CN116435609A

CN116435609A - Battery monomer, battery, power utilization device, detection method and module for safety performance

Info

Publication number: CN116435609A
Application number: CN202310707734.2A
Authority: CN
Inventors: 余斌; 吴桂森; 李伟
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-06-15
Filing date: 2023-06-15
Publication date: 2023-07-14

Abstract

The invention provides a battery monomer, a battery, an electric device, a detection method and a module of safety performance, wherein the battery monomer comprises the following components: a case and an electrode assembly disposed in the receiving chamber and connecting the first electrode terminal and the second electrode terminal; the third electrode is arranged on the wall part, the third electrode, the first electrode terminal and the second electrode terminal are mutually insulated, and the third electrode is used for being electrically connected with the first electrode terminal and/or the second electrode terminal; the electrode layer is arranged between the shell and the electrode assembly, is made of conductive materials and is mutually insulated from the electrode assembly, and a charge-discharge voltage-charge state curve corresponding to the conductive materials of the electrode layer is made of charge-discharge platform voltage. According to the method, the third electrode is electrically connected with the electrode layer, when the voltage of the electrode layer is in the stable platform voltage, the potential offset of the third electrode which is independently used is improved, and the charging condition of the electrode terminal in the battery cell is accurately detected.

Description

Battery monomer, battery, power utilization device, detection method and module for safety performance

Technical Field

The application relates to the field of batteries, in particular to a detection method and a module for single batteries, power utilization devices and safety performance.

Background

Energy conservation and emission reduction are key to sustainable development of the automobile industry, and electric vehicles become an important component of sustainable development of the automobile industry due to the energy conservation and environmental protection advantages of the electric vehicles. For electric vehicles, battery technology is an important factor in the development of the electric vehicles.

In order to detect the performance of a battery, it is necessary to detect the electrical parameters of two electrode terminals on a battery cell, for example, the voltage parameters of two electrode terminals, but how to accurately detect the charging condition of the electrode terminals of the battery cell is still a problem to be solved in the art.

Disclosure of Invention

In view of the above problems, the present application provides a battery cell, a battery, an electric device, a method and a module for detecting safety performance, which can accurately detect the electrification condition of an electrode terminal in the battery cell.

In a first aspect, the present application provides a battery cell comprising: a housing having a wall portion and a receiving chamber defined by the wall portion; an electrode assembly disposed in the receiving chamber and connected to the first electrode terminal and the second electrode terminal; a third electrode provided on the wall portion, the third electrode, the first electrode terminal, and the second electrode terminal being insulated from each other; the electrode layer is arranged between the shell and the electrode assembly, is made of conductive materials and is mutually insulated from the electrode assembly, and a charge-discharge voltage-charge state curve corresponding to the conductive materials of the electrode layer is made of charge-discharge platform voltage.

In the technical scheme of the embodiment of the application, the electrode layer of the conductive material is arranged in the battery cell, so that the electrode layer is electrically connected with the third electrode. The design ensures that the third electrode and the electrode layer have the same stable voltage, and when the voltage of the electrode layer is in a stable platform voltage, the third electrode with unstable voltage is insufficient to influence the stable voltage of the electrode layer, so that the problem of potential deviation existing in the independent use of the third electrode is solved, the electrification condition of an electrode terminal in a battery cell can be accurately detected through the third electrode and the electrode layer, and the detection accuracy of the safety performance of the battery is further improved.

In some embodiments, the housing comprises a conductive material and the housing acts as a third electrode, the electrode layer being electrically connected to the housing.

By using the case as the third electrode, it is unnecessary to provide a separate third electrode, and the structure of the battery cell can be further simplified. And the shell usually comprises a conductive material which is not easy to corrode, so that the third electrode is not easy to corrode, and the safety performance of the battery cell is improved.

In some embodiments, the wall portion includes a housing having an opening and an end cap disposed over the opening, the end cap and/or the housing acting as the third electrode.

By using the end cap and/or the housing as the third electrode, the third electrode is facilitated to be connected with the first electrode terminal and/or the second electrode terminal.

In some embodiments, the wall portion includes a housing having an opening and an end cap covering the opening, and the third electrode is disposed on a side of the end cap or the housing facing away from the receiving cavity.

By arranging the third electrode on the side of the end cap or the housing facing away from the receiving cavity, the third electrode is facilitated to be connected with the first electrode terminal and/or the second electrode terminal.

In some embodiments, the electrode layer includes an electrode coating layer disposed on a surface of the wall facing the receiving cavity, the electrode coating layer and the electrode assembly being insulated from each other and the electrode coating layer being electrically connected to the third electrode.

By disposing the electrode coating on the surface of the wall portion facing the accommodation chamber, the structure of the battery cell is simplified.

In some embodiments, the electrode layer includes an electrode film disposed between the wall portion and the electrode assembly, the electrode film and the electrode assembly being insulated from each other and the electrode film being electrically connected to the third electrode.

By arranging the electrode film, the electrode film is arranged between the third electrode and the electrode assembly, so that the battery cell is convenient to assemble.

In some embodiments, the material from which the electrode layer is made comprises one of lithium titanate, lithium iron phosphate.

Because lithium titanate and lithium iron phosphate have stable platform voltage, the voltage of the third electrode is stable by electrically connecting the lithium titanate or lithium iron phosphate with the third electrode, and the electrification condition of an electrode terminal in a battery monomer is detected more accurately.

In some embodiments, the battery cell further includes a signal line including a first signal line connecting the first electrode terminal and the third electrode and a second signal line connecting the second electrode terminal and the third electrode.

By providing signal lines in the battery cells, the voltage difference between the third electrode and the first and second electrode terminals is detected.

In a second aspect, the present application provides a battery comprising the battery cell of the above embodiment.

Since the battery cell in the battery can accurately detect the electrification condition of the electrode terminal, the battery can also accurately detect the electrification condition of the electrode terminal.

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

Because the battery cell can accurately detect the electrification condition of the electrode terminal, the electricity utilization device can also accurately detect the electrification condition of the electrode terminal.

In a fourth aspect, the present application provides a method for detecting safety performance of a battery monomer, where the method includes: providing a battery cell, wherein the battery cell comprises an electrode assembly, a third electrode and an electrode layer, the electrode layer is made of conductive materials and is electrically connected with the third electrode, and the electrode assembly comprises a first electrode terminal and a second electrode terminal; the first electrode terminal is a negative electrode terminal, and a charge-discharge voltage-charge state curve corresponding to the conductive material of the electrode layer is provided with a charge-discharge platform voltage; acquiring a voltage difference between the first electrode terminal and the third electrode; it is determined whether the battery cell is in a safe state based on the voltage difference.

In the technical scheme of the embodiment of the application, through carrying out the electricity with third electrode and electrode layer and connecting to improve the problem of the electric potential drift of third electrode, regard third electrode and electrode layer as the reference electrode jointly, can acquire the accurate voltage difference between third electrode and the first electrode terminal, obtain the accurate voltage difference between negative electrode terminal and the third electrode promptly, can confirm whether the battery monomer is in safe state according to this voltage difference, confirm the performance of battery monomer.

In some embodiments, before the step of obtaining the voltage difference between the first electrode terminal and the third electrode, the voltage difference between the charging and discharging platform voltages in the charging and discharging voltage-state-of-charge curves respectively corresponding to the multiple cyclic charging and discharging processes is less than a preset value, the method further includes: and adjusting the voltage of the electrode layer to the voltage of the charge-discharge platform.

By activating the electrode layer, the active material in the electrode layer is converted into positive and negative plates having electrochemical properties, so as to detect an accurate voltage difference between the third electrode and the first electrode terminal.

In some embodiments, the step of adjusting the voltage of the electrode layer to the charge-discharge platform voltage specifically includes: when the material of the electrode layer is the positive electrode material, the first electrode terminal is used as a negative electrode, and the third electrode is used as a positive electrode to perform multiple charge and discharge operations; or, in the case that the material of the electrode layer is a negative electrode material, the second electrode terminal is taken as a positive electrode, and the third electrode is taken as a negative electrode to perform multiple charge and discharge operations; and adjusting the voltage of the electrode layer to the voltage of the charge-discharge platform through charge-discharge operation.

