Solid electrolyte ionic conductivity estimation method and system

Abstract

The present invention belongs to the technical field of battery testing, and discloses a method and system for estimating the ionic conductivity of a solid electrolyte. The differential change curve of the impedance modulus time function to the impedance modulus is obtained according to the electrochemical impedance spectrum of the solid electrolyte, and the impedance limit that can distinguish the solid electrolyte impedance from the diffusion impedance is obtained in the curve, and the total impedance contributed by the solid electrolyte is obtained and used as the impedance of the solid electrolyte. The ionic conductivity of the solid electrolyte is estimated according to the obtained impedance of the solid electrolyte. The method is simple to test and operate, does not require model fitting or complex analysis of the data, and has low test cost. It has important application value in high-throughput screening of solid electrolytes and rapid performance evaluation.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery testing, and in particular relates to a method and system for estimating ionic conductivity of a solid electrolyte. Background Art

[0002] Lithium-ion batteries have become one of the mainstream energy storage solutions due to their high energy density, long cycle life and relatively high safety, and are widely used in portable electronic products, electric vehicles and large-scale energy storage systems. However, traditional liquid electrolyte lithium-ion batteries have disadvantages such as leakage, flammability, poor stability and limited operating temperature range, which limit the application scope and performance of lithium-ion batteries.

[0003] As a new type of electrolyte material, solid electrolytes have attracted widespread attention due to their excellent thermal stability, higher safety performance and potential high energy density. Solid electrolytes can effectively solve the problem of electrolyte leakage, reduce the risk of combustion, and are expected to work stably in a wider temperature range. At present, a major problem faced by solid electrolytes in practical applications is that their ionic conductivity is usually lower than that of liquid electrolytes, which limits the charge and discharge efficiency and power density of lithium-ion batteries.

[0004] Therefore, how to improve the ionic conductivity of solid electrolytes is an urgent problem to be solved in the application of solid electrolytes. The research on the ionic conductivity of solid electrolytes often involves the optimization of the chemical composition, microstructure and manufacturing process of solid electrolyte materials. How to accurately and quickly measure the ionic conductivity of solid electrolytes during the research and optimization process plays a key role in the optimization of solid electrolytes. Summary of the invention

[0005] The object of the present invention is to provide a solid electrolyte ion conductivity estimation method and system to achieve accurate and rapid evaluation of the solid electrolyte ion conductivity.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for estimating the ionic conductivity of a solid electrolyte obtains a differential change curve of the impedance modulus as a function of time to the impedance modulus based on the electrochemical impedance spectrum of the solid electrolyte, obtains an impedance boundary that can distinguish the solid electrolyte impedance from the diffusion impedance in the curve, obtains the total impedance contributed by the solid electrolyte and uses it as the impedance of the solid electrolyte, and estimates the ionic conductivity of the solid electrolyte based on the obtained impedance of the solid electrolyte.

[0008] Optionally, a method for obtaining the impedance of a solid electrolyte includes:

[0009] Testing the electrochemical impedance spectrum of the sample to be tested formed by using the solid electrolyte, and obtaining a first curve of impedance modulus changing with frequency;

[0010] Convert the first curve to obtain a second curve of impedance modulus changing with time;

[0011] Solving the inverse function of the second curve to obtain a third curve showing the change of impedance modulus value with time;

[0012] Performing second-order differential processing on the third curve to obtain a fourth curve of second-order differential change of impedance modulus time function to impedance modulus value;

[0013] The impedance modulus value corresponding to the maximum value of the second-order differential of the impedance modulus value with respect to time in the fourth curve is obtained and used as the impedance of the solid electrolyte.

[0014] Optionally, the sample to be tested is obtained by integrally pressing and molding by respectively arranging blocking electrodes on both sides of a solid electrolyte.

[0015] Optionally, the pressure used for compression molding of the solid electrolyte is 200MPa-600MPa.

[0016] Optionally, the material of the blocking electrode includes at least one of graphite, indium, lithium, steel, copper, silver, gold and platinum.

[0017] Optionally, the solid electrolyte is one or more of a polymer electrolyte, an oxide electrolyte, a sulfide electrolyte, and a halide electrolyte.

