Gas inlet system for preparing silicon-carbon negative electrode material through vapor deposition and control method of gas inlet system

Abstract

The invention discloses a gas inlet system for preparing a silicon-carbon negative electrode material through vapor deposition and a control method thereof, and the system comprises a pressure monitoring unit which is used for monitoring the pressure in a vapor deposition furnace in real time and transmitting the pressure to a control unit; the gas circuit unit comprises a silane gas circuit, an acetylene gas circuit and a nitrogen gas circuit, the nitrogen gas circuit comprises a main protection gas circuit, an acetylene purging / replacement gas circuit, a silane purging / replacement gas circuit and a silane exhaust gas circuit which are arranged independently, and the control unit is in signal connection with all pneumatic valves, mass flow meters and pressure transmitters of the gas circuit unit. And the switching of each gas path is controlled. The pressure monitoring unit, the gas path unit and the control unit are matched with one another to form closed-loop control, so that the control unit can control switching of different gas path branches in the gas path unit according to actual conditions, manual operation is replaced, the production efficiency and the product quality are greatly improved, meanwhile, the gas path unit is further provided with a protective gas path, and the production cost is reduced. And the safety of the whole system is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion battery material preparation, and in particular to an air inlet system for preparing silicon-carbon negative electrode material by vapor deposition and a control method thereof. BACKGROUND

[0002] As a key negative electrode material for the next generation of high-energy-density lithium ion batteries, silicon-carbon composite material is usually prepared by vapor deposition (such as CVD) involving multiple process gases such as silane and acetylene. The process is intrinsically complex and includes multiple procedures with different parameters. Taking the core "silicon deposition" procedure as an example, it can be subdivided into multiple stages (such as preheating, nucleation, growth, stabilization, etc.), and the gas medium, gas flow rate, gas inlet time, and corresponding high-temperature furnace optimal pressure range required for each stage are all quite different. Therefore, real-time and stable monitoring of the pressure in the high-temperature furnace is not only related to the deposition quality, but also has crucial guiding significance for judging whether the current procedure is completed and whether it should be safely switched to the next procedure. Currently, the mainstream production mode in this field still highly depends on manual intervention. The operator needs to manually set and adjust the gas flow, on-off valve, and monitor the pressure gauge at different process stages according to experience. This mode has the following outstanding drawbacks: 1. Efficiency and cost issues: full-time attendance is required, resulting in high labor costs and low production efficiency, making it difficult to achieve continuous and large-scale production. 2. Quality and consistency issues: manual operation inevitably introduces large errors, and there are delays and deviations in the judgment and parameter adjustment at the stage switching point, resulting in large fluctuations in product quality and poor repeatability within the same batch, which seriously affects the performance consistency of silicon-carbon negative electrode material. 3. Major safety hazards: silane (SiH4) used is self-igniting, and acetylene (C2H2) is flammable and explosive, manual operation not only exposes personnel directly to a dangerous environment, but more critically, for sudden conditions such as pressure abnormalities, manual response has serious lag, and effective measures cannot be taken within milliseconds, which can easily lead to serious safety accidents. Some existing automated equipment has achieved single control of some parameters, but generally lacks "formulation" coordinated control capability for complex multi-stage processes and multi-level, proactive safety interlocking mechanisms that can respond to various abnormal conditions. Therefore, there is an urgent need in this field for an intelligent air inlet system that is fully functional, safe and reliable, can accurately control multiple process parameters at the same time, and is easy to operate, to fundamentally improve the safety, efficiency, and product quality of the silicon-carbon negative electrode material preparation process. SUMMARY

[0003] The present application aims at the problems in the prior art and discloses a gas inlet system for preparing silicon-carbon negative electrode material by vapor deposition and a control method thereof.

[0004] The present application is realized by the following technical solutions: The present application first provides a gas inlet system for preparing silicon-carbon negative electrode material by vapor deposition, which comprises A pressure monitoring unit is used to monitor the pressure in the vapor deposition furnace in real time and transmit the pressure to the control unit. The gas path unit comprises a silane gas path, an acetylene gas path and a nitrogen gas path, wherein the nitrogen gas path comprises a main protection gas path, an acetylene purging / replacement gas path, a silane purging / replacement gas path and a silane evacuation gas path which are independently arranged. The control unit is connected with all pneumatic valves, mass flow meters and pressure transmitters of the gas path unit and controls the switching of each gas path.

[0005] As a further solution, the control unit comprises a controller and a one-key start-stop module which can realize one-key start-stop function according to the instructions of the controller or external instructions.

