and an electrical device having said secondary battery. Background Technology
[0002] Secondary batteries (such as lithium-ion batteries) are widely used in electronic mobile devices, power tools, and electric vehicles. Stacked secondary batteries typically consist of stacked electrodes and tabs connected to the electrodes. The tabs are integrally connected to the current collectors of the electrodes and are manufactured using a die-cutting process.
[0003] However, tabs may occupy space within the secondary battery, leading to a decrease in energy density. Furthermore, tabs may cause localized poor wetting of the electrode sheets, affecting the cycle performance of the secondary battery. Additionally, tabs manufactured using die-cutting processes have lower electrical and thermal conductivity, and the die-cutting process reduces production efficiency and increases production costs.
[0004] Summary of the Invention
[0005] In view of this, it is necessary to provide a secondary battery that can solve at least one of the above technical problems.
[0006] In addition, it is necessary to provide an electrical device having the aforementioned secondary battery.
[0007] This application provides a secondary battery, including a housing, at least one electrode assembly disposed within the housing, and a plurality of first tabs. Each electrode assembly is a stacked structure and includes a plurality of first tabs stacked in a first direction. Each first tab includes a first current collector and a first material layer disposed on the first current collector. The first current collector includes a first side, a second side, a third side, and a fourth side connected end-to-end. The second side and the fourth side are disposed opposite each other in a second direction, and the first side and the third side are disposed opposite each other in a third direction, with the first direction, the second direction, and the third direction being perpendicular to each other. The dimension of the first side in the second direction is W1, and the dimension of the second side in the third direction is L1, where 1 < L1 / W1 ≤ 5. The first tab is integrally disposed with the first current collector and extends from the first side of the first current collector. Viewed from the first direction, the first tab is in contact with the first material layer at the first side. The dimension of the first tab in the second direction is W2, where W2 = W1. The secondary battery also includes a first adapter electrically connected to the plurality of first tabs and also connected to the housing.
[0008] In the secondary battery of this application, by setting a first tab extending from the first side to the first current collector, the space occupied by the first tab within the casing is reduced, thereby reducing the impact of the first tab on the energy density of the secondary battery. Furthermore, during electrolyte injection, the electrolyte can enter the interlayer gap of the electrode sheet from both ends of the electrode assembly in the second direction. The required wetting distance of the electrolyte is shorter, which is beneficial for the electrolyte to fully wet the electrode assembly and improve the wetting efficiency of the electrolyte, improving the interface during cycling and enhancing the cycle performance of the secondary battery. In addition, the first tab does not require die-cutting, thus increasing the conduction area for current and heat, which not only improves conductivity and thermal conductivity but also improves production efficiency and reduces production costs. Moreover, since 1 < L1 / W1 ≤ 5, the conduction distance of electrons in the first current collector from the third side along the third direction to the first side can be reduced, thereby reducing the risk of uneven electron density distribution or increased internal resistance, further improving the interface during cycling and enhancing the cycle performance of the secondary battery.
[0009] In some possible implementations, the first tab includes a first segment connecting a first side and a second segment connecting the first segment, the second segment being bent relative to the first segment. Multiple second segments form a first connecting portion, to which a first adapter is connected. Therefore, it is advantageous to reduce the space occupied by the first tab on the electrode assembly side in the third-side upward direction, thereby increasing the energy density of the secondary battery.
[0010] In some possible implementations, multiple first tabs are divided into N tab groups, where N is a positive integer. Each tab group includes a first tab bundle and a second tab bundle. The first segments of the first tabs in the first tab bundle and the first segments of the first tabs in the second tab bundle extend in a direction away from each other, while the second segments of the first tabs in the second tab bundle and the second segments of the first tabs in the second tab bundle extend in a direction closer to each other. By bending each tab bundle independently, the length required for the second segments to overlap after bending the first tabs is smaller, thereby reducing the overall weight and production cost of the secondary battery.
[0011] In some possible implementations, there is one electrode assembly, and N tabs are all connected to the first electrode of the electrode assembly.
[0012] In some possible implementations, there are multiple electrode assemblies, with N tab groups connected to the first electrode plates of multiple electrode assemblies. By dividing the first tabs connecting the multiple electrode assemblies into an even number of tab bundles and bending each tab bundle independently, the length required for the second segments to overlap after bending the first tabs is reduced, thereby decreasing the overall weight and production cost of the secondary battery. Furthermore, when at least one electrode assembly has a quality problem, the problematic electrode assembly (and other electrode assemblies welded to it) can be removed individually, avoiding the risk of all electrode assemblies being scrapped simultaneously when the first tabs of all electrode assemblies are bent together.
[0013] In some possible implementations, there are two electrode assemblies, with N being 1. A first tab bundle is connected to the first electrode of one electrode assembly, and a second tab bundle is connected to the first electrode of another electrode assembly. By bending the first tabs connected to the same electrode assembly to form a first tab bundle or a second tab bundle, the length required for the second segment to be stacked after bending the first tab is reduced, thereby reducing the overall weight and production cost of the secondary battery.
[0014] In some possible implementations, the first adapter includes N connecting regions and an adapter region connected to each connecting region, the adapter region being bent relative to the connecting regions. The connecting region is located on the side of the first connecting portion facing the electrode assembly, and is connected to the second segment of the first tab in the first and second tab bundles. The adapter region is connected to the housing. The N connecting regions and N tab groups correspond one-to-one, thereby facilitating the connection of the first adapter to each tab group.
[0015] In some possible implementations, the second segments of the first tabs in the first tab bundle are stacked and welded together to form a first welding area, thereby increasing the connection strength between the second segments. The connecting area is welded to the second segments to form a second welding area, thereby increasing the welding strength between the connecting area and the second segments. Furthermore, the stacking and welding of the second segments facilitates the connection between the connecting area and the second segment of each first tab in the corresponding tab bundle.
[0016] In some possible implementations, from a third-party perspective, the first and second welding zones overlap, thereby improving the stability of the welding between the second segments at the first welding zone.
[0017] In some possible implementations, viewed from a third-party perspective, the first welding area is located at 0 to 1 / 3 of the thickness of the electrode assembly in the first direction. This allows for sufficient welding between the respective second segments in each tab group, enabling the first tab in each tab group to connect to the first adapter.
[0018] In some possible implementations, the secondary battery further includes a first insulating member disposed on the side of the connection area facing the electrode assembly, with the first insulating member facing third-party upward. The first insulating member may cover burrs or solder marks on the connection area, reducing the risk of such burrs or solder marks piercing the first segment of the first tab.
[0019] In some possible implementations, the secondary battery further includes a second insulating member disposed on the side of the first connection portion facing away from the connection area, in a third-direction orientation. The second insulating member may cover burrs or solder marks on the first connection portion, reducing damage to the casing caused by such burrs or solder marks.
[0020] In some possible implementations, the number of first tabs in the first tab bundle and the second tab bundle is the same. This allows for the use of the same welding parameters to weld the second segment of each tab bundle, improving the uniformity of the weld quality. It also helps to improve the flatness of the internal structure of the housing.
[0021] In some possible implementations, the length of the first tab is D along the direction extending from the first side, and the thickness of the electrode assembly in the first direction is T, where T / 3 ≤ D ≤ 2T / 3. This allows the first tabs of each tab bundle to be stacked between the folded second segments for easier welding and fixing, while reducing the impact of overlapping second segments of different tab bundles on the energy density or weight of the secondary battery.
