A method, device and electronic device for judging the aging mechanism of a lithium iron phosphate battery

Abstract

The present invention relates to a method, device, and electronic device for determining the aging mechanism of lithium iron phosphate batteries. The method comprises: constructing a battery model, performing charge and discharge processing on the battery model, obtaining a discharge curve and a preset battery aging evaluation index value for the battery model after the charge and discharge processing; using the discharge curve to obtain a preset characteristic curve and obtain characteristic parameters of the preset characteristic curve; and determining the aging mechanism of the battery model based on the characteristic parameters and the preset battery aging evaluation index value. The method for determining the aging mechanism of lithium iron phosphate batteries disclosed in the present invention can identify factors influencing lithium battery aging caused by the loss of active lithium ions.

Description

Technical Field

[0001] The present invention relates to the field of lithium battery technology, and in particular to a method, device, electronic device and computer-readable storage medium for determining the aging mechanism of a lithium iron phosphate battery. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density, low self-discharge rate, and no memory effect. They are becoming increasingly popular in all aspects of social production and have become the first choice for electric vehicle power batteries. As the power core of electric vehicles, their cycle life is crucial to the cost and range of electric vehicles.

[0003] Battery cyclic aging is a very complex process with numerous and interacting degradation mechanisms. It can ultimately be divided into three main aging mechanisms: increase in battery internal resistance, loss of active materials, and loss of active lithium ions. Usually, during the battery cyclic aging process, all three aging mechanisms will always participate in the aging process partially or completely, so it is not easy to determine which aging mechanism is affecting the battery life.

[0004] At present, most of the research on the judgment of lithium battery aging mechanism focuses on single-body research on the increase of battery internal resistance and the loss of active materials. However, the loss of active lithium ions has a great impact on the aging of lithium batteries and cannot be ignored. Summary of the Invention

[0005] In view of this, it is necessary to provide a method, device, electronic device and computer-readable storage medium for determining the aging mechanism of lithium iron phosphate batteries to solve the problem in the prior art that it is impossible to determine the aging of lithium batteries caused by the loss of active lithium ions.

[0006] In order to solve the above problems, the present invention provides a method for determining the aging mechanism of lithium iron phosphate batteries, comprising:

[0007] Constructing a battery model, performing charge and discharge processing on the battery model, and obtaining a discharge curve of the battery model after the charge and discharge processing and a preset battery aging evaluation index value;

[0008] Obtaining a preset characteristic curve using the discharge curve, and acquiring characteristic parameters of the preset characteristic curve;

[0009] The aging mechanism of the battery model is determined according to the characteristic parameters and the preset evaluation battery aging index value.

[0010] Furthermore, a battery model is constructed, including:

[0011] Construct a battery model that incorporates the mechanisms that pre-determine the battery aging reactions.

[0012] Furthermore, before obtaining the preset evaluation battery aging index value of the battery model after charge and discharge processing, it includes:

[0013] The rated capacity of the battery model and the remaining capacity of the battery model after charge and discharge processing are obtained.

[0014] Furthermore, obtaining a preset evaluation battery aging index value of the battery model after charge and discharge processing includes:

[0015] The SOH value of the battery model after charge and discharge treatment is calculated using a calculation formula for evaluating battery aging indicators, the rated capacity of the battery model, and the remaining capacity of the battery model after charge and discharge treatment;

[0016] The calculation formula for evaluating the battery aging index is: Among them, Q 剩余 is the remaining capacity of the battery model after charge and discharge processing, Q 额定 is the rated capacity of the battery model.

[0017] Furthermore, obtaining a preset characteristic curve using the discharge curve includes:

[0018] The IC curve is obtained using the discharge curve.

[0019] Furthermore, obtaining characteristic parameters of the preset characteristic curve includes:

[0020] The peak value, peak area, peak position, left and right slopes of the peak and discharge time corresponding to the peak of the preset characteristic curve are obtained.

[0021] Furthermore, judging the aging mechanism of the battery model according to the characteristic parameter and the preset evaluation battery aging index value includes:

[0022] Calculating the correlation between the characteristic parameter and the preset battery aging evaluation index value using the Pearson correlation coefficient method;

[0023] If the correlation degree is greater than a set threshold, the characteristic parameter is used as the aging mechanism of the battery model.

