In-situ method for measuring ionic conductivity of solid state electrolytes

Abstract

The application discloses a method for in-situ measurement of ion conductivity of a solid electrolyte, and comprises the following steps: placing a solid electrolyte to be measured in an atomic force microscope device, applying a bias voltage to form an electric field in a preset direction, scanning the solid electrolyte to be measured along a direction parallel to the electric field direction, obtaining a slope of potential change with time, and measuring the ion conductivity of the solid electrolyte according to the slope of potential change with time. The application first uses an atomic force microscope to in-situ test the ion conductivity of a solid electrolyte, fills a gap in the field of atomic force microscopes, and has the advantages of simple testing process and good reproducibility.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte ionic conductivity testing technology, and in particular to an in-situ method for measuring the ionic conductivity of solid electrolytes. Background Technology

[0002] Solid-state electrolytes include inorganic solid-state electrolytes, polymer solid-state electrolytes, and composite solid-state electrolytes. Compared to liquid electrolytes, solid-state electrolytes offer advantages such as better safety, a wider electrochemical window, and lower ionic conductivity. To obtain solid-state electrolyte materials with high ionic conductivity, advanced characterization techniques are needed to understand the complexity of ion transport mechanisms. The ion diffusion coefficient measures the ability of ions to migrate within the crystal lattice of a material, and is crucial for studying the microstructure and ion transport mechanisms of materials. Ion mobility and ionic conductivity can be obtained by measuring the ion diffusion coefficient, and current methods for measuring the ion diffusion coefficient include isotope tracing, galvanostatic titration (GITT), and potential step method (PSCA). Isotope tracing methods are difficult to implement and only applicable to a limited range of material systems. Gaussian galvanostatic titration (GITT) and potential step method (PSCA) are often used to test the lithium diffusion coefficient in lithium-ion electrode materials, but these methods cannot directly test solid-state electrolytes, lacking direct microscopic characterization. Instead, they require the fabrication of full or half-cells for testing, and cannot distinguish between electrode and electrolyte signals, making the test results susceptible to interference from various factors. Therefore, developing new, low-cost technologies that can directly test and characterize the microscopic ion transport in solid-state electrolytes is crucial. In-depth research into ion transport mechanisms will further advance the development of solid-state electrolytes.

[0003] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide an in-situ method for measuring the ionic conductivity of solid electrolytes, aiming to solve the problems that existing methods for testing the ionic conductivity of solid electrolytes require the solid electrolyte to be prepared as a half cell or a full cell, making it impossible to distinguish the signals of the electrodes and the electrolyte, and lacking direct microscopic characterization of solid electrolytes.

[0005] The technical solution of the present invention is as follows:

[0006] A first aspect of the present invention provides an in-situ method for measuring the ionic conductivity of a solid electrolyte, comprising the steps of:

[0007] Provide the solid electrolyte to be tested;

[0008] The solid electrolyte to be tested is placed in an atomic force microscope device, and a bias voltage is applied to the solid electrolyte to be tested to form an electric field in a preset direction;

[0009] The solid electrolyte under test is scanned using an atomic force microscope along a direction parallel to the electric field direction to obtain a slanted line showing the change of potential over time.

[0010] The ionic conductivity of the solid electrolyte is determined based on the slope of the potential change over time.

[0011] Optionally, the solid electrolyte under test has a test surface at the top and two electrode surfaces on both sides, and a metal layer is disposed on each of the two electrode surfaces.

[0012] Optionally, the solid electrolyte to be tested is placed in the fixture of the atomic force microscope device, and the metal layers on the two electrode surfaces are respectively attached to the two sides of the fixture;

[0013] Positive and negative electrode wires are led out from the mating surfaces of the two metal layers and the fixture, respectively, and the other ends of the positive and negative electrode wires are connected to the controller of the atomic force microscope device. A DC bias voltage is applied to the solid electrolyte under test through the controller.

[0014] Optionally, the solid electrolyte under test is linearly scanned using a scanning Kelvin microscope in an atomic force microscope device along a direction parallel to the direction of the electric field, and the potential change on the test line is recorded to obtain a slanted line of potential change over time.