[0018] Optionally, a pressure of 20MPa-200MPa is applied to the sample to be tested, and the electrochemical impedance spectrum of the sample to be tested is tested in a constant potential mode. The lower limit of the test frequency range is any frequency between 0.01 Hz and 10 Hz, and the upper limit of the test frequency range is 10^7 Hz.

[0019] Optionally, before converting the first curve, the step of preprocessing the first curve is also included, including:

[0020] Taking the data corresponding to the portion where the imaginary part of the impedance in the first curve turns into a positive value, and excluding the data where the imaginary part of the impedance just turns into a positive value, to obtain the preprocessed first curve;

[0021] The preprocessed first curve is converted to obtain a second curve showing the impedance modulus changing with time.

[0022] Optionally, the step of estimating the ionic conductivity of the solid electrolyte according to the acquired impedance of the solid electrolyte includes:

[0023] Obtain the size parameters of the sample to be tested, including thickness and area;

[0024] The ionic conductivity of the solid electrolyte is obtained according to the thickness and area of ​​the sample to be tested and the impedance of the solid electrolyte.

[0025] On the other hand, the present invention also provides a solid electrolyte ion conductivity estimation system, comprising:

[0026] A first curve processing module, the first curve processing module is used to convert the acquired curve of the impedance modulus value of the sample to be tested formed by using solid electrolyte into a curve of the impedance modulus value changing with frequency into a curve of the impedance modulus value changing with time;

[0027] A second curve processing module, the second curve processing module is used to perform an inverse function solution on the curve of impedance modulus value changing with time to obtain a curve of impedance modulus value changing with time;

[0028] A third curve processing module, the third curve processing module is used to perform second-order differential processing on the curve of time changing with impedance modulus value to obtain a curve of second-order differential change of impedance modulus value as a function of impedance modulus value time;

[0029] An estimation module is used to obtain the impedance of the solid electrolyte from a curve of the second-order differential change of the impedance modulus value as a function of the impedance modulus value over time, and to estimate the ionic conductivity of the solid electrolyte.

[0030] Optionally, the system also includes a curve preprocessing module, which is used to obtain data corresponding to the conversion of the imaginary part of the impedance to the positive part in the curve of the impedance modulus changing with frequency, and does not include data where the imaginary part of the impedance has just been converted to a positive value, so as to obtain a preprocessed curve of the impedance modulus changing with frequency.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] The present invention is based on the difference in contribution of solid electrolyte impedance and diffusion impedance to impedance modulus at different frequencies in electrochemical impedance spectroscopy, obtains the impedance boundary that distinguishes solid electrolyte impedance from diffusion impedance in a curve of differential change of impedance modulus with time, obtains the total impedance contributed by the solid electrolyte and uses it as the impedance of the solid electrolyte, thereby achieving accurate and rapid estimation of the ionic conductivity of the solid electrolyte. The method has simple test operation, does not require model fitting or complex analysis of data, and has low test cost, and has important application value in high-throughput screening of solid electrolytes and rapid performance evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 is a curve showing the change of the first-order differential of the impedance modulus over time in the embodiment of the present invention; wherein, is the impedance modulus, is the first-order differential of the impedance modulus with respect to time.

[0035] Figure 2 is a second-order differential change curve of the impedance modulus time function to the impedance modulus in the embodiment of the present invention; wherein, is the impedance modulus, is the second-order differential of the impedance modulus with respect to time.

[0036] Figure 3 for Figure 2 A local enlarged diagram corresponding to the maximum value of the second-order differential of the impedance modulus time function to the impedance modulus.

[0037] Figure 4 is a curve showing the impedance modulus value changing with frequency in Example 1 of the present invention; wherein, f is the frequency, is the impedance modulus.

[0038] Figure 5 is a curve showing the impedance modulus changing with time in Example 1 of the present invention; wherein τ is time, is the impedance modulus.

[0039] Figure 6 is a curve showing the change of time with impedance modulus in Example 1 of the present invention; wherein, is the impedance modulus, and τ is the time.

[0040] Figure 7 is the second-order differential change curve of the impedance modulus time function to the impedance modulus in Example 1 of the present invention; wherein, is the impedance modulus, is the second-order differential of the impedance modulus with respect to time.

