Battery cell, manufacturing method thereof and electric equipment

Abstract

The embodiment of the invention provides a battery cell, a manufacturing method thereof and electric equipment. The battery cell comprises a shell, an electrode assembly and filler. The electrode assembly comprises a first electrode assembly and a second electrode assembly, the first electrode assembly and the second electrode assembly are stacked in the first direction, in the second direction, the length of the second electrode assembly is larger than that of the first electrode assembly, the second electrode assembly is provided with a first surface facing the first electrode assembly, and when observed in the first direction, the length of the first surface is larger than that of the second surface. The second electrode assembly is provided with an overlapping area overlapped with the first electrode assembly and a non-overlapping area not overlapped with the first electrode assembly, and the side wall, close to the non-overlapping area, of the first electrode assembly in the second direction and the first surface of the non-overlapping area form a first step; the shell forms a second step corresponding to the first step, and an accommodating space is formed between the first step and the second step; the second direction is perpendicular to the first direction; the filler is arranged in the containing space. According to the technical scheme, the safety and reliability of the battery cell can be improved.

Description

Technical Field

[0001] The present application relates to the field of battery cell technology, and more specifically, to a battery cell and a manufacturing method thereof, and electrical equipment. Background Art

[0002] In recent years, with the rapid development of new energy technologies, batteries have been widely used in electronic equipment, electric vehicles, electric two-wheelers, power tools and other electrical equipment.

[0003] As the application scenarios of battery cells increase, the shape of the battery cells also changes to meet different setting environments. In the same battery cell, multiple electrode assemblies of different sizes are set up so that two adjacent electrode assemblies form steps. However, at the combined junction between electrode assemblies of different sizes, pressure is applied externally, resulting in a poor electrode interface in this area. There may be a risk of black spots and metal ion precipitation during the cycle, resulting in reduced safety and reliability of the battery cell. Summary of the invention

[0004] The present application provides a battery cell and a manufacturing method thereof, and electrical equipment, which can improve the safety and reliability of the battery cell.

[0005] This application is achieved through the following technical solutions:

[0006] In the first aspect, the embodiment of the present application provides a battery cell, which includes a shell, an electrode assembly and a filler. The electrode assembly is contained in the shell, and the electrode assembly includes a first electrode assembly and a second electrode assembly, which are stacked along a first direction, and along a second direction, the length of the second electrode assembly is greater than the length of the first electrode assembly, and the second electrode assembly has a first surface facing the first electrode assembly, and when viewed along the first direction, the second electrode assembly has an overlapping area overlapping with the first electrode assembly, and a non-overlapping area that does not overlap with the first electrode assembly, and the side wall of the first electrode assembly close to the non-overlapping area in the second direction and the first surface of the non-overlapping area form a first step; the shell forms a second step corresponding to the first step, and a holding space is formed between the first step and the second step; the second direction is perpendicular to the first direction; and the filler is arranged in the holding space.

[0007] According to the battery cell of the embodiment of the present application, the first electrode assembly and the second electrode assembly form a first step, and the outer shell forms a second step corresponding to the first step, so as to facilitate the assembly of the electrode assembly and the outer shell, so that the battery cell has a stepped structure, so that the battery cell can adapt to different application scenarios. During the assembly process of the electrode assembly and the outer shell, a storage space is formed between the first step of the electrode assembly and the second step of the outer shell, and the electrolyte can be contained in the storage space, which is beneficial to the charge and discharge cycle of the battery cell. By arranging the filler in the storage space, the filler fills the storage space or the filler cooperates with the electrolyte in the storage space, the pressure in the battery cell manufacturing process can be effectively transferred to the area corresponding to the second electrode assembly and the storage space, which is beneficial to increase the force consistency of the area and other areas of the second electrode assembly, so that the bonding force between the negative electrode plate and the corresponding diaphragm is higher, and the risk of metal ions precipitating on the surface of the negative electrode plate is reduced, so that the battery cell has higher safety and reliability.

[0008] In one or more of the above optional embodiments, the filler comprises an organic material.

[0009] Organic materials have high toughness and can provide physical support, which helps to effectively and evenly transmit pressure.

[0010] In one or more of the above optional embodiments, the filler includes a mixture of organic material and inorganic material, and the mass proportion of the inorganic material in the mixture is 1% to 95%.

[0011] Inorganic materials can improve the hardness of the filler. At the same time, inorganic materials have a certain ability to absorb or transmit electrolyte, effectively improving the electrolyte wettability of the electrode assembly and the corresponding area of ​​the accommodation space. The mixture of organic and inorganic materials not only has high mechanical strength and toughness, but also has the function of absorbing or transmitting electrolyte, which facilitates the effective transmission of the pressure of the battery cell process to the area corresponding to the second electrode assembly and the accommodation space, ensuring the force consistency of this area and other areas of the second electrode assembly, which is conducive to improving the electrolyte wettability of the electrode assembly and the corresponding part of the accommodation space, and further effectively improving the interface at the junction of the second electrode assembly and the first electrode assembly.

[0012] If the mass proportion of inorganic materials in the mixture is too small, the mixture will have poor effect in absorbing or transmitting electrolyte, and the electrolyte wettability of the electrode assembly and the corresponding area of ​​the accommodating space will be poor; if the mass proportion of inorganic materials in the mixture is too large, the mass proportion of organic materials in the mixture will be too small, the toughness of the mixture will be weak, and it will not be conducive to uniform pressure transmission.

[0013] By setting the mass proportion of inorganic materials in the mixture to greater than or equal to 1% and less than or equal to 95%, on the one hand, the effect of the mixture in absorbing and transmitting electrolyte can be improved, and the electrolyte wettability of the electrode assembly and the corresponding area of ​​the accommodating space can be improved; on the other hand, the mixture has higher toughness, which is conducive to uniform pressure transmission.

[0014] In one or more of the above optional embodiments, the mass proportion of the inorganic material in the mixture is 5% to 90%.

[0015] The mass proportion of inorganic materials in the mixture is greater than or equal to 5%, which further improves the effect of the mixture on absorbing and transmitting electrolyte and improves the electrolyte wettability of the electrode assembly and the corresponding area of ​​the accommodating space. The mass proportion of inorganic materials in the mixture is less than or equal to 90%, which further makes the mixture have higher toughness and is conducive to uniform pressure transmission.

[0016] In one or more of the above optional embodiments, the inorganic material includes at least one of aluminum oxide, boehmite, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, zinc oxide, barium sulfate, silicon carbide, titanium dioxide, barium titanate, calcium carbonate, silicon oxide, calcium titanate, lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, lithium nitride or lithium lanthanum titanate.

[0017] The inorganic material is selected from at least one of the above materials, has high strength and hardness, good high temperature resistance, and high chemical stability. When combined with the organic material, the composite of the organic material and the inorganic material has high strength and toughness, good high temperature resistance, and high chemical stability.

[0018] In one or more of the above optional embodiments, the organic material includes at least one of silicone, polyurethane, epoxy resin, polyethylene, polypropylene, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, polyester or polyamide.

[0019] The organic material is selected from at least one of the above materials and has good flexibility and ductility.

