Method for detecting moisture content in sulfide solid electrolyte

Abstract

The invention provides a method for detecting the moisture content in sulfide solid electrolyte, and belongs to the field of battery testing. The method comprises the following steps: reacting hydrogen sulfide with sulfur dioxide to generate water and elemental sulfur precipitate, completely reacting hydrogen sulfide with excessive sulfur dioxide, and testing the total moisture content after the reaction by utilizing a coulometry method; under the acidic condition, H2S, entering the electrolyte of the titration cell, in the sulfide solid electrolyte sample to be tested is oxidized by I2 generated by electrolysis to generate S precipitate, and a Karl Fischer moisture meter is used for testing second moisture content; and finally, calculating the difference value between the total moisture content and the second moisture content to obtain the actual moisture content. The detection method provided by the invention is simple to operate and high in accuracy. Wherein hydrogen sulfide is converted into water, so that the detection is safer, and the method is more environment-friendly.

Description

Technical Field

[0001] The invention relates to the technical field of battery testing, and in particular to a method for detecting the moisture content in a sulfide solid electrolyte. Background Art

[0002] Lithium-ion batteries are widely used in various advanced devices such as electronic products and electric vehicles. However, the organic electrolytes used in lithium-ion batteries have risks such as leakage, flammability and explosion. In order to develop the next generation of lithium-ion batteries with high safety and high energy density, sulfide solid electrolytes such as LGPS and LPSC have received extensive attention from researchers. The main advantage of solid electrolytes is to increase the safety of batteries. However, some sulfide solid electrolytes are unstable and are easily hydrolyzed when exposed to air to produce H2S gas, which affects the electrochemical performance of the battery to a certain extent.

[0003] It can be seen that the determination of the moisture content in the sulfide solid electrolyte before battery assembly is of great significance; however, there is currently no public literature report or test standard.

[0004] Conventional methods for determining the moisture content of chemicals mainly include drying method, chromatography, spectroscopy, Karl Fischer method, etc. Karl Fischer method is the most specific and accurate method for water among various chemical methods for determining the moisture content of substances; Karl Fischer method includes titration method and coulometric method. The principle of coulometric method generally includes: when the Karl Fischer reagent in the electrolytic cell of the instrument reaches equilibrium, the water-containing sample to be tested is injected, and the water participates in the redox reaction of iodine and sulfur dioxide. In the presence of pyridine and methanol, pyridine hydroiodide and pyridine methylsulfate are generated, and the consumed iodine is electrolyzed at the anode, so that the redox reaction continues until all the water is exhausted; according to Faraday's law of electrolysis, the iodine produced by electrolysis is directly proportional to the amount of electricity consumed during electrolysis, that is, 1 mole of iodine oxidizes 1 mole of sulfur dioxide, requiring 1 mole of water, and the amount of electricity for electrolyzing iodine is equivalent to the amount of electricity for electrolyzing water, so the moisture content in the sample can be calculated. However, for sulfide solid electrolyte samples, the H2S therein will consume elemental iodine and react with SO2 to produce water, making it impossible to accurately measure the actual moisture content. Summary of the invention

[0005] In view of this, the present invention provides a method for detecting the moisture content in a sulfide solid electrolyte, which has high accuracy and is easy to operate.

[0006] The present invention provides a method for detecting the moisture content in a sulfide solid electrolyte, comprising the following steps:

[0007] A sample of the sulfide solid electrolyte to be tested with a first mass is heated under certain conditions, and under the protection of a first carrier gas, the gas produced by heating is introduced into a first titration unit of a Karl Fischer moisture meter. The first titration unit is filled with a first electrolyte solution, and the first electrolyte solution contains an iodine salt, methanol, an organic base, and an excessive amount of sulfur dioxide. Through the electrolysis test unit of the Karl Fischer moisture meter, the first moisture content x1 of the sample of the sulfide solid electrolyte to be tested is obtained.

[0008] Another sample of the sulfide solid electrolyte to be tested with a second mass is heated under the same conditions, and under the protection of a second carrier gas, the gas produced by heating is introduced into a second titration unit of the Karl Fischer moisture meter. The second titration unit is filled with a second electrolyte solution, and the second electrolyte solution contains the iodine salt, methanol, and an acid. Through the electrolysis test unit of the Karl Fischer moisture meter, the second moisture content x of the sample of the sulfide solid electrolyte to be tested is obtained. 2’ ;

[0009] The difference between the first mass and the second mass is within one-thousandth; the actual moisture content of the sample of the sulfide solid electrolyte with the first mass is the difference between x1 and x. 2’ of.

