Method and device for detecting silicon content in silicon-based electrode material

Abstract

This application relates to a method and apparatus for detecting the silicon content in silicon-based electrode materials. The method for detecting the silicon content in silicon-based electrode materials includes the following steps: mixing the silicon-based electrode material to be tested with an alkaline solution, and performing a first reaction to obtain a first slurry; performing a first solid-liquid separation treatment on the first slurry to obtain a first solid material and a first filtrate; mixing the first solid material with an aqua regia solution, and performing a second reaction to obtain a second slurry; performing a second solid-liquid separation treatment on the second slurry to obtain a second solid material and a second filtrate; detecting the silicon content in the first filtrate and the second filtrate respectively, and calculating the silicon content in the silicon-based electrode material based on the silicon content in the first filtrate and the second filtrate. The method for detecting the silicon content in silicon-based electrode materials of this application has simple operating steps and can also achieve a good extraction effect on silicon in silicon-based electrode materials, thereby improving the accuracy of silicon content detection in silicon-based electrode materials.

Description

Technical Field

[0001] This application relates to the field of chemical analysis technology, and in particular to a method and apparatus for detecting the silicon content in silicon-based electrode materials. Background Technology

[0002] Silicon-based electrode materials possess high theoretical specific capacity and have broad application prospects in fields such as lithium-ion batteries. The silicon content in silicon-based electrode materials has a significant impact on the performance and stability of the battery.

[0003] Traditional methods for detecting silicon content in silicon-based electrode materials often fail to simultaneously achieve both good silicon extraction efficiency and simple operating procedures. Summary of the Invention

[0004] Therefore, it is necessary to provide a method and apparatus for detecting the silicon content in silicon-based electrode materials. The method for detecting the silicon content in silicon-based electrode materials of this application has simple operating steps and also has a good extraction effect on silicon in silicon-based electrode materials, thereby improving the accuracy of silicon content detection in silicon-based electrode materials.

[0005] In a first aspect, this application provides a method for detecting the silicon content in a silicon-based electrode material, comprising the following steps:

[0006] The silicon-based electrode material to be tested is mixed with an alkaline solution, and after a first reaction, a first slurry is obtained.

[0007] The first slurry is subjected to a first solid-liquid separation process to obtain a first solid material and a first filtrate.

[0008] The first solid material is mixed with aqua regia solution, and then subjected to a second reaction to obtain a second slurry;

[0009] The second slurry is subjected to a second solid-liquid separation process to obtain a second solid material and a second filtrate;

[0010] The silicon content in the first filtrate and the second filtrate were detected respectively, and the silicon content in the silicon-based electrode material was calculated based on the silicon content in the first filtrate and the silicon content in the second filtrate.

[0011] In some embodiments, the solute in the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide.

[0012] In some embodiments, the mass concentration of the solute in the alkaline solution is 5% to 20%.

[0013] In some embodiments, the mass ratio of the silicon-based electrode material to be tested to the solute in the alkaline solution is 1:(8~12).

[0014] In some embodiments, the temperature of the first reaction is 115°C to 125°C.

[0015] In some embodiments, the first reaction time is 160 min to 200 min.

[0016] In some embodiments, the volume ratio of aqua regia to deionized water in the aqua regia solution is (3~7):5.

[0017] In some embodiments, the mass ratio of the silicon-based electrode material to be tested to the volume ratio of the aqua regia solution is 1g:8mL to 1g:12mL.

[0018] In some embodiments, the temperature of the second reaction is 115°C to 125°C.

[0019] In some embodiments, the second reaction takes 25 to 35 minutes.

[0020] In some embodiments, after the first slurry undergoes a first solid-liquid separation process to obtain a first solid material and a first filtrate, the following steps are further included:

[0021] The first solid material is washed with deionized water to obtain a first cleaning solution, and the first cleaning solution is mixed with the first filtrate.