[0006] As a further solution, the acetylene gas path comprises an acetylene inlet, a first three-way joint, a second three-way joint, a second four-way joint, a sixth three-way joint and a high-temperature furnace which are sequentially connected by pipelines, a pressure transmitter is installed on the sixth three-way joint, a pipeline connected to another opening of the sixth three-way joint is installed with a second flame arrester, and the second flame arrester is externally installed with a fourth pneumatic normally closed valve; wherein a fourth pneumatic normally open valve is further installed on the pipeline between the acetylene inlet and the first three-way joint, a first manual diaphragm valve and a first pressure reducing valve are further installed on the pipeline between the first three-way joint and the second three-way joint, a first mass flow meter MFC1 is installed on the pipeline between the second three-way joint and the second four-way joint, and the first mass flow meter MFC1, the pressure transmitter and the fourth pneumatic normally open valve are all signal-connected to the controller.

[0007] As a further scheme, the silane gas path includes a silane inlet, a No. 3 three-way valve, a No. 4 three-way valve, a No. 5 three-way valve, a No. 2 four-way valve, a No. 6 three-way valve and a high-temperature furnace connected in sequence by pipelines, the No. 5 three-way valve is further connected to a vacuum generator by a pipeline, and a No. 3 pneumatic normally closed valve is installed on the pipeline between the two; wherein a No. 1 pneumatic normally open valve is further installed on the pipeline between the silane inlet and the No. 3 three-way valve, a No. 5 manual diaphragm valve and a No. 3 pressure reducing valve are further installed on the pipeline between the No. 3 three-way valve and the No. 4 three-way valve, a No. 3 mass flow meter MFC3 is installed on the pipeline between the No. 3 three-way valve and the No. 2 four-way valve, and a No. 3 pneumatic normally open valve is installed on the pipeline between the No. 5 three-way valve and the No. 2 four-way valve, the No. 3 mass flow meter MFC3, the No. 3 pneumatic normally open valve and the No. 5 pneumatic normally open valve are all signal connected to the controller.

[0008] As a further scheme, the main protection gas path includes a nitrogen inlet, a No. 1 four-way valve, a gas distribution, a No. 2 four-way valve, a No. 6 three-way valve and a high-temperature furnace connected in sequence by pipelines, wherein the second opening of the No. 1 four-way valve is connected to the nitrogen inlet, wherein a No. 3 manual diaphragm valve and a No. 2 pressure reducing valve are installed on the pipeline between the No. 1 four-way valve and the gas distribution, and a No. 2 pneumatic normally open valve and a No. 2 mass flow meter MFC2 signal connected to the controller are installed on the pipeline between the gas distribution and the No. 2 four-way valve.

[0009] As a further scheme, the pipeline connection between the gas distribution and the No. 2 three-way valve forms an acetylene backup branch, a No. 6 pneumatic normally closed valve is installed on the acetylene backup branch, the pipeline connection between the gas distribution and the No. 4 three-way valve forms a silane backup branch, a No. 7 pneumatic normally closed valve is installed on the silane backup branch, and the No. 6 pneumatic normally closed valve and the No. 7 pneumatic normally closed valve are respectively signal connected to the controller.

[0010] As a further scheme, the acetylene purge / replacement gas path includes a nitrogen inlet, a No. 1 four-way valve, a No. 5 pneumatic normally closed valve, a No. 1 one-way valve and a No. 1 three-way valve connected in sequence by pipelines, and the No. 5 pneumatic normally closed valve is connected in parallel with a No. 2 manual diaphragm valve as a left and right backup valve, and the No. 2 manual diaphragm valve is in a normally closed state by default, wherein the No. 5 pneumatic normally closed valve is signal connected to the controller.

[0011] As a further scheme, the silane purge / replacement gas path includes a nitrogen inlet, a No. 1 four-way valve, a No. 1 pneumatic normally closed valve, a No. 2 one-way valve and a No. 2 three-way valve connected in sequence by pipelines, and the No. 1 pneumatic normally closed valve is further connected in parallel with a No. 4 manual diaphragm valve as a backup valve, and the No. 4 manual diaphragm valve is in a normally closed state by default, wherein the No. 1 pneumatic normally closed valve is signal connected to the controller.

[0012] As a further scheme, the silane air exhaust air path includes a nitrogen gas inlet, a first four-way valve, a second pneumatic normally closed valve, a vacuum generator, a third one-way valve and a first flame arrester connected in sequence, and is discharged through the first flame arrester, the second pneumatic normally closed valve, the vacuum generator and the first flame arrester are signal connected to the controller respectively; the vacuum generator is also connected to the fifth three-way valve, and a third pneumatic normally closed valve is installed on the pipeline between the two, and the third pneumatic normally closed valve is signal connected to the controller.

