Cylindrical battery and battery pack

Abstract

To provide a cylindrical battery and a battery pack for solving a short circuit problem.SOLUTION: The present application provides a cylindrical battery and a battery pack. The cylindrical battery includes a case, an electrode assembly, and a first insulating layer. The case includes a receiving cavity. The electrode assembly is disposed within the receiving cavity. The electrode assembly includes a positive electrode sheet, a separator, and a negative electrode sheet. The positive electrode sheet has a negative electrode tab, and the negative electrode sheet has a positive electrode tab. The positive electrode tab and the negative electrode tab are located at respective ends of the electrode assembly. The first insulating layer is disposed on a surface of the negative electrode sheet toward the separator, and is disposed away from the negative electrode tab.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This application claims priority to a Chinese patent application filed with the China Patent Office on September 15, 2023, bearing application number 202311201240.3, the entire contents of which are incorporated herein by reference.

[0002] This application relates to battery technology, and in particular to cylindrical batteries and battery packs. [Background technology]

[0003] During long-term cycling of a cylindrical battery, the negative plate inside the battery expands and stretches, causing the separator to break through. Summary of the Invention [Problem to be solved by the invention]

[0004] After the separator is broken, the material area of ​​the negative plate away from the negative tab directly contacts the positive tab, causing a short circuit. At present, how to avoid a short circuit caused by the material area of ​​the negative plate away from the negative tab contacting the positive tab after breaking through the separator remains a technical problem that needs to be solved as soon as possible. [Means for solving the problem]

[0005] The present application provides a cylindrical battery and a battery pack for solving the problem of short circuit in the related art caused by the material area of ​​the negative plate away from the negative tab breaking through the separator and then contacting the positive tab.

[0006] According to a first aspect, the present application provides a cylindrical battery, the cylindrical battery comprising: a case having a receiving cavity, an electrode assembly and a first insulating layer disposed within the receiving cavity, the electrode assembly including a positive plate, a separator, and a negative plate disposed in a stacked and wound manner, the positive electrode tab of the positive plate and the negative electrode tab of the negative plate being disposed at both ends of the electrode assembly, and a first insulating layer disposed on a surface of the negative plate facing the separator, the first insulating layer being disposed at an end of the surface remote from the negative electrode tab.

[0007] According to a second aspect, the present application provides a battery pack, the battery pack including a plurality of the cylindrical batteries described above, the plurality of cylindrical batteries being connected in series or in parallel. Effect of the Invention

[0008] In the present application, by providing a first insulating layer on the material region on the side away from the negative electrode tab of the negative electrode plate, when the material region on the side away from the negative electrode tab of the negative electrode plate breaks through the separator and extends toward the positive electrode tab, the first insulating layer separates the material region on the side away from the negative electrode tab of the negative electrode plate from the positive electrode tab, thereby solving the problem of short circuiting in the related art caused by the material region on the side away from the negative electrode tab of the negative electrode plate coming into contact with the positive electrode tab after breaking through the separator. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is an exploded view of a cylindrical battery according to an embodiment of the present application. [Diagram 2] FIG. 2 is a front view of a negative electrode plate in a developed state on which a first insulating layer is provided according to an embodiment of the present application. [Diagram 3] FIG. 2 is a plan view of a negative electrode plate on which a first type first insulating layer is provided according to an embodiment of the present application. [Figure 4] FIG. 2 is a plan view of a negative electrode plate on which a second type of first insulating layer is provided according to an embodiment of the present application. [Diagram 5] FIG. 13 is a front view of another negative electrode plate in an expanded state on which a first insulating layer is provided according to an embodiment of the present application. [Figure 6]FIG. 11 is a plan view of a negative electrode plate on which a third type first insulating layer is provided according to an embodiment of the present application. [Figure 7] FIG. 11 is a plan view of a negative electrode plate on which a fourth type first insulating layer is provided according to an embodiment of the present application. [Figure 8] FIG. 11 is a plan view of a negative electrode plate on which a fifth type first insulating layer is provided according to an embodiment of the present application. [Figure 9] FIG. 11 is a plan view of a negative electrode plate on which a sixth type first insulating layer is provided according to an embodiment of the present application. [Figure 10] FIG. 13 is a plan view of a negative electrode plate on which a seventh type first insulating layer is provided according to an embodiment of the present application. [Figure 11] FIG. 13 is a plan view of a negative electrode plate on which an eighth type first insulating layer is provided according to an embodiment of the present application. [Figure 12] FIG. 13 is a plan view of a negative electrode plate on which a ninth type first insulating layer is provided according to an embodiment of the present application. [Figure 13] FIG. 13 is a plan view of a negative plate having a tenth type first insulating layer according to an embodiment of the present application. [Figure 14] FIG. 2 is a plan view of a negative electrode plate on which a first insulating layer and a second insulating layer are provided according to an embodiment of the present application. [Figure 15] 1 is a structural schematic diagram of a battery pack according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Referring to FIG. 1, FIG. 1 is an exploded view of a cylindrical battery 10 according to an embodiment of the present application. The embodiment of the present application provides a cylindrical battery 10 including a case 101, an electrode assembly 102, and a first insulating layer 103. The case 101 has a receiving cavity 1014. The electrode assembly 102 is installed in the receiving cavity 1014. The electrode assembly 102 includes a positive plate, a separator, and a negative plate 1021, which are stacked and wound. A positive electrode tab 1024 of the positive plate and a negative electrode tab 1022 of the negative plate 1021 are located at both ends of the electrode assembly 102. A first insulating layer 103 is installed on the surface of the negative plate 1021 facing the separator, and the first insulating layer 103 is located at the end of the surface away from the negative electrode tab 1022.