According to the material of which the electrode layer is made, it is determined that the third electrode is connected to the first electrode terminal or the second electrode terminal to convert the active material in the electrode layer into positive and negative electrode plates having electrochemical characteristics, and the voltages of the third electrode and the electrode layer are adjusted to a stable plateau voltage through charge-discharge operations.

In some embodiments, the positive electrode material comprises lithium titanate and the negative electrode material comprises lithium iron phosphate.

In some embodiments, the battery cell further includes a housing, the electrode assembly disposed within the housing, the housing acting as the third electrode; the step of obtaining a voltage difference between the first electrode terminal and the third electrode specifically includes: acquiring a first voltage difference value between a first electrode terminal and a shell which are not in a charge-discharge state within a preset time period; the step of determining whether the battery cell is in a safe state based on the voltage difference value specifically includes: and determining that the shell is corroded when the first voltage difference value is reduced in a preset time period.

The detection method of the embodiment of the application not only can indicate that the battery monomer breaks down, but also can determine that the type of the fault is that the shell is corroded, and can reduce the thermal runaway risk of the battery monomer.

In some embodiments, the step of determining whether the battery cell is in a safe state based on the voltage difference value specifically includes: and in a preset time period, when the first voltage difference value is smaller than or equal to a first voltage threshold value, determining that the corrosion condition of the shell is serious, and sending out an alarm signal.

By comparing the first voltage difference value with the first voltage threshold value, whether the corrosion condition of the shell is serious or not can be determined, and when the corrosion condition of the shell is serious, an alarm signal is sent out, so that a user can know the corrosion condition of the shell in time to improve the safety performance of the battery cell.

In some embodiments, the step of obtaining a voltage difference between the first electrode terminal and the third electrode specifically includes: acquiring a second voltage difference between the first electrode terminal and the third electrode in a charged state; the step of determining whether the battery cell is in a safe state based on the voltage difference value specifically includes: and determining that lithium precipitation occurs at the first electrode terminal when the second voltage difference is less than or equal to the second voltage threshold.

It can be determined whether lithium precipitation occurs at the negative terminal by comparing the second voltage threshold value with the second voltage difference in the charged state. The detection method of the embodiment of the application not only can indicate that the battery monomer breaks down, but also can determine that the type of the fault is that the negative electrode terminal is subjected to lithium precipitation, and can reduce the thermal runaway risk of the battery monomer.

In a fifth aspect, the present application provides a detection module for safety performance of a battery cell, where the battery cell includes an electrode assembly, a third electrode, and an electrode layer, the electrode layer is made of a conductive material and is electrically connected to the third electrode, a charge-discharge voltage-state-of-charge curve corresponding to the conductive material of the electrode layer has a charge-discharge plateau voltage, and the electrode assembly includes a first electrode terminal and a second electrode terminal; the first electrode terminal is a negative electrode terminal; the detection module comprises: an acquisition unit configured to acquire a voltage difference between the first electrode terminal and the third electrode; and the processing unit is used for determining whether the battery cell is in a safe state or not based on the voltage difference value.

In the technical scheme of this embodiment, through carrying out the electricity with third electrode and electrode layer and being connected to improve the problem of the electric potential drift of third electrode, regard third electrode and electrode layer as the reference electrode jointly, obtain the accurate voltage difference between unit can obtain third electrode and the first electrode terminal, obtain the accurate voltage difference between negative electrode terminal and the third electrode promptly, processing unit can confirm the security performance of battery monomer according to this voltage difference, and then improve the detection accuracy.

In some embodiments, the voltage difference between the charging and discharging platform voltages in the charging and discharging voltage-state-of-charge curves respectively corresponding to the multiple cycle charging and discharging processes is smaller than a preset value, and the detection module further includes: and the preprocessing unit is used for adjusting the voltage of the electrode layer to the voltage of the charge-discharge platform.

The electrode layer is activated by the arranged pretreatment unit, so that active substances in the electrode layer are converted into positive and negative electrode plates with electrochemical characteristics, and an accurate voltage difference between the third electrode and the first electrode terminal is conveniently detected.

In some embodiments, the preprocessing unit is configured to perform multiple charge and discharge operations with the first electrode terminal as a negative electrode and the third electrode as a positive electrode when the material of the electrode layer is a positive electrode material; or, in the case that the material of the electrode layer is a negative electrode material, the second electrode terminal is used as a positive electrode, and the third electrode is used as a negative electrode to perform charge and discharge operations for a plurality of times; and adjusting the voltage of the electrode layer to the voltage of the charge-discharge platform through charge-discharge operation.

And the third electrode is connected with the first electrode terminal or the second electrode terminal according to the material of the electrode layer by the arranged pretreatment unit, so that active substances in the electrode layer are converted into positive and negative electrode plates with electrochemical characteristics, and the voltage of the third electrode and the electrode layer is regulated to a stable platform voltage by charge-discharge operation.

In some embodiments, the battery cell further includes a housing, the electrode assembly disposed within the housing, the housing acting as the third electrode; the acquisition unit is used for acquiring a first voltage difference value between the first electrode terminal and the shell, which are not in a charging and discharging state in a preset time period; the processing unit is used for determining that the shell is corroded when the first voltage difference value is reduced in a preset time period.

The detection module of the embodiment not only can indicate that the battery monomer has faults, but also can determine that the fault type is that the shell has corrosion, and can reduce the thermal runaway risk of the battery monomer.

In some embodiments, the processing unit is configured to determine that the corrosion condition of the casing is serious and send an alarm signal when the first voltage difference is less than or equal to the first voltage threshold value in a preset time period.

The processing unit in this embodiment can determine whether the corrosion condition of the casing is serious by comparing the first voltage difference value with the first voltage threshold value, and when the corrosion condition of the casing is serious, an alarm signal is sent out, so that the user can know the corrosion condition of the casing in time to improve the safety performance of the battery cell.

In some embodiments, the acquiring unit is configured to acquire a second voltage difference between the first electrode terminal and the third electrode in the charged state; the processing unit is used for determining that lithium precipitation occurs at the first electrode terminal when the second voltage difference value is smaller than or equal to a second voltage threshold value.

The detection module of the embodiment of the application not only can indicate that the battery monomer breaks down, but also can determine that the fault type is that the negative electrode terminal is subjected to lithium precipitation, and can reduce the thermal runaway risk of the battery monomer.

The foregoing description is only an overview of the technical solutions of the present application, and may be implemented according to the content of the specification in order to make the technical means of the present application more clearly understood, and in order to make the above-mentioned and other objects, features and advantages of the present application more clearly understood, the following detailed description of the present application will be given.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:

FIG. 1 is a schematic illustration of a vehicle according to some embodiments of the present application;

fig. 2 is an exploded view of a battery according to some embodiments of the present application;

fig. 3 is a schematic structural view of a battery module according to some embodiments of the present application;

fig. 4 is a schematic exploded view of a battery cell according to some embodiments of the present application;

fig. 5 is a schematic structural view of a battery cell according to some embodiments of the present application;

fig. 6 is a schematic structural view of a battery cell according to another embodiment of the present application;

fig. 7 is a schematic flow chart of a method for detecting safety performance of a battery monomer according to an embodiment of the present application;

fig. 8 is a schematic structural diagram of a detection module of a battery cell according to an embodiment of the present disclosure;

fig. 9 is a schematic structural diagram of a detection module of a battery cell according to another embodiment of the present application.

Reference numerals in the specific embodiments are as follows:

A vehicle 1000;

battery 100, controller 200, motor 300;

a case 10, a first portion 11, a second portion 12;

a battery module 20; a battery cell 21; a housing 211; a housing 211a; an end cap 211b; wall portion 211aa; a receiving chamber 212; a first electrode terminal 213; a second electrode terminal 214; an electrode assembly 215; a third electrode 216; an electrode layer 217; a signal line 218; a first signal line 218a; a second signal line 218b;

a detection module 30; an acquisition unit 31; a processing unit 32; a preprocessing unit 33.

