Cylindrical battery monomer, battery device and electric equipment

Abstract

The invention discloses a cylindrical battery monomer, a battery device and electric equipment. The cylindrical battery monomer comprises an electrode assembly and a shell, the shell comprises a side wall, the electrode assembly is accommodated in the shell, and the side wall surrounds the electrode assembly; wherein the volume energy density of the cylindrical battery monomer is EWh / L, the size of the shell is Hmm in the axial direction of the cylindrical battery monomer, the minimum thickness of the side wall is Dmm, and E, H and D meet the following conditions: 300 Wh / L < = E < = 1500 Wh / L, 120 mm < = H < = 300 mm, and 0.3 mm < = D < = 1 mm. According to the cylindrical battery cell provided by the embodiment of the invention, the reliability can be improved.

Description

Technical Field

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

[0002] With the development of new energy technology, batteries are used more and more widely, for example, in mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc.

[0003] The development of battery technology must take into account multiple design factors at the same time. For example, how to improve the reliability of cylindrical battery cells is an important research direction in the battery field. Summary of the invention

[0004] The present application provides a cylindrical battery cell, a battery device and an electrical device, which can improve the reliability of the cylindrical battery cell.

[0005] In a first aspect, the present application provides a cylindrical battery cell, comprising an electrode assembly and a shell; the shell comprises a side wall, the electrode assembly is accommodated in the shell, and the side wall surrounds the electrode assembly; wherein the volume energy density of the cylindrical battery cell is EWh / L, and in the axial direction of the cylindrical battery cell, the size of the shell is H mm, the minimum thickness of the side wall is D mm, and E, H, and D satisfy: 300 Wh / L ≤ E ≤ 1500Wh / L, 120mm≤ H ≤ 300mm, 0.3mm≤ D≤1mm.

[0006] In the technical solution of the embodiment of the present application, the volume energy density of the battery cell, its axial size and the thickness of the side wall of the shell are obtained respectively, and the values ​​of the three are made to satisfy a certain parameter range respectively, thereby optimizing the structural proportions of the cylindrical battery cell. When thermal runaway occurs, the possibility that the cylindrical battery cell can be successfully depressurized through the pressure relief mechanism is increased, and the possibility of the outer shell rupture due to reasons such as the inability to discharge gas in time and the air pressure inside the shell exceeding the bearing capacity of the battery shell is reduced, thereby improving the reliability of the cylindrical battery cell.

[0007] According to some embodiments of the present application, E, H, and D satisfy: 500 Wh / L ≤ E ≤ 800Wh / L, 150 mm ≤ H ≤ 220 mm, 0.5 mm ≤ D ≤ 0.7 mm. The parameter range of the cylindrical battery cell is further limited.

[0008] According to some embodiments of the present application, E, H, and D satisfy: 150000 Wh / L≤ E×H / D ≤375000 Wh / L. By limiting the ratio among volume energy density, axial dimension, and sidewall thickness, the possibility of pressure relief through the pressure relief mechanism is further improved.

[0009] According to some embodiments of the present application, 150000 Wh / L ≤ E×H / D ≤ 300000 Wh / L. The ratio range is further reduced to reduce the possibility and degree of deformation of the shell after pressure relief.

[0010] According to some embodiments of the present application, 150000 Wh / L ≤ E×H / D ≤ 250000 Wh / L. The ratio range is further reduced to reduce the possibility of shell deformation after pressure relief.

[0011] According to some embodiments of the present application, 150000 Wh / L ≤ E×H / D ≤ 250000 Wh / L. The ratio of the product of volume energy density and length to the wall thickness is further reduced, thereby further reducing the possibility of sidewall rupture during thermal runaway.

[0012] According to some embodiments of the present application, in the radial direction of the cylindrical battery cell, the size of the cylindrical battery cell is A, 10 mm ≤ A ≤ 100 mm, so that the cylindrical battery cell can have both a large capacity and high reliability.

[0013] According to some embodiments of the present application, 300Wh / L ≤ E ≤ 1500Wh / L. The reliability of the cylindrical battery cell is improved on the basis of having a suitable volume energy density.

[0014] According to some embodiments of the present application, the housing includes a shell and an end cap, the shell includes a side wall, the side wall encloses an opening, the end cap covers the opening and is connected to the side wall; the cylindrical battery cell also includes a pressure relief mechanism, and the pressure relief mechanism is arranged on the end cap. The cylindrical battery cell may include a shell having a side wall and a pressure relief mechanism arranged on the end cap, so that it can release pressure through the pressure relief mechanism in the event of thermal runaway.

[0015] According to some embodiments of the present application, the side wall includes a main body area and a thickened area, the thickness of the thickened area is greater than the thickness of the main body area, the thickened area is arranged on at least one side of the main body area in the axial direction and encloses an opening; the thickness of at least part of the main body area is D mm, 0.3 mm ≤ D ≤ 1 mm. The reliability of the side wall can be further improved by partially thickening.

[0016] According to some embodiments of the present application, the end cap is connected to the thickened area by welding. By welding in the thicker area, the connection between the end cap and the housing can be stable and reliable.

[0017] According to some embodiments of the present application, in the axial direction, the ratio of the size of the main body area to the size of the side wall is 0.5-0.98, so that the main body area occupies a larger size proportion, thereby reducing the overall weight and volume of the housing while improving the structural strength and connection stability.

[0018] According to some embodiments of the present application, the thickened area is arranged to protrude from the main area in a direction close to the central axis of the cylindrical battery cell, so that the outer peripheral surface of the cylindrical battery cell has a more regular shape, which facilitates the arrangement of multiple cylindrical battery cells close to each other and reduces the gap when in use.

[0019] According to some embodiments of the present application, the housing includes two end covers, the side wall is provided with openings at two opposite ends in the axial direction, the two end covers are provided in one-to-one correspondence with the openings and cover the openings respectively, and the end covers are welded to the side wall; the housing also includes a pressure relief mechanism, and at least one end cover is provided with a pressure relief mechanism. The housing can adopt a structural form in which end covers are provided at both ends, so that the electrode assembly is easy to install.

