Impedance-based method and system for detecting moisture content of thermal battery electrolyte materials

Abstract

The application discloses an impedance-based thermal battery electrolyte material moisture content detection method and system, and solves the technical problem that the moisture content of the thermal battery electrolyte material cannot be quickly and non-destructively detected at present. The method comprises the following steps: the application is applied to the state of a thermal battery monomer battery piece or the state of a battery complete machine after assembly, the influence of moisture content and distribution uniformity, environmental temperature and compacted density on the impedance of the thermal battery is considered, a nonlinear correlation model of impedance and electrolyte material moisture content and a determination process of parameters in the correlation model are proposed, the impedance of the thermal battery in a non-activated state is measured, the nonlinear correlation model of electrolyte material moisture content and impedance is adopted, and the moisture content in the electrolyte material of the thermal battery is calculated. The application can obtain the moisture content of the electrolyte material in the battery complete machine and the monomer battery piece of the thermal battery in real time, is fast, accurate in measurement, non-destructive to the product, applicable to different temperature environments, and can be non-destructively detected on line.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal battery detection, and particularly relates to a thermal battery electrolyte moisture content detection method and system based on impedance. BACKGROUND

[0002] A thermal battery is a kind of disposable reserve battery widely used in various types of equipment, and has the characteristics of long storage life, high reliability, high safety, high specific energy and high specific power. Each monomer battery of the thermal battery is pressed by a positive electrode, an electrolyte and a negative electrode, the negative electrode is generally a very active lithium alloy such as LiB, LiSi and LiAl, the positive electrode is generally a material such as FeS2, Fe x Co 1-x S2, CoS2, V2O5 and NiCl2, and the electrolyte is a molten salt. Since the molten salt electrolyte is prone to moisture absorption, it often contains a certain amount of moisture, and the moisture released from the molten salt reacts with the positive electrode and the negative electrode during the long-term storage process or working of the thermal battery, resulting in a decrease in the performance of the battery. Therefore, the moisture in the electrolyte material is one of the key factors affecting the performance of the thermal battery, and the trace moisture content in the electrolyte must be strictly controlled and characterized in the production and inspection of the thermal battery.

[0003] The currently commonly used methods for detecting the moisture content of the material mainly include Karl Fischer method and thermogravimetric method, both of which can only test a small amount of electrolyte material, and the moisture content in the electrolyte material of the thermal battery monomer battery or the thermal battery product needs to be tested after the thermal battery is destroyed to obtain the electrolyte material, and the sampling and measurement process is easily affected by the environmental humidity and needs to be operated in a dry environment, which is complex, time-consuming and harsh to the environment, and is a destructive test.

[0004] Meizhou Liangneng New Energy Technology Co., Ltd. reported a method for detecting the moisture content of a battery electrode sheet, which measures the resistance of the battery electrode sheet to detect the moisture content of the battery electrode material, but this method cannot be applied to the detection of the moisture content of the thermal battery electrolyte material. First, since the electrode sheet resistance only accounts for a small part of the battery resistance, this method is only applicable to the detection of the moisture content of the electrode sheet material in the electrode sheet preparation process, and cannot be applied after the completion of the pressing of the battery monomer battery or the assembly of the whole machine. Second, since the conductive mechanisms of the electrode material and the electrolyte material are different, the linear correlation model of impedance and moisture content in the method cannot be applied to the molten salt electrolyte of the thermal battery. Third, the method does not eliminate the influence of uneven distribution of moisture on the impedance of the material. Fourth, the method does not eliminate the influence of the measurement environment temperature on the impedance of the molten salt electrolyte. Fifth, the electrode in the method adopts a coating process, while the thermal battery monomer battery generally adopts a powder pressing process, and the different pressures result in different electrolyte compaction densities and different resistivities, and the method does not eliminate the influence of the impedance difference caused by the change of the compaction density on the detection accuracy of the moisture content. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the moisture content of the electrolyte material in existing thermal batteries needs to be tested through destructive testing in a dry environment. However, the existing methods for detecting the moisture content of battery electrode sheets are not suitable for detecting the moisture content of electrolyte materials in thermal batteries, and cannot accurately and non-destructively detect the moisture content of electrolyte materials in individual battery cells or the entire battery system.

[0006] The purpose of this invention is to provide a method and system for detecting the moisture content of electrolyte materials in thermal batteries based on impedance. This invention is applied to the overall state of the battery after the individual cell is pressed or assembled. Considering the influence of factors such as moisture content and distribution uniformity, ambient temperature changes, and compaction density on the impedance of the electrolyte material, a nonlinear correlation model between impedance and the moisture content of the electrolyte material is proposed. By measuring the impedance of the thermal battery in its inactive state, this model is used to obtain the moisture content of the electrolyte material in the entire thermal battery and individual cells in real time. It is fast, accurate, non-destructive to the product, applicable to different temperature environments, and can be used for online non-destructive testing.

[0007] This invention is achieved through the following technical solution:

[0008] In a first aspect, the present invention provides a method for detecting the moisture content of electrolyte materials in thermal batteries based on impedance, the method comprising:

[0009] Measure the impedance of the thermal battery in its inactive state;

[0010] Based on the measured impedance of the thermal battery in its inactive state, the moisture content in the electrolyte material is calculated using a nonlinear correlation model between the moisture content and impedance of the electrolyte material. The nonlinear correlation model between the moisture content and impedance of the electrolyte material is as follows:

[0011] Y=a×{[R0×S0 / (n0×h0)]×exp[c×(1 / T1-1 / T0)]+d×(m3×S0×h0-m0×S1×h1) / (S0×h0

[0012] ×S1×h)} -b

[0013] Among them, a is the electrolyte material factor, b is the moisture influence factor, c is the temperature influence factor, d is the compaction density influence factor, R0 is the impedance of the thermal battery in the unactivated state, n0 is the number of single battery sheets in the thermal battery, S0 is the area of the single battery sheet, h0 is the thickness of the electrolyte material layer in the single battery sheet, m0 is the mass of the electrolyte material in the single battery sheet, m3 is the mass of the electrolyte sheet in the preliminary test, S1 is the area of the electrolyte sheet in the preliminary test, h1 is the thickness of the electrolyte sheet in the preliminary test, T1 is the ambient temperature in the preliminary test, and T0 is the ambient temperature when measuring the impedance of the thermal battery in the unactivated state.

[0014] Further, measuring the impedance of the thermal battery in the unactivated state includes:

[0015] When the thermal battery is at temperature T0, the impedance is obtained by measuring the alternating current impedance spectrum or the direct current current-voltage (I-V) curve of the thermal battery; where 273K <= T0 <= 473K, and K is the absolute temperature unit Kelvin.