[0022] In some embodiments, after the second slurry undergoes a second solid-liquid separation process to obtain a second solid material and a second filtrate, the following steps are further included:

[0023] The second solid material is washed with deionized water to obtain a second cleaning solution, and the second cleaning solution is mixed with the second filtrate.

[0024] In some embodiments, detecting the silicon content in the first filtrate and the second filtrate respectively includes the following steps:

[0025] The silicon concentration in the first filtrate and the second filtrate was detected by inductively coupled plasma mass spectrometry.

[0026] In some embodiments, detecting the silicon concentration in the first filtrate and the second filtrate using inductively coupled plasma mass spectrometry includes the following steps:

[0027] Prepare silicon standard solutions of different concentrations;

[0028] The silicon concentration in each silicon standard solution was measured by inductively coupled plasma mass spectrometry, and the response value-concentration curve was obtained.

[0029] The first filtrate and the second filtrate were tested by inductively coupled plasma mass spectrometry to obtain the first response value of the first filtrate and the second response value of the second filtrate.

[0030] The silicon concentration in the first filtrate and the second filtrate is obtained by comparing the first response value, the second response value, and the response value-concentration curve.

[0031] In some embodiments, the silicon-based electrode material includes at least one of lithium orthosilicate and its composite materials.

[0032] Secondly, this application provides a device for detecting the silicon content in a silicon-based electrode material, comprising: a first reaction device, a first solid-liquid separation device, a second reaction device, a second solid-liquid separation device, and a detection device; wherein,

[0033] The first reaction device is used to mix the silicon-based electrode material to be tested with an alkaline solution, and after a first reaction, obtain a first slurry;

[0034] The first solid-liquid separation device is used to perform a first solid-liquid separation process on the first slurry to obtain a first solid material and a first filtrate;

[0035] The second reaction apparatus is used to mix the first solid material and the aqua regia solution, and through a second reaction, obtain a second slurry;

[0036] The second solid-liquid separation device is used to perform a second solid-liquid separation process on the second slurry to obtain a second solid material and a second filtrate;

[0037] The detection device is used to detect the silicon content in the first filtrate and the second filtrate respectively, and to calculate the silicon content in the silicon-based electrode material based on the silicon content in the first filtrate and the silicon content in the second filtrate.

[0038] In the aforementioned method for detecting silicon content in silicon-based electrode materials, a first reaction is carried out between an alkaline solution and the silicon-based electrode material to be tested, yielding a first filtrate, i.e., an alkaline silicon-dissolving solution. Then, a second reaction is carried out between an aqua regia solution and the first solid material after the first reaction, yielding a second filtrate, i.e., an acid-dissolving silicon-dissolving solution. This method achieves a high extraction rate of silicon from silicon-based electrode materials. The silicon content in the first and second filtrates is then detected separately, and the silicon content in the silicon-based electrode material can be calculated from the silicon content in the first and second filtrates. The method for detecting silicon content in silicon-based electrode materials of this application has simple operating steps and also provides good extraction of silicon from silicon-based electrode materials, thereby improving the accuracy of silicon content detection in silicon-based electrode materials. Detailed Implementation

[0039] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0042] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0043] One embodiment of this application provides a method for detecting the silicon content in a silicon-based electrode material, comprising the following steps:

[0044] The silicon-based electrode material to be tested is mixed with an alkaline solution, and after a first reaction, a first slurry is obtained.

[0045] The first slurry is subjected to a first solid-liquid separation process to obtain a first solid material and a first filtrate.

[0046] The first solid material is mixed with aqua regia solution, and then subjected to a second reaction to obtain a second slurry;

[0047] The second slurry is subjected to a second solid-liquid separation process to obtain a second solid material and a second filtrate.

[0048] The silicon content in the first filtrate and the second filtrate were measured respectively, and the silicon content in the silicon-based electrode material was calculated based on the silicon content in the first filtrate and the silicon content in the second filtrate.

