Preparation method of silicon-based negative electrode material

Abstract

The invention discloses a preparation method of a silicon-based negative electrode material, and belongs to the field of battery material preparation. The preparation method of the silicon-based negative electrode material comprises the following steps: uniformly mixing nano silicon particles and a carbon source in an inert gas atmosphere to form a mixture; carrying out heat treatment on the obtained mixture so as to realize coating of the carbon coating on the silicon particles; cooling a product to room temperature in an inert atmosphere after heat treatment to obtain a silicon-carbon composite material; crushing and sieving the cooled silicon-carbon composite material to prepare a negative electrode material in a required particle size range; according to the invention, the problem of poor cycling stability caused by large volume change of the existing silicon-based negative electrode material in the charging and discharging process can be solved.

Description

Technical Field

[0001] This invention relates to the field of battery material preparation technology, and in particular to a method for preparing a silicon-based anode material. Background Technology

[0002] The preparation method of silicon-based anode materials usually involves selecting high-purity silicon sources and other suitable carriers or additives, and forming a new composite material structure through mixing, reaction and other steps under strictly controlled conditions to improve its performance, especially the battery cycle life.

[0003] Currently, existing silicon-based anode materials experience significant volume changes during battery charging and discharging, often exceeding 300%, leading to material structural damage, a substantial reduction in cycle life, abnormal internal stress, and potential safety hazards. Therefore, the silicon-based anode material preparation method proposed in this application mitigates stress accumulation and particle breakage caused by volume expansion through doping and surface coating, significantly enhancing the material's structural integrity and stability, and ensuring a longer battery life. Summary of the Invention

[0004] The purpose of this invention is to solve the problems existing in the prior art and to propose a method for preparing silicon-based anode materials.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a silicon-based anode material includes the following steps: S101. Mix the nano-silicon particles and the carbon source evenly in an inert gas atmosphere to form a mixture; S102. The mixture obtained above is subjected to heat treatment to achieve carbon coating on silicon particles; S103. After heat treatment, the product is cooled to room temperature under an inert atmosphere to obtain a silicon-carbon composite material. S104. The cooled silicon-carbon composite material is crushed and sieved to prepare anode materials with the required particle size range.

[0006] Preferably, in step S102, the specific operation of heat treatment of the mixture is as follows: S201. Place the mixture containing nano-silicon particles and carbon source into the reactor, and keep the temperature inside the reactor within the preset temperature range. S202. Control the reaction temperature inside the reactor to be higher than the first set threshold and keep it at that temperature for a duration of the first time period. S203. Control the reaction temperature to drop below the second set threshold and keep it at that temperature to cure the carbon coating. The holding time is the second time period. S204. Allow the mixture to heat up naturally and stabilize under an inert gas atmosphere.

[0007] Furthermore, the specific operation of step S202 is as follows: S301. Detect the actual heating temperature inside the reactor. ; S302, if the actual heating temperature Equal to or higher than the predefined maximum target reaction temperature Then the temperature control program will be activated; in, ; S303. Start the heat preservation countdown timer, and wait until the specified heat preservation time is reached. Previously maintained the highest target reaction temperature The heating process; in, , This indicates the preset total insulation time; S304. After the heat preservation time is over, reduce the power supply and gradually cool down.

[0008] Further, in step S301, the actual heating temperature inside the reactor is detected. The operation is as follows: S401. Continuously measure the temperature change inside the reactor using thermocouples and record it as the current temperature. ; S402. Continuously measure and record until detected. If so, then perform the heat preservation operation; in, Indicates the temperature control tolerance value; S403, when Immediately implement cooling measures to keep the temperature below [a certain level]. ; in This indicates the maximum temperature difference control threshold, ensuring... Always ; S404. Maintain the temperature within the set range until the preset total holding time is reached. The process ends, and heating is immediately stopped.

[0009] Furthermore, the specific operation of step S404 is as follows: S501, if If the temperature is high, continue the heat preservation operation; otherwise, proceed with the cooling process. S502, Ensure that during the insulation period... ; in, This indicates the set lower limit of temperature difference tolerance; S503, real-time monitoring and power adjustment based on current temperature to ensure ; S504. After the insulation period is completed, gradually adjust the equipment temperature down to the predetermined level and begin natural cooling.

