Nondestructive testing method for internal interface defects of phosphide all-solid-state battery

Abstract

The invention relates to the technical field of nondestructive testing, and discloses a nondestructive testing method for internal interface defects of a phosphide all-solid-state battery, which comprises the following steps: carrying out thermoacoustic coupling on a to-be-tested point by utilizing a periodically modulated thermal excitation source and confocal shear waves to generate a phase modulation acoustic signal carrying physical property information; performing dual-channel demodulation on the signal by using a lock-in amplifier, and synchronously extracting signal amplitude and phase delay; after finishing area scanning, respectively reconstructing an amplitude image and a phase delay image based on the data set; and finally, the two images are subjected to collaborative analysis to distinguish defect properties. According to the method, the thermoacoustic coupling signal is decomposed into two independent physical dimensions, namely the amplitude and the phase, and the collaborative analysis model of the corresponding image is established, so that chemical and structural interface defects with different physical causes and similar signal characteristics are effectively distinguished; and the problem of insufficient information dimension of a traditional single physical field detection method can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of nondestructive testing, and in particular to a nondestructive testing method for internal interface defects of a phosphide all-solid-state battery. Background Art

[0002] As the next generation of high-energy density and high-safety energy storage devices, the core advantage of phosphide all-solid-state batteries lies in the use of inorganic solid-state electrolytes to replace the flammable organic electrolytes in traditional lithium-ion batteries. During the preparation and circulation of the battery, various defects are easily generated at the internal interfaces formed between the electrodes and the electrolyte, as well as between the electrolyte grains. These microscopic defects are the key bottleneck that determines the overall performance, stability and life of the battery.

[0003] Currently, a variety of non-destructive testing technologies have been developed for the detection of internal structural defects in batteries. For example, ultrasonic microscopy based on acoustic impedance differences can effectively identify mechanical discontinuity defects such as cracks and voids inside the material, while infrared thermal imaging based on thermal properties is good at capturing abnormal temperature rise points caused by excessive local resistance or short circuits. At the same time, technologies such as X-ray computed tomography (CT) can also obtain the internal macroscopic structural morphology by performing three-dimensional reconstruction of the differences in the X-ray absorption coefficients of the material.

[0004] However, the interface defects of phosphide solid-state batteries are often not a single physical structural damage, but a complex product of the coupling and symbiosis of chemical defects and structural defects. For example, chemical side reactions at the interface will generate new phases with changed mechanical and thermal properties. The signal characteristics generated by this chemical change under a single physical field detection are highly similar to the signal characteristics generated by pure structural defects such as microcracks or poor contact. As a result, the existing detection methods that rely on a single information dimension such as acoustics, thermals or density can detect the existence of abnormal areas, but cannot effectively distinguish the fundamental physical properties of the defects. The ambiguity of this diagnostic information makes it difficult for researchers to accurately trace the cause of the defects, and it is even more difficult to provide clear guidance for battery failure mechanism analysis and manufacturing process optimization, which seriously restricts the reliability improvement and industrialization process of phosphide all-solid-state batteries. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a non-destructive detection method for internal interface defects of phosphide all-solid-state batteries, aiming to solve the problem that the existing technology has difficulty in distinguishing between chemical and structural interface defects with similar signal characteristics due to the single dimension of detection information.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A non-destructive detection method for internal interface defects of phosphide all-solid-state batteries, comprising the following steps: S1. Using a periodically modulated thermal excitation source and a confocal shear wave to perform thermoacoustic coupling at the point to be measured to generate a phase-modulated acoustic wave signal carrying the physical property information of the point; S2. Performing dual-channel quadrature demodulation on the phase-modulated acoustic wave signal using a lock-in amplifier to synchronously extract the signal amplitude and signal phase delay; S3. After completing the regional scan, reconstructing an amplitude image and a phase delay image based on the signal amplitude and phase delay data sets; S4. By performing collaborative comparative analysis on the amplitude image and the phase delay image, chemical defects and structural defects inside the battery are distinguished, and asymmetric excitation is introduced to analyze the anisotropy and potential expansion direction of the defects.