[0024] The present invention also provides a device for determining the aging mechanism of lithium iron phosphate batteries, comprising a model building module, a parameter acquisition module and an aging determination module;

[0025] The model building module is used to build a battery model, perform charge and discharge processing on the battery model, and obtain a discharge curve of the battery model after the charge and discharge processing and a preset battery aging evaluation index value;

[0026] The parameter acquisition module is used to obtain a preset characteristic curve using the discharge curve, and obtain characteristic parameters of the preset characteristic curve;

[0027] The aging judgment module is used to judge the aging mechanism of the battery model according to the characteristic parameters and the preset battery aging evaluation index value.

[0028] The present invention also provides an electronic device comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the method for determining the aging mechanism of a lithium iron phosphate battery as described in any of the above technical solutions is implemented.

[0029] The present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for determining the aging mechanism of a lithium iron phosphate battery as described in any of the above technical solutions is implemented.

[0030] The beneficial effect of adopting the above embodiment is: the method for judging the aging mechanism of lithium iron phosphate batteries provided by the present invention constructs a battery model for active lithium ion loss, performs charge and discharge processing on the battery model, and analyzes the aging process of the battery model, thereby judging the aging mechanism of the battery model, and thus finding the influencing factors of lithium battery aging caused by active lithium ion loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic flow chart of an embodiment of a method for determining the aging mechanism of a lithium iron phosphate battery provided by the present invention;

[0032] Figure 2 A schematic diagram of a discharge curve of a battery model provided in an embodiment of the present invention;

[0033] Figure 3 A diagram showing the corresponding relationship between the discharge curve and the IC curve of the battery model provided in an embodiment of the present invention;

[0034] Figure 4 A schematic diagram of an IC curve of a battery model provided in an embodiment of the present invention;

[0035] Figure 5 This is a structural block diagram of an embodiment of a device for determining the aging mechanism of a lithium iron phosphate battery provided by the present invention;

[0036] Figure 6 This is a structural block diagram of an embodiment of an electronic device provided by the present invention. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0038] The present invention provides a method, device, electronic device, and computer-readable storage medium for determining the aging mechanism of a lithium iron phosphate battery, which are described in detail below.

[0039] The embodiment of the present invention provides a method for determining the aging mechanism of lithium iron phosphate batteries, the flow chart of which is as follows: Figure 1 As shown, the method for determining the aging mechanism of lithium iron phosphate batteries includes:

[0040] Step S101: constructing a battery model, performing charge and discharge processing on the battery model, and obtaining a discharge curve of the battery model after the charge and discharge processing and a preset evaluation battery aging index value;

[0041] Step S102: obtaining a preset characteristic curve using the discharge curve, and acquiring characteristic parameters of the preset characteristic curve;

[0042] Step S103: determining the aging mechanism of the battery model according to the characteristic parameters and the preset battery aging evaluation index value.

[0043] It should be noted that, compared with the prior art, the present invention constructs a battery model for active lithium ion loss, performs charge and discharge processing on the battery model, and analyzes the aging process of the battery model, thereby determining the aging mechanism of the battery model, and thus finding the influencing factors of lithium battery aging caused by active lithium ion loss.

[0044] In a specific embodiment, constructing a battery model includes building a P2D model of a lithium iron phosphate battery in multi-physics field simulation software comsol, adding an SEI film to the P2D model of the lithium iron phosphate battery to generate a side reaction, and changing the conductivity of the SEI film to make its conductivity equal to that of graphite, and charging and discharging the battery model including cyclically charging and discharging the battery model at 25°C and 0.5C for 480 cycles, and extracting its discharge curve every 80 cycles. A schematic diagram of the discharge curve of the battery model is shown as follows. Figure 2 As shown, Figure 2 The horizontal axis is capacity (unit: Ah), the vertical axis is voltage (unit: V), and obtaining the preset evaluation battery aging index value is to obtain the battery SOH value.

