All-solid-state battery health state detection method based on electrochemical impedance spectroscopy

Abstract

The invention relates to the technical field of battery detection, and discloses an all-solid-state battery health state detection method based on electrochemical impedance spectroscopy. The method comprises the following steps: applying a dynamic mechanical modulation signal to a selected area on the surface of the all-solid-state battery, and simultaneously performing broadband electrochemical impedance spectroscopy measurement to obtain a time domain impedance signal; a multi-harmonic analysis is performed on the time-domain impedance signal to obtain at least one zero-order response, one-order response, and high-order harmonic response, and the state of health of the battery is evaluated based on these responses. According to the method, the zero-order response is associated with the conventional impedance, the first-order response is associated with the interface flexibility, and the high-order harmonic response is associated with the structural defect, so that the technical problems that different physical recession modes are difficult to distinguish and early mechanical structural risks cannot be effectively identified in the prior art are solved; the early failure risk of the battery can be identified, the local defect can be spatially positioned, and the accuracy, depth and foresight of health state assessment are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery detection, and in particular to a method for detecting the health status of an all-solid-state battery based on electrochemical impedance spectroscopy. Background Art

[0002] All-solid-state batteries, which use solid-state electrolytes instead of the flammable organic electrolytes found in traditional lithium-ion batteries, offer significant advantages in energy density and safety and are considered a key development direction for next-generation energy storage technologies. To ensure the reliability and safety of all-solid-state batteries in practical applications, it is crucial to develop detection technologies that can accurately assess their state of health (SOH) and identify early failure risks.

[0003] Electrochemical impedance spectroscopy (EIS) is a non-destructive electrochemical characterization technique that can obtain rich information about electrode process dynamics, charge transfer, and material transport by measuring the impedance response of the battery over a wide frequency range. Therefore, it is widely used in the research and diagnosis of battery systems.

[0004] However, direct application of traditional electrochemical impedance spectroscopy (EIS) technology to the health assessment of all-solid-state batteries presents inherent technical limitations. The performance degradation and failure modes of all-solid-state batteries differ significantly from those of traditional liquid electrolyte batteries. Under long-term cycling or external stress, the solid-solid interface within them is susceptible to mechanical and structural degradation, such as contact loss, interfacial delamination, or microcrack propagation. Traditional EIS measurement methods obtain the averaged electrochemical response of the entire battery. When local structural defects first emerge, the weak impedance signal they generate is easily masked by the overall response of the battery's larger, healthy regions, resulting in insufficient sensitivity for detecting local defects.

[0005] In addition, this method is also insufficient in distinguishing impedance changes from different physical sources. For example, the physical root of the measured increase in interfacial impedance stems from the purely electrochemical process of thickening the solid electrolyte interface (SEI) film at the interface, and from the mechanical process of increased contact impedance due to weakened physical contact between the electrode and the electrolyte. Traditional electrochemical impedance spectroscopy technology has difficulty in effectively decoupling these two different types of decay modes, resulting in ambiguity in the judgment of the true health status of the battery. Therefore, this technology can often only observe significant impedance changes when structural damage has developed to a more serious level, and its early warning ability is limited in identifying risks such as early interfacial contact deterioration as a precursor to serious failure. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides an all-solid-state battery health status detection method based on electrochemical impedance spectroscopy, which solves the problem that the existing all-solid-state battery health status detection method based on electrochemical impedance spectroscopy is difficult to effectively distinguish the impedance changes caused by different physical and chemical processes inside the battery, especially the inability to effectively identify and locate early risks caused by interface contact loss and key mechanical structural degradation of microcracks, thereby affecting the accuracy and foresight of battery health status assessment.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: a method for detecting the health status of an all-solid-state battery based on electrochemical impedance spectroscopy, the method comprising: applying a dynamic mechanical modulation signal to a selected area on the surface of the all-solid-state battery; While applying the dynamic mechanical modulation signal, performing broadband electrochemical impedance spectroscopy measurement on the all-solid-state battery to obtain a time-domain impedance signal; Performing multiharmonic analysis on the time-domain impedance signal to obtain at least a zero-order response, a first-order response, and a higher-order harmonic response; The health status of the all-solid-state battery is evaluated based on the zero-order response, first-order response and high-order harmonic response.

