Method and apparatus for analyzing impedance of a battery

Abstract

A battery impedance analysis method and device are provided to improve the accuracy of battery impedance information analysis. The method comprises obtaining electrochemical impedance spectrum data of the battery at a first temperature, wherein the first temperature is in a range of -10 DEG C to -30 DEG C; obtaining a pore ion resistance of the battery at the first temperature according to the electrochemical impedance spectrum data of the battery at the first temperature; obtaining conductivities of the electrolyte at the first temperature and a second temperature; obtaining a pore ion resistance of the battery at the second temperature according to the pore ion resistance of the battery at the first temperature and the conductivities of the electrolyte at the first temperature and the second temperature; obtaining electrochemical impedance spectrum data of the battery at the second temperature; and obtaining an interface reaction impedance of the battery at the second temperature according to the pore ion resistance of the battery at the second temperature and the electrochemical impedance spectrum data of the battery at the second temperature.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a method and apparatus for impedance analysis of batteries. Background Technology

[0002] Lithium-ion batteries are widely used in power batteries, energy storage, and other fields due to their advantages such as high energy density, good cycle performance, no memory effect, high operating voltage, low self-discharge rate, low internal resistance, and environmental friendliness. Studying the interfacial reaction processes of lithium-ion batteries is of great significance for elucidating their capacity decay mechanism and improving their cycle capacity and rate performance. Electrochemical impedance spectroscopy (EIS), as an important method for studying interfacial reaction processes, is widely used in the lithium battery industry.

[0003] Porous electrodes, due to their larger reaction surface area, are widely used in lithium-ion batteries, which facilitates electrochemical reactions. Lithium ions encounter resistance during migration within the porous electrode; however, current impedance analysis methods using electrochemical induction (EIS) neglect this migration resistance, resulting in low accuracy. Therefore, accurately analyzing the impedance information of lithium-ion batteries is a pressing issue that needs to be addressed. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a method for impedance analysis of batteries, which is beneficial to improving the accuracy of impedance information analysis of lithium-ion batteries.

[0005] To achieve the above objectives, this application provides a method and apparatus for impedance analysis of batteries.

[0006] In a first aspect, an impedance analysis method for a battery is provided, comprising: acquiring electrochemical impedance spectroscopy (EIS) data of the battery at a first temperature, wherein the first temperature ranges from -10°C to -30°C; obtaining the pore ionic resistance of the battery at the first temperature based on the EIS data; acquiring the conductivity of the electrolyte of the battery at the first temperature and a second temperature; obtaining the pore ionic resistance of the battery at the second temperature based on the pore ionic resistance of the battery at the first temperature and the conductivity of the electrolyte at the first temperature and the second temperature; acquiring the EIS data of the battery at the second temperature; and obtaining the interfacial reaction impedance of the battery at the second temperature based on the pore ionic resistance and the EIS data.

[0007] In this embodiment, the pore ionic resistance of the battery at a first temperature (ranging from -10°C to -30°C) can be obtained by analyzing the electrochemical impedance spectroscopy data. Then, based on the obtained conductivity of the electrolyte at both the first and second temperatures, the pore ionic resistance of the battery at the second temperature is calculated. Since the pore ionic resistance of the battery at the second temperature is determined, when there is overlap between the frequency ranges corresponding to the pore ionic resistance and the interfacial reaction impedance in the electrochemical impedance spectroscopy data at the second temperature, the pore ionic resistance can be considered a constant with a definite value. Therefore, when analyzing the electrochemical impedance spectroscopy data, the analysis will not be inaccurate in the frequency ranges where the pore ionic resistance and the interfacial reaction impedance overlap because both are variables. The technical solution of this application, when the frequency ranges of pore ion resistance and interfacial reaction impedance of the battery at the second temperature overlap, calculates the pore ion resistance of the battery at the second temperature by analyzing the electrochemical impedance spectroscopy data of the battery at the first temperature (where the frequency ranges of pore ion resistance and interfacial reaction impedance of the battery at the first temperature do not overlap) and combining it with the conductivity of the electrolyte at the first and second temperatures respectively. Therefore, in the electrochemical impedance spectroscopy data of the battery at the second temperature, only the interfacial reaction impedance is a variable in the frequency range corresponding to the interfacial reaction impedance. Based on this, the interfacial reaction impedance of the battery at the second temperature can be obtained by analyzing the electrochemical impedance spectroscopy data, thereby achieving accurate analysis of the interfacial reaction impedance of the battery at the second temperature.