Detailed Description

Embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical solutions of the present application, and thus are only examples, and are not intended to limit the scope of protection of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having" and any variations thereof in the description and claims of the present application and in the description of the figures above are intended to cover non-exclusive inclusions.

In the description of the embodiments of the present application, the technical terms "first," "second," etc. are used merely to distinguish between different objects and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, which means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

In the description of the embodiments of the present application, the term "plurality" refers to two or more (including two), and similarly, "plural sets" refers to two or more (including two), and "plural sheets" refers to two or more (including two).

In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of describing the embodiments of the present application and for simplifying the description, rather than indicating or implying that the apparatus or element referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the embodiments of the present application.

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; or may be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to the specific circumstances.

Currently, the application of power batteries is more widespread from the development of market situation. The power battery is not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles, and the like, and a plurality of fields such as military equipment, aerospace, and the like. With the continuous expansion of the application field of the power battery, the market demand of the power battery is also continuously expanding.

Reference to a battery in embodiments of the present application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in the present application may include a battery module or a battery pack, or the like. The battery generally includes a case for enclosing one or more battery cells. The case can improve the effect of liquid or other foreign matter on the charge or discharge of the battery cells.

The battery cell comprises an electrode assembly and electrolyte, wherein the electrode assembly comprises a positive electrode plate, a negative electrode plate and a separator. The battery cell mainly relies on metal ions to move between the positive pole piece and the negative pole piece to work. The positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is coated on the surface of the positive electrode current collector; the positive current collector comprises a positive current collecting part and a positive lug connected to the positive current collecting part, wherein the positive current collecting part is coated with a positive active material layer, and the positive lug is not coated with the positive active material layer. Taking a lithium ion battery as an example, the material of the positive electrode current collector may be aluminum, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate or the like. The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector; the negative electrode current collector comprises a negative electrode current collecting part and a negative electrode tab connected to the negative electrode current collecting part, wherein the negative electrode current collecting part is coated with a negative electrode active material layer, and the negative electrode tab is not coated with the negative electrode active material layer. The material of the anode current collector may be copper, the anode active material layer includes an anode active material, and the anode active material may be carbon or silicon, or the like. The material of the separator may be PP (polypropylene) or PE (polyethylene), etc.

In order to improve the safety performance of the battery cell, it is necessary to monitor the voltage variation of the electrode terminals of the battery cell.

In order to detect the voltage conditions of two electrode terminals in a battery cell, a reference electrode is provided in the related art, and the voltage change of the electrode terminal is determined by comparing the voltage difference between the reference electrode and the two electrode terminals. In the related art, a reference electrode is usually disposed between two pole pieces, for example, the reference electrode is a copper wire plated with metal lithium, and the reference electrode is implanted into the laminated electrode assembly. The insertion of the reference electrode into the electrode assembly itself is complicated, and in consideration of the problem of easy oxidation of lithium metal, it is also necessary to insert the reference electrode into the electrode assembly in a closed environment, which results in complicated and difficult manufacturing of the battery cell.

In order to alleviate the problem that the structure of the battery cell is complex, the reference electrode may be disposed on the housing of the battery cell, for example, the housing of the battery cell is used as the reference electrode, and the material of the housing may be a conductive material, for example, the material of which the housing is made may be aluminum.

The shell in the battery cell is directly used as a reference electrode, and the maximum voltage fluctuation of the shell is up to 120mV, namely the potential stability of the reference electrode is poor. That is, it is difficult to accurately detect the electrification of the electrode terminal in the battery cell by directly using the housing as the reference electrode.

Based on the above consideration, in order to solve the problem that the battery cell structure is complex, in order to accurately acquire the voltages of two electrode terminals in the battery cell, a battery cell is designed. In such a battery cell, the third electrode and the electrode layer are disposed on the housing of the battery cell, so that the structure of the battery cell can be simplified, and the voltage of the two electrode terminals in the battery cell can be accurately obtained by electrically connecting the electrode layer with the third electrode and according to the voltage difference between the third electrode and the two electrode terminals.

The battery cell disclosed by the embodiment of the application can be used for an electric device using a battery as a power supply or various energy storage systems using the battery as an energy storage element. The power device may be, but is not limited to, a cell phone, tablet, notebook computer, electric toy, electric tool, battery car, electric car, ship, spacecraft, etc. The vehicle can be a fuel oil vehicle, a fuel gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended vehicle; spacecraft including airplanes, rockets, space planes, spacecraft, and the like; the electric toy includes fixed or mobile electric toys, such as a game machine, an electric car toy, an electric ship toy, and an electric airplane toy; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railroad power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete shakers, and electric planers, among others.

It should be understood that the technical solutions described in the embodiments of the present application are not limited to the above-described batteries and electric devices, but may be applied to all batteries including a case and electric devices using the batteries, but for simplicity of description, the following embodiments are described by taking an electric vehicle as an example.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a vehicle according to some embodiments of the present application. The vehicle can be a fuel oil vehicle, a fuel gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended vehicle and the like. The interior of the vehicle is provided with a battery, which may be provided at the bottom or at the head or at the tail of the vehicle. The battery may be used for power supply of the vehicle, for example, the battery may be used as an operating power source of the vehicle. The vehicle may also include a controller and a motor, the controller being configured to control the battery to power the motor, for example, for operating power requirements during start-up, navigation, and travel of the vehicle.

In some embodiments of the present application, the battery may be used not only as an operating power source for the vehicle, but also as a driving power source for the vehicle, instead of or in part instead of fuel oil or natural gas, to provide driving power for the vehicle.

In some embodiments of the present application, battery 100 may not only serve as an operating power source for vehicle 1000, but may also serve as a driving power source for vehicle 1000, instead of or in part instead of fuel oil or natural gas, to provide driving power for vehicle 1000.

Referring to fig. 2, fig. 2 is an exploded view of a battery according to some embodiments of the present application. The battery 100 includes a case 10 and a battery cell 21, and the battery cell 21 is accommodated in the case 10. The case 10 is used to provide a receiving space for the battery cells 21, and the case 10 may have various structures. In some embodiments, the case 10 may include a first portion 11 and a second portion 12, the first portion 11 and the second portion 12 being overlapped with each other, the first portion 11 and the second portion 12 together defining an accommodating space for accommodating the battery cell 21. The second portion 12 may be a hollow structure with one end opened, the first portion 11 may be a plate-shaped structure, and the first portion 11 covers the opening side of the second portion 12, so that the first portion 11 and the second portion 12 together define a containing space; the first portion 11 and the second portion 12 may be hollow structures each having an opening at one side, and the opening side of the first portion 11 is engaged with the opening side of the second portion 12. Of course, the case 10 formed by the first portion 11 and the second portion 12 may be of various shapes, such as a cylinder, a rectangular parallelepiped, or the like.

Referring to fig. 3, fig. 3 is a schematic structural diagram of a battery module according to some embodiments of the present application.

In the battery 100, the plurality of battery cells 21 may be plural, and the plurality of battery cells 21 may be connected in series, parallel, or a series-parallel connection, where a series-parallel connection means that the plurality of battery cells 21 are connected in both series and parallel. The plurality of battery cells 21 can be directly connected in series or in parallel or in series-parallel, and then the whole formed by the plurality of battery cells 21 is accommodated in the box 10; of course, the battery 100 may also be in the form of a plurality of battery cells 21 connected in series or parallel or series-parallel to form the battery module 20, and a plurality of battery modules 20 connected in series or parallel or series-parallel to form a whole and accommodated in the case 10. Specifically, the plurality of battery cells 21 may be electrically connected to each other through a bus bar member, so as to realize parallel connection, serial connection, or series-parallel connection of the plurality of battery cells 21 in the battery module 20.

Wherein each battery cell 21 may be a secondary battery or a primary battery; but not limited to, lithium sulfur batteries, sodium ion batteries, or magnesium ion batteries.