[0007] Preferably, the process of thermoacoustic coupling in step S1 is specifically as follows: The temperature oscillation generated by the periodically modulated thermal excitation source is utilized, and based on the characteristic that the shear modulus of the material at the point to be measured varies with temperature, the propagation speed of the shear wave passing through the point is synchronously modulated.

[0008] Preferably, the synchronous modulation method is: A laser beam whose intensity is modulated by an acousto-optic modulator is used as the thermal excitation source, and is focused on the point to be measured by an objective lens; At the same time, a shear wave transducer is driven to emit the shear wave, and the focus of the shear wave is made to coincide with the focus of the laser beam in space.

[0009] Preferably, the specific content of the dual-channel orthogonal demodulation in step S2 is: The reference signal for modulating the thermal excitation source is sent to the reference input terminal of the lock-in amplifier, and the phase-modulated acoustic wave signal is decomposed into an in-phase component in phase with the reference signal and an orthogonal component in phase with the reference signal.

[0010] Preferably, the signal amplitude is extracted by calculating the modulus of the vector sum of the in-phase component and the quadrature component, and the signal phase delay is extracted by calculating the inverse tangent of the quadrature component and the in-phase component.

[0011] Preferably, the area scanning in step S3 is performed as follows: According to the preset two-dimensional scanning path, the relative position of the measured point, the thermal excitation source and the shear wave is moved point by point, and the signal amplitude and signal phase delay of each point are collected in turn to form a data set corresponding to the coordinates of the two-dimensional scanning path.

[0012] Preferably, the reconstructed amplitude image and the phase delay image are implemented as follows: The signal amplitude at each scanning path coordinate in the data set is mapped to the pixel value of the corresponding position in the amplitude image matrix, and the signal phase delay at each scanning path coordinate is mapped to the pixel value of the corresponding position in the phase delay image matrix.

[0013] Preferably, the amplitude image matrix and the phase delay image matrix are fused into a composite image, wherein the pixel values ​​in the amplitude image matrix are used to define the brightness channel of the composite image, and the pixel values ​​in the phase delay image matrix are used to define the chrominance channel of the composite image.

[0014] Preferably, the collaborative comparative analysis in step S4 is performed as follows: By comparing the amplitude image and the phase delay image, areas showing local anomalies at the same spatial position in both images are identified as defect locations.

[0015] Preferably, the properties of the defect location are defined as follows: By comparing the relative prominence of the defect positions, the region with more significant abnormalities in the phase delay image is defined as a chemical defect, and the region with more significant abnormalities in the amplitude image is defined as a structural defect.

[0016] The present invention provides a nondestructive detection method for internal interface defects of phosphide all-solid-state batteries. It has the following beneficial effects: 1. The present invention uses a scheme of phase modulation of confocal shear waves using periodic thermal excitation to obtain a coupled signal that carries both thermal and mechanical properties. Compared with the existing method of relying on a single physical field such as ultrasound or infrared for detection, it helps to solve the problem of difficulty in distinguishing complex interface defects with similar physical causes and similar signal characteristics due to the single information dimension.

[0017] 2. The present invention establishes a collaborative analysis model of amplitude images and phase delay images, and determines the nature of defects based on the relative significance of abnormal signals, thereby effectively distinguishing between chemical defects and structural defects. Compared with the existing methods that can only locate defects but cannot effectively characterize them, this method helps to solve the problem of its lack of ability in defect tracing and failure mechanism analysis.

[0018] 3. The present invention proposes a solution for encoding amplitude and phase information into the brightness and chrominance channels of a composite image, respectively, to achieve a visualization effect that intuitively integrates multidimensional physical information. Compared with the existing analysis method of displaying multiple sets of data graphs in parallel, this solution helps to address the limitations of low analysis efficiency and difficulty in discovering potential correlations between different physical quantities.