[0008] In one possible implementation, obtaining the pore ion resistance of the battery at the first temperature based on the electrochemical impedance spectroscopy data of the battery at the first temperature includes: selecting data from the electrochemical impedance spectroscopy data of the battery at the first temperature corresponding to the pore ion resistance of the battery at the first temperature; and fitting the data from the first characteristic frequency range to obtain the pore ion resistance of the battery at the first temperature.

[0009] In one possible implementation, obtaining the pore ion resistance of the battery at the second temperature based on the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first and second temperatures includes: substituting the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first and second temperatures into the relationship equation between the pore ion resistance of the battery and the conductivity of the electrolyte to calculate the pore ion resistance of the battery at the second temperature.

[0010] In one possible implementation, obtaining the interfacial reaction impedance of the battery at the second temperature based on the pore ion resistance and electrochemical impedance spectroscopy data of the battery at the second temperature includes: processing the electrochemical impedance spectroscopy data of the battery at the second temperature based on the pore ion resistance of the battery at the second temperature to obtain processed electrochemical impedance spectroscopy data of the battery at the second temperature; selecting data from the processed electrochemical impedance spectroscopy data of the battery at the second temperature corresponding to a first characteristic frequency range of pore ion resistance and a second characteristic frequency range corresponding to the interfacial reaction impedance; and fitting the data from the first characteristic frequency range and the second characteristic frequency range to obtain the interfacial reaction impedance of the battery at the second temperature.

[0011] In one possible implementation, fitting the data of the first characteristic frequency range and the second characteristic frequency range to obtain the interface reaction impedance of the battery at the second temperature includes: fitting the data of the first characteristic frequency range and the second characteristic frequency range with an equivalent circuit model of a transmission line to obtain the interface reaction impedance of the battery at the second temperature.

[0012] In one possible implementation, fitting the data in the first characteristic frequency range to obtain the pore ion resistance of the battery at the first temperature includes: fitting the data in the first characteristic frequency range with a transmission line equivalent circuit model to obtain the pore ion resistance of the battery at the first temperature.

[0013] In one possible implementation, the battery is a three-electrode battery.

[0014] In one possible implementation, the electrochemical impedance spectroscopy data of the battery is 200kHz to 1MHz electrochemical impedance spectroscopy data detected by a preset pulse current signal.

[0015] In a second aspect, an impedance analysis device for a battery is provided. The device includes: a first acquisition module for acquiring electrochemical impedance spectroscopy data of the battery at a first temperature and a second temperature, wherein the first temperature ranges from -10℃ to -30℃; a first data processing module for obtaining the pore ion resistance of the battery at the first temperature based on the electrochemical impedance spectroscopy data of the battery at the first temperature; a second acquisition module for acquiring the conductivity of the electrolyte of the battery at the first temperature and the second temperature; a second data processing module for obtaining the pore ion resistance of the battery at the second temperature based on the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first temperature and the second temperature; and the first data processing module is further used to obtain the interfacial reaction impedance of the battery at the second temperature based on the pore ion resistance and the electrochemical impedance spectroscopy data of the battery at the second temperature.

[0016] In one possible implementation, the first data processing module is specifically used to: select data from the electrochemical impedance spectroscopy data of the battery at the first temperature corresponding to the first characteristic frequency range of the pore ion resistance; and fit the data from the first characteristic frequency range to obtain the pore ion resistance of the battery at the first temperature.

