A secondary battery and an electrical device

Abstract

The present application discloses a secondary battery and an electrical device using the same. The secondary battery includes: an electrode assembly, a first insulating sheet, and a second insulating sheet. The second insulating sheet includes a fixing portion and a supporting portion, and the fixing portion is connected to the supporting portion. The secondary battery satisfies the following: in the present application, by providing the second insulating sheet, it can assist in bending the tab when the electrode assembly is assembled. Especially when the above relationship is satisfied, it can ensure the mutual adhesion between the second insulating sheet, the first insulating sheet, and the tab, and there is no adhesiveness between the supporting portion and the tab. On the one hand, the partially adhered second insulating sheet can reduce the risk of tearing and deformation caused by bending the tab with full surface glue application, so as to improve the battery performance. On the other hand, the supporting portion can also reduce the movement space of the tab, prevent the short-circuit problem caused by the insertion of the tab, and further improve the battery service life.

Description

Technical Field

[0001] This application belongs to the technical field of batteries, and particularly relates to a secondary battery and an electrical device using the same. Background Art

[0002] When the electrode tab is inserted into the battery case, the electrode tab needs to be bent. The electrode tab is prone to deformation during bending and there is a risk of short circuit caused by the inner insertion into the electrode plate. Therefore, an insulating sheet needs to be provided to assist the bending of the electrode tab to avoid the inner insertion of the electrode tab. The traditional insulating sheet has an overall adhesive on the back and is directly adhered to the electrode tab, resulting in the electrode tab being easily pulled by the insulating sheet during bending, causing deformation and tearing of the electrode tab, and thus affecting the battery performance. Summary of the Invention

[0003] Object of the Invention: This application provides a secondary battery to solve the problem that the electrode tab is torn due to the overall adhesive of the insulating sheet, which affects the battery performance; this application also provides an electrical device including the above secondary battery.

[0004] Technical Solution: A secondary battery of this application includes:

[0005] An electrode assembly, the electrode assembly includes a wound core body and an electrode tab disposed on the wound core body; the electrode tab includes a first section and a second section, one end of the first section is connected to the wound core body, and the other end of the first section is connected to the second section; the second section is bent relative to the first section so that the second section and the top surface of the wound core body are disposed opposite to each other in the first direction x;

[0006] A first insulating sheet, the first insulating sheet includes a third section and a fourth section, the third section and the fourth section are connected; the surface of the second section opposite to the wound core body is a first surface; the third section is attached to the first surface, and the fourth section is attached to the first section;

[0007] A second insulating sheet, the second insulating sheet includes a fixing portion and a supporting portion, the fixing portion is connected to the supporting portion; the surface of the third section away from the first surface is a second surface, and the fixing portion is attached to the second surface; the supporting portion is bent relative to the fixing portion, and the supporting portion contacts at least a part of the fourth section;

[0008] Wherein, the thickness of the third section is D1 mm; the thickness of the fixing portion is D2 mm; the thickness of the supporting portion is D3 mm; the holding adhesion of the third section and the first surface is T1 h, and the holding adhesion of the fixing portion and the second surface is T2 h; the volume resistivity of the first insulating sheet is ρ1 Ω·cm; the volume resistivity of the fixing portion is ρ2 Ω·cm; the volume resistivity of the supporting portion is ρ3 Ω·cm; satisfying:

[0009] In some embodiments, the secondary battery further satisfies:

[0010] In some embodiments, the secondary battery further satisfies:

[0011] In some embodiments, the secondary battery further satisfies: 0.8 ≤ D2 / D1 ≤ 1.6, or, 1 ≤ D3 / D1 ≤ 1.5.

[0012] In some embodiments, the secondary battery further satisfies: 1.0 ≤ T2 / T1 ≤ 2.5.

[0013] In some embodiments, the support portion and at least a part of the fourth segment have a gap in the first direction x, and the gap has a maximum dimension of H mm in the first direction x, satisfying: 0.5 ≤ H ≤ 10.

