Secondary battery and electronic device

Abstract

The invention discloses a secondary battery and an electronic device. The secondary battery comprises an electrode assembly, a first cavity and a second cavity, the electrode assembly comprises a multi-tab structure and an adapter, the multi-tab structure is connected with the adapter, and the multi-tab structure comprises a plurality of tabs stacked in the thickness direction of the electrode assembly. A multi-tab structure and an adapter are arranged in the first cavity, and the second cavity is not provided with a multi-tab structure; the first cavity protrudes out of the second cavity on one side of the multi-tab structure in the length direction of the electrode assembly and is provided with a first surface. One side, close to the multi-tab structure, of the second cavity is sunken relative to the first cavity and is provided with a second surface; at least part of the multi-tab structure is arranged between the first surface and the winding structure. In the length direction of the electrode assembly, the distance between the first surface and the winding structure is D1, the distance between the second surface and the winding structure is D2, and D1 is larger than D2. According to the secondary battery, the space utilization rate in the shell can be improved, and the energy density loss of the secondary battery is reduced.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a secondary battery and an electronic device. Background Art

[0002] The wound multi-tab battery cell structure varies from 80W to 120W based on the application rate requirements of different fast charging applications. Based on the different charging rate requirements, the battery cell head is equipped with a single multi-tab structure or multiple multi-tab structures. Summary of the Invention

[0003] The applicant discovered that a multi-tab structure, which includes multiple tabs stacked and wound from the same electrode sheet, uses transfer welding to extract polarity. This requires a certain amount of space between the tabs and the cell head. This space is not fully utilized, resulting in a loss of volumetric energy density in the secondary battery. Therefore, it is necessary to provide a secondary battery that can improve the space utilization within the housing and reduce the loss of secondary battery energy density.

[0004] An embodiment of the present application provides a secondary battery, including an electrode assembly and a shell, the electrode assembly including a first electrode plate, a second electrode plate, a diaphragm and a adapter, the first electrode plate, the diaphragm and the second electrode plate are stacked and wound together to form a wound structure, and the diaphragm is arranged between the first electrode plate and the second electrode plate; the electrode assembly also includes a multi-pole tab structure, the multi-pole tab structure includes a plurality of pole tabs stacked along the thickness direction of the electrode assembly, the multi-pole tab structure is electrically connected to the first electrode plate and the adapter, respectively, or the multi-pole tab structure is electrically connected to the second electrode plate and the adapter, respectively. The housing includes a first cavity and a second cavity, with the wound structure located within the first and second cavities. A multi-tab structure and an adapter are disposed within the first cavity, while neither is disposed within the second cavity. Along the length of the electrode assembly, the first cavity protrudes from the second cavity on a side where the multi-tab structure is disposed and has a first surface. The second cavity is recessed relative to the first cavity on a side near the multi-tab structure and has a second surface. The length of the electrode assembly is perpendicular to its thickness. At least a portion of the multi-tab structure is disposed between the first surface and the wound structure. Along the length of the electrode assembly, a distance D1 is defined between the first surface and the wound structure, while a distance D2 is defined between the second surface and the wound structure, with D1 being greater than D2.

[0005] Compared to the second cavity of the housing, which does not have a multi-pole lug structure, the multi-pole lug structure has more lugs and needs to be connected to an adapter to lead out the polarity, so more space is required within the first cavity. By having the first cavity protrude from the second cavity, the space on the multi-pole lug side of the first cavity is larger to accommodate the multi-pole lug structure. By having the second cavity recessed from the first cavity, the space on the multi-pole lug side of the second cavity is reduced, thereby reducing unused space within the housing, thereby improving space utilization and reducing the volume of the secondary battery while maintaining the battery capacity, thereby increasing the volumetric energy density of the secondary battery.

[0006] In at least one embodiment, ΔD is defined as D1-D2, and 0.5 mm ≤ ΔD ≤ 10 mm. ΔD ≥ 0.5 mm ensures sufficient space between the first surface and the wound structure to accommodate the multi-electrode structure. ΔD ≤ 10 mm prevents the distance between the first surface and the wound structure from being too large, thereby minimizing the impact on the overall volume of the secondary battery and reducing the loss of volumetric energy density of the secondary battery.

[0007] In at least one embodiment, 1mm≤ΔD≤2.4mm. Within this range, sufficient space is provided for the multi-tab structure, while minimizing the volumetric energy density loss of the secondary battery. Furthermore, ΔD is not too large, which improves the regularity of the secondary battery's shape.