[0017] In one possible implementation, the second data processing module is specifically used to: obtain a relationship equation between the pore ion resistance of the battery and the conductivity of the electrolyte based on the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first temperature; and calculate the pore ion resistance of the battery at the second temperature based on the relationship equation and the conductivity of the electrolyte at the second temperature.

[0018] Thirdly, an impedance analysis apparatus for a battery is provided, the apparatus comprising a processor and a memory for storing instructions, the processor for reading the instructions and executing an impedance analysis method according to the first aspect and any possible implementation thereof. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart illustrating an impedance analysis method according to an embodiment of this application;

[0021] Figure 2 This is the Nyquist plot corresponding to the electrochemical impedance spectroscopy data of a battery according to an embodiment of this application at a first temperature;

[0022] Figure 3 This is the Nyquist plot corresponding to the electrochemical impedance spectroscopy data of a battery according to an embodiment of this application at a second temperature;

[0023] Figure 4 The Nyquist plot corresponds to the electrochemical impedance spectroscopy data of a battery according to an embodiment of this application after treatment at a second temperature.

[0024] Figure 5 This is a battery equivalent circuit according to an embodiment of this application;

[0025] Figure 6 This is a schematic block diagram of a battery impedance analysis device according to an embodiment of this application;

[0026] Figure 7 This is a schematic block diagram of a battery impedance analysis device according to another embodiment of this application. Detailed Implementation

[0027] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0028] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0029] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0031] Lithium-ion batteries are widely used in power batteries, energy storage, and other fields due to their advantages such as high energy density, good cycle performance, no memory effect, high operating voltage, low self-discharge rate, low internal resistance, and environmental friendliness. Studying the interfacial reaction processes of lithium-ion batteries is of great significance for elucidating their capacity decay mechanism and improving their cycle capacity and rate performance.

[0032] Electrochemical interfacial imaging (EIS), as an important method for studying interfacial reaction processes, is widely used in the lithium-ion battery industry. EIS can determine the different reactions occurring at electrodes within different frequency ranges based on the varying time constants of each step in the electrochemical reaction. Using EIS to study the relevant kinetic parameters of lithium-ion insertion and extraction processes in electrode materials, such as the resistance, electronic conductivity, charge transfer resistance, and diffusion coefficient of lithium ions within the solid electrolyte interface (SEI) film, as well as the relationship between these kinetic parameters and electrode polarization potential and temperature, plays a crucial role in understanding the mechanisms of lithium-ion insertion and extraction in electrode materials, particularly in the failure mechanisms of lithium-ion batteries.

[0033] Porous electrodes, due to their larger reaction surface area, are widely used in lithium-ion batteries, which facilitates electrochemical reactions. However, lithium ions encounter resistance during migration within the porous electrode. Current methods using EIS to establish equivalent circuit models for fitting and analyzing the response characteristics of lithium batteries during charge and discharge neglect this impedance during migration, resulting in low accuracy in impedance analysis. Therefore, accurately fitting and analyzing the impedance information of lithium-ion batteries is a pressing problem that needs to be solved.

