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

Battery 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] This application relates to the field of battery technology, and more specifically, to a battery cell, a battery, and an electrical device. Background Technology

[0004] With the rapid development of electronic information technology, various electronic devices are also moving towards intelligence and multifunctionality, placing increasingly higher demands on battery reliability and lifespan. Therefore, improving battery reliability and lifespan has become a pressing issue in the battery industry.

[0005] Summary of the Invention

[0006] This application provides a battery cell, a battery, and an electrical device that can effectively improve the reliability and lifespan of the battery.

[0007] In a first aspect, this application provides a battery cell, including an electrode assembly and a packaging bag. The packaging bag is used to house the electrode assembly and includes a first housing and a second housing. The first housing includes a first bonding layer, and the second housing 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 overflow area, a sealing area, and a second overflow area. Along the width direction of the sealing portion, the sealing area is located between the first overflow area and the second overflow area. The sealing area includes a first segment and a second segment. Along the width direction of the sealing portion, the second segment is closer to the electrode assembly than the first segment. The average thickness of the second segment is less than the average thickness of the first segment.

[0008] In the above technical solution, the battery cell includes a packaging bag for housing the electrode assembly, which protects the electrode assembly. The packaging bag includes a first shell and a second shell. A first bonding layer of the first shell and a second bonding layer of the second shell form a sealing part, which seals the space in which the packaging bag houses the electrode assembly, reducing the possibility of electrolyte leakage inside the packaging bag and enabling the battery cell to work normally. The sealing part includes a first overflow area, a sealing area, and a second overflow area. Along the width direction of the sealing part, the sealing area is located between the first overflow area and the second overflow area. The sealing area includes a first segment and a second segment. Along the width direction of the sealing part, the second segment is closer to the electrode assembly than the first segment. The average thickness of the second segment is less than the average thickness of the first segment, which makes the cross-sectional area of ​​the second segment in the width direction of the sealing part smaller. This results in less moisture penetrating into the packaging bag through the sealing area, thereby slowing down the expansion rate of the packaging bag and reducing the possibility of battery cell leakage failure due to packaging bag rupture, thus improving battery reliability and service life. 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 prone to leakage due to separation.

[0009] 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 13% ≤ H2 / H1 ≤ 80%.

[0010] In the above technical solution, by ensuring that the average thickness H1 of the first segment and the average thickness H2 of the second segment satisfy 13% ≤ H2 / H1 ≤ 80%, on the one hand, the volume of the first and / or second overflow areas is not too large, and the sealing area is less likely to be corroded by electrolyte due to bending and cracking of the other layers of the first and / or second shells; on the other hand, the amount of moisture penetrating into the packaging bag through the sealing area is reduced, thereby slowing down the expansion rate of the packaging bag, reducing the possibility of cell leakage failure due to packaging bag rupture, 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, 35μm≤H1≤110μm, and 10μm≤H2≤60μm.

[0012] In the above technical solution, by ensuring that the average thickness H1 of the first segment satisfies 35μm≤H1≤110μm, on the one hand, the bonding strength between the first shell and the second shell is greater, the sealing performance of the packaging bag is better, and the problem of leakage is less likely to occur; on the other hand, the amount of water vapor that permeates into the packaging bag through the sealing area is less.

[0013] By ensuring that the average thickness H2 of the second segment satisfies 10μm≤H2≤60μm, on the one hand, the volume of the first and / or second adhesive overflow areas is not too large, and the sealing area is less likely to be corroded by electrolyte due to bending and cracking of the other layers of the first and / or second shells; on the other hand, less moisture permeates into the packaging bag through the sealing area, thereby slowing down the expansion rate of the packaging bag, reducing the possibility of cell leakage failure due to packaging bag rupture, 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, which connects the first section and the second section, and the thickness of the first transition section gradually increases in the 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 facilitates 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 segment. Along the width direction of the sealing portion, the second segment is disposed between the third segment and the first segment, and the average thickness of the second segment is less than the average thickness of the third segment.

[0017] In the above technical solution, the sealing area also includes a third section. Along the width direction of the sealing part, the second section is set 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 near the electrode assembly is not too large. This can reduce the space occupied by the overflow area of ​​the sealing area near the electrode assembly on the internal space of the packaging bag, 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, and 13% ≤ H2 / H1 ≤ 80%, 13% ≤ H2 / H3 ≤ 80%.

[0019] In the above technical solution, by ensuring that the average thickness H1 of the first segment and the average thickness H2 of the second segment meet the condition of 13% ≤ H2 / H1 ≤ 80%, and the average thickness H1 of the first segment and the average thickness H3 of the third segment meet the condition of 13% ≤ H2 / H3 ≤ 80%, on the one hand, the volume of the first and second overflow areas is not too large, and the sealing area is not easily corroded by electrolyte due to bending and cracking. On the other hand, the amount of moisture penetrating into the packaging bag through the sealing area is reduced, thereby slowing down the expansion rate of the packaging bag, reducing the possibility of cell leakage failure due to packaging bag rupture, 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, with 35μm≤H1≤110μm, 10μm≤H2≤60μm, and 35μm≤H3≤110μm.

