Secondary battery, battery pack, and electronic device

Abstract

The secondary battery provided by the embodiment of the utility model comprises a negative electrode plate, the negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer comprises a negative electrode straight region and a negative electrode thinned region located at one end of the negative electrode straight region along a first direction; the positive pole piece comprises a positive pole current collector and a positive pole active material layer, and the positive pole active material layer comprises a positive pole straight area and a positive pole thinned area which deviates from the first direction and is positioned at one end of the positive pole straight area; wherein the first part, facing the negative electrode straight area, of the positive electrode thinned area deviates from the first direction and exceeds the second part, back to the negative electrode straight area, of the positive electrode thinned area. The utility model aims to provide a secondary battery, a battery pack and an electronic device so as to at least improve the energy density of the secondary battery.

Description

Technical Field

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

[0002] In the field of new energy power batteries, a secondary battery refers to a rechargeable battery, also known as a renewable battery or a storage battery. Different from a primary battery, a secondary battery can be charged and discharged in multiple cycles through reverse charging for repeated use. A secondary battery generally includes an electrode assembly, a housing, a cover plate, etc. A cylindrical battery refers to a cylindrical wound core battery, which includes a housing and an electrode assembly. The electrode assembly includes a positive electrode tab, a negative electrode tab and a separator located between the positive electrode tab and the negative electrode tab. These positive electrode tab, negative electrode tab and separator are stacked with each other and then wound into an electrode assembly, and then encapsulated in the housing. Summary of the Utility Model

[0003] Aiming at the problems existing in the related art, the purpose of the utility model is to provide a secondary battery, a battery pack and an electronic device, so as to at least improve the energy density of the secondary battery.

[0004] To achieve the above purpose, an embodiment of the present application provides a secondary battery, including: a negative electrode tab, the negative electrode tab includes a negative current collector and a negative active material layer, the negative active material layer includes a negative flat area and a negative thinning area located at one end of the negative flat area along a first direction; a positive electrode tab, the positive electrode tab includes a positive current collector and a positive active material layer, the positive active material layer includes a positive flat area and a positive thinning area located at one end of the positive flat area away from the first direction, the positive thinning area includes a first part located on the surface of the positive current collector along the thickness direction and a second part on the other surface along the thickness direction; away from the first direction, the negative flat area extends beyond the positive thinning area; wherein, away from the first direction, the first part extends beyond the second part.

[0005] In some embodiments, away from the first direction, the range of the width by which the first part extends beyond the second part is 0.2 mm to 0.8 mm.

[0006] In some embodiments, away from the first direction, the range of the extending beyond width by which the negative flat area extends beyond the positive thinning area is 0.5 mm to 1.5 mm.

[0007] In some embodiments, the secondary battery further includes: an ear glue. Away from the first direction, the positive current collector includes a positive electrode ear protruding from the positive thinning area, and the ear glue is arranged on the positive electrode ear and adjacent to the positive thinning area.

[0008] In some embodiments, the negative thinning area includes a third part located on the surface of the negative current collector along the thickness direction and a fourth part on the other surface along the thickness direction. Along the first direction, the third part extends beyond the fourth part.

[0009] In some embodiments, along the first direction, the range by which the third part exceeds the width of the fourth part is from 0.7 mm to 1.2 mm.

[0010] In some embodiments, along the first direction, the third part extends beyond the positive electrode flat region, and the fourth part extends beyond the positive electrode flat region with the range of the exceeded width being from 0.5 mm to 2.5 mm.

[0011] In some embodiments, the secondary battery is a cylindrical battery, and the secondary battery further includes a separator and an electrolyte.

[0012] Embodiments of the present application further provide a battery pack including the secondary battery according to any one of the above.

[0013] Embodiments of the present application further provide an electronic device including the above battery pack.

[0014] The beneficial technical effects of the present utility model are as follows:

[0015] In the positive electrode thinning region of the embodiment of the present application, the first part facing the negative electrode flat region exceeds the second part facing away from the negative electrode flat region. Compared with the embodiment where the edges of the first part and the second part are aligned, the width of the first part is increased, that is, the widths of the positive electrode thinning region and the positive electrode active material layer are increased. At least the energy density of the secondary battery on the positive electrode side is improved, and the relatively long (i.e., the positive electrode capacity is relatively large) first part faces the negative electrode flat region, while the relatively short (i.e., the positive electrode capacity is relatively small) second part faces away from the negative electrode flat region. The negative electrode flat region can fully receive the lithium ions from the first part with a relatively large positive electrode capacity, and the negative electrode capacity of the negative electrode flat region is better exerted. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 Shows a schematic diagram when the electronic device of the embodiment of the present application is a vehicle.