[0020] According to some embodiments of the present application, the side wall includes a main body area and two thickened areas, the thickness of the thickened area is greater than the thickness of the main body area, and the two thickened areas are respectively arranged on two opposite sides of the main body area in the axial direction. Both ends to be connected to the end cap are set to have a larger thickness, thereby improving the connection strength of the two ends and the reliability of the cylindrical battery cell as a whole.

[0021] According to some embodiments of the present application, in the axial direction, the distance between the surfaces of the two end covers facing away from each other is H mm. The distance between the outer surfaces of the two end covers is recorded as the dimension H of the housing in the axial direction.

[0022] According to some embodiments of the present application, the housing includes a shell and an end cover, the shell includes a side wall and an end wall, the end wall and the end cover are axially opposite, and the thickness of the end wall is greater than the thickness of the side wall. The housing may be provided with an opening and an end cover only in one section, and the end wall on the opposite side may be thickened to improve the structural strength at the end wall.

[0023] According to some embodiments of the present application, the side wall is made of steel, so that the entire housing has a higher structural strength.

[0024] In a second aspect, a battery device is provided according to an embodiment of the present application, comprising a box and a plurality of cylindrical battery cells according to any one of the embodiments of the first aspect, wherein the cylindrical battery cells are arranged in the box.

[0025] In a third aspect, according to an embodiment of the present application, an electrical device is proposed, comprising a battery device in any embodiment of the second aspect, and the battery device is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings: Figure 1 A simplified schematic diagram of a vehicle provided for some embodiments of the present application; Figure 2 An exploded schematic diagram of a battery device provided in some embodiments of the present application; Figure 3 An exploded schematic diagram of a battery module provided in some embodiments of the present application; Figure 4 A schematic diagram of the structure of a cylindrical battery cell provided in some embodiments of the present application; Figure 5 An exploded schematic diagram of a cylindrical battery cell provided in some embodiments of the present application; Figure 6 A partial cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of the present application.

[0027] Reference numerals: 1000-Vehicles; 100-cylindrical battery cell; 200-battery device; 300-controller; 400-motor; 500-battery module; 10-electrode assembly; 20-housing; 30-pressure relief mechanism; 40-box; 21-side wall; 22-housing; 23-end cover; 41-first box body; 42-second box body; 43-accommodating portion; 211-main body area; 212-thickened area; 221-opening; X-axis direction. DETAILED DESCRIPTION

[0028] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0030] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0031] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0032] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0033] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0034] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0035] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0036] 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.

[0037] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiments of the present application.

[0038] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0039] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0040] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0041] As an example, the positive electrode current collector may be a metal foil or a composite current collector.

[0042] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0043] As an example, the negative electrode current collector may be a metal foil, a foamed metal, or a composite current collector.

[0044] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0045] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0046] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.

[0047] 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.

[0048] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0049] 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 stability and mechanical stability can be selected.

[0050] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0051] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. The electrolyte can be liquid, gel or solid.

[0052] In some embodiments, the electrode assembly is provided with tabs, which can lead current out of the electrode assembly. The tabs include a positive tab and a negative tab.

[0053] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0054] In some embodiments, the housing may be provided with functional components such as electrode terminals, etc. The electrode terminals may be used to electrically connect to the electrode assembly to output or input electrical energy of the battery cell.

[0055] The battery device mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include a plurality of battery cells, and the plurality of battery cells are connected in series, in parallel or in mixed connection through a busbar.

[0056] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells.

[0057] As an example, the battery cell assembly may be a battery module, which is formed by arranging and fixing a plurality of battery cells to form an independent module. As an example, the battery module may be formed by bundling a plurality of battery cells by a cable tie.

[0058] In some embodiments, the battery device may be a battery pack, which includes a case and one or more battery cell assemblies, wherein the battery cell assemblies are accommodated in the case.

[0059] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box by fixing the battery module in the box.

[0060] As an example, the battery cell assembly may also be housed in the case by directly fixing a plurality of battery cells to the case.

[0061] As an example, the box may include a first box and a second box. The first box and the second box are buckled together to form a closed space inside the box to accommodate the battery cell assembly. The closed here means covered or closed, which can be sealed or unsealed. The first box can be a top cover or a bottom plate.

[0062] As an example, the box body may include a top cover, a frame and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that a closed space is formed inside the box body to accommodate the battery cell assembly.

[0063] 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.

[0064] In a cylindrical battery cell, it usually includes a shell and an electrode assembly and electrolyte disposed in the shell. The electrode assembly in the cylindrical battery cell is usually made by winding, and its axial direction is the same as the axial direction of the cylindrical battery cell as a whole, so that the electrode assembly fills the shell, and then forms an external electrical connection through components such as adapters and electrode terminals. At the same time, a pressure relief mechanism is usually provided at the top or bottom of the cylindrical battery cell to relieve pressure when thermal runaway occurs.

[0065] However, since the shape of the inner cavity of the shell of a cylindrical battery cell is usually the same as or similar to the shape of the outer peripheral surface of the electrode assembly, the electrode assembly is filled more fully in the shell. Accordingly, the exhaust passage used for exhaust in the event of thermal runaway is relatively narrow, especially for cylindrical battery cells with larger axial dimensions, which have longer exhaust passages and are more prone to poor exhaust. Therefore, when a battery cell has a thermal runaway problem, problems such as poor gas flow and the air pressure in the shell exceeding the bearing capacity of the shell are likely to occur, which ultimately leads to the battery cell bursting at the side wall and being unable to be depressurized by the pressure relief mechanism.

[0066] In view of this, an embodiment of the present application provides a technical solution, which reduces the possibility of side wall rupture in the event of thermal runaway and improves the reliability of cylindrical battery cells by adjusting the relationship between the length dimension of the cylindrical battery cell, the thickness of the side wall of the shell, and the volume energy density.

[0067] The technical solutions described in the embodiments of the present application are applicable to various electrical devices that use battery cells, such as mobile phones, portable devices, laptop computers, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, for example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.

[0068] The battery cells described in the embodiments of the present application are not limited to the electrical equipment described above, but for the sake of simplicity, the following embodiments are described using electric vehicles as examples.