[0016] Further, the obtaining methods of the electrolyte material factor, the moisture influence factor, the temperature influence factor and the compaction density influence factor are as follows:

[0017] S100. Take out the electrolyte materials B1, B2,..., Bn from the containers C1, C2,..., Cn, weigh n portions of electrolyte materials D1, D2,..., Dn with a mass of m1 from each portion of the electrolyte, and press the n portions of electrolyte materials with a mass of m1 into electrolyte thin sheets E1, E2,..., En with an area of S1 and a thickness of h1 respectively, where n is an integer greater than 2;

[0018] S101. Measure the impedances of the above n electrolyte thin sheets at temperature T1, which are R11, R12,..., R1n respectively;

[0019] S102. Take R11, R12,..., R1n as the independent variable R1, take the moisture contents Y1, Y2,..., Yn of the n portions of electrolyte materials as the dependent variable Y, and use Y = a×[R1×S1 / h1] -b for fitting to obtain the coefficients a and b, where a is the electrolyte material factor and b is the moisture influence factor;

[0020] S103. Place any one of the electrolyte thin sheets E1, E2,..., En at temperatures T21, T22,..., T2m respectively, and measure the impedances R21, R22,..., R2m at this temperature, where 273K <= T21 < T22 <... < T2m <= 473K, and m is an integer greater than 1;

[0021] S104. Take T21, T22, ……, T2m as the independent variable T2, take R21, R22, ……, R2m as the dependent variable R2, and use R2 = e×exp(c / T2) for fitting to obtain the coefficients c and e, where e is the pre-factor of the temperature test and c is the temperature influence factor;

[0022] S105. Take out the electrolyte material Bj from the container Cj, weigh k portions of electrolytes with a mass of m3 each, and obtain k electrolyte thin films F1, F2, ……, Fk with an area of S1 and thicknesses of h21, h22, ……, h2k respectively by controlling the pressing pressure, where j is an integer not greater than n, k is an integer greater than 1, 0 < m3 <= (m2 - m1) / k, and m2 is the mass of the electrolyte material in the container Cj;

[0023] S106. Measure the impedance of the k portions of electrolyte thin films in step S105 at temperature T1, which are R31, R32, ……, R3k respectively;

[0024] S107. Take m3 / (S1×h21), m3 / (S1×h22), ……, m3 / (S1×h2k) as the independent variable P, take R31×S1 / h21, R32×S1 / h22, ……, R3k×S1 / h2k as the dependent variable R3, and use R3 = f + d×P for fitting to obtain the coefficients f and d, where f is the compaction density intercept factor and d is the compaction density influence factor.

[0025] Further, before step S100, it also includes:

[0026] A. Bake the electrolyte material in a vacuum drying oven at a temperature higher than 373K for more than 24h;

[0027] B. Weigh n portions of the baked electrolyte material A1, A2, ……, An with a mass of m2 each;

[0028] C. Drop Y1×m2, Y2×m2, ……, Yn×m2 of deionized water into the n portions of electrolyte materials A1, A2, ……, An respectively to obtain the hydrated electrolyte materials B1, B2, ……, Bn, where 0 < Y1 < Y2 < …… < Yn < 1;

[0029] D. Place the n portions of electrolyte materials B1, B2, ……, Bn into containers C1, C2, ……, Cn respectively and seal them;

[0030] E. Bake the containers C1, C2, ……, Cn in an oven at a temperature higher than 373K for more than 24h;

[0031] F. Allow containers C1, C2, ..., Cn to cool naturally. During the cooling process, shake the containers for at least 1 hour using an automatic mixer or manually to ensure that the moisture in the electrolyte material is evenly distributed.

[0032] Furthermore, the temperature T1 is: 273K <= T1 <= 473K;

[0033] Temperatures T21, T22, ..., T2m are: 273K <= T21 <T22<……<T2m<=473K。

[0034] Furthermore, the electrolyte material of the thermal battery is a mixture of molten salt material and adsorbent material in any proportion.

[0035] Furthermore, the molten salt material is a solid solution or mixture formed from one or more of the following materials: LiCl, KCl, LiF, LiBr, KBr, LiI, NaBr, LiNO3, KNO3, RbNO3, NaNO3, Li2CO3, Li2SO4, and Li3PO4.

[0036] Furthermore, the adsorbent materials are MgO, Al2O3, and Li7La3Zr2O. 12 Materials such as SiO2 and BN.

[0037] Secondly, the present invention provides an impedance-based system for detecting the moisture content of electrolyte materials in thermal batteries, the system comprising:

[0038] The thermal battery impedance test unit is used to measure the impedance of a thermal battery in an inactive state.

[0039] The thermal battery electrolyte moisture content calculation unit is used to calculate the moisture content in the electrolyte material of the thermal battery based on impedance and using a nonlinear correlation model between the moisture content and impedance of the electrolyte material.

[0040] The nonlinear correlation model between the moisture content and impedance of the electrolyte material is as follows:

[0041] Y=a×{[R0×S0 / (n0×h0)]×exp[c×(1 / T1-1 / T0)]+d×(m3×S0×h0-m0×S1×h1) / (S0×h0

[0042] ×S1×h)} -b

[0043] Where a is the electrolyte material factor, b is the moisture influence factor, c is the temperature influence factor, d is the compaction density influence factor, R0 is the impedance of the thermal battery in the inactive state, n0 is the number of individual cells in the thermal battery, S0 is the area of ​​the individual cell, h0 is the thickness of the electrolyte material layer in the individual cell, m0 is the mass of the electrolyte material in the individual cell, m3 is the mass of the electrolyte sheet in the pre-test, S1 is the area of ​​the electrolyte sheet in the pre-test, h1 is the thickness of the electrolyte sheet in the pre-test, T1 is the ambient temperature in the pre-test, and T0 is the ambient temperature when measuring the impedance of the thermal battery in the inactive state.

[0044] Furthermore, the execution process of the thermal battery impedance testing unit is as follows:

[0045] The impedance of a thermal battery at temperature T0 is obtained by measuring its AC impedance spectrum or DC IV curve; where 273K <= T0 <= 473K, and K is the absolute temperature unit Kelvin.

