Battery monomer, battery device and power utilization device

Abstract

The embodiment of the utility model provides a battery monomer, a battery device and a power utilization device, the battery monomer comprises an electrode assembly, a pressure relief mechanism and a protective film, and the pressure relief mechanism is located at one side of the electrode assembly along a first direction; the protective film is located on at least one side of the pressure relief mechanism in the first direction, the protective film and the pressure relief mechanism are located on the same side of the electrode assembly in the first direction, and in a projection plane perpendicular to the first direction, at least part of projection of the pressure relief mechanism in the first direction coincides with projection of the protective film in the first direction. The thickness dimension of the protective film is multiplied by the melting point of the structure of the protective film to obtain a first product, the first product is divided by the volume energy density of the battery cell to obtain a first quotient, and the value of the first quotient ranges from 0.0068 to 100. According to the battery monomer in the embodiment of the invention, the probability that external emissions enter the battery monomer and then are in contact with the electrode assembly can be reduced, and the probability that the electrode assembly is subjected to thermal runaway due to high temperature and impact is reduced.

Description

Technical Field

[0001] Embodiments of the present application relate to the technical field of batteries, and particularly to a battery cell, a battery device, and an electrical device. Background Art

[0002] A pressure relief mechanism is provided on the battery cell. In the state where the battery cell gets out of control, the emissions generated inside the battery cell can be discharged outside the battery cell through the pressure relief mechanism, so as to reduce the risk of the battery cell splitting under the pressure of the emissions.

[0003] In a battery device, a plurality of battery cells are arranged, and at least some of the battery cells are arranged in the same space, so that the emissions ejected from the battery cell that gets out of control will contact other battery cells.

[0004] Since the pressure relief mechanism needs to be connected to the outside of the battery cell in the state where the battery cell gets out of control, its structural strength and high-temperature resistance are worse than those of the outer shell of the battery cell. Therefore, after the emissions contact the originally intact battery cell from the outside, the pressure relief mechanism is easily damaged under the action of the high-temperature and high-pressure emissions, and then the emissions enter the inside of the originally intact battery cell, causing the originally intact battery cell to be heated and get out of control, increasing the number of battery cells that get out of control in the battery device. Summary of the Utility Model

[0005] In view of this, embodiments of the present application are expected to provide a battery cell, a battery device, and an electrical device that are beneficial to reducing thermal runaway caused by the influence of external emissions.

[0006] To achieve the purpose, the technical solution of the embodiments of the present application is realized as follows:

[0007] Embodiments of the present application provide a battery cell, including:

[0008] An electrode assembly;

[0009] A pressure relief mechanism located on one side of the electrode assembly along a first direction;

[0010] A protective film located on at least one side of the pressure relief mechanism along the first direction and on the same side of the electrode assembly as the pressure relief mechanism along the first direction. In a projection plane perpendicular to the first direction, at least part of the projection of the pressure relief mechanism along the first direction coincides with the projection of the protective film along the first direction. The protective film is configured to be able to block the emissions outside the battery cell. The thickness dimension of the protective film is multiplied by the melting point of the structure of the protective film to obtain a first product, and the first product is divided by the volume energy density of the battery cell to obtain a first quotient. The value range of the first quotient is from 0.0068 to 100.

[0011] In the battery cell of the embodiment of the present application, through the shielding and protection effects of the protective film, the probability that external emissions enter the battery cell and come into contact with the electrode assembly can be reduced, and the probability that the electrode assembly undergoes thermal runaway due to high temperature and impact can be reduced. It is convenient for the melting point and the dimension in the first direction of the protective film to meet the high temperature and impact requirements of the emissions discharged from battery cells with different volumetric energy densities, and the risk of the protective film cracking under the impact of external emissions is reduced.

[0012] In some embodiments, the value range of the first quotient is from 0.06 to 100. In this way, the risk of the protective film cracking under the impact of external emissions can be further reduced.

[0013] In some embodiments, in the projection plane perpendicular to the first direction, the projection of the pressure relief mechanism along the first direction is located within the projection range of the protective film along the first direction. In this way, the shielding effect of the protective film is improved, and the probability that external emissions enter the battery cell and come into contact with the electrode assembly is further reduced.

[0014] In some embodiments, the protective film includes a first film, and the first film covers the surface of the pressure relief mechanism facing away from the electrode assembly. In this way, the pressure relief mechanism directly provides an installation position for the first film, and reduces the probability that external emissions directly come into contact with the pressure relief mechanism, playing a certain protective role for the pressure relief mechanism. At the same time, it is beneficial to install the first film from the outside of the battery cell, improving the installation convenience and facilitating the replacement of the first film;

[0015] And / or, the protective film includes a second film, and the second film covers the surface of the pressure relief mechanism facing the electrode assembly. In this way, in the normal working state of the battery cell, the pressure relief mechanism can shield and protect the second film, reducing the probability of the second film being damaged due to factors such as collision.

[0016] In some embodiments, the battery cell further includes a separator, and the separator is located between the electrode assembly and the pressure relief mechanism;

[0017] The protective film includes a third film, and the third film is located between the separator and the electrode assembly. In this way, it is beneficial to reduce the risk that external emissions can be blocked by the third film after passing through the pressure relief mechanism and the separator in sequence, reducing the risk of external emissions coming into contact with the electrode assembly;

[0018] And / or, the protective film includes a fourth film, and the fourth film is located between the separator and the pressure relief mechanism. In this way, it is beneficial to reduce the risk that external emissions can be blocked by the fourth film after passing through the pressure relief mechanism, reducing the risk of external emissions coming into contact with the electrode assembly.