[0041] Figure 8 for Figure 7 A local enlarged diagram corresponding to the maximum value of the second-order differential of the impedance modulus time function to the impedance modulus.

[0042] Fig. 9 is the second-order differential change curve of the impedance modulus time function to the impedance modulus in Example 2 of the present invention; wherein, is the impedance modulus, is the second-order differential of the impedance modulus with respect to time.

[0043] Fig.10 for Fig. 9 A local enlarged diagram corresponding to the maximum value of the second-order differential of the impedance modulus time function to the impedance modulus. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the present application clearer, the specific embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. It is understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for the convenience of description, only the part related to the present application but not all the contents are shown in the accompanying drawings. Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow chart describes each operation (or step) as a sequential process, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of each operation can be rearranged. The process can be terminated when its operation is completed, but it can also have additional steps not included in the accompanying drawings. The process can correspond to a method, a function, a procedure, a subroutine, a subprogram, etc.

[0045] At present, the solid electrolyte ionic conductivity test methods used include equivalent circuit fitting based on electrochemical impedance spectroscopy and DC polarization technology. These test methods have problems such as complex data analysis, long test time, and large errors, which limit their application in high-throughput screening and rapid performance evaluation of solid electrolytes.

[0046] Electrochemical impedance spectroscopy: Apply a small amplitude AC potential wave with different frequencies to the electrochemical system and measure the ratio of the AC potential to the current signal as the sine wave frequency changes. f The change in the phase angle of the impedance with the frequency of the sine wave f changes.

[0047] Based on the demand for high-throughput screening and rapid performance evaluation of solid electrolytes, the present invention proposes a method for estimating the ionic conductivity of solid electrolytes based on impedance modulus. This method does not require model fitting, is simple to analyze data, can achieve rapid estimation with small errors, and can realize accurate and rapid estimation of the ionic conductivity of solid electrolytes.

[0048] In some embodiments of the present invention, a method for estimating the ionic conductivity of a solid electrolyte is to obtain a differential change curve of the impedance modulus as a function of the impedance modulus time based on the electrochemical impedance spectrum of the solid electrolyte, obtain an impedance boundary that can distinguish the solid electrolyte impedance from the diffusion impedance in the curve, obtain the total impedance contributed by the solid electrolyte and use it as the impedance of the solid electrolyte, and estimate the ionic conductivity of the solid electrolyte based on the obtained impedance of the solid electrolyte.

[0049] The impedance modulus time function to impedance modulus differential change curve here refers to a curve obtained by performing differential processing on the curve of impedance modulus change with time.

[0050] The diffusion impedance here refers to the diffusion impedance of lithium ions in the blocking electrode.

[0051] Based on the fact that the modulus of electrochemical impedance spectroscopy has the characteristics of the entire impedance of the electrochemical system to be measured, and in the electrochemical impedance spectroscopy, at high frequencies, the impedance modulus mainly reflects the impedance contributed by the solid electrolyte, which has a smaller impedance, while at medium and low frequencies, the impedance modulus mainly reflects the diffusion of lithium ions in the blocking electrode, which has a larger impedance. The present invention adopts a curve of the change of impedance modulus over time (i.e. The first-order differential curve is processed to obtain the curve of the impedance modulus value changing with time to the first-order differential of the impedance modulus value (i.e. curve), refer to Figure 1 ,from It can be seen from the curve that the first half of the curve changes faster, while the second half changes slower. Through analysis, it is found that the first half changes faster, mainly because the impedance contributed by the solid electrolyte is extremely small. Due to its small change, its first-order differential changes larger; the second half changes slower, mainly because the lithium ion diffusion impedance in the blocking electrode changes larger, making its first-order differential change smaller.

[0052] Based on this finding, if we can find The turning point of the curve change rate in the curve can be used to obtain the impedance boundary that separates the solid electrolyte impedance and the diffusion impedance. Through this impedance boundary, the total impedance contributed by the solid electrolyte can be obtained, that is, the impedance of the solid electrolyte can be obtained.

