Battery, preparation method of battery and electronic device

Abstract

The invention discloses a battery, a preparation method of the battery and an electronic device. The battery comprises an electrode assembly and a shell, the shell comprises a top wall, a bottom wall and a side wall, the top wall and the bottom wall are arranged in a spaced mode in the first direction, and the side wall is located between the top wall and the bottom wall. The side wall is fixedly connected with the top wall and the bottom wall to form a containing cavity, and the electrode assembly is arranged in the containing cavity. Viewed in the first direction, the side wall is arranged around the electrode assembly and abuts against the outer peripheral surface of the electrode assembly. A first end part and a second end part are respectively arranged at two ends of the side wall along the surrounding direction of the side wall, and the first end part is fixedly connected with the second end part. In the battery, the side wall is arranged around the electrode assembly and abuts against the peripheral surface of the electrode assembly so as to bind the peripheral surface of the electrode assembly and limit the expansion amplitude of the electrode assembly, so that the risk that the pole piece of the electrode assembly is broken due to excessive expansion in the circulation process is reduced, and the cycle life of the battery is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage, and particularly relates to a battery, a preparation method of the battery, and an electronic device. Background Art

[0002] In the existing cylindrical battery, the wound electrode sheet will be excessively expanded during the cycling process, resulting in the fracture of the electrode sheet, thereby reducing the cycle life of the battery. Summary of the Invention

[0003] In view of the above situation, the present application provides a battery that can extend the cycle life.

[0004] An embodiment of the present application provides a battery, which includes an electrode assembly and a housing. The electrode assembly has a wound structure. The housing includes a top wall, a bottom wall, and a side wall. The top wall and the bottom wall are spaced apart along a first direction, and the side wall is located between the top wall and the bottom wall. The side wall is fixedly connected to the top wall and the bottom wall and forms a receiving cavity, and the electrode assembly is disposed in the receiving cavity. When observed along the first direction, the side wall surrounds the electrode assembly and abuts against the outer peripheral surface of the electrode assembly. Along the circumferential direction of the side wall, a first end portion and a second end portion are respectively provided at both ends of the side wall, and the first end portion is fixedly connected to the second end portion.

[0005] In the above battery, the side wall surrounds the electrode assembly and abuts against the outer peripheral surface of the electrode assembly to restrain the outer peripheral surface of the electrode assembly, limit the expansion amplitude of the electrode assembly, and further reduce the risk of the electrode sheet of the electrode assembly being excessively expanded and fractured during the cycling process, which is beneficial to extending the cycle life of the battery. The first end portion is fixedly connected to the second end portion, so that the side wall can abut against the outer peripheral surface of the electrode assembly during the process of the first end portion being fixedly connected to the second end portion, which is beneficial to improving the stability of the abutment.

[0006] In some embodiments of the present application, along a direction perpendicular to the circumferential direction of the side wall, the thickness of the side wall is T 1 , 50 μm ≤ T 1 ≤ 200 μm, so as to facilitate the structural strength of the first end portion and the second end portion to meet the welding requirements and is beneficial to improving the energy density of the battery.

[0007] In some embodiments of the present application, controlling 50 μm ≤ T 1 ≤ 120 μm can facilitate welding, reduce the risk of the electrode sheet being fractured due to cyclic expansion, and further improve the energy density of the battery.

[0008] In some embodiments of the present application, the thickness of the bottom wall is not less than the thickness of the side wall, and the difference between the thickness of the bottom wall and the thickness of the side wall is T 2 , 0 μm ≤ T 2≤150 μm, so as to facilitate the plastic deformation of the side wall during the preparation of the battery, enabling the side wall to abut against the outer peripheral surface of the electrode assembly, and reducing the space occupied by the side wall, which is beneficial to improving the energy density of the battery.

[0009] In some embodiments of the present application, the outer peripheral surface of the electrode assembly includes an empty foil area. When observed in the second direction, the connection between the first end and the second end coincides with the empty foil area, and the second direction is perpendicular to the first direction. The empty foil area is an area on the current collector where no active material layer is provided. When observed in the second direction X, the connection between the first end and the second end 3 coincides with the empty foil area, so as to reduce the risk of damage to the active material layer of the electrode assembly caused by the high temperature generated during the welding of the first end and the second end, and improve the manufacturing yield of the battery.