[0019] In some embodiments, the protective film further includes a fifth film, and the fifth film is attached to the surface of the electrode assembly facing the pressure relief mechanism. Thus, it is beneficial for the protective film to directly shield and protect the electrode assembly, reducing the probability of the electrode assembly coming into contact with the external emissions passing through the pressure relief mechanism.

[0020] In some embodiments, the material of the protective film includes one of polyimide, polytetrafluoroethylene, fluorinated ethylene propylene, polyethylene naphthalate, polyethylene terephthalate, polyether ether ketone, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherimide, and ceramics. Thus, it is beneficial for the protective film to withstand the impact and high temperature of external emissions, and it is also beneficial for extending the service life of the protective film.

[0021] In some embodiments, the thickness dimension range of the protective film is from 0.1 mm to 5 mm. Thus, it is beneficial for the protective film to have a certain structural strength, reducing the probability of the protective film being penetrated by external emissions; at the same time, making the structure of the protective film compact;

[0022] And / or, the melting point range of the structure of the protective film is from 85°C to 1000°C. Thus, on the one hand, it is difficult for the protective film to melt due to the heat released during the normal charging and discharging process of the battery cell, which is beneficial for extending the service life of the protective film; on the other hand, it is beneficial for reducing the probability of the protective film melting at the high temperature of external emissions and causing external emissions to pass through the protective film;

[0023] And / or, the volume energy density range of the battery cell is from 50 Wh / L to 1250 Wh / L, which is beneficial for the protective film to block the high temperature and impact of emissions generated by other battery cells.

[0024] In some embodiments, the thickness dimension range of the protective film is from 0.5 mm to 5 mm. Thus, it is beneficial for further reducing the probability of the protective film being penetrated by external emissions; at the same time, making the structure of the protective film compact;

[0025] And / or, the melting point range of the structure of the protective film is from 150°C to 1000°C. Thus, it is further beneficial for extending the service life of the protective film.

[0026] The embodiment of the present application further provides a battery device, which includes a box body and a plurality of battery cells as described in any one of the foregoing embodiments. An accommodation space is provided in the box body, and the battery cells are located in the accommodation space.

[0027] By adopting the battery cells in the foregoing embodiments, it is beneficial to reduce the probability that other intact battery cells also experience thermal runaway after some battery cells in the battery device undergo thermal runaway, and it is beneficial to reduce the severity of thermal runaway of the battery device.

[0028] An embodiment of the present application further provides an electrical device, and the electrical device includes the battery device as described in the foregoing embodiments, and the battery device is used as the power source of the electrical device.

[0029] By adopting the battery device in the foregoing embodiments, it is beneficial to reduce the risk of damage to other components in the electrical device in the event of thermal runaway occurring within the battery device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of an electrical device being a vehicle in an embodiment of the present application;

[0031] Figure 2 Schematic diagram of a battery device in an embodiment of the present application;

[0032] Figure 3 Explosion schematic diagram of a battery cell in the first embodiment of the present application;

[0033] Figure 4 is Figure 3 Schematic diagram from another perspective;

[0034] Figure 5 is Figure 4 Cross-sectional schematic diagram at the A-A position in;

[0035] Figure 6 is Figure 5 Enlarged schematic diagram at the B position in;

[0036] Figure 7 Explosion schematic diagram of a battery cell in the second embodiment of the present application;

[0037] Figure 8 is Figure 7 Schematic diagram from another perspective;

[0038] Figure 9 is Figure 8 Cross-sectional schematic diagram at the C-C position in;

[0039] Figure 10 Schematic diagram of an electrode assembly, an end cap, a separator, and a protective film in the third embodiment of the present application;

[0040] Figure 11 is Figure 10 Schematic diagram from another perspective of an embodiment including a housing and a pressure relief mechanism in;

[0041] Figure 12 is Figure 11 a schematic cross-sectional view at the D-D position in

[0042] Figure 13 is Figure 12 a partially enlarged schematic view at the E position in

[0043] Figure 14 a schematic cross-sectional view of a battery cell in the fourth embodiment of the present application, and its cross-sectional position is the same as that at the D-D position in Figure 11 ;

[0044] Figure 15 is Figure 12 a partially enlarged schematic view at the F position in

[0045] Figure 16 a schematic view of an electrode assembly and a protective film in the fifth embodiment of the present application.

[0046] Description of the reference numerals

[0047] 1000, vehicle; 100, battery device; 200, controller; 300, motor; 10, box body; 11, first box body; 12, second box body; 20, battery cell; 20a, accommodation cavity; 21, electrode assembly; 22, pressure relief mechanism; 23, protective film; 231, first film; 232, second film; 233, third film; 234, fourth film; 235, fifth film; 24, outer shell; 241, housing; 2411, first wall; 242, end cover; 25, partition. Detailed implementation manners

[0048] It should be noted that, without conflict, the embodiments in the present application and the technical features in the embodiments can be combined with each other. The detailed description in the detailed implementation manners should be understood as an explanatory illustration of the purpose of the present application and should not be regarded as an improper limitation to the present application.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill 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" and any variations thereof in the description and drawings of this application are intended to cover non-exclusive inclusion.

[0050] In the description of the embodiments of the present application, the technical terms "first", "second", "third", etc. are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, "a plurality of" means more than two unless otherwise specifically defined.

