Protective film, battery cell, battery, and electric device

Abstract

A protective film, a battery cell comprising the protective film, a battery, and an electric device. The protective film is used for wrapping an electrode assembly, and the protective film comprises a film body and detection units. The detection units are formed on the film body, and the detection units are used for detecting information related to the electrode assembly. The detection units are formed on the film body, so that the space of the battery cell jointly occupied by the detection units and the film body is reduced, so that the group margin of the battery cell is improved, thereby improving the energy density of the battery.

Description

Protective film, battery cells, batteries and electrical equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202321866336.7, filed on July 17, 2023, entitled “Protective film, battery cell, battery and electrical equipment,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a protective film, a battery cell, a battery, and an electrical device. Background Art

[0004] Batteries are widely used in electronic devices such as electric vehicles, electric cars, electric airplanes, electric ships, etc.

[0005] How to improve the energy density of batteries is an urgent problem to be solved in battery technology.

[0006] Summary of the Invention

[0007] In view of the above problems, the present application provides a protective film, a battery cell, a battery and an electrical device, which can improve the safety of the battery.

[0008] In a first aspect, the present application provides a protective film for wrapping an electrode assembly. The protective film includes a film body and a detection unit. The detection unit is formed on the film body and is used to detect information related to the electrode assembly.

[0009] In the technical solution of the embodiment of the present application, the detection unit is formed on the membrane body, so that the space occupied by the detection unit and the membrane body inside the battery cell is reduced, which is beneficial to improving the group margin of the battery cell and further improving the energy density of the battery.

[0010] In some embodiments, a recess is provided on the membrane body, and at least a portion of the detection unit is accommodated in the recess. This design allows at least a portion of the detection unit to be located inside the membrane body, further improving the group margin of the battery cells.

[0011] In some embodiments, the detection unit is formed on the membrane body by spraying, screen printing or 3D printing. This design allows the detection unit to be assembled while the membrane body is being produced, thereby improving assembly efficiency.

[0012] In some embodiments, the detection unit includes a circuit and an insulating layer, with the circuit located between the insulating layer and the membrane body. This design makes the membrane body part of the detection unit, reducing the space occupied by the detection unit and the membrane body within the battery cell, thereby improving the group margin within the battery cell.

[0013] In some embodiments, the circuit is formed on the membrane body by spraying, screen printing, or 3D printing, and the insulating layer is also formed on the membrane body by spraying, screen printing, or 3D printing. The detection unit adopts such a forming method so that after the protective film is processed, the circuit does not protrude from the membrane body, thereby reducing the risk of single-point overvoltage in the electrode assembly caused by the circuit protruding from the membrane body.

[0014] In some embodiments, the detection unit is a sheet-like structure. This design, on the one hand, allows the sheet-like detection unit to fit closely with the electrode assembly, improving the detection unit's detection accuracy. On the other hand, it also ensures a high surface flatness on the protective film, reducing the risk of single-point overvoltage in the electrode assembly.

[0015] In some embodiments, there are multiple detection units, and the multiple detection units are arranged at intervals. Such a design can obtain more samples of relevant information about the electrode assembly, and thus the relevant information about the electrode assembly obtained is more accurate.

[0016] In some embodiments, the multiple detection units include at least one of a pressure detection unit, a strain detection unit, an air pressure detection unit, and a temperature detection unit. This design can collect multiple information of the electrode assembly in real time, providing more comprehensive monitoring of the electrode assembly.

[0017] In some embodiments, the number of detection points per unit area of ​​the detection unit is A, satisfying the following: A ≥ 4 points / cm². The density of the multiple detection units is designed within a reasonable range to reduce the risk that the detection unit will not be able to promptly capture abnormal information after a battery cell anomaly occurs due to the number of detection points per unit area being less than 4 points / cm².

[0018] In some embodiments, the detection unit includes a pressure detection unit. The detection range of the pressure detection unit is P1, which satisfies the following conditions: 0 < P1 ≤ 10 MPa, and the detection accuracy is no less than 10 kPa. In some embodiments, when a battery cell is in normal operating condition, its internal expansion force is generally 10 MPa. Therefore, the pressure detection range P1 of the pressure detection unit is set between 0 and 10 MPa to conform to actual operating conditions, thereby reducing the additional cost of selecting a pressure detection unit with an excessively large pressure detection range. Furthermore, to ensure that the detection results have a certain reference value, the detection accuracy of the pressure detection unit can be set to no less than 10 kPa.

[0019] In some embodiments, the detection unit includes a temperature detection unit. The detection range of the temperature detection unit is P2, which satisfies the following conditions: -40°C ≤ P2 ≤ 400°C, and the detection accuracy is not less than 0.1°C. In some embodiments, when a battery cell is in normal operation, its internal temperature is generally between -40°C and 400°C. Therefore, the temperature detection range P2 of the temperature detection unit is set to between -40°C and 400°C to conform to actual operating conditions, thereby reducing the additional cost of selecting a temperature detection unit with an excessively wide temperature detection range. At the same time, to ensure that the detection results have a certain reference value, the detection accuracy of the temperature detection unit can be set to not less than 0.1°C.

[0020] In some embodiments, the detection unit includes a strain detection unit. The detection range of the strain detection unit is P3, satisfying the following conditions: 0 < P3 ≤ 20%, and a detection accuracy of no less than 1%. In some embodiments, when the battery cell is in normal operating condition, the stress of the electrode assembly is generally between 0 and 20%. Therefore, the strain detection range P3 of the strain detection unit is set to between 0 and 20% to conform to actual operating conditions and reduce the additional cost of using a strain detection unit with an excessively wide strain detection range. At the same time, to ensure that the detection results have a certain reference value, the detection accuracy of the strain detection unit can be set to no less than 1%.

[0021] In some embodiments, the detection unit includes an air pressure detection unit. The detection range of the air pressure detection unit is P4, which satisfies the following conditions: 0<P4≤4MPa, and the detection accuracy is not less than 10kPa. In some embodiments, when the battery cell is in normal working condition, the electrode assembly produces gas, causing the pressure inside the battery cell to generally be between 0 and 4MPa. To this end, the air pressure detection range P4 of the air pressure detection unit is set to between 0 and 4MPa to conform to actual operating conditions, thereby reducing the additional cost caused by selecting an air pressure detection unit with an overly wide air pressure detection range. At the same time, to ensure that the detection results have a certain reference value, the detection accuracy of the air pressure detection unit can be set to not less than 10kPa.