[0014] In some embodiments, the secondary battery satisfies at least one of the following characteristics:

[0015] a) 0.5 ≤ D1 ≤ 1.5;

[0016] b) 0.4 ≤ D2 ≤ 2.4;

[0017] c) 0.5 ≤ D3 ≤ 2.25;

[0018] d) 10 ≤ T1 ≤ 25;

[0019] e) 4 ≤ T2 ≤ 25;

[0020] f) 1×10 12 ≤ ρ1 ≤ 2×10 13 ;

[0021] g) 0.1×10 14 ≤ ρ2 ≤ 2×10 14 ;

[0022] h) 0.1×10 14 ≤ ρ3 ≤ 2×10 14 .

[0023] In some embodiments, the electrode assembly includes at least two groups, and the electrode assemblies are spaced apart in the third direction z to make the tabs symmetrical;

[0024] The second segment has a maximum dimension of W1 mm in the second direction y, the third segment has a maximum dimension of W2 mm in the second direction y, and the fixing portion has a maximum dimension of W3 mm in the second direction y, satisfying: satisfying: W2 ≥ W3 > W1;

[0025] The second section has a maximum dimension of U1 mm in the third direction z, the third section has a maximum dimension of U2 mm in the third direction z, and the fixing portion has a maximum dimension of U3 mm in the third direction z, satisfying: U3 > 2U2 ≥ 2U1; wherein, the third direction z, the second direction y, and the first direction x intersect pairwise.

[0026] In some embodiments, the secondary battery satisfies at least one of the following characteristics:

[0027] i) 10 ≤ W2 ≤ 100;

[0028] j) 10 ≤ W3 ≤ 100;

[0029] k) 10 ≤ W1 ≤ 100;

[0030] l) 1 ≤ U2 ≤ 50;

[0031] m) 10 ≤ U3 ≤ 100;

[0032] n) 1 ≤ U1 ≤ 50.

[0033] In some embodiments, the present application further provides an electrical device including the secondary battery described above.

[0034] Beneficial effects: Compared with the prior art, a secondary battery of the present application includes: an electrode assembly including a core body and a tab disposed on the core body; the tab includes a first section and a second section, one end of the first section is connected to the core body, and the other end of the first section is connected to the second section; the second section is bent relative to the first section so that the second section is disposed opposite to the top surface of the core body in the first direction x; a first insulating sheet including a third section and a fourth section, the third section and the fourth section are connected, and the surface of the second section opposite to the core body is a first surface; the third section is attached to the first surface, and the fourth section is attached to the first section; a second insulating sheet including a fixing portion and a supporting portion, the fixing portion is connected to the supporting portion; the surface of the third section away from the first surface is a second surface, and the fixing portion is attached to the second surface; the supporting portion is bent relative to the fixing portion, and the supporting portion contacts at least a part of the fourth section; wherein, the thickness of the third section is D1 mm; the thickness of the fixing portion is D2 mm; the thickness of the supporting portion is D3 mm; the holding force of the third section and the first surface is T1 h; the holding force of the fixing portion and the second surface is T2 h; the volume resistivity of the first insulating sheet is ρ1 Ω·cm; the volume resistivity of the fixing portion is ρ2 Ω·cm; the volume resistivity of the supporting portion is ρ3 Ω·cm; satisfying: In this application, by providing the second insulating sheet, it can assist in bending the tab when the electrode assembly is assembled. Especially when the above relationship is satisfied, it can ensure that the fixing part of the second insulating sheet, the third section of the first insulating sheet, and the second section of the tab are adhesively connected to each other; the gap between the fourth section of the first insulating sheet and the supporting section reflects that they are not adhesively connected, which can reduce the probability of the tab being pulled and torn by the insulating sheet during the bending with full-surface glue application, so as to improve the battery performance; on the other hand, the supporting part can also reduce the moving space of the tab and prevent the short-circuit problem caused by the insertion of the tab, further improving the battery service life.

[0035] It can be understood that compared with the prior art, the electrical device provided by the embodiment of this application has all the technical features and beneficial effects of the above-mentioned welding positioning device, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The following will combine the drawings and describe the specific embodiments of this application in detail, and the technical solutions and other beneficial effects of this application will be obvious.