[0049] In the aforementioned method for detecting silicon content in silicon-based electrode materials, a first reaction is carried out between an alkaline solution and the silicon-based electrode material to be tested, yielding a first filtrate, i.e., an alkaline silicon-dissolving solution. Then, a second reaction is carried out between an aqua regia solution and the first solid material after the first reaction, yielding a second filtrate, i.e., an acid-dissolving silicon-dissolving solution. This method achieves a high extraction rate of silicon from silicon-based electrode materials. The silicon content in the first and second filtrates is then detected, and the silicon content in the silicon-based electrode material can be calculated from the silicon content in the first and second filtrates. It is understood that the silicon content detection method in silicon-based electrode materials of this application achieves a high extraction rate of silicon, therefore the silicon content in the silicon-based electrode material can be directly calculated by summing the silicon content in the first and second filtrates. The silicon content detection method in silicon-based electrode materials of this application has simple operating steps and also achieves good extraction effect on silicon in silicon-based electrode materials, thus improving the accuracy of silicon content detection.

[0050] Furthermore, the method for detecting silicon content in silicon-based electrode materials of this application has the following advantages:

[0051] 1. The chemical reagents and steps for sample pretreatment are simplified. The pretreatment reagents required in this application are few and relatively conventional, consisting only of alkaline solution and aqua regia solution. Compared with existing sample treatment methods, there is no need to use chemical reagents such as ammonium nitrate, potassium pyrosulfate, hydrofluoric acid, and lithium borate, and there is no need for complex pretreatment steps such as high-temperature melting, thermal swelling and transfer, high-temperature volatilization of hydrofluoric acid, and repeated drying to constant weight, which reduces testing time costs and improves work efficiency.

[0052] 2. Reduced equipment costs for pretreatment and testing. The pretreatment equipment in this application only requires ordinary electric hot plates, without the need for high-temperature furnaces and platinum crucibles; the testing equipment only requires ICP-OES and conventional liquid standards, without the need to purchase specific solid standards and XRF equipment, resulting in low operating costs for the ICP-OES equipment.

[0053] 3. High accuracy and stability of test data. The detection method of this application is applicable to lithium silicate composite materials with different concentrations of metal doping for batteries, with a wide range of applications, high accuracy of test data, and good test repeatability.

[0054] In some embodiments, the mass concentration of the solute in the alkaline solution is 5% to 20%.

[0055] Within the range of solute mass concentration in the aforementioned alkaline solution, it is convenient to achieve a better extraction effect of silicon in silicon-based electrode materials. Optionally, the mass concentration of the solute in the alkaline solution is 5%, 8%, 10%, 12%, 15%, 18%, or 20%, or the mass concentration of the solute in the alkaline solution can be within the range of any two of the above concentrations.

[0056] In some embodiments, the mass ratio of the silicon-based electrode material to be tested to the solute in the alkaline solution is 1:(8~12).

[0057] Within the range of the mass ratio of the silicon-based electrode material to be tested and the solute in the alkaline solution, it is convenient to achieve a better extraction effect of silicon in the silicon-based electrode material. Optionally, the mass ratio of the silicon-based electrode material to be tested and the solute in the alkaline solution is 1:8, 1:8.5, 1:9, 1:9.5, 1:10, 1:10.5, 1:11, 1:11.5 or 1:12, or the mass ratio of the silicon-based electrode material to be tested and the solute in the alkaline solution can also be within the range between any two of the above mass ratios.

[0058] In some of these embodiments, the temperature of the first reaction is 115°C to 125°C.

[0059] Within the temperature range of the first reaction described above, it is convenient to achieve a better extraction effect of silicon from silicon-based electrode materials. Optionally, the temperature of the first reaction is 115℃, 116℃, 117℃, 118℃, 119℃, 120℃, 121℃, 122℃, 123℃, 124℃, or 125℃, or the temperature of the first reaction can be within the range of any two of the above temperatures.

[0060] In some implementations, the first reaction time is 160 min to 200 min.