[0069] See also Figure 1 , Figure 1 A simple schematic diagram of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery device 200 may be provided inside the vehicle 1000, and specifically, for example, a battery device 200 may be provided at the bottom, front or rear of the vehicle 1000. The battery device 200 may be used to power the vehicle 1000, for example, the battery device 200 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 300 and a motor 400, and the controller 300 is used, for example, to control the battery to power the motor 400. The battery device 200 may be used for starting and navigating the vehicle 1000, and of course, the battery may also be used to drive the vehicle 1000, replacing or partially replacing fuel or natural gas to provide drive for the vehicle 1000.

[0070] Please also read Figure 2 and Figure 3 , Figure 2 An exploded schematic diagram of a battery device 200 provided in some embodiments of the present application, Figure 3 Schematic diagram of an explosion of a battery module 500 provided in some embodiments of the present application. Figure 2 and Figure 3 As shown, the battery device 200 includes a case 40 and a cylindrical battery cell 100 , and the cylindrical battery cell 100 is accommodated in the case 40 .

[0071] The box body 40 is used to accommodate the cylindrical battery cell 100, and the box body 40 can be a variety of structures. In some embodiments, the box body 40 may include a first box body portion 41 and a second box body portion 42, the first box body portion 41 and the second box body portion 42 cover each other, and the first box body portion 41 and the second box body portion 42 jointly define a receiving portion 43 for accommodating the cylindrical battery cell 100. The second box body portion 42 may be a hollow structure with one end open, the first box body portion 41 is a plate-like structure, and the first box body portion 41 covers the open side of the second box body portion 42 to form a box body 40 with a receiving portion 43; the first box body portion 41 and the second box body portion 42 may also be a hollow structure with one side open, and the open side of the first box body portion 41 covers the open side of the second box body portion 42 to form a box body 40 with a receiving portion 43. Of course, the first box body portion 41 and the second box body portion 42 may be in a variety of shapes, such as a cylinder, a cuboid, etc.

[0072] In the battery device 200, there can be one or more cylindrical battery cells 100. If there are more than one cylindrical battery cells 100, the multiple cylindrical battery cells 100 can be connected in series, in parallel, or in mixed connection. Mixed connection means that the multiple cylindrical battery cells 100 are both connected in series and in parallel. The multiple cylindrical battery cells 100 can be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple cylindrical battery cells 100 is accommodated in the box 40; of course, it is also possible that the multiple cylindrical battery cells 100 are first connected in series, in parallel, or in mixed connection to form a battery module 500, and the multiple battery modules 500 are then connected in series, in parallel, or in mixed connection to form a whole, and accommodated in the box 40.

[0073] In some embodiments, there are multiple cylindrical battery cells 100, which are first connected in series, in parallel, or in series to form a battery module 500. The multiple battery modules 500 are then connected in series, in parallel, or in series to form a whole, and are contained in the box 40.

[0074] Next, combine with Figure 4 To Attachment Figure 6 The structures of the cylindrical battery cell 100, the battery device 200 and the electric equipment are described.

[0075] Please also read Figure 4 and Figure 5 , Figure 4 A schematic diagram of the structure of a cylindrical battery cell provided in some embodiments of the present application, Figure 5 An exploded schematic diagram of a cylindrical battery cell provided in some embodiments of the present application.

[0076] In a first aspect, the present application provides a cylindrical battery cell 100, comprising an electrode assembly 10 and a shell 20; the shell 20 comprises a side wall 21, the electrode assembly 10 is accommodated in the shell 20, and the side wall 21 surrounds the electrode assembly 10; wherein the volume energy density of the cylindrical battery cell 100 is E Wh / L, in the axial direction X of the cylindrical battery cell 100, the size of the shell 20 is H mm, the minimum thickness of the side wall 21 is D mm, and E, H, and D satisfy: 300 Wh / L ≤ E ≤ 1500Wh / L, 120mm≤ H ≤ 300mm, 0.3mm≤ D≤1mm.

[0077] The embodiment of the present application provides a cylindrical battery cell 100, which includes a shell 20 and an electrode assembly 10 arranged in the shell 20. The shell 20 may be provided with a pressure relief mechanism 30, electrode terminals and other components required for the operation of the cylindrical battery cell 100, and a current collecting plate, electrolyte and the like may also be correspondingly provided in the shell 20.

[0078] Optionally, the cross-sectional shape formed by the shell 20 in the cylindrical battery cell 100 in the cross section perpendicular to its own axial direction X can be circular or elliptical, which includes the top and bottom located at both ends of the electrode assembly 10 in the axial direction X, and the side wall 21 arranged around the electrode assembly 10, and the side wall 21 can have the same or similar thickness dimensions everywhere; or, the side wall 21 can have the same or similar thickness dimensions in most areas, and required components or reinforcement structures are arranged in other parts.

[0079] Optionally, the electrode assembly 10 may be a cylindrical structure formed by winding, and may have a central hole extending along the axial direction X at the position of the central axis. An insulating structure or other protective film layer may be optionally provided between the electrode assembly 10 and the housing 20, and a gap may be left between the electrode assembly 10 and the housing 20 for exhaust in a thermal runaway state.

[0080] On this basis, the volume energy density of the cylindrical battery cell 100 is recorded as E Wh / L, the dimension of the cylindrical battery cell 100 in its own axial direction X is recorded as H mm, and the minimum thickness of the housing 20 is recorded as D mm. The axial dimension of the cylindrical battery cell 100, that is, the length of the cylindrical battery cell 100, can be detected by a ruler or the like. In an embodiment where the two opposite ends of the cylindrical battery cell 100 in the axial direction X are not parallel to each other, multiple measurements can be performed and the average value can be calculated, and the average value can be recorded as the length dimension H.

[0081] At least some areas of the housing 20 may have the same or similar thickness, so that the structural strength of each area is relatively uniform, which is convenient for dispersing stress. Similar to the measurement of the length dimension, when measuring the minimum thickness of the housing 20, a region with the smallest thickness compared with other regions and the same or similar thickness at each location may be selected for measurement. Specifically, multiple locations may be selected from the region for measurement and the average value may be calculated, and then the average value may be recorded as the minimum thickness dimension D.