[0051] 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.

[0052] In the description of the embodiments of the present application, the term "and / or" is only 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 article generally indicates that the associated objects before and after are in an "or" relationship.

[0053] In the description of the embodiments of the present application, for the convenience of explanation, as shown in the accompanying drawings of the specification, the direction of the arrow X is referred to as the “first direction”.

[0054] 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 terms in the embodiments of the present application can be understood according to the specific circumstances.

[0055] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, the technical term "contact" should be understood in a broad sense, and may be direct contact or contact through an intermediate medium layer. It may be contact with essentially no interaction force between the two contacting parties, or it may be contact with interaction force between the two contacting parties.

[0056] 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.

[0057] 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.

[0058] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator disposed between the negative electrode and the positive electrode. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode and the negative electrode. The separator is disposed between the positive electrode and the negative electrode, which can prevent short circuit between the positive and negative electrodes and allow active ions to pass through.

[0059] In some embodiments, the battery cell may include a housing. The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film, etc. In some embodiments, the housing can be a sealed structure or a non-sealed structure. As an example, when the housing is a non-sealed structure, the housing serves to protect the electrode assembly, and a sealed bag is further included between the housing and the electrode assembly for encapsulating the electrode assembly and the electrolyte. Specifically, the sealed bag can be a bag-shaped insulating member or an aluminum-plastic film. When the housing is a sealed structure, it is used to encapsulate components such as the electrode assembly and the electrolyte.

[0060] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a multi-prismatic battery, and the multi-prismatic battery is, for example, a hexagonal prism battery, etc. There is no particular limitation in this application.

[0061] In some embodiments, the housing includes an end cap and a housing body. The housing body is provided with an opening, and the end cap covers the opening. The housing body can be provided with one or more openings. One or more end caps can also be provided.

[0062] In some embodiments, a pressure relief mechanism is provided on the housing. The pressure relief mechanism is used to discharge the internal gas of the battery cell.

[0063] As an example, it is actuated to release the internal pressure or temperature when the internal pressure or temperature of the battery cell reaches a predetermined threshold. When the internal pressure or temperature of the battery cell reaches a predetermined threshold, the pressure relief mechanism performs an action or a weak structure provided in the pressure relief mechanism is damaged, thereby forming an opening or a channel for the internal pressure or temperature to be released. This threshold design varies according to different design requirements. The threshold may depend on one or several materials among the positive electrode sheet, negative electrode sheet, electrolyte, and separator in the battery cell.

[0064] As an example, the pressure relief mechanism can be integrally formed with the housing.

[0065] As an example, the pressure relief mechanism can also be separately provided and connected to the housing.

[0066] As used in this application, "actuation" refers to the movement or activation of the pressure relief mechanism to a certain state, so that the internal pressure and temperature of the battery cell can be released. The movement generated by the pressure relief mechanism may include, but is not limited to: the movement of components in the pressure relief mechanism to form an exhaust passage, the rupture, fragmentation, tearing or opening of at least a part of the pressure relief mechanism, etc. When the pressure relief mechanism is actuated, the high-temperature and high-pressure substances inside the battery cell will be discharged outward from the actuated part as emissions. In this way, the battery cell can be depressurized and temperature-relieved under controlled pressure or temperature, thereby avoiding potential more serious accidents.

[0067] In some embodiments, when the housing is a non-sealed structure, the pressure relief mechanism can be set as a through hole for discharging the gas inside the battery cell.

[0068] The emissions from the battery cell mentioned in this application include, but are not limited to: electrolytes, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by reactions, flames, etc.

[0069] The battery apparatus mentioned in the embodiments of this 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, parallel or in a hybrid connection through a busbar component.

[0070] In some embodiments, the battery cell assembly is usually formed by arranging a plurality of battery cells.

[0071] As an example, the battery cell assembly can be a battery module, and the battery module is formed by arranging and fixing a plurality of battery cells into an independent module. As an example, the battery module can be formed by bundling a plurality of battery cells with cable ties.

[0072] In some embodiments, the battery apparatus can be a battery pack, and the battery pack includes a box assembly and one or more battery cell assemblies, and the battery cell assemblies are accommodated in the box assembly.

[0073] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be accommodated in the box assembly by fixing the battery module in the box assembly.

[0074] As an example, the battery cell assembly can also be accommodated in the box assembly by directly fixing a plurality of battery cells to the box.

[0075] In some embodiments, the housing assembly can be part of the chassis structure of a vehicle. For example, part of the housing can form at least part of the floor of the vehicle, or part of the housing assembly can form at least part of the cross beams and longitudinal beams of the vehicle.

[0076] As an example, referring to Figure 2 , the housing 10 may include a first housing 11 and a second housing 12. The first housing 11 and the second housing 12 are snapped together so that a closed space is formed inside the housing 10 to accommodate the battery cell assembly. Here, "closed" means covered or closed, and it can be sealed or non-sealed. The first housing 11 can be a top cover or a bottom plate.

[0077] As an example, the housing assembly 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 housing assembly to accommodate the battery cell assembly.

[0078] The technical solutions described in the embodiments of the present application are applicable to various electrical devices using battery cells, such as mobile phones, portable devices, laptop computers, battery-powered vehicles, electric toys, electric tools, vehicles, ships, and spacecrafts, etc. For example, spacecrafts include airplanes, rockets, space shuttles, and spaceships, etc.

[0079] In the following embodiments, for the convenience of description, the electrical device in an embodiment of the present application is taken as an example of a vehicle 1000 for illustration. The following will be described with reference to the accompanying drawings.