[0018] Figure 2 Shows a perspective view of a cylindrical battery according to an embodiment of the present application.

[0019] Figure 3 Shows a cross-sectional view of a cylindrical battery according to an embodiment of the present application.

[0020] Figure 4Shows the positive electrode tab and the negative electrode tab of a cylindrical battery according to an embodiment of the present application.

[0021] Figure 5 Shows Figure 4 The electron microscope image of region A in

[0022] Figure 6 Shows Figure 4 The electron microscope image of region B in Detailed implementation manners

[0023] To better understand the spirit of the embodiments of the present application, the following further describes it in conjunction with some preferred embodiments of the present application.

[0024] The embodiments of the present application will be described in detail below. Throughout the specification of the present application, components that are the same or similar and have the same or similar functions are denoted by similar reference numerals. The embodiments of the related drawings described herein are illustrative, diagrammatic, and are used to provide a basic understanding of the present application. The embodiments of the present application should not be construed as a limitation on the present application.

[0025] As used herein, the terms "substantially", "generally", "essentially" and "about" are used to describe and illustrate minor variations. When used in connection with an event or situation, these terms can refer to instances where the event or situation occurs precisely and instances where the event or situation occurs very nearly.

[0026] In this specification, unless specifically specified or limited otherwise, relative terms such as: "central", "longitudinal", "lateral", "front", "rear", "right", "left", "inner", "outer", "lower", "higher", "horizontal", "vertical", "above", "below", "upper", "lower", "top", "bottom" and their derivative terms (such as "horizontally", "downwardly", "upwardly", etc.) should be construed as referring to the directions described in the discussion or depicted in the drawings. These relative terms are only for convenience of description and do not require the present application to be constructed or operated in a specific direction.

[0027] For ease of description, "first", "second", "third", etc. may be used herein to distinguish different components of a figure or a series of figures. "First", "second", "third", etc. are not intended to describe corresponding components.

[0028] The present utility model provides an electronic device 1000. For ease of explanation in the following embodiments, the electronic device 1000 is taken as an example of a vehicle. Refer to Figure 1, a battery pack 1002 is provided inside the vehicle. The battery pack 1002 can be arranged at the bottom, head or tail of the vehicle body 1001. The battery pack 1002 can be used for power supply of the vehicle. For example, the battery pack 1002 can be used as the operating power source of the vehicle. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain power support. The vehicle 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, an extended-range vehicle, etc., but not limited thereto. The working part is the vehicle body, and the battery pack 1002 is arranged at the bottom of the vehicle body and provides power support for the running of the vehicle or the operation of the electrical components inside 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 and an electric tool, etc. The spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc.; the working part can obtain the electric energy of the battery pack 1002 and is a unit component that performs corresponding work, such as the fan blade rotation unit of a fan, the dust suction working unit of a vacuum cleaner, etc. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, such as 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 planer, etc. The embodiments of the present application do not impose special restrictions on the above-mentioned electronic device 1000.

[0029] Figure 2 A perspective view of a secondary battery 100 according to an embodiment of the present application is shown. Figure 3 A cross-sectional view of a secondary battery 100 according to an embodiment of the present application is shown. Figure 4 The positive electrode plate 10 and the negative electrode plate 20 of a secondary battery 100 according to an embodiment of the present application are shown. Figure 5 Shown is Figure 4 The electron microscope image of area A in Figure 6 Shown is Figure 4Electron micrograph of the middle region B. In an embodiment where the secondary battery 100 of the present application is a cylindrical battery, the electrode assembly 120 is mainly formed by winding the positive electrode tab 10 and the negative electrode tab 20, and a separator 122 is provided between the positive electrode tab 10 and the negative electrode tab 20. The positive electrode tab 10 includes a positive current collector 18 and a positive active material layer 16, and the positive active material layer 16 is coated on the surface of the positive current collector 18; the positive current collector 18 includes a positive coating area and a positive tab 181 connected to the positive coating area, the positive coating area is coated with the positive active material layer 16, and the positive tab 181 is not coated with the positive active material layer 16. The negative electrode tab 20 includes a negative current collector 28 and a negative active material layer 26, and the negative active material layer 26 is coated on the surface of the negative current collector 28; the negative current collector 28 includes a negative coating area and a negative tab 281 connected to the negative coating area, the negative coating area is coated with the negative active material layer 26, and the negative tab 281 is not coated with the negative active material layer 26. Taking a lithium-ion battery as an example, the material of the positive current collector 18 can be aluminum, the positive active material layer 16 includes a positive active material, and the positive active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, etc. The material of the negative current collector 28 can be copper, the negative active material layer 26 includes a negative active material, and the negative active material can be carbon or silicon, etc. The material of the separator 122 can be PP or PE, etc. To protect and insulate the electrode assembly 120, an insulating film can also be coated on the outside of the electrode assembly 120, and the insulating film can be synthesized from PP, PE, PET, PVC or other polymer materials.