[0020] In one or more of the above optional embodiments, the outer shell includes a first wall and a second wall arranged opposite to each other along a first direction, the first wall has a main body wall and a step wall, along the second direction, the step wall is located at at least one end of the main body wall, the step wall is recessed relative to the main body wall in the direction of the second wall, and the step wall and the main body wall are connected by a connecting wall to form a second step; the second electrode assembly is arranged between the step wall and the second wall, the first electrode assembly is arranged between the main body wall and the second electrode assembly, and the first electrode assembly, the second electrode assembly, the connecting wall and the main body wall form a accommodating space.

[0021] The first wall can be formed into a second step by stamping or injection molding, which is convenient for processing and manufacturing, and the first wall has a high overall strength. The second electrode assembly is arranged between the step wall and the second wall, and the first electrode assembly is arranged between the main body wall and the second electrode assembly, so that the outer shell and the electrode assembly contour match, the outer shell is convenient for protecting the electrode assembly, and the risk of damage to the electrode assembly is reduced.

[0022] In one or more optional embodiments above, along the first direction, the second electrode assembly has a first region overlapping with the projection of the accommodating space, the projection area of ​​the first region is S1, the projection area of ​​the second electrode assembly is S2, and 0.001≤S1 / S2≤0.2 is satisfied.

[0023] If the ratio of the projected area of ​​the first region to the projected area of ​​the second electrode assembly is too small, the volume of the accommodating space is too small, which is not conducive to the assembly of the electrode assembly and the outer shell, and the pressure transmission effect between the filler and the first region is poor; if the ratio of the projected area of ​​the first region to the projected area of ​​the second electrode assembly is too large, the volume of the accommodating space is too large, the utilization rate of the internal space of the outer shell is low, and the energy density of the battery cell is low.

[0024] The first region corresponds to the boundary region between the second electrode assembly and the first electrode assembly. When observed along the first direction, the filler and the first region at least partially overlap. By setting the ratio of the projected area of ​​the first region to the projected area of ​​the second electrode assembly to be greater than or equal to 0.001 and less than or equal to 0.2, on the one hand, it is convenient to assemble the electrode assembly and the outer shell, and to transfer pressure between the filler and the first region, which is beneficial to the greater bonding force between the negative electrode sheet and the diaphragm in the first region, thereby reducing the risk of metal ion precipitation on the surface of the negative electrode sheet in the first region. On the other hand, the internal space utilization rate of the outer shell is high, and the battery cell has a higher energy density.

[0025] In one or more optional embodiments above, along the first direction, the projection area of ​​the first electrode assembly is S3, and the projection area of ​​the second electrode assembly is S2, satisfying 0.2≤S3 / S2≤0.9.

[0026] If the ratio of the projected area of ​​the first electrode assembly to the projected area of ​​the second electrode assembly is too large, the difference between the size of the first electrode assembly and the size of the second electrode assembly is too small, and the processing and manufacturing are difficult; if the ratio of the projected area of ​​the first electrode assembly to the projected area of ​​the second electrode assembly is too small, the difference between the size of the first electrode assembly and the size of the second electrode assembly is too large, which is not conducive to achieving the design goal of increasing the energy density of the battery cell by flexible use of space, and if the difference between the size of the first electrode assembly and the size of the second electrode assembly is too large, the area of ​​the junction area between the first electrode assembly and the second electrode assembly, that is, the first area, will be larger, and the problem of uneven force will be more serious.

[0027] By setting the ratio of the projected area of ​​the first electrode assembly to the projected area of ​​the second electrode assembly to be greater than or equal to 0.2 and less than or equal to 0.9, on the one hand, the processing and manufacturing difficulty is lower; on the other hand, the battery cell has a higher energy density, reducing the uneven force in the interface area between the first electrode assembly and the second electrode assembly.

[0028] In one or more of the above optional embodiments, the filler is connected to the second electrode assembly and / or the housing.

[0029] The filler is connected to the second electrode assembly and / or the outer shell, which is beneficial to the transmission of pressure and facilitates ensuring the force consistency between the electrode assembly and the corresponding area of ​​the accommodating space and other areas of the second electrode assembly.

[0030] In one or more of the above optional embodiments, along the first direction, the minimum distance between the filler and the shell is H, satisfying 0≤H≤5mm.

[0031] The shell has a certain elasticity, and by setting the distance between the filler and the shell along the first direction to be greater than or equal to 0 and less than or equal to 5 mm, the pressure on the shell is facilitated to be transmitted to the first area along the first direction.

[0032] In one or more of the above optional embodiments, 0.4 mm ≤ H ≤ 3.5 mm.

[0033] When H≥0.4 mm, it is easy to assemble the electrode assembly and the shell, and can adapt to processing errors; when H≤3.5 mm, the distance between the shell and the filler is small, which is further conducive to transferring the pressure on the shell to the first area.

[0034] In a second aspect, an embodiment of the present application further provides an electrical device, which includes a battery cell provided according to any of the above embodiments.

[0035] In a third aspect, an embodiment of the present application further provides a method for manufacturing a battery cell, which is used to manufacture a battery cell according to any of the above embodiments. The method for manufacturing a battery cell includes:

[0036] providing an electrode assembly;

[0037] Provide a housing;

[0038] The slurry is coated on the second step of the shell, or the slurry is coated on the first step of the electrode assembly, and the electrode assembly is accommodated in the shell so that the slurry is located in the accommodation space between the first step and the second step, and the slurry solidifies to form a filler.

[0039] The battery cell manufactured by the battery cell manufacturing method has high safety and reliability.

[0040] In one or more of the above optional embodiments, the initial construction viscosity of the slurry is greater than or equal to 30,000 Pa·s.

[0041] By setting the initial construction viscosity of the slurry to be greater than or equal to 30,000 Pa·s, the fluidity of the slurry is poor, thereby reducing the risk of the slurry flowing into the electrode assembly during the battery cell preparation process and affecting the battery cell capacity.

[0042] In one or more optional embodiments above, the slurry is coated on the second step of the shell, or the slurry is coated on the first step of the electrode assembly, the electrode assembly is accommodated in the shell so that the slurry is located in the accommodation space between the first step and the second step, and the slurry solidifies to form a filler, including: heating and melting the slurry, coating the melted slurry on the second step or the first step, accommodating the electrode assembly in the shell, and the slurry solidifies to form a filler after cooling.

[0043] The slurry is melted by hot melting, so that the organic material in the slurry melts, which is beneficial for the connection between the slurry and the shell or electrode assembly. After the temperature drops to room temperature, the organic material hardens again. Through the material hardening method, the filler is set in the accommodation space, and the filler has a higher hardness, which is beneficial for pressure transmission.

[0044] In one or more of the above optional embodiments, the heating temperature of the slurry is 50°C to 300°C.

[0045] If the heating temperature of the slurry is too low, the slurry is not fully melted, which is not conducive to the assembly of the slurry with the shell or electrode assembly; if the heating temperature of the slurry is too high, energy is wasted, and the slurry has high fluidity and is easy to flow into the interior of the electrode assembly.