[0022] In some embodiments, the maximum thickness of the protective film is T, satisfying: T ≤ 200 μm. In some embodiments, the minimum distance between the electrode assembly and the wall of the battery cell housing is generally 200 μm. Designing the maximum thickness of the protective film within a reasonable range makes it easier to insert the protective film into the housing after the electrode assembly is covered with it, reducing the risk of the electrode assembly being scratched by the wall of the housing when the protective film is covered and inserted into the housing, thereby causing insulation failure between the electrode assembly and the housing.

[0023] In a second aspect, the present application provides a battery cell, which includes a housing, an electrode assembly and the protective film in the above embodiment, wherein the electrode assembly is disposed in the housing, and the protective film is disposed in the housing and wraps the electrode assembly.

[0024] In some embodiments, the electrode assembly is flat, and the outer peripheral surface of the electrode assembly includes two first surfaces arranged opposite to each other along the thickness direction of the electrode assembly, two second surfaces arranged opposite to each other along the width direction of the electrode assembly, and a bent surface connecting the first surface and the second surface. The protective film includes a first area covering the first surface, the first area is provided with a detection unit, and / or the protective film also includes a second area covering the bent surface, the second area is provided with a detection unit, and / or the protective film also includes a third area covering the second surface, the third area is provided with a detection unit. The detection unit can be provided in different areas of the protective film, and the information of the electrode assemblies in different areas can be compared and analyzed, which is conducive to issuing more targeted early warning information when an abnormality occurs in a specific area of ​​the battery cell.

[0025] In some embodiments, a through hole is provided in the wall of the housing, and the battery cell further includes a wire, one end of the wire being connected to the detection unit, and the other end of the wire passing through the housing through the through hole, and the wire is used to transmit the signal of the detection unit. Using a wire to transmit the signal of the detection unit can reduce the risk of electromagnetic interference to the signal of the detection unit. The detection unit may also include a wireless communication module, which is used to transmit the signal of the detection unit. Using a wireless communication module to transmit the signal of the detection unit eliminates the need for assembly operations such as wire management and wiring, which can reduce the difficulty of assembling the battery cell.

[0026] In some embodiments, the housing includes a shell and an end cap, the shell having an opening, and the end cap sealing the opening. A through hole is provided in the end cap. The wires are led out through the through hole in the end cap. On the one hand, compared to a solution in which the wires are led out through the side wall of the housing, the risk of the wires being corroded by the electrolyte soaking can be reduced. On the other hand, when multiple battery cells are grouped to form a battery, the wires are led out through the end cap. Compared to a solution in which the wires are led out through the side wall of the housing, the risk of the wires being damaged by the squeezing force caused by the mutual squeezing of adjacent battery cells can be reduced. On another hand, generally, the end cap is the component of the housing farthest from the ground. For this reason, providing a through hole in the end cap can reduce the risk of electrolyte leakage from the area between the end cap and the wire.

[0027] In some embodiments, the battery cell further includes a sealing member disposed in the through hole to fill a gap between the conductive wire and the through hole.

[0028] By filling the gap between the wire and the through hole with a sealant, the risk of electrolyte in the battery cell leaking from the gap between the wire and the through hole can be effectively reduced.

[0029] In a third aspect, the present application provides a battery comprising the battery cell in the above embodiment.

[0030] In a fourth aspect, the present application provides an electrical device, which includes the battery in the above embodiment, and the battery is used to provide electrical energy.

[0031] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, which can be implemented in accordance with the contents of the specification, and to make other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0033] FIG1 is a schematic structural diagram of a vehicle according to some embodiments of the present application;

[0034] FIG2 is an exploded view of a battery according to some embodiments of the present application;

[0035] FIG3 is a schematic structural diagram of a battery cell according to some embodiments of the present application;

[0036] FIG4 is an expanded view of a protective film according to some embodiments of the present application;

[0037] FIG5 is a cross-sectional view of a protective film according to some embodiments of the present application;

[0038] FIG6 is an exploded view of a portion of the structure of a battery cell according to some other embodiments of the present application;

[0039] FIG7 is an expanded view of the protective film of some other embodiments of the present application;

[0040] FIG8 is a top view of a top cover according to some embodiments of the present application;

[0041] FIG9 is a schematic diagram of a partial structure of a battery according to some embodiments of the present application.

[0042] The reference numerals in the specific embodiment are as follows: 1000 - vehicle; 200 - controller; 300 - motor; 100 - battery; 11 - housing; 111 - first part; 112 - second part; 12-battery cell; 121-housing; 1211-end cap; 12111-through hole; 1212-housing; 122-electrode assembly; 1221-first surface; 1222-second surface; 1223-bending surface; 123-protective film; 1231-membrane body; 12311-first region; 12312-second region; 12313-third region; 12314-bottom region; 12315-substrate region; 1232-detection unit; 12321-base; 12322-circuit; 123221-sensitive layer; 123222-electrode; 12323-insulating layer; 124-adapter; 125-electrode terminal; 126-wire; 127-seal; 13-host computer. DETAILED DESCRIPTION

[0043] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art 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 specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0045] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0046] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0047] 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).

[0048] 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., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and 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 device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0049] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0050] In this application, battery cells may include, but are not limited to, lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries. The shape of a battery cell may include, but is not limited to, a cylinder, a flat body, a rectangular parallelepiped, or other shapes. Battery cells, depending on the packaging method, may include, but are not limited to, cylindrical battery cells, prismatic battery cells, and soft-pack battery cells.

[0051] In some high-power applications such as electric vehicles, the application of batteries includes three levels: battery cells, battery modules and batteries. The battery module is formed by electrically connecting a certain number of battery cells together and placing them in a frame in order to protect the battery cells from external impact, heat, vibration, etc. The battery refers to the final state of the battery system installed in the electric vehicle. The battery mentioned in the embodiments of the present application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. The battery generally includes a box for encapsulating one or more battery cells. The box can reduce the risk of liquid or other foreign matter affecting the charging or discharging of the battery cells.

[0052] The following description will mainly focus on rectangular parallelepiped battery cells. It should be understood that the embodiments described below are also applicable to cylindrical battery cells or soft-pack battery cells in some aspects.

[0053] In a typical battery cell structure, the battery cell includes a housing component, an electrode assembly, and an electrolyte. The housing component can be an end cap or a shell, and the end cap closes an opening of the shell to define a receiving space for receiving the electrode assembly.

[0054] The electrode assembly is housed in the housing. It includes a positive electrode sheet, a negative electrode sheet, and a separator. Battery cells primarily operate by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive electrode collector. The uncoated positive electrode collector protrudes from the coated positive electrode collector, serving as the positive electrode tab. For lithium-ion batteries, for example, the positive electrode collector can be made of aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative electrode collector. The uncoated negative electrode collector protrudes from the coated negative electrode collector, serving as the negative electrode tab. The negative electrode collector can be made of copper, and the negative electrode active material can be carbon, silicon, or other materials. In order to pass high current without melting, the number of positive tabs is multiple and stacked together, and the number of negative tabs is multiple and stacked together. In addition, the electrode assembly can be formed in a manner including but not limited to winding or lamination.