[0022] In some possible implementations, the secondary battery further includes multiple second tabs. The electrode assembly also includes multiple second electrode sheets stacked in a first direction. Each second electrode sheet includes a second current collector and a second active material layer disposed on the surface of the second current collector. The second current collector includes a fifth, sixth, seventh, and eighth side connected end-to-end, with the sixth and eighth sides facing each other in the second direction, and the fifth and seventh sides facing each other in the third direction. The fifth side has a dimension of W3 in the second direction, and the sixth side has a dimension of L2 in the third direction, where 1 < L2 / W3 ≤ 5. The second tabs are integrally formed with the second current collector and extend from the fifth side of the second current collector. Viewed from the first direction, the second tabs are in contact with the second active material layer at the fifth side. The second tabs have a dimension of W4 in the second direction, where W4 = W3. The secondary battery also includes a second adapter electrically connected to the multiple second tabs and also connected to the housing. By setting the second tabs to extend from the fifth side of the second current collector, the space occupied by the second tabs within the housing is reduced, thereby helping to reduce the impact of the second tabs on the energy density of the secondary battery. Furthermore, during electrolyte injection, the electrolyte can enter the interlayer gap of the electrode sheet from both ends of the electrode assembly in the second direction. The required wetting distance of the electrolyte is shorter, which is beneficial for the electrolyte to fully wet the electrode assembly and improve the wetting efficiency. In addition, the second tab does not require die-cutting, thus increasing the conduction area for current and heat. This not only improves electrical and thermal conductivity but also increases production efficiency and reduces production costs.
[0023] In some possible implementations, the first tab and the second tab are located at opposite ends of the electrode assembly in a third-direction orientation.
[0024] In some possible implementations, the secondary battery is a prismatic battery with a metal casing. The casing includes a first end wall and a second end wall disposed opposite each other in a second direction, a side wall connecting the first and second end walls, a first electrode post, and a second electrode post. The first and second electrode posts are either both located on the first end wall or both on the side wall. A first adapter is connected to the first electrode post, and a second adapter is connected to the second electrode post. Therefore, the first and second electrode posts can exhibit the same polarity as the first and second electrodes, respectively, and the first and second electrode posts can be used to connect external components.
[0025] In some possible implementations, the housing is a packaging bag. The housing includes a receiving portion and a sealing edge connected to the receiving portion. The electrode assembly is disposed within the receiving portion. Both the first adapter and the second adapter extend from the sealing edge of the housing. Therefore, the first adapter and the second adapter can be used to connect external components.
[0026] A second aspect of this application also provides an electrical device, including a battery compartment and the aforementioned secondary battery. The electrical device is powered by the aforementioned secondary battery, which improves the energy density and electrolyte wetting efficiency of the secondary battery, and eliminates the need for die-cutting of the first tab of the secondary battery. Attached Figure Description
[0027] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:
[0028] Figure 1 is a schematic diagram of the structure of a secondary battery provided in one embodiment of this application in some embodiments.
[0029] Figure 2A is a cross-sectional view of the secondary battery shown in Figure 1 along section line II-II in some embodiments.
[0030] Figure 2B is a cross-sectional view of the secondary battery shown in Figure 1 along section line II-II in some other embodiments.
[0031] Figure 3 is a cross-sectional view of the secondary battery shown in Figure 1 along section line III-III in some embodiments (separator membrane omitted).
[0032] Figure 4 is a cross-sectional view of the secondary battery shown in Figure 1 along section line IV-IV in some embodiments.
[0033] Figure 5 is a schematic diagram of the structure of the first adapter of the secondary battery shown in Figure 4 when viewed from a third-party perspective.
[0034] Figure 6 is a schematic diagram of the structure of the secondary battery of this application in some other embodiments.
[0035] Figure 7 is a cross-sectional view of the secondary battery shown in Figure 6 along the cutting line VII-VII.
[0036] Figure 8 is a cross-sectional view of the secondary battery shown in Figure 1 along section line II-II in some other embodiments.
[0037] Figure 9 is a cross-sectional view of the secondary battery shown in Figure 1 along section line IV-IV in some other embodiments.
[0038] Figure 10 is a schematic diagram of the structure of the first adapter of the secondary battery shown in Figure 9 when viewed from a third-party perspective.
[0039] Figure 11 is a cross-sectional view of the secondary battery shown in Figure 1 along section line II-II in some embodiments.
[0040] Figure 12 is a cross-sectional view of the secondary battery shown in Figure 1 along section line II-II in some other embodiments.
[0041] Figure 13 is a schematic diagram of the structure of a secondary battery provided in another embodiment of this application.
[0042] Figure 14 is a cross-sectional view of the secondary battery shown in Figure 13 along the cutting line XIII-XIII.
[0043] Figure 15 is a schematic diagram of the structure of an electrical device provided in one embodiment of this application.
[0044] Key Component Symbols and Explanations: Electrical Device 1; Housing 10; First End Wall 11; Second End Wall 12; Side Wall 13; First Terminal 14; Second Terminal 15; Receiving Part 16; Sealing Edge 17; Electrode Assembly 20; First Electrode 21; Second Electrode 22; Separator 23; First Tab 30; Tab Assembly 30A; First Tab Bundle 30B; Second Tab Bundle 30C; First Segment 31; Second Segment 32; Second Tab 40; First Adapter 50; Connection Area 51; Adapter Area 52; Second Adapter 60; First Insulator 70; Second Insulator 80; Secondary Battery 100; Battery Compartment 101; First Opening 111; Second Opening 112; First Current Collector 210; First Active Material Layer 211; Insulating Layer 212; Second Current Collector 220; Second Active Material Layer 221; First Connecting Part 320; First Section 521; Second Section 522; First Side 2101; Second Side 2102; Third Side 2103; Fourth Side 2104; Fifth Side 2201 Sixth side 2202, Seventh side 2203, Eighth side 2204, First direction X, Second direction YThird direction Z, First side X1, Second side X2, First material layer H, First welding area S1, Second welding area S2, Length D, Thickness T, Dimensions W1, W2, W3, W4, L1, L2.
[0045] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation
[0046] The technical solutions in the embodiments of this application are described clearly and in detail below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit this application.
[0047] The embodiments of this application will be described in detail below. However, this application may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided to provide a thorough and detailed understanding of this application to those skilled in the art.
[0048] Additionally, for brevity and clarity, the dimensions or thicknesses of various components and layers may be enlarged in the accompanying drawings. Throughout the text, the same numerical values refer to the same elements. As used herein, the terms "and / or" and "and / or" include any and all combinations of one or more of the associated enumerated items. Furthermore, it should be understood that when element A is referred to as "connecting" element B, element A may be directly connected to element B, or there may be an intermediate element C and element A and element B may be indirectly connected to each other.
[0049] Furthermore, when describing the implementation of this application, the word "may" refers to "one or more implementations of this application".
[0050] The technical terms used herein are for the purpose of describing particular embodiments and are not intended to limit this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It should be further understood that the term "comprising," as used in this specification, means the presence of the described features, values, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, values, steps, operations, elements, components, and / or combinations thereof.
