Battery cell

Abstract

The utility model discloses a battery monomer, and relates to the technical field of batteries. The battery monomer comprises a battery cell assembly, a first functional layer and a second functional layer, the battery cell assembly comprises a pole piece and a diaphragm which are arranged in a laminated manner, the battery cell assembly is provided with two side surfaces which are oppositely arranged in a first direction, and the first direction is the width direction of the battery cell assembly; the first functional layer covers the two side surfaces; the second functional layer is filled in a gap among the first functional layer, the pole piece and the diaphragm; wherein the hardness of the first functional layer is smaller than that of the second functional layer. Therefore, the first functional layer and the second functional layer have the functions of fixing, supporting and insulating the electrode assembly and the liquid retaining effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery, in particular to a battery monomer. BACKGROUND

[0002] The battery monomer is generally assembled by a shell, a cover plate and a cell assembly. For the cell assembly of the laminated sheet, the positive sheet, the negative sheet and the diaphragm form the cell assembly after the laminating and hot pressing process. Considering the internal insulation and consistent stress of the battery monomer, the cell assembly is generally bundled by using the adhesive tape, the side of the cell assembly is protected by using the side support, and the cell assembly is coated by using the insulating film, so that the cell assembly and the inner surface of the shell are insulated and isolated. Therefore, the complexity of the structure of the battery monomer is increased, and the structural reliability is poor. CONTENT OF THE UTILITY MODEL

[0003] The utility model discloses a battery monomer to solve the technical problem of low energy density, poor structural reliability, poor cycle performance and low production efficiency of the battery monomer caused by adhesive tape, insulating film and side support.

[0004] To achieve the above-mentioned purpose, the utility model provides a battery monomer, which comprises: a cell assembly, the cell assembly comprising laminated positive sheets and diaphragms, the cell assembly having two opposite sides in a first direction, the first direction being the width direction of the cell assembly; a first functional layer covering the two sides; and a second functional layer filling the gap between the first functional layer, the positive sheets and the diaphragms, wherein the hardness of the first functional layer is less than that of the second functional layer.

[0005] In some embodiments, the positive sheets and the negative sheets are alternately laminated, and the diaphragm is arranged between the positive sheets and the negative sheets to insulate and isolate the positive sheets and the negative sheets; the two sides are a first side and a second side, and the gap comprises a first gap and a second gap; on the first side, the first gap is formed between two diaphragms adjacent to the same positive sheet; on the second side, the second gap is formed between two diaphragms adjacent to the same negative sheet; and the second functional layer fills the first gap and the second gap and is located on the opposite side of the two first functional layers covering the two sides.

[0006] In some embodiments, the diaphragm comprises a plurality of first corner portions and a plurality of second corner portions, the first corner portion is located on the first side and covers the first side of the negative sheet in the first direction, and the second corner portion is located on the second side and covers the first side of the positive sheet in the first direction; wherein on the first side, the first gap is formed between two first corner portions adjacent to the same positive sheet; and on the second side, the second gap is formed between two second corner portions adjacent to the same negative sheet.

[0007] In some embodiments, the battery cell assembly has a first surface and a second surface oppositely arranged in a second direction, the second direction being a stacking direction of the battery cell assembly; the first functional layer extends and partially covers the first surface and the second surface.

[0008] In some embodiments, the second functional layer is further arranged between the first surface and the first functional layer and between the second surface and the first functional layer.

[0009] In some embodiments, the first functional layer is an organic material, and the second functional layer is a mixture of inorganic material and organic material.

[0010] In some embodiments, the compression amount of the first functional layer is greater than the compression amount of the second functional layer.

[0011] In some embodiments, the first functional layer and the second functional layer both have porosity.

[0012] In some embodiments, the battery cell assembly includes a body portion and two tab portions, one of the two tab portions being connected to one end of the body portion along the second direction, and the other of the two tab portions being connected to the other end of the body portion along the second direction, the second direction being a stacking direction of the battery cell assembly.

[0013] In some embodiments, the battery cell assembly is arranged in a housing.

