Battery monomer, battery and electric device

Abstract

The utility model discloses a single battery, a battery and a power utilization device, the single battery comprises N1 electrode assemblies, a shell and a pressure relief component, positive pole pieces, negative pole pieces and separators are stacked to form a straight area, the number of layers of the positive pole pieces stacked in the straight area of the electrode assemblies is N2, the straight area has an outer surface perpendicular to a first direction, the surface area of the outer surface is S, and the surface area of the outer surface is S; n1 * N2 is greater than or equal to 50, S is greater than or equal to 8000 mm < 2 >, the shell comprises a first wall part, the thickness size of the first wall part in the second direction is H, H is less than or equal to 2.5 mm, the pressure relief component is arranged on the first wall part, the pressure relief component is provided with a first indented groove, the first indented groove comprises a first groove section extending along a linear track, the size of the groove bottom surface of the first groove section in the first direction is A, the minimum residual thickness of the first groove section is D1, and D is greater than or equal to 0.5 mm. 0.3 mm < = A < = 0.8 mm, and 0.1 mm < = D1 < = 0.28 mm. Therefore, the risk of fatigue cracking can be reduced to a certain extent, and meanwhile, when thermal runaway occurs to the single battery, the pressure relief component can be exploded in time, so that the reliability of the single battery is improved.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry. Electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of the sustainable development of the automotive industry. For electric vehicles, battery technology is a key factor in their development.

[0003] In order to increase the energy density of battery cells, more layers of electrodes are contained in the shell of the battery cells, and the thickness of the shell wall is reduced as much as possible to increase the space for accommodating the electrodes. However, during the charging and discharging process of the battery cells, the electrode assembly will expand and deform, causing the shell accommodating the electrode assembly to bulge and deform as well. The design with more electrodes will generate greater expansion force, and the thinning of the wall makes the shell more susceptible to deformation, which in turn makes the pressure relief component provided on the shell prone to damage, reducing the reliability of the battery cells. Utility Model Content

[0004] In view of the above problems, the present application provides a battery cell, a battery and an electrical device, which can alleviate the problem of damage to the pressure relief component during battery use.

[0005] In a first aspect, the present application provides a battery cell, comprising: N1 electrode assemblies, each of the electrode assemblies comprising at least one positive electrode sheet, at least one negative electrode sheet, and at least one separator, the positive electrode sheet, the negative electrode sheet, and the separator being stacked to form a flat region, at least a portion of the positive electrode sheet, at least a portion of the negative electrode sheet, and at least a portion of the separator being stacked along a first direction in the flat region; the number of layers of the positive electrode sheets stacked in the flat region of each electrode assembly is N2, the flat region having an outer surface perpendicular to the first direction, the area of ​​the outer surface being S, N1 ≥ 1, N2 ≥ 1, N1*N2 ≥ 50, and S ≥ 8000 mm 2; A shell for accommodating N1 electrode assemblies, the shell comprising a first wall portion, the first wall portion being located on one side of the electrode assembly in a second direction, the second direction being the thickness direction of the first wall portion and being perpendicular to the first direction, the thickness dimension of the first wall portion in the second direction being H, H≤2.5mm; a pressure relief component being arranged on the first wall portion, the pressure relief component being provided with a first notch groove, the pressure relief component being configured to be able to split along at least a portion of the first notch groove when the battery cell is pressure-relieved, the first notch groove comprising a first groove segment extending along a straight trajectory, the length direction of the first groove segment being perpendicular to the first direction, the size of the groove bottom surface of the first groove segment in the first direction being A, the minimum residual thickness of the first groove segment being D1, satisfying: 0.3mm≤A≤0.8mm, 0.1mm≤D1≤0.28mm.

[0006] In the technical solution of the embodiment of the present application, by limiting the bottom width and the minimum residual thickness of the first groove segment within the above-mentioned range, the damage, cracking, and leakage of the weak area corresponding to the first groove segment due to the expansion and deformation of the electrode assembly can be reduced, thereby reducing the risk of fatigue cracking to a certain extent. At the same time, when thermal runaway occurs in the battery cell, the pressure relief component can explode in time to release the internal air pressure of the battery cell, thereby improving the reliability of the battery cell.

[0007] In some embodiments, the following conditions are satisfied: 0.4mm≤A≤0.7mm, 0.12mm≤D1≤0.25mm. In the above technical solution, the ability of the first groove section to withstand deformation can be further increased, and the deformation of the pressure relief component at the first groove section when the electrode assembly expands can be reduced. This can, to a certain extent, avoid the risk of fatigue cracking of the pressure relief component during long-term charge and discharge use of the battery cell, reduce the probability of leakage caused by the pressure relief component being pulled and damaged, and improve the reliability of the battery cell. At the same time, it can prevent the pressure relief component from having an excessively high burst pressure, and reduce the probability of the pressure relief component failing to explode in time and easily exploding at other locations when thermal runaway occurs in the battery cell, further improving the reliability of the battery cell.

[0008] In some embodiments, the pressure relief component includes a main body and a pressure relief portion, the main body being connected to the first wall portion, the thickness of the pressure relief portion being less than that of the main body, the first notch groove being provided in the pressure relief portion, and the thickness dimension of the pressure relief portion in the second direction being D2, satisfying the following conditions: 0.182mm≤D2≤0.4mm, preferably, 0.2mm≤D2≤0.3mm. In the above technical solution, the stress concentration at the first groove section is reduced, and the risk of fatigue cracking of the pressure relief component is avoided to a certain extent. At the same time, the pressure relief component can be prevented from having an excessively high burst pressure. When thermal runaway occurs in a battery cell, the probability that the pressure relief component fails to explode in time and is easily exploded at other locations is reduced, thereby improving the reliability of the battery cell.

[0009] In some embodiments, the pressure relief component is provided with a pressure relief portion, the first notched groove is provided in the pressure relief portion, and the thickness dimension of the pressure relief portion in the second direction is D2, satisfying the following: 0.55≤D1 / D2≤0.85. In the above technical solution, the stress concentration at the first groove section is reduced, which, to a certain extent, avoids the risk of fatigue cracking of the pressure relief component. At the same time, it can prevent the pressure relief component from having an excessively high burst pressure. In the event of thermal runaway of the battery cell, the probability of the pressure relief component failing to explode in time and being easily exploded at other locations is reduced, thereby improving the reliability of the battery cell.

[0010] In some embodiments, the first wall portion has a pressure relief hole, the pressure relief component is installed in the pressure relief hole, and the area of ​​the pressure relief hole projected along the second direction is W, 400mm 2 ≤W≤1400mm 2 , preferably 600mm 2 ≤W≤1200mm 2 In the above technical solution, the risk of fatigue cracking of the pressure relief component can be avoided to a certain extent. At the same time, when thermal runaway occurs in the battery cell, the probability of the pressure relief component failing to explode in time and easily exploding at other locations is reduced, thereby improving the reliability of the battery cell.

[0011] In some embodiments, the first wall portion has a pressure relief hole, and the pressure relief component is mounted in the pressure relief hole. The pressure relief hole has a dimension B in the first direction and a dimension L in a third direction, the third direction being perpendicular to the first and second directions, and the following relationship is satisfied: 1.5 ≤ L / B ≤ 5, preferably 2 ≤ L / B ≤ 4. This technical solution can, to a certain extent, mitigate the risk of fatigue cracking in the pressure relief component, while reducing manufacturing difficulty and improving manufacturing yield.

[0012] In some embodiments, the width of the first wall along the first direction is D3, satisfying the following conditions: 0.008 ≤ A / D3 ≤ 0.019, and 20 mm ≤ D3 ≤ 80 mm. This technical solution reduces the risk of damage, cracking, and leakage in the weak area corresponding to the first slot segment due to electrode assembly expansion, reducing the risk of fatigue cracking to a certain extent. Furthermore, when thermal runaway occurs in a battery cell, the pressure relief component can promptly rupture and release the internal pressure of the battery cell, thereby improving the reliability of the battery cell.

[0013] In some embodiments, the housing includes two second walls connected to the first wall, the two second walls being located on either side of the electrode assembly along the first direction, the distance between the inner surfaces of the two second walls being P2. When the battery cells are fully discharged, the total thickness of the N1 electrode assemblies in the first direction is P1, satisfying the following: P1 / P2 ≥ 92%. This technical solution can improve the energy density of the battery cells.

[0014] In some embodiments, the first score groove defines at least one predetermined pressure relief area, and the pressure relief component is provided with a second score groove, which is configured to guide at least a portion of the predetermined pressure relief area to flip over, thereby opening at least a portion of the predetermined pressure relief area. In the above technical solution, by providing the second score groove, the predetermined pressure relief area can be guided to open, thereby improving the opening effect of the predetermined pressure relief area of ​​the pressure relief component, and further increasing the pressure relief rate of the battery cell when thermal runaway occurs, thereby reducing the risk of fire, explosion, connection failure, etc. caused by untimely pressure relief of the battery cell, which is conducive to improving the reliability of the battery cell.

[0015] In some embodiments, the residual thickness of the second score groove is greater than the residual thickness of the first score groove. In the above technical solution, the strength of the pressure relief component in the area where the first score groove is provided can be made weaker than the strength of the area where the second score groove is provided, so that the pressure relief component can preferentially rupture along the first score groove to achieve rapid opening of the predetermined pressure relief area.

[0016] In some embodiments, the width of the second scoring groove in a direction perpendicular to the extension direction is greater than the width of the first scoring groove in a direction perpendicular to the extension direction. In the above technical solution, the manufacturing and forming of the second scoring groove can be facilitated.

[0017] In some embodiments, the first notch groove further includes two second groove segments, the two second groove segments are arranged opposite each other, the two ends of the first groove segment are respectively connected to one end of the two second groove segments, and the other ends of the two second groove segments are connected to the two ends of the second notch groove, and the first groove segment, the two second groove segments, and the second notch groove together define a predetermined pressure relief area. In the above technical solution, the first groove segment, the second notch groove, and the two second groove segments are connected to form an annular structure, so that the intersection of the first groove segment and the second groove segment is weaker and easier to crack and open the predetermined pressure relief area for pressure relief; at the same time, this structure is conducive to increasing the opening area of ​​the predetermined pressure relief area, increasing the pressure relief area of ​​the battery cell, and improving the pressure relief rate of the battery cell.

[0018] In some embodiments, the second notched groove is arranged parallel to and opposite to the first groove section, and the second groove section extends along a straight line and / or an arc. In the above technical solution, the second groove section extends along a straight line, which can reduce the difficulty of forming the second groove section. The second groove section is an arc-shaped groove, which makes it easier for the pressure relief component to break along the second groove section when the battery cell is depressurized, thereby achieving a faster opening of the predetermined pressure relief area.

[0019] In some embodiments, the housing includes: a shell and an end cap, wherein at least one side of the shell has an opening, the end cap is connected to the shell and is used to close the opening, and the first wall portion is formed on the shell. In the above technical solution, by arranging the pressure relief component on the shell, the structure of the end cap can be simplified, and the distance between the pressure relief component and the main body of the electrode assembly can be shortened. This can further shorten the path of the discharge medium flowing to the pressure relief component during pressure relief, shorten the time it takes for the discharge medium to reach the pressure relief component, improve the timeliness of pressure relief of the battery cell, and thus effectively improve the reliability of the battery cell.

[0020] In some embodiments, the housing has openings on opposite sides, and the two end caps are used to close the openings on the corresponding sides. In the above technical solution, by providing two openings on the housing, it is possible to facilitate the manufacturing and molding of the housing, and at the same time facilitate the extension of the electrode tabs from both ends of the electrode assembly, thereby facilitating the separation of the two electrical connections and reducing the risk of short circuits in the battery cells.

[0021] In some embodiments, the shell has an opening at at least one end along the second direction, and the shell includes a second wall portion, and the second wall portion is welded to the end cover to form a first connecting portion; wherein, the second wall portion includes a first area and a second area arranged along the second direction, the thickness of the first area is greater than the thickness of the second area, and the first area is located between the first connecting portion and the second area.

[0022] In the above technical solution, the thickness of the first zone is greater than that of the second zone, and the first zone is located between the first connecting portion and the second zone, so that the first zone with a larger thickness is closer to the first connecting portion than the second zone. The first zone strengthens the area of ​​the first wall near the first connecting portion, reducing the risk of fatigue cracking of the area of ​​the second wall near the first connecting portion due to expansion of the electrode assembly, thereby improving the service life of the battery cell.

[0023] In some embodiments, along the third direction, the size of the first area is larger than the size of the positive electrode sheet and / or the size of the negative electrode sheet, and the first direction, the second direction and the third direction are perpendicular to each other. The size of the first area along the third direction is made larger, so that the strength of the first wall in more areas along the third direction is enhanced, and the risk of fatigue cracking in the area of ​​the first wall near the first connection portion is further reduced. In some embodiments, the first wall portion is used to support the electrode assembly and is located below the electrode assembly. In the above technical solution, the pressure relief component can be provided at the bottom of the battery cell, and the bottom of the battery cell can be provided with an exhaust channel, and the exhaust channel can be connected to the pressure relief component to discharge high-temperature and high-pressure flue gas through the pressure relief component at the bottom into the exhaust channel when thermal runaway occurs in the battery cell, and then discharged to the outside.