[0055] When the electrode assembly is placed in the housing, the outer surface of the electrode assembly is typically covered with an insulating film to reduce the risk of scratches from the housing and to insulate the electrode assembly from the housing wall. The insulating film is generally soft and flexible. One insulating film can cover one or more electrode assemblies. For example, when multiple electrode assemblies are housed within the housing, one insulating film can cover multiple electrode assemblies.

[0056] The tabs generally lead out the electrical energy of the electrode assembly by being electrically connected to the conductive member. In some cases, the conductive member is a transition piece connecting the tabs and the electrode terminals. In other cases, the conductive member is the electrode terminal.

[0057] Electrode terminals generally include positive and negative terminals. For rectangular battery cells, electrode terminals are typically located in the end caps. In some other cases, electrode terminals may also be located in the housing. Multiple battery cells can be connected in series and / or in parallel via the electrode terminals for various applications.

[0058] The development of battery technology must take into account multiple design factors at the same time, such as reliability, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, the energy density of the battery must also be considered.

[0059] Electrode terminals generally include positive and negative electrode terminals. For rectangular battery cells, the electrode terminals are typically located on the end caps. Multiple battery cells are connected in series and / or in parallel via the electrode terminals for various applications.

[0060] When a battery cell is in use, short circuits, overcharge, and other phenomena may occur. These phenomena may cause thermal runaway inside the battery cell, resulting in a sudden increase in pressure or temperature, which may cause the battery cell to explode or catch fire. In order to issue a timely warning when the above phenomena occur in the battery cell, a detection unit is generally set inside or outside the battery cell. The detection unit is used to detect information related to the electrode assembly, for example, to detect the pressure, stress, temperature, and gas pressure of the electrode assembly. The signal obtained by the detection unit is generally led out of the battery cell through a wire and transmitted to a host computer, such as the battery management system of the battery. The battery management system compares and judges the received signal with the pre-set standard value. If the battery cell is at risk of thermal runaway or the temperature, pressure, stress, or gas pressure of the electrode assembly inside the battery cell is abnormal, the battery management system will take corresponding measures, such as issuing a thermal runaway warning. In some cases, in order to improve the detection accuracy of the detection unit, the detection unit is set inside the shell of the battery cell, for example, the detection unit is attached to the inner wall of the shell. Since the detection unit occupies the internal space of the battery cell, the group margin of the battery cell is reduced, so that the energy density of the battery is reduced and the performance of the battery is reduced.

[0061] In light of this, the present application provides a protective film for wrapping an electrode assembly. The protective film comprises a membrane body and a detection unit, which is formed within the membrane body and is used to detect information related to the electrode assembly. The detection unit is formed within the membrane body, reducing the space occupied by the detection unit and the membrane body within the battery cell, thereby improving the cell group margin and, in turn, the battery's energy density.

[0062] The technical solutions described in the embodiments of the present application are applicable to battery cells, batteries, and electrical equipment using batteries.

[0063] Electrical equipment includes, but is not limited to, battery vehicles, electric vehicles, ships, and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.

[0064] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0065] For example, FIG1 is a schematic diagram of the structure of a vehicle 1000 according to some embodiments of the present application. Vehicle 1000 may be a fuel-powered vehicle, a gas-powered vehicle, or a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle. Vehicle 1000 may be provided with a motor 300, a controller 200, and a battery 100. Controller 200 controls the battery 100 to power the motor. For example, battery 100 may be provided at the bottom, front, or rear of vehicle 1000. Battery 100 may be used to power vehicle 1000. For example, battery 100 may serve as an operating power source for vehicle 1000 and may be used for the circuit 12322 systems of vehicle 1000, such as for starting, navigation, and operating the vehicle 1000. In another embodiment of the present application, battery 100 may serve not only as an operating power source for vehicle 1000 but also as a driving power source for vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for vehicle 1000.

[0066] To meet different power requirements, the battery 100 may include multiple battery cells 12, wherein the multiple battery cells 12 can be connected in series, in parallel, or in a hybrid connection. Hybrid connection refers to a mixture of series and parallel connections. The battery 100 may also be referred to as a battery pack. Optionally, multiple battery cells 12 may first be connected in series, in parallel, or in a hybrid connection to form a battery module, and multiple battery modules may then be connected in series, in parallel, or in a hybrid connection to form the battery 100. In other words, multiple battery cells 12 may directly form the battery 100, or they may first form battery modules, which may then form the battery 100.

[0067] For example, referring to FIG. 2 , FIG. 2 is an exploded view of a battery 100 according to some embodiments of the present application. The battery 100 may include a plurality of battery cells 12. The battery 100 may also include a housing 11 having a hollow interior, and the plurality of battery cells 12 are housed within the housing 11. As shown in FIG. 2 , these are referred to herein as a first portion 111 and a second portion 112, respectively. The first portion 111 and the second portion 112 are fastened together. The shapes of the first portion 111 and the second portion 112 may be determined based on the combined shape of the plurality of battery cells 12. The first portion 111 and the second portion 112 may each have a single opening. For example, the first portion 111 and the second portion 112 may each be a hollow rectangular parallelepiped, each with only one open face. The opening of the first portion 111 and the opening of the second portion 112 are arranged opposite each other, and the first portion 111 and the second portion 112 are fastened together to form the housing 11 having a closed chamber. The plurality of battery cells 12 are then arranged in parallel, in series, or in a mixed configuration and then placed within the housing 11 formed by the fastening of the first portion 111 and the second portion 112.

[0068] Optionally, the battery 100 may also include other structures, which are not described in detail here. For example, the battery 100 may also include a busbar assembly, which is used to electrically connect multiple battery cells 12, such as in parallel, series, or mixed connection. Specifically, the busbar assembly can electrically connect the battery cells 12 by connecting to the electrode terminals 125 of the battery cells 12. Furthermore, the busbar assembly can be fixed to the electrode terminals 125 of the battery cells 12 by welding.

[0069] The number of battery cells 12 can be set to any value according to different power requirements. Multiple battery cells 12 can be connected in series, parallel, or in a hybrid manner to achieve a larger capacity or power. Since the number of battery cells 12 included in each battery 100 may be large, for ease of installation, the battery cells 12 can be grouped, and each group of battery cells 12 constitutes a battery module. The number of battery cells 12 included in a battery module is not limited and can be set according to requirements. The battery 100 may include multiple battery modules, which can be connected in series, parallel, or in a hybrid manner.