Primary batteries (Primary batteries) are also known as "disposable" batteries and galvanic cells, because they cannot be recharged for use after their charge has been exhausted and can only be discarded. Secondary batteries (Secondary Battery) are also referred to as rechargeable batteries or secondary batteries, accumulators. The secondary battery has the advantages of being capable of being recycled after being charged, and the output current load force of the secondary battery is higher than that of most of the primary batteries. The types of secondary batteries that are currently common are: lead acid batteries, nickel hydrogen batteries, and lithium ion batteries. The lithium ion battery has the advantages of light weight, large capacity (the capacity is 1.5-2 times of that of the nickel-hydrogen battery with the same weight), no memory effect and the like, and has very low self-discharge rate, so that the lithium ion battery is widely applied even though the price is relatively high. Lithium ion batteries are also widely used in pure electric vehicles and hybrid vehicles at present, and the capacity of the lithium ion batteries used for the purposes is relatively slightly low, but the lithium ion batteries have larger output and charging currents, longer service lives and higher cost.

In the present application, the battery cell 21 may include a lithium ion battery, a sodium ion battery, a magnesium ion battery, or the like, which is not limited in the embodiment of the present application. The battery cell 21 may be in a cylindrical shape, a flat shape, a rectangular parallelepiped shape, or other shapes, etc., which is not limited in the embodiment of the present application. The battery cells 21 are generally divided into three types in a package manner: the cylindrical battery cells 21, the square battery cells 21, and the pouch battery cells 21 are not limited thereto. However, for simplicity of description, the following embodiments will be described by taking the square battery cell 21 as an example.

Referring to fig. 4 and 5, fig. 4 is a schematic diagram illustrating an exploded structure of a battery cell according to some embodiments of the present application; fig. 5 is a schematic structural diagram of a battery cell according to some embodiments of the present application.

The battery cell 21 refers to the smallest unit constituting the battery. As shown in fig. 3, the battery cell 21 includes an end cap 211b, a case 211a, an electrode assembly 215, and other functional components.

The end cap 211b refers to a member that is capped at the opening of the case 211a to isolate the internal environment of the battery cell 21 from the external environment. Without limitation, the shape of the end cap 211b may be adapted to the shape of the housing 211a to fit the housing 211a. Alternatively, the end cap 211b may be made of a material having a certain hardness and strength (such as an aluminum alloy), so that the end cap 211b is not easily deformed when being extruded and collided, so that the battery cell 21 can have a higher structural strength, and the safety performance can be improved. The end cap 211b may be provided with a functional member such as the electrode terminal 21 a. The electrode terminal 21a may be used to be electrically connected with the electrode assembly 215 for outputting or inputting electric power of the battery cell 21. In some embodiments, a pressure relief mechanism may also be provided on the end cap 211b for relieving the internal pressure when the internal pressure or temperature of the battery cell 21 reaches a threshold. The material of the end cap 211b may be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, insulation may also be provided on the inside of the end cap 211b, which may be used to isolate electrical connection components within the housing 211a from the end cap 211b to reduce the risk of shorting. By way of example, the insulation may be plastic, rubber, or the like.

The case 211a is an assembly for mating with the end cap 211b to form an internal environment of the battery cell 21, wherein the formed internal environment may be used to house the electrode assembly 215, the electrolyte, and other components. The case 211a and the end cap 211b may be separate members, and an opening may be provided in the case 211a, and the end cap 211b may be closed at the opening to form the internal environment of the battery cell 21. However, the end cap 211b and the housing 211a may be integrated, specifically, the end cap 211b and the housing 211a may form a common connection surface before other components are put into the housing, and when the interior of the housing 211a needs to be sealed, the end cap 211b is covered with the housing 211a. The housing 211a may be of various shapes and various sizes, such as rectangular parallelepiped, cylindrical, hexagonal prism, etc. Specifically, the shape of the case 211a may be determined according to the specific shape and size of the electrode assembly 215. The material of the housing 211a may be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

The electrode assembly 215 is a component in which electrochemical reactions occur in the battery cell 21. One or more electrode assemblies 215 may be contained within the housing 211a. The electrode assembly 215 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is generally provided between the positive electrode sheet and the negative electrode sheet. The portions of the positive and negative electrode sheets having active material constitute the main body of the electrode assembly 215, and the portions of the positive and negative electrode sheets having no active material constitute the tabs 23a, respectively. The positive electrode tab and the negative electrode tab may be located at one end of the main body portion together or located at two ends of the main body portion respectively. During charge and discharge of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tab 23a is connected to the electrode terminal to form a current loop.

Some embodiments of the present application provide a battery cell 21 including a housing 211, an electrode assembly 215, a third electrode 216, and an electrode layer 217. Wherein the housing 211 has a wall portion 211aa and a receiving cavity 212 surrounded by the wall portion 211 aa; the electrode assembly 215 is disposed in the receiving chamber 212 and connects the first electrode terminal 213 and the second electrode terminal 214; the third electrode 216 is disposed on the wall 211aa, and the third electrode 216, the first electrode terminal 213, and the second electrode terminal 214 are insulated from each other; the electrode layer 217 is disposed between the housing 211 and the electrode assembly 215, the electrode layer 217 electrically connected to the third electrode 216 is made of a conductive material and is insulated from the electrode assembly 215, and a charge-discharge voltage-charge state curve corresponding to the conductive material of the electrode layer 217 has a charge-discharge plateau voltage.

The electrode assembly 215 includes a positive electrode tab provided with a positive electrode tab and a negative electrode tab provided with a negative electrode tab, and the first electrode terminal 213 is connected to one of the positive electrode tab and the negative electrode tab and the second electrode terminal 214 is connected to the other of the positive electrode tab and the negative electrode tab. For example, the first electrode terminal 213 is connected to the negative electrode tab as a negative electrode terminal, and the second electrode terminal 214 is connected to the positive electrode tab as a positive electrode terminal.

The third electrode 216 is a reference electrode, the third electrode 216 and the first electrode terminal 213 are connected, and a voltage difference signal between the first electrode terminal 213 and the third electrode 216 is detected by a voltage detection device. By connecting the third electrode 216 and the second electrode terminal 214, a voltage difference signal between the second electrode terminal 214 and the third electrode 216 is detected by a voltage detection device.

The electrode layer 217 refers to a component in a battery, which is used as an electrode material for inputting or outputting electric current in a conductive medium (solid, gas, vacuum, or electrolyte solution). The electrode layer 217 is electrically connected to the third electrode 216, so that the third electrode 216 has the same stable voltage as the electrode layer 217. The charge-discharge voltage-charge state curve corresponding to the conductive material of the electrode layer 217 has a charge-discharge plateau voltage, and the voltage difference between the charge-discharge plateau voltages in the charge-discharge voltage-charge state curves corresponding to the charge-discharge processes respectively in multiple cycles is smaller than a preset value.

The Charge-discharge voltage-State-of-Charge curve may be an SOC curve, which is one of the best methods for determining the State of Charge of the secondary battery based on time, current and voltage in the battery management system (Battery Management System, BMS). In secondary batteries, SOC curves are typically used to infer battery charge and discharge conditions.

Specifically, there is at least one charge-discharge plateau voltage in the charge-discharge voltage-state-of-charge curve due to the conductive material from which the electrode layer 217 is made. When the electrode layer 217 adjusts the voltage to the charge-discharge plateau voltage by charge-discharge, the voltage of the electrode layer 217 is in a relatively stable state. That is, the electrode layer 217 at the discharge plateau voltage does not affect the voltage of the electrode layer 217 with the decrease of the electric quantity of the electrode layer 217 in the process of detecting the electrode terminal of the battery cell 21. Since the electrode layer 217 is electrically connected to the third electrode 216, the electrode layer 217 and the third electrode 216 have the same voltage. When the voltage of the electrode layer 217 is at the charge-discharge plateau voltage, the third electrode 216 is also at the charge-discharge plateau voltage, so that the problem of potential deviation of the third electrode 216 is improved, and the charging condition of the electrode terminal in the battery cell 21 can be accurately detected through the third electrode 216 and the electrode layer 217.

Further, since the content of the active material in the electrode layer 217 is far higher than the content of the active material in the third electrode 216, the unstable voltage of the third electrode 216 is insufficient to affect the stable voltage of the electrode layer 217, when the third electrode 216 is electrically connected to the electrode layer 217, the voltage of the third electrode 216 is the same as the voltage of the electrode layer 217 and can be at the charge-discharge plateau voltage, so that the potential shift of the third electrode 216 is improved, and the charging condition of the electrode terminal in the battery cell 21 can be accurately detected by the voltage-stabilized third electrode 216 and the electrode layer 217.