[0046] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0047] This invention proposes a method and system for detecting the moisture content of electrolyte materials in thermal batteries based on impedance. This invention is applied after the individual thermal battery cells have been pressed or after the battery assembly is complete. Considering the influence of moisture distribution uniformity, ambient temperature, and compaction density on the impedance of the electrolyte material, a nonlinear correlation model between impedance and the moisture content of the electrolyte material is proposed. Using this model, the moisture content of the electrolyte material in the complete thermal battery and individual cells can be obtained in real time. This method is fast, accurate, non-destructive to the product, applicable to different temperature environments, and allows for online non-destructive testing. Attached Figure Description

[0048] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0049] Figure 1 This is a flowchart of the impedance-based method for detecting the moisture content of electrolyte materials in thermal batteries according to the present invention.

[0050] Figure 2 This is a graph showing the relationship between electrolyte impedance R and moisture content Y in this invention.

[0051] Figure 3 This is a graph showing the relationship between the impedance R of the electrolyte sheet and the temperature T in this invention;

[0052] Figure 4 This is a graph showing the relationship between the impedance of the electrolyte sheet multiplied by the ratio of area to thickness, R×S / h, and the compaction density, P, in this invention.

[0053] Figure 5 This is a block diagram of the impedance-based moisture content detection system for thermal battery electrolyte materials according to the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0055] Each cell in a thermal battery is formed by pressing together three layers: a positive electrode, an electrolyte, and a negative electrode. The negative electrode is typically a highly reactive lithium alloy such as LiB, LiSi, or LiAl, while the positive electrode is typically FeS2 or Fe... x Co 1-x Materials such as S2, CoS2, V2O5, and NiCl2 are used, with molten salt as the electrolyte. Because molten salt electrolytes are highly hygroscopic and often contain a certain amount of moisture, the moisture released from the molten salt during long-term storage or operation reacts with the positive and negative electrode materials, leading to a decline in battery performance. Therefore, moisture in the electrolyte material is one of the key factors affecting the performance of thermal batteries. In the production and testing of thermal batteries, the trace moisture content in the electrolyte must be strictly controlled and characterized.

[0056] Currently, the commonly used methods for detecting the moisture content of materials are mainly the Karl Fischer method and the thermogravimetric method. Both methods can only be used for sampling tests on a small amount of electrolyte material. When testing the moisture content of electrolyte material in a single cell or product of a thermal battery, the thermal battery must be destroyed to obtain the electrolyte material before testing can be performed. Furthermore, the sample preparation and measurement process is easily affected by the ambient humidity and needs to be carried out in a dry environment. The process is complex, time-consuming, and has stringent environmental requirements. It is also a destructive test.

[0057] Furthermore, an existing method for detecting the moisture content of battery electrode sheets measures the moisture content of the battery electrode material by measuring the resistance of the electrode sheet. However, this method cannot be applied to the moisture detection of electrolyte materials in hot batteries. First, since electrode resistance accounts for only a small portion of the battery resistance, this method is only applicable to the moisture content detection of electrode materials during the battery electrode manufacturing process, and cannot be applied after the battery cells have been pressed or the entire assembly is complete. Second, due to the different conduction mechanisms in electrode materials and electrolyte materials, the linear correlation model between impedance and moisture content proposed in this method cannot be applied to molten salt electrolytes in hot batteries. Third, this method does not eliminate the influence of uneven moisture distribution on the impedance of molten salt electrolytes. Fourth, this method does not eliminate the influence of ambient temperature on the impedance of molten salt electrolytes. Fifth, the electrodes in this method are produced using a coating process, while hot battery cells are generally produced using a powder pressing process. Different pressures lead to different electrolyte compaction densities and resistivities; this method does not eliminate the impact of impedance differences caused by variations in compaction density on the accuracy of moisture content detection.

[0058] To address the above issues, this invention proposes an impedance-based method for detecting the moisture content of electrolyte materials in thermal batteries. The basic principle is that a thermal battery consists of individual battery cells, a heating element, and current collectors connected in series. In the unactivated state, the current collector of the heating element is a good conductor, and the battery impedance is determined by the impedance of the individual battery cells. The impedance of a single thermal battery cell is the result of the series impedances of the positive electrode, negative electrode, molten salt electrolyte, and their interface. The positive and negative electrode materials of the individual battery cells are good conductors, and the interface has a very small thickness; their impedance is very small compared to the electrolyte. Therefore, the impedance of a single thermal battery cell is mainly determined by the impedance of the molten salt electrolyte layer.

[0059] For a thermal cell containing n0 individual cells with area S0 and electrolyte thickness h0, and its impedance in the inactive state at temperature T0 is R0, then the resistivity p0 of the molten salt electrolyte layer is:

[0060] p0 = R0 × S0 / (n0 × h0)

[0061] Molten salt electrolytes have extremely high resistivity when completely anhydrous, but they are highly hygroscopic. As the water content gradually increases, the number of freely moving ions in the electrolyte gradually increases, its ionic conductivity gradually increases, and its resistivity gradually decreases. The resistivity p0 of the molten salt electrolyte layer and the water content Y have a power-law relationship:

[0062] Y = a × [p0] -b

[0063] a and b are determined through prior experiments.

[0064] Molten salt electrolyte materials containing a certain amount of moisture have ions as the dominant charge carriers. As the temperature increases, the migration rate of ions increases and the resistivity decreases. The resistivity p0 at temperature T0 and the resistivity p1 at the pre-test ambient temperature T1 follow an exponential relationship.

[0065] p0 = p1 × exp[c / (1 / T0 - 1 / T1)]

[0066] Wherein, c is determined through prior experiments.

[0067] The preparation of thermal battery cells generally employs a powder pressing process. The greater the pressing pressure, the greater the compaction density of the electrolyte sheet, and the lower the resistivity of the electrolyte sheet. The resistivity p of the electrolyte sheet and the compaction density P follow a linear relationship.

[0068] p = (f + d × P)

[0069] Where f and d are determined through prior experiments, and the compaction density P = m3 / S1×h1, where m3 is the mass of the electrolyte material, S1 is the electrolyte area, and h1 is the thickness of the electrolyte layer. Under the same moisture content, the difference between the resistivity p0 and p1 of two electrolyte sheets with compaction densities P0 = m0 / (S0×h0) and P1 = m3 / (S1×h1) is: p1-p0 = d×(m3×S0×h0-m0×S1×h1) / (S0×h0×S1×h1).

[0070] Therefore, considering the effects of moisture content, temperature, and compaction density, the correlation model between moisture content in the electrolyte material of a thermal battery and the impedance of the thermal battery in its inactive state is as follows:

[0071] Y=a×{[R0×S0 / (n0×h0)]×exp[c×(1 / T1-1 / T0)]+d×(m3×S0×h0-m0×S1×h1) / (S0×h0×S1×h)} -b .