[0013] The application also provides a control method of the gas inlet system for preparing silicon-carbon negative electrode material by vapor deposition. S1, at room temperature, using nitrogen to purge the furnace body and pipeline to exclude air, while introducing acetylene to establish a basic inert atmosphere; S2, on the basis of S1, heating and continuously introducing nitrogen to maintain the positive pressure in the furnace; S3, at the target temperature, first introduce nitrogen as carrier gas and protective gas, then introduce silane gas for silane deposition, and when the silane is introduced, a gradual safety protection is adopted; S4, at high temperature, acetylene gas is introduced to crack on the surface of the deposited nanosilicon to form a uniform carbon coating layer; S5, after the reaction is completed, the furnace body is cooled to a safe temperature under the protection of continuous nitrogen.

[0014] The application has the following characteristics and advantages: (1) The application forms a depth protection system combining software and hardware through multi-stage safety interlocking, special air displacement and replacement pipeline and one-key emergency stop function, can respond to sudden conditions in milliseconds, greatly improves the intrinsic safety level of the system, and uses intelligent control instead of manual operation, greatly improves the production efficiency and product consistency, and reduces the labor cost and intensity.

[0015] (2) The application ensures the accurate execution of each process parameter based on the accurate flow control of the mass flow meter and the real-time feedback control of the furnace pressure, and provides reliable guarantee for the preparation of high-quality silicon-carbon negative electrode material.

[0016] (3) The one-key interruption / resumption function of the application enhances the flexibility of the system in response to exceptions; all process data records are traceable, which is convenient for quality tracing and process optimization. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creating any creative labor.

[0018] Figure 1 A flow chart of a gas inlet system for preparing a silicon-carbon negative electrode material by vapor deposition according to an embodiment of the present application; Figure 2 A nitrogen replacement control principle block diagram of an acetylene pipeline according to an embodiment of the present application; Figure 3 A nitrogen replacement control principle block diagram of a silane pipeline according to an embodiment of the present application; Figure 4 A silane air exhaust pipeline control principle block diagram according to an embodiment of the present application; Figure 5 A control principle block diagram of a main protection gas pipeline of a silane gas pipeline, an acetylene gas pipeline and a nitrogen gas pipeline according to an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present application, the present application will be described more fully below, and embodiments of the present application will be given, but the scope of the present application is not limited thereto.

[0020] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0021] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0022] The prior art preparation of silicon-carbon negative electrode material is all manual operation, since the silane involved in the material production process is self-igniting, and acetylene is flammable and explosive, manual operation not only exposes personnel directly to a dangerous environment, but more fatally, for sudden conditions such as pressure abnormality, manual response has serious hysteresis, and cannot take effective measures within milliseconds, which easily leads to serious safety accidents. The present application forms a closed-loop control through the cooperation of the pressure monitoring unit, the gas path unit and the control unit, so that the control unit can control the switching of different gas path branches in the gas path unit according to the actual situation, wherein the multiple protection gas paths arranged in the gas path increase the safety from the process itself through the switching of different gas paths, and in addition, intelligent control replaces manual operation, greatly improving production efficiency and product quality.

[0023] An air inlet system for preparing silicon-carbon negative electrode material by vapor deposition, as shown in Figures 1 to 5 including a gas path unit, a pressure monitoring unit and a control unit, The pressure monitoring unit is used to monitor the pressure in the vapor deposition furnace in real time and transmit it to the control unit. The gas path unit includes a silane gas path, an acetylene gas path and a nitrogen gas path, wherein the nitrogen gas path includes a main protection gas path, an acetylene purging / replacement gas path, a silane purging / replacement gas path and a silane evacuation gas path, the silane evacuation gas path includes a vacuum generator and a fire arrestor, and is used to safely perform vacuumization-inertization circulation replacement on the silane gas path. The control unit is connected with all pneumatic valves, mass flow meters and pressure transmitters of the gas path unit, and controls the switching of each gas path.

[0024] In some embodiments, the pressure monitoring unit is a pressure transmitter, In some embodiments, the control unit includes a controller and a one-key start-stop module, and preferably the controller is a PLC.

[0025] The one-key start-stop module can realize one-key start-stop function according to the instruction of the controller or external instruction.

[0026] The control unit records all process parameters and equipment state data in real time, and exports or sends these data to a remote control center or a cloud data storage center.