[0070] Please refer to Figure 3, which is an exploded view of a battery cell 12 in some embodiments of the present application. The battery cell 12 includes one or more electrode assemblies 122 and a shell 121. The shell 121 may include a housing 1212. The multiple walls of the housing 1212, i.e., the multiple walls of the housing 121, form a cavity, which can be used to accommodate the electrode assembly 122. The housing 1212 is determined according to the shape of the one or more electrode assemblies 122 after being combined. For example, the housing 1212 can be a hollow cuboid, a cube, or a regular polyhedron, and one of the faces of the housing 1212 has an opening so that one or more electrode assemblies 122 can be placed in the housing 1212. The housing 1212 is filled with an electrolyte, such as an electrolyte solution.

[0071] The battery cell 12 may also include two electrode terminals 125, which may be disposed on the end cap 1211. The end cap 1211 is typically in the shape of a flat plate, with the two electrode terminals 125 fixed to the flat surface of the end cap 1211. The two electrode terminals 125 are respectively a positive electrode terminal and a negative electrode terminal. Each electrode terminal 125 is provided with a corresponding adapter 124, which is located between the end cap 1211 and the electrode assembly 122 and is used to electrically connect the electrode assembly 122 and the electrode terminal 125. In the battery cell 12, the electrode assembly 122 may be provided as a single or multiple electrode assemblies, depending on actual usage requirements. In some embodiments, the battery cell 12 may also include an insulating film, which is used to wrap the electrode assembly 122. One insulating film may cover one or more electrode assemblies 122. For example, when multiple electrode assemblies 122 are accommodated in the accommodation space, one insulating film may cover multiple electrode assemblies 122. In some cases, the insulating film may also be referred to as a protective film 123.

[0072] According to some embodiments of the present application, please refer to Figures 2 and 3. The present application provides a protective film 123 for wrapping the electrode assembly 122. The protective film 123 includes a film body 1231 and a detection unit 1232. The detection unit 1232 is formed on the film body 1231. The detection unit 1232 is used to detect information related to the electrode assembly 122.

[0073] The detection unit 1232 is generally a thin film sensor, generally including an insulating layer 12323, a circuit 12322 and a substrate 12321. The circuit 12322 generally includes a sensitive layer 123221 and an electrode 123222. The sensitive layer 123221 is a powdery substance usually made of oxide particles or nanomaterials. Changes in the resistance of the sensitive layer 123221 can reflect information such as the pressure, stress, temperature of the electrode assembly 122, and the gas pressure of the gas produced by the electrode assembly 122. The electrode 123222 is used to convert the resistance change of the sensitive layer 123221 into an electrical signal. The electrode 123222 is generally electrically connected to the wire 126 and the host computer 13.

[0074] The detection unit 1232 is formed on the membrane body 1231, which means that the detection unit 1232 is formed on the membrane body 1231 at the same time as the membrane body 1231 is produced. The membrane body 1231 can serve as the insulating layer 12323 and / or substrate 12321 of the detection unit 1232, while also maintaining the thickness of the protective film 123 substantially unchanged. This improves the group margin of the battery cell 12, which can be understood as the percentage of the internal space of the battery cell 12 occupied by the electrode assembly 122.

[0075] The detection unit 1232 can be formed on two surfaces of the membrane body 1231 along its thickness direction or inside the membrane body 1231.

[0076] The shape, size and accuracy of the detection unit 1232 can be adjusted according to detection requirements.

[0077] In some embodiments, multiple detection units 1232 can be provided, and multiple detection units 1232 are distributed on the entire outer surface of the electrode assembly 122. Multiple detection units 1232 formed on the membrane body 1231 will form multiple detection areas. In each detection area, the expansion force, and / or stress and / or air pressure, and / or temperature and other sensing signals of multiple points of the electrode assembly 122 can be obtained, thereby realizing the detection of signals such as the expansion force of the electrode assembly 122, the stress of the electrode assembly 122, the air pressure inside the battery cell 12, and the temperature of the electrode assembly 122. The above-mentioned signals can be transmitted to the host computer 13 for processing via the wire 126, etc. During the battery 100 test process, the host computer 13 can be a computer, processor, etc. During the use of the battery 100, the host computer 13 can be the battery management system of the battery 100. After processing the above-mentioned sensor signals, the battery management system can present the regionalized expansion force of the electrode assembly 122, the stress of the electrode assembly 122, the air pressure inside the battery cell 12, and the distribution diagram of the temperature of the electrode assembly 122 and the corresponding specific values, and conduct comparative analysis on the information of each area, and perform targeted warnings and other operations for areas with abnormal information.

[0078] The detection area can be set according to actual needs. The outer peripheral surface of the electrode assembly 122 generally includes a large surface arranged oppositely along its thickness direction, a side surface arranged oppositely along its width direction, and a bent surface 1223 connecting adjacent large surfaces and side surfaces. The detection area can correspond to the large surface, and / or the side surface, and / or the bent surface 1223 of the electrode assembly 122. In some embodiments, to improve the accuracy of the detection results, the area of ​​the detection area is generally 80% of the area of ​​the area to be tested. For example, if the area to be tested is a large surface, the detection area is 80% of the area of ​​the large surface. If the area to be tested is also a portion of the large surface, the detection area is 80% of the area of ​​the portion of the large surface to be tested.

[0079] In some embodiments, the detection unit 1232 may be in the form of a sheet or a film, and may be made of a flexible material, bendable and foldable, and have good flatness.

[0080] When assembling the protective film 123, the detection unit 1232 can be first formed on the film body 1231, and then the protective film 123 can be wrapped around the outer surface of the electrode assembly 122. Finally, the overlapping portions of the protective film 123 wrapped around the electrode assembly 122 are heat-fused to complete the assembly of the protective film 123. When the electrode assembly 122 wrapped with the protective film 123 is installed in the outer shell 121 of the battery cell 12, the wire 126 used to transmit the signal of the detection unit 1232 can be first led out from the outer shell 121 of the battery 100, and then the accommodating space of the outer shell 121 for accommodating the electrode assembly 122 can be sealed by welding or other methods.

[0081] In the technical solution of the embodiment of the present application, the detection unit 1232 is formed on the membrane body 1231, so that the space occupied by the detection unit 1232 and the membrane body 1231 inside the battery cell 12 is reduced, which is beneficial to improving the group margin of the battery cell 12 and further improving the energy density of the battery 100.

[0082] According to some embodiments of the present application, referring to FIG. 5 , a recess is provided on the membrane body 1231 , and at least a portion of the detection unit 1232 is accommodated in the recess.

