Secondary battery, electric equipment and preparation method of secondary battery
Through the split shell structure and bent plate technology, the problem of insufficient energy density of secondary batteries is solved, higher energy density and stability are achieved, the risk of leakage is reduced, and the preparation efficiency is improved.
Patent Information
- Application Number
- CN202510816385.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-18
- Publication Date
- 2025-09-05
AI Technical Summary
The energy density of existing secondary batteries is limited by the shell welding process and material thickness, resulting in insufficient space utilization and affecting the overall energy density.
A split shell structure is adopted, and the side walls and end walls are formed by bending the plate to reduce the width and thickness of the end wall. The shell cover is connected by laser welding and other methods to meet the welding width requirements and improve the space utilization and stability of the shell.
The energy density of the secondary battery is improved, the sealing and stability of the shell are enhanced, the risk of leakage is reduced, and the preparation efficiency is improved.
Smart Images
Figure CN120601007A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of energy storage technology, and in particular to a secondary battery, an electrical device, and a method for preparing the secondary battery. Background Art
[0002] Secondary batteries include steel-cased batteries and soft-pack batteries. Currently, the outer shell of steel-cased batteries is primarily formed using two methods: Method 1: The shell is first punched to form a recess and flange, and the shell cover is welded to the flange. Method 2: The shell is first punched to form a recess, and the shell cover is directly welded to the sidewall of the shell. However, the energy density of secondary batteries formed using these two methods still has room for improvement. Summary of the Invention
[0003] Regarding the secondary batteries formed by the two aforementioned methods, the inventors discovered that in method one, the flange formed by punching is generally relatively wide. After welding the flanges of the shell cover and shell, a portion of the flange needs to be removed. At this point, the remaining flange is relatively wide and still occupies a certain amount of space. The shell wall thickness cannot be too thin, otherwise the shell will easily break after punching, resulting in a loss of energy density in the secondary battery. In method two, the shell sidewall dimensions must meet the welding width required by the welding process, and the shell wall thickness cannot be too thin, otherwise the shell will easily break after punching, resulting in a loss of energy density in the secondary battery.
[0004] In view of the above situation, it is necessary to provide a secondary battery that is conducive to improving energy density.
[0005] The first aspect of the present application provides a secondary battery, comprising a housing and an electrode assembly, wherein the electrode assembly is housed within the housing. The housing is a split structure, comprising a housing, a first housing cover, and a second housing cover. The housing comprises side walls and end walls, wherein the side walls enclose a through cavity, and the end walls are disposed at both ends of the side walls along the through-cavity direction. The projections of the side walls and the end walls along the through-cavity direction are both annular, and the end walls protrude from the side walls in a direction perpendicular to the through-cavity direction. The first housing cover and the second housing cover are respectively fixedly connected to the end walls at both ends of the side wall along the through-cavity direction. The thickness of the side wall is D, and D≤0.2mm.
[0006] By adopting a split-piece structure for the outer shell, the outer shell, first shell cover, and second shell cover can be processed separately when manufacturing the secondary battery outer shell. In this case, the side walls and end walls of the outer shell can be formed by bending the sheet material first, thereby reducing the width of the end walls. The first shell cover and the second shell cover are then fixedly connected to the end walls, thereby reducing the space occupied by the end walls. Furthermore, when bending, a thinner sheet material (less than or equal to 0.2 mm) can be used to reduce the wall thickness of the outer shell, thereby improving the energy density of the secondary battery.
[0007] In one or more of the above embodiments, the end wall includes a first portion connected to the side wall along a direction through the cavity, and a second portion connected to the first portion in a direction perpendicular to the direction through the cavity and protruding from the side wall. The width of the second portion in the direction perpendicular to the direction through the cavity is W, and 0.03mm≤W≤3mm. When the first shell cover and the second shell cover are welded to the end wall, by setting 0.03mm≤W, the width of the second portion can be kept from being too small, which is conducive to meeting the welding width required by the welding process; by setting W≤3mm, the width of the second portion can be kept from being too large, which is conducive to reducing the amount of the second portion that needs to be removed after welding, thereby facilitating improving the efficiency of the fixed connection of the first shell cover and the second shell cover to the end wall.
[0008] In one or more of the above embodiments, 0.05mm≤W<0.3mm. When the first shell cover and the second shell cover are welded to the end wall, by setting 0.05mm≤W, the wall thickness of the side wall can be reduced while meeting the welding width required by the welding process, which is beneficial to further improve the energy density of the secondary battery; by setting W<0.3mm, the amount of the second portion that needs to be removed after welding can be reduced, which is beneficial to further improve the efficiency of the fixed connection between the first shell cover and the second shell cover and the end wall.