[0037] Figure 1 Structural schematic diagram of the electrode assembly provided by the embodiment of this application;

[0038] Figure 2 is Figure 1 side view in

[0039] Figure 3 is Figure 2 local enlarged view at A in

[0040] Figure 4 Structural schematic diagram of the electrode assembly and the first insulating sheet provided by the embodiment of this application;

[0041] Figure 5 Connection schematic diagram of the electrode assembly and the second insulating sheet provided by the embodiment of this application;

[0042] Figure 6 is Figure 5 local schematic diagram at B in

[0043] Figure 7 Connection schematic diagram of the tab, the first insulating sheet, and the second insulating sheet provided by the embodiment of this application;

[0044] Figure 8 is Figure 5 top view explosion schematic diagram of

[0045] Figure 9 is Figure 3 local enlarged view of

[0046] Reference numerals in the figure: 10 - electrode assembly, 11 - core body, 12 - tab, 20 - first insulating sheet, 30 - second insulating sheet, 40 - gap, 121 - first section, 122 - second section, 201 - third section, 202 - fourth section, 301 - fixing portion, 302 - supporting portion, 1221 - first surface, 2011 - second surface. Detailed implementation manners

[0047] Next, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

[0048] In the description of the present application, it should be noted that, unless otherwise clearly defined and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, an electrical connection, or a communication with each other; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal connection or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations. In the description of the present application, "a plurality of" means two or more, unless otherwise specifically defined. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features.

[0049] The following disclosure provides many different implementation manners or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application.

[0050] The applicant has found that a power secondary battery generally consists of a top cover, a housing, an electrode assembly, etc. To increase the energy density of the secondary battery, the electrode assembly includes a core body and tabs. Multiple core bodies are arranged side by side, and when the electrode assembly is inserted into the housing, the tabs need to be bent. When the tabs are bent, they are prone to deformation and there is a risk of short circuit caused by the tabs being inserted into the electrode plates. It is necessary to add insulating sheets to assist in bending the tabs and prevent the tabs from being inserted inside. The traditional insulating sheet has an overall adhesive backing and adheres to the tabs. When the tabs are bent, it is easy to pull the tabs, causing the tabs to deform and tear, thereby affecting the performance of the secondary battery. Based on this, the embodiments of the present application provide a secondary battery and an electrical device using the same. By locally pasting the insulating sheet, the tabs will not be pulled when the insulating sheet assists in bending the tabs, thus solving the above problems.

[0051] See Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 9 , the embodiments of the present application provide a secondary battery, including: an electrode assembly 10, a first insulating sheet 20, and a second insulating sheet 30; the electrode assembly 10 includes a core body 11 and tabs 12 provided on the core body; the tabs 12 include a first section 121 and a second section 122, one end of the first section 121 is connected to the core body 11, and the other end of the first section 121 is connected to the second section 122; the second section 122 is bent relative to the first section 121 so that the second section 122 and the top surface of the core body 11 are relatively arranged in the first direction x; the first insulating sheet 20 includes a third section 201 and a fourth section 202, the third section 201 and the fourth section 202 are connected, and the surface of the second section 122 facing the core body 11 is a first surface 1221; the third section 201 is attached to the first surface 1221, and the fourth section 202 is attached to the first section 121; the second insulating sheet 30 includes a fixing portion 301 and a supporting portion 302, the fixing portion 301 is connected to the supporting portion 302; the surface of the third section 201 away from the second section 122 is a second surface 2011, the fixing portion 301 is attached to the second surface 2011, and the supporting portion 302 is bent relative to the fixing portion 301, and the supporting portion 302 contacts at least a part of the fourth section 202; wherein, the thickness of the third section 201 is D1 mm; the thickness of the fixing portion 301 is D2 mm; the thickness of the supporting portion 302 is D3 mm; the holding force of the third section 201 and the first surface 1221 is T1 h, and the holding force of the fixing portion 301 and the second surface 2011 is T2 h; the volume resistivity of the first insulating sheet 20 is ρ1 Ω·cm; the volume resistivity of the fixing portion 301 is ρ2 Ω·cm; the volume resistivity of the supporting portion 302 is ρ3 Ω·cm; satisfying:

[0052] It can be understood that in the present application, by providing the second insulating sheet 30, it can assist in bending the tabs 12 when the electrode assembly 10 is assembled, especially when satisfying When within the numerical range, it can be ensured that the fixing portion 301 of the second insulating sheet 30, the third section 201 of the first insulating sheet 20, and the second section 122 of the tab 12 are adhesively connected to each other, while only the part of the supporting portion 302 and the fourth section 202 of the first insulating sheet 20 are in contact, that is, there is no adhesion between the supporting portion 302 and the fourth section 202; the setting method in which only the fixing portion 301 of the second insulating sheet 30 is adhered can, on the one hand, reduce the probability of deformation caused by the tab being pulled and torn by the insulating sheet when the tab is bent with full glue coverage, so as to improve the service performance of the battery; on the other hand, the supporting portion 302 can also reduce the movement space of the tab 12 and prevent the short-circuit problem caused by the tab being inserted inside, further improving the service life of the battery.

[0053] In some embodiments, referring to Figure 6 , the tab 12 is led out from the foil of the core body 11. The first section 121 of the tab 12 is the part directly led out from the foil, and the second section 122 of the tab is the part extending along the third direction z; after the electrode assembly 10 is cored, referring to Figure 3 , the second section 122 and the upper surface of the core body 11 are arranged in parallel. Here, parallel means completely parallel or almost completely parallel. For example, within a range of 5° of complete parallelism, it is considered parallel.

[0054] In some embodiments, the fitting in this embodiment specifically refers to adhesive connection. The performance of adhesion can be characterized by the holding power. The holding power represents the ability to resist the destruction of the bonding surface caused by parallel shear external forces. The unit of the holding power is time, that is, it can be understood as the time of continuous adhesion. The longer the time of the holding power, the better the adhesion performance of the fitting interface and the less likely to separate. In order to prevent the tearing of the tab 12, the second insulating sheet 30 is set to be partially adhered in this embodiment. Since the supporting portion 302 is closer to the root of the tab, there is no fitting between the supporting portion 302 and the fourth section 202, so that there is no force interaction between the supporting portion 302 and the tab. Therefore, the tab will not be pulled by the second insulating sheet 30 after being bent. In this embodiment, by controlling the adhesion performance between the first insulating sheet 20 and the tab 12 and between the second insulating sheet 30 and the first insulating sheet 20, it is ensured that the insulating sheet can play roles such as insulation and limiting inside the tab to meet the usage requirements of the battery.

[0055] Furthermore, the test of holding power can be carried out in accordance with the method in GB / T 4851—2014. For example, under the conditions of constant load, temperature of (23±1)°C, and relative humidity of (50±5)%, the holding power of the first insulating sheet and the second insulating sheet is measured by the failure time of the first insulating sheet and the second insulating sheet. Specifically: the first insulating sheet or the second insulating sheet is pasted onto the corresponding surface at a controlled rolling rate, the surface is set vertically, and at the same time, a weight of standard mass is hung at the free end of the first insulating sheet or the second insulating sheet, and the time of adhesive failure is measured to obtain the holding power.

[0056] In some embodiments, referring to Figure 4 , in addition to including the third section 201 and the fourth section 202, the first insulating sheet 20 may further include a fifth section 203. The third section 201, the fourth section 202, and the fifth section 203 are integrally formed to ensure that the first insulating sheet 20 has a uniform thickness. The fitting of the fourth section 202 and the first section 121 can ensure the insulation protection of the tab, and at the same time, the debris generated during the welding of the tab can be fixed to avoid affecting the battery performance. The fifth section 203 is on the side of the fourth section 202 away from the third section 201, and the fifth section 203 is connected to the large surface of the core body 11. Here, the large surface refers to the surface of the core body 11 with the largest area.