Optionally, according to some embodiments of the present application, the housing 211 comprises a conductive material and the housing 211 serves as the third electrode 216, the electrode layer 217 being electrically connected to the housing 211.

As above, the case 211 includes, for example, a material such as an aluminum alloy, so that the case 211 can be electrically conductive, and when the case 211 and the first electrode terminal 213 are connected, a voltage difference between the case 211 and the first electrode terminal 213 can be detected by the voltage detecting means. When the case 211 and the second electrode terminal 214 are connected, a voltage difference between the case 211 and the second electrode terminal 214 can be detected by the voltage detecting means.

In these embodiments, by using the case 211 as the third electrode 216, it is unnecessary to provide the third electrode 216 additionally, and the structure of the battery cell 21 can be further simplified. And the housing 211 generally includes a conductive material that is not easily corroded, so that the third electrode 216 is not easily corroded, and the safety performance of the battery cell 21 obtained by detection is more accurate.

Optionally, according to some embodiments of the present application, the wall portion 211aa includes a housing 211a having an opening and an end cap 211b covering the opening, the end cap 211b and/or the housing 211a acting as the third electrode 216.

In one embodiment, the end cap 211b comprises a conductive material, for example, the end cap 211b comprises a conductive material such as an aluminum alloy, aluminum metal, or the like. With the end cap 211b as the third electrode 216, when the end cap 211b is connected to the first electrode terminal 213, a voltage difference between the end cap 211b and the first electrode terminal 213 can be detected by the voltage detecting means. When the cap 211b and the second electrode terminal 214 are connected, a voltage difference between the cap 211b and the second electrode terminal 214 can be detected by the voltage detecting means.

In one embodiment, the housing 211a includes a conductive material, e.g., the housing 211a includes a conductive material such as an aluminum alloy, an aluminum metal, or the like. When the case 211a is connected to the first electrode terminal 213 with the case 211a as the third electrode 216, a voltage difference between the case 211a and the first electrode terminal 213 can be detected by the voltage detecting means. When the case 211a and the second electrode terminal 214 are connected, a voltage difference between the case 211a and the second electrode terminal 214 can be detected by the voltage detecting means.

In these embodiments, by using the end cap 211b and/or the case 211a as the third electrode 216, the third electrode 216 is facilitated to be connected with the first electrode terminal 213 and/or the second electrode terminal 214.

Optionally, according to some embodiments of the present application, the wall portion 211aa includes a housing 211a having an opening and an end cap 211b covering the opening, and the third electrode 216 is disposed on the end cap 211b or a side of the housing 211a facing away from the accommodating chamber 212. For example, the third electrode 216 is welded to the end cap 211b or the side of the case 211a facing away from the accommodating chamber 212, facilitating the connection of the third electrode 216 with the first electrode terminal 213 and the second electrode terminal 214. Specifically, the first electrode terminal 213 and the second electrode terminal 214 are both disposed on the end cap 211b, and the third electrode 216 is also welded to the end cap 211b on the side facing away from the accommodating chamber 212 for convenience of connection.

In these embodiments, the third electrode 216 is conveniently connected to the first electrode terminal 213 and/or the second electrode terminal 214 by providing the third electrode 216 on a side of the end cap 211b or the housing 211a facing away from the accommodating chamber 212.

Optionally, according to some embodiments of the present application, the electrode layer 217 comprises an electrode coating layer disposed on a surface of the wall portion 211aa facing the receiving cavity 212, the electrode coating layer and the electrode assembly 215 being insulated from each other and the electrode coating layer being electrically connected to the third electrode 216.

The electrode coating is a solid continuous film of conductive material applied to the substrate surface at one time. To protect the electrode coating, the electrode coating is disposed on the surface of the case 211a and/or the end cap 211b facing the electrode assembly 215. The thickness of the specific electrode coating can be set according to actual conditions.

In these embodiments, by providing the electrode coating layer on the surface of the wall portion 211aa facing the accommodating chamber 212, both the electrode layer 217 is protected and the structure of the battery cell 21 is simplified.

Optionally, according to some embodiments of the present application, the electrode layer 217 includes an electrode film, the electrode film is disposed between the wall portion 211aa and the electrode assembly 215, the electrode film and the electrode assembly 215 are insulated from each other, and the electrode film is electrically connected to the third electrode 216.

The electrode film is a thin, soft sheet formed from a conductive material by spraying, casting, or the like. For ease of installation, the electrode film is disposed between the wall portion 211aa and the electrode assembly 215. The thickness of the specific electrode film can be set according to the requirements.

In these embodiments, the assembly of the battery cell 21 is facilitated by providing an electrode film between the third electrode 216 and the electrode assembly 215.

In some embodiments, the material from which electrode layer 217 is made comprises one of lithium titanate, lithium iron phosphate.

In these embodiments, since the lithium titanate and the lithium iron phosphate have stable plateau voltages, the voltage of the third electrode 216 is stabilized by electrically connecting the lithium titanate or the lithium iron phosphate with the third electrode 216, and the charging condition of the electrode terminal in the battery cell 21 is detected more accurately. The platform voltage refers to that the voltage of the conductive material is kept unchanged along with the increase or decrease of the stored electric quantity of the conductive material at a certain stage in the charge-discharge process. The stable platform voltage means that the voltage difference between the charging and discharging platform voltages is smaller than a preset value in the process of charging and discharging for many times.

Referring to fig. 6, fig. 6 is a schematic structural diagram of a battery cell according to another embodiment of the present application.

In some embodiments, the battery cell 21 includes a signal line 218, the signal line 218 including a first signal line 218a connecting the first electrode terminal 213 and the third electrode 216 and a second signal line 218b connecting the second electrode terminal 214 and the third electrode 216.

The first signal line 218a may be a complete one line, or the first signal line 218a may include two sub-signal lines, for example, a voltage detecting device is disposed between the two sub-signal lines, one end of the voltage detecting device is connected to the first electrode terminal 213 through one sub-signal line, and the other end of the voltage detecting device is connected to the third electrode 216 through the other sub-signal line, so that the voltage detecting device can obtain a voltage difference between the first electrode terminal 213 and the third electrode 216 through the two sub-signal lines of the first signal line 218 a. The second signal line 218b is disposed in a similar manner to the first signal line 218a, and will not be described again.

In these embodiments, the voltage difference between the third electrode 216 and the first and

second electrode terminals

213 and 214 is detected by providing the signal line 218 in the battery cell 21.

According to an embodiment of the present application, there is provided a battery cell 21, the battery cell 21 including a housing 211a, an end cap 211b, an electrode assembly 215, a third electrode 216, an electrode coating, a first signal line 218a, a second signal line 218b. The case 211a has a housing cavity 212, the electrode assembly 215 is disposed in the housing cavity 212, the end cap 211b covers the opening of the housing cavity 212, the third electrode 216 is disposed on a side surface of the end cap 211b away from the housing cavity 212, the end cap 211b is provided with a first electrode terminal 213 and a second electrode terminal 214, and the first electrode terminal 213, the second electrode terminal 214 and the third electrode 216 are disposed on the same surface of the same end cap 211 b. The electrode coating is disposed on a side surface of the case 211a and the end cap 211b facing the electrode assembly 215, and the electrode coating is electrically connected to the third electrode 216. The material of the third electrode 216 is aluminum. Wherein the electrode coating is made of lithium titanate or lithium iron phosphate. The electrode coating made of lithium titanate or lithium iron phosphate can be charged and discharged reversibly, and in SOC curves corresponding to the lithium titanate and the lithium iron phosphate respectively, the lithium titanate and the lithium iron phosphate have relatively stable charge and discharge platform voltages. The first electrode terminal 213 and the third electrode 216 are connected through a first signal line 218a to detect a voltage difference between the first electrode terminal 213 and the third electrode 216 by a voltage detection device. The second electrode terminal 214 and the third electrode 216 are connected through the second signal line 218b to detect a voltage difference between the second electrode terminal 214 and the third electrode 216 through the voltage detection device.