[0009] In one or more of the above embodiments, the end wall includes a first portion connected to the side wall along the through-direction of the cavity and a second portion connected to the first portion in a direction perpendicular to the through-direction of the cavity and protruding from the side wall, and the wall thickness of the second portion is H, 0.02mm≤H≤0.5mm. By setting 0.02mm≤H, the thickness of the second portion is not too thin, which can improve the structural strength of the second portion. When the first shell cover and the second shell cover are welded and fixed to the end wall, it is beneficial to improve the stability of the fixation of the first shell cover and the second shell cover to the second portion, thereby helping to reduce the risk of leakage of the secondary battery due to fixation failure. By setting H≤0.5mm, the thickness of the second portion is not too thick. When the first shell cover and the second shell cover are welded and fixed to the end wall, the second portion can be more easily melted, which is beneficial to improve the convenience of fixing the first shell cover and the second shell cover to the end wall.
[0010] In one or more of the above embodiments, 0.03mm≤H≤0.15mm. Setting 0.03mm≤H further improves the stability of the fixation between the first and second shell covers and the end wall, thereby further reducing the risk of secondary battery leakage due to fixation failure. Setting H≤0.15mm further improves the convenience of fixing the first and second shell covers to the end wall and helps reduce the overall weight of the housing.
[0011] In one or more of the above embodiments, the end walls are formed by bending the sheet material and are integrally formed with the side walls, with the connection between the end walls and the side walls forming a rounded transition. In this case, the side and end walls of the shell body are formed by the bending process. Compared with forming the side and end walls by punching, the bending process can preserve the surface characteristics of the raw material forming the shell body (such as the rough surface, matte surface, and glossiness), reduce the number of steps required to further process the shell body surface, and improve the production efficiency of secondary batteries.
[0012] In one or more of the above embodiments, the end wall includes a first portion connected to the side wall along a direction extending through the cavity, and a second portion connected to the first portion in a direction perpendicular to the direction extending through the cavity and protruding from the side wall, wherein the wall thickness of the second portion is less than that of the side wall. When the side wall and end wall of the housing are formed by a bending process, the radius of the fillet formed by the side wall and the end wall after bending can be reduced, which is beneficial for improving the energy density of the secondary battery and increasing the connection area between the end wall and the first shell cover and the second shell cover.
[0013] In one or more of the above embodiments, the housing includes a weld mark extending from the end wall at one sidewall to the end wall at the other sidewall along the through-hole direction of the cavity. In this case, after the sidewalls and end walls of the housing are formed by bending the sheet material, welding the ends of the housing along the direction in which the sidewalls and end walls enclose each other helps improve the sealing performance of the housing.
[0014] In one or more of the above embodiments, D is ≤ 0.04 mm; along the through-hole direction of the cavity, the sidewall height is L, and L is ≥ 4 mm. In this case, the sidewalls and end walls formed by the punching process are prone to cracking, while the sidewalls and end walls formed by the bending process are less prone to cracking.
[0015] In one or more of the above embodiments, D≥0.02 mm. By setting D≥0.02 mm, the thickness of the side wall is not too thin, and the supporting strength of the side wall can be improved.
[0016] In one or more of the above embodiments, the first shell cover and the second shell cover are respectively welded to the end walls at both ends of the side wall, which is beneficial to improve the stability of the first shell cover and the second shell cover and the end wall, thereby reducing the risk of secondary battery leakage caused by fixing failure.
[0017] The second aspect of the present application provides an electric device, comprising the secondary battery of the first aspect of the present application. The secondary battery of the first aspect of the present application has a high energy density, which is beneficial to improving the endurance of the electric device.
[0018] The third aspect of the present application provides a method for preparing a secondary battery, comprising the following steps: bending two side edges of a plate arranged opposite to each other along a first direction toward a plane perpendicular to the first direction to form side walls and end walls, wherein the end walls are connected to both ends of the side wall along the first direction, and the end walls protrude from at least one surface of the side wall along the thickness direction. Bending the plate several times toward a plane perpendicular to a second direction, and connecting both ends of the plate along the second direction, the plates enclose forming a through cavity so that the side walls and end walls form a shell body, wherein the second direction is perpendicular to the first direction and the thickness direction of the side wall. Placing the electrode assembly in the cavity, and fixing the first shell cover and the second shell cover to the end walls at both ends of the side wall along the through direction of the cavity, wherein the shell body, the first shell cover and the second shell cover form the outer shell of the secondary battery. This is conducive to preparing a secondary battery with a higher energy density.