[0061] Within the time range of the first reaction described above, it is convenient to achieve a better extraction effect of silicon in silicon-based electrode materials. Optionally, the time of the first reaction is 160 min, 165 min, 170 min, 175 min, 180 min, 185 min, 190 min, 195 min or 200 min, or the time of the first reaction can also be within the range of any two of the above times.

[0062] In some embodiments, the volume ratio of aqua regia to deionized water in the aqua regia solution is (3~7):5.

[0063] It is understood that an aqua regia solution refers to a mixture of aqua regia and deionized water. Aqua regia is a mixture of concentrated hydrochloric acid and concentrated nitric acid in a volume ratio of 3:1. Optionally, the volume ratio of aqua regia to deionized water in the aqua regia solution can be 3:5, 4:5, 5:5, 6:5, or 7:5, or the volume ratio of aqua regia to deionized water in the aqua regia solution can also be within any two of the above volume ratios.

[0064] In some embodiments, the mass ratio of the silicon-based electrode material to be tested to the volume ratio of the aqua regia solution is 1 g: 8 mL to 1 g: 12 mL.

[0065] Within the range of the mass-to-volume ratio of the silicon-based electrode material to be tested to the aqua regia solution, it is convenient to achieve a better extraction effect of silicon in the silicon-based electrode material. Optionally, the mass-to-volume ratio of the silicon-based electrode material to be tested to the aqua regia solution is 1g:8mL, 1g:9mL, 1g:10mL, 1g:11mL, or 1g:12mL, or the mass-to-volume ratio of the silicon-based electrode material to be tested to the aqua regia solution can also be within the range of any two of the above ratios.

[0066] In some embodiments, the temperature of the second reaction is 115°C to 125°C.

[0067] Within the temperature range of the second reaction described above, it is convenient to achieve a better extraction effect of silicon from silicon-based electrode materials. Optionally, the temperature of the second reaction is 115℃, 116℃, 117℃, 118℃, 119℃, 120℃, 121℃, 122℃, 123℃, 124℃, or 125℃, or the temperature of the second reaction can be within any two of the above-mentioned temperatures.

[0068] In some implementations, the second reaction takes 25 to 35 minutes.

[0069] Within the time range of the second reaction described above, it is convenient to achieve a better extraction effect of silicon from silicon-based electrode materials. Optionally, the time of the second reaction is 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min, 34 min, or 35 min, or the time of the second reaction can also be within any two of the above time ranges.

[0070] In some embodiments, after the first slurry undergoes a first solid-liquid separation process to obtain a first solid material and a first filtrate, the following steps are further included:

[0071] The first solid material is washed with deionized water to obtain a first cleaning solution, which is then mixed with the first filtrate.

[0072] In some embodiments, after the second slurry undergoes a second solid-liquid separation process to obtain a second solid material and a second filtrate, the following steps are further included:

[0073] The second solid material is washed with deionized water to obtain a second cleaning solution, and the second cleaning solution and the second filtrate are mixed.

[0074] In some embodiments, detecting the silicon content in the first filtrate and the second filtrate respectively includes the following steps:

[0075] The silicon concentration in the first and second filtrates was detected by inductively coupled plasma mass spectrometry.

[0076] It is understandable that the silicon concentration in the first and second filtrates can be detected by inductively coupled plasma atomic emission spectrometry (ICP-OES) using inductively coupled plasma mass spectrometry.

[0077] In some embodiments, detecting the silicon concentration in the first filtrate and the second filtrate using inductively coupled plasma mass spectrometry includes the following steps:

[0078] Prepare silicon standard solutions of different concentrations;

[0079] The silicon concentration in each silicon standard solution was measured by inductively coupled plasma mass spectrometry, and the response value-concentration curve was obtained.

[0080] The first filtrate and the second filtrate were tested by inductively coupled plasma mass spectrometry to obtain the first response value of the first filtrate and the second response value of the second filtrate.

[0081] The silicon concentration in the first filtrate and the second filtrate was obtained by comparing the first response value, the second response value, and the response value-concentration curve.

