Battery safety evaluation method based on electrochemical normalization model

Abstract

The application provides a battery safety evaluation method based on an electrochemical normalization model, and relates to the technical field of power systems, wherein the method comprises the following steps: modeling the decomposition of a solid electrolyte interface, the reaction between an anode and an electrolyte, the reaction between a cathode and the electrolyte, and the decomposition reaction of the electrolyte in a battery thermal runaway process based on the internal reaction mechanism of the battery thermal runaway process, to obtain a four-step reaction temperature model; establishing a one-step global temperature model of the battery thermal runaway process based on the four-step reaction temperature model, inputting the parameters of a target battery into the one-step global temperature model, and outputting the temperature safety range boundary of the target battery thermal runaway process; and evaluating the safety of the target battery based on the temperature safety range boundary. The application adopting the above scheme realizes the prediction of the battery thermal runaway characteristics and provides a reference for the safe operation of the battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, and particularly relates to a battery safety evaluation method and device based on an electrochemical normalization model. BACKGROUND

[0002] With the development of global decarbonization and electrification trends, the research and development of lithium-ion batteries (LIBs) have attracted extensive attention due to their applications in ground transportation and energy storage. One of the biggest challenges facing lithium-ion batteries is thermal runaway, which occurs under inappropriate conditions such as overheating, overcharging, collision, and internal short circuit, and side reactions occur between battery materials. These side reactions not only release heat and increase the battery temperature, but also release flammable gases and particles, which can trigger subsequent combustion and fire, leading to a larger scale of thermal runaway spread. Thermal runaway directly threatens life and property safety, and is therefore a key factor in future battery design and safety evaluation. SUMMARY

[0003] The present application aims to at least partially solve one of the technical problems in the related art.

[0004] To this end, a first object of the present application is to provide a battery safety evaluation method based on an electrochemical normalization model, which realizes the prediction of battery thermal runaway characteristics and provides a reference for safe operation of the battery.

[0005] A second object of the present application is to provide a battery safety evaluation device based on an electrochemical normalization model.

[0006] A third object of the present application is to provide a computer device.

[0007] A fourth object of the present application is to provide a non-transitory computer readable storage medium.

[0008] To achieve the above objects, a battery safety evaluation method based on an electrochemical normalization model according to a first aspect of the present application comprises: modeling the decomposition of the solid electrolyte interface, the reaction between the anode and the electrolyte, the reaction between the cathode and the electrolyte, and the decomposition reaction of the electrolyte in the battery thermal runaway process based on the internal reaction mechanism of the battery thermal runaway process, to obtain a four-step reaction temperature model; establishing a one-step global temperature model of the battery thermal runaway process based on the four-step reaction temperature model, and inputting the parameters of the target battery into the one-step global temperature model to output the temperature safety range boundary of the target battery thermal runaway process; and evaluating the safety of the target battery based on the temperature safety range boundary.

[0009] The battery safety evaluation method based on the electrochemical normalization model of the embodiment of the application realizes the prediction of the thermal runaway characteristics of the battery by combining the battery electrochemical model, the thermal runaway process and the real-time state monitoring of the battery, and provides a reference for the safe operation of the battery.

[0010] Optionally, in an embodiment of the application, the decomposition of the solid electrolyte interface is modeled, including:

[0011] The thermal abuse reaction of the lithium ion battery is represented by a first equation, wherein the first equation is:

[0012]

[0013] wherein c sei is the dimensionless quantity of lithium-containing metastable species in the SEI film, A sei is the decomposition frequency factor of the SEI film, E a,sei is the SEI decomposition activation energy, R is the ideal gas constant, T is the temperature, H is the reaction heat, and W is the density of the reactants in the medium.

[0014] Optionally, in an embodiment of the application, the reaction between the anode and the electrolyte is modeled, including:

[0015] The reaction between the anode and the electrolyte is represented by a second equation, wherein the second equation is:

[0016]

[0017] wherein c ne represents the dimensionless quantity of lithium-containing metastable species in the graphite, A ne represents the frequency factor of the reaction between the negative electrode and the electrolyte, represents the dimensionless quantity of lithium embedded in the graphite, t sei represents the dimensionless thickness of the SEI film, t sei0 represents the reference SEI layer thickness, E a,ne represents the SEI decomposition activation energy, R is the ideal gas constant, T is the temperature, H is the reaction heat, and W is the density of the reactants in the medium.