[0019] In one or more of the above embodiments, welding the two ends of the side wall along the second direction can reduce the possibility of disconnection of the two ends of the plate along the second direction under the action of bending stress, which is beneficial to improving the sealing performance of the housing.
[0020] In one or more of the above embodiments, the portion of the end wall protruding from the side wall is squeezed inward from both sides along the thickness direction of the end wall, which can reduce the fillet radius formed by the side wall and the end wall, thereby improving the energy density of the secondary battery.
[0021] In one or more of the above embodiments, the thickness of the plate is less than 0.04 mm. The side walls and end walls formed by the punching process are prone to cracking, while the side walls and end walls formed by the bending process are not prone to cracking.
[0022] In one or more of the above embodiments, the first shell cover and the second shell cover are respectively welded to the end walls at both ends of the side wall along the through-going direction of the cavity. This helps to improve the stability of the first shell cover and the second shell cover and the end walls, thereby helping to reduce the risk of secondary battery leakage caused by fixing failure. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 This is an overall schematic diagram of a secondary battery provided in one embodiment of the present application.
[0024] Figure 2 An exploded view of a secondary battery provided in one embodiment of the present application.
[0025] Figure 3 For the Figure 1 Cross-section along the midline AA.
[0026] Figure 4 For the Figure 1 Cross-section along the midline BB.
[0027] Figure 5A schematic diagram of bending a plate to form side walls and end walls provided in one embodiment of the present application.
[0028] Figure 6 A schematic diagram of enclosing plates to form a through cavity provided in one embodiment of the present application.
[0029] Figure 7 This is an overall schematic diagram of an electrical device provided in one embodiment of the present application.
[0030] Description of main component symbols 1000. Electrical equipment; 100. Secondary battery; 10. Casing; 11. Body; 111. Side wall; 112. End wall; 1121. First portion; 1122. Second portion; 12. First shell cover; 13. Second shell cover; 20. Electrode assembly; 21. Negative electrode sheet; 22. Positive electrode sheet; 23. Diaphragm; 30. Post; 40. Insulator; 50. Negative tab; 501. Negative tab bundle; 60. Positive tab; 601. Positive tab bundle; X, first direction; Y, second direction. DETAILED DESCRIPTION
[0031] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.
[0032] It should be noted that when an element is considered to be “connected” to another element, it may be directly connected to the other element or there may be a centrally disposed element. When an element is considered to be “disposed on” another element, it may be directly disposed on the other element or there may be a centrally disposed element.
[0033] Unless otherwise specified, the term "plurality" as used herein means two or more than two.
[0034] The terms "first", "second", etc. are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implying the quantity, specific order or primary and secondary relationship of the technical features indicated.
[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0036] It should be understood that, taking into account actual manufacturing tolerances, in the technical solution of this application, when two components are arranged parallel or perpendicularly, the angle between the two components is allowed to have a tolerance of within 10% relative to the angle corresponding to the parallel or perpendicular arrangement. In the technical solution of this application, when two parameters are equal, a tolerance of within 10% is allowed between the two parameters.
[0037] The present application provides a secondary battery comprising a housing and an electrode assembly, wherein the electrode assembly is housed within the housing. The housing is a split structure comprising a housing, a first housing cover, and a second housing cover. The housing comprises side walls and end walls, wherein the side walls enclose a through cavity, and the end walls are disposed at both ends of the side walls along the through-cavity direction. The projections of the side walls and end walls along the through-cavity direction are both annular, and the end walls protrude from the side walls in a direction perpendicular to the through-cavity direction. The first housing cover and the second housing cover are respectively fixedly connected to the end walls at both ends of the side wall along the through-cavity direction. The thickness of the side wall is D, where D is ≤ 0.2 mm.
[0038] In the secondary battery of the present application, by adopting a split-type outer shell structure, when manufacturing the secondary battery outer shell, the shell body, the first shell cover, and the second shell cover can be processed separately. In this case, the side walls and end walls of the shell body can be formed by bending the sheet material first, thereby reducing the width of the end walls. At this time, the first shell cover and the second shell cover are respectively fixedly connected to the end walls, which can reduce the space occupied by the end walls. In addition, when bending, a thinner sheet material can be used to reduce the wall thickness of the shell body, thereby facilitating the improvement of the energy density of the secondary battery.
[0039] The following will describe some embodiments of the present application in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.