[0021] In the above technical solution, by ensuring that the average thickness H1 of the first segment and the average thickness H3 of the third segment satisfy 35μm≤H1≤110μm and 35μm≤H3≤110μm, on the one hand, the bonding strength between the first shell and the second shell is greater, the sealing performance of the packaging bag is better, and the problem of leakage is less likely to occur; on the other hand, the amount of water vapor that permeates into the packaging bag through the sealing area is less.

[0022] By ensuring that the average thickness H2 of the second segment satisfies 10μm≤H2≤60μm, on the one hand, the volume of the first and second overflow areas is not too large, and the sealing area is less likely to be corroded by electrolyte due to bending and cracking of the first shell and / or other layers of the second shell; on the other hand, less moisture permeates into the packaging bag through the sealing area, thereby slowing down the expansion rate of the packaging bag, reducing the possibility of cell leakage failure due to packaging bag rupture, and improving the reliability and service life of the battery.

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

[0024] In the above technical solution, by ensuring that the width W1 of the first segment, the width W3 of the third segment, and the width W of the sealing area satisfy 5%≤W1 / W≤50% and 5%≤W3 / W≤50%, on the one hand, the bonding strength between the first shell and the second shell is greater, the sealing performance of the packaging bag is better, and it is less likely to cause leakage; on the other hand, the amount of water vapor that penetrates into the packaging bag through the sealing area is less.

[0025] By ensuring that the width W2 of the second segment satisfies 5% ≤ W2 / W ≤ 50%, on the one hand, the amount of moisture penetrating into the packaging bag through the sealing area is reduced; on the other hand, the volume of the first and second overflow areas is not too large, and the sealing area is less likely to be corroded by the electrolyte due to bending and cracking.

[0026] In some of the above embodiments, the width of the first segment is W1, the width of the second segment is W2, the width of the third segment 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 ensuring that the width W1 of the first segment and the width W3 of the third segment 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 is greater, the sealing performance of the packaging bag is better, and leakage is less likely to occur; on the other hand, the space occupied by the first segment and the third segment is smaller, which is beneficial to improving the energy density of the battery.

[0028] By ensuring that the width W2 of the second segment satisfies 0.15mm≤W2≤4mm, on the one hand, the amount of moisture penetrating into the packaging bag through the sealing area is reduced; on the other hand, the volume of the first and second overflow areas is not too large, and the sealing area is less likely to be corroded by the electrolyte due to bending and cracking.

[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 and second shells is greater, the sealing performance of the packaging bag is better, and leakage is less likely to occur; on the other hand, the space occupied by the sealing area is smaller, which is beneficial 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 connects the second section and the third section, and the thickness of the second transition section gradually increases along the direction close to the electrode assembly.

[0031] In the above technical solution, the sealing area also includes a second transition section, which connects the second section and the third section. The thickness of the second transition section gradually increases along the direction close to the electrode assembly, so that a smooth transition is formed between the second section and the third section with different thicknesses, which facilitates 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 plane or a concave-convex surface.

[0033] In the above technical solution, the surface of the second segment along its thickness direction is flat, which facilitates the pressing and forming of the second segment; the surface of the second segment along its thickness direction is concave and convex, which can increase the bonding strength between the first shell and the second shell.

[0034] Secondly, this application provides a battery characterized in that it includes the battery cell as described above.

[0035] Thirdly, this application provides an electrical device including a battery as described above, the battery being used to provide electrical energy. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings.

[0037] Figure 1 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0038] Figure 2 is a schematic cross-sectional view of the battery cell along AA in Figure 1;

[0039] Figure 3 is a schematic diagram of the structure of a battery cell provided in some other embodiments of this application;

[0040] Figure 4 is a schematic cross-sectional view of the battery cell along BB in Figure 3;

[0041] Figure 5 is a schematic diagram of a partial structure of a battery cell provided in some embodiments of this application.

[0042] Icons: 10-Battery cell; 100-Electrode assembly; 200-Packaging bag; 210-First housing; 211-First bonding layer; 212-First metal layer; 213-First connecting layer; 214-First protective layer; 220-Second housing; 221-Second bonding layer; 222-Second metal layer; 223-Second connecting layer; 224-Second protective layer; 230-Sealing part; 231-First overflow area; 232-Sealing area; 2321-First segment; 2322-Second segment; 2323-First transition segment; 2324-Third segment; 2325-Second transition segment; 233-Second overflow area; X-Width direction of battery cell; Y-Length direction of battery cell; Z-Thickness direction of battery cell. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application 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 meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having" and any variations thereof in the specification, claims and foregoing description of the drawings are intended to cover non-exclusive inclusion.

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

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

[0047] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0048] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, 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 lifespan are gradually increasing. Currently, battery cells packaged in bags generally have 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 part to encapsulate the electrode assembly. However, if the thickness of the sealing area 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, a large amount of moisture will penetrate into the packaging bag through the sealing area, accelerating the expansion rate of the packaging bag, leading to packaging bag rupture and leakage failure, resulting in lower battery reliability and shorter lifespan.