[0014] The technical effect of the battery monomer is to provide a battery cell assembly by arranging a first functional layer and a second functional layer on both sides of the battery cell assembly in the width direction. The second functional layer fills the gap between the first functional layer, the electrode sheet and the separator to fix the relative position of the multiple separators, positive electrode sheets and negative electrode sheets in the battery cell assembly, to enhance the adhesion between the electrode sheet and the separator, avoid the dislocation of the electrode sheet, and ensure that the reaction area does not deform. The first functional layer has insulation and support functions, and can directly replace the side support plate and the insulation film to simplify the production steps from battery monomer molding to assembly, and speed up the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0015] The technical scheme and other beneficial effects of the present application will become apparent from the following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings.

[0016] Figure 1 is a top view of a conventional battery monomer.

[0017] Figure 2 is a side view of a conventional battery monomer.

[0018] Figure 3 is a sectional view of a conventional battery monomer.

[0019] Figure 4A top view of the battery cell assembly provided by the embodiment of the present application.

[0020] Figure 5 A side view of the battery cell assembly provided by the embodiment of the present application.

[0021] Figure 6 A top view of the battery cell provided by the embodiment of the present application.

[0022] Figure 7 A side view of the battery cell provided by the embodiment of the present application.

[0023] Figure 8 A sectional view of the battery cell assembly provided by the embodiment of the present application.

[0024] Figure 9 A sectional view of the battery cell provided by the embodiment of the present application.

[0025] The components in the drawings are identified as follows:

[0026] 1 battery cell assembly; 2 first functional layer; 3 second functional layer; 11 positive electrode sheet; 12 negative electrode sheet; 13 separator; 131 first corner portion; 132 second corner portion; 101 first side surface; 102 second side surface; 103 first surface; 104 second surface; 111 body portion; 112 tab portion; 121 first gap; 122 second gap; 4 insulating film adhesive; 5 insulating film; 6 adhesive tape; Y first direction; Z second direction; X third direction. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without any creative work fall within the scope of protection of the present application.

[0028] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and 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. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0029] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between 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 according to the specific circumstances.

[0030] 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 being 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 being 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.

[0031] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplifying the present application, the components and arrangements of the specific examples are described in the following. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to the same reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, which in itself does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0032] As shown in Figures 1 to 3 The conventional battery cell generally includes a positive plate 11, a negative plate 12, a separator 13, an insulating film adhesive 4, an insulating film 5, a side support plate (not shown), a tape 6, etc. The positive plate 11 and the negative plate 12 are used to provide chemical substances for electrochemical reaction. The separator 13 is mainly used to isolate the positive plate 11 and the negative plate 12 to ensure the normal progress of the electrochemical reaction. It should be noted that the outermost separator 13 can also meet the insulation needs of the inside of the shell and the battery assembly. The insulating film adhesive 4 is mainly used to fix the insulating film 5 to wrap the body part of the battery assembly 1. The side support plate is mainly used to support the side of the battery assembly 1 to avoid damage to the positive plate 11 or the negative plate 12 when the battery assembly is placed. The tape 6 is mainly used to fix the relative position of the multiple layers of the separator 13, the positive plate 11 and the negative plate 12 in the battery assembly 1 to ensure that the reaction area does not deform. It can be understood that the thicker the thickness of the battery assembly 1, the worse the fixing effect of the tape 6 on each layer of the plate. Since the insulating film 5 and the tape 6, etc. cannot provide external energy and occupy a certain volume space, this not only increases the complexity of the structure of the battery cell, but also reduces the energy density of the battery cell. Moreover, the battery assembly 1 needs to be processed by multiple rounds of packaging before it is put into the shell, which also greatly reduces the production speed of the battery assembly. When the battery assembly 1 is put into the shell (i.e. arranged inside the shell), the binding force of the separator to the positive plate 11 and the negative plate 12 will be significantly reduced after the electrolyte infiltrates the battery assembly 1. When the outside of the battery cell is impacted in a certain direction, the positive plate and the negative plate inside will be dislocated, which may cause problems such as lithium precipitation of the negative electrode.