[0008] In at least one embodiment, the width of the first surface along the width direction of the electrode assembly is W, and 8 mm ≤ W ≤ 25 mm. W ≥ 8 mm ensures sufficient width to accommodate a multi-tab structure. W ≤ 25 mm prevents the first surface from being too wide, minimizing the volume of the housing, improving the space utilization of the housing, and reducing the volumetric energy density loss of the secondary battery.

[0009] In at least one embodiment, the electrode assembly includes a first pole tab group and a second pole tab group, the adapter includes a first adapter, the first pole tab group and the second pole tab group are located on the same side of the length direction of the electrode assembly, the first pole tab group is a multi-pole tab structure, the first pole tab group includes multiple first pole tabs, the first pole tab group is electrically connected to the first pole piece and the first adapter; the second pole tab group is a single pole tab structure, the second pole tab group is a single second pole tab, and the second pole tab group is electrically connected to the second pole piece; along the length direction of the electrode assembly, part of the single pole tab structure is located between the second surface and the winding structure, and part of the single pole tab structure passes through the second surface and extends out of the shell.

[0010] Compared with the case where both the first pole tab group and the second pole tab group are single pole tab structures, setting the first pole tab group to a multi-pole tab structure and the second pole tab group to a single pole tab structure can improve the charging rate while setting the width of the first surface to be smaller, thereby reducing the occupied space and improving the energy density.

[0011] In at least one embodiment, along the width direction of the electrode assembly, the width W of the first surface is 8 mm ≤ W ≤ 18 mm.

[0012] Within this range, not only can sufficient accommodation space be provided for the first tab group, but the first surface is also prevented from being too wide, thereby improving the space utilization between the first surface and the winding structure, reducing the volume of the secondary battery, and improving the volume energy density of the secondary battery.

[0013] In at least one embodiment, one first tab group is provided, and several second tab groups are provided; when viewed along the thickness direction of the electrode assembly, the first tab group and the several second tab groups are distributed in sequence along the width direction of the electrode assembly.

[0014] By providing multiple second tab groups, the charging rate of the secondary battery can be further improved; and the number of single tab structures is greater than the number of multi-tab structures, which can reduce the space occupied by the protruding part of the first cavity, thereby helping to reduce the overall volume of the secondary battery.

[0015] In at least one embodiment, the first tab in the first tab group is an anode tab, and the second tab in the second tab group is a cathode tab.

[0016] If both the anode and cathode tabs are multi-pole tab structures, the charge rate is further improved, but the improvement is not large, and a wider first surface is required, resulting in a loss of volume energy density of the secondary battery. Compared with the solution in which only the anode tab is set to a multi-pole tab structure, the charge rate improvement effect is not obvious when only the cathode tab is a multi-pole tab structure. This solution sets only the anode tab to a multi-pole tab structure and the cathode tab to a single-pole tab structure. While ensuring a large charge rate, the width of the first surface is not too wide, thereby taking into account the setting of the charge rate and the width of the first surface, and having good charge rate and energy density benefits.

[0017] In at least one embodiment, the electrode assembly includes a first pole tab group and a second pole tab group, the first pole tab group and the second pole tab group are located on the same side of the length direction of the electrode assembly, the first pole tab group is electrically connected to the first pole sheet, and the second pole tab group is electrically connected to the second pole sheet; the first pole tab group and the second pole tab group are both multi-pole tab structures; the first pole tab group includes multiple first pole tabs, and the second pole tab group includes multiple second pole tabs; observed along the thickness direction of the electrode assembly, the first pole tab group and the second pole tab group are distributed in sequence along the width direction of the electrode assembly.

[0018] By configuring both the first tab group and the second tab group to have a multi-tab structure, the charge rate of the secondary battery can be increased.

[0019] In at least one embodiment, along the width direction of the electrode assembly, the width W of the first surface is 15 mm ≤ W ≤ 25 mm.

[0020] When W is ≤ 25 mm, the first surface is limited to a small width, minimizing the space occupied by the protruding portion of the first cavity and reducing the volume of the secondary battery. When W is ≥ 15 mm, the first cavity is wide enough to accommodate two multi-tab structures. The first and second tab groups do not overlap in the thickness direction of the electrode assembly, thereby reducing the overall thickness of the electrode assembly.

[0021] An embodiment of the present application further provides an electronic device, comprising the secondary battery in any of the above embodiments.

[0022] By arranging a first cavity protruding from a second cavity in the secondary battery, the space of the first cavity on the side of the multi-pole lug structure is larger to facilitate accommodating the multi-pole lug structure; and the second cavity is arranged to be recessed in the first cavity, reducing the space of the second cavity on the side of the multi-pole lug structure, thereby reducing the unused space in the shell, that is, improving the space utilization rate, and reducing the volume of the secondary battery while keeping the battery capacity unchanged, thereby improving the volume energy density of the secondary battery, thereby reducing the space occupied by the secondary battery on the electronic device, and helping to reduce the overall volume of the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a perspective view of a secondary battery in one embodiment of the present application.