[0057] In some embodiments, since the thickness D1 of the first insulating sheet 20 and the thickness D2 of the fixing part 301 directly affect their pressure-bearing capacity and tear resistance, the bonding performance of the first insulating sheet 20 and the fixing part 301 is also limited by the thickness D1 of the first insulating sheet 20 and the thickness D2 of the fixing part 301. Only when the corresponding thickness requirements are met can the first insulating sheet 20 and the fixing part 301 have excellent bearing capacity and better durability. In addition, although the supporting part 302 is not pasted to the tab 12, when the electrode assembly 10 is cored, the supporting part 302 is located between the first section 121 and the second section 122 of the tab, and the thickness D3 of the supporting part 302 needs to be limited to reduce the moving space of the first section 121 after bending. It can be understood that the thickness D1 of the first insulating sheet 20, the thickness D2 of the fixing part 301, and the thickness D3 of the supporting part 302 can all be directly measured by a caliper. When measuring, multiple points can be selected and the average value can be taken to improve the accuracy of the thickness.

[0058] In some embodiments, in order to prevent short - circuit during the bending of the tab 12, the first insulating sheet 20 and the second insulating sheet 30 need to have insulation properties, that is, the insulation requirements are achieved by defining the volume resistivity of the first insulating sheet 20 and the second insulating sheet 30. It can be understood that the volume resistivity, also known as volume resistance or volume resistivity coefficient, is an important index characterizing the electrical properties of dielectrics or insulating materials. The larger the volume resistivity, the better the insulation performance. Among them, the volume resistivity ρ1 Ω·cm of the first insulating sheet 20, the volume resistivity ρ2 Ω·cm of the fixing part 301, and the volume resistivity ρ3 Ω·cm of the supporting part 302 are determined by the materials they adopt, and the range of the volume resistivity can be directly determined by the used materials.

[0059] In some embodiments, when the range of is satisfied, since the second insulating sheet 30 is locally pasted through the fixing part 301, excellent pasting performance between the fixing part 301 of the second insulating sheet 30 and the third section 201 of the first insulating sheet 20 is ensured. At the same time, the supporting part 302 is not pasted to the second section 122 of the tab 12, reducing the probability that the second section 122 of the tab is pulled and torn during bending. Moreover, under the limitation of the corresponding thickness, the supporting part 302 of the second insulating sheet 30 can also reduce the movement space of the first section 121, assist in bending the tab and play an insulating role. When the above - mentioned range is too small, it indicates that the pasting effect between the first insulating sheet 20 and the tab 12 is poor, unable to meet the insulation effect of the first insulating sheet 20, and even less able to firmly set the second insulating sheet 30 inside the tab. When the above - mentioned range is too large, it indicates that the pasting effect between the second insulating sheet 30 and the first insulating sheet 20 is poor, unable to meet the insulation effect of the second insulating sheet 30.

[0060] In some embodiments, the secondary battery further satisfies:

[0061] In some embodiments, the secondary battery further satisfies:

[0062] In some embodiments, the secondary battery further satisfies: 0.8 ≤ D2 / D1 ≤ 1.6, and 1 ≤ D3 / D1 ≤ 1.5. For example, D2 / D1 can be any value among 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 or the range between any two values; D3 / D1 can be any value among 1, 1.1, 1.2, 1.3, 1.4, 1.5 or the range between any two values. It can be understood that in the preferred range, the thickness D3 mm of the supporting part 302 satisfies not less than the thickness D1 mm of the first insulating sheet 20, so as to further prevent the short - circuit problem caused by internal insertion by limiting the movement space of the tab.

[0063] In some embodiments, the secondary battery further satisfies: 1.0 ≤ T2 / T1 ≤ 2.5. For example, T2 / T1 can be any value among 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5 or the range between any two values. It can be understood that within the preferred range, the holding adhesive force T2 between the fixing portion 301 and the second surface 2011 is not less than the holding adhesive force T1 between the first insulating sheet 20 and the first surface 1221. This is because the materials between the fixing portion 301 and the second surface 2011 are all insulating materials. Therefore, it is necessary to ensure a stronger pasting effect between the two to improve the insulation performance of the second insulating sheet 30 and can improve the durability of the battery during use.