[0046] By setting the heating temperature of the slurry to be greater than or equal to 50°C and less than or equal to 300°C, on the one hand, it can be adapted to the melting of a wider variety of materials and the slurry can be melted and coated on the casing or electrode assembly, which is beneficial to the preparation of the battery cell; on the other hand, it can save energy, and the fluidity of the slurry is poor, reducing the risk of flowing into the interior of the electrode assembly.

[0047] In one or more optional embodiments above, the slurry is coated on the second step of the outer shell, or the slurry is coated on the first step of the electrode assembly, the electrode assembly is accommodated in the outer shell so that the slurry is located in the accommodation space between the first step and the second step, and the slurry solidifies to form a filler, including: coating the slurry on the second step, or coating the slurry on the first step, accommodating the electrode assembly in the outer shell, and causing the slurry to undergo a chemical reaction and solidify to form a filler by heating the battery cell or by catalysis of the catalyst in the slurry.

[0048] The organic material in the slurry undergoes a chemical reaction under the action of high temperature or a catalyst and produces a cross-linked structure, which causes the slurry to harden and makes the filler have a higher hardness.

[0049] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0051] Figure 1 A three-dimensional diagram of a battery cell provided in some embodiments of the present application;

[0052] Figure 2 A three-dimensional diagram of an electrode assembly provided for some embodiments of the present application;

[0053] Figure 3 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0054] Figure 4 A schematic diagram of the partial structure of a battery cell provided in some embodiments of the present application.

[0055] Icon: 1000-battery cell; 1-shell; 11-second step; 12-first wall; 121-main body wall; 122-step wall; 123-connecting wall; 13-second wall; 14-third wall; 15-fourth wall; 16-fifth wall; 2-electrode assembly; 2a-first electrode assembly; 2b-second electrode assembly; 21-first surface; 22-first step; 23-first area; 24-second area; 25-third area; 3-filler; 4-accommodating space; X-third direction; Y-second direction; Z-first direction. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0057] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0058] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0059] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0060] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0061] The term "multiple" as used in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).

[0062] At present, judging from the development of the market situation, the application of battery cells is becoming more and more extensive. Battery cells are widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as in many fields such as electric tools, mobile phones, tablets, drones, energy storage equipment, etc. With the increase in the application scenarios of battery cells, in order to meet different setting environments, the shape of the battery cells has also changed. For example, the battery cell is stepped. In the same battery cell, multiple electrode assemblies of different sizes are set, so that two adjacent electrode assemblies form steps. For example, the first step is formed at the junction of the large and small electrode assemblies. Due to the large hardness of the outer shell, in order to assemble the electrode assembly with the outer shell, the outer shell forms a second step corresponding to the first step, so that the contour of the outer shell matches the contour of the electrode assembly. However, during the manufacturing process of the battery cell, pressure is applied to the battery cell. Due to the accommodation space between the first step and the second step, when the battery cell is subjected to the pressure of the pressing block, the pressure cannot directly act on the area where the second electrode assembly is located on the side of the first electrode assembly and corresponds to the accommodation space, resulting in uneven force in the area. In other words, external pressure can easily lead to uneven force at the combined interface between electrode assemblies of different sizes, which leads to weakened bonding between the negative electrode plate and the diaphragm in this area. During the charge and discharge cycle, black spots and metal ion precipitation may appear on the surface of the negative electrode plate in this area, resulting in low safety and reliability of the battery cell.

[0063] Based on the above considerations, in order to solve the problem of low safety and reliability of the battery cell due to the precipitation of black spots and metal ions at the combined interface between electrode assemblies of different sizes, the embodiment of the present application provides a battery cell, which includes a shell, an electrode assembly and a filler. The electrode assembly is accommodated in the shell, and the electrode assembly includes a first electrode assembly and a second electrode assembly. The first electrode assembly and the second electrode assembly are stacked along a first direction. Along the second direction, the length of the second electrode assembly is greater than the length of the first electrode assembly. The second electrode assembly has a first surface facing the first electrode assembly, and the side wall and the first surface of the first electrode assembly in the second direction form a first step; the shell forms a second step corresponding to the first step, and a holding space is formed between the first step and the second step; the second direction is perpendicular to the first direction; the filler is arranged in the holding space.

[0064] In such a battery cell, by arranging the filler in the accommodation space, the filler fills the accommodation space or the filler cooperates with the electrolyte in the accommodation space, the pressure in the battery cell manufacturing process can be effectively transferred to the area corresponding to the second electrode assembly and the accommodation space, which is beneficial to increase the force consistency between the area and other areas of the second electrode assembly, so that the bonding force between the negative electrode plate and the corresponding diaphragm is higher, and the risk of metallic lithium precipitation on the surface of the negative electrode plate is reduced, so that the battery cell has higher safety and reliability.

[0065] The battery cell disclosed in the embodiments of the present application can be used in, but not limited to, electric two-wheeled vehicles, electronic equipment, electric tools, drones, energy storage equipment and other electrical equipment. The battery cell disclosed in the present application can also be used as a power supply system for electrical equipment, which is conducive to improving the safety performance of the battery cell.

[0066] The present application provides an electric device using a battery cell as a power source, and the electric device may be, but is not limited to, electronic equipment, electric tools, electric vehicles, drones, and energy storage devices. Among them, electronic equipment may include mobile phones, tablets, laptops, etc., electric tools may include electric drills, electric saws, etc., and electric vehicles may include electric cars, electric motorcycles, electric bicycles, etc.

[0067] The structure of the battery cell provided in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0068] Please refer to Figures 1 to 4 , an embodiment of the present application provides a battery cell 1000 , which includes a housing 1 and an electrode assembly 2 .

[0069] The housing 1 has a space for accommodating the electrode assembly 2, and the electrode assembly 2 and the electrolyte are accommodated in the space. The housing 1 can be a hard shell, for example, the housing 1 can be a steel shell, an aluminum shell, a hard plastic shell, etc., and the battery cell 1000 is a hard shell battery cell.

[0070] The electrode assembly 2 includes a positive electrode sheet, a negative electrode sheet and a separator, and the separator is disposed between the positive electrode sheet and the negative electrode sheet to insulate and separate the positive electrode sheet and the negative electrode sheet, thereby reducing the risk of short circuit of the battery cell 1000. The material of the separator may include polypropylene or polyethylene.

[0071] The electrode assembly 2 is a laminated structure, in which the positive electrode sheet, the separator and the negative electrode sheet are laminated in a certain order.

[0072] Please refer to Figure 2 and Figure 3 The electrode assembly 2 includes a first electrode assembly 2a and a second electrode assembly 2b, and the first electrode assembly 2a and the second electrode assembly 2b are stacked along a first direction Z, and the first direction Z may be parallel to the thickness direction of the battery cell 1000. The first electrode assembly 2a includes a first positive electrode sheet, a first negative electrode sheet, and a first separator, and the first positive electrode sheet, the first separator, and the first negative electrode sheet are stacked along the first direction Z. The second electrode assembly 2b includes a second positive electrode sheet, a second negative electrode sheet, and a second separator, and the second positive electrode sheet, the second separator, and the second negative electrode sheet are stacked along the first direction Z.