[0083] The recessed portion on the membrane body 1231 can be naturally formed during the molding process of the membrane body 1231 by the equipment used to process the membrane body 1231. In some embodiments, using 3D printing as an example, the path of the 3D printer's nozzle can be designed to create the recessed portion during the molding process. After the recessed portion is formed as designed, the nozzle spray material can be changed to spray the circuit 12322 into the recessed portion. Subsequently, an insulating layer 12323 is sprayed onto the membrane body 1231 to form the detection unit 1232.

[0084] In some embodiments, the thickness of the membrane body 1231 of the molded detection unit 1232 may also be consistent with the thickness of the membrane body 1231 in the original design.

[0085] Such a design enables at least a portion of the detection unit 1232 to be located inside the mold body, further improving the group margin of the battery cells 12 .

[0086] According to some embodiments of the present application, the detection unit 1232 is formed on the membrane body 1231 by spraying, screen printing or 3D printing.

[0087] Spraying can be called a powder spraying process. Powder spraying equipment can be used to spray different raw materials onto the carrier platform. After the powder solidifies and forms, a layered structure is formed, such as the insulating layer 12323, circuit 12322, substrate 12321, etc. of the detection unit 1232.

[0088] The screen printing process can print the circuit 12322 onto the substrate 12321. After printing, the circuit 12322 can be formed on the film body 1231 by heating and curing. Then, the insulating layer 12323 is attached to the substrate 12321. The insulating layer 12323, the circuit 12322 and the substrate 12321 are formed into an integrated structure through processes such as heat pressing. The film body 1231 can serve as the substrate 12321 and / or the insulating layer 12323. In the embodiment where the film body 1231 serves as the substrate 12321 and the insulating layer 12323, the substrate 12321, the insulating layer 12323 and the circuit 12322 can serve as a three-layer structure, and the protective film 123 is formed through a heat pressing process. The thickness of the protective film 123 can be substantially consistent with the thickness of the protective film 123 produced by conventional methods.

[0089] The base 12321 can be printed using a 3D printing device first, and then the powder can be replaced to print the circuit 12322 on the base 12321. Finally, the powder can be replaced again to cover the circuit 12322 and the base 12321 with an insulating layer 12323 to form the detection unit 1232 on the membrane body 1231.

[0090] The detection unit 1232 is formed on the membrane body 1231 by spraying, screen printing or 3D printing. This design allows the assembly of the detection unit 1232 to be completed while the membrane body 1231 is being produced, thereby improving assembly efficiency.

[0091] According to some embodiments of the present application, the detection unit 1232 includes a circuit 12322 and an insulating layer 12323 , and the circuit 12322 is located between the insulating layer 12323 and the membrane body 1231 .

[0092] Circuit 12322 is located between insulating layer 12323 and membrane body 1231, meaning that detection unit 1232 no longer requires substrate 12321, requiring only circuit 12322 and insulating layer 12323, thus reducing its overall thickness. Alternatively, membrane body 1231 can be understood as serving as substrate 12321 for detection unit 1232, meaning that membrane body 1231 is part of detection unit 1232.

[0093] The detection unit 1232 includes a circuit 12322 and an insulating layer 12323. The circuit 12322 is located between the insulating layer 12323 and the membrane body 1231, so that the membrane body 1231 is a part of the detection unit 1232, reducing the space occupied by the detection unit 1232 and the membrane body 1231 inside the battery cell 12, and improving the group margin inside the battery cell 12.

[0094] According to some embodiments of the present application, the circuit 12322 is formed on the membrane body 1231 by spraying, screen printing or 3D printing, and the insulating layer 12323 is formed on the membrane body 1231 by spraying, screen printing or 3D printing.

[0095] The insulating layer 12323 is formed on the membrane body 1231 by spraying, screen printing or 3D printing, which means that in some embodiments, the insulating layer 12323 can completely cover the membrane body 1231, and the circuit 12322 is located between the insulating layer 12323 and the membrane body 1231. The gaps between adjacent circuits 12322 can be filled with powder to form the insulating layer 12323 through the above process, so that the circuit 12322 will not protrude from the membrane body 1231. At the same time, the number of stress concentration points on the protective film 123 will also be reduced, reducing the risk of single-point overvoltage of the electrode assembly 122.

[0096] The detection unit 1232 adopts the above-mentioned molding method, so that after the protective film 123 is processed, the circuit 12322 will not protrude from the film body 1231, reducing the risk of single-point overvoltage on the surface of the electrode assembly 122.

[0097] According to some embodiments of the present application, the detection unit 1232 is a sheet-like structure.

[0098] The sheet-like detection unit 1232 generally has a high degree of flatness and a high degree of fit with the electrode assembly 122 .

[0099] This design, on the one hand, allows the sheet-shaped detection unit 1232 to fit closely with the electrode assembly 122, thereby improving the detection accuracy of the detection unit 1232. On the other hand, it allows the surface flatness of the protective film 123 to be higher, thereby reducing the risk of single-point overpressure on the electrode assembly 122.

[0100] According to some embodiments of the present application, referring to FIG. 4 , there are multiple detection units 1232 , and the multiple detection units 1232 are arranged at intervals.

[0101] The detection units 1232 may be distributed in an array or randomly.

[0102] With this design, more samples of relevant information about the electrode assembly 122 are obtained, and thus the relevant information about the electrode assembly 122 is more accurate.

[0103] According to some embodiments of the present application, the plurality of detection units 1232 include at least one of a pressure detection unit, a strain detection unit, an air pressure detection unit, and a temperature detection unit.

[0104] The protective film 123 may be integrated with a pressure detection unit, and / or a strain detection unit, and / or an air pressure detection unit, and / or a temperature detection unit.

[0105] The pressure detection unit includes one or more pressure sensors of piezoresistive, piezoelectric, capacitive, etc. that can be made into a sheet structure.

[0106] The strain detection unit includes one or more strain sensors such as resistance strain gauge, semiconductor strain gauge, alloy type, capacitance type, etc. that can be made into a sheet structure.

[0107] The air pressure detection unit includes one or more of the air pressure sensors of piezoresistive, piezoelectric, capacitive, pressure-variable, photoelectric, and pressure-sensitive types that can be made into a sheet structure.

[0108] The temperature detection unit includes one or more types of resistive, capacitive, and other air pressure sensors that can be made into a sheet structure.

[0109] Such a design can collect various information of the electrode assembly 122 in real time, and monitor the electrode assembly 122 more comprehensively.

[0110] According to some embodiments of the present application, the number of detection points per unit area of ​​the detection unit 1232 is A, satisfying: A≥4 points / cm2.

[0111] The value of A can be 4 points, 5 points, 6 points, 7 points, 8 points, 9 points, 10 points, 11 points, 12 points, 13 points, 14 points, 15 points, 16 points, 17 points, 18 points, 19 points, 20 points, etc. per square centimeter.