[0027] The acetylene gas path includes an acetylene inlet, a first three-way valve, a second three-way valve, a second four-way valve (first opening and fourth opening), a sixth three-way valve and a high-temperature furnace connected in sequence, a pressure transmitter is installed on the sixth three-way valve, a second fire arrestor is installed on another opening of the sixth three-way valve, and a fourth pneumatic normally closed valve is installed outside the second fire arrestor for pressure relief; this gas path is used to provide the carbon source required for the reaction, The pipeline between the acetylene inlet and the No. 4 three-way valve is further provided with a No. 4 pneumatic normally open valve, the pipeline between the No. 1 three-way valve and the No. 2 three-way valve is further provided with a No. 1 manual diaphragm valve and a No. 1 pressure reducing valve, the No. 1 pressure reducing valve is used for stabilizing the inlet pressure, the No. 1 manual diaphragm valve is used for maintenance isolation, the pipeline between the No. 2 three-way valve and the No. 2 four-way valve is provided with a No. 1 mass flow meter MFC1, and the No. 1 mass flow meter MFC1, the pressure transmitter and the No. 4 pneumatic normally open valve are signal connected to the controller, so as to realize accurate control of the gas circuit.

[0028] The silane gas circuit comprises, which are sequentially connected in the pipeline, a silane inlet, a No. 3 three-way valve, a No. 4 three-way valve, a No. 5 three-way valve, a No. 2 four-way valve (third opening and fourth opening), a No. 6 three-way valve and a high-temperature furnace, the No. 5 three-way valve is further connected to the No. 2 vacuum generator in the pipeline, and a No. 3 pneumatic normally closed valve is installed between the No. 5 three-way valve and the No. 2 vacuum generator; the gas circuit is used for providing a silicon source required by the reaction; The pipeline between the silane inlet and the No. 3 three-way valve is further provided with a No. 1 pneumatic normally open valve, the pipeline between the No. 3 three-way valve and the No. 4 three-way valve is further provided with a No. 5 manual diaphragm valve and a No. 3 pressure reducing valve, the No. 3 pressure reducing valve is used for stabilizing the inlet pressure, the No. 5 manual diaphragm valve is used for maintenance isolation, the pipeline between the No. 3 three-way valve and the No. 2 four-way valve is provided with a No. 3 mass flow meter MFC3, and the pipeline between the No. 5 three-way valve and the No. 2 four-way valve is provided with a No. 3 pneumatic normally open valve, The No. 3 mass flow meter MFC3, the No. 3 pneumatic normally open valve and the No. 5 pneumatic normally open valve are signal connected to the controller, so as to realize accurate control of the gas circuit.

[0029] The nitrogen gas circuit is the most complex in path, which is divided into four branches after the No. 1 four-way valve, which are respectively a main protection gas circuit, an acetylene purge / replacement gas circuit, a silane purge / replacement gas circuit and a silane evacuation gas circuit.

[0030] The main protection gas circuit comprises, which are sequentially connected in the pipeline, a nitrogen inlet, a No. 1 four-way valve (second opening and fourth opening), a gas distribution and exhaust, a No. 2 four-way valve (second opening and fourth opening), a No. 6 three-way valve and a high-temperature furnace, wherein the second opening of the No. 1 four-way valve is connected to the nitrogen inlet, and the main protection gas circuit enters the reaction furnace as a carrier gas or a protection gas.

[0031] The gas distribution row divides the gas input by the first four-way into three paths, a third manual diaphragm valve and a second pressure reducing valve are installed on the pipeline between the first four-way and the gas distribution row, a second pneumatic normally open valve and a second mass flow meter MFC2 are installed on the pipeline between the gas distribution row and the second four-way, the gas distribution row is also connected to the second three-way and the fourth three-way through the pipeline, and the pipeline connection between the gas distribution row and the second three-way forms an acetylene standby branch, a sixth pneumatic normally closed valve is installed on the branch, the pipeline connection between the gas distribution row and the fourth three-way forms a silane standby branch, and a seventh pneumatic normally closed valve is installed on the branch. The two standby branches are used to compensate for the insufficient nitrogen flow of MFC2; silane and acetylene cannot be passed at the same time, when silane is passed, the acetylene standby branch does not work, and if the process requires silane, the nitrogen flow rate increases and MFC2 has reached the maximum range but still cannot meet the requirements, the acetylene standby branch is started to allow MFC1 to pass nitrogen to compensate. The working principle of the silane standby branch is the same as that of the acetylene standby branch.

[0032] The second pneumatic normally open valve, the sixth pneumatic normally closed valve and the seventh pneumatic normally closed valve are respectively signal connected to the controller.

[0033] The acetylene purging / replacement gas path includes a nitrogen gas inlet, a first four-way (first opening and second opening), a fifth pneumatic normally closed valve, a one-way valve and a first three-way connected in sequence by pipelines, and the fifth pneumatic normally closed valve is connected in parallel with a second manual diaphragm valve as a left and right standby valve, and the second manual diaphragm valve is in a normally closed state by default, wherein the fifth pneumatic normally closed valve is signal connected to the controller. The acetylene pipeline purging / replacement gas path is used for nitrogen purging of the acetylene pipeline before and after the process to ensure safety.