[0080] The vehicle 1000 can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, etc. As Figure 1 shown, a battery device 100 is provided inside the vehicle 1000. The battery device 100 can be provided at the bottom, the head, or the tail of the vehicle 1000. The battery device 100 can be used for power supply of the vehicle 1000. For example, the battery device 100 can be used as the operating power source of the vehicle 1000. The vehicle 1000 can also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300. For example, it is used for the working power requirements during the start, navigation, and driving of the vehicle 1000.

[0081] In some embodiments of the present application, the battery device 100 can not only be used as the operating power source of the vehicle 1000, but also be used as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0082] Next, the embodiments of the present application will be described in detail.

[0083] In the related art, a pressure relief mechanism is provided on the outer shell of a battery cell and a part of it is exposed to the outside of the battery cell, so that after the battery cell undergoes thermal runaway, the pressure relief mechanism opens to discharge the emissions formed inside the battery cell due to thermal runaway outside the battery cell.

[0084] After the emissions of the battery cell that has undergone thermal runaway are discharged, they diffuse within the battery device and come into contact with other battery cells that have not undergone thermal runaway. Due to the limited impact resistance and high-temperature resistance of the pressure relief mechanism, the pressure relief mechanism is easily damaged under the impact and high-temperature influence of the emissions, thereby enabling the emissions to enter the interior of the battery cells that have not undergone thermal runaway. The electrode assembly and electrolyte inside the battery cells that have not undergone thermal runaway are heated up under the influence of the emissions and are thus prone to thermal runaway, causing the battery cells that originally did not undergo thermal runaway to undergo thermal runaway, and increasing the number of battery cells that undergo thermal runaway within the battery device.

[0085] Based on the technical problems, embodiments of the present application provide a battery cell, a battery device, and an electrical device. By providing an additional protective film, the external emissions need to break through the protective film to come into contact with the electrode assembly, thereby reducing the risk of the external emissions entering the interior of the battery cells that have not undergone thermal runaway and causing them to undergo thermal runaway.

[0086] Specifically, referring to Figures 3 to 16 , embodiments of the present application provide a battery cell 20, which includes an electrode assembly 21, a pressure relief mechanism 22, and a protective film 23.

[0087] The pressure relief mechanism 22 is located on one side of the electrode assembly 21 along a first direction.

[0088] The protective film 23 is located on at least one side of the pressure relief mechanism 22 along the first direction and is on the same side of the electrode assembly 21 along the first direction as the pressure relief mechanism 22. In a projection plane perpendicular to the first direction, at least a part of the projection of the pressure relief mechanism 22 along the first direction coincides with the projection of the protective film 23 along the first direction. The protective film 23 is configured to be able to block the external emissions of the battery cell 20. The thickness dimension of the protective film 23 is multiplied by the melting point of the structure of the protective film 23 to obtain a first product, and the first product is divided by the volume energy density of the battery cell 20 to obtain a first quotient. The value range of the first quotient is from 0.0068 to 100.

[0089] The pressure relief mechanism 22 can be selectively opened and closed. In a state where the electrode assembly 21 undergoes thermal runaway, the pressure relief mechanism 22 is in an open state to discharge the emissions generated by the electrode assembly 21 outside the battery cell 20; in a state where the battery cell 20 is operating normally, the pressure relief mechanism 22 is in a closed state to reduce the risk of leakage of the electrolyte stored inside the battery cell 20 and also reduce the probability of external foreign objects entering the interior of the battery cell 20 through the pressure relief mechanism 22.

[0090] The protective film 23 may be located on the side of the pressure relief mechanism 22 close to the electrode assembly 21 along the first direction; may be located on the side of the pressure relief mechanism 22 away from the electrode assembly 21; or may be provided with protective films 23 on both sides of the pressure relief mechanism 22.

[0091] The pressure relief mechanism 22 and the protective film 23 are located on the same side of the electrode assembly 21, and the projection of the pressure relief mechanism 22 along the first direction and the projection of the protective film 23 along the first direction at least partially overlap with each other. That is, at least part of the protective film 23 is located in the flow path of the emissions along the first direction from the outside of the battery cell 20 through the pressure relief mechanism 22 to the electrode assembly 21, so that in this flow path, the protective film 23 can block the flow of emissions.

[0092] External emissions are emissions generated by thermal runaway of other battery cells 20 in the battery device 100 .

[0093] The thickness of the protective film 23 is d, the melting point of the protective film 23 is r, and the volume energy density of the battery cell 20 is VED. The three satisfy the relationship: 0.0068≤(r*d) / VED≤100.

[0094] The volume energy density of the battery cell 20 refers to the amount of electricity per unit volume of the battery cell 20. Specifically, it is the quotient of the amount of electricity in the battery cell 20 and the volume of the battery cell 20.

[0095] The battery cell capacity is the rated capacity value of the battery cell 20 measured under the conditions specified by the battery manufacturer and declared by the manufacturer, and its unit is Wh (Watt Hours).

[0096] The volume of the battery cells 20 is the total volume of the space occupied by the battery cells 20 , and its unit is m 3 (cubic meter) or L (liter).

[0097] It is understandable that the higher the volume energy density of the battery cell 20, the greater the pressure and heat of the exhaust discharged by the battery cell 20, and the greater the impact of thermal shock and thermal diffusion generated by the exhaust. Therefore, the greater the volume energy density of the battery cell 20, in order to make the value of the first quotient meet the above range requirements, the value of the first product increases accordingly, which means that at least one of the two parameters, the thickness of the protective film 23 and the melting point of the structure of the protective film 23, needs to be increased.