[0011] The negative electrode plate 1021 includes a current collector and an active material layer disposed on the current collector, and the region in which the active material layer is located is a material region 1023. The surface of the active material layer away from the current collector is the surface facing the separator of the negative electrode plate 1021. One end of the surface of the current collector along the width direction is a blank region where no active material layer is disposed, and the current collector located in the blank region is a negative electrode tab 1022. The first insulating layer 103 is disposed on the surface of the active material layer away from the current collector, and is located at the end of that surface away from the negative electrode tab 1022.

[0012] The first insulating layer 103 is a material layer having insulating properties, and can be installed on the negative electrode plate 1021 by coating, or can be installed on the negative electrode plate 1021 by adhesion. In terms of weight percentage, the first insulating layer 103 may include 20% to 40% ceramic, 15% to 60% adhesive, and 5% to 20% organic solvent. The ceramic includes, but is not limited to, aluminum oxide, boehmite, and zirconia. The adhesive includes, but is not limited to, polyvinylidene fluoride, polytetrafluoroethylene, and sodium carboxymethyl cellulose. The organic solvent includes, but is not limited to, i-methylpyrrolidone, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, and a highly insulating adhesive resin. Here, the highly insulating adhesive resin may be a polyvinylidene fluoride-based adhesive. The polyvinylidene fluoride-based adhesive is an adhesive resin formed by producing a copolymer from organic monomers such as butyl acrylate, acrylonitrile, and vinyl acetate, and dispersing the copolymer and an inorganic filler in an organic solvent. Inorganic fillers include, but are not limited to, potassium persulfate, sodium persulfate, ammonium persulfate, and the like.

[0013] Specifically, the first insulating layer 103 may employ any one or more insulating adhesives in the table below.

[0014] Table 1 provides information on some insulating adhesives.

[0015] [Table 1]

[0016] In this embodiment, a material region 1023 is provided on the surface of the negative electrode plate 1021 facing the separator, and a first insulating layer 103 is provided on the surface of the end of the material region 1023 away from the negative electrode tab 1022. As a result, during use of the cylindrical battery 10, when the negative electrode plate 1021 expands and stretches, and the negative electrode plate 1021 breaks through the separator and extends toward the positive electrode tab 1022, the first insulating layer 103 separates the material region 1023 on the side away from the negative electrode tab 1022 of the negative electrode plate 1021 from the positive electrode tab 1024, thereby preventing the material region 1023 on the side away from the negative electrode tab 1022 of the negative electrode plate 1021 from directly contacting the positive electrode tab 1024. Furthermore, this solves the problem of short circuit caused by the material region 1023 on the side away from the negative electrode tab 1022 of the negative electrode plate 1021 contacting the positive electrode tab 1024 in the related art, and improves the safety and stability of the battery.