[0112] By designing the density of the plurality of detection units 1232 within a reasonable range, the number of detection points per unit area can be increased, so that when an abnormality occurs in the battery cell 12 , the detection unit 1232 can capture the abnormality information in a timely manner.

[0113] According to some embodiments of the present application, the detection unit 1232 includes a pressure detection unit, the detection range of the pressure detection unit is P1, and it satisfies: 0<P1≤10MPa, and the detection accuracy is not less than 10kPa.

[0114] The pressure detection range of the pressure detection unit is P1, and P1 can take any value of 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa or 10Mpa. At the same time, the detection accuracy of the pressure detection unit can be no less than 10kPa.

[0115] In some embodiments, the internal expansion force of the battery cell 12 under normal operating conditions is generally 10 MPa. Therefore, the pressure detection range P1 of the pressure detection unit is set to between 0 and 10 MPa to meet actual operating conditions and reduce the additional cost of using a pressure detection unit with an excessively large pressure detection range. Furthermore, to ensure that the detection results have a certain reference value, the detection accuracy of the pressure detection unit can be set to no less than 10 kPa.

[0116] According to some embodiments of the present application, the detection unit 1232 includes a temperature detection unit, the detection range of the temperature detection unit is P2, and it satisfies: -40°C ≤ P2 ≤ 400°C, and the detection accuracy is not less than 0.1°C.

[0117] The temperature detection range of the temperature detection unit is P2. P2 can take any value between -40℃ and 400℃. P2 can be -40℃, -30℃, -20℃, -10℃, 0℃, 10℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, and 400℃. At the same time, the detection accuracy of the temperature detection unit can be no less than 0.1°C.

[0118] In some embodiments, the internal temperature of the battery cell 12 is generally between -40°C and 400°C when in normal operation. Therefore, the temperature detection range P2 of the temperature detection unit is set to between -40°C and 400°C to conform to actual operating conditions, thereby reducing the additional cost of using a temperature detection unit with an excessively wide temperature detection range. Furthermore, to ensure that the detection results have a certain reference value, the detection accuracy of the temperature detection unit can be set to no less than 0.1°C.

[0119] According to some embodiments of the present application, the detection unit 1232 includes a strain detection unit, the detection range of the strain detection unit is P3, and the following conditions are satisfied: 0<P3≤20%, and the detection accuracy is not less than 1%.

[0120] The detection range of the strain detection unit can take any value between greater than 0 and less than or equal to 20%, and P3 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%. The detection accuracy of the strain detection unit can be no less than 1%.

[0121] In some embodiments, when the battery cell 12 is operating normally, the stress of the electrode assembly 122 is generally between 0 and 20%. Therefore, the strain detection range P3 of the strain detection unit is set to between 0 and 20% to conform to actual operating conditions, thereby reducing the additional cost of using a strain detection unit with an excessively wide strain detection range. Furthermore, to ensure that the detection results have a certain reference value, the detection accuracy of the strain detection unit can be set to no less than 1%.

[0122] According to some embodiments of the present application, the detection unit 1232 includes an air pressure detection unit, the detection range of the air pressure detection unit is P4, and satisfies: 0<P4≤4MPa, and the detection accuracy is not less than 10kPa.

[0123] The detection range of the air pressure detection unit can be any value between greater than 0 and less than or equal to 4 MPa. P4 can be 0.2 MPa, 0.4 MPa, 0.6 MPa, 0.8 MPa, 1 MPa, 1.2 MPa, 1.4 MPa, 1.6 MPa, 1.8 MPa, 2 MPa, 2.2 MPa, 2.4 MPa, 2.6 MPa, 2.8 MPa, 3 MPa, 3.2 MPa, 3.4 MPa, 3.6 MPa, 3.8 MPa, or 4 MPa. The detection accuracy of the air pressure detection unit can be no less than 10 kPa.

[0124] According to some embodiments of the present application, referring to FIG. 5 , the maximum thickness of the protective film 123 is T, which satisfies: T≤200 μm.

[0125] The maximum thickness T of the protective film 123 can take any value greater than 0 and less than or equal to 200μm. T can be 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, or 200μm.

[0126] In some embodiments, the minimum distance between the electrode assembly 122 and the wall of the outer shell 121 of the battery cell 12 is generally 200 μm. The maximum thickness of the protective film 123 is designed within a reasonable range, so that it is more convenient to insert the protective film 123 into the shell after it is wrapped around the electrode assembly 122, and the risk of the electrode assembly 122 being scratched and damaged by the wall of the outer shell 121 when it is wrapped with the protective film 123 and inserted into the shell, resulting in insulation failure between the electrode assembly 122 and the outer shell 121, is reduced.

[0127] According to some embodiments of the present application, the present application provides a battery cell 12, including a shell 121, an electrode assembly 122 and a protective film 123 described in any of the above schemes, the electrode assembly 122 is arranged in the shell 121, and the protective film 123 is arranged in the shell 121 and wraps the electrode assembly 122.

[0128] According to some embodiments of the present application, referring to FIG6 and FIG7 , the electrode assembly 122 is flat, and the outer peripheral surface of the electrode assembly 122 includes two first surfaces 1221 arranged opposite to each other along the thickness direction of the electrode assembly 122, two second surfaces 1222 arranged opposite to each other along the width direction of the electrode assembly 122, and a bent surface 1223 connecting the first surface 1221 and the second surface 1222. The protective film 123 includes a first region 12311 covering the first surface 1221, the first region 12311 being provided with a detection unit 1232, and / or the protective film 123 also includes a second region 12312 covering the bent surface 1223, the second region 12312 being provided with a detection unit 1232, and / or the protective film 123 also includes a third region 12313 covering the second surface 1222, the third region 12313 being provided with a detection unit 1232.

[0129] Referring to Figure 7 , when unfolded, the membrane body 1231 generally includes a bottom region 12314. Two opposing sides of the bottom region 12314 are connected to the first region 12311. One of the first regions 12311 has two opposing sides connected to the substrate region 12315. The other first region 12311 has two opposing sides connected to the second region 12312. The second region 12312, facing away from the bottom region 12314, is connected to the third region 12313. After the protective film 123 covers the electrode assembly 122, the bottom of the electrode assembly 122 is covered by the bottom region 12314. The third region 12313 partially overlaps with the substrate region 12315 and is generally located outside of the substrate region 12315. The third region 12313 is connected to the substrate region 12315 via heat fusion, typically using a point-to-point connection method. In some embodiments, the edges of the third region 12313 can be bonded to the substrate region 12315 using polyamide tape.

[0130] The detection unit 1232 can be set in different areas of the protective film 123 to compare and analyze information of the electrode assemblies 122 in different areas, which is conducive to issuing more targeted early warning information when an abnormality occurs in a specific area of ​​the battery cell 12.