[0015] Optionally, the step of determining the ionic conductivity of the solid electrolyte based on the slope of the potential change over time specifically includes:

[0016] Place the oblique line in a rectangular coordinate system with the x-axis parallel to the direction of the electric field and the y-axis perpendicular to the x-axis;

[0017] Projecting the oblique line onto the x-axis yields the ion migration distance, and projecting the oblique line onto the y-axis yields the time taken for the ion to migrate that distance.

[0018] The ion migration velocity is obtained based on the ion migration distance and the time.

[0019] The ionic conductivity of solid electrolytes is determined based on the relationship between ion migration rate and ionic conductivity.

[0020] Optionally, based on the proportional relationship between ion migration rate and ion conductivity, the magnitude of the ion conductivity of the solid electrolyte can be qualitatively determined according to the magnitude of the ion migration rate.

[0021] Optionally, the ionic conductivity of the solid electrolyte is quantitatively determined based on the following relationship between ion migration rate and ionic conductivity:

[0022]

[0023] In the formula, σ is the ionic conductivity, n is the concentration of mobile ions per unit volume, q is the charge carried by the ions, v is the ion migration velocity, and E is the electric field strength.

[0024] Beneficial Effects: This invention, for the first time, utilizes atomic force microscopy (AFM) to electrically control the solid electrolyte under test by applying an external electric field, thereby observing the phenomenon of microscopic ion transport. Simultaneously, a slope curve showing the change in potential over time is obtained. Based on this slope, the ion migration velocity is determined, and then the ionic conductivity of the solid electrolyte is measured according to the relationship between ion migration velocity and ionic conductivity. This invention eliminates the need to prepare the solid electrolyte into a full or half-cell before testing, and allows direct observation of microscopic ion transport phenomena. It effectively solves the problems of existing methods that require preparing the solid electrolyte into a half or full cell, making it impossible to distinguish the signals of electrodes and electrolytes, and lacking direct microscopic characterization of solid electrolytes. The measurement method provided by this invention is simple to prepare, the testing process is convenient, and it has good reproducibility. This invention is the first to utilize AFM for in-situ testing of the ionic conductivity of solid electrolytes, filling the gap in in-situ measurement of solid electrolyte ionic conductivity using AFM, and is of great significance for the development of in-situ testing methods using AFM. Attached Figure Description

[0025] Figure 1 This is a schematic flowchart of the in-situ measurement method for the ionic conductivity of solid electrolytes in an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of an in-situ atomic force microscope method for testing the ionic conductivity of solid electrolytes in an embodiment of the present invention.

[0027] Figure 3 This is a physical image of the fixture in Embodiment 1 of the present invention.

[0028] Figure 4 This is a topographic image of LZP under an atomic force microscope in Embodiment 1 of the present invention.

[0029] Figure 5 This is a potential diagram of LZP measured under different DC bias voltages in Embodiment 1 of the present invention.

[0030] Figure 6 The graph shows the ion migration rate of LZP measured under different DC bias voltages in Example 1 of this invention.

[0031] Figure 7The graph shows the ionic conductivity of LZP measured under different DC bias voltages in Example 1 of this invention.

[0032] Figure 8 This is a potential diagram of LZFP measured under different DC bias voltages in Embodiment 2 of the present invention.

[0033] Figure 9 The graph shows the ion migration velocity results of LZFP measured under different DC bias voltages in Example 2 of the present invention.

[0034] Figure 10 The graph shows the ionic conductivity results of LZFP measured under different DC bias voltages in Example 2 of this invention. Detailed Implementation

[0035] This invention provides an in-situ method for determining the ionic conductivity of solid electrolytes. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0037] This invention provides an in-situ method for determining the ionic conductivity of a solid electrolyte, wherein, as shown in the embodiments of the present invention... Figure 1 As shown, the steps include:

[0038] S1. Provide the solid electrolyte to be tested;

[0039] S2. Place the solid electrolyte to be tested in an atomic force microscope device, apply a bias voltage to the solid electrolyte to be tested, and form an electric field in a preset direction;

[0040] S3. Scan the solid electrolyte under test using an atomic force microscope along a direction parallel to the electric field direction to obtain a slanted line showing the change of potential over time.

[0041] S4. Determine the ionic conductivity of the solid electrolyte based on the slope of the potential change over time.

[0042] Atomic force microscopy (AFM) utilizes the interaction between a probe and a sample to obtain high spatial resolution images. AFM can not only image the surface morphology of samples but also perform high spatial resolution measurements and imaging of local surface potential, charge, and conductivity. For different test samples, it is necessary to design test methods suitable for AFM.