[0017] The size of the first insulating layer 103 in the length direction of the negative electrode plate 1021 is S1, the length of the negative electrode plate 1021 is S, and S1 ≤ S is satisfied. When S1 < S, the first insulating layer 103 can be installed at any position in the length direction of the negative electrode plate 1021. At this time, the first insulating layer 103 partially covers the edge on the side away from the negative electrode tab 1022 of the negative electrode plate 1021, thereby separating the positive electrode tab 1024 from a part of the material region 1023 on the side away from the negative electrode tab 1022 of the negative electrode plate 1021. As shown in FIGS. 2 to 4, FIG. 2 is a front view in the unfolded state of the negative electrode plate 1021 where the first insulating layer 103 is installed according to an embodiment of the present application, FIG. 3 is a plan view of the negative electrode plate 1021 where the first type of the first insulating layer 103 is installed according to an embodiment of the present application, and FIG. 4 is a plan view of the negative electrode plate 1021 where the second type of the first insulating layer 103 is installed according to an embodiment of the present application. In FIGS. 2 and 3, the first insulating layer 103 is installed from one end in the length direction of the negative electrode plate 1021, and in FIG. 4, the first insulating layer 103 is installed from a certain position in the middle of the length of the negative electrode plate 1021. When S1 = S, as shown in FIG. 5, FIG. 5 is a front view in the unfolded state of another negative electrode plate 1021 where the first insulating layer 103 is installed according to an embodiment of the present application. At this time, the first insulating layer 103 completely covers the edge on the side away from the negative electrode tab 1022 of the negative electrode plate 1021, thereby separating the positive electrode tab 1024 from all of the material region 1023 on the side away from the negative electrode tab 1022 of the negative electrode plate 1021.

[0018] The size of the first insulating layer 103 in the width direction of the negative electrode plate 1021 is L1, and 0.1 mm ≤ L1 ≤ 50 mm is satisfied. When L1 is smaller than 0.1 mm, the covered area of the first insulating layer 103 is too small, and there may be a possibility that a short circuit cannot be completely avoided during the process of the negative electrode plate 1021 expanding and stretching. When L1 > 50 mm, the area covered by the first insulating layer 103 exceeds the Overhang area too much, which is disadvantageous for lithium release and absorption.

[0019] In one embodiment, the size of the first insulating layer 103 in the thickness direction of the negative electrode plate 1021 is d.

Number

[0020] The formula for calculating the length S2 of the negative electrode plate 1021 where the first insulating layer 103 is not provided is S2=[(a+2b)(n+1)n+(2n-1)nD+2r]π. From this formula, it can be seen that the formula for calculating the length S of the negative electrode plate 1021 where the first insulating layer 103 is provided is S=[(d+a+2b)(n+1)n+(2n-1)nD+2r]π. Converting this formula,

number

[0021] In one embodiment, the size d of the first insulating layer 103 in the thickness direction of the negative electrode plate 1021 is further set to:

number

[0022] Based on formula (1), a more preferred range of values ​​for size d can be obtained based on the group margin calculation formula, i.e., formula (2). The value of size d in this range can have a high energy density while having the technical effect corresponding to formula (1).

[0023] 6, which is a plan view of a negative plate 1021 having a third type first insulating layer 103 according to an embodiment of the present application. In one embodiment, the first insulating layer 103 is disposed on the same side of the negative plate 1021 and includes multiple first sub-insulating layers 1031 stacked in sequence along the thickness direction of the negative plate 1021.

[0024] Along the direction approaching the negative electrode plate 1021, the sizes of the first sub-insulation layers 1031 in the thickness direction of the negative electrode plate 1021 are d1, d2, . . . , d i where i is a natural number and i ≥ 2, and Σ di As can be understood, the number of layers of the first sub-insulation layer 1031 is selectively designed based on the thickness d of the first insulating layer 103, for example, i=2, or i=3, or i=4, or i=5, and Σ di The value of can be set to the above formula (1) or formula (2).

