Battery and electronic device

Abstract

The application provides a battery and an electronic device, which comprises a shell, an electrode assembly and a bonding member. The electrode assembly placed in the shell comprises a first end surface and a second end surface opposite to each other along a first direction and a first side surface between the two; the bonding member comprises a substrate layer, a first adhesive layer and an expansion layer; the substrate layer comprises a first surface and a second surface opposite to each other, and the second surface is farther away from the electrode assembly; the bonding member comprises a first part, a second part and a third part connected in sequence, and the first part and the third part are bonded to the first end surface and the second end surface respectively through the first adhesive layer; the expansion layer is arranged on the second surface of the second part; the shell comprises a first main wall and a second main wall opposite to each other along the first direction and a first side wall between the two; the expansion layer comprises a first surface and a second surface opposite to each other, the first surface is closer to the first side wall, and the first surface comprises a plurality of first recesses recessed in a direction away from the first side wall; and / or the second surface comprises a plurality of second recesses recessed in a direction away from the first side surface.

Description

Technical Field

[0001] This application relates to the field of electrochemical technology, and in particular to a battery and electronic device. Background Technology

[0002] Lithium-ion batteries are widely used in smartphones, wearable devices, drones, and electric vehicles due to their high energy density, long cycle life, and lack of memory effect. With the widespread application of lithium-ion batteries, the market has placed increasingly higher demands on their safety performance, such as drop resistance. During a drop, the electrode components inside the battery casing are prone to relative displacement, causing impact to the casing. In severe cases, this can lead to casing breakage and cracking, resulting in safety risks such as fire and explosion. Therefore, improving the drop safety of lithium-ion batteries has become a pressing technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0003] In view of this, the purpose of this application is to provide a battery and electronic device to improve the drop safety of the battery.

[0004] This application provides a battery, comprising: a housing, an electrode assembly, and an adhesive; the housing includes a first main wall and a second main wall opposite to each other along a first direction, and a first side wall located between the first main wall and the second main wall; the electrode assembly is disposed within the housing, the electrode assembly including a first end face and a second end face opposite to each other along the first direction, and a first side face located between the first end face and the second end face; the adhesive includes a substrate layer, a first adhesive layer, and an expansion layer; the substrate layer includes a first surface and a second surface opposite to each other, the second surface being away from the electrode assembly relative to the first surface; the first adhesive layer is disposed on the first surface; the adhesive includes a first portion, a second portion, and a third portion connected in sequence, the first portion and the third portion being bonded to the first end face and the second end face respectively by the first adhesive layer; the second portion is located between the first side face and the first side wall; the expansion layer is disposed on the second surface of the second portion, the expansion layer including a first surface and a second surface opposite to each other, the first surface being closer to the first side wall relative to the second surface, satisfying that: the first surface includes a plurality of first recesses recessed in a direction away from the first side wall; and / or, the second surface includes a plurality of second recesses recessed in a direction away from the first side face.

[0005] In the battery of this application, by disposing an expansion layer on the second surface of the second portion of the adhesive, while the adhesive fixes the electrode assembly by bonding the first and second end faces of the electrode assembly through the first and third portions respectively, an expansion layer can be disposed between the first side surface of the electrode assembly and the first side wall of the housing. After being inserted into the housing along with the electrode assembly, the expansion of the expansion layer fills the gap between the first side surface of the electrode assembly and the first side wall of the housing, thereby suppressing the movement of the electrode assembly within the housing. Simultaneously, after expansion, the concave portions on the surface of the expansion layer can act as a buffer during battery drops, better absorbing impact kinetic energy and reducing the impact of the electrode assembly on the first side wall of the housing, thereby improving the battery's drop safety.

[0006] In any one or more alternative embodiments, the first surface further includes a plurality of first protrusions that project toward the first sidewall, the first protrusions being located between adjacent first recesses.

[0007] In any one or more alternative embodiments, the second surface further includes a plurality of second protrusions that project toward the first side surface, the second protrusions being located between adjacent second recesses.

[0008] The presence of the first protrusion and / or the second protrusion helps to better support the electrode assembly, suppress the movement of the electrode assembly, and thus reduce the impact of the electrode assembly on the first sidewall of the housing.

[0009] In any one or more alternative embodiments, at least a portion of the first protrusion is in contact with the first sidewall.

[0010] In any one or more alternative embodiments, at least a portion of the second protrusion is in contact with the first side surface.

[0011] In any one or more alternative embodiments, the expansion layer has a wavy structure. This facilitates better support and cushioning for the electrode assembly, suppresses the movement of the electrode assembly, disperses and absorbs impact kinetic energy, thereby reducing the impact of the electrode assembly on the first sidewall of the housing.