[0072] In the preliminary test, to eliminate the influence of uneven moisture distribution in the molten salt on the electrolyte impedance, the electrolyte material was first thoroughly dried to remove water. Then, a certain mass of water was added to the electrolyte, and it was placed in a sealed container and baked at a temperature above 373K for more than 24 hours to desorb and vaporize the water in the electrolyte material in the sealed container. Afterwards, during the cooling and re-adsorption of water by the electrolyte material, an automatic mixing device or manual shaking was used to ensure that the electrolyte material in the container adsorbed water evenly, thereby effectively eliminating the influence of uneven moisture on impedance.

[0073] Simultaneously, during the preliminary testing, this invention also considered the influence of ambient temperature and compaction density on the electrolyte material, and determined the electrolyte material factor a, moisture influence factor b, temperature influence factor c, and compaction density influence factor d in the nonlinear correlation model between impedance and electrolyte material moisture content. This invention is applied to the complete assembly state of the battery, using the proposed nonlinear impedance and electrolyte material moisture content detection model to obtain the moisture content of the electrolyte material in the complete thermal battery and individual battery cells in real time. It is fast, accurate, non-destructive to the product, applicable to different temperature environments, and can perform online non-destructive testing.

[0074] Example 1

[0075] like Figure 1 As shown, the present invention provides a method for detecting the moisture content of electrolyte materials in thermal batteries based on impedance. The method includes:

[0076] Measure the impedance of the thermal battery in its inactive state;

[0077] Based on the measured impedance of the thermal battery in its inactive state, the moisture content in the electrolyte material is calculated using a nonlinear correlation model between the moisture content and impedance of the electrolyte material. The nonlinear correlation model between the moisture content and impedance of the electrolyte material is as follows:

[0078] Y=a×{[R0×S0 / (n0×h0)]×exp[c×(1 / T1-1 / T0)]+d×(m3×S0×h0-m0×S1×h1) / (S0×h0

[0079] ×S1×h)} -b

[0080] Where a is the electrolyte material factor, b is the moisture influence factor, c is the temperature influence factor, d is the compaction density influence factor, R0 is the impedance of the thermal battery in the inactive state, n0 is the number of individual cells in the thermal battery, S0 is the area of ​​the individual cell, h0 is the thickness of the electrolyte material layer in the individual cell, m0 is the mass of the electrolyte material in the individual cell, m3 is the mass of the electrolyte sheet in the pre-test, S1 is the area of ​​the electrolyte sheet in the pre-test, h1 is the thickness of the electrolyte sheet in the pre-test, T1 is the ambient temperature in the pre-test, and T0 is the ambient temperature when measuring the impedance of the thermal battery in the inactive state.

[0081] As a further implementation, the impedance of the thermal battery in its inactive state is measured, including:

[0082] The impedance of a thermal battery at temperature T0 is obtained by measuring its AC impedance spectrum or DC current-voltage (IV) curve; where 273K <= T0 <= 473K.

[0083] As a further implementation, the methods for obtaining the electrolyte material factor, moisture influence factor, temperature influence factor, and compaction density influence factor are as follows:

[0084] A. Bake the electrolyte material in a vacuum drying oven at a temperature greater than 373K for more than 24 hours;

[0085] B. Weigh n portions of the baked electrolyte material A1, A2,..., An with a mass of m2 respectively;

[0086] C. Add Y1×m2, Y2×m2,..., Yn×m2 of deionized water to the n portions of electrolyte material A1, A2,..., An respectively to obtain the hydrated electrolyte materials B1, B2,..., Bn, where 0 < Y1 < Y2 <... < Yn < 1;

[0087] D. Place the n portions of electrolyte materials B1, B2,..., Bn into containers C1, C2,..., Cn respectively and seal them;

[0088] E. Bake the containers C1, C2,..., Cn in an oven at a temperature greater than 373K for more than 24 hours;

[0089] F. Let the containers C1, C2,..., Cn cool down naturally. During the cooling process, use an automatic mixer or manually shake each container for more than 1 hour to make the moisture in the electrolyte materials in the containers evenly distributed;

[0090] G. Take out the electrolyte materials B1, B2,..., Bn from the containers C1, C2,..., Cn. Weigh n portions of electrolyte materials D1, D2,..., Dn with a mass of m1 from each portion of the electrolyte. Press the n portions of electrolyte materials with a mass of m1 into electrolyte thin sheets E1, E2,..., En with an area of S1 and a thickness of h1 respectively;

[0091] H. Measure the impedance of the above n portions of electrolyte thin sheets at temperature T1, which are R01, R02,..., R0n respectively, where 273K <= T1 <= 473K;

[0092] I. Use R11, R12,..., R1n as the independent variable R1, and use the electrolyte materials with moisture contents of Y1, Y2,..., Yn in the n portions of electrolyte materials as the dependent variable Y. Adopt Y = a×[R1×S1 / h1] -b for fitting to obtain the coefficients a and b;

[0093] J. Place any one of the electrolyte thin sheets E1, E2,..., En at temperatures T21, T22,..., T2m respectively and measure the impedance R21, R22,..., R2m at this temperature, where 273K <= T21 < T22 <... < T2m <= 473K, and m is an integer greater than 1;

[0094] K. Using T21, T22, ..., T2m as independent variables T2 and R21, R22, ..., R2m as dependent variables R2, the coefficients c and e are obtained by fitting the data using R2 = e × exp(c / T2), where e is the pre-exponential factor of the temperature test and c is the temperature influence factor.

[0095] L. Take out electrolyte material Bj from container Cj, and weigh out k portions of electrolyte, each with a mass of m3. By controlling the pressing pressure, obtain k electrolyte sheets F1, F2, ..., Fk with area S1 and thicknesses h21, h22, ..., h2k, respectively, where j is an integer and 1 <= j <= n, k is an integer greater than 1, and 0 <= n ... <m3<=(m2-m1) / k;

[0096] M. Measure the impedance of k electrolyte sheets in step L at temperature T1, which are R31, R32, ..., R3k respectively;

[0097] N. Using m3 / (S1×h21), m3 / (S1×h22), ..., m3 / (S1×h2k) as independent variables P, and R31×S1 / h21, R32×S1 / h22, ..., R3k×S1 / h2k as dependent variables R3, we fit the data using R3=f+d×P to obtain the coefficients f and d, where f is the compaction density intercept factor and d is the compaction density influence factor.