[0034] In view of this, this application provides an impedance analysis method for a battery. By analyzing the electrochemical impedance spectroscopy data of the battery at a first temperature (the first temperature ranges from -10℃ to -30℃), the pore ionic resistance of the battery at the first temperature can be obtained. Then, based on the obtained conductivity of the electrolyte at the first and second temperatures, the pore ionic resistance of the battery at the second temperature can be calculated. Since the pore ionic resistance of the battery at the second temperature is determined, when there is overlap in the frequency ranges corresponding to the pore ionic resistance and the interfacial reaction impedance in the electrochemical impedance spectroscopy data at the second temperature, the pore ionic resistance can be regarded as a constant with a definite value. Thus, when analyzing the electrochemical impedance spectroscopy data, the analysis of the electrochemical impedance spectroscopy data will not be inaccurate because both the pore ionic resistance and the interfacial reaction impedance are variables, especially in the overlapping frequency ranges. The technical solution of this application, when there is an overlap in the frequency range of the pore ion resistance and interfacial reaction impedance of the battery at the second temperature, calculates the pore ion resistance of the battery at the second temperature by analyzing the electrochemical impedance spectroscopy data of the battery at the first temperature (where the frequency ranges of the pore ion resistance and interfacial reaction impedance of the battery at the first temperature do not overlap) and combining it with the conductivity of the electrolyte at the first and second temperatures respectively. Therefore, in the electrochemical impedance spectroscopy data of the battery at the second temperature, only the interfacial reaction impedance is a variable in the frequency range corresponding to the interfacial reaction impedance. Based on this analysis of the electrochemical impedance spectroscopy data of the battery at the second temperature, the interfacial reaction impedance of the battery at the second temperature can be obtained, thereby achieving accurate analysis of the interfacial reaction impedance of the battery at the second temperature.

[0035] The impedance analysis method for batteries in this application is applicable to electrical devices with rechargeable batteries. These rechargeable batteries include, but are not limited to, lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, and lead-acid batteries; however, this application does not limit the types of batteries described.

[0036] Figure 1 This is a schematic flowchart of a battery impedance analysis method provided in this application. Figure 1 As shown, the impedance analysis method 100 for batteries includes the following steps.

[0037] Step S101: Obtain electrochemical impedance spectroscopy data of the battery at the first temperature.

[0038] Specifically, the electrochemical impedance spectroscopy (EIS) data of the battery can be obtained using an electrochemical workstation employing AC impedance spectroscopy. In this embodiment, the EIS data of the battery at a first temperature can be obtained under a preset state of charge (SOC), for example, the preset SOC can be 50%. It is understood that in other embodiments, the preset SOC can also be 90%, 85%, etc., and is not specifically limited here.

[0039] refer to Figure 2 , Figure 2 This is the Nyquist plot corresponding to the electrochemical impedance spectroscopy data of the battery obtained in one embodiment of this application at the first temperature. Figure 2 The horizontal axis represents the real part of the impedance, and the vertical axis represents the imaginary part of the impedance. Figure 2 The Nyquist plot in the figure is the Nyquist plot corresponding to the electrochemical impedance spectroscopy data obtained by performing AC impedance testing on the battery using an electrochemical workstation at a temperature of -20°C and a SOC of 50%. In this embodiment, the test conditions are an amplitude of 5mV and a frequency range of 200kHz to 5MHz.

[0040] In this embodiment, the first temperature ranges from -10℃ to -30℃ (excluding -10℃). In the electrochemical impedance spectroscopy data measured at the first temperature, the characteristic frequency ranges of the pore ion resistance and the interfacial reaction impedance do not overlap. Therefore, impedance analysis can be performed separately on the pore ion resistance and the interfacial reaction impedance, allowing for accurate determination of the pore ion resistance value of the battery at the first temperature. (Reference) Figure 2 , Figure 2 The first arc segment a represents the frequency range of the pore ion resistance of the battery at the first temperature, and the second arc segment b represents the frequency range of the interfacial reaction impedance of the battery at the first temperature.

[0041] In this embodiment, pore ion resistance refers to the impedance during the insertion and extraction of metal ions in the pores of the porous electrode. Interfacial reaction impedance is the resistance generated by the charge transfer process of the SEI film on the electrode surface, i.e., charge transfer impedance.

[0042] Step S102: Based on the electrochemical impedance spectroscopy data of the battery at the first temperature, obtain the pore ion resistance of the battery at the first temperature.