In the manufacturing process of the battery cell 21, an electrode coating is formed on the surfaces of the housing 211a and the end cap 211b facing the receiving chamber 212 by spraying and drying or casting and drying using lithium titanate or lithium iron phosphate as a raw material to modify the housing 211a and the end cap 211 b. The material of the housing 211a and the end cap 211b may be metal aluminum. The electrode assembly 215 is assembled to the receiving chamber 212, the electrode assembly 215 is insulated from the electrode coating layer, and the electrode coating layer is electrically connected to the case 211. The end cap 211b is capped with the opening of the receiving chamber 212 so that the electrode assembly 215 is in a closed space. A third electrode 216 is welded on the surface of the end cap 211b where the first electrode terminal 213 and the second electrode terminal 214 are provided, and the third electrode 216 is a conductive material. The third electrode 216 is electrically connected to the cap 211b, the case 211a, and the electrode layer 217.

The spraying means a coating method of dispersing uniform and fine mist droplets by means of pressure or centrifugal force by means of a spray gun or a disk atomizer, and applying the mist droplets to surfaces of the housing 211a and the end cap 211b facing the accommodation chamber 212. The casting method is a forming method for preparing a film with a required thickness on a casting machine by adding components such as a solvent, a dispersing agent, a binder, a plasticizer and the like into lithium titanate or lithium iron phosphate to obtain uniformly dispersed stable slurry. Drying refers to the process of vaporizing moisture (or solvents) in materials by thermal energy and taking away the generated vapors by inert gases in the chemical industry.

According to some embodiments of the present application, there is also provided a battery 100 including the battery cell 21 of any one of the above aspects.

According to some embodiments of the present application, there is also provided an electrical device comprising the battery 100 of any of the above aspects, and the battery 100 is used to provide electrical energy to the electrical device. The electric device may be the vehicle 1000.

The powered device may be any of the devices or systems described above that employ battery 100.

Referring to fig. 7, fig. 7 is a flow chart of a method for detecting safety performance of a battery cell according to an embodiment of the present application. The battery cell 21 may be the battery cell 21 shown in fig. 4, 5, and 6.

Step S1: providing a battery cell, wherein the battery cell comprises an electrode assembly, a third electrode and an electrode layer, the electrode layer is made of conductive materials and is electrically connected with the third electrode, and the electrode assembly comprises a first electrode terminal and a second electrode terminal; the first electrode terminal is a negative electrode terminal.

The battery cell 21 in this embodiment may be the battery cell 21 in any of the above embodiments. The content of the active material in the electrode layer 217 may be determined according to the thickness and the area of the electrode layer 217, thereby determining the corresponding storage capacity of the electrode layer 217.

Step S2: a voltage difference between the first electrode terminal and the third electrode is obtained.

As above, the first electrode terminal 213 and the third electrode 216 may be connected, and the voltage difference between the first electrode terminal 213 and the third electrode 216 may be acquired by the voltage detection device.

Step S3: it is determined whether the battery cell is in a safe state based on the voltage difference.

In the technical solution of this embodiment, by electrically connecting the third electrode 216 and the electrode layer 217, the third electrode 216 and the electrode layer 217 are used together as a reference electrode, so as to improve the problem of potential drift of the original third electrode 216, and further obtain an accurate voltage difference between the electrode layer 217 and the first electrode terminal 213, that is, obtain an accurate voltage difference between the negative electrode terminal and the electrode layer 217, and determine whether the battery cell 21 is in a safe state according to the voltage difference, so as to determine the performance of the battery cell 21.

In some embodiments, the charge-discharge voltage-charge state curve corresponding to the material of the electrode layer 217 has a charge-discharge plateau voltage, and the voltage difference between the charge-discharge plateau voltages in the charge-discharge voltage-charge state curves corresponding to the charge-discharge processes of multiple cycles is less than a preset value.

In step S2: before the voltage difference between the first electrode terminal 213 and the third electrode 216 is obtained, further comprising: the electrode layer 217 is activated and the voltage of the electrode layer 217 is adjusted to the charge-discharge plateau voltage.

The activation of the electrode layer 217 is a process of converting an active material in the electrode layer 217 into a positive electrode plate or a negative electrode plate having electrochemical characteristics by charge and discharge with the electrode layer 217 as a positive electrode or a negative electrode. After the electrode layer 217 is activated, the voltage of the electrode layer 217 is adjusted by adjusting the storage electric quantity of the active material in the electrode layer 217, so that the voltage of the electrode layer 217 is at the charge-discharge platform voltage. Since the electrode layer 217 is electrically connected to the third electrode 216, the voltage of the electrode layer 217 is the same as the voltage of the third electrode 216, i.e., the voltage of the third electrode 216 is also at the charge-discharge plateau voltage.

In these embodiments, by activating the electrode layer 217, the active material in the electrode layer 217 is converted into positive and negative plates having electrochemical properties so as to detect an accurate voltage difference between the third electrode 216 and the first electrode terminal 213.

In some embodiments, the step of activating the electrode layer 217 and adjusting the voltage of the electrode layer 217 to the charge-discharge plateau voltage specifically includes: in response to the material of the electrode layer 217 being a positive electrode material, performing charge and discharge operations a plurality of times with the first electrode terminal 213 as a negative electrode and the third electrode 216 as a positive electrode; or, in response to the material of the electrode layer 217 being a negative electrode material, the second electrode terminal 214 is taken as a positive electrode, and the third electrode 216 is taken as a negative electrode for a plurality of charge and discharge operations; the voltage of the electrode layer 217 is adjusted to the charge-discharge plateau voltage by the charge-discharge operation.

The charge and discharge operation refers to that in the constant current charge and discharge process, the charge and discharge current is limited, and the current input of the battery is kept unchanged until the battery voltage reaches the required charge and discharge voltage. This method is suitable for applications requiring fast charging, such as vehicle-mounted batteries.

In these embodiments, it is determined that the third electrode 216 is connected to the first electrode terminal 213 or the second electrode terminal 214 according to the material of which the electrode layer 217 is made, so as to convert the active material in the electrode layer 217 into positive and negative electrode plates having electrochemical characteristics, and the voltages of the third electrode 216 and the electrode layer 217 are adjusted to a stable plateau voltage through a charge-discharge operation.

In these embodiments, since the lithium titanate and the lithium iron phosphate have stable plateau voltages, the voltage of the third electrode 216 is stabilized by electrically connecting the lithium titanate or the lithium iron phosphate with the third electrode 216, and the charging condition of the electrode terminal in the battery cell 21 is detected more accurately.

In some embodiments, the battery cell 21 further includes a housing 211, the electrode assembly 215 is disposed within the housing 211, and the housing 211 serves as the third electrode 216.

The step of acquiring the voltage difference between the first electrode terminal 213 and the third electrode 216 in step S2 specifically includes: acquiring a first voltage difference between the first electrode terminal 213 and the case 211, which are not in a charge-discharge state for a preset period of time; the step of determining the safety performance of the battery cell 21 based on the voltage difference in step S3 specifically includes: when the first voltage difference value is decreased within a preset period of time, it is determined that corrosion of the housing 211 occurs.

The duration of the preset time period can be set according to actual conditions.

In these alternative embodiments, by using the housing 211 as the third electrode 216, the corrosion condition of the housing 211 may be determined based on the voltage difference between the third electrode 216 and the negative terminal.

The corrosion phenomenon of the case 211 as the positive electrode occurs because the case 211 overlaps the anode of the battery cell 21 to form a primary battery. For example, the material of the case 211 is aluminum metal, and the anode of the battery cell 21 is lithium metal. Electrons in the primary cell are transferred from the anode to the housing 211 and lithium ions intercalate into lattice octahedral voids of aluminum metal to form a lithium aluminum alloy. As the degree of intercalation of lithium ions increases, the lithium aluminum alloy reacts with oxygen and carbon dioxide in the air to form alkali metal salts, causing the housing 211 to be corroded. The potential difference between the third electrode 216 electrically connected to the corroded casing 211 and the first electrode terminal 213 (i.e., the negative electrode terminal) decreases, thereby causing a voltage difference between the third electrode 216 and the first electrode terminal 213 to decrease compared to a voltage difference where the corrosion phenomenon does not occur. If the case 211 is not corroded, the voltage difference between the first electrode terminal 213 and the third electrode 216 should be constant when the battery cell 21 is not in the charge-discharge state.