[0082] The volume energy density E of the battery can be obtained by first obtaining the discharge energy and platform voltage of the cylindrical battery cell 100 through cyclic charge and discharge and multiple measurements and taking the average value. Then, the volume of the cylindrical battery cell 100 can be measured by CT scanning or the "drainage method", and the volume energy density E can be obtained by calculation.

[0083] In the cylindrical battery cell 100, the gas production efficiency when thermal runaway occurs is positively correlated with parameters such as its own volume energy density E, while the maximum internal air pressure that its shell 20 can bear is positively correlated with parameters such as the minimum wall thickness D of the side wall 21. The probability that the gas can flow smoothly to the pressure relief mechanism 30 when thermal runaway occurs is negatively correlated with the length dimension H of the shell 20.

[0084] On this basis, the above three parameters are respectively satisfied as follows: 300 Wh / L ≤ E ≤ 1500Wh / L, 120mm ≤ H ≤ 300mm, and 0.3mm ≤ D ≤ 1mm, which can effectively improve the possibility of smooth pressure relief of the cylindrical battery cell 100 in the thermal runaway state. Among these three parameters, as the energy density E and the length H of the cylindrical battery cell 100 increase, the pressure generated by the internal gas production in the thermal runaway state and the possibility of poor gas flow also increase accordingly, and as the wall thickness D increases, the structural strength of the housing 20, that is, the ability to resist the above pressure, also increases accordingly.

[0085] Thus, by making E ≤ 1500Wh / L, H ≤ 300mm and 0.3mm ≤ D, the possibility of smooth pressure relief of the cylindrical battery cell by the pressure relief mechanism in the thermal runaway state can be increased, and the possibility of rupture or explosion of the housing 20 can be reduced. At the same time, by making 300 Wh / L ≤ E, 120mm ≤ H and D ≤ 1mm, the cylindrical battery cell 100 can have a larger capacity and a higher energy density while improving the reliability during the pressure relief process.

[0086] Optionally, the parameter ranges of the volume energy density E, the length dimension H, and the wall thickness D of the side wall 21 proposed in the embodiment of the present application can be applied to the cylindrical battery cell 100 whose length dimension in the axial direction X and the volume energy density are within the aforementioned range, and can achieve accurate and reliable results. At the same time, by limiting the size and volume energy density of the cylindrical battery cell 100 to the aforementioned range, the cylindrical battery cell 100 can have both a larger capacity and higher reliability.

[0087] In some optional embodiments, E, H, and D satisfy: 500 Wh / L ≤ E ≤ 800Wh / L, 150 mm ≤ H ≤ 220 mm, and 0.5 mm ≤ D ≤ 0.7 mm.

[0088] On the basis of making the energy density E, length dimension H, and minimum wall thickness D of the cylindrical battery cell 100 conform to the aforementioned parameter ranges, the parameter ranges of the three can be further narrowed so that E, H, and D satisfy: 500 Wh / L ≤ E ≤ 800Wh / L, 150mm≤ H ≤ 220mm, 0.5mm≤ D≤0.7mm. Exemplarily, E can be selected as any one of 500 Wh / L, 600 Wh / L, 700 Wh / L, and 800 Wh / L, or between any two of them, H can be selected as any one of 150 mm, 170 mm, 190 mm, 210 mm, and 220 mm, or between any two of them, and D can be selected as any one of 0.5 mm, 0.6 mm, and 0.7 mm, or between any two of them.

[0089] By further limiting the numerical ranges of the energy density E, the length dimension H, and the minimum wall thickness D, the possibility of smooth pressure relief at the pressure relief mechanism in the event of thermal runaway can be further increased.

[0090] In some optional embodiments, E, H, and D satisfy: 150000 Wh / L ≤ E×H / D ≤ 375000 Wh / L.

[0091] On the basis that the three parameters E, H, and D satisfy the aforementioned numerical ranges respectively, the aforementioned three parameters can be further made to satisfy 150000 Wh / L≤ E×H / D ≤ 375000 Wh / L, so as to further improve the possibility of smooth pressure relief of the cylindrical battery cell 100 in the thermal runaway state. Specifically, by making the ratio value parameter E×H / D greater than or equal to 150000, the possibility of the overall capacity and volume energy density of the cylindrical battery cell 100 being too low can be reduced, and the practicality of the cylindrical battery cell 100 can be improved. Relatively speaking, by making the ratio value parameter E×H / D less than or equal to 375000, the possibility of poor exhaust during thermal runaway caused by the excessive length and high volume energy density of the cylindrical battery cell 100 can be reduced, thereby reducing the possibility of rupture of the side wall 21 and abnormal pressure relief due to excessively thin wall thickness and poor exhaust.

[0092] Therefore, the combination of the above two can effectively improve the reliability of the cylindrical battery cell 100, and increase the possibility of smooth pressure release during thermal runaway on the basis of having a higher volume energy density.

[0093] In some optional embodiments, 150000 Wh / L ≤ E×H / D ≤ 300000 Wh / L.

[0094] Based on the above-mentioned numerical range, the numerical range of the ratio parameter E×H / D can be further reduced to 150,000 Wh / L-300,000 Wh / L. For example, it can be selected as any one of 150,000 Wh / L, 170,000 Wh / L, 190,000 Wh / L, 210,000 Wh / L, 230,000 Wh / L, 250,000 Wh / L, 270,000 Wh / L, 300,000 Wh / L or between any two of them.

[0095] By reducing the upper limit of the numerical range of the ratio parameter, the reliability of abnormal pressure release in the case of thermal runaway of the cylindrical battery cell 100 can be further reduced. Optionally, when designing the cylindrical battery cell 100, the numerical parameter E×H / D can be made less than or equal to 300,000 Wh / L to further reduce the possibility of abnormal pressure release due to too thin wall thickness of the cylindrical battery cell 100 with a long length and a large volume energy density.

[0096] At the same time, setting the value of the ratio parameter E×H / D within the aforementioned range can also improve the structural integrity of the cylindrical battery cell 100 after pressure relief in a thermal runaway state, and can reduce the degree of deformation after pressure relief, thereby further improving the reliability of the cylindrical battery cell 100.