[0053] Therefore, some embodiments of the present invention adopt The curve is further subjected to first-order differential processing to obtain the second-order differential change curve of the impedance modulus value time function to the impedance modulus value (i.e. curve), refer to Figure 2 and Figure 3 The local enlarged diagram corresponding to the maximum value of the second-order differential of the impedance modulus time function to the impedance modulus is shown in the figure. The impedance modulus value corresponding to the maximum value of the second-order differential of the impedance modulus value with respect to time in the curve is the total impedance contributed by the solid electrolyte, thereby obtaining the impedance of the solid electrolyte, and according to the impedance of the solid electrolyte, the ionic conductivity of the solid electrolyte can be estimated.

[0054] In some embodiments of the present invention, a method for obtaining the impedance of a solid electrolyte includes:

[0055] The electrochemical impedance spectrum of the solid electrolyte sample was tested to obtain the first curve of impedance modulus changing with frequency, namely curve;

[0056] The first curve is converted to obtain a second curve of impedance modulus changing with time, that is, curve;

[0057] Solving the inverse function of the second curve, we can obtain the third curve of the change of impedance modulus over time, that is, curve;

[0058] The third curve is subjected to second-order differential processing to obtain the fourth curve of the second-order differential change of the impedance modulus value as a function of the impedance modulus value, that is, curve;

[0059] The impedance modulus value corresponding to the maximum value of the second-order differential of the impedance modulus value with respect to time in the fourth curve is obtained and used as the impedance of the solid electrolyte sample.

[0060] In some embodiments, before converting the first curve, the step of preprocessing the first curve is also included, including:

[0061] The data corresponding to the part where the imaginary part (-Z'') of the impedance in the first curve is converted to a positive value is taken, and the data where the imaginary part (-Z'') of the impedance has just been converted to a positive value is not included, to obtain the preprocessed first curve; the preprocessed first curve is converted to obtain a second curve where the impedance modulus changes with time.

[0062] In some embodiments, the step of estimating the ionic conductivity of the solid electrolyte according to the acquired impedance of the solid electrolyte includes:

[0063] Obtain the size parameters of the sample to be tested, including thickness and area;

[0064] The ionic conductivity of the solid electrolyte is obtained according to the thickness and area of ​​the sample to be tested and the impedance of the solid electrolyte.

[0065] As an implementable manner, the method for estimating ionic conductivity of a solid electrolyte of the present invention may employ the following specific steps:

[0066] 1) Prepare the samples to be tested;

[0067] A solid electrolyte is used and blocking electrodes are respectively arranged on both sides of the solid electrolyte, which is pressed into a dense small disc in a solid-state battery mold to obtain a test sample to be tested.

[0068] The solid electrolyte can be a mixture of one or more of polymer electrolytes (such as PEO, PPC, etc.), oxide electrolytes (such as LLZO, LLTO, LAGP, etc.), sulfide electrolytes (such as LPS, LPSC, LGPS, etc.), and halide electrolytes (such as Li3InCl6, Li3ScCl6, etc.).

[0069] The solid electrolyte may contain a binder, and the binder may be a mixture of one or more of PVDF, SBR, PAA, PTFE, SEBS, and EBS.

[0070] The pressure used during compression molding may be 200 MPa-600 MPa.

[0071] The blocking electrode can be made of sheet materials such as graphite, indium, lithium, steel, copper, silver, gold, and platinum.

[0072] 2) Test the electrochemical impedance spectroscopy of the sample to be tested;

[0073] An electrochemical impedance spectroscopy test was performed on the sample to be tested set in the solid-state battery mold. During the test, a pressure of 20MPa-200MPa was applied to the sample to be tested, and the electrochemical impedance spectrum was obtained by the test in a constant potential mode of 10mV.

[0074] The lower limit of the frequency range used in the electrochemical impedance spectroscopy test is any frequency between 0.01 Hz and 10 Hz, such as 10 Hz, 1 Hz, 0.1 Hz, and 0.01 Hz, and the upper limit of the test frequency range is 10^7 Hz.

[0075] The number of data points collected in the electrochemical impedance spectroscopy test can be set as needed. The more data points collected, the more accurate the test results of this method will be, but the time required for the test will increase. For example, the number of data points collected can be selected to be 10-20 per frequency order of magnitude.