[0040] See also Figure 1 and Figure 2The embodiment of the present application provides a secondary battery 100, comprising a housing 10 and an electrode assembly 20, wherein the housing 10 is filled with an electrolyte and the electrode assembly 20 is housed within the housing 10. The housing 10 is a split structure, comprising a housing 11, a first housing cover 12, and a second housing cover 13. The material of the housing 11 includes, but is not limited to, metal materials such as iron, aluminum, nickel, copper, and titanium, and the materials of the first housing cover 12 and the second housing cover 13 may be the same as or different from the material of the housing 11. The housing 10 being a split structure means that the housing 11, the first housing cover 12, and the second housing cover 13 can be manufactured separately, and then the first housing cover 12 and the second housing cover 13 are fixedly connected to the housing 11 to form the housing 10. The methods of fixed connection include, but are not limited to, adhesive fixing, riveting fixing, and welding fixing, wherein welding includes, but is not limited to, laser welding, atomic beam welding, and brazing. In some embodiments, the materials of the housing 11, the first housing cover 12, and the second housing cover 13 are all metal materials, and the first housing cover 12 and the second housing cover 13 are fixed to the housing 11 by laser welding.
[0041] See also Figure 2 The shell body 11 includes side walls 111 and end walls 112. The side walls 111 enclose a through cavity, and the end walls 112 are provided at both ends of the side walls 111 along the through-hole direction of the cavity. The wall thickness of the side wall 111 is D, where D is ≤ 0.2 mm. For example, D is 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.08 mm, 0.1 mm, 0.15 mm, 0.2 mm, or any value between the listed end values. The wall thickness of the end wall 112 can be less than, equal to, or greater than the wall thickness of the side wall 111. In some embodiments, when manufacturing the shell body 11, specific locations (such as the side or middle) of the sheet material can be pre-rolled. Thus, after the sheet material is bent to form the side walls 111 and end walls 112 of the shell body 11, the wall thickness of the end wall 112 is less than, equal to, or greater than the wall thickness of the side wall 111. In some other embodiments, the side walls 111 and the end walls 112 of the housing 11 are formed by sheet metal processing such as cutting the sheet.
[0042] Along the through-going direction of the cavity, the projections of the side wall 111 and the end wall 112 are both annular. Along the direction perpendicular to the through-going direction of the cavity, the end wall 112 protrudes from the side wall 111. The so-called annular shape can be regular or irregular, such as a circular ring, a rectangular ring, or other polygonal ring. Figure 3 or Figure 4The end wall 112 includes a first portion 1121 and a second portion 1122. The first portion 1121 is connected to the side wall 111 along the through-going direction of the cavity. The second portion 1122 is connected to the first portion 1121 along a direction perpendicular to the through-going direction of the cavity and is a portion of the end wall 112 protruding from the side wall 111 along the direction perpendicular to the through-going direction of the cavity ( Figure 3 and Figure 4 The dashed lines in the figure schematically depict the boundary between the first portion 1121 and the sidewall 111, and the boundary between the second portion 1122 and the first portion 1121. The second portion 1122 protrudes from the sidewall 111 from the inside outward in a direction perpendicular to the through-going direction of the cavity, or alternatively, the second portion 1122 protrudes from the sidewall 111 from the outside inward in a direction perpendicular to the through-going direction of the cavity. In some embodiments, when manufacturing the shell 11, after bending the sheet material to form the sidewalls 111 and end walls 112 of the shell 11, the second portion 1122 can be extruded inward from both sides along the wall thickness direction of the end wall 112, such that the wall thickness of the second portion 1122 is less than that of the sidewall 111.
[0043] The first shell cover 12 and the second shell cover 13 are respectively fixedly connected to the end walls 112 at both ends of the side wall 111 along the direction through which the cavity passes. By adopting a split structure for the outer shell 10, when manufacturing the outer shell 10 of the secondary battery 100, the shell body 11, the first shell cover 12, and the second shell cover 13 can be processed separately. In this case, the side walls 111 and end walls 112 of the shell body 11 can be formed by bending the sheet material to reduce the width of the end wall 112. At this time, the first shell cover 12 and the second shell cover 13 are respectively fixedly connected to the end wall 112, which can reduce the space occupied by the end wall 112. In addition, when bending, a thinner sheet material (less than or equal to 0.2 mm) can be used to reduce the wall thickness of the shell body 11, thereby facilitating an improvement in the energy density of the secondary battery 100. In some embodiments, the first shell cover 12 and the second shell cover 13 are respectively welded to the end walls 112 at both ends of the side wall 111. This is beneficial to improving the stability of fixing the first shell cover 12 and the second shell cover 13 to the end wall 112 , thereby reducing the risk of leakage of the secondary battery 100 due to fixing failure.