[0082] In some embodiments, the silicon-based electrode material includes at least one of silicates and their composites.

[0083] In some embodiments, the silicon-based electrode material includes at least one of lithium orthosilicate and its composite materials.

[0084] Another embodiment of this application provides a device for detecting the silicon content in a silicon-based electrode material, comprising: a first reaction device, a first solid-liquid separation device, a second reaction device, a second solid-liquid separation device, and a detection device. The first reaction device is used to mix the silicon-based electrode material to be tested with an alkaline solution, and after a first reaction, obtain a first slurry. The first solid-liquid separation device is used to perform a first solid-liquid separation treatment on the first slurry to obtain a first solid material and a first filtrate. The second reaction device is used to mix the first solid material with an aqua regia solution, and after a second reaction, obtain a second slurry. The second solid-liquid separation device is used to perform a second solid-liquid separation treatment on the second slurry to obtain a second solid material and a second filtrate. The detection device is used to detect the silicon content in the first filtrate and the second filtrate respectively, and calculate the silicon content in the silicon-based electrode material based on the silicon content in the first filtrate and the silicon content in the second filtrate.

[0085] Example 1

[0086] Methods for detecting silicon content in silicon-based electrode materials:

[0087] Weigh 0.1 g of lithium orthosilicate composite material, wet with a small amount of deionized water, add 10 mL of 10% NaOH solution, shake well, and heat on a 120℃ hot plate for 180 min. After cooling, filter and wash the filter residue three times with deionized water. Collect the filtrate and dilute to a 100 mL polyethylene volumetric flask to obtain an alkali-soluble silica solution. Transfer the filter residue along with the filter paper to a polytetrafluoroethylene beaker, add deionized water to cover the filter paper, add 2 mL of aqua regia solution (1:1 volume ratio of aqua regia and deionized water), heat on a 120℃ hot plate for 30 min, remove and cool, and dilute to a 100 mL glass volumetric flask to obtain an acid-soluble silica solution.

[0088] The concentration of silicon in the alkaline-soluble silicon solution and acid-soluble silicon solution to be tested was detected by inductively coupled plasma optical emission spectrometry (ICP-OES). The specific detection method is as follows: (1) Preparation of standard solution: 1000 ppm silicon standard solution (China Nonferrous Metals Research Institute) was provided. 5 mL of standard solution was taken and diluted to 50 mL to obtain a 100 ppm standard stock solution. The stock solution was diluted stepwise with 0.1% sodium carbonate solution to obtain silicon standard solutions of 0.5 ppm, 1 ppm, 2 ppm, 5 ppm, 10 ppm and 20 ppm. (2) Equipment parameter setting: Equipment model: ICAP 7000, power: 1150W, nebulizer flow rate: 0.5 L / min, auxiliary gas flow rate: 0.5 L / min, delay time: 40 s, and the wavelength of 251.611 nm was selected as the analysis wavelength. (3) The silicon standard solution concentration was tested to obtain the response value-concentration curve. Based on the response-concentration curve, the concentrations of silicon in the alkali-soluble silicon solution and the acid-soluble silicon solution are obtained respectively. The silicon content in the lithium orthosilicate composite material can be obtained by adding the two silicon contents together.

[0089] Comparative Example 1

[0090] Currently, the determination of the main components and doped metal content of lithium orthosilicate composite materials for electrodes mainly refers to GB / T14506.3-2010 Chemical Analysis Methods for Silicate Rocks.