[0043] Specifically, data from the first characteristic frequency range corresponding to the pore ion resistance in the electrochemical impedance spectroscopy data of the battery at the first temperature are selected (e.g., Figure 2 The first arc segment a) in the first characteristic frequency range is fitted to obtain the pore ion resistance of the battery at the first temperature.

[0044] In this embodiment, the data of the battery in the first characteristic frequency range at the first temperature can be fitted using a transmission line equivalent circuit model.

[0045] It should be noted that a battery not only contains different components such as a positive electrode, negative electrode, electrolyte, and current collector, but also multiple interfaces such as negative electrode / electrolyte, positive electrode / electrolyte, negative electrode / current collector, and positive electrode / current collector. When electrons or ions pass through these components or interfaces under the drive of an external circuit (charging or discharging), various different physical and chemical processes occur, thereby causing changes in battery impedance and polarization. In step S101, an alternating current with varying frequency is applied to the battery, and the ratio of the alternating current potential to the current signal is measured. This ratio is the impedance of the system, which is the result of the combined effects of the different polarization processes. Since the different polarization processes have overlapping frequency ranges, it is impossible to directly distinguish each process from the frequency domain. For example, at temperatures of -10°C and above, the pore ion resistance and interfacial reaction impedance have overlapping frequency ranges, making it impossible to accurately analyze the impedance information of pore ion resistance and interfacial reaction impedance in the analysis of battery impedance information. At temperatures below -10°C, the pore ion resistance and interfacial reaction impedance do not overlap in frequency, allowing impedance analysis of both to be performed separately within their respective frequency ranges. This application utilizes the analysis results of pore ion resistance at temperatures below -10°C to analyze the interfacial reaction impedance of the battery at temperatures of -10°C and above, as detailed in the following steps.

[0046] Step S103: Obtain the conductivity of the battery electrolyte at the first temperature and the second temperature.

[0047] In this embodiment, the conductivity of the electrolyte can be obtained using a conductivity meter. In this embodiment, the second temperature can be a temperature of -10°C or higher, for example, 0°C, 20°C, 25°C, 40°C, 45°C, etc., which will not be elaborated further here.

[0048] In this embodiment, the conductivity of the electrolyte is obtained by testing the electrolyte using a conductivity meter when the battery is at -20°C and SOC is 50%, and at 25°C and SOC is 50%. The conductivity of the electrolyte at -20°C is 7.44 S / m; the conductivity of the electrolyte at 25°C is 2.2 S / m.

[0049] Step S104: Based on the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first and second temperatures, the pore ion resistance of the battery at the second temperature is obtained.

[0050] Specifically, the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first and second temperatures can be substituted into the relationship equation between the pore ion resistance and conductivity of the battery to calculate the pore ion resistance of the battery at the second temperature. For example, this relationship equation can be shown as follows:

[0051]

[0052] Where, σ a σ represents the conductivity of the electrolyte at the first temperature. b Rion represents the conductivity of the electrolyte at the second temperature. a Rion represents the pore ion resistance of the battery at the first temperature. b This represents the pore ion resistance of the battery at the second temperature.

[0053] In this embodiment, the calculated pore ion resistance of the battery at 25°C is 0.489973Ω.

[0054] Step S105: Obtain electrochemical impedance spectroscopy data of the battery at the second temperature.

[0055] refer to Figure 3 , Figure 3 This is the Nyquist plot corresponding to the electrochemical impedance spectroscopy data of the battery obtained in one embodiment of this application at the second temperature. Figure 3 In the diagram, the horizontal axis represents the real part of the impedance, and the vertical axis represents the imaginary part of the impedance. It should be understood that in this embodiment, the battery used is the one tested with electrochemical impedance spectroscopy data at the first temperature described above; the parameters that are the same as those of the battery will not be repeated here. The difference is that the battery's test temperature is 25°C, the amplitude is 5mV, and the frequency range is 200kHz to 30MHz.

[0056] Step S106: Based on the pore ion resistance and electrochemical impedance spectroscopy data of the battery at the second temperature, the interfacial reaction impedance of the battery at the second temperature is obtained.