[0044] In some embodiments, the housing 11 includes a weld mark (not shown) extending from the end wall 112 at one end of the side wall 111 to the end wall 112 at the other end of the side wall 111 along the through-hole direction of the cavity. In this case, after the side walls 111 and end walls 112 of the housing 11 are formed by bending the sheet material, welding the ends of the housing 11 along the direction enclosed by the side walls 111 and end walls 112 helps improve the sealing performance of the housing 10.
[0045] In some embodiments, D is ≤ 0.04 mm. Along the through-hole direction of the cavity, the height of the sidewall 111 is L, where L is ≥ 4 mm. For example, L is 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, 15 mm, or 20 mm. In this case, the sidewall 111 and end wall 112 formed by the punching process are prone to cracking, while the sidewall 111 and end wall 112 formed by the bending process are less prone to cracking.
[0046] In some embodiments, D≥0.02 mm. By setting D≥0.02 mm, the thickness of the side wall 111 is not too thin, and the supporting strength of the side wall 111 can be improved.
[0047] In some embodiments, along a direction perpendicular to the through-direction of the cavity, the width of the second portion 1122 is W, and 0.03 mm ≤ W ≤ 3 mm. For example, W is 0.03 mm, 0.05 mm, 0.07 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, or any value between the listed endpoints. When the first shell cover 12 and the second shell cover 13 are welded to the end wall 112, by setting 0.03 mm ≤ W, the width of the second portion 1122 can be kept from being too small, which is conducive to meeting the welding width required by the welding process. By setting W ≤ 3 mm, the width of the second portion 1122 can be kept from being too large, which is conducive to reducing the amount of the second portion 1122 that needs to be removed after welding, thereby facilitating improving the efficiency of the fixed connection between the first shell cover 12 and the second shell cover 13 and the end wall 112.
[0048] In some embodiments, 0.05 mm ≤ W < 0.3 mm. When the first shell cover 12 and the second shell cover 13 are welded to the end wall 112, by setting 0.05 mm ≤ W, the wall thickness of the side wall 111 can be reduced while meeting the welding width required by the welding process, which is beneficial for further improving the energy density of the secondary battery 100. By setting W < 0.3 mm, the amount of second portion 1122 that needs to be removed after welding can be reduced, which is beneficial for further improving the efficiency of the fixed connection between the first shell cover 12 and the second shell cover 13 and the end wall 112.
[0049] In some embodiments, the wall thickness of the second portion 1122 is H, and 0.02 mm ≤ H ≤ 0.5 mm. For example, H is 0.02 mm, 0.03 mm, 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, or any value between the listed endpoints. By setting 0.02 mm ≤ H, the thickness of the second portion 1122 is not too thin, which can improve the structural strength of the second portion 1122. When the first and second shell covers 12 and 13 are welded to the end wall 112, the stability of the fixation between the first and second shell covers 12 and 13 and the second portion 1122 is improved, thereby reducing the risk of leakage of the secondary battery 100 due to fixation failure. By setting H≤0.5mm, the thickness of the second portion 1122 is not too thick. When the first shell cover 12 and the second shell cover 13 are welded and fixed to the end wall 112, the second portion 1122 can be easily melted, which is beneficial to improving the convenience of fixing the first shell cover 12 and the second shell cover 13 to the end wall 112.
[0050] In some embodiments, 0.03 mm ≤ H ≤ 0.15 mm. Setting 0.03 mm ≤ H further improves the stability of the fixation between the first and second shell covers 12 , 13 and the end wall 112 , thereby further reducing the risk of leakage from the secondary battery 100 due to a fixation failure. Setting H ≤ 0.15 mm further improves the ease of fixation between the first and second shell covers 12 , 13 and the end wall 112 and helps reduce the overall weight of the housing 10 .
[0051] In some embodiments, the end wall 112 is formed by bending a sheet material and is integrally formed with the side wall 111. The connection between the end wall 112 and the side wall 111 is rounded. In this case, the side walls 111 and end walls 112 of the housing 11 are formed by a bending process. Compared to forming the side walls 111 and end walls 112 by a punching process, the bending process can preserve the surface characteristics (such as the roughness, matte surface, and glossiness) of the raw material forming the housing 11. This can reduce the number of steps required to further process the surface of the housing 11, thereby improving the production efficiency of the secondary battery 100.
[0052] In some embodiments, the wall thickness of the second portion 1122 is less than the wall thickness of the side wall 111, that is, H < D. When the side wall 111 and the end wall 112 of the housing 11 are formed by a bending process, the radius of the fillet formed by the bent side wall 111 and the end wall 112 can be reduced, which is beneficial for improving the energy density of the secondary battery 100 and increasing the connection area between the end wall 112 and the first and second housing covers 12 and 13.