[0045] As a preferred embodiment, building a battery model includes:

[0046] Construct a battery model that incorporates the mechanisms that pre-determine the battery aging reactions.

[0047] It should be noted that the constructed battery model only includes the side reaction of generating SEI film because it is known that during the charging process of lithium batteries, lithium ions will be consumed to generate a layer of solid electrolyte interface film, namely SEI film, on the surface of the graphite negative electrode, which will also increase the internal resistance of the battery. Therefore, adding the side reaction of generating SEI film and changing the conductivity of SEI film can eliminate the influence of increased internal resistance. At this time, there is only one aging mechanism of the battery, namely the loss of active lithium ions.

[0048] As a preferred embodiment, before obtaining the preset evaluation battery aging index value of the battery model after charge and discharge processing, the method includes:

[0049] The rated capacity of the battery model and the remaining capacity of the battery model after charge and discharge processing are obtained.

[0050] As a preferred embodiment, obtaining a preset evaluation battery aging index value of a battery model after charge and discharge processing includes:

[0051] The SOH value of the battery model after charge and discharge treatment is calculated using a calculation formula for evaluating battery aging indicators, the rated capacity of the battery model, and the remaining capacity of the battery model after charge and discharge treatment;

[0052] The calculation formula for evaluating the battery aging index is: Among them, Q 剩余 is the remaining capacity of the battery model after charge and discharge processing, Q 额定 is the rated capacity of the battery model.

[0053] It should be noted that there are many ways to calculate the battery SOH value. The capacity calculation used in the present invention is simpler. For a new battery, the initial SOH value is 100%. When the SOH value reaches 80%, the battery reaches the retirement condition.

[0054] As a preferred embodiment, obtaining a preset characteristic curve using the discharge curve includes:

[0055] The IC curve is obtained using the discharge curve.

[0056] In a specific embodiment, the corresponding relationship diagram of the battery model discharge curve and IC curve is as follows: Figure 3 As shown, all the discharge curves are converted into IC curves, and the schematic diagram of the IC curve of the battery model is as follows: Figure 4 As shown, Figure 4 The horizontal axis is voltage (unit: V), and the vertical axis is capacity increment dQ / dV (unit: Ah / V). Figure 4It can be seen that peaks 2 and 5 hardly change with the progress of aging, which can be determined that the lithium battery has no increase in internal resistance and loss of active materials. Peak 1 changes regularly with the progress of aging. Therefore, peak 1 is used as the research object for lithium battery aging caused by loss of active lithium ions.

[0057] As a preferred embodiment, obtaining characteristic parameters of the preset characteristic curve includes:

[0058] The peak value, peak area, peak position, left and right slopes of the peak and discharge time corresponding to the peak of the preset characteristic curve are obtained.

[0059] As a preferred embodiment, judging the aging mechanism of the battery model according to the characteristic parameter and the preset evaluation battery aging index value includes:

[0060] Calculating the correlation between the characteristic parameter and the preset battery aging evaluation index value using the Pearson correlation coefficient method;

[0061] If the correlation degree is greater than a set threshold, the characteristic parameter is used as the aging mechanism of the battery model.

[0062] In a specific embodiment, the Pearson correlation coefficient formula is used. Calculate the correlation between the characteristic parameter and the preset evaluation battery aging index value, where cov(X, Y) is the covariance of the characteristic parameter X and the preset evaluation battery aging index value Y, σ is the standard deviation, and ρ is the correlation. The correlation values between the characteristic parameters of the IC curve and the SOH value are shown in Table 1 below;

[0063] Table 1 Correlation between characteristic parameters of IC curve and SOH value

[0064] characteristic parameters Correlation value ρ Peak 0.9998 Peak position 0.9967 Peak area 0.9998 Left slope 0.9961 Right slope -0.9908 Discharge time 0.9998

[0065] As can be seen from Table 1, the highest correlation value between the peak value and peak area of peak 1 in the characteristic parameters and the SOH value is 0.9998. Therefore, these two characteristic parameters can be used to judge whether active lithium ion loss occurs during the aging process of lithium batteries. When the correlation value of these two characteristic parameters with SOH is greater than 95%, it indicates that active lithium ion loss has occurred.

