Cell, battery, and electric device

Abstract

The present application provides a cell, a battery, and an electric device. The cell comprises an electrode assembly and a casing; the casing is used for accommodating the electrode assembly; the casing comprises a first casing member and a second casing member; a first bonding layer of the first casing member is bonded to a second bonding layer of the second casing member to form a sealing portion; the sealing portion has a first glue overflow area, a sealing area, and a second glue overflow area; the sealing area comprises a first section and a second section; the sealing area is located between the first glue overflow area and the second glue overflow area in the width direction of the sealing portion; the second section is closer to the electrode assembly than the first section; and the average thickness of the second section is less than the average thickness of the first section. In this way, the cross-sectional area of the second section in the width direction of the sealing portion can be smaller, such that water vapor permeating into the casing through the sealing area is less, thereby slowing down the expansion speed of the casing, reducing the possibility of a cell failure due to leakage caused by casing breakage, improving the reliability of a battery, and prolonging the service life of the battery.

Description

Cells, batteries, and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application CN202311444061.2, filed on November 1, 2023, entitled “Battery Cell, Battery and Electrical Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0004] With the rapid development of electronic information technology, various electronic devices are also developing towards intelligence and multi-functionality, and the requirements for battery reliability and service life are becoming increasingly higher. Therefore, how to improve battery reliability and service life has become an urgent problem to be solved in the battery field.

[0005] Summary of the Invention

[0006] The present application provides a battery cell, a battery, and an electrical device, which can effectively improve the reliability and service life of the battery.

[0007] In a first aspect, the present application provides a battery cell comprising an electrode assembly and a packaging bag. The packaging bag is used to accommodate the electrode assembly, and the packaging bag comprises a first shell and a second shell, the first shell comprising a first bonding layer, the second shell comprising a second bonding layer, the first bonding layer and the second bonding layer being combined to form a sealing portion; the sealing portion comprises a first glue overflow area, a sealing area, and a second glue overflow area, and along the width direction of the sealing portion, the sealing area is located between the first glue overflow area and the second glue overflow area. The sealing area comprises a first section and a second section, and along the width direction of the sealing portion, the second section is closer to the electrode assembly than the first section; the average thickness of the second section is less than the average thickness of the first section.

[0008] In the above technical solution, the battery cell includes a packaging bag for accommodating the electrode assembly, which can protect the electrode assembly; the packaging bag includes a first shell and a second shell, and the first bonding layer of the first shell and the second bonding layer of the second shell form a sealing portion, which can seal the space of the packaging bag for accommodating the electrode assembly, reduce the possibility of electrolyte leakage in the packaging bag, and enable the battery cell to work normally; the sealing portion includes a first glue overflow area, a sealing area, and a second glue overflow area. Along the width direction of the sealing portion, the sealing area is located between the first glue overflow area and the second glue overflow area. The sealing area includes a first section and a second section. Along the width direction of the sealing portion, the second section is closer to the electrode assembly than the first section; the average thickness of the second section is less than the average thickness of the first section, which can make the cross-sectional area of ​​the second section in the width direction of the sealing section smaller, so that the amount of water vapor penetrating into the interior of the packaging bag through the sealing area is less, thereby slowing down the expansion speed of the packaging bag, reducing the possibility of the packaging bag rupturing and causing leakage and failure of the battery cell, and improving the reliability and service life of the battery; at the same time, the sealing performance of the sealing area is good, and the first shell and the second shell of the sealing area are not easy to leak due to separation.

[0009] In some of the above embodiments, the average thickness of the first section is H1, the average thickness of the second section is H2, and 13%≤H2 / H1≤80%.

[0010] In the above technical solution, by ensuring that the average thickness H1 of the first section and the average thickness H2 of the second section satisfy 13%≤H2 / H1≤80%, on the one hand, the volume of the first glue overflow area and / or the second glue overflow area will not be too large, and the sealing area is not easily corroded by the electrolyte due to bending and cracking, which may cause other layer structures of the first shell and / or the second shell to be corroded by the electrolyte; on the other hand, the amount of water vapor penetrating into the interior of the packaging bag through the sealing area can be reduced, thereby slowing down the expansion speed of the packaging bag, reducing the possibility of leakage and failure of the battery cell due to rupture of the packaging bag, and improving the reliability and service life of the battery.

[0011] In some of the above embodiments, the average thickness of the first segment is H1, the average thickness of the second segment is H2, 35 μm≤H1≤110 μm, and 10 μm≤H2≤60 μm.

[0012] In the above technical solution, by making the average thickness H1 of the first section satisfy 35μm≤H1≤110μm, on the one hand, the bonding strength between the first shell and the second shell can be made greater, the sealing of the packaging bag can be better, and leakage problems are less likely to occur; on the other hand, the amount of water vapor penetrating into the interior of the packaging bag through the sealing area can be reduced.

[0013] By ensuring that the average thickness H2 of the second section satisfies 10μm≤H2≤60μm, on the one hand, the volume of the first glue overflow area and / or the second glue overflow area will not be too large, and the sealing area is not easily corroded by the electrolyte due to bending and cracking, which may cause other layer structures of the first shell and / or the second shell to be corroded by the electrolyte; on the other hand, the amount of water vapor that penetrates into the interior of the packaging bag through the sealing area can be reduced, thereby slowing down the expansion speed of the packaging bag, reducing the possibility of leakage and failure of the battery cell due to rupture of the packaging bag, and improving the reliability and service life of the battery.

[0014] In some of the above embodiments, the sealing area further includes a first transition section, the first transition section is connected between the first section and the second section, and the thickness of the first transition section gradually increases in a direction away from the electrode assembly.

[0015] In the above technical solution, the sealing area also includes a first transition section, which is connected between the first section and the second section. The thickness of the first transition section gradually increases in the direction away from the electrode assembly, so that a smooth transition is formed between the first section and the second section with different thicknesses, which can facilitate the pressing and forming of the first section and the second section.

[0016] In some of the above embodiments, the sealing area further includes a third section, and along the width direction of the sealing portion, the second section is arranged between the third section and the first section, and the average thickness of the second section is smaller than the average thickness of the third section.

[0017] In the above technical solution, the sealing area also includes a third section. Along the width direction of the sealing portion, the second section is arranged between the third section and the first section. The average thickness of the second section is less than the average thickness of the third section, which can ensure that the volume of the overflow area of ​​the sealing area close to the electrode assembly side will not be too large, thereby reducing the occupation of the internal space of the packaging bag by the overflow area of ​​the sealing area close to the electrode assembly side, which is beneficial to improving the energy density of the battery.

[0018] In some of the above embodiments, the average thickness of the first segment is H1, the average thickness of the second segment is H2, the average thickness of the third segment is H3, 13%≤H2 / H1≤80%, and 13%≤H2 / H3≤80%.

[0019] In the above technical solution, by making the average thickness H1 of the first section and the average thickness H2 of the second section satisfy 13%≤H2 / H1≤80%, and the average thickness H1 of the first section and the average thickness H3 of the third section satisfy 13%≤H2 / H3≤80%, on the one hand, the volume of the first glue overflow area and the second glue overflow area will not be too large, and the sealing area is not prone to bending and cracking, causing other layer structures of the first shell and / or the second shell to be corroded by the electrolyte; on the other hand, the amount of water vapor penetrating into the interior of the packaging bag through the sealing area can be reduced, thereby slowing down the expansion speed of the packaging bag, reducing the possibility of the packaging bag rupturing and causing leakage and failure of the battery cell, and improving the reliability and service life of the battery.