Accordingly, when the first voltage difference is decreased, indicating that there is no charge-discharge, there is charge transfer between the first electrode terminal 213 (i.e., the negative electrode terminal) and the case 211, so that it can be determined that there is a corrosion condition of the case 211 when the first voltage difference is decreased.

The detection method of the embodiment of the application not only can indicate that the battery cell 21 has a fault, but also can determine that the fault type is that the shell 211 is corroded, and can reduce the thermal runaway risk of the battery cell 21.

In some embodiments, the step of determining the safety performance of the battery cell 21 based on the voltage difference value specifically includes: and in the preset time period, when the first voltage difference value is smaller than or equal to the first voltage threshold value, determining that the corrosion condition of the shell 211 is serious, and sending out an alarm signal.

The first voltage threshold may be set according to actual conditions. The voltage difference between the negative terminal and the third electrode 216 when severe corrosion of the case 211 occurs may be determined to be the first voltage threshold, for example, by experiments in advance.

In these alternative embodiments, by comparing the first voltage difference value with the first voltage threshold value, it may be determined whether the corrosion condition of the housing 211 is serious, and when the corrosion condition of the housing 211 is serious, an alarm signal is sent, so that the user can know the corrosion condition of the housing 211 in time to improve the safety performance of the battery cell 21.

According to some embodiments of the present application, in step S2: the step of obtaining the voltage difference between the first electrode terminal 213 and the third electrode 216 specifically includes: acquiring a second voltage difference between the first electrode terminal 213 and the third electrode 216 in the charged state; in step S3: the step of determining the safety performance of the battery cell 21 based on the voltage difference value specifically includes: when the second voltage difference is less than or equal to the second voltage threshold, it is determined that lithium precipitation occurs at the first electrode terminal 213. Wherein, lithium ions can be released from the positive electrode and inserted into the negative electrode during the charging process of the lithium ion battery. However, if some abnormal conditions occur and lithium ions released from the positive electrode cannot be inserted into the negative electrode, lithium ions are precipitated only on the surface of the negative electrode, and a gray substance is formed, which is called lithium precipitation.

The second voltage threshold may be set according to the actual situation. It may be determined, for example, experimentally in advance that the voltage difference between the first electrode terminal 213 and the third electrode 216 is the second voltage threshold when the lithium precipitation condition occurs at the first electrode terminal 213.

In these alternative embodiments, it can be determined whether lithium precipitation at the negative terminal occurs by comparing the second voltage threshold to the second voltage difference in state of charge. The detection method of the embodiment of the application not only can indicate that the battery cell 21 has a fault, but also can determine that the fault type is that the negative terminal has lithium precipitation, and can reduce the thermal runaway risk of the battery cell 21.

Further, in the detection method provided in the embodiment of the present application, the voltage difference between the first electrode terminal 213, the second electrode terminal 214, and the third electrode 216 of the battery cell 21 of the molded product is directly compared, and the fault condition of the battery cell 21 is determined from the voltage difference. The structure of the battery monomer 21 of the formed product is closer to that of the battery monomer 21 in actual use, so that the detection result of the detection method provided by the embodiment of the application is more suitable for the actual product, and the detection deviation between experimental data and the actual product can be improved.

Referring to fig. 8 and 9, fig. 8 is a schematic structural diagram of a detection module for a battery cell according to an embodiment of the present disclosure; fig. 9 is a schematic structural diagram of a detection module of a battery cell according to another embodiment of the present application. The battery cell 21 may be the battery cell 21 shown in fig. 4, 5, and 6.

The detection module 30 of the safety performance of the battery cell 21 in the present embodiment includes an acquisition unit 31 and a processing unit 32.

According to some embodiments of the present application, as shown in fig. 4, 5, 6 and 8, the battery cell 21 includes an electrode assembly 215, a third electrode 216 and an electrode layer 217, the electrode layer 217 being of a conductive material and being electrically connected to the third electrode 216, the electrode assembly 215 including a first electrode terminal 213 and a second electrode terminal 214; the first electrode terminal 213 is a negative electrode terminal, and the acquiring unit 31 is configured to acquire a voltage difference between the first electrode terminal 213 and the third electrode 216; the processing unit 32 is used to determine the safety performance of the battery cell 21 based on the voltage difference.

In the technical solution of this embodiment, by electrically connecting the third electrode 216 and the electrode layer 217 to improve the problem of potential drift of the third electrode 216, the third electrode 216 and the electrode layer 217 are used together as reference electrodes, the obtaining unit 31 can obtain an accurate voltage difference between the third electrode 216 and the first electrode terminal 213, that is, an accurate voltage difference between the negative electrode terminal and the third electrode 216, and the processing unit 32 can determine the safety performance of the battery cell 21 according to the voltage difference, and determine the performance of the battery cell 21.

In some embodiments, the charge-discharge voltage-charge state curve corresponding to the material of the electrode layer 217 has a charge-discharge plateau voltage, and the voltage difference between the charge-discharge plateau voltages in the charge-discharge voltage-charge state curves corresponding to the charge-discharge processes of multiple cycles is less than a preset value. As shown in fig. 4, 5, 6 and 9, the detection module 30 for the safety performance of the battery cell 21 further includes a preprocessing unit 33, where the preprocessing unit 33 is configured to activate the electrode layer 217 and adjust the voltage of the electrode layer 217 to the charge-discharge platform voltage.

The electrode layer 217 is activated by the pre-processing unit 33 provided so that the active material in the electrode layer 217 is converted into positive and negative plates having electrochemical characteristics, so as to detect an accurate voltage difference between the third electrode 216 and the first electrode terminal 213.

In some embodiments, the preprocessing unit 33 is configured to perform multiple charge and discharge operations with the first electrode terminal 213 as a negative electrode and the third electrode 216 as a positive electrode when the material of the electrode layer 217 is a positive electrode material; or, in the case where the material of the electrode layer 217 is a negative electrode material, the second electrode terminal 214 is used as a positive electrode, and the third electrode 216 is used as a negative electrode, and charge and discharge operations are performed a plurality of times; the voltage of the electrode layer 217 is adjusted to the charge-discharge plateau voltage by the charge-discharge operation.

The connection of the third electrode 216 to the first electrode terminal 213 or the second electrode terminal 214 is determined by the provision of the preprocessing unit 33 according to the material of which the electrode layer 217 is made, to convert the active material in the electrode layer 217 into positive and negative electrode plates having electrochemical characteristics, and to regulate the voltages of the third electrode 216 and the electrode layer 217 to a stable plateau voltage through the charge-discharge operation.

Since the lithium titanate and the lithium iron phosphate have stable platform voltages, the voltage of the third electrode 216 is stable by electrically connecting the lithium titanate or the lithium iron phosphate with the third electrode 216, and the electrification condition of the electrode terminal in the battery cell 21 is detected more accurately.

In some embodiments, the battery cell 21 further includes a housing 211, the electrode assembly 215 is disposed within the housing 211, and the housing 211 serves as the third electrode 216; the acquisition unit 31 is for acquiring a first voltage difference between the first electrode terminal 213 and the case 211, which are not in a charge-discharge state for a preset period of time; the processing unit 32 is configured to determine that the housing 211 is corroded when the first voltage difference falls within a preset time period.

The detection module 30 of the present embodiment can not only indicate that the battery cell 21 has failed, but also determine that the failure type is that the housing 211 has corrosion, and can reduce the risk of thermal runaway of the battery cell 21.

In some embodiments, the processing unit 32 is configured to determine that the corrosion condition of the housing 211 is serious when the first voltage difference is less than or equal to the first voltage threshold value within a preset period of time, and send an alarm signal.

The processing unit 32 in this embodiment can determine whether the corrosion condition of the housing 211 is serious by comparing the first voltage difference value with the first voltage threshold value, and send out an alarm signal when the corrosion condition of the housing 211 is serious, so that the user can know the corrosion condition of the housing 211 in time to improve the safety performance of the battery cell 21.