[0030] In an example where the secondary battery 100 of the embodiment of the present application is a cylindrical battery, see Figure 3 , the electrode assembly 120 is hermetically installed in the housing 200. Along the height direction h of the secondary battery 100, the electrode assembly 120 is disposed between the end wall 111 and the rolling groove 113, and the rolling groove 113 can limit the axial movement of the electrode assembly 120 between the end wall 111 and the rolling groove 113. The electrode assembly 120 is respectively provided with a first tab and a second tab at both ends in the height direction h of the secondary battery 100, and the polarities of the first tab and the second tab are opposite, wherein the first tab faces the opening side, and the first tab is the negative tab 281. It should be noted that in other embodiments, the first tab can also be the positive tab 181, and the second tab is the negative tab 281.

[0031] See Figure 4 and Figure 6, an embodiment of the present application provides a secondary battery 100. The secondary battery 100 includes a stacked and wound positive electrode plate 10, a negative electrode plate 20, and a separator located between the positive electrode plate 10 and the negative electrode plate 20. The negative electrode plate 20 includes a negative electrode current collector 28 and a negative electrode active material layer 26. The negative electrode active material layer 26 includes a negative electrode flat region 24 and a negative electrode thinned region 22 located at one end of the negative electrode flat region 24 along a first direction D (parallel to the height direction h of the secondary battery 100). The negative electrode thinned region 22 is thinner than the negative electrode flat region 24. The positive electrode plate 10 includes a positive electrode current collector 18 and a positive electrode active material layer 16. The positive electrode active material layer 16 includes a positive electrode flat region 14 and a positive electrode thinned region 12 located at one end of the positive electrode flat region 14 away from the first direction D. The positive electrode thinned region 12 is thinner than the positive electrode flat region 14. The positive electrode thinned region 12 includes a first portion 121 located on the surface of the positive electrode current collector 18 along the thickness direction T and a second portion 122 on the other surface along the thickness direction T. Away from the first direction D, the negative electrode flat region 24 extends beyond the positive electrode thinned region 12. Away from the first direction D, the first portion 121 extends beyond the second portion 122. In the positive electrode thinned region 12 of the embodiment of the present application, the first portion 121 overhangs (OH) the second portion 122, which increases the width of the first portion 121 compared to the embodiment where the edges of the first portion 121 and the second portion 122 are aligned. That is, it increases the width of the positive electrode thinned region 12 and the positive electrode active material layer 16, at least improving the energy density of the secondary battery 100 on the positive electrode side. Although the first portion 121 extends relatively long, that is, the positive electrode capacity is large, the first portion 121 does not exceed the negative electrode flat region 24, avoiding the situation of lithium plating. And the negative electrode flat region 24 can completely receive the lithium ions from the first portion 121 with a large positive electrode capacity, better exerting the negative electrode capacity of the negative electrode flat region 24.

[0032] See Figure 4, deviating from the first direction D, the range by which the first part 121 exceeds the width H3 of the second part 122 is from 0.2 mm to 0.8 mm. When H3 is within this range, the energy density of the secondary battery 100 can be increased without lithium plating. If H3 is greater than 0.8 mm, then the first part 121 extends too long, and the alignment will deviate when the positive electrode sheet 10 and the negative electrode sheet 20 are wound, and there is a risk of lithium plating when the first part 121 exceeds the negative flat region 24. If H3 is less than 0.2 mm, the energy density of the secondary battery 100 cannot be effectively increased. When manufacturing the positive electrode sheet 10, H3 can be set to 0.2 mm, plus an engineering deviation of 0.5 mm (considering that the alignment of the active material layer coating engineering ability is ±0.5 mm), and finally a safety margin with H3 less than 0.8 mm is obtained. Along the first direction D, the negative flat region 24 exceeds the positive electrode thinning region 12, that is, exceeds the longer first part 121 thereof, and the range of the exceeded width H4 is from 0.5 mm to 1.5 mm. It can be understood that the deviation occurring during winding is within the scope protected by this application. By setting H4 to be from 0.5 mm to 1.5 mm, even if a deviation occurs during winding, it can be ensured that the negative flat region 24 exceeds the positive electrode thinning region 12, and it can be ensured that although the first part 121 of the positive electrode thinning region 12 exceeds the second part 122, the negative electrode capacity here will be greater than the positive electrode capacity, avoiding the occurrence of lithium plating.