[0053] See also Figure 3 or Figure 4The electrode assembly 20 includes a negative electrode sheet 21, a positive electrode sheet 22 and a separator 23. The negative electrode sheets 21 and the positive electrode sheets 22 are arranged alternately. The separator 23 is arranged between the negative electrode sheet 21 and the positive electrode sheet 22, thereby separating the negative electrode sheet 21 and the positive electrode sheet 22.
[0054] In some embodiments, the electrode assembly 20 is a laminated structure, wherein the negative electrode sheets 21 and the positive electrode sheets 22 are alternately stacked, and the separator 23 is disposed between the negative electrode sheets 21 and the positive electrode sheets 22. In some embodiments, the electrode assembly 20 is a wound structure, wherein the negative electrode sheets 21 and the positive electrode sheets 22 are alternately wound, and the separator 23 is disposed between the negative electrode sheets 21 and the positive electrode sheets 22. In some embodiments, the negative electrode sheet 21 includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is disposed on at least one surface of the negative electrode current collector along the thickness direction. For example, when a negative electrode sheet 21 is located at the outermost layer of the electrode assembly 20, the negative electrode active material layer of the negative electrode sheet 21 may be disposed only on the surface of the negative electrode current collector facing the interior of the electrode assembly 20 along the thickness direction. In some embodiments, the positive electrode sheet 22 includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is disposed on at least one surface of the positive electrode current collector along the thickness direction. For example, when a positive electrode sheet 22 is located at the outermost layer of the electrode assembly 20 , the positive active material layer of the positive electrode sheet 22 may be provided only on the surface of the positive current collector facing the interior of the electrode assembly 20 along the thickness direction.
[0055] In some embodiments, the material of the negative electrode current collector includes but is not limited to copper foil, copper alloy foil, nickel foil, titanium foil, nickel foam and copper foam, and the material of the positive electrode current collector includes but is not limited to aluminum foil and aluminum alloy foil. The material of the negative electrode active material layer includes at least one of graphite, hard carbon, soft carbon, silicon, silicon oxide material and silicon carbon material, and the material of the positive electrode active material layer includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese iron phosphate or lithium manganese oxide. The material of the separator 23 includes but is not limited to at least one of polyethylene (PE), polypropylene (PP)-based polyolefins (PO), polyesters (such as polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex and aramid.
[0056] In some embodiments, the housing 10 is a metal housing, and the housing 10 is insulated and provided with a pole 30, the negative pole piece 21 is electrically connected to the housing 10, and the positive pole piece 22 is electrically connected to the pole 30. In some embodiments, please refer to Figures 1 to 4 The housing 10 is insulated and provided with two poles 30, and the negative pole piece 21 and the positive pole piece 22 are electrically connected to different poles 30. The poles 30 can be insulated and provided on the side wall 111 of the housing 11, the first housing cover 12 or the second housing cover 13. In some embodiments, please refer to Figure 3 and Figure 4The pole 30 is insulated from the housing 10 by an insulating member 40. The insulating member 40 includes but is not limited to an insulating gasket and an insulating sleeve. The insulating gasket is provided between the contact surface of the pole 30 and the housing 10, and the insulating sleeve is wrapped around the outer circumference of the pole 30. The material of the insulating member 40 includes but is not limited to plastic and rubber.
[0057] In some embodiments, the negative electrode sheet 21 is provided with a negative electrode tab 50 (see Figure 3 ), the negative tabs 50 are gathered to form a negative tab bundle 501 and then connected to the pole 30. The positive electrode sheet 22 is provided with a positive tab 60 (see Figure 4 ), the positive electrode tabs 60 are gathered to form a positive electrode tab bundle 601 and then connected to the electrode column 30.
[0058] In some embodiments, the electrode sheet located at the outermost layer of the electrode assembly 20 is provided with a hollow foil area, which is in contact with the first shell cover 12 or the second shell cover 13. In some embodiments, the electrode sheet located at the outermost layer of the electrode assembly 20 is provided with a hollow foil area, which is indirectly connected to the first shell cover 12 or the second shell cover 13 via a conductive member. The conductive member includes but is not limited to conductive protrusions, metal springs, and conductive adhesive. The conductive protrusions can be formed by laser roughening the first shell cover 12 or the second shell cover 13. The so-called electrode sheet located at the outermost layer of the electrode assembly 20 can be the negative electrode sheet 21 or the positive electrode sheet 22.