[0097] In some optional embodiments, 150000 Wh / L ≤ E×H / D ≤ 250000 Wh / L.

[0098] By further reducing the numerical range of the ratio and lowering the upper limit, the possibility of deformation of the housing 20 after pressure relief can be further reduced on the basis of smoothly releasing pressure from the cylindrical battery cell 100 by the pressure relief mechanism, thereby further improving reliability.

[0099] In some optional embodiments, in the radial direction of the cylindrical battery cell 100 , the size of the cylindrical battery cell 100 is A, and 10 mm ≤ A ≤ 100 mm.

[0100] In the axial direction X of the cylindrical battery cell 100, its own extension dimension is recorded as A, that is, the diameter of the cylindrical battery cell 100 is Amm. At least part of the cylindrical battery cell 100 may be cylindrical, and the diameter A may be obtained by measuring in the cylindrical region. Similar to the aforementioned length dimension H, it may be calculated by taking the average value of multiple measurements.

[0101] Optionally, the radial dimension A of the cylindrical battery can be between 10 mm and 100 mm, and can further be between 40 mm and 100 mm, and can specifically be any one of 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, and 100 mm or between any two thereof.

[0102] The cylindrical battery cell 100 has a larger diameter, which enables the cylindrical battery cell 100 to have both a larger capacity and higher reliability.

[0103] In some optional embodiments, the housing 20 includes a shell 22 and an end cover 23, the shell 22 includes a side wall 21, the side wall 21 encloses an opening 221, and the end cover 23 covers the opening 221 and is connected to the side wall 21; the cylindrical battery cell 100 also includes a pressure relief mechanism 30, which is disposed on the end cover 23.

[0104] In the cylindrical battery cell 100, the housing 20 may include a shell 22 and an end cap 23, wherein the shell 22 may include a side wall 21 surrounding the electrode assembly 10, or the shell 22 may include a side wall 21 and an end wall. The shell 22 has at least one opening 221, and the opening 221 may be opened along the axial direction X. The end cap 23 covers the opening 221 and is connected to the shell 22, and the two may be connected by a clamping, crimping, welding, fastener connection, etc.

[0105] The cylindrical battery cell 100 is also provided with a pressure relief mechanism 30 for discharging the internal gas of the cylindrical battery cell 100. The pressure relief mechanism 30 can be provided at the end cover 23 in the outer shell 20, so that the housing 22 has a more reliable structural strength.

[0106] Exemplarily, the pressure relief mechanism 30 is used to actuate to release the internal pressure or temperature when the internal pressure or temperature of the cylindrical battery cell 100 reaches a predetermined threshold. When the internal pressure or temperature of the cylindrical battery cell 100 reaches the predetermined threshold, the pressure relief mechanism 30 performs an action or a weak structure provided in the pressure relief mechanism 30 is destroyed, thereby forming an opening or channel for the internal pressure or temperature to be released.

[0107] In some embodiments, when the housing 20 is a non-sealed structure, the pressure relief mechanism 30 may also be configured as a through hole for discharging the gas inside the cylindrical battery cell 100 .

[0108] See also Figure 6 , Figure 6 A partial cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of the present application. In some optional embodiments, the side wall 21 includes a main body area 211 and a thickened area 212, the thickness of the thickened area 212 is greater than the thickness of the main body area 211, and the thickened area 212 is arranged on at least one side of the main body area 211 in the axial direction X and encloses an opening 221; the thickness of at least part of the main body area 211 is D mm, 0.3mm≤D≤1mm.

[0109] Optionally, the side wall 21 in the housing 20 may be partially thickened in radial dimension, that is, the side wall 21 may include a thinner main body area 211 and a thicker thickened area 212 , and the thickened area 212 and the main body area 211 are arranged along the axial direction X of the cylindrical battery cell 100 .

[0110] Optionally, the side wall 21 may include one or more thickened areas 212. In an embodiment in which multiple thickened areas 212 are provided, these thickened areas 212 may be located on two opposite sides of the main area 211, or these thickened areas 212 may be located on the same side of the main area 211 and have different thicknesses.

[0111] The shell 22 portion in the outer shell 20 is provided with an opening 221. In the embodiment where the side wall 21 of the shell 22 includes a main area 211 and a thickened area 212, the opening 221 can be optionally formed by enclosing the thickened area 212, that is, the thickened area 212 can be arranged in a position close to the end of the side wall 21 and can be used to connect with the end cover 23.

[0112] By setting a local thickened area on the side wall 21, the structural strength of the thickened position can be correspondingly improved. At the same time, by setting the thickened area 212 on one side of the main body area 211 on the axial direction X and enclosing to form an opening 221, a larger connection area can be provided between the shell 22 and the end cover 23, thereby improving the stability of the connection.

[0113] In some optional embodiments, the end cover 23 is connected to the thickened area 212 by welding.

[0114] Optionally, welding connection can be used when connecting the end cover 23 to the shell 22 to make the connection stable and reliable. When welding, at least a partial area of ​​the end cover 23 can be overlapped on the surface of the end of the shell 22 that intersects the axial direction X. The surface can be located in the thickened area 212, thereby enabling the end cover 23 to be welded to the thickened area 212, thereby effectively increasing the area of ​​the welding area and improving the stability and reliability of the welding connection.

[0115] Optionally, when welding, welding can be performed from the side of the end cover 23 away from the thickened area 212, or welding can be performed from the side of the thickened area 212 and the end cover 23 away from the central axis of the cylindrical battery cell 100. The welding method can be laser welding, etc., and the present application does not make any specific limitation on this.

[0116] In some optional embodiments, in the axial direction X, the ratio of the size of the main body region 211 to the size of the side wall 21 is 0.5-0.98.

[0117] Optionally, in the side wall 21 of the shell 20 , the main body area 211 may have an axial extension dimension greater than or equal to that of the thickened area 212 , so that the shell 20 has a lighter weight on the basis of improving the structural strength and connection stability through the thickened area 212 .