[0018] Optionally, in an embodiment of the application, the reaction between the cathode and the electrolyte is modeled, including:

[0019] The reaction between the cathode and the electrolyte is represented by a third equation, wherein the third equation is:

[0020]

[0021] wherein A pe represents the frequency factor of the reaction between the positive electrode and the electrolyte, m pe,p1m is the reaction order of alpha pe,p2 E represents the reaction order of (1-alpha) a,pe H represents the heat of reaction, and W represents the density of the reactants in the medium.

[0022] Optionally, in an embodiment of the present application, the decomposition reaction of the electrolyte is modeled, including:

[0023] The exothermic decomposition of the electrolyte at high temperature is represented by a fourth equation, wherein the fourth equation is:

[0024]

[0025] A represents the frequency factor of electrolyte decomposition, e E represents the frequency factor of electrolyte decomposition, E represents the proportion of residual electrolyte, a,e H represents the heat of reaction, and W represents the density of the reactants in the medium.

[0026] Optionally, in an embodiment of the present application, a one-step global temperature model is established, represented as:

[0027] The one-step global temperature model is represented by a species and energy conservation law, wherein the species and energy conservation law is:

[0028]

[0029] H represents the heat of reaction, and W represents the density of the reactants in the medium. The temperature rise rate value is a temperature rise rate value.

[0030] Optionally, in an embodiment of the present application, the parameters of the target battery are input into the one-step global temperature model, and the temperature safety range boundary of the target battery thermal runaway process is output, including:

[0031] The temperature rise rate value in the one-step global model is set based on the parameters of the target real battery, and the battery temperature is solved to obtain the upper and lower temperature bounds of the predicted battery thermal runaway process.

[0032] To achieve the above purpose, a second aspect embodiment of the present application proposes a battery safety evaluation device based on an electrochemical normalization model, including:

[0033] The reaction model construction module is used to model the decomposition of the solid electrolyte interface, the reaction between the anode and the electrolyte, the reaction between the cathode and the electrolyte, and the decomposition reaction of the electrolyte in the battery thermal runaway process based on the internal reaction mechanism of the battery thermal runaway process, to obtain a four-step reaction temperature model.

[0034] The global model construction module is configured to establish a one-step global temperature model of a battery thermal runaway process based on a four-step reaction temperature model, input parameters of a target battery into the one-step global temperature model, and output a temperature safety range boundary of the target battery thermal runaway process.

[0035] The safety evaluation module is configured to evaluate the safety of the target battery based on the temperature safety range boundary.

[0036] To achieve the above object, the third aspect of the present application provides a computer device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, the above-mentioned battery safety evaluation method based on the electrochemical normalization model is realized.

[0037] To achieve the above object, the fourth aspect of the present application provides a non-transitory computer readable storage medium, when the instructions in the storage medium are executed by the processor, the above-mentioned battery safety evaluation method based on the electrochemical normalization model can be executed.

[0038] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above-mentioned and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

[0040] Figure 1 A flowchart of a battery safety evaluation method based on an electrochemical normalization model provided by the first aspect of the present application;

[0041] Figure 2 A structural schematic diagram of a battery safety evaluation device based on an electrochemical normalization model provided by the present application. DETAILED DESCRIPTION

[0042] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.

[0043] Table 1 shows the meanings of the parameters involved in the present application.

[0044] Table 1

[0045]

[0046]

[0047] A battery safety evaluation method and device based on an electrochemical normalization model are described below with reference to the accompanying drawings.

[0048] Figure 1 A flowchart of a battery safety evaluation method based on an electrochemical normalization model is provided in Embodiment One of the present application.

[0049] As shown in Figure 1 The battery safety evaluation method based on an electrochemical normalization model includes the following steps:

[0050] Step 101: Based on the internal reaction mechanism of the battery thermal runaway process, the decomposition of the solid electrolyte interface, the reaction between the anode and the electrolyte, the reaction between the cathode and the electrolyte, and the decomposition reaction of the electrolyte in the battery thermal runaway process are modeled respectively, and a four-step reaction temperature model is obtained;

[0051] Step 102: A one-step global temperature model of the battery thermal runaway process is established based on the four-step reaction temperature model, and the parameters of the target battery are input into the one-step global temperature model, and the temperature safety range boundary of the target battery thermal runaway process is output;

[0052] Step 103: The safety of the target battery is evaluated based on the temperature safety range boundary.