[0051] Spatial terms, such as "above," may be used herein for convenience in describing the relationship between one element or feature and another element (or feature) or feature (or feature) illustrated in the figures. It should be understood that, in addition to the directions depicted in the figures, spatial terms are intended to include different orientations of the device or apparatus during use or operation. For example, if the device in the figure is flipped, an element described as "above" or "on" other elements or features would be oriented "below" or "under" other elements or features. Therefore, the exemplary term "above" can include both above and below orientations. It should be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. Therefore, a first element, component, region, layer, or portion discussed below may be referred to as a second element, component, region, layer, or portion without departing from the teachings of the exemplary embodiments.
[0052] As used in this article, "parallel" and "perpendicular" are used to describe the ideal state between two components. In actual production or use, two components may exist in a state that is approximately parallel or perpendicular. For example, combined with numerical descriptions, parallel can refer to the angle between two straight lines within ±10°, parallel can also refer to the dihedral angle between two planes within ±10°, and parallel can also refer to the angle between a straight line and a plane within ±10°. Perpendicular can refer to the angle between two straight lines within 90±10°, perpendicular can also refer to the dihedral angle between two planes within 90±10°, and perpendicular can also refer to the angle between a straight line and a plane within 90±10°. The two components described as "parallel" or "perpendicular" do not have to be absolutely straight lines or planes; they can be approximately straight lines or planes. From a macroscopic perspective, if the overall direction of extension is a straight line or plane, the component can be considered a "straight line" or "plane".
[0053] In this application, the design relationships of greater than, less than, or not equal to parameter values need to exclude reasonable errors of the measuring equipment.
[0054] Please refer to Figures 1 to 4. One embodiment of this application provides a secondary battery 100, including a housing 10, at least one electrode assembly 20 disposed within the housing 10, an electrolyte (not shown), a first tab 30, and a second tab 40. Figures 1 to 4 illustrate the electrode assembly 20 as a single unit. As shown in Figures 2A to 4, each electrode assembly 20 has a stacked structure, including multiple first electrodes 21, multiple second electrodes 22, and multiple separators 23. In the stacked structure, the first electrodes 21 and second electrodes 22 are stacked alternately, with one second electrode 22 in every two adjacent first electrodes 21 and one first electrode 21 in every two adjacent second electrodes 22. The separators 23 are disposed between adjacent first electrodes 21 and second electrodes 22, and the separators 23 are used to prevent direct contact between the first electrodes 21 and second electrodes 22, thereby reducing the possibility of short circuits caused by contact between the first electrodes 21 and second electrodes 22. The first tab 30 is electrically connected to the first electrode 21, and the second tab 40 is electrically connected to the second electrode 22.
[0055] In some embodiments, the housing 10 is made of metal. The housing 10 includes a first end wall 11 and a second end wall 12 disposed opposite to each other, a side wall 13 connecting the first end wall 11 and the second end wall 12, and a first electrode post 14 and a second electrode post 15 respectively disposed on the first end wall 11. The first electrode post 14 and the second electrode post 15 are electrically isolated from the first end wall 11. The first end wall 11 and the second end wall 12 may be arranged in parallel. In some embodiments, the secondary battery 100 is a prismatic battery. The side wall 13 and the second end wall 12 may be integrally formed, and the first end wall 11 and the side wall 13 may be welded or snap-fitted together. The housing 10 may be made entirely of steel. For example, the steel housing includes the elements Fe and C, and may also include one or more of the elements Ni, Co, Al, Mn, Cr, Cu, Mg, Mo, S, Si, Ti, V, Pb, Sb, N, and P. For example, the first end wall 11 is made of steel, and the second end wall 12 and the side wall 13 are also made of steel. As shown in Figure 3, a first opening 111 and a second opening 112 are provided on the first end wall 11, which are spaced apart. The first pole post 14 and the second pole post 15 can be installed in the first opening 111 and the second opening 112 by means of bonding or riveting, respectively.
[0056] A three-dimensional coordinate system is established based on three mutually perpendicular directions: a first direction X, a second direction Y, and a third direction Z. In the description of this embodiment, the first direction X is the stacking direction of the plurality of first pole pieces 21. Although Figures 1 to 4 indicate that the first direction X has a specific vector direction to illustrate the stacking direction of the plurality of first pole pieces 21, it can be understood that the opposite direction can also be the stacking direction of the plurality of first pole pieces 21. As shown in Figure 2A, the first direction X has a first side X1 and a second side X2 opposite to the first side X1. The second direction Y is the direction from the second end wall 12 to the first end wall 11. The third direction Z is the direction from the first pole piece 14 to the second pole piece 15.
[0057] As shown in Figures 2A and 4, the first electrode 21 includes a first current collector 210 and a first active material layer 211 stacked in the first direction X. The first electrode 21 can be a positive electrode. Correspondingly, the first current collector 210 can be a positive current collector, and the first active material layer 211 can be a positive active material layer. The second electrode 22 includes a second current collector 220 and a second active material layer 221 stacked together. The second electrode 22 can be a negative electrode. Correspondingly, the second current collector 220 can be a negative current collector, and the second active material layer 221 can be a negative active material layer.
[0058] The positive electrode current collector can be aluminum foil or nickel foil, and the negative electrode current collector can be at least one of copper foil, nickel foil, or carbon-based current collector. The positive electrode active material layer contains a positive electrode active material, which includes a compound that reversibly inserts and extracts lithium ions (lithiation intercalation compound). In some embodiments, the positive electrode active material may include a lithium transition metal composite oxide. This lithium transition metal composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel. In some embodiments, the positive electrode active material is selected from lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt ternary materials (NCM), lithium manganese oxide (LiMn2O4), and lithium nickel manganese oxide (LiNi). 0.5 Mn 1.5 At least one of lithium iron phosphate (LiFePO4) or lithium iron phosphate (LiFePO4).
[0059] The negative electrode active material layer comprises a negative electrode active material, which is a known negative electrode active material capable of reversible intercalation and deintercalation of active ions, and this application is not limited thereto. For example, it may be one or more combinations of graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate, or other metals that can form alloys with lithium. Among them, graphite may be selected from one or more combinations of artificial graphite, natural graphite, and modified graphite; silicon-based materials may be selected from one or more combinations of elemental silicon, silicon oxide compounds, silicon-carbon composites, and silicon alloys; tin-based materials may be selected from one or more combinations of elemental tin, tin oxide compounds, and tin alloys.
[0060] The separator 23 comprises at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene. Polyethylene and polypropylene, in particular, have good effects on improving short-circuit performance.