[0010] In some embodiments of the present application, the battery includes a pole column, and the pole column is connected to the top wall and is insulated from the top wall. The electrode assembly includes a pole piece group, a first pole tab and a second pole tab. When observed in the first direction, the side wall surrounds the outer peripheral surface of the pole piece group and abuts against the outer peripheral surface of the pole piece group. In the first direction, at least a part of the first pole tab is located between the top wall and the pole piece group, and the first pole tab is electrically connected to the pole column. The second pole tab is located between the bottom wall and the pole piece group, and at least a part of the second pole tab is electrically connected to the bottom wall.

[0011] In some embodiments of the present application, the pole piece group includes a first pole piece, a second pole piece and a separator. The polarity of the second pole piece is opposite to that of the first pole piece, and the separator is disposed between the first pole piece and the second pole piece. The first pole piece, the separator and the second pole piece are wound around a winding axis, and the axial direction of the winding axis is parallel to the first direction. The first pole tab is connected to the first pole piece, and the second pole tab is connected to the second pole piece, so that the pole column and the bottom wall have different polarities, which is convenient for the battery 100 to be electrically connected to an external circuit.

[0012] In some embodiments of the present application, the electrode assembly includes an adhesive member. The adhesive member is adhered to the outer peripheral surface and covers the end part of the pole piece group. The side of the adhesive member facing away from the pole piece group is adhered to the side wall, which is beneficial to improving the stability of the side wall in restraining the outer peripheral surface of the electrode assembly.

[0013] In some embodiments of the present application, the housing is a metal housing. The side wall is welded to the top wall and the bottom wall, and the first end and the second end are welded together. The welding connection between the first end and the second end extends in the first direction. The vertically arranged welding connection can minimize the welding area, which is beneficial to reducing the influence of welding on the electrode assembly.

[0014] The embodiments of the present application further provide a preparation method for any one of the above-mentioned batteries. The preparation method of the battery includes the following steps: Apply an external force to the first end and the second end of the side wall, so that the side wall surrounds the electrode assembly and abuts against the outer peripheral surface of the electrode assembly; Weld the first end and the second end; Weld the side wall and the top wall; Weld the side wall and the bottom wall.

[0015] In the preparation method of the above battery, the side wall surrounds the electrode assembly and abuts against the outer peripheral surface of the electrode assembly, and then the first end and the second end are welded to bind the outer peripheral surface of the electrode assembly, limit the expansion amplitude of the electrode assembly, and further reduce the risk of the electrode sheet of the electrode assembly breaking due to excessive expansion during cycling, which is beneficial to extending the cycle life of the battery.

[0016] In some embodiments of the present application, the battery includes a pole column, and the pole column is connected to the top wall and is insulated from the top wall. The electrode assembly includes a pole piece group and a first pole ear and a second pole ear connecting the pole piece group, and the side wall is disposed around the outer peripheral surface of the pole piece group. Before applying an external force to the first end and the second end of the side wall or before welding the side wall and the top wall, the first pole ear is electrically connected to the pole column, and the second pole ear is electrically connected to the bottom wall, so that the pole column and the bottom wall have different polarities, which is convenient for the battery to be electrically connected to an external circuit.

[0017] In some embodiments of the present application, the welding joint of the first end and the second end is polished to eliminate the surface defects of the welding joint and improve the stability of the fixed connection between the first end and the second end.

[0018] The embodiments of the present application further provide an electronic device, and the electronic device includes any one of the above batteries. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of a battery in an embodiment of the present application.

[0020] Figure 2 It is a schematic internal structural diagram of a battery in an embodiment of the present application.

[0021] Figure 3 It is a schematic internal structural diagram of a battery in another embodiment of the present application.

[0022] Figure 4 It is a schematic disassembly structural diagram of a battery in an embodiment of the present application.

[0023] Figure 5 It is a schematic flow diagram of a preparation method of a battery in an embodiment of the present application.

[0024] Figure 6 It is a schematic structural diagram of an electronic device in an embodiment of the present application.

