Battery monomer and preparation method thereof, battery and power utilization device

Abstract

The invention belongs to the technical field of batteries, and discloses a battery monomer, a preparation method thereof, a battery and a power utilization device. The electrode assembly is arranged in the accommodating cavity of the shell assembly and comprises a first surface, a second surface and a third surface; the first insulating part of the insulating part covers the first surface, and the second insulating part of the insulating part covers the second surface; a base film layer of the binding assembly is bonded to the side, away from the electrode assembly, of the first insulating part through a first bonding layer and bonded to the side, away from the electrode assembly, of the second insulating part through a second bonding layer. The first functional layer of the binding component corresponds to the third surface; the first functional layer comprises a first functional material, the first functional material is of a shell-core structure, the first functional material comprises an inner core and a shell layer located on the surface of the inner core, the glass transition temperature of the shell layer is 70-120 DEG C, the inner core expands in volume when the temperature is 70-130 DEG C, and the volume expansion multiple is 5-60 times. The service life is prolonged.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a battery cell and its preparation method, a battery, and an electrical device. Background Technology

[0002] The two ends of a wound-cell battery in the width direction form bends, also known as the radius (R-angle) of the wound-cell battery. The battery casing is usually a square shell structure, resulting in a large gap between the bends of the wound core and the inner wall of the casing. Large gaps exist at the bends between the positive electrode and the separator, the negative electrode and the separator, and between the positive and negative electrodes. During battery charging and discharging, especially during fast charging, these large gaps lengthen the lithium-ion migration path, increase migration resistance, and consequently exacerbate concentration polarization and electrochemical polarization. This can also lead to severe lithium plating problems and a shorter battery life. Summary of the Invention

[0003] The first objective of this application is to provide a battery cell that solves the technical problems of severe lithium plating and short lifespan.

[0004] The second objective of this application is to provide a method for preparing a battery cell that is easy to operate and can alleviate the lithium plating problem.

[0005] The third objective of this application is to provide a battery that has a long service life.

[0006] The fourth objective of this application is to provide an electrical device with high safety.

[0007] Based on the above concept, the technical solution adopted in this application is: Battery cells, including: Housing assembly, including receiving cavity; An electrode assembly is disposed within the receiving cavity. The electrode assembly includes a first surface, a second surface, and a third surface. The first surface and the second surface are disposed opposite each other in a first direction. The third surface is the surface of the electrode assembly in a second direction and is connected between the first surface and the second surface. The first direction is the thickness direction of the electrode assembly, and the second direction is the length direction of the electrode assembly. An insulating component includes a first insulating portion and a second insulating portion, wherein the first insulating portion covers a first surface and the second insulating portion covers a second surface; A binding assembly includes a base film layer and a first adhesive layer, a second adhesive layer, and a first functional layer, all disposed on the side of the base film layer facing the electrode assembly. The base film layer is bonded to the side of the first insulating portion away from the electrode assembly via the first adhesive layer and to the side of the second insulating portion away from the electrode assembly via the second adhesive layer. The first functional layer is disposed between the first adhesive layer and the second adhesive layer and is disposed corresponding to the third surface. The first functional layer includes a first functional material, which has a core-shell structure and includes a core and a shell layer located on the surface of the core. The glass transition temperature of the shell layer is 70°C-120°C. The core is configured to expand in volume at a temperature range of 70°C-130°C, and the volume expansion factor is 5-60 times.

[0008] In one or more embodiments of this application, the material of the shell layer includes at least one of polystyrene, acrylic resin, polymethyl methacrylate, and polyurethane; And / or, The core material includes at least one of n-hexane, cyclohexane, methanol, ethanol, and isopropanol.

[0009] In one or more embodiments of this application, the restraint component further includes a second functional layer disposed on the side of the first functional layer opposite to the base film layer; The second functional layer includes a second functional material, which includes at least one of polymer foam, aerogel, carbon adsorbent, inorganic adsorbent, and composite adsorbent. Preferably, the second functional material includes polymer foam; Preferably, the second functional material includes polyurethane foam; Preferably, the thickness of the second functional layer is c, wherein 0.2mm≤c≤1mm.

[0010] In one or more embodiments of this application, the end face of the restraint component in the third direction is flush with the end face of the electrode component in the third direction; or, the end face of the restraint component in the third direction extends beyond the end face of the electrode component in the third direction by a first distance a, wherein a≤1mm; Wherein, the third direction is perpendicular to both the first direction and the second direction.

[0011] In one or more embodiments of this application, the thickness of the first functional layer is b, wherein 0.01mm≤b≤5mm; And / or, the thickness of the base film layer is d, wherein 0.01mm≤d≤0.1mm; And / or, the thickness of the first adhesive layer is e, where 10 μm ≤ e ≤ 200 μm; And / or, the thickness of the second adhesive layer is f, wherein 10μm≤f≤200μm; preferably, e=f.

[0012] In one or more embodiments of this application, the restraint assembly further includes a third adhesive layer, through which the first functional layer is bonded to the base film layer.

[0013] A method for preparing a battery cell, used to prepare the aforementioned battery cell, the method comprising the following steps: The first insulating portion of the insulating member covers the first surface of the electrode assembly, and the second insulating portion of the insulating member covers the second surface of the electrode assembly; The base film layer of the binding component is bonded to the side of the first insulating portion away from the electrode component by a first adhesive layer, and to the side of the second insulating portion away from the electrode component by a second adhesive layer, and the first functional layer is located between the base film layer and the third surface of the electrode component. The assembled electrode assembly, the insulating component, and the restraint assembly are placed into the receiving cavity of the outer shell assembly, and the receiving cavity is sealed after one liquid injection. The outer casing assembly is baked to expand the first functional layer of the confinement assembly and fill the gap between the third surface and the base film layer, thereby obtaining a battery cell.

[0014] In one or more embodiments of this application, the temperature during baking of the housing assembly is 80°C-120°C.

[0015] The battery comprises the battery cell described above; or, the battery comprises a battery cell prepared by the method described above for preparing the battery cell.

[0016] The electrical device includes the battery described above; or, the electrical device includes the battery cell described above; or, the electrical device includes the battery cell prepared by the method described above.

