Method for measuring cross-scale strain of electrode structure in electrochemical environment

Abstract

The invention discloses an electrode structure cross-scale strain measurement method in an electrochemical environment. The method comprises the following steps: preparing and assembling a button cell with an optical window; carrying out macroscopic in-plane strain measurement on the electrode in the electrochemical process; carrying out electrode microscopic three-dimensional strain measurement in an electrochemical process; and data normalization processing is carried out based on the macroscopic in-plane strain measurement of the electrode and the microscopic three-dimensional strain measurement of the electrode to obtain the cross-scale strain evolution information of the electrode structure in the electrochemical environment. According to the invention, in-situ integration of macroscopic digital image correlation and microscopic X-ray diffraction and Raman spectrum measurement is realized, a cross-scale strain measurement platform based on a unified test piece and a unified electrochemical process is constructed, and the problem that cross-scale measurement cannot be synchronized is effectively solved. Compared with existing single-scale strain measurement, the method has the advantages that the electrode structure strain information of the electrode under macroscopic and microscopic scales can be obtained, and the continuity and comprehensiveness of strain measurement data are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of multi-field coupling such as force-electricity-chemistry, and particularly relates to a method for measuring the cross-scale strain of an electrode structure in an electrochemical environment. Background Art

[0002] With the rapid development of new energy technologies, lithium-ion batteries are increasingly widely used in the energy storage field. During the charge and discharge process of lithium-ion batteries, the electrodes undergo complex lithium insertion / extraction reactions and structural changes, accompanied by multi-scale strain responses. These multi-scale strain evolutions are closely related to the capacity attenuation, cycle life, and safety of the batteries. Therefore, revealing the evolution characteristics of macroscopic and microscopic strains in the electrode structure during the electrochemical process is of great significance for improving the performance of lithium-ion batteries.

[0003] Currently, for the detection of deformation, there are technologies such as digital image correlation (DIC), X-ray diffraction (XRD), and Raman spectroscopy. Among them, the DIC technology is suitable for measuring macroscopic-scale strains and reflecting the strain characteristics on the electrode surface; the XRD and Raman spectroscopy technologies are suitable for detecting micro-scale information and providing crystal structure information of the electrode material. At present, it is still difficult to achieve the comprehensive characterization of the cross-scale strain of the electrode structure in an electrochemical environment.

[0004] Therefore, there is an urgent need to develop a method that can realize the in-situ comprehensive measurement of macroscopic and microscopic strains to deeply explore the cooperative characteristics of the cross-scale mechanical behavior of the electrode structure during the electrochemical process, providing experimental basis and technical support for battery structure optimization and battery performance improvement. Summary of the Invention

[0005] The present invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a method for measuring the cross-scale strain of an electrode structure in an electrochemical environment.

[0006] The technical solution of the present invention is: a method for measuring the cross-scale strain of an electrode structure in an electrochemical environment, including the following steps:

[0007] A. Prepare and assemble a button battery with an optical window;

[0008] B. Measure the in-plane macroscopic strain of the electrode during the electrochemical process;

[0009] C. Measure the three-dimensional microscopic strain of the electrode during the electrochemical process;

[0010] D. Based on the measurement of the in-plane macroscopic strain of the electrode and the measurement of the three-dimensional microscopic strain of the electrode, perform data normalization processing to obtain the cross-scale strain evolution information of the electrode structure in the electrochemical environment.

[0011] Furthermore, for step A of preparing and assembling a button battery with an optical window, the specific process is as follows:

[0012] First, a commercial CR2032 button battery is used as the object of improvement;

[0013] Then, a laser hole is drilled in the center of the positive electrode case of the button battery;

[0014] Next, the laser hole is sealed with a transparent polyimide PI film;

[0015] Finally, a layer of open-cell nickel foam is added between the electrode to be measured and the positive electrode case inside the battery case.

[0016] Furthermore, the electrode to be measured uses a copper mesh as the substrate, fluorescent speckle particles are sprayed on the surface of the electrode to be measured, and the surface of the electrode to be measured is placed facing the optical window.