[0061] As shown in Figure 3, viewed from the first direction X, the first current collector 210 can be roughly rectangular, comprising a first side 2101, a second side 2102, a third side 2103, and a fourth side 2104 connected end to end. The second side 2102 and the fourth side 2104 are positioned opposite each other in the second direction Y, and the first side 2101 and the third side 2103 are positioned opposite each other in the third direction Z. In the second direction Y, the second side 2102 is closer to the first pole post 14 and the second pole post 15 than the fourth side 2104. The dimension of the first side 2101 in the second direction Y is defined as W1, and the dimension of the second side 2102 in the third direction Z is defined as L1, where 1 < L1 / W1 ≤ 5. It can be understood that when the first current collector 210 is approximately rectangular, the dimension of the third side 2103 in the second direction Y is approximately the same as the dimension of the first side 2101 in the second direction Y, and the dimension of the fourth side 2104 in the third direction Z is approximately the same as the dimension of the second side 2102 in the third direction Z. Therefore, the first side 2101 and the third side 2103 are the short sides of the first current collector 210, and the extension direction of the first side 2101 or the third side 2103 is the second direction Y; the second side 2102 and the fourth side 2104 are the long sides of the first current collector 210, and the extension direction of the second side 2102 or the fourth side 2104 is the third direction Z. The first electrode 30 is integrally disposed with the first current collector 210 and extends from the first side 2101 (short side) of the first current collector 210, and the direction in which the first electrode 30 extends out of the electrode assembly 30 is the third direction Z. The dimension of the first electrode 30 in the second direction Y is equal to the dimension of the first side 2101 in the second direction Y. The dimension of the first tab 30 in the second direction Y is defined as W2, where W2 = W1. Therefore, the first tab 30 does not require die-cutting. During manufacturing, the positive electrode active slurry can be coated on the surface of the first current collector 210, and a blank foil area is reserved at the edge of the first current collector 210. After the positive electrode active slurry is dried, the reserved blank foil area forms the first tab 30. In the embodiments of this application, since the first tab 30 and the first current collector 210 are integrally formed, the first side 2101 of the first current collector 210 can be a virtual boundary line between the first tab 30 and the first current collector 210, as shown in Figures 2A and 3. When viewed from the first direction X, the first tab 30 is in contact with the first material layer H, i.e., the first active material layer 211, at the first side 2101.
[0062] As shown in Figure 2A, in some embodiments, the first tab 30 extends from the electrode assembly 20 in the Z direction and is bent. The first tab 30 includes a first segment 31 connecting the first side 2101 and a second segment 32 connecting the first segment 31, with the second segment 32 bent relative to the first segment 31. By bending the first tab 30, it is beneficial to reduce the space occupied by the first tab 30 on one side of the electrode assembly 20 in the Z direction, thereby increasing the energy density of the secondary battery 100.
[0063] In some embodiments, when the first electrode 21 is a positive electrode and the second electrode 22 is a negative electrode, to reduce the risk of lithium plating on the negative electrode, the edge of the second electrode 22 can extend beyond the edge of the first electrode 21 in the third direction Z, and the edge of the separator 23 can also extend beyond the edge of the second electrode 22. As shown in Figure 2B, in other embodiments, to reduce the risk of short circuits caused by the contact between the bent first tab 30 and the edge of the second electrode 22 (e.g., the separator 23 shrinks at high temperatures, and the first tab 30 may contact the edge of the second electrode 22 in the event of a drop or collision), the first electrode 21 can also include an insulating layer 212 disposed on the first current collector 210, and the first active material layer 211 and the insulating layer 212 are interconnected in the third direction Z. In the third direction Z, the edge of the insulating layer 212 extends beyond the edge of the second electrode 22. At this point, the first active material layer 211 and the insulating layer 212 together form the first material layer H, as shown in Figure 2B. Viewed from the first direction X, the first tab 30 is in contact with the first material layer H at the first edge 2101. More specifically, the first tab 30 is in contact with the insulating layer 212 of the first material layer H at the first edge 2101. Thus, even if the separator 23 shrinks at high temperatures, the insulating layer 212 can reduce the risk of a short circuit at the edge contact between the first tab 30 and the second electrode 22. The insulating layer 212 comprises inorganic particles and polymers. The inorganic particles include at least one of aluminum oxide, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium dioxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. The polymers include at least one of polyacryl alcohol, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyamide-imide, styrene-butadiene rubber, polyvinyl alcohol, polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, waterborne acrylic resin, carboxymethyl cellulose, or sodium carboxymethyl cellulose.
[0064] As shown in Figure 3, viewed from the first direction X, the second current collector 220 can also be roughly rectangular, comprising a fifth side 2201, a sixth side 2202, a seventh side 2203, and an eighth side 2204 connected end-to-end. The sixth side 2202 and the eighth side 2204 are positioned opposite each other in the second direction Y, while the fifth side 2201 and the seventh side 2203 are positioned opposite each other in the third direction Z. The first side 2101 and the seventh side 2203 are located at one end of the electrode assembly 20 in the third direction Z, and the third side 2103 and the fifth side 2201 are located at the other end of the electrode assembly 20 in the third direction Z. In the second direction Y, the sixth side 2202 is closer to the first electrode post 14 and the second electrode post 15 than the eighth side 2204. The second side 2102 and the sixth side 2202 are located at one end of the electrode assembly 20 in the second direction Y, while the fourth side 2104 and the eighth side 2204 are located at the other end of the electrode assembly 20 in the second direction Y. The fifth side 2201 has a dimension of W3 in the second direction Y, and the sixth side 2202 has a dimension of L2 in the third direction Z, where 1 < L2 / W3 ≤ 5. It can be understood that when the second current collector 220 is approximately rectangular, the seventh side 2203 has a dimension in the second direction Y that is approximately the same as the fifth side 2201 in the second direction Y, and the eighth side 2204 has a dimension in the third direction Z that is approximately the same as the sixth side 2202 in the third direction Z. Therefore, the fifth side 2201 and the seventh side 2203 are the short sides of the second current collector 220, and the sixth side 2202 and the eighth side 2204 are the long sides of the second current collector 220. The second electrode tab 40 is integrally formed with the second current collector 220 and extends from the fifth side 2201 (the short side) out of the second current collector 220. The direction in which the second electrode tab 40 extends out of the electrode assembly 30 is the third direction Z. The dimension of the second electrode tab 40 in the second direction Y is equal to the dimension of the fifth side 2201 in the second direction Y. The dimension of the second tab 40 in the second direction Y is defined as W4, where W4 = W3. Therefore, the second tab 40 does not require die-cutting. During manufacturing, the negative electrode active slurry can be coated on the surface of the second current collector 220, and a blank foil area is reserved at the edge of the second current collector 220. After the negative electrode active slurry is dried, the reserved blank foil area forms the second tab 40. In the embodiments of this application, since the second tab 40 and the second current collector 220 are integrally formed, the fifth side 2201 of the second current collector 220 can be a virtual boundary line between the second tab 40 and the second current collector 220. As shown in FIG3, when viewed from the first direction X, the second tab 40 is in contact with the second active material layer 221 at the fifth side 2201. In some embodiments, the first tab 30 and the second tab 40 are respectively located at opposite ends of the electrode assembly 20 in the third direction Z. The first tab 30 extends out of the electrode assembly 20 from the second side X2, and the second tab 40 extends out of the electrode assembly 20 from the first side X1.
[0065] As shown in Figure 3, when viewed from the first direction X, the first electrode 21 and the second electrode 22 overlap. When the first electrode 21 is the positive electrode and the second electrode 22 is the negative electrode, in order to reduce the risk of lithium plating on the negative electrode, the second electrode 22 can be set to extend from the area overlapping with the first electrode 21 along the second direction Y and the third direction Z. Therefore, in the third direction Z, the seventh side 2203 is closer to the sidewall 13 than the first side 2101, and the fifth side 2201 is closer to the sidewall 13 than the third side 2103; in the second direction Y, the sixth side 2202 is closer to the first electrode post 14 and the second electrode post 15 than the second side 2102, and the eighth side 2204 is farther away from the first electrode post 14 and the second electrode post 15 than the fourth side 2104.
[0066] As shown in Figures 2A to 5, the secondary battery 100 further includes a first adapter 50 and a second adapter 60 (the second adapter 60 is shown in Figures 2A and 3). The first adapter 50 is electrically connected to a plurality of first tabs 30, and the second adapter 60 is electrically connected to a plurality of second tabs 40. In some embodiments, the second segments 32 of the plurality of first tabs 30 together form a first connecting portion 320, and the first adapter 50 is connected to the first connecting portion 320.