[0059] In some embodiments, the secondary battery 100 includes adhesive members (not shown) disposed between the first housing cover 12 and the electrode assembly 20, and between the second housing cover 13 and the electrode assembly 20, along the direction through the cavity. The adhesive members facilitate securing the first and second housing covers 12 and 13 to the electrode assembly 20, respectively, thereby improving the stability of the electrode assembly 20 within the outer housing 10. Adhesive members include, but are not limited to, glue, tape, and hot melt adhesive.
[0060] Please refer to Figure 5 and Figure 6 One embodiment of the present application provides a method for preparing a secondary battery 100, comprising the following steps: Step 1: Bend two side edges of the plate that are opposite to each other along the first direction X toward a plane perpendicular to the first direction X to form side walls 111 and end walls 112, wherein the end walls 112 are connected to both ends of the side walls 111 along the first direction X, and the end walls 112 protrude from at least one surface of the side walls 111 along the thickness direction. Figure 5 shows the morphological changes of the plate after the treatment in step 1, and Figure 5 The two dotted lines in the figure schematically illustrate the bending positions of two side edges of the plate that are arranged opposite to each other along the first direction X.
[0061] Step 2: Bend the plate several times toward a plane perpendicular to the second direction Y, and connect the two ends of the plate along the second direction Y to enclose the plate to form a through cavity, so that the side wall 111 and the end wall 112 form the shell body 11, wherein the second direction Y is perpendicular to the first direction X and the thickness direction of the side wall 111. Figure 6 The figure shows the morphological changes of the plate after the second step.
[0062] Step 3: Place the electrode assembly 20 in the cavity, and securely connect the first and second shell covers 12, 13 to the end walls 112 at both ends of the side wall 111 along the cavity's through-going direction. The shell 11, first and second shell covers 12, 13 together form the outer shell 10 of the secondary battery 100. This facilitates the production of a secondary battery 100 with a higher energy density.
[0063] In some embodiments, the plate is made of metal, which is convenient for bending and shaping.
[0064] In some embodiments, the thickness of the plate is less than 0.04 mm. In this case, the sidewalls 111 and end walls 112 formed by the punching process are prone to cracking, while the sidewalls 111 and end walls 112 formed by the bending process are not prone to cracking.
[0065] In some embodiments, in step 1, two sides of the plate opposite to each other along the first direction X are bent toward a plane perpendicular to the first direction X, so that the end wall 112 protrudes from the same surface of the side wall 111 along the thickness direction.
[0066] In some embodiments, in step one, two side edges of the plate that are opposite to each other along the first direction X are bent toward a plane perpendicular to the first direction X by a folding machine.
[0067] In some embodiments, in step 2, "several times" refers to two or more times. For example, the plate is bent twice toward a plane perpendicular to the second direction Y, and the ends of the plate along the second direction Y are connected to form a through triangular prism-shaped cavity. For another example, the plate is bent three times toward a plane perpendicular to the second direction Y, and the ends of the plate along the second direction Y are connected to form a through quadrangular prism-shaped cavity.
[0068] In some embodiments, in step 2, the plate is bent several times toward a plane perpendicular to the second direction Y and in a direction opposite to the protruding direction of the end wall 112 , so that the end wall 112 protrudes from the side wall 111 in a direction away from the cavity.
[0069] In some embodiments, in step 2, the two ends of the side wall 111 along the second direction Y are welded together. This can reduce the possibility of disconnection of the two ends of the plate along the second direction Y under the action of bending stress, which is beneficial to improving the sealing performance of the housing 10 .
[0070] In some embodiments, in step 1 or step 2, the portion of the end wall 112 protruding from the side wall 111 is squeezed inward from both sides along the thickness direction of the end wall 112. This can reduce the radius of the fillet formed by the side wall 111 and the end wall 112, thereby improving the energy density of the secondary battery 100 and increasing the connection area between the end wall 112 and the first and second housing covers 12 and 13.
[0071] In some embodiments, in step 1 or step 2, a through hole is formed in the plate, the first shell cover 12 or the second shell cover 13, and the electrode 30 is insulated and disposed in the through hole via an insulating member 40. In step 3, the electrode assembly 20 is electrically connected to the electrode 30.
[0072] In some embodiments, in step three, the first shell cover 12 and the second shell cover 13 are respectively welded to the end walls 112 at both ends of the side wall 111 along the cavity through-going direction. This helps to improve the stability of the fixing of the first shell cover 12 and the second shell cover 13 to the end walls 112, thereby helping to reduce the risk of leakage of the secondary battery 100 due to fixing failure.