[0050] To improve battery reliability and lifespan, this application provides a battery cell including an electrode assembly and a packaging bag. The packaging bag is used to house the electrode assembly and includes a first shell and a second shell. The first shell includes a first bonding layer, and 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 overflow area, a sealing area, and a second overflow area. Along the width direction of the sealing portion, the sealing area is located between the first overflow area and the second overflow area. The sealing area includes a first segment and a second segment. Along the width direction of the sealing portion, the second segment is closer to the electrode assembly than the first segment. The average thickness of the second segment is less than the average thickness of the first segment.

[0051] In this type of battery cell, the cell includes a packaging bag for housing the electrode assembly, which protects the electrode assembly. The packaging bag includes a first shell and a second shell. The first bonding layer of the first shell and the bonding layer of the second shell form a sealing part, which seals the space in the packaging bag for housing the electrode assembly, reducing the possibility of electrolyte leakage and enabling the battery cell to function normally. The sealing part includes a first overflow area, a sealing area, and a second overflow area. Along the width direction of the sealing part, the sealing area is located between the first and second overflow areas. The sealing area includes a first segment and a second segment. Along the width direction of the sealing part, the second segment is closer to the electrode assembly than the first segment. The average thickness of the second segment is less than that of the first segment, which results in a smaller cross-sectional area of ​​the second segment in the width direction of the sealing part. This reduces the amount of moisture that permeates into the packaging bag through the sealing area, thereby slowing down the expansion rate of the packaging bag and reducing the possibility of battery cell leakage due to packaging bag rupture, thus improving battery reliability and lifespan. 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 less likely to separate and cause leakage.

[0052] This application provides a battery including a cell. The battery can be a secondary battery or a primary battery, such as a lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, etc., and this application is not limited in this respect. The battery can be cylindrical, flat, cuboid, or other shapes, and this application is not limited in this respect either.

[0053] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc.

[0054] Referring to Figures 1 and 2, Figure 1 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application; Figure 2 is a schematic cross-sectional view of the battery cell in Figure 1 along AA.

[0055] This application provides a battery cell 10, which includes an electrode assembly 100 and a packaging bag 200. The packaging bag 200 is used to house the electrode assembly 100 and 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 overflow area 231, a sealing area 232, and a second overflow area 233. Along the width direction (X and Y) of the sealing portion 230, the sealing area 232 is located between the first overflow area 231 and the second overflow area 233. The sealing area 232 includes a first segment 2321 and a second segment 2322. Along the width direction (X and Y) of the sealing portion 230, the second segment 2322 is closer to the electrode assembly 100 than the first segment 2321. The average thickness of the second segment 2322 is less than the average thickness of the first segment 2321.

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

[0057] In some embodiments, the average thickness of the first segment 2321 can be obtained by dividing the first segment 2321 into multiple equal segments along the width direction (X and Y) of the sealing portion 230, adding the thicknesses of each segment, and dividing by the number of segments. The average thickness of other portions is calculated similarly. In some embodiments, the first bonding layer 211 and the second bonding layer 221 are combined to form four sealing portions 230, located on the four sides of the battery cell 10. All four sealing portions 230 satisfy the condition that the average thickness of the second segment 2322 is less than the average thickness of the first segment 2321.

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

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

[0060] In some embodiments, the electrode assembly 100 comprises a positive electrode, a negative electrode, and a separator. The battery cell primarily operates by the movement of metal ions between the positive and negative electrode plates. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the portion of the positive current collector without the positive active material layer serves as a positive electrode tab, through which electrical energy is input or output to the positive electrode. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary materials, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the portion of the negative current collector without the negative active material layer serves as a negative electrode tab, through which electrical energy is input or output to the negative electrode. The material of the negative current collector can be copper, and the negative active material can be carbon or silicon, etc. The separator can be made of polypropylene (PP) or polyethylene (PE), etc. The electrolyte can include organic solvents, lithium salts, etc.

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

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

[0063] In some embodiments, the first bonding layer 211 and the second bonding layer 221 may be made of polypropylene (PP) material, which can melt when heated so that the first bonding layer 211 and the second bonding layer 221 are fused together, resulting in a greater bonding strength between the first shell 210 and the second shell 220.

[0064] In some embodiments, the width direction X, length direction Y, and thickness direction Z of the battery cell 10 are perpendicular to each other. The sealing portion 230 is disposed around the circumference or at least three sides of the electrode assembly 100, the width direction of the sealing portion 230 includes both 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 overflow area 231 and the second overflow area 233 are formed by the material of the sealing area 232 being squeezed out. The smaller the thickness of the sealing area 232 being squeezed out, the more material overflows, and the larger the volume of the first overflow area 231 and the second overflow area 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, which provides protection for the electrode assembly 100. The packaging bag 200 includes a first housing 210 and a second housing 220. A first bonding layer 211 of the first housing 210 and a second bonding layer of the second housing 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 and enabling the battery cell 10 to function normally. The sealing portion 230 includes a first overflow area 231, a sealing area 232, and a second overflow area 233. Along the width direction (X and Y) of the sealing portion 230, the sealing area 232 is located between the first overflow area 231 and the second overflow area 233. The sealing area 232 includes a first segment 2321 and a second segment 2322. Along the width direction (X and Y) of the sealing portion 230, the second segment 2322 is closer to the electrode assembly 100 than the first segment 2321. The average thickness of the second segment 2322 is less than that of the first segment 2321, which makes the cross-sectional area of ​​the second segment 2322 in the width direction (X and Y) of the sealing part 230 smaller. This results in less moisture penetrating into the packaging bag 200 through the sealing area 232, thereby slowing down the expansion rate of the packaging bag 200 and reducing the possibility of leakage failure of the battery cell 10 due to the rupture of the packaging bag 200. This improves 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 less likely 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%, etc.