[0043] This invention, for the first time, utilizes atomic force microscopy (AFM) to electrically control the solid electrolyte under test by applying an external electric field, thereby observing the phenomenon of microscopic ion transport. Simultaneously, a slope curve showing the change in potential over time is obtained. Based on this slope, the ion migration velocity is determined, and then the ionic conductivity of the solid electrolyte is measured according to the relationship between ion migration velocity and ionic conductivity. This invention eliminates the need to prepare the solid electrolyte into a full or half-cell before testing. It can obtain information on the microstructure of the solid electrolyte surface and directly observe the phenomenon of microscopic ion transport, effectively solving the problems of existing methods that require preparing the solid electrolyte into a half or full cell, making it impossible to distinguish the signals of electrodes and electrolytes, and lacking direct microscopic characterization of solid electrolytes. The measurement method provided by this invention is simple to prepare, the testing process is convenient, and it has good reproducibility. This invention is the first to utilize AFM for in-situ testing of the ionic conductivity of solid electrolytes, filling the gap in in-situ measurement of solid electrolyte ionic conductivity using AFM, and is of great significance for the development of in-situ testing methods using AFM.

[0044] In step S1, the roughness of the test surface can be set according to the actual situation. In some embodiments, the solid electrolyte under test has a test surface located at the top, and the roughness (Ra) of the test surface is 10-50 nm, for example, it can be 10, 15, 20, 25, 30, 35, 40, 45, or 50 nm. When using an atomic force microscope for testing, the Z-axis range of the probe is only 3 μm. Therefore, to obtain a complete and clear data map, the difference between the highest and lowest points of the measurement area must be less than 3 μm. At the same time, the potential signal is affected by the morphology to a certain extent. When the roughness of the test surface is 10-50 nm, the influence of the test surface morphology can be better avoided, making the test results more accurate.

[0045] In some embodiments, the solid electrolyte under test further has two parallel electrode surfaces located on opposite sides, each with a metal layer disposed thereon. This invention does not limit the method of preparing the metal layers; exemplarily, the metal layers can be prepared on the two electrode surfaces using either magnetron sputtering or ion sputtering. The metal layers on the two electrode surfaces are provided to better apply a DC bias voltage to the solid electrolyte under test.

[0046] In some embodiments, the metal in the metal layer includes at least one selected from gold, copper, titanium, chromium, and platinum. In some specific embodiments, the metal in the metal layer is gold. Gold allows for better application of DC bias to the solid electrolyte under test, while its conductivity and ductility better meet the testing requirements.

[0047] In step S2, in some embodiments, the solid electrolyte is placed in the fixture of the atomic force microscope device, and the metal layers on the two parallel electrode surfaces are respectively attached to the two sides of the fixture.

[0048] Positive and negative electrode wires are led out from the mating surfaces of the two metal layers and the fixture, respectively, and the other ends of the positive and negative electrode wires are connected to the controller of the atomic force microscope device. A DC bias voltage is applied to the solid electrolyte under test through the controller.

[0049] In this embodiment, the solid electrolyte under test is connected to the controller using external positive and negative leads to apply a DC bias voltage to the solid electrolyte under test. In this embodiment, the fixture can be placed in the atomic force microscope device first, and then the solid electrolyte under test can be placed in the fixture of the atomic force microscope device; alternatively, the solid electrolyte under test can be placed in the fixture first, and then the fixture holding the solid electrolyte under test can be placed in the atomic force microscope device.

[0050] In some embodiments, the DC bias voltage is 1.25-3V. The DC bias voltage is the driving force for ion migration in the solid electrolyte; when the DC bias voltage reaches 1.25V, a distinct diagonal line can be observed. Of course, the DC bias voltage can be set according to actual conditions, with the appearance of a distinct diagonal line as the standard.

[0051] In step S3, in some embodiments, the solid electrolyte to be tested is linearly scanned using a scanning Kelvin microscope in an atomic force microscope device along a direction parallel to the direction of the electric field, and the potential change on the test line is recorded to obtain a slanted line showing the change of potential over time.