[0008] Preferably, the method further includes the step of dividing the surface of the all-solid-state battery into a plurality of grid units before applying the dynamic mechanical modulation signal. Accordingly, the step of applying the dynamic mechanical modulation signal is specifically: sequentially selecting the grid units as the selected areas and applying the dynamic mechanical modulation signal thereto. Through this scanning detection method, the health status information of different areas of the all-solid-state battery can be obtained, thereby overcoming the technical defect of traditional electrochemical impedance spectroscopy measurement that cannot identify local defects due to signal averaging.

[0009] Preferably, the dynamic mechanical modulation signal is a sinusoidal mechanical modulation signal, which makes the instantaneous pressure of the selected area The following relationship is satisfied: in, is a static preload pressure, is the amplitude of the dynamic pressure modulation, is the angular frequency of dynamic pressure modulation, For time.

[0010] Preferably, by introducing a controllable dynamic mechanical micro-perturbation, the changes in the mechanical structural characteristics of the battery are converted into a measurable electrochemical impedance response component that is strictly phase-locked with the mechanical modulation signal. Specifically, the impedance response of a healthy, well-contacted solid-solid interface to small pressures tends to be linear, so its time-domain impedance signal primarily contains a fundamental frequency component (i.e., a first-order response) that is identical to the mechanical modulation frequency. However, when structural defects such as microcracks, voids, or poor particle contact exist at the interface, the periodic pressure causes asymmetric changes in the contact state (e.g., crack "opening and closing"), thereby introducing higher-order harmonic components (i.e., higher-order harmonic responses) into the time-domain impedance signal that are multiples of the mechanical modulation frequency.

[0011] Preferably, the step of performing multiharmonic analysis is specifically for electrochemical frequency , calculated by the following formula Order mechanical related impedance : in, For the location The measured time domain impedance signal, For time, is the harmonic order, is the angular frequency of the dynamic mechanical modulation signal, is the modulation period, is the total number of periods used for integration, is an imaginary unit. When , the calculation result corresponds to the zero-order response, characterizing the time-averaged impedance of the region; when When , the calculation result corresponds to the first-order response, which characterizes the linear sensitivity of the impedance of the region to the pressure; when When , the calculation result corresponds to the high-order harmonic response, which characterizes the nonlinear sensitivity of the impedance in this area to pressure.

[0012] Preferably, the present invention can achieve multi-dimensional evaluation of battery health status by analyzing different order responses.

[0013] Preferably, as an optional technical solution of the present invention, the evaluation step includes: generating a conventional impedance spectrum based on the zero-order response; generating an interface compliance spectrum based on the first-order response, the signal intensity of which is related to the tightness and elasticity of the interface contact; generating a structural defect spectrum based on the high-order harmonic response, the signal intensity of which is directly related to interface microcracks and layered structural defects.

[0014] The present invention provides a method for detecting the health status of all-solid-state batteries based on electrochemical impedance spectroscopy. It has the following beneficial effects: 1. The present invention can effectively distinguish impedance changes caused by different physical mechanisms by performing multiharmonic analysis on the time-domain impedance signal. Specifically, the present invention uses first-order responses to characterize linear and elastic changes in interface contact tightness, while using higher-order harmonic responses to characterize nonlinear changes caused by the opening and closing of microcracks. This distinction enables the present method to identify the specific physical source of the impedance increase, thereby resolving the technical problem of easy confusion between different decay modes in the prior art and improving the accuracy of the diagnostic results.

[0015] 2. This invention can identify the risk of premature failure of all-solid-state batteries. By analyzing the first-order response to generate an interface compliance map, the present invention can detect abnormal signals at the stage where the battery interface only shows weakened bonding but has not yet developed significant structural damage. This ability to identify early risks makes battery health assessment more proactive and facilitates early intervention before serious performance degradation or structural damage occurs.

[0016] 3. The present invention enables spatial localization of internal battery defects. By dividing the battery surface into multiple grid cells and performing scanning inspection on selected areas, the present invention can generate spatially resolved conventional impedance maps, interface compliance maps, and structural defect maps. This enables the method to pinpoint the specific spatial origin of abnormal signals, overcoming the limitation of traditional electrochemical impedance spectroscopy measurements, which cannot locate local defects due to obtaining a global average signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of the all-solid-state battery health status detection system of the present invention; Figure 2 This is a flow chart of the all-solid-state battery health status detection method of the present invention. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the specification of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] In order to better understand the present invention, the above contents are described in detail below in conjunction with specific embodiments.