[0012] In any one or more alternative embodiments, the gap between the first side surface and the first sidewall is A along the direction opposite to the first side surface and the first sidewall, and the thickness of the expansion layer is a, where 0.1A ≤ a ≤ 0.9A. The thickness of the expansion layer is the maximum distance between the first surface and the second surface of the expansion layer along the direction opposite to the first side surface and the first sidewall. Thus, the expansion layer can better provide support and cushioning for the electrode assembly, suppressing the movement of the electrode assembly and absorbing impact kinetic energy, thereby reducing the impact of the electrode assembly on the first sidewall of the housing.

[0013] In any one or more alternative embodiments, along the second direction, the size of the substrate layer is W, the size of the expansion layer is w, 0.2W≤w≤W, and the second direction is the length direction of the first side.

[0014] In any one or more alternative embodiments, the electrode assembly has a dimension B along the first direction, the expansion layer has a dimension b along the first direction, and 0.4B ≤ b ≤ B.

[0015] By controlling the size w and / or b of the expansion layer within the above range, it is beneficial to increase the area of ​​the expansion layer, so that the expansion layer can better provide support and buffer for the electrode assembly.

[0016] In any one or more alternative embodiments, along the direction opposite to the first side and the first sidewall, the gap dimension between the first side and the first sidewall is A, and the depth of the first recess is s1, where 0.1A≤s1≤0.8A.

[0017] In any one or more alternative embodiments, the depth of the second recess is s2, where 0.1A ≤ s2 ≤ 0.8A.

[0018] By controlling the depth s1 of the first recess and / or the depth s2 of the second recess within the aforementioned range, the electrode assembly can be better supported and buffered, the movement of the electrode assembly can be suppressed and the impact kinetic energy can be absorbed, thereby reducing the impact of the electrode assembly on the first sidewall of the housing.

[0019] In any one or more alternative embodiments, a plurality of the expansion layers are stacked on the second surface of the second portion. This creates gaps between the expansion layers, further providing cushioning for the electrode assembly, absorbing impact kinetic energy, and thereby further reducing the impact of the electrode assembly on the first sidewall of the housing.

[0020] In any one or more alternative embodiments, at least a portion of the first recess of one of the expansion layers faces at least a portion of the second recess of an adjacent expansion layer that is relatively close to the first sidewall. This increases the buffer space, better providing cushioning for the electrode assembly, absorbing impact kinetic energy, reducing the impact of the electrode assembly on the first sidewall of the housing, and improving the battery's drop safety.

[0021] In any one or more alternative embodiments, a first protrusion on the first surface of the expansion layer is in contact with the first sidewall.

[0022] In any one or more alternative embodiments, a second protrusion on the second surface of the expansion layer is in contact with the first side surface.

[0023] In any one or more alternative embodiments, along a third direction, the first side includes opposing first and second sub-sides, and along a second direction, the first side includes opposing third and fourth sub-sides; the length of the first sub-side along the second direction is less than the length of the third sub-side along the third direction.

[0024] In any one or more alternative embodiments, the adhesive includes a first sub-adhesive, the second portion of which is located between the first sub-sidewall and the first sidewall.

[0025] In any one or more alternative embodiments, the adhesive includes a second sub-adhesive, the second portion of which is located between the second sub-sidewall and the first sidewall.

[0026] The first and second sub-sides are the surfaces where the short side is located. The area of ​​this surface is relatively small. When falling along this surface, the impact pressure is greater than that of other surfaces, making it easier to break through the casing. By setting sub-adhesives between the first and / or second sub-sides and the first sidewall of the casing, the impact of the electrode assembly on the short side of the casing can be better reduced, the risk of the casing being broken can be reduced, and the drop safety of the battery can be better improved.

[0027] In any one or more alternative embodiments, the first end face and the second end face are square, rectangular or L-shaped.

[0028] In any one or more optional embodiments, the expansion layer includes at least one of an electrolyte swelling layer or a thermal expansion layer. By setting the expansion layer as an electrolyte swelling layer, the swelling layer can spontaneously expand after the electrolyte is introduced, which is simple and easy to implement. Similarly, by setting the expansion layer as a thermal expansion layer, spontaneous expansion of the expansion layer can also be achieved during subsequent heat treatment processes (such as baking and dehydration processes), which is also simple and easy to implement.

[0029] In any one or more alternative embodiments, the expansion ratio of the expansion layer is 100% to 500%. An expansion ratio of 100% to 500% helps to better fill the gap between the first side and the first sidewall, suppresses the movement of the electrode assembly, and provides better cushioning for the electrode assembly, reducing the impact of the electrode assembly on the first sidewall of the housing.

[0030] In any one or more alternative embodiments, a second adhesive layer is provided between the substrate layer and the expanded layer.

[0031] In any one or more alternative embodiments, a second adhesive layer is provided between the expansion layer and the expansion layer.

[0032] In any one or more alternative embodiments, the material of the electrolyte swelling layer includes acrylic resin.

[0033] In any one or more alternative embodiments, the material of the thermal expansion layer includes thermally expanded foam.

[0034] A second aspect of this application provides an electronic device comprising the battery described in any of the above embodiments. Because the battery described above has good drop safety, the electronic device using the battery has good safety in use. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these accompanying drawings.