[0066] The embodiment of the present invention also provides a device for judging the aging mechanism of lithium iron phosphate batteries, the structural block diagram of which is as follows: Figure 5 As shown, the device for determining the aging mechanism of a lithium iron phosphate battery includes a model building module 501, a parameter acquisition module 502 and an aging determination module 503;

[0067] The model building module 501 is used to build a battery model, perform charge and discharge processing on the battery model, and obtain a discharge curve of the battery model after the charge and discharge processing and a preset battery aging evaluation index value;

[0068] The parameter acquisition module 502 is configured to obtain a preset characteristic curve using the discharge curve and obtain characteristic parameters of the preset characteristic curve;

[0069] The aging judgment module 503 is used to judge the aging mechanism of the battery model according to the characteristic parameters and the preset battery aging evaluation index value.

[0070] like Figure 6 As shown in the above method for determining the aging mechanism of lithium iron phosphate batteries, the present invention also provides an electronic device, which can be a computing device such as a mobile terminal, desktop computer, notebook, PDA, and server. The electronic device includes a processor 603, a display 602, and a memory 601.

[0071] In some embodiments, the memory 601 may be an internal storage unit of a computer device, such as a hard disk or memory of the computer device. In other embodiments, the memory 601 may also be an external storage device of the computer device, such as a plug-in hard disk equipped on the computer device, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. Furthermore, the memory 601 may also include both an internal storage unit of the computer device and an external storage device. The memory 601 is used to store application software and various types of data installed on the computer device, such as program codes for installing the computer device. The memory 601 can also be used to temporarily store data that has been output or is to be output. In one embodiment, a program 604 for determining the aging mechanism of a lithium iron phosphate battery is stored on the memory 601, and the program 604 for determining the aging mechanism of a lithium iron phosphate battery can be executed by the processor 603, thereby realizing the method for determining the aging mechanism of a lithium iron phosphate battery in each embodiment of the present invention.

[0072] In some embodiments, the processor 603 can be a central processing unit (CPU), a microprocessor or other data processing chip, used to run the program code or process data stored in the memory 601, such as executing a program for determining the aging mechanism of lithium iron phosphate batteries.

[0073] In some embodiments, the display 602 can be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, or an OLED (Organic Light-Emitting Diode) touchscreen. The display 602 is used to display information on the computer device and to display a visual user interface. The components 601-603 of the computer device communicate with each other via a system bus.

[0074] In one embodiment, when the processor 603 executes the lithium iron phosphate battery aging mechanism determination program 604 in the memory 601, the following steps are implemented:

[0075] Constructing a battery model, performing charge and discharge processing on the battery model, and obtaining a discharge curve of the battery model after the charge and discharge processing and a preset battery aging evaluation index value;

[0076] Obtaining a preset characteristic curve using the discharge curve, and acquiring characteristic parameters of the preset characteristic curve;

[0077] The aging mechanism of the battery model is determined according to the characteristic parameters and the preset evaluation battery aging index value.

[0078] This embodiment further provides a computer-readable storage medium storing a program for determining the aging mechanism of a lithium iron phosphate battery. When the program for determining the aging mechanism of a lithium iron phosphate battery is executed by a processor, the following steps are implemented:

[0079] Constructing a battery model, performing charge and discharge processing on the battery model, and obtaining a discharge curve of the battery model after the charge and discharge processing and a preset battery aging evaluation index value;

[0080] Obtaining a preset characteristic curve using the discharge curve, and acquiring characteristic parameters of the preset characteristic curve;

[0081] The aging mechanism of the battery model is determined according to the characteristic parameters and the preset evaluation battery aging index value.

[0082] The present invention provides a method, device, electronic device and computer-readable storage medium for determining the aging mechanism of lithium iron phosphate batteries. By constructing a battery model for active lithium ion loss, the battery model is subjected to charge and discharge processing to analyze the aging process of the battery model, thereby determining the aging mechanism of the battery model. Therefore, it is possible to identify the factors affecting the aging of lithium batteries caused by active lithium ion loss.