[0064] In some embodiments, further referring to Figure 3 and Figure 5 , the supporting portion 302 and the fourth section 202 have a gap 40 in the first direction x. The gap 40 has a maximum dimension H mm in the first direction x, satisfying: 0.5 ≤ H ≤ 10. It can be understood that the gap 40 indicates that the supporting portion 302 and the fourth section 202 are not pasted. The size of the gap 40 depends on the bending state of the tab. If the gap 40 is too large or too small, it means that the tab 12 may not meet the connection requirements with the connecting piece after bending. Therefore, it is necessary to limit the size of the gap 40. The gap 40 can be any value among 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10 or the range between any two values.

[0065] It can be understood that the measurement of the gap 40 can be carried out by a transmissive type dimension measuring instrument or a reflective type 2D laser displacement meter. For example, from the Figure 3 perspective, facing the gap 40 and using a transmissive type dimension measuring instrument, the width of the transmitted light can be directly measured to obtain the size of the gap 40.

[0066] In some embodiments, the secondary battery satisfies: 0.5 ≤ D1 ≤ 1.5, 0.4 ≤ D2 ≤ 2.4, 0.5 ≤ D3 ≤ 2.25; for example, D1 can be any value among 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 or a range between any two of these values; D2 can be any value among 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4 or a range between any two of these values; D3 can be any value among 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.25 or a range between any two of these values.

[0067] In some embodiments, the secondary battery satisfies: 10 ≤ T1 ≤ 25, 4 ≤ T2 ≤ 25; for example, T1 can be any value among 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or a range between any two of these values; T2 can be any value among 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or a range between any two of these values.

[0068] In some embodiments, the secondary battery satisfies: 1×10 12 ≤ ρ1 ≤ 2×10 13 ,0.1×10 14 ≤ ρ2 ≤ 2×10 14 ,0.1×10 14 ≤ ρ3 ≤ 2×10 14 ; for example, ρ1 can be 1×10 12 、2×10 12 、3×10 12 、4×10 12 、5×10 12 、6×10 12 、7×10 12 、8×10 12 、9×10 12 、1×10 13 、2×10 13 or a range between any two of these values. ρ2 and ρ3 can be 0.1×10 14 、0.2×10 14 、0.3×10 14 、0.4×10 14, 0.5×10 14 , 0.6×10 14 , 0.7×10 14 , 0.8×10 14 , 0.9×10 14 , 1.0×10 14 , 1.1×10 14 , 1.2×10 14 , 1.3×10 14 , 1.4×10 14 , 1.5×10 14 , 1.6×10 14 , 1.7×10 14 , 1.8×10 14 , 1.9×10 14 , 2.0×10 14 Any value within or range between any two values among

[0069] In some embodiments, referring to Figure 5 and Figure 8 , the second section 122 has a maximum dimension W1 mm in the second direction y, the third section 201 has a maximum dimension W2 mm in the second direction y, and the fixing part 301 has a maximum dimension W3 mm in the second direction y, satisfying: W2≥W3>W1; wherein, the first direction x and the second direction y intersect. It can be understood that the above relationship indicates that in the second direction y, the first insulating sheet 20 and the fixing part 301 should at least completely cover the second section 122 to ensure the insulation effect and avoid the short-circuit problem caused by the exposure of the tab 12.

[0070] In some embodiments, referring to Figure 6 , Figure 7 and Figure 8 , the electrode assembly 10 includes at least two groups, and the electrode assemblies 10 are spaced apart in the third direction z so that the tabs 12 are symmetrically arranged to Figure 8 As shown in Figure 8 , the fixing part 301 is a rectangular structure and is located between the electrode assemblies 10, and the fixing part 301 is attached to the first insulating sheet 20,

[0071] In some embodiments, the first direction x, the second direction y, and the third direction z are Figure 1 , Figure 8 the directions indicated by the arrows in the figure. The third direction z, the second direction y, and the first direction x intersect pairwise perpendicularly, where the perpendicularity here means fully perpendicular or almost completely perpendicular. For example, within the range of ±5° of full perpendicularity is considered perpendicular.

[0072] In some embodiments, under the requirement of W2≥W3>W1, the secondary battery further satisfies: 10≤W2≤100; 10≤W3≤100; 10≤W1≤100. For example, W2 can be any value among 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or the range between any two values; W3 can be any value among 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or the range between any two values; W1 can be any value among 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or the range between any two values.