[0017] Furthermore, the assembled button battery is placed inside an inert argon glove box.

[0018] Furthermore, in step B, in-situ in-plane strain measurement of the electrode during the electrochemical process is carried out, including on the basis of a traditional DIC measurement device, combining fluorescent particles, a monochromatic laser light source and a filter to form a fluorescence DIC strain measurement system. The specific process is as follows:

[0019] First, the white light source of the traditional DIC measurement device is replaced with a monochromatic laser light source, and at the same time, a beam expander is equipped to expand the diameter of the laser spot;

[0020] Then, the monochromatic laser is placed at a certain inclination angle, and its laser irradiates the surface of the electrode to be measured, exciting the fluorescent particles in the measurement area;

[0021] Finally, a CCD camera is placed vertically above the battery as a signal receiving device, and a filter is installed in front of the lens to selectively receive the fluorescence signal of a specific wavelength emitted by the fluorescent particles.

[0022] Furthermore, in step B, in-situ in-plane strain measurement of the electrode during the electrochemical process is carried out. The specific process is as follows:

[0023] First, the fluorescence speckle images on the surface of the electrode during the electrochemical process are recorded in real time through the fluorescence DIC strain measurement system;

[0024] Then, correlation calculations are performed on the fluorescence speckle images to obtain the in-situ in-plane strain information on the surface of the electrode.

[0025] Furthermore, in step C, in-situ three-dimensional strain measurement of the electrode during the electrochemical process is carried out. The specific process is as follows:

[0026] First, the in-situ three-dimensional strain measurement of the electrode includes interlayer strain and in-plane strain;

[0027] Then, XRD technology is used to obtain the interlayer strain information;

[0028] Finally, in-plane strain information is obtained using Raman spectroscopy technology.

[0029] Furthermore, step D is based on the macroscopic in-plane strain measurement of the electrode and the microscopic three-dimensional strain measurement of the electrode, and data normalization is performed to obtain the cross-scale strain evolution information of the electrode structure in the electrochemical environment. The specific process is as follows:

[0030] First, during the electrochemical process, macroscopic fluorescence speckle images, XRD spectra, and Raman spectra are collected in real time to obtain the results of fluorescence DIC experiments at the macroscopic scale and XRD and Raman spectroscopy experiments at the microscopic scale;

[0031] Then, the electrochemical process is normalized;

[0032] Finally, the cross-scale strain evolution information of the electrode structure in the electrochemical environment is obtained.

[0033] The beneficial effects of the present invention are as follows:

[0034] The present invention realizes the in-situ integration of macroscopic digital image correlation and microscopic X-ray diffraction and Raman spectroscopy measurements, constructs a cross-scale strain measurement platform based on a unified specimen and a unified electrochemical process, and effectively solves the problem that cross-scale measurements cannot be synchronized. Compared with the existing single-scale strain measurement, the present invention can obtain the electrode structure strain information at the macroscopic and microscopic scales of the electrode, significantly improving the continuity and comprehensiveness of the strain measurement data.

[0035] The present invention uses a windowed button battery with a transparent polyimide PI film window to achieve the compatibility and synchronization of macroscopic DIC measurement and microscopic XRD and Raman spectroscopy measurements, without damaging the structure of the electrode specimen, and belongs to a non-destructive in-situ measurement technique. This method has good spatial and temporal resolutions and can reveal the macro-micro scale collaborative strain characteristics of electrode materials in real time and accurately during the electrochemical process. Description of the Drawings

[0036] Figure 1 is the structural diagram of the improved button battery in the present invention;

[0037] Figure 2 is the fluorescence DIC strain measurement route in the present invention;

[0038] Figure 3 is the in-situ XRD strain measurement route in the present invention;

[0039] Figure 4 is the in-situ Raman strain measurement route in the present invention;

[0040] Figure 5 is the curve of the macroscopic average in-plane strain, microscopic interlayer, and in-plane strain changing with the lithiumation depth in the present invention. Detailed implementation mode

[0041] The present invention will be described in detail below with reference to the accompanying drawings and embodiments:

[0042] As Figures 1 to 5 shown, a method for measuring the cross-scale strain of an electrode structure in an electrochemical environment includes the following steps:

[0043] A. Prepare and assemble a button battery with an optical window;

[0044] B. Measure the in-plane strain of the electrode during the electrochemical process;

[0045] C. Measure the three-dimensional micro-strain of the electrode during the electrochemical process;

[0046] D. Based on the in-plane strain measurement of the electrode and the three-dimensional micro-strain measurement of the electrode, perform data normalization processing to obtain the cross-scale strain evolution information of the electrode structure in the electrochemical environment.