[0019] 4. The present invention introduces an analytical approach of using asymmetric excitation to perform multi-angle detection on identified defects, which can reveal the anisotropy of defects and predict their potential expansion direction. Compared with existing technologies that can usually only provide static size and morphology information of defects, this helps to solve the problem of being unable to provide a dynamic development trend basis for battery life prediction and reliability assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the method flow of the present invention; Figure 2 Schematic diagram of the system structure of the present invention; Figure 3 Schematic diagram of the data processing and visualization process of the present invention; Figure 4 Schematic diagram of the defect collaborative analysis principle of the present invention. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Please see the attached Figure 1 -Attached Figure 4 The embodiment of the present invention provides a nondestructive detection method for internal interface defects of a phosphide all-solid-state battery, comprising the following steps: S1. Using a periodically modulated thermal excitation source and a confocal shear wave to perform thermoacoustic coupling at the point to be measured to generate a phase-modulated acoustic wave signal carrying the physical property information of the point; This step is based on a thermoacoustic coupling physical model. Its core is to use the sensitivity of the shear modulus of the material itself to temperature changes as a medium to convert thermal information into acoustic information.

[0023] Specifically, the thermoacoustic coupling process first uses a periodically modulated thermal excitation source to generate a small, periodic temperature oscillation field at the test point. The mathematical model of this temperature oscillation is expressed as follows: ; Where, is the instantaneous temperature of the test point changing with time, is the ambient reference temperature at that point, is the maximum temperature rise caused by the thermal excitation source, is the modulation angular frequency of the thermal excitation source, For time.

[0024] Shear modulus of materials such as phosphide solid electrolytes It is temperature In the range of small temperature rise, the functional relationship can be approximated as linear, and its mathematical model can be expressed as: ; Where, is the shear modulus corresponding to the instantaneous temperature, Base temperature The shear modulus under is the temperature coefficient of the shear modulus of the material, is the temperature coefficient of the shear modulus of the material, is the instantaneous temperature of the test point, The ambient reference temperature at which measurements are taken.

[0025] At the same time, a shear wave passes through the periodically heated test point, and the propagation speed of the shear wave in the medium is Determined by the shear modulus and material density, the physical relationship can be expressed as: ; Where, is the propagation velocity of the shear wave, is the shear modulus of the medium, is the density of the medium.

[0026] The combination of the above formulas reveals that the local shear wave propagation velocity at the test point is synchronously modulated due to the periodic oscillation of temperature. This process realizes the conversion of thermal information into acoustic information.

[0027] In order to realize the above physical process, the present invention provides a preferred implementation device structure. The specific method of synchronous modulation is to use a device including a thermal excitation component, a shear wave transceiver component and a confocal optical path system.

[0028] The thermal excitation component preferably uses a laser beam as a thermal excitation source, and further uses an acousto-optic modulator (AOM) to perform high-frequency sinusoidal or square wave intensity modulation on the output light intensity of the laser beam to generate periodic energy input.

[0029] The confocal optical system includes an objective lens. The laser beam modulated by the acousto-optic modulator is precisely focused on the point to be measured through the objective lens to form a local thermal excitation area of ​​the order of microns.

[0030] The shear wave transceiver assembly includes a shear wave transducer, which is responsible for emitting shear waves and making the focus of its acoustic field coincide with the focus of the laser beam in three-dimensional space to ensure maximum coupling efficiency between the thermal field and the acoustic field.

[0031] When the system is running, when the modulated laser beam and the shear wave act confocally at the point to be measured, the propagation phase of the shear wave passing through the area will be synchronously modulated due to the periodic change of the propagation speed, and finally a phase-modulated acoustic wave signal carrying comprehensive physical information such as the point is formed.

[0032] Finally, the generated phase-modulated acoustic wave signal is collected by a receiving transducer (which can be the same device as the transmitting transducer) and used as the input signal for step S2. This signal fully carries the thermal-mechanical coupling characteristics of the test point, providing raw data with a high signal-to-noise ratio for the subsequent distinction between chemical defects and structural defects, enabling precise analysis of defects.