[0069] To reduce the space occupied by the battery cell, after the electrode assembly 100 is sealed in the packaging bag 200, the sealing part 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 seep through the crack formed by the seal area 231 into other layers of the first shell 210 and / or the second shell 220, thereby corroding the other layers and causing problems such as damage and leakage of the packaging bag 200. By ensuring that the average thickness H1 of the first segment 2321 and the average thickness H2 of the second segment 2322 satisfy 13% ≤ H2 / H1 ≤ 80%, on the one hand, the volume of the first overflow area 231 and / or the second overflow area 233 is not too large, and the sealing area 232 is less likely to be corroded by electrolyte due to bending and cracking of the other layers of the first shell 210 and / or the second shell 220; on the other hand, the amount of moisture penetrating into the packaging bag 200 through the sealing area 232 is reduced, thereby slowing down the expansion rate of the packaging bag 200, reducing the possibility of leakage failure of the battery cell 10 due to rupture of the packaging bag 200, and improving the reliability and service life of the battery.

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

[0071] By ensuring that the average thickness H1 of the first segment 2321 satisfies 35μm≤H1≤110μm, on the one hand, the bonding strength between the first shell 210 and the second shell 220 is greater, the sealing performance of the packaging bag 200 is better, and it is less likely to cause leakage; on the other hand, the amount of water vapor that penetrates into the packaging bag 200 through the sealing area 232 is less.

[0072] By ensuring that the average thickness H2 of the second segment 2322 satisfies 10μm≤H2≤60μm, on the one hand, the volume of the first overflow area 231 and / or the second overflow area 233 is not too large, and the sealing area 232 is less likely to be corroded by electrolyte due to bending and cracking of the other layers of the first shell 210 and / or the second shell 220; on the other hand, the amount of moisture penetrating into the packaging bag 200 through the sealing area 232 is reduced, thereby slowing down the expansion rate of the packaging bag 200, reducing the possibility of leakage failure of the battery cell 10 due to rupture of the packaging bag 200, and 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 sealing area 232 is W, where 5% ≤ W1 / W ≤ 50% and 5% ≤ W2 / W ≤ 50%. For example, W1 / W can be 5%, 25%, or 50%, etc. W2 / W can be 5%, 30%, or 50%, etc.

[0074] By ensuring that the width W1 of the first segment 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 is greater, 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 that penetrates into the packaging bag 200 through the sealing area 232 is less.

[0075] By ensuring that the width W2 of the second segment 232 and the width W of the sealing area 232 satisfy 5% ≤ W2 / W ≤ 50%, on the one hand, the amount of moisture penetrating into the packaging bag 200 through the sealing area 232 is reduced; on the other hand, the volume of the first overflow area 231 and the second overflow area 233 is not too large, and the sealing area 232 is less likely to be corroded by the electrolyte due to bending and cracking.

[0076] 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 sealing area 232 is W, satisfying 0.15mm≤W1≤4mm, 0.15mm≤W2≤4mm, and 3mm≤W≤8mm. For example, W1 can be 0.15mm, 1.8mm, or 4mm, etc. W2 can be 0.15mm, 2.3mm, or 4mm, etc. W can be 3mm, 5mm, or 8mm.

[0077] By ensuring that the width W1 of the first segment 2321 satisfies 0.15mm≤W1≤4mm, on the one hand, the bonding strength between the first shell 210 and the second shell 220 is greater, the sealing performance of the packaging bag 200 is better, and leakage is less likely to occur; on the other hand, the space occupied by the first segment 2321 is smaller, which is beneficial to improving the energy density of the battery.

[0078] By ensuring that the width W2 of the second segment 2322 satisfies 0.15mm≤W2≤4mm, on the one hand, the amount of moisture penetrating into the packaging bag 200 through the sealing area 232 is reduced; on the other hand, the volume of the first overflow area 231 and the second overflow area 233 is not too large, and the sealing area 232 is less likely to be corroded by the electrolyte due to bending and cracking.

[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 is greater, the sealing performance of the packaging bag 200 is better, and leakage is less likely to occur; on the other hand, the space occupied by the sealing area 232 is smaller, 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, and the thickness of the first transition section 2323 gradually increases in the 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 facilitates the pressing and forming of the first section 2321 and the second section 2322.

[0083] Referring to Figures 3 and 4, Figure 3 is a structural schematic diagram of a battery cell provided in some other embodiments of this application; Figure 4 is a cross-sectional structural schematic diagram of the battery cell in Figure 3 along BB.