[0047] In step A, the preparation and assembly of a button battery with an optical window are carried out, and the specific process is as follows:

[0048] First, a commercial CR2032 button battery is used as the object to be improved;

[0049] Then, a laser hole is drilled in the center of the positive electrode case of the button battery;

[0050] Then, the above laser hole is sealed with a transparent polyimide PI film;

[0051] Finally, a layer of open-cell nickel foam is added between the electrode to be measured and the positive electrode case inside the battery case.

[0052] The electrode to be measured uses a copper mesh as the substrate, and fluorescent speckle particles are sprayed on the surface of the electrode to be measured, and the surface of the electrode to be measured is placed facing the optical window.

[0053] The assembled button battery is placed in an inert argon glove box.

[0054] In step B, the in-plane strain measurement of the electrode during the electrochemical process is carried out, including combining fluorescent particles, a monochromatic laser light source and a filter on the basis of a traditional DIC measurement device to form a fluorescence DIC strain measurement system. The specific process is as follows:

[0055] First, the white light source of the traditional DIC measurement device is replaced with a monochromatic laser light source, and at the same time, a beam expander is equipped to expand the diameter of the laser spot;

[0056] Then, the monochromatic laser is placed at a certain inclination angle, and its laser irradiates the surface of the electrode to be measured, exciting the fluorescent particles in the measurement area;

[0057] Finally, the CCD camera is placed vertically above the battery as a signal receiving device, and a filter is installed in front of the lens to selectively receive the fluorescence signals of specific wavelengths emitted by the fluorescent particles.

[0058] In step B, the in-plane strain of the electrode is measured during the electrochemical process. The specific process is as follows:

[0059] First, the fluorescence speckle images on the electrode surface during the electrochemical process are recorded in real time by the fluorescence DIC strain measurement system;

[0060] Then, the correlation calculation is performed on the fluorescence speckle images to obtain the in-plane strain information on the electrode surface.

[0061] In step C, the three-dimensional microscopic strain of the electrode is measured during the electrochemical process. The specific process is as follows:

[0062] First, the three-dimensional microscopic strain measurement of the electrode includes the interlayer strain and the in-plane strain;

[0063] Then, the XRD technology is used to obtain the interlayer strain information;

[0064] Finally, the Raman spectroscopy technology is used to obtain the in-plane strain information.

[0065] In step D, based on the in-plane strain measurement of the electrode and the three-dimensional microscopic strain measurement of the electrode, data normalization is performed to obtain the cross-scale strain evolution information of the electrode structure in the electrochemical environment. The specific process is as follows:

[0066] First, during the electrochemical process, the acquisition of the macroscopic fluorescence speckle images, XRD spectra, and Raman spectra is carried out in real time to obtain the results of the fluorescence DIC experiment at the macroscopic scale and the XRD and Raman spectroscopy experiments at the microscopic scale;

[0067] Then, the electrochemical process is normalized;

[0068] Finally, the cross-scale strain evolution information of the electrode structure in the electrochemical environment is obtained.

[0069] Specifically, in step A, the transparent polyimide PI film can ensure that the white natural light can see the electrode surface inside the battery, and at the same time the spectrum can pass through the film to reach the electrode surface.

[0070] Specifically, the positive electrode of the battery is the electrode to be measured, and the commercial graphite electrode material is used. The negative electrode is a lithium sheet. The electrode to be measured uses a copper mesh as the substrate instead of the traditional copper foil substrate, and fluorescent speckle particles are sprayed on the electrode surface to ensure that ions can pass through the copper mesh to reach the electrode surface, and the electrode surface is placed facing the optical window of the battery case, while meeting the subsequent optical and spectral strain real-time measurements.