[0033] In this embodiment, by synchronously modulating the periodic changes in the material shear modulus caused by thermal excitation onto the confocal shear wave phase, the local thermal-mechanical coupling characteristic parameters of the test point are accurately converted into high signal-to-noise ratio acoustic wave signals, providing a reliable data basis for subsequent defect analysis.

[0034] S2. Use a lock-in amplifier to perform dual-channel orthogonal demodulation on the phase-modulated acoustic wave signal and synchronously extract the signal amplitude and signal phase delay; Specifically, the core of this step is to use phase-locked amplification technology to send the phase-modulated acoustic wave signal output by the receiving transducer in step S1 to the signal input end of a phase-locked amplifier. This signal is a weak signal containing the thermal-mechanical coupling information of the test point.

[0035] At the same time, in order to provide an accurate phase reference for the demodulation process, the periodic reference signal used to modulate the thermal excitation source (for example, driving the acousto-optic modulator) is synchronously sent to the reference input of the phase-locked amplifier.

[0036] The lock-in amplifier internally performs dual-channel quadrature demodulation, which decomposes the phase-modulated acoustic wave signal into an in-phase component that is in phase with the reference signal and a quadrature component that is orthogonal to the reference signal (i.e., 90 degrees out of phase).

[0037] After obtaining the in-phase component and the quadrature component, the final required signal amplitude and signal phase delay can be extracted through mathematical operations.

[0038] The signal amplitude is extracted by calculating the modulus of the vector sum of the in-phase component and the orthogonal component. Its mathematical model can be expressed as: ;; ; Where, is the extracted signal amplitude, is the value of the in-phase component, is the value of the orthogonal component.

[0039] The above signal amplitude It mainly reflects the overall efficiency of thermal-acoustic coupling.

[0040] The signal phase delay is extracted by calculating the arc tangent of the quadrature component and the in-phase component. The mathematical model can be expressed as: ; Where, is the extracted signal phase delay, are the values ​​of the orthogonal components, is the value of the in-phase component.

[0041] The above signal phase delay It mainly reflects the time delay caused by processes such as thermal diffusion.

[0042] Finally, the above demodulation and calculation process is performed for each point to be measured on the scanning path, thereby obtaining two independent values ​​of signal amplitude and signal phase delay corresponding to each spatial coordinate point.

[0043] In this embodiment, by performing dual-channel orthogonal demodulation on the phase-modulated acoustic wave signal and performing vector operations based on its in-phase and quadrature components, high-precision synchronous extraction of two core physical quantities, signal amplitude and signal phase delay, is achieved. This provides independent and physically clear data sources for the subsequent construction of dual-channel images and the differentiation of internal defects of different properties.

[0044] S3, after completing the regional scan, reconstructing an amplitude image and a phase delay image based on the signal amplitude and phase delay data sets; Specifically, this step first requires performing an area scan to acquire a dataset.

[0045] The execution method is: according to a preset two-dimensional scanning path (for example, line-by-line raster scanning), the relative position of the test point and the confocal point of the thermal excitation source and shear wave is moved point by point through a high-precision translation stage or other device.

[0046] At each coordinate point of the scanning path, the operations of steps S1 and S2 are fully executed, that is, thermoacoustic coupling excitation and phase-locked demodulation are performed, so as to sequentially collect and record the signal amplitude and signal phase delay of the point.

[0047] After completing the scanning of the entire preset area, a data set that completely corresponds to the coordinates of the two-dimensional scanning path can be formed. The data set contains two independent sets of physical quantity data associated with the spatial position.

[0048] Then, the amplitude image and phase delay image are reconstructed based on the data set. The reconstruction is achieved by mapping the signal amplitude at each scan path coordinate in the data set to the pixel value at the corresponding position in the amplitude image matrix.

[0049] At the same time, the signal phase delay at each scanning path coordinate is mapped to the pixel value of the corresponding position in a phase delay image matrix, thereby generating two grayscale images that can independently display the spatial distribution of physical quantities.