[0020] Please refer to the attached Figure 1 , the system is used to perform an all-solid-state battery health status detection method based on electrochemical impedance spectroscopy.

[0021] The system includes a dynamic mechanical modulation unit, an impedance measurement unit, and a central control and analysis unit. The dynamic mechanical modulation unit contacts the surface of an all-solid-state battery under test and is electrically connected to the central control and analysis unit. The impedance measurement unit is electrically connected to the positive and negative electrodes of the all-solid-state battery under test and is also electrically connected to the central control and analysis unit.

[0022] Specifically, the dynamic mechanical modulation unit is used to apply controllable mechanical pressure containing static and dynamic components to a specific area on the surface of the all-solid-state battery. The dynamic mechanical modulation unit includes a micro piezoelectric actuator array and a drive controller. The micro piezoelectric actuator array consists of multiple independently addressable actuator units. The array of actuators is arranged in a matrix and packaged on a flexible substrate, enabling it to adhere closely to the surface of the all-solid-state battery being tested. A drive controller communicates with a central control and analysis unit, receiving its instructions to precisely control the drive voltage of each actuator unit in the array, thereby applying independent mechanical pressure to selected areas of the battery surface.

[0023] The impedance measurement unit is used to measure broadband electrochemical impedance spectroscopy (EIS) of all-solid-state batteries. It is an electrochemical workstation with a wide frequency sweep range and an external trigger input port for receiving a synchronous trigger signal from the central control and analysis unit. This ensures precise synchronization between the acquisition of the impedance spectrum and the application of the signal by the dynamic mechanical modulation unit.

[0024] The central control and analysis unit coordinates the overall operation of the control system and executes core data processing and analysis algorithms. This unit is a computer or dedicated digital signal processor loaded with specific software modules. Its internal functional modules include a coordinated control module, a signal processing module, and a state assessment module.

[0025] The collaborative control module manages the timing of the entire testing process. Based on a pre-set program, it sends instructions to the drive controller, controlling the micropiezoelectric actuator array to apply static preload pressure and dynamic mechanical modulation signals to specific selected areas. Simultaneously, it sends synchronous trigger signals to the impedance measurement unit to start and stop impedance spectrum measurements.

[0026] The signal processing module is responsible for processing the raw measurement data received from the impedance measurement unit. The raw measurement data is a time domain impedance signal ,in is the spatial coordinate of the selected area, is the angular frequency of the electrochemical scan, The signal processing module performs multiharmonic analysis on the time domain impedance signal to calculate the k-order mechanical related impedance The calculation is done using the following formula: in, is the harmonic order, which is a non-negative integer; is the angular frequency of the dynamic mechanical modulation signal; is the modulation period; is the total number of mechanical modulation cycles used for integration, a positive integer; is an imaginary unit. By this calculation, the zero-order response can be separated , first-order response and higher-order harmonic response .

[0027] The state assessment module is responsible for performing a final health assessment based on the output of the signal processing module. Based on the calculated response data of each order, this module reconstructs spatially resolved conventional impedance spectra, interface compliance spectra, and structural defect spectra at the selected characteristic electrochemical frequency. These spectra are then comprehensively analyzed to output an assessment of the health status of the all-solid-state battery.

[0028] Refer to the attached Figure 2 , this method can be used by Figure 1 Specifically, the method may include the following steps: The system is initialized by placing the all-solid-state battery under test on the test platform. The dynamic mechanical modulation unit's micro-piezoelectric actuator array is mounted and attached to the surface of the all-solid-state battery under test. Subsequently, the impedance measurement unit's measuring electrodes are electrically connected to the positive and negative terminals of the all-solid-state battery.

[0029] Apply static preload, the central control and analysis unit controls the dynamic mechanical modulation unit so that all actuator units in its micro piezoelectric actuator array simultaneously apply a uniform and constant static preload pressure to the entire surface to be tested of the all-solid-state battery This step is to establish sufficient and consistent physical contact between the micro piezoelectric actuator array and the battery surface. At the same time, the central control and analysis unit logically divides the battery surface into corresponding micro piezoelectric actuator arrays. A spatial grid, where each grid cell is represented by a coordinate Uniquely identify.