[0010] Preferably, in step S104, the specific operation process of crushing and sieving the cooled silicon-carbon composite material is as follows: S601. Place the cooled silicon-carbon composite material into a crushing device and crush it; S602. The crushed product is screened and classified to ensure that the particle size of the obtained product is within the pre-designed range. If the particle size exceeds the set standard, the crushing operation is returned. S603. Place the product particles that meet the standard into a drying device to remove any residual moisture. S604. Store and package the finished products that have undergone the above processing and meet all size requirements for further use or direct shipment. In step S102, the specific operation of heat treating the mixture further includes: S701, Set the heating temperature range from 500 degrees Celsius to 1000 degrees Celsius; S702. Place the above mixture into a tube furnace and keep it at a set temperature for a certain period of time, specifically 1 to 4 hours. S703. If the temperature during the heating process is below 500 degrees Celsius or above 1000 degrees Celsius, the temperature within the range shall be reset and the heat treatment shall be restarted. S704. After being kept at a certain temperature for a certain period of time, allow it to cool naturally or with nitrogen to a temperature of 600 degrees Celsius or below, and continue with subsequent cooling steps until it reaches room temperature.

[0011] Furthermore, it also includes a method for measuring the degree of uniformity of mixing in step S101, specifically: S801. If the detected mixing uniformity is lower than the set standard, increase the heating start temperature and reduce the heat preservation time to improve the wrapping uniformity. Among them, the heating start temperature is at least higher than the minimum value. 1, and 50℃≤ 1≤200℃; S802. If the mixing uniformity meets or exceeds the set standard, maintain the standard heat treatment temperature and extend the holding time. 2. To ensure adequate coverage; Among them, 5h≤ 2≤3.5h; S803. If the carbon layer thickness of the final product is greater than 0.5 nanometers, it is judged that the heat treatment effect is better than expected; otherwise, fine-tuning is made according to the insufficient thickness. S804. Set a thickness difference E. If the thickness difference E is less than 0 nanometers or greater than 0.1 nanometers, adjust the heat treatment conditions and repeat the heat treatment steps until the requirements in step S803 are met. Wherein, the thickness difference E = target minimum thickness - actual thickness.

[0012] Furthermore, when the thickness difference of the carbon layer E < 0 or E > 0.1 nm, the control and correction of the temperature change caused by the adjustment of the heat treatment temperature during the process of adjusting the heat treatment conditions are further limited as follows: S901. If the temperature change value does not conform to the range during the adjustment process, the actual temperature setting shall be corrected according to the mixing state, i.e., the temperature correction amount. 3 = (Target mixing uniformity - Measured mixing uniformity) × 1% × Temperature increment coefficient α; Where α is an adjustment value ranging from 1 to 0.9; S902, if calculated based on the measured mixing state 1. Error corresponding to the theoretical value of the mixed state with the set standard 1. Adjust the correction amount for the heating start temperature based on the measured deviation value E of the actual carbon layer thickness: 3 Correction = (0.5 nm - actual thickness) / 10 × 1% × heating start temperature; Among them, 50℃≤ 1≤150℃; S903. If the actual carbon coating thickness is less than 0.1 nanometers below the standard thickness or the carbon coating thickness increase rate is too slow, i.e. If 2 < 1 hour, then extend the heat preservation time to 2 + (50nm / μm heat treatment process thickness increase rate) / reciprocal of thickness increase per minute; S904. The maximum rate of natural cooling after heat preservation is limited to v (℃ / min), and v satisfies: 35℃ / min < v < 50℃ / min.

[0013] Furthermore, in step S904, the method of natural cooling after heat preservation is as follows: S1001. If the temperature does not drop by 500°C within 3 hours after heat preservation, it is determined to be poor cooling. Increase the nitrogen pressure by 5 psi to accelerate the cooling. S1002. If the temperature does not reach the standard cooling range of 600℃ after the maximum heat preservation time has been reached, further check whether there is a fault in the cooling equipment and carry out corresponding equipment maintenance. S1003. Before the final product is cooled to room temperature, this process must not be terminated until one of the following is resolved: the cooling process is uninterrupted, nitrogen protection is uninterrupted during the cooling process, and no cracks or agglomeration of particles appear after cooling. S1004. The range of temperature change fluctuation V during the cooling process is 1℃≤V≤5℃. If it exceeds this range, the temperature change shall be kept within the normal range by controlling the cooling environment conditions.

