Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a secondary battery, a battery pack and an electronic device. The secondary battery comprises a shell and an electrode assembly accommodated in the shell, wherein the electrode assembly comprises a winding structure formed by laminating and winding a positive plate, a diaphragm and a negative plate; a positive current collector of the positive plate comprises a positive coated region and a positive uncoated region, and a negative current collector of the negative plate comprises a negative coated region and a negative uncoated region; the positive electrode uncoated area comprises a positive electrode lug and a positive electrode connecting area, and the negative electrode uncoated area comprises a negative electrode lug and a negative electrode connecting area; wherein at least partial area of the positive electrode connecting area and / or the negative electrode connecting area is covered with a ceramic insulating layer, and the value range of the material particle size D of the ceramic insulating layer is 1.5 [mu] m < D < 4.0 [mu] m. By arranging the ceramic insulating layer of which the material particle size is in a specific value range, the porosity of the pole piece can be increased, the liquid retention capacity of the pole piece can be improved, and the quick charge and long-term performance of the secondary battery can be optimized on the premise of ensuring that the quick charge capacity of the secondary battery is not deteriorated.

Description

Technical Field

[0001] The utility model relates to a secondary battery, a battery pack and an electronic device. Background Art

[0002] The fast charging performance of cylindrical batteries is affected by their structure and the amount of free electrolyte on both sides of the core. Excessive free electrolyte will cause the fast charging of the battery cell to fail. Utility Model Content

[0003] The technical problem to be solved by the present invention is to overcome the defect in the prior art that there is too much free electrolyte on both sides of the winding core, which will lead to failure of fast charging of the battery cell, and to provide a secondary battery, a battery pack and an electronic device.

[0004] The utility model solves the above technical problems through the following technical solutions:

[0005] A secondary battery, characterized in that it comprises:

[0006] case;

[0007] an electrode assembly housed in the housing, the electrode assembly comprising a wound structure formed by stacking and winding a positive electrode sheet, a separator, and a negative electrode sheet; the positive electrode sheet comprising a positive electrode current collector, and the negative electrode sheet comprising a negative electrode current collector; along the axial direction of the wound structure, the positive electrode current collector comprising a positive electrode coating region covered by the positive electrode active material layer and a positive electrode uncoated region not covered by the positive electrode active material layer; and the negative electrode current collector comprising a negative electrode coating region covered by the negative electrode active material layer and a negative electrode uncoated region not covered by the negative electrode active material layer;

[0008] The direction from the positive electrode coated area to the positive electrode uncoated area is a first direction, and the direction from the negative electrode coated area to the negative electrode uncoated area is a second direction; along the first direction, the positive electrode uncoated area includes a positive electrode tab and a positive electrode connection area connected between the positive electrode tab and the positive electrode coated area; along the second direction, the negative electrode uncoated area includes a negative electrode tab and a negative electrode connection area connected between the negative electrode tab and the negative electrode coated area;

[0009] Wherein, at least a portion of the positive electrode connection region and / or the negative electrode connection region is covered with a ceramic insulating layer, and the particle size D of the material of the ceramic insulating layer is in the range of 1.5 μm<D<4.0 μm.

[0010] In this technical solution, by setting the ceramic insulating layer and the range of values ​​of the material particle size of the ceramic insulating layer, the porosity of the electrode can be increased, the liquid retention capacity of the electrode can be improved, and the fast charging and long-term performance of the secondary battery can be optimized while ensuring that the fast charging capability of the secondary battery (battery cell) does not deteriorate.

[0011] Preferably, the material of the ceramic insulating layer is porous alumina.

[0012] Preferably, along the radial direction of the winding structure, the negative electrode connection area includes a first negative electrode connection side facing away from the center hole of the winding structure and a second negative electrode connection side facing the center hole, wherein at least a partial area of ​​the first negative electrode connection side and / or the second negative electrode connection side is covered with the ceramic insulating layer.

[0013] Preferably, the ceramic insulating layer covers the entire area of ​​the first negative electrode connection side of the negative electrode connection area; and / or,

[0014] The ceramic insulating layer covers the entire area of ​​the second negative electrode connection side of the negative electrode connection area; and / or,

[0015] Along the second direction, the maximum width of the ceramic insulating layer is greater than or equal to the width of the negative electrode connecting region.