[0036] Figure 1 These are perspective views of the batteries in some embodiments of this application;

[0037] Figure 2a This is a top view of the battery in some other embodiments of this application;

[0038] Figure 2b for Figure 2a Enlarged cross-sectional view of section I;

[0039] Figure 3 for Figure 2a A three-dimensional magnified structural diagram of part I in the diagram;

[0040] Figure 4a This is a schematic diagram of the cross-sectional structure of the adhesive before expansion provided in some embodiments of this application;

[0041] Figure 4b A side view of a cross-sectional structural diagram of the adhesive before expansion provided in some embodiments of this application;

[0042] Figure 4c for Figure 4b Top view of the bonded component after expansion;

[0043] Figure 5 This is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application.

[0044] Housing 10; First main wall 11; Second main wall 12; First side wall 13; Electrode assembly 20; First side wall 20a; First sub-side wall 20a1; Second sub-side wall 20a2; Third sub-side wall 20a3; Fourth sub-side wall 20a4; First end face 20b; Second end face 20c; Diaphragm 21; First electrode 22; Second electrode 23; Electrode tab 24; Adhesive 30; First part 30a; Second part 30b; Third part 30c; Sub-adhesive component 30-1; second sub-adhesive component 30-2; substrate layer 31; first adhesive layer 32; second adhesive layer 33; first surface 31a; second surface 31b; expansion layer 34; first surface 341; first recess 3411; depth s1 of the first recess; first protrusion 3412; second surface 342; second recess 3421; depth s2 of the second recess; second protrusion 3422; first direction X; second direction Y; third direction Z. Detailed Implementation

[0045] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in this application are within the scope of protection of this application.

[0046] like Figures 1-4c As shown, the first aspect of this application provides a battery, exemplarily, Figure 1 A 3D view of a rectangular battery is shown. Figure 2a A top view of an irregularly shaped (L-shaped) battery is shown. For ease of understanding, a three-dimensional Cartesian coordinate system is established with the thickness direction of the battery as the first direction X, the width direction of the battery as the second direction Y, and a third direction Z (i.e. the length direction of the battery) perpendicular to the first direction X and the second direction Y. Figure 2b for Figure 2a Enlarged cross-sectional diagram of section I. Figure 3 A schematic diagram showing the positional relationship between the electrode assembly 20, the housing 10, and the adhesive 30 is provided. Figure 4a A schematic cross-sectional view of the adhesive component 30 before expansion is shown. Figure 4b The diagram shows a cross-sectional view of the adhesive 30 before it expands after being bonded to the electrode assembly 20. Figure 4cA top view of the adhesive 30 after expansion is shown in some other embodiments. The battery includes a housing 10, an electrode assembly 20, and an adhesive 30. The housing 10 includes a first main wall 11 and a second main wall 12 opposite each other along a first direction X, and a first side wall 13 located between the first main wall 11 and the second main wall 12. The electrode assembly 20 is disposed within the housing 10 and includes a first end face 20b and a second end face 20c opposite each other along the first direction X, and a first side face 20a located between the first end face 20b and the second end face 20c. The adhesive 30 includes a substrate layer 31, a first adhesive layer 32, and an expansion layer 34. The substrate layer 31 includes a first surface 31a and a second surface 31b opposite to each other, with the second surface 31b being away from the electrode assembly 20 relative to the first surface 31a. The first adhesive layer 32 is disposed on the first surface 31a. The adhesive 30 includes a first portion 30a, a second portion 30b, and a third portion 30c connected in sequence. The first portion 30a and the third portion 30c are respectively bonded to the first end face 20b and the second end face 20c by the first adhesive layer 32. The second portion 30b is located between the first side surface 20a and the first sidewall 13. An expansion layer 34 is disposed on the second surface 31b of the second portion 30b. The expansion layer 34 includes a first surface 341 and a second surface 342 opposite to each other. The first surface 341 is closer to the first sidewall 13 relative to the second surface 342, and satisfies the following conditions: the first surface 341 includes a plurality of first recesses 3411 recessed in a direction away from the first sidewall 13; and / or, the second surface 342 includes a plurality of second recesses 3421 recessed in a direction away from the first side surface 20a. That is, the expansion layer 34 may have a first recess 3411 on the first surface 341, or a second recess 3421 on the second surface 342, or both the first surface 341 and the second surface 342 may have a second recess 3421.