[0030] Perform scanning local dynamic modulation, the central control and analysis unit selects the grid cells in the spatial grid in sequence according to the preset scanning path As the current selected area. For the selected area The central control and analysis unit controls the corresponding actuator unit in the dynamic mechanical modulation unit to maintain the static preload pressure. On the basis of the superposition of the sinusoidal mechanical modulation signal, the instantaneous pressure of the selected area is The following relationship is satisfied: in, For time, is the amplitude of the dynamic pressure modulation, is the angular frequency of dynamic pressure modulation. During this period, the actuator units corresponding to the remaining unselected grid units maintain the output of a constant static preload pressure .

[0031] Perform synchronous impedance spectroscopy measurement on the selected area During the entire process of applying the dynamic mechanical modulation signal, the central control and analysis unit sends a synchronous trigger signal to the impedance measurement unit through its collaborative control module. After receiving the signal, the impedance measurement unit immediately performs a complete broadband electrochemical impedance spectroscopy scan of the all-solid-state battery, thereby obtaining a time-domain impedance signal modulated by the local mechanical state and varying with time. ,in is the angular frequency of the electrochemical scan. This measurement lasts for several complete cycles of the mechanical modulation to collect enough data samples.

[0032] Perform multiharmonic analysis on the selected region of the acquired impedance spectrum during the simultaneous impedance spectroscopy measurement. and electrochemical frequency The corresponding time domain impedance signal The signal processing module of the central control and analysis unit performs multi-harmonic analysis. Order mechanical related impedance This is achieved by separating the response components that are strictly related to the mechanical modulation frequency and its harmonics from the original signal.

[0033] Reconstructing the multi-dimensional characteristic map, after completing the scanning and multi-harmonic analysis of all grid units, the state evaluation module of the central control and analysis unit, based on the calculated response data of each order, At least three two-dimensional characteristic maps are generated: conventional impedance map , the values ​​of each point are determined by the zero-order response The modulus value of the interface is determined; the interface flexibility diagram , the values ​​of each point are determined by the first-order response Determination of the modulus value; Structural defect map , whose values ​​at each point are determined by the second-order or higher-order harmonic response, such as The modulus value is determined.

[0034] To conduct comprehensive health status assessment, the status assessment module conducts collaborative analysis on the multidimensional feature maps generated in the reconstructed multidimensional feature maps. This analysis includes but is not limited to comparing the same spatial position By analyzing the signal strength on conventional impedance maps, interface compliance maps, and structural defect maps, and their relative strength, it is possible to distinguish whether a local area of ​​the all-solid-state battery is in a uniform aging state, at early risk of weakened interface bonding, or has already formed a structural defect, ultimately producing a comprehensive assessment report on the health status of the all-solid-state battery.

[0035] After receiving the response data of each order calculated by the signal processing module, the state assessment module performs a comprehensive health state assessment. The assessment process is to perform spatial position comparison and logical analysis on the three feature maps generated in the step of reconstructing the multi-dimensional feature map. The corresponding signal strengths on the three maps can be used to classify the local decay pattern at that location. The following is the analysis process for three typical scenarios: Scenario 1: Uniform Electrochemical Aging: When the conventional impedance spectrum shows a uniform increase in overall signal intensity, and the interface compliance spectrum and structural defect spectrum do not show significant signal enhancement in all regions, the state assessment module determines that the all-solid-state battery is undergoing a uniform electrochemical aging process. This pattern corresponds to a general increase in the bulk resistance of internal battery materials (such as electrolytes or electrode active materials), or uniform growth of the solid electrolyte interface (SEI) film, without localized mechanical and structural degradation.

[0036] Scenario 2: Local interface contact deterioration (early risk) when in a specific area In a typical impedance spectrum, a slight signal increase might be observed. However, the interface flexibility spectrum shows a significant signal increase (i.e., a "hotspot") in this region. Meanwhile, when the signal intensity of the structural defect spectrum in this region remains at a low background level, the condition assessment module determines that this region presents an early risk of interface contact deterioration. This is because the enhanced first-order response directly indicates an increase in the mechanical compliance of the interface at that location—in other words, a weakening of the interface bonding force or a slight loosening that has not yet evolved into nonlinear, irreversible structural damage. The identification of this scenario demonstrates the present invention's ability to provide early warning of failure risks.