[0073] Along the second direction Y, the length of the second electrode assembly 2b is greater than the length of the first electrode assembly 2a, and at least one end of the second electrode assembly 2b exceeds the first electrode assembly 2a. The second direction Y is perpendicular to the first direction Z, and the second direction Y can be parallel to the length direction of the battery cell 1000, or the second direction Y can be parallel to the width direction of the battery cell 1000.

[0074] Please refer to Figure 2 and Figure 3 , the second electrode assembly 2b has a first surface 21 facing the first electrode assembly 2a, and the first surface 21 is perpendicular to the first direction Z. Observed along the first direction Z, the second electrode assembly 2b has an overlapping area overlapping with the first electrode assembly 2a, and a non-overlapping area not overlapping with the first electrode assembly 2a, and the side wall of the first electrode assembly 2a close to the non-overlapping area and the first surface 21 of the non-overlapping area in the second direction Y form a first step 22. The housing 1 forms a second step 11 corresponding to the first step 22, and a receiving space 4 is formed between the first step 22 and the second step 11. The surface of the second step 11 facing the interior of the battery cell 1000, the first step 22, and other wall portions of the housing enclose the receiving space 4.

[0075] The side wall of the first electrode assembly 2a refers to the side wall formed by the edges of the plurality of anode pole pieces in the first electrode assembly 2a.

[0076] Please refer to Figure 1 The outer shell 1 is a hard shell, and the second step 11 is provided so that the contour of the outer shell 1 matches the contour of the electrode assembly 2 , so as to facilitate the assembly of the electrode assembly 2 and the outer shell 1 .

[0077] The battery cell 1000 further includes a filler 3, which is disposed in the accommodation space 4. Since the accommodation space 4 contains an electrolyte, the filler 3 is disposed in the accommodation space 4, and the filler 3 fills the accommodation space 4, or the filler 3 cooperates with the electrolyte, and the filler 3 can provide physical support, which can facilitate the transmission of pressure to the second electrode assembly 2b and the corresponding area of ​​the accommodation space 4.

[0078] According to the battery cell 1000 of the embodiment of the present application, the length of the second electrode assembly 2b along the second direction Y is greater than the length of the first electrode assembly 2a along the second direction Y, so that the second electrode assembly 2b and the first electrode assembly 2a form a step structure, and the contour of the shell 1 matches the contour of the electrode assembly 2, so that the battery cell 1000 can adapt to different application scenarios; during the assembly process of the electrode assembly 2 and the shell 1, a receiving space 4 is formed between the first step 22 of the electrode assembly 2 and the second step 11 of the shell 1, and the receiving space 4 can contain electrolyte, which is beneficial to the charge and discharge cycle of the battery cell 1000. By arranging the filler 3 in the receiving space 4, the filler 3 fills the receiving space 4 or the filler 3 cooperates with the electrolyte in the receiving space 4, the pressure in the manufacturing process of the battery cell 1000 can be effectively transmitted to the area corresponding to the second electrode assembly 2b and the receiving space 4, which is beneficial to increase the force consistency of the area and other areas of the second electrode assembly 2b, so that the bonding force between the negative electrode plate and the corresponding diaphragm is higher, and the risk of metal lithium precipitation on the surface of the negative electrode plate is reduced, so that the battery cell 1000 has higher safety and reliability.

[0079] In one or more of the above optional embodiments, the filler 3 includes an organic material.

[0080] Organic materials have high toughness and can provide physical support, which helps to effectively and evenly transmit pressure.

[0081] In one or more of the above optional embodiments, the filler 3 includes a mixture of organic material and inorganic material, and the mass proportion of the inorganic material in the mixture is 1% to 95%.

[0082] Inorganic materials can improve the hardness of the filler 3. At the same time, inorganic materials have a certain function of absorbing or transmitting electrolyte, which effectively improves the electrolyte wettability of the electrode assembly 2 and the corresponding area of ​​the accommodating space 4. The organic material and the inorganic material are mixed, and the filler 3 not only has high mechanical strength and toughness, but also has the function of absorbing or transmitting electrolyte, which facilitates the effective transmission of the pressure of the battery cell 1000 process to the area corresponding to the second electrode assembly 2b and the accommodating space 4, ensuring the force consistency of this area and other areas of the second electrode assembly 2b, which is conducive to improving the electrolyte wettability of the corresponding part of the electrode assembly 2 and the accommodating space 4, and further effectively improving the interface at the junction of the second electrode assembly 2b and the first electrode assembly 2a.

[0083] If the mass proportion of inorganic materials in the mixture is too small, the mixture will have poor effect in absorbing or transmitting electrolyte, and the electrolyte wettability of the electrode assembly 2 and the corresponding area of ​​the accommodating space 4 will be poor; if the mass proportion of inorganic materials in the mixture is too large, the mass proportion of organic materials in the mixture will be too small, the toughness of the mixture will be weak, and it will not be conducive to uniform pressure transmission.

[0084] By setting the mass proportion of inorganic materials in the mixture to greater than or equal to 1% and less than or equal to 95%, on the one hand, the effect of the mixture in absorbing and transmitting electrolyte can be improved, and the electrolyte wettability of the electrode assembly 2 and the corresponding area of ​​the accommodating space 4 can be improved; on the other hand, the mixture has higher toughness, which is conducive to uniform pressure transmission.

[0085] In one or more of the above optional embodiments, the mass proportion of the inorganic material in the mixture is 5% to 90%.

[0086] The mass proportion of the inorganic material in the mixture is greater than or equal to 5%, which further improves the effect of the mixture on absorbing and transmitting the electrolyte, and improves the electrolyte wettability of the electrode assembly 2 and the corresponding area of ​​the accommodating space 4. The mass proportion of the inorganic material in the mixture is less than or equal to 90%, which further makes the mixture have higher toughness and is conducive to uniform pressure transmission.

[0087] In one or more of the above optional embodiments, the inorganic material includes at least one of aluminum oxide, boehmite, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, zinc oxide, barium sulfate, silicon carbide, titanium dioxide, barium titanate, calcium carbonate, silicon oxide, calcium titanate, lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, lithium nitride or lithium lanthanum titanate.

[0088] In a mixture of an organic material and an inorganic material, the inorganic material may be selected from one of the above materials, or the inorganic material may be selected from a combination structure of two or more of the above materials.

[0089] The inorganic material is selected from at least one of the above materials, has high strength and hardness, good high temperature resistance, and high chemical stability. When combined with the organic material, the composite of the organic material and the inorganic material has high strength and toughness, good high temperature resistance, and high chemical stability.

[0090] In one or more of the above optional embodiments, the organic material includes at least one of silicone, polyurethane, epoxy resin, polyethylene, polypropylene, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, polyester or polyamide.

[0091] In a mixture of an organic material and an inorganic material, the organic material may be selected from one of the above materials, or the organic material may be selected from a combination structure of two or more of the above materials.

[0092] The organic material is selected from at least one of the above materials and has good flexibility and ductility.

[0093] In one or more of the above optional embodiments, the housing 1 includes a first wall 12 and a second wall 13 arranged relatively to each other along a first direction Z, the first wall 12 has a main wall 121 and a step wall 122, along the second direction Y, the step wall 122 is located at at least one end of the main wall 121, the step wall 122 is recessed relative to the main wall 121 toward the direction of the second wall 13, and the step wall 122 is connected to the main wall 121 by a connecting wall 123 to form a second step 11.