[0024] In some embodiments, the battery cell further includes two electrical connectors, each of which is provided on the end cap and has opposite polarities and is electrically connected to the electrode assembly. The end cap is provided with an extraction hole, and the electrical connector includes a terminal body, a first stopper, and a second stopper. The terminal body connects the first stopper and the second stopper, and the terminal body is inserted through the extraction hole. Along the first direction, the first stopper is located on the side of the end cap facing away from the electrode assembly, and the second stopper is located on the side of the end cap facing the electrode assembly. This type of electrical connector can be riveted to the end cap, which reduces installation effort and offers improved cost-effectiveness.

[0025] In some embodiments, the electrode assembly is a laminated structure, comprising a plurality of positive electrode sheets and a plurality of negative electrode sheets, wherein the plurality of positive electrode sheets and the plurality of negative electrode sheets are stacked along the first direction. The laminated electrode assembly is more compact and has greater resistance to extrusion.

[0026] In some embodiments, the number of the negative electrode sheets is greater than the number of the positive electrode sheets, and one positive electrode sheet is disposed between two adjacent negative electrode sheets.

[0027] In some embodiments, each of the negative electrode sheets is provided with a negative electrode tab; and / or each of the positive electrode sheets is provided with a positive electrode tab.

[0028] In some embodiments, the material of the first wall portion includes aluminum alloy. In the above technical solution, the housing has the advantages of being lightweight, safe, easy to process and having good corrosion resistance.

[0029] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector along the thickness direction of the negative electrode sheet and containing a negative electrode active material. The negative electrode active material includes a silicon-based material, and the silicon content of the silicon-based material is 0.3% to 10.0% by weight, based on the total weight of the negative electrode active material. In the above technical solution, by keeping the silicon content of the silicon-based material within the above range, the capacity of the negative electrode active material can be increased, thereby improving the energy density of the battery cell. This increased energy density prevents excessive expansion force, thereby reducing the risk of damage, cracking, and leakage in weak areas caused by expansion and deformation of the electrode assembly.

[0030] In some embodiments, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector along the thickness direction of the negative electrode plate and containing a negative electrode active material, and the discharge capacity per unit area of ​​the negative electrode film layer is 2.0 mAh / cm 2 Up to 5.0 mAh / cm 2 When the discharge capacity per unit area of ​​the negative electrode film is within the above range, there are sufficient sites for lithium embedding in the negative electrode film, which can reduce the risk of lithium plating. This is also conducive to rapid charging, and the expansion force is not too large, reducing the risk of damage, cracking, and leakage in weak areas caused by expansion and deformation of the electrode assembly.

[0031] In some embodiments, the thickness of the negative electrode film layer is 9 μm≤T1≤75 μm.

[0032] In a second aspect, the present application provides a battery comprising the battery cell in the above embodiment.

[0033] In a third aspect, the present application provides an electrical device, which includes the battery in the above embodiment, and the battery is used to provide electrical energy.

[0034] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0036] Figure 1 is a schematic diagram of an electrical device in the related art;

[0037] Figure 2 A schematic diagram of a battery in the related art;

[0038] Figure 3 A schematic diagram of a battery cell provided in some embodiments of the present application;

[0039] Figure 4 An exploded view of a battery cell provided in some embodiments of the present application;

[0040] Figure 5 A schematic diagram of an electrode assembly provided in some embodiments of the present application;

[0041] Figure 6 Schematic diagrams of electrode assemblies provided in other embodiments of the present application;

[0042] Figure 7 A cross-sectional view of a battery cell in a fully discharged state provided in some embodiments of the present application;

[0043] Figure 8 A schematic diagram of a pressure relief component according to some embodiments of the present application;

[0044] Figure 9 For the Figure 8 Cross-sectional view along line AA;

[0045] Figure 10 for Figure 9 The middle circle shows an enlarged view of point B;

[0046] Figure 11 Schematic diagram of a housing according to some embodiments of the present application;

[0047] Figure 12 For the Figure 11 Cross-sectional view of the mid-CC line;

[0048] Figure 13 for Figure 7 The middle circle shows the enlarged view of point D;

[0049] Figure 14 Schematic diagram of the connection between the end cap and the electrical connection part provided in some embodiments of the present application.

[0050] Reference numerals:

[0051] Battery 1000, vehicle 2000, battery cell 100, housing 200, first portion 201, first portion 202, housing 10, housing 101, end cap 102, first wall 11, pressure relief hole 111, second wall 12, first area 1111, second area 1112, first inner surface 11121, first outer surface 11122, electrode assembly 20, positive electrode sheet 21, negative electrode sheet 22, flat area 2 3, turning area 24, isolating part 25, electrical connection part 30, terminal body 31, first limiting part 32, second limiting part 33, pressure relief component 40, predetermined pressure relief area 401, first surface 40a, second surface 40b, first notched groove 41, first groove section 411, second groove section 412, second notched groove 42, pressure relief part 43, connecting part 5, first connecting part 51, first insulating part 6, second insulating part 7, patch 60. DETAILED DESCRIPTION

[0052] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0053] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" 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-secondary relationship.

[0054] Mentioning "embodiment" in this application means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places 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. The term "and / or" in this application is merely a description of the association relationship of associated objects, indicating that three relationships may exist. 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 previous and subsequent associated objects are in an "or" relationship.

[0055] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0056] The term "plurality" used in this application refers to two or more (including two).

[0057] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0058] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0059] The battery mentioned in the embodiments of the present application may include one or more battery cells to provide a single physical module with higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel or in hybrid through a busbar.

[0060] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. In some embodiments, the battery may be a battery pack. The battery pack includes a housing and battery cells. The battery cells or battery modules are housed in the housing.

[0061] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0062] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0063] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, the safety performance of the battery also needs to be considered.

[0064] In a battery cell, to ensure the safety performance of the battery cell, a pressure relief component may be provided on the outer shell of the battery cell. When the battery cell experiences thermal runaway, the pressure inside the battery cell is released through the pressure relief component to improve the safety of the battery cell.

[0065] During the charging and discharging process of the battery cell, the electrode assembly will expand, causing the shell to swell and deform. The expansion of the shell will be transmitted to the surface of the pressure relief component, causing the surface of the pressure relief component to become concave and stretched, especially in the direction of greater expansion of the electrode assembly. The notched groove will produce a large strain. The battery cell has a large expansion force when fully charged and a small expansion force when discharged. There is a large expansion force amplitude during long-term charging and discharging. Coupled with the gas production inside the battery cell and different external constraints, the notched groove will produce a large strain and strain amplitude, which will lead to fatigue cracking of the pressure relief component. The battery cell is prone to cracking, failure, and leakage of the pressure relief component before the warranty conditions are met.

[0066] In view of this, an embodiment of the present application provides a battery cell, comprising: N1 electrode assemblies, each electrode assembly comprising at least one positive electrode sheet, at least one negative electrode sheet, and at least one separator, the positive electrode sheets, the negative electrode sheets, and the separator are stacked to form a flat region, at least a portion of the positive electrode sheet, at least a portion of the negative electrode sheet, and at least a portion of the separator are stacked along a first direction in the flat region; the number of layers of positive electrode sheets stacked in the flat region of each electrode assembly is N2, N1 ≥ 1, N2 ≥ 1, N1 * N2 ≥ 50, the flat region has an outer surface perpendicular to the first direction, the area of ​​the outer surface is S, S ≥ 8000 mm 2 , the thickness dimension of the first wall portion in the second direction is H, H≤2.5mm. The shell is used to accommodate N1 electrode assemblies, and the shell includes a first wall portion. The first wall portion is located on one side of the electrode assembly in the second direction. The second direction is the thickness direction of the first wall portion and is perpendicular to the first direction. The pressure relief component is arranged on the first wall portion. The pressure relief component is provided with a first notch groove. The pressure relief component is configured to be able to crack along at least a portion of the first notch groove when the battery cell is depressurized. The first notch groove includes a first groove section extending along a straight trajectory, and the length direction of the first groove section is perpendicular to the first direction. The dimension of the bottom surface of the first groove section in the first direction is A, and the minimum residual thickness of the first groove section is D1, which satisfies: 0.3mm≤A≤0.8mm, 0.1mm≤D1≤0.28mm.

[0067] In such a battery cell, by limiting the bottom width and minimum residual thickness of the first slot segment within the above-mentioned range, the risk of damage, cracking, and leakage in the weak area corresponding to the first slot segment due to expansion and deformation of the electrode assembly can be reduced, thereby reducing the risk of fatigue cracking to a certain extent. At the same time, when thermal runaway occurs in the battery cell, the pressure relief component can explode in time to release the internal air pressure of the battery cell, thereby improving the reliability of the battery cell.

[0068] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries. Electrical devices may be vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may be fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0069] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0070] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 2000 provided in some embodiments of the present application. A battery 1000 is disposed within vehicle 2000, and battery 1000 can be located at the bottom, front, or rear of vehicle 2000. Battery 1000 can be used to power vehicle 2000, for example, as an operating power source for vehicle 2000.

[0071] The vehicle 2000 may further include a controller and a motor. The controller is used to control the battery 1000 to power the motor, for example, to meet the power requirements of the vehicle 2000 during starting, navigation, and driving.

[0072] In some embodiments of the present application, the battery 1000 can not only serve as the operating power source of the vehicle 2000, but also serve as the driving power source of the vehicle 2000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 2000.

[0073] Please refer to Figure 2 , Figure 2 This is an exploded view of a battery 1000 provided in some embodiments of the present application. The battery 1000 includes a battery cell 100 and a housing 200 , wherein the housing 200 is used to accommodate the battery cell 100 .

[0074] The housing 200 is a component that houses the battery cells 100 and provides storage space for the battery cells 100. The housing 200 can have various structures. In some embodiments, the housing 200 can include a first portion 201 and a second portion 202, which overlap to define a storage space for the battery cells 100. The first portion 201 and the second portion 202 can have various shapes, such as a rectangular parallelepiped or a cylinder. The first portion 201 can be a hollow structure with one side open, and the second portion 202 can be a hollow structure with one side open. The open side of the second portion 202 overlaps the open side of the first portion 201, forming the housing 200 with storage space. Alternatively, the first portion 201 can be a hollow structure with one side open, and the second portion 202 can be a plate-like structure. The second portion 202 overlaps the open side of the first portion 201, forming the housing 200 with storage space. As an example, the battery cell 100 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell 100 of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a polygonal battery, and a polygonal battery such as a hexagonal battery, etc. There is no special limitation in this application.

[0075] In the battery 1000, there can be one or more battery cells 100. If there are multiple battery cells 100, the multiple battery cells 100 can be connected in series, parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 100. Multiple battery cells 100 can be connected in series, parallel, or in a hybrid connection to form a battery module, which is then connected in series, parallel, or in a hybrid connection to form a whole and housed within the housing 200. Alternatively, all battery cells 100 can be directly connected in series, parallel, or in a hybrid connection, and then the whole battery module 100 can be housed within the housing 200.

[0076] Please refer to Figure 3 and Figure 4 , Figure 3 A schematic diagram of a battery cell 100 provided in some embodiments of the present application; Figure 4 The exploded view of the battery cell 100 provided in some embodiments of the present application is as follows. The battery cell 100 may include a housing 10 and an electrode assembly 20.

[0077] The housing 10 is used to house the electrode assembly 20 and other components such as the electrolyte. The housing 10 may be a steel shell, an aluminum shell, a plastic shell (e.g., polypropylene), a composite metal shell (e.g., a copper-aluminum composite shell), or an aluminum-plastic film. For example, the housing 10 may include a shell 101 and an end cap 102.

[0078] The housing 101 may be a hollow structure with an opening at one end, or may be a hollow structure with openings at two opposite ends. The housing 101 may be made of a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, and the like.

[0079] The end cap 102 is a component that closes the opening of the shell 101 to isolate the internal environment of the battery cell 100 from the external environment. The end cap 102 and the shell 101 together define a storage space for accommodating the electrode assembly 20, electrolyte and other components. The end cap 102 can be connected to the shell 101 by welding or rolling to close the opening of the shell 101. The shape of the end cap 102 can be adapted to the shape of the shell 10. For example, the shell 101 is a rectangular parallelepiped structure, and the end cap 102 is a rectangular plate structure adapted to the shell 10. The material of the end cap 102 can also be various, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0080] In the battery cell 10, there can be one or two end caps 102. In embodiments where the housing 101 is a hollow structure with openings at both ends, two end caps 102 can be provided. The two end caps 102 respectively close the two openings of the housing 101, and the two end caps 102 and the housing 101 together define a storage space. In embodiments where the housing 101 is a hollow structure with an opening at one end, there can be one end cap 102 provided. The end cap 102 closes the opening at one end of the housing 101, and the end cap 102 and the housing 101 together define a storage space.

[0081] The electrode assembly 20 includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell 100, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0082] In some embodiments, the positive electrode may be a positive electrode sheet 21 . The positive electrode sheet 22 may include a positive electrode current collector and a positive electrode active material region disposed on at least one surface of the positive electrode current collector. The positive electrode active material region has a positive electrode active material.

[0083] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material region is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0084] In some embodiments, the negative electrode may be a negative electrode sheet 22 , and the negative electrode sheet 22 may include a negative electrode current collector and a negative electrode active material region disposed on at least one surface of the negative electrode current collector.

[0085] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material region is provided on either one or both of the two facing surfaces of the negative electrode current collector.

[0086] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0087] In some embodiments, the electrode assembly 20 further includes a separator disposed between the positive electrode and the negative electrode.