[0067] The first adapter 50 and the second adapter 60 are also connected to the housing 10. In some embodiments, when the housing 10 is made of metal, the first adapter 50 is connected to the first terminal 14, and the second adapter 60 is connected to the second terminal 15. Therefore, the first terminal 14 and the second terminal 15 can have opposite polarities, allowing the secondary battery 100 to supply power to external components (not shown). For example, when the first electrode 21 is a positive electrode and the second electrode 22 is a negative electrode, the first terminal 14 is positive and the second terminal 15 is negative. Moreover, when the first adapter 50 connects the first tab 30 to the first terminal 14 and the second adapter 60 connects the second tab 40 to the second terminal 15, the first tab 30 and the second tab 40 are guided to the same end of the electrode assembly 20 through the two adapters. Referring to Figures 6 and 7, in some embodiments, the two adapters can also guide the first tab 30 and the second tab 40 to opposite ends of the electrode assembly 20 in the third direction Z. For example, the first post 14 and the second post 15 are both disposed on the sidewall 13, and the first post 14 and the second post 15 are arranged opposite each other in the third direction Z. The first adapter 50 connects the first tab 30 to the first post 14, and the second adapter 60 connects the second tab 40 to the second post 15. By guiding the first tab 30 and the second tab 40 to the same end or opposite ends of the electrode assembly 20 through the two adapters, the application range of the secondary battery 100 is broadened.
[0068] In some embodiments, the first adapter 50 can be made of aluminum, nickel, copper, steel, or nickel-plated copper. The second adapter 60 can be made of aluminum, nickel, copper, steel, or nickel-plated copper. To reduce the impact of the first adapter 50 and the second adapter 60 on the energy density of the secondary battery 100, the width of the first adapter 50 in the first direction X can be set to not exceed the thickness T of the electrode assembly 20 in the first direction X, and the width of the second adapter 60 in the first direction X can not exceed the thickness T of the electrode assembly 20 in the first direction X. Further, the thickness of the first adapter 50 can be from 0.08 mm to 2.0 mm, and the thickness of the second adapter 60 can be from 0.08 mm to 2.0 mm.
[0069] In the secondary battery 100 of this application, by providing a first tab 30 extending from the first side 2101 (short side) to form a first current collector 210, the space occupied by the first tab 30 within the casing 10 is reduced, thereby helping to minimize the impact of the first tab 30 on the energy density of the secondary battery 100. Furthermore, during electrolyte injection, the electrolyte can enter the interlayer gap of the electrode sheet from both ends of the electrode assembly 20 in the second direction Y. The required wetting distance of the electrolyte is shorter, which facilitates sufficient wetting of the electrode assembly 20 and improves the wetting efficiency of the electrolyte, improves the interface during cycling, reduces capacity decay caused by lithium plating, black spots, purple spots, etc., and enhances the cycle performance of the secondary battery 100. In addition, the first tab 30 does not require die-cutting, thus increasing the current and heat conduction area, which not only improves electrical and thermal conductivity but also increases production efficiency and reduces production costs.
[0070] Similarly, by setting the second tab 40 to extend from the fifth side 2201 (short side) to form the second current collector 220, the space occupied by the second tab 40 within the housing 10 is reduced, thereby helping to minimize the impact of the second tab 40 on the energy density of the secondary battery 100. Furthermore, during electrolyte injection, the electrolyte can enter the interlayer gap of the electrode sheet from both ends of the electrode assembly 20 in the second direction Y. The required wetting distance of the electrolyte is shorter, which facilitates the full wetting of the electrode assembly 20 and improves the wetting efficiency of the electrolyte, improves the interface during cycling, reduces capacity decay caused by lithium plating, black spots, purple spots, etc., and improves the cycle performance of the secondary battery 100. In addition, the second tab 40 does not require die-cutting, thus increasing the current and heat conduction area, which not only improves electrical and thermal conductivity but also increases production efficiency and reduces production costs.
[0071] Furthermore, in this application, since 1 < L1 / W1 ≤ 5, the conduction distance of electrons in the first current collector 210 from the third side 2103 along the third direction Z to the first side 2101 is reduced, thereby reducing the risk of uneven electron density distribution or increased internal resistance, thus further improving the interface during cycling and enhancing the cycle performance of the secondary battery 100. Further, when 1 < L2 / W3 ≤ 5, the conduction distance of electrons in the second current collector 220 from the seventh side 2203 along the third direction Z to the fifth side 2201 can be reduced, thereby reducing the risk of uneven electron density distribution or increased internal resistance.
[0072] In some embodiments, the plurality of first tabs 30 are divided into N tab groups 30A, where N is a positive integer. As shown in FIG2A, when the number of electrode components 20 is one, all N tab groups 30A are connected to the first electrode plate 21 of the electrode component 20. Each tab group 30A includes a first tab bundle 30B and a second tab bundle 30C, that is, the plurality of first tabs 30 are divided into an even number of tab bundles. For example, when N=1, the plurality of first tabs 30 are divided into two tab bundles; when N=2, the plurality of first tabs 30 are divided into four tab bundles.
[0073] The first segment 31 of the first electrode bundle 30B and the first segment 31 of the second electrode bundle 30C extend in a direction away from each other, while the second segments 32 of the first electrode bundle 30B and the second segments 32 of the second electrode bundle 30C extend in a direction closer to each other, so that the first electrode bundle 30B and the second electrode bundle 30C can each form a generally U-shaped structure. The second segments 32 of the first electrode bundle 30B and the second segments 32 of the second electrode bundle 30C are stacked on top of each other, thereby facilitating the simultaneous electrical connection of the first adapter 50 with all the second segments 32 in each electrode bundle. In some embodiments, the first tabs 30 in the first tab bundle 30B or the second tab bundle 30C are bent to form a generally U-shaped structure, such that the first tab bundle 30B or the second tab bundle 30C has an innermost layer and an outermost layer. The innermost layer of the first tab bundle 30B refers to the first tab 30 in the first tab bundle 30B that is connected to the first adapter 50, while the outermost layer of the first tab bundle 30B refers to the first tab 30 in the first tab bundle 30B that is farthest from the first adapter 50 along the stacking direction. Compared to bending all the first tabs 30 together (e.g., all the first tabs 30 extend towards the first side X1 and then towards the second side X2), by dividing the multiple first tabs 30 into an even number of tab bundles and bending each tab bundle independently, the length required for the second segments 32 to overlap after bending the first tabs 30 is smaller. This is especially true when the electrode assembly 20 has a large thickness T in the first direction X (in which case the length required for the first tabs 30 is even greater when bending all the first tabs 30 together). This application can significantly reduce the length required for bending the first tabs 30, thereby reducing the overall weight and production cost of the secondary battery 100. Similarly, to reduce the length required for bending the second tabs 40, the multiple second tabs 40 can also be divided into an even number of tab bundles. The bundling method of the multiple first tabs 30 and the bundling method of the multiple second tabs 40 can be the same or different.