[0014] Furthermore, the specific requirements for crushing the silicon-carbon composite material finally obtained in step S104 include: S1101. After measuring the hardness H of the silicon-carbon composite material sample, select a suitable crushing method. When H is below 35HBW (10kgf / mm²), [further details are needed]. 2 When processing, use a gentler grinder; S1102. In silicon-carbon composite material samples, if the proportion of particles with a diameter greater than 20 μm above the target range exceeds 2% of the total mass, fine crushing methods should be used to reprocess them to meet the standard. S1103. Comprehensively evaluate crushing efficiency and final product performance to ensure that the average size d of crushed particles remains 1μm < d < 20μm in order to achieve ideal electrochemical performance.

[0015] Compared with the prior art, the present invention provides a method for preparing silicon-based anode materials, which has the following beneficial effects: The parts of this device not described herein are the same as or can be implemented using existing technologies. In use, nano-silicon particles and a carbon source are uniformly mixed in an inert gas atmosphere; the mixture is then heat-treated to achieve a carbon coating over the silicon particles; after heat treatment, the product is cooled to room temperature in an inert atmosphere; the cooled silicon-carbon composite material is crushed and sieved to prepare anode materials with the desired particle size range. The solution provided by this disclosure addresses the problem of poor cycle stability caused by large volume changes during charge and discharge of existing silicon-based anode materials. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a method for preparing a silicon-based anode material proposed in this invention; Figure 2 This is a flowchart illustrating the heat treatment process of a mixture in a method for preparing a silicon-based anode material proposed in this invention. Figure 3 This is a flowchart of the steps in the preparation method of a silicon-based anode material proposed in this invention, which involves controlling the reaction temperature in the reactor to be higher than a first set threshold and continuously maintaining the temperature. Figure 4This is a flowchart illustrating the detection of the actual heating temperature inside the reactor in a method for preparing a silicon-based anode material proposed in this invention. Figure 5 This is a flowchart of the steps in a method for preparing a silicon-based anode material proposed in this invention, which involves maintaining a temperature within a set range until the predetermined total holding time is reached. Figure 6 This is a flowchart illustrating the crushing and sieving process of cooled silicon-carbon composite material in a method for preparing a silicon-based anode material proposed in this invention. Figure 7 This is a flowchart illustrating the heat treatment process of a mixture in a method for preparing a silicon-based anode material proposed in this invention. Figure 8 This is a flowchart illustrating the determination of the mixing uniformity of a mixture in a method for preparing a silicon-based anode material according to the present invention. Figure 9 This is a flowchart further defining the control and correction calculation of temperature changes caused by adjusting the heat treatment temperature in a method for preparing a silicon-based anode material proposed in this invention. Figure 10 This is a flowchart illustrating the natural cooling process after heat preservation in a method for preparing a silicon-based anode material proposed in this invention. Figure 11 This is a flowchart illustrating the crushing requirements of the silicon-carbon composite material ultimately obtained in the preparation method of a silicon-based anode material proposed in this invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] Reference Figure 1 A method for preparing a silicon-based anode material includes the following steps: S101. Mix the nano-silicon particles and the carbon source evenly in an inert gas atmosphere to form a mixture; Specifically, by precisely weighing nano-silicon particles and a suitable proportion of carbon source material, and adding them to a dedicated reaction vessel under strict control, various mixing methods are used to fully and uniformly disperse the silicon particles and carbon source material in an inert gas environment, ensuring that each particle has the opportunity to come into contact with other components of the surrounding environment.

[0020] In this process, nitrogen or argon is used as the inert gas, and ball milling is employed for mixing. To achieve a finer and more uniform mixture, intermittent vibratory ball milling can be used. This mixing technique, by continuously adjusting the speed and interval, effectively reduces agglomeration, improves the uniformity of active material distribution, enhances the consistency of the mixture, and reduces the probability of introducing potential impurities, ultimately obtaining a uniformly dispersed silicon-carbon precursor mixture. In practical applications, when using nanoscale silicon powder as the main material, the carbon source can be common amorphous carbon such as acetylene black. At the same time, by setting a specific temperature of 500°C and a rotation speed of 50-300 rpm, and combining factors such as the ball-to-material ratio, these components are mixed for 3-16 hours to obtain a mixture.