[0024] Figure 2 is an exploded view of a secondary battery in one embodiment of the present application.

[0025] Figure 3 is a cross-sectional view of an electrode assembly in one embodiment of the present application.

[0026] Figure 4 1 is a top view of a secondary battery in one embodiment of the present application.

[0027] Figure 5 1 is a top view of a secondary battery in one embodiment of the present application.

[0028] Figure 6 1 is a top view of a secondary battery in one embodiment of the present application.

[0029] Figure 7 is a schematic diagram of an electronic device in one embodiment of the present application.

[0030] Description of main component symbols 100. Secondary battery; 10. Electrode assembly; 10a. Winding structure; 10b. Multi-tab structure; 10c. Single-tab structure; 11. First pole piece; 12. Second pole piece; 13. Diaphragm; 14. First pole piece group; 141. First pole piece; 1411. First portion; 1412. Second portion; 15. Second pole piece group; 151. Second pole piece; 1511. Sixth portion; 1512. Seventh portion; 16. Adapter; 161. First adapter; 162. Second adapter; 20. Housing; 20a. Main body; 20b. Sealing portion; 21. First cavity; 211. First surface; 22. Second cavity; 221. Second surface; X, first direction; Y, second direction; Z, third direction; 200. Electronic device; 201. Device body. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0032] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0033] In the wound multi-pole battery cell structure, the application rate requirements of different fast charging range from 80W to 120W. Based on different charging rate requirements, the battery head is provided with a single multi-pole structure or multiple multi-pole structures. The multi-pole structure includes multiple pole tabs stacked after winding the same pole piece. The multi-pole structure leads out the polarity through the form of transfer welding, resulting in a certain space between the pole tab and the battery head. This space is not fully utilized, which leads to the loss of volume energy density of the secondary battery.

[0034] An embodiment of the present application provides a secondary battery, comprising an electrode assembly and a housing. The electrode assembly comprises a first electrode sheet, a second electrode sheet, a diaphragm, and an adapter. The first electrode sheet, the diaphragm, and the second electrode sheet are stacked and wound together to form a wound structure, with the diaphragm disposed between the first and second electrode sheets. The electrode assembly further comprises a multi-pole tab structure, comprising a plurality of tabs stacked along the thickness of the electrode assembly. The multi-pole tab structure is electrically connected to the first electrode sheet and the adapter, or the multi-pole tab structure is electrically connected to the second electrode sheet and the adapter. The multi-pole tab structure and the adapter are disposed within a first cavity, while the multi-pole tab structure and the adapter are not disposed within a second cavity. Along the length of the electrode assembly, the first cavity protrudes from the second cavity on a side where the multi-pole tab structure is disposed and has a first surface. The second cavity is recessed relative to the first cavity on a side near the multi-pole tab structure and has a second surface. The length of the electrode assembly is perpendicular to the thickness of the electrode assembly. At least a portion of the multi-pole tab structure is disposed between the first surface and the wound structure. Along the length direction of the electrode assembly, the distance between the first surface and the winding structure is D1, and the distance between the second surface and the winding structure is D2, where D1>D2.

[0035] Compared to the second cavity of the housing, which does not have a multi-pole lug structure, the multi-pole lug structure has more lugs and needs to be connected to an adapter to lead out the polarity, so more space is required within the first cavity. By having the first cavity protrude from the second cavity, the space on the multi-pole lug side of the first cavity is larger to accommodate the multi-pole lug structure. By having the second cavity recessed from the first cavity, the space on the multi-pole lug side of the second cavity is reduced, thereby reducing unused space within the housing, thereby improving space utilization and reducing the volume of the secondary battery while maintaining the battery capacity, thereby increasing the volumetric energy density of the secondary battery.

[0036] The embodiments of the present application are further described below with reference to the accompanying drawings.

[0037] like Figure 1 、 Figure 2 and Figure 3 As shown, an embodiment of the present application provides a secondary battery 100, which includes an electrode assembly 10 and a housing 20. The electrode assembly 10 is accommodated in the housing 20. The electrode assembly 10 includes a first electrode sheet 11, a second electrode sheet 12, a diaphragm 13, and an adapter 16. The first electrode sheet 11, the diaphragm 13, and the second electrode sheet 12 are stacked and wound together to form a wound structure 10a. The diaphragm 13 is disposed between the first electrode sheet 11 and the second electrode sheet 12 to separate the first electrode sheet 11 from the second electrode sheet 12.