[0017] The beneficial effects of this application are: The battery cell uses a binding component to bind the electrode assembly, especially binding the area where the third surface of the electrode assembly is located. This suppresses the increase of gaps in the electrode assembly during use, so that the ion migration paths at various locations of the electrode assembly will not grow during charging and discharging, and the migration resistance will not increase. This reduces the risk of lithium plating, improves the fast charging capability of the battery cell, and extends the service life of the battery cell. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments of this application 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 drawings can be obtained based on the content of the embodiments of this application and these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a single battery cell provided in an embodiment of this application; Figure 2 This is a schematic diagram of another battery cell provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of an electrode assembly provided in an embodiment of this application; Figure 4 This is a schematic diagram of the restraint component provided in an embodiment of this application; Figure 5 This is a schematic diagram of the structure of the first functional layer, the first adhesive layer, and the second adhesive layer provided in the embodiments of this application; Figure 6 This is a side view of a restraint component provided in an embodiment of this application; Figure 7 This is a side view of another restraint component provided in an embodiment of this application; Figure 8 This is a side view of another restraint component provided in an embodiment of this application; Figure 9 This is a side view of another restraint component provided in an embodiment of this application; Figure 10 This is a front view of a battery cell provided in an embodiment of this application; Figure 11 This is a front view of another battery cell provided in the embodiments of this application.

[0020] Explanation of reference numerals in the attached figures: 1. Housing assembly; 11. Receiving cavity; 2. Electrode assembly; 21. First surface; 22. Second surface; 23. Third surface; 3. Insulator; 31. First insulating part; 32. Second insulating part; 4. Binding assembly; 41. Base film layer; 42. First adhesive layer; 43. Second adhesive layer; 44. First functional layer; 441. Core; 442. Shell layer; 45. Second functional layer; 46. Third adhesive layer; X, First direction; Y, Second direction; Z, Third direction. Detailed Implementation

[0021] To make the technical problems solved by this application, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of this application will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining this application and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not all of them.

[0022] It should be understood that the phrase "an embodiment" or "one embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment" or "in one embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this application, unless otherwise expressly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature. In the description of this embodiment, unless otherwise specified, "multiple" specifically refers to two or more.

[0026] In the description of this embodiment, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of description and simplification of operation. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0027] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on the other component or it can be located in between the component.

[0028] The technical solution of this application will be further described below with reference to the accompanying drawings and specific embodiments.

[0029] This embodiment provides a battery cell that can reduce the risk of lithium plating and has high safety and reliability.

[0030] For example, such as Figures 1 to 8 As shown, the battery cell includes a housing assembly 1, an electrode assembly 2, an insulating component 3, and a restraint assembly 4. Figure 1 As shown, the housing assembly 1 includes a receiving cavity 11 for accommodating the electrode assembly 2. An insulating member 3 and a restraining assembly 4 are both located within the housing assembly 1. The insulating member 3 provides insulation between the electrode assembly 2 and the housing assembly 1, and the restraining assembly 4 restrains the bends of the electrode assembly 2.

[0031] In some embodiments, such as Figure 1 and Figure 2 As shown, electrode assembly 2 is disposed within receiving cavity 11, and, as Figure 3 As shown, the electrode assembly 2 includes a first surface 21, a second surface 22, and a third surface 23. The first surface 21 and the second surface 22 are disposed opposite each other in a first direction X, and the third surface 23 is a surface of the electrode assembly 2 in a second direction Y, connecting the first surface 21 and the second surface 22. The first direction X is the thickness direction of the electrode assembly 2, and the second direction Y is the length direction of the electrode assembly 2. In some optional embodiments, the first surface 21 and the second surface 22 are both large surfaces (i.e., surfaces with a larger area) of the electrode assembly 2, and the third surface 23 can be a side surface in the length direction of the electrode assembly 2. In this embodiment, the third surface 23 is the surface corresponding to the bending area of ​​the electrode assembly 2; that is, the third surface 23 can be an arc surface or a curved surface, which is not limited in this embodiment.

[0032] For example, such as Figure 1 and Figure 2 As shown, the insulating member 3 includes a first insulating portion 31 and a second insulating portion 32. The first insulating portion 31 covers the first surface 21, that is, the first insulating portion 31 is located between the inner wall of the housing assembly 1 and the first surface 21, and is used for insulation between the first surface 21 and the housing assembly 1. The second insulating portion 32 covers the second surface 22, that is, the second insulating portion 32 is located between the inner wall of the housing assembly 1 and the second surface 22, and is used for insulation between the second surface 22 and the housing assembly 1.

[0033] It should be noted that the first insulating part 31 and the second insulating part 32 can be connected. For example, the first insulating part 31 and the second insulating part 32 can be connected by an insulating part that bypasses the surface of the electrode assembly 2 in the height direction. Of course, it is understood that the first insulating part 31 and the second insulating part 32 can also be independent of each other, and this embodiment does not limit this.

[0034] In one or more embodiments of this application, such as Figure 4 and Figure 5 As shown, the binding assembly 4 includes a base film layer 41 and a first adhesive layer 42, a second adhesive layer 43, and a first functional layer 44, all disposed on the side of the base film layer 41 facing the electrode assembly 2. The base film layer 41 is bonded to the side of the first insulating portion 31 opposite to the electrode assembly 2 via the first adhesive layer 42, and to the side of the second insulating portion 32 opposite to the electrode assembly 2 via the second adhesive layer 43, thereby connecting the base film layer 41 between the first insulating portion 31 and the second insulating portion 32, and allowing the base film layer 41 to span the third surface 23 of the electrode assembly 2.

[0035] In at least one possible implementation, a first functional layer 44 is disposed between a first adhesive layer 42 and a second adhesive layer 43, and is disposed corresponding to the third surface 23. The first functional layer 44 can be fixedly disposed on the base film layer 41 to improve the overall integrity of the binding assembly 4. Exemplarily, the first functional layer 44 includes a first functional material, which has a core-shell structure, and, as... Figure 4 As shown, the first functional material includes a core 441 and a shell 442 located on the surface of the core 441. The glass transition temperature of the shell 442 is 70°C-120°C, and the core 441 is configured to expand in volume in the temperature range of 70°C-130°C, with a volume expansion factor of 5-60 times.