[0088] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0089] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0090] In some embodiments, the battery cell 100 further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte may be selected based on needs. The electrolyte may be liquid, gel, or solid.

[0091] In some embodiments, the electrode assembly 20 is a wound structure in which the positive electrode sheet, the negative electrode sheet, and the separator are wound into the wound structure.

[0092] In some embodiments, the electrode assembly 20 is a laminated structure.

[0093] As an example, a plurality of positive electrode sheets 21 , a plurality of negative electrode sheets 22 and a plurality of separators 25 may be provided, and the plurality of positive electrode sheets 21 , the plurality of negative electrode sheets 22 and the plurality of separators 25 may be alternately stacked.

[0094] As an example, multiple separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0095] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0096] In some embodiments, the shape of the electrode assembly 20 can be flat or polygonal.

[0097] In some embodiments, the electrode assembly 20 is provided with tabs, which can conduct current from the electrode assembly 20. The tabs include a positive tab and a negative tab.

[0098] The battery cell 100 may further include an electrical connector 30 , which may be disposed on the outer casing 10 . The electrical connector 30 is configured to electrically connect to the tab of the electrode assembly 20 to output electrical energy from the battery cell 10 . The electrical connector 30 and the tab may be directly connected, for example, by direct welding. Alternatively, the electrical connector 30 and the tab may be indirectly connected, for example, through a current collecting member. The current collecting member may be a metal conductor, such as copper, iron, aluminum, steel, or an aluminum alloy.

[0099] like Figure 3 and Figure 4 As shown, taking the shell 101 as an example of a hollow structure with an opening at one end, two electrical connection parts 30 can be provided on the end cover 102, and the two electrical connection parts 30 are respectively a positive electrical connection part and a negative electrical connection part, the positive electrical connection part is electrically connected to the positive electrode ear, and the negative electrical connection part is electrically connected to the negative electrode ear.

[0100] Please refer to Figure 5 and Figure 6 , Figure 5 A schematic diagram of an electrode assembly 20 provided in some embodiments of the present application; Figure 6 Schematic diagram of an electrode assembly 20 provided in some other embodiments of the present application. The electrode assembly 20 includes a positive electrode sheet 21 and a negative electrode sheet 22. The positive electrode sheet 21 includes a positive electrode body and a positive electrode tab. The positive electrode tab extends from one end of the positive electrode body. Most of the positive electrode tab is not coated with positive electrode active material, while most of the positive electrode body is coated with positive electrode active material. The negative electrode sheet 22 includes a negative electrode body and a negative electrode tab. The negative electrode tab extends from one end of the negative electrode body. Most of the negative electrode tab is not coated with negative electrode active material, while most of the negative electrode body is coated with negative electrode active material. The positive electrode body and the negative electrode body constitute the main body of the electrode assembly.

[0101] like Figure 5 As shown, the electrode assembly 20 includes a plurality of electrode sheets arranged in a wound manner. The electrode assembly 20 includes a straight region 23 and a turning region 24 connected to ends of the straight region 23 .

[0102] A plurality of electrode sheets arranged in a wound manner, namely, a positive electrode sheet 21 and a negative electrode sheet 22 are stacked and wound around a set axis to form an electrode assembly 20. The straight area 23 refers to the portion of the electrode sheet extending along the plane after winding; the turning area 24 refers to the portion of the electrode sheet extending along the arc surface after winding, for example Figure 5 As shown, the portion between the front side surface and the rear side surface of the electrode assembly 20 is formed as a straight area 23. The extension direction of the electrode piece in the straight area 23 is the length direction of the straight area 23. Figure 5 As shown, in the straight area 23 , the length dimension of the positive electrode plate 21 in the left-right direction is B1 , and the left and right ends of the straight area 23 are turning areas 24 .

[0103] like Figure 6 As shown, the electrode assembly 120 includes a plurality of electrode sheets arranged in a stacked manner, and the electrode assembly 20 has a flat region 23 .

[0104] A plurality of stacked electrodes, for example, at least one positive electrode 21 and at least one negative electrode 22, are stacked to form an electrode assembly 20. The straight region 23 is formed by stacking at least a portion of the positive electrode 21 and the negative electrode 22. Alternatively, the straight region 23 is formed by stacking at least a portion of the positive electrode 21 and the negative electrode 22. The extension direction of the electrode in the straight region 23 is the length direction of the straight region 23. Figure 6 As shown, in the straight area 23 , the length dimension of the positive electrode tab 21 in the left-right direction is B1 .

[0105] Please refer to Figure 7-14 , Figure 7 and Figure 13 is a cross-sectional view of a battery cell in a fully discharged state according to some embodiments; Figures 8-10 A schematic diagram of a pressure relief component according to some embodiments of the present application; Figure 11-12 Schematic diagram of the housing of some embodiments of the present application, Figure 14 Schematic diagram of the connection between the end cap and the electrical connection part provided in some embodiments of the present application.

[0106] like Figure 3-Figure 12 As shown, the battery cell 100 according to an embodiment of the present application includes: N1 electrode assemblies 20, each electrode assembly 20 includes at least one positive electrode sheet 21, at least one negative electrode sheet 22 and at least one separator, the positive electrode sheet 21, the negative electrode sheet 22 and the separator are stacked to form a straight area 23, at least a portion of the positive electrode sheet 21 and at least a portion of the negative electrode sheet 22 and at least a portion of the separator are stacked in the straight area 23 along a first direction F1.

[0107] The number of layers of positive electrode sheets 21 stacked in the straight area 23 of each electrode assembly 20 is N2. The straight area has an outer surface perpendicular to the first direction F1, and the outer surface area is S, N1≥1, N2≥1, N1*N2≥50, S≥8000mm 2 .

[0108] The shell 10 is used to accommodate N1 electrode assemblies 20. The shell 10 includes a first wall portion 11. The first wall portion 11 is located on one side of the electrode assembly 20 in the second direction F2. The second direction F2 is the thickness direction of the first wall portion 11, and the second direction F2 is perpendicular to the first direction F1.

[0109] The thickness of the first wall portion 11 in the second direction F2 is H, where H is ≤ 2.5 mm.

[0110] The pressure relief component 40 is arranged on the first wall portion 11, and is provided with a first notched groove 41. The pressure relief component 40 is configured to be able to split along at least a portion of the first notched groove 41 when the battery cell 100 releases pressure. The first notched groove 41 includes a first groove segment 411 extending along a straight line trajectory, and the length direction of the first groove segment 411 is perpendicular to the first direction F1.

[0111] The dimension of the bottom surface of the first groove section 411 in the first direction F1 is A, and the minimum residual thickness of the first groove section 411 is D1, which satisfies the following conditions: 0.3 mm ≤ A ≤ 0.8 mm, and 0.1 mm ≤ D1 ≤ 0.28 mm.

[0112] The housing 10 refers to the outermost structural component of the battery cell 100 , and houses the electrode assembly 20 and electrolyte, etc. The housing 10 may contain one or more electrode assemblies 20 .

[0113] The electrode assembly 20 can be a laminated type, that is, multiple pole pieces of the electrode assembly 20 are stacked, and the pole pieces are stacked to form a flat area 23. The electrode assembly 20 is in a stacked state as a whole. In the flat area 23, the positive pole piece 21, the negative pole piece 22 and at least a portion of the isolation member 25 are stacked along the first direction F1, so that the expansion deformation of the electrode assembly 20 is particularly obvious in the first direction F1.

[0114] The electrode assembly 20 can also be a wound type. The positive electrode sheet 21 and the negative electrode sheet 22 of the electrode assembly 20 are stacked and wound with the separator 25, and a straight area 23 and a turning area 24 are formed. The straight area 23 refers to the part of the electrode sheet extending along the plane after winding, and the part of the electrode assembly 20 in the straight area 23 is in a stacked state; the turning area 24 refers to the part of the electrode sheet extending along the arc surface after winding, and the outer surface of the turning area 24 is at least partially an arc surface. The straight area 23 connects the two turning areas 24. In the straight area 23, part of the positive electrode sheet 21, part of the negative electrode sheet 22 and part of the separator 25 are stacked along the first direction F1. For example, after winding, each layer of the positive electrode sheet 21, each layer of the negative electrode sheet 22 and each layer of the separator 25 can be pierced by a straight line extending along the first direction F1, so that the expansion deformation of the electrode assembly 20 is particularly obvious in the first direction F1. The number of layers of positive electrode sheets 21 stacked in the flat region 23 of each electrode assembly 20 is N2.

[0115] The positive electrode sheet 21 includes a positive electrode body and a positive electrode tab. The positive electrode tab protrudes from the positive electrode body in the second direction F2. Most or all areas of the positive electrode body are coated with positive electrode active material, and most or all areas of the positive electrode tab are not coated with positive electrode active material. A small amount of insulating layer may be coated on the edge of the positive electrode body.

[0116] Correspondingly, the negative electrode sheet 22 includes a negative electrode body and a negative electrode tab, the negative electrode tab protrudes from the negative electrode body in the second direction F2, most or all areas of the negative electrode body are coated with negative electrode active material, and most or all areas of the negative electrode tab are not coated with negative electrode active material.

[0117] The outer shell 10 includes a first wall portion 11 and two second wall portions 12. The two second wall portions 12 are respectively located on both sides of the electrode assembly 20 in the first direction F1. Most of the expansion of the electrode assembly 20 will act on the second wall portions 12. The first wall portion 11 is located on one side of the electrode assembly 20 in the second direction F2. The second direction F2 is perpendicular to the first direction F1. The thickness direction of the first wall portion 11 is the second direction F2. A pressure relief component 40 is provided on the first wall portion 11.

[0118] The pressure relief component 40 is a component used to release the internal pressure of the battery cell 100. When the internal pressure of the battery cell 100 reaches a threshold, the discharge medium inside the battery cell 100 is discharged through the pressure relief component 40 to achieve the purpose of pressure relief. The threshold design varies according to different design requirements. The threshold may depend on one or more materials of the positive electrode plate 21, the negative electrode plate 22, the electrolyte and the separator in the battery cell 100.

[0119] When the battery cell 100 is depressurized, it can be split along at least a portion of the first notched groove 41, that is, the first notched groove 411 of the pressure relief component 40 is a weak portion. The first notched groove 41 includes a first groove segment 411, and the first groove segment 411 extends along a straight line. The length direction of the first groove segment 411 is perpendicular to the first direction F1, that is, the extension direction of the first groove segment 411 is perpendicular to the first direction F1. Figures 8-10 As shown, the first slot segment 411 extends along the third direction F3 , and the dimension A of the slot bottom surface of the first slot segment 411 in the first direction F1 is the width dimension of the slot bottom surface of the first slot segment 411 .

[0120] The first groove section 411 serves as a weak area of ​​the pressure relief component 40. Along the thickness direction of the first wall portion 11 (the second direction F2), the first groove section 411 has a minimum residual thickness D1. The minimum residual thickness D1 of the first groove section 411 is the minimum thickness dimension of the pressure relief component 40 in the second direction F2 at the first groove section 411.

[0121] When the battery cell 100 expands during the charge and discharge process, causing the outer shell 10 to deform, the deformation of the first wall portion 11 is mainly borne by the first groove section 411. Because under the same expansion force, the groove section with a smaller width dimension deforms more than the groove section with a larger width dimension. Therefore, the smaller the dimension A of the groove bottom surface of the first groove section 411 in the first direction F1, the weaker the ability of the first groove section 411 to withstand deformation in the first direction F1. During the long-term charge and discharge process of the battery cell 100, the greater the strain and strain amplitude generated in the first groove section 411, the more likely the pressure relief component 40 will suffer from fatigue cracking, and the lower the long-term reliability.

[0122] When the dimension A of the bottom surface of the first groove section 411 in the first direction F1 is larger, the stress concentration at the first groove section 411 is reduced, and the number of fatigue cracks during the long-term use of the battery cell 100 increases. However, when A is too large, the bursting pressure at the first notched groove 41 increases, resulting in a decrease in the probability of the pressure relief component 40 bursting and relieving pressure in a timely manner. When the battery cell 100 has thermal runaway, it is easy to explode at the end cover welding point, which will also reduce reliability.

[0123] In addition, the smaller the minimum residual thickness D1 of the first groove section 411, the lower the strength at the first groove section 411. During the long-term charging and discharging use of the battery cell 100, the greater the strain and strain amplitude generated at the first groove section 411, the more likely the pressure relief component 40 is to suffer from fatigue cracking, which affects the number of cycles of the battery cell 100 and reduces the long-term reliability.

[0124] When the minimum residual thickness D1 of the first groove section 411 is larger, the stress concentration at the first groove section 411 is reduced, and the number of fatigue cracks during the long-term use of the battery cell 100 increases. However, when D1 is too large, the bursting pressure at the first notched groove 41 increases, resulting in a decrease in the probability of the pressure relief component 40 bursting and relieving pressure in a timely manner. When thermal runaway occurs, the battery cell 100 is prone to bursting at the end cover welding point, which also reduces reliability.

