Method for testing carbon-coating completeness of silicon-based material

Abstract

The application provides a testing method for carbon coating completeness of a silicon-based material, and belongs to the technical field of material testing. The method comprises the following steps: placing a first mass of strong alkaline material and a second mass of testing silicon-based material in a reaction tank to perform a reaction, and obtaining first current information output by a detection device; placing the first mass of strong alkaline material and a contrast material in the reaction tank to perform a reaction, and obtaining contrast current information output by the detection device; drawing a test image based on the first current information and the contrast current information; and calculating the carbon coating completeness of the testing silicon-based material based on the peak area and the peak current value of the testing silicon-based material in the test image, the peak area and the peak current value of the contrast material, and the second mass and the mass of the contrast material. The testing method for carbon coating completeness of the silicon-based material provided by the application can simply and conveniently test the carbon coating completeness of the silicon-based material.

Description

Technical Field

[0001] This invention belongs to the field of materials testing technology, specifically relating to a method for testing the integrity of carbon coating on silicon-based materials. Background Technology

[0002] With the rapid development of portable electronic products and new energy vehicles, people have increasingly higher requirements for anode materials. Compared with traditional graphite anode materials, silicon-based anode materials have advantages such as high energy density, good cycle performance, and high safety, and therefore silicon-based anode materials are attracting more and more attention from all sectors.

[0003] However, silicon-based materials suffer from significant volume expansion. To address this issue, a common practice is to coat silicon-based materials with carbon, which can effectively reduce volume expansion.

[0004] While carbon coating can effectively reduce volume expansion, characterizing the integrity and uniformity of the carbon coating remains a new challenge. Currently, methods for characterizing the integrity of carbon coatings on silicon-based materials mainly include SEM, TEM, and Raman spectroscopy. However, these methods suffer from problems such as complex processes, high costs, and the inability to detect only a small portion of the material, lacking representativeness. Therefore, a simple, easy-to-operate, and low-cost testing method is needed to characterize the integrity of carbon coatings. Summary of the Invention

[0005] The purpose of this invention is to meet practical needs by providing a test method for the integrity of carbon coating on silicon-based materials. This method can easily and conveniently test the integrity of carbon coating on silicon-based materials.

[0006] This invention provides a method for testing the integrity of carbon coating on silicon-based materials, the method comprising:

[0007] A first mass of strongly alkaline material and a second mass of test silicon-based material are placed in a reaction vessel to react, and the first current information output by the detection device is obtained.

[0008] The first mass of strongly alkaline material and the control material were placed in a reaction vessel to react, and the control current information output by the detection device was obtained.

[0009] A test image is drawn based on the first current information and the comparative current information, wherein the horizontal axis of the test image represents the current acquisition time and the vertical axis represents the current intensity.

[0010] Based on the peak area and peak current value of the test silicon-based material, the peak area and peak current value of the comparison material, and the mass of the second and comparison materials in the test image, the carbon coating integrity of the test silicon-based material is calculated.

[0011] Preferably, the comparative materials include pure carbon material and a carbon-free comparative silicon-based material; based on the peak area and peak current value corresponding to the test silicon-based material, the peak area and peak current value corresponding to the comparative silicon-based material, the peak area and peak current value corresponding to the pure carbon material in the test image, the second mass, the third mass of the comparative silicon-based material, and the fourth mass of the pure carbon material, the carbon coating integrity of the test silicon-based material is calculated; wherein,

[0012] The peak area corresponding to the tested silicon-based material is: the area enclosed by the curve corresponding to the pure carbon material and the baseline;

[0013] The peak area corresponding to the comparative silicon-based material is: the area enclosed by the curve corresponding to the pure carbon material and the baseline;

[0014] The peak area corresponding to the pure carbon material is 0.