[0073] In some embodiments, under the requirement of U3>2U2≥2U1, the secondary battery further satisfies: 1≤U2≤50; 10≤U3≤100; 1≤U1≤50. For example, U2 can be any value among 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50 or the range between any two values; U3 can be any value among 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or the range between any two values; U1 can be any value among 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50 or the range between any two values.

[0074] In some embodiments, the first insulating sheet 20 and the second insulating sheet 30 can use pressure - sensitive adhesive, and the specific materials can be polymer materials such as PP, PE, PC, PET, etc. The first insulating sheet 20 and the second insulating sheet 30 can use the same material or different materials.

[0075] In some embodiments, the present embodiment further provides an electrical device. The electrical device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and so on. The vehicle may be a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, an extended-range vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, and so on; the electric toy includes a stationary or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, and so on; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator, and a power planer, and so on. The embodiments of the present application do not impose special restrictions on the above electrical devices.

[0076] Ten sets of secondary batteries are provided as Examples 1-26. For the structures of the secondary batteries in Examples 1-26, see Figure 1-8 , and Examples 1-26 satisfy At the same time, three sets of batteries are provided as Comparative Examples 1-3. Among them, in the secondary battery of Comparative Example 1, the second insulating layer is pasted to the first insulating film in a full-back adhesive manner, so that there is a force acting between it and the tab; the batteries of Comparative Example 2 and Comparative Example 2 do not satisfy the relationship. The insulation performance of the secondary batteries of Examples 1-26 and Comparative Examples 1-3 is tested. At the same time, the batteries are disassembled, and the tabs are bent 10 times, and then the states of the tab roots of Examples 1-10 and Comparative Examples 1-3 are observed. The results are shown in Tables 1 and 2.

[0077] Among them, the insulation performance test process is as follows: Disassemble the battery, place the first insulating sheet and the second insulating sheet on an insulation resistance meter for insulation testing. If the insulation resistance value under 500V voltage is greater than or equal to 200MΩ, it means that the insulation requirement is met.

[0078] The states of the tab roots have appeared in three situations: obvious tearing, slight tearing, and no tearing. Obvious tearing means that the root of the tab 12 is completely torn. Slight tearing means that the root of the tab 12 is partially torn. No tearing means that the root of the tab 12 is intact. Among them, the degree of slight tearing is smaller than that of obvious tearing.

[0079] The test method for the internal resistance value:

[0080] Among them, the internal resistance value test process is as follows: Place one end of the probe of the resistance meter at the tab root and the other end on the upper surface of the electrode terminal. The internal resistance value in the state of tab tearing is significantly greater than that in the normal state, and 0 < the internal resistance value of the tab in the state of no tearing at the root < the internal resistance value of the tab in the state of slight tearing at the root < the internal resistance value of the tab in the state of obvious tearing at the root < 0.1mΩ.

[0081] Table 1

[0082]

[0083]

[0084] Table 2

[0085]

[0086]

[0087]

[0088] From the test results of Table 1 and Table 2, it can be seen that compared with Comparative Examples 1-3, when is satisfied, the secondary batteries of Examples 1-26 meet the requirements of the insulation test, and there is no obvious tearing at the root of the tab after 10 bends. Combining the test results of the internal resistance value of the tab, it can be seen that by setting the second insulating sheet, it can assist the bending of the tab when the electrode assembly is assembled. The partially adhered second insulating sheet can reduce the probability of tearing and deformation caused by the tab being bent with the insulating sheet fully coated with glue, reduce the internal resistance value of the tab, reduce current overload and improve the battery cycle performance; at the same time, the insulation test results also show that the structure of the present application meets the insulation test requirements, further ensuring the use performance of the secondary battery.