[0125] Among them, whether it is a wound or laminated electrode assembly 20, in the straight area 23 of the electrode assembly 20, the more layers of stacked positive electrode sheets 21, the more corresponding negative electrode sheets 22 are required, and the greater the expansion deformation of the electrode assembly 20. Therefore, the expansion of the electrode assembly 20 is positively correlated with the number of layers of positive electrode sheets 21. The larger the area of ​​the outer surface of the straight area 23 perpendicular to the first direction F1, the greater the expansion deformation of the electrode assembly 20, the smaller the thickness of the first wall portion 11, the weaker the rigidity of the first wall portion 11, and the higher the risk of fatigue cracking of the first notch groove 41. Accordingly, the total number of layers of positive electrode sheets 21 stacked in the straight area 23 is N1*N2≥50, and the area S of the outer surface of the straight area perpendicular to the first direction F1 is ≥8000mm 2In a battery cell with a thickness dimension H of the first wall portion 11 in the second direction F2 of ≤ 2.5 mm, the electrode assembly 20 has a large expansion during the charge and discharge process of the battery cell 100. The measurement method of N2 is as follows: after disassembling the battery cell 100 and removing the electrode assembly, the number of positive electrode sheets in the flat area 23 in the first direction F1 is calculated without damaging the integrity of the electrode assembly 20. Figure 5-Figure 7 As shown, the measurement method of S here is the product of the height dimension M2 of the outer plane of the flat area perpendicular to the first direction in the second direction F2 and the length dimension M1 in the third direction F3.

[0126] For this reason, Figure 10 As shown, the groove bottom surface size A of the first groove segment 411 is limited to between 0.3mm and 0.8mm. A can be any point value among 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, or a range value between any two of them. The minimum residual thickness D1 of the first groove segment 411 is limited to between 0.1 mm and 0.28 mm. D1 can be any point value among 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, and 0.28 mm, or a range value between any two of them.

[0127] This increases the bottom width and minimum residual thickness of the first groove section 411 to a certain extent, increases the deformation resistance of the first groove section 411, and reduces the deformation of the pressure relief component 40 at the first groove section 411 when the electrode assembly 20 expands. This can avoid the risk of fatigue cracking of the pressure relief component 40 to a certain extent during the long-term charging and discharging process of the battery cell 100, reduce the probability of leakage caused by the pressure relief component 40 being pulled and damaged, and improve the reliability of the battery cell 100; at the same time, it can avoid the explosion pressure of the pressure relief component 40 being too high, and reduce the probability of the pressure relief component 40 failing to explode in time and easily exploding at other positions when the battery cell 100 suffers from thermal runaway, thereby further improving the reliability of the battery cell 100.

[0128] In the technical solution of the embodiment of the present application, by limiting the bottom surface size and residual thickness of the first groove section 411, the damage, cracking and leakage of the weak area corresponding to the first groove section 411 due to the expansion of the electrode assembly 20 can be reduced, thereby reducing the risk of fatigue cracking to a certain extent. At the same time, when thermal runaway occurs in the battery cell 100, the pressure relief component 40 can explode in time to release the internal air pressure of the battery cell 100, thereby improving the reliability of the battery cell 100.

[0129] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0130] Example 1

[0131] 1) Preparation of positive electrode sheet

[0132] The positive electrode active material LiNi0.7Co0.1Mn0.1O2, the conductive agent Super P, and the binder polyvinylidene fluoride (PVDF) are prepared into a positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 50wt%, and the mass ratio of LiNi0.7Co0.1Mn0.1O2, Super P, and PVDF in the solid components is 8:1:1. The positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil and dried at 85°C and then cold pressed. Then, the positive electrode sheet is trimmed, cut into pieces, and divided into strips, and then dried under vacuum conditions at 85°C for 4 hours to make a positive electrode sheet.

[0133] 2) Preparation of negative electrode sheet

[0134] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry is 30wt%, and the mass ratio of graphite, silicon oxide, Super P, CMC and adhesive styrene butadiene rubber (SBR) in the solid components is 88:7:3:2. The negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C, and then cold pressed, trimmed, cut into pieces, and slit, and then dried under vacuum conditions at 120°C for 12 hours to prepare a negative electrode sheet.

[0135] 3) Preparation of electrolyte

[0136] In an argon atmosphere glove box (H2O <0.1ppm, O2 <0.1ppm), the fully dried electrolyte salt LiPF6 was dissolved in a mixed solvent (the mixed solvent included ethylene carbonate (EC) and diethyl carbonate (DEC), and ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a mass ratio of 50:50), and after mixing evenly, a liquid electrolyte with a concentration of 1 mol / L was obtained.

[0137] 4) Isolation parts

[0138] A 16 μm polyethylene film was used as a separator.

[0139] 5) Lithium-ion battery preparation

[0140] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed in the middle of the positive and negative electrode sheets to isolate the positive and negative electrodes. The electrode assembly is wound and the tabs are welded. The electrode assembly is placed in an aluminum casing, and the prepared electrolyte is injected into the dried casing. The battery is packaged, allowed to stand, formed, shaped, and capacity tested to complete the preparation of the lithium-ion battery.

[0141] In the structure of the lithium-ion battery, there are two electrode assemblies in the housing. The number of positive electrode sheets stacked in the straight area of ​​each electrode assembly is 64, and the total number of positive electrode sheets stacked in the straight area is 128. The surface area of ​​the positive electrode body of each positive electrode sheet is S, S = 20000mm 2 .

[0142] The shell includes a shell and an end cover. The direction perpendicular to the large surface of the electrode assembly is the first direction. The first shell is a rectangular parallelepiped structure. The shell is a structure with an open end in the second direction. The end cover closes the opening. The end cover is welded to the shell. The wall opposite to the end cover is the first wall. The thickness of the first wall is H, H = 1.5mm. The first wall is a rectangular wall. The first wall has a pressure relief hole. The area of ​​the pressure relief hole projected along the second direction F2 is W, W = 860mm 2 The dimension of the pressure relief hole in the first direction F1 is B, the dimension of the pressure relief hole 111 in the third direction F3 is L, and L / B=3.38.

[0143] The pressure relief component is arranged at the pressure relief hole of the first wall portion. The pressure relief component is provided with a pressure relief portion. The thickness dimension of the pressure relief portion is D2, D2=0.31mm. The pressure relief portion has a first notched groove and a second notched groove. The first notched groove includes a first groove section and two second groove sections. The first groove section and the second notched groove extend along a third direction. The first groove section, the two second groove sections and the second notched groove jointly define a predetermined pressure relief area.

[0144] The width dimension of the first groove segment in the first direction F1 is A, which is 0.3 mm. The minimum residual thickness of the first groove segment is D1, which is 0.18 mm.

[0145] The method for measuring the fatigue times of battery cells is as follows:

[0146] 1) Prepare a special test fixture. Specifically, the fixture consists of three 10mm steel plates (first steel plate, second steel plate, and third steel plate). Each steel plate can completely cover the large surface of the battery cell. The first and third steel plates are located at both ends of the fixture and are fixed by bolts. The second steel plate is located between the first and third steel plates and is constrained by a guide rail. The second steel plate can only move in a direction perpendicular to the plane of the steel plates.

[0147] 2) A support structure is placed between the largest outer surface of one side of the battery cell and the first steel plate, and between the largest outer surface of the other side of the battery cell and the second steel plate (i.e., a support structure is placed on both sides of the battery cell in the expansion direction of the electrode assembly). The support structure can be an insulation pad or a water-cooling plate (consistent with the material / structure between the battery cells in the actual battery). The support structure can be compressed to provide expansion space for the battery cell during the charge and discharge cycle aging process; the largest outer surface of one side of the battery cell is laminated to the support structure, the first steel plate is laminated to the corresponding support structure, the second steel plate is laminated to the corresponding support structure, and a pressure sensor is provided between the second and third steel plates;

[0148] 3) Adjust the position of the second steel plate by adjusting the pre-tightening force of the bolts, observe the pressure sensor, make the initial extrusion force of the battery cell 2000N, and connect the two electrical connection parts of the battery cell to the dedicated battery charging and discharging equipment;

[0149] 4) Place the battery cell and fixture in a constant temperature environment of 25±2℃ and start the test after the battery cell reaches temperature equilibrium;

[0150] 5) The test steps are carried out in accordance with Section 6.4 "Standard Cycle Life" of GBT31484-2015 Cycle Life Requirements and Test Methods for Power Batteries for Electric Vehicles, and the test cycle end condition is changed to "stop testing until damage occurs at the notch groove of the pressure relief component."

[0151] Specifically, test according to the following steps:

[0152] a) Discharge to 2.8V with a current of 1I1(A);

[0153] b) Leave it for no less than 30 minutes;

[0154] c) Charge in accordance with the method 6.1.1.3 of GBT31484-2015 Cycle Life Requirements and Test Methods for Power Batteries for Electric Vehicles;

[0155] d) Leave it for no less than 30 minutes;

[0156] e) Discharge to 2.8V at a current of 1I1(A);

[0157] f) Repeat steps b) to e) until the notch of the pressure relief component breaks and the test is stopped.

[0158] That is, the pressure relief component of the battery cell is continuously observed during the test process until the notched groove of the pressure relief component is damaged and cracked, resulting in leakage. The number of cycles is recorded as the cycle fatigue number of the battery cell. Among them, the more cycle fatigue numbers of the battery cell, the lower the probability of premature cracking of the pressure relief component of the battery cell during long-term use, and the longer the service life. Therefore, the cycle fatigue number of the battery cell can be used to reasonably predict the possibility of premature cracking of the pressure relief component of the battery cell during use.

[0159] The battery cell thermal runaway test method is as follows:

[0160] 1) Select the heating plate according to the size of the battery cell. The size of the heating plate should cover as much surface of the battery cell as possible (coverage area ≥ 60%).

[0161] 2) Before testing, charge the battery cells to 100% SOC and ensure that the battery cell temperature is 25±5℃;

[0162] 3) Sensor Layout: a) Temperature Sensing Wire Layout: Apply a layer of Teflon to the center of each of the two large surfaces of the battery cell. Place the temperature sensing wire on top of the Teflon, and then apply another layer of Teflon. b) Voltage Sampling Wire Layout: Apply a layer of Teflon to the positive and negative electrical connections and the outer shell of the battery cell. Place the voltage sampling wire on top of the Teflon, and then apply another layer of Teflon. c) Connect the temperature sensing wire and voltage sampling wire to a data acquisition device for real-time data collection and analysis. The data acquisition device acquisition frequency is ≤0.1s.

[0163] 4) Assemble the fixture so that it completely covers the large surface of the battery cell. The clamping force is 3000N. Note: The arrangement order of the fixture, heating plate and battery cell is: fixture + heating plate + battery cell + fixture;

[0164] 5) Test: Turn on the data acquisition instrument to collect temperature and voltage data, then turn on the heating plate at a power of 500W to heat the battery cell until the battery cell thermal runaway occurs.

[0165] 6) Thermal runaway determination criteria: a) The triggering object generates a voltage drop that exceeds 25% of the initial voltage; b) The temperature at the detection point reaches the maximum operating temperature specified by the manufacturer; c) The temperature rise rate dT / dt at the detection point is ≥ 1°C / s and lasts for more than 3 seconds. When a) and c) or b) and c) occur, thermal runaway is determined to have occurred and the moment of thermal runaway is determined.

[0166] 7) After the surface temperature of the battery cell cools to room temperature, observe whether there is any cracking or explosion at the welding point between the battery cell end cover and the shell.

[0167] The preparation methods of the battery cells in Examples 2-6 and Comparative Examples 1-4 are the same as those in Example 1, with the specific difference being the values ​​of A and / or D1, as shown in Table 1. The number of cycles of the battery cells 100 (i.e., the number of fatigue times of the battery cells) and the thermal runaway of the battery cells when the pressure relief component 40 of the batteries obtained in Examples 1-6 and Comparative Examples 1-4 leaks are characterized, and the characterization results are shown in Table 1.

[0168] Table 1

[0169]

[0170]

[0171] Based on the data of Examples 1-3 and Comparative Examples 1 and 2, it can be seen that when A is less than 0.3 mm, the fatigue times are too low to meet the life requirements, but when A is greater than 0.8 mm, the end cover will explode when the battery cell 100 thermally runs away. Further adjusting the size of A within the given range is conducive to the battery cell 100 having better cycle performance.

[0172] Based on the data of Examples 4-6 and Comparative Examples 3 and 4, it can be seen that when D1 is less than 0.1 mm, the fatigue times are too low to meet the life requirements, but when D1 is greater than 0.28 mm, the end cover will explode when the battery cell 100 thermally runs away. Further adjusting the size of D1 within the given range is conducive to the battery cell 100 having better cycle performance.

[0173] In some embodiments, 0.4mm≤A≤0.7mm, that is, the groove bottom surface size A of the first groove segment 411 can be any one of 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, 0.51mm, 0.52mm, 0.53mm, 0.54mm, 0.55mm, 0.56mm, 0.57mm, 0.58mm, 0.59mm, 0.6mm, 0.61mm, 0.62mm, 0.63mm, 0.64mm, 0.65mm, 0.66mm, 0.67mm, 0.68mm, 0.69mm, and 0.7mm, or a range value between any two of them.

[0174] This increases the ability of the first groove section 411 to withstand deformation and reduces the deformation of the pressure relief component 40 at the first groove section 411 when the electrode assembly 20 expands. This can avoid the risk of fatigue cracking of the pressure relief component 40 to a certain extent during the long-term charging and discharging use of the battery cell 100, reduce the probability of leakage caused by the pressure relief component 40 being pulled and damaged, and improve the reliability of the battery cell 100; at the same time, it can avoid excessive explosion pressure of the pressure relief component 40, and reduce the probability of the pressure relief component 40 failing to explode in time and easily exploding at other locations when the battery cell 100 suffers from thermal runaway, thereby further improving the reliability of the battery cell 100.