[0016] Preferably, along the second direction, the width of the ceramic insulating layer covering the negative electrode connection area is in the range of 0.1 mm to 2 mm.

[0017] Preferably, the maximum thickness of the ceramic insulating layer is 30%-50% of the maximum thickness of the negative electrode active material layer.

[0018] Preferably, along the second direction, one side of the ceramic insulating layer overlaps or abuts against the outer edge of the negative electrode coating region, and the other side of the ceramic insulating layer is parallel to the outer edge of the negative electrode coating region.

[0019] Preferably, along the radial direction of the winding structure, the positive electrode connection area includes a first positive electrode connection side facing away from the center hole of the winding structure and a second positive electrode connection side facing the center hole, wherein at least a partial area of ​​the first positive electrode connection side and / or the second positive electrode connection side is covered with the ceramic insulating layer.

[0020] Preferably, the ceramic insulating layer covers the entire area of ​​the first positive electrode connection side of the positive electrode connection area; and / or,

[0021] The ceramic insulating layer covers the entire area of ​​the second positive electrode connection side of the positive electrode connection area; and / or,

[0022] Along the first direction, the maximum width of the ceramic insulating layer is greater than or equal to the width of the positive electrode connecting area.

[0023] Preferably, the filling coefficient of the secondary battery is 1.3-1.4.

[0024] Preferably, the housing includes a surrounding side wall, one end of which is formed with an opening; the end of the housing close to the opening includes a crimping portion recessed toward the interior of the housing;

[0025] The secondary battery further includes:

[0026] a cover plate mounted on the opening;

[0027] an insulating seal, the insulating seal being arranged around the periphery of the cover plate to insulate and seal the cover plate and the housing;

[0028] a current collecting plate, disposed between the electrode assembly and the cover plate and electrically connected to the housing, wherein the connecting piece of the current collecting plate is located on a side of the crimping portion facing the electrode assembly and is welded to the crimping portion;

[0029] and / or,

[0030] The secondary battery is a cylindrical battery.

[0031] A battery pack is characterized by comprising the secondary battery described above.

[0032] An electronic device is characterized by comprising the battery pack as described above.

[0033] The positive progress effect of this utility model is:

[0034] The utility model increases the porosity of the electrode and improves the liquid retention capacity of the electrode by providing a ceramic insulating layer with a material particle size within a specific value range, thereby optimizing the fast charging and long-term performance of the secondary battery while ensuring that the fast charging capability of the secondary battery does not deteriorate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The figure is a schematic cross-sectional view of a secondary battery according to a preferred embodiment of the present invention.

[0036] Figure 2 for Figure 1 Schematic diagram of the locally enlarged structure of part A.

[0037] Figure 3 for Figure 1 Schematic diagram of the locally enlarged structure of part B.

[0038] Figure 4 This is a schematic diagram of the three-dimensional structure of an electrode assembly of a secondary battery according to a preferred embodiment of the present invention.

[0039] Figure 5 This is a partial cross-sectional structural diagram of an electrode assembly of a secondary battery according to a preferred embodiment of the present invention.

[0040] Figure 6 for Figure 5 Schematic diagram of the locally enlarged structure of part E.

[0041] Figure 7 for Figure 5 Schematic diagram of the locally enlarged structure of part F.

[0042] Figure 8 This is a partial cross-sectional structural diagram of a single-turn positive electrode sheet of a secondary battery according to a preferred embodiment of the present invention.

[0043] Figure 9 This is a schematic structural diagram of the positive electrode sheet of a secondary battery in a preferred embodiment of the present invention when it is not wound.

[0044] Figure 10 This is a partial cross-sectional structural diagram of a single-turn negative electrode sheet of a secondary battery according to a preferred embodiment of the present invention.

[0045] Figure 11 This is a schematic structural diagram of the negative electrode sheet of a secondary battery in a preferred embodiment of the present invention when it is not wound.

[0046] Figure 12 This is a table showing the change in liquid retention of a wound structure of a secondary battery according to a preferred embodiment of the present invention.

[0047] Figure 13 This is a schematic structural diagram of a battery pack according to a preferred embodiment of the present invention.