[0052] In a homogeneous and stable solid electrolyte material, without material exchange with the outside world, the ions in the solid electrolyte material are uniformly distributed and have a consistent ion concentration. If a DC bias voltage (forming an electric field) is applied to the solid electrolyte material, the ions in the solid electrolyte material will migrate under the drive of the electric field (taking lithium ions as an example, their migration direction is from the positive electrode to the negative electrode, and the lithium ion migration direction is parallel to the electric field direction). The probe is fixed on a test line parallel to the electric field direction and repeatedly scanned (e.g., ...). Figure 2 As shown in the diagram, the change in potential along this test line over time can be measured. Furthermore, since the surface potential of a solid electrolyte is solely caused by ion migration, the potential is directly proportional to the ion concentration. Therefore, by recording the change in potential over time along a test line of a solid electrolyte sample, the movement of ions can be observed.

[0053] In step S4, in some embodiments, the step of determining the ionic conductivity of the solid electrolyte based on the slope of the potential change over time specifically includes:

[0054] S41. Place the oblique line in a rectangular coordinate system with the coordinate axis parallel to the electric field direction as the x-axis and the coordinate axis perpendicular to the x-axis as the y-axis;

[0055] S42. Project the oblique line onto the x-axis to obtain the ion migration distance, and project the oblique line onto the y-axis to obtain the time taken for the ion to migrate the distance.

[0056] S43. Obtain the ion migration rate based on the ion migration distance and the time.

[0057] S44. Determine the ionic conductivity of solid electrolytes based on the relationship between ion migration rate and ionic conductivity.

[0058] In steps S41-S42, such as Figure 2 As shown, projecting the oblique line onto the x-axis yields the ion migration distance, and projecting the oblique line onto the y-axis (corresponding to...) Figure 2 The time taken for ions to migrate the specified distance is obtained by projecting the oblique line onto the x-axis (the time axis in the diagram). In other words, the projection of the oblique line onto the x-axis represents the ion migration distance, and the projection onto the y-axis represents the time taken for the ion to migrate that distance.

[0059] The diagonal lines represent equipotential lines, meaning the potential along the diagonal line is the same. Since the surface potential of a solid electrolyte is solely caused by ion migration, and the potential is directly proportional to the ion concentration, within a small spatial and temporal scale, under an applied bias voltage, ions within a region migrate simultaneously. It can be assumed that the concentration distribution within a finite region remains constant over a short period. Therefore, equipotential lines represent lines of equal ion concentration. Thus, equipotential lines can be considered the vector sum of the time and space of ion movement at the same concentration. Projecting the diagonal lines onto the x-axis and y-axis respectively, the projection onto the x-axis can be considered the ion migration distance, and the projection onto the y-axis can be considered the time taken for the ions to migrate this distance.

[0060] In step S43, the ion migration speed is obtained by dividing the ion migration distance by the time taken for the ion to migrate that distance.

[0061] In step S44, the ionic conductivity of solid electrolytes can be qualitatively or quantitatively determined based on the relationship between ion migration rate and ionic conductivity.

[0062] In some implementations, the ionic conductivity of the solid electrolyte is qualitatively determined based on the proportional relationship between ion migration rate and ionic conductivity, according to the magnitude of the ion migration rate. In other words, the ionic conductivity of the solid electrolyte is qualitatively compared based on the magnitude of the ion migration rate. Since the reciprocal of the ion migration rate is also the slope of the curve, the ionic conductivity of the solid electrolyte can also be qualitatively compared by comparing the slopes of the measured curves. Specifically, the smaller the slope of the curve, the greater the ionic conductivity of the solid electrolyte.

[0063] In other embodiments, the ionic conductivity of a solid electrolyte can be quantitatively determined based on the relationship between ion migration rate and ionic conductivity. Specifically, the ionic conductivity of the solid electrolyte is quantitatively determined based on the following relationship between ion migration rate and ionic conductivity:

[0064]

[0065] In the formula, σ is the ionic conductivity, n is the concentration of mobile ions per unit volume, q is the charge carried by the ions, v is the ion migration velocity, and E is the electric field strength.

[0066] Specifically, the ion mobility under the influence of an electric field can be characterized as the ratio of the ion migration velocity to the applied electric field strength, i.e. In the formula, v is the ion migration rate and E is the electric field strength. Therefore, by obtaining the electric field strength during ion migration, the ion mobility μ can be calculated.