[0118] The two opposite edges of the main body region 211 in the axial direction X may be selected as two annular surfaces parallel to each other, and the two annular surfaces may be selected to be perpendicular to the axial direction X of the cylindrical battery cell 100 as a whole. In this embodiment, the axial X extension dimension of the main body region 211 is the axial spacing between the two annular surfaces at the two side edges. Alternatively, in an embodiment where the two side edges of the main body region 211 are irregular or non-parallel, the extension dimension of the main body region 211 in the axial direction X may be selected as the average value of the axial dimensions at each location, which may be obtained by calculation or measurement.

[0119] Specifically, along the axial direction X of the cylindrical battery cell 100, the size of the main area 211 may account for 0.5-0.98 of the overall size of the side wall 21, and correspondingly, the axial size of the thickened area 212 may account for 0.02-0.5. By making the main area 211 occupy a larger size proportion, the overall weight and volume of the housing 20 can be reduced while improving the structural strength and connection stability.

[0120] In some optional embodiments, the thickened area 212 is disposed to protrude from the main area 211 in a direction close to the central axis of the cylindrical battery cell 100 .

[0121] In the embodiment where the thickened area 212 having a thickness greater than that of the main body area 211 is provided, the outer peripheral surface of the thickened area 212 in the radial direction may be flush with the outer peripheral surface of the main body area 211, that is, the outer peripheral surface of the thickened area 212 and the outer peripheral surface of the main body area 211 are located in the same cylindrical surface, and at this time, the inner sidewall 21 of the thickened area 212 may be protruded relative to the main body area 211 in the direction close to the central axis of the cylindrical battery cell 100. The thickness of the thickened area 212 may be the same at all locations in the radial direction.

[0122] By making the thickened area 212 protrude inward relative to the main body area 211 , the outer circumferential surface of the cylindrical battery cell 100 can be more regular, so that multiple cylindrical battery cells 100 can be arranged close to each other and the gaps can be reduced during use.

[0123] In some optional embodiments, the outer shell 20 includes two end covers 23, and the side wall 21 is respectively provided with openings 221 at two opposite ends in the axial direction X. The two end covers 23 are arranged one-to-one corresponding to the openings 221 and respectively cover the openings 221, and the end covers 23 are connected to the side wall 21; the outer shell 20 also includes a pressure relief mechanism 30, and at least one end cover 23 is provided with a pressure relief mechanism 30.

[0124] In order to facilitate the installation of the electrode assembly 10 and other components in the housing 20, the housing 20 may include a shell 22 and two end caps 23 connected to the shell 22. Specifically, the shell 22 may be cylindrical, and openings 221 are respectively provided at two opposite ends in the axial direction X. The two end caps 23 are respectively covered at the openings 221 and connected to the shell 22. The end caps 23 and the shell 22 may be welded to make the connection stable and reliable.

[0125] Optionally, two end caps 23 disposed on opposite sides may be electrically connected to the positive electrode and the negative electrode of the electrode assembly 10 , respectively, so as to electrically connect the cylindrical battery cell 100 to external components.

[0126] By configuring the housing 20 to have end covers 23 at both ends, it is possible to facilitate installation of components such as the electrode assembly 10 and the adapter.

[0127] In some optional embodiments, the side wall 21 includes a main body area 211 and two thickened areas 212 , the thickness of the thickened area 212 is greater than the thickness of the main body area 211 , and in the axial direction X, the two thickened areas 212 are respectively arranged on two opposite sides of the main body area 211 .

[0128] Optionally, in order to facilitate the connection between the shell 22 and the end cover 23, in an embodiment where the side wall 21 includes a main body area 211 and a thickened area 212, thickened areas 212 can be provided on both side ends of the main body area 211 opposite to each other in the axial direction X, so that the two thickened areas 212 respectively enclose openings 221 at both ends and are respectively arranged corresponding to the two end covers 23.

[0129] Optionally, the thickness and axial extension size of the two thickened areas 212 can be selected to be the same, so that the size and weight of the two sides are more uniform. Alternatively, the two thickened areas 212 can adopt different thicknesses and axial sizes according to different parameters such as the width of the end cover 23 to be connected and the strength requirements of the connection, and this application does not make specific limitations on this.

[0130] By setting both ends to be connected to the end cap 23 to have a greater thickness, the connection strength of the two ends and the reliability of the cylindrical battery cell 100 as a whole can be improved.

[0131] In some optional embodiments, in the axial direction X, the distance between the side surfaces of the two end covers 23 facing away from each other is H mm.

[0132] In the embodiment where end caps 23 are provided at both ends of the housing 22, the extension dimension of the housing 20 in the axial direction X may be calculated according to the position of the end caps 23, and specifically, the distance between the surfaces of the two end caps 23 facing away from each other in the axial direction X may be recorded as the length dimension H. By recording the aforementioned dimension as the length dimension H, the size or structure of the electrode terminal can be prevented from affecting the detection result, so that the parameter calculation is more accurate.

[0133] The surfaces of the two end caps 23 facing away from each other can be arranged parallel to each other so that the spacing between the two surfaces is the same or close. When performing the size detection, multiple points can be selected on the two end caps 23 for detection, and the average value is taken as the final result.

[0134] In some optional embodiments, the housing 20 includes a shell 22 and an end cover 23 , the shell 22 includes a side wall 21 and an end wall, the end wall and the end cover are axially opposite, and the thickness of the end wall is greater than the thickness of the side wall 21 .

[0135] Similar to the above-mentioned embodiment, the outer shell 20 of the cylindrical battery cell 100 may also be provided with only one end cover 23, in which case the shell 22 is provided with an opening 221 and an end wall at opposite ends in the axial direction X, respectively, and the side wall 21 is connected therebetween. In this embodiment, the end wall and the side wall 21 may be integrally formed, or the two may be welded.

[0136] Optionally, the end wall in the housing 22 may be selected to have the same thickness everywhere, and the thickness of the end wall may be greater than the thickness of the side wall 21, so that the end wall has a higher structural strength and load-bearing capacity, so as to reduce the possibility that the end wall breaks before the side wall 21 during thermal runaway. By setting the end wall to have a larger thickness and making E×H / D within the aforementioned numerical range, the possibility that the housing 22 as a whole will not break during thermal runaway can be increased, that is, the possibility that the end wall, the side wall 21 and the connection between the two will not break can be increased, thereby further improving the reliability of the cylindrical battery cell 100.