[0098] As a further implementation, the electrolyte material of the thermal battery is a mixture of molten salt material and adsorbent material in any proportion. The molten salt material is a solid solution or mixture formed from one or more of the following: LiCl, KCl, LiF, LiBr, KBr, LiI, NaBr, LiNO3, KNO3, RbNO3, NaNO3, Li2CO3, Li2SO4, and Li3PO4. The adsorbent material is MgO, Al2O3, or Li7La3Zr2O. 12 Materials such as SiO2 and BN.

[0099] Example 2

[0100] like Figure 2 , Figure 3 and Figure 4 As shown, the difference between this embodiment and Embodiment 1 is that the test object is the entire thermal battery, the electrolyte thickness and area of ​​the individual thermal battery cells are different from the area and thickness of the individual cells in the pre-test, the test environment temperature is different from the pre-test environment temperature, and the compaction density of the individual thermal battery cells is different from the compaction density of the individual cells in the pre-test.

[0101] The method includes:

[0102] Measure the impedance of the thermal battery in its inactive state;

[0103] Based on the measured impedance of the thermal battery in its inactive state, the moisture content in the electrolyte material is calculated using a nonlinear correlation model between the moisture content and impedance of the electrolyte material. The nonlinear correlation model between the moisture content and impedance of the electrolyte material is as follows:

[0104] Y=a×{[R0×S0 / (n0×h0)]×exp[c×(1 / T1-1 / T0)]+d×(m3×S0×h0-m0×S1×h1) / (S0×h0

[0105] ×S1×h1)} -b

[0106] Where a is the electrolyte material factor, b is the moisture influence factor, c is the temperature influence factor, d is the compaction density influence factor, R0 is the impedance of the thermal battery in the inactive state, n0 is the number of individual cells in the thermal battery, S0 is the area of ​​the individual cell, h0 is the thickness of the electrolyte material layer in the individual cell, m0 is the mass of the electrolyte material in the individual cell, m3 is the mass of the electrolyte sheet in the pre-test, S1 is the area of ​​the electrolyte sheet in the pre-test, h1 is the thickness of the electrolyte sheet in the pre-test, T1 is the ambient temperature in the pre-test, and T0 is the ambient temperature when measuring the impedance of the thermal battery in the inactive state.

[0107] In practice:

[0108] S10. Bake the electrolyte material in a vacuum drying oven at a temperature greater than 373K for more than 24 hours.

[0109] S20, also known as 10 portions of 5g each of baked electrolyte materials A1, A2, ..., A10;

[0110] S30. Add 0.1%×5g, 0.15%×5g, 0.20%×5g, 0.3%×5g, 0.4%×5g, 0.5%×5g, 0.6%×5g, 0.7%×5g, 0.8%×5g, and 0.9%×5g of deionized water dropwise to 10 portions of electrolyte materials A1, A2, ..., A10, respectively, to obtain aqueous electrolyte materials B1, B2, ..., B10.

[0111] S40. Place 10 portions of electrolyte materials B1, B2, ..., B10 into containers C1, C2, ..., C10 respectively, and seal them.

[0112] S50. Bake containers C1, C2, ..., C10 in an oven at a temperature greater than 373K for at least 24 hours.

[0113] S60. Allow containers C1, C2, ..., C10 to cool down naturally. During the cooling process, shake the containers for more than 1 hour using an automatic mixing device or manually to ensure that the electrolyte material in the containers is evenly distributed with moisture.

[0114] S70. Take out electrolyte materials B1, B2, ..., B10 from containers C1, C2, ..., C10. Weigh out 1g portions of electrolyte material D1, D2, ..., D10 from each portion of electrolyte. Press each 1g portion of electrolyte material into a piece with an area of ​​8cm². 2 Electrolyte sheets E1, E2, ..., E10 with a thickness of 0.08 cm;

[0115] S80. The impedance of the above 10 electrolyte sheets was measured at a temperature of 298K, and the values ​​were 4.25 × 10⁻⁶. 12 Ω, 5.86×10 11 Ω, 1.44×10 11 Ω, 1.98×10 10 Ω, 4.89×10 9 Ω, 1.63×10 9 Ω, 6.67×10 8 Ω, 3.14×10 8 Ω, 4.1.63×10 8 Ω, 9.18×10 7 Ω;

[0116] S90, with 4.25×10 12 Ω, 5.86×10 11 Ω, 1.44×10 11 Ω, 1.98×10 10 Ω, 4.89×10 9 Ω, 1.63×10 9 Ω, 6.67×10 8 Ω, 3.14×10 8 Ω, 4.1.63×10 8 Ω, 9.18×10 7 Ω is used as the independent variable R1, and 0.1%, 0.15%, 0.20%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, and 0.9% are used as the dependent variable Y. The formula is Y = a × [R1 × 8 / 0.08]. -b The fitting yielded coefficients a = 0.38 and b = 0.2.

[0117] S100. Electrolyte sheet E5 was placed at temperatures of 298K, 308K, 318K, 328K, and 338K, and the impedance at each temperature was measured to be 4.89 × 10⁻⁶. 9Ω, 2.15×10 9 Ω, 9.98×10 8 Ω, 4.84×10 8 Ω, 2.45×10 8 Ω;

[0118] S110, with 298K, 308K, 318K, 328K, and 338K as independent variables T2, and 4.89 × 10 9 Ω, 2.15×10 9 Ω, 9.98×10 8 Ω, 4.84×10 8 Ω, 2.45×10 8 Using Ω as the dependent variable R2, the coefficients c = 7530 and e = 0.0052 were obtained by fitting the data using R2 = e × exp(c / T2).

[0119] S120. Take out electrolyte material B5 from container C5, weigh out 3 portions of electrolyte, each with a mass of 1g, and obtain an area of ​​8cm² by controlling the pressing pressure. 2 Three electrolyte sheets, F1, F2, and F3, with thicknesses of 0.088 cm, 0.08 cm, and 0.072 cm, respectively;

[0120] S130. The impedances of the three electrolyte sheets F1, F2, and F3 from step L were measured at 298 K, and were 5.85 × 10⁻⁶ respectively. 9 Ω, 4.89×10 9 Ω, 3.95×10 9 Ω;

[0121] S140, using 1 / (8×0.088), 1 / (8×0.08), and 1 / (8×0.072)) as independent variables P, with 5.85×10 9 ×8 / 0.088, 4.89×10 9 ×8 / 0.08, 3.95×10 9 Using ×8 / 0.072 as the dependent variable R3, and fitting the data using R3 = f + d × P, the coefficient f = -2.9 × 10⁻⁸ is obtained. 11 and d = 9.49 × 10 11 .