[0067] The relationship between ion mobility and ion conductivity is: σ = n·q·μ;

[0068] In the formula, σ is the ionic conductivity, n is the mobile ion concentration per unit volume, q is the charge carried by the ions, and μ is the ion mobility. Therefore, the ionic conductivity can be obtained from the ion mobility and the ionic conductivity.

[0069] The following detailed description uses specific examples.

[0070] Example 1

[0071] An in-situ method for determining the ionic conductivity of the solid electrolyte lithium zirconium phosphate (LZP), comprising the following steps:

[0072] (1) Provide the solid electrolyte to be tested, which is LZP prepared by liquid method. It is an ion conductor with a diameter of 11 mm and a thickness of 1 mm (cylindrical).

[0073] (2) Place the LZP to be tested in an ion sputtering instrument and sputter the two bottom surfaces (as electrode surfaces) of the LZP. Set the current to 8mA, the sputtering time to 3min, and the sputtering material to gold to form a gold layer.

[0074] (3) Polish the sides of the gold-plated LZP to be tested with a metallographic polishing machine until there is no gold residue (when sputtering gold on the two bottom surfaces, it may cause some of the sides to be sputtered with gold as well); continue to polish until smooth to form a test surface suitable for atomic force microscopy testing. At this time, the roughness Ra of the test surface is 20nm; and the remaining part of the two bottom surfaces with a diameter of 11mm after the above polishing test surface steps is used as the electrode surface (equivalent to the side of the cylinder being polished into a plane, and the area of ​​the two bottom surfaces is also reduced accordingly due to polishing).

[0075] (4) Figure 3 As shown, the LZP to be tested obtained in step (3) is placed in a fixture (PR-AFM-MH Pro). The fixture is clamped on the two gold-plated electrode surfaces of the LZP to be tested, so that the test surface is on top and exposed outside the fixture. The positive and negative copper wires are led out from the contact surface between the gold layer and the fixture, and the other end of the positive wire and the other end of the negative wire are connected to the controller of the atomic force microscope. By setting the program, a DC bias voltage is applied to the LZP to be tested to form an electric field in a preset direction.

[0076] (5) The fixture was placed in an atomic force microscope (AFM) for in-situ testing. A scanning Kelvin microscope was used to test the potential distribution on the LZP surface. A relatively smooth line was selected as the test line, with a length of 5 μm and a direction parallel to the applied electric field. Using the line scan mode of the scanning Kelvin microscope, DC bias voltages of 0V, 2V, 2.1V, 2.2V, 2.3V, and 2.4V were applied to both ends of the sample via the controller. The test line was repeatedly linearly scanned with a probe under different DC bias voltages. (During the linear scan, the appearance of the potential line can be observed by applying a suitable DC bias voltage. In this embodiment, the potential line was observed above 2V.) Figure 5 As shown by the dashed line in the figure, the change of the potential of the test line over time can be recorded, that is, different potential changes over time are obtained under different DC bias voltages (i.e., isopotential lines).

[0077] (6) Figure 2 As shown, the oblique line is placed in a rectangular coordinate system with the x-axis parallel to the electric field direction as the x-axis and the y-axis perpendicular to the x-axis as the y-axis. The projection of the oblique line onto the x-axis is the ion migration distance, and the projection of the oblique line onto the y-axis is the time taken for the ion to migrate that distance. The ion migration velocity is obtained by dividing the ion migration distance by the time taken for the ion to migrate that distance.

[0078] (7) According to (Where σ is the ionic conductivity, n is the concentration of mobile ions per unit volume, q is the charge carried by the ions, v is the ion migration velocity, and E is the electric field strength), the ionic conductivity is calculated.

[0079] The morphology of LZP obtained using atomic force microscopy is shown in the figure below. Figure 4 As shown.

[0080] The potential diagram of LZP under different DC bias voltages is as follows: Figure 5 As shown.

[0081] The results of LZP ion migration velocities measured under different DC bias voltages are shown in the figure below. Figure 6 As shown.

[0082] The ionic conductivity of LZP measured under different DC bias voltages is shown in the figure below. Figure 7 As shown, the average ionic conductivity of LZP measured under different DC biases is 1.4 × 10⁻⁶. -4 S / cm, where the ionic conductivity of LZP measured by EIS method is 3.3 × 10⁻⁶. -5 S / cm.