[0089] The above has introduced in detail a secondary battery and an electrical device provided by an embodiment of the present application. Specific examples are used in the present application to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A secondary battery, characterized in that, Comprising: An electrode assembly (10), the electrode assembly (10) including a core body (11) and tab (12) provided on the core body; the tab (12) includes a first section (121) and a second section (122), one end of the first section (121) is connected to the core body (11), and the other end of the first section (121) is connected to the second section (122); the second section (122) is bent relative to the first section (121) so that the second section (122) and the top surface of the core body (11) are oppositely arranged in a first direction (x); A first insulating sheet (20), the first insulating sheet (20) including a third section (201) and a fourth section (202), the third section (201) and the fourth section (202) are connected, and the surface of the second section (122) close to the core body (11) is a first surface (1221); the third section (201) is attached to the first surface (1221), and the fourth section (202) is attached to the first section (121); A second insulating sheet (30), the second insulating sheet (30) including a fixing part (301) and a supporting part (302), the fixing part (301) is connected to the supporting part (302); the surface of the third section (201) away from the first surface (1221) is a second surface (2011), and the fixing part (301) is attached to the second surface (2011); the supporting part (302) is bent relative to the fixing part (301), and the supporting part (302) contacts at least a part of the fourth section (202); Wherein, the thickness of the third section (201) is D1 mm; the thickness of the fixing part (301) is D2 mm; the thickness of the supporting part (302) is D3 mm; the adhesion force between the third section (201) and the first surface (1221) is T1 h, and the adhesion force between the fixing part (301) and the second surface (2011) is T2 h; the volume resistivity of the first insulating sheet (20) is ρ1 Ω·cm; the volume resistivity of the fixing part (301) is ρ2 Ω·cm; the volume resistivity of the supporting part (302) is ρ3 Ω·cm; satisfying:

2. The secondary battery according to claim 1, wherein, The secondary battery further satisfies:

3. The secondary battery according to claim 1, characterized in that, The secondary battery further satisfies:

4. A secondary battery according to claim 1, characterized in that, The secondary battery further satisfies: 0.8 ≤ D2 / D1 ≤ 1.6, or, 1 ≤ D3 / D1 ≤ 1.

5.

5. A secondary battery according to claim 1, characterized in that, The secondary battery further satisfies: 1.0 ≤ T2 / T1 ≤ 2.

5.

6. The secondary battery according to claim 1, wherein, At least a part of the supporting part (302) and the fourth section (202) has a gap (40) in the first direction (x), and the maximum dimension of the gap (40) in the first direction (x) is H mm, satisfying: 0.5 ≤ H ≤ 10.

7. A secondary battery according to any one of claims 1-4, characterized in that, The secondary battery satisfies at least one of the following characteristics: a) 0.5 ≤ D1 ≤ 1.5; b) 0.4 ≤ D2 ≤ 2.4; c) 0.5 ≤ D3 ≤ 2.25; d) 10 ≤ T1 ≤ 25; e) 4 ≤ T2 ≤ 25; f) 1×10 12 ≤ ρ1 ≤ 2×10 13 ; g) 0.1×10 14 ≤ ρ2 ≤ 2×10 14 ; h) 0.1×10 14 ≤ ρ3 ≤ 2×10 14 .

8. A secondary battery according to claim 1, characterized in that, The electrode assembly (10) includes at least two groups, and the electrode assemblies (10) are spaced apart in the third direction (z) to make the tabs (12) symmetrical; The second section (122) has a maximum dimension of W1 mm in the second direction (y), the third section (201) has a maximum dimension of W2 mm in the second direction (y), and the fixing portion (301) has a maximum dimension of W3 mm in the second direction (y), satisfying: W2≥W3>W1; The second section (122) has a maximum dimension of U1 mm in the third direction (z), the third section (201) has a maximum dimension of U2 mm in the third direction (z), and the fixing portion (301) has a maximum dimension of U3 mm in the third direction (z), satisfying: U3>2U2≥2U1; wherein, the third direction (z), the second direction (y) and the first direction (x) intersect pairwise.

9. A secondary battery according to claim 8, characterized in that, The secondary battery satisfies at least one of the following characteristics: i) 10≤W2≤100; j) 10≤W3≤100; k) 10≤W1≤100; l)1≤U2≤50； m) 10≤U3≤100; n) 1≤U1≤50.

10. An electrical device, characterized in that, Comprising the secondary battery according to any one of claims 1-9.

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