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

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

[0086] The smaller the thickness of the sealing area 232, the larger the volume of the overflow area adjacent to the sealing area 232. The sealing area 232 also includes a third segment 2324. Along the width direction (X and Y) of the sealing portion 230, the second segment 2322 is disposed between the third segment 2324 and the first segment 2321, so that the material overflowing from the second segment 2322 does not directly form an overflow area. Furthermore, the average thickness of the second segment 2322 is less than the average thickness of the third segment 2324, and the third segment 2324 overflows less material than the second segment 2322. Therefore, the volume of the overflow area (second overflow area 233) of the sealing area 232 near the electrode assembly 100 is not too large, thereby reducing the occupation of the overflow area (second overflow area 233) of the sealing area 232 near the electrode assembly 100 on 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, wherein 13% ≤ H2 / H1 ≤ 80% and 13% ≤ H2 / H3 ≤ 80%. For example, H2 / H1 can be 13%, 50%, or 80%, etc. H2 / H3 can be 13%, 55%, or 80%, etc.

[0088] By ensuring that the average thickness H1 of the first segment 2321 and the average thickness H2 of the second segment 2322 satisfy 13% ≤ H2 / H1 ≤ 80%, and the average thickness H1 of the first segment 2321 and the average thickness H3 of the third segment 2324 satisfy 13% ≤ H2 / H3 ≤ 80%, on the one hand, the volume of the first overflow area 231 and the second overflow area 233 is not too large, and the sealing area 232 is not prone to corrosion of other layers of the first shell 210 and / or the second shell 220 by electrolyte due to bending and cracking; on the other hand, the amount of moisture penetrating into the packaging bag 200 through the sealing area 232 is reduced, thereby slowing down the expansion rate of the packaging bag 200, reducing the possibility of leakage failure of the battery cell 10 due to rupture of the packaging bag 200, and 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, wherein 35μm≤H1≤110μm, 10μm≤H2≤60μm, and 35μm≤H3≤110μm. For example, H1 can be 35μm, 70μm, or 110μm, etc. H2 can be 10μm, 45μm, or 60μm, etc. H3 can be 35μm, 75μm, or 110μm, etc.

[0090] By ensuring that the average thickness H1 of the first segment 2321 and the average thickness H3 of the third segment 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 is greater, 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 that penetrates into the interior of the packaging bag 200 through the sealing area 232 is reduced.

[0091] By ensuring that the average thickness H2 of the second segment 2322 satisfies 10μm≤H2≤60μm, on the one hand, the volume of the first overflow area 231 and the second overflow area 233 is not too large, and the sealing area 232 is less likely to be corroded by electrolyte due to bending and cracking of the other layers of the first shell 210 and / or the second shell 220; on the other hand, the amount of moisture penetrating into the packaging bag 200 through the sealing area 232 is reduced, thereby slowing down the expansion rate of the packaging bag 200, reducing the possibility of leakage failure of the battery cell 10 due to rupture of the packaging bag 200, and 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 sealing area 232 is W, where 5% ≤ W1 / W ≤ 50%, 5% ≤ W2 / W ≤ 50%, and 5% ≤ W3 / W ≤ 50%. For example, W1 / W can be 5%, 25%, or 50%, etc. W2 / W can be 5%, 30%, or 50%, etc. W3 / W can be 5%, 35%, or 50%, etc.

[0093] By ensuring that the width W1 of the first segment 2321, the width W3 of the third segment 2324, and the width W of the sealing area 232 satisfy 5%≤W1 / W≤50% and 5%≤W3 / W≤50%, on the one hand, the bonding strength between the first shell 210 and the second shell 220 is greater, the sealing performance of the packaging bag 200 is better, and leakage is less likely to occur; on the other hand, the amount of moisture that penetrates into the packaging bag 200 through the sealing area 232 is reduced.

[0094] By ensuring that the width W2 of the second segment 232 and the width W of the sealing area 232 satisfy 5% ≤ W2 / W ≤ 50%, on the one hand, the amount of moisture penetrating into the packaging bag 200 through the sealing area 232 is reduced; on the other hand, the volume of the first overflow area 231 and the second overflow area 233 is not too large, and the sealing area 232 is less likely to be corroded by the electrolyte 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 sealing area 232 is W, satisfying 0.15mm≤W1≤4mm, 0.15mm≤W2≤4mm, 0.15mm≤W3≤4mm, and 3mm≤W≤8mm. For example, W1 can be 0.15mm, 1.8mm, or 4mm, etc. W2 can be 0.15mm, 2.3mm, or 4mm, etc. W3 can be 0.15mm, 2.8mm, or 4mm, etc. W can be 3mm, 5mm, or 8mm.

[0096] By ensuring that the width W1 of the first segment 2321 and the width W3 of the third segment 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 is greater, the sealing performance of the packaging bag 200 is better, and leakage is less likely to occur; on the other hand, the space occupied by the first segment 2321 and the third segment 2324 is smaller, which is beneficial to improving the energy density of the battery.

[0097] By ensuring that the width W2 of the second segment 2322 satisfies 0.15mm≤W2≤4mm, on the one hand, the amount of moisture penetrating into the packaging bag 200 through the sealing area 232 is reduced; on the other hand, the volume of the first overflow area 231 and the second overflow area 233 is not too large, and the sealing area 232 is less likely to be corroded by the electrolyte due to bending and cracking.