[0033] Continue to refer to Figure 4 , along the first direction D, the negative electrode current collector 28 includes a negative electrode tab 281 protruding from the negative electrode thinning region 22; deviating from the first direction D, the positive electrode current collector 18 includes a positive electrode tab 181 protruding from the positive electrode thinning region 12. This application is a design with the positive electrode tab 181 and the negative electrode tab 281 on different sides. For the electrode assembly 120 with tabs on different sides, the positive electrode flat region 14 corresponds to the negative electrode thinning region 22, the positive electrode thinning region 12 corresponds to the negative electrode flat region 24, and the positive electrode thinning region 12 and the negative electrode thinning region 22 are also on different sides. The tab adhesive 40 is provided on the positive electrode tab 181 and adjacent to the positive electrode thinning region 12. The tab adhesive 40 can be a ceramic layer and can be AT9 material. The tab adhesive 40 is mainly used to avoid burrs piercing the separator when the positive electrode tab 181 is cut, resulting in the direct contact between the positive electrode sheet 10 and the negative electrode sheet 20 and causing the problem of cell failure. And since the tab adhesive 40 covers the part of the positive electrode tab 181 adjacent to the positive electrode thinning region 12, it can limit the width H3 of the positive electrode side edge ramp region / run-off region (that is, the region where the first part 121 exceeds the second part 122), and H3 will not be too large to cause lithium plating.

[0034] Refer to Figure 4 and Figure 5, for the negative electrode side of the secondary battery 100, the negative electrode thinning region 22 includes a third portion 223 located on the surface of the negative electrode current collector 28 along the thickness direction T and a fourth portion 224 on the other surface along the thickness direction T. Along the first direction D, the third portion 223 extends beyond the fourth portion 224, and the range of the width H1 by which the third portion 223 extends beyond the fourth portion 224 is 0.7 mm to 1.2 mm. It is possible to increase safety within the limited width range of the negative electrode active material layer 24. This is equivalent to having more negative electrode active material receiving lithium ions from the positive electrode active material, thereby reducing the occurrence of lithium deposition. When manufacturing the negative electrode sheet 20, H1 can be set to 0.7 mm, plus an engineering deviation of 0.5 mm (considering that the alignment degree of the active material layer coating engineering ability is ±0.5 mm). The finally obtained H1 is within the safety margin of 1.2 mm. Along the first direction D, the negative electrode thinning region 22 extends beyond the positive electrode flat region 14, and both the third portion 223 and the fourth portion 224 extend beyond the positive electrode flat region 14. The range of the width H2 by which the fourth portion 224 extends beyond the positive electrode flat region 14 is 0.5 mm to 2.5 mm. It can be understood that the deviation occurring during winding is within the scope protected by this application. The negative electrode thinning region 22 corresponds to the positive electrode flat region 14. By setting H2 to 0.5 mm to 2.5 mm, even if a deviation occurs during winding, it can be ensured that both the third portion 223 and the longer-extending fourth portion 224 extend beyond the positive electrode flat region 14. Therefore, it can be ensured that the negative electrode capacity here is greater than the positive electrode capacity, and further, the situation of lithium deposition can be avoided when lithium ions from the positive electrode active material layer 16 are transmitted to the negative electrode active material layer 26. Thus, the safety of the negative electrode side of the secondary battery 100 is increased to the greatest extent possible.