[0074] As shown in Figures 2A to 5, in some embodiments, the first adapter 50 includes N connecting regions 51 and an adapter region 52 connected to each connecting region 51, the adapter region 52 being bent relative to the connecting region 51. The N connecting regions 51 correspond one-to-one with the N tab groups 30A. For example, when multiple first tabs 30 include one tab group 30A, the first adapter 50 includes one connecting region 51. In other embodiments, as shown in Figures 8 to 10, when multiple first tabs 30 include two tab groups 30A, the first adapter 50 includes two connecting regions 51. Each connecting region 51 of the first adapter 50 is located on the side of the first connecting portion 320 facing the electrode assembly 20, and each connecting region 51 is connected to the second segment 32 of the first tab bundle 30B and the second segment 32 of the second tab bundle 30C. The adapter region 52 of the first adapter 50 is connected to the housing 10 (e.g., the adapter region 52 is connected to the first electrode post 14). As shown in Figures 2A and 3, in some embodiments, each connection region 51 is disposed between the electrode assembly 20 and the side wall 13 of the housing 10 in the third direction Z. Viewed from the third direction Z, the connection region 51 overlaps with the connected second segment 32, and the connection region 51 extends from the overlapping area with the second segment 32 in the second direction Y. The transition region 52 is disposed between the electrode assembly 20 and the first end wall 11 of the housing 10 in the second direction Y. Viewed from the third direction Z, the transition region 52 extends from its connection point with the connection region 51 in the third direction Z, and the transition region 52 extends to overlap with the first electrode post 14. Both the connection region 51 and the transition region 52 can be sheet-like structures. The plane containing the connection region 51 extends along the first direction X and the second direction Y, and the plane containing the transition region 52 extends along the first direction X and the third direction Z. The second transition member 60 may have a structure similar to the first transition member 50, which will not be described in detail here.
[0075] As shown in Figures 2A and 8, in some embodiments, the second segments 32 of the first tab bundle 30B or the second tab bundle 30C are stacked and welded together to form a first welding area S1, thereby improving the connection strength between the second segments 32. The connecting area 51 is welded to the second segment 32 to form a second welding area S2, thereby improving the welding strength between the connecting area 51 and the second segment 32. When manufacturing the secondary battery 100, the first tab bundle 30B or the second tab bundle 30C can be bent using a welding head to stack the second segments 32, and then the second segments 32 of the first tab bundle 30B or the second tab bundle 30C can be pre-welded and fixed to improve the connection strength between the second segments 32. Subsequently, the connecting area 51 of the first adapter 50 is stacked on the side of the second segment 32 facing the electrode assembly 20, and then the connecting area 51 is welded and fixed to the second segment 32 using a welding head. The pre-welding and fixing of the second segment 32 facilitates the connection between the connecting area 51 and the second segment 32 of each first tab 30 of the first tab bundle 30B or the second tab bundle 30C.
[0076] In this assembly, the number of first tabs 30 contained in the first tab bundle 30B and the second tab bundle 30C of the tab group 30A can be the same. This allows the same welding parameters (such as welding time and welding temperature) to be used to weld the second segment 32 of the first tab bundle 30B and the second segment 32 of the second tab bundle 30C, eliminating the need for frequent adjustments to welding parameters when welding different tab bundles, simplifying the process, and improving the uniformity of welding quality. Furthermore, it also helps improve the flatness of the internal structure of the housing 10.
[0077] As shown in Figures 2A and 8, in some embodiments, when viewed from a third party to Z, the first welding area S1 and the second welding area S2 overlap, thereby improving the stability of the welding between the second segments 32 at the first welding area S1. In other embodiments, when viewed from a third party to Z, the first welding area S1 and the second welding area S2 can also be separated, thereby reducing the risk of over-welding at the first welding area S1.
[0078] In some embodiments, viewed from a third party in the Z direction, the first welding area S1 is located at 0 to 1 / 3 of the thickness T of the electrode assembly 20 in the first direction X. When the electrode assembly 20 is divided into three equal regions of equal thickness in the first direction X, viewed from a third party in the Z direction, the first welding area S1 may overlap with any region near the outer edge of the aforementioned three equal regions in the first direction X. This ensures sufficient welding between the respective second segments 32 in each tab group 30A, thereby facilitating the connection of the first tab 30 in each tab group 30A to the first adapter 50.
[0079] As shown in Figure 2A, in some embodiments, the length of the first tab 30 is D along the direction extending from the first side 2101, and the thickness of the electrode assembly 20 in the first direction X is T, where T / 3 ≤ D ≤ 2T / 3. Therefore, the first tabs 30 of the first tab bundle 30B or the second tab bundle 30C can be stacked between the folded second segments 32 to facilitate welding and fixing, while reducing the impact of the overlapping of the second segments 32 of the first tab bundle 30B and the second segments 32 of the second tab bundle 30C on the energy density or weight of the secondary battery 100. It can be understood that the direction in which the first tab 30 extends from the first side 2101 is a curved direction. The length D of the first tab 30 is the sum of the lengths of the first segment 31 and the second segment 32 along the aforementioned curved direction.
[0080] Referring to Figures 11 and 12, in some embodiments, the number of electrode assemblies 20 is multiple. Multiple electrode assemblies 20 are connected in parallel or series to increase the supply voltage of the secondary battery 100. In this case, N tab groups 30A are respectively connected to the first electrode plates 21 of the multiple electrode assemblies 20, and each tab group 30A includes a first tab bundle 30B and a second tab bundle 30C. That is, in this embodiment, the first tabs 30 to which the multiple electrode assemblies 20 are connected are divided into an even number of tab bundles, and each tab bundle is bent independently. Figure 11 shows that the number of electrode assemblies 20 is two and the number of tab groups 30A is one. The first tab bundle 30B of this tab group 30A is connected to one of the electrode assemblies 20, and the second tab bundle 30C is connected to the other electrode assembly 20. The first adapter 50 includes a connection area 51, to which both the first tab bundle 30B and the second tab bundle 30C are connected. Figure 12 shows two electrode assemblies 20 and two tab assemblies 30A. Each tab assembly 30A is connected to one of the two electrode assemblies 20. Correspondingly, the first adapter 50 includes two connection areas 51, where the first tab bundle 30B and the second tab bundle 30C of each tab assembly 30A are connected to the same connection area 51.
[0081] Thus, bending the first tab 30 reduces the length required for the second segments 32 to be stacked, especially when the electrode assembly 20 is thick in the first direction X. This embodiment can significantly reduce the length required for bending the first tab 30, thereby reducing the overall weight and production cost of the secondary battery 100. Furthermore, when at least one electrode assembly 20 has a quality problem, the problematic electrode assembly 20 (and other electrode assemblies 20 welded to it) can be removed individually, avoiding the risk of all electrode assemblies 20 being simultaneously scrapped when the first tabs 30 of all electrode assemblies 20 are bent together. Multiple electrode assemblies 20 can be stacked in the first direction X.
[0082] In some other embodiments, the multiple first tabs 30 may not be grouped. In this case, all the first tabs 30 are bent together (e.g., all the first tabs 30 extend towards the first side X1 first and then towards the second side X2), thereby reducing the number of soldering operations and simplifying the process.
[0083] As shown in Figure 2A, in some embodiments, the secondary battery 100 further includes a first insulating member 70, which is disposed on the side of the connection area 51 facing the electrode assembly 20 in the third direction Z. The first insulating member 70 may cover burrs or solder marks on the connection area 51 (burrs may be generated when cutting the first adapter 50, and solder marks may be generated when welding the connection area 51 to the second segment 32, but this application is not limited thereto), reducing the risk of the burrs or solder marks piercing the first segment 31 of the first tab 30, thereby reducing the risk that the first tab 30 is prone to breakage during mechanical abuse. The first insulating member 70 may be a single-sided adhesive containing an insulating material, which may be selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, or polyethylene glycol. In other embodiments, the first insulating member 70 may also be a ceramic coating. The thickness of the first insulating member 70 may be from 0.01 mm to 0.1 mm.