[0053] The battery safety evaluation method based on an electrochemical normalization model of the present application starts from the modeling aspect, evaluates the critical temperature of the hot spot that can trigger self-sustaining thermal runaway based on the concept of minimum ignition energy, determines the safety range boundary of thermal runaway through calculation, and specifically, realizes the prediction of the battery thermal runaway characteristics by combining the battery electrochemical model, the thermal runaway process, and the real-time state monitoring of the battery, and provides a reference for the safe operation of the battery.

[0054] The present application describes the battery through an electrochemical model, which significantly reduces the calculation complexity and does not significantly reduce the calculation accuracy; at the same time, the lower limit and upper limit of the kinetic modeling are determined by using a one-step global chemical method, which realizes the effective prediction of the battery thermal runaway characteristics.

[0055] Optionally, in an embodiment of the present application, the battery aging reaction mechanism is analyzed, and specifically,

[0056] Thermal runaway side reactions usually include: decomposition of SEI film, melting of separator, decomposition of cathode material, decomposition and combustion of electrolyte, etc. Generally speaking, when the temperature reaches about 70-100 degrees Celsius, the solid electrolyte interface releases heat and the battery temperature continues to rise. When the temperature reaches the melting point of the separator, the separator absorbs heat, melts and shrinks. The separator material is usually made of polypropylene or polyethylene, and the characteristic temperature is about 120-130 degrees Celsius. The significant increase in internal resistance is a typical feature after the melting of the separator (Analysis of the aging effects on the thermal runaway characteristics of Lithium-Ion cells through stepwise reactions). As the side reactions continue to occur, the battery internal short circuit occurs due to the loss of protection between the anode and the cathode, and a large amount of heat is released in a short time, and the temperature rises rapidly. At this time, with the decomposition of the positive electrode material and the electrolyte, oxygen may be generated in the battery, and combustion may occur, and the highest temperature often reaches two or three hundred degrees Celsius.

[0057] Optionally, in an embodiment of the present application, the decomposition of the solid electrolyte interface is modeled, including:

[0058] By listing the component reactions that occur at high temperatures, the thermal abuse reactions of lithium-ion batteries can be modeled for three-dimensional battery simulation.

[0059] The negative electrode is protected from direct reaction with the solvent by an ionically conductive film called the solid electrolyte interface (SEI). This layer is metastable and can exothermically decompose at 90-120°C, which reaction can be represented by the following equation:

[0060]

[0061] Optionally, in an embodiment of the present application, the reaction between the anode and the electrolyte is modeled, including:

[0062] At high temperatures (>120°C), an exothermic reaction occurs between the intercalated lithium and the electrolyte, as shown in the following formula:

[0063]

[0064] Optionally, in an embodiment of the present application, the reaction between the cathode and the electrolyte is modeled, including:

[0065] In the oxidized state, the positive electrode material reacts directly with the electrolyte. Alternatively, the positive electrode active material can decompose exothermically and release oxygen, which can react exothermically with the electrolyte. In any case, the chemical reduction of the positive electrode active material with the electrolyte is highly exothermic (equation).

[0066]

[0067] Optionally, in an embodiment of the application, the decomposition reaction of the electrolyte is modeled, including:

[0068] The electrolyte can decompose exothermically at high temperatures (> 200°C), as shown in the following equation:

[0069]

[0070] Optionally, in an embodiment of the application, a one-step global temperature model is established, including:

[0071] For actual operation, the four-step thermal runaway model has the disadvantages of complex parameters and cumbersome solution. In order to solve the challenges brought by the parameter optimization of the four-step thermal runaway model and the inherent battery variability in the thermal runaway test, this embodiment proposes a thermal runaway statistical analysis method based on a one-step global chemical model. From the four-step reaction process, a one-step global chemical model in the form of Arrhenius can be uniquely determined. By directly statistically analyzing the one-step global mechanism of each battery, the average and standard deviation of the frequency factor and activation energy can be easily obtained. Then the variation of the frequency factor and activation energy can be used to quantify the uncertainty range of the thermal runaway chemistry. By comparing the experimental data with the nominal value and the uncertainty range of the model, the battery safety can be more strictly evaluated on the basis of statistical analysis.

[0072] The one-step global model will use the following species and energy conservation laws:

[0073]

[0074] where H is the overall enthalpy change of the thermal runaway process, H = c p ΔT = c p (T3-T1), is the temperature rise rate value, so the above equation is independent of the battery's own heat capacity parameter.

[0075] where delta T and the battery state of charge have a strong correlation. When the battery SOC is high, the proportion of active material inside the battery is high, and the highest temperature that can be reached during thermal runaway, i.e. T3, also increases, while the starting temperature of the battery thermal runaway decreases accordingly. At this time, delta T will also increase.