[0015] Preferably, under the condition that t = 12000 / (T*v) ± 0.5, the carbon coating integrity of the tested silicon-based material is calculated using the following formula:

[0016]

[0017] Wherein, C represents the carbon coating integrity of the tested silicon-based material; S1 represents the peak area corresponding to the tested silicon-based material, S2 represents the peak area corresponding to the comparative silicon-based material, and S3 represents the peak area corresponding to the pure carbon material; m1 represents the second mass, m2 represents the third mass, and m3 represents the fourth mass; I1 represents the peak current value corresponding to the tested silicon-based material, I2 represents the peak current value corresponding to the comparative silicon-based material, and I3 represents the peak current value corresponding to the pure carbon material, wherein I1<0, I2<0, and I3>0; t represents the heating time of the reaction, T represents the heating temperature of the reaction, and v represents the carrier gas flow rate of the reaction.

[0018] Preferably, the step of placing a first mass of strongly alkaline material and a second mass of test silicon-based material in a reaction vessel for reaction includes:

[0019] Weigh out the first mass of the strongly alkaline material, place it in distilled water, stir and cool to obtain a strongly alkaline mixture;

[0020] Weigh a second mass of the test silicon-based material and place it in a mixed solution of distilled water and ethanol, then stir and cool to obtain a silicon-based material mixture.

[0021] The strong alkali mixture and the silicon-based material mixture are mixed evenly to obtain a test dispersion, and the test dispersion is placed in a reaction vessel for reaction.

[0022] The step of placing a first mass of strongly alkaline material and a control material in a reaction vessel for reaction, and obtaining the control current information output by the detection device, includes:

[0023] Weigh out the first mass of the strongly alkaline material, place it in distilled water, stir and cool to obtain a strongly alkaline mixture;

[0024] Weigh a third mass of the comparative silicon-based material and place it in a mixed solution of distilled water and ethanol, then stir and cool to obtain a mixed solution of the comparative silicon-based material;

[0025] The strong alkali mixture and the comparative silicon-based material mixture are mixed evenly to obtain a comparative silicon-based material dispersion. The comparative silicon-based material dispersion is placed in a reaction vessel for reaction.

[0026] Weigh out the first mass of the strongly alkaline material, place it in distilled water, stir and cool to obtain a strongly alkaline mixture;

[0027] Weigh out the fourth mass of pure carbon material and place it in a mixed solution of distilled water and ethanol, stir and cool to obtain a pure carbon material mixture.

[0028] The strong alkali mixture and the pure carbon material mixture are mixed evenly to obtain a pure carbon material dispersion, which is then placed in a reaction vessel for reaction.

[0029] Preferably, the first mass is 0.1 mol, the volume of distilled water used to dissolve the strong alkaline material is 40 mL, the second mass of the test silicon-based material ranges from 1 g to 5 g, the volume of distilled water used to disperse the test silicon-based material and the comparative material is 40 mL, the volume of ethanol used to disperse the test silicon-based material and the comparative material is 20 mL, the third mass of the comparative silicon-based material ranges from 1 g to 5 g, and the fourth mass of the pure carbon material ranges from 1 g to 5 g.

[0030] Preferably, the chemical reaction occurring in the reaction vessel is as follows:

[0031]

[0032] Preferably, the reaction vessel is connected to a heating device, a carrier gas control device, and a detection device; wherein the detection device includes a hydrogen sensor, which outputs current information based on the amount of hydrogen generated by the reaction.

[0033] Preferably, the heating device is set to a heating temperature range of 60℃ to 90℃ and a heating time range of 0.5h to 5h; the carrier gas flow rate ranges from 50sccm to 1000sccm.

[0034] Preferably, the carrier gas supplied to the reaction vessel by the carrier gas control device is an inert gas.

[0035] Preferably, the strongly alkaline material is any one of sodium hydroxide, lithium hydroxide, and potassium hydroxide.

[0036] Compared with the prior art, the advantages and positive effects of this application are:

[0037] The method for testing the carbon coating integrity of silicon-based materials according to embodiments of the present invention involves placing a strongly alkaline material and the test silicon-based material, as well as the strongly alkaline material and the control material, in a reaction vessel to generate hydrogen gas through a chemical reaction. The generated hydrogen gas is then detected by a detection device. This means the testing method provided by the present invention does not require high-temperature sintering and is simple and safe to operate. Furthermore, the testing method uses a detection device to detect hydrogen gas, using current information to reflect the amount of hydrogen generated, and then generates a test image. Based on the peak area and peak current value corresponding to the test silicon-based material, the peak area and peak current value corresponding to the control material, and the masses of the control and control materials in the test image, the carbon coating integrity of the test silicon-based material is calculated. This provides a more intuitive representation of the carbon coating integrity result and results in higher accuracy. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A schematic flowchart illustrating a method for testing the integrity of carbon coating on silicon-based materials according to an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the first type of test image provided in this embodiment of the invention;