[0084] The secondary battery 100 may further include a second insulating member 80, which is disposed on the side of the first connecting portion 320 opposite to the connecting area 51 in a third direction Z. The second insulating member 80 may cover burrs or solder marks on the first connecting portion 320, reducing damage to the housing 10 caused by such burrs or solder marks. The second insulating member 80 may be a single-sided adhesive containing insulating material, which may be selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, or polyethylene glycol. In other embodiments, the second insulating member 80 may also be a ceramic coating. The thickness of the second insulating member 80 may be from 0.01 mm to 0.1 mm. A similar insulating member may also be provided on the side of the connecting area of the second adapter 60 facing the electrode assembly 20, and a similar insulating member may also be provided on the side of the second connecting portion (not shown) formed by the second tab 40 opposite to the connecting area; these details are omitted here.
[0085] Referring to Figures 13 and 14, another embodiment of this application provides a secondary battery 200. Unlike the secondary battery 100 described above, the casing 10 is a packaging bag, meaning the secondary battery 200 can be a pouch battery. For example, the casing 10 can be a packaging bag sealed with an encapsulating film (such as aluminum-plastic film). The casing 10 includes a receiving portion 16 and a sealing edge 17 connected to the receiving portion 16. An electrode assembly 20 is disposed within the receiving portion 16. A first adapter 50 and a second adapter 60 both extend from the sealing edge 17 into the casing 10, and are used to connect to an external device (not shown). In this embodiment, the second direction Y is the direction in which the adapter area 52 of the first adapter 50 extends from the sealing edge 17, and also the direction in which the adapter area of the second adapter 60 extends from the sealing edge 17. The third direction Z is the arrangement direction of the adapter areas 52 of the first adapter 50 and the adapter areas of the second adapter 60.
[0086] The transition area 52 includes a first part 521 and a second part 522 connected to each other. The first part 521 is connected to the connecting area 51, and the second part 522 is connected to the sealing edge 17. To facilitate the transition area 52 extending beyond the sealing edge 17, the plane containing the first part 521 can be configured to extend along a first direction X and a third direction Z, while the plane containing the second part 522 can extend along a second direction Y and a third direction Z (i.e., along the plane containing the sealing edge 17). That is, the second part 522 is bent relative to the first part 521.
[0087] The secondary battery 100 (or secondary battery 200) of this application can be a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries and lithium-ion polymer secondary batteries.
[0088] Please refer to Figure 15. One embodiment of this application also provides an electrical device 1, including a battery compartment 101 and a secondary battery 100 (or secondary battery 200) housed within the battery compartment 101. The electrical device 1 is powered by the aforementioned secondary battery 100. The energy density and electrolyte wetting efficiency of the secondary battery 100 are improved, and the first tab 30 of the secondary battery 100 does not require die-cutting. In some embodiments, the electrical device 1 of this application may be, but is not limited to, a laptop computer, a pen input computer, a mobile computer, an e-book player, a portable telephone, a portable fax machine, a portable copier, a portable printer, a stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini CD, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, an electric bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household storage battery, and a lithium-ion capacitor, etc.
[0089] The performance of the secondary battery provided in this application is described below through specific embodiments and comparative examples. The secondary battery is illustrated using a square-shell battery with one electrode assembly, a first electrode as the positive electrode, and a second electrode as the negative electrode, along with specific preparation processes and testing methods. Those skilled in the art should understand that the preparation methods described in this application are merely examples, and any other suitable preparation methods are within the scope of this application.
[0090] Example 1
[0091] (1) Preparation of the first electrode: Lithium iron phosphate (LiFePO4), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 96.5:1.5:2. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75wt%, and the mixture was stirred evenly. The slurry was uniformly coated on one surface of a current collector aluminum foil with a thickness of 12μm, leaving an empty foil area at the edge of the aluminum foil. The foil was then dried at 90℃ to obtain an active material layer with a coating thickness of 74μm. The above coating steps were repeated on the other surface of the aluminum foil to obtain a double-sided coated first electrode. The empty foil area is the first tab. The first tab is integrally connected to the first side of the aluminum foil. The dimension W1 of the first side in the second direction is 100mm, the dimension W2 of the first tab in the second direction is 100mm, and the dimension L1 of the second side of the aluminum foil in the third direction is 110mm.
[0092] (2) Preparation of the second electrode: The negative electrode active materials, artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR), were mixed in a weight ratio of 96:1.5:2.5. Deionized water was added as a solvent to prepare a slurry with a weight percentage of 70 wt%, and the mixture was stirred evenly. The slurry was uniformly coated on one surface of a copper current collector foil with a thickness of 8 μm, leaving an empty foil area at the edge of the copper foil. The foil was dried at 110°C to obtain an active material layer with a coating thickness of 58 μm. The above steps were repeated on the other surface of the copper foil to obtain a double-sided coated second electrode, with the empty foil area serving as the second electrode tab. The second electrode tab was integrally connected to the fifth side of the copper foil. The dimension W3 of the fifth side in the second direction was 103 mm, and the dimension W4 of the second electrode tab in the second direction was also 103 mm. The dimension L2 of the sixth side of the copper foil in the third direction was 113 mm.
[0093] (3) Preparation of electrolyte: In a dry argon atmosphere, the organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are first mixed in a mass ratio of EC:EMC:DEC = 30:50:20. Then, lithium salt lithium hexafluorophosphate (LiPF6) is added to the organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.
[0094] (4) Preparation of the isolation membrane: A polyethylene (PE) membrane with a thickness of 9 μm was selected.
[0095] (5) Assembly of the secondary battery: The first electrode, the separator, and the second electrode are stacked sequentially to obtain a stacked electrode assembly, which is then placed inside the housing. Next, the first tab is stacked and welded to the first adapter, and the first adapter is welded to the first terminal post. The first adapter is made of aluminum. The second tab is stacked and welded to the second adapter, and the second adapter is welded to the second terminal post. The second adapter is made of copper. Then, electrolyte is injected into the housing, and the top cover is welded. After standing and formation processes, the secondary battery is obtained.
[0096] Examples 2-4 and Comparative Example 1
[0097] The difference from Example 1 lies in the value of L1 / W1.
[0098] Ten secondary batteries from each comparative example and embodiment were taken for energy density and cycle performance testing.
[0099] The energy density testing steps are as follows: 1) At a test temperature of 25℃, the battery is charged at a constant current of 0.2C to 3.650V, then discharged at a constant current of 0.2C to 0.02C, left to stand for 10 minutes, and then discharged at a constant current of 0.2C to 2.5V, left to stand for 10 minutes, and the discharge capacity D of the battery is obtained. The battery is then charged at a constant current of 0.2C to 3.35V, and then charged at a constant voltage of 0.02C to 3.35V. The length, width, and height of the secondary battery are then measured using an optical measuring instrument to calculate the volume T. The energy density (ED) = D / T, in Wh / L. Finally, the average energy density of 10 samples is calculated.