[0037] Scenario 3: Local structural defects are formed in a specific area When the conventional impedance spectrum, interface compliance spectrum, and structural defect spectrum all show significant signal enhancement, the state assessment module determines that a clear structural defect has formed in that area. In this scenario, the enhancement of the first-order response indicates poor interface contact at that location, while the significant enhancement of the second-order and higher-order harmonic responses provides direct evidence of asymmetric mechanical behavior such as microcracks, interface delamination, or electrode particle pulverization in that area. The "hot spots" on the structural defect spectrum can be used to accurately locate the structural defect.

[0038] Through the above-mentioned collaborative analysis process, the present invention can not only evaluate the overall performance degradation level of all-solid-state batteries, but also identify and locate local degradation patterns of different properties, thereby providing comprehensive, in-depth and refined data support for battery health status management, life prediction and safety assessment.

[0039] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting the health status of all-solid-state batteries based on electrochemical impedance spectroscopy, characterized in that: The following steps are involved: applying a dynamic mechanical modulation signal to a selected area on the surface of the all-solid-state battery; While applying the dynamic mechanical modulation signal, performing broadband electrochemical impedance spectroscopy measurement on the all-solid-state battery to obtain a time-domain impedance signal; Performing multiharmonic analysis on the time-domain impedance signal to obtain at least a zero-order response, a first-order response, and a higher-order harmonic response; The health status of the all-solid-state battery is evaluated based on the zero-order response, first-order response and high-order harmonic response.

2. The all-solid-state battery health status detection method based on electrochemical impedance spectroscopy according to claim 1, characterized in that: The step of applying a dynamic mechanical modulation signal to the selected area on the surface of the all-solid-state battery divides the surface of the all-solid-state battery into multiple grid units, selects the grid units in turn as the selected area, and applies the dynamic mechanical modulation signal to it to realize scanning detection of the all-solid-state battery.

3. The all-solid-state battery health status detection method based on electrochemical impedance spectroscopy according to claim 1, characterized in that: The steps of performing multiharmonic analysis include: , calculated by the following formula Order mechanical related impedance : in, For the location The measured time domain impedance signal, For time, is the harmonic order is the angular frequency of the dynamic mechanical modulation signal, is the modulation period, is the total number of periods used for integration, is an imaginary unit; corresponds to the zero-order response, corresponds to the first-order response, , which corresponds to the high-order harmonic response.

4. The method for detecting the health status of an all-solid-state battery based on electrochemical impedance spectroscopy according to claim 1, characterized in that: The step of evaluating the health status of the all-solid-state battery includes: reconstructing at least two characteristic maps representing different health status dimensions based on at least two of the zero-order response, the first-order response and the higher-order harmonic response.

5. The all-solid-state battery health status detection method based on electrochemical impedance spectroscopy according to claim 4, characterized in that: The step of reconstructing at least two characteristic spectra includes: generating a conventional impedance spectrum based on the zero-order response, generating an interface compliance spectrum based on the first-order response to characterize the tightness of interface contact, and generating a structural defect spectrum based on the high-order harmonic response to characterize the presence of structural defects.

6. The all-solid-state battery health status detection method based on electrochemical impedance spectroscopy according to claim 1, characterized in that: The step of evaluating the health status of the all-solid-state battery also includes: collaboratively analyzing conventional impedance spectra, interface compliance spectra and structural defect spectra, and classifying the local degradation mode of the all-solid-state battery by comparing the signal intensity of the same area on different spectra.

7. The all-solid-state battery health status detection method based on electrochemical impedance spectroscopy according to claim 1, characterized in that: The dynamic mechanical modulation signal is a sinusoidal mechanical modulation signal.

8. The method for detecting the health status of all-solid-state batteries based on electrochemical impedance spectroscopy according to claim 1, characterized in that: The dynamic mechanical modulation signal is applied to the surface of the all-solid-state battery through a micro piezoelectric actuator array.

9. The all-solid-state battery health status detection method based on electrochemical impedance spectroscopy according to claim 1, characterized in that: The step of applying a dynamic mechanical modulation signal causes the instantaneous pressure of the selected area to The following relationship is satisfied: , in, is a static preload pressure, is the amplitude of dynamic pressure modulation, is the angular frequency of dynamic pressure modulation, For time.

10. The all-solid-state battery health status detection method based on electrochemical impedance spectroscopy according to claim 5, characterized in that: The evaluation step can distinguish between the early risk of weakened interfacial bonding strength of the all-solid-state battery and the structural defects that have already formed; wherein, the signal enhancement of the interface flexibility map indicates the early risk, and the signal enhancement of the structural defect map indicates the structural defects that have already formed.

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