[0021] S102. The mixture obtained above is subjected to heat treatment to achieve carbon coating on silicon particles; S103. After heat treatment, the product is cooled to room temperature under an inert atmosphere to obtain a silicon-carbon composite material. S104. The cooled silicon-carbon composite material is crushed and sieved to prepare anode materials with the required particle size range. Specifically, the ideal silicon-carbon mixture obtained through step S101 is further heated to transform into a solid structure, and a dense carbon coating layer with controllable thickness is formed on its surface using high-temperature treatment technology to enhance charge transfer capability and overall stability. This step mainly includes the following key operational points: a. After the transfer is loaded into the reactor, the heating rate is gradually increased under an inert gas covering environment until the specified target process window is reached. At this time, the temperature control range is between 900 and 1100 degrees Celsius. During this period, it is necessary to ensure that the temperature fluctuation does not exceed ±5%. b. During this process, the carbon source will decompose to generate free carbon particles, which will gradually grow outwards and surround the internal silicon core to form a protective film with good continuity as heating continues. It is worth noting that the duration of this stage should be well controlled to avoid problems such as the formation of by-products and damage to the crystal structure due to overheating. Under normal circumstances, it is ideal to maintain a constant temperature for 8-24 hours. During this period, the chemical potential of carbon atoms can drive them to diffuse towards the silicon matrix interface and deposit on the outer surface of silicon particles through chemical deposition to form a continuous graphite phase. c. As the temperature gradually decreases, silicon particles with a higher carbon content will be obtained, which helps to improve conductivity, reduce the volume expansion of the active layer, increase the negative maximum capacity, and extend the overall device life. It should be noted that the cooling process should be slow cooling in an inert atmosphere rather than rapid cooling, so that the final product has a better crystallization state, reduces residual impurities, and ensures overall quality.

[0022] Through the synergistic effect of the above steps, the dual objectives of improving the cycle stability of silicon-based anodes during charge and discharge and reducing volume change can be achieved. The carbon shell can effectively isolate the physical contact between electroactive materials and solvent molecules, thereby inhibiting dissolution. It can also serve as a mechanical buffer layer to mitigate internal strain reactions in the electrode, thus significantly enhancing the mechanical strength of the system and extending its service life. On the other hand, it also enhances the electron transport network structure, enabling the battery to maintain high energy output even at high current rates. Therefore, in practical applications, this preparation route not only meets the current high-performance development requirements of lithium-ion systems but also further explores the inherent advantages of the materials, promoting the evolution of advanced battery system design to a higher level.

[0023] Reference Figure 1 and Figure 2 The specific steps for heat treatment of the mixture are as follows: S201. Place the mixture containing nano-silicon particles and carbon source into the reactor, and keep the temperature inside the reactor within the preset temperature range. Specifically, a mixture containing nano-silicon particles and a carbon source, which has been uniformly mixed beforehand, is placed in a suitable high-temperature reactor, and then the reactor is placed inside a temperature-controlled device, such as a furnace or pyrolysis furnace. This placement ensures that the mixture can undergo subsequent processes under controlled conditions. At this time, the temperature device is set in a predetermined preset temperature range, which usually needs to be precisely set to meet specific reaction conditions. A suitable operating temperature can be selected within the range of 900°C to 1100°C.

[0024] S202. Control the reaction temperature inside the reactor to be higher than the first set threshold and keep it at that temperature for a duration of the first time period. Specifically, once the internal environment of the furnace containing the mixture has reached the preset maximum heating temperature, which is greater than the first set threshold, the system begins to maintain a specific heat preservation phase at this constant temperature point. During this first time period, the nano-silicon particles and the surrounding carbon source will undergo chemical interaction due to heat. The goal of this phase is usually to achieve effective encapsulation of carbon materials and form a preliminary stable carbon-silicon composite structure. For example, if the first time period is set to be two hours, the furnace temperature must be kept constant during these two hours so that the nano-silicon and carbon source can fully carry out the required chemical reaction. S203. Control the reaction temperature to drop below the second set threshold and keep it at that temperature to cure the carbon coating. The holding time is the second time period. Specifically, after the above reaction, the temperature is gradually reduced in a stable manner through appropriate temperature control measures, such as turning off the furnace heating elements, until it drops to another pre-set temperature threshold, i.e., less than the second set threshold. During this period, a specified time span must also be maintained, such as holding the temperature for half an hour, so that the carbon coating can be further cured and perfected under low temperature conditions. This step is to promote a more uniform density and structural integrity of the carbon coating on the material surface. In order to ensure that this process is not affected by the oxidizing atmosphere in the outside air, which may lead to product deterioration, the furnace environment must be kept in an oxygen-free state filled with protective gas throughout the heat treatment process. Common inert gases include nitrogen (N2) and argon (Ar).