[0076] Electrochemical impedance spectroscopy testing can be performed at any temperature between -30°C and 100°C.

[0077] 3) Measure the dimensional parameters of the sample to be tested;

[0078] The tested sample is disassembled from the solid-state battery mold, and the thickness and area of ​​the solid electrolyte layer of the sample are measured.

[0079] 4) Obtain the curve of impedance modulus changing with frequency according to the electrochemical impedance spectrum and perform preprocessing;

[0080] From the test results of the electrochemical impedance spectroscopy, the curve of impedance modulus changing with frequency is obtained, that is, curve;

[0081] right The curve is preprocessed. The part corresponding to the inductance and ohmic internal resistance is discarded in the curve, specifically The curve only takes the data corresponding to the part where the imaginary part of the impedance (-Z'') turns to a positive value, and does not include the data that has just turned to a positive value, and obtains the preprocessed The first curve after preprocessing is obtained.

[0082] 5) The pre-processed Curve, according to The frequency f Converted to time τ, we get the curve of impedance modulus changing with time, that is, curve.

[0083] 6) Yes The inverse function of the curve is solved to obtain the curve of the change of impedance modulus over time, that is, curve.

[0084] 7) Obtain the impedance of the solid electrolyte;

[0085] right The curve is processed by second-order differential to obtain the second-order differential change curve of impedance modulus value time function to impedance modulus value, that is, curve;

[0086] The impedance modulus value corresponding to the maximum value of the second-order differential of the impedance modulus value with respect to time in the curve is the total impedance contributed by the solid electrolyte, which is taken as the impedance of the solid electrolyte of the sample to be tested.

[0087] 8) Calculate the ionic conductivity of solid electrolytes by solid electrolyte impedance;

[0088] Through the solid electrolyte ionic conductivity formula:

[0089] ;

[0090] Where σ is the ionic conductivity, L is the thickness of the solid electrolyte layer of the sample to be tested, R is the solid electrolyte impedance, S is the cross-sectional area of ​​the solid electrolyte layer of the sample to be tested;

[0091] The ionic conductivity of the solid electrolyte is calculated, thereby realizing the estimation of the ionic conductivity of the solid electrolyte.

[0092] The method for estimating ionic conductivity of solid electrolytes of the present invention is described in detail below with reference to specific embodiments.

[0093] Example 1

[0094] This embodiment is a method for estimating the ionic conductivity of a sulfide solid electrolyte, comprising:

[0095] 1) Prepare the samples to be tested;

[0096] The sulfide electrolyte membrane containing PVDF binder was cut into small discs of Φ10 mm, which were placed in a Φ10 mm solid-state battery mold, and graphite paper was placed on both sides of the sulfide electrolyte membrane as blocking electrodes;

[0097] A pressure of 300 MPa is applied to the sulfide electrolyte membrane and the blocking electrode as a whole in the solid-state battery mold to form a sample to be tested.

[0098] 2) Test the electrochemical impedance spectroscopy of the sample to be tested;

[0099] The sample to be tested prepared in step 1) is subjected to a constant potential electrochemical impedance spectroscopy test at a bias voltage of 10mV in a solid-state battery mold, the test frequency range is 10^7Hz-1Hz, and the number of data points collected is 10 data points per frequency order of magnitude;

[0100] During the test, a pressure of 50 MPa was applied to the sample to be tested and the test temperature was 25°C.

[0101] 3) Measure the dimensional parameters of the sample to be tested;

[0102] The tested sample is disassembled from the solid-state battery mold and the thickness of the solid electrolyte layer of the sample is measured. L and area S , respectively 0.0085cm, 0.785cm 2 .

[0103] 4) Obtain the curve of impedance modulus changing with frequency according to the electrochemical impedance spectrum and perform preprocessing;

[0104] From the test results of the electrochemical impedance spectroscopy, the curve of impedance modulus changing with frequency is obtained, that is, Curves, such as Figure 4 As shown;

[0105] right The curve is preprocessed to discard the parts corresponding to the inductance and ohmic internal resistance, as shown in Table 1, and the data starting from the 12th row of data (excluding the header) is obtained, including the data of the 12th row, but excluding the data of the 11th row, because the data of the 11th row is the data where the imaginary part of the impedance (-Z'') has just turned positive.