[0094] Please refer to Figure 1 The housing 1 may further include a third wall 14, a fourth wall 15 and two fifth walls 16, the third wall 14 and the fourth wall 15 are arranged opposite to each other along the second direction Y, the third wall 14 connects the main wall 121 and the second wall 13, the fourth wall 15 connects the step wall 122 and the second wall 13, and the two fifth walls 16 are arranged opposite to each other along the third direction X, one end of the fifth wall 16 is connected to the second wall 13, and the other end of the fifth wall 16 is connected to the main wall 121, the step wall 122 and the connecting wall 123. The third direction X, the second direction Y and the first direction Z are perpendicular to each other.

[0095] In some embodiments, the first wall 12 may be an integrally formed structure, for example, the step wall 122 is recessed relative to the main body wall 121 toward the second wall 13, and the housing 1 may be formed by stamping during the manufacturing process. Alternatively, the first wall 12 may be an integrally formed injection molded structure.

[0096] The first wall 12 can be formed into the second step 11 by stamping or injection molding, which is easy to process and manufacture, and the first wall 12 has a high overall strength.

[0097] The second electrode assembly 2b is disposed between the step wall 122 and the second wall 13 , and the first electrode assembly 2a is disposed between the main body wall 121 and the second electrode assembly 2b . The first electrode assembly 2a , the second electrode assembly 2b , the connecting wall 123 and the main body wall 121 form a receiving space 4 .

[0098] The first wall 12 and the second wall 13 are spaced apart along the first direction Z. After the electrode assembly 2 is assembled with the outer shell 1, along the first direction Z, the second electrode assembly 2b is arranged between the step wall 122 and the second wall 13, that is, the second electrode assembly 2b is located between the second wall 13 and the first wall 12; along the first direction Z, the first electrode assembly 2a is arranged between the main wall 121 and the second electrode assembly 2b.

[0099] The second electrode assembly 2b is arranged between the step wall 122 and the second wall 13, and the first electrode assembly 2a is arranged between the main wall 121 and the second electrode assembly 2b, so that the outer shell 1 matches the contour of the electrode assembly 2, the outer shell 1 protects the electrode assembly 2, and reduces the risk of damage to the electrode assembly 2.

[0100] In one or more optional embodiments above, along the first direction Z, the second electrode assembly 2b has a first region 23 overlapping with the projection of the accommodating space 4, the projection area of ​​the first region 23 is S1, and the projection area of ​​the second electrode assembly 2b is S2, satisfying 0.001≤S1 / S2≤0.2.

[0101] Taking the first direction Z as the projection direction, on the projection plane perpendicular to the first direction Z, the area of ​​the orthographic projection of the first region 23 is S1, and the area of ​​the orthographic projection of the second electrode assembly 2b is S2.

[0102] If the ratio of the projection area of ​​the first region 23 to the projection area of ​​the second electrode assembly 2b is too small, the volume of the accommodating space 4 is too small, which is not conducive to the assembly of the electrode assembly 2 and the outer shell 1, and the pressure transmission effect between the filler 3 and the first region 23 is poor; if the ratio of the projection area of ​​the first region 23 to the projection area of ​​the second electrode assembly 2b is too large, the volume of the accommodating space 4 is too large, the internal space utilization rate of the outer shell 1 is low, and the energy density of the battery cell 1000 is low.

[0103] The first region 23 corresponds to the boundary region between the second electrode assembly 2b and the first electrode assembly 2a. When observed along the first direction Z, the filler 3 and the first region 23 at least partially overlap. By setting the ratio of the projected area of ​​the first region 23 to the projected area of ​​the second electrode assembly 2b to be greater than or equal to 0.001 and less than or equal to 0.2, on the one hand, it is convenient to assemble the electrode assembly 2 and the outer shell 1, and to transfer pressure between the filler 3 and the first region 23, which is beneficial to the greater bonding force between the negative electrode sheet and the diaphragm in the first region 23, thereby reducing the risk of metallic lithium precipitation on the surface of the negative electrode sheet in the first region 23; on the other hand, the internal space utilization rate of the outer shell 1 is high, and the battery cell 1000 has a high energy density.

[0104] Illustratively, the ratio of the projected area of ​​the first region 23 to the projected area of ​​the second electrode assembly 2 b may be, but is not limited to, 0.001, 0.005, 0.01, 0.05, 0.1, 0.15, 0.2, or the like.

[0105] Exemplarily, 0.01≤S1 / S2≤0.15. S1 / S2≥0.01 further facilitates the assembly of the electrode assembly 2 and the housing 1, facilitates the pressure transmission between the filler 3 and the first region 23, facilitates the strong bonding between the negative electrode sheet and the diaphragm in the first region 23, and reduces the risk of metal lithium precipitation on the surface of the negative electrode sheet in the first region 23; S1 / S2≤0.15 further makes the internal space utilization of the housing 1 higher, and the battery cell 1000 has a higher energy density.

[0106] In some embodiments, along the second direction Y, the end of the first region 23 may exceed the accommodation space 4. For example, along the first direction Z, the first region 23 has a first overlapping region overlapping a portion of the first positive electrode tab, and a second overlapping region overlapping a portion of the step wall 122.

[0107] In some embodiments, please refer to Figure 4 The second electrode assembly 2b also includes a second region 24 and a third region 25. The second region 24, the first region 23 and the third region 25 are distributed along the second direction Y, and the first region 23 connects the second region 24 and the third region 25. Along the first direction Z, the projection of the second region 24 partially overlaps with the main wall 121, and the projection of the third region 25 at least partially overlaps with the step wall 122.

[0108] In one or more optional embodiments above, along the first direction Z, the projection area of ​​the first electrode assembly 2a is S3, and the projection area of ​​the second electrode assembly 2b is S2, satisfying 0.2≤S3 / S2≤0.9.

[0109] Taking the first direction Z as the projection direction, the area of ​​the orthographic projection of the first electrode assembly 2a is S3, and the area of ​​the orthographic projection of the second electrode assembly 2b is S2.

[0110] If the ratio of the projected area of ​​the first electrode assembly 2a to the projected area of ​​the second electrode assembly 2b is too large, the size of the first electrode assembly 2a and the size of the second electrode assembly 2b will be too small, and the processing and manufacturing difficulty will be high; if the ratio of the projected area of ​​the first electrode assembly 2a to the projected area of ​​the second electrode assembly 2b is too small, the size of the first electrode assembly 2a and the size of the second electrode assembly 2b will be too different, which is not conducive to achieving the design purpose of increasing the energy density of the battery cell 1000 by flexible use of space, and if the size of the first electrode assembly 2a and the size of the second electrode assembly 2b are too different, the area of ​​the boundary area of ​​the first electrode assembly 2a and the second electrode assembly 2b, that is, the first area 23, will be larger, and the problem of uneven force will be more serious.