[0036] It should be noted that the glass transition temperature refers to the critical temperature range within which an amorphous polymer (specifically, shell 442 in this embodiment) transitions from a rigid "glassy state" to a soft, elastic "highly elastic state" (or rubbery state). Below the glass transition temperature, shell 442 is in a glassy state, and the molecular chains of shell 442 are "frozen" and cannot move freely. Shell 442 behaves like glass, being hard, brittle, and exhibiting very little deformation. Above the glass transition temperature, shell 442 is in a highly elastic state. The molecular chains of shell 442 gain sufficient energy and begin to move. Shell 442 specifically becomes soft and elastic.

[0037] In this embodiment, the glass transition temperature of the shell layer 442 cannot be too low. If it is too low, it means that the softening temperature of the shell layer 442 is low, and the squeezing effect on the electrode assembly is not obvious. The glass transition temperature of the shell layer 442 cannot be too high. If it is too high, it means that the softening temperature of the shell layer 442 is high, and the expansion effect at the corresponding temperature cannot be achieved.

[0038] In this embodiment, the binding assembly 4 is used such that the first adhesive layer 42, the second adhesive layer 43, and the first functional layer 44 are all disposed on the base film layer 41, with the first functional layer 44 located between the first adhesive layer 42 and the second adhesive layer 43. The base film layer 41 is bonded to the side of the first insulating portion 31 facing away from the electrode assembly 2 via the first adhesive layer 42, and to the side of the second insulating portion 32 facing away from the electrode assembly 2 via the second adhesive layer 43, thereby fixing the binding assembly 4 to the first insulating portion 31 and the second insulating portion 32. The binding assembly 4 does not affect the contact between the first insulating portion 31 and the first surface 21, nor does it affect the contact between the second insulating portion 32 and the second surface 22. Subsequently, the temperature is increased, causing the core 441 of the first functional material of the first functional layer 44 to expand. At the same time, the shell layer 442 undergoes a glass transition, causing the entire first functional layer 44 to expand. Since the two ends of the base film layer 41 are connected to the first insulating portion 31 and the second insulating portion 32, the expanded first functional layer 44 can fill the gap between itself and the third surface 23 of the electrode assembly 2, thereby achieving the binding of the electrode assembly 2.

[0039] The battery cell provided in this embodiment uses a binding component 4 to bind the electrode component 2, especially binding the area where the third surface 23 of the electrode component 2 is located. This suppresses the increase of the gap between the electrode components 2 during use, so that the ion migration paths at each position of the electrode component 2 will not grow during charging and discharging, and the migration resistance will not increase. This reduces the risk of lithium plating, improves the fast charging capability of the battery cell, and extends the service life of the battery cell.

[0040] In at least one implementation, such as Figure 1As shown, the electrode assembly 2 can be a single-cell structure. In this case, the third surface 23 is a convex curved surface. The shape of the first functional layer 44 of the binding assembly 4 is similar to that of the third surface 23, and it is wound around the third surface 23 along the extension direction of the third surface 23. Before the first functional layer 44 expands, there is a gap between the first functional layer 44 and the third surface 23. After the first functional layer 44 expands, it can fill the gap between the first functional layer 44 and the third surface 23, thereby tightly binding the positive electrode, negative electrode and separator in the electrode assembly.

[0041] In other implementations, such as Figure 2 As shown, the electrode assembly 2 can be a dual-cell structure, in which case the third surface 23 is a curved surface with two protrusions. The first functional layer 44 of the binding assembly 4 is wound around the third surface 23 and supported on the two protrusions of the third surface 23. After the first functional layer 44 expands, it fills the gap between the first functional layer 44 and the third surface 23, and fills the gap between the two cells, so as to tightly bind the two cells.

[0042] It should be noted that the side of the base film layer 41 facing away from the electrode assembly 2 may or may not contact the inner wall of the outer shell assembly 1; this embodiment does not limit this. When the side of the base film layer 41 facing away from the electrode assembly 2 contacts the inner wall of the outer shell assembly 1, it can improve the stability of the electrode assembly 2 within the outer shell assembly 1, reduce the risk of shaking, and thus improve safety.

[0043] In some embodiments, such as Figure 6 As shown, the first functional layer 44 is disposed between the first adhesive layer 42 and the second adhesive layer 43. The first functional layer 44, the first adhesive layer 42, and the second adhesive layer 43 can be disposed in the same layer, and the first functional layer 44 is located between the first adhesive layer 42 and the second adhesive layer 43.

[0044] In other embodiments, such as Figure 7 As shown, the first functional layer 44 is disposed between the first adhesive layer 42 and the second adhesive layer 43. Alternatively, in the extension direction of the binding component 4, the first functional layer 44 is located between the first adhesive layer 42 and the second adhesive layer 43, and the first functional layer 44, the first adhesive layer 42 and the second adhesive layer 43 are not necessarily disposed in the same layer.

[0045] In some alternative embodiments, the material of the shell layer 442 includes at least one selected from polystyrene, acrylic resin, polymethyl methacrylate, and polyurethane. Preferably, the material of the shell layer 442 is acrylic resin, which allows the shell layer 442 to have good flexibility, processability, and chemical stability.

[0046] In some embodiments, the material of the core 441 includes at least one selected from n-hexane, cyclohexane, methanol, ethanol, and isopropanol. Preferably, the material of the core 441 is cyclohexane, which gives the core 441 a moderate boiling point and good expansion properties, thus giving the core 441 good expansion performance.

[0047] In one or more embodiments of this application, such as Figure 4 and Figure 8 As shown, the binding component 4 also includes a second functional layer 45. The second functional layer 45 is disposed on the side of the first functional layer 44 facing away from the base film layer 41, that is, between the first functional layer 44 and the third surface 23 facing the electrode assembly 2. The second functional layer 45 is used to prevent the first functional layer 44 from directly contacting the electrode assembly 2, thereby preventing the first functional layer 44 from expanding and squeezing, deforming, or even breaking the electrode assembly 2. Exemplarily, the second functional layer 45 completely covers the first functional layer 44 to better protect the electrode assembly 2. The second functional layer 45 is offset from both the first adhesive layer 42 and the second adhesive layer 43 to avoid affecting the bonding effect of the first adhesive layer 42 and the second adhesive layer 43.

[0048] In some embodiments, the second functional layer 45 includes a second functional material. Exemplarily, the second functional material includes at least one of polymer foam, aerogel, carbon adsorbent, inorganic adsorbent, and composite adsorbent. This configuration enables the second functional material to adsorb electrolyte, thereby allowing the second functional layer 45 to replenish the electrolyte on the third surface 23 of the electrode assembly 2, effectively improving the lifespan of the battery cell.