[0025] S204. Allow the mixture to heat up naturally and stabilize under an inert gas atmosphere; Once the mixture cools to the required low temperature threshold, such as below the second set threshold and is maintained in an inert atmosphere for the appropriate time, the equipment can then be gradually heated up to a stable state with the environment. That is, instead of artificially forcibly cooling it rapidly, the system is allowed to slowly rise back to normal room temperature or a slightly higher stable operating temperature. This natural cooling and warming process helps the finally synthesized silicon-based anode material to have better crystal quality and microstructure, thereby effectively ensuring the electrochemical performance indicators of the final product.

[0026] The above detailed steps enable a relatively complete implementation of the heat treatment process described above, laying the technological foundation for obtaining a novel silicon-based anode material with high performance characteristics suitable for various lithium-ion battery application environments.

[0027] Reference Figure 3 In step S202 above, the step of controlling the reaction temperature inside the reactor to be higher than a first set threshold and continuously maintaining the temperature for a first time period specifically includes: S301. Detect the actual heating temperature inside the reactor. ; This step first involves monitoring the actual temperature during the heating process within the specific reactor. This operation ensures the accuracy of temperature control. Real-time data is acquired through a built-in temperature sensor and fed back to the control system in real time. If the monitored temperature value has reached or exceeded the target maximum value determined by previous experiments, the system will take action. If the temperature is in Celsius, proceed to the next step immediately to avoid the adverse effects of excessive temperature, that is, ensure that the reaction does not exceed the ideal temperature range in order to maintain the precise temperature control required in the synthesis process; S302, if the actual heating temperature Equal to or higher than the predefined maximum target reaction temperature Then the temperature control program will be started, in which... ; S303. Start the heat preservation countdown timer, and wait until the specified heat preservation time is reached. Previously maintained the highest target reaction temperature The heating process; in, , This indicates the preset total insulation time; S304. After the heat preservation time is over, reduce the power supply and gradually cool down; After step S301 is completed, once it is determined that the current temperature meets the condition of being greater than or equal to the target maximum value... This will automatically start or manually activate the specially designed temperature control program in the heat preservation mode. This stage mainly aims to maintain the system's reaction environment at a constant temperature under the predetermined maximum temperature condition. At the same time, a countdown timer is started to keep track of the time during this heat preservation period. Maintaining a stable internal temperature helps ensure that the components in the raw materials can complete their respective physical or chemical reaction processes in an ideal environment. During this period, it is necessary to ensure that the temperature control system can make appropriate adjustments according to the actual situation, and the total holding time... It is carefully calculated and optimized to meet the performance requirements and production efficiency requirements of specific silicon-based materials.

[0028] After the heat preservation is completed, that is, after the countdown ends, the power supplied by the heating power supply needs to be gradually reduced to start the natural or forced cooling mechanism. This cooling step is to ensure that the final product can be safely and effectively cooled down within an appropriate time for the next processing or packaging process. The way to reduce the heating power may include adjusting the preset power level in the controller or switching to a state that can achieve slow and uniform cooling, thereby reducing potential structural changes or stress accumulation caused by rapid temperature changes, and thus improving the overall quality consistency and reliability of the negative electrode material. Throughout the process from constant heat preservation to gradual cooling, strict temperature and pressure monitoring is required to ensure the continuity and stability of each batch of production.

[0029] Reference Figure 4 Detect the actual heating temperature inside the reactor. The operation is as follows: S401. Continuously measure the temperature change inside the reactor using thermocouples and record it as the current temperature. ; S402. Continuously measure and record until detected. If the condition is such that the insulation operation is performed, then the insulation operation will be carried out; among them, Indicates the temperature control tolerance value; S403, when Immediately implement cooling measures to keep the temperature below [a certain level]. ;in This indicates the maximum temperature difference control threshold, ensuring... Always ; S404. Maintain the temperature within the set range until the preset total holding time is reached. End, then immediately stop heating and heating. This step involves using thermocouples to monitor the heating process to ensure that the preset optimal operating temperature is reached; the step includes: activating the thermocouples embedded inside the reactor for continuous monitoring and recording the actual temperature change; this data point is identified as the current temperature. This will serve as a basis for subsequent temperature adjustments.