[0025] Description of the Main Element Symbols Battery 100 Electronic device 200 Electrode assembly 10 Outer peripheral surface 10A Empty foil area 10A1 Electrode sheet group 11 Ending end 11A First electrode sheet 111 Second electrode sheet 112 Separator 113 First tab 12 Second tab 13 Adhesive part 14 Shell 20 Receiving cavity 20A Top wall 21 Bottom wall 22 Side wall 23 First end portion 231 Second end portion 232 Terminal post 30 First direction Z Second direction X The following specific embodiments will further illustrate the present application in conjunction with the above-mentioned drawings. Specific embodiments

[0026] The technical solutions in the embodiments of the present application will be described below with reference to the 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 the embodiments.

[0027] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element. When an element is considered to be "arranged" on another element, it can be directly arranged on the other element or there may be an intermediate element.

[0028] When a numerical value is considered to be "equal" to another numerical value, it means that the two are equal within a set deviation, and the set deviation range is within 5%. That is to say, when at least one of the two numerical values fluctuates within the set deviation range, even if their values are not equal, they are still determined to be approximately equal. When the ratio of a numerical value to another numerical value is "1:1", it means that the two are equal within a set deviation, and the set deviation range is within 5%. That is to say, when at least one of the two numerical values fluctuates within the set deviation range, even if their values are not equal, they are still determined to have an equal ratio.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items. The term "overlap" used herein means that the projected parts of two components overlap or the projections of two components coincide.

[0030] An embodiment of the present application provides a battery, which includes an electrode assembly and a housing. The housing includes a top wall, a bottom wall, and a side wall. The top wall and the bottom wall are spaced apart in a first direction, and the side wall is located between the top wall and the bottom wall. The side wall is fixedly connected to the top wall and the bottom wall and forms a receiving cavity, and the electrode assembly is disposed in the receiving cavity. When observed in the first direction, the side wall surrounds the electrode assembly and abuts against the outer peripheral surface of the electrode assembly. Along the circumferential direction of the side wall, a first end and a second end are respectively provided at both ends of the side wall, and the first end is fixedly connected to the second end.

[0031] In the above battery, the side wall surrounds the electrode assembly and abuts against the outer peripheral surface of the electrode assembly to restrain the outer peripheral surface of the electrode assembly, limit the expansion amplitude of the electrode assembly, and further reduce the risk of the electrode sheet of the electrode assembly breaking due to excessive expansion during cycling, which is beneficial to extending the cycle life of the battery. The first end is fixedly connected to the second end, so that the side wall can abut against the outer peripheral surface of the electrode assembly during the process of fixedly connecting the first end and the second end, which is beneficial to improving the stability of the abutment.

[0032] The embodiments of the present application will be further described below with reference to the accompanying drawings.

[0033] Please refer to Figure 1 and Figure 2 . An embodiment of the present application provides a battery 100. The battery 100 may but is not limited to a secondary battery, and a secondary battery refers to a battery that can be activated by charging after discharging and can be used continuously.

[0034] The battery 100 includes an electrode assembly 10 and a housing 20. The electrode assembly 10 is made of a positive electrode sheet, a separator, and a negative electrode sheet arranged in sequence, and the electrode assembly 10 is used to convert chemical energy into electrical energy.

[0035] The housing 20 includes a top wall 21, a bottom wall 22, and a side wall 23. The top wall 21 and the bottom wall 22 are spaced apart along a first direction Z. The side wall 23 is located between the top wall 21 and the bottom wall 22. The side wall 23 is fixedly connected to the top wall 21 and the bottom wall 22 and forms a receiving cavity 20A. The electrode assembly 10 is disposed in the receiving cavity 20A. When observed along the first direction Z, the side wall 23 surrounds the electrode assembly 10 and abuts against the outer peripheral surface 10A of the electrode assembly 10 to constrain the outer peripheral surface 10A of the electrode assembly 10, limit the expansion amplitude of the electrode assembly 10, and further reduce the risk of the electrode sheets of the electrode assembly 10 being over-expanded during cycling, which is conducive to extending the cycle life of the battery 100.

[0036] It should be noted that "abut" means direct contact between two components.

[0037] Along the circumferential direction of the side wall 23, a first end portion 231 and a second end portion 232 are respectively provided at both ends of the side wall 23. The first end portion 231 is fixedly connected to the second end portion 232, so that the side wall 23 abuts against the outer peripheral surface 10A of the electrode assembly 10 during the process of the first end portion 231 being fixedly connected to the second end portion 232, which is conducive to improving the stability of the abutment.