[0047] The adhesive 30 is bonded to the first end face 20b, the second end face 20c, and the first side face 20a located between the first end face 20b and the second end face 20c of the electrode assembly 20, which can increase the fixing effect of the electrode assembly 20 and reduce the risk of the electrode assembly 20 becoming loose. While the adhesive 30 fixes the electrode assembly 20 by bonding the first end face 20b and the second end face 20c of the electrode assembly 20 through the first part 30a and the third part 30c respectively, an expansion layer 34 can be provided between the first side face 20a of the electrode assembly 20 and the first side wall 13 of the housing 10. After the electrode assembly 20 is inserted into the housing, the expansion of the expansion layer 34 fills the gap between the first side face 20a of the electrode assembly 20 and the first side wall 13 of the housing 10, thereby suppressing the movement of the electrode assembly 20 within the housing 10. Meanwhile, after expansion, the concave portion on the surface of the expansion layer 34 can act as a buffer during battery drop, better absorb impact kinetic energy, reduce the impact of the electrode assembly 20 on the first sidewall 13 of the casing 10, thereby improving the battery's drop safety.

[0048] It is understandable that, such as Figure 5 As shown, Figure 5 An electrode assembly 20 in a stacked configuration is shown. The electrode assembly 20 includes a diaphragm 21, a first electrode 22, and a second electrode 23. The first electrode 22 can be a positive or negative electrode, and the second electrode 23 can be a negative or positive electrode. When the first electrode 22 is a positive electrode, the second electrode 23 is a negative electrode. The diaphragm 21 is used to separate the positive and negative electrodes.

[0049] In some embodiments, such as Figure 2a and Figure 2b As shown, the first surface 341 also includes a plurality of first protrusions 3412 that protrude toward the first sidewall 13, and the first protrusions 3412 are located between adjacent first recesses 3411.

[0050] In some embodiments, such as Figure 2a and Figure 2b As shown, the second surface 342 also includes a plurality of second protrusions 3422 that protrude toward the first side surface 20a, and the second protrusions 3422 are located between adjacent second recesses 3421.

[0051] It is understandable that the first protrusion 3412 may be provided only between the first recesses 3411 of the first surface 341, or the second protrusion 3422 may be provided only between the second recesses 3421 of the second surface 342, or the first protrusion 3412 may be provided between the first recesses 3411 of the first surface 341 and the second protrusion 3422 may be provided between the second recesses 3421 of the second surface 342.

[0052] By providing a first protrusion 3412 between the first recesses 3411 and / or a second protrusion 3422 between the second recesses, it is beneficial to provide better support for the electrode assembly 20, suppress the movement of the electrode assembly 20, and thereby reduce the impact of the electrode assembly 20 on the first sidewall 13 of the housing.

[0053] In some embodiments, at least a portion of the first protrusion 3412 is in contact with the first sidewall 13. By having the first protrusion 3412 in contact with the first sidewall 13, movement of the electrode assembly 20 relative to the housing 10 can be suppressed.

[0054] In some embodiments, at least a portion of the second protrusion 3422 is in contact with the first side surface 20a. By having the second protrusion 3422 in contact with the first side surface 20a, movement of the electrode assembly 20 relative to the housing 10 can be suppressed.

[0055] In some embodiments, the expansion layer 34 has a wavy structure. That is, both the first surface 341 and the second surface 342 of the expansion layer 34 are uneven, wavy surfaces. The expansion layer 34 is connected to the first sidewall 13 via a first protrusion 3412 and to the first side surface 20a via a second protrusion 3422, which can suppress the movement of the electrode assembly 20. At the locations of the first recess 3411 and the second recess 3421, there is a certain buffer space between the expansion layer 34 and the first sidewall 13 and the first side surface 20a, which can improve the battery's drop performance. Therefore, the wavy structure of the expansion layer 34 is beneficial for providing better support and buffering for the electrode assembly 20, suppressing the movement of the electrode assembly 20, dispersing and absorbing impact kinetic energy, thereby reducing the impact of the electrode assembly 20 on the first sidewall 13 of the housing 10.

[0056] In some embodiments, such as Figure 2a , Figure 2b and Figure 3 As shown, along the direction opposite to the first side surface 20a and the first sidewall 13, the gap size between the first side surface 20a and the first sidewall 13 is A, and the thickness of the expansion layer 34 is a, where 0.1A ≤ a ≤ 0.9A. The thickness of the expansion layer 34 is the maximum distance between the first surface 341 and the second surface 342 of the expansion layer 34 along the direction opposite to the first side surface 20a and the first sidewall 13. Thus, the expansion layer 34 can better provide support and buffer for the electrode assembly 20, suppress the movement of the electrode assembly 20 and absorb impact kinetic energy, thereby reducing the impact of the electrode assembly 20 on the first sidewall 13 of the housing 10. It should be noted that the thickness of the expansion layer 34 refers to the final thickness of the expansion layer 34 after its own expansion, i.e., the expanded thickness. The thickness of the substrate layer 31 and the first adhesive layer 32 can be adjusted by subtracting the thickness occupied by the expansion layer 34 from the gap size between the first side surface 20a and the first sidewall 13, so that the adhesive 30 can fill the entire gap.