[0038] In some embodiments, the housing 20 is a flexible packaging bag, such as an aluminum-plastic film. In other embodiments, the housing 20 is a hard shell, such as a plastic shell, or a metal shell including at least one of steel alloy, aluminum alloy, and copper alloy.

[0039] In some embodiments, the housing 20 is an integrally formed structure.

[0040] In some embodiments, an electrolyte (not shown) is injected into the housing 20 , and the electrolyte components include a solvent, an electrolyte salt, and an additive.

[0041] In some embodiments, the electrolyte salt includes at least one of an organic lithium salt or an inorganic lithium salt.

[0042] In some embodiments, the electrolyte salt includes but is not limited to at least one of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide LiN(CF3SO2)2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO2F)2) (LiFSI), lithium hexafluorocesium oxide (LiCsF6), lithium perchlorate (LiClO4) or lithium trifluoromethanesulfonate (LiCF3SO3).

[0043] In some embodiments, the first electrode 11 and the second electrode 12 have different polarities. For example, the first electrode 11 is an anode electrode and the second electrode 12 is a cathode electrode. For another example, the first electrode 11 is a cathode electrode and the second electrode 12 is an anode electrode.

[0044] See also Figure 3 In some embodiments, the first electrode 11 includes a first current collector and a first active material layer, the first active material layer is arranged on two surfaces of the first current collector along the thickness direction of the first current collector, and the diaphragm 13 is arranged between the first active material layer and the second electrode 12.

[0045] See also Figure 2 In some embodiments, the second pole piece 12 includes a second current collector and a second active material layer. The thickness direction of the second pole piece 12 is consistent with the thickness direction of the second current collector. The second active material layer is disposed on both surfaces of the second current collector along the thickness direction of the second current collector.

[0046] In some embodiments, a secondary battery 100 includes a first electrode sheet 11, two separators 13, and a second electrode sheet 12. The two separators 13 are respectively a first separator and a second separator. The first electrode sheet 11 is a cathode electrode sheet, and the second electrode sheet 12 is an anode electrode sheet. The first electrode sheet 11, the first separator, the second electrode sheet 12, and the second separator are stacked and wound in sequence to form a wound structure 10a.

[0047] See also Figure 2 and Figure 3In some embodiments, the electrode assembly 10 of the wound structure 10a further includes a first electrode tab 141 and a second electrode tab 151 , wherein the first electrode tab 141 is connected to the first current collector; and the second electrode tab 151 is connected to the second current collector.

[0048] Taking the first electrode piece 11 as an anode electrode piece and the second electrode piece 12 as a cathode electrode piece as an example, the first current collector and the second current collector can be metal layers. The first current collector can be a metal layer including at least one of copper, nickel, tantalum, titanium, etc., such as copper foil. The second current collector can be a metal layer including at least one of aluminum, nickel, tantalum, titanium, etc., such as aluminum foil.

[0049] Taking the first electrode 11 as an anode electrode and the second electrode 12 as a cathode electrode as an example, the polarity of the first active material layer is anodic, and the first active material layer includes an anode active material. The anode active material may include at least one of graphite, hard carbon, soft carbon, silicon, silicon-oxygen material, silicon-carbon material, etc. The polarity of the second active material layer is cathodic, and the second active material layer includes a cathode active material. The cathode active material may include at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese iron phosphate, or lithium manganese oxide, etc.

[0050] See also Figure 2 and Figure 3 In some embodiments, the electrode assembly 10 further includes a multi-pole tab structure 10 b, which is connected to the first pole piece 11 or the second pole piece 12 . The multi-pole tab structure 10 b includes a plurality of pole tabs stacked along the thickness direction of the electrode assembly 10 .

[0051] The multi-tab structure 10 b is electrically connected to the first pole piece 11 and the adapter 16 , respectively. Alternatively, the multi-tab structure 10 b is electrically connected to the second pole piece 12 and the adapter 16 , respectively.

[0052] The housing 20 includes a first cavity 21 and a second cavity 22. The multi-tab structure 10b and the adapter 16 are disposed within the first cavity 21, while the multi-tab structure 10b and the adapter 16 are not disposed within the second cavity 22. Along the length of the electrode assembly 10, the first cavity 21 protrudes from the second cavity 22 on the side where the multi-tab structure 10b is disposed and has a first surface 211. The second cavity 22 is recessed relative to the first cavity 21 on the side near the multi-tab structure 10b and has a second surface 221. The length direction of the electrode assembly 10 is perpendicular to the thickness direction of the electrode assembly 10. At least a portion of the multi-tab structure 10b is disposed between the first surface 211 and the wound structure 10a. The length direction of the electrode assembly 10 is a first direction X, and the thickness direction is a second direction Y.