[0071] Specifically, in step C, XRD technology is used to obtain the interlayer strain information, and the specific process is as follows:

[0072] c11. Use an XRD instrument to collect spectral line information during the electrochemical process in real time. By tracking the change in the diffraction angle of the graphite (002) diffraction peak, the interlayer spacing parameter of the graphite lattice structure during the electrochemical process is given by Bragg's law, and its expression is as follows:

[0073]

[0074] Among them, d is the interlayer spacing; θ is the diffraction angle; λ is the wavelength of the X-ray; n is the diffraction order.

[0075] c12. According to the interlayer spacing parameter, further calculate the graphite micro interlayer strain information, and its expression is as follows:

[0076]

[0077] Among them, ε d refers to the interlayer strain; d0 refers to the interlayer spacing of graphite before lithium intercalation occurs.

[0078] Specifically, in step C, Raman spectroscopy technology is used for the in-plane strain information, and the specific process is as follows:

[0079] c21. The basic principle of Raman spectroscopy strain measurement is that when the material undergoes in-plane deformation, the lattice vibration frequency (phonon) will change and be reflected in the change of the spectral line peak position.

[0080] c22. During the electrochemical process, the peak position of the characteristic 2D peak of graphite will change, and the peak position of the 2D peak is linearly related to the strain.

[0081] c23. Use a Raman spectrometer to collect spectral line information during the electrochemical process in real time, and obtain the in-plane strain information of the graphite microstructure by tracking the change in the 2D peak position.

[0082] c24. Combining the lattice dynamics equation and the theory of elasticity, the strain calculation formula is as follows:

[0083]

[0084] Among them, ω0 is the initial peak position of the 2D peak in the strain-free state before the start of the electrochemical cycle, Δω is the change in the 2D peak, and γ is the Grüneisen parameter of the 2D peak.

[0085] Example 1

[0086] A method for measuring the cross-scale strain of an electrode structure in an electrochemical environment includes the following steps:

[0087] A. Prepare and assemble a button battery with an optical window

[0088] a1. Select the layered graphite material as the active material of the electrode to be tested.

[0089] a11. Mix graphite powder, conductive agent and binder, dissolve and disperse them in N-methylpyrrolidone solvent, and stir well to form a uniform slurry.

[0090] a12. Coat the slurry on the copper mesh current collector substrate and dry and cure it at 120 °C for 24 h. After drying, punch the electrode sheet into circular pieces with a diameter of 15 mm for standby.

[0091] The mass ratio of graphite powder, conductive agent and binder is 90:5:5.

[0092] a2. Uniformly coat fluorescent particles on the surface of the electrode disc by spraying method to obtain a high-contrast speckle image that meets the requirements of DIC calculation, and the speckle density is about 300-500 particles per square millimeter.

[0093] a21. The fluorescent particles have a core-shell structure (the core is rhodamine B dye and the shell is silica), and the particle size is about 600-800 nm.

[0094] a22. The silica shell layer ensures the chemical inertness of the particles during the electrochemical process and prevents the fluorescence decay of the fluorescent agent during the electrode reaction process.

[0095] a3. To ensure clear optical and spectral signals during the experiment, the in-situ cell device used has a transparent observation window and is specially designed in structure.

[0096] a31. Select a commercial CR2032 button cell positive electrode shell, and use a laser processing device to punch a hole with a diameter of about 5 mm in the center. Seal a transparent polyimide (PI) film with a diameter of about 16 mm and a thickness of 50 μm at the window of the cell shell with UV glue and cure it by ultraviolet light irradiation.

[0097] a4. In the glove box, assemble the in-situ cell specimen according to Figure 1 the internal structure of the cell shown.

[0098] a41. Use the graphite disc prepared in step one as the working electrode, that is, the electrode to be tested, and add a layer of open-cell nickel foam film between the graphite electrode and the positive electrode shell to increase the conductivity of the graphite electrode.