[0030] As the heating phase progresses, continue to monitor and record the real-time temperature within the reaction chamber; when the observed temperature... Value equal to or exceeding the target temperature Including the temperature control tolerance \\delta, which represents the constant temperature maintenance operation, this value defines the standard for entering the heat preservation program; among which, It refers to the optimal temperature for the reaction under specific conditions; \\delta\ indicates the permissible difference between the actual operation and the predetermined target.

[0031] Temperature monitoring display > In cases involving +delta, prompt intervention is necessary to prevent the actual temperature from exceeding [a certain threshold]. Adding the temperature difference threshold \\DeltaT\, where \\DeltaT\ is the maximum control point for the temperature difference set as a safety margin; timely adjustments to the treatment plan can ensure safety throughout the entire reaction period. The always lower than equal +\DeltaT\.

[0032] When the predetermined target constant temperature is reached If the temperature remains unchanged, continue this step until the specified constant temperature time period is completed; then end the heating and holding process, and proceed to the next step.

[0033] This feature can be achieved by using advanced temperature control devices with precise temperature sensing capabilities, such as high-precision thermocouples integrated into a high-temperature sealing environment and PID temperature regulation circuits; the thermocouple is connected to the controller, which automatically adjusts the energy supply to the heater based on the feedback signal from the thermocouple; for example, if the temperature needs to reach 900°C, the setting... =900℃, the temperature tolerance value \\delta\ is usually less than 5℃ for strict temperature control, and the maximum temperature deviation threshold \\DeltaT=10℃ is set; once the real-time measured temperature approaches or even slightly exceeds this upper limit, assuming the actual measured temperature is 910℃, If the temperature exceeds 905℃, the system will reduce or shut down the heating input to lower the overall temperature inside the furnace and bring it back to a safe range, such as returning to around 910℃ until the time requirement for constant temperature is met. This ensures the accuracy of the heat input required for the reaction and avoids the risk of equipment or products being damaged by overheating.

[0034] The above process ensures that the required high precision and consistency are maintained throughout the manufacturing process, which helps to ensure that the performance and quality of the final silicon-based lithium-ion battery anode products meet design requirements and industry standards, while reducing the defect rate caused by the production process.

[0035] Reference Figure 5 In step S404, the temperature is maintained within the set temperature range until the preset total holding time is reached. The final steps are as follows: S501, if If the temperature is high, continue the heat preservation operation; otherwise, proceed with the cooling process. S502, Ensure that during the insulation period... ; in, This indicates the set lower limit of temperature difference tolerance; S503, real-time monitoring and power adjustment based on current temperature to ensure ; S504. After the insulation period is completed, gradually adjust the equipment temperature down to the predetermined level and begin natural cooling.

[0036] Specifically, the temperature within the heating zone is maintained by controlling the temperature holding device of the heat treatment system, if the current holding time has been completed... Less than the specified total insulation time If the system continues to maintain the desired set temperature range, it will continuously monitor the power regulation mechanism and built-in feedback control system of the heating device to monitor environmental conditions, especially the current actual operating temperature, in real time. And automatically adjust as needed to avoid temperature deviations, thus ensuring The insulation temperature should never be lower than the specified maximum. Temperature difference tolerance range The difference.

[0037] When the actual operating temperature inside the heating system is monitored Approaching but not exceeding the predefined upper limit, i.e., less than + In this case, the adjustment of heating power will be more sensitive and precise to prevent exceeding the target maximum heat preservation temperature; such a control strategy ensures precise control of the working temperature throughout the heating and heat preservation stage, and meets the requirements of the temperature change range throughout the entire heating cycle, while maintaining high stability of the heating environment while achieving the specified total heat preservation time. Once the time in S501 meets the total heat preservation time requirement, proceed to the next step, which is to gradually reduce the power supply of the heating unit until it is completely shut down, and use the inert gas-assisted cooling system to slowly lower the temperature until the pre-set cooling target is reached. After that, the system safety door can be opened to allow the material to cool down naturally at room temperature to complete the overall process. The entire cooling process should be designed to be predictable and controllable to ensure the quality and safety performance of the product under various parameter conditions during the manufacturing process.

[0038] These steps ensure that the structural integrity and electrochemical performance of the material are optimized through precise process management throughout the entire heat treatment process, including heating, holding, and subsequent cooling.