[0083] Example 2

[0084] The in-situ testing method for the ionic conductivity of lithium zirconium iron phosphate is basically the same as the method for determining the ionic conductivity of the solid electrolyte lithium zirconium iron phosphate in Example 1, except that:

[0085] The solid electrolyte to be tested is lithium zirconium iron phosphate (LZP), a ceramic electrolyte prepared by liquid method. It is an ion conductor with a diameter of 10 mm and a thickness of 1 mm.

[0086] The controller applies DC bias voltages of 0V, 1V, 1.25V, 1.3V, 1.35V, 1.4V, 1.6V, 1.7V, 1.9V, and 2.0V to both ends of the sample, respectively.

[0087] The potential diagram of LZFP under different DC bias voltages is as follows: Figure 8 As shown, a sloping line is observed above 1.4V; the ion migration velocity results of LZFP measured under different DC bias voltages are shown in the figure below. Figure 9 As shown in the figure; the ionic conductivity results of LZFP measured under different DC bias voltages are shown in the figure. Figure 10 As shown, the average ionic conductivity of LZFP measured under different DC biases is 2.28 × 10⁻⁶. -4 The ionic conductivity of LZFP, measured by EIS, is 7.2 × 10⁻⁶ S / cm. -5 S / cm.

[0088] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for in-situ determination of the ionic conductivity of a solid electrolyte, characterized in that, Including the following steps: A solid electrolyte to be tested is provided, the solid electrolyte to be tested having a test surface located on its top, the roughness of the test surface being 10-50 nm; The solid electrolyte to be tested is placed in an atomic force microscope device, and a DC bias voltage is applied to the solid electrolyte to be tested to form an electric field in a preset direction; Along a direction parallel to the electric field direction, the test line on the test surface of the solid electrolyte under test is repeatedly linearly scanned using a scanning Kelvin microscope in an atomic force microscope device. The change of potential at each point on the same test line over time is recorded to obtain a potential data graph of each point on the test line over time. In the potential data graph, the horizontal axis represents the position of each point on the test line, and the vertical axis represents the scanning time of the repeated linear scan. Connect the points with equal potential values ​​in the potential data graph to form a diagonal line; The ionic conductivity of the solid electrolyte to be tested is determined based on the oblique line. The step of determining the ionic conductivity of the solid electrolyte to be tested based on the oblique line specifically includes: Place the oblique line in a rectangular coordinate system with the x-axis parallel to the direction of the electric field and the y-axis perpendicular to the x-axis; Projecting the oblique line onto the x-axis yields the migration distance of the ions, and projecting the oblique line onto the y-axis yields the time it takes for the ions to migrate to the migration distance. The ion migration velocity is obtained based on the migration distance of the ion and the time taken for the ion to migrate to the migration distance. The ionic conductivity of the solid electrolyte under test is determined based on the relationship between ion migration rate and ionic conductivity.

2. The in-situ method for determining the ionic conductivity of a solid electrolyte according to claim 1, characterized in that the solid electrolyte to be tested further has two electrode surfaces located on its two sides, and a metal layer is disposed on each of the two electrode surfaces.

3. The in-situ method for determining the ionic conductivity of a solid electrolyte according to claim 2, characterized in that, The solid electrolyte to be tested is placed in the fixture of the atomic force microscope device, and the metal layers on the two electrode surfaces are respectively attached to the two sides of the fixture. Positive and negative electrode wires are led out from the mating surfaces of the two metal layers and the fixture, respectively, and the other ends of the positive and negative electrode wires are connected to the controller of the atomic force microscope device. A DC bias voltage is applied to the solid electrolyte under test through the controller.

4. The in-situ method for determining the ionic conductivity of a solid electrolyte according to claim 1, characterized in that, Based on the direct proportionality between ion migration velocity and ion conductivity, the magnitude of the ion conductivity of the solid electrolyte under test is qualitatively determined according to the magnitude of the ion migration velocity.

5. The in-situ method for determining the ionic conductivity of a solid electrolyte according to claim 1, characterized in that, The ionic conductivity of the solid electrolyte under test is quantitatively determined based on the following relationship between ion migration rate and ionic conductivity: In the formula, Let be the ionic conductivity, n be the concentration of mobile ions per unit volume, and q be the charge carried by the ions. Let E be the ion migration velocity and E be the electric field strength.

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