[0041] Figure 3 A schematic diagram of the second type of test image provided in this embodiment of the invention;

[0042] Figure 4 A schematic diagram of the third type of test image provided in this embodiment of the invention;

[0043] Figure 5 A schematic diagram of the fourth type of test image provided in this embodiment of the invention;

[0044] Figure 6 A schematic diagram of the fifth type of test image provided in this embodiment of the invention;

[0045] Figure 7A schematic diagram of the sixth type of test image provided in this embodiment of the invention.

[0046] It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0048] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] For the first embodiment, please refer to... Figure 1 , Figure 1 This is a flowchart illustrating a method for testing the integrity of carbon coating on silicon-based materials according to an embodiment of the present invention. The testing method includes steps 101-104.

[0050] Step 101: Place the first mass of strongly alkaline material and the second mass of test silicon-based material into a reaction vessel for reaction, and obtain the first current information output by the detection device.

[0051] Specifically, the chemical reactions that occur inside the reaction vessel are as follows:

[0052]

[0053] The reaction vessel is connected to a heating device, a carrier gas control device, and a detection device. The detection device includes a hydrogen sensor, which outputs current information based on the amount of hydrogen generated in the reaction. When a chemical reaction begins in the reaction vessel, the detection device, carrier gas control device, and heating device are immediately activated sequentially. The first current information output by the detection device is then acquired. In this embodiment, the current information is used to reflect the amount of hydrogen generated.

[0054] Step 102: Place the first mass of strongly alkaline material and the control material in a reaction vessel to react, and obtain the control current information output by the detection device.

[0055] After step 101 is completed, the reaction vessel is cleaned, and then a first mass of strongly alkaline material and a control material are placed in the reaction vessel for reaction. Similar to step 101, when the chemical reaction begins in the reaction vessel, the detection device, carrier gas control device, and heating device are immediately turned on in sequence, and then the control current information output by the detection device is acquired.

[0056] As can be seen from the above, in this embodiment, the strongly alkaline material and the test silicon-based material, as well as the strongly alkaline material and the control material, are placed in a reaction vessel to react and generate hydrogen gas using a chemical method. Then, the hydrogen gas generated by the chemical reaction is detected by a detection device. In other words, the testing method provided by this invention does not require high-temperature sintering and is simple and safe to operate.

[0057] In addition, this embodiment does not require the use of expensive experimental equipment and instruments, making it low-cost, economical and environmentally friendly.

[0058] Step 103: Draw a test image based on the first current information and the comparison current information.

[0059] In the test image, the horizontal axis represents the current acquisition time, the vertical axis represents the current intensity, and the first current information and the comparison current information are represented by a curve in the test image.

[0060] Step 104: Based on the peak area and peak current value of the tested silicon-based material, the peak area and peak current value of the comparison material, and the mass of the second material and the comparison material in the test image, calculate the carbon coating integrity of the tested silicon-based material.

[0061] Therefore, this embodiment uses a detection device to detect hydrogen, which can accurately detect hydrogen, use current information to reflect the amount of hydrogen generated, and generate a test image. By comparing the peak area, the integrity of the carbon coating is intuitively displayed, and the test results are more accurate.

[0062] In the second embodiment, the comparative materials in the first embodiment include pure carbon materials and a comparative silicon-based material without carbon coating; then, based on the peak area and peak current value corresponding to the test silicon-based material, the peak area and peak current value corresponding to the comparative silicon-based material, the peak area and peak current value corresponding to the pure carbon material, the second mass, the third mass of the comparative silicon-based material, and the fourth mass of the pure carbon material in the test image, the carbon coating integrity of the test silicon-based material is calculated.