[0049] For example, polymeric foams may include polyurethane foam, pearl cotton, etc. Aerogels may include resin-based aerogels, carbon-based aerogels, etc. Carbon adsorbent materials may include activated carbon, carbon nanotubes, etc. Inorganic adsorbent materials may include mesoporous silica materials, zeolite molecular sieves, etc. Composite adsorbent materials may include graphene / clay composites, carbon-based polymer composites, etc.

[0050] Preferably, the second functional material includes polymer foam. Polymer foam can absorb and store electrolyte. During battery cell cycling, on the one hand, the binding component 4 suppresses the increase in gap between electrode components 2 in the region near the third surface 23 (i.e., the bending region). On the other hand, if the gap between electrode components 2 increases, it will exert a compressive force on the second functional layer 45, causing the electrode liquid stored in the second functional material layer to be released, preferentially replenishing the electrolyte in the bending region of the electrode components 2, thereby improving cycle performance.

[0051] Preferably, the second functional material includes polyurethane foam. The polyurethane foam provided in this embodiment has high porosity, large pore size, strong electrolyte absorption capacity, and also has certain strength and toughness. The internal stress of the battery cell can be released by compressing the polyurethane foam, thereby buffering and reducing the expansion of the battery cell. The polyurethane foam can maintain good buffering function under long-term volume change compression.

[0052] In some alternative embodiments, such as Figure 4 As shown, the thickness of the second functional layer 45 is c, where 0.2mm ≤ c ≤ 1mm. The thickness of the second functional layer 45 cannot be too large, as this would occupy the space of the first functional layer 44, thus affecting the expansion of the first functional layer 44 and the overall binding capacity of the binding assembly 4. The thickness of the second functional layer 45 cannot be too small, as this would affect the amount of electrolyte adsorbed by the second functional layer 45 and reduce its protective effect on the electrode assembly 2.

[0053] For example, the thickness of the second functional layer 45 can be 0.2mm, 0.3mm, 0.5mm, 0.6mm, 0.8mm, 0.9mm, 1mm, etc.

[0054] In some alternative embodiments, such as Figure 8 As shown, the second functional layer 45 can protrude from the first adhesive layer 42 and the second adhesive layer 43, that is, the second functional layer 45 is not on the same layer as the first adhesive layer 42 and the second adhesive layer 43.

[0055] In other alternative embodiments, such as Figure 9 As shown, the second functional layer 45 may not protrude from the first adhesive layer 42 and the second adhesive layer 43. That is, the second functional layer 45, the first adhesive layer 42 and the second adhesive layer 43 may be disposed in the same layer. This embodiment does not limit this.

[0056] In one or more embodiments of this application, such as Figure 8 and Figure 9 As shown, the restraint assembly 4 also includes a third adhesive layer 46. The first functional layer 44 is bonded to the base film layer 41 through the third adhesive layer 46. By providing the third adhesive layer 46, the connection strength between the first functional layer 44 and the base film layer 41 can be improved, the risk of the first functional layer 44 falling off can be reduced, and thus the overall integrity of the restraint assembly can be improved.

[0057] In some embodiments, such as Figure 8 As shown, the third adhesive layer 46, the first adhesive layer 42, and the second adhesive layer 43 can be disposed on the same layer, and the first functional layer 44 and the second functional layer 45 protrude from the first adhesive layer 42.

[0058] In other embodiments, such as Figure 9As shown, the sum of the thicknesses of the third adhesive layer 46, the first functional layer 44, and the second functional layer 45 is equal to the thickness of the first adhesive layer 42 (or the second adhesive layer 43), but this embodiment does not limit this. The thickness of the second functional layer 45 can refer to its thickness when it is not expanded.

[0059] In at least one possible implementation, such as Figure 10 As shown, the end face of the restraint component 4 in the third direction Z is flush with the end face of the electrode component 2 in the third direction Z. This arrangement ensures that the restraint component 4 corresponds to the end face of the electrode component 2 in the third direction Z, thereby avoiding the problem of increased gap at the end face of the electrode component 2 in the third direction Z. Here, the third direction Z is the height direction of the electrode component 2, that is, the third direction Z, the first direction X, and the second direction Y are perpendicular to each other.

[0060] It should be noted that the electrode assembly 2 has two end faces in the third direction Z, and the binding assembly 4 is flush with both end faces of the electrode assembly 2.

[0061] In other possible implementations, such as Figure 11 As shown, the end face of the restraint component 4 in the third direction Z extends beyond the end face of the electrode component 2 in the third direction Z by a first distance a, where a ≤ 1 mm. This arrangement ensures that the restraint component covers the end face of the electrode component 2 in the third direction Z, thereby allowing the first functional layer 44 to fill the gap near the end face after expansion, thus ensuring that the gap at the end face does not increase.

[0062] It should be noted that the distance by which the restraint component 4 extends beyond the electrode component 2 in the third direction Z cannot be too large, otherwise it will interfere with the installation of the top cover of the battery cell. For example, the value of 'a' can be 0.1mm, 0.5mm, 0.8mm, 0.9mm, 1mm, etc., and this embodiment does not limit this value.

[0063] In some optional embodiments, the restraint component 4 can cover the entire third surface 23, that is, the restraint component 4 can cover the entire area of ​​the electrode component 2 in the length direction. In this way, the uniformity of restraining the electrode component 2 can be improved, so that the force on the electrode component 2 is more uniform and the restraint effect is improved.

[0064] In other alternative embodiments, multiple binding components 4 may be provided at intervals along the third direction Z. The multiple binding components 4 cooperate with each other to bind the electrode assembly 2, which can also suppress the increase of the gap.

[0065] In some alternative embodiments, such as Figure 4As shown, the thickness of the first functional layer 44 is b, where 0.01mm ≤ b ≤ 5mm. The thickness of the first functional layer 44 cannot be too large, otherwise the electrode assembly 2 may be damaged due to excessive expansion and extrusion pressure. The thickness of the first functional layer 44 cannot be too small, otherwise the first functional layer 44 will be too thin, that is, there will be less first functional material, which will result in the first functional layer 44 expanding insignificantly, having a weak binding effect on the electrode assembly 2, and the electrode assembly 2 will also have a higher risk of lithium plating.

[0066] For example, the thickness of the first functional layer 44 can be 0.01mm, 0.05mm, 0.1mm, 0.15mm, 0.2mm, 1mm, 1.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc., and this embodiment does not limit it.