[0033] Since the long-term cycling of the battery assembly will cause the consumption of the electrolyte, a large amount of electrolyte will be injected during the design of the battery cell to ensure the cycle life of the battery. Therefore, after the positive plate, the negative plate and the separator in the battery assembly are infiltrated by the electrolyte, there is still some free electrolyte in the shell. However, since the insulating film is usually a non-porous material, when the electrolyte in the battery assembly is consumed, it is difficult for the free electrolyte inside the shell to pass through the insulating film to supplement the electrode assembly.

[0034] To solve the above problems, the embodiment of the present application provides a battery monomer, which comprises an electrode assembly, a first functional layer and a second functional layer. The electrode assembly comprises a Z-shaped wound electrode tab and a separator. The electrode assembly has two oppositely arranged side surfaces in a first direction, and the first direction is the width direction of the electrode assembly. The first functional layer is wrapped around the two side surfaces. The second functional layer fills the gap between the first functional layer, the electrode tab and the separator. The hardness of the first functional layer is less than the hardness of the second functional layer. Therefore, the second functional layer fills the gap between the first functional layer, the electrode tab and the separator to fix the relative positions of the multiple layers of the separator, the positive electrode tab and the negative electrode tab in the electrode assembly, to enhance the adhesion between the electrode tab and the separator, to avoid dislocation of the electrode tab, and to ensure that the reaction area does not deform. The first functional layer has insulation and support functions, and can directly replace the side support plate and the insulation film, thereby simplifying the production steps from battery monomer molding to assembly and speeding up the production efficiency. The following will be described in detail.

[0035] As shown in Figures 4 to 9 , the battery monomer comprises an electrode assembly 1, a first functional layer 2 and a second functional layer 3.

[0036] As shown in Figures 4 to 5 , the electrode assembly 1 has a first direction Y, a second direction Z and a third direction X intersecting with each other. The first direction Y is the width direction of the electrode assembly 1, the second direction Z is the stacking direction or the thickness direction of the electrode assembly 1, and the third direction X is the length direction of the electrode assembly 1.

[0037] As shown in Figures 4 to 9 , the electrode assembly 1 comprises a separator 13 and an electrode tab arranged in layers. The electrode assembly 1 has two oppositely arranged side surfaces in the first direction Y. The first functional layer 2 is wrapped around the two side surfaces. The second functional layer 3 fills the gap between the first functional layer 2, the electrode tab and the separator 13. Therefore, when the electrode assembly 1 is arranged in the shell (not shown in the figure), the first functional layer 2 and the second functional layer 3 have the functions of fixing, supporting and insulating the electrode assembly, and the liquid retention effect, thereby improving the energy density, structural reliability, cycle performance and production efficiency of the battery monomer.

[0038] The hardness of the first functional layer 2 is less than the hardness of the second functional layer 3. In this way, the second functional layer 3 can prevent the edge burr from piercing the separator 13 or the electrode tab from falling off, and the electrode assembly 1 can prevent the electrode tab from being damaged when it is put into the shell. After being put into the shell, the first functional layer 2 can ensure the close fit between the electrode assembly 1 and the shell, and reduce the shaking of the electrode assembly 1 in the shell.

[0039] As shown in Figure 8As shown, the pole pieces include positive pole pieces 11 and negative pole pieces 12, and the plurality of positive pole pieces 11 and the plurality of negative pole pieces 12 are alternately and laminatedly arranged. The separator 13 is arranged between the positive pole pieces 11 and the negative pole pieces 12 to insulate the positive pole pieces 11 and the negative pole pieces 12.

[0040] The separator 13 is a complete film, and the positive pole pieces 11 and the negative pole pieces 12 are alternately and sequentially wrapped by the separator 13 through bending the separator 13, so as to achieve the insulation effect between the two pole pieces.

[0041] As shown in FIG. 1, the battery cell assembly 1 has a first side 101 and a second side 102 opposite to each other in the first direction Y. The first side 101 and the second side 102 are respectively wrapped by the two first functional layers 2. Figure 5 and Figure 8 As shown, the battery cell assembly 1 has a first face 103 and a second face 104 opposite to each other in the second direction Z. On the first face 103 and the second face 104, the surface of the pole pieces is wrapped by the separator 13, which realizes the insulation effect of the two surfaces of the battery cell assembly 1 in the second direction Z.