[0091] Methods for detecting silicon content in silicon-based electrode materials:

[0092] Weigh 1g of lithium orthosilicate composite material and place it in a platinum crucible pre-filled with 6g of anhydrous sodium carbonate powder. Stir well, then cover with 1g of anhydrous sodium carbonate, cover with a platinum crucible lid, and place in a high-temperature furnace. Melt at 1000℃ for 40 minutes, then cool and remove. Place the cooled platinum crucible in a 250ml beaker and slowly add 50mL of dilute hydrochloric acid (1:1 volume ratio). After the vigorous reaction stops, heat to remove the melt, wash out the crucible, and place the beaker in a boiling water bath. Evaporate to about 10mL, remove, add 20ml of hydrochloric acid, place the beaker in a 70℃ water bath, add 10ml of animal gel, stir well, and after 10 minutes, add water to 40ml. Stir to dissolve the salts, filter, and wash the filter residue until no chloride ions are present. Place the filter paper and filter residue in the platinum crucible, ashing at low temperature, and then ignite in a 1000℃ high-temperature furnace for 1 hour. Weigh, and repeat ignition for 30 minutes until constant weight is achieved. Add 3 drops of water along the crucible wall to moisten the precipitate, add 10 ml of sulfuric acid and 5 ml of hydrofluoric acid, heat until white smoke stops, place the crucible in a 1000℃ high-temperature furnace and ignite for 30 minutes, cool and weigh, then ignite again for 30 minutes until constant weight, the difference between the two weights is the silica content in the precipitate. The residue in the crucible was melted in a 700℃ high-temperature furnace with 1g of potassium pyrosulfate for 5min. A small amount of deionized water was added to cover the residue, and then 5 drops of hydrochloric acid were added. The mixture was heated to dissolve and filtered. The filtrate was added to the filtrate obtained from the first filtration and the volume was adjusted to 250ml. 10ml of the filtrate was placed in a 50ml polytetrafluoroethylene beaker, and 10ml of sodium hydroxide solution (concentration 100g / L) was added. The mixture was heated to boiling for 10min. After cooling, 1 drop of phenolphthalein indicator was added and neutralized with hydrochloric acid until the red color faded and an excess of 6ml was added. The volume was adjusted to 100ml. The solution was transferred to an Erlenmeyer flask, and 10mL of ethanol and 5mL of ammonium molybdate solution were added. After standing for 20min, 10mL of dilute sulfuric acid was added, and the mixture was shaken for 5min. Then, 5mL of ascorbic acid was added. After standing for 1h, the absorbance was measured at a wavelength of 660nm on a spectrophotometer and compared with a standard concentration of silica solution to calculate the silica content in the filtrate. The sum of the silica content in the filter residue and the filtrate is the total silica content in the sample, which can be converted to obtain the total silicon content.

[0093] Comparative Example 2

[0094] The sample was extracted and tested in accordance with the national standard GB / T 14506.31-2019 Chemical Analysis Methods for Silicate Rocks - Lithium Metaborate Fusion-Inductively Coupled Plasma Atomic Emission Spectrometry.

[0095] Methods for detecting silicon content in silicon-based electrode materials:

[0096] Weigh 0.1g of lithium orthosilicate composite material and place it in a graphite crucible containing 0.4g of anhydrous lithium metaborate. Stir well, cover and place in a high-temperature furnace at 1000℃ for 15min. After cooling, place the graphite crucible in a beaker containing 30mL of aqua regia with a volume ratio of 1:1. Place the beaker in an ultrasonic cleaner and add deionized water to the beaker to cover the graphite crucible. Dissolve the molten salt by ultrasonic vibration for 15min. Wash out the graphite crucible and dilute the solution in the beaker to 50mL. This is the sample solution to be tested. The concentration of silicon in the solution to be tested is detected by inductively coupled plasma optical emission spectrometry (ICP-OES). The specific detection method is as follows: (1) Preparation of standard solution: Provide 1000ppm silicon standard solution (China Nonferrous Metals Research Institute). Take 5mL of standard solution and dilute to 50mL to obtain a 100ppm standard stock solution. The stock solution was gradually diluted with 0.1% sodium carbonate solution to obtain silicon standard solutions of 0.5 ppm, 1 ppm, 2 ppm, 5 ppm, 10 ppm and 20 ppm. (2) Equipment parameter settings: Equipment model: ICAP 7000, power: 1150W, atomizer flow rate: 0.5L / min, auxiliary gas flow rate: 0.5L / min, delay time: 40s, and the wavelength of 251.611nm was selected as the analysis wavelength. (3) The silicon concentration of each silicon standard solution was tested to obtain the response value-concentration curve. Based on the response value-concentration curve, the silicon concentration in the alkaline silicon solution and the acid-soluble silicon solution was obtained respectively. The silicon content in the lithium orthosilicate composite material was obtained by adding the two silicon contents.