[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 is greater, the sealing performance of the packaging bag 200 is better, and leakage is less likely to occur; on the other hand, the space occupied by the sealing area 232 is smaller, 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 connects the second section 2322 and the third section 2324, and the thickness of the second transition section 2325 gradually increases in the direction close to 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 connects the second section 2322 and the third section 2324. The thickness of the second transition section 2325 gradually increases along the direction close to 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 facilitates 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 a plane.

[0103] The term "the surface of the second segment 2322 along its thickness direction Z" can be interpreted broadly as meaning that the difference between the surface of the second segment 2322 along its thickness direction Z and the perpendicular plane (XY plane) of the thickness direction of the sealing part 230 is less than a threshold.

[0104] By making the surface of the second segment 2322 plane along its thickness direction, it is easier to press and form the second segment 2322.

[0105] Referring to Figures 1 and 2, in some embodiments, the first housing 210 further includes a first protective layer, a first metal layer 212, a first connecting layer 213, and a first protective layer 214, which are stacked sequentially, with a first bonding layer 211 disposed on the side of the first metal layer 212 facing away from the first connecting layer 213. The second housing 220 further includes a second metal layer 222, a second connecting layer 223, and a second protective layer 224, which are stacked sequentially, with a second bonding layer 221 disposed on the side of the second metal layer 222 facing away from the second connecting 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 pressing and 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 adhesive, 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, making the layered structure of the first housing 210 and the second housing 220 more stable and less prone to delamination.

[0108] In some embodiments, the first protective layer 214 and the second protective layer 224 may be made of polyamide (PA, Nylon), polyethylene terephthalate (PET), or a mixture of polyamide and polyethylene terephthalate, and have good wear resistance, chemical resistance and corrosion resistance, and can play a good protective role 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] Referring to Figure 5, Figure 5 is a schematic diagram of a partial structure of a battery cell provided in some embodiments of this application.

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

[0111] By making the surface of the second segment 2322 along its thickness direction Z uneven, the bonding strength between the first shell 210 and the second shell 220 can be increased.

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

[0113] Table 1. Water vapor permeation test of battery cells

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

[0115] (1) Make a hole in the packaging film. The length of the hole is 80mm, the width is 60mm and the depth is 5mm.

[0116] (2) Stack a piece of un-drilled packaging film and a piece of drilled packaging film and seal the top edge, bottom edge and first side edge of the two packaging films to form the top seal edge, bottom seal edge and first side seal edge of the packaging bag. The sealing temperature is 190℃, the sealing time is 3 seconds and the sealing width is 4mm. The sealing thickness is designed to be the thickness and width corresponding to each embodiment and comparative example by using different sealing heads.

[0117] (3) Bake the packaging bags at 85℃ for 4 hours;

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

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

[0120] (6) Use a syringe to draw 0.5g of dimethyl carbonate solution from the packaging bag, add 1 to 2 drops of dimethyl carbonate solution to the titration cell of the water vapor detector, test and record the water content of the dimethyl carbonate solution as a1 (μg), and the ratio of water content to the weight of dimethyl carbonate solution droplets b1 (g) is c1 = a1 / b1 (μg / g or ppm);

[0121] (7) Place the above-mentioned test packaging bags in an environment with a temperature of 60℃ and a relative humidity of 90% and let them stand for 28 days. Then repeat step (6) to test and record the water content of the dimethyl carbonate solution as a2 (μg). The ratio of water content to the weight of the dimethyl carbonate solution droplets as b2 (g) is c2=a2 / b2 (μg / g or ppm).

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

[0123] In the preparation process of the packaging bags used for the above tests, the difference between the comparative example and the embodiment is that the sealing surface of the sealing head of the packaging film in the comparative example is flat, while the sealing surface of the sealing head of the packaging film in the embodiment is stepped to form multiple segments of different thicknesses. All other steps are the same.

[0124] As can be seen from Table 1:

[0125] (1) Compared with Comparative Example 1, Examples 1 to 4 and 6 to 10 show that when H2 / H1 is smaller, the amount of water vapor permeation and its proportion are smaller; Compared with Comparative Example 1, Example 5 shows that when H2 / H1 is the same, when the average thickness of H1 and H2 is smaller, the amount of water vapor permeation and its proportion are smaller, which can slow down the expansion rate of the packaging bag, reduce the possibility of leakage failure of the battery cell using the packaging bag due to the packaging bag breaking, and improve the reliability and service life of the battery using the packaging bag.

[0126] (2) Comparing Examples 1 to 4, it can be seen that when the average thickness of the first segment remains unchanged, the smaller the average thickness of the second segment, the smaller the water vapor permeation. That is, by reducing the average thickness of the second segment, the water vapor permeation and its proportion in the battery cell can be further reduced. Although the water vapor permeation and its proportion are relatively small when H2 is less than 10 μm (Example 1), when H2 is less than 10 μm, the average thickness of the second segment is smaller, resulting in excessive adhesive overflow in the sealing area. When the sealing area is subjected to stress, the first bonding layer and the second bonding layer are easily damaged, which increases the risk of corrosion of the first metal layer and the second metal layer. Furthermore, the adhesion of the first bonding layer and the second bonding layer to the part of the second segment 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 segment remains unchanged, the smaller the average thickness of the first segment, the smaller the water vapor permeation. That is, by reducing the average thickness of the first segment, the water vapor permeation and its proportion in the battery cell can be further reduced. Although the water vapor permeation and its proportion are relatively small when H1 is less than 35 μm (Example 5), when H1 is less than 35 μm, the average thickness of the first segment is smaller, resulting in excessive adhesive overflow in the sealing area. When the sealing area is subjected to stress, the first bonding layer and the second bonding layer are easily damaged, which increases the risk of corrosion of the first metal layer and the second metal layer. Furthermore, the adhesion between the first bonding layer and the second bonding layer corresponding to the first segment is weak, and the first bonding layer and the second bonding layer are easy to separate. When H1 is greater than 110 μm (Example 10), the water vapor permeation and its proportion are larger.