[0020] In some of the above embodiments, the average thickness of the first segment is H1, the average thickness of the second segment is H2, and the average thickness of the third segment is H3, 35 μm≤H1≤110 μm, 10 μm≤H2≤60 μm, and 35 μm≤H3≤110 μm.

[0021] In the above technical solution, by making the average thickness H1 of the first section and the average thickness H3 of the third section satisfy 35μm≤H1≤110μm and 35μm≤H3≤110μm, on the one hand, the bonding strength between the first shell and the second shell can be made greater, the sealing performance of the packaging bag can be better, and leakage problems are less likely to occur; on the other hand, the amount of water vapor penetrating into the interior of the packaging bag through the sealing area can be reduced.

[0022] By ensuring that the average thickness H2 of the second section satisfies 10μm≤H2≤60μm, on the one hand, the volumes of the first glue overflow area and the second glue overflow area will not be too large, and the sealing area will not be easily corroded by the electrolyte due to bending and cracking, thereby reducing the amount of water vapor that penetrates into the packaging bag through the sealing area. This can slow down the expansion rate of the packaging bag, reduce the possibility of leakage and failure of the battery cell due to rupture of the packaging bag, and improve the reliability and service life of the battery.

[0023] In some of the above embodiments, the width of the first section is W1, the width of the second section is W2, the width of the third section is W3, the width of the sealing area is W, 5%≤W1 / W≤50%, 5%≤W2 / W≤50%, 5%≤W3 / W≤50%.

[0024] In the above technical solution, by making the width W1 of the first section, the width W3 of the third section, and the width W of the sealing area satisfy 5%≤W1 / W≤50%, 5%≤W3 / W≤50%, on the one hand, the bonding strength between the first shell and the second shell can be made greater, the sealing performance of the packaging bag is better, and leakage problems are less likely to occur; on the other hand, the amount of water vapor penetrating into the interior of the packaging bag through the sealing area can be reduced.

[0025] By making the width W2 of the second section and the width W of the sealing area satisfy 5%≤W2 / W≤50%, on the one hand, the amount of water vapor penetrating into the interior of the packaging bag through the sealing area can be reduced; on the other hand, the volumes of the first glue overflow area and the second glue overflow area will not be too large, and the sealing area is not easily corroded by the electrolyte in other layer structures of the first shell and / or the second shell due to bending and cracking.

[0026] In some of the above embodiments, the width of the first section is W1, the width of the second section is W2, the width of the third section is W3, and the width of the sealing area is W, satisfying 0.15mm≤W1≤4mm, 0.15mm≤W2≤4mm, 0.15mm≤W3≤4mm, and 3mm≤W≤8mm.

[0027] In the above technical solution, by making the width W1 of the first section and the width W3 of the third section satisfy 0.15mm≤W1≤4mm and 0.15mm≤W3≤4mm, on the one hand, the bonding strength between the first shell and the second shell can be made greater, the sealing of the packaging bag can be better, and leakage problems are less likely to occur; on the other hand, the space occupied by the first and third sections can be made smaller, which is conducive to improving the energy density of the battery.

[0028] By ensuring that the width W2 of the second section satisfies 0.15mm≤W2≤4mm, on the one hand, the amount of water vapor penetrating into the interior of the packaging bag through the sealing area can be reduced; on the other hand, the volumes of the first glue overflow area and the second glue overflow area will not be too large, and the sealing area is not easily corroded by the electrolyte due to bending and cracking, thereby preventing the other layer structures of the first shell and / or the second shell from being corroded by the electrolyte.

[0029] By ensuring that the width W of the sealing area satisfies 3mm≤W≤8mm, on the one hand, the bonding strength between the first shell and the second shell can be increased, the sealing of the packaging bag can be better, and leakage problems are less likely to occur; on the other hand, the space occupied by the sealing area can be smaller, which is conducive to improving the energy density of the battery.

[0030] In some of the above embodiments, the sealing area further includes a second transition section, which is connected between the second section and the third section, and the thickness of the second transition section gradually increases in a direction approaching the electrode assembly.

[0031] In the above technical solution, the sealing area also includes a second transition section, which is connected between the second section and the third section. The thickness of the second transition section gradually increases in the direction approaching the electrode assembly, so that a smooth transition is formed between the second section and the third section with different thicknesses, which can facilitate the pressing and forming of the second section and the third section.

[0032] In some of the above embodiments, the surface of the second segment along its thickness direction is a flat surface or a concave-convex surface.

[0033] In the above technical solution, the surface of the second section along its thickness direction is a plane, which can facilitate the press forming of the second section; the surface of the second section along its thickness direction is a concave-convex surface, which can increase the bonding strength between the first shell and the second shell.

[0034] In a second aspect, the present application provides a battery, characterized in that it includes the battery cell as described above.

[0035] In a third aspect, the present application provides an electrical device comprising a battery as described above, the battery being used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can also be obtained based on these drawings.

[0037] FIG1 is a schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0038] FIG2 is a schematic cross-sectional view of the battery cell along line AA in FIG1 ;

[0039] FIG3 is a schematic structural diagram of a battery cell provided in some other embodiments of the present application;

[0040] FIG4 is a schematic cross-sectional view of the battery cell along line BB in FIG3 ;

[0041] FIG5 is a schematic diagram of a partial structure of a battery cell provided in some embodiments of the present application.

[0042] Icon: 10-battery cell; 100-electrode assembly; 200-packaging bag; 210-first shell; 211-first bonding layer; 212-first metal layer; 213-first connecting layer; 214-first protective layer; 220-second shell; 221-second bonding layer; 222-second metal layer; 223-second connecting layer; 224-second protective layer; 230-sealing part; 231-first glue overflow area; 232-sealing area; 2321-first section; 2322-second section; 2323-first transition section; 2324-third section; 2325-second transition section; 233-second glue overflow area; X-width direction of battery cell; Y-length direction of battery cell; Z-thickness direction of battery cell. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0044] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by technicians 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 terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0045] The terms "first", "second" and the like in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0046] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0047] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0048] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0049] With the development of the new energy industry, the requirements for battery reliability and service life are gradually increasing. At present, battery cells packaged in packaging bags are generally provided with a first shell and a second shell. The first bonding layer of the first shell and the second bonding layer of the second shell form a sealing portion to achieve the packaging of the electrode assembly. However, if the thickness of the sealing area of ​​the sealing portion is too small, the bonding strength between the first shell and the second shell will be poor; if the thickness of the sealing area is too large, the amount of water vapor that penetrates into the interior of the packaging bag through the sealing area will be large, accelerating the expansion speed of the packaging bag, causing the packaging bag to rupture and leak and fail, resulting in low battery reliability and a short service life.

[0050] In order to improve the reliability and service life of the battery, an embodiment of the present application provides a battery cell, including an electrode assembly and a packaging bag, the packaging bag is used to accommodate the electrode assembly, the packaging bag includes a first shell and a second shell, the first shell includes a first bonding layer, the second shell includes a second bonding layer, the first bonding layer and the second bonding layer are combined to form a sealing portion; the sealing portion includes a first glue overflow area, a sealing area and a second glue overflow area, along the width direction of the sealing portion, the sealing area is located between the first glue overflow area and the second glue overflow area; the sealing area includes a first section and a second section, along the width direction of the sealing portion, the second section is closer to the electrode assembly than the first section; the average thickness of the second section is less than the average thickness of the first section.