[0063] Specifically, the peak area corresponding to the silicon-based material is measured by taking the curve corresponding to the pure carbon material as the baseline and comparing it with the area enclosed by the curve corresponding to the silicon-based material. The peak area corresponding to the silicon-based material is compared by taking the curve corresponding to the pure carbon material as the baseline and comparing it with the area enclosed by the curve corresponding to the silicon-based material.

[0064] For example, please see Figure 2 The curve corresponding to pure carbon material is the baseline, therefore the peak area for pure carbon material is 0. Since the pure carbon material did not undergo the aforementioned chemical reaction, meaning the detection device did not detect the generated hydrogen gas, the peak current value for pure carbon material is positive. The peak area for silicon-based material is... Figure 2 The area enclosed by the midline and the baseline is compared to the peak area of ​​the corresponding silicon-based material. Figure 2 The area enclosed by the dashed line and the baseline. Because both the tested silicon-based material and the control silicon-based material undergo the aforementioned chemical reaction (i.e., the detection device detects the generated hydrogen gas), the peak current values ​​corresponding to both materials are negative. Furthermore, since the control silicon-based material is a carbon-free silicon-based material, it is more prone to the aforementioned chemical reaction, meaning the detection device can detect a greater amount of hydrogen gas. Therefore, the absolute value of the peak current corresponding to the control silicon-based material is greater than the absolute value of the peak current corresponding to the tested silicon-based material.

[0065] Under the condition that t=12000 / (T*v)±0.5, based on the positive correlation between hydrogen generation, peak area, and current value, the following formula is constructed to calculate the carbon coating integrity of the tested silicon-based material:

[0066]

[0067] Where C represents the carbon coating integrity of the tested silicon-based material; S1 represents the peak area corresponding to the tested silicon-based material, S2 represents the peak area corresponding to the comparative silicon-based material, and S3 represents the peak area corresponding to the pure carbon material; m1 represents the second mass, m2 represents the third mass, and m3 represents the fourth mass; I1 represents the peak current value corresponding to the tested silicon-based material, I2 represents the peak current value corresponding to the comparative silicon-based material, and I3 represents the peak current value corresponding to the pure carbon material, where I1 < 0, I2 < 0, and I3 > 0; t represents the heating time of the reaction, T represents the heating temperature of the reaction, and v represents the carrier gas flow rate of the reaction.

[0068] The mass parameter introduced in the above formula can normalize the peak area, meaning that the calculated carbon coating integrity is independent of the mass of the materials participating in the reaction.

[0069] The heating device is set with a heating temperature range of 60℃ to 90℃ and a heating time range of 0.5h to 5h; the carrier gas flow rate ranges from 50sccm to 1000sccm, and the carrier gas is at least one inert gas selected from nitrogen and argon. As an example, when the heating temperature is set to 70℃ and the carrier gas flow rate is set to 200sccm, the heating time can be set to 1h ± 0.5h, satisfying the condition t = 12000 / (T*v) ± 0.5, to ensure that the current reaches a stable state. Therefore, the carbon coating integrity of the tested silicon-based material can be accurately calculated based on the above formula.

[0070] In the third embodiment, the step of placing a first mass of strongly alkaline material and a second mass of test silicon-based material in a reaction vessel for reaction in the first embodiment can be achieved through the following steps A-C.

[0071] Step A: Weigh the first mass of the strong alkaline material, place it in distilled water, stir and cool to obtain a strong alkaline mixture.

[0072] For example, the aforementioned strong alkaline material can be any one of sodium hydroxide, lithium hydroxide, or potassium hydroxide. At 25℃±5℃, 0.1 mol of the strong alkaline material is placed in 40 ml of distilled water and stirred while cooling to 25℃±5℃ to obtain a strong alkaline mixture.

[0073] Step B: Weigh a second mass of the test silicon-based material and place it in a mixed solution of distilled water and ethanol, stir and cool to obtain a silicon-based material mixture.

[0074] For example, 1g-5g of the silicon-based material can be placed in a mixed solution of 40ml distilled water and 20ml ethanol and stirred and cooled to obtain a silicon-based material mixture.

[0075] Step C: Mix the strong alkali mixture and the silicon-based material mixture evenly to obtain a dispersion, and place the dispersion in a reaction vessel for reaction.

[0076] To make the content of this invention easier to understand, the invention will be further described in detail based on the above embodiments and specific implementation methods.