[0010] In an embodiment of the present invention, the organic base in the first electrolyte solution is pyridine or imidazole.

[0011] In an embodiment of the present invention, the organic base in the first electrolyte solution is imidazole.

[0012] In an embodiment of the present invention, the acid in the second electrolyte solution is formic acid, acetic acid, or hydrochloric acid.

[0013] In an embodiment of the present invention, the first carrier gas and the second carrier gas are the same inert gas.

[0014] In an embodiment of the present invention, the sample of the sulfide solid electrolyte to be tested is Li 10 GeP2S 12 test sample or Li6PS5Cl test sample.

[0015] In an embodiment of the present invention, the heating is achieved by a Kjeldahl furnace, and the heating temperature is 195 - 205 °C.

[0016] In an embodiment of the present invention, the heating time is more than 5 minutes.

[0017] In an embodiment of the present invention, the detection method is carried out in an environment with a water content ≤ 1 ppm and an oxygen content ≤ 1 ppm.

[0018] In an embodiment of the present invention, the detection method is carried out in a glove box.

[0019] Compared with the prior art, based on the reaction of hydrogen sulfide and sulfur dioxide to generate water and sulfur elemental precipitation, after reacting hydrogen sulfide completely with excessive sulfur dioxide, the total water content after the reaction is measured by the coulometric method; then, under acidic conditions, the H2S in the sulfide solid electrolyte sample to be measured that enters the titration cell electrolyte is oxidized by the I2 generated by electrolysis to produce S precipitation, and the Karl Fischer moisture meter is used to measure the second water content; finally, the difference between the total water content and the second water content is calculated to obtain the actual water content. The detection method proposed by the present invention is simple in operation and high in accuracy. Among them, converting hydrogen sulfide into water makes the detection safer, more environmentally friendly, and does not require introducing new substances, avoiding the risk of increasing other side reactions and the addition of reagent devices. Specific Embodiments

[0020] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0021] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, which is only a way of distinguishing objects with the same attributes when describing the embodiments of the present application.

[0022] The present invention provides a method for detecting the water content in a sulfide solid electrolyte, including the following steps:

[0023] Heat a sulfide solid electrolyte sample to be measured with a first mass under certain conditions, and under the protection of a first carrier gas, introduce the gas produced by heating into a first titration unit of a Karl Fischer moisture meter. The first titration unit is filled with a first electrolyte, and the first electrolyte contains an iodide salt, methanol, an organic base, and excessive sulfur dioxide; through the electrolysis test unit of the Karl Fischer moisture meter, the first water content x1 of the sulfide solid electrolyte sample to be measured is obtained;

[0024] Heat another sulfide solid electrolyte sample to be measured with a second mass under the same conditions, and under the protection of a second carrier gas, introduce the gas produced by heating into a second titration unit of the Karl Fischer moisture meter. The second titration unit is filled with a second electrolyte, and the second electrolyte contains the iodide salt, methanol, and an acid; through the electrolysis test unit of the Karl Fischer moisture meter, the second water content x of the sulfide solid electrolyte sample to be measured is obtained 2’ ;

[0025] The difference between the first mass and the second mass is within one-thousandth; the actual moisture content of the sulfide solid electrolyte test sample with the first mass is x1 and the difference between x 2’ and x.

[0026] Since the moisture content of the sulfide solid electrolyte is not measured in the existing technical solutions, the present invention provides a method for detecting the moisture content in the sulfide solid electrolyte with high accuracy, safety and no environmental pollution.

[0027] In an embodiment of the present invention, a sulfide solid electrolyte test sample with a first mass m1 is weighed, heated under certain conditions, and under the protection of a first carrier gas, the gas produced by heating is introduced into a first titration unit of a Karl Fischer moisture meter. The first titration unit is filled with a first electrolyte, and the first electrolyte contains an iodide salt, methanol, an organic base and an excessive amount of sulfur dioxide; through the electrolysis test unit of the Karl Fischer moisture meter, the first moisture content x1 of the sulfide solid electrolyte test sample is obtained.

[0028] That is, in an embodiment of the present invention, the total moisture content after the electrolysis reaction of the test sample is first measured by using a Karl Fischer moisture meter. The present invention has no special restrictions on the equipment model of the Karl Fischer moisture meter, which generally includes an electrolytic cell (equipped with an electrolytic electrode and a titration cell), a stirring device, an instrument input / output unit (such as an instrument keyboard, a display window), etc.