[0048] Figure 14 FIG. 1 is a structural diagram of an electronic device according to a preferred embodiment of the present invention.

[0049] Description of Reference Numerals

[0050] Electronic device 1000

[0051] Battery Pack 100

[0052] Working Department 300

[0053] Box 310

[0054] Box cover 320

[0055] Secondary battery 1

[0056] Housing 10

[0057] end wall 11

[0058] Side wall 12

[0059] Accommodating chamber 13

[0060] Opening 14

[0061] Electrode assembly 20

[0062] Winding structure 201

[0063] Center Hole 2011

[0064] Positive electrode 21

[0065] Positive electrode current collector 211

[0066] Positive electrode active material layer 2111

[0067] Positive electrode coating area 212

[0068] Positive electrode uncoated area 213

[0069] Positive electrode tab 2131

[0070] Positive connection area 2132

[0071] Diaphragm 22

[0072] Negative electrode 23

[0073] Negative electrode current collector 231

[0074] Negative electrode active material layer 2311

[0075] Negative electrode coating area 232

[0076] Negative electrode uncoated area 233

[0077] Negative electrode tab 2331

[0078] Negative electrode connection area 2332

[0079] Ceramic insulation layer 24

[0080] Crimping portion 30

[0081] Cover 40

[0082] Insulation seal 50

[0083] First collecting plate 61

[0084] Second collecting plate 62

[0085] Pole 70

[0086] Insulation 80

[0087] The axial direction P of the winding structure

[0088] Radial R of the winding structure

[0089] First direction Q1

[0090] Second direction Q2 DETAILED DESCRIPTION

[0091] A preferred embodiment is given below, and the present invention is described more clearly and completely in conjunction with the accompanying drawings.

[0092] The secondary battery in the prior art is affected by its structure, and the fast charging performance will be affected by the amount of free electrolyte on both sides of the winding core. Excessive free electrolyte will cause the fast charging of the battery cell to fail.

[0093] like Figures 1 to 3 As shown, this embodiment provides a secondary battery 1. The secondary battery 1 includes a housing 10 and an electrode assembly 20. The electrode assembly 20 is accommodated in the housing 10.

[0094] like Figures 4 to 11 As shown, the electrode assembly 20 includes a positive electrode sheet 21, a separator 22, and a negative electrode sheet 23 stacked and wound to form a wound structure 201. The positive electrode sheet 21 includes a positive current collector 211, and the negative electrode sheet 23 includes a negative current collector 231. Along the axial direction P of the wound structure 201, the positive current collector 211 includes a positive electrode coating area 212 covered by a positive electrode active material layer 2111 and a positive electrode uncoated area 213 not covered by the positive electrode active material layer 2111. The negative electrode current collector 231 includes a negative electrode coating area 232 covered by a negative electrode active material layer 2311 and a negative electrode uncoated area 233 not covered by the negative electrode active material layer 2311. The axial direction P of the wound structure 201 is in the same direction as the height of the wound structure 201.

[0095] The direction from the positive electrode coating area 212 to the positive electrode uncoated area 213 is the first direction Q1, and the direction from the negative electrode coating area 232 to the negative electrode uncoated area 233 is the second direction Q2; along the first direction Q1, the positive electrode uncoated area 213 includes a positive electrode tab 2131, and a positive electrode connection area 2132 connected between the positive electrode tab 2131 and the positive electrode coating area 212; along the second direction Q2, the negative electrode uncoated area 233 includes a negative electrode tab 2331, and a negative electrode connection area 2332 connected between the negative electrode tab 2331 and the negative electrode coating area 232.

[0096] At least a portion of the positive electrode connection region 2132 and / or the negative electrode connection region 2332 is covered with a ceramic insulating layer 24 , and a particle size D of the ceramic insulating layer 24 is in the range of 1.5 μm<D<4.0 μm.

[0097] In this way, by setting the ceramic insulating layer 24 and the range of values ​​of the material particle size of the ceramic insulating layer 24, the porosity of the electrode can be increased, the liquid retention capacity of the electrode can be improved, and the fast charging and long-term performance of the secondary battery 1 can be optimized while ensuring that the fast charging capability of the secondary battery 1 (battery cell) does not deteriorate.