[0175] In some embodiments, 0.12 mm ≤ D1 ≤ 0.25 mm, that is, the minimum residual thickness D1 of the first groove segment 411 can be any one of 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, and 0.25 mm, or a range between any two of them.

[0176] This increases the ability of the first groove section 411 to withstand deformation and reduces the deformation of the pressure relief component 40 at the first groove section 411 when the electrode assembly 20 expands. This can avoid the risk of fatigue cracking of the pressure relief component 40 to a certain extent during the long-term charging and discharging use of the battery cell 100, reduce the probability of leakage caused by the pressure relief component 40 being pulled and damaged, and improve the reliability of the battery cell 100; at the same time, it can avoid excessive explosion pressure of the pressure relief component 40, and reduce the probability of the pressure relief component 40 failing to explode in time and easily exploding at other locations when the battery cell 100 suffers from thermal runaway, thereby further improving the reliability of the battery cell 100.

[0177] like Figure 9 and Figure 10As shown, in some embodiments, the pressure relief component 40 includes a main body and a pressure relief portion 43, the main body is connected to the first wall portion 11, the thickness of the pressure relief portion 43 is less than the thickness of the main body, the first notch groove 41 is provided in the pressure relief portion 43, and the thickness dimension of the pressure relief portion 43 in the second direction F2 is D2, satisfying: 0.182mm≤D2≤0.4mm.

[0178] like Figure 9 and Figure 10 As shown, the pressure relief component 40 includes a main body and a pressure relief portion 43. The main body is connected to the first wall portion 11. The thickness of the pressure relief portion 43 is less than the thickness of the main body. The pressure relief portion 43 can be a constant thickness structure. The thickness of the pressure relief portion 43 is less than the thickness of the main body and greater than the thickness at the first notch groove 41. The pressure relief portion 43 can also be a variable thickness structure. The maximum thickness of the pressure relief portion 43 is less than the thickness of the main body, and the minimum thickness of the pressure relief portion 43 is greater than the thickness at the first notch groove 41.

[0179] The shape of the pressure relief portion 43 projected onto the plane where the first wall portion 11 is located can be a square with rounded corners, or a circle, or an oblong, or an ellipse. The pressure relief portion 43 can also be formed in a ring shape, and the edge of the pressure relief portion 43 is arc-shaped, thereby reducing the probability of stress concentration at the edge of the pressure relief portion 43, and reducing the probability of liquid leakage due to damage to the edge of the pressure relief portion 43.

[0180] The first notched groove 41 is provided on the pressure relief portion 43, that is, a notch is provided on one side surface of the pressure relief portion 43 to form the first notched groove 41, wherein the thickness dimension of the pressure relief portion 43 in the second direction F2 is D2. If D2 is too large, stress concentration is likely to occur at the first groove section 411, and fatigue cracking is likely to occur in the pressure relief component 40; the smaller D2 is, the pressure relief portion 43 can absorb part of the deformation, thereby reducing the stress concentration degree at the first groove section 411 and increasing the number of fatigue cracking of the battery cell 100 during long-term use; however, if D2 is too small, the pressure relief portion 43 absorbs too much deformation, the stress concentration degree at the first groove section 411 is too small, the bursting pressure at the first notched groove 41 increases, and the battery cell 100 is likely to explode at the end cover welding point when thermal runaway occurs, which will reduce reliability.

[0181] To this end, D2 is limited to between 0.182mm and 0.4mm. D2 can be any one of 0.182mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, or 0.4mm, or a range value between any two of them.

[0182] In this way, the stress concentration at the first groove section 411 is reduced, and the risk of fatigue cracking of the pressure relief component 40 is avoided to a certain extent. At the same time, the explosion pressure of the pressure relief component 40 can be prevented from being too high. When the battery cell 100 has thermal runaway, the probability that the pressure relief component 40 fails to explode in time and easily explodes at other locations is reduced, thereby improving the reliability of the battery cell 100.

[0183] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0184] The battery cell preparation methods and battery cell structures in Examples 7-10 are the same as those in Example 1.

[0185] The difference is that in Examples 7-10, the width dimension A of the first groove segment 411 in the first direction F1 is 0.55 mm, the minimum residual thickness D1 of the first groove segment is 0.18 mm, and the value of the thickness dimension D2 of the pressure relief portion is shown in Table 2.

[0186] The number of cycles of the battery cells 100 (ie, fatigue times of the battery cells) and thermal runaway of the battery cells when the pressure relief components 40 leaked in the batteries obtained in Examples 7-10 were characterized. The characterization results are shown in Table 2.

[0187] Table 2

[0188] serial number D2(mm) Technical Effects Example 7 0.4 Fatigue number 1089, the welding between the end cover and the shell is normal Example 8 0.35 Fatigue times 1378, the welds between the end cover and the shell are normal Example 9 0.26 Fatigue times 2166, the welds between the end cover and the shell are normal Example 10 0.182 Fatigue times 2828, the welding between the end cover and the shell is normal

[0189] Based on the data of Examples 7-10, it can be seen that when D2 is greater than 0.4 mm, the fatigue times will be further reduced, affecting the service life of the battery cell. However, when D2 is less than 0.182 mm, the probability of the end cover 102 exploding when the battery cell 100 thermally runs away will increase. Further adjusting the size of D2 within the given range is conducive to the battery cell 100 having better cycle performance.

[0190] In some preferred examples, 0.2 mm ≤ D2 ≤ 0.3 mm.

[0191] That is, D2 can be any point value among 0.2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, and 0.3mm, or a range value between any two of them.

[0192] As a result, the stress concentration at the first groove section 411 is further reduced, and the risk of fatigue cracking of the pressure relief component 40 is avoided to a certain extent. At the same time, the explosion pressure of the pressure relief component 40 can be prevented from being too high. When the battery cell 100 has thermal runaway, the probability that the pressure relief component 40 fails to explode in time and easily explodes at other locations is reduced, thereby improving the reliability of the battery cell 100.

[0193] like Figure 9 and Figure 10 As shown, in some embodiments, the pressure relief component 40 is provided with a pressure relief portion 43, the first notch groove 41 is provided in the pressure relief portion 43, and the thickness dimension of the pressure relief portion 43 in the second direction F2 is D2, satisfying: 0.55≤D1 / D2≤0.85.

[0194] The first notched groove 41 is provided on the pressure relief portion 43, that is, a notch is provided on one side surface of the pressure relief portion 43 to form the first notched groove 41, wherein the thickness dimension of the pressure relief portion 43 in the second direction F2 is D2. When the minimum residual thickness D1 of the first groove segment 411 of the first notched groove 41 is constant, when D1 / D2 is too small and D2 is too large, the thickness difference between the first groove segment 411 and the pressure relief portion 43 of the pressure relief component 40 is large, stress concentration is easy to occur at the first groove segment 411, and fatigue cracking is easy to occur in the pressure relief component 40.

[0195] The larger D1 / D2 is and the smaller D2 is, when the electrode assembly 20 expands, the pressure relief portion 43 can absorb part of the deformation, thereby reducing the stress concentration at the first groove section 411 and increasing the number of fatigue cracks of the battery cell 100 during long-term use. However, when D1 / D2 is too large and D2 is too small, the pressure relief portion 43 absorbs too much deformation, the stress concentration at the first groove section 411 is too small, the bursting pressure at the first notched groove 41 increases, and the battery cell 100 is prone to explode at the end cover welding when thermal runaway occurs, which also reduces reliability.

[0196] To this end, D1 / D2 is limited to between 0.55-0.85, and D1 / D2 can be any one of 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.85, 0.81, 0.82, 0.83, 0.84, 0.85, or a range between any two of them.

[0197] As a result, the stress concentration at the first groove section 411 is reduced, and the risk of fatigue cracking of the pressure relief component 40 is avoided to a certain extent. At the same time, the explosion pressure of the pressure relief component 40 can be prevented from being too high. When the battery cell 100 suffers from thermal runaway, the probability that the pressure relief component 40 fails to explode in time and easily explodes at other locations is reduced, thereby improving the reliability of the battery cell 100. In addition, limiting D1 / D2 within the above range is also beneficial to the manufacturing and forming of the notched groove on the pressure relief portion 43, thereby facilitating the manufacture of the pressure relief component 40.

[0198] like Figure 11 As shown, in some embodiments, the first wall portion 11 has a pressure relief hole 111, and the pressure relief component 40 is installed in the pressure relief hole 111. The area of ​​the pressure relief hole 111 projected along the second direction F2 is W, 400mm 2 ≤W≤1400mm 2 .

[0199] like Figures 8-11 As shown, the pressure relief component 40 and the shell 10 are two separate components, which are separately molded and then installed together. Specifically, the pressure relief component 40 can be an explosion-proof disk, an explosion-proof valve, a safety valve and other components. The pressure relief component 40 can be installed on the first wall portion 11 by bonding, welding and other methods. The first wall portion 11 is provided with a pressure relief hole 111, and the pressure relief component 40 is installed in the pressure relief hole 111. When the internal pressure of the battery cell 100 reaches a threshold value, the pressure relief component 40 opens at least part of the pressure relief hole 111, and the discharge medium inside the battery cell 100 is discharged through the pressure relief hole 111 to release the pressure inside the battery cell 100.

[0200] like Figure 8 and Figure 11As shown, taking the pressure relief component 40 as an explosion-proof disc as an example, the explosion-proof disc is a sheet having at least a portion of its strength less than that of the first wall portion 11. The explosion-proof disc covers the pressure relief hole 111 and is welded to the first wall portion 11. When the internal pressure of the battery cell 100 reaches a threshold, the explosion-proof disc is at least partially destroyed, thereby opening at least a portion of the pressure relief hole 111 to release the pressure within the battery cell 100. The pressure relief component 40 is a separate component from the outer casing 10. The pressure relief component 40 and the outer casing 10 can be manufactured and reassembled separately, which reduces manufacturing complexity and improves efficiency.

[0201] Among them, the larger the area of ​​the pressure relief hole 111, the weaker the first wall portion 11, and the more likely the first notch groove 41 is to fatigue and crack during the charging and discharging process of the battery cell 100; the smaller the area of ​​the pressure relief hole 111, the smaller the explosion area of ​​the pressure relief component 40, thereby affecting the pressure relief effect, and it is also easy for the pressure relief component 40 to explode at other locations, affecting the reliability of the battery cell 100.

[0202] To this end, the area W of the pressure relief hole 111 projected along the second direction F2 is limited to 400mm 2 -1400mm 2 Between, that is, W can be 400mm 2 , 500mm 2 , 600mm 2 , 700mm 2 , 800mm 2 , 900mm 2 , 1000mm 2 , 1100mm 2 , 1200mm 2 , 1300mm 2 , 1400mm 2 Any point value or any range of values ​​between them.

[0203] In this way, the risk of fatigue cracking of the pressure relief component 40 can be avoided to a certain extent. At the same time, when the battery cell 100 has thermal runaway, the probability that the pressure relief component 40 fails to explode in time and easily explodes at other locations is reduced, thereby improving the reliability of the battery cell 100.

[0204] Among them, Figure 11 As an example of the runway-shaped pressure relief hole 111, the size of the pressure relief hole 111 in the first direction F1 is B, and the size of the pressure relief hole 111 in the third direction is L, W = B*L+(ΠB 2 ) / 4.

[0205] In some examples, 600 mm 2 ≤W≤1200mm 2 , that is, the area W of the pressure relief hole 111 can be 600mm 2, 700mm 2 , 800mm 2 , 900mm 2 , 1000mm 2 , 1100mm 2 , 1200mm 2 Any point value or any range of values ​​between them.

[0206] Thus, the risk of fatigue cracking of the pressure relief component 40 is further avoided. At the same time, when thermal runaway occurs in the battery cell 100, the pressure relief component 40 can explode in time to release the internal air pressure of the battery cell 100, thereby improving the reliability of the battery cell 100.

[0207] like Figure 11 As shown, in some embodiments, the first wall portion 11 has a pressure relief hole 111, and the pressure relief component 40 is installed in the pressure relief hole 111. The size of the pressure relief hole 111 in the first direction F1 is B, and the size of the pressure relief hole 111 in the third direction is L. The third direction is perpendicular to the first direction F1 and the second direction F2, satisfying: 1.5≤L / B≤5.

[0208] The first wall portion 11 is provided with a pressure relief hole 111, and the pressure relief component 40 is installed in the pressure relief hole 111. When the internal pressure of the battery cell 100 reaches a threshold value, the pressure relief component 40 opens at least part of the pressure relief hole 111, and the discharge medium inside the battery cell 100 is discharged through the pressure relief hole 111 to release the pressure inside the battery cell 100.

[0209] By controlling the area of ​​the pressure relief hole 111 within a certain range, the pressure relief component 40 has a sufficient explosion area to ensure the pressure relief effect, wherein the area of ​​the pressure relief hole 111 is related to the dimension B of the pressure relief hole 111 in the first direction and the dimension L in the third direction. For a certain area of ​​the pressure relief hole 111, when L / B is too large, the pressure relief hole 111 is relatively slender, the stiffness of the first wall portion 11 is low, the pressure relief component 40 is more prone to fatigue cracking, and the reliability is low; when L / B is too small, the pressure relief hole 111 is too close to the edge of the first wall portion 11, the manufacturing difficulty is large, and the manufacturing quality rate is difficult to meet the requirements.

[0210] To this end, L / B is limited to between 1.5 and 5. L / B can be any one of 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or a range between any two of them.