[0057] Specifically, based on the pore ion resistance of the battery at the second temperature, the electrochemical impedance spectroscopy data of the battery at the second temperature are processed to obtain the processed electrochemical impedance spectroscopy data of the battery at the second temperature, and the corresponding Nyquist plot is shown below. Figure 4 The blue curve in the graph is shown.

[0058] Then, data from the electrochemical impedance spectroscopy data of the battery after treatment at the second temperature were selected, specifically the first characteristic frequency range corresponding to the pore ion resistance and the second characteristic frequency range corresponding to the interfacial reaction impedance (e.g., Figure 4The third arc segment (c) is used to fit the data of the first and second characteristic frequency ranges to obtain the interfacial reaction impedance of the battery at the second temperature.

[0059] It should be noted that, Figure 4 In the diagram, the blue curves only show the curves corresponding to the first characteristic frequency range of pore ion resistance and the second characteristic frequency range of interfacial reaction impedance in the electrochemical impedance spectroscopy data after the battery treatment at the second temperature. The orange curves are fitted curves obtained by fitting the data of the first characteristic frequency range of pore ion resistance and the second characteristic frequency range of interfacial reaction impedance in the electrochemical impedance spectroscopy data after the battery treatment at the second temperature.

[0060] In this embodiment, the pore ion resistance Rion and the interfacial reaction resistance Rct in the electrochemical impedance spectroscopy data have the functional relationship shown in Equation (II):

[0061]

[0062] Where R represents the characteristic resistance of the battery.

[0063] In this embodiment, the data of the battery in the first and second characteristic frequency ranges at the second temperature can be fitted using a transmission line equivalent circuit model.

[0064] In this embodiment, the pore ionic resistance of the battery at the first temperature can be obtained by analyzing the electrochemical impedance spectroscopy data of the battery at the first temperature. Then, based on the obtained conductivity of the electrolyte at the first and second temperatures, the pore ionic resistance of the battery at the second temperature is calculated. Since the pore ionic resistance of the battery at the second temperature is determined, when there is overlap in the frequency ranges corresponding to the pore ionic resistance and the interfacial reaction impedance in the electrochemical impedance spectroscopy data at the second temperature, the pore ionic resistance can be considered a constant with a definite value. Therefore, when analyzing the electrochemical impedance spectroscopy data, the analysis of the electrochemical impedance spectroscopy data will not be inaccurate because both the pore ionic resistance and the interfacial reaction impedance are variables, especially in the overlapping frequency ranges. The technical solution of this application, when there is an overlap in the frequency range between the pore ion resistance and the interfacial reaction impedance of the battery at the second temperature, calculates the pore ion resistance of the battery at the second temperature by analyzing the electrochemical impedance spectroscopy data of the battery at the first temperature and combining it with the conductivity of the electrolyte at the first and second temperatures respectively. Therefore, in the electrochemical impedance spectroscopy data of the battery at the second temperature, only the interfacial reaction impedance is a variable in the frequency range corresponding to the interfacial reaction impedance. Based on this, the interfacial reaction impedance of the battery at the second temperature can be obtained by analyzing the electrochemical impedance spectroscopy data, thereby achieving accurate analysis of the interfacial reaction impedance of the battery at the second temperature.

[0065] For example, in the embodiments of this application, the transmission line equivalent circuit model can be adopted as follows: Figure 5 The equivalent circuit shown.

[0066] In some embodiments, the battery may be a three-electrode battery. It should be understood that the battery may also be a symmetrical battery, a two-electrode battery, or a coin cell.

[0067] In the above embodiments, the battery is a three-electrode battery. The working electrode is made of NCM ternary material, the counter electrode is made of graphite material, and the reference electrode is made of elemental lithium.