[0098] In this embodiment, the material of the ceramic insulating layer 24 is porous alumina. In this way, by using porous alumina for the ceramic insulating layer 24, the liquid retention capacity of the wound structure 201 (winding core) can be increased without increasing the free electrolyte, and the cycle life of the secondary battery 1 can be optimized without deteriorating the fast charging performance of the secondary battery 1. In addition, compared with conventional alumina, the porosity of porous alumina is increased by 15%, and the increased porosity allows the wound structure 201 to accommodate more electrolyte. It should be noted that the porosity of conventional alumina is about 40%, while the porosity of porous alumina is greater than 60%. Therefore, compared with conventional alumina, the porosity of porous alumina can be increased by at least 15%, and the increased porosity allows the wound structure 201 to accommodate more electrolyte.

[0099] Furthermore, along the radial direction R of the wound structure 201, the negative electrode connection region 2332 includes a first negative electrode connection side facing away from the central hole 2011 of the wound structure 201 and a second negative electrode connection side facing the central hole 2011, wherein at least a portion of the first negative electrode connection side and / or the second negative electrode connection side is covered with a ceramic insulating layer 24. Thus, by covering at least a portion of the first negative electrode connection side and / or the second negative electrode connection side with a ceramic insulating layer 24, the liquid retention capacity of the wound structure 201 can be increased without increasing the free electrolyte, thereby optimizing the cycle life of the secondary battery 1 while ensuring that the fast charging performance of the secondary battery 1 is not deteriorated.

[0100] Please refer back to Figure 8 and Figure 9 In this embodiment, both the first and second negative electrode connection sides of the negative electrode connection area 2332 are covered with a ceramic insulating layer 24. However, this is not limiting. In other embodiments, only the first negative electrode connection side of the negative electrode connection area 2332 may be covered with a ceramic insulating layer 24, or only the second negative electrode connection side of the negative electrode connection area 2332 may be covered with a ceramic insulating layer 24. This can be adjusted according to design requirements.

[0101] Preferably, the ceramic insulating layer 24 covers the entire first negative electrode connection side of the negative electrode connection area 2332; the ceramic insulating layer 24 covers the entire second negative electrode connection side of the negative electrode connection area 2332; and along the second direction Q2, the maximum width of the ceramic insulating layer 24 is greater than or equal to the width of the negative electrode connection area 2332. This configuration maximizes the width of the ceramic insulating layer 24, maximizing liquid absorption and increasing the hardness of the negative electrode tab 2331. This prevents the negative electrode tab 2331 from being inserted into the battery during bending, thereby ensuring safety.

[0102] In this embodiment, the width W2 of the ceramic insulating layer 24 covering the negative electrode connection region 2332 along the second direction Q2 ranges from 0.1 mm to 2 mm, and can be, for example, 0.1 mm, 0.7 mm, 1.35 mm, 1.55 mm, 1.73 mm, or 2 mm. By setting the width W2 of the ceramic insulating layer 24 along the second direction Q2 within a certain range, the following configurations can be employed: 1. The width of the ceramic insulating layer 24 can be prevented from being too small, thereby preventing the winding structure 201 from having a liquid-retaining capacity increased; and 2. The following configurations can be employed: 2. The width of the ceramic insulating layer 24 can be prevented from being too large, thereby preventing the negative electrode tab 2331 from properly bending and properly electrically connecting to external conductive components.

[0103] Preferably, the maximum thickness of the ceramic insulating layer 24 is 30%-50% of the maximum thickness of the negative electrode active material layer 2311. By setting the ratio between the maximum thickness of the ceramic insulating layer 24 and the maximum thickness of the negative electrode active material layer 2311, the ceramic insulating layer 24 can be prevented from being too thin and thus failing to increase the liquid retention capacity of the wound structure 201. Furthermore, the ceramic insulating layer 24 can be prevented from being too thick and thus affecting the normal bending of the positive electrode tab 2131 and the normal electrical connection with external conductive components.