[0057] When the filler 30 has a consistent degree of filling and the expansion layer 34 is made of the same material, the thickness of the expansion layer 34 after expansion is smaller, and therefore the initial thickness before expansion is also smaller. For example, if the thickness of the expansion layer 34 after expansion is equal to 0.1A, then the initial thickness of the expansion layer 34 is also smaller. Since the final gap size filled by the adhesive 30 remains unchanged, the thickness of the substrate layer 31 and the first adhesive layer 32 is larger. That is, the initial thickness of the adhesive 30 in its initial state, i.e., before the expansion layer 34 has expanded, is also larger. Therefore, the difference between the adhesive 30 before expansion and the gap size is smaller. After the adhesive 30 is provided on the electrode assembly 20, the difficulty of inserting it into the housing will increase. Conversely, if the expanded layer 34 has a large thickness after expansion, such as 0.9 Å, then the initial thickness of the expanded layer 34 is also large. Since the final gap size filled by the adhesive 30 remains unchanged, the thickness of the substrate layer 31 and the first adhesive layer 32 is small. That is, the initial thickness of the adhesive 30 in its initial state, i.e., before the expanded layer 34 has expanded, is also small. Therefore, the difference between the adhesive 30 before expansion and the gap size is large. After the adhesive 30 is provided on the electrode assembly 20, the difficulty of inserting the electrode assembly 20 into the housing will be reduced during the housing insertion process.

[0058] In some embodiments, such as Figure 3 As shown, along the second direction Y, the size of the substrate layer 31 is W, and the size of the expansion layer 34 is w, where 0.2W ≤ w ≤ W. The second direction Y is the length direction of the first side surface 20a. This improves the filling effect between the electrode assembly 20 and the housing 10, reducing the probability of relative movement between them. Simultaneously, it facilitates increasing the area of ​​the expansion layer 34, allowing it to better support and buffer the electrode assembly 20.

[0059] In some embodiments, such as Figure 3 As shown, the dimension of the electrode assembly 20 along the first direction X is B, and the dimension of the expansion layer 34 along the first direction X is b, where 0.4B ≤ b ≤ B. This improves the filling effect between the electrode assembly 20 and the housing 10, reducing the probability of relative movement between them. Simultaneously, it facilitates increasing the area of ​​the expansion layer 34, allowing it to better support and buffer the electrode assembly 20.

[0060] In some embodiments, such as Figure 2b and Figure 4c As shown, along the direction opposite to the first side surface 20a and the first side wall 13, the gap size between the first side surface 20a and the first side wall 13 is A, and the depth of the first recess 3411 is s1, 0.1A≤s1≤0.8A.

[0061] In some embodiments, such as Figure 2b and Figure 4cAs shown, the depth of the second recess 3421 is s2, 0.1A≤s2≤0.8A.

[0062] By controlling the depth s1 of the first recess and / or the depth s2 of the second recess within the aforementioned range, the electrode assembly 20 can be better supported and buffered, suppressing the movement of the electrode assembly 20 and absorbing impact kinetic energy, thereby reducing the impact of the electrode assembly 20 on the first sidewall 13 of the housing 10.

[0063] In some embodiments, such as Figure 4b and Figure 4c As shown, a plurality of expansion layers 34 are stacked on the second surface 31b of the second part 30b. In some embodiments, after expansion, the first recesses 3411 between two adjacent expansion layers 34 may not correspond. Therefore, gaps may also be formed between expansion layers 34, thereby providing a buffer space for the electrode assembly 20, better absorbing impact kinetic energy, and further reducing the impact of the electrode assembly 20 on the first sidewall 13 of the housing 10.

[0064] For example, such as Figure 4b and Figure 4c As shown, four expansion layers 34 are provided on the second surface 31b of the second part 30b, which makes the thickness of each expansion layer 34 thinner, thus improving the deformation capacity during the expansion process and promoting the formation of gaps between the expansion layers 34. Through the gaps between the expansion layers 34 and the gaps between the expansion layers 34 and the first sidewall 13, the electrode assembly 20 is further buffered to absorb the impact kinetic energy, thereby further reducing the impact of the electrode assembly 20 on the first sidewall 13 of the housing 10 and improving the drop performance of the battery.

[0065] In some embodiments, such as Figure 4c As shown, at least a portion of the first recess 3411 of an expansion layer 34 is opposite to at least a portion of the second recess 3421 of an adjacent expansion layer 34 that is relatively close to the first sidewall 13. In this way, the buffer space can be increased, providing better cushioning for the electrode assembly 20, absorbing impact kinetic energy, reducing the impact of the electrode assembly 20 on the first sidewall 13 of the housing 10, and improving the drop safety of the battery.

[0066] In some embodiments, such as Figure 4c As shown, a first protrusion 3412 on the first surface 341 of an expansion layer 34 is in contact with the first sidewall 13. By connecting the first protrusion 3412 with the first sidewall 13, movement of the electrode assembly 20 relative to the housing 10 can be suppressed.

[0067] In some embodiments, such as Figure 4cAs shown, the second protrusion 3422 of the second surface 342 of the expansion layer 34 is in contact with the first side surface 20a. By connecting the second protrusion 3422 with the first side surface 20a, the movement of the electrode assembly 20 relative to the housing 10 can be suppressed.