[0042] As shown in FIG. 1, the battery cell assembly 1 has a first side 101 and a second side 102 opposite to each other in the first direction Y. The first side 101 and the second side 102 are respectively wrapped by the two first functional layers 2. Figure 8 As shown in FIG. 1, the battery cell assembly 1 has a first side 101 and a second side 102 opposite to each other in the first direction Y. The first side 101 and the second side 102 are respectively wrapped by the two first functional layers 2.

[0043] Figure 8 As shown in FIG. 1, the battery cell assembly 1 has a first side 101 and a second side 102 opposite to each other in the first direction Y. The first side 101 and the second side 102 are respectively wrapped by the two first functional layers 2.

[0044] Further, as shown in FIG. 1, the separator 13 includes a plurality of first corner portions 131 and a plurality of second corner portions 132. The first corner portions 131 are located on the first side 101 and wrap the first side of the negative pole pieces 12 in the first direction Y. The second corner portions 132 are located on the second side 102 and wrap the first side of the positive pole pieces 11 in the first direction Y. Wherein, between the two first corner portions 131 adjacent to the same positive pole piece 11 on the first side 101, the first gap 121 is formed. Between the two second corner portions 132 adjacent to the same negative pole piece 12 on the second side 102, the second gap 122 is formed. Figure 8 As shown in FIG. 1, the battery cell assembly 1 has a first side 101 and a second side 102 opposite to each other in the first direction Y. The first side 101 and the second side 102 are respectively wrapped by the two first functional layers 2.

[0045] Figures 8 to 9 ​​As shown, the second functional layer 3 fills the first gap 121 and the second gap 122 to fix the relative positions of the multilayer separator 13, positive electrode 11 and negative electrode 12 in the cell assembly 1, thereby enhancing the adhesion between the electrode and the separator 13, preventing the electrode from misaligning, and ensuring that the reaction area does not deform. The first functional layer 2 can provide elastic support for the two sides of the cell assembly 1. Therefore, when the cell assembly 1 is installed in the casing, the first functional layer 2 is squeezed and installed into the casing. After installation, the first functional layer 2 can replace the side support plate to support the cell assembly 1, so that the battery cell assembly 1 is protected from collisions, short circuits and other faults with the battery casing (not shown) during transportation and use, thereby improving the safety performance of the battery.

[0046] like Figures 8 to 9 As shown, by placing the first functional layer 2 and the second functional layer 3 on two sides of the cell assembly 1 in the first direction Y, when the cell assembly 1 is assembled inside the casing and the electrolyte is applied, the binding force of the separator 13 on the positive electrode 11 and the negative electrode 12 will be significantly improved. When the battery cell is subjected to an impact in a certain direction, the presence of the first functional layer 2 and the second functional layer 3 can not only enhance the adhesion between the electrode and the separator 13 to prevent the electrode from misaligning, but also replace the side support plate to prevent the cell assembly 1 from colliding with the battery casing and short-circuiting, thus avoiding safety risks. At the same time, these two functional layers can also ensure that lithium ions can be successfully inserted into the lithium-ion battery during charging, avoiding lithium plating, thereby improving battery performance and cycle life.

[0047] like Figure 9 As shown, in one embodiment, the first functional layer 2 extends and partially covers the first surface 103 and the second surface 104, which can increase the adhesion between the electrode and the separator 13 and effectively control the peeling between the first functional layer 2 and the cell assembly 1, and prevent the ends of the first functional layer 2 from lifting.

[0048] Furthermore, such as Figure 9 As shown, the second functional layer 3 is also disposed between the first surface 103 and the first functional layer 2, and between the second surface 104 and the first functional layer 2. It can be understood that the second functional layer 3 is disposed between the first surface 103 and the first functional layer 2, and between the second surface 104 and the first functional layer 2.

[0049] The first functional layer 2 is made of organic materials, while the second functional layer 3 is made of a mixture of inorganic and organic materials.

[0050] Inorganic materials include one of the following: silicon dioxide, aluminum oxide, molecular sieves, and Si / Al ceramics. Organic materials include one of the following: polypropylene, polyethylene, aramid, polyimide, polyetheretherketone, polyetherketone, and ethyl acetate.