[0098] In the battery cell 20 of the embodiment of the present application, through the shielding and protection functions of the protective film 23, the probability that external emissions enter the battery cell 20 and come into contact with the electrode assembly 21 can be reduced, and the probability that the electrode assembly 21 undergoes thermal runaway due to high temperature and impact can be reduced. It is convenient for the melting point and thickness dimensions of the protective film 23 to meet the high temperature and impact requirements of the emissions discharged from battery cells 20 with different volume energy densities, and the risk of the protective film 23 cracking under the impact of external emissions can be reduced.

[0099] It can be understood that the melting point of the structure of the protective film 23 is higher than the highest temperature of the environment where the protective film 23 is located when the battery cell 20 is in a normal working state, so as to reduce the risk of the protective film 23 failing when the battery cell 20 is in a normal working state.

[0100] It can be understood that the protective film 23 has certain insulation properties to reduce the risk of short circuit of the protective film 23 inside the battery cell 20.

[0101] In some embodiments, refer to Figure 3 、 Figure 4 and Figure 5 The battery cell 20 further includes a housing 24. An accommodation cavity 20a is provided inside the housing 24. The electrode assembly 21 is located in the accommodation cavity 20a. The pressure relief mechanism 22 is provided on the housing 24 and communicates with the accommodation cavity 20a. In the state where the battery cell 20 undergoes thermal runaway, the pressure relief mechanism 22 communicates the accommodation cavity 20a with the outside of the battery cell 20.

[0102] It can be understood that the protective film 23 can be disposed in the accommodation cavity 20a so that the housing 24 can provide a certain degree of protection for the protective film 23, reducing the risk of the protective film 23 cracking due to factors such as collision and friction when the battery cell 20 is in a normal working state; the protective film 23 can also be disposed outside the housing 24, which is beneficial to improving the convenience in the process of assembling the battery cell 20, improving the production efficiency of the battery cell 20, and also facilitating the installation of the protective film 23 on the existing battery cell 20.

[0103] It can be understood that in the state where the battery cell 20 undergoes thermal runaway, the higher the volume energy density of the battery cell 20, the greater the pressure and heat of the emissions discharged from the battery cell 20, and the more significant the adverse impact on the surrounding intact battery cells 20.

[0104] In some embodiments, the first direction is the direction of gravity.

[0105] In some embodiments, the range of the value of the first quotient is from 0.06 to 100. That is, 0.06 ≤ (r * d) / VED ≤ 100.

[0106] In this way, the risk of the protective film 23 being broken due to the impact of external emissions can be further reduced.

[0107] Specific values of the first quotient can be 0.0068, 0.01, 0.02, 0.05, 0.06, 0.1, 0.2, 0.5, 1, 2, 5, 10, 12, 15, 16, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, etc.

[0108] A specific method for measuring the thickness of the protective film 23 is to use a vernier caliper, place the vernier and the main scale in contact with the two end surfaces of the protective film 23 along the thickness direction of the protective film 23, and read the indication of the vernier caliper to obtain the thickness of the protective film 23.

[0109] A specific method for measuring the melting point of the structure of the protective film 23 is to cut a portion of the sample from the protective film 23 and put it into a melting point tester to obtain the melting point of the structure of the protective film 23 .

[0110] In some embodiments, a thickness direction of at least a portion of the protective film 23 is the same as the first direction.

[0111] In some embodiments, see Figure 3 , Figure 5 and Figure 6 In the projection plane perpendicular to the first direction, the projection of the pressure relief mechanism 22 along the first direction is located within the projection range of the protective film 23 along the first direction.

[0112] That is, the protective film 23 completely blocks the pressure relief mechanism 22 along the first direction. When the protective film 23 blocks the pressure relief mechanism 22 from the side of the pressure relief mechanism 22 away from the electrode assembly 21, the external emissions need to break through the protective film 23 to contact the pressure relief mechanism 22; when the protective film 23 blocks the pressure relief mechanism 22 from the side of the pressure relief mechanism 22 close to the electrode assembly 21, the emissions that pass through the pressure relief mechanism 22 need to break through the protective film 23 to contact the electrode assembly 21.

[0113] In this way, the shielding effect of the protective film 23 is improved, and the probability of external emissions entering the interior of the battery cell 20 and contacting the electrode assembly 21 is further reduced.

[0114] In some embodiments, the pressure relief mechanism 22 has a discharge area on one side surface facing away from the electrode assembly 21. When the pressure relief mechanism 22 is in the open state, the internal emissions of the battery cell 20 enter the pressure relief mechanism 22 and are discharged to the outside of the battery cell 20 through the discharge area.

[0115] The emissions from the battery cell 20 are emissions generated by thermal runaway of the battery cell 20 itself.

[0116] The specific type of the discharge area is not limited, such as an outlet.

[0117] In some embodiments where the protective film 23 is located on the side of the pressure relief mechanism 22 away from the electrode assembly 21, in the projection plane perpendicular to the first direction, the projection of the discharge area along the first direction is located within the projection range of the protective film 23 along the first direction.

[0118] In this way, it is beneficial to reduce the size of the protective film 23 while reducing the risk that external emissions enter the pressure relief mechanism 22, causing damage to the pressure relief mechanism 22 and further entering the battery cell 20 and contacting the electrode assembly 21.