[0025] 6, multiple layers of the first insulating sub-layer 1031 can be disposed on the same side of the negative electrode plate 1021 by coating. This is not only advantageous for controlling the thickness of the first insulating layer 103, but also for improving the insulating properties of the first insulating layer 103, and increases the internal resistance between the material region 1023 on the side away from the negative electrode tab 1022 of the negative electrode plate 1021 and the positive electrode tab 1024, thereby improving the insulation properties between the material region 1023 on the side away from the negative electrode tab 1022 of the negative electrode plate 1021 and the positive electrode tab 1024.

[0026] 7 to 9, Fig. 7 is a plan view of a negative plate 1021 having a fourth type first insulating layer 103 according to an embodiment of the present application, Fig. 8 is a plan view of a negative plate 1021 having a fifth type first insulating layer 103 according to an embodiment of the present application, and Fig. 9 is a plan view of a sixth type negative plate 1021 having a first insulating layer 103 according to an embodiment of the present application. In one embodiment, the first insulating layer 103 includes a plurality of first sub-insulating layers 1031, the negative plate 1021 has a first side and a second side opposite to each other, a part of the first sub-insulating layer 1031 is disposed on the first side, and the remaining first sub-insulating layer 1031 is disposed on the second side, and the first sub-insulating layers 1031 located on the same side of the negative plate 1021 are stacked in order along the thickness direction of the negative plate 1021.

[0027] As shown in FIG. 7, FIG. 8 and FIG. 9, a part of the first sub-insulating layer 1031 is disposed on a first side of the negative plate 1021, and another part of the first sub-insulating layer 1031 is disposed on a second side of the negative plate 1021. In FIG. 7, one first sub-insulating layer 1031 is disposed on both sides of the negative plate 1021. The sizes of the two first sub-insulating layers 1031 in the thickness direction of the negative plate 1021 are d1 and d2, respectively, and d1+d2=d. In FIG. 8, two first sub-insulating layers 1031 are disposed on both sides of the negative plate 1021. The sizes of the multiple first sub-insulating layers 1031 in the thickness direction of the negative plate 1021 are d1, d2, d3 and d4, respectively, from the first side to the second side of the negative plate 1021, and d1+d2+d3+d4=d. 9, three first sub-insulating layers 1031 are provided on one side of the negative electrode plate 1021, and two first sub-insulating layers 1031 are provided on the other side of the negative electrode plate 1021. The sizes of the multiple first sub-insulating layers 1031 in the thickness direction of the negative electrode plate 1021 are d1, d2, d3, d4, and d5, respectively, from the first side to the second side of the negative electrode plate 1021, and d1+d2+d3+d4+d5=d.

[0028] A first sub-insulating layer 1031 is provided on both sides of the negative electrode plate 1021, so that the first insulating layer 103 separates both sides of the two surfaces in the thickness direction of the negative electrode plate 1021, which are far from the negative electrode tab 1022, from the positive electrode tab 1024, thereby preventing the material region 1023 on the side far from the negative electrode tab 1022 on the two surfaces in the thickness direction of the negative electrode plate 1021 from directly contacting the positive electrode tab after the separator is broken through.