[0034] The silane purging / replacement gas path includes a nitrogen gas inlet, a first four-way (second opening and third opening), a first pneumatic normally closed valve, a second one-way valve and a second three-way connected in sequence by pipelines, and the first pneumatic normally closed valve is also connected in parallel with a fourth manual diaphragm valve as a standby valve, and the fourth manual diaphragm valve is in a normally closed state by default, wherein the first pneumatic normally closed valve is signal connected to the controller. The silane pipeline purging / replacement gas path is used for nitrogen purging of the silane pipeline before and after the process to ensure safety.

[0035] The silane evacuation gas path includes a nitrogen gas inlet, a first four-way (second opening and fourth opening), a second pneumatic normally closed valve, a vacuum generator, a third one-way valve and a first flame arrester connected in sequence by pipelines, and the second pneumatic normally closed valve, the vacuum generator and the first flame arrester are respectively signal connected to the controller. This is a key safety design, because the gas distribution row is connected to the fourth three-way, so that this gas path can perform "vacuum pumping-nitrogen filling" cycle cleaning on the silane pipeline, completely eliminating dangerous residual gas. The design of this gas path reflects the additional safety protection of the self-igniting gas silane.

[0036] In one embodiment, the vacuum generator is also connected to the No. 5 three-way pipe, and a No. 3 pneumatic normally closed valve is installed on the pipe between the two, and the signal of the No. 3 pneumatic normally closed valve is connected to the controller. The trigger logic of the No. 3 pneumatic normally closed valve is: when the silane pipeline needs to be purged, the opening and closing of the No. 3 pneumatic normally closed valve is intermittent, so that the silane pipeline is alternately under high pressure and low pressure, which is more conducive to the removal of silane in the pipeline.

[0037] In some embodiments, the model of all manual diaphragm valves is FUND-71G-6.3, the model of all pneumatic normally open valves is FP-NSD-71-6.35, the inlet pressure of all pressure reducing valves is 2MPa, the outlet pressure of all pressure reducing valves is 0.8MPa, the flow range of all mass flow meters is 0-50L / min, and the material needs to be selected according to the medium; the model of the pressure transmitter is SUP-P300, which is used to monitor the pressure in the furnace, the size of all pneumatic normally closed valves and check valves is 6.35mm, and the flame arrester needs to have an explosion-proof function. The material of the gas distribution, three-way pipe and four-way pipe should be SS316L.

[0038] A control method of a gas inlet system for preparing a silicon-carbon negative electrode material by vapor deposition is as follows: S1, replacement at room temperature In order to establish a basic inert atmosphere, the furnace body and the pipeline are purged with nitrogen at room temperature to exclude air (oxygen), and a carbon source (acetylene) is introduced to prepare for the subsequent reaction.

[0039] Nitrogen and acetylene are introduced through the nitrogen gas path and the acetylene gas path respectively, and the specific method is as follows: S11, nitrogen gas path: the controller controls the opening of the No. 2 pneumatic normally open valve. Nitrogen flows out from the nitrogen gas source and flows through the path: nitrogen gas source → No. 1 four-way pipe → No. 3 manual diaphragm valve → No. 2 pressure reducing valve → gas distribution → No. 2 pneumatic normally open valve → MFC2 → No. 2 four-way pipe → No. 6 three-way pipe → high-temperature furnace. MFC2 works at a set high flow rate.

[0040] S12, acetylene gas path: the controller controls the opening of the No. 4 pneumatic normally open valve. Acetylene flows out from the acetylene gas source and flows through the path: acetylene gas source → No. 1 manual diaphragm valve → No. 1 pressure reducing valve → No. 4 pneumatic normally open valve → No. 1 three-way pipe → MFC1 → No. 2 four-way pipe → No. 6 three-way pipe → high-temperature furnace. MFC1 works at a set flow rate.

[0041] Control points: this stage does not monitor the furnace pressure, and the core goal is to replace quickly and at a high flow rate; the duration is T1.

[0042] Through this step, oxygen is completely removed before heating, greatly avoiding the risk of explosion of flammable gases such as acetylene meeting oxygen at high temperature, and improving the safety of the system. Nitrogen and acetylene are introduced at the same time, which preloads the reactants while establishing an inert atmosphere, shortens the total process time, and greatly improves the work efficiency. The valve switching of this step is automatically completed by the controller without manual intervention, ensuring consistency and high automation.