[0051] Because the second functional layer 3 is made of a mixture of inorganic and organic materials, while the first functional layer 2 is made of organic materials, the hardness of the first functional layer 2 is less than that of the second functional layer 3. Therefore, the second functional layer 3 can prevent edge burrs from puncturing the separator 13 or causing electrode material to fall out. The compression of the first functional layer 2 is greater than that of the second functional layer 3, which prevents electrode damage when the cell assembly 1 is installed in the casing. After installation, the first functional layer 2 ensures a tight fit between the cell assembly 1 and the casing, reducing the shaking of the cell assembly 1 within the casing.

[0052] like Figures 8 to 9 As shown, in one embodiment, both the first functional layer 2 and the second functional layer 3 have porosity, allowing free electrolyte within the casing to wet the cell assembly 1 even when electrolyte is consumed due to prolonged cycling of the cell assembly 1. Furthermore, the abundant pores and large specific surface area in the first and second functional layers 2 and 3 significantly increase the electrolyte capacity within the cell assembly 1. Additionally, the insulation capacity of the cured first functional layer 2 is greater than that of a traditional insulating film, and its hardness is greater than that of the side support plate and far greater than that of the separator 13, preventing the positive electrode 11 and negative electrode 12 from being punctured by edge burrs. Moreover, the first functional layer 2 serves both insulating and supporting functions and can directly replace the side support plate and insulating film, simplifying the production steps from cell molding to assembly, accelerating production efficiency, and reducing the cost of tape, side support plate, and insulating film.

[0053] A battery cell is the smallest energy unit of a battery unit or battery. A battery unit or battery includes multiple battery cells, a large surface defined by the width and length edges of the battery cell, a small surface defined by the width and height edges of the battery cell, and an end face defined by the length and width edges of the battery cell. The first surface 103 and the second surface 104 mentioned above are the large surfaces of the battery cell, and the first side surface 101 and the second side surface 102 are the small surfaces of the battery cell.

[0054] like Figures 8 to 9As shown, the width of the negative tab 12 in the first direction Y is greater than the width of the positive tab 11 in the first direction Y. Since the increase in the width of the negative tab 12 means an increase in the mass of the negative active material, the total capacity of the battery will also increase, which can provide more ability to store and release electric charges, thereby prolonging the use time of the battery. The increase in the width of the negative tab 12 can also provide more electrode surface area, increasing the contact area between the electrode and the electrolyte, which helps to improve the reaction rate and charge transfer efficiency of the battery, thereby improving the power performance of the battery. The increase in the width of the negative tab 12 can also reduce the current density inside the battery, dispersing the flow path of the current, which helps to reduce the accumulation of heat and the occurrence of local electrochemical reactions inside the battery, improving the stability and safety of the battery.

[0055] As shown in the drawings, Figures 5 to 6 In one embodiment, the cell assembly 1 includes a body part 111 and two tab parts 112, one of the two tab parts 112 is connected to one end of the body part 111 along the third direction X, and the other of the two tab parts 112 is connected to the other end of the body part 111 along the third direction X.

[0056] Specifically, the body part 111 is a Z-shaped winding structure formed by winding the tab and the separator 13. The two tab parts 112 are positive and negative tab parts, the positive tab part includes a plurality of positive tabs, and the negative tab part includes a plurality of negative tabs. The positive and negative tabs are mainly connected to the external circuit to meet the inflow and outflow of electrons in the cell assembly 1.

[0057] As shown in the drawings, Figures 8 to 9 The battery cell provided by the embodiments of the present application is provided with the first functional layer 2 and the second functional layer 3 on the two sides of the cell assembly 1 in the width direction. The second functional layer 3 fills the gap between the first functional layer 2, the tab and the separator 13, so as to fix the relative positions of the multiple separators 13, the positive tab 11 and the negative tab 12 in the cell assembly 1, to enhance the adhesion between the tab and the separator 13, to avoid the tab from being dislocated, and to ensure that the reaction area does not deform. The first functional layer 2 has the functions of insulation and support, and can directly replace the side supporting plate and the insulating film, so as to simplify the production steps from molding to assembling of the battery cell and to speed up the production efficiency. Moreover, since the first functional layer 2 and the second functional layer 3 both have porosity, the storage space of the electrolyte in the shell is increased, and the migration difficulty of the free electrolyte in the shell to the cell assembly 1 is also reduced.