[0029] When the first sub-insulating layer 1031 has multiple layers, the multiple first sub-insulating layers 1031 may adopt the same insulating material or different insulating materials, as shown in Figures 10 to 13, Figure 10 is a plan view of a negative electrode plate 1021 having a seventh type first insulating layer 103 according to an embodiment of the present application, Figure 11 is a plan view of a negative electrode plate 1021 having an eighth type first insulating layer 103 according to an embodiment of the present application, Figure 12 is a plan view of a negative electrode plate 1021 having a ninth type first insulating layer 103 according to an embodiment of the present application, and Figure 13 is a plan view of a negative electrode plate 1021 having a tenth type first insulating layer 103 according to an embodiment of the present application. In Figure 10, two first sub-insulating layers 1031 are installed on one side of the negative electrode plate 1021, and the insulating materials of the two first sub-insulating layers 1031 are different. 11, one first sub-insulating layer 1031 is provided on each side of the negative plate 1021, and the insulating materials of the first sub-insulating layers 1031 on each side of the negative plate 1021 are different. In FIG. 12, two first sub-insulating layers 1031 are provided on each side of the negative plate 1021, and of the first sub-insulating layers 1031 on each side, the first sub-insulating layer 1031 directly applied to the negative plate 1021 uses one insulating material, and another first sub-insulating layer 1031 applied to the first sub-insulating layer 1031 uses a different insulating material. In FIG. 13 , the first sub-insulating layers 1031 on both sides of the negative plate 1021 can be arranged in mirror symmetry with respect to the negative plate 1021. For example, two first sub-insulating layers 1031 are arranged on both sides of the negative plate 1021, one first sub-insulating layer 1031 applied directly to one side of the negative plate 1021 adopts a first insulating material, another first sub-insulating layer 1031 applied to the first sub-insulating layer 1031 adopts a second insulating material, one first sub-insulating layer 1031 applied directly to the other side of the negative plate 1021 adopts the second insulating material, and another sub-insulating layer applied to the first sub-insulating layer 1031 adopts the first insulating material.

[0030] The multiple first sub-insulation layers 1031 adopt different insulating materials, so that the first insulation layer 103 can obtain the combined performance of various different insulating materials, which is advantageous in improving the insulation between the material region 1023 on the side away from the negative electrode tab 1022 of the negative electrode plate 1021 and the positive electrode tab 1024.

[0031] Based on the table describing some insulating adhesive information above, the following four sets of control experiments were carried out for the configuration of the first insulating layer 103.

[0032] In the first set, the negative electrode plate 1021 does not have the first insulating layer 103 provided thereon.

[0033] In the second set, the insulating adhesive A is applied uniformly on one side of the negative plate 1021 on the material area away from the negative tab 1022 to form the first insulating layer 103. The first insulating layer 103 includes a plurality of first sub-insulating layers 1031, each of which has a thickness d i The average value of is 5.7 μm, and the length S1 coincides with the length S of the negative electrode plate.

[0034] In the third set, the insulating adhesive A is applied uniformly on the material areas away from the negative tabs 1022 on both sides of the negative plate 1021 to form the first insulating layer 103. The first sub-insulating layers 1031 applied on both sides of the negative plate 1021 have thicknesses of 5.5 μm and 5.7 μm, respectively, and their lengths S1 match the length S of the negative plate.

[0035] In the fourth set, the insulating adhesives A and B are respectively uniformly applied on the material areas away from the negative tab 1022 on both sides of the negative plate 1021 to form the first insulating layer 103. The first sub-insulating layers 1031 applied on both sides of the negative plate 1021 have thicknesses of 5.7 μm and 9.5 μm, respectively, and their lengths S1 are consistent with the length S of the negative plate.

[0036] 4. Using a probe method, the internal resistance of the side of the four sets of negative electrode plates 1021 away from the negative electrode tabs 1022 is detected to obtain the following internal resistance data table.

[0037] Table 2 shows the internal resistance of the four negative electrode plates 1021 measured.

[0038] [Table 2]

[0039] As is clear from Table 2, the thicker the first insulating layer 103 is and the more insulating adhesive is applied to both sides of the negative electrode plate 1021, the higher the internal resistance of the corresponding negative electrode plate 1021 becomes.

[0040] In one embodiment, when there are multiple first insulating sub-layers 1031, the sizes of the multiple first insulating sub-layers 1031 in the thickness direction of the negative electrode plate 1021 from one side to the other side of the negative electrode plate 1021 are sequentially denoted as d1, d2, ..., d i where i is a natural number, i≧2, and 0.15 <d1:d i <= 1.