[0097] Test Example 1

[0098] Five different samples were tested using the silicon content detection method for silicon-based electrode materials in Example 1, and sample 1# was tested using the silicon content detection methods for silicon-based electrode materials in Comparative Examples 1 and 2. The test results are shown in the table below:

[0099]

[0100] Test data show that the silicon content obtained by the extraction methods in Example 1 and Comparative Example 1 is not significantly different. However, the silicon content obtained by the silicon-based electrode material detection method in Comparative Example 2 is significantly lower than that in Example 1 and Comparative Example 1, indicating that the silicon content detection method in the silicon-based electrode material in Comparative Example 2 is not effective for silicon extraction.

[0101] Test Example 2

[0102] The silicon extraction rate of the five samples in Test Example 1 was determined.

[0103] Weigh 0.1 g of lithium orthosilicate composite material sample into a polytetrafluoroethylene (PTFE) beaker. Weigh 0.02 g of high-purity silicon powder (99.99%) and add it to the PTFE beaker containing the sample. Wet the beaker with a small amount of deionized water, add 20 mL of 10% NaOH solution, shake well, and heat on a 120°C hot plate for 180 min. After cooling, filter the solution and wash the filter residue three times with deionized water. Collect the filtrate and dilute it to a 100 mL polyethylene volumetric flask to obtain an alkali-soluble silicon solution. Transfer the filter residue along with the filter paper to a PTFE beaker, add deionized water to cover the filter paper, add 4 mL of aqua regia (1:1 volume ratio), and heat on a 120°C hot plate for 30 min. After cooling, dilute it to a 100 mL glass volumetric flask to obtain an acid-soluble silicon solution. The silicon concentration in the alkali-soluble and acid-soluble silicon solutions was detected using inductively coupled plasma optical emission spectrometry (ICP-OES). Based on the response-concentration curves, the silicon concentration in each solution was obtained. The silicon content in the lithium orthosilicate composite material was then calculated by summing the two concentrations. Specific data are as follows:

[0104]

[0105] By directly adding high-purity silicon powder to the sample, the extraction rate of silicon in the silicon-based electrode material of this application can be tested using the method for detecting silicon content in the silicon-based electrode material. As shown in the table above, the silicon content detection method of this application achieves an extraction rate of over 99% for silicon in different silicon-based electrode materials. This indicates that the silicon content detection method of this application has a good extraction effect on silicon in silicon-based electrode materials. Compared with the silicon content detection method in Comparative Example 1, the silicon extraction rate in Example 1 is comparable, but the operation steps are simplified.

[0106] Test Example 3

[0107] Sample 1# was repeatedly tested using the silicon content detection method for silicon-based electrode materials described in Example 1. The test results are shown in the table below:

[0108]

[0109] It can be seen that when the silicon content detection method of the silicon-based electrode material of this application is used to detect the same sample multiple times, the relative standard deviation is less than 1%, indicating that the test results of the silicon content detection method of the silicon-based electrode material of this application have high repeatability and small error.

[0110] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for detecting the silicon content in a silicon-based electrode material, characterized in that, Includes the following steps: The silicon-based electrode material to be tested is mixed with an alkaline solution and subjected to a first reaction to obtain a first slurry. The silicon-based electrode material includes at least one of silicates and their composite materials. The first slurry is subjected to a first solid-liquid separation process to obtain a first solid material and a first filtrate. The first solid material is mixed with aqua regia solution, and then subjected to a second reaction to obtain a second slurry; The second slurry is subjected to a second solid-liquid separation process to obtain a second solid material and a second filtrate; The silicon content in the first filtrate and the second filtrate were detected respectively, and the silicon content in the silicon-based electrode material was calculated based on the silicon content in the first filtrate and the silicon content in the second filtrate.