[0119] In some embodiments, one side surface of the pressure relief mechanism 22 close to the electrode assembly 21 has an inlet area. When the pressure relief mechanism 22 is in an open state, the emissions inside the battery cell 20 enter the pressure relief mechanism 22 through the inlet area.

[0120] The specific type of the inlet area is not limited, such as an inlet.

[0121] In some embodiments where the protective film 23 is located on the side of the pressure relief mechanism 22 close to the electrode assembly 21, in the projection plane perpendicular to the first direction, the projection of the inlet area along the first direction is located within the projection range of the protective film 23 along the first direction.

[0122] In this way, it is beneficial to reduce the size of the protective film 23 while reducing the probability that external emissions contact the electrode assembly 21 after passing through the pressure relief mechanism 22.

[0123] It can be understood that the external emissions are at a lower temperature and lower pressure compared to their state before being ejected from the pressure relief mechanism 22.

[0124] It can be understood that the protective film 23 is configured such that in a state where the battery cell 20 is in thermal runaway, the emissions ejected from the pressure relief mechanism 22 can melt through the protective film 23.

[0125] That is to say, the protective film 23 can be melted through by the emissions generated by the battery cell 20 itself so that the pressure relief mechanism 22 can discharge the emissions it generates. Since the external emissions are at a lower temperature and lower pressure, the protective film 23 can block the external emissions from entering the battery cell 20 where it is located and contacting the electrode assembly 21.

[0126] In some embodiments, referring to Figures 3 to 6 , the protective film 23 includes a first film 231, and the first film 231 covers one side surface of the pressure relief mechanism 22 away from the electrode assembly 21.

[0127] That is to say, the first film 231 is attached to the pressure relief mechanism 22, which is conducive to reducing or even eliminating the surface of the pressure relief mechanism 22 directly exposed to the external environment of the battery cell 20.

[0128] In this way, the pressure relief mechanism 22 directly provides an installation position for the first film 231, and reduces the probability of direct contact between external emissions and the pressure relief mechanism 22, playing a certain protective role for the pressure relief mechanism 22; at the same time, it is conducive to installing the first film 231 from the outside of the battery cell 20, improving the installation convenience and facilitating the replacement of the first film 231.

[0129] There is no limit to the specific manner in which the first film 231 covers the surface of the pressure relief mechanism 22. For example, the first film 231 is bonded to the pressure relief mechanism 22.

[0130] In some embodiments, refer to Figure 7 、 Figure 8 and Figure 9 , the protective film 23 includes a second film 232, and the second film 232 covers the surface of the pressure relief mechanism 22 facing the electrode assembly 21.

[0131] In this way, in the normal working state of the battery cell 20, the pressure relief mechanism 22 can block and protect the second film 232, reducing the probability of the second film 232 being damaged due to factors such as collision.

[0132] In some embodiments provided with the housing 24, the second film 232 is located in the accommodation cavity 20a.

[0133] In some embodiments, refer to Figure 10 and Figure 15 , the battery cell 20 further includes a partition 25, and the partition 25 is located between the electrode assembly 21 and the pressure relief mechanism 22.

[0134] The partition 25 can separate the electrode assembly 21 and the pressure relief mechanism 22, so that a certain gap can be maintained between the electrode assembly 21 and the pressure relief mechanism 22 in the first direction, which is conducive to the emissions generated after the battery cell 20 undergoes thermal runaway entering the pressure relief mechanism 22 through the gap.

[0135] In some embodiments, refer to Figures 10 to 13 , the protective film 23 includes a third film 233, and the third film 233 is located between the partition 25 and the electrode assembly 21.

[0136] In this way, it is conducive to reducing the risk that external emissions can be blocked by the third film 233 after passing through the pressure relief mechanism 22 and the partition 25 in sequence, and reducing the risk of contact between external emissions and the electrode assembly 21.

[0137] In some embodiments, the third film 233 is adhesively fixed to the partition plate 25 and the electrode assembly 21 respectively.

[0138] In some embodiments, referring to Figure 14 and Figure 15 , the protective film 23 includes a fourth film 234, and the fourth film 234 is located between the partition plate 25 and the pressure relief mechanism 22.

[0139] Thus, it is beneficial to reduce the risk that the external emissions can be blocked by the fourth film 234 after passing through the pressure relief mechanism 22, and reduce the risk of contact between the external emissions and the electrode assembly 21.

[0140] In some embodiments, the fourth film 234 adheres to the surface of the partition plate 25 on the side close to the pressure relief mechanism 22.

[0141] In some embodiments provided with the housing 24, both the third film 233 and the fourth film 234 are respectively located in the accommodation cavity 20a.

[0142] In some embodiments, referring to Figure 16 , the protective film 23 further includes a fifth film 235, and the fifth film 235 is attached to the surface of the electrode assembly 21 facing the pressure relief mechanism 22.

[0143] Thus, it is beneficial to enable the protective film 23 to directly shield and protect the electrode assembly 21, and reduce the probability of contact between the electrode assembly 21 and the external emissions passing through the pressure relief mechanism 22.

[0144] In some embodiments provided with the housing 24, the fifth film 235 is located in the accommodation cavity 20a.

[0145] In some embodiments, referring to Figure 3 and Figure 5 , the housing 24 includes a housing body 241 and an end cover 242. The housing body 241 is provided with an accommodation space, one side of the accommodation space is open along the first direction, and the end cover 242 is covered on the open position of the accommodation space to be hermetically sealed with the housing body 241 to form the accommodation cavity 20a.