[0111] By setting the ratio of the projected area of ​​the first electrode assembly 2a to the projected area of ​​the second electrode assembly 2b to be greater than or equal to 0.2 and less than or equal to 0.9, on the one hand, the processing and manufacturing difficulty is lower; on the other hand, the battery cell 1000 has a higher energy density, reducing the uneven force in the interface area between the first electrode assembly 2a and the second electrode assembly 2b.

[0112] Illustratively, the ratio of the projected area of ​​the first electrode assembly 2a to the projected area of ​​the second electrode assembly 2b may be, but is not limited to, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, etc.

[0113] Exemplarily, 0.3≤S3 / S2≤0.8. S3 / S2≥0.3 further makes the processing and manufacturing difficulty lower; S3 / S2≤0.8 further makes the battery cell 1000 have a higher energy density.

[0114] In one or more of the above optional embodiments, the filler 3 is connected to the second electrode assembly 2 b and / or the housing 1 .

[0115] In some embodiments, the filler 3 can be connected to the second electrode assembly 2b in the accommodating space 4, that is, the filler 3 is connected to the first region 23 of the second electrode assembly 2b; in the manufacturing process of the battery cell 1000, when the second electrode assembly 2b is subjected to a force toward the first electrode assembly 2a, the filler 3 can provide physical support, facilitate pressure transfer, and improve the force consistency between the first region 23 and other regions of the second electrode assembly 2b.

[0116] In some embodiments, the filler 3 can be connected to the outer shell 1 in the accommodating space 4. In the manufacturing process of the battery cell 1000, when the second electrode assembly 2b is subjected to a force toward the first electrode assembly 2a, the filler 3 can provide physical support, facilitate pressure transfer, and ensure the consistency of force between the first area 23 and other areas of the second electrode assembly 2b.

[0117] In some embodiments, in the accommodating space 4, the filler 3 can be connected to the second electrode assembly 2b and the outer shell 1, and the filler 3 is supported between the first region 23 and the outer shell 1. In the manufacturing process of the battery cell 1000, when the second electrode assembly 2b is subjected to a force toward the first electrode assembly 2a, the filler 3 can provide physical support, facilitate pressure transfer, and ensure the consistency of force between the first region 23 and other regions of the second electrode assembly 2b.

[0118] By connecting the filler 3 with the second electrode assembly 2b and / or the housing 1, pressure transmission is facilitated, and force consistency between the electrode assembly 2 and the corresponding area of ​​the accommodating space 4 and other areas of the second electrode assembly 2b is ensured.

[0119] In one or more optional embodiments above, the housing 1 is a hard housing, and the battery cell 1000 is a hard housing battery cell. For example, the housing 1 can be a steel housing, an aluminum housing, a hard plastic housing, or the like.

[0120] In one or more of the above optional embodiments, along the first direction Z, the minimum distance between the filler 3 and the shell 1 is H, satisfying 0≤H≤5mm.

[0121] When the outer shell 1 is a hard shell, if the distance between the filler 3 and the outer shell 1 along the first direction Z is too large, the pressure on the outer shell 1 cannot be transmitted to the first area 23 .

[0122] The shell 1 has a certain elasticity. By setting the distance between the filler 3 and the shell 1 along the first direction Z to be greater than or equal to 0 and less than or equal to 5 mm, the pressure on the shell 1 is facilitated to be transmitted to the first area 23 along the first direction.

[0123] Exemplarily, H can be, but is not limited to, 0, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.7 mm, 4 mm, 4.2 mm, 4.5 mm, 4.7 mm, 5 mm, etc.

[0124] In one or more of the above optional embodiments, 0.4 mm ≤ H ≤ 3.5 mm.

[0125] When H≥0.4 mm, it is easy to assemble the electrode assembly 2 and the shell 1 and can adapt to processing errors; when H≤3.5 mm, the distance between the shell 1 and the filler 3 is small, which is further conducive to transferring the pressure on the shell 1 to the first area 23.

[0126] Based on the above-mentioned battery cell 1000, an embodiment of the present application further provides an electrical device, which includes the battery cell 1000 provided according to any of the above-mentioned embodiments.

[0127] The battery cell 1000 described above has high safety and reliability, so that the electrical equipment formed by the battery cell 1000 has high safety and reliability.

[0128] The embodiment of the present application further provides a method for manufacturing a battery cell 1000, which is used to manufacture the battery cell 1000 provided according to any of the above embodiments. The method for manufacturing the battery cell 1000 includes:

[0129] S100, providing an electrode assembly 2;

[0130] S200, providing a housing 1;

[0131] S300, coating the slurry on the second step 11 of the outer shell 1, or coating the slurry on the first step 22 of the electrode assembly 2, accommodating the electrode assembly 2 in the outer shell 1 so that the slurry is located in the accommodating space 4 between the first step 22 and the second step 11, and the slurry solidifies to form a filler 3.

[0132] The battery cell 1000 manufactured by the above-mentioned method for manufacturing the battery cell 1000 has high safety and reliability.

[0133] In one or more of the above optional embodiments, the initial construction viscosity of the slurry is greater than or equal to 30,000 Pa·s.

[0134] The initial construction viscosity of the slurry refers to the viscosity of the slurry before being applied to the housing 1 or the electrode assembly 2. The slurry initially has a certain viscosity, which facilitates the connection between the slurry and the housing 1 or the electrode assembly 2 and facilitates the assembly of the battery cell 1000.

[0135] By setting the initial construction viscosity of the slurry to be greater than or equal to 30,000 Pa·s, the fluidity of the slurry is poor, thereby reducing the risk of the slurry flowing into the electrode assembly 2 during the preparation of the battery cell 1000 and affecting the capacity of the battery cell 1000 .

[0136] In one or more optional embodiments above, in step "S300, applying slurry on the second step 11 of the outer shell 1, or applying slurry on the first step 22 of the electrode assembly 2, accommodating the electrode assembly 2 in the outer shell 1 so that the slurry is located in the accommodating space 4 between the first step 22 and the second step 11, and the slurry solidifies to form a filler 3", includes: heating the slurry to melt, applying the melted slurry on the second step 11 or the first step 22, accommodating the electrode assembly 2 in the outer shell 1, and solidifying the slurry to form a filler 3 after cooling.

[0137] Before the electrode assembly 2 is assembled with the shell 1, the slurry is first applied to the surface of the first step 22 of the shell 1 that encloses the accommodation space 4, or the slurry is applied to the second step 11 of the electrode assembly 2, and then the electrode assembly 2 is accommodated in the shell 1. The slurry temperature is reduced to room temperature and then hardened to form a filler 3.

[0138] In some embodiments, after the slurry is melted, the slurry may have good viscosity, so that the bonding force between the slurry and the housing 1 or the electrode assembly 2 is high, which is beneficial to the connection between the slurry and the housing 1 or the electrode assembly 2.

[0139] The slurry is melted by hot melting, so that the organic material in the slurry is melted, which is beneficial for the connection between the slurry and the shell 1 or the electrode assembly 2. After the temperature drops to room temperature, the organic material hardens again. Through the material hardening method, the filler 3 is set in the accommodating space 4, and the filler 3 has a higher hardness, which is beneficial for pressure transmission.