[0051] In a battery cell of this structure, the battery cell includes a packaging bag for accommodating an electrode assembly, which can protect the electrode assembly; the packaging bag includes a first shell and a second shell, and the first bonding layer of the first shell and the bonding layer of the second shell form a sealing portion, which can seal the space of the packaging bag for accommodating the electrode assembly, reduce the possibility of electrolyte leakage in the packaging bag, and enable the battery cell to work normally; the sealing portion includes a first glue overflow area, a sealing area, and a second glue overflow area. Along the width direction of the sealing portion, the sealing area is located between the first glue overflow area and the second glue overflow area. The sealing area includes a first section and a second section. Along the width direction of the sealing portion, the second section is closer to the electrode assembly than the first section; the average thickness of the second section is less than the average thickness of the first section, which can make the cross-sectional area of ​​the second section in the width direction of the sealing section smaller, so that the amount of water vapor penetrating into the interior of the packaging bag through the sealing area is less, thereby slowing down the expansion speed of the packaging bag, reducing the possibility of the packaging bag rupturing and causing leakage and failure of the battery cell, and improving the reliability and service life of the battery; at the same time, the sealing performance of the sealing area is good, and the first shell and the second shell of the sealing area are not easy to leak due to separation.

[0052] The present invention provides a battery comprising a cell. The battery may be a secondary battery or a primary battery, such as a lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, although this invention is not limited thereto. The battery may be cylindrical, flat, rectangular, or have other shapes, although this invention is not limited thereto.

[0053] An embodiment of the present application provides an electrical device that uses a battery as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, and the like.

[0054] 1 and 2 , FIG1 is a schematic structural diagram of a battery cell provided in some embodiments of the present application; FIG2 is a schematic cross-sectional structural diagram of the battery cell in FIG1 along AA.

[0055] An embodiment of the present application provides a battery cell 10, which includes an electrode assembly 100 and a packaging bag 200. The packaging bag 200 is used to accommodate the electrode assembly 100. The packaging bag 200 includes a first shell 210 and a second shell 220. The first shell 210 includes a first bonding layer 211, and the second shell 220 includes a second bonding layer 221. The first bonding layer 211 and the second bonding layer 221 are combined to form a sealing portion 230; the sealing portion 230 includes a first glue overflow area 231, a sealing area 232, and a second glue overflow area 233. Along the width direction (X and Y) of the sealing portion 230, the sealing area 232 is located between the first glue overflow area 231 and the second glue overflow area 233; the sealing area 232 includes a first section 2321 and a second section 2322. Along the width direction (X and Y) of the sealing portion 230, the second section 2322 is closer to the electrode assembly 100 than the first section 2321; the average thickness of the second section 2322 is less than the average thickness of the first section 2321.

[0056] The thickness of the first section 2321 and the thickness of the second section 2322 both refer to the thickness after the first bonding layer 211 and the second bonding layer 221 are bonded or fused.

[0057] In some embodiments, the average thickness of the first section 2321 can be along the width direction (X and Y) of the sealing portion 230, dividing the first section 2321 into multiple sections, adding the thickness of each section and dividing it by the number of sections to obtain the average thickness of the first section 2321. The average thickness calculation method of other parts is similar. In some embodiments, the first bonding layer 211 and the second bonding layer 221 are combined to form four sealing portions 230, which are respectively located on the four sides of the battery cell 10. Among them, the four sealing portions 230 all meet the requirement that the average thickness of the second section 2322 is less than the average thickness of the first section 2321.

[0058] In other embodiments, only one, two, or three of the four sealing portions 230 may satisfy the requirement that the average thickness of the second section 2322 is less than the average thickness of the first section 2321 .

[0059] In other embodiments, the sealing portion 230 may only partially satisfy the requirement that the average thickness of the second section 2322 is less than the average thickness of the first section 2321 .

[0060] In some embodiments, the electrode assembly 100 is composed of a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive electrode collector. The portion of the positive electrode collector not coated with the positive active material layer serves as the positive electrode tab, allowing electrical energy to be input or output from the positive electrode sheet through the positive electrode tab. Taking a lithium-ion battery as an example, the positive electrode current collector can be made of aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, a ternary material, or lithium manganese oxide. The negative electrode sheet includes a negative electrode current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative electrode collector. The portion of the negative electrode collector not coated with the negative active material layer serves as the negative electrode tab, allowing electrical energy to be input or output from the negative electrode sheet through the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be made of carbon or silicon. The material of the isolation film may be polypropylene (PP) or polyethylene (PE), etc. The electrolyte may include an organic solvent, an electrolyte lithium salt, etc.

[0061] In some embodiments, the electrode assembly 300 may be a laminated structure formed by stacking a negative electrode sheet, a separator, and a positive electrode sheet.

[0062] In other embodiments, the electrode assembly 300 may also be a wound structure formed by winding a negative electrode sheet, a separator, and a positive electrode sheet.

[0063] In some embodiments, the first bonding layer 211 and the second bonding layer 221 can be made of polypropylene (PP) material respectively, which can melt when heated so that the first bonding layer 211 and the second bonding layer 221 are integrated, so that the bonding strength of the first shell 210 and the second shell 220 is greater.

[0064] In some embodiments, the width direction X of the battery cell 10, the length direction Y of the battery cell 10, and the thickness direction Z of the battery cell 10 are perpendicular to each other. The sealing portion 230 is disposed around the periphery or at least three sides of the electrode assembly 100. The width direction of the sealing portion 230 includes the X and Y directions, and the thickness direction of the sealing portion 230 is the thickness direction Z of the battery cell 10.

[0065] In some embodiments, the first and second glue overflow areas 231 and 233 are formed by the material of the sealing area 232 being squeezed out. The smaller the thickness of the sealing area 232 formed by squeezing, the more material overflows, and the larger the volume of the first and second glue overflow areas 231 and 233 formed.

[0066] In some embodiments, the thickness of the first segment 2321 is the dimension of the first segment 2321 in the thickness direction Z of the sealing portion 230 , and the thickness of the second segment 2322 is the dimension of the second segment 2322 in the thickness direction Z of the sealing portion 230 .

[0067] The battery cell 10 includes a packaging bag 200 for housing the electrode assembly 100 and protecting the electrode assembly 100. The packaging bag 200 includes a first shell 210 and a second shell 220. The first bonding layer 211 of the first shell 210 and the second bonding layer of the second shell 220 form a sealing portion 230, which seals the space within the packaging bag 200 for housing the electrode assembly 100, reducing the possibility of electrolyte leakage within the packaging bag 200 and enabling the normal operation of the battery cell 10. The sealing portion 230 includes a first glue overflow area 231, a sealing area 232, and a second glue overflow area 233. Along the width (X and Y) directions of the sealing portion 230, the sealing area 232 is located between the first and second glue overflow areas 231 and 233. The sealing area 232 includes a first section 2321 and a second section 2322. Along the width (X and Y) directions of the sealing portion 230, the second section 2322 is closer to the electrode assembly 100 than the first section 2321. The average thickness of the second section 2322 is smaller than the average thickness of the first section 2321, which can make the cross-sectional area of ​​the second section 2322 in the width direction (X and Y) of the sealing portion 230 smaller, thereby reducing the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232, thereby slowing down the expansion speed of the packaging bag 200, reducing the possibility of the packaging bag 200 rupturing and causing leakage and failure of the battery cell 10, and improving the reliability and service life of the battery; at the same time, the sealing performance of the sealing area is better, and the first shell and the second shell of the sealing area are not easy to leak due to separation.

[0068] In some embodiments, the average thickness of the first segment 2321 is H1, the average thickness of the second segment 2322 is H2, and 13%≤H2 / H1≤80%. For example, H2 / H1 can be 13%, 46%, or 80%.