[0053] See also Figure 4Along the length direction of the electrode assembly 10 , the distance between the first surface 211 and the wound structure 10 a is D1 , and the distance between the second surface 221 and the wound structure 10 a is D2 , where D1 > D2 .

[0054] It can be understood that in the secondary battery 100, the number of tabs is positively correlated with the charge rate. During charging, current flows from the external circuit through the tabs into or out of the current collector of the electrode. In a single-tab design, current can only flow from the tab position along the length or width of the current collector to the entire electrode active material area. The current collector itself has a certain resistance (ohmic resistance). The farther away from the tab, the greater the path resistance, and the more difficult it is for the current to reach that area. The multi-tab design means that current can enter or flow out of the current collector from multiple points, which greatly shortens the average path length for the current to reach any point, significantly reducing the ohmic resistance on the entire current collector, thereby improving the charge rate of the secondary battery 100.

[0055] Compared to the second cavity 22 of the housing 20, which does not contain the multi-pole lug structure 10b, the multi-pole lug structure 10b has a larger number of lugs and needs to be connected to the adapter 16 to lead out the polarity. Therefore, more space is required within the first cavity 21. By arranging the first cavity 21 to protrude from the second cavity 22, the space on the side of the multi-pole lug structure 10b in the first cavity 21 is larger to accommodate the stacked multi-pole lug structure 10b. By arranging the second cavity 22 to be recessed in the first cavity 21, the space on the side of the multi-pole lug structure 10b in the second cavity 22 is reduced, thereby reducing the unused space within the housing 20, that is, improving space utilization. While maintaining the battery capacity, the volume of the secondary battery 100 is reduced, thereby improving the volumetric energy density of the secondary battery 100.

[0056] In some embodiments, the interior space of the first cavity 21 and the interior space of the second cavity 22 together constitute an accommodation space, and the wound structure 10a is located in the accommodation space. For example, the first cavity 21 and the second cavity 22 are connected along the width direction of the electrode assembly 10 to form the accommodation space, and the width direction of the electrode assembly 10 is the third direction Z.

[0057] In some embodiments, the first cavity 21 and the second cavity 22 are integrally provided. In other embodiments, the first cavity 21 and the second cavity 22 may also be connected by welding.

[0058] See also Figure 1 In some embodiments, the first cavity 21 and the second cavity 22 together form the main body 20a of the shell 20. The shell 20 also includes a sealing portion 20b, which is arranged around the edge of the main body 20a to ensure the sealing of the internal space of the shell 20.

[0059] See also Figure 2In some embodiments, the tabs of the multi-tab structure 10b are connected to the electrode sheets by welding. The phrase "at least a portion of the multi-tab structure 10b is disposed between the first surface 211 and the wound structure 10a" can be understood as meaning that the tabs of the multi-tab structure 10b include a first portion 1411 and a second portion 1412, a portion of the first portion 1411 is welded to the first electrode sheet 11 or the second electrode sheet 12, and the second portion 1412 is stacked between the wound structure 10a and the first surface 211.

[0060] In some embodiments, the tabs of the multi-tab structure 10b are formed by die-cutting on the pole piece. In this case, "at least a portion of the multi-tab structure 10b is disposed between the first surface 211 and the wound structure 10a" can be understood as meaning that the entire multi-tab structure 10b is disposed between the first surface 211 and the wound structure 10a.

[0061] In some embodiments, the adapter 16 is a conductor, connected to the multi-electrode structure 10b within the housing 20, and extending outside the housing 20. The adapter 16 is used to electrically lead the first electrode 11 or the second electrode 12. For example, the adapter 16 is a metal sheet.

[0062] In some embodiments, ΔD is defined as D1-D2, with 0.5 mm ≤ ΔD ≤ 10 mm. For example, ΔD can be, but is not limited to, any of 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm. ΔD ≥ 0.5 mm ensures sufficient space between the first surface 211 and the wound structure 10 a to accommodate the multi-tab structure 10 b. ΔD ≤ 10 mm prevents the distance between the first surface 211 and the wound structure 10 a from being too large, minimizing the impact on the overall volume of the secondary battery 100 and reducing the loss of volumetric energy density of the secondary battery 100.