[0122] S140. The area of ​​a single solar cell was measured to be 16 cm² at an environment of 303K. 2 The impedance of a hot battery in its unactivated state, with an electrolyte thickness of 0.1 cm, an electrolyte mass of 1.8 g, and 15 individual cells, is 1.2 × 10⁻⁶. 11 Ω, calculate the moisture content Y in the electrolyte material: Y = 0.38 × {[1.2 × 1011 ×16 / (15×0.1)]×exp[7530×(1 / 298-1 / 303)]+9.49×10 11 ×(1×16×0.1-1.8×8×0.08) / (16×0.1×8×0.08)} -0.2 =0.13%.

[0123] Example 3

[0124] like Figure 2 , Figure 3 and Figure 4 As shown, the difference between this embodiment and embodiments 1 and 2 is that the test object is a thermal battery cell, and the electrolyte thickness, area, compaction density, and test environment temperature of the thermal battery cell are the same as in the preliminary test.

[0125] The method includes:

[0126] Measure the impedance of a single thermal cell;

[0127] Based on the measured impedance of a single thermal battery cell, the moisture content in the electrolyte material of the single thermal battery cell is calculated using a nonlinear correlation model between the moisture content and impedance of the electrolyte material. The nonlinear correlation model between the moisture content and impedance of the electrolyte material is as follows:

[0128] Y=a×{[R0×S0 / (n0×h0)]×exp[c×(1 / T1-1 / T0)]+d×(m3×S0×h0-m0×S1×h1) / (S0×h0

[0129] ×S1×h1)} -b

[0130] Where a is the electrolyte material factor, b is the moisture influence factor, c is the temperature influence factor, d is the compaction density influence factor, R0 is the impedance of the thermal battery in the inactive state, n0 is the number of individual cells in the thermal battery, S0 is the area of ​​the individual cell, h0 is the thickness of the electrolyte material layer in the individual cell, m0 is the mass of the electrolyte material in the individual cell, m3 is the mass of the electrolyte sheet in the pre-test, S1 is the area of ​​the electrolyte sheet in the pre-test, h1 is the thickness of the electrolyte sheet in the pre-test, T1 is the ambient temperature in the pre-test, and T0 is the ambient temperature when measuring the impedance of the thermal battery in the inactive state.

[0131] In practice:

[0132] S10. Bake the electrolyte material in a vacuum drying oven at a temperature greater than 373K for more than 24 hours.

[0133] S20, also known as 10 portions of 5g each of baked electrolyte materials A1, A2, ..., A10;

[0134] S30. Add 0.1%×5g, 0.15%×5g, 0.20%×5g, 0.3%×5g, 0.4%×5g, 0.5%×5g, 0.6%×5g, 0.7%×5g, 0.8%×5g, and 0.9%×5g of deionized water dropwise to 10 portions of electrolyte materials A1, A2, ..., A10, respectively, to obtain aqueous electrolyte materials B1, B2, ..., B10.

[0135] S40. Place 10 portions of electrolyte materials B1, B2, ..., B10 into containers C1, C2, ..., C10 respectively, and seal them.

[0136] S50. Bake containers C1, C2, ..., C10 in an oven at a temperature greater than 373K for at least 24 hours.

[0137] S60. Allow containers C1, C2, ..., C10 to cool down naturally. During the cooling process, shake the containers for more than 1 hour using an automatic mixing device or manually to ensure that the electrolyte material in the containers is evenly distributed with moisture.

[0138] S70. Take out electrolyte materials B1, B2, ..., B10 from containers C1, C2, ..., C10. Weigh out 1g portions of electrolyte material D1, D2, ..., D10 from each portion of electrolyte. Press each 1g portion of electrolyte material into a piece with an area of ​​8cm². 2 Electrolyte sheets E1, E2, ..., E10 with a thickness of 0.08 cm;

[0139] S80. The impedance of the above 10 electrolyte sheets was measured at a temperature of 298K, and the values ​​were 4.25 × 10⁻⁶. 12 Ω, 5.86×10 11 Ω, 1.44×10 11 Ω, 1.98×10 10 Ω, 4.89×10 9 Ω, 1.63×10 9 Ω, 6.67×10 8 Ω, 3.14×10 8 Ω, 4.1.63×10 8 Ω, 9.18×10 7 Ω;

[0140] S90, with 4.25×10 12 Ω, 5.86×10 11 Ω, 1.44×10 11 Ω, 1.98×1010 Ω, 4.89×10 9 Ω, 1.63×10 9 Ω, 6.67×10 8 Ω, 3.14×10 8 Ω, 4.1.63×10 8 Ω, 9.18×10 7 Ω is used as the independent variable R1, and 0.1%, 0.15%, 0.20%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, and 0.9% are used as the dependent variable Y. The formula is Y = a × [R1 × 8 / 0.08]. -b The fitting yielded coefficients a = 0.38 and b = 0.2.

[0141] S100. Electrolyte sheet E5 was placed at temperatures of 298K, 308K, 318K, 328K, and 338K, and the impedance at each temperature was measured to be 4.89 × 10⁻⁶. 9 Ω, 2.15×10 9 Ω, 9.98×10 8 Ω, 4.84×10 8 Ω, 2.45×10 8 Ω;

[0142] S110, with 298K, 308K, 318K, 328K, and 338K as independent variables T2, and 4.89 × 10 9 Ω, 2.15×10 9 Ω, 9.98×10 8 Ω, 4.84×10 8 Ω, 2.45×10 8 Using Ω as the dependent variable R2, the coefficients c = 7530 and e = 0.0052 were obtained by fitting the data using R2 = e × exp(c / T2).

[0143] S120. Take out electrolyte material B5 from container C5, weigh out 3 portions of electrolyte, each with a mass of 1g, and obtain an area of ​​8cm² by controlling the pressing pressure. 2 Three electrolyte sheets, F1, F2, and F3, with thicknesses of 0.088 cm, 0.08 cm, and 0.072 cm, respectively;

[0144] S130. The impedances of the three electrolyte sheets F1, F2, and F3 from step L were measured at 298 K, and were 5.85 × 10⁻⁶ respectively. 9 Ω, 4.89×10 9 Ω, 3.95×10 9 Ω;

[0145] S140, using 1 / (8×0.088), 1 / (8×0.08), and 1 / (8×0.072)) as independent variables P, with 5.85×10 9 ×8 / 0.088, 4.89×10 9 ×8 / 0.08, 3.95×10 9 Using ×8 / 0.072 as the dependent variable R3, and fitting the data using R3 = f + d × P, the coefficient f = -2.9 × 10⁻⁸ is obtained. 11 and d = 9.49 × 10 11 .