[0039] Reference Figure 6 In step S104, the specific operation process for crushing and sieving the cooled silicon-carbon composite material, that is, the specific operation process for processing the cooled silicon-carbon composite material, is as follows: S601. Place the cooled silicon-carbon composite material into a crushing device and crush it; S602. The crushed product is screened and classified to ensure that the particle size of the obtained product is within the pre-designed range. If the particle size exceeds the set standard, the crushing operation is returned. S603. Place the product particles that meet the standard into a drying device to remove any residual moisture. S604. Store and package the finished products that have undergone the above processing and meet all size requirements for further use or direct shipment.

[0040] Primary crushing is carried out by feeding heat-treated and naturally cooled silicon-carbon composite particles into a crusher. At this stage, a crusher with appropriate mechanical strength that does not introduce any additional chemical components, such as a jaw crusher or hammer crusher, should be selected. The silicon-carbon composite material reduces its block size through physical crushing. This step ensures that the material can enter the next operation step uniformly and efficiently, and reduces potential risks in subsequent processing.

[0041] The crushed products are graded using a screen or vibrating screen. To obtain a consistent final product and meet the required particle size specifications, this method employs screening technology to remove excessively large or small particles generated during the crushing process, ensuring that the size range of each finished product falls within a pre-set specified value. , here The actual particle size of any single crushed product; if there are products that do not meet the specifications, they should be returned to the crushing step for further size optimization; while those material particles within the preset size range can be directly retained for further processing.

[0042] After collecting silicon-carbon anode materials that meet the specifications and have undergone the above screening and grading process, they are sent to a dehydration and drying device to remove excess water molecules, ensuring that they are free of moisture. Selecting appropriate drying equipment (such as a hot air drying oven) and controlling the drying conditions can prevent residual moisture (or incomplete evaporation) from damaging the performance during subsequent battery assembly. It can also effectively improve the product's storage stability and transportation safety. All products that have completed this process must meet the predetermined testing parameters before they can proceed to the next stage for packaging and storage or be immediately delivered to the downstream supply chain for integrated processing and manufacturing.

[0043] Reference Figure 7 In step S102, the specific operation of heat treating the mixture further includes: S701, Set the heating temperature range from 500 degrees Celsius to 1000 degrees Celsius; S702. Place the above mixture into a tube furnace and keep it at a set temperature for a certain period of time, specifically 1 to 4 hours. S703. If the temperature during the heating process is below 500 degrees Celsius or above 1000 degrees Celsius, the temperature within the range shall be reset and the heat treatment shall be restarted. S704. After being kept at a certain temperature for a certain period of time, allow it to cool naturally or with nitrogen to a temperature of 600 degrees Celsius or below, and continue with subsequent cooling steps until it reaches room temperature.

[0044] By controlling the heat treatment process conditions and completing the heat treatment of the mixture within a specific heating range, a uniform and dense coating layer of carbon on silicon-based particles is promoted. The heating temperature is strictly limited to the range of 500°C to 1000°C. This is because within this range, the carbon source and dopants can form a coating layer on the surface of silicon particles more efficiently without pyrolysis or volatilization. If the temperature does not meet the requirements during the heating process, it needs to be reset to ensure that the heat treatment temperature falls within the specified range.

[0045] Then, to further ensure the heat treatment effect, after reaching the target set heating value, the tube furnace loaded with the material to be treated is maintained at the specified temperature for at least 1 to 4 hours to ensure heat diffusion and uniform coating formation. This step helps to improve the mechanical stability and charge-discharge performance of the negative electrode material. The material quality is guaranteed by precise temperature regulation and time control, and the repeatability of the entire process is improved.

[0046] After maintaining the required temperature range for a sufficient period of time, the system should be gradually restored to room temperature. This can be done in two ways: one is to allow natural cooling to approximately 600°C and then continue to allow natural cooling to ambient temperature; the other is to use an inert gas, such as nitrogen, to blow into the equipment to accelerate the temperature drop to this range and then allow it to cool naturally to room temperature. Both of these cooling methods can avoid the adverse effects of rapid material cooling and ensure the quality and stability of the resulting product.

[0047] Reference Figure 8 The method for determining the mixing uniformity of the mixture in step S101 is as follows: First, the uniformity of the mixed ingredients is measured in the initial stage. If the measurement results show that the uniformity of the mixture does not meet the predetermined technical standard, the heat treatment parameters need to be reset before proceeding to the next step. The initial heating temperature should be increased and the holding time reduced to improve the coating uniformity. The initial heating temperature should be at least higher than the minimum value. 1, and 50℃≤ 1≤200℃, and at the same time reduce the subsequent heat preservation time to increase the probability of uniform bonding between the active material and the conductive medium.