[0146] In some embodiments, the pressure relief mechanism 22 is provided on the end cover 242, and the partition plate 25 is located between the end cover 242 and the electrode assembly 21.

[0147] In some embodiments, referring to Figure 12 , Figure 13 and Figure 15 , the housing body 241 includes a first wall 2411, the first wall 2411 is located on the side opposite to the end cover 242 along the first direction, the pressure relief mechanism 22 is located on the first wall 2411, and the partition plate 25 is located between the first wall 2411 and the electrode assembly 21.

[0148] In some embodiments, the first wall 2411 is located on the bottom side of the battery cell 20 along the direction of gravity, and the separator 25 can support the electrode assembly 21.

[0149] In some embodiments, the material of the protective film 23 includes one of polyimide, polytetrafluoroethylene, fluorinated ethylene propylene, polyethylene naphthalate, polyethylene terephthalate, polyether ether ketone, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherimide, and ceramics.

[0150] Polyimide (PI) has excellent high-temperature tolerance and can withstand temperatures above 300°C. It has good mechanical strength, chemical stability, and electrical insulation properties.

[0151] Polytetrafluoroethylene (PTFE) can withstand temperatures up to 260°C and has good chemical resistance, low friction coefficient, and insulation properties.

[0152] Fluorinated ethylene propylene (FEP) has good high-temperature resistance and is suitable for high-temperature environments. It also has low adhesion, excellent chemical resistance, and transparency.

[0153] Polyethylene naphthalate (PEN) can maintain dimensional stability and transparency at relatively high temperatures.

[0154] Polyethylene terephthalate (PET) can improve its heat resistance through modification to be suitable for high-temperature environments.

[0155] Polyether ether ketone (PEEK) has excellent high-temperature resistance and can withstand relatively high continuous use temperatures. It also has good mechanical properties and chemical stability.

[0156] Polysulfone resin (PSU) has good high-temperature resistance and chemical stability.

[0157] Polyethersulfone (PES) is heat-resistant and suitable for high-temperature environments.

[0158] Polyphenylene sulfide (PPS) has good heat resistance, chemical resistance, and electrical insulation properties.

[0159] Polyetherimide (PEI) has good high-temperature resistance and mechanical strength and is suitable for electrical insulation and high-temperature sealing applications.

[0160] Ceramics can withstand extreme high temperatures and corrosive environments.

[0161] This helps the protective film 23 to withstand the impact and high temperature of external emissions and also helps to extend the service life of the protective film 23.

[0162] The specific type of ceramic material used in the structure of the protective film 23 can be alumina, zirconia, etc.

[0163] In some embodiments, referring to Figure 6 , the thickness dimension range of the protective film 23 is from 0.1 mm to 5 mm. That is, 0.1 mm ≤ d ≤ 5 mm.

[0164] This helps the protective film 23 to have a certain structural strength and reduces the probability of the protective film 23 being penetrated by external emissions; at the same time, it makes the structure of the protective film 23 compact.

[0165] In some embodiments, the thickness dimension range of the protective film 23 is from 0.5 mm to 5 mm. That is, 0.5 mm ≤ d ≤ 5 mm.

[0166] This further helps to reduce the probability of the protective film 23 being penetrated by external emissions; at the same time, it makes the structure of the protective film 23 compact.

[0167] The specific values of the thickness dimension of the protective film 23 can be 0.1 mm, 0.2 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm.

[0168] In some embodiments, the melting point range of the structure of the protective film 23 is from 85 °C to 1000 °C.

[0169] In this way, on the one hand, it is difficult for the protective film 23 to melt due to the heat released during the normal charging and discharging process of the battery cell 20, which helps to extend the service life of the protective film 23; on the other hand, it helps to reduce the probability of the protective film 23 melting at the high temperature of external emissions and causing the external emissions to pass through the protective film 23.

[0170] In some embodiments, the melting point range of the structure of the protective film 23 is from 150 °C to 1000 °C.

[0171] This further helps to extend the service life of the protective film 23.

[0172] The specific values of the melting point of the structure of the protective film 23 can be 85°C, 100°C, 120°C, 150°C, 160°C, 180°C, 200°C, 250, 300, 350, 400, 500, 600, 700, 800, 900, 1000°C, etc.

[0173] In some embodiments, the volumetric energy density range of the battery cell 20 is from 50 Wh / L to 1250 Wh / L.

[0174] Thus, it is beneficial to enable the protective film 23 to block the high temperature and impact of the emissions generated by other battery cells 20.

[0175] The specific values of the volumetric energy density of the battery cell 20 can be 50 Wh / L, 100 Wh / L, 150 Wh / L, 200 Wh / L, 300 Wh / L, 400 Wh / L, 500 Wh / L, 600 Wh / L, 700 Wh / L, 800 Wh / L, 900 Wh / L, 1000 Wh / L, 1100 Wh / L, 1200 Wh / L, 1250 Wh / L.