[0140] In one or more of the above optional embodiments, the heating temperature of the slurry is 50°C to 300°C.

[0141] If the heating temperature of the slurry is too low, the slurry is not fully melted, which is not conducive to the assembly of the slurry with the shell 1 or the electrode assembly 2; if the heating temperature of the slurry is too high, energy is wasted, and the slurry has a high fluidity and is easy to flow into the interior of the electrode assembly 2.

[0142] By setting the heating temperature of the slurry to be greater than or equal to 50°C and less than or equal to 300°C, on the one hand, it can be adapted to the melting of a wider variety of materials, and the slurry can be melted and coated on the casing 1 or the electrode assembly 2, which is beneficial to the preparation of the battery cell 1000; on the other hand, it can save energy, and the fluidity of the slurry is poor, reducing the risk of flowing into the interior of the electrode assembly 2.

[0143] Illustratively, the heating temperature of the slurry may be, but is not limited to, 50°C, 80°C, 100°C, 120°C, 160°C, 200°C, 240°C, 260°C, 300°C, etc.

[0144] Illustratively, the heating temperature of the slurry may be 80°C to 260°C.

[0145] In one or more optional embodiments above, the slurry is coated on the second step 11 of the outer shell 1, or the slurry is coated on the first step 22 of the electrode assembly 2, the electrode assembly 2 is accommodated in the outer shell 1, so that the slurry is located in the accommodation space 4 between the first step 22 and the second step 11, and the slurry solidifies to form the filler 3, including: coating the slurry on the second step 11, or coating the slurry on the first step 22, accommodating the electrode assembly 2 in the outer shell 1, and causing the slurry to undergo a chemical reaction and solidify to form the filler 3 by heating the battery cell 1000 or by catalysis of the catalyst in the slurry.

[0146] The heating of the battery cell 1000 can be completed in the drying process, that is, when the electrode assembly 2 is accommodated in the housing 1, the slurry may not be solidified. When the battery cell 1000 is transported to the drying process, the slurry undergoes a chemical reaction and solidifies to form the filler 3 during the drying process of the battery cell 1000.

[0147] In some embodiments, a catalyst may be mixed in the slurry, and the slurry undergoes a chemical reaction and solidifies to form the filler 3 .

[0148] The organic material in the slurry undergoes a chemical reaction under the action of high temperature or a catalyst and generates a cross-linked structure, which causes the slurry to harden, so that the filler 3 has a higher hardness.

[0149] The features and performance of the battery cell 1000 of the present application are further described in detail below in conjunction with the embodiments.

[0150] The battery cells 1000 in each embodiment and comparative example are prepared and tested according to the following directions.

[0151] 1. Preparation of battery cell 1000

[0152] 1.1 Preparation of positive electrode

[0153] The active material lithium cobalt oxide, the conductive agent (conductive carbon (super P)), and the binder (polyvinylidene fluoride (PVDF)) are fully stirred and mixed in an N-methylpyrrolidone solvent system at a weight ratio of 94:3:3, and then coated on an aluminum foil, dried, and cold pressed to obtain a positive electrode sheet.

[0154] 1.2 Preparation of negative electrode

[0155] Active material artificial graphite, conductive agent (conductive carbon (super P)), adhesive (styrene-butadiene rubber (SBR)), thickener (sodium carbon methyl cellulose (CMC)) are fully stirred and mixed in a deionized water solvent system at a weight ratio of 97:1:1.5:0.5, and then coated on copper foil, dried, and cold pressed to obtain a negative electrode sheet.

[0156] 1.3 Preparation of electrode assembly 2

[0157] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, with the separator being located between the positive electrode sheet and the negative electrode sheet to play an isolating role, to obtain a first electrode assembly 2a and a second electrode assembly 2b, and the first electrode assembly 2a and the second electrode assembly 2b are hot-pressed and composited to form a stepped electrode assembly 2 structure.

[0158] 1.4 battery cells 1000 assembly

[0159] The electrode assembly 2 is placed in a steel shell, and the containing space 4 between the steel shell and the electrode assembly 2 is filled with a filler 3, and then an electrolyte is injected and packaged, and the final battery cell 1000 is manufactured after chemical formation.

[0160] 2. Test methods

[0161] 2.1 Test on the proportion of inorganic materials

[0162] The battery cell 1000 is disassembled, the filler 3 of the organic material and the inorganic material is taken out, and is placed in a muffle furnace at 500° C. and heated for 12 hours. The weight before and after heating is weighed and recorded as M0 and M1 respectively. The proportion of inorganic material is calculated as follows: (M1 / M0)*100%.

[0163] 2.2 Viscosity test of filler 3

[0164] For chemical hardening materials: take 500g of filler 3 of organic material and inorganic material, use a rotational viscometer to measure and verify the viscosity of filler 3, take the average value of 3 tests, and record it as the final viscosity value;

[0165] For physically hardened materials: 500 g of filler 3 of organic and inorganic materials is taken, heated to 100° C., and the viscosity of filler 3 is measured and verified using a rotational viscometer. The average value of three tests is taken and recorded as the final viscosity value.

[0166] 2.3 Battery Cell 1000 Interface Test

[0167] Take 1000 finished battery cells after formation, disassemble them after full charging at 0.5C, observe the black spots and lithium precipitation on the interface of the negative electrode, and take photos to record them.

[0168] 3. Comparative Examples and Examples

[0169] Comparative Example 1

[0170] The first electrode assembly 2a and the second electrode assembly 2b were prepared according to the above method, and after hot pressing and compounding, liquid injection and chemical formation were performed. The chemical formation temperature was 75° C., the pressure was 1.0 MPa, and the chemical formation time was 60 min to obtain a finished battery cell 1000.

[0171] Example 1

[0172] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 0.5%, and the viscosity of the filler 3 was 29000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0173] Example 2

[0174] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 1%, and the viscosity of the filler 3 was 31000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0175] Example 3

[0176] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 5%, and the viscosity of the filler 3 was 31000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0177] Example 4

[0178] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 40%, and the viscosity of the filler 3 was 30000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0179] Example 5

[0180] The first electrode assembly 2a and the second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 50%, and the viscosity of the filler 3 was 54000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0181] Example 6

[0182] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 70%, and the viscosity of the filler 3 was 154000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0183] Example 7

[0184] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 90%, and the viscosity of the filler 3 was 200000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0185] Example 8

[0186] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 95%, and the viscosity of the filler 3 was 210000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0187] Example 9

[0188] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 96%, and the viscosity of the filler 3 was 220000 mPa·s. Then, liquid injection and formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0189] Example 10

[0190] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and boehmite was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of boehmite in the filler 3 was 50%, and the viscosity of the filler 3 was 52000 mPa·s. Then, liquid injection and formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0191] Embodiment 11

[0192] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of silicone and lithium aluminum titanium phosphate was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of lithium aluminum titanium phosphate in the filler 3 was 50%, and the viscosity of the filler 3 was 55000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0193] Example 12

[0194] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of epoxy resin and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 50%, and the viscosity of the filler 3 was 56000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0195] Example 13

[0196] A first electrode assembly 2a and a second electrode assembly 2b were prepared according to the above method. After hot pressing and compounding, a filler 3 of ethylene-vinyl acetate copolymer and aluminum oxide was coated in the accommodating space 4 generated by the steel shell and the compounded electrode assembly 2. The mass proportion of aluminum oxide in the filler 3 was 50%, and the viscosity of the filler 3 was 52000 mPa·s. Then, liquid injection and chemical formation were carried out. The formation temperature was 75°C, the pressure was 1.0 MPa, and the formation time was 60 min to obtain a finished battery cell 1000.