[0067] In some optional implementations, please refer to [link / reference]. Figure 4 The thickness of the base film layer 41 is d, where 0.01mm ≤ d ≤ 0.1mm. The thickness of the base film layer 41 cannot be too large, as this would affect the load capacity of the first functional layer 44, and consequently affect the expansion effect of the confinement component 4. The thickness of the base film layer 41 cannot be too small, as this would reduce the confinement force on the first functional layer 44, making the base film layer 41 prone to cracking, and thus affecting the compression effect on the electrode component 2. For example, the thickness of the base film layer 41 can be 0.01mm, 0.03mm, 0.05mm, 0.06mm, 0.08mm, 0.1mm, etc., and this embodiment does not limit it.

[0068] In at least one possible implementation, such as Figure 7 As shown, the thickness of the first adhesive layer 42 is e, where 10μm≤e≤200μm. The thickness of the first adhesive layer 42 cannot be too large, as this would increase the weight of the entire binding assembly 4. The thickness of the first adhesive layer 42 cannot be too small, as this would affect the adhesion between the base film layer 41 and the first insulating portion 31, thereby affecting the binding effect of the binding assembly 4.

[0069] For example, the thickness of the first adhesive layer 42 can be 10μm, 50μm, 80μm, 100μm, 120μm, 150μm, 180μm, 200μm, etc.

[0070] In some embodiments, such as Figure 7 As shown, the thickness of the second adhesive layer 43 is f, where 10μm≤f≤200μm. The thickness of the second adhesive layer 43 cannot be too large, as this would increase the weight of the entire binding assembly 4. The thickness of the second adhesive layer 43 cannot be too small, as this would affect the adhesion between the base film layer 41 and the second insulating part 32, thereby affecting the binding effect of the binding assembly 4.

[0071] For example, the thickness of the second adhesive layer 43 can be 10μm, 50μm, 80μm, 100μm, 120μm, 150μm, 180μm, 200μm, etc.

[0072] In some embodiments, the thickness of the first adhesive layer 42 and the thickness of the second adhesive layer 43 may be equal, that is, e=f, ​​but this is not a limitation.

[0073] Optionally, the thickness of the third adhesive layer 46 can range from 10μm to 200μm. The thickness of the third adhesive layer 46 cannot be too large, as this would affect the load capacity of the first functional layer 44, and consequently affect the expansion effect of the confinement component 4. The thickness of the third adhesive layer 46 cannot be too small, as this would affect the bonding effect, and consequently cause the first functional layer 44 to separate from the base film layer 41.

[0074] In at least one embodiment, the adhesive layer (i.e., the first adhesive layer 42, the second adhesive layer 43, and the third adhesive layer 46) is made of at least one of acrylic adhesive, polyurethane adhesive, and epoxy resin adhesive.

[0075] In one or more embodiments of this application, the first functional layer 44 further includes a first adhesive, wherein the material of the first adhesive is at least one selected from styrene-butadiene rubber, polyacrylic acid, and carboxymethyl cellulose. Preferably, the first adhesive is styrene-butadiene rubber, and the mass ratio of the first functional material to the first adhesive in the first functional layer 44 is 70:30-98:2. The mass ratio of the first functional material to the first adhesive cannot be too large, as this will result in poor adhesion within the first functional layer 44 and easy cracking. The mass ratio of the first functional material to the first adhesive cannot be too small, as this will result in poor expansion of the first functional layer 44, and excessive first adhesive will make expansion difficult.

[0076] In some embodiments, the first functional layer 44 is prepared by adding the first functional material and the first binder into a first solvent (e.g., at least one of NMP or deionized water), mixing them evenly, coating them onto the surface of the base film layer 41, and then drying them (at a temperature of 30°C-45°C) to obtain the first functional layer 44.

[0077] In some optional embodiments, the second functional layer 45 can be bonded to the surface of the first functional layer 44 by adhesive coating, or it can be prepared as a slurry and coated onto the surface of the first functional layer 44. The method of preparing a slurry involves adding the second functional material and the second binder to a second solvent (e.g., at least one of acetone, ethyl acetate, and NMP), mixing them thoroughly, applying the mixture to the surface of the first functional layer 44, and then drying it (at a temperature of 25°C-45°C) to obtain the second functional layer 45. The mass ratio of the second functional material to the second binder is 80:20-97:3 to ensure the functionality of both materials. The second binder can be at least one of styrene-butadiene rubber, polyacrylic acid, and carboxymethyl cellulose.

[0078] This embodiment also provides a method for preparing a battery cell, used to prepare the aforementioned battery cell. The method for preparing the battery cell includes the following steps: S1. The first insulating part 31 of the insulating member 3 covers the first surface 21 of the electrode assembly 2, and the second insulating part 32 of the insulating member 3 covers the second surface 22 of the electrode assembly 2. S2. The base film layer 41 of the binding component 4 is bonded to the side of the first insulating part 31 away from the electrode component 2 by the first adhesive layer 42, and bonded to the side of the second insulating part 32 away from the electrode component 2 by the second adhesive layer 43, and the first functional layer 44 is located between the base film layer 41 and the third surface 23 of the electrode component 2. S3. Place the assembled electrode assembly 2, insulating component 3 and binding assembly 4 into the receiving cavity 11 of the outer shell assembly 1, perform one liquid injection and then seal the receiving cavity 11. S4. Bake the outer casing assembly 1 to expand the first functional layer 44 of the binding assembly 4 and fill the gap between the third surface 23 and the base film layer 41 to obtain a battery cell.

[0079] In step S1, the first insulating part 31 may or may not be connected to the first surface 21; this embodiment does not limit this. The second insulating part 32 may or may not be connected to the second surface 22; this embodiment does not limit this.

[0080] In step S2, the binding component 4 is connected to the first insulating part 31 and the second insulating part 32, thereby fixing the binding component 4. The first functional layer 44 is disposed opposite to the third surface, so that the first functional layer 44 will not affect the connection between the first insulating part 31 and the first surface 21 and the second insulating part 32 and the second surface 22.

[0081] In step S3, the electrode assembly 2, the insulating member 3, and the binding assembly 4, all disposed on the electrode assembly 2, are placed into the receiving cavity 11, and then electrolyte is injected into the receiving cavity 11. When the binding assembly 4 includes a second functional layer 45, the second functional layer 45 adsorbs the electrolyte during this process.