[0106] Table 1 Impedance modulus value changes with frequency

[0107] Data serial number Frequency (Hz) Real impedance Z' (Ω) Impedance imaginary part - Z'' (Ω) Impedance modulus |Z| (Ω) 1 10000250 7.736794 -60.7865 61.27692 2 7943532 7.719179 -50.0943 50.68559 3 6309823 7.249581 -39.0075 39.67543 4 5012122 7.348305 -29.7924 30.68527 5 3981322 7.463118 -22.5144 23.71911 6 3162528 7.838823 -16.6439 18.39742 7 2512136 8.521953 -11.974 14.69697 8 1995512 9.094459 -8.13638 12.20286 9 1585143 9.781852 -4.91597 10.94766 10 1259175 10.43903 -2.38897 10.7089 11 1000250 11.10428 0.016237 11.10429 12 794578.2 11.8574 2.042291 12.03199 13 631207.3 12.62281 3.888724 13.20823 14 501437.2 13.45903 5.666407 14.6032 15 398357.2 14.33797 7.450335 16.15812 16 316477.8 15.31579 9.315723 17.92641 17 251438.6 16.46065 11.2963 19.96395 18 199776.2 17.56618 13.5313 22.17356 19 158489.3 18.86832 16.07106 24.78492 20 125892.5 20.3461 19.01236 27.8466 21 100000 21.9501 22.38296 31.3497 22 79432.82 23.77506 26.37978 35.51262 23 63095.73 25.85716 31.12985 40.46802 24 50118.72 28.22899 36.81425 46.39143 25 39810.72 30.9751 43.59289 53.47707 26 31622.78 34.1421 51.71884 61.97194 27 25118.86 37.77608 61.53615 72.20616 28 19952.62 42.01464 73.30941 84.49556 29 15848.93 47.04004 87.54393 99.38161 30 12589.25 52.87755 104.429 117.0532 31 10000 59.84496 125.0306 138.6148 32 7943.282 68.04267 149.8413 164.5668 33 6309.573 77.81247 179.768 195.886 34 5011.872 89.49805 215.8123 233.634 35 3981.072 103.5567 259.5101 279.4092 36 3162.278 120.2228 311.8839 334.2531 37 2511.886 140.2771 375.1173 400.488 38 1995.262 164.3702 451.1826 480.1909 39 1584.893 193.445 543.0547 576.4802 40 1258.925 228.4349 653.7057 692.4692 41 1000 270.7978 787.0433 832.3272 42 794.3282 321.9308 947.5246 1000.721 43 630.9573 383.9791 1140.659 1203.555 44 501.1872 459.1882 1373.086 1447.833 45 398.1072 550.5497 1652.95 1742.226 46 316.2278 661.4727 1988.003 2095.162 47 251.1886 797.0598 2390.095 2519.496 48 199.5262 960.7329 2874.667 3030.96 49 158.4893 1161.356 3453.759 3643.789 50 125.8925 1403.865 4148.162 4379.279 51 100 1704.673 4977.613 5261.42 52 79.43282 2060.023 5967.095 6312.679 53 63.09573 2463.007 7164.775 7576.305 54 50.11872 3062.636 8260.86 8810.309 55 39.81072 3639.181 10212.2 10841.25 56 31.62278 4310.395 12155.95 12897.54 57 25.11886 5274.173 14565.45 15490.94 58 19.95262 6306.749 17411.88 18518.87 59 15.84893 7586.312 20842.5 22180.22 60 12.58925 8993.012 24834.56 26412.68 61 10 10764.39 29699.32 31589.9 62 7.943282 12996.65 35344.21 37658.01 63 6.309573 15249.94 42632.57 45277.99 64 5.011872 18436.59 50994.05 54224.54 65 3.981071 21388.15 60907.29 64553.47 66 3.162278 25873.09 73804.16 78207.87 67 2.511886 30375.01 88111.29 93200 68 1.995262 37432.95 106000 112415.5 69 1.584893 45854.29 126561.9 134612.5 70 1.258925 53919.31 152155.6 161426.9

[0108] 5) The pre-processed Curve, according to The frequency f Converted to time τ, we get the curve of impedance modulus changing with time, that is, Curves, such as Figure 5 shown.

