Control method of production procedure for preparing silicon-carbon negative electrode through chemical vapor deposition

Abstract

The invention relates to a control method of a production procedure for preparing a silicon-carbon negative electrode through chemical vapor deposition. The control method comprises the following steps: 1, setting a reactor operation temperature range, a sampler temperature, a sampling branch pressure difference, a transfer tank capacity and a transfer tank vacuum degree; 2, sampling a production program in real time; 3, testing the surface area; 4, testing the pore volume; 5, testing the silicon content; 6, comparing with a standard curve; and 7, evaluating the quality of the production program according to a comparison result. Aiming at the defects of the current deposition process, a sampling branch is introduced on a reaction facility, so that sampling of products in real-time reaction is realized. A valve and a vacuum replacement technology are adopted to isolate the contact between gas in the reactor and a sampling atmosphere in a sampling process, so that the purity and the reliability of a sample are ensured; according to the invention, the fineness of process control is improved, the difference between batches is reduced, and the stability of the process and the qualified rate of products are obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon-carbon negative electrode production control, in particular to a control method for a production procedure of preparing silicon-carbon negative electrodes by chemical vapor deposition. Background Art

[0002] Chemical vapor deposition is used to prepare silicon-carbon negative electrode materials for lithium batteries. Silicon-carbon composite materials are prepared by chemical vapor deposition of silicon materials in porous carbon particles. During the deposition process, porous carbon particles with a specific surface area of ​​more than 1000m2 / g are distributed in the reactor. The reactor temperature is raised to 400-600C under the protection of inert gas, and monosilane (SiH4) gas is introduced. After the monosilane molecules are adsorbed into the porous carbon, they are pyrolyzed at high temperature to form nano-silicon particles uniformly dispersed inside the porous carbon particles. In order to prevent the oxidation reaction of the nano-silicon component in the air, after the silicon is filled, the silane gas needs to be switched to a carbon source gas (acetylene, propane, or propylene) to carbon-coat the formed silicon-carbon composite particles. Therefore, during the entire deposition process, the filling amount and filling uniformity of silicon during the deposition process must be tested in real time to accurately determine the switching time point of the silane and carbon source gases, accurately control the process, and achieve a stable and consistent deposition process.

[0003] Since both silane and carbon source gas are flammable and explosive molecules, the existing process control determines the time points of silicon deposition and carbon deposition by controlling the reaction time and flow rate. However, this method lacks control precision, and the performance of reaction products from different batches varies greatly, resulting in poor process stability and low product qualification rate. Summary of the invention

[0004] The object of the present invention is to provide a control method for the production process of preparing silicon-carbon negative electrode by chemical vapor deposition to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A control method for a production process of preparing a silicon-carbon negative electrode by chemical vapor deposition comprises the following steps:

[0007] 1. Set the reactor operating temperature range, sampler temperature, sampling branch pressure difference, transfer tank capacity, and transfer tank vacuum degree;

[0008] 2. Real-time sampling of production procedures;

[0009] 3. Test surface area;

[0010] 4. Test pore volume;

[0011] 5. Test silicon content;

[0012] 6. Compare with the standard curve;

[0013] 7. Evaluate the quality of the production process based on the comparison results.

[0014] Further:

[0015] The reactor operating temperature range is set to 400-600°C, the sampler temperature is set to no higher than 50°C, and the sampling branch pressure difference is set to between 0.1-1.0 kPa;

[0016] The transfer tank capacity is set to 50-500 ml, and the vacuum degree of the transfer tank is controlled at 0.1-0.5 Pa; thereby, by controlling the pressure difference between the reactor and the sampling branch, real-time sampling of the reaction product is achieved, while ensuring the isolation of the reaction gas and the sampling atmosphere.

[0017] The surface area measurement range of the test surface area procedure is 5-1500m 2 / g;

[0018] The pore volume measurement range of the pore volume test procedure is 0.05-1.5cm 3 / g, single test time shall not exceed 35 minutes;

[0019] In the silicon content test procedure, the filling amount and filling uniformity of silicon are monitored in real time to determine the switching time point of silane gas and carbon source gas, wherein the switching time point of silane gas and carbon source gas is controlled when the reaction proceeds to 60-90% and the filling uniformity standard deviation is less than 5%;

[0020] In the standard curve comparison procedure, the standard curve is the variation trend of the specific surface area and pore volume of the material during the deposition process, and the deviation between the real-time data and the standard curve is set within 5%;

[0021] The frequency of adjusting each process parameter in step 1 does not exceed once per hour, and the adjustment range does not exceed ±10% of the initial set value.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention aims at the defects of the current deposition process, and realizes the sampling of the products in the real-time reaction by introducing a sampling branch in the reaction facility. The specific method is to ensure the real-time and accuracy of the sampling process by controlling the pressure difference between the reactor and the sampling branch. A transfer tank is introduced into the sampling accessory, and valves and vacuum replacement technology are used to isolate the contact between the gas in the reactor and the sampling atmosphere during the sampling process, thereby ensuring the purity and reliability of the sample;

[0024] 2. The specific surface area and pore volume data of the sample are quickly tested on the iPore test station, and compared with the standard curve of the porous carbon material silicon deposition process to determine the reaction progress. This method improves the precision of process control, reduces the differences between batches, and significantly improves the stability of the process and the qualified rate of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the workflow of this patent.