In some embodiments, the battery cell 21 further includes a housing 211, the electrode assembly 215 is disposed within the housing 211, and the housing 211 serves as the third electrode 216; the acquisition unit 31 is configured to acquire a second voltage difference between the first electrode terminal 213 and the third electrode 216 in a charged state; the processing unit 32 is configured to determine that the first electrode terminal 213 is subjected to lithium precipitation when the second voltage difference is less than or equal to the second voltage threshold.

The detection module 30 of the embodiment of the application not only can indicate that the battery cell 21 has a fault, but also can determine that the fault type is that the negative terminal has lithium precipitation, and can reduce the thermal runaway risk of the battery cell 21.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the embodiments, and are intended to be included within the scope of the claims and description. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, the battery cell comprising:

a housing having a wall portion and a receiving chamber defined by the wall portion;

an electrode assembly disposed in the receiving chamber and connected to the first electrode terminal and the second electrode terminal;

a third electrode provided on the wall portion, the third electrode, the first electrode terminal, and the second electrode terminal being insulated from each other;

the electrode layer is arranged between the shell and the electrode assembly, the electrode layer electrically connected with the third electrode is made of conductive materials and is mutually insulated from the electrode assembly, and a charge-discharge voltage-charge state curve corresponding to the conductive materials for manufacturing the electrode layer is provided with a charge-discharge platform voltage.

2. The battery cell of claim 1, wherein the housing comprises a conductive material and the housing acts as the third electrode.

3. The battery cell of claim 2, wherein the wall portion includes a housing having an opening and an end cap covering the opening, the end cap and/or the housing acting as the third electrode.

4. The battery cell of claim 1, wherein the wall portion includes a housing having an opening and an end cap covering the opening, and the third electrode is disposed on a side of the end cap or the housing facing away from the receiving chamber.

5. The battery cell of any one of claims 1 to 4, wherein the electrode layer comprises an electrode coating layer disposed on a surface of the wall portion facing the receiving cavity, the electrode coating layer and the electrode assembly being insulated from each other and the electrode coating layer being electrically connected to the third electrode.

6. The battery cell according to any one of claims 1 to 4, wherein the electrode layer includes an electrode film disposed between the wall portion and the electrode assembly, the electrode film and the electrode assembly being insulated from each other and the electrode film being electrically connected to the third electrode.

7. The battery cell of any one of claims 1 to 4, wherein the electrode layer is made of a material comprising one of lithium titanate and lithium iron phosphate.

8. The battery cell of claim 1, further comprising a signal line comprising a first signal line connecting the first electrode terminal and the third electrode and a second signal line connecting the second electrode terminal and the third electrode.

9. A battery, comprising: the battery cell according to any one of claims 1 to 8.

10. An electrical device comprising the battery of claim 9 for providing electrical energy.

11. The method for detecting the safety performance of the battery monomer is characterized by comprising the following steps of:

providing a battery cell, wherein the battery cell comprises an electrode assembly, a third electrode and an electrode layer, the electrode layer is made of conductive materials and is electrically connected with the third electrode, and the electrode assembly comprises a first electrode terminal and a second electrode terminal; the first electrode terminal is a negative electrode terminal; the charge-discharge voltage-charge state curve corresponding to the conductive material of the electrode layer is provided with a charge-discharge platform voltage;

acquiring a voltage difference between the first electrode terminal and the third electrode;

determining whether the battery cell is in a safe state based on the voltage difference.

12. The detecting method according to claim 11, wherein the voltage difference between the charge and discharge plateau voltages in the charge and discharge voltage-state-of-charge curves respectively corresponding to the charge and discharge processes of the plurality of cycles is smaller than a preset value,

before the step of obtaining the voltage difference between the first electrode terminal and the third electrode, the method further includes:

And adjusting the voltage of the electrode layer to the voltage of the charge-discharge platform.

13. The method of claim 12, wherein,

the step of adjusting the voltage of the electrode layer to the voltage of the charge-discharge platform specifically includes:

when the material of the electrode layer is a positive electrode material, the first electrode terminal is used as a negative electrode, and the third electrode is used as a positive electrode to perform multiple charge and discharge operations; or, in the case that the material of the electrode layer is a negative electrode material, performing charge and discharge operations for a plurality of times by using the second electrode terminal as a positive electrode and the third electrode as a negative electrode;

and adjusting the voltage of the electrode layer to the voltage of the charge-discharge platform through charge-discharge operation.

14. The method of detection of claim 13, wherein the positive electrode material comprises lithium titanate and the negative electrode material comprises lithium iron phosphate.

15. The detection method according to any one of claims 11 to 14, wherein the battery cell further includes a case in which the electrode assembly is disposed, the case functioning as the third electrode;

the step of obtaining the voltage difference between the first electrode terminal and the third electrode specifically includes:

Acquiring a first voltage difference value between the first electrode terminal and the shell, which are not in a charge-discharge state within a preset time period;

the step of determining whether the battery cell is in a safe state based on the voltage difference value specifically includes:

and determining that the shell is corroded when the first voltage difference value is reduced in the preset time period.

16. The method of claim 15, wherein,

and in the preset time period, when the first voltage difference value is smaller than or equal to a first voltage threshold value, determining that the corrosion condition of the shell is serious, and sending out an alarm signal.

17. The method of claim 16, wherein,

acquiring a second voltage difference between the first electrode terminal and the third electrode in a charged state;

And determining that lithium precipitation occurs at the first electrode terminal when the second voltage difference is less than or equal to a second voltage threshold.

18. The detection module is characterized in that the battery cell comprises an electrode assembly, a third electrode and an electrode layer, wherein the electrode layer is made of a conductive material and is electrically connected with the third electrode, a charge-discharge voltage-charge state curve corresponding to the conductive material of the electrode layer is made to have a charge-discharge platform voltage, and the electrode assembly comprises a first electrode terminal and a second electrode terminal; the first electrode terminal is a negative electrode terminal;

the detection module comprises:

an acquisition unit configured to acquire a voltage difference between the first electrode terminal and the third electrode;

and the processing unit is used for determining whether the battery cell is in a safe state or not based on the voltage difference value.

19. The detecting module according to claim 18, wherein the voltage difference between the charging and discharging plateau voltages in the charging and discharging voltage-state of charge curves respectively corresponding to the plurality of times of the cyclic charging and discharging processes is smaller than a preset value,

the detection module further comprises:

and the preprocessing unit is used for adjusting the voltage of the electrode layer to the voltage of the charge-discharge platform.

20. The detection module according to claim 19, wherein the preprocessing unit is configured to perform charge and discharge operations for a plurality of times with the first electrode terminal as a negative electrode and the third electrode as a positive electrode, in a case where the material of the electrode layer is a positive electrode material; or, in the case that the material of the electrode layer is a negative electrode material, performing charge and discharge operations for a plurality of times by using the second electrode terminal as a positive electrode and the third electrode as a negative electrode; and adjusting the voltage of the electrode layer to the voltage of the charge-discharge platform through charge-discharge operation.

21. The detection module of claim 20, wherein the positive electrode material comprises lithium titanate and the negative electrode material comprises lithium iron phosphate.

22. The detection module according to any one of claims 18 to 21, wherein the battery cell further comprises a housing within which the electrode assembly is disposed, the housing functioning as the third electrode;

the acquisition unit is used for acquiring a first voltage difference value between the first electrode terminal and the shell, wherein the first electrode terminal is not in a charge-discharge state within a preset time period;

the processing unit is used for determining that the shell is corroded when the first voltage difference value is reduced in the preset time period.

23. The detection module of claim 22, wherein the processing unit is configured to determine that the corrosion of the housing is severe when the first voltage difference is less than or equal to a first voltage threshold during the predetermined time period, and to send an alarm signal.

24. The detection module of claim 23, wherein the detection module,

the acquisition unit is used for acquiring a second voltage difference value between the first electrode terminal and the third electrode in a charged state;

the processing unit is used for determining that lithium is separated from the first electrode terminal when the second voltage difference value is smaller than or equal to a second voltage threshold value.