[0077] Fourth embodiment.

[0078] First, connect the reaction vessel to the heating device, carrier gas control device, and detection device.

[0079] At 25°C, 4g of sodium hydroxide, a strong alkaline material, was weighed and placed in 40mL of distilled water. The mixture was stirred and cooled to room temperature (25°C) to obtain a strong alkaline mixture. Then, 4.02g of carbon-coated (3.0%) test silicon-based material 1 was weighed and placed in a mixture of 40mL of distilled water and 20mL of ethanol. The mixture was stirred evenly to obtain a silicon-based material mixture. Finally, the strong alkaline mixture and the silicon-based material mixture were mixed evenly to form a test dispersion. The test dispersion was placed in a sealed reaction vessel.

[0080] Simultaneously activate the heating device, carrier gas control device, and detection device. Set the heating temperature of the heating device to 70℃, the heating time to 1 hour, and the carrier gas flow rate to 200 sccm. Then, acquire the current information collected by the detection device.

[0081] Clean the reaction vessel thoroughly. At 25°C, weigh 4g of the strong alkaline material sodium hydroxide and place it in 40mL of distilled water. Stir and cool to room temperature (25°C) to obtain a strong alkaline mixture. Then, weigh 1.00g of the carbon-free comparative silicon-based material and place it in a mixed solution of 40mL of distilled water and 20mL of ethanol. Stir until homogeneous to obtain a comparative silicon-based material mixture. Finally, mix the strong alkaline mixture and the comparative silicon-based material mixture to form a comparative silicon-based material dispersion. Place the comparative silicon-based material dispersion in the reaction vessel and seal it.

[0082] Simultaneously activate the heating device, carrier gas control device, and detection device. Set the heating temperature of the heating device to 70℃, the heating time to 1 hour, and the carrier gas flow rate to 200 sccm. Then, acquire the first comparative current information collected by the detection device.

[0083] Clean the reaction vessel thoroughly. At 25°C, weigh 4g of sodium hydroxide, a strong alkaline material, and place it in 40mL of distilled water. Stir and cool to 25°C to obtain a strong alkaline mixture. Then, weigh 4.01g of pure carbon material and place it in a mixture of 40mL of distilled water and 20mL of ethanol. Stir until homogeneous to obtain a pure carbon material mixture. Finally, mix the strong alkaline mixture and the pure carbon material mixture to form a pure carbon material dispersion. Place the pure carbon material dispersion in the reaction vessel and seal it.

[0084] Simultaneously activate the heating device, carrier gas control device, and detection device. Set the heating temperature of the heating device to 70℃, the heating time to 1 hour, and the carrier gas flow rate to 200 sccm. Then, acquire the second comparative current information collected by the detection device.

[0085] Based on current information and comparative current information, the following diagram is drawn: Figure 2 The test image is shown. The carbon coating integrity of the tested silicon-based material 1 is calculated according to the following formula.

[0086]

[0087] Wherein, C1 represents the carbon coating integrity of the test silicon-based material 1 with carbon coating (3.0%); S′1 represents the peak area corresponding to the test silicon-based material 1, S2 represents the peak area corresponding to the control silicon-based material, and S3 represents the peak area corresponding to the pure carbon material; m′1 represents the mass of the test silicon-based material 1, m2 represents the mass of the control silicon-based material, and m3 represents the mass of the pure carbon material; I′1 represents the peak current value corresponding to the test silicon-based material 1, I2 represents the peak current value corresponding to the control silicon-based material, and I3 represents the peak current value corresponding to the pure carbon material, where I′1 < 0, I2 < 0, and I3 > 0.

[0088] Fifth embodiment.

[0089] Compared with the fourth embodiment, the fifth embodiment replaces the 4g carbon-coated (3.0%) test silicon-based material 1 with the 3g carbon-coated (1.5%) test silicon-based material 2. The testing steps in the fifth embodiment are exactly the same as those in the fourth embodiment, and the final result is as follows. Figure 3 The test image is shown, and the carbon coating integrity of the tested silicon-based material 2 is calculated according to the following formula.