[0099] a42. Place the lithium metal sheet as the counter electrode on the other side of the separator. Both sides of the separator are immersed in the electrolyte, and complete the assembly of the cell specimen with battery components such as gaskets and shrapnel.

[0100] a43. While retaining the electrochemical performance of the standard CR2032 button battery, the improved button battery structure positions the working electrode opposite the transparent window, thus meeting the test requirements of subsequent in-situ DIC, XRD, and Raman spectroscopy.

[0101] B. Measure the in-plane strain of the electrode during the electrochemical process.

[0102] b1. Fix the assembled button battery with an optical window on the shock-proof optical measurement platform. Place the CCD camera lens vertically above the battery and adjust the camera focus to obtain a clear image of the graphite electrode surface.

[0103] b2. Use the fluorescence DIC strain measurement system built as shown in Figure 2 to collect images: Use a laser with a wavelength of 532 nm to excite the fluorescence particles to emit light. Add a beam expander in front of the laser to expand the laser spot diameter. At the same time, a long-pass filter with a cut-off wavelength above 600 nm is placed in front of the CCD camera lens, allowing only the red fluorescence emitted by the fluorescence particles to enter the photosensitive chip of the CCD camera. This effectively eliminates the influence of the color change of the electrode itself and ambient stray light on the image gray level in the collected speckle images, improving the signal-to-noise ratio and correlation of the speckle images.

[0104] b3. Collect the initial fluorescence speckle image as a reference image before the battery is loaded, and then apply a constant current to the battery for charge-discharge cycling.

[0105] In this example, a Blue Power battery tester is used to perform charge-discharge cycling experiments on the battery specimen at a rate of C / 7, and speckle images of the electrode surface are collected at fixed time intervals.

[0106] b4. Input a series of speckle images (including the initial undeformed state and the deformed states at various time points) collected from the DIC optical experiment into commercial DIC software (PMLAD-DIC) for correlation calculation to obtain the displacement field distribution and evolution information of the electrode surface.

[0107] C. Measure the three-dimensional microscopic strain of the electrode during the electrochemical process.

[0108] c1. Obtain the interlayer strain information using XRD technology

[0109] c11. Place the same battery specimen on the sample stage of the X-ray diffractometer and adjust the height position of the battery so that the X-ray can penetrate the window and irradiate the graphite electrode surface.

[0110] Figure 3 The optical path diagram of in-situ XRD measurement is given. In this example, a Smartlab diffractometer equipped with a Cu target is used, and the acceleration voltage is set to about 60 kV and the tube current is set to about 220 mA.

[0111] c12. Since graphite is a layered crystal, the diffraction peak position of its (002) plane is very sensitive to the change in the interlayer spacing of the crystal structure. By detecting the shift of the (002) diffraction peak angle relative to the initial state, the change in the interlayer strain of graphite can be calculated.

[0112] In this example, the in-situ XRD experiment was set with the measurement angle range between 20° and 30° to meet the scanning range of the (002) diffraction peak, the scanning step was 10° / min, and each in-situ XRD scan took 1.5 min.

[0113] c13. The initial (002) diffraction peak was collected as a reference peak before the battery was loaded, and then a constant current was applied to the battery for charge and discharge cycles.

[0114] In this example, a battery test specimen was subjected to charge and discharge cycle experiments using a Blue Electric battery tester at the same C / 7 rate, and XRD spectral data was collected at fixed time intervals during the discharge process.

[0115] c14. The fitting of XRD spectral data was realized using Jade software. The Gaussian function was used to fit the 002 diffraction peak of the graphite material to obtain the frequency shift and peak intensity information of the spectrum. Further, Bragg's law was applied to calculate the change in the lattice interlayer spacing of the electrode material, so as to obtain the microscopic interlayer strain and its evolution information.

[0116] c2. The in-plane strain information was obtained using Raman spectroscopy.

[0117] c21. The same battery test specimen was placed on the sample stage of the Raman spectrometer, and the height position of the battery was adjusted so that the laser could penetrate the window and irradiate the surface of the graphite electrode. Figure 4 The optical path diagram of in-situ Raman measurement is given. The in-situ Raman spectroscopy measurement was realized using an Alpha 300 type Witec confocal micro-Raman spectrometer in combination with a Blue Electric battery tester. The position of the Raman optical path was adjusted synchronously with the position of the battery window so that the Raman laser focus was as close as possible or adjacent to the XRD measurement area, thus ensuring the detection of the strain information of the material at the same position.