[0083] This technical solution is mainly used to determine whether active lithium ion loss occurs in the lithium iron phosphate battery during the aging process. Subsequent analysis is performed through the IC curve to observe the impact of active lithium ion loss on various characteristic parameters of the IC curve, including peak value, peak area, peak position, left slope, right slope and discharge time corresponding to the peak. The correlation between each characteristic parameter and SOH is then analyzed. For characteristic parameters with high correlation, they are affected by active lithium ion loss. Therefore, characteristic parameters with high correlation with SOH can be used as the basis for determining whether active lithium ion loss occurs in the lithium battery during the aging process.

[0084] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0085] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for determining the aging mechanism of lithium iron phosphate batteries, characterized in that: include: Constructing a battery model, performing charge and discharge processing on the battery model, and obtaining a discharge curve of the battery model after the charge and discharge processing and a preset battery aging evaluation index value; Obtaining a preset characteristic curve using the discharge curve, and acquiring characteristic parameters of the preset characteristic curve; Determining the aging mechanism of the battery model according to the characteristic parameters and the preset battery aging evaluation index value; Build a battery model, including: A battery model is constructed that incorporates a mechanism that presets a battery aging reaction, a SEI film generation side reaction is added to the battery model, and the conductivity of the SEI film is made equal to that of graphite.

2. The method for determining the aging mechanism of lithium iron phosphate batteries according to claim 1, characterized in that: Before obtaining the preset evaluation battery aging index value of the battery model after charge and discharge processing, including: The rated capacity of the battery model and the remaining capacity of the battery model after charge and discharge processing are obtained.

3. The method for determining the aging mechanism of lithium iron phosphate batteries according to claim 2, characterized in that: Obtain the preset evaluation battery aging index values of the battery model after charge and discharge processing, including: The SOH value of the battery model after charge and discharge treatment is calculated using a calculation formula for evaluating battery aging indicators, the rated capacity of the battery model, and the remaining capacity of the battery model after charge and discharge treatment; The calculation formula for evaluating the battery aging index is: ,in, is the remaining capacity of the battery model after charge and discharge processing, is the rated capacity of the battery model.

4. The method for determining the aging mechanism of lithium iron phosphate batteries according to claim 1, characterized in that: Obtaining a preset characteristic curve using the discharge curve includes: The IC curve is obtained using the discharge curve.

5. The method for determining the aging mechanism of lithium iron phosphate batteries according to claim 1, characterized in that: Obtaining characteristic parameters of the preset characteristic curve includes: The peak value, peak area, peak position, left and right slopes of the peak and discharge time corresponding to the peak of the preset characteristic curve are obtained.

6. The method for determining the aging mechanism of lithium iron phosphate batteries according to claim 1, characterized in that: Determining the aging mechanism of the battery model according to the characteristic parameter and the preset evaluation battery aging index value includes: Calculating the correlation between the characteristic parameter and the preset battery aging evaluation index value using the Pearson correlation coefficient method; If the correlation degree is greater than a set threshold, the characteristic parameter is used as the aging mechanism of the battery model.

7. A device for determining the aging mechanism of lithium iron phosphate batteries, characterized in that: It includes model building module, parameter acquisition module and aging judgment module; The model building module is used to build a battery model, perform charge and discharge processing on the battery model, and obtain a discharge curve of the battery model after the charge and discharge processing and a preset battery aging evaluation index value; Build a battery model, including: Constructing a battery model that incorporates a preset mechanism causing battery aging reactions, adding a SEI film generation side reaction to the battery model, and making the conductivity of the SEI film equal to that of graphite; The parameter acquisition module is used to obtain a preset characteristic curve using the discharge curve, and obtain characteristic parameters of the preset characteristic curve; The aging judgment module is used to judge the aging mechanism of the battery model according to the characteristic parameters and the preset battery aging evaluation index value.

8. An electronic device, characterized in that: The invention comprises a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method for determining the aging mechanism of a lithium iron phosphate battery according to any one of claims 1 to 6 is implemented.

9. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the computer program is executed by a processor, the method for determining the aging mechanism of a lithium iron phosphate battery as described in any one of claims 1 to 6 is implemented.

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