[0041] d1:d i By limiting, it is possible to ensure that the thickness difference between the first sub-insulating layers 1031 is not large, so that the thickness distribution of the first sub-insulating layers 1031 is as uniform as possible, and the adhesion stability between two adjacent first sub-insulating layers 1031 can be improved. <d1:di≦0.75である。

[0042] 14, which is a plan view of a negative electrode plate 1021 having a first insulating layer 103 and a second insulating layer 104 according to an embodiment of the present application. In one embodiment, one end surface of the negative electrode plate 1021 in the longitudinal direction is a first end surface located on the outer periphery of the electrode assembly 102, and the second insulating layer 104 is provided on the first end surface.

[0043] The first end face of the negative electrode plate 1021 is located on the outer periphery of the electrode assembly 102, and when the negative electrode plate 1021 expands and stretches, the amount of deformation increases, and there is a risk of the negative electrode plate 1021 breaking through the separator and causing a short circuit. Therefore, by providing the second insulating layer 104 on the first end face, when the first end face breaks through the separator and extends toward the positive electrode plate, the first end face and the positive electrode plate are separated from each other, and the stability of the cylindrical battery 10 can be improved.

[0044] Similar to the first insulating layer 103, the second insulating layer 104 is also a material layer having insulating properties. There are many options for the insulating materials of the first insulating layer 103 and the second insulating layer 104, and the specific raw materials are not limited, and may be adaptively selected according to the actual application environment.

[0045] In one embodiment, the second insulating layer 104 covers the first end surface. The second insulating layer 104 covers the entire first end surface, thereby completely isolating the positive plate from the first end surface. In addition, when the negative plate 1021 is cut, a burr is present on the first end surface as the cut surface of the negative plate 1021. After the second insulating layer 104 is installed, the second insulating layer 104 covers the burr, thereby preventing the burr on the cut surface from breaking through the separator, thereby improving the stability of the cylindrical battery 10.

[0046] In one embodiment, the size of the negative electrode plate 1021 of the second insulating layer 104 in the thickness direction is L2, the thickness of the negative electrode plate 1021 is D, and D≦L2≦50 mm is satisfied, and the size of the negative electrode plate 1021 of the second insulating layer 104 in the length direction is d0, and 0.001 mm≦d0≦10 mm is satisfied.

[0047] If L2 is smaller than the thickness D of the negative plate 1021, the second insulating layer 104 cannot completely cover the first end surface. If L2 is larger than 50 mm, it is disadvantageous to winding the negative plate 1021, and the second insulating layer 104 is easily detached from the first end surface. If d0 is smaller than 0.001 mm, the second insulating layer 104 is damaged due to the deformation of the first end surface when winding the negative plate 1021, so that when the negative plate 1021 expands and stretches, the active material of the negative plate 1021 extends from the damaged point and breaks through the separator. If d0 is larger than 10 mm, the protective layer is too thick and protrudes too much at the end of the negative plate, which affects the void volume in the receiving cavity of the assembled battery, and the void becomes too small.

[0048] For example, D≦L2≦30 mm and 0.01 mm≦d0≦1 mm.

[0049] In one embodiment, both the positive electrode tab 1024 and the negative electrode tab 1022 are flattened tabs. The flattened tabs can effectively reduce the space occupancy of the tabs, thereby improving the energy density of the battery. However, after flattening the tabs, the positive electrode tab is moved to the end of the negative electrode plate farther from the negative electrode tab. As a result, when the negative electrode plate expands and stretches, the edge of the material area of ​​the negative electrode plate 1021 farther from the negative electrode tab 1022 can more easily contact the positive electrode tab 1024 after breaking through the separator. In this embodiment, a first insulating layer is provided on the edge of the material area of ​​the negative electrode plate 1021 farther from the negative electrode tab 1022, which can greatly improve the stability of the cylindrical battery with flattened tabs.

[0050] As shown in FIG. 15, FIG. 15 is a structural schematic diagram of a battery pack 1 according to an embodiment of the present application. The embodiment of the present application further provides a battery pack 1. The battery pack 1 includes a plurality of cylindrical batteries 10 connected in series or parallel. The battery pack 1 further includes a housing 20 including a housing lid 201 and a housing body 202. The housing lid 201 covers the housing body 202 to form a closed cylindrical battery mounting cavity. A plurality of cylindrical batteries 10 are installed in the cylindrical battery mounting cavity. [Explanation of symbols]

[0051] 1-battery pack, 10-cylindrical battery, 101-case, 1011-top cover, 1012-body, 1013-bottom cover, 1014-receiving cavity, 102-electrode assembly, 1021-negative plate, 1022-negative tab, 1023-material area, 1024-positive tab, 103-first insulating layer, 1031-first sub-insulating layer, 104-second insulating layer, 20-housing, 201-housing cover, 202-housing body.