[0069] To reduce the space occupied by the battery cells, after the electrode assembly 100 is packaged in the packaging bag 200, the sealing portion 230 of the packaging bag 200 can be bent. However, if the thickness of the sealing area 231 is too small, the sealing area 231 may crack during bending. The electrolyte inside the packaging bag 200 may penetrate through the gaps formed by the cracks in the sealing area 231 and penetrate into other layers of the first shell 210 and / or the second shell 220, thereby corroding these other layers and causing damage to the packaging bag 200, leakage, and other problems. By ensuring that the average thickness H1 of the first section 2321 and the average thickness H2 of the second section 2322 satisfy 13%≤H2 / H1≤80%, on the one hand, the volume of the first glue overflow area 231 and / or the second glue overflow area 233 will not be too large, and the sealing area 232 is not easily bent and cracked, causing other layer structures of the first shell 210 and / or the second shell 220 to be corroded by the electrolyte; on the other hand, the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232 can be reduced, thereby slowing down the expansion speed of the packaging bag 200, reducing the possibility of the packaging bag 200 rupturing and causing leakage and failure of the battery cell 10, and improving the reliability and service life of the battery.

[0070] In some embodiments, the average thickness of the first segment 2321 is H1, and the average thickness of the second segment 2322 is H2, where 35 μm ≤ H1 ≤ 110 μm, and 10 μm ≤ H2 ≤ 60 μm. For example, H1 can be 35 μm, 72 μm, or 110 μm, and H2 can be 10 μm, 35 μm, or 60 μm, etc.

[0071] By ensuring that the average thickness H1 of the first section 2321 satisfies 35μm≤H1≤110μm, on the one hand, the bonding strength between the first shell 210 and the second shell 220 can be increased, the sealing of the packaging bag 200 can be improved, and leakage problems are less likely to occur; on the other hand, the amount of water vapor that penetrates into the interior of the packaging bag 200 through the sealing area 232 can be reduced.

[0072] By ensuring that the average thickness H2 of the second section 2322 satisfies 10μm≤H2≤60μm, on the one hand, the volume of the first glue overflow area 231 and / or the second glue overflow area 233 will not be too large, and the sealing area 232 is not easily bent and cracked, causing other layer structures of the first shell 210 and / or the second shell 220 to be corroded by the electrolyte; on the other hand, the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232 can be reduced, thereby slowing down the expansion speed of the packaging bag 200 and reducing the possibility of the packaging bag 200 rupturing and causing leakage and failure of the battery cell 10, thereby improving the reliability and service life of the battery.

[0073] In some embodiments, the width of the first segment 2321 is W1, the width of the second segment 2322 is W2, and the width of the seal area 232 is W. 5% ≤ W1 / W ≤ 50%, and 5% ≤ W2 / W ≤ 50%. For example, W1 / W can be 5%, 25%, or 50%, and W2 / W can be 5%, 30%, or 50%, etc.

[0074] By making the width W1 of the first section 2321 and the width W of the sealing area 232 satisfy 5%≤W1 / W≤50%, on the one hand, the bonding strength between the first shell 210 and the second shell 220 can be increased, the sealing performance of the packaging bag 200 is better, and leakage is less likely to occur; on the other hand, the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232 can be reduced.

[0075] By making the width W2 of the second section 2322 and the width W of the sealing area 232 satisfy 5%≤W2 / W≤50%, on the one hand, the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232 can be reduced; on the other hand, the volumes of the first glue overflow area 231 and the second glue overflow area 233 will not be too large, and the sealing area 232 is not easily corroded by the electrolyte in other layer structures of the first shell 210 and / or the second shell 220 due to bending and cracking.

[0076] In some embodiments, the width of the first section 2321 is W1, the width of the second section 2322 is W2, and the width of the seal area 232 is W, satisfying 0.15 mm ≤ W1 ≤ 4 mm, 0.15 mm ≤ W2 ≤ 4 mm, and 3 mm ≤ W ≤ 8 mm. For example, W1 can be 0.15 mm, 1.8 mm, or 4 mm. W2 can be 0.15 mm, 2.3 mm, or 4 mm. W can be 3 mm, 5 mm, or 8 mm.

[0077] By ensuring that the width W1 of the first section 2321 satisfies 0.15mm≤W1≤4mm, on the one hand, the bonding strength between the first shell 210 and the second shell 220 can be increased, the sealing of the packaging bag 200 can be improved, and leakage problems are less likely to occur; on the other hand, the space occupied by the first section 2321 can be reduced, which is beneficial to improving the energy density of the battery.

[0078] By ensuring that the width W2 of the second section 2322 satisfies 0.15mm≤W2≤4mm, on the one hand, the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232 can be reduced; on the other hand, the volumes of the first glue overflow area 231 and the second glue overflow area 233 will not be too large, and the sealing area 232 is not easily bent or cracked, causing other layer structures of the first shell 210 and / or the second shell 220 to be corroded by the electrolyte.

[0079] By ensuring that the width W of the sealing area 232 satisfies 3mm≤W≤8mm, on the one hand, the bonding strength between the first shell 210 and the second shell 220 can be increased, the sealing performance of the packaging bag 200 can be improved, and leakage problems are less likely to occur; on the other hand, the space occupied by the sealing area 232 can be reduced, which is beneficial to improving the energy density of the battery.

[0080] In some embodiments, the sealing area 232 further includes a first transition section 2323 , which is connected between the first section 2321 and the second section 2322 . The thickness of the first transition section 2323 gradually increases in a direction away from the electrode assembly 100 .

[0081] In some embodiments, the thickness of the first transition section 2323 is the dimension of the first transition section 2323 in the thickness direction Z of the sealing portion 230 .

[0082] The sealing area 232 also includes a first transition section 2323, which is connected between the first section 2321 and the second section 2322. The thickness of the first transition section 2323 gradually increases in the direction away from the electrode assembly 100, so that a smooth transition is formed between the first section 2321 and the second section 2322 with different thicknesses, which can facilitate the pressing and forming of the first section 2321 and the second section 2322.

[0083] 3 and 4 , FIG3 is a schematic structural diagram of battery cells provided in other embodiments of the present application; FIG4 is a schematic cross-sectional structural diagram of the battery cell in FIG3 along line BB.

[0084] In some embodiments, the sealing area 232 further includes a third section 2324 , and along the width direction (X and Y) of the sealing portion 230 , the second section 2322 is arranged between the third section 2324 and the first section 2321 , and the average thickness of the second section 2322 is less than the average thickness of the third section 2324 .

[0085] In some embodiments, the thickness of the third segment 2324 refers to the dimension of the third segment 2324 in the thickness direction Z of the sealing portion 230 .

[0086] Since the thickness of the sealing area 232 is smaller, the volume of the glue overflow area adjacent to the sealing area 232 is larger. The sealing area 232 also includes a third section 2324. Along the width direction (X and Y) of the sealing portion 230, the second section 2322 is arranged between the third section 2324 and the first section 2321, so that the material overflowing from the second section 2322 does not directly form the glue overflow area, and the average thickness of the second section 2322 is less than the average thickness of the third section 2324. The third section 2324 overflows less material than the second section 2322. Therefore, the volume of the glue overflow area (second glue overflow area 233) on the side of the sealing area 232 close to the electrode assembly 100 is not too large, thereby reducing the glue overflow area (second glue overflow area 233) on the side of the sealing area 232 close to the electrode assembly 100 that occupies the internal space of the packaging bag 200, which is beneficial to improving the energy density of the battery.