[0131] According to some embodiments of the present application, please refer to Figure 3, Figure 8 and Figure 9, the wall of the shell 121 is provided with a through hole 12111, and the battery cell 12 also includes a wire 126, one end of the wire 126 is connected to the detection unit 1232, and the other end of the wire 126 passes through the shell 121 through the through hole 12111, and the wire 126 is used to transmit the signal of the detection unit 1232.

[0132] The wall portion of the outer shell 121 may be a wall portion of the housing 1212 or an end cover 1211 .

[0133] Through hole 12111 is a hole structure provided in the wall of housing 121. It can connect the interior and exterior of housing 121, allowing wire 126 to pass from the interior of housing 121 to the exterior of housing 121. Wire 126 can be used to transmit current and pressure signals. Current is transmitted to detection unit 1232 via wire 126 to enable detection unit 1232 to operate. Signals obtained by detection unit 1232 can be transmitted to host computer 13 via wire 126, for example, to a battery management system for transmission.

[0134] Using the wire 126 to realize signal transmission of the detection unit 1232 can reduce the risk of the signal of the detection unit 1232 being subject to electromagnetic interference.

[0135] The wireless communication module can be Bluetooth or WiFi, etc.

[0136] The detection unit 1232 may also include a wireless communication module for transmitting signals from the detection unit 1232. Using the wireless communication module to transmit signals from the detection unit 1232 eliminates the need for assembly operations such as wiring and connection, thereby reducing the difficulty of assembling the battery cell 12.

[0137] According to some embodiments of the present application, referring to Figures 3, 8, and 9, the housing 121 includes a shell 1212 and an end cap 1211. The shell 1212 has an opening, and the end cap 1211 closes the opening. A through hole 12111 is provided in the end cap 1211.

[0138] The end cover 1211 may be the top of the outer shell 121 . When the battery cell 12 is in use, the end cover 1211 may be the portion of the battery cell 12 that is farthest from the ground.

[0139] After the end cover 1211 closes the opening, the end cover 1211 is generally connected to the housing 1212 by welding or other methods.

[0140] The wire 126 is led out through the through hole 12111 on the end cover 1211. On the one hand, compared with the solution in which the wire 126 is led out from the side wall of the shell 121, the risk of the wire 126 being soaked in electrolyte and causing corrosion of the wire 126 can be reduced; on the other hand, when multiple battery cells 12 are grouped to form the battery 100, the wire 126 is led out through the end cover 1211. Compared with the solution in which the wire 126 is led out from the side wall of the shell 121, the risk of the wire 126 being damaged by the squeezing force caused by the mutual squeezing of adjacent battery cells 12 can be reduced; on another hand, generally, the end cover 1211 is the component of the shell 121 farthest from the ground. For this reason, setting the through hole 12111 on the end cover 1211 can reduce the risk of the electrolyte leaking from the area between the end cover 1211 and the wire 126.

[0141] According to some embodiments of the present application, referring to Figures 3, 8, and 9, the battery cell 12 further includes a sealant 127, which is disposed in the through-hole 12111 to fill the gap between the wire 126 and the through-hole 12111. By filling the gap between the wire 126 and the through-hole 12111 with the sealant 127, the risk of electrolyte in the battery cell 12 leaking through the gap between the wire 126 and the through-hole 12111 can be effectively reduced.

[0142] Sealing member 127 is a component disposed between conductive wire 126 and through-hole 12111. Its function is to fill the gap between conductive wire 126 and through-hole 12111 to reduce the risk of electrolyte leakage. In some embodiments, sealing member 127 may be a sealant, which is applied between through-hole 12111 and conductive wire 126. After the sealant cures, a good seal is achieved between conductive wire 126 and through-hole 12111. In other embodiments, a step or groove may be provided in the wall of through-hole 12111 to accommodate sealing member 127.

[0143] By filling the gap between the wire 126 and the through hole 12111 with the sealant 127 , the risk of the electrolyte in the battery cell 12 leaking from the gap between the wire 126 and the through hole 12111 can be effectively reduced.

[0144] According to some embodiments of the present application, the present application provides a battery 100 including the battery cell 12 described in any of the above solutions.

[0145] According to some embodiments of the present application, the present application provides an electrical device, including the battery 100 described in any of the above solutions, and the battery 100 is used to provide electrical energy.

[0146] According to some embodiments of the present application, referring to Figures 3 to 9 , a protective film 123 is provided for wrapping an electrode assembly 122. The protective film 123 includes a membrane body 1231 and a detection unit 1232. The detection unit 1232 is formed on the membrane body 1231 and is used to detect information related to the electrode assembly 122. The membrane body 1231 is provided with a recess, and at least a portion of the detection unit 1232 is accommodated in the recess. The detection unit 1232 includes a circuit 12322 and an insulating layer 12323. The circuit 12322 is positioned between the insulating layer 12323 and the membrane body 1231. The circuit 12322 is formed on the membrane body 1231 by spraying, screen printing, or 3D printing, and the insulating layer 12323 is formed on the membrane body 1231 by spraying, screen printing, or 3D printing. The detection unit 1232 is a sheet-like structure. There are multiple detection units 1232, and the multiple detection units 1232 are spaced apart. The plurality of detection units 1232 include a pressure detection unit, a strain detection unit, an air pressure detection unit, and a temperature detection unit.

[0147] The production process of the protective film 123 is to process a film body 1231 with a recess, use the film body 1231 as the base 12321 of the detection unit 1232, and form the circuit 12322 in the recess by spraying, screen printing or 3D printing. Then, the insulating layer 12323 is formed on the film body 1231 by spraying, screen printing or 3D printing. The film body 1231 covers the recess to form a protective film 123.

[0148] According to some embodiments of the present application, referring to FIG. 3 to FIG. 9 , the present application provides a battery cell 12, which includes a housing 121, an electrode assembly 122, and a protective film 123. The electrode assembly 122 is disposed within the housing 121, and the protective film 123 is disposed within the housing 121 and wraps around the electrode assembly 122. The electrode assembly 122 is flat, and its outer circumference includes two first surfaces 1221 disposed opposite each other along the thickness of the electrode assembly 122, two second surfaces 1222 disposed opposite each other along the width of the electrode assembly 122, and a curved surface 1223 connecting the first surfaces 1221 and the second surfaces 1222. The protective film 123 includes a first region 12311 covering the first surface 1221, a second region 12312 covering the curved surface 1223, and a third region 12313 covering the second surface 1222. A detection unit 1232 is disposed on the first region 12311.