[0211] In this way, the risk of fatigue cracking of the pressure relief component 40 can be avoided to a certain extent, while the manufacturing difficulty is reduced and the manufacturing efficiency is improved.

[0212] In some preferred examples, 2≤L / B≤4, L / B can be any one of 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, or a range between any two of them.

[0213] In this way, the risk of fatigue cracking of the pressure relief component 40 can be further avoided, while the manufacturing difficulty is reduced and the manufacturing efficiency is improved.

[0214] like Figure 11 As shown, in some embodiments, the width of the first wall portion 11 along the first direction F1 is D3, satisfying: 0.008≤A / D3≤0.019, 20mm≤D3≤80mm.

[0215] In the first direction F1, the width D3 of the first wall portion 11 is between 20 mm and 80 mm. For example, the width D3 of the first wall portion 11 is any one of 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, and 80 mm, or a range between any two of them.

[0216] Among them, on a battery cell of a certain size, if A / D3 is too small, the width A of the first groove section 411 is too small, the ability of the first groove section 411 to withstand deformation in the first direction F1 is weaker, and during the long-term charging and discharging use of the battery cell 100, the strain and strain amplitude generated in the first groove section 411 are greater, the pressure relief component 40 is more likely to suffer fatigue cracking, and the long-term reliability is lower; if A / D3 is too large, the width A of the first groove section 411 is too large, the bursting pressure at the first notched groove 41 increases, resulting in a lower probability of the pressure relief component 40 exploding and relieving pressure in time, and the battery cell 100 is likely to explode at the end cover weld when thermal runaway occurs, thereby also reducing reliability.

[0217] To this end, A / D3 can be limited to between 0.008 and 0.019. A / D3 can be any one of 0.008, 0.009, 0.01, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, and 0.019, or a range between any two of them.

[0218] This can reduce the risk of damage, cracking, and leakage in the weak area corresponding to the first groove section 411 due to the expansion of the electrode assembly 20, and reduce the risk of fatigue cracking to a certain extent. At the same time, when the battery cell 100 suffers from thermal runaway, the pressure relief component 40 can explode in time to release the internal air pressure of the battery cell 100, thereby improving the reliability of the battery cell 100.

[0219] In some embodiments, the outer shell 10 includes two second wall portions 12 connected to the first wall portion 11. The two second wall portions 12 are located on both sides of the electrode assembly 20 along the first direction F1. The distance between the inner surfaces of the two second wall portions 12 is P2. When the battery cell 100 is fully charged, the total thickness dimension of N1 electrode assemblies 20 in the first direction F1 is P1, satisfying: P1 / P2 ≥ 92%.

[0220] When the battery cell 100 is in a fully discharged state, that is, when the battery cell 100 is discharged to be completely empty, the metal ions are released from the negative electrode material and return to the positive electrode material. At this time, the thickness dimension of the electrode assembly 20 in the first direction F1 is P1. In the design of a shell 10 of a certain size, the larger the thickness P1 of the electrode assembly, that is, the more electrode assemblies are filled in the shell 10, the higher the energy density of the battery cell 100. Therefore, P1 / P2 is limited to greater than or equal to ≥92%, thereby improving the energy density of the battery cell 100.

[0221] Please refer to Figure 8 In some embodiments, the first score groove 41 defines at least one predetermined pressure relief area 401, and the pressure relief component 40 is provided with a second score groove 42, which is configured to guide at least a portion of the predetermined pressure relief area 401 to flip to open at least a portion of the predetermined pressure relief area 401.

[0222] The second score groove 42 is a flipping score provided on the pressure relief component 40. When the pressure relief component 40 is split along at least a portion of the first score groove 41, the second score groove 42 can guide the flipping of at least a portion of the predetermined pressure relief area 401. In other words, the second score groove 42 facilitates the flipping of the predetermined pressure relief area 401, making it easier for the predetermined pressure relief area 401 to flip toward the outside of the battery cell 100, thereby quickly opening the predetermined pressure relief area 401. The second score groove 42 can guide the flipping of the predetermined pressure relief area 401 in its entirety or only in a portion.

[0223] During the pressure relief process of the battery cell 100, the pressure relief component 40 can be split along at least part of the first score groove 41, and generally will not be split along the second score groove 42, and the predetermined pressure relief area 401 can be flipped with the second score groove 42 as the flipping axis after the first score groove 41 is split, so that after the predetermined pressure relief area 401 is flipped, the inside of the shell 10 and the outside of the shell 10 are connected to each other and the pressure is relieved.

[0224] The second scored groove 42 can be formed in various ways, such as by stamping, milling, etc. The second scored groove 42 can have various shapes, such as extending along an arcuate trajectory, or extending along a straight trajectory. The cross-sectional shape of the second scored groove 42 can also be various shapes, such as rectangular, trapezoidal, etc.

[0225] By providing the second notched groove 42, the predetermined pressure relief area 401 can be guided to open, thereby improving the opening effect of the predetermined pressure relief area 401 of the pressure relief component 40, and further improving the pressure relief rate of the battery cell 100 when thermal runaway occurs, thereby reducing the risk of fire, explosion, connection failure, etc. caused by untimely pressure relief of the battery cell 100, which is beneficial to improving the reliability of the battery cell 100.

[0226] In some embodiments, the residual thickness of the second score groove 42 is greater than the residual thickness of the first score groove 41 .

[0227] The minimum residual thickness of the second scored groove 42 is the minimum thickness of the remaining portion of the pressure relief component 40 after the second scored groove 42 is provided. The remaining portion may be the bottom wall of the second scored groove 42. The thickness of the bottom wall of the second scored groove 42 may be uniform or uneven. If the thickness of the bottom wall of the second scored groove 42 is uneven, the thickness of the thinnest portion of the bottom wall of the second scored groove 42 is the minimum residual thickness of the second scored groove 42.

[0228] In this embodiment, the strength of the area where the first score groove 41 of the pressure relief component 40 is set can be made smaller than the strength of the area where the second score groove 42 of the pressure relief component 40 is set, so that the pressure relief component 40 can preferentially break along the first score groove 41 to achieve rapid opening of the predetermined pressure relief area 401.

[0229] In some embodiments, the width of the second score groove 42 in the direction perpendicular to the extension direction is greater than the width of the first score groove 41 in the direction perpendicular to the extension direction.

[0230] For example, the second notch groove 42 extends along the third direction F3, and the first groove segment 411 of the first notch groove 41 extends along the third direction F3. In the first direction F1, the width of the groove bottom surface of the second notch groove 42 is greater than the width of the groove bottom surface of the first groove segment 411.

[0231] The second scoring groove 42 can be manufactured and formed in the same manner as the first scoring groove 41 , for example, by integral stamping with a mold, thereby facilitating the formation of the second scoring groove 42 with a larger residual thickness and a wider size.

[0232] Please refer to Figure 8In some embodiments, the first notched groove 41 also includes two second groove sections 412, which are arranged opposite to each other. The first groove section 411 is respectively connected to one end of the two second groove sections 412, and the other ends of the two second groove sections 412 are connected to the two ends of the second notched groove 42. The first groove section 411, the two second groove sections 412 and the second notched groove 42 jointly define a predetermined pressure relief area 401.

[0233] As an example, in Figure 8 In the illustrated embodiment, the first groove segment 411 and the second notched groove 42 are arranged opposite to each other, and the first groove segment 411 and the second notched groove 42 are parallel, the two ends of the first groove segment 411 are respectively connected to the two second groove segments 412, and the two ends of the second notched groove 42 are respectively connected to the two second groove segments 412, and the two second groove segments 412 and the first groove segment 411 and the second notched groove 42 form a closed annular structure; in the second direction F2, the outer edge of the orthographic projection of the annular structure constitutes the predetermined opening boundary of the predetermined pressure relief area 401, that is, the predetermined opening boundary is surrounded by the outer edge of the orthographic projection of the first notched groove 41 and the second notched groove 42 in the second direction F2.

[0234] The first groove section 411 and the second notch groove 42 extend along a straight line. Figure 8 As shown, the first groove segment 411 and the second notched groove 42 extend along the third direction F3. In the first direction F1, the width dimension of the groove bottom surface of the first groove segment 411 is W, and 0.3 mm≤W≤0.8 mm.

[0235] The second slot section 412 can extend along a straight trajectory, for example, along the first direction F1, thereby forming a square predetermined pressure relief area 401; the second slot section 412 can also extend along an arc trajectory, thereby forming a runway-shaped predetermined pressure relief area 401.

[0236] In this embodiment, the first groove section 411, the second notched groove 42 and the two second groove sections 412 are connected to form an annular structure, so that the intersection of the first groove section 411 and the second groove section 412 is weaker and easier to crack and open the predetermined pressure relief area 401 for pressure relief; at the same time, this structure is conducive to increasing the opening area of ​​the predetermined pressure relief area 401, increasing the pressure relief area of ​​the battery cell 100, and improving the pressure relief rate of the battery cell 100.

[0237] In some embodiments, the second scoring groove 42 is parallel to and opposite to the first groove segment 411 , and the second groove segment 412 extends along a straight line and / or an arc trajectory.

[0238] In some examples, the length of the second notched groove 42 is the same as that of the first groove segment 411 , the second groove segment 412 is a straight groove, the second groove segment 412 is perpendicular to the first groove segment 411 , and the second groove segment 412 extends along a straight line, which can reduce the difficulty of forming the second groove segment 412 .

[0239] In some examples, the length of the second notched groove 42 is the same as that of the first groove section 411, and the second groove section 412 extends along an arc trajectory. The second groove section 412 is an arc-shaped groove. Therefore, the pressure relief component 40 is more likely to break along the second groove section 412 when the battery cell 100 is depressurized, thereby achieving a faster opening of the predetermined pressure relief area 401.

[0240] In some examples, the length of the second notched groove 42 is smaller than the length of the first groove segment 411, and each second groove segment includes two parts, one part extending along an arc and the other part extending along a straight line, thereby forming an annular structure. The length of the second notched groove 42 is shortened to a certain extent, and the length of the first notched groove 41 is increased, which is conducive to the faster opening of the predetermined pressure relief area 401.

[0241] like Figure 3 and Figure 4 As shown, in some examples, the housing 10 includes: a shell 101 and an end cover 102 , at least one side of the shell 101 has an opening, the end cover 102 is connected to the shell 101 and is used to close the opening, and the first wall portion 11 is formed on the shell 101 .

[0242] The housing 101 may be a hollow structure with an opening at one end, or may be a hollow structure with openings at two opposite ends. The housing 101 may be in various shapes, such as a prism.

[0243] The end cap 102 is a component that closes the opening of the shell 101 to isolate the internal environment of the battery cell 100 from the external environment. The end cap 102 and the shell 101 together define a storage space for accommodating the electrode assembly 20, the electrolyte and other components. The shape of the end cap 102 can be adapted to the shape of the shell 10. For example, the shell 101 is a rectangular parallelepiped structure, and the end cap 102 is a rectangular plate structure adapted to the shell 10. For another example, the shell 101 is a cylindrical structure, and the end cap 102 is a circular plate structure adapted to the shell 101. The material of the end cap 102 can also be a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the end cap 102 and the shell 101 can be the same or different.

[0244] In an embodiment where the housing 101 is open at one end, one end cap 102 may be provided. In an embodiment where the housing 101 is open at two opposite ends, two end caps 102 may be provided, each of which closes the two openings of the housing 101, and the two end caps 102 and the housing 101 together define a receiving space.

[0245] The shell 101 has a first wall portion 11 and a second wall portion 12, and the pressure relief component 40 is arranged on the shell 101. The pressure relief component 40 can be integrally formed with the shell 101, or can be separately arranged from the shell 101. By arranging the pressure relief component 40 on the shell 101, the structure of the end cover 102 can be simplified, and at the same time, it is convenient to shorten the distance between the pressure relief component 40 and the main body of the electrode assembly 20, thereby shortening the path of the discharge medium flowing to the pressure relief component 40 during pressure relief, shortening the time for the discharge medium to reach the pressure relief component 40, and improving the timeliness of the pressure relief of the battery cell 100, thereby effectively improving the reliability of the battery cell 100.

[0246] In some embodiments, two opposite sides of the housing 101 have openings, and the two end covers 102 are used to close the openings on the corresponding sides.

[0247] In an embodiment where the housing 101 has openings at opposite ends, two end covers 102 may be provided. The two end covers 102 respectively close the two openings of the housing 101, and the two end covers 102 and the housing 101 together define a receiving space. The first wall 11 is located on the housing 101, and the pressure relief component 40 is located between the two openings. An electrical connection portion 30 may be provided on each end cover 102. By providing two openings on the housing 101, the manufacturing and forming of the housing 101 can be facilitated, and it is also convenient for the electrode assembly 20 to lead out the tabs from both ends, thereby facilitating the separation and arrangement of the two electrical connections 30, thereby reducing the risk of short circuiting of the battery cell 100.

[0248] The end cap 102 is provided with an electrical connection portion 30 , which is electrically connected to the positive electrode sheet 21 or the negative electrode sheet 22 , thereby being able to input or output electrical energy of the battery cell 100 .

[0249] In some embodiments, please refer to Figure 7 and Figure 13 The shell 101 has an opening at at least one end along the second direction F2, and the shell 101 includes a second wall portion 12, which is welded to the end cover 102 to form a first connecting portion 51; wherein the second wall portion 12 includes a first area 1111 and a second area 1112 arranged along the second direction F2, the thickness of the first area 1111 is greater than the thickness of the second area 1112, and the first area 1111 is located between the first connecting portion 51 and the second area 1112.