[0026] Figure 2 This is a schematic diagram of the process control principle of this patent.

[0027] Figure 3 Schematic diagram of the sampling structure for the production of silicon-carbon negative electrode fluidized high-temperature furnace.

[0028] Among them, 1 is the standard curve, 2 is the test point, 3 is the sampling valve, 4 is the sealed sampler, and 5 is the silicon-carbon negative electrode fluidized high temperature furnace. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] A control method for a production process of preparing a silicon-carbon negative electrode by chemical vapor deposition comprises the following steps:

[0031] 1. Set the reactor operating temperature range, sampler temperature, sampling branch pressure difference, transfer tank capacity, and transfer tank vacuum degree;

[0032] 2. Real-time sampling of production procedures;

[0033] 3. Test surface area;

[0034] 4. Test pore volume;

[0035] 5. Test silicon content;

[0036] 6. Compare with the standard curve;

[0037] 7. Evaluate the quality of the production process based on the comparison results.

[0038] Further:

[0039] The reactor operating temperature range is set to 400-600°C, the sampler temperature is set to no higher than 50°C, and the sampling branch pressure difference is set to between 0.1-1.0 kPa;

[0040] The transfer tank capacity is set to 50-500 ml, and the vacuum degree of the transfer tank is controlled at 0.1-0.5 Pa; thereby, by controlling the pressure difference between the reactor and the sampling branch, real-time sampling of the reaction product is achieved, while ensuring the isolation of the reaction gas and the sampling atmosphere.

[0041] The surface area measurement range of the test surface area procedure is 5-1500m 2 / g;

[0042] The pore volume measurement range of the pore volume test procedure is 0.05-1.5cm 3 / g, single test time shall not exceed 35 minutes;

[0043] In the silicon content test procedure, the filling amount and filling uniformity of silicon are monitored in real time to determine the switching time point of silane gas and carbon source gas, wherein the switching time point of silane gas and carbon source gas is controlled when the reaction proceeds to 60-90% and the filling uniformity standard deviation is less than 5%;

[0044] In the standard curve comparison procedure, the standard curve is the variation trend of the specific surface area and pore volume of the material during the deposition process, and the deviation between the real-time data and the standard curve is set within 5%;

[0045] The frequency of adjusting each process parameter in step 1 does not exceed once per hour, and the adjustment range does not exceed ±10% of the initial set value.

[0046] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A control method for the production process of preparing silicon-carbon negative electrode by chemical vapor deposition, characterized in that: The steps include: 1) Set the reactor operating temperature range, sampler temperature, sampling branch pressure difference, transfer tank capacity, and transfer tank vacuum degree; 2) Real-time sampling of production procedures; 3) Test surface area; 4) Test pore volume; 5) Test silicon content; 6) Compare with the standard curve; 7) Evaluate the quality of the production process based on the comparison results.

2. The control method for the production process of preparing silicon-carbon negative electrode by chemical vapor deposition according to claim 1, characterized in that: The operating temperature range of the reactor is set to 400-600°C, the sampler temperature is set to no higher than 50°C, and the pressure difference of the sampling branch is set to between 0.1-1.0 kPa.

3. The control method for the production process of preparing silicon-carbon negative electrode by chemical vapor deposition according to claim 1, characterized in that: The transfer tank capacity is set to 50-500 ml, and the vacuum degree of the transfer tank is controlled at 0.1-0.5 Pa; thereby, by controlling the pressure difference between the reactor and the sampling branch, real-time sampling of the reaction product is achieved, while ensuring the isolation of the reaction gas and the sampling atmosphere.

4. The control method for the production process of preparing silicon-carbon negative electrode by chemical vapor deposition according to claim 1, characterized in that: The surface area measurement range of the test surface area procedure is 5-1500m 2 / g; the pore volume measurement range of the pore volume test procedure is 0.05-1.5cm 3 / g, single test time does not exceed 35 minutes.

5. The control method for the production process of preparing silicon-carbon negative electrode by chemical vapor deposition according to claim 1, characterized in that: In the silicon content testing procedure, the silicon filling amount and filling uniformity are monitored in real time to determine the switching time point of the silane gas and the carbon source gas, wherein the switching time point of the silane gas and the carbon source gas is controlled when the reaction proceeds to 60-90%, and the filling uniformity standard deviation is less than 5%.

6. The control method for the production process of preparing silicon-carbon negative electrode by chemical vapor deposition according to claim 1, characterized in that: In the standard curve comparison procedure, the standard curve is the variation trend of the specific surface area and pore volume of the material during the deposition process, and the deviation between the real-time data and the standard curve is set within 5%.

7. The control method for the production process of preparing silicon-carbon negative electrode by chemical vapor deposition according to claim 1, characterized in that: The frequency of adjusting each process parameter in step 1 does not exceed once per hour, and the adjustment range does not exceed ±10% of the initial set value.

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