[0038] In the above battery 100, the side wall 23 surrounds the electrode assembly 10 and abuts against the outer peripheral surface 10A of the electrode assembly 10 to constrain the outer peripheral surface 10A of the electrode assembly 10, limit the expansion amplitude of the electrode assembly 10, and further reduce the risk of the electrode sheets of the electrode assembly 10 being over-expanded during cycling, which is conducive to extending the cycle life of the battery 100. The first end portion 231 is fixedly connected to the second end portion 232, so that the side wall 23 abuts against the outer peripheral surface 10A of the electrode assembly 10 during the process of the first end portion 231 being fixedly connected to the second end portion 232, which is conducive to improving the stability of the abutment.

[0039] Please refer to Figure 1 and Figure 2 , in some embodiments, the electrode assembly 10 is cylindrical, and correspondingly, the housing 20 is cylindrical and adapted to the electrode assembly 10.

[0040] It should be noted that the electrode assembly 10 is not limited to being cylindrical, and may also be triangular prism-shaped, quadrangular prism-shaped, pentagonal prism-shaped, flat-shaped, etc. Correspondingly, the housing 20 is triangular prism-shaped, quadrangular prism-shaped, pentagonal prism-shaped, flat-shaped, etc. adapted to the electrode assembly 10.

[0041] Please refer to Figure 1 and Figure 2 , in some embodiments, the housing 20 is a steel shell, an aluminum shell, etc. Among them, the steel shell may be stainless steel, nickel-plated steel, etc.; the aluminum shell may be aluminum alloy, aluminum manganese alloy, etc.

[0042] In some embodiments, along a direction perpendicular to the circumferential direction of the side wall 23, the first end 231 and the second end 232 at least partially overlap and are then connected by welding. The weld seam formed by welding connects the edges or surfaces of the overlapping area to improve the stability of the fixed connection between the first end 231 and the second end 232.

[0043] Please refer to Figure 3 , in some embodiments, the end face of the first end 231 and the edge of the second end 232 are aligned and then connected into one body by filling weld metal.

[0044] In some embodiments, the edges of the first end 231 and the second end 232 extend along the first direction Z to control the range of influence on the electrode assembly 10 when the first end 231 and the second end 232 are welded, reduce the risk of damage to the electrode assembly 10 caused by the high temperature generated when the first end 231 and the second end 232 are welded, and improve the preparation yield of the battery 100.

[0045] In some embodiments, the tensile strength between the first end 231 and the second end 232 is less than the tensile strength of other parts of the side wall 23. When the battery 100 undergoes thermal runaway, the area between the first end 231 and the second end 232 can rupture in time to form an opening or channel for internal pressure relief, so as to improve the safety performance of the battery 100.

[0046] Please refer to Figure 1 and Figure 4 , in some embodiments, along a direction perpendicular to the circumferential direction of the side wall 23, the thickness of the side wall 23 is T 1 , 50μm ≤ T 1 ≤ 200μm. When T 1 is too small (for example, less than 50μm), it is easy to cause insufficient structural strength of the first end 231 and the second end 232, resulting in difficult welding. When T 1 is too large (for example, greater than 200μm), it is easy to cause the side wall 23 to occupy a large space, resulting in a decrease in the energy density of the battery 100. By defining 50μm ≤ T 1 ≤ 200μm, it is convenient for the structural strength of the first end 231 and the second end 232 to meet the welding requirements, and is beneficial to improving the energy density of the battery 100.

[0047] In some embodiments, controlling 50μm ≤ T 1 ≤ 120μm can facilitate welding, reduce the risk of the pole piece breaking due to cyclic expansion, and further improve the energy density of the battery.

[0048] Optionally, T 1One of 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm, 165μm, 170μm, 175μm, 180μm, 185μm, 190μm, 195μm, 200μm and any other value within the range of 50μm ≤ T 1 ≤ 200μm

[0049] Please refer to Figure 4 , in some embodiments, the thickness of the bottom wall 22 is not less than the thickness of the side wall 23, and the difference between the thickness of the bottom wall 22 and the side wall 23 is T 2 , 0μm ≤ T 2 ≤ 150μm, so as to plastically deform the side wall 23 during the preparation process of the battery 100 to make the side wall 23 abut against the outer peripheral surface 10A of the electrode assembly 10, and can reduce the space occupied by the side wall 23, which is beneficial to improving the energy density of the battery 100.