[0043] S2, on the basis of S1, continue to replace by heating; During the programmed heating process, nitrogen is continuously introduced to maintain the positive pressure in the furnace, prevent air from flowing back, and further purify the furnace environment. This is achieved by introducing only nitrogen, and the specific gas path and control logic are as follows: Nitrogen gas path: the controller closes the No. 4 pneumatic normally open valve (acetylene path) and keeps the No. 2 pneumatic normally open valve (nitrogen protection path) open. The nitrogen flow path is: nitrogen gas source → No. 1 four-way valve → No. 3 manual diaphragm valve → No. 2 pressure reducing valve → gas distribution exhaust → No. 2 pneumatic normally open valve → MFC2 → No. 2 four-way valve → No. 6 three-way valve → high temperature furnace. Adjust MFC2 to a moderate flow rate.

[0044] Control points: This stage still does not monitor the furnace pressure, the focus is to cooperate with the heating program and maintain stable positive pressure; Duration: T2 (time required to heat to target temperature).

[0045] Through this step, the gas inlet system only introduces inert nitrogen gas during the critical heating stage, eliminating any risk of flammable gas presence, making the system safe; continuous nitrogen flow can remove any residual trace amounts of moisture and oxygen in the furnace, and provide a stable atmosphere for the heating process, ensuring temperature uniformity and effectively maintaining the stability of the overall environment.

[0046] S3, silane deposition of silicon At the target temperature, introduce silane gas, which is the core reaction step and needs to be accurately controlled.

[0047] The introduced gas is nitrogen and silane, and the specific gas path and control logic are as follows: S31, nitrogen gas path (protection gas path): the controller keeps the No. 2 pneumatic normally open valve open. The flow path is consistent with S11, serving as a carrier gas and protection gas.

[0048] S32, the controller automatically executes a "vacuum-nitrogen filling" emptying cycle for the silane pipeline once through the silane exhaust path, ensuring safety, Specific method: the controller controls the opening of the second pneumatic normally closed valve and the vacuum generator, and the vacuum generator evacuates the connected pipeline while nitrogen is sequentially discharged through the nitrogen inlet, the first four-way valve, the second pneumatic normally closed valve, the vacuum generator, the third one-way valve and the first flame arrester, so that the gas circuit is filled with nitrogen, achieving the "vacuum-pumping nitrogen" emptying cycle.

[0049] S33, silane gas circuit: the controller controls the opening of the first pneumatic normally open valve and the third pneumatic normally open valve. Silane flows out from the silane gas source and flows through the path: silane gas source → five manual diaphragm valves → three pressure reducing valves → first pneumatic normally open valve → three three-way valves → MFC3 → five three-way valves → third pneumatic normally open valve → second four-way valve → six three-way valves → high-temperature furnace. MFC3 works at the set flow rate.

[0050] S33, core control logic (focus on furnace pressure): S331, normal deposition: the pressure transmitter monitors the furnace pressure in real time. The deposition process continues.

[0051] Process endpoint / primary response (P1): when the furnace pressure reaches the set value P1 (as a signal that needs to be stopped), the controller immediately closes the first pneumatic normally open valve to cut off the silane gas source. At the same time, the first pneumatic normally closed valve is opened, and nitrogen is introduced into the silane gas circuit through the gas distribution to ensure the safety of the pipeline.

[0052] S332, safety interlock / secondary response (P2): if the furnace pressure continues to abnormally rise to a higher safety threshold P2, the controller immediately closes the second pneumatic normally open valve (cutting off the main nitrogen) and the first pneumatic normally closed valve (stopping purging), so that the system is completely isolated to prevent overpressure accidents.

[0053] The total duration of this step is based on reaching pressure P1 or fixed time T3.

[0054] This step uses the furnace pressure as the feedback signal of the deposition process, achieving accurate judgment and control of the deposition endpoint, ensuring product quality and batch consistency. Setting two pressure thresholds P1 and P2 provides gradual safety protection, which can normally end the reaction and effectively respond to abnormal overpressure, achieving multiple safety interlocks. After deposition, the dangerous silane pipeline is automatically purged with nitrogen to avoid the residue of self-igniting gas.

[0055] S4, high-temperature acetylene carbon coating At high temperature, acetylene gas is introduced to crack and form a uniform carbon coating layer on the surface of the deposited nanosilicon, improving the electrical conductivity and structural stability of the material.

[0056] The introduced gas is nitrogen and acetylene, and the specific gas circuit and control logic are as follows: S41, nitrogen gas path: the controller controls the opening of the second pneumatic normally open valve. The flow path is consistent with S11.

[0057] S42, acetylene gas path: the controller controls the opening of the fourth pneumatic normally open valve. The acetylene flow path is the same as S12.