[0128] Refer to Table 2, which uses the battery cell 10 embodiment shown in Figures 3 and 4 as an example for experimental illustration. The definitions of H1, H2, the first segment width percentage, the second segment width percentage, and the water vapor permeation percentage in Table 2 are the same as in Table 1 and will not be repeated here. H3 is the average thickness of the third segment 2324, and the third segment width percentage is the ratio of the width W3 of the third segment 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 153 μm (before hot pressing), and the total width W of the sealing area 232 is 4 mm. The test method for water vapor permeation is the same as in Table 1 and will not be repeated here.

[0129] As can be seen from Table 2:

[0130] (1) As can be seen from Examples 11 to 20 compared to Comparative Example 2, the embodiments of this application have a second segment with a smaller thickness, and the amount and proportion of water vapor permeation are smaller, which can slow down the expansion rate of the packaging bag, reduce the possibility of leakage failure of the battery cell using the packaging bag due to the packaging bag breaking, and improve the reliability and service life of the battery using the packaging bag.

[0131] Table 2. Water vapor permeation test of battery cells

[0132] (2) Comparing Examples 11 to 15, it can be seen that when the width ratio of the third segment remains unchanged, the larger the width ratio of the second segment, the smaller the water vapor permeation and its ratio. That is, by increasing the width ratio of the second segment, the water vapor permeation and its ratio of the battery cell can be further reduced. When the width ratio of the second segment is less than 5% (Example 11), the water vapor permeation and its ratio are relatively large. Furthermore, due to the smaller width of the second segment, the precision requirements for the sealing head are higher, the processed sealing head is sharper, which will accelerate wear, and the dimensional consistency of the sealing head is poor. Although when the width ratio of the second segment is greater than 50% (Example 15), the water vapor permeation and its ratio are relatively small, but when the width ratio of the second segment is greater than 50%, it will lead to excessive glue overflow in the sealing area. Moreover, 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) Comparing Examples 11 and Examples 12 to 14, it can be seen that the width ratio of the second segment in Examples 12 to 14 is in the range of 5.0% to 50.0%, and the water vapor permeation is relatively small. In contrast, the width ratio of the first segment and the width ratio of the second segment in Example 11 are outside the range of 5.0% to 50.0%, and the water vapor permeation is relatively large, but it is still better than Comparative Example 2.

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

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

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

[0137] Table 3. Water vapor permeation test of battery cells

[0138] As can be seen from Table 3:

[0139] (1) Compared with Comparative Example 3, Examples 21 to 36 show that H2 / H3 is smaller, and the amount and proportion of water vapor permeation are smaller; Compared with Comparative Example 3, Examples 21 to 24 and 26 to 26 show that H2 / H1 is smaller, and the amount and proportion of water vapor permeation 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, and the amount and proportion of water vapor permeation are smaller, which can slow down the expansion rate of the packaging bag, reduce the possibility of leakage failure of the battery cell using the packaging bag due to the rupture of the packaging bag, and improve the reliability and service life of the battery using the packaging bag.

[0140] (2) Comparing Examples 21 to 24, it can be seen that when the average thickness of the first and third segments remains unchanged, the smaller the average thickness of the second segment, the smaller the water vapor permeation. That is, by reducing the average thickness of the second segment, the water vapor permeation and its proportion in the battery cell can be further reduced. However, when H2 is less than 10 μm (Example 21), the average thickness of the second segment will be smaller, resulting in excessive adhesive overflow in the sealing area. When the sealing area is subjected to stress, the first bonding layer and the second bonding layer are prone to damage, which in turn increases the risk of corrosion of the first metal layer and the second metal layer. Furthermore, the adhesion between the first bonding layer and the second bonding layer corresponding to the second segment is weak, and the first bonding layer and the second bonding layer are easy to separate.

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

[0142] (4) Comparing Examples 25 to 30, it can be seen that when the average thickness of the second and third segments remains unchanged, the smaller the average thickness of the first segment, the smaller the water vapor permeation. That is, by reducing the average thickness of the first segment, the water vapor permeation and its proportion in the battery cell can be further reduced. Although the water vapor permeation and its proportion are relatively small when H1 is less than 35 μm (Example 25), when H1 is less than 35 μm, the average thickness of the first segment is smaller, resulting in excessive adhesive overflow in the sealing area. When the sealing area is subjected to stress, the first bonding layer and the second bonding layer are easily damaged, which increases the risk of corrosion of the first metal layer and the second metal layer. Furthermore, the adhesion of the first bonding layer and the second bonding layer to the part corresponding to the first segment is weak, and the first bonding layer and the second bonding layer are easy to separate. When H1 is greater than 110 μm (Example 30), the water vapor permeation and its proportion are larger.