[0068] In some embodiments, such as Figure 2a As shown, along the third direction Z, the first side 20a includes a first sub-side 20a1 and a second sub-side 20a2, and along the second direction Y, the first side 20a includes a third sub-side 20a3 and a fourth sub-side 20a4; the length of the first sub-side 20a1 along the second direction Y is less than the length of the third sub-side 20a3 along the third direction Z.

[0069] In some embodiments, the adhesive 30 includes a first sub-adhesive 30-1, and a second portion 30b of the first sub-adhesive 30-1 is located between the first sub-side surface 20a1 and the first sidewall 13.

[0070] In some embodiments, the adhesive 30 includes a second sub-adhesive 30-2, the second portion 30b of which is located between the second sub-sidewall 20a2 and the first sidewall 13.

[0071] The first sub-side surface 20a1 and the second sub-side surface 20a2 are the surfaces containing the short side. These surfaces have a smaller area, and when dropped along them, the impact pressure is greater than on other surfaces, making it easier to break through the casing. By providing sub-adhesives between the first sub-side surface 20a1 and / or the second sub-side surface 20a2 and the first sidewall 13 of the casing 10, the impact of the electrode assembly 20 on the short side of the casing 10 can be better reduced, lowering the risk of the casing 10 being broken and improving the battery's drop safety. It is understood that the adhesive 30 can simultaneously include a first sub-adhesive 30-1 and a second sub-adhesive 30-2. The second part 30b of the first sub-adhesive 30-1 is located between the first sub-side surface 20a1 and the first sidewall 13, and the second part 30b of the second sub-adhesive 30-2 is located between the second sub-side surface 20a2 and the first sidewall 13. That is, by simultaneously providing expansion layers 34 on both the first sub-side surface 20a1 and the second sub-side surface 20a2 containing the short side, the battery's drop safety is further improved.

[0072] For example, such as Figure 2a As shown, the expansion layer 34 is only provided on the end faces of the electrode assembly 20 where L4 and L6 are located, as... Figure 5 As shown, the expansion layer 34 is only provided on the end face where the tab 24 is provided and on the end face opposite to the tab 24.

[0073] In some embodiments of this application, such as Figure 5 As shown, the first end face 20b and the second end face 20c can be square or rectangular. Figure 5Only the first end face 20b is shown, and the second end face 20c is its opposite side; or, as shown Figure 2a As shown, the first end face 20b and the second end face 20c can be L-shaped. In this embodiment, the battery can be a regular-shaped battery or an irregular-shaped battery, thus making the expansion layer 34 applicable not only to regular-shaped batteries but also to irregular-shaped batteries, expanding its applicability. A regular shape, such as a cuboid, does not mean the battery is strictly a cuboid; chamfering is allowed at certain corners. When the first end face 20b and the second end face 20c are irregular-shaped, for example, they can be L-shaped.

[0074] In some embodiments of this application, such as Figure 4a , Figure 4b and Figure 4c As shown, the expansion layer 34 can be an electrolyte swelling layer or a thermal expansion layer.

[0075] By setting the expansion layer 34 as an electrolyte swelling layer, it can spontaneously expand after the electrolyte is introduced, which is simple and easy to implement. Alternatively, setting the expansion layer 34 as a thermal expansion layer allows for spontaneous expansion during subsequent heat treatment processes (such as baking and dehydration), which is also simple and easy to implement. The electrolyte swelling layer can be made of acrylic resin. The thermal expansion layer can be made of thermally expanding foam, which expands when heated to fill gaps and then does not return to its original shape at room temperature.

[0076] In some embodiments of this application, such as Figure 4a As shown, before the expansion layer 34 expands, a second adhesive layer 33 is provided between the substrate layer 31 and the expansion layer 34, that is, the expansion layer 34 is bonded to the second surface 31b of the substrate layer 31 through the second adhesive layer 33. When multiple expansion layers 34 are provided, as shown... Figure 4b As shown, a second adhesive layer 33 may be further provided between the expansion layers 34. When an electrolyte is injected to expand the expansion layers 34, the second adhesive layer 33 dissolves in the electrolyte, thereby causing the expansion layers 34 to lose adhesion to the substrate layer 31, promoting the curling of the expansion layers 34 during expansion, and ultimately... Figure 4c As shown, a plurality of first recesses 3411, first protrusions 3412, second recesses 3421, and second protrusions 3422 are formed on the surface of the expansion layer 34. When the expansion layer 34 is expanded by heating, the second adhesive layer 33 can lose its adhesion during heating, thereby causing the expansion layer 34 to lose its adhesion to the substrate layer 31, promoting the curling of the expansion layer 34 during expansion, and ultimately achieving the same result as... Figure 4c As shown, a plurality of first recesses 3411, first protrusions 3412, second recesses 3421, and second protrusions 3422 are formed on the surface of the expansion layer 34. In some embodiments of this application, the material of the second adhesive layer 33 may include acrylic pressure-sensitive adhesive.