[0118] In order to ensure enough spacing between the graphite electrode and the Raman lens to avoid contact, a 50X long focal length lens was used. The commonly used Raman laser wavelength of 532 nm was selected, and it was carried out at a relatively low laser power (5 mW), with an exposure time of 2 s and an integration of 3 times.

[0119] c22. The Raman spectrum of the graphite electrode was collected in the initial state of the battery (before lithium intercalation), and the position of the characteristic peak was identified as the reference. The typical Raman characteristic peaks of graphite materials include the G peak at 1580 cm -1 and the 2700 cm -1The 2D peak, and the peak position of the 2D peak is linearly correlated with the strain. Therefore, the in-plane strain information of the graphite electrode can be obtained by measuring the change in the peak position of the 2D peak. Immediately afterwards, a constant current is applied to the battery for charge and discharge cycling.

[0120] In this example, a battery test specimen is subjected to charge and discharge cycling experiments using a LAND battery tester at the same C / 7 rate, and Raman spectroscopic data is collected at fixed time intervals during discharge.

[0121] c23. All the collected Raman spectroscopic data is processed using Project FIVE software, and the Lorentz function is used to fit the Raman characteristic peaks of the graphite material to obtain the frequency shift and peak intensity information of the spectral lines. According to the pre-calibrated quantitative functional relationship between the Raman peak shift and the strain, the offset of the 2D peak is converted into the in-plane strain value of the graphite layered structure.

[0122] D. Based on the measurement of the macroscopic in-plane strain of the electrode and the microscopic three-dimensional strain of the electrode, data normalization processing is carried out to obtain the cross-scale strain evolution information of the electrode structure in the electrochemical environment.

[0123] The above macroscopic and microscopic experimental strain results are normalized using a unified state of charge (SOC) to achieve precise alignment of experimental data at different scales.

[0124] In addition, since the strain values in the x and y directions of the in-plane strain contour map at the macroscopic scale are approximately equal, the average value is used as the equivalent macroscopic in-plane strain, thereby obtaining the variation law of the macroscopic strain with the state of charge. Figure 5 The curves of the macroscopic average in-plane strain, the microscopic interlayer and in-plane strain versus the state of charge are given.

[0125] The present invention is based on the digital image correlation (DIC) technology at the macroscopic scale and the X-ray diffraction (XRD) technology and Raman spectroscopic measurement technology at the microscopic scale to in-situ obtain the cross-scale strain information of the electrode structure. Through the processing and analysis of the macroscopic optical images and microscopic spectral data collected in the experiment, the comprehensive characterization of the macroscopic and microscopic strains of the electrode structure during the electrochemical process is realized, providing a basis for revealing the cross-scale lithium storage mechanism of the electrode and optimizing the battery structure design.

[0126] Specifically, the following functions are realized:

[0127] 1. It can characterize the evolution characteristics of the macroscopic in-plane strain on the electrode surface in the electrochemical environment.

[0128] 2. It can characterize the evolution characteristics of the interlayer strain and in-plane strain of the electrode microstructure in the electrochemical environment.

[0129] The present invention realizes the in-situ integration of macroscopic digital image correlation (DIC) with microscopic X-ray diffraction (XRD) and Raman spectroscopy measurements, constructs a cross-scale strain measurement platform based on a unified specimen and a unified electrochemical process, and effectively solves the problem of the inability to synchronize cross-scale measurements. Compared with the existing single-scale strain measurement, the present invention can obtain the electrode structure strain information at the macroscopic and microscopic scales of the electrode, significantly improving the continuity and comprehensiveness of the strain measurement data.

[0130] The present invention realizes the compatibility and synchronization of macroscopic DIC measurement with microscopic XRD and Raman spectroscopy measurements by using a windowed button battery with a transparent polyimide PI film window, without the need to destroy the structure of the electrode specimen, belonging to a non-destructive in-situ measurement technique. This method has good spatial and temporal resolutions and can reveal the macro-microscopic scale collaborative strain characteristics of electrode materials in real time and accurately during the electrochemical process.