Claims

1. A cylindrical battery, A case (101) having a receiving cavity (1014); An electrode assembly (102) is installed in the receiving cavity (1014), the electrode assembly (102) includes a positive electrode plate, a separator, and a negative electrode plate (1021) that are stacked and wound, and a positive electrode tab (1024) of the positive electrode plate and a negative electrode tab (1022) of the negative electrode plate (1021) are located at both ends of the electrode assembly (102); A cylindrical battery, comprising: a first insulating layer (103) disposed on a surface of the negative electrode plate (1021) facing the separator, the first insulating layer (103) being located at the end of said surface remote from the negative electrode tab (1022).

2. The size of the first insulating layer (103) in the thickness direction of the negative electrode plate (1021) is d; [0010] Fulfilling Where: S is the length (mm) of the negative electrode plate (1021), r is the radius (mm) of the winding pin used in winding to form the electrode assembly (102); a is the thickness (mm) of the positive electrode plate, b is the thickness of the separator (mm), D is the thickness (mm) of the negative electrode plate (1021), 2. The cylindrical battery of claim 1, wherein n is the number of turns the negative plate (1021) is wound around.

3. The size d of the first insulating layer (103) in the thickness direction of the negative electrode plate (1021) is further defined as: [0025] Fulfilling Where:

3. The cylindrical battery according to claim 2, wherein R is the radius of the case (101) (mm).

4. 2. The cylindrical battery of claim 1, wherein the first insulating layer (103) includes a plurality of first sub-insulating layers (1031), the plurality of first sub-insulating layers (1031) being disposed on the same side of the negative electrode plate (1021), and the plurality of first sub-insulating layers (1031) being stacked in order along the thickness direction of the negative electrode plate (1021).

5. The cylindrical battery according to any one of claims 1 to 4, wherein the first insulating layer (103) includes a plurality of first sub-insulating layers (1031), the negative plate (1021) has opposing first and second sides, a portion of the first sub-insulating layer (1031) is disposed on the first side and a remaining portion of the first sub-insulating layer (1031) is disposed on the second side, and the first sub-insulating layers (1031) located on the same side of the negative plate (1021) are stacked in order along the thickness direction of the negative plate (1021).

6. The first sub-insulation layer (1031) of the plurality of layers is arranged in a thickness direction of the negative electrode plate (1021) in order of size d from one side of the negative electrode plate (1021) to the other side of the negative electrode plate (1021). １ , d ２ , ..., d ｉ where i is a natural number, i≧2, and 0.15<d １ :d ｉ 5. The cylindrical battery according to claim 4, wherein:

7. The cylindrical battery according to any one of claims 1 to 4, wherein one end face in the longitudinal direction of the negative electrode plate (1021) is a first end face located on the outer periphery of the electrode assembly (102), and a second insulating layer (104) is provided on the first end face.

8. 8. The cylindrical battery of claim 7, wherein the second insulating layer (104) covers the first end surface.

9. The size of the second insulating layer (104) in the thickness direction of the negative electrode plate (1021) is L ２ and the thickness of the negative electrode plate (1021) is D, and D≦L ２ ≦50 mm, and the size of the second insulating layer (104) in the length direction of the negative electrode plate (1021) is d ０ and 0.001 mm≦d ０ The cylindrical battery according to claim 7, wherein the thickness satisfies ≦10 mm.

10. The cylindrical battery of any one of claims 1 to 4, wherein the positive electrode tab (1024) and the negative electrode tab (1022) are both flattened tabs.

11. A battery pack comprising a plurality of cylindrical batteries (10) according to any one of claims 1 to 4 connected in series or in parallel.

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