[0077] In some embodiments of this application, the expansion ratio of the expansion layer 34 is 100% to 500%. The expansion ratio (%) is calculated as follows: (final thickness of expansion layer 34 - initial thickness of expansion layer 34) / initial thickness of expansion layer 34 × 100%. The initial thickness of expansion layer 34 is the thickness before expansion, and the final thickness of expansion layer 34 is the final thickness after expansion. Controlling the expansion ratio of the expansion layer 34 within the above range helps to better fill the gap between the first side surface 20a and the first sidewall 13, suppresses the movement of the electrode assembly 20, and better provides buffering for the electrode assembly 20, reducing the impact of the electrode assembly 20 on the first sidewall 13 of the housing 10.

[0078] A second aspect of this application provides an electronic device comprising the battery described in any of the above embodiments. Because the battery described above has good drop safety, the electronic device using the battery has good safety in use.

[0079] The electronic device referred to in this application is not particularly limited. For example, the electronic device may include, but is not limited to, mobile phones, laptops, tablets, electric vehicles, power tools, and drones.

[0080] The following uses a lithium-ion battery as an example to further illustrate this application.

[0081] Example 1-1: A drop test was conducted on a steel-cased lithium-ion battery with an L-shaped first end face 20b and a second end face 20c. Figure 2aThe battery shown has a lithium-ion battery with lithium cobalt oxide as the positive electrode material and graphite as the negative electrode material. The six sides of the L-shaped electrode assembly 20 have dimensions of L1 = 31 mm, L2 = 20 mm, L3 = 48 mm, L4 = 38 mm, L5 = 79 mm, and L6 = 58 mm, respectively. The gap A between the electrode assembly 20 and the sidewall of the housing 10 is 0.3 mm. The thickness of the electrode assembly 20, i.e., the dimension along the first direction X, is B = 4.2 mm. The substrate layer 31 has a dimension W of 8 mm along the second direction Y. Conventional single-sided SIS tape is applied to the end faces of L1, L2, L3, and L5 to fix the stacked electrode assembly 20. Adhesive 30 is applied to the end faces where L4 and L6 are located, and the second part 30b is provided with an expansion layer 34. The dimension w of the expansion layer 34 along the second direction Y is W, and the dimension b of the expansion layer 34 along the first direction X is B. The substrate layer 31 is made of polyethylene terephthalate resin with a thickness of 12 μm (0.04A); the first adhesive layer is made of electrolyte-resistant SIS adhesive (styrene-isoprene-styrene copolymer) with a thickness of 6 μm (0.02A); the expansion layer 34 is made of acrylic resin with an initial thickness of 0.03 mm (0.1A). The expansion layer 34 and the substrate layer 31 are bonded together by a second adhesive layer 33 of acrylic pressure-sensitive adhesive, which is not resistant to electrolytes and has a thickness of 2 μm.

[0082] Examples 2 to 4: Except for the initial thickness of the expansion layer 34, which varies with the data in Table 1, the rest are the same as in Example 1.

[0083] Examples 5 and 6: Except for the number of layers of the expanded layer 34 and the second adhesive layer 33, which varies with the data in Table 1, the rest are the same as in Example 1.

[0084] Comparative Example 1: Unlike Example 1, the second part 30b of the adhesive 30 on the first side 20a where L4 and L6 are located does not have an expansion layer 34 and a second adhesive layer 33.

[0085] Comparative Example 2: Unlike Example 1, the second adhesive layer was replaced with an electrolyte-resistant SIS adhesive (styrene-isoprene-styrene copolymer), and the initial thickness of the expanded layer 34 was adjusted to 0.27 mm (0.9A).

[0086] Drop test: Take 20 batteries from each group. Under the condition of ambient temperature of 20±5℃, fix the batteries in the fixture and drop them freely from a height of 1.8m. Set the batteries to be dropped in sequence with L4 and L6 facing down. After each side is dropped 3 times, the next side is dropped. After the drop is completed, observe whether the casing is broken or leaking. Record the number of batteries with broken casing and leaking liquid as the failure number.

[0087] The parameters and drop test results of each embodiment and comparative example are shown in Table 1.

[0088] Table 1

[0089]

[0090] A comparison of Examples 1-6, Comparative Example 2, and Comparative Example 1 shows that by providing an expansion layer 34 at the position corresponding to the first side 20a of the adhesive 30, the drop performance of the battery can be improved. A comparison of Examples 1-4 and Comparative Example 2 shows that by forming an uneven structure on the surface of the expansion layer 34, the number of battery drop failures can be further reduced. This is because the uneven structure on the surface of the expansion layer 34 provides support for the electrode assembly 20 while buffering and absorbing the impact kinetic energy of the electrode assembly 20 during a drop, thereby reducing the impact of the electrode assembly 20 on the side wall of the housing 10, reducing the risk of the housing 10 being broken, and thus improving the drop safety of the battery.