Claims

1. A method for measuring the cross-scale strain of an electrode structure in an electrochemical environment, characterized in that: It includes the following steps: A. Prepare and assemble a button battery with an optical window; B. Measure the in-plane strain of the electrode during the electrochemical process; C. Measure the three-dimensional micro-strain of the electrode during the electrochemical process; D. Based on the in-plane strain measurement of the electrode and the three-dimensional micro-strain measurement of the electrode, perform data normalization to obtain the cross-scale strain evolution information of the electrode structure in the electrochemical environment.

2. The method for measuring the cross-scale strain of an electrode structure in an electrochemical environment according to claim 1, wherein: In step A, prepare and assemble a button battery with an optical window. The specific process is as follows: First, use a commercial CR2032 button battery as the object to be improved; Then, laser drill a hole in the center of the positive electrode case of the button battery; Next, use a transparent polyimide PI film to seal the above laser hole; Finally, add a layer of open-cell nickel foam between the electrode to be measured and the positive electrode case inside the battery case.

3. The method for measuring the cross-scale strain of an electrode structure in an electrochemical environment according to claim 2, characterized in that: The electrode to be measured uses a copper mesh as the substrate, sprays fluorescent speckle particles on the surface of the electrode to be measured, and places the surface of the electrode to be measured facing the optical window.

4. A method for measuring the cross-scale strain of an electrode structure in an electrochemical environment according to claim 3, characterized in that: The assembled button battery is placed in an inert argon glove box.

5. A method for measuring cross-scale strain of an electrode structure in an electrochemical environment according to claim 1, characterized in that: In step B, measure the in-plane strain of the electrode during the electrochemical process, including combining fluorescent particles, a monochromatic laser light source and a filter on the basis of a traditional DIC measurement device to form a fluorescence DIC strain measurement system. The specific process is as follows: First, replace the white light source of the traditional DIC measurement device with a monochromatic laser light source, and at the same time equip an expander to expand the diameter of the laser spot; Then, place the monochromatic laser at a certain inclination angle, and its laser irradiates the surface of the electrode to be measured to excite the fluorescent particles in the measurement area; Finally, place the CCD camera as a signal receiving device vertically above the battery, and install a filter in front of the lens to selectively receive the fluorescent signal of a specific wavelength emitted by the fluorescent particles.

6. The method for measuring the cross-scale strain of an electrode structure in an electrochemical environment according to claim 5, characterized in that: In step B, measure the in-plane strain of the electrode during the electrochemical process. The specific process is as follows: First, use the fluorescence DIC strain measurement system to record the fluorescence speckle images on the surface of the electrode during the electrochemical process in real time; Then, perform correlation calculation on the fluorescence speckle images to obtain the in-plane strain information on the surface of the electrode.

7. An electrochemical environment electrode structure cross-scale strain measurement method according to claim 1, characterized in that: In step C, measure the three-dimensional micro-strain of the electrode during the electrochemical process. The specific process is as follows: First, the three-dimensional micro-strain measurement of the electrode includes interlayer strain and in-plane strain; Then, use the XRD technique to obtain the interlayer strain information; Finally, use the Raman spectroscopy technique to obtain the in-plane strain information.

8. A method for measuring the cross-scale strain of an electrode structure in an electrochemical environment according to claim 1, characterized in that: In step D, based on the in-plane strain measurement of the electrode and the three-dimensional micro-strain measurement of the electrode, perform data normalization to obtain the cross-scale strain evolution information of the electrode structure in the electrochemical environment. The specific process is as follows: First, collect the macroscopic fluorescence speckle images, XRD spectra and Raman spectra in real time during the electrochemical process to obtain the results of the macroscopic fluorescence DIC experiment and the microscopic XRD and Raman spectroscopy experiments; Then, normalize the electrochemical process; Finally, obtain the cross-scale strain evolution information of the electrode structure in the electrochemical environment.

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