[0090]

[0091] Wherein, C2 represents the carbon coating integrity of the test silicon-based material 2 with carbon coating (1.5%); S"1 represents the peak area corresponding to the test silicon-based material 2, S2 represents the peak area corresponding to the control silicon-based material, and S3 represents the peak area corresponding to the pure carbon material; m"1 represents the mass of the test silicon-based material 2, m2 represents the mass of the control silicon-based material, and m3 represents the mass of the pure carbon material; I"1 represents the peak current value corresponding to the test silicon-based material 2, I2 represents the peak current value corresponding to the control silicon-based material, and I3 represents the peak current value corresponding to the pure carbon material, where I"1 < 0, I2 < 0, and I3 > 0.

[0092] Sixth embodiment.

[0093] Compared with the fourth embodiment, the sixth embodiment replaces the 4g carbon-coated (3.0%) test silicon-based material 1 with 4g carbon-coated (3.0%) test silicon-based material 3. The difference between test silicon-based material 3 and test silicon-based material 1 is the carbon coating process. The testing steps in the sixth embodiment are exactly the same as those in the fourth embodiment, and the final result is as follows. Figure 5 The test image is shown, and the carbon coating integrity of the tested silicon-based material 3 is calculated according to the following formula.

[0094]

[0095] Wherein, C3 represents the carbon coating integrity of the tested silicon-based material 3 with carbon coating (3.0%); S″′1 represents the peak area corresponding to the tested silicon-based material 3, S2 represents the peak area corresponding to the control silicon-based material, and S3 represents the peak area corresponding to the pure carbon material; m″′1 represents the mass of the tested silicon-based material 3, m2 represents the mass of the control silicon-based material, and m3 represents the mass of the pure carbon material; I″′1 represents the peak current value corresponding to the tested silicon-based material 3, I2 represents the peak current value corresponding to the control silicon-based material, and I3 represents the peak current value corresponding to the pure carbon material, where I″′1 < 0, I2 < 0, and I3 > 0.

[0096] First refer to Figure 2 and Figure 4 When detecting hydrogen generated in the reaction corresponding to the carbon-coated (3.0%) silicon-based material 1, the reaction had not started in the initial stage, so the detection device could not detect hydrogen, and the current was positive. When the reaction started, the detection device detected hydrogen, and the current dropped rapidly, becoming negative. As the reaction continued, the hydrogen in the reaction vessel was carried out by the carrier gas and introduced into the detection device, and the current dropped continuously and rapidly until it reached the lowest point of the first stage. At this point, the carbon shell layer of the carbon coating blocked the alkaline solution from contacting the internal SiO2. x When there is contact (0≤x<2), the reaction slows down and the current rises slowly; due to ion movement, the OH- in the alkaline solution... - SiO gradually emerges from the incomplete carbon shell. x (0≤x<2) Upon contact, the second stage of the reaction occurs, during which the current rapidly decreases until it reaches its lowest point. This process repeats continuously thereafter. Figure 4 As shown, the current undergoes a cyclical process of rising and falling until all reactive substances have reacted, at which point the current slowly rises to a more stable value.

[0097] When detecting hydrogen gas generated by the reaction of pure carbon materials, since no reaction occurs and no hydrogen gas is generated, the current remains at a relatively stable positive value.

[0098] When comparing the hydrogen produced by the reaction corresponding to silicon-based materials, the reaction inside the reaction vessel is relatively stable due to the absence of a carbon shell. The amount of hydrogen detected by the hydrogen sensor shows a trend of first increasing and then decreasing, so the current first decreases and then increases until it tends to a stable value.

[0099] Please see Figure 4 When the carbon content is higher, the carbon shell is more complete, resulting in less hydrogen produced in the reaction. Therefore, the peak area of ​​the tested silicon-based material 1 with carbon coating (3.0%) is smaller than that of the tested silicon-based material 2 with carbon coating (1.5%).

[0100] Please see Figure 2 , Figure 5 and Figure 6 When silicon-based materials are coated with the same carbon content, but the coating process is different, the integrity of the carbon shell will also be different. The above test method can clearly and intuitively reflect the integrity of carbon coating of different materials.

[0101] The data obtained through the above testing methods are shown in Table 1.