[0035] In some embodiments, the secondary battery 100 is a cylindrical battery, and the height of the cylindrical battery (such as Figure 3As shown, the ratio of the distance (from the end wall 111 to the cover plate 130) to the diameter (outer diameter) ranges from 1.7 to 3.3. For example, the height is 80 mm and the diameter is 46 mm; or the height is 15 mm and the diameter is 46 mm. In some embodiments, the cylindrical battery is a 4680 cylindrical battery. In the cylindrical battery, the positive electrode tab 181 faces the positive electrode side, and the negative electrode tab 281 faces the other side. The cylindrical battery has an increasingly higher requirement for energy density. In the embodiments of the present application, the length of the first part 121 of the positive electrode thinning region 12 facing the negative electrode flat region 24 is extended, and the total height of the electrode assembly 120 is not changed. On the premise of ensuring no lithium deposition, the energy density of the cylindrical battery is increased at least on the positive electrode side. In addition, in order to increase the energy density of the battery, the distance between the wound positive electrode plate 10 and the negative electrode plate 20 is very small, and when the battery is in use, the negative electrode plate 20 expands, causing the end of the positive electrode flat region 14 opposite to the positive electrode thinning region 12 to extend into the region corresponding to the negative electrode thinning region 22. This can increase the positive electrode capacity and thus the energy density of the secondary battery 100, while avoiding the sharp part of the positive electrode flat region 14 directly facing the negative electrode flat region 24, thereby relieving stress.

[0036] Embodiments of the present application further provide a battery pack 1002, including the secondary battery 100 of any one of the above, and the battery pack 1002 can have the beneficial effects described above regarding the secondary battery 100.

[0037] Embodiments of the present application further provide an electronic device 1000, including at least one of the secondary battery 100 of any one of the above and the battery pack 1002, and the electronic device 1000 can have the beneficial effects described above regarding the secondary battery 100 and / or the battery pack 1002.

[0038] The positive electrode active material layer 16 of the positive electrode plate 10 and the negative electrode active material layer 26 of the negative electrode plate 20 in the embodiments of the present application are formed using gaskets, coating dies, and coating devices. The opening angle and edge thickness of the gasket are adjusted, and different materials, different viscosities of slurries, and different speeds can be used on the positive electrode current collector 18 and the negative electrode current collector 28 to achieve different coating effects, achieving the set width, depth, etc. The gasket body of the coating die includes a base and two side seats respectively connected to both ends of the base. By designing the gasket opening, the flow rate of the slurry at the edge position of the electrode plate can be reduced, so as to reduce the weight of the slurry coated at the edge of the electrode plate, form the above-mentioned thinning regions on both sides of the electrode plate, reduce the possibility of edge bulging at the coating edges on both sides of the electrode plate, and can also adjust the thickness and uniformity of the thinning regions, so that the thickness of the thinning regions is not too low to cause insufficient active material and lithium deposition, facilitating the improvement of the volume energy density of the battery cell, and also making the thickness of the thinning regions highly consistent and the edge thinning transition relatively smooth, improving the quality of the produced battery.

[0039] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. For those skilled in the art, various modifications and variations can be made to the present utility model. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A secondary battery, characterized in that, Comprising: A negative electrode tab, the negative electrode tab comprising a negative current collector and a negative active material layer, the negative active material layer comprising a negative flat region and a negative thinned region located at one end of the negative flat region in a first direction; A positive electrode tab, the positive electrode tab comprising a positive current collector and a positive active material layer, the positive active material layer comprising a positive flat region and a positive thinned region located at one end of the positive flat region away from the first direction, the positive thinned region comprising a first portion on a surface of the positive current collector in a thickness direction and a second portion on the other surface in the thickness direction; Away from the first direction, the negative flat region extends beyond the positive thinned region; Wherein, away from the first direction, the first portion extends beyond the second portion.

2. The secondary battery according to claim 1, characterized in that, Away from the first direction, the width range of the first portion extending beyond the second portion is 0.2 mm to 0.8 mm.

3. The secondary battery according to claim 1, wherein Away from the first direction, the width range of the negative flat region extending beyond the positive thinned region is 0.5 mm to 1.5 mm.

4. The secondary battery according to claim 1, characterized in that, Further comprising: An ear glue, away from the first direction, the positive current collector comprises a positive electrode ear protruding beyond the positive thinned region, and the ear glue is disposed on the positive electrode ear and adjacent to the positive thinned region.

5. The secondary battery according to claim 1, wherein The negative thinned region comprises a third portion on a surface of the negative current collector in the thickness direction and a fourth portion on the other surface in the thickness direction, and along the first direction, the third portion extends beyond the fourth portion.

6. The secondary battery according to claim 5, characterized in that, Along the first direction, the width range of the third portion extending beyond the fourth portion is 0.7 mm to 1.2 mm.

7. The secondary battery according to claim 6, characterized in that, Along the first direction, the third portion extends beyond the positive flat region, and the fourth portion extends beyond the positive flat region with a width range of 0.5 mm to 2.5 mm.

8. The secondary battery according to claim 1, characterized in that, The secondary battery is a cylindrical battery, and the secondary battery further comprises a separator and an electrolyte.

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

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

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