[0100] The cyclic testing steps are as follows: 1) At a test temperature of 25℃, let the battery stand for 30 minutes to allow it to reach a constant temperature; 2) Charge the battery, specifically: charge at a constant current of 0.5C to 3.650V, CV to 0.02C, and then discharge at a constant current of 0.5C to 2.5V. This constitutes one charge-discharge cycle, with the initial discharge capacity being 100%; 2) Repeat this 800 charge-discharge cycles; 3) Disassemble the electrode assembly and check whether black spots, purple spots, or lithium plating have appeared on the surface of the second electrode. If no black spots, purple spots, or lithium plating are found on any part of the second electrode that is greater than or equal to 2mm, the battery is considered to have completed the charge-discharge cycle. 2 If black spots, purple spots, or lithium plating appear in the area, the cycle test is considered passed. Then, the cycle test pass rate of 100 samples is calculated.
[0101] Table 1
[0102] As can be seen from the test results in Table 1, compared with Comparative Example 1, Examples 1-3 improve the energy density of the secondary battery by setting the first current collector to extend from the shorter first side of the first electrode tab and the second current collector to extend from the shorter fifth side of the second electrode tab; and during electrolyte injection, it is beneficial for the electrolyte to fully wet the electrode assembly and improve the wetting efficiency of the electrolyte, thus improving the interface during the cycle process and improving the cycle performance of the secondary battery.
[0103] Compared to Comparative Example 2, Examples 1-3 reduce the electron conduction distance in the first and second current collectors by setting 1 < L1 / W1 ≤ 5 and 1 < L2 / W3 ≤ 5, thereby reducing the risk of uneven electron density distribution or increased internal resistance, and thus improving the cycle performance of the secondary battery.
[0104] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Therefore, any equivalent variations made in accordance with this application are still within the scope of this application.
Claims
1. A secondary battery, comprising a housing, at least one electrode assembly disposed within the housing, and a plurality of first tabs, each electrode assembly being a stacked structure and comprising a plurality of first tabs stacked in a first direction, wherein, The first electrode includes a first current collector and a first material layer disposed on the first current collector. The first current collector includes a first side, a second side, a third side and a fourth side connected end to end. The second side and the fourth side are arranged opposite to each other in a second direction. The first side and the third side are arranged opposite to each other in a third direction. The first direction, the second direction and the third direction are perpendicular to each other. The first side has a dimension of W1 in the second direction, and the second side has a dimension of L1 in the third direction, where 1 < L1 / W1 ≤ 5. The first electrode tab is integrally formed with the first current collector and extends from the first side out of the first current collector. When viewed from the first direction, the first electrode tab is in contact with the first material layer at the first side. The first electrode tab has a dimension of W2 in the second direction, where W2 = W1. The secondary battery also includes a first adapter, which is electrically connected to a plurality of first tabs and is also connected to the housing.
2. The secondary battery as described in claim 1, wherein, The first electrode includes a first segment connecting the first side and a second segment connecting the first segment. The second segment is bent relative to the first segment, and a plurality of the second segments form a first connecting portion. The first adapter is connected to the first connecting portion.
3. The secondary battery as described in claim 2, wherein, The plurality of first electrodes are divided into N electrode groups, where N is a positive integer. Each electrode group includes a first electrode bundle and a second electrode bundle. The first segment of the first electrode in the first electrode bundle and the first segment of the first electrode in the second electrode bundle extend in a direction away from each other, while the second segment of the first electrode in the first electrode bundle and the second segment of the first electrode in the second electrode bundle extend in a direction close to each other.
4. The secondary battery as described in claim 3, wherein, The number of electrode assemblies is one, and the N tabs are all connected to the first electrode plate of the electrode assembly.
5. The secondary battery as described in claim 3, wherein, The number of electrode assemblies is multiple, and the N tabs are respectively connected to the first electrode plates of the multiple electrode assemblies.
6. The secondary battery as described in claim 3, wherein, The number of electrode assemblies is two, N is 1, the first electrode bundle is connected to the first electrode plate of one electrode assembly, and the second electrode bundle is connected to the first electrode plate of the other electrode assembly.
7. The secondary battery as described in claim 3, wherein, The first adapter includes N connection areas and an adapter area connected to each of the connection areas. The adapter area is bent relative to the connection area. The connection area is located on the side of the first connection portion facing the electrode assembly. The connection area is connected to the second segment of the first tab in the first tab bundle and the second tab bundle. The adapter area is connected to the housing.
8. The secondary battery as described in claim 7, wherein, In the first electrode bundle, the second segments of the first electrode are stacked and welded together to form a first welding area, and the connecting area is welded to the second segment to form a second welding area.
9. The secondary battery as described in claim 8, wherein, From the perspective of the third party, the first welding area and the second welding area overlap.
10. The secondary battery as claimed in claim 8, wherein, When observed from the third direction, the first welding area is located at 0 to 1 / 3 of the thickness of the electrode assembly in the first direction.
11. The secondary battery as claimed in claim 7, wherein, The secondary battery further includes a first insulating member, which is disposed on the side of the connection area facing the electrode assembly in the third direction.
12. The secondary battery as claimed in claim 7, wherein, The secondary battery further includes a second insulating member, which is disposed on the side of the first connection portion背离 the connection area in the third direction.
13. The secondary battery as described in claim 3, wherein, The number of the first tab ears included in the first tab ear bundle and the second tab ear bundle is the same.
14. The secondary battery as claimed in claim 1, wherein, Along the direction in which the first tab ear extends from the first side, the length of the first tab ear is D, and the thickness of the electrode assembly in the first direction is T, where T / 3 ≤ D ≤ 2T / 3.
15. The secondary battery as claimed in claim 1, wherein, The secondary battery further includes a plurality of second tab ears, and the electrode assembly further includes a plurality of second electrode plates stacked in the first direction; The second electrode plate includes a second current collector and a second active material layer disposed on the second current collector. The second current collector includes a fifth side, a sixth side, a seventh side, and an eighth side that are sequentially connected end to end. The sixth side and the eighth side are oppositely disposed in the second direction, and the fifth side and the seventh side are oppositely disposed in the third direction; The dimension of the fifth side in the second direction is W3, and the dimension of the sixth side in the third direction is L2, where W3 < L2. The second tab ear is integrally provided with the second current collector and extends out of the second current collector from the fifth side. When observed from the first direction, the second tab ear is in contact with the second active material layer at the fifth side; the dimension of the second tab ear in the second direction is W4, and W4 = W3; The secondary battery further includes a second adapter, which is electrically connected to the plurality of second tab ears, and the second adapter is further connected to the housing.
16. The secondary battery as claimed in claim 15, wherein, The first tab ear and the second tab ear are respectively located at opposite ends of the electrode assembly in the third direction.
17. The secondary battery as claimed in claim 16, wherein, The secondary battery is a square shell battery. The housing is made of metal and includes a first end wall and a second end wall that are oppositely disposed in the second direction, a side wall connected between the first end wall and the second end wall, a first pole column, and a second pole column. The first pole column and the second pole column are both disposed on the first end wall or both disposed on the side wall. The first adapter is connected to the first pole column, and the second adapter is connected to the second pole column.
18. The secondary battery as claimed in claim 16, wherein, The housing is a packaging bag, which includes a containing portion and a sealing edge connected to the containing portion. The electrode assembly is disposed in the containing portion, and the first adapter and the second adapter both extend out of the housing from the sealing edge.
19. An electrical device, comprising a battery compartment, wherein, The electrical device further includes a secondary battery as described in any one of claims 1 to 18, and the secondary battery is accommodated in the battery compartment.