[0058] S43, core control logic (focus on furnace pressure): S431, normal carbon coating: the pressure transmitter monitors the furnace pressure in real time.

[0059] S432, process endpoint / primary response (P11): when the furnace pressure reaches the set value P11, the controller immediately closes the fourth pneumatic normally open valve to cut off the acetylene gas source. At the same time, the fifth pneumatic normally closed valve is opened, and nitrogen is introduced into the acetylene gas path for purging.

[0060] S433, safety interlock / secondary response (P21): if the furnace pressure abnormally rises to the safety threshold P21, the controller immediately closes the second pneumatic normally open valve (cuts off the main nitrogen) and the fifth pneumatic normally closed valve (stops purging), so that the system is completely isolated.

[0061] S434, duration: based on reaching the pressure P11 or a fixed time T4.

[0062] Through this step, a uniform carbon coating layer is formed, effectively buffering the volume expansion of silicon, significantly improving the cycle life of the negative electrode material, and optimizing the material performance; In the same high temperature environment, the silicon deposition and carbon coating are continuously completed, the process flow is compact and efficient, and material pollution is avoided. This step also realizes endpoint control and safety purging for the acetylene pipeline, forming a complete safety control closed loop.

[0063] S5, cooling After the reaction is completed, the furnace body is cooled to a safe temperature under continuous nitrogen protection to prevent high-temperature materials from being oxidized when taken out.

[0064] The gas introduced is only nitrogen, and the specific gas path and control logic are as follows: The controller closes all valves of dangerous gas pipelines (such as the first and third pneumatic normally open valves of the silane path, and the fourth pneumatic normally open valve of the acetylene path), and only keeps the second pneumatic normally open valve open. Nitrogen is continuously introduced at a low flow rate, and the flow path is the same as that in S2.

[0065] Control points: cooperate with the program cooling curve until the furnace temperature drops to the set value.

[0066] Through the cooling of the furnace body, it is ensured that the final product is not oxidized during the cooling process, and the product quality is guaranteed. At the same time, a safety period is drawn for the entire process.

[0067] The whole process does not need manual intervention, and all data are recorded. If an emergency occurs in the process, a one-key emergency stop button can be manually triggered, the system will be safely interrupted, and the subsequent steps can be continued after the button is pressed again by the staff, the control is more flexible, and the humanization is stronger.

[0068] It should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An air intake system for preparing silicon-carbon anode materials by vapor deposition, characterized in that: include The pressure monitoring unit is used to monitor the pressure inside the vapor deposition furnace in real time and transmit it to the control unit. The gas path unit includes a silane gas path, an acetylene gas path, and a nitrogen gas path. The nitrogen gas path comprises an independently configured main protection gas path, an acetylene purging / displacement gas path, a silane purging / displacement gas path, and a silane exhaust gas path. The control unit is connected to all pneumatic valves, mass flow meters, and pressure transmitters in the pneumatic circuit unit to control the switching of each pneumatic circuit.

2. The air intake system for preparing silicon-carbon anode materials by vapor deposition according to claim 1, characterized in that: The control unit includes a controller and a one-button start / stop module. The one-button start / stop module can realize the one-button start / stop function according to the controller's instructions or external instructions.

3. The air intake system for preparing silicon-carbon anode materials by vapor deposition according to claim 2, characterized in that: The acetylene gas circuit includes an acetylene inlet, a No. 1 tee, a No. 2 tee, a No. 2 four-way valve, a No. 6 tee, and a high-temperature furnace, connected sequentially by pipelines. A pressure transmitter is installed on the No. 6 tee, and a No. 2 flame arrester is installed on the other opening of the No. 6 tee. A No. 4 pneumatic normally closed valve is installed on the outside of the No. 2 flame arrester. A No. 4 pneumatic normally open valve is also installed on the pipeline between the acetylene inlet and the No. 1 tee. A No. 1 manual diaphragm valve and a No. 1 pressure reducing valve are also installed on the pipeline between the No. 1 tee and the No. 2 tee. A No. 1 mass flow meter MFC1 is installed on the pipeline between the No. 2 tee and the No. 2 four-way valve. The No. 1 mass flow meter MFC1, the pressure transmitter, and the No. 4 pneumatic normally open valve are all connected to the controller.