[0029] The Karl Fischer moisture meter usually selects a coulometric Karl Fischer moisture meter. The more commonly used brands and models are Mettler InMotion KF combined with C20S or C30S, and Metrohm 885 KF furnace combined with 831 or 917. The titration speed is the same as the conventional one, usually selected according to the type of the generating electrode, with a maximum of 2.24 mg H2O / min. The types of generating electrodes are divided into diaphragm electrodes and non-diaphragm electrodes, and both can be used in this experiment; the indicating electrode is a double Pt electrode (double platinum needle electrode). The required injection volume is such that the volume covers the bottom of the sample bottle and does not exceed 1 / 3 of the bottle, and the mass is usually 0.1 - 1 g.

[0030] Its working principle and the involved reaction formula are as follows:

[0031] 2H2S + SO2 → 3S↓ + 2H2O (1);

[0032] Based on the reaction of hydrogen sulfide and sulfur dioxide to generate water and sulfur elemental precipitation, in an embodiment of the present invention, the hydrogen sulfide is completely reacted with an excessive amount of sulfur dioxide, and then the total moisture content is measured by using the coulometric method.

[0033] The exemplary reaction formula is:

[0034] I2 + H2O + SO2 + 3C5H5N + CH3OH → 2C5H5N·HI + C5H5N·HSO4CH3 (2).

[0035] In the coulometric titration method, the required iodine is generated by the electrolytic reaction. During the electrolysis process, according to Faraday's law of electrolysis, the electrode reactions are as follows:

[0036] Anode: 2I - - 2e - → I2;

[0037] Cathode: I2 + 2e - → 2I - .

[0038] It can be seen from reaction (2) that 1 mol of iodine oxidizes 1 mol of sulfur dioxide and consumes 1 mol of water. By using the strict quantitative relationship between charge and iodine, the content of H2O can be measured and calculated. When a very small amount of free iodine appears, the voltage difference between the two ends of the double platinum needle indicating electrode will decrease sharply. In the embodiments of the present invention, this change is utilized to determine the titration end point.

[0039] Combined with the fact that 1 mol of hydrogen sulfide reacts with sulfur dioxide to produce 1 mol of water in reaction (1), the amount of iodine consumed in the whole process is equal to the total amount of water substance, and the total amount of water substance is the sum of the actual amount of water substance and the amount of hydrogen sulfide substance.

[0040] Faraday's law: W / M = Q / (Nf);

[0041] Wherein, W is the mass (g) of the substance undergoing a chemical reaction on the electrode, M is the molar mass (g / mol) of the reaction substance, Q is the electrolytic charge (C), f is the Faraday constant (96485 C / mol), and N is the number of electrons transferred in the electrode reaction stoichiometric equation.

[0042] According to Faraday's law, it can be obtained that:

[0043] x1·m1 / M1 = Q1 / (2 * 96485) (3);

[0044] x1 / M1 = x2 / M2 + x3 / M1 (4).

[0045] Wherein, x1 is the content (μg / g) of the total H2O of the substance undergoing a chemical reaction on the electrode, and is also the total water content measured by the Karl Fischer moisture meter; x2 is the content (μg / g) of H2S of the substance undergoing a chemical reaction on the electrode; x3 is the content (μg / g) of the actual H2O of the substance undergoing a chemical reaction on the electrode; M1 is the molar mass (g / mol) of H2O; M2 is the molar mass (g / mol) of H2S; Q1 is the electrolytic charge (C); m1 is the first mass (g) of the sample obtained during the test.

[0046] Moreover, in the embodiment of the present invention, the sulfide solid electrolyte sample to be tested with the second mass m2 is heated under the same conditions, and under the protection of the second carrier gas, the gas produced by heating is introduced into the second titration unit of the Karl Fischer moisture meter. The second titration unit is filled with a second electrolyte solution, and the second electrolyte solution contains the iodide salt, methanol and acid; through the electrolysis test unit of the Karl Fischer moisture meter, the second moisture content x of the sulfide solid electrolyte sample to be tested is obtained 2’ . That is, the embodiment of the present invention uses a Karl Fischer moisture meter to test the second water content; its working principle and the involved reaction formula are as follows:

[0047] I2+H2S→2HI+S↓ (5);

[0048] Under acidic conditions, the H2S entering the electrolyte solution of the titration cell is oxidized by the I2 generated by electrolysis, and S precipitation occurs. Utilizing the strict quantitative relationship between charge and iodine, the embodiment of the present invention can measure and calculate the content of H2S. When a very small amount of free iodine appears, the voltage difference across the Pt indicator electrode will drop sharply, and this change can be used to determine the titration endpoint

[0049] During the electrolysis process, the electrode reactions are as follows:

[0050] Anode: 2I - -2e - →I2;

[0051] Cathode: I2+2e - →2I - .