[0058] In general, the first functional layer 2 and the second functional layer 3 have the functions of fixing, supporting and insulating the electrode assembly and the liquid preservation effect, so as to improve the energy density, structural reliability, cycle performance and production efficiency of the battery cell.

[0059] The application further provides a battery pack, comprising a box body and a plurality of battery cells arranged in the box body. The battery pack serves as a power supply for a power consumption device. The power consumption device can be a mobile phone, a portable device, a notebook computer, an electric vehicle, an electric automobile, a ship, a spacecraft, an electric toy and an electric tool, etc. For example, the spacecraft includes an airplane, a rocket, a space shuttle and a spaceship, etc.; the electric toy includes a stationary or mobile electric toy, such as a game machine, an electric automobile toy, an electric ship toy and an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator and an electric planer, etc.

[0060] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0061] The battery cell and the battery pack provided by the embodiments of the application are described in detail above, and the principle and implementation manner of the application are described by applying specific examples. The above description of the embodiments is only used to help understand the technical solutions of the application and the core idea thereof; a person of ordinary skill in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some technical features can be replaced equivalently; and the modification or replacement does not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A battery cell, characterized by, The battery cell comprises: an electrode assembly comprising electrode pieces and separators arranged in layers, the electrode assembly having two opposite sides in a first direction, the first direction being a width direction of the electrode assembly; a first functional layer covering the two sides; a second functional layer filling gaps between the first functional layer, the electrode pieces and the separators; wherein the first functional layer has a smaller hardness than the second functional layer.

2. The battery cell of claim 1, wherein: the electrode pieces comprise positive electrode pieces and negative electrode pieces, a plurality of the positive electrode pieces and a plurality of the negative electrode pieces being arranged in layers alternately; and the separators are arranged between the positive electrode pieces and the negative electrode pieces to insulate the positive electrode pieces and the negative electrode pieces; the two sides are a first side and a second side respectively; and the gaps comprise first gaps and second gaps. between the first side, the first gaps are formed between two separators adjacent to the same positive electrode piece; and between the second side, the second gaps are formed between two separators adjacent to the same negative electrode piece. The second functional layer fills the first gaps and the second gaps and is located at opposite sides of the two first functional layers covering the two sides.

3. The battery cell of claim 2, wherein: the separators comprise a plurality of first corner portions and a plurality of second corner portions, the first corner portions being located at the first side and covering a first side of the negative electrode piece in the first direction, and the second corner portions being located at the second side and covering a first side of the positive electrode piece in the first direction; between the first side, the first gaps are formed between two first corner portions adjacent to the same positive electrode piece; and between the second side, the second gaps are formed between two second corner portions adjacent to the same negative electrode piece.

4. The battery cell of any one of claims 1-3, wherein: the electrode assembly has a first face and a second face opposite to each other in a second direction, the second direction being a layering direction of the electrode assembly; and the first functional layer extends and partially covers the first face and the second face.

5. The battery cell of claim 4, wherein: the second functional layer is further arranged between the first face and the first functional layer and between the second face and the first functional layer.

6. The battery cell of any one of claims 1-3, wherein: the first functional layer is made of an organic material, and the second functional layer is made of a mixture of an inorganic material and an organic material.

7. The battery cell of any one of claims 1-3, wherein: the first functional layer has a larger compression amount than the second functional layer.

8. The battery cell of any one of claims 1-3, wherein: the first functional layer and the second functional layer both have porosity.

9. The battery cell of any one of claims 1-3, wherein: The electric core assembly comprises a body part and two tab parts, one of the two tab parts is connected with one end of the body part along a third direction, the other of the two tab parts is connected with the other end of the body part along the third direction, and the third direction is the length direction of the electric core assembly.

10. The battery cell of any one of claims 1-3, wherein, Comprise: A shell, the electric core assembly is arranged in the shell.

Images