[0104] Along the second direction Q2, one side of the ceramic insulating layer 24 overlaps or abuts the outer edge of the negative electrode coating region 232, and the other side of the ceramic insulating layer 24 is parallel to the outer edge of the negative electrode coating region 232. Thus, by limiting the overlap or abutment of one side of the ceramic insulating layer 24 with the outer edge of the negative electrode coating region 232, that is, by positioning the ceramic insulating layer 24 as close as possible to the negative electrode coating region 232, the width of the ceramic insulating layer 24 can be maximized, thereby maximizing liquid absorption and increasing the hardness of the negative electrode tab 2331. By positioning the other side of the ceramic insulating layer 24 parallel to the outer edge of the negative electrode coating region 232, the outer edge of this side is aligned with the outer edge of the negative electrode coating region 232, thereby achieving uniform distribution of the electrolyte.

[0105] Preferably, along the radial direction R of the wound structure 201, the positive electrode connection region 2132 includes a first positive electrode connection side facing away from the central hole 2011 of the wound structure 201 and a second positive electrode connection side facing the central hole 2011, wherein at least a portion of the first positive electrode connection side and / or the second positive electrode connection side is covered with a ceramic insulating layer 24. Thus, by covering at least a portion of the first positive electrode connection side and / or the second positive electrode connection side with the ceramic insulating layer 24, the liquid retention capacity of the wound structure 201 can be increased without increasing the free electrolyte, thereby optimizing the cycle life of the secondary battery 1 while ensuring that the fast charging performance of the secondary battery 1 does not deteriorate.

[0106] Please refer back to Figure 10 and Figure 11In this embodiment, both the first and second positive electrode connection sides of the positive electrode connection area 2132 are covered with a ceramic insulating layer 24. However, this is not limiting. In other embodiments, only the first positive electrode connection side of the positive electrode connection area 2132 may be covered with a ceramic insulating layer 24, or only the second positive electrode connection side of the positive electrode connection area 2132 may be covered with a ceramic insulating layer 24. This can be adjusted according to design requirements.

[0107] Preferably, the ceramic insulating layer 24 covers the entire first positive electrode connection side of the positive electrode connection area 2132; the ceramic insulating layer 24 covers the entire second positive electrode connection side of the positive electrode connection area 2132; and along the first direction Q1, the maximum width of the ceramic insulating layer 24 is greater than or equal to the width of the positive electrode connection area 2132. This configuration maximizes the width of the ceramic insulating layer 24, maximizing liquid absorption and increasing the hardness of the positive electrode tab 2131. This prevents the tab 2131 from being inserted into the battery during bending, ensuring safety.

[0108] Along the first direction Q1, the width W1 of the ceramic insulating layer 24 covering the positive electrode connection area 2132 is in the range of 0.1 mm to 2 mm, and can be, for example, 0.1 mm, 0.7 mm, 1.35 mm, 1.55 mm, 1.73 mm, or 2 mm. By setting the width W1 of the ceramic insulating layer 24 along the first direction Q1 within this range, it is possible to prevent the width of the ceramic insulating layer 24 from being too small, thereby preventing the winding structure 201 from having a liquid-retaining capacity increased. Furthermore, it is possible to prevent the width of the ceramic insulating layer 24 from being too large, thereby preventing the positive electrode tab 2131 from properly bending and properly electrically connecting to external conductive components.

[0109] The thickness of the ceramic insulating layer 24 covering the positive electrode connection area 2132 and the negative electrode connection area 2332 is 5 μm to 30 μm, for example, 5 μm, 10 μm, 14 μm, 17.5 μm, 27 μm, or 30 μm. By setting a range of values ​​for the thickness of the ceramic insulating layer 24, on the one hand, it is prevented that the ceramic insulating layer 24 is too thin and fails to increase the liquid retention capacity of the wound structure 201; on the other hand, it is prevented that the ceramic insulating layer 24 is too thick and affects the normal bending of the tab and the normal electrical connection with external conductive components.