[0137] In some optional embodiments, the side wall 21 is made of steel.

[0138] Optionally, the outer shell 20 of the cylindrical battery cell 100 may be a steel shell. By making the outer shell 20 of steel, the outer shell 20 can have higher structural strength and impact resistance, and can be easily processed and formed.

[0139] Optionally, at least a portion of the side wall 21 in the outer shell 20 can be set to be made of steel. In an embodiment where the outer shell 20 includes a shell 22 and an end cover 23, the shell 22 as a whole can be selected to be made of steel and can be selected to be an integrally molded setting to further improve the structural strength of the shell 22.

[0140] In a second aspect, a battery device 200 is provided according to an embodiment of the present application, including a box body 40 and a plurality of cylindrical battery cells 100 in any embodiment of the first aspect, wherein the cylindrical battery cells 100 are disposed in the box body 40 .

[0141] In a third aspect, according to an embodiment of the present application, an electrical device is proposed, comprising the battery device 200 in any embodiment of the second aspect, and the battery device 200 is used to provide electrical energy.

[0142] The battery device 200 and the electrical equipment in the embodiment of the present application have all the beneficial effects of the cylindrical battery cell 100 in the first aspect. For details, reference may be made to the specific description of the cylindrical battery cell 100 in the above embodiments, which will not be repeated in this embodiment.

[0143] Example The following examples describe the contents disclosed in the examples of the present application in more detail, and these examples are only used for illustrative purposes, because it is obvious to those skilled in the art that various modifications and variations are made within the scope of the disclosure of the examples of the present application. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0144] Example 1 1. Preparation of positive electrode The positive electrode sheet includes a positive electrode collector and a positive electrode film layer. The positive electrode film layer is located on both sides of the positive electrode collector. The positive electrode collector is an aluminum foil. The positive electrode film layer is formed by evenly coating the positive electrode slurry (the solvent is N-methylpyrrolidone NMP) on the surface of the positive electrode collector aluminum foil, drying, and cold pressing. The positive electrode film layer includes a positive electrode active material, a conductive agent carbon black (Super P), and a binder polyvinylidene fluoride (PVDF) in a weight ratio of 97:1:2.

[0145] The positive electrode active material includes a LiNi 0.8 Co 0.1 Mn 0.1 Layered transition metal oxides of O2 (NCM811).

[0146] 2. Preparation of negative electrode sheet The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer. The negative electrode film layer is located on both sides of the negative electrode current collector. The negative electrode current collector is copper foil. The negative electrode film layer is formed by evenly coating the negative electrode slurry (the solvent is deionized water) on the surface of the negative electrode current collector copper foil, drying, and cold pressing. The negative electrode film layer includes silicon-based materials (specifically silicon oxides), graphite, conductive agent carbon black, conductive agent carbon nanotubes, and binder polyacrylic acid in a weight ratio of 12.6:82.4:1.9:0.1:3.

[0147] 3. Preparation of Isolators Provide PE (Polyethylene) based film.

[0148] 4. Preparation of electrolyte The electrolyte includes an organic solvent and a lithium salt. Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, the fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0149] 5. Preparation of cylindrical battery cells The positive electrode sheet, separator and negative electrode sheet are stacked in order, so that the separator is placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, and the positive electrode sheet, separator and negative electrode sheet are wound to obtain an electrode assembly; the electrode assembly is placed in a cylindrical shell, and after drying, the electrolyte is injected, and after vacuum packaging, standing, forming, shaping and other processes, a cylindrical battery cell is obtained, wherein the electrode assembly is a cylindrical structure, and the shell is a cylindrical structure, the shell includes a shell and an end cover, and the shell includes an integrally formed side wall and end wall, the side wall is arranged around the electrode assembly, and the end cover and the end wall are opposite along the axial direction X of the shell.

[0150] 6. Performance Testing 6.1. Volume energy density test of cylindrical battery cells The volume energy density of the cylindrical battery cell can be obtained by calculation, and the calculation method is capacity × platform voltage / volume. Specifically, the discharge energy and platform voltage of the cylindrical battery cell can be obtained by cyclic charge and discharge, multiple measurements and average values, and then the volume of the cylindrical battery cell can be measured by CT scanning or "drainage method", and the volume energy density E can be obtained by calculation.

[0151] 6.2. Cylindrical battery cell length dimension and minimum wall thickness test in its own axial direction The length of the cylindrical battery cell can be measured by measuring with a ruler, calculating with a CT scan, etc., and the minimum wall thickness can be measured by using tools such as a ruler and a vernier caliper. Both parameters can be measured multiple times to obtain the average value to improve accuracy.

[0152] 6.3 Cylindrical battery cell safety test Heating and other operations are performed on cylindrical battery cells to trigger thermal runaway. Optional triggering methods include internal heating, external heating, and acupuncture, etc. Here, the internal heating method is taken as an example.

[0153] When making the test cylindrical battery cell, a 30mm×30mm×1mm (length x width x thickness) heating sheet is pasted on the surface of the electrode assembly. The positive and negative wires of the heating sheet are led out from the preset outlet holes of the end cover of the cylindrical battery cell. The small hole position is structurally sealed, and the strength of the sealing position is not less than the strength required for the opening of the pressure relief mechanism in the cylindrical battery cell. After the test cylindrical battery cell is made, the cylindrical battery cell is charged to a full charge state (100% SOC). The ambient temperature of the test: room temperature (25±5℃) or a specific operating temperature (for example: 50±5℃); the wires of the heating sheet are connected to a DC power supply, so that the output power of the heating sheet is under the condition of 300±50w, and the heating is triggered to thermal runaway of the cylindrical battery cell, and the thermal runaway behavior characteristics of the cylindrical battery cell are explored.

[0154] When recording the test results, the situation where pressure is released only from the pressure relief mechanism will be recorded as normal pressure relief, and the situation where pressure is released from other places other than the pressure relief mechanism area (such as the side walls, welding places on the outer shell, etc.) will be recorded as abnormal pressure relief.