[0087] In some embodiments, the average thickness of the first segment 2321 is H1, the average thickness of the second segment 2322 is H2, and the average thickness of the third segment 2324 is H3. 13% ≤ H2 / H1 ≤ 80%, and 13% ≤ H2 / H3 ≤ 80%. For example, H2 / H1 can be 13%, 50%, or 80%, and H2 / H3 can be 13%, 55%, or 80%, etc.

[0088] By ensuring that the average thickness H1 of the first section 2321 and the average thickness H2 of the second section 2322 satisfy 13%≤H2 / H1≤80%, and the average thickness H1 of the first section 2321 and the average thickness H3 of the third section 2324 satisfy 13%≤H2 / H3≤80%, on the one hand, the volumes of the first glue overflow area 231 and the second glue overflow area 233 will not be too large, and the sealing area 232 is not easily corroded by the electrolyte due to bending and cracking, and on the other hand, the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232 can be reduced, thereby slowing down the expansion speed of the packaging bag 200 and reducing the possibility of leakage and failure of the battery cell 10 due to rupture of the packaging bag 200, thereby improving the reliability and service life of the battery.

[0089] In some embodiments, the average thickness of the first segment 2321 is H1, the average thickness of the second segment 2322 is H2, and the average thickness of the third segment 2324 is H3. 35 μm ≤ H1 ≤ 110 μm, 10 μm ≤ H2 ≤ 60 μm, and 35 μm ≤ H3 ≤ 110 μm. For example, H1 can be 35 μm, 70 μm, or 110 μm. H2 can be 10 μm, 45 μm, or 60 μm. H3 can be 35 μm, 75 μm, or 110 μm.

[0090] By making the average thickness H1 of the first section 2321 and the average thickness H3 of the third section 2324 satisfy 35μm≤H1≤110μm and 35μm≤H3≤110μm, on the one hand, the bonding strength between the first shell 210 and the second shell 220 can be increased, the sealing performance of the packaging bag 200 is better, and leakage is less likely to occur; on the other hand, the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232 can be reduced.

[0091] By ensuring that the average thickness H2 of the second section 2322 satisfies 10μm≤H2≤60μm, on the one hand, the volumes of the first glue overflow area 231 and the second glue overflow area 233 will not be too large, and the sealing area 232 is not easily corroded by the electrolyte due to bending and cracking, which may cause the other layer structures of the first shell 210 and / or the second shell 220 to be corroded by the electrolyte; on the other hand, the amount of water vapor that penetrates into the interior of the packaging bag 200 through the sealing area 232 can be reduced, thereby slowing down the expansion speed of the packaging bag 200 and reducing the possibility of the packaging bag 200 rupturing and causing leakage and failure of the battery cell 10, thereby improving the reliability and service life of the battery.

[0092] In some embodiments, the width of the first segment 2321 is W1, the width of the second segment 2322 is W2, the width of the third segment 2324 is W3, and the width of the seal area 232 is W. 5% ≤ W1 / W ≤ 50%, 5% ≤ W2 / W ≤ 50%, and 5% ≤ W3 / W ≤ 50%. For example, W1 / W can be 5%, 25%, or 50%. W2 / W can be 5%, 30%, or 50%, and W3 / W can be 5%, 35%, or 50%.

[0093] By making the width W1 of the first section 2321, the width W3 of the third section 2324, and the width W of the sealing area 232 satisfy 5%≤W1 / W≤50%, 5%≤W3 / W≤50%, on the one hand, the bonding strength between the first shell 210 and the second shell 220 can be increased, the sealing performance of the packaging bag 200 is better, and leakage is less likely to occur; on the other hand, the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232 can be reduced.

[0094] By making the width W2 of the second section 2322 and the width W of the sealing area 232 satisfy 5%≤W2 / W≤50%, on the one hand, the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232 can be reduced; on the other hand, the volumes of the first glue overflow area 231 and the second glue overflow area 233 will not be too large, and the sealing area 232 is not easily corroded by the electrolyte in other layer structures of the first shell 210 and / or the second shell 220 due to bending and cracking.

[0095] In some embodiments, the width of the first segment 2321 is W1, the width of the second segment 2322 is W2, the width of the third segment 2324 is W3, and the width of the seal area 232 is W, satisfying 0.15 mm ≤ W1 ≤ 4 mm, 0.15 mm ≤ W2 ≤ 4 mm, 0.15 mm ≤ W3 ≤ 4 mm, and 3 mm ≤ W ≤ 8 mm. For example, W1 can be 0.15 mm, 1.8 mm, or 4 mm. W2 can be 0.15 mm, 2.3 mm, or 4 mm. W3 can be 0.15 mm, 2.8 mm, or 4 mm. W can be 3 mm, 5 mm, or 8 mm.

[0096] By making the width W1 of the first section 2321 and the width W3 of the third section 2324 satisfy 0.15mm≤W1≤4mm and 0.15mm≤W3≤4mm, on the one hand, the bonding strength between the first shell 210 and the second shell 220 can be increased, the sealing of the packaging bag 200 can be better, and leakage problems are less likely to occur; on the other hand, the space occupied by the first section 2321 and the third section 2324 can be reduced, which is beneficial to improving the energy density of the battery.

[0097] By ensuring that the width W2 of the second section 2322 satisfies 0.15mm≤W2≤4mm, on the one hand, the amount of water vapor penetrating into the interior of the packaging bag 200 through the sealing area 232 can be reduced; on the other hand, the volumes of the first glue overflow area 231 and the second glue overflow area 233 will not be too large, and the sealing area 232 is not easily bent or cracked, causing other layer structures of the first shell 210 and / or the second shell 220 to be corroded by the electrolyte.

[0098] By ensuring that the width W of the sealing area 232 satisfies 3mm≤W≤8mm, on the one hand, the bonding strength between the first shell 210 and the second shell 220 can be increased, the sealing performance of the packaging bag 200 can be improved, and leakage problems are less likely to occur; on the other hand, the space occupied by the sealing area 232 can be reduced, which is beneficial to improving the energy density of the battery.

[0099] In some embodiments, the sealing area 232 further includes a second transition section 2325 , which is connected between the second section 2322 and the third section 2324 . The thickness of the second transition section 2325 gradually increases in a direction approaching the electrode assembly 100 .

[0100] In some embodiments, the thickness of the second transition section 2325 is the dimension of the second transition section 2325 in the thickness direction Z of the sealing portion 230 .

[0101] The sealing area 232 also includes a second transition section 2325, which is connected between the second section 2322 and the third section 2324. The thickness of the second transition section 2325 gradually increases in the direction approaching the electrode assembly 100, so that a smooth transition is formed between the second section 2322 and the third section 2324 with different thicknesses, which can facilitate the pressing and forming of the second section 2322 and the third section 2324.

[0102] In some embodiments, the surface of the second segment 2322 along its thickness direction Z is planar.

[0103] The surface of the second section 2322 along its thickness direction Z is a plane, which can be understood in a broad sense, that is, the difference in distance between the surface of the second section 2322 along its thickness direction Z and the vertical plane (XY plane) in the thickness direction of the sealing part 230 is less than a threshold value, which can be understood as the surface of the second section 2322 along its thickness direction Z is a plane.

[0104] By making the surface of the second section 2322 in its thickness direction flat, press-forming of the second section 2322 can be facilitated.

[0105] 1 and 2 , in some embodiments, the first housing 210 further includes a first protective layer, a first metal layer 212, a first connection layer 213, and a first protective layer 214 stacked in sequence, with the first bonding layer 211 disposed on a side of the first metal layer 212 facing away from the first connection layer 213. The second housing 220 further includes a second metal layer 222, a second connection layer 223, and a second protective layer 224 stacked in sequence, with the second bonding layer 221 disposed on a side of the second metal layer 222 facing away from the second connection layer 223.