[0110] Please refer back to Figures 1 to 3In this embodiment, the shell 10 includes a surrounding side wall 12, and an opening 14 is formed at one end of the side wall 12; the end of the shell 10 near the opening 14 includes a crimping portion 30 that is recessed into the interior of the shell 10. The secondary battery 1 also includes: a cover plate 40, an insulating seal 50, and a current collecting plate. The cover plate 40 is installed in the opening 14. The insulating seal 50 is arranged around the periphery of the cover plate 40 to insulate and seal the cover plate 40 and the shell 10. The current collecting plate is arranged between the electrode assembly 20 and the cover plate 40, and is electrically connected to the shell 10. The connecting piece of the current collecting plate is located on the side of the crimping portion 30 facing the electrode assembly 20 and is welded to the crimping portion 30. In this way, by arranging the connecting piece of the collecting plate to be located on the side of the crimping portion 30 facing the electrode assembly 20 and being welded to the crimping portion 30, that is, the welding area between the collecting plate and the electrode tab is located at a position closer to the electrode assembly 20 than the crimping portion 30, the influence of the crimping portion 30 on the welding area between the electrode tab and the collecting plate can be prevented, thereby improving the welding strength between the electrode tab and the collecting plate.

[0111] Furthermore, the housing 10 includes an end wall 11, and a side wall 12 disposed around the end wall 11 and located at the end of the side wall 12 away from the opening 14. The end wall 11 and the side wall 12 enclose a housing cavity 13 within the housing 10 for accommodating the electrode assembly 20, electrolyte, and other essential battery components. The connection between the end wall 11 and the side wall 12 can be achieved in a variety of ways, such as integral stamping, integral casting, or separate welding.

[0112] The secondary battery 1 further includes a terminal post 70 , which passes through the end wall 11 and is insulated from the end wall 11 by an insulating member 80 .

[0113] The current collecting trays include a first collecting tray 61 and a second collecting tray 62. The first collecting tray 61 is disposed between the electrode assembly 20 and the cover plate 40, while the second collecting tray 62 is disposed between the electrode assembly 20 and the end wall 11. In this embodiment, the first collecting tray 61 corresponds to the positive electrode tab 2131, which is electrically connected to the electrode post 70 via the first collecting tray 61. The second collecting tray 62 corresponds to the negative electrode tab 2331, which is electrically connected to the housing 10 via the second collecting tray 62. However, this is not limiting. In other embodiments, the first collecting tray 61 may correspond to the negative electrode tab 2331, while the second collecting tray 62 may correspond to the positive electrode tab 2131.

[0114] The welding order of the first current collecting plate 61 and the second current collecting plate 62 of the secondary battery 1 in this embodiment and the electrode assembly 20 is as follows: first, place the first current collecting plate 61; then, press the electrode assembly 20 on both the positive and negative sides (the pressing process can increase the contact between the current collecting plate and the electrode assembly 20 and avoid cold welding); weld the first current collecting plate 61 by linear welding instead of spot welding. This is because the negative electrode tab 2331 is relatively soft. After two pressings, the distance between the second current collecting plate 62 and the electrode assembly 20 will be closer. Spot welding will cause the diaphragm 22 to be burned due to concentrated heat, while linear welding will cause less heat to avoid burning the diaphragm 22 and causing a short circuit between the positive and negative electrodes; then, place the second current collecting plate 62; press the electrode assembly 20 on both the positive and negative sides again; finally, weld the second current collecting plate 62.

[0115] In this embodiment, the secondary battery 1 is a cylindrical battery. Cylindrical batteries have advantages such as high energy density, long cycle life, and good safety performance. However, the present invention is not limited thereto. In other embodiments, the secondary battery 1 may also be a battery of other shapes, such as a square battery.

[0116] In this embodiment, the positive electrode tab 2131 is a cut-and-stacked tab. When welding the tabs to the current collector of a cylindrical battery, the tab pre-treatment steps include two different treatment methods: one is flattening the tab, and the other is the cut-and-stacked tab treatment used for the positive electrode tab 2131 in this embodiment. Similarly, the negative electrode tab 2331 is also a cut-and-stacked tab.

[0117] It should be noted that when the liquid filling coefficient of the secondary battery in the prior art is greater than 1.3, lithium deposition first occurs on one side of the negative electrode tab 2331, regardless of whether the battery is placed with the pole facing up or down. In other words, the negative electrode tab 2331 of the electrode assembly is more susceptible to corrosion. In this embodiment, the ceramic insulating layer 24 is preferentially disposed on one side of the negative electrode tab 2331 of the electrode assembly 20, that is, the ceramic insulating layer 24 is preferentially disposed in the negative electrode connection area 2332, to improve the liquid retention capacity of the negative electrode tab 2331 of the electrode assembly 20, thereby preventing lithium deposition on the negative electrode tab 2331.