[0063] In some embodiments, 1mm≤ΔD≤2.4mm. For example, ΔD can be, but is not limited to, any of 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, and 2.4mm. Within this range, while providing sufficient space for the multi-tab structure 10b, the volume of the secondary battery 100 is minimized, minimizing the loss of volumetric energy density of the secondary battery 100. Furthermore, a relatively small ΔD can improve the regularity of the shape of the secondary battery 100.

[0064] In some embodiments, the width of the first surface 211 along the width direction of the electrode assembly 10 is W, and 8 mm ≤ W ≤ 25 mm. For example, W can be, but is not limited to, any one of 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, and 25 mm.

[0065] W ≥ 8 mm ensures that the width is sufficient to accommodate the multi-tab structure 10 b. W ≤ 25 mm prevents the first surface 211 from being too wide, minimizing the volume of the housing 20 , improving the space utilization of the housing 20 , and reducing the volume energy density loss of the secondary battery 100 .

[0066] See also Figure 2 and Figure 4 In some embodiments, the electrode assembly 10 includes a first electrode tab group 14 and a second electrode tab group 15, and the adapter 16 includes a first adapter 161. The first electrode tab group 14 and the second electrode tab group 15 are located on the same side of the length direction of the electrode assembly 10. The first electrode tab group 14 is a multi-electrode tab structure 10b, and the first electrode tab group 14 includes multiple first electrode tabs 141. The first electrode tab group 14 is electrically connected to the first electrode sheet 11 and the first adapter 161; the second electrode tab group 15 is a single electrode tab structure 10c, and the second electrode tab group 15 is a single second electrode tab 151. The second electrode tab group 15 is electrically connected to the second electrode sheet 12; along the length direction of the electrode assembly 10, part of the single electrode tab structure 10c is located between the second surface 221 and the winding structure 10a, and part of the single electrode tab structure 10c passes through the second surface 221 and extends out of the shell 20. In some embodiments, there may be multiple second tab groups 15 , and the multiple second tab groups 15 may be stacked or separately arranged, with some of the second tab groups 15 being located between the winding structure 10 a and the second surface 221 .

[0067] Compared with the case where both the first tab group 14 and the second tab group 15 are single-pole tab structures 10c, setting the first tab group 14 to a multi-pole tab structure 10b and the second tab group 15 to a single-pole tab structure 10c can improve the charging rate while setting the width of the first surface 211 to be smaller, thereby reducing the occupied space and improving the energy density.

[0068] In some embodiments, the first electrode tab 141 is an anode electrode tab, and the second electrode tab 151 is a cathode electrode tab. Alternatively, the first electrode tab 141 is a cathode electrode tab, and the second electrode tab 151 is an anode electrode tab.

[0069] In some embodiments, the second electrode tab 151 in the single-pole tab structure 10c is connected to the second electrode sheet 12 by welding. "A portion of the single-pole tab structure 10c is located between the second surface 221 and the wound structure 10a" can be understood as the second electrode tab 151 including a third portion, a fourth portion, and a fifth portion, the third portion being welded to the second electrode sheet 12, the fourth portion being located between the second surface 221 and the wound structure 10a, and the fifth portion passing through the second surface 221 and extending outside the housing 20.

[0070] In some embodiments, the second tab 151 in the single-pole tab structure 10c is formed by die-cutting the second pole piece 12. The phrase "a portion of the single-pole tab structure 10c is located between the second surface 221 and the wound structure 10a" can be understood as meaning that the second tab 151 of the second tab assembly 15 includes a sixth portion 1511 and a seventh portion 1512, wherein the sixth portion 1511 is connected to the second pole piece 12, and the seventh portion 1512 passes through the second surface 221 and extends outside the housing 20.

[0071] Furthermore, along the width direction of the electrode assembly 10, the width W of the first surface 211 is 8 mm ≤ W ≤ 18 mm. For example, W can be, but is not limited to, any one of 8 mm, 9 mm, 11 mm, 13 mm, 15 mm, 17 mm, and 18 mm. Within this range, sufficient space is provided for the first tab assembly 14, and the first surface 211 is prevented from being too wide, thereby improving the space utilization between the first surface 211 and the wound structure 10 a, reducing the volume of the secondary battery 100, and improving the volumetric energy density of the secondary battery 100.

[0072] In some embodiments, there is one first tab group 14 and several second tab groups 15, that is, one multi-tab structure 10b and several single-tab structures 10c. When viewed along the thickness direction of the electrode assembly 10, the first tab group 14 and several second tab groups 15 are distributed in sequence along the width direction of the electrode assembly 10. For example Figure 5 In the embodiment, two single-pole lug structures 10c are provided. It is understandable that three, four, five, etc. single-pole lug structures 10c may also be provided.