[0052] It can be seen from the above reactions that the amount of substance of iodine consumed in the whole process is equal to the amount of substance of hydrogen sulfide

[0053] According to Faraday's law, it can be obtained that:

[0054] x2·m2 / M2 = Q2 / (2*96485) (6);

[0055] However, what is actually displayed after the test in the Karl Fischer moisture meter is the second water content (x 2′ ), and the amount of electricity consumed at this time is unchanged, that is to say, Q2 / (2*96485) is unchanged, so x 2′ ·m2 / M1 = Q2 / (2*96485), that is:

[0056] x2 / M2 = x 2′ / M1 (7).

[0057] In the formula, x2 is the content of H2S (μg / g) that undergoes a chemical reaction on the electrode; x 2′is the second water content (μg / g) shown by the Karl Fischer moisture meter; M1 is the molar mass of H2O (g / mol); M2 is the molar mass of H2S (g / mol); Q2 is the electrolysis charge (C); m2 is the second mass (g) of the sample taken during the test.

[0058] Finally, the actual water content calculated in the embodiments of the present invention is obtained from Equations (4) and (7) as follows:

[0059] x3 = x1 - x 2′ (8);

[0060] In the formula, x1 is the content (μg / g) of the total H2O that undergoes a chemical reaction on the electrode, and is also the total moisture content obtained by testing with the Karl Fischer moisture meter; x 2′ is the second water content (μg / g) shown by the Karl Fischer moisture meter; x3 is the actual H2O content (μg / g) that undergoes a chemical reaction on the electrode.

[0061] Specifically, the steps of the detection method are as follows:

[0062] Weigh a sample of the first mass m1 and place it in a sample bottle; place the sample bottle with the sample on a Kjeldahl furnace, and set the heating temperature T and heating time t; introduce the first carrier gas, and pass the hydrogen sulfide gas and water vapor volatilized by heating in the sample bottle into the first titration cell containing the first electrolyte;

[0063] After waiting for the hydrogen sulfide reaction to complete, turn on the Karl Fischer moisture meter, input the sample mass m1, wait for the potential to reach the end point, and read the total moisture content x1 after the reaction on the instrument;

[0064] Take another clean sample bottle and a second titration cell; weigh a sample of the second mass m2 and place it in the sample bottle; place the sample bottle with the sample on a Kjeldahl furnace, and set the same heating temperature T and heating time t; introduce the second carrier gas, and pass the hydrogen sulfide gas and water vapor volatilized by heating in the sample bottle into the second titration cell containing the second electrolyte;

[0065] Turn on the Karl Fischer moisture tester, input the sample mass m2, wait for the potential to reach the end point, and read the moisture content x 2′ ; According to the difference between x1 and x 2′ , calculate the actual moisture content x3.

[0066] Among them, the first titration cell is filled with a first electrolyte solution, which contains an iodine salt, excessive sulfur dioxide, methanol (CH3OH), and an organic base; the iodine salt serves as a source for electrolytic generation of I2, and the organic base is preferably pyridine or imidazole. Considering the odor toxicity and pollution of pyridine, imidazole is further preferred. Specifically, the first electrolyte solution generally adopts a molar ratio of iodine: sulfur dioxide: imidazole: methanol = 1:3:10:50, and a small amount of organic base is added to adjust the pH to 8-9.

[0067] The second titration cell is filled with a second electrolyte solution, which contains an iodine salt, methanol, and an acid. The iodine salt serves as a source for electrolytic generation of I2, which is the same as the iodine salt in the first electrolyte solution; the acid is an acid that does not produce side reactions, such as formic acid, acetic acid, hydrochloric acid, etc., which can provide an acidic condition, etc. Taking hydrochloric acid as an example, the second electrolyte solution adopts a molar ratio of iodine: methanol: acid = 10:500:1.

[0068] The sulfide solid electrolyte sample to be measured is Li 10 GeP2S 12 a sample to be measured or a Li6PS5Cl sample to be measured; the masses of the samples to be measured weighed twice in the embodiments of the present invention are as close as possible, and the difference between the first mass and the second mass is within one-thousandth.