[0118] Furthermore, the filling coefficient of the secondary battery 1 is 1.3-1.4. By setting the value range of the filling coefficient of the secondary battery 1, on the one hand, it is avoided that the filling coefficient is too large and the full charge capacity after multiple fast charges is reduced; on the other hand, it is avoided that the filling coefficient is too small and the performance of the secondary battery 1 cannot be guaranteed.

[0119] like Figure 12 As shown in the figure, the changes in the liquid retention of the winding structure of the secondary battery under different conditions are shown as follows:

[0120] Case 1: The liquid retention capacity of the wound structure of the secondary battery in the prior art, which is also the lowest among all cases;

[0121] Case 2: Only the positive electrode connection area of ​​the positive electrode sheet is covered with a ceramic insulating layer, and the material of the ceramic insulating layer is alumina. The liquid retention capacity of the wound structure in Case 2 is 0.2g higher than that of the wound structure in Case 1.

[0122] Case 3: Only the negative electrode connection area of ​​the negative electrode sheet is covered with a ceramic insulating layer, and the material of the ceramic insulating layer is alumina. The liquid retention capacity of the wound structure in Case 3 is 0.3g higher than that of the wound structure in Case 1.

[0123] Case 4: Only the negative electrode connection area of ​​the negative electrode sheet is covered with a ceramic insulating layer, and the material of the ceramic insulating layer is porous alumina. The liquid retention capacity of the wound structure in Case 4 is 0.5g higher than that of the wound structure in Case 1.

[0124] Case 5: The positive electrode connection area of ​​the positive electrode sheet and the negative electrode connection area of ​​the negative electrode sheet are both covered with a ceramic insulating layer and the material of the ceramic insulating layer is porous alumina. The liquid retention capacity of the winding structure in Case 5 is increased by 0.7g compared with the liquid retention capacity of the winding structure in Case 1.

[0125] In summary, the present embodiment can effectively improve the liquid retention capacity of the winding structure by covering the positive electrode connection area of ​​the positive electrode sheet and the negative electrode connection area of ​​the negative electrode sheet with a ceramic insulating layer.

[0126] like Figure 13 As shown, the present invention further provides a battery pack 100, which includes the aforementioned secondary battery 1. In one embodiment of the present invention's battery pack 100, the battery pack 100 comprises a housing 310, a housing cover 320, and a plurality of secondary batteries 1. The plurality of secondary batteries 1 are placed within the housing 310 and connected in series or in parallel, or in a combination of series and parallel. The housing cover 320 seals the housing 310 to protect the plurality of secondary batteries 1. It should be noted that, in addition to the present invention's secondary battery 1, the battery pack 100 may also include a thermal management system, a circuit board, and other components. The battery pack 100 may be a battery module, a battery pack, an energy storage cabinet, or the like; detailed descriptions are omitted here.

[0127] like Figure 14As shown, the present invention also provides an electronic device 1000, which includes the above-mentioned battery pack 100. The working unit 300 is electrically connected to the battery pack 100 to obtain electrical energy support. As an example, the electronic device 1000 is a vehicle, which can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, etc., but is not limited to this. The working unit 300 is the vehicle body, and the battery pack 100 is arranged at the bottom of the vehicle body and provides electrical energy support for the vehicle's driving or the operation of electrical components within the vehicle. However, in some other embodiments, the electronic device 1000 can also be a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. The working unit 300 can be a unit component that can obtain electrical energy from the battery pack 100 and perform corresponding work, such as the fan blade rotation unit of a fan, the dust collection unit of a vacuum cleaner, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys; electric tools include metal cutting tools, grinding tools, assembly tools, and railway tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. The present embodiment of the present application does not impose any particular limitation on the electronic device 1000.

[0128] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of protection of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of protection of the present invention.