[0106] In some embodiments, the first metal layer 212 and the second metal layer 222 may be made of aluminum (Al), which has good ductility and facilitates the press forming of the sealing area 232 .

[0107] In some embodiments, the first connecting layer 213 and the second connecting layer 223 can be made of glue, which can better connect the first metal layer 213 and the first protective layer 214, the second metal layer 223 and the second protective layer 224, so that the layered structure of the first shell 210 and the second shell 220 is more stable and less prone to stratification problems.

[0108] In some embodiments, the first protective layer 214 and the second protective layer 224 can be made of polyamide (PA, Nylon), polyethylene terephthalate (PET, polyethylene terephthalate) or a mixture of polyamide and polyethylene terephthalate, and have good wear resistance, chemical resistance and corrosion resistance, and can provide good protection for the first metal layer 212, the first connecting layer 213, the first bonding layer 211, the second metal layer 222, the second connecting layer 223 and the second bonding layer 221.

[0109] See FIG5 , which is a schematic diagram of a partial structure of a battery cell provided in some embodiments of the present application.

[0110] In other embodiments, the surface of the second segment 2322 along the thickness direction Z thereof is a concave-convex surface.

[0111] By making the surface of the second section 2322 along the thickness direction Z thereof into a concave-convex surface, the bonding strength between the first shell 210 and the second shell 220 can be increased.

[0112] See Table 1. Table 1 uses the battery cell 10 embodiment shown in Figures 1 and 2 as an example for experimental description. In Table 1, H1 is the average thickness of the first section 2321, H2 is the average thickness of the second section 2322, the first section width ratio is the ratio of the width W1 of the first section 2321 to the width W of the sealing area 232, the second section width ratio is the ratio of the width W2 of the second section 2322 to the width W of the sealing area 232, and the water vapor permeability ratio is the ratio of the water vapor permeability of each embodiment to the water vapor permeability of Comparative Example 1. The first shell 210 and the second shell 220 use an aluminum-plastic film with a thickness of 153μm (before hot pressing), and the total width W of the sealing area 232 is 4mm.

[0113] Table 1 Water vapor permeability test of battery cells

[0114] The test method for water vapor permeability is:

[0115] (1) Punch a hole on the packaging film with a length of 80 mm, a width of 60 mm, and a depth of 5 mm;

[0116] (2) A packaging film without dents and a packaging film with dents were stacked and the top edge, bottom edge and first side edge of the two packaging films were sealed to form the top seal edge, bottom seal edge and first side seal edge of the packaging bag. The sealing temperature was 190° C., the sealing time was 3 seconds, and the sealing width was 4 mm. The sealing thickness was designed to the corresponding thickness and width of each embodiment and comparative example by using different sealing heads;

[0117] (3) baking the packaging bag at a temperature of 85° C. for 4 hours;

[0118] (4) In an environment with a temperature of less than 28° C. and a relative humidity of less than 2%, inject 5.345 g of dimethyl carbonate (DMC) solution from the second side of the packaging bag, and seal the second side to form a second side seal of the packaging bag. The sealing conditions are the same as the sealing conditions for the top edge, bottom edge, and first side of the packaging film.

[0119] (5) Cutting the excess packaging film along the second side seal of the packaging bag to form the final packaging bag for testing;

[0120] (6) Use a syringe to extract 0.5 g of dimethyl carbonate solution from the packaging bag, and drip 1 to 2 drops of dimethyl carbonate solution into the titration cell of the water vapor detection instrument. Test and record the water content of the dimethyl carbonate solution as a1 (μg). The ratio of the water content to the weight of the dimethyl carbonate solution droplet b1 (g) is c1 = a1 / b1 (μg / g or ppm);

[0121] (7) Place the packaging bags for each test in an environment with a temperature of 60° C. and a relative humidity of 90% and allow to stand for 28 days. Repeat step (6) to test and record the water content of the dimethyl carbonate solution as a2 (μg). The ratio of the water content to the weight of the dimethyl carbonate solution droplet b2 (g) is c2 = a2 / b2 (μg / g or ppm).

[0122] (8) Calculate the water vapor permeability Q = c2-c1.

[0123] In the preparation of the packaging bags used in the tests described above, the difference between the comparative example and the example is that the sealing surface of the sealing head used to seal the packaging film in the comparative example is flat, while the sealing surface of the sealing head used to seal the packaging film in the example is stepped to form multiple sections of varying thicknesses. All other steps remain the same.

[0124] According to Table 1, we can see that:

[0125] (1) Compared with Comparative Example 1, it can be seen from Examples 1 to 4 and 6 to 10 that when H2 / H1 is smaller, the water vapor permeability and its proportion are both smaller; compared with Comparative Example 1, it can be seen from Example 5 that when H2 / H1 is the same, the average thickness of H1 and H2 is smaller, the water vapor permeability and its proportion are both smaller, thereby slowing down the expansion speed of the packaging bag, reducing the possibility of leakage and failure of the battery cell using the packaging bag due to rupture of the packaging bag, and improving the reliability and service life of the battery using the packaging bag.

[0126] (2) By comparing Examples 1 to 4, it can be seen that when the average thickness of the first section remains unchanged, the smaller the average thickness of the second section, the smaller the water vapor permeability, that is, by reducing the average thickness of the second section, the water vapor permeability and its proportion of the battery cell can be further reduced. Although when H2 is less than 10μm (Example 1), the water vapor permeability and its proportion are relatively small, when H2 is less than 10μm, the average thickness of the second section will be smaller, resulting in an excessive amount of glue overflowing from the sealing area, and when the sealing area is subjected to stress, it is easy to cause the first bonding layer and the second bonding layer to be damaged, thereby increasing the risk of corrosion of the first metal layer and the second metal layer; and the adhesion of the first bonding layer and the second bonding layer corresponding to the second section is weak, and the first bonding layer and the second bonding layer are easy to separate.

[0127] (3) Comparing Examples 5 to 10, it can be seen that when the average thickness of the second section remains unchanged, the smaller the average thickness of the first section, the smaller the water vapor permeability, that is, by reducing the average thickness of the first section, the water vapor permeability and its proportion of the battery cell can be further reduced. Although when H1 is less than 35μm (Example 5), the water vapor permeability and its proportion are relatively small, when H1 is less than 35μm, the average thickness of the first section will be smaller, resulting in excessive glue overflow in the sealing area, and when the sealing area is subjected to stress, it is easy to cause the first bonding layer and the second bonding layer to be damaged, thereby increasing the risk of corrosion of the first metal layer and the second metal layer; and the adhesion between the first bonding layer and the second bonding layer corresponding to the first section is weak, and the first bonding layer and the second bonding layer are easy to separate. When H1 is greater than 110μm (Example 10), the water vapor permeability and its proportion are large.

[0128] Refer to Table 2, in which the battery cell 10 embodiment shown in Figures 3 and 4 is used as an example for experimental description. The definitions of H1, H2, the first section width ratio, the second section width ratio, and the water vapor permeability ratio in Table 2 are the same as those in Table 1 and will not be repeated here. H3 is the average thickness of the third section 2324, and the third section width ratio is the ratio of the width W3 of the third section 2324 to the width W of the sealing area 232. The first shell 210 and the second shell 220 use an aluminum-plastic film with a thickness of 153μm (before hot pressing), and the total width W of the sealing area 232 is 4mm. The test method for water vapor permeability is the same as in Table 1 and will not be repeated here.