[0082] In step S4, the outer shell assembly 1 is baked from the outside, causing the temperature of the outer shell assembly 1 and the electrode assembly 2 and the binding assembly 4 inside it to rise. When the temperature of the first functional layer 44 of the binding assembly 4 rises to, for example, 70°C-120°C, the volume of the core 441 of the first functional material expands, and the shell layer 442 undergoes a glass transition, thereby enabling the first functional layer 44 to fill the gap between the third surface 23 and the base film layer 41, thus binding the electrode assembly 2.

[0083] In the battery cell fabrication method provided in this embodiment, the expansion of the first functional layer 44 is performed after the electrode assembly 2 is installed into the housing assembly 1. This eliminates the need for contouring treatment of the first functional layer 44, allowing it to form different shapes according to the gap between the base film layer 41 and the third surface 23 of the electrode assembly 2. This provides better flexibility, filling effect, and binding effect. Furthermore, the binding assembly 4 provided in this embodiment has a lower manufacturing cost, is simple to operate, and is easy to install.

[0084] In some optional embodiments, the baking temperature for baking the outer casing assembly 1 is 80°C-120°C. Within this temperature range, the core 441 of the first functional material in the first functional layer 44 expands, causing the first functional layer 44 to expand in connection with the second functional layer 45. With the help of the corresponding components of the battery cell, the shape of this expansion can conform to the bending area of ​​the electrode assembly 2 (i.e., near the third surface 23), thereby confining the bending area and suppressing the increase of the gap between the positive and negative electrode plates.

[0085] This embodiment also provides a battery that reduces the risk of lithium plating and has a longer service life. Exemplarily, the battery includes the battery cell described above; or, the battery includes a battery cell prepared according to the method described above for preparing the battery cell.

[0086] This embodiment also provides an electrical device that offers high safety. Exemplarily, the electrical device includes the battery described above; or, the electrical device includes the battery cell described above; or, the electrical device includes a battery cell prepared according to the battery cell preparation method described above.

[0087] For example, electrical devices may include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles may be gasoline-powered vehicles, natural gas-powered vehicles, or new energy vehicles; new energy vehicles may be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc.; spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0088] Example The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0089] Example 1 This embodiment provides a single battery cell, the specific preparation method of which is as follows: Materials used in the preparation: 2 pre-wound electrode assembly, 3 insulating component, battery cell support plate, 1 outer shell assembly, 4 binding assembly, electrolyte, aluminum nail for sealing the injection hole, plastic nail for sealing the injection hole, and top cover patch.

[0090] The specific preparation steps are as follows: The binding component 4 is prepared as follows: the base film layer 41 has a thickness of 0.05 mm, and the adhesive layers (specifically, the first adhesive layer 42, the second adhesive layer 43, and the third adhesive layer 46) each have a thickness of 60 μm. The adhesive layer material is acrylic adhesive. The first functional layer 44 has a thickness of 1.2 mm, and the first adhesive in the first functional layer 44 is styrene-butadiene rubber. The mass ratio of the first functional material to the first adhesive is 90:10. The first functional layer 44 is prepared by adding the first functional material and the first adhesive to a first solvent (NMP in this embodiment), mixing them evenly, coating them on the surface of the base film layer 41, and then drying them (at a drying temperature of 35°C) to obtain the first functional layer 44. The second functional layer 45 has a thickness of 0.8 mm and is bonded to the surface of the first functional layer 44. Specifically, the second functional layer 45 can be prepared as a slurry and coated on the surface of the first functional layer 44. The method for preparing the slurry coating involves adding the second functional material and the second binder to the second solvent acetone, mixing them evenly, applying the mixture to the surface of the first functional layer 44, and then drying it (at a temperature of 30°C) to obtain the second functional layer 45. The mass ratio of the second functional material to the second binder is 95:5. The second binder is styrene-butadiene rubber.

[0091] Preparation process of core-shell structure: For ease of understanding, the core-shell structure will be referred to as microspheres in the following content. I. Raw Material Preparation; Monomers and Crosslinking Agent: Acrylic acid and methyl methacrylate (mass ratio 1:1) are used as the main monomers to synthesize the polyacrylic acid resin shell. N,N-methylenebisacrylamide is selected as the crosslinking agent, with its dosage controlled at 1.25% of the total monomer mass to adjust the degree of crosslinking of the shell. Potassium persulfate (KPS) is selected as the water-soluble initiator, with a dosage of 0.5% of the total monomer mass, used to initiate the polymerization reaction. Polyvinyl alcohol (PVA) is selected as the dispersant, with a dosage of 3% of the total monomer mass, and its aqueous solution concentration controlled at 2%, which helps stabilize the emulsion system and prevent microsphere aggregation. Core Material: Cyclohexane with a purity of not less than 99% is used as the expanding core material. Other: Deionized water is used as the reaction medium to prepare the reaction solution and ensure the purity of the system.

[0092] II. Preparation of Pre-emulsion; 1. Add acrylic acid and methyl methacrylate monomers to a beaker, add crosslinking agent N,N-methylenebisacrylamide, and stir until homogeneous. 2. Add 0.5% (by weight of total monomers) of potassium persulfate initiator to the above mixed monomers, and stir until fully dissolved to obtain a monomer mixture. 3. In another beaker, prepare a 2% polyvinyl alcohol aqueous solution, with the amount of polyvinyl alcohol being 3% of the total monomer mass. Slowly add the polyvinyl alcohol aqueous solution to the monomer mixture while stirring, maintaining a 1:1 mass ratio of polyvinyl alcohol aqueous solution to monomer mixture. 4. Stir at 1500 rpm for 45 minutes using a high-speed stirrer to form a stable pre-emulsion system.

[0093] III. Emulsion Polymerization; 1. Transfer the pre-emulsion system to a four-necked flask equipped with a stirrer, thermometer, and condenser. Dilute with 1.2 times the mass of deionized water to bring the total volume of the reaction system to a suitable range. 2. Start stirring, controlling the speed at 450 r / min, and simultaneously raise the temperature to 70°C to initiate the polymerization reaction. 3. Continue stirring during the reaction, maintaining a stable temperature. Control the reaction time to 3 hours, observing the system status during this period to ensure the polymerization reaction proceeds fully.