[0091] A comparison of Examples 1 and 5-6 shows that when multiple expansion layers 34 are provided, the number of battery drop failures is further reduced. This may be because the first recess 3411 of an expansion layer 34 between adjacent expansion layers can face the second recess of an adjacent expansion layer 34 relatively close to the sidewall of the housing 10, thereby providing better cushioning for the electrode assembly 20, further reducing the risk of the housing 10 being punctured, and improving the battery's drop safety.

[0092] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A battery, characterized in that, include: A housing, the housing including a first main wall and a second main wall opposite to each other along a first direction, and a first side wall located between the first main wall and the second main wall; An electrode assembly is disposed within the housing, the electrode assembly including a first end face and a second end face opposite to each other along the first direction, and a first side face located between the first end face and the second end face; An adhesive comprising a substrate layer, a first adhesive layer, and an expansion layer; the substrate layer comprising a first surface and a second surface opposite to each other, the second surface being away from the electrode assembly relative to the first surface; the first adhesive layer being disposed on the first surface; the adhesive comprising a first portion, a second portion, and a third portion connected in sequence, the first portion and the third portion being bonded to the first end face and the second end face respectively by the first adhesive layer; the second portion being located between the first side surface and the first sidewall; The expansion layer is disposed on the second surface of the second portion. The expansion layer includes a first surface and a second surface opposite to each other. The first surface is closer to the first sidewall than the second surface, satisfying the following conditions: the first surface includes a plurality of first recesses that are recessed in a direction away from the first sidewall; and / or, the second surface includes a plurality of second recesses that are recessed in a direction away from the first sidewall. The second part has a plurality of expansion layers stacked on its second surface, and at least a portion of the first recess of one expansion layer is opposite to at least a portion of the second recess of an adjacent expansion layer that is relatively close to the first sidewall; A second adhesive layer is provided between the substrate layer and the expansion layer, and a second adhesive layer is provided between the expansion layers. The expansion layer includes at least one of an electrolyte swelling layer or a thermal expansion layer. When the expansion layer is an electrolyte swelling layer, the second adhesive layer dissolves in the electrolyte when the expansion layer is expanded by injecting electrolyte. When the expansion layer is a thermal expansion layer, the second adhesive layer loses its stickiness when the expansion layer is expanded by heating.

2. The battery according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The first surface further includes a plurality of first protrusions that protrude toward the first sidewall, the first protrusions being located between adjacent first recesses; (2) The second surface further includes a plurality of second protrusions that protrude toward the first side, the second protrusions being located between adjacent second recesses.

3. The battery according to claim 2, characterized in that, At least one of the following conditions must be met: (1) At least a portion of the first protrusion is in contact with the first sidewall; (2) At least a portion of the second protrusion is in contact with the first side surface; (3) The expansion layer has a wavy structure.

4. The battery according to claim 1, characterized in that, At least one of the following conditions must be met: (1) Along the direction opposite to the first side and the first sidewall, the gap between the first side and the first sidewall is A, the thickness of the expansion layer is a, 0.1A≤a≤0.9A, the thickness of the expansion layer is the maximum distance between the first surface and the second surface of the expansion layer along the direction opposite to the first side and the first sidewall; (2) Along the second direction, the size of the substrate layer is W, the size of the expansion layer is w, 0.2W≤w≤W, and the second direction is the length direction of the first side surface; (3) The dimension of the electrode assembly along the first direction is B, and the dimension of the expansion layer along the first direction is b, 0.4B≤b≤B; (4) Along the direction opposite to the first side and the first sidewall, the gap between the first side and the first sidewall is A, and the depth of the first recess is s1, 0.1A≤s1≤0.8A; (5) Along the direction opposite to the first side and the first sidewall, the gap between the first side and the first sidewall is A, and the depth of the second recess is s2, 0.1A≤s2≤0.8A.

5. The battery according to claim 1, characterized in that, At least one of the following conditions must be met: (2) The first protrusion on the first surface of the expansion layer is in contact with the first sidewall; (3) The second protrusion of the second surface of the expansion layer is connected to the first side surface.

6. The battery according to claim 1, characterized in that, Along a third direction, the first side includes opposing first and second sub-sides; along a second direction, the first side includes opposing third and fourth sub-sides; the length of the first sub-side along the third direction is less than the length of the third sub-side along the second direction, satisfying at least one of the following conditions: (1) The adhesive includes a first sub-adhesive, wherein the second portion of the first sub-adhesive is located between the first sub-side surface and the first sidewall; (2) The adhesive includes a second sub-adhesive, the second portion of which is located between the second sub-sidewall and the first sidewall.

7. The battery according to any one of claims 1-6, characterized in that, At least one of the following conditions must be met: (1) The first end face and the second end face are rectangular or L-shaped; (2) The expansion ratio of the expansion layer is 100%~500%.

8. An electronic device, characterized in that, The electronic device includes the battery according to any one of claims 1-7.

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