[0076] Through statistical analysis, the frequency factor A can be expressed as 3.49E8 ± 2.40E8 min-1, and the global activation energy is 8.58E4 ± 2.04E3 J / mol. Compared with the frequency factor, the global activation energy shows a smaller percentage change.

[0077] Optionally, in an embodiment of the present application, the temperature rise rate value in the formula is set according to the parameters obtained according to the above process. The is 0.02℃ / min, and the temperature is solved. It can be intuitively seen that the upper limit (110.2℃) of the predicted exothermic starting temperature Texo occurs when A takes the minimum value and E takes the maximum value, and the lower limit (71.8℃) of Texo prediction occurs when A takes the maximum value and E takes the minimum value. When A and E take the average value, the nominal value (86.5℃) of the starting temperature can be obtained.

[0078] In order to realize the above-mentioned embodiment, the present application further provides a battery safety evaluation device based on an electrochemical normalization model.

[0079] Figure 2 A structural schematic diagram of a battery safety evaluation device based on an electrochemical normalization model provided in an embodiment of the present application.

[0080] As Figure 2 shown, the battery safety evaluation device based on the electrochemical normalization model includes:

[0081] A reaction model construction module, configured to model the decomposition of the solid electrolyte interface, the reaction between the anode and the electrolyte, the reaction between the cathode and the electrolyte, and the decomposition reaction of the electrolyte in the battery thermal runaway process based on the internal reaction mechanism of the battery thermal runaway process, to obtain a four-step reaction temperature model;

[0082] A global model construction module, configured to establish a one-step global temperature model of the battery thermal runaway process based on the four-step reaction temperature model, and input the parameters of the target battery into the one-step global temperature model to output the temperature safety range boundary of the target battery thermal runaway process;

[0083] A safety evaluation module, configured to evaluate the safety of the target battery based on the temperature safety range boundary.

[0084] It should be noted that the aforementioned explanation and description of the embodiment of the battery safety evaluation method based on the electrochemical normalization model also apply to the embodiment of the battery safety evaluation device based on the electrochemical normalization model, which will not be described here.

[0085] In order to achieve the above-mentioned embodiments, the application further provides a computer device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the method of the above-mentioned embodiments when executing the computer program.

[0086] In order to achieve the above-mentioned embodiments, the application further provides a non-transitory computer readable storage medium, having a computer program stored thereon, wherein the computer program is executable by a processor to implement the method of the above-mentioned embodiments.

[0087] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the description of the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0088] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0089] Any process or method descriptions in flow charts or otherwise described herein can be understood as representing code modules, segments, or portions of code that include one or more executable instructions for implementing the specified logic functions or processes, and the preferred embodiments of the present application also include additional implementation examples, in which the functions can be performed in different orders, in different ways, or in reverse, and the described embodiments should not be construed as limited to the described or discussed order or sequence of functions, and the skilled person in the art should understand that the described embodiments can be implemented in other ways, such as in a substantially simultaneous manner or in reverse order, according to the functions involved.

[0090] The logic and / or steps represented in flow diagrams or otherwise described herein, for example, can be considered as a sequence of instructions to implement logic functions, and can be embodied in any computer-readable medium for use by an instruction execution system, apparatus, or device, such as a computer-based system, processor- containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this specification, a "computer-readable medium" can be any means that can contain, store, communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-readable medium can be a machine-readable storage device (e.g., magnetic, optical or other) a machine-readable storage diskette (e.g., floppy disk, optical disk, CD- ROM, etc.), a machine- readable storage card (e.g., PCMCIA card, etc.), a machine-readable storage tape (e.g., magnetic tape, optical tape, etc.), a machine-readable storage medium (e.g., RAM, ROM, etc.), a machine-readable signal (e.g., electrical, optical, etc.), a machine-readable medium (e.g., carrier wave, etc.) or any other suitable medium or means of embodying the program. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a RAM, a ROM, an EPROM, a FLASH memory card, an optical fiber, and a portable compact disc read-only memory (CD-ROM). Additionally, the computer-readable medium can be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, for example, via optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and stored in a computer memory.

[0091] It should be understood that aspects of the application can be implemented in hardware, software, firmware or combinations thereof. In the above embodiments, various steps or methods can be implemented in software or firmware that is stored in memory and executed by a suitable instruction execution system. As such, in some embodiments, the steps or methods can be implemented in hardware such as a special purpose computer, a programmed microprocessor or microcontroller, a microprocessor-based or a microcontroller-based application-specific integrated circuit, a peripheral integrated circuit element, a digital signal processor, a highly-parallelized architecture or other similar or well-known computing devices. In other embodiments, the steps or methods can be implemented in software that is stored in a memory and executed on a suitable instruction execution system. In other embodiments, the steps or methods can be implemented in a combination of both software and hardware.