Claims

1. A secondary battery, characterized in that: It includes: case; an electrode assembly housed in the housing, the electrode assembly comprising a wound structure formed by stacking and winding a positive electrode sheet, a separator, and a negative electrode sheet; the positive electrode sheet comprising a positive electrode current collector, and the negative electrode sheet comprising a negative electrode current collector; along the axial direction of the wound structure, the positive electrode current collector comprising a positive electrode coating region covered by the positive electrode active material layer and a positive electrode uncoated region not covered by the positive electrode active material layer; and the negative electrode current collector comprising a negative electrode coating region covered by the negative electrode active material layer and a negative electrode uncoated region not covered by the negative electrode active material layer; The direction from the positive electrode coated area to the positive electrode uncoated area is a first direction, and the direction from the negative electrode coated area to the negative electrode uncoated area is a second direction; along the first direction, the positive electrode uncoated area includes a positive electrode tab and a positive electrode connection area connected between the positive electrode tab and the positive electrode coated area; along the second direction, the negative electrode uncoated area includes a negative electrode tab and a negative electrode connection area connected between the negative electrode tab and the negative electrode coated area; Wherein, at least a portion of the positive electrode connection region and / or the negative electrode connection region is covered with a ceramic insulating layer, and the particle size D of the material of the ceramic insulating layer is in the range of 1.5 μm<D<4.0 μm.

2. The secondary battery according to claim 1, wherein The material of the ceramic insulating layer is porous alumina.

3. The secondary battery according to claim 1, wherein Along the radial direction of the winding structure, the negative electrode connection area includes a first negative electrode connection side facing away from the center hole of the winding structure and a second negative electrode connection side facing the center hole, wherein at least a partial area of ​​the first negative electrode connection side and / or the second negative electrode connection side is covered with the ceramic insulating layer.

4. The secondary battery according to claim 3, wherein The ceramic insulating layer covers the entire area of ​​the first negative electrode connection side of the negative electrode connection area; and / or, The ceramic insulating layer covers the entire area of ​​the second negative electrode connection side of the negative electrode connection area; and / or, Along the second direction, the maximum width of the ceramic insulating layer is greater than or equal to the width of the negative electrode connection area; and / or, Along the second direction, the width of the ceramic insulating layer covering the negative electrode connection area ranges from 0.1 mm to 2 mm; and / or, The maximum thickness of the ceramic insulating layer is 30%-50% of the maximum thickness of the negative electrode active material layer; and / or, Along the second direction, one side of the ceramic insulating layer overlaps or abuts against the outer edge of the negative electrode coating region, and the other side of the ceramic insulating layer is parallel to the outer edge of the negative electrode coating region.

5. The secondary battery according to claim 1, wherein Along the radial direction of the wound structure, the positive electrode connection area includes a first positive electrode connection side facing away from the center hole of the wound structure and a second positive electrode connection side facing the center hole, wherein at least a partial area of ​​the first positive electrode connection side and / or the second positive electrode connection side is covered with the ceramic insulating layer.

6. The secondary battery according to claim 5, wherein The ceramic insulating layer covers the entire area of ​​the first positive electrode connection side of the positive electrode connection area; and / or, The ceramic insulating layer covers the entire area of ​​the second positive electrode connection side of the positive electrode connection area; and / or, Along the first direction, the maximum width of the ceramic insulating layer is greater than or equal to the width of the positive electrode connecting area.

7. The secondary battery according to claim 1, wherein The filling coefficient of the secondary battery is 1.3-1.

4.

8. The secondary battery according to any one of claims 1 to 7, wherein: The shell includes a surrounding side wall, one end of which is formed with an opening; the end of the shell close to the opening includes a crimping portion recessed toward the interior of the shell; The secondary battery further includes: a cover plate mounted on the opening; an insulating seal, the insulating seal being arranged around the periphery of the cover plate to insulate and seal the cover plate and the housing; a current collecting plate, disposed between the electrode assembly and the cover plate and electrically connected to the housing, wherein the connecting piece of the current collecting plate is located on a side of the crimping portion facing the electrode assembly and is welded to the crimping portion; and / or, The secondary battery is a cylindrical battery.

9. A battery pack, characterized in that: A secondary battery comprising the secondary battery according to any one of claims 1 to 8.

10. An electronic device, characterized in that: A battery pack comprising the battery pack according to claim 9.

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