[0094] IV. Core Injection; 1. After 1.5 hours of polymerization, cyclohexane is slowly added dropwise to the reaction system, with the amount of cyclohexane added controlled at 35% of the total monomer mass. 2. Stirring is maintained during the dropwise addition to ensure that the cyclohexane is uniformly dispersed in the polymer emulsion, forming an oil-water-polymer three-phase system. 3. The reaction continues for 1.5 hours to further solidify the polyacrylic acid resin shell, encapsulating the cyclohexane to form a complete microsphere structure.

[0095] V. Post-processing; 1. Washing: After the reaction, the product is cooled to room temperature and collected by centrifugation (4500 r / min, 7.5 min). The microspheres are then washed five times with deionized water to remove residual monomers, initiators, and dispersants. 2. Drying: The washed microspheres are placed in a vacuum drying oven and dried at 30℃ for 24 hours until the moisture content is less than 1%, yielding dried, expanded microspheres. 3. Screening: The dried microspheres are screened by particle size using a vibrating sieve. Microspheres with a particle size of 40 μm are selected as the finished product based on actual application requirements.

[0096] The preparation steps of the electrode assembly are as follows: Positive electrode preparation: Lithium iron phosphate, conductive carbon black and polyvinylidene fluoride are mixed in a mass ratio of 88:7:5 to form a slurry, which is then coated onto aluminum foil to obtain the positive electrode.

[0097] Negative electrode preparation: Graphite, conductive carbon black, carboxymethyl cellulose, and styrene-butadiene rubber are mixed in a mass ratio of 92:2:3:3 to form a slurry, which is then coated onto copper foil to obtain the negative electrode.

[0098] Diaphragm: The diaphragm is made of polyethylene (PE).

[0099] The positive electrode, separator, and negative electrode are fabricated into an electrode assembly.

[0100] Electrolyte preparation method: The electrolyte concentration is 1.2 mol / L LiPF6, and the solvent is a mixed solution of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a volume ratio of 3:3:4.

[0101] The preparation method of a single battery cell is as follows: Using the aforementioned electrode assembly 2, the insulating component 3 covers a large area of ​​the electrode assembly 2; that is, the first insulating part 31 covers the first surface 21, the second insulating part 32 covers the second surface 22, and the third surface 23 is not covered by the insulating component 3. The binding component 4 extends 0.5 mm beyond the end face of the electrode assembly 2 in the third direction Z. One end of the base film layer 41 is adhered to the surface of the first insulating part 31 facing away from the electrode assembly 2 via the first adhesive layer 42, and the other end of the base film layer 41 is adhered to the surface of the second insulating part 32 facing away from the electrode assembly 2 via the second adhesive layer 43. The first functional layer 44 is positioned opposite the third surface 23 in the direction facing the electrode assembly 2. The battery cell is placed in the housing assembly 1, electrolyte is injected, the housing assembly 1 is sealed, and after baking and electrolyte injection, a battery cell is obtained. The baking temperature is 95°C. At this temperature, the core 441 of the first functional material in the first functional layer 44 expands, causing the first functional layer 44 to expand in conjunction with the second functional layer 45. With the help of the corresponding components of the battery cell, the shape of the expansion can fit the bending area (i.e., the third surface 23) of the electrode assembly 2, thereby restricting the increase in the gap between the positive and negative electrode plates in the R-angle region of the electrode assembly 2.

[0102] Example 2: The battery cell provided in this embodiment differs from that in Embodiment 1 in that: the adhesive layers of the binding assembly 4 (specifically referring to the first adhesive layer 42, the second adhesive layer 43, and the third adhesive layer 46) are made of epoxy resin; the first adhesive in the first functional layer 44 is made of carboxymethyl cellulose; the shell layer 442 in the first functional layer 44 is made of polymethyl methacrylate; the core material is made of isopropanol; and the second functional material of the second functional layer 45 is activated carbon fiber, a carbon adsorption material. Everything else is the same as in Embodiment 1.

[0103] Preparation of the core-shell structure: 1. A prepolymer solution was prepared by mixing methyl methacrylate, initiator, and crosslinking agent with an aqueous dispersant solution and emulsifying. 2. Polymerization was initiated by heating to form a polymethyl methacrylate shell. 3. Isopropanol was added dropwise to continue the reaction and encapsulate the core. 4. The mixture was cooled, washed, and dried to obtain expanded microspheres.

[0104] Example 3: The difference between the battery cell provided in this example and Example 1 is that the binding component 4 does not extend beyond the end face of the electrode component 2 in the third direction Z in the third direction Z. Otherwise, it is the same as Example 1.

[0105] Example 4: The difference between the battery cell provided in this example and Example 1 is that the restraint component 4 does not include the second functional layer 45, but otherwise it is the same as Example 1.

[0106] Example 5: The difference between the battery cell provided in this example and Example 1 is that the thickness of the first functional layer 44 is 0.01 mm, and the rest is the same as in Example 1.

[0107] Example 6: The difference between the battery cell provided in this example and Example 1 is that the thickness of the first functional layer 44 is 5mm, and the rest is the same as in Example 1.

[0108] Example 7: The difference between the battery cell provided in this example and Example 1 is that the baking temperature is 80°C, and the rest is the same as in Example 1.

[0109] Example 8: The difference between the battery cell provided in this example and Example 1 is that the baking temperature is 120°C, and the rest is the same as in Example 1.

[0110] Comparative Example 1: The difference between the battery cell provided in this comparative example and Example 1 is that the binding component 4 is not provided, and ordinary tape is used instead of the binding component 4. Otherwise, it is the same as Example 1.

[0111] Comparative Example 2: The difference between the battery cell provided in this comparative example and Example 1 is that the restraint component 4 only includes the second functional layer 45 and does not include the first functional layer 44, otherwise it is the same as Example 1.

[0112] Comparative Example 3: The difference between the battery cell provided in this comparative example and Example 1 is that the confinement component 4 includes both the first functional layer 44 and the second functional layer 45, but the glass transition temperature of the shell layer 442 is lower than 70°C. Specifically, the material of the shell layer 442 is butyl acrylate (BA)-methacrylic acid (MAA) copolymer, and the rest is the same as in Example 1.

[0113] Comparative Example 4: The difference between the battery cell provided in this comparative example and Example 1 is that the confinement component 4 includes both the first functional layer 44 and the second functional layer 45, but the glass transition temperature of the shell layer 442 is higher than 120°C. Specifically, the material of the shell layer 442 is an acrylonitrile (AN)-methyl methacrylate (MMA)-methacrylamide (MAM) terpolymer, and the rest is the same as in Example 1.