[0146] S140. Measure an area of ​​8 cm² in an environment with a temperature of 298K. 2 The single-cell thermal battery with an electrolyte thickness of 0.08 cm and an electrolyte mass of 1 g has an impedance of 1.0 × 10⁻⁶. 8 Ω, calculate the moisture content Y in the electrolyte material: Y = 0.38 × {[1.0 × 10 8 ×8 / (1×0.08)]×exp[7530×(1 / 298-1 / 298)]+9.49×10 11 ×(1×8×0.08-1×8×0.08) / (8×0.08×8×0.08)} -0.2 =0.38%.

[0147] Example 4

[0148] like Figure 5 As shown, the difference between this embodiment and Embodiment 1 is that this embodiment provides an impedance-based system for detecting the moisture content of electrolyte materials in thermal batteries. This system includes:

[0149] The thermal battery impedance test unit is used to measure the impedance of a thermal battery in an inactive state.

[0150] The thermal battery electrolyte moisture content calculation unit is used to calculate the moisture content in the electrolyte material of the thermal battery based on impedance and using a nonlinear correlation model between the moisture content and impedance of the electrolyte material.

[0151] The nonlinear correlation model between the moisture content and impedance of the electrolyte material is as follows:

[0152] Y=a×{[R0×S0 / (n0×h0)]×exp[c×(1 / T1-1 / T0)]+d×(m1×S0×h0-m0×S1×h1) / (S0×h0

[0153] ×S1×h)} -b

[0154] Where a is the electrolyte material factor, b is the moisture influence factor, c is the temperature influence factor, d is the compaction density influence factor, R0 is the impedance of the thermal battery in the inactive state, n0 is the number of individual cells in the thermal battery, S0 is the area of ​​the individual cell, h0 is the thickness of the electrolyte material layer in the individual cell, m0 is the mass of the electrolyte material in the individual cell, m3 is the mass of the electrolyte sheet in the pre-test, S1 is the area of ​​the electrolyte sheet in the pre-test, h1 is the thickness of the electrolyte sheet in the pre-test, T1 is the ambient temperature in the pre-test, and T0 is the ambient temperature when measuring the impedance of the thermal battery in the inactive state.

[0155] In this embodiment, the impedance is obtained by measuring the AC impedance spectrum or DC IV curve of the thermal battery at temperature T0; where 273K <= T0 <= 473K.

[0156] The execution process of each unit can be carried out according to the steps of the impedance-based method for detecting the moisture content of thermal battery electrolyte materials in Example 1, and will not be described in detail in this example.

[0157] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting moisture content in electrolyte materials for thermal batteries based on impedance, characterized in that, The method includes: Measuring the impedance of the thermal battery in an unactivated state; Calculating the moisture content in the electrolyte material of the thermal battery according to the impedance based on a non-linear correlation model between the moisture content of the electrolyte material and the impedance; the non-linear correlation model between the moisture content of the electrolyte material and the impedance is: Y=a×{[R0×S0 / (n0×h0)]×exp[c×(1 / T1-1 / T0)] +d×(m3×S0×h0-m0×S1×h1) / (S0×h0×S1×h1)} -b Where Y is the moisture content; a is the electrolyte material factor, b is the moisture influence factor, c is the temperature influence factor, d is the compaction density influence factor, R0 is the impedance of the thermal battery in an unactivated state, n0 is the number of single cell sheets in the thermal battery, S0 is the area of the single cell sheet, h0 is the thickness of the electrolyte material layer in the single cell sheet, m0 is the mass of the electrolyte material in the single cell sheet, m3 is the mass of the electrolyte sheet in the preliminary test, S1 is the area of the electrolyte sheet in the preliminary test, h1 is the thickness of the electrolyte sheet in the preliminary test, T1 is the ambient temperature in the preliminary test, and T0 is the ambient temperature when measuring the impedance of the thermal battery in an unactivated state; The method for obtaining the electrolyte material factor, moisture influence factor, temperature influence factor and compaction density influence factor is: S100. Take out electrolyte materials B1, B2, ……, Bn from containers C1, C2, ……, Cn, respectively weigh n portions of electrolyte materials D1, D2, ……, Dn with a mass of m1 from each portion of the electrolyte, and press the n portions of electrolyte materials with a mass of m1 into electrolyte thin sheets E1, E2, ……, En with an area of S1 and a thickness of h1, where n is an integer greater than 2; S101. Measure the impedance of the above n electrolyte thin sheets at temperature T1, which are R11, R12, ……, R1n respectively; S102. Using R11, R12, ..., R1n as independent variables R1, and the moisture content of n portions of electrolyte material Y1, Y2, ..., Yn as dependent variables Y, the formula Y = a × [R1 × S1 / h1] is adopted. -b By fitting the data, coefficients a and b are obtained, where a is the electrolyte material factor and b is the moisture influence factor. S103. Place any one of the electrolyte thin sheets E1, E2, ……, En at temperatures T21, T22, ……, T2m respectively, and measure the impedance R21, R22, ……, R2m at this temperature, where m is an integer greater than 1; S104. Use T21, T22, ……, T2m as the independent variable T2, and R21, R22, ……, R2m as the dependent variable R2, and perform fitting using R2 = e×exp(c / T2) to obtain the coefficients c and e, where e is the pre-factor of the temperature test and c is the temperature influence factor; S105. Take out the electrolyte material Bj from container Cj, respectively weigh k portions of electrolyte with a mass of m3 each, and obtain k electrolyte thin sheets F1, F2, ……, Fk with an area of S1 and thicknesses h21, h22, ……, h2k respectively by controlling the pressing pressure, where j is an integer and 1≤j≤n, k is an integer greater than 1, 0 < m3 <= (m2 - m1) / k, where m2 is the mass of the electrolyte material in container Cj; S106. Measure the impedance of the k portions of electrolyte thin sheets in step S105 at temperature T1, which are R31, R32, ……, R3k respectively; S107. Using m3 / (S1×h21), m3 / (S1×h22), ..., m3 / (S1×h2k) as independent variables P, and R31×S1 / h21, R32×S1 / h22, ..., R3k×S1 / h2k as dependent variables R3, the coefficients f and d are obtained by fitting the data using R3=f+d×P, where f is the compaction density intercept factor and d is the compaction density influence factor.