[0050] Optionally, T 2 is one of 0μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm and any other value within the range of 0μm ≤ T 2 ≤ 150μm

[0051] Please refer to Figure 4 , in some embodiments, the thickness of the top wall 21 is not less than the thickness of the side wall 23, and the difference between the thickness of the top wall 21 and the side wall 23 is T 3 , 0μm ≤ T 3 ≤ 150μm, so as to plastically deform the side wall 23 during the preparation process of the battery 100 to make the side wall 23 abut against the outer peripheral surface 10A of the electrode assembly 10, and can reduce the space occupied by the side wall 23, which is beneficial to improving the energy density of the battery 100.

[0052] Optionally, T 3 is one of 0μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm and any other value within the range of 0μm ≤ T 3 ≤ 150μm

[0053] Please refer to togetherFigure 2 and Figure 4 In some embodiments, the outer peripheral surface 10A of the electrode assembly 10 includes an empty foil area 10A1, which is an area on the current collector where the active material layer is not provided. When observed along the second direction X, the connection between the first end 231 and the second end 232 coincides with the empty foil area 10A1, so as to reduce the risk of damage to the active material layer of the electrode assembly 10 caused by the high temperature generated during the welding of the first end 231 and the second end 232, and improve the preparation yield of the battery 100. Wherein, the second direction X is perpendicular to the first direction Y.

[0054] Please refer to Figure 1 and Figure 4 In some embodiments, the battery 100 includes a pole column 30, and the pole column 30 is connected to the top wall 21 and is insulated from the top wall 21. The electrode assembly 10 includes a pole piece group 11, a first pole tab 12 and a second pole tab 13. The outer peripheral surface 10A of the pole piece group 11 is the outer peripheral surface 10A of the electrode assembly 10. When observed along the first direction Z, the side wall 23 surrounds the outer peripheral surface 10A of the pole piece group 11 and abuts against the outer peripheral surface 10A of the pole piece group 11. Along the first direction Z, at least part of the first pole tab 12 is located between the top wall 21 and the pole piece group 11, and the first pole tab 12 is electrically connected to the pole column 30. At least part of the second pole tab 13 is located between the bottom wall 22 and the pole piece group 11, and the second pole tab 13 is electrically connected to the bottom wall 22, so that the pole column 30 and the bottom wall 22 have different polarities, which is convenient for the battery 100 to be electrically connected to an external circuit.

[0055] Please refer to Figure 2 and Figure 4 In some embodiments, the pole piece group 11 includes a first pole piece 111, a second pole piece 112 and a separator 113. The polarity of the second pole piece 112 is opposite to that of the first pole piece 111, and the separator 113 is disposed between the first pole piece 111 and the second pole piece 112. The first pole piece 111, the separator 113 and the second pole piece 112 are wound around the winding axis O. The axial direction of the winding axis O is parallel to the first direction Z, so that the first pole piece 111 and the second pole piece 112 expand towards the side wall 23 during the cycle, which is convenient for the side wall 23 to limit the expansion amplitude of the electrode assembly 10, and further reduces the risk of the pole pieces of the electrode assembly 10 being over-expanded and broken during the cycle, which is beneficial to extending the cycle life of the battery 100. The first pole tab 12 is connected to the first pole piece 111, and the second pole tab 13 is connected to the second pole piece 112, so that the pole column 30 and the bottom wall 22 have different polarities.

[0056] Optionally, the outer peripheral surface 10A includes at least one of the empty foil area of the first pole piece 111, the empty foil area of the second pole piece 112 and the separator 113.

[0057] Please refer to Figure 2, in some embodiments, the electrode assembly 10 includes an adhesive member 14. The adhesive member 14 is adhered to the outer peripheral surface 10A and covers the end portion 11A of the electrode sheet group 11. One side of the adhesive member 14 facing away from the electrode sheet group 11 is adhered to the side wall 23, which is beneficial to improving the stability of the side wall 23 in restraining the outer peripheral surface 10A of the electrode assembly 10.

[0058] In some embodiments, the adhesive member 14 does not overlap with the first end portion 231 and the second end portion 232, so as to reduce the risk of damage to the adhesive member 14 caused by the high temperature generated during the welding of the first end portion 231 and the second end portion 232, and improve the production yield of the battery 100.