[0197] The battery cells 1000 of the above comparative examples and embodiments were tested by the above test method to obtain the results in Table 1.

[0198] Table 1

[0199]

[0200]

[0201]

[0202] It can be seen from Table 1 that in Comparative Example 1, the filler 3 is not provided in the accommodating space 4, so that the first region 23 and other regions of the second electrode assembly 2b are subjected to uneven force, resulting in a low adhesion between the negative electrode plate of the first region 23 and the corresponding diaphragm. After the battery cell 1000 is charged and cycled, metal ions are easily precipitated on the surface of the negative electrode plate of the second electrode assembly 2b, resulting in obvious black spots or purple spots on the surface of the negative electrode plate of the second electrode assembly 2b.

[0203] However, in Examples 1-13, by arranging the filler 3 in the accommodating space 4, the filler 3 can transmit pressure to ensure the force consistency between the first area 23 and other areas of the second electrode assembly 2b, so that the area of ​​black spots or purple spots on the surface of the negative electrode plate of the second electrode assembly 2b is smaller, and the black spots or purple spots are significantly improved, so that the battery cell 1000 has higher safety performance.

[0204] Furthermore, in Examples 2-8 and 10-13, the mass proportion of inorganic materials in the mixture is greater than or equal to 1% and less than or equal to 95%, the filler 3 has high toughness and hardness, and can effectively and evenly conduct pressure. At the same time, the filler 3 has a certain function of absorbing or transmitting electrolyte, which can effectively improve the electrolyte wettability in the area where the second electrode assembly 2b overlaps with the accommodating space 4, further effectively improve the interface at the junction of the second electrode assembly 2b and the first electrode assembly 2a, and significantly improve the black spots or purple spots on the negative electrode plate of the second electrode assembly 2b.

[0205] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: shell; An electrode assembly, the electrode assembly is accommodated in the shell, the electrode assembly comprises a first electrode assembly and a second electrode assembly, the first electrode assembly and the second electrode assembly are stacked along a first direction, along a second direction, the length of the second electrode assembly is greater than the length of the first electrode assembly, the second electrode assembly has a first surface facing the first electrode assembly, and when viewed along the first direction, the second electrode assembly has an overlapping region overlapping with the first electrode assembly, and a non-overlapping region not overlapping with the first electrode assembly, a side wall of the first electrode assembly close to the non-overlapping region in the second direction and the first surface of the non-overlapping region form a first step; the shell forms a second step corresponding to the first step, and a holding space is formed between the first step and the second step; The second direction is perpendicular to the first direction; The filler is arranged in the accommodating space.

2. The battery cell according to claim 1, characterized in that: The filler includes an organic material.

3. The battery cell according to claim 2, characterized in that: The filler comprises a mixture of organic material and inorganic material, and the mass proportion of the inorganic material in the mixture is 1% to 95%.

4. The battery cell according to claim 3, characterized in that: The inorganic material accounts for 5% to 90% by weight of the mixture.

5. The battery cell according to claim 3, characterized in that: The inorganic material includes at least one of aluminum oxide, boehmite, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, zinc oxide, barium sulfate, silicon carbide, titanium dioxide, barium titanate, calcium carbonate, silicon oxide, calcium titanate, lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, lithium nitride or lithium lanthanum titanate.

6. The battery cell according to claim 2, characterized in that: The organic material includes at least one of silicone, polyurethane, epoxy resin, polyethylene, polypropylene, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, polyester or polyamide.

7. The battery cell according to claim 1, characterized in that: The housing comprises a first wall and a second wall arranged opposite to each other along the first direction, the first wall comprises a main body wall and a step wall, the step wall is located at at least one end of the main body wall along the second direction, the step wall is recessed relative to the main body wall toward the direction of the second wall, and the step wall is connected to the main body wall via a connecting wall to form the second step; The second electrode assembly is disposed between the step wall and the second wall, the first electrode assembly is disposed between the main body wall and the second electrode assembly, and the first electrode assembly, the second electrode assembly, the connecting wall and the main body wall enclose the accommodating space.

8. The battery cell according to claim 7, characterized in that: Along the first direction, the second electrode assembly has a first region overlapping with a projection of the accommodation space, the projection area of ​​the first region is S1, and the projection area of ​​the second electrode assembly is S2, satisfying 0.001≤S1 / S2≤0.

2.

9. The battery cell according to claim 1, characterized in that: Along the first direction, the projection area of ​​the first electrode assembly is S3, and the projection area of ​​the second electrode assembly is S2, satisfying 0.2≤S3 / S2≤0.

9.

10. The battery cell according to claim 1, characterized in that: The filler is connected to the second electrode assembly and / or the housing.

11. The battery cell according to claim 1, characterized in that: Along the first direction, the minimum distance between the filler and the shell is H, satisfying 0≤H≤5mm.

12. The battery cell according to claim 11, characterized in that: 0.4mm≤H≤3.5mm.

13. An electrical equipment, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 12.

14. A method for manufacturing a battery cell, used for manufacturing the battery cell according to any one of claims 1 to 12, characterized in that: The manufacturing method of the battery core comprises: Providing the electrode assembly; providing the housing; The slurry is applied on the second step of the shell, or the slurry is applied on the first step of the electrode assembly, and the electrode assembly is accommodated in the shell so that the slurry is located in the accommodation space between the first step and the second step, and the slurry solidifies to form the filler.

15. The method for manufacturing a battery cell according to claim 14, characterized in that: The initial construction viscosity of the slurry is greater than or equal to 30000 Pa·s.

16. The method for manufacturing a battery cell according to claim 14, characterized in that: The method comprises: coating the slurry on the second step of the housing, or coating the slurry on the first step of the electrode assembly, accommodating the electrode assembly in the housing so that the slurry is located in the accommodation space between the first step and the second step, and solidifying the slurry to form the filler, comprising: The slurry is heated and melted, and the melted slurry is applied to the second step or the first step, and the electrode assembly is accommodated in the shell. The slurry is cooled and solidified to form the filler.

17. The method for manufacturing a battery cell according to claim 16, characterized in that: The heating temperature of the slurry is 50°C to 300°C.

18. The method for manufacturing a battery cell according to claim 14, characterized in that: The method comprises: coating the slurry on the second step of the housing, or coating the slurry on the first step of the electrode assembly, accommodating the electrode assembly in the housing so that the slurry is located in the accommodation space between the first step and the second step, and solidifying the slurry to form the filler, comprising: The slurry is coated on the second step, or the slurry is coated on the first step, the electrode assembly is accommodated in the housing, and the slurry undergoes a chemical reaction and solidifies to form a filler by heating the battery core or catalyzing the catalyst in the slurry.

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