[0050] Furthermore, in order to present two physical properties simultaneously and intuitively in one image, the amplitude image matrix and the phase delay image matrix can be fused into a composite image.

[0051] In the fusion process, the pixel values ​​in the magnitude image matrix are used to define the luminance channel (Luminance Channel) of the composite image, and the pixel values ​​in the phase delay image matrix are used to define the chroma channel (Chroma / HueChannel) of the composite image.

[0052] Finally, the composite image is output, in which changes in signal amplitude are reflected as changes in image brightness, while changes in signal phase delay are reflected as changes in color, allowing abnormal areas with different physical properties to be clearly observed together.

[0053] In this embodiment, the detection area is scanned point by point, and the collected amplitude and phase data sets are mapped to two image matrices respectively. The two matrices are further fused into a composite image encoded using brightness and color. This realizes the conversion of discrete, multi-dimensional physical quantity data into a centralized, information-rich visualization carrier, providing a basis for subsequent efficient and intuitive collaborative defect analysis.

[0054] S4. By performing collaborative comparative analysis of amplitude images and phase delay images, chemical defects and structural defects inside the battery can be distinguished, and asymmetric excitation is introduced to analyze the anisotropy and potential expansion direction of the defects.

[0055] This step is the core link for the present invention to ultimately achieve defect characterization and representation. Its purpose is to interpret the image data generated in step S3, thereby locating the defects, defining their physical causes, and evaluating their development trends.

[0056] First, a collaborative contrast analysis is performed to identify the defect location by comparing the magnitude image with the phase delay image.

[0057] Specifically, through image processing algorithms, local abnormal areas where pixel values ​​at the same spatial position in both images show significant differences compared with their neighborhoods are identified as candidate defect locations.

[0058] After the defect location is identified, the nature of the defect at that location needs to be defined. The core of this definition method is to compare the relative significance of the anomaly shown by the defect location in the amplitude image and the phase delay image.

[0059] In order to objectively quantify this “relative significance”, the pixel points at each defect position can be Calculate its normalized anomaly score in two image channels. An exemplary mathematical model is as follows: ; Where, is the anomaly significance score of the amplitude channel, is the magnitude image at coordinates The pixel value at is the average pixel value of the global or local background of the amplitude image, is the standard deviation of the pixel values ​​in the corresponding background area.

[0060] ; Where, is the abnormal significance score of the phase delay channel, The phase delay image is in coordinates The pixel value at is the average pixel value of the global or local background of the phase-delay image, is the standard deviation of the pixel values ​​in the corresponding background area.

[0061] Then, based on the above significance scores, a discriminant function can be used to define the defect type. The area with more significant abnormalities in the phase delay image is defined as a chemical defect; On the contrary, the area with more obvious abnormality in the amplitude image is defined as a structural defect.

[0062] Furthermore, in order to analyze the anisotropy and potential extension direction of the identified defects, the present method can also introduce asymmetric excitation analysis. In this process, the circular focused thermal excitation spot in step S1 can be adjusted to an elliptical shape, and the identified defect position can be repeatedly measured at multiple angles by rotating the azimuth angle of the elliptical spot.

[0063] By analyzing the changing patterns of signal responses (amplitude and phase) at different excitation angles, it is possible to determine whether the defect is directional in physical properties and infer its most likely expansion direction.

[0064] In this embodiment, by collaboratively analyzing amplitude and phase images and introducing standardized anomaly scores to quantify the relative significance of defects, it is possible to accurately distinguish chemical defects from structural defects in mixed signals. Anisotropic information of defects can be further obtained through asymmetric excitation, thereby providing a comprehensive and quantitative diagnostic basis for failure analysis and life prediction of all-solid-state batteries.