[0155] Furthermore, when recording the appearance of the outer shell of a cylindrical battery cell after thermal runaway: The ability to achieve stable directional pressure relief and no shell deformation after loss of control is recorded as "+++"; If the normal pressure relief can be achieved stably, and the shell can maintain basic integrity after thermal runaway, and there is no serious deformation, it is marked as "++"; If normal pressure relief can be achieved but the shell is deformed, such as bulging of the cylindrical surface, it is marked as "+"; Abnormal pressure relief means that not only the pressure relief mechanism releases pressure, but also other areas such as welds and cylindrical surfaces. The pressure relief area in other areas is small and is recorded as "-"; Abnormal pressure relief, shell explosion after the pressure relief mechanism is opened, and other extreme events are recorded as "--"; The extreme events such as the pressure relief mechanism not opening and the shell exploding directly occurring are recorded as “---”.

[0156] Specifically, the test results of each embodiment are shown in Table 1 below: Table 1

[0157] According to the above results, embodiments 1 to 6 have achieved good results. The relationship between the volume energy density E, the length dimension H and the minimum thickness D of the side wall 21 of the outer shell 20 of the cylindrical battery cell is appropriately adjusted. When thermal runaway occurs inside the cylindrical battery cell and gas is produced to form air pressure, the cylindrical battery cell can be normally depressurized at its own pressure relief mechanism, thereby reducing the structural deformation of the cylindrical battery cell 100, reducing the possibility of rupture and explosion of the side wall 21 of the outer shell 20 due to poor exhaust, further reducing the risk of battery explosion, and improving the reliability of the cylindrical battery cell 100.

[0158] The embodiment of the present application provides a cylindrical battery cell 100, including an electrode assembly and a shell; the shell includes a side wall, the electrode assembly is accommodated in the shell 20, and the side wall 21 surrounds the electrode assembly; the volume energy density of the cylindrical battery cell 100 is EWh / L, in the axial direction of the cylindrical battery cell 100, the size of the shell is H mm, the minimum thickness of the side wall is D mm, and in the radial direction of the cylindrical battery cell, the size of the cylindrical battery cell is Amm, wherein A, E, H, and D satisfy: 120mm ≤ H ≤ 300mm, 10mm ≤ A ≤ 100mm, 300Wh / L ≤ E ≤ 1500Wh / L, 150000 ≤ E×H / D ≤ 250000.

[0159] 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 replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate 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 cylindrical battery cell, characterized in that: include: Electrode assembly; a housing, comprising a side wall, wherein the electrode assembly is accommodated in the housing, and the side wall surrounds the electrode assembly; The volume energy density of the cylindrical battery cell is E Wh / L. In the axial direction of the cylindrical battery cell, the size of the shell is H mm, the minimum thickness of the side wall is D mm, and E, H, and D satisfy: 300 Wh / L ≤ E ≤1500Wh / L, 120mm≤ H ≤ 300mm, and 0.3mm≤ D≤1mm.

2. The cylindrical battery cell according to claim 1, characterized in that: E, H, and D meet the following requirements: 500 Wh / L ≤ E ≤800Wh / L, 150mm≤ H ≤ 220mm, 0.5mm≤ D≤0.7mm.

3. The cylindrical battery cell according to claim 1, characterized in that: E, H, D meet the following requirements: 150000 Wh / L ≤ E×H / D ≤ 375000Wh / L.

4. The cylindrical battery cell according to claim 3, characterized in that: 150000 Wh / L ≤ E×H / D ≤300000 Wh / L.

5. The cylindrical battery cell according to claim 4, characterized in that: 150000 Wh / L ≤ E×H / D ≤250000 Wh / L.

6. The cylindrical battery cell according to claim 1, characterized in that: In the radial direction of the cylindrical battery cell, the diameter of the cylindrical battery cell is A, 10 mm ≤ A ≤ 100 mm.

7. The cylindrical battery cell according to claim 1, characterized in that: The housing comprises a shell and an end cover, the shell comprises the side wall, the side wall encloses an opening, and the end cover covers the opening and is connected to the side wall; The cylindrical battery cell further includes a pressure relief mechanism, and the pressure relief mechanism is disposed on the end cover.

8. The cylindrical battery cell according to claim 7, characterized in that: The side wall includes a main body area and a thickened area, the thickness of the thickened area is greater than the thickness of the main body area, and the thickened area is arranged on at least one side of the main body area in the axial direction and encloses the opening; The thickness of at least a part of the main body region is D mm, and 0.3 mm ≤ D ≤ 1 mm.

9. The cylindrical battery cell according to claim 8, characterized in that: The end cover is connected to the thickened area by welding.

10. The cylindrical battery cell according to claim 8, characterized in that: In the axial direction, the ratio of the size of the main body region to the size of the side wall is 0.5-0.

98.

11. The cylindrical battery cell according to claim 8, characterized in that: The thickened area is arranged to protrude from the main body area in a direction close to the central axis of the cylindrical battery cell.

12. The cylindrical battery cell according to claim 7, characterized in that: The housing comprises two end covers, the side wall is provided with openings at two opposite ends in the axial direction, the two end covers are provided in one-to-one correspondence with the openings and cover the openings respectively, and the end covers are connected to the side wall; The housing further comprises a pressure relief mechanism, and at least one of the end covers is provided with the pressure relief mechanism.

13. The cylindrical battery cell according to claim 12, characterized in that: The side wall includes a main body area and two thickened areas. The thickness of the thickened area is greater than the thickness of the main body area. In the axial direction, the two thickened areas are respectively arranged on two opposite sides of the main body area.

14. The cylindrical battery cell according to claim 7, characterized in that: The housing includes the shell and an end cover, the shell includes the side wall and the end wall, the end wall and the end cover are opposite to each other along the axial direction, and the thickness of the end wall is greater than the thickness of the side wall.

15. The cylindrical battery cell according to claim 1, characterized in that: The material of the side wall is steel.

16. A battery device, characterized in that: include: Box; A plurality of cylindrical battery cells according to any one of claims 1 to 15, wherein the cylindrical battery cells are arranged in the box.

17. An electrical equipment, characterized in that: Comprising the battery device as claimed in claim 16, the battery device is used to provide electrical energy.

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