[0073] By providing multiple second tab groups 15, the charge rate of the secondary battery 100 can be further improved. Furthermore, the number of single tab structures 10c is greater than the number of multi-tab structures 10b. While improving the charge rate of the secondary battery 100, no additional space is occupied in the first cavity 21, thereby facilitating a reduction in the overall volume of the secondary battery 100. The first tab group 14 and the plurality of second tab groups 15 do not overlap in the thickness direction of the electrode assembly 10, thereby facilitating a reduction in the thickness of the electrode assembly 10.

[0074] In the embodiment where only the first tab group 14 is a multi-tab structure 10 b , the first tab 141 in the first tab group 14 is an anode tab, and the second tab 151 in the second tab group 15 is a cathode tab.

[0075] If both the anode tab and the cathode tab are multi-pole tab structures 10b, the charge rate is further improved, but the improvement is not large, and a wider first surface 211 needs to be provided, resulting in a loss of volume energy density of the secondary battery 100. Due to the difference in ion migration rate, compared with the solution in which only the anode tab is set to the multi-pole tab structure 10b, the charge rate improvement effect is not obvious when only the cathode tab is set to the multi-pole tab structure 10b. This solution only sets the anode tab to the multi-pole tab structure 10b and the cathode tab to the single-pole tab structure 10c. While ensuring a larger charge rate, the width of the first surface 211 will not be too wide, thereby taking into account the setting of the charge rate and the width of the first surface 211, and having good charge rate and energy density benefits.

[0076] See also Figure 6 In some embodiments, the electrode assembly 10 includes a first electrode tab group 14 and a second electrode tab group 15, and the first electrode tab group 14 and the second electrode tab group 15 are located on the same side in the length direction of the electrode assembly 10. The first electrode tab group 14 is electrically connected to the first electrode sheet 11, and the second electrode tab group 15 is electrically connected to the second electrode sheet 12. The first electrode tab group 14 and the second electrode tab group 15 are both multi-electrode tab structures 10b. The first electrode tab group 14 includes a plurality of first electrode tabs 141, and the second electrode tab group 15 includes a plurality of second electrode tabs 151. When viewed along the thickness direction of the electrode assembly 10, the first electrode tab group 14 and the second electrode tab group 15 are distributed sequentially along the width direction of the electrode assembly 10. The adapter 16 includes a first adapter 161 and a second adapter 162. The first adapter 161 is connected to the first electrode tab group 14, and the second adapter 162 is connected to the second electrode tab group 15.

[0077] By configuring both the first tab group 14 and the second tab group 15 as a multi-tab structure 10b, the charge rate of the secondary battery 100 can be further improved compared to a solution in which only the first tab group 14 is a multi-tab structure 10b. Furthermore, the first tab group 14 and the second tab group 15 do not overlap in thickness in the thickness direction of the electrode assembly 10, thereby facilitating a reduction in the thickness of the electrode assembly 10.

[0078] Furthermore, along the width direction of the electrode assembly 10, the width W of the first surface 211 is 15 mm ≤ W ≤ 25 mm. For example, W can be, but is not limited to, any one of 15 mm, 17 mm, 19 mm, 21 mm, 23 mm, and 25 mm.

[0079] When W is ≤ 25 mm, the first surface 211 is not too wide, thus reducing the space occupied by the first surface 211 and the volume of the secondary battery 100. When W is ≥ 15 mm, the first cavity 21 has a first surface 211 that is sufficiently wide to accommodate two multi-tab structures 10 b. The first tab group 14 and the second tab group 15 do not overlap in the thickness direction of the electrode assembly 10, thereby reducing the overall thickness of the electrode assembly 10.

[0080] See also Figure 7 , an embodiment of the present application further provides an electronic device 200, which includes the secondary battery 100 in any of the above embodiments.

[0081] By arranging the first cavity 21 protruding from the second cavity 22 in the secondary battery 100, the space of the first cavity 21 on the side of the multi-pole lug structure 10b is larger to facilitate accommodating the multi-pole lug structure 10b; and the second cavity 22 is arranged to be recessed in the first cavity 21, reducing the space of the second cavity 22 on the side of the multi-pole lug structure 10b, thereby reducing the unused space in the shell 20, that is, improving the space utilization rate, and reducing the volume of the secondary battery 100 while keeping the battery capacity unchanged, thereby improving the volume energy density of the secondary battery 100, thereby reducing the space occupied by the secondary battery 100 on the electronic device 200, which is conducive to reducing the overall volume of the electronic device 200.