[0065] 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 nondestructive detection method for internal interface defects of phosphide all-solid-state batteries, characterized in that: The following steps are involved: S1. Using a periodically modulated thermal excitation source and a confocal shear wave to perform thermoacoustic coupling at the point to be measured to generate a phase-modulated acoustic wave signal carrying the physical property information of the point; S2. Performing dual-channel quadrature demodulation on the phase-modulated acoustic wave signal using a lock-in amplifier to synchronously extract the signal amplitude and signal phase delay; S3. After completing the regional scan, reconstructing an amplitude image and a phase delay image based on the signal amplitude and phase delay data sets; S4. By performing collaborative comparative analysis on the amplitude image and the phase delay image, chemical defects and structural defects inside the battery are distinguished, and asymmetric excitation is introduced to analyze the anisotropy and potential expansion direction of the defects.

2. The nondestructive detection method for internal interface defects of a phosphide all-solid-state battery according to claim 1, characterized in that: The process of thermoacoustic coupling in step S1 is specifically as follows: The temperature oscillation generated by the periodically modulated thermal excitation source is utilized, and based on the characteristic that the shear modulus of the material at the point to be measured varies with temperature, the propagation speed of the shear wave passing through the point is synchronously modulated.

3. The nondestructive detection method for internal interface defects of a phosphide all-solid-state battery according to claim 2, characterized in that: The synchronous modulation method is: A laser beam whose intensity is modulated by an acousto-optic modulator is used as the thermal excitation source, and is focused on the point to be measured by an objective lens; At the same time, a shear wave transducer is driven to emit the shear wave, and the focus of the shear wave is made to coincide with the focus of the laser beam in space.

4. The nondestructive detection method for internal interface defects of a phosphide all-solid-state battery according to claim 1, characterized in that: The specific contents of the dual-channel orthogonal demodulation in step S2 are: The reference signal for modulating the thermal excitation source is sent to the reference input terminal of the lock-in amplifier, and the phase-modulated acoustic wave signal is decomposed into an in-phase component in phase with the reference signal and an orthogonal component in phase with the reference signal.

5. The nondestructive detection method for internal interface defects of a phosphide all-solid-state battery according to claim 4, characterized in that: The signal amplitude is extracted by calculating the modulus of the vector sum of the in-phase component and the quadrature component, and the signal phase delay is extracted by calculating the inverse tangent of the quadrature component and the in-phase component.

6. The nondestructive detection method for internal interface defects of a phosphide all-solid-state battery according to claim 1, characterized in that: The area scan in step S3 is performed as follows: According to the preset two-dimensional scanning path, the relative position of the measured point, the thermal excitation source and the shear wave is moved point by point, and the signal amplitude and signal phase delay of each point are collected in turn to form a data set corresponding to the coordinates of the two-dimensional scanning path.

7. The nondestructive detection method for internal interface defects of a phosphide all-solid-state battery according to claim 6, characterized in that: The reconstructed amplitude image and the phase delay image are realized by: The signal amplitude at each scanning path coordinate in the data set is mapped to the pixel value of the corresponding position in the amplitude image matrix, and the signal phase delay at each scanning path coordinate is mapped to the pixel value of the corresponding position in the phase delay image matrix.

8. The nondestructive detection method for internal interface defects of a phosphide all-solid-state battery according to claim 7, characterized in that: The amplitude image matrix and the phase delay image matrix are fused into a composite image, wherein the pixel values ​​in the amplitude image matrix are used to define the luminance channel of the composite image, and the pixel values ​​in the phase delay image matrix are used to define the chrominance channel of the composite image.

9. The nondestructive detection method for internal interface defects of a phosphide all-solid-state battery according to claim 1, characterized in that: The collaborative comparative analysis method in step S4 is: By comparing the amplitude image and the phase delay image, areas showing local anomalies at the same spatial position in both images are identified as defect locations.

10. The non-destructive detection method for internal interface defects of a phosphide all-solid-state battery according to claim 9, characterized in that: The nature of the defect location is defined as follows: By comparing the relative prominence of the defect positions, the region with more significant abnormalities in the phase delay image is defined as a chemical defect, and the region with more significant abnormalities in the amplitude image is defined as a structural defect.

Images