[0109] 6) For the result obtained in step 5) The inverse function of the curve is solved to obtain the curve of the change of impedance modulus over time, that is, Curves, such as Figure 6 shown.

[0110] 7) Obtain the impedance of the solid electrolyte;

[0111] For the result obtained in step 6) The curve is processed by second-order differential to obtain the second-order differential change curve of impedance modulus value time function to impedance modulus value, that is, curve;

[0112] The impedance modulus value corresponding to the maximum value of the second-order differential of the impedance modulus value with respect to time in the curve is the total impedance contributed by the solid electrolyte, which is taken as the impedance of the solid electrolyte of the sample to be tested; Figure 7 and Figure 8 As shown in the partial enlarged figure in the figure, the impedance of the solid electrolyte can be obtained. R 19.96Ω;

[0113] Through the solid electrolyte ionic conductivity formula: ; The calculated ionic conductivity σ of the solid electrolyte is 0.54×10^-3S / cm.

[0114] Example 2

[0115] This embodiment is a method for estimating the ionic conductivity of a sulfide solid electrolyte.

[0116] The difference from Example 1 is:

[0117] The solid electrolyte used to prepare the sample to be tested is 100 mg of sulfide solid electrolyte powder, and the solid electrolyte does not contain a binder;

[0118] Thickness of the sample to be tested L 0.085cm, area S 0.785cm 2 ;

[0119] like Fig. 9 and Fig.10 As shown, the impedance of the solid electrolyte in this embodiment can be obtained R 74.13Ω;

[0120] The calculated ionic conductivity σ of the solid electrolyte is 1.46×10^-3S / cm.

[0121] The method of the present invention can realize rapid and accurate estimation of the ionic conductivity of solid electrolytes at low cost, and has important application value in high-throughput screening and performance evaluation of solid electrolytes. It is of great significance to accelerate the development of solid-state battery technology, promote the performance improvement of electric vehicles and renewable energy storage systems, and promote energy transformation.

[0122] On the other hand, in some embodiments of the present invention, there is provided a solid electrolyte ion conductivity estimation system, comprising:

[0123] The first curve processing module is used to convert the obtained curve of the impedance modulus value of the sample to be tested formed by solid electrolyte into a curve of the impedance modulus value changing with frequency

[0124] A second curve processing module, the second curve processing module is used to solve the inverse function of the curve of impedance modulus value changing with time, so as to obtain the curve of impedance modulus value changing with time;

[0125] A third curve processing module, the third curve processing module is used to perform second-order differential processing on the curve of time changing with impedance modulus value, to obtain a curve of second-order differential change of impedance modulus value as a function of impedance modulus value time;

[0126] The estimation module is used to obtain the impedance of the solid electrolyte from the curve of the second-order differential change of the impedance modulus value as a function of the impedance modulus value over time, and to estimate the ionic conductivity of the solid electrolyte.

[0127] The method of estimating the ionic conductivity of solid electrolytes using this system has been described in detail above and will not be repeated here.

[0128] In some embodiments, the system also includes a curve preprocessing module, which is used to obtain data corresponding to the conversion of the imaginary part of the impedance (-Z'') to a positive value in the curve of the impedance modulus value changing with frequency, and does not include data where the imaginary part of the impedance (-Z'') has just been converted to a positive value, so as to obtain a preprocessed curve of the impedance modulus value changing with frequency.

[0129] Correspondingly, the first curve processing module is used to convert the preprocessed curve of impedance modulus changing with frequency into a curve of impedance modulus changing with time.

[0130] Of course, the system may also include a data acquisition module for acquiring test data of the electrochemical impedance spectroscopy test.