[0082] In some embodiments, the electronic device 200 may be a mobile phone, a laptop computer, a tablet computer, a drone, a power tool, a power toy, a game console, a video recorder, a portable recorder, a radio, or a smart watch, etc., which are not listed here one by one.

[0083] In some embodiments, the electronic device 200 further includes a device body 201, and the secondary battery 100 is installed in the device body 201. Since the electronic device 200 adopts the technical solution of the secondary battery 100 in any of the above embodiments, it has at least the beneficial effects brought about by the technical solution of any of the above embodiments of the secondary battery 100, which will not be described in detail here.

[0084] In addition, those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments are within the scope of disclosure of the present application.

Claims

1. A secondary battery, characterized in that: include: An electrode assembly, the electrode assembly comprising a first electrode piece, a second electrode piece, a diaphragm, and a transition piece, wherein the first electrode piece, the diaphragm, and the second electrode piece are stacked and wound together to form a wound structure, and the diaphragm is disposed between the first electrode piece and the second electrode piece; the electrode assembly further comprises a multi-pole tab structure, the multi-pole tab structure comprising a plurality of electrode tabs stacked along a thickness direction of the electrode assembly, the multi-pole tab structure being electrically connected to the first electrode piece and the transition piece, respectively, or the multi-pole tab structure being electrically connected to the second electrode piece and the transition piece, respectively; A shell, the shell comprising a first cavity and a second cavity, the winding structure being located in the first cavity and the second cavity; the multi-pole lug structure and the adapter being disposed in the first cavity, and the multi-pole lug structure and the adapter not being disposed in the second cavity; along the length direction of the electrode assembly, the first cavity protrudes from the second cavity on a side where the multi-pole lug structure is disposed and has a first surface, and the second cavity is recessed relative to the first cavity on a side close to the multi-pole lug structure and has a second surface, and the length direction of the electrode assembly is perpendicular to the thickness direction of the electrode assembly; At least a portion of the multi-tab structure is disposed between the first surface and the winding structure; Along the length direction of the electrode assembly, the distance between the first surface and the winding structure is D1, and the distance between the second surface and the winding structure is D2, where D1>D2.

2. The secondary battery according to claim 1, wherein Define △D=D1-D2, 0.5mm≤△D≤10mm.

3. The secondary battery according to claim 2, wherein 1mm≤△D≤2.4mm.

4. The secondary battery according to claim 1, wherein Along the width direction of the electrode assembly, the width of the first surface is W, 8 mm ≤ W ≤ 25 mm.

5. The secondary battery according to claim 1, wherein The electrode assembly includes a first pole tab group and a second pole tab group, the adapter includes a first adapter, the first pole tab group and the second pole tab group are located on the same side in the length direction of the electrode assembly, the first pole tab group is the multi-pole tab structure, the first pole tab group includes multiple first pole tabs, the first pole tab group is electrically connected to the first pole sheet and the first adapter; the second pole tab group is a single pole tab structure, the second pole tab group is a single second pole tab, and the second pole tab group is electrically connected to the second pole sheet; along the length direction of the electrode assembly, part of the single pole tab structure is located between the second surface and the winding structure, and part of the single pole tab structure passes through the second surface and extends out of the shell.

6. The secondary battery according to claim 5, wherein Along the width direction of the electrode assembly, the width W of the first surface is 8 mm ≤ W ≤ 18 mm.

7. The secondary battery according to claim 5, wherein There is one first electrode tab group and several second electrode tab groups; when viewed along the thickness direction of the electrode assembly, the first electrode tab group and several second electrode tab groups are distributed in sequence along the width direction of the electrode assembly.

8. The secondary battery according to claim 5, wherein The first electrode tab in the first electrode tab group is an anode electrode tab, and the second electrode tab in the second electrode tab group is a cathode electrode tab.

9. The secondary battery according to claim 1, wherein The electrode assembly includes a first tab group and a second tab group, the adapter includes a first adapter and a second adapter, the first tab group and the second tab group are located on the same side of the length direction of the electrode assembly, the first tab group is electrically connected to the first pole piece and the first adapter, respectively, and the second tab group is electrically connected to the second pole piece and the second adapter, respectively; the first tab group and the second tab group are both multi-tab structures; the first tab group includes a plurality of first tabs, and the second tab group includes a plurality of second tabs; Observing along the thickness direction of the electrode assembly, the first electrode tab group and the second electrode tab group are sequentially distributed along the width direction of the electrode assembly.

10. The secondary battery according to claim 9, wherein Along the width direction of the electrode assembly, the width W of the first surface is 15 mm ≤ W ≤ 25 mm.

11. An electronic device, characterized in that: The secondary battery according to any one of claims 1 to 10 is included.

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