[0102] Table 1: Data table of test methods for carbon coating integrity of silicon-based materials.

[0103]

[0104] As shown in Table 1, the carbon coating integrity of silicon-based material sample 1 with carbon coating (3.0%) is 94.98%, the carbon coating integrity of silicon-based material sample 2 with carbon coating (1.5%) is 93.32%, and the carbon coating integrity of silicon-based material sample 3 with carbon coating (3.0%) using different coating processes is 95.94%. The test and analysis results are consistent with the characteristics of the samples, which indicates that the test method of the present invention has high accuracy.

[0105] Comparative example.

[0106] First, connect the reaction vessel to the heating device, carrier gas control device, and detection device.

[0107] At 25°C, 4g of sodium hydroxide, a strong alkaline material, was weighed and placed in 40mL of distilled water. The mixture was stirred and cooled to 25°C to obtain a strong alkaline mixture. Then, 4.02g of carbon-coated (3.0%) test silicon-based material 1 was weighed and placed in a mixture of 40mL of distilled water and 20mL of ethanol. The mixture was stirred evenly to obtain a silicon-based material mixture. Finally, the strong alkaline mixture and the silicon-based material mixture were mixed evenly to form a dispersion. The dispersion was placed in a sealed reaction vessel.

[0108] Simultaneously activate the heating device, carrier gas control device, and detection device. Set the heating temperature of the heating device to 70℃, the heating time to 1 hour, and the carrier gas flow rate to 200 sccm. Then, acquire the current information corresponding to 70℃ from the detection device.

[0109] Then, the reaction vessel was cleaned, and at room temperature (25℃±5℃), 4g of strong alkaline material sodium hydroxide was weighed and placed in 40mL of distilled water. The mixture was stirred and cooled to room temperature (25℃±5℃) to obtain a strong alkaline mixture. Then, 4.02g of carbon-coated (3.0%) test silicon-based material 1 was weighed and placed in a mixed solution of 40mL of distilled water and 20mL of ethanol. The mixture was stirred evenly to obtain a silicon-based material mixture. Finally, the strong alkaline mixture and the silicon-based material mixture were mixed evenly to form a dispersion. The dispersion was placed in the reaction vessel and sealed.

[0110] Simultaneously activate the heating device, carrier gas control device, and detection device. Set the heating temperature of the heating device to 30℃, the heating time to 1 hour, and the carrier gas flow rate to 200 sccm. Then, acquire the current information corresponding to 30℃ from the detection device.

[0111] The following plot is based on the current information corresponding to 70℃ and 30℃. Figure 7 The test image shown. From Figure 7 It can be seen that when the heating temperature is 30℃, the reaction in the reaction vessel is relatively slow, the current decrease and increase are relatively slower, the measured current peak area is smaller, and the experimental error is larger; therefore, the heating temperature needs to be appropriately higher, with 60℃~90℃ yielding better results. Furthermore, to obtain a more comprehensive picture of the carbon coating integrity, the heating time needs to be controlled within a certain range, at least until the current stabilizes. Therefore, the heating time can be controlled between 0.5h and 5h depending on the properties of the sample material.

[0112] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of this application in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A method for testing the integrity of carbon coating on silicon-based materials, characterized in that, The method includes: A first mass of strongly alkaline material and a second mass of test silicon-based material are placed in a reaction vessel to react, and the first current information output by the detection device is obtained. The first mass of strongly alkaline material and the control material were placed in a reaction vessel to react, and the control current information output by the detection device was obtained. A test image is drawn based on the first current information and the comparative current information, wherein the horizontal axis of the test image represents the current acquisition time and the vertical axis represents the current intensity. The comparative materials include pure carbon materials and non-carbon-coated comparative silicon-based materials; Based on the peak area and peak current value corresponding to the test silicon-based material, the peak area and peak current value corresponding to the comparison silicon-based material, the peak area and peak current value corresponding to the pure carbon material in the test image, the second mass, the third mass of the comparison silicon-based material, and the fourth mass of the pure carbon material, the carbon coating integrity of the test silicon-based material is calculated. in, The peak area corresponding to the tested silicon-based material is: the area enclosed by the curve corresponding to the pure carbon material and the baseline; The peak area corresponding to the comparative silicon-based material is: the area enclosed by the curve corresponding to the pure carbon material and the baseline; The peak area corresponding to the pure carbon material is 0; In satisfying In this case, the carbon coating integrity of the tested silicon-based material is calculated using the following formula: ； Wherein, C represents the carbon coating integrity of the tested silicon-based material; The peak area corresponding to the tested silicon-based material, The peak area corresponding to the silicon-based material being compared The peak area corresponding to the pure carbon material; For the second quality, For the third mass, The fourth mass; The peak current value corresponding to the tested silicon-based material, The peak current value corresponding to the silicon-based material being compared. Let be the peak current value corresponding to the pure carbon material, where , , ; denoted as , where is the heating time of the reaction, T is the heating temperature of the reaction, and v is the carrier gas flow rate of the reaction.