[0129] According to Table 2, we can see that:

[0130] (1) Compared with Comparative Example 2, Examples 11 to 20 show that the embodiments of the present application have a second section with a smaller thickness, and the water vapor permeability and its proportion are both smaller, thereby slowing down the expansion rate of the packaging bag, reducing the possibility of leakage and failure of the battery cell using the packaging bag due to rupture of the packaging bag, and improving the reliability and service life of the battery using the packaging bag.

[0131] Table 2 Water vapor permeability test of battery cells

[0132] (2) By comparing Examples 11 to 15, it can be seen that when the width ratio of the third section remains unchanged, the larger the width ratio of the second section, the smaller the water vapor permeability and its ratio, that is, by increasing the width ratio of the second section, the water vapor permeability and its ratio of the battery cell can be further reduced. When the width ratio of the second section is less than 5% (Example 11), the water vapor permeability and its ratio are both large, and because the width of the second section is small, the precision requirements for the sealing head are high, the processed sealing head is sharp, which will accelerate wear, and the dimensional consistency of the sealing head is poor. Although the water vapor permeability and its ratio are both small when the width ratio of the second section is greater than 50% (Example 15), when the width ratio of the second section is greater than 50%, the amount of glue overflowing from the sealing area will be too large, and when the sealing area is subjected to stress, it is easy to cause damage to the first bonding layer and the second bonding layer, thereby increasing the risk of corrosion of the first metal layer and the second metal layer.

[0133] (3) By comparing Example 11 with Examples 12 to 14, it can be seen that the width proportion of the second section in Examples 12 to 14 is in the range of 5.0% to 50.0%, and the water vapor permeability is relatively small, while the width proportion of the first section and the width proportion of the second section in Example 11 are outside the range of 5.0% to 50.0%, and the water vapor permeability is relatively large, but it is still better than Comparative Example 2.

[0134] (4) By comparing Examples 16 to 20, it can be seen that when the width ratio of the second section remains unchanged, the smaller the width ratio of the first section, the smaller the water vapor permeability and its ratio, that is, by reducing the width ratio of the first section, the water vapor permeability and its ratio of the battery cell can be further reduced. When the width ratio of the first section is greater than 50% (Example 20), the water vapor permeability and its ratio are both large, and the width of the third section will be smaller, the precision requirements for the sealing head will be higher, the processed and formed sealing head will be sharper, which will accelerate wear, and the dimensional consistency of the sealing head will be poor. Although the water vapor permeability and its ratio are both small when the width ratio of the first section is less than 5% (Example 16), when the width ratio of the first section is less than 5%, the width of the first section will be smaller, the precision requirements for the sealing head will be higher, the processed and formed sealing head will be sharper, which will accelerate wear, and the dimensional consistency of the sealing head will be poor.

[0135] (5) By comparing Example 20 with Examples 17 to 19, it can be seen that the width proportion of the first section in Examples 17 to 19 is in the range of 5.0% to 50.0%, and the water vapor permeability is relatively small, while the width proportion of the first section and the width proportion of the third section in Example 20 are outside the range of 5.0% to 50.0%, and the water vapor permeability is relatively large, but it is still better than Comparative Example 2.

[0136] See Table 3, which uses the battery cell 10 embodiment shown in Figures 3 and 4 as an example for experimental description. The definitions of H1, H2, H3, the first section width ratio, the second section width ratio, the third section width ratio, and the water vapor permeability ratio in Table 3 are the same as those in Table 2 and are not repeated here. The first shell 210 and the second shell 220 use an aluminum-plastic film with a thickness of 153μm (before hot pressing), and the total width W of the sealing area 232 is 4mm. The test method for water vapor permeability is the same as that in Table 1 and is not repeated here.

[0137] Table 3 Water vapor permeability test of battery cells

[0138] According to Table 3, we can see that:

[0139] (1) Compared with Comparative Example 3, Examples 21 to 36 show that H2 / H3 is smaller, and the water vapor permeability and its proportion are smaller; Compared with Comparative Example 3, Examples 21 to 24 and 26 to 26 show that H2 / H1 is smaller, and the water vapor permeability and its proportion are smaller; Compared with Comparative Example 3, Example 25 shows that when H2 / H1 is the same, the average thickness of H1 and H2 is smaller, the water vapor permeability and its proportion are smaller, thereby slowing down the expansion speed of the packaging bag, reducing the possibility of leakage and failure of the battery cell using the packaging bag due to rupture of the packaging bag, and improving the reliability and service life of the battery using the packaging bag.

[0140] (2) By comparing Examples 21 to 24, it can be seen that when the average thickness of the first and third sections remains unchanged, the smaller the average thickness of the second section, the smaller the water vapor permeability, that is, by reducing the average thickness of the second section, the water vapor permeability and its proportion of the battery cell can be further reduced. However, when H2 is less than 10μm (Example 21), the average thickness of the second section will be smaller, resulting in an excessive amount of glue overflowing from the sealing area, and when the sealing area is subjected to stress, it is easy to cause the first bonding layer and the second bonding layer to be damaged, thereby increasing the risk of corrosion of the first metal layer and the second metal layer; and the adhesion between the first bonding layer and the second bonding layer corresponding to the second section is weak, and the first bonding layer and the second bonding layer are easy to separate.

[0141] (3) By comparing Example 21 with Examples 22 to 24, it can be seen that the thickness of the second section in Examples 12 to 14 is in the range of 10 μm to 60 μm, the values ​​of H2 / H1 and H2 / H3 are in the range of 13% to 80%, and the water vapor permeability is small; while the thickness of the second section in Example 21 is outside the range of 10 μm to 60 μm, the values ​​of H2 / H1 and H2 / H3 are outside the range of 13% to 80%, and the water vapor permeability is large, but it is still better than Comparative Example 3.

[0142] (4) By comparing Examples 25 to 30, it can be seen that when the average thickness of the second and third sections remains unchanged, the smaller the average thickness of the first section, the smaller the water vapor permeability, that is, by reducing the average thickness of the first section, the water vapor permeability and its proportion of the battery cell can be further reduced. Although when H1 is less than 35μm (Example 25), the water vapor permeability and its proportion are relatively small, when H1 is less than 35μm, the average thickness of the first section will be smaller, resulting in an excessive amount of glue overflowing from the sealing area, and when the sealing area is subjected to stress, it is easy to cause the first bonding layer and the second bonding layer to be damaged, thereby increasing the risk of corrosion of the first metal layer and the second metal layer; and the adhesion between the first bonding layer and the second bonding layer corresponding to the first section is weak, and the first bonding layer and the second bonding layer are easy to separate. When H1 is greater than 110μm (Example 30), the water vapor permeability and its proportion are both large.

[0143] (5) By comparing Example 30 with Examples 26 to 29, it can be seen that the thickness range of the first section in Examples 26 to 29 is within the range of 35 μm to 110 μm, and the water vapor permeability is relatively small; while the thickness range of the first section in Example 30 is outside the range of 35 μm to 110 μm, and the water vapor permeability is relatively large, but it is still better than Comparative Example 3.

[0144] (6) Comparing Examples 31 to 36, it can be seen that when the average thickness of the first and second sections remains unchanged, the smaller the average thickness of the third section, the smaller the water vapor permeability, that is, by reducing the average thickness of the third section, the water vapor permeability and its proportion of the battery cell can be further reduced. Although when H3 is less than 35μm (Example 31), the water vapor permeability and its proportion are relatively small, when H3 is less than 35μm, the average thickness of the third section will be smaller, resulting in excessive glue overflow in the sealing area, and when the sealing area is subjected to stress, it is easy to cause the first bonding layer and the second bonding layer to be damaged, thereby increasing the risk of corrosion of the first metal layer and the second metal layer; and the adhesion of the first bonding layer and the second bonding layer corresponding to the first section is weak, and the first bonding layer and the second bonding layer are easy to separate. When H3 is greater than 110μm (Example 36), the water vapor permeability and its proportion are large.