[0068] The impedance analysis method for the battery provided in this application has been described in detail above. The following section will combine... Figure 6 and Figure 7 This application describes the impedance analysis apparatus for batteries provided in the embodiments of the present application. The technical features described in the method embodiments are applicable to the following apparatus embodiments.

[0069] Figure 6 A schematic block diagram of a battery impedance analysis device 600 according to an embodiment of this application is shown. As shown, the impedance analysis device 600 includes a first acquisition module 610, a first data processing module 620, a second acquisition module 630, and a second data processing module 640.

[0070] The first acquisition module 610 is used to acquire electrochemical impedance spectroscopy data of the battery at a first temperature and a second temperature.

[0071] The first data processing module 620 is used to obtain the pore ion resistance of the battery at the first temperature based on the electrochemical impedance spectroscopy data of the battery at the first temperature.

[0072] The second acquisition module 630 is used to acquire the conductivity of the battery electrolyte at a first temperature and a second temperature.

[0073] The second data processing module 640 is used to obtain the pore ion resistance of the battery at the second temperature based on the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first and second temperatures.

[0074] The first data processing module 620 is also used to obtain the interfacial reaction impedance of the battery at the second temperature based on the pore ion resistance and electrochemical impedance spectroscopy data of the battery at the second temperature.

[0075] In some embodiments, the first data processing module 620 is specifically used to select data corresponding to the first characteristic frequency range of pore ion resistance in the electrochemical impedance spectroscopy data of the battery at the first temperature; and to fit the data of the first characteristic frequency range to obtain the pore ion resistance of the battery at the first temperature.

[0076] In some embodiments, the second data processing module 640 is specifically used to: substitute the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first and second temperatures into the relationship equation between the pore ion resistance of the battery and the conductivity of the electrolyte, and calculate the pore ion resistance of the battery at the second temperature.

[0077] It should be understood that the battery impedance analysis device 600 according to the embodiments of this application can correspond to the execution subject in the embodiments of the battery impedance analysis method 100 of this application, and the above and other operations and / or functions of each unit in the battery impedance analysis device 600 are respectively for implementing Figure 1 The corresponding process of the method in the document will not be elaborated here for the sake of brevity.

[0078] Figure 7 Another battery impedance analysis device 700 according to an embodiment of this application is shown. Figure 7 As shown, the impedance analysis device 700 includes a processor 710 and a memory 720. The memory 720 stores instructions, and the processor 710 reads the instructions and executes the methods described in the various embodiments of this application based on the instructions.

[0079] The memory 720 can be a separate device independent of the processor 710, or it can be integrated into the processor 710.

[0080] This application also provides a readable storage medium for storing a computer program for performing the methods described in the various embodiments of this application.

[0081] It is understood that the memory in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), Enhanced Synchronous DRAM (ESDRAM), Synchlink DRAM (SLDRAM), and Direct Rambus RAM (DR RAM). It should be noted that the memory used in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0082] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for impedance analysis of a battery, characterized in that, The method includes: The electrochemical impedance spectroscopy data of the battery are obtained at a first temperature, the first temperature being in the range of -10℃ to -30℃. Based on the electrochemical impedance spectroscopy data of the battery at the first temperature, the pore ion resistance of the battery at the first temperature is obtained; The conductivity of the electrolyte of the battery is obtained at the first temperature and the second temperature; The pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first and second temperatures are used to obtain the pore ion resistance of the battery at the second temperature. Obtain the electrochemical impedance spectroscopy data of the battery at the second temperature; The interfacial reaction impedance of the battery at the second temperature is obtained based on the pore ion resistance and electrochemical impedance spectroscopy data of the battery at the second temperature.

2. The method according to claim 1, characterized in that, The step of obtaining the pore ion resistance of the battery at the first temperature based on the electrochemical impedance spectroscopy data of the battery at the first temperature includes: Select data from the first characteristic frequency range corresponding to the pore ion resistance in the electrochemical impedance spectroscopy data of the battery at the first temperature; The data in the first characteristic frequency range are fitted to obtain the pore ion resistance of the battery at the first temperature.