2. The method for detecting silicon content in silicon-based electrode materials according to claim 1, characterized in that, The solute in the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide; and / or, The mass concentration of the solute in the alkaline solution is 5% to 20%; and / or, The mass ratio of the silicon-based electrode material to be tested to the solute in the alkaline solution is 1:(8-12).

3. The method for detecting silicon content in silicon-based electrode materials according to claim 1, characterized in that, The temperature of the first reaction is 115℃~125℃; and / or, The reaction time for the first reaction is 160 min to 200 min.

4. The method for detecting silicon content in silicon-based electrode materials according to claim 1, characterized in that, The volume ratio of aqua regia to deionized water in the aqua regia solution is (3-7):5; and / or, The mass ratio of the silicon-based electrode material to be tested to the volume ratio of the aqua regia solution is 1g:8mL to 1g:12mL.

5. The method for detecting silicon content in silicon-based electrode materials according to claim 1, characterized in that, The temperature of the second reaction is 115℃~125℃; and / or, The second reaction takes 25 to 35 minutes.

6. The method for detecting silicon content in silicon-based electrode materials according to claim 1, characterized in that, After performing a first solid-liquid separation process on the first slurry to obtain a first solid material and a first filtrate, the process further includes the following steps: The first solid material is washed with deionized water to obtain a first washing solution, and the first washing solution is mixed with the first filtrate; and / or, After the second slurry undergoes a second solid-liquid separation process to obtain a second solid material and a second filtrate, the process further includes the following steps: The second solid material is washed with deionized water to obtain a second cleaning solution, and the second cleaning solution is mixed with the second filtrate.

7. The method for detecting silicon content in silicon-based electrode materials according to claim 1, characterized in that, The detection of silicon content in the first filtrate and the second filtrate includes the following steps: The silicon concentration in the first filtrate and the second filtrate was detected by inductively coupled plasma mass spectrometry.

8. The method for detecting silicon content in silicon-based electrode materials according to claim 7, characterized in that, The detection of silicon concentration in the first filtrate and the second filtrate by inductively coupled plasma mass spectrometry includes the following steps: Prepare silicon standard solutions of different concentrations; The silicon concentration in each silicon standard solution was measured by inductively coupled plasma mass spectrometry, and the response value-concentration curve was obtained. The first filtrate and the second filtrate were tested by inductively coupled plasma mass spectrometry to obtain the first response value of the first filtrate and the second response value of the second filtrate. The silicon concentration in the first filtrate and the second filtrate is obtained by comparing the first response value, the second response value, and the response value-concentration curve.

9. The method for detecting silicon content in silicon-based electrode materials according to any one of claims 1 to 8, characterized in that, The silicon-based electrode material includes at least one of lithium orthosilicate and its composite materials.

10. A device for detecting the silicon content in a silicon-based electrode material, characterized in that, include: The apparatus comprises a first reaction device, a first solid-liquid separation device, a second reaction device, a second solid-liquid separation device, and a detection device; wherein... The first reaction apparatus is used to mix the silicon-based electrode material to be tested with an alkaline solution, and after a first reaction, obtain a first slurry. The silicon-based electrode material includes at least one of silicates and their composite materials. The first solid-liquid separation device is used to perform a first solid-liquid separation process on the first slurry to obtain a first solid material and a first filtrate; The second reaction apparatus is used to mix the first solid material and the aqua regia solution, and through a second reaction, obtain a second slurry; The second solid-liquid separation device is used to perform a second solid-liquid separation process on the second slurry to obtain a second solid material and a second filtrate; The detection device is used to detect the silicon content in the first filtrate and the second filtrate respectively, and to calculate the silicon content in the silicon-based electrode material based on the silicon content in the first filtrate and the silicon content in the second filtrate.

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