[0145] (7) By comparing Example 36 with Examples 32 to 35, it can be seen that the thickness range of the third section in Examples 32 to 35 is within the range of 35 μm to 110 μm, and the water vapor permeability is relatively small; while the thickness range of the third section in Example 36 is outside the range of 35 μm to 110 μm, and the water vapor permeability is relatively large, but it is still better than Comparative Example 3.

[0146] Referring to Table 4, the first section thickness ratio is the ratio of the thickness H1 of the first section 2321 to the thickness of the sealing area in Comparative Example 4, the second section thickness ratio is the ratio of the thickness H2 of the second section 2322 to the thickness of the sealing area in Comparative Example 4, and the third section thickness ratio is the ratio of the thickness H3 of the third section 2323 to the thickness of the sealing area in Comparative Example 4. The definitions of the first section width ratio, the second section width ratio, and the third section width ratio are the same as those in Table 3 above and will not be repeated here. The packaging tension is the maximum tension that pulls the first shell and the second shell of the sealing area apart. The thickness of the sealing area in Comparative Example 4 is 75 μm, and the width W of the sealing area in Comparative Example 4 and Examples 37 to 41 is 4 mm.

[0147] The test method for package tension is:

[0148] (1) Disassemble the battery cell and keep the packaging bag and the sealing part on one side of the packaging bag;

[0149] (2) Referring to FIG. 3 , the packaging bag 200 is cut along the width direction X of the packaging bag 200 on one side thereof to produce a sample strip. The sample strip includes the sealing portion 230 of the packaging bag 200, a portion of the first shell 210, and a portion of the second shell 220. The cutting width of the sample strip (i.e., the dimension of the sample strip along the length direction Y of the packaging bag 200) is 8 mm, and the cutting length of the sample strip (i.e., the dimension of the sample strip along the width direction X of the packaging bag 200) is 20 mm to 50 mm.

[0150] (3) opening the sample strip so that a portion of the first shell 210 and a portion of the second shell 220 in the sample strip extend in opposite directions;

[0151] (4) Connect and tighten the two ends of the opened sample strip to the two chucks of the tensile testing machine, with the distance between the two chucks being 25 mm to 50 mm;

[0152] (5) Move the two chucks in opposite directions to stretch the sample strip at a stretching speed of 175 mm / min, and record the maximum tensile force of the tensile testing machine, which is the sealing tensile force of the packaging bag.

[0153] Table 4 Packaging tensile test of battery cells

[0154] According to Table 4, we can see that:

[0155] (1) Compared with Comparative Example 4, it can be seen that the difference in packaging tension in Examples 37 to 41 is small. In the present application, a second section with a smaller thickness is provided, which can reduce the water vapor permeation of the battery cell and has little effect on the sealing effect of the sealing part.

[0156] (2) By comparing Example 39 and Comparative Example 4, it can be seen that when the thickness of the second section accounts for 47% and the width of the second section accounts for 50.0%, the packaging tension of the battery cell is greater than the packaging tension of the battery cell of Comparative Example 4, which can reduce the water vapor permeability of the battery cell while making the sealing effect of the sealing part better.

[0157] (3) By comparing Example 41 and Comparative Example 4, it can be seen that when the thickness of the second section accounts for 13% and the width of the second section accounts for 35.0%, the packaging tension of the battery cell is greater than the packaging tension of the battery cell of Comparative Example 4, which can reduce the water vapor permeability of the battery cell while making the sealing effect of the sealing part better.

[0158] An embodiment of the present application provides a battery, comprising a battery cell 10 according to any of the above solutions.

[0159] An embodiment of the present application provides an electrical device, comprising a battery according to any of the above solutions, and the battery is used to provide electrical energy.

[0160] The power-consuming device may be any of the aforementioned devices or systems using batteries.

[0161] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0162] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, characterized in that: include: Electrode assembly; A packaging bag for accommodating the electrode assembly, the packaging bag comprising a first shell and a second shell, the first shell comprising a first bonding layer, the second shell comprising a second bonding layer, the first bonding layer and the second bonding layer being combined to form a sealing portion; the sealing portion comprising a first glue overflow area, a sealing area and a second glue overflow area, and along the width direction of the sealing portion, the sealing area is located between the first glue overflow area and the second glue overflow area; The sealing area includes a first section and a second section. Along the width direction of the sealing portion, the second section is closer to the electrode assembly than the first section. The average thickness of the second section is smaller than the average thickness of the first section.

2. The battery cell according to claim 1, characterized in that: The average thickness of the first section is H1, the average thickness of the second section is H2, and 13%≤H2 / H1≤80%.

3. The battery cell according to claim 1, characterized in that: The average thickness of the first section is H1, the average thickness of the second section is H2, 35 μm≤H1≤110 μm, 10 μm≤H2≤60 μm.

4. The battery cell according to claim 1, characterized in that: The sealing area further includes a first transition section, which is connected between the first section and the second section, and a thickness of the first transition section gradually increases in a direction away from the electrode assembly.

5. The battery cell according to claim 1, characterized in that: The sealing area further includes a third section. Along the width direction of the sealing portion, the second section is arranged between the third section and the first section. The average thickness of the second section is smaller than the average thickness of the third section.

6. The battery cell according to claim 5, characterized in that: The average thickness of the first section is H1, the average thickness of the second section is H2, the average thickness of the third section is H3, 13%≤H2 / H1≤80%, 13%≤H2 / H3≤80%.

7. The battery cell according to claim 5, characterized in that: The average thickness of the first section is H1, the average thickness of the second section is H2, and the average thickness of the third section is H3, 35 μm≤H1≤110 μm, 10 μm≤H2≤60 μm, and 35 μm≤H3≤110 μm.

8. The battery cell according to any one of claims 5 to 7, characterized in that: The width of the first section is W1, the width of the second section is W2, the width of the third section is W3, the width of the sealing area is W, 5%≤W1 / W≤50%, 5%≤W2 / W≤50%, 5%≤W3 / W≤50%.

9. The battery cell according to claim 1, characterized in that: The width of the first section is W1, the width of the second section is W2, the width of the sealing area is W, 5%≤W1 / W≤50%, 5%≤W2 / W≤50%.

10. The battery cell according to any one of claims 5 to 7, characterized in that: The width of the first section is W1, the width of the second section is W2, the width of the third section is W3, and the width of the sealing area is W, satisfying 0.15mm≤W1≤4mm, 0.15mm≤W2≤4mm, 0.15mm≤W3≤4mm, and 3mm≤W≤8mm.

11. The battery cell according to claim 1, characterized in that: The width of the first section is W1, the width of the second section is W2, and the width of the sealing area is W, satisfying 0.15mm≤W1≤4mm, 0.15mm≤W2≤4mm, and 3mm≤W≤8mm.

12. The battery cell according to claim 5, characterized in that: The sealing area further includes a second transition section, wherein the second transition section is connected between the second section and the third section, and the thickness of the second transition section gradually increases in a direction approaching the electrode assembly.

13. The battery cell according to claim 1, characterized in that: The surface of the second section along the thickness direction thereof is a flat surface or a concave-convex surface.

14. A battery, characterized in that: Comprising the battery cell as claimed in any one of claims 1 to 13.

15. An electrical device, characterized in that: Comprising a battery as claimed in claim 14, the battery is used to provide electrical energy.

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