[0059] In some embodiments, the housing 20 is a metal housing. The side wall 23 is welded to the top wall 21 and the bottom wall 22, and the first end portion 231 is welded to the second end portion 232. The welding joint of the first end portion 231 and the second end portion 232 extends along the first direction Z. The vertically arranged welding joint can minimize the welding area, which is beneficial to reducing the influence of welding on the electrode assembly.

[0060] Please refer to Figure 5 , an embodiment of the present application further provides a method for manufacturing a battery 100, including the following steps: Apply an external force to the first end portion 231 and the second end portion 232 of the side wall 23, so that the side wall 23 surrounds the electrode assembly 10 and abuts against the outer peripheral surface 10A of the electrode assembly 10; Weld the first end portion 231 and the second end portion 232; Weld the side wall 23 and the top wall 21; Weld the side wall 23 and the bottom wall 22.

[0061] In the above method for manufacturing the battery 100, after the side wall 23 surrounds the electrode assembly 10 and abuts against the outer peripheral surface 10A of the electrode assembly 10, the first end portion 231 and the second end portion 232 are welded to restrain the outer peripheral surface 10A of the electrode assembly 10, limit the expansion amplitude of the electrode assembly 10, and further reduce the risk of the electrode sheet of the electrode assembly 10 being broken due to excessive expansion during cycling, which is beneficial to extending the cycle life of the battery 100.

[0062] In some embodiments, before applying an external force to the first end portion 231 and the second end portion 232 of the side wall 23 or before welding the side wall 23 and the top wall 21, the first pole ear 12 is electrically connected to the pole column 30, and the second pole ear 13 is electrically connected to the bottom wall 22, so that the pole column 30 and the bottom wall 22 have different polarities, which is convenient for the battery 100 to be electrically connected to an external circuit.

[0063] In some embodiments, the welded joint of the first end portion 231 and the second end portion 232 is polished to eliminate surface defects at the welded joint and improve the stability of the fixed connection between the first end portion 231 and the second end portion 232.

[0064] Please refer to Figure 6 , an embodiment of the present application further provides an electronic device 200. The electronic device 200 includes the battery 100 in any of the above embodiments. The electronic device 200 can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc.

[0065] In the above battery 100 and electronic device 200, the side wall 23 surrounds the electrode assembly 10 and abuts against the outer peripheral surface 10A of the electrode assembly 10 to restrain the outer peripheral surface 10A of the electrode assembly 10, limit the expansion amplitude of the electrode assembly 10, and further reduce the risk of the electrode sheet of the electrode assembly 10 being over-expanded during cycling and causing the electrode sheet to break, which is beneficial to extending the cycle life of the battery 100. The first end portion 231 is fixedly connected to the second end portion 232 so that the side wall 23 can abut against the outer peripheral surface 10A of the electrode assembly 10 during the process of fixedly connecting the first end portion 231 and the second end portion 232, which is beneficial to improving the stability of the abutment.

[0066] Hereinafter, embodiments and comparative examples are given to illustrate the embodiments of the present application more specifically. Various tests and evaluations are carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0067] 1. Battery cycle test: The battery is charged at a constant current of 1.0C to 4.45V at 25°C, charged at a constant voltage of 4.45V until the cut-off current is 0.05C, left standing for 10 minutes, discharged at a constant current of 1.0C to 3.0V, and left standing for 15 minutes. The above is one cycle, and the cycle is repeated 1000 times in the above manner to observe whether the electrode sheet of the battery breaks. The judgment criterion for passing the test: the electrode sheet of the battery does not break. 100 batteries are tested, and the number of cells passing the test is X, and the test pass rate is X / 100.

[0068] 2. Volume energy density test: The battery is placed in an incubator at 25°C and left standing for 30 minutes to make the battery reach a constant temperature. The battery at a constant temperature is charged at a constant current of 0.5C until the voltage reaches 4.53V, then charged at a constant voltage of 4.53V until the current is 0.05C, and discharged at 0.2C until the voltage reaches 3.0V, and the discharge capacity and the plateau voltage are recorded.

[0069] Volume energy density = discharge capacity × plateau voltage / (length × width × thickness of the battery).

[0070] Calculation method of energy density gain: (Energy density of the battery to be tested - Energy density of Comparative Example 1) / Energy density of Comparative Example 1.