[0092] Those of skill in the art would understand that information and signals can be represented using any of a variety of technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0093] In addition, each of the functional units in the various embodiments of the present application can be integrated in one processing module, or each of the units can be physically present separately, or two or more units can be integrated in one module. The integrated module can be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer readable storage medium.

[0094] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method for battery safety assessment based on electrochemical normalization model, characterized in that, The method comprises: internal reaction mechanism of the battery thermal runaway process, to model the decomposition of the solid electrolyte interface, the reaction between the anode and the electrolyte, the reaction between the cathode and the electrolyte, and the decomposition reaction of the electrolyte in the battery thermal runaway process, to obtain a four-step reaction temperature model; wherein the decomposition of the solid electrolyte interface is modeled, comprising: a first equation is used to represent the thermal abuse reaction of the lithium ion battery, wherein the first equation is: wherein c sei is the dimensionless quantity of the lithium-containing metastable species in the SEI film, A sei is the decomposition frequency factor of the SEI film, E a,sei is the SEI decomposition activation energy, R is the ideal gas constant, T is the temperature, H is the reaction heat, and W is the density of the reactants in the medium; the reaction between the anode and the electrolyte is modeled, comprising: a second equation is used to represent the reaction between the anode and the electrolyte, wherein the second equation is: wherein c ne represents a dimensionless quantity of lithium-containing metastable state in graphite, A ne represents a frequency factor of reaction of the negative electrode with the electrolyte, represents a dimensionless quantity of lithium intercalated in graphite, t sei represents a dimensionless thickness of the SEI film, t sei0 represents a reference SEI layer thickness, E a,ne represents an SEI decomposition activation energy; the reaction between the cathode and the electrolyte is modeled, comprising: a third equation is used to represent the reaction between the cathode and the electrolyte, wherein the third equation is: wherein A pe represents a frequency factor of the reaction of the positive electrode with the electrolyte, m pe,p1 is the reaction order of a, m pe,p2 represents the reaction order of (1-a), E a,pe represents the activation energy of the reaction of the positive electrode with the electrolyte; the decomposition reaction of the electrolyte is modeled, comprising: a fourth equation is used to represent the exothermic decomposition of the electrolyte at high temperature, wherein the fourth equation is: wherein A e represents a frequency factor of electrolyte decomposition, represents the proportion of residual electrolyte, E a,e represents the activation energy of electrolyte decomposition; a one-step global temperature model of the battery thermal runaway process is established based on the four-step reaction temperature model, and parameters of the target battery are input into the one-step global temperature model to output a temperature safety range boundary of the target battery thermal runaway process; wherein the one-step global temperature model is established, comprising: the one-step global temperature model is represented by the species and energy conservation law, wherein the species and energy conservation law is: wherein, H is the overall enthalpy change of the thermal runaway process; and the safety of the target battery is evaluated based on the temperature safety range boundary.

2. The method of claim 1, wherein, The one-step global temperature model is established based on the four-step reaction temperature model, and parameters of the target battery are input into the one-step global temperature model to output a temperature safety range boundary of the target battery thermal runaway process, comprising: the temperature rise rate value in the one-step global model is set based on the parameters of the target real battery, and the battery temperature is solved to obtain the upper and lower boundaries of the predicted battery thermal runaway process temperature.

3. A battery safety assessment device based on an electrochemical normalization model, characterized in that, The device implements the method of claim 1, and the device comprises: a reaction model construction module configured to model the decomposition of the solid electrolyte interface, the reaction between the anode and the electrolyte, the reaction between the cathode and the electrolyte, and the decomposition reaction of the electrolyte in the battery thermal runaway process based on the internal reaction mechanism of the battery thermal runaway process, to obtain a four-step reaction temperature model; a global model construction module configured to establish a one-step global temperature model of the battery thermal runaway process based on the four-step reaction temperature model, and input parameters of a target battery into the one-step global temperature model to output a temperature safety range boundary of the target battery thermal runaway process; a safety evaluation module configured to evaluate the safety of the target battery based on the temperature safety range boundary.

4. A computer device, comprising: The computer program is executed by the processor to implement the method of any one of claims 1-2.

5. A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the method of any one of claims 1-2.

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