[0250] The housing 101 may have an opening at only one end along the second direction F2, with one end cap 102 correspondingly provided. Alternatively, the housing 101 may have openings at both opposite ends along the second direction F2, with two end caps 102 correspondingly provided. The housing 101 may have various shapes, such as cylindrical or prismatic. The prism may be a triangular prism, a quadrangular prism, a pentagonal prism, a hexagonal prism, etc., and the quadrangular prism may be a cuboid, a cube, etc. The second direction F2 is parallel to the orientation of the opening of the housing 101. In embodiments where the housing 101 is cylindrical, the second direction F2 may be parallel to the axial direction of the housing 101; in embodiments where the housing 101 is prismatic, the second direction F2 may be parallel to the extension direction of the side edges of the housing 101. The first direction F1 is parallel to the thickness direction of the second wall portion 12. In embodiments where the housing 101 is cylindrical, the second wall portion 12 is cylindrical. The radial direction of the housing 101 is the thickness direction of the second wall portion 12, and the first direction F1 is parallel to the radial direction of the housing 101. In embodiments where the housing 101 is prismatic, the second wall portion 12 may be a rectangular plate-like structure. The second direction F2 may form an acute angle, a right angle, or an obtuse angle with the first direction F1.

[0251] The end cap 102 can be welded to the housing 101. The welding of the end cap 102 and the housing 101 can form a connecting portion 5, which can extend along the circumference of the opening of the housing 101. The end cap 102 and the housing 101 are connected and fixed via the connecting portion 5 to achieve a seal between the end cap 102 and the housing 101. The connecting portion 5 is the portion where the weld mark is formed after the end cap 102 and the housing 101 are welded together. The connecting portion 5 can be the portion where the end cap 102 and the housing 101 are welded and fused together.

[0252] The second wall portion 12 in the housing 101 may be one or more. The first connection portion 51 may correspond one-to-one to the second wall portion 12. The first connection portion 51 is the portion with a weld mark formed after the end cover 102 and the second wall portion 12 are welded together. The first connection portion 51 may be the portion where the end cover 102 and the second wall portion 12 are welded and fused together. A portion of the first connection portion 51 is formed on the end cover 102, and another portion of the first connection portion 51 is formed on the second wall portion 12. The second wall portion 12 and the end cover 102 may be formed by seam welding to form the first connection portion 51, or by penetration welding to form the first connection portion 51. The first connection portion 51 may be a portion of the connection portion 5 or the entire connection portion 5. In an embodiment where the shell 101 is cylindrical, there is only one second wall portion 12 in the shell 101, the second wall portion 12 is cylindrical, and the first connecting portion 51 is the connecting portion 5; in an embodiment where the shell 101 is prismatic, the shell 101 may include multiple side walls, and the multiple side walls are arranged along the opening of the shell 101, and at least one side wall of the two side walls arranged opposite to each other along the first direction F1 may be the second wall portion 12, and the first connecting portion 51 is a part of the connecting portion 5.

[0253] The second wall portion 12 may be the wall with the largest outer surface area in the housing 101, or the second wall portion 12 may not be the wall with the largest outer surface area in the housing 101. Taking the housing 101 as a rectangular parallelepiped as an example, the housing 101 may include two second walls 12 and two third walls, the two second walls 12 being arranged opposite each other along the first direction F1, and the two third walls being arranged opposite each other along the third direction F3, with the second direction F2, the first direction F1, and the third direction F3 being perpendicular to each other. The second wall portion 12 may be the wall with the largest outer surface area in the housing 101, such that the outer surface area of ​​the second wall portion 12 is greater than the outer surface area of ​​the third wall portion, or the third wall portion may be the wall with the largest outer surface area in the housing 101, such that the outer surface area of ​​the third wall portion is greater than the outer surface area of ​​the second wall portion 12.

[0254] The first region 1111 may be a region where the thickness of the second wall portion 12 is increased. The first region 1111 is thicker than the second region 1112. The second region 1112 may be a portion of the second wall portion 12 located along the second direction F2 on the side of the first region 1111 away from the first connecting portion 51. The first region 1111 and the first connecting portion 51 may be directly or indirectly connected; the first region 1111 and the second region 1112 may be directly or indirectly connected. The first region 1111 may have a uniform thickness structure or a non-uniform thickness structure; the second region 1112 may have a uniform thickness structure or a non-uniform thickness structure. If at least one of the first region 1111 and the second region 1112 has a non-uniform thickness structure, the maximum thickness of the second region 1112 may be less than or equal to the minimum thickness of the first region 1111, so that the thickness of the first region 1111 is greater than the thickness of the second region 1112.

[0255] The second area 1112 has a first inner surface 11121 facing the inner space of the housing 101 and a first outer surface 11122 facing away from the inner space of the housing 101. The first area 1111 may partially protrude from the first inner surface 11121 and / or the first outer surface 11122. Figure 6 In the illustrated embodiment, a portion of the first region 1111 protrudes from the first inner surface 11121 , and an outer surface of the first region 1111 is coplanar with the first outer surface 11122 .

[0256] The electrode assembly 20 is located within the housing 101 and the end cap 102. The electrode assembly 20 may be a laminated structure or a wound structure. There may be one or more electrode assemblies 20 in the housing 101. If there are multiple electrode assemblies 20, the multiple electrode assemblies 20 may be stacked, for example, along the first direction F1.

[0257] At least a portion of the positive electrode sheet 21 and at least a portion of the negative electrode sheet 22 are stacked along the first direction F1. During cycling, the electrode assembly 20 expands along the first direction F1. The second wall portion 12 is deformed by the expansion force of the electrode assembly 20, which can easily cause fatigue cracking in the area of ​​the second wall portion 12 near the first connection portion 51. In the present application, the thickness of the first region 1111 is set to be greater than the thickness of the second region 1112, and the first region 1111 is positioned between the first connection portion 51 and the second region 1112. This allows the thicker first region 1111 to be closer to the first connection portion 51 than the second region 1112. The first region 1111 strengthens the area of ​​the second wall portion 12 near the first connection portion 51, reducing the risk of fatigue cracking in the area of ​​the second wall portion 12 near the first connection portion 51 due to expansion of the electrode assembly 20, thereby increasing the service life of the battery cell 10.

[0258] In some embodiments, along the third direction F3 , the size of the first region 1111 is larger than the size of the positive electrode sheet 21 and / or the size of the negative electrode sheet 22 , and the second direction F2 , the first direction F1 and the third direction F3 are perpendicular to each other.

[0259] If along the third direction F3, the size of the first area 1111 is larger than the size of the positive electrode sheet 21, the first area 1111 extends beyond at least one end of the positive electrode sheet 21 along the third direction F3; if along the third direction F3, the size of the first area 1111 is larger than the size of the negative electrode sheet 22, the first area 1111 extends beyond at least one end of the negative electrode sheet 22 along the third direction F3.

[0260] In this embodiment, along the third direction F3, the size of the first area 1111 is larger than the size of the positive electrode sheet 21 and / or the size of the negative electrode sheet 22, so that the size of the first area 1111 along the third direction F3 is larger, so that the strength of more areas of the second wall portion 12 along the third direction F3 is enhanced, further reducing the risk of fatigue cracking in the area of ​​the second wall portion 12 near the first connecting portion 51.

[0261] In some embodiments, please refer to Figure 14 , Figure 14Schematic diagram of the connection between the end cap 102 and the electrical connection portion 30 provided in some embodiments of the present application. The battery cell 10 also includes two electrical connection portions 30, which are provided on the end cap 102. The two electrical connection portions 30 have opposite polarities and are both electrically connected to the electrode assembly 20. The end cap 102 is provided with an extraction hole. The electrical connection portion 30 includes a terminal body 31, a first limiting portion 32, and a second limiting portion 33. The terminal body 31 connects the first limiting portion 32 and the second limiting portion 33. The terminal body 31 is provided through the extraction hole. Along the second direction F2, the first limiting portion 32 is located on the side of the end cap 102 facing away from the electrode assembly 20, and the second limiting portion 33 is located on the side of the end cap 102 facing the electrode assembly 20.

[0262] The first limiting portion 32 and the second limiting portion 33 have a limiting function. The first limiting portion 32 and the second limiting portion 33 are respectively connected to the ends of the terminal body 31. The first limiting portion 32 and the second limiting portion 33 cooperate to limit the terminal body 31 from being disengaged from the lead-out hole. Along the second direction F2, the projected area of ​​the first limiting portion 32 and the projected area of ​​the second limiting portion 33 are both larger than the projected area of ​​the terminal body 31. The projected area of ​​the first limiting portion 32 may be larger than the projected area of ​​the second limiting portion 33, or the projected area of ​​the second limiting portion 33 may be larger than the projected area of ​​the first limiting portion 32. The first limiting portion 32, the second limiting portion 33, and the terminal body 31 may be integrally formed, or one of the first limiting portion 32 and the second limiting portion 33 may be integrally formed with the terminal body 31, while the other is separately provided and connected to the terminal body 31.

[0263] As an example, the battery cell 10 may also include a first insulating member 6 and a second insulating member 7, the first insulating member 6 being at least partially arranged between the electrical connection part 30 and the end cover 102 to insulate and isolate the electrical connection part 30 and the end cover 102, and the second insulating member 7 being arranged on the side of the end cover 102 facing the electrode assembly 20 to insulate and isolate the electrode assembly 20 and the end cover 102.

[0264] In this embodiment, the electrical connection portion 30 can be installed on the end cover 102 by riveting, which has low installation difficulty and better economy.

[0265] In some embodiments, the electrode assembly 20 is a laminated structure, and the electrode assembly 20 includes a plurality of positive electrode sheets 21 and a plurality of negative electrode sheets 22 , and the plurality of positive electrode sheets 21 and the plurality of negative electrode sheets 22 are stacked along a first direction F1 .

[0266] As an example, the positive electrode sheets 21 and the negative electrode sheets 22 in the electrode assembly 20 are alternately arranged along the first direction F1 , and a separator is provided between the positive electrode sheets 21 and the negative electrode sheets 22 .

[0267] In this embodiment, the electrode assembly 20 is a laminated electrode assembly, which has a more compact structure and a stronger anti-extrusion capability.

[0268] In some embodiments, the number of negative electrode sheets 22 is greater than the number of positive electrode sheets 21 , and one positive electrode sheet 21 is disposed between two adjacent negative electrode sheets 22 .

[0269] As an example, there is one more negative electrode sheet 22 than positive electrode sheet 21 .

[0270] In some embodiments, each negative electrode plate 22 is provided with a negative electrode tab; and / or each positive electrode plate 21 is provided with a positive electrode tab.

[0271] like Figure 3 and Figure 7 As shown, the first wall portion 11 is used to support the electrode assembly 20 , and the first wall portion 11 is located below the electrode assembly 20 .

[0272] Therefore, the pressure relief component 40 can be arranged at the bottom of the battery cell 100, and an exhaust channel can be provided at the bottom of the battery cell 100. The exhaust channel and the pressure relief component 40 can be connected, so that when the battery cell 100 has thermal runaway, the high-temperature and high-pressure flue gas can be discharged into the exhaust channel through the pressure relief component 40 at the bottom, and then discharged to the outside.

[0273] In some embodiments, the material of the first wall portion includes aluminum alloy, and the shell of the outer shell has the same material as the first wall portion. The aluminum alloy here can be three-series aluminum, which makes the shell have the advantages of light weight, safety, easy processing and good corrosion resistance.

[0274] In some embodiments, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector along the thickness direction of the negative electrode plate and containing a negative electrode active material, the negative electrode active material includes a silicon-based material, and the mass content of silicon element in the silicon-based material is 0.3% to 10.0%, based on the total mass of the negative electrode active material.

[0275] In the above technical solution, by adjusting the mass content of silicon elements in the silicon-based material within the above range, the capacity of the negative electrode active material can be increased, thereby improving the energy density of the battery cell; by increasing the energy density, the expansion force will not be too large, and the damage, cracking and leakage of weak areas caused by the expansion and deformation of the electrode assembly can be reduced.

[0276] In some embodiments, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector along the thickness direction of the negative electrode plate and containing a negative electrode active material. The discharge capacity per unit area of ​​the negative electrode film layer is 2.0 mAh / cm 2 Up to 5.0 mAh / cm 2 .

[0277] The discharge capacity per unit area of ​​the negative electrode film layer refers to the actual lithium-insertable capacity of the negative electrode active material. The test method is as follows: disassemble the battery in a PRS340 / 11-119-11 Braun glove box, remove the negative electrode sheet, and assemble it into a CR2430 model semi-button battery with a negative electrode and lithium sheet. The area of ​​the negative electrode sheet used is f mm 2 , wherein the electrolyte is a solution of 1 mol / L LiPF6 in EC / EMC / DEC=3 / 5 / 2 (mass ratio); the assembled half-button battery is then left to stand for 3 hours, and the test is carried out at 25°C. It is discharged (discharge) in the voltage range of 2V-0V using 0.1C to insert lithium, and then charged (discharge) to 2V using 0.05C, and the cycle is repeated twice. The discharge capacity of the second cycle is recorded as Z mAh. The actual battery design has a negative electrode piece length of h mm and a width of i mm. The number of surfaces of the negative electrode active material coated on the negative electrode current collector is d, then the negative electrode lithium insertion capacity = Z / f*h*i*d.