[0071] Example 1: A battery with a rated capacity of 60 mAh is assembled as follows: (1) Preparation of the negative electrode sheet: The negative electrode active material artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) are mixed in a weight ratio of 96:1.5:2.5, and deionized water is added as a solvent to prepare a slurry with a weight percentage of 50 wt%. After stirring evenly, the slurry is evenly coated on one surface of the copper foil and then dried at 110 °C to obtain a negative electrode sheet with a negative electrode active material layer coated on one side. When preparing a double-sided coated negative electrode sheet, the above steps are repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a negative electrode active material layer coated on both sides. Then, the coated electrode sheet is cold-pressed, and a negative electrode tab is welded to the negative electrode sheet. The material of the negative electrode tab is copper.

[0072] (2) Preparation of the positive electrode sheet: The positive electrode active material lithium cobaltate (LiCoO 2 )), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75 wt%. After stirring evenly, the slurry is evenly coated on one surface of the aluminum foil and then dried at 90 °C to obtain a positive electrode sheet with a positive electrode active material coated on one side. When preparing a double-sided coated positive electrode sheet, the above coating steps are repeated on the other surface of the aluminum foil. Then, the coated electrode sheet is cold-pressed, and a positive electrode tab is welded to the positive electrode sheet. The material of the positive electrode tab is aluminum.

[0073] (3) Preparation of the electrolyte: In a dry argon atmosphere, first, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent, and then lithium hexafluorophosphate (LiPF 6 ) is added to the basic organic solvent and dissolved and mixed evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0074] (4) Preparation of the separator: A three-layer structure separator is used, which includes an adhesive layer, a base material layer, and an adhesive layer stacked. The material of the first base material layer is polyethylene (PE), the binder in the adhesive layer is PVDF, and the adhesive layer also contains inorganic particles boehmite.

[0075] (5) Preparation of the electrode assembly: The positive electrode sheet, the separator, and the negative electrode sheet are wound.

[0076] (6) Battery assembly: Apply an external force to the first end and the second end of the side wall, so that the side wall surrounds the electrode assembly and abuts against the outer peripheral surface of the electrode assembly; weld the first end and the second end; weld the side wall and the top wall; weld the side wall and the bottom wall to obtain an assembled electrode assembly.

[0077] (7) Electrolyte injection and encapsulation: Inject electrolyte into the assembled electrode assembly, and through processes such as vacuum encapsulation, static placement, hot pressing formation, and shaping, a secondary battery is obtained.

[0078] Comparative Example 1: The housing includes a bottom case and a cover body. The bottom case is an integrally provided side wall and bottom wall. The electrode assembly is directly placed in the bottom case and then the cover body is fixed to the side wall. There is an assembly gap between the outer peripheral surface of the housing and the electrode assembly. It should be noted that other parameters of Comparative Example 1 are the same as those of Example 1.

[0079] Examples 6 - 8: Control the thickness of the bottom wall to be 200 μm, and other parameters except those related to Table 1 are the same as those of Example 1.

[0080] It can be seen from Comparative Example 1 and Examples 1 - 8 that by arranging the side wall to surround the electrode assembly and abut against the outer peripheral surface of the electrode assembly, it is beneficial to improve the passing rate of the battery cycle test and further extend the cycle life of the battery.

[0081] It can be seen from Examples 1 - 5 that by limiting 50 μm ≤ T 1 ≤ 200 μm, the passing rate of the battery cycle test and the energy density of the battery can be improved. It should be noted that when T 1 < 50 μm, it is easy for the structural strength of the side wall to be insufficient, resulting in difficult welding. When T 1 > 200 μm, it is easy for the side wall to occupy too much space, resulting in a significant reduction in the energy density of the battery. Therefore, examples with T 1 < 50 μm and T 1 > 200 μm are not set.

[0082] It can be seen from Examples 1 - 3 that by limiting 50 μm ≤ T 1 ≤ 120 μm, while maintaining a relatively high passing rate of the battery cycle test, the energy density of the battery can be further improved.

[0083] It can be seen from Examples 6 - 8 that by limiting 0 μm ≤ T 2 ≤ 150 μm, the energy density of the battery can be improved. It should be noted that when T 2 > 150 μm, it is easy for the side wall to be too thin, resulting in difficult welding. Therefore, examples with T 2 > 150 μm are not set.