[0143] (5) Comparing Example 30 and Examples 26 to 29, it can be seen that the thickness of the first segment in Examples 26 to 29 is in the range of 35μm to 110μm, and the water vapor permeation is relatively small; while the thickness of the first segment in Example 30 is outside the range of 35μm to 110μm, and the water vapor permeation 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 segments remains unchanged, the smaller the average thickness of the third segment, the smaller the water vapor permeation. That is, by reducing the average thickness of the third segment, the water vapor permeation and its proportion in the battery cell can be further reduced. Although the water vapor permeation and its proportion are relatively small when H3 is less than 35 μm (Example 31), when H3 is less than 35 μm, the average thickness of the third segment is smaller, resulting in excessive adhesive overflow in the sealing area. When the sealing area is subjected to stress, the first bonding layer and the second bonding layer are easily damaged, which increases the risk of corrosion of the first metal layer and the second metal layer. Furthermore, the adhesion of the first bonding layer and the second bonding layer to the part corresponding to the first segment is weak, and the first bonding layer and the second bonding layer are easy to separate. When H3 is greater than 110 μm (Example 36), the water vapor permeation and its proportion are larger.

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

[0146] Referring to Table 4, the thickness percentage of the first segment is the ratio of the thickness H1 of the first segment 2321 to the thickness of the sealing area in Comparative Example 4; the thickness percentage of the second segment is the ratio of the thickness H2 of the second segment 2322 to the thickness of the sealing area in Comparative Example 4; and the thickness percentage of the third segment is the ratio of the thickness H3 of the third segment 2323 to the thickness of the sealing area in Comparative Example 4. The definitions of the width percentages of the first, second, and third segments are the same as those in Table 3 above and will not be repeated here. The sealing pull force is the maximum pull force that separates the first and second shells of the sealing area. 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 the sealing pull force is as follows:

[0148] (1) Disassemble the battery cell, keeping the packaging bag and the seal on one side of the packaging bag;

[0149] (2) Referring to Figure 3, the packaging bag 200 is cut along the width direction X of the packaging bag 200 on one side to make a sample strip. The sample strip includes the sealing part 230 of the packaging bag 200, a part of the first shell 210 and a part 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) Open 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 respectively;

[0151] (4) Connect and lock the two ends of the opened sample strip to the two clamps of the tensile testing machine respectively. The distance between the two clamps is 25mm to 50mm.

[0152] (5) Make the two clamps move in opposite directions to stretch the sample strip. The stretching speed is 175 mm / min. Record the maximum tensile force of the tensile testing machine, which is the sealing tensile force of the packaging bag.

[0153] Table 4. Packaging Pull-Out Test of Battery Cells

[0154] As can be seen from Table 4:

[0155] (1) As can be seen from Examples 37 to 41 compared with Comparative Example 4, the difference in encapsulation tension is small. The second section with a smaller thickness is provided in this application, which can reduce the amount of water vapor permeation of the battery cell and has little impact on the sealing effect of the sealing part.

[0156] (2) Comparing Example 39 and Comparative Example 4, it can be seen that when the thickness of the second segment accounts for 47% and the width of the second segment accounts for 50.0%, the encapsulation pull force of the battery cell is greater than that of the battery cell in Comparative Example 4. This can reduce the amount of water vapor permeation of the battery cell while making the sealing effect of the sealing part better.

[0157] (3) Comparing Example 41 and Comparative Example 4, it can be seen that when the thickness of the second segment accounts for 13% and the width of the second segment accounts for 35.0%, the encapsulation pull force of the battery cell is greater than that of the battery cell in Comparative Example 4. This can reduce the amount of water vapor permeation of the battery cell while making the sealing effect of the sealing part better.

[0158] This application provides a battery comprising a cell 10 according to any of the above embodiments.

[0159] This application provides an electrical device including a battery according to any of the above-described schemes, the battery being used to provide electrical energy.

[0160] The electrical device can be any of the aforementioned battery-powered devices or systems.

[0161] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0162] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

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

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

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

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

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

6. The battery cell according to claim 5, characterized in that, 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, where 13% ≤ H2 / H1 ≤ 80% and 13% ≤ H2 / H3 ≤ 80%.

7. The battery cell according to claim 5, characterized in that, 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, where 35μm≤H1≤110μm, 10μm≤H2≤60μm, and 35μm≤H3≤110μm.

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

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

10. The battery cell according to any one of claims 5-7, characterized in that, The width of the first segment is W1, the width of the second segment is W2, the width of the third segment 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 segment is W1, the width of the second segment 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, which connects the second section and the third section, and the thickness of the second transition section gradually increases along the direction close to the electrode assembly.

13. The battery cell according to claim 1, characterized in that, The surface of the second segment along its thickness direction is either flat or uneven.

14. A battery, characterized in that, Includes the battery cell as described in any one of claims 1 to 13.

15. An electrical appliance, characterized in that, Includes the battery as described in claim 14, the battery being used to provide electrical energy.

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