[0131] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for estimating ionic conductivity of a solid electrolyte, characterized in that: According to the electrochemical impedance spectrum of the solid electrolyte, a curve of the differential change of the impedance modulus value as a function of the impedance modulus value over time is obtained, an impedance boundary that can distinguish the solid electrolyte impedance from the diffusion impedance is obtained from the curve, the total impedance contributed by the solid electrolyte is obtained and used as the impedance of the solid electrolyte, and the ionic conductivity of the solid electrolyte is estimated according to the obtained impedance of the solid electrolyte; The method for obtaining the impedance of the solid electrolyte includes: Testing the electrochemical impedance spectrum of the sample to be tested formed by using the solid electrolyte, and obtaining a first curve of impedance modulus changing with frequency; Convert the first curve to obtain a second curve of impedance modulus changing with time; Solving the inverse function of the second curve to obtain a third curve showing the change of impedance modulus value with time; Performing second-order differential processing on the third curve to obtain a fourth curve of second-order differential change of impedance modulus value as a function of impedance modulus value over time; Obtaining the impedance modulus value corresponding to the maximum value of the second-order differential of the impedance modulus value with respect to time in the fourth curve and using it as the impedance of the solid electrolyte; Before converting the first curve, the method further includes preprocessing the first curve, including: Taking the data corresponding to the portion where the imaginary part of the impedance in the first curve turns into a positive value, and excluding the data where the imaginary part of the impedance just turns into a positive value, to obtain the preprocessed first curve; The preprocessed first curve is converted to obtain a second curve showing the impedance modulus changing with time.

2. The method for estimating ionic conductivity of a solid electrolyte according to claim 1, characterized in that: The sample to be tested is obtained by integrally pressing and molding by respectively arranging blocking electrodes on both sides of a solid electrolyte.

3. The method for estimating ionic conductivity of a solid electrolyte according to claim 2, characterized in that: The pressure used for pressing and molding the solid electrolyte is 200MPa-600MPa.

4. The method for estimating ionic conductivity of a solid electrolyte according to claim 2, characterized in that: The material of the blocking electrode includes at least one of graphite, indium, lithium, steel, copper, silver, gold and platinum.

5. The method for estimating ionic conductivity of a solid electrolyte according to claim 1 or 2, characterized in that: The solid electrolyte is one or more of a polymer electrolyte, an oxide electrolyte, a sulfide electrolyte, and a halide electrolyte.

6. The method for estimating ionic conductivity of a solid electrolyte according to claim 1, characterized in that: A pressure of 20MPa-200MPa is applied to the sample to be tested, and the electrochemical impedance spectrum of the sample to be tested is tested in constant potential mode. The lower limit of the test frequency range is any frequency between 0.01 Hz and 10 Hz, and the upper limit of the test frequency range is 10^7 Hz.

7. The method for estimating ionic conductivity of a solid electrolyte according to claim 1, characterized in that: The step of estimating the ionic conductivity of the solid electrolyte according to the acquired impedance of the solid electrolyte comprises: Obtain the size parameters of the sample to be tested, including thickness and area; The ionic conductivity of the solid electrolyte is obtained according to the thickness and area of ​​the sample to be tested and the impedance of the solid electrolyte.

8. A solid electrolyte ion conductivity estimation system, characterized in that: include: A first curve processing module, the first curve processing module is used to convert the acquired curve of the impedance modulus value of the sample to be tested formed by using solid electrolyte into a curve of the impedance modulus value changing with frequency into a curve of the impedance modulus value changing with time; A second curve processing module, the second curve processing module is used to perform an inverse function solution on the curve of impedance modulus value changing with time to obtain a curve of impedance modulus value changing with time; A third curve processing module, the third curve processing module is used to perform second-order differential processing on the curve of time changing with impedance modulus value to obtain a curve of second-order differential change of impedance modulus value as a function of impedance modulus value time; An estimation module, the estimation module is used to obtain the impedance of the solid electrolyte from the curve of the second-order differential change of the impedance modulus value as a function of the impedance modulus value over time, and to estimate the ionic conductivity of the solid electrolyte; The solid electrolyte ionic conductivity estimation system also includes a curve preprocessing module, which is used to obtain data corresponding to the part where the imaginary part of the impedance is converted to a positive value in the curve where the impedance modulus changes with frequency, and does not include data where the imaginary part of the impedance has just been converted to a positive value, so as to obtain a preprocessed curve where the impedance modulus changes with frequency.

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