[0084] In addition, those skilled in the art can also make other changes within the spirit of this application. Of course, all such changes made in accordance with the spirit of this application should be included within the scope disclosed in this application.

Claims

1. A battery, characterized in that: The battery comprises: An electrode assembly, wherein the electrode assembly is a wound structure; A shell, the shell comprising a top wall, a bottom wall and a side wall, the top wall and the bottom wall are spaced apart along a first direction, the side wall is located between the top wall and the bottom wall, the side wall is fixedly connected to the top wall and the bottom wall to form a accommodating cavity, the electrode assembly is arranged in the accommodating cavity, and when observed along the first direction, the side wall is arranged around the electrode assembly and abuts against the outer peripheral surface of the electrode assembly, and along the circumferential direction of the side wall, the two ends of the side wall are respectively provided with a first end and a second end, and the first end is fixedly connected to the second end.

2. The battery according to claim 1, characterized in that The thickness of the side wall is T1, 50 μm≤T1≤200 μm.

3. The battery according to claim 2, characterized in that 50μm≤T1≤120μm.

4. The battery according to claim 2, characterized in that The thickness of the bottom wall is not less than the thickness of the side wall, and the difference between the thickness of the bottom wall and the side wall is T2, 0μm≤T2≤150μm.

5. The battery according to claim 1, characterized in that The outer peripheral surface of the electrode assembly includes a hollow foil area. When viewed along a second direction, a connection between the first end and the second end coincides with the hollow foil area. The second direction is perpendicular to the first direction.

6. The battery according to claim 1, characterized in that The battery comprises a pole, the pole is connected to the top wall and is insulated from the top wall; The electrode assembly includes a pole piece group, a first pole ear and a second pole ear. When viewed along the first direction, the side wall surrounds the outer peripheral surface of the pole piece group and abuts against the outer peripheral surface of the pole piece group. Along the first direction, at least part of the first pole ear is located between the top wall and the pole piece group, and the first pole ear is electrically connected to the pole column. The second pole ear is located between the bottom wall and the pole piece group, and at least part of the second pole ear is electrically connected to the bottom wall.

7. The battery according to claim 6, characterized in that The pole piece group includes a first pole piece, a second pole piece and a diaphragm, the polarity of the second pole piece is opposite to that of the first pole piece, the diaphragm is arranged between the first pole piece and the second pole piece, the first pole piece, the diaphragm and the second pole piece are wound around a winding axis, the axial direction of the winding axis is parallel to the first direction, the first pole ear is connected to the first pole piece, and the second pole ear is connected to the second pole piece.

8. The battery according to claim 7, characterized in that The electrode assembly includes an adhesive member, which is bonded to the outer peripheral surface and covers the tail end of the electrode assembly, and the side of the adhesive member facing away from the electrode assembly is bonded to the side wall.

9. The battery according to claim 1, characterized in that The shell is a metal shell, the side wall is connected to the top wall and the bottom wall by welding, and the first end is connected to the second end by welding.

10. The battery according to claim 9, characterized in that The welded connection between the first end and the second end extends along the first direction.

11. The battery according to claim 1, characterized in that The electrode assembly is cylindrical.

12. A method for preparing a battery according to any one of claims 1 to 11, characterized in that: The method for preparing the battery comprises the following steps: Applying external force to the first end and the second end of the side wall so that the side wall is disposed around the electrode assembly and abuts against the outer peripheral surface of the electrode assembly; welding the first end portion and the second end portion; Welding the side wall and the top wall; The side walls and the bottom wall are welded.

13. The method for preparing a battery according to claim 12, characterized in that: The battery comprises a pole, the pole is connected to the top wall and is insulated from the top wall, the electrode assembly comprises a pole piece group and a first pole ear and a second pole ear connected to the pole piece group, and the side wall is arranged around the outer peripheral surface of the pole piece group; Before applying external force to the first end and the second end of the side wall or before welding the side wall and the top wall, the first pole tab is electrically connected to the pole, and the second pole tab is electrically connected to the bottom wall.

14. The method for preparing a battery according to claim 13, characterized in that: A polishing process is performed on a welding point between the first end portion and the second end portion.

15. An electronic device, characterized in that: The electronic device comprises the battery according to any one of claims 1 to 11.

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