[0176] In a specific embodiment of the embodiments of the present application, the battery cell 20 is as follows:

[0177] The battery cell 20 includes an electrode assembly 21, a pressure relief mechanism 22, and a protective film 23. The pressure relief mechanism 22 is located on one side of the electrode assembly 21 along a first direction. The protective film 23 is located on at least one side of the pressure relief mechanism 22 along the first direction and on the same side of the pressure relief mechanism 22 as the electrode assembly 21 along the first direction. In a projection plane perpendicular to the first direction, at least a part of the projection of the pressure relief mechanism 22 along the first direction coincides with the projection of the protective film 23 along the first direction. The protective film 23 is configured to be able to block emissions outside the battery cell 20. In a projection plane perpendicular to the first direction, the projection of the pressure relief mechanism 22 along the first direction is within the projection range of the protective film 23 along the first direction. The material of the protective film 23 includes one of polyimide, polytetrafluoroethylene, fluorinated ethylene propylene, polyethylene naphthalate, polyethylene terephthalate, polyether ether ketone, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherimide, and ceramic. The thickness dimension of the protective film 23 is multiplied by the melting point of the structure of the protective film 23 to obtain a first product, and the first product is divided by the volume energy density of the battery cell 20 to obtain a first quotient. The value range of the first quotient is from 0.0068 to 100. The thickness dimension range of the protective film 23 is from 0.1 mm to 5 mm, the melting point range of the structure of the protective film 23 is from 85 °C to 1000 °C, and the volume energy density range of the battery cell 20 is from 50 Wh / L to 1250 Wh / L. The protective film 23 includes at least one of a first film 231, a second film 232, and a fifth film 235. The first film 231 covers one surface of the pressure relief mechanism 22 facing away from the electrode assembly 21, the second film 232 covers one surface of the pressure relief mechanism 22 facing the electrode assembly 21, and the fifth film 235 adheres to one surface of the electrode assembly 21 facing the pressure relief mechanism 22.

[0178] An embodiment of the present application further provides a battery device 100. Refer to Figure 2 , the battery device 100 includes a box body 10 and a plurality of battery cells 20 as described in any one of the foregoing. An accommodation space is provided in the box body 10, and the battery cells 20 are located in the accommodation space.

[0179] By adopting the battery cell 20 in the foregoing embodiment, it is beneficial to reduce the probability that other intact battery cells 20 also undergo thermal runaway after some battery cells 20 in the battery device 100 undergo thermal runaway, and it is beneficial to reduce the severity of thermal runaway of the battery device 100.

[0180] An embodiment of the present application further provides an electrical device. Refer to Figure 1 , the electrical device includes the battery device 100 in the foregoing embodiment, and the battery device 100 is used as the power source of the electrical device.

[0181] By adopting the battery device 100 in the foregoing embodiment, it is beneficial to reduce the risk of damage to other components in the electrical device when a thermal runaway occurs in the battery device 100.

[0182] The various embodiments / implementation manners provided in this application can be combined with each other without conflict.

[0183] The above are only the preferred embodiments of this application and are not used to limit the embodiments in this application. For those skilled in the art, the embodiments of this application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of this application shall be included within the protection scope of the embodiments of this application.

Claims

1. A battery cell, characterized in that, Comprising: An electrode assembly; A pressure relief mechanism located on one side of the electrode assembly along a first direction; A protective film located on at least one side of the pressure relief mechanism along the first direction and on the same side of the electrode assembly as the pressure relief mechanism along the first direction. In a projection plane perpendicular to the first direction, at least a part of the projection of the pressure relief mechanism along the first direction coincides with the projection of the protective film along the first direction. The protective film is configured to be able to block emissions outside the battery cell. The thickness dimension of the protective film is multiplied by the melting point of the structure of the protective film to obtain a first product, and the first product is divided by the volume energy density of the battery cell to obtain a first quotient. The value range of the first quotient is from 0.0068 to 100.

2. The battery cell according to claim 1, wherein, The value range of the first quotient is from 0.06 to 100.

3. The battery cell according to claim 1, characterized in that, In a projection plane perpendicular to the first direction, the projection of the pressure relief mechanism along the first direction is located within the projection range of the protective film along the first direction.

4. The battery cell according to claim 1, characterized in that, The protective film includes a first film that covers one side surface of the pressure relief mechanism facing away from the electrode assembly; And / or, the protective film includes a second film that covers one side surface of the pressure relief mechanism facing the electrode assembly.

5. The battery cell according to claim 1, characterized in that The battery cell further includes a separator located between the electrode assembly and the pressure relief mechanism; The protective film includes a third film located between the separator and the electrode assembly; And / or, the protective film includes a fourth film located between the separator and the pressure relief mechanism.

6. The battery cell according to claim 1, characterized in that, The protective film further includes a fifth film attached to the surface of the electrode assembly facing the pressure relief mechanism side.

7. The battery cell according to claim 1, characterized in that, The material of the protective film includes one of polyimide, polytetrafluoroethylene, fluorinated ethylene propylene, polyethylene naphthalate, polyethylene terephthalate, polyether ether ketone, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherimide, and ceramic.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The thickness dimension range of the protective film is from 0.1 mm to 5 mm; And / or, the melting point range of the structure of the protective film is from 85 °C to 1000 °C; And / or, the volume energy density range of the battery cell is from 50 Wh / L to 1250 Wh / L.

9. The battery cell according to any one of claims 1 to 7, characterized in that, The thickness dimension range of the protective film is from 0.5 mm to 5 mm; And / or, the melting point range of the structure of the protective film is from 150 °C to 1000 °C.

10. A battery device, characterized in that, The battery device includes a box body and a plurality of battery cells as described in any one of claims 1 to 9. An accommodation space is provided in the box body, and the battery cells are located in the accommodation space.

11. An electrical device, characterized in that, The electrical device includes the battery device as described in claim 10, and the battery device is used as the power source of the electrical device.

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