[0114] The batteries formed from the battery cells provided in Examples 1 to 7 and the batteries formed from the battery cells provided in Comparative Examples 1 to 4 were tested. The specific test methods were as follows: Cyclic performance testing procedure: Under constant temperature conditions of 25℃, the battery is charged to 3.65V using a 2C constant current, then charged to 0.05C using a constant voltage, and then left to stand for 30 minutes; then discharged to 2.0V using a 1C constant current, and left to stand for 30 minutes. This constitutes one cycle. Continuous cycling is performed, and the discharge capacity of each cycle is recorded.

[0115] Calculation method: Capacity retention rate = Cn / C1*100%. Where C1 is the discharge capacity of the first cycle and Cn is the discharge capacity of the nth cycle. Obviously, the above embodiments of this application are merely examples for clear illustration and are not intended to limit the implementation of this application. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of the claims of this application.

Claims

1. A single battery cell, characterized in that, include: The housing assembly (1) includes a receiving cavity (11); An electrode assembly (2) is disposed within the receiving cavity (11). The electrode assembly (2) includes a first surface (21), a second surface (22), and a third surface (23). The first surface (21) and the second surface (22) are disposed opposite each other in a first direction (X). The third surface (23) is the surface of the electrode assembly (2) in a second direction (Y) and is connected between the first surface (21) and the second surface (22). The first direction (X) is the thickness direction of the electrode assembly (2), and the second direction (Y) is the length direction of the electrode assembly (2). The insulating member (3) includes a first insulating part (31) and a second insulating part (32), wherein the first insulating part (31) covers the first surface (21) and the second insulating part (32) covers the second surface (22); The binding assembly (4) includes a base film layer (41) and a first adhesive layer (42), a second adhesive layer (43), and a first functional layer (44) all disposed on the side of the base film layer (41) facing the electrode assembly (2). The base film layer (41) is bonded to the side of the first insulating portion (31) away from the electrode assembly (2) through the first adhesive layer (42), and is bonded to the side of the second insulating portion (32) away from the electrode assembly (2) through the second adhesive layer (43). The first functional layer (44) is disposed on the side of the first insulating portion (31) facing the electrode assembly (2). The first functional layer (44) is disposed between the adhesive layer (42) and the second adhesive layer (43) and corresponding to the third surface (23); the first functional layer (44) includes a first functional material, the first functional material is a core-shell structure, and the first functional material includes a core (441) and a shell (442) located on the surface of the core (441), the glass transition temperature of the shell (442) is 70℃-120℃, and the core (441) is configured to expand in volume in the temperature range of 70℃-130℃, and the volume expansion factor is 5-60 times.

2. The battery cell according to claim 1, characterized in that, The material of the shell layer (442) includes at least one of polystyrene, acrylic resin, polymethyl methacrylate, and polyurethane; And / or, The material of the core (441) includes at least one of n-hexane, cyclohexane, methanol, ethanol, and isopropanol.

3. The battery cell according to claim 1 or 2, characterized in that, The binding assembly (4) further includes a second functional layer (45), which is disposed on the side of the first functional layer (44) away from the base film layer (41); The second functional layer (45) includes a second functional material, which includes at least one of polymer foam, aerogel, carbon adsorbent, inorganic adsorbent, and composite adsorbent. Preferably, the second functional material includes polymer foam; Preferably, the second functional material includes polyurethane foam; Preferably, the thickness of the second functional layer (45) is c, wherein 0.2mm≤c≤1mm.

4. The battery cell according to claim 1 or 2, characterized in that, The end face of the restraint component (4) in the third direction (Z) is flush with the end face of the electrode component (2) in the third direction (Z); or, the end face of the restraint component (4) in the third direction (Z) extends beyond the end face of the electrode component (2) in the third direction (Z) by a first distance a, where a≤1mm; The third direction (Z) is perpendicular to both the first direction (X) and the second direction (Y).

5. The battery cell according to claim 1, characterized in that: The thickness of the first functional layer (44) is b, where 0.01mm≤b≤5mm; And / or, the thickness of the base film layer (41) is d, wherein 0.01mm≤d≤0.1mm; And / or, the thickness of the first adhesive layer (42) is e, where 10 μm ≤ e ≤ 200 μm; And / or, the thickness of the second adhesive layer (43) is f, wherein 10μm≤f≤200μm; preferably, e=f.

6. The battery cell according to claim 1, characterized in that, The binding assembly (4) further includes a third adhesive layer (46), through which the first functional layer (44) is bonded to the base film layer (41).

7. A method for preparing a battery cell, used to prepare a battery cell as described in any one of claims 1-6, characterized in that, The method for preparing the battery cell includes the following steps: The first insulating portion (31) of the insulating member (3) covers the first surface (21) of the electrode assembly (2), and the second insulating portion (32) of the insulating member (3) covers the second surface (22) of the electrode assembly (2). The base film layer (41) of the binding component (4) is bonded to the side of the first insulating part (31) away from the electrode component (2) by the first adhesive layer (42), and is bonded to the side of the second insulating part (32) away from the electrode component (2) by the second adhesive layer (43), and the first functional layer (44) is located between the base film layer (41) and the third surface (23) of the electrode component (2); The assembled electrode assembly (2), the insulating component (3) and the binding assembly (4) are placed into the receiving cavity (11) of the outer shell assembly (1), and the receiving cavity (11) is sealed after one liquid injection. The outer casing assembly (1) is baked to expand the first functional layer (44) of the binding assembly (4) and fill the gap between the third surface (23) and the base film layer (41) to obtain a battery cell.

8. The method for preparing a battery cell according to claim 7, characterized in that, The temperature during baking of the outer shell assembly (1) is 80℃-120℃.

9. A battery, characterized in that, The battery comprises a battery cell as described in any one of claims 1-6; or, the battery comprises a battery cell prepared by the method for preparing a battery cell as described in claim 7 or 8.

10. An electrical appliance, characterized in that, The power-consuming device includes the battery as described in claim 9; or, the power-consuming device includes a battery cell as described in any one of claims 1-6; or, the power-consuming device includes a battery cell prepared by the method for preparing a battery cell as described in claim 7 or 8.

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