[0069] Moreover, the temperatures of the two heatings are the same, preferably 195-205 °C. The first carrier gas and the second carrier gas are preferably the same, and can be inert gases such as nitrogen, argon, and helium. The optional range of the flow rate of the carrier gas is 10-150 ml / min, and the flow rate of the carrier gas is preferably fixedly selected as 50 ml / min.

[0070] In addition, the drift value of the Karl Fischer moisture meter < 10 μg / min. The "drift value" is the moisture calculated from the electrical signal output by the indicating electrode within a certain period of time during the operation of the device, with the unit of μg / min. Here, it reflects the moisture introduced from the electrolyte solution itself or the working environment by the titration unit when no sample is added, and is subtracted as the environmental blank during calculation; generally, the lower the drift value, the less the test is affected by the environment and reagents, and the more stable the test is.

[0071] Regarding the sample injection volume, it is required that the volume covers the bottom of the sample bottle and does not exceed 1 / 3 of the bottle, and the mass is usually 0.1-1 g. When in use, the state of the electrolyte solution: it is used in a liquid state at room temperature of 25 (±5) °C, and cannot be heated or frozen, and the drift value is less than 10 μg / min.

[0072] After the hydrogen sulfide in the embodiment of the present invention is completely reacted with excessive sulfur dioxide, the total moisture content after the reaction is measured by the coulometric method; then, under acidic conditions, the H2S in the sulfide solid electrolyte sample to be measured entering the titration cell electrolyte is oxidized by the I2 generated by electrolysis to produce S precipitation, and the Karl Fischer moisture meter is used to measure the second moisture content; finally, the difference between the total moisture content and the second moisture content is calculated to obtain the actual moisture content. The detection method proposed by the present invention is simple to operate, has high accuracy, is safer to detect, and is more environmentally friendly.

[0073] To better understand the technical content of this application, specific embodiments are provided below to further illustrate this application. In this experiment, a glove box is used, which is a Vigor double-sided multi-station glove box. Any equipment that can achieve an oxygen-free and water-free environment with a water content ≤ 1 ppm and an oxygen content ≤ 1 ppm and can perform experimental operations can be used.

[0074] Examples 1-4

[0075] All the following steps are carried out in the glove box (with a water content ≤ 1 ppm and an oxygen content ≤ 1 ppm).

[0076] 1. Weigh a certain mass of the powder to be measured m1 and place it in sample bottle 1.

[0077] 2. Tighten the cap of sample bottle 1 and place it on the Kjeldahl furnace.

[0078] 3. Turn on the Kjeldahl furnace and set the heating temperature T and heating time t.

[0079] 4. The gas generated after heating enters titration cell 1 (containing the first electrolyte) along with the argon gas connected to the Kjeldahl furnace and reacts.

[0080] 5. After reacting for 5 minutes, turn on the Karl Fischer moisture meter, input the sample mass m1, set the drift value < 10 μg / min, and the stirring speed is 5-6, and start the test.

[0081] 6. After reaching the end point, record the total moisture content x1.

[0082] 7. Take another clean sample bottle 2 and titration cell 2.

[0083] 8. Weigh a certain mass of the powder to be measured m2 and place it in sample bottle 2.

[0084] 9. Tighten the cap of sample bottle 2 and place it on the Kjeldahl furnace.

[0085] 10. Turn on the Kjeldahl furnace and set the heating temperature T and heating time t.

[0086] 11. The gas generated after heating enters titration cell 2 (containing the second electrolyte) along with the argon gas connected to the Kjeldahl furnace and reacts.

[0087] 12. Turn on the Karl Fischer moisture meter, input the sample mass m2, set the drift value < 10 μg / min, and the stirring speed to 5 - 6, then start the test; the stirring here serves to disperse the iodine generated near the generator electrode into the reagent, without precise requirements.

[0088] 13. After reaching the end point, record the second moisture content x displayed on the instrument. 2′ ;

[0089] 14. Calculate the actual moisture content: x3 = x1 - x 2′ .

[0090] The samples to be tested in Examples 1 - 4 are LGPS, LGPS, LPSC, and LPSC in sequence.

[0091] The test results are as follows; it can be seen from the results of the examples that the moisture content in LGPS and LPSC powders is relatively stable.

[0092] Table 1 Detection results of the examples of the present invention

[0093]

[0094] In the above examples, the first electrolyte uses the commonly available electrolyte of the Saifuri brand on the market, and imidazole is added to adjust the pH to 8 - 9 on this basis. The second electrolyte is prepared with anhydrous reagents, and the molar ratio is iodine: methanol: formic acid = 10:500:1.