[0073] See also Figure 7 One embodiment of the present application provides an electric device 1000, comprising the aforementioned secondary battery 100. The secondary battery 100 of the present application has a high energy density, which helps extend the battery life of the electric device 1000. The electric device 1000 includes, but is not limited to, electronic devices such as e-book players, mobile phones, fax machines, copiers, printers, headphones, video recorders, LCD televisions, tape recorders, radios, cameras, tablet computers, and laptop computers.
[0074] In addition, those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. As long as they are within the substantive scope of the present application, appropriate changes and modifications to the above embodiments are within the scope disclosed in the present application.
Claims
1. A secondary battery comprising a housing and an electrode assembly, wherein the electrode assembly is housed in the housing, wherein: The housing is a split structure, including a housing, a first housing cover, and a second housing cover. The housing includes side walls and end walls. The side walls enclose a through cavity, and the end walls are provided at both ends of the side walls along the through-going direction of the cavity. The projections of the side walls and the end walls along the through-going direction of the cavity are both annular. The end walls protrude from the side walls in a direction perpendicular to the through-going direction of the cavity. The first housing cover and the second housing cover are respectively fixedly connected to the end walls at both ends of the side walls along the through-going direction of the cavity. Wherein, the wall thickness of the side wall is D, D≤0.2mm.
2. The secondary battery according to claim 1, wherein The end wall includes a first part connected to the side wall along the through-direction of the cavity and a second part connected to the first part along a direction perpendicular to the through-direction of the cavity and protruding from the side wall. Along the direction perpendicular to the through-direction of the cavity, the width of the second part is W, 0.03mm≤W≤3mm.
3. The secondary battery according to claim 2, wherein 0.05mm≤W<0.3mm.
4. The secondary battery according to claim 1, wherein The end wall includes a first portion connected to the side wall along the through-going direction of the cavity and a second portion connected to the first portion along a direction perpendicular to the through-going direction of the cavity and protruding from the side wall. The wall thickness of the second portion is H, 0.02mm≤H≤0.5mm.
5. The secondary battery according to claim 4, wherein 0.03mm≤H≤0.15mm.
6. The secondary battery according to claim 1, wherein The end wall is formed by bending a plate and is integrally provided with the side wall. The connection between the end wall and the side wall is rounded.
7. The secondary battery according to claim 6, characterized in that The end wall includes a first portion connected to the side wall along the through-going direction of the cavity and a second portion connected to the first portion along a direction perpendicular to the through-going direction of the cavity and protruding from the side wall, wherein the wall thickness of the second portion is smaller than that of the side wall.
8. The secondary battery according to claim 6, wherein The shell body includes a weld mark, and along the through-going direction of the cavity, the weld mark extends from the end wall at one end of the side wall to the end wall at the other end of the side wall.
9. The secondary battery according to claim 1, wherein D≤0.04mm; along the through direction of the cavity, the height of the side wall is L, L≥4mm.
10. The secondary battery according to claim 1, wherein D≥0.02mm.
11. The secondary battery according to any one of claims 1 to 10, characterized in that: The first shell cover and the second shell cover are respectively welded to the end walls at both ends of the side wall.
12. An electrical device, characterized in that: The secondary battery according to any one of claims 1 to 11 is included.
13. A method for preparing a secondary battery, characterized in that: The steps include: Bending two side edges of the plate opposite to each other along a first direction toward a plane perpendicular to the first direction to form side walls and end walls, wherein the end walls are connected to both ends of the side wall along the first direction and protrude from at least one surface of the side wall along the thickness direction; The plate is bent several times toward a plane perpendicular to a second direction, and both ends of the plate along the second direction are connected to form a through cavity enclosed by the plate, so that the side walls and the end walls form a shell body, wherein the second direction is perpendicular to the first direction and the thickness direction of the side walls; The electrode assembly is arranged in the cavity, and the first shell cover and the second shell cover are fixedly connected to the end walls at both ends of the side wall along the cavity penetration direction, wherein the shell body, the first shell cover and the second shell cover form the outer shell of the secondary battery.
14. The method for preparing a secondary battery according to claim 13, wherein: include: Two ends of the side wall along the second direction are connected by welding.
15. The method for preparing a secondary battery according to claim 13, wherein: include: The portion of the end wall protruding from the side wall is squeezed inward from both sides along the wall thickness direction of the end wall.
16. The method for preparing a secondary battery according to claim 13, wherein: include: The thickness of the plate is less than 0.04 mm.
17. The method for preparing a secondary battery according to claim 13, wherein: include: The first shell cover and the second shell cover are respectively welded to the end walls at both ends of the side wall along the through-going direction of the cavity.