4. The air intake system for preparing silicon-carbon anode materials by vapor deposition according to claim 3, characterized in that: The silane gas path includes a silane inlet, a No. 3 tee, a No. 4 tee, a No. 5 tee, a No. 2 4-way valve, a No. 6 tee, and a high-temperature furnace, all connected in sequence by pipelines. The No. 5 tee is also connected to a vacuum generator, and a No. 3 pneumatic normally closed valve is installed on the pipeline between the two. A No. 1 pneumatic normally open valve is also installed on the pipeline between the silane inlet and the No. 3 tee. A No. 5 manual diaphragm valve and a No. 3 pressure reducing valve are also installed on the pipeline between the No. 3 tee and the No. 2 4-way valve. A No. 3 mass flow meter MFC3 is installed on the pipeline between the No. 5 tee and the No. 2 4-way valve. A No. 3 pneumatic normally open valve is installed on the pipeline between the No. 5 tee and the No. 2 4-way valve. The No. 3 mass flow meter MFC3, the No. 3 pneumatic normally open valve, and the No. 5 pneumatic normally open valve are all connected to the controller.

5. The air intake system for preparing silicon-carbon anode materials by vapor deposition according to claim 4, characterized in that: The main protective gas circuit includes a nitrogen inlet, a No. 1 four-way valve, a gas distributor, a No. 2 four-way valve, a No. 6 three-way valve, and a high-temperature furnace, which are connected in sequence by pipelines. The second opening of the No. 1 four-way valve is connected to the nitrogen inlet. A No. 3 manual diaphragm valve and a No. 2 pressure reducing valve are installed on the pipeline between the No. 1 four-way valve and the gas distributor. A No. 2 pneumatic normally open valve and a No. 2 mass flow meter MFC2 are installed on the pipeline between the gas distributor and the No. 2 four-way valve, which are respectively connected to the controller signal.

6. The air intake system for preparing silicon-carbon anode materials by vapor deposition according to claim 5, characterized in that: The pipeline connecting the gas distributor and the No. 2 tee is used to form an acetylene backup branch. A No. 6 pneumatic normally closed valve is installed on the acetylene backup branch. The pipeline connecting the gas distributor and the No. 4 tee is used to form a silane backup branch. A No. 7 pneumatic normally closed valve is installed on the silane backup branch. The No. 6 and No. 7 pneumatic normally closed valves are respectively connected to the controller.

7. The air intake system for preparing silicon-carbon anode materials by vapor deposition according to claim 2, characterized in that: The acetylene purging / displacement gas path includes a nitrogen inlet, a No. 1 four-way valve, a No. 5 pneumatic normally closed valve, a No. 1 check valve, and a No. 1 three-way valve connected in sequence. The No. 5 pneumatic normally closed valve is connected in parallel with a No. 2 manual diaphragm valve as a backup valve. The No. 2 manual diaphragm valve is normally closed by default. The No. 5 pneumatic normally closed valve is connected to the controller.

8. The air intake system for preparing silicon-carbon anode materials by vapor deposition according to claim 2, characterized in that: The silane purging / displacement gas path includes a nitrogen inlet, a No. 1 four-way valve, a No. 1 pneumatic normally closed valve, a No. 2 one-way valve, and a No. 2 three-way valve connected in sequence. The No. 1 pneumatic normally closed valve is also connected in parallel with a No. 4 manual diaphragm valve as a backup valve. The No. 4 manual diaphragm valve is normally closed by default. The No. 1 pneumatic normally closed valve is connected to the controller.

9. An air intake system for preparing silicon-carbon anode materials by vapor deposition according to claim 2, characterized in that: The silane exhaust path includes a nitrogen inlet, a No. 1 four-way valve, a No. 2 pneumatic normally closed valve, a vacuum generator, a No. 3 one-way valve, and a No. 1 flame arrester connected in sequence. The exhaust gas is discharged through the No. 1 flame arrester. The No. 2 pneumatic normally closed valve, the vacuum generator, and the No. 1 flame arrester are respectively connected to the controller. The vacuum generator is also connected to the No. 5 three-way valve, and a No. 3 pneumatic normally closed valve is installed on the pipeline between the two. The No. 3 pneumatic normally closed valve is connected to the controller.

10. A control method for an air intake system for preparing silicon-carbon anode materials by vapor deposition according to any one of claims 1-9, characterized in that: Includes the following steps: S1. At room temperature, purge the furnace body and pipelines with nitrogen to remove air, and simultaneously introduce acetylene to establish a basic inert atmosphere; S2. Increase the temperature based on S1 and continuously introduce nitrogen to maintain positive pressure inside the furnace; S3. At the target temperature, nitrogen gas is first introduced as a carrier gas and protective gas, and then silane gas is introduced to precipitate silicon with silane. When introducing silane, a gradual safety protection is adopted. S4. At high temperature, acetylene gas is introduced to cause it to decompose on the deposited nano-silicon surface to form a uniform carbon coating layer. S5. After the reaction is complete, the furnace body is cooled to a safe temperature under continuous nitrogen protection.

Images