2. The method for testing the integrity of carbon coating on silicon-based materials according to claim 1, characterized in that, The step of placing a first mass of strongly alkaline material and a second mass of test silicon-based material in a reaction vessel for reaction includes: Weigh out the first mass of the strongly alkaline material, place it in distilled water, stir and cool to obtain a strongly alkaline mixture; Weigh a second mass of the test silicon-based material and place it in a mixed solution of distilled water and ethanol, then stir and cool to obtain a silicon-based material mixture. The strong alkali mixture and the silicon-based material mixture are mixed evenly to obtain a test dispersion, and the test dispersion is placed in a reaction vessel for reaction. The step of placing a first mass of strongly alkaline material and a comparative material in a reaction vessel for reaction includes: Weigh out the first mass of the strongly alkaline material, place it in distilled water, stir and cool to obtain a strongly alkaline mixture; Weigh a third mass of the comparative silicon-based material and place it in a mixed solution of distilled water and ethanol, then stir and cool to obtain a mixed solution of the comparative silicon-based material; The strong alkali mixture and the comparative silicon-based material mixture are mixed evenly to obtain a comparative silicon-based material dispersion. The comparative silicon-based material dispersion is placed in a reaction vessel for reaction. Weigh out the first mass of the strongly alkaline material, place it in distilled water, stir and cool to obtain a strongly alkaline mixture; Weigh out the fourth mass of pure carbon material and place it in a mixed solution of distilled water and ethanol, stir and cool to obtain a pure carbon material mixture. The strong alkali mixture and the pure carbon material mixture are mixed evenly to obtain a pure carbon material dispersion, which is then placed in a reaction vessel for reaction.

3. The method for testing the integrity of carbon coating on silicon-based materials according to claim 2, characterized in that, The first mass is 0.1 mol, the volume of distilled water used to dissolve the strong alkaline material is 40 mL, the second mass of the test silicon-based material ranges from 1 g to 5 g, the volume of distilled water used to disperse the test silicon-based material and the comparative material is 40 mL, the volume of ethanol used to disperse the test silicon-based material and the comparative material is 20 mL, the third mass of the comparative silicon-based material ranges from 1 g to 5 g, and the fourth mass of the pure carbon material ranges from 1 g to 5 g.

4. The method for testing the integrity of carbon coating on silicon-based materials according to claim 1, characterized in that, The chemical reaction that occurs inside the reaction vessel is as follows: 。 5. The method for testing the integrity of carbon coating on silicon-based materials according to claim 4, characterized in that, The reaction vessel is connected to a heating device, a carrier gas control device, and a detection device; wherein, the detection device includes a hydrogen sensor, which outputs current information based on the amount of hydrogen generated by the reaction.

6. The method for testing the integrity of carbon coating on silicon-based materials according to claim 5, characterized in that, The heating device is set to a heating temperature range of 60℃ to 90℃ and a heating time range of 0.5h to 5h; the carrier gas flow rate ranges from 50sccm to 1000sccm.

7. The method for testing the integrity of carbon coating on silicon-based materials according to claim 5, characterized in that, The carrier gas supplied to the reaction vessel by the carrier gas control device is an inert gas.

8. The method for testing the integrity of carbon coating on silicon-based materials according to claim 1, characterized in that, The strongly alkaline material is any one of sodium hydroxide, lithium hydroxide, and potassium hydroxide.

Images