[0149] The outer shell 121 includes a housing 1212 and an end cap 1211. The housing 1212 has an opening, and the end cap 1211 seals the opening. A through hole 12111 is provided in the end cap 1211. The battery cell 12 also includes a wire 126. One end of the wire 126 is connected to the detection unit 1232, and the other end of the wire 126 passes through the outer shell 121 through the through hole 12111. The wire 126 is used to transmit signals to the detection unit 1232. The battery cell 12 also includes a seal 127, which is provided in the through hole 12111 to fill the gap between the wire 126 and the through hole 12111.

[0150] When the protective film 123 is applied to a battery cell with a size of 141mm×50mm×95mm (length×width×height), the size of the bottom area 12314 of the protective film 123 is 141×50mm, the area of ​​the first area 12311 is 131×95mm, the area of ​​the second area 12312 is 15×95mm, the area of ​​the third area 12313 is 42×95mm, and the substrate area 12315 is 30×95mm.

[0151] The protective film 123 includes a membrane body 1231 and a detection unit 1232. The detection unit 1232 is formed on the membrane body 1231 and is used to detect information related to the electrode assembly 122. A recess is provided on the membrane body 1231, and at least a portion of the detection unit 1232 is accommodated in the recess. The detection unit 1232 includes a circuit 12322 and an insulating layer 12323. The circuit 12322 is located between the insulating layer 12323 and the membrane body 1231. The circuit 12322 is formed on the membrane body 1231 by spraying, screen printing or 3D printing, and the insulating layer 12323 is formed on the membrane body 1231 by spraying, screen printing or 3D printing. The detection unit 1232 is a sheet-like structure. There are multiple detection units 1232, and the multiple detection units 1232 are arranged at intervals. The plurality of detection units 1232 include a pressure detection unit, a strain detection unit, an air pressure detection unit, and a temperature detection unit.

[0152] The assembly process of the battery cell 12 is roughly as follows: the protective film 123 with the detection unit 1232 is wrapped on the surface of the electrode assembly 122, the wire 126 is first led out from the through hole 12111 of the end cover 1211, and then the electrode assembly 122 wrapped by the protective film 123 is installed in the shell 1212, and finally the end cover 1211 is closed with the shell 1212 and fixed by welding and sealant is filled between the through hole 12111 and the wire 126.

[0153] After the battery cell 12 is assembled, it can be connected to the battery management system through the wire 126 to realize real-time collection of data on the large-surface expansion force, stress, temperature of the electrode assembly 122 and the internal air pressure of the battery cell 12 after the electrode assembly 122 produces gas. The battery management system processes and analyzes the collected data and issues early warnings for risks such as local overvoltage, temperature anomalies, stress anomalies, and air pressure anomalies.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A protective film for wrapping an electrode assembly, wherein: include: membrane body; The detection unit is formed on the membrane body and is used to detect information related to the electrode assembly.

2. The protective film according to claim 1, wherein: The membrane body is provided with a recessed portion, and at least a part of the detection unit is accommodated in the recessed portion.

3. The protective film according to claim 1 or 2, wherein: The detection unit is formed on the membrane body by spraying, screen printing or 3D printing.

4. The protective film according to any one of claims 1 to 3, wherein: The detection unit includes a circuit and an insulating layer, wherein the circuit is located between the insulating layer and the membrane body.

5. The protective film according to claim 4, wherein: The circuit is formed on the membrane body by spraying, screen printing or 3D printing, and the insulating layer is formed on the membrane body by spraying, screen printing or 3D printing.

6. The protective film according to any one of claims 1 to 5, wherein: The detection unit is a sheet-like structure.

7. The protective film according to any one of claims 1 to 5, wherein: There are multiple detection units, and the multiple detection units are arranged at intervals.

8. The protective film according to claim 7, wherein: The plurality of detection units include at least one of a pressure detection unit, a strain detection unit, an air pressure detection unit and a temperature detection unit.

9. The protective film according to any one of claims 1 to 8, wherein: The number of detection points per unit area of ​​the detection unit is A, satisfying: A≥4 points / cm2.

10. The protective film according to any one of claims 1 to 9, wherein: The detection unit includes a pressure detection unit, the detection range of the pressure detection unit is P1, which satisfies: 0<P1≤10MPa, and the detection accuracy is not less than 10kPa.

11. The protective film according to any one of claims 1 to 10, wherein: The detection unit includes a temperature detection unit, the detection range of the temperature detection unit is P2, and satisfies: -40°C≤P2≤400°C, and the detection accuracy is not less than 0.1°C.

12. The protective film according to any one of claims 1 to 11, wherein: The detection unit includes a strain detection unit, the detection range of the strain detection unit is P3, and satisfies: 0<P3≤20%, and the detection accuracy is not less than 1%.

13. The protective film according to any one of claims 1 to 12, wherein: The detection unit includes an air pressure detection unit, the detection range of the air pressure detection unit is P4, and satisfies: 0<P4≤4MPa, and the detection accuracy is not less than 10kPa.

14. The protective film according to any one of claims 1 to 13, wherein: The maximum thickness of the protective film is T, which satisfies: T≤200 μm.

15. A battery cell, wherein: include: shell; An electrode assembly is disposed in the housing ； The protective film as described in any one of claims 1 to 14 is arranged in the shell and wraps the electrode assembly.

16. The battery cell according to claim 15, wherein: The electrode assembly is flat, and the outer peripheral surface of the electrode assembly includes two first surfaces arranged opposite to each other along the thickness direction of the electrode assembly, two second surfaces arranged opposite to each other along the width direction of the electrode assembly, and a bending surface connecting the first surface and the second surface; The protective film includes a first area covering the first surface, and the first area is provided with the detection unit; And / or, the protective film further includes a second area covering the bending surface, and the second area is provided with the detection unit; And / or, the protective film further includes a third area covering the second surface, and the detection unit is disposed in the third area.

17. The battery cell according to any one of claims 15 to 16, wherein: The wall of the housing is provided with a through hole, the battery cell further comprises a wire, one end of the wire is connected to the detection unit, the other end of the wire passes through the housing through the through hole, and the wire is used for transmitting a signal of the detection unit; Alternatively, the detection unit includes a wireless communication module, and the wireless communication module is used for transmitting the signal of the detection unit.

18. The battery cell according to claim 17, wherein: The housing comprises a shell and an end cover, the shell has an opening, and the end cover closes the opening; Wherein, the through hole is arranged on the end cover.

19. The battery cell according to claim 17 or 18, wherein: The battery cell further includes a sealing member disposed at the through hole to fill a gap between the wire and the through hole.

20. A battery, wherein: The invention comprises a battery cell as claimed in any one of claims 15 to 19.

21. An electrical device, wherein: The electric device comprises the battery as claimed in claim 20, and the battery is used to provide electric energy.

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