3. The method according to claim 1 or 2, characterized in that, The step of obtaining the pore ion resistance of the battery at the second temperature based on the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first temperature and the second temperature includes: Substituting the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first temperature and the second temperature into the relationship equation between the pore ion resistance of the battery and the conductivity of the electrolyte, the pore ion resistance of the battery at the second temperature is calculated.

4. The method according to any one of claims 1 to 3, characterized in that, The step of obtaining the interfacial reaction impedance of the battery at the second temperature based on the pore ion resistance and electrochemical impedance spectroscopy data of the battery at the second temperature includes: The electrochemical impedance spectroscopy data of the battery at the second temperature are processed based on the pore ion resistance of the battery at the second temperature to obtain the processed electrochemical impedance spectroscopy data of the battery at the second temperature. Select data from the electrochemical impedance spectroscopy data of the battery after treatment at the second temperature, including the first characteristic frequency range corresponding to the pore ion resistance and the second characteristic frequency range corresponding to the interfacial reaction impedance; By fitting the data from the first characteristic frequency range and the second characteristic frequency range, the interfacial reaction impedance of the battery at the second temperature is obtained.

5. The method according to claim 4, characterized in that, The step of fitting the data from the first characteristic frequency range and the second characteristic frequency range to obtain the interfacial reaction impedance of the battery at the second temperature includes: The data from the first and second characteristic frequency ranges are fitted with the transmission line equivalent circuit model to obtain the interfacial reaction impedance of the battery at the second temperature.

6. The method according to claim 2, characterized in that, The step of fitting the data within the first characteristic frequency range to obtain the pore ion resistance of the battery at the first temperature includes: The data in the first characteristic frequency range is fitted with the transmission line equivalent circuit model to obtain the pore ion resistance of the battery at the first temperature.

7. The method according to any one of claims 1 to 6, characterized in that, The battery is a three-electrode battery.

8. The method according to any one of claims 1 to 7, characterized in that, The electrochemical impedance spectroscopy data of the battery is 200kHz to 1MHz electrochemical impedance spectroscopy data detected by a preset pulse current signal.

9. An impedance analysis device for a battery, characterized in that, The device includes: The first acquisition module is used to acquire electrochemical impedance spectroscopy data of the battery at a first temperature and a second temperature, wherein the value of the first temperature ranges from -10℃ to -30℃. The first data processing module is used to obtain the pore ion resistance of the battery at the first temperature based on the electrochemical impedance spectroscopy data of the battery at the first temperature. The second acquisition module is used to acquire the conductivity of the electrolyte of the battery at the first temperature and the second temperature; The second data processing module is used to obtain the pore ion resistance of the battery at the second temperature based on the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first temperature and the second temperature. The first data processing module is further configured to obtain the interfacial reaction impedance of the battery at the second temperature based on the pore ion resistance and electrochemical impedance spectroscopy data of the battery at the second temperature.

10. The apparatus according to claim 9, characterized in that, The first data processing module is specifically used for: Select data from the first characteristic frequency range corresponding to the pore ion resistance in the electrochemical impedance spectroscopy data of the battery at the first temperature; The data in the first characteristic frequency range are fitted to obtain the pore ion resistance of the battery at the first temperature.

11. The apparatus according to claim 9 or 10, characterized in that, The second data processing module is specifically used for: Substituting the pore ion resistance of the battery at the first temperature and the conductivity of the electrolyte at the first temperature and the second temperature into the relationship equation between the pore ion resistance of the battery and the conductivity of the electrolyte, the pore ion resistance of the battery at the second temperature is calculated.

12. An impedance analysis device for a battery, characterized in that, The device includes a processor and a memory, the memory being used to store instructions, and the processor being used to read the instructions and execute the impedance analysis method according to any one of claims 1 to 8.

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