[0278] The discharge capacity per unit area of ​​the negative electrode film layer can be selected as 2mAh / cm 2 Up to 5mAh / cm 2 For example, the discharge capacity per unit area of ​​the negative electrode film is 2.0 mAh / cm 2 , 2.1mAh / cm 2 , 2.2mAh / cm 2 , 2.3mAh / cm 2 , 2.4mAh / cm 2 , 2.5mAh / cm 2 , 2.6mAh / cm 2 , 2.7mAh / cm 2 , 2.8mAh / cm 2 , 2.9mAh / cm 2 、3.0mAh / cm 2 、3.1mAh / cm 2 、3.2mAh / cm 2 、3.3mAh / cm 2 、3.4mAh / cm 2 、3.5mAh / cm 2 、3.6mAh / cm 2 、3.7mAh / cm 2 、3.8mAh / cm 2 、3.9mAh / cm 2 、4.0mAh / cm 2 , 4.1mAh / cm 2 , 4.2mAh / cm 2 , 4.4mAh / cm 2, 4.8mAh / cm 2 、5.0mAh / cm 2 Any point value or any range of values ​​between them.

[0279] When the discharge capacity per unit area of ​​the negative electrode film layer is within the above range, there are sufficient sites in the negative electrode film layer for lithium embedding, which can reduce the risk of lithium plating; and it is conducive to fast charging, the expansion force is not too large, and the damage, cracking and leakage of weak areas caused by the expansion and deformation of the electrode assembly are reduced.

[0280] In some embodiments, the thickness of the negative electrode film layer is T1, 9μm≤T1≤75μm, T1 can be selected from 9μm to 75μm, and the thickness T1 of the negative electrode film layer can be any point value among 9μm, 15μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 75μm or a range value between any two of them.

[0281] The battery 1000 according to the second aspect embodiment of the present application includes the battery cell 100 according to the above-mentioned first aspect embodiment of the present application. By adopting the above-mentioned battery cell 100, the risk of fatigue cracking can be reduced to a certain extent. At the same time, when the battery cell 100 has thermal runaway, the pressure relief component 40 can explode in time to release the internal air pressure of the battery cell 100, thereby improving the reliability of the battery.

[0282] According to an embodiment of the third aspect of the present application, an electrical device includes the battery 1000 according to the embodiment of the second aspect of the present application, and the battery 1000 is used to provide power to the electrical device. Thus, by using the battery 1000, the safety and reliability of the electrical device can be improved.

[0283] Alternatively, as Figure 1 As shown, when battery 1000 is used in a vehicle, it can be installed at the bottom, front, or rear of the vehicle. Battery 1000 can be used to power the vehicle, for example, as an operating power source for the vehicle. The vehicle may also include a controller and a motor. The controller is used to control battery 1000 to power the motor, for example, to meet the vehicle's starting, navigation, and driving needs.

[0284] A battery 1000 and a vehicle having the same according to a specific embodiment of the present application will be described below with reference to the accompanying drawings.

[0285] like Figure 1 As shown, the battery 1000 is located at the bottom of the vehicle and Figure 2 As shown, the battery 1000 includes a plurality of battery cells 100. Figure 3As shown, each battery cell 100 includes a shell 10 and two electrode assemblies 20. The shell 10 is provided with an electrical connection portion 30 and a pressure relief component 40. The electrical connection portion 30 and the pressure relief component 40 are located on different sides of the shell 10; the electrode assembly 20 is arranged in the shell 10.

[0286] The electrode assembly 20 has a flat area 23. The number of layers of positive electrode sheets 21 stacked in the flat area 23 of each electrode assembly 20 is N2. The total number of layers of positive electrode sheets 21 stacked in the flat area 23 is 2*N2≥50. The area of ​​the outer surface of the flat area 23 perpendicular to the first direction F1 is S, and S≥8000mm 2 .

[0287] like Figure 4 As shown, the housing 10 is generally in the shape of a quadrangular prism, has a simple structure, and is easy to form. The housing 10 has a first wall portion 11, which is located on one side of the electrode assembly 20 in the second direction F2. The first wall portion 11 extends along the third direction F3. The thickness of the first wall portion 11 in the second direction F2 is H, and H is ≤ 2.5 mm.

[0288] like Figure 11 and Figure 12 As shown, the first wall portion 11 is provided with a pressure relief hole 111, and the pressure relief component 40 can be installed at the pressure relief hole 111 of the first wall portion 11 by welding or the like, as shown in FIG. Figure 8 As shown, the pressure relief component 40 is a component independent of the housing 10. The pressure relief component 40 and the housing 10 can be produced and assembled separately. A patch 60 can also be provided on the outside of the pressure relief component 40. The patch 60 cooperates with the housing 10 to protect the pressure relief component 40.

[0289] like Figure 8 As shown, the pressure relief component 40 is provided with a first scoring groove 41 and a second scoring groove 42 , and the residual thickness at the first scoring groove 41 is smaller than the residual thickness at the second scoring groove 42 .

[0290] like Figures 8-10 As shown, the pressure relief component 40 is configured to rupture along at least a portion of the first scored groove 41 when the battery cell 100 releases pressure. Specifically, the first scored groove 41 includes a first groove segment 411 and two second groove segments 412. The first groove segment 411 and the second scored groove 42 are disposed opposite each other and extend along the third direction F3. The two second groove segments 412 are disposed opposite each other and form an arc-shaped groove. The two ends of each first groove segment 411 are respectively connected to the two second groove segments 412. The two second groove segments 412, the first groove segment 411, and the second scored groove 42 form a closed annular structure.

[0291] In the first direction F1, the width dimension of the groove bottom surface of the first groove segment 411 is A, 0.4mm≤A≤0.7mm, and the first groove segment 411 has a minimum residual thickness D1, 0.12mm≤D1≤0.25mm. The groove bottom surface dimension and minimum residual thickness of the second groove segment 412 are the same as those of the first groove segment 411.

[0292] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: N1 electrode assemblies, each comprising at least one positive electrode sheet, at least one negative electrode sheet, and at least one separator, wherein the positive electrode sheet, the negative electrode sheet, and the separator are stacked to form a flat region, and at least a portion of the positive electrode sheet, at least a portion of the negative electrode sheet, and at least a portion of the separator are stacked along a first direction in the flat region; The number of layers of the positive electrode sheets stacked in the straight area of ​​each electrode assembly is N2, the straight area has an outer surface perpendicular to the first direction, and the area of ​​the outer surface is S, N1≥1, N2≥1, N1*N2≥50, and S≥8000mm 2 ; a housing for accommodating N1 electrode assemblies, the housing comprising a first wall portion, the first wall portion being located on one side of the electrode assembly in a second direction, the second direction being a thickness direction of the first wall portion and being perpendicular to the first direction, the first wall portion having a thickness dimension H in the second direction, H being ≤ 2.5 mm; A pressure relief component is provided on the first wall portion, and the pressure relief component is provided with a first notch groove. The pressure relief component is configured to be able to split along at least a portion of the first notch groove when the battery cell is depressurized, and the first notch groove includes a first groove segment extending along a straight trajectory, the length direction of the first groove segment is perpendicular to the first direction, the size of the groove bottom surface of the first groove segment in the first direction is A, and the minimum residual thickness of the first groove segment is D1, satisfying: 0.3mm≤A≤0.8mm, 0.1mm≤D1≤0.28mm.

2. The battery cell according to claim 1, wherein: Meet the following requirements: 0.4mm≤A≤0.7mm, 0.12mm≤D1≤0.25mm.

3. The battery cell according to claim 1, wherein: The pressure relief component includes a main body and a pressure relief portion, the main body is connected to the first wall portion, the thickness of the pressure relief portion is smaller than the thickness of the main body, the first notch groove is provided in the pressure relief portion, and the thickness dimension of the pressure relief portion in the second direction is D2, satisfying: 0.182mm≤D2≤0.4mm.

4. The battery cell according to claim 3, characterized in that 0.2mm≤D2≤0.3mm.

5. The battery cell according to claim 1, characterized in that The pressure relief component is provided with a pressure relief portion, the first notch groove is provided in the pressure relief portion, and the thickness dimension of the pressure relief portion in the second direction is D2, which satisfies: 0.55≤D1 / D2≤0.

85.

6. The battery cell according to claim 1, characterized in that The first wall portion has a pressure relief hole, the pressure relief component is installed in the pressure relief hole, and the area of ​​the pressure relief hole projected along the second direction is W, 400mm 2 ≤W≤1400mm 2 .

7. The battery cell according to claim 6, characterized in that 600mm 2 ≤W≤1200mm 2 。 8. The battery cell according to claim 1, wherein: The first wall portion has a pressure relief hole, and the pressure relief component is installed in the pressure relief hole. The size of the pressure relief hole in the first direction is B, and the size of the pressure relief hole in the third direction is L. The third direction is perpendicular to the first direction and the second direction, and satisfies: 1.5≤L / B≤5.

9. The battery cell according to claim 8, characterized in that 2≤L / B≤4.

10. The battery cell according to claim 1, characterized in that The width of the first wall portion along the first direction is D3, which satisfies the following conditions: 0.008≤A / D3≤0.019, 20 mm≤D3≤80 mm.

11. The battery cell according to claim 1, characterized in that The outer shell includes two second wall portions connected to the first wall portion, and the two second wall portions are respectively located on both sides of the electrode assembly along the first direction. The distance between the inner surfaces of the two second wall portions is P2. When the battery cells are fully discharged, the total thickness dimension of N1 electrode assemblies in the first direction is P1, satisfying: P1 / P2≥92%.

12. The battery cell according to claim 1, wherein The first score groove defines at least one predetermined pressure relief area, and the pressure relief component is provided with a second score groove, which is configured to guide at least a portion of the predetermined pressure relief area to flip over to open at least a portion of the predetermined pressure relief area.

13. The battery cell according to claim 12, characterized in that: The residual thickness of the second scoring groove is greater than the residual thickness of the first scoring groove.

14. The battery cell according to claim 12, characterized in that The width of the second scoring groove in a direction perpendicular to the extension direction is greater than the width of the first scoring groove in a direction perpendicular to the extension direction.

15. The battery cell according to claim 12, characterized in that The first notched groove also includes two second groove sections, which are arranged opposite to each other. The two ends of the first groove section are respectively connected to one end of the two second groove sections, and the other ends of the two second groove sections are connected to the two ends of the second notched groove. The first groove section, the two second groove sections and the second notched groove jointly define a predetermined pressure relief area.

16. The battery cell according to claim 15, characterized in that The second notch groove is parallel to and opposite to the first groove segment, and the second groove segment extends along a straight line and / or an arc track.

17. The battery cell according to any one of claims 1 to 16, characterized in that: The housing includes a shell and an end cover. At least one side of the shell has an opening. The end cover is connected to the shell and is used to close the opening. The first wall portion is formed on the shell.

18. The battery cell according to claim 17, characterized in that Two opposite sides of the shell are each provided with an opening, and the two end covers are used to close the openings on the corresponding sides.

19. The battery cell according to claim 17, characterized in that At least one end of the housing along the second direction has an opening, and the housing includes a second wall portion, and the second wall portion is welded to the end cover to form a first connecting portion; It is characterized in that the second wall portion includes a first area and a second area arranged along the second direction, the thickness of the first area is greater than the thickness of the second area, and the first area is located between the first connecting portion and the second area.

20. The battery cell according to claim 19, characterized in that Along the third direction, the size of the first region is larger than the size of the positive electrode sheet and / or the size of the negative electrode sheet, and the first direction, the second direction and the third direction are perpendicular to each other.

21. The battery cell according to claim 17, wherein: The battery cell further includes an electrical connection portion, which is provided on the end cover and electrically connected to the electrode assembly; The end cover is provided with a lead-out hole, and the electrical connection part includes a terminal body, a first limiting part and a second limiting part. The terminal body connects the first limiting part and the second limiting part, and the terminal body is passed through the lead-out hole. Along the first direction, the first limiting part is located on the side of the end cover away from the electrode assembly, and the second limiting part is located on the side of the end cover facing the electrode assembly.

22. The battery cell according to claim 1, characterized in that The electrode assembly is a laminated structure, comprising a plurality of positive electrode sheets and a plurality of negative electrode sheets, wherein the plurality of positive electrode sheets and the plurality of negative electrode sheets are stacked along the first direction.

23. The battery cell according to claim 22, characterized in that The number of the negative electrode sheets is greater than the number of the positive electrode sheets, and one positive electrode sheet is arranged between two adjacent negative electrode sheets.

24. The battery cell according to claim 22, characterized in that Each of the negative electrode plates is provided with a negative electrode tab; and / or each of the positive electrode plates is provided with a positive electrode tab.

25. The battery cell according to claim 1, characterized in that The first wall portion is used to support the electrode assembly and is located below the electrode assembly.

26. The battery cell according to claim 1, characterized in that The negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector along the thickness direction of the negative electrode plate and containing a negative electrode active material. The discharge capacity per unit area of ​​the negative electrode film layer is 2.0 mAh / cm 2 Up to 5.0 mAh / cm 2 .

27. The battery cell according to claim 26, characterized in that The thickness of the negative electrode film layer is T1, 9 μm≤T1≤75 μm.

28. A battery, characterized in that: The invention comprises a battery cell according to any one of claims 1 to 27.

29. An electrical device, characterized in that: The battery according to claim 28 is used to provide electrical energy to the electrical device.

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