[0095] Comparative Example

[0096] All the following steps are carried out in a glove box (water content ≤ 1 ppm, oxygen content ≤ 1 ppm).

[0097] 1. Weigh a certain mass of the powder to be tested m and place it in a sample bottle.

[0098] 2. Tighten the sample bottle cap and place it on the Kjeldahl furnace.

[0099] 3. Turn on the Kjeldahl furnace and set the heating temperature T and heating time t.

[0100] 4. The gas generated after heating enters the titration cell along with the argon gas connected to the Kjeldahl furnace and reacts.

[0101] 5. Turn on the Karl Fischer moisture analyzer, input the sample mass m, set the offset value < 10, and the stirring speed to 5 - 6, then start the test.

[0102] 6. After reaching the end point, record the moisture content displayed on the instrument.

[0103] The test results are as follows:

[0104] Table 2 Detection Results of Comparative Examples of the Present Invention

[0105] Sample composition Mass / g Heating temperature T / ℃ Heating time t / min Moisture content / ppm LGPS 0.2011 200 5 606.5 LGPS 0.2013 200 5 321.2 LPSC 0.2008 200 5 203.2 LPSC 0.2005 200 5 306.4

[0106] It can be seen from the results of the comparative examples that the moisture content values in the LGPS and LPSC powders are unstable. The side reactions of hydrogen sulfide with iodine and with sulfur dioxide were not excluded in the comparative examples, and the occurrence order, reaction mechanism and degree of the side reactions were uncontrollable in the conventional methods. Compared with the results of the examples, the moisture content measured in the comparative examples was significantly larger and the test results were unstable. Due to the presence of hydrogen sulfide in the LGPS and LPSC powders, side reactions occurred with the components in the electrolyte to release moisture or consume iodine, resulting in incorrect results.

[0107] As can be seen from the above examples, the detection method proposed by the present invention is simple to operate and has high accuracy. Among them, converting hydrogen sulfide into water makes the detection safer, more environmentally friendly, and does not require the introduction of new substances, avoiding the risk of increasing other side reactions and the increase of reagent devices.

[0108] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting the water content in a sulfide solid electrolyte, characterized in that, The method includes the following steps: Heat a sample of the sulfide solid electrolyte to be measured with a first quality under certain conditions, and under the protection of a first carrier gas, introduce the gas produced by heating into a first titration unit of a Karl Fischer moisture meter. The first titration unit is filled with a first electrolyte, and the first electrolyte contains an iodide salt, methanol, an organic base, and an excessive amount of sulfur dioxide; obtain a first moisture content x1 of the sulfide solid electrolyte sample to be measured through the electrolysis test unit of the Karl Fischer moisture meter; Separately, the sample of the sulfide solid electrolyte to be tested with the second quality is heated under the same conditions, and under the protection of a second carrier gas, the gas produced by heating is introduced into a second titration unit of a Karl Fischer moisture meter. The second titration unit is filled with a second electrolyte solution, and the second electrolyte solution contains the iodine salt, methanol, and an acid; through the electrolysis test unit of the Karl Fischer moisture meter, the second moisture content x of the sample of the sulfide solid electrolyte to be tested is obtained 2’ ; The difference between the first mass and the second mass is within one-thousandth; the actual moisture content of the sulfide solid electrolyte test sample with the first mass is the difference between x1 and x 2’ of.

2. The detection method according to claim 1, characterized in that, The organic base in the first electrolyte is pyridine or imidazole.

3. The detection method according to claim 2, characterized in that, The organic base in the first electrolyte is imidazole.

4. The detection method according to claim 1, characterized in that, The acid in the second electrolyte is formic acid, acetic acid, or hydrochloric acid.

5. The detection method according to claim 1, characterized in that, The first carrier gas and the second carrier gas are the same inert gas.

6. The detection method according to any one of claims 1-5, characterized in that, The sulfide solid electrolyte sample to be measured is Li 10 GeP2S 12 sample to be measured or Li6PS5Cl sample to be measured.

7. The detection method according to claim 6, characterized in that, The heating is achieved by a Kjeldahl furnace, and the heating temperature is 195 - 205 °C.

8. The detection method according to claim 7, wherein The heating time is more than 5 minutes.

9. The detection method according to any one of claims 1-5, characterized in that The detection method is carried out in an environment with a water content ≤ 1 ppm and an oxygen content ≤ 1 ppm.

10. The detection method according to claim 9, characterized in that, The detection method is carried out in a glove box.

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