2. The method for detecting moisture content in thermal battery electrolyte materials based on impedance according to claim 1, characterized in that, The method for measuring the impedance of a thermal battery in its inactive state includes: The impedance of a thermal battery is obtained by measuring its AC impedance spectrum or DC IV curve at temperature T0; where 273K <= T0 <= 473K.

3. The method for detecting moisture content in thermal battery electrolyte materials based on impedance according to claim 1, characterized in that, The steps preceding step S100 also include: A. Bake the electrolyte material in a vacuum drying oven at a temperature greater than 373K for more than 24 hours; B. Weigh out n portions of the baked electrolyte material A1, A2, ..., An, each with a mass of m2; C. Add Y1×m2, Y2×m2, ..., Yn×m2 of deionized water dropwise to n portions of electrolyte materials A1, A2, ..., An respectively to obtain aqueous electrolyte materials B1, B2, ..., Bn, where 0 <Y1<Y2<……<Yn<1; D. Place n portions of electrolyte materials B1, B2, ..., Bn into containers C1, C2, ..., Cn respectively, and seal them; E. Bake containers C1, C2, ..., Cn in an oven at a temperature greater than 373K for at least 24 hours; F. Allow containers C1, C2, ..., Cn to cool naturally. During the cooling process, shake the containers for at least 1 hour using an automatic mixer or manually to ensure that the moisture in the electrolyte material is evenly distributed.

4. The method for detecting moisture content in thermal battery electrolyte materials based on impedance according to claim 1, characterized in that, The temperature T1 is: 273K <= T1 <= 473K; The temperatures T21, T22, ..., T2m are: 273K <= T21 <T22<……<T2m<=473K。 5. The method for detecting moisture content in thermal battery electrolyte materials based on impedance according to claim 1, characterized in that, The electrolyte material of the thermal battery is a mixture of molten salt material and adsorbent material in any proportion.

6. The method for detecting moisture content in thermal battery electrolyte materials based on impedance according to claim 5, characterized in that, The molten salt material is a solid solution or mixture formed from one or more of the following materials: LiCl, KCl, LiF, LiBr, KBr, LiI, NaBr, LiNO3, KNO3, RbNO3, NaNO3, Li2CO3, Li2SO4, and Li3PO4.

7. The method for detecting moisture content in thermal battery electrolyte materials based on impedance according to claim 5, characterized in that, The adsorbent material is MgO, Al2O3, or Li7La3Zr2O. 12 One or more of SiO2 and BN materials.

8. A system for detecting the moisture content of electrolyte materials in thermal batteries based on impedance, characterized in that, The system includes: The thermal battery impedance test unit is used to measure the impedance of a thermal battery in an inactive state. The thermal battery electrolyte moisture content calculation unit is used to calculate the moisture content in the electrolyte material of the thermal battery based on the impedance and using a nonlinear correlation model between the moisture content of the electrolyte material and the impedance. The nonlinear correlation model between the moisture content and impedance of the electrolyte material is as follows: Y=a×{[R0×S0 / (n0×h0)]×exp[c×(1 / T1-1 / T0)] +d×(m3×S0×h0-m0×S1×h1) / (S0×h0×S1×h1)} -b Where, Y is the moisture content; a is the electrolyte material factor, b is the moisture influence factor, c is the temperature influence factor, d is the compaction density influence factor, R0 is the impedance of the thermal battery in the unactivated state, n0 is the number of single battery sheets in the thermal battery, S0 is the area of the single battery sheet, h0 is the thickness of the electrolyte material layer in the single battery sheet, m0 is the mass of the electrolyte material in the single battery sheet, m3 is the mass of the electrolyte sheet in the preliminary test, S1 is the area of the electrolyte sheet in the preliminary test, h1 is the thickness of the electrolyte sheet in the preliminary test, T1 is the ambient temperature in the preliminary test, and T0 is the ambient temperature when measuring the impedance of the thermal battery in the unactivated state; The methods for obtaining the electrolyte material factor, moisture influence factor, temperature influence factor, and compaction density influence factor are as follows: S100. Take out electrolyte materials B1, B2,..., Bn from containers C1, C2,..., Cn. Weigh n portions of electrolyte materials D1, D2,..., Dn with a mass of m1 from each portion of the electrolyte. Press the n portions of electrolyte materials with a mass of m1 into electrolyte thin sheets E1, E2,..., En with an area of S1 and a thickness of h1, where n is an integer greater than 2; S101. Measure the impedances of the above n electrolyte thin sheets at temperature T1, which are R11, R12,..., R1n respectively; S102. Using R11, R12, ..., R1n as independent variables R1, and the moisture content of n portions of electrolyte material Y1, Y2, ..., Yn as dependent variables Y, the formula Y = a × [R1 × S1 / h1] is adopted. -b By fitting the data, coefficients a and b are obtained, where a is the electrolyte material factor and b is the moisture influence factor. S103. Place any one of the electrolyte thin sheets E1, E2,..., En at temperatures T21, T22,..., T2m respectively, and measure the impedance R21, R22,..., R2m at this temperature, where m is an integer greater than 1; S104. Use T21, T22,..., T2m as the independent variable T2, and R21, R22,..., R2m as the dependent variable R2, and perform fitting using R2 = e×exp(c / T2) to obtain the coefficients c and e, where e is the pre-factor of the temperature test and c is the temperature influence factor; S105. Take out the electrolyte material Bj from container Cj, weigh k portions of electrolyte with a mass of m3 each, and obtain k electrolyte thin sheets F1, F2,..., Fk with an area of S1 and thicknesses of h21, h22,..., h2k respectively by controlling the pressing pressure, where j is an integer and 1≤j≤n, k is an integer greater than 1, 0 < m3 < = (m2 - m1) / k, where m2 is the mass of the electrolyte material in container Cj; S106. Measure the impedances of the k portions of electrolyte thin sheets in step S105 at temperature T1, which are R31, R32,..., R3k respectively; S107. Use m3 / (S1×h21), m3 / (S1×h22),..., m3 / (S1×h2k) as the independent variable P, and R31×S1 / h21, R32×S1 / h22,..., R3k×S1 / h2k as the dependent variable R3, and perform fitting using R3 = f + d×P to obtain the coefficients f and d, where f is the compaction density intercept factor and d is the compaction density influence factor.

9. The impedance-based moisture content detection system for thermal battery electrolyte materials according to claim 8, characterized in that, The execution process of the thermal battery impedance test unit is as follows: The impedance of a thermal battery is obtained by measuring its AC impedance spectrum or DC IV curve at temperature T0; where 273K <= T0 <= 473K.

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