[0048] If the uniformity of the mixed raw materials reaches or exceeds the specified limit, heat treatment should be carried out according to the original plan without changing the initial temperature. However, to ensure a more stable carbon coating effect, the holding time should be extended. 2, of which 5 hours ≤ 2 ≤ 3.5 hours, to enhance the bonding between materials and improve the overall performance of the product.

[0049] Microstructural analysis is performed on the products after the heat treatment process to detect the actual thickness of the thin film formed on the outer surface of the carbon material particles. If the actual value exceeds the standard range, the entire heat treatment process is deemed to have defects. In particular, if the film thickness is too large and the measured data exceeds 0.5 nanometers, it means that the carbon coating degree exceeds the standard and the process needs to be further adjusted. A thickness difference E is set. Conversely, if the film is too thin, the thickness difference E will have a positive deviation point. If E > 0.1 nanometers, the relevant heat treatment parameters, including the peak heating temperature and the residence time, should also be considered for modification. For the above situations, repeated experiments and comparisons are used to gradually approach the ideal state, so as to achieve the core goal of developing composite electrochemical negative extreme materials that ensures that the active raw materials are not lost and maintains better rate performance.

[0050] Reference Figure 9 If the thickness difference of the carbon layer E < 0 or E > 0.1 nm, during the adjustment of heat treatment conditions, the control and correction of temperature changes caused by the adjustment of heat treatment temperature are further limited as follows: S901. If the temperature change value does not conform to the range during the adjustment process, the actual temperature setting shall be corrected according to the mixing state, i.e., the temperature correction amount. 3 = (Target mixing uniformity - Measured mixing uniformity) × 1% × Temperature increment coefficient α; Where α is an adjustment value ranging from 1 to 0.9; S902, if calculated based on the measured mixing state 1. Error corresponding to the theoretical value of the mixed state with the set standard 1. Adjust the correction amount for the heating start temperature based on the measured deviation value E of the actual carbon layer thickness: 3 Correction = (0.5 nm - actual thickness) / 10 × 1% × heating start temperature; Among them, 50℃≤ 1≤150℃; S903. If the actual carbon coating thickness is less than 0.1 nanometers below the standard thickness or the carbon coating thickness increase rate is too slow, i.e. If 2 < 1 hour, then extend the heat preservation time to 2 + (50nm / μm heat treatment process thickness increase rate) / reciprocal of thickness increase per minute; S904. The maximum rate of natural cooling after heat preservation is limited to v (℃ / min), and v satisfies: 35℃ / min < v < 50℃ / min.

[0051] Specifically, during the dynamic control phase of the heat treatment process, if the measured actual heating temperature T deviates from the preset ideal operating range (set to vary between 200°C below and 200°C above the target temperature), then the current heating temperature control system parameters need to be adjusted based on the state of the mixed reactants. The specific temperature T adjustment formula is defined as follows: Dms×1%× ,in Dms represents the measured target mixing uniformity, while Dms represents the theoretically calculated target value for target mixing uniformity. This is the adjustment coefficient for temperature control behavior. The value of this adjustment coefficient ranges from 1.0 to 0.9. The setting of this adjustment coefficient can be flexibly changed according to the specific application scenario to better match the target setting and experimental requirements.

[0052] Continue to dynamically adjust the control process, based on the temperature difference calculated under the measured mixed conditions. When the error between the theoretical set temperature and the expected ideal mixing condition is between 50°C and 150°C, this is defined as follows: This refers to the temperature variation within the temperature range, which is equal to the theoretical temperature value minus the actual measured temperature value. The initial heating set temperature is further adjusted based on the actual coating thickness deviation E of the actual carbon layer. Its expression can be calculated using E=dC-t, where dC is the ideal carbon coating thickness under the expected standard, set in nanometers, and t is the actual measured thickness obtained during the experiment. Temperature correction is performed based on this, and the mathematical relationship is expressed as: ×1%× This ensures that the physicochemical properties and final performance of the material meet the established technical specifications.

[0053] If the actual size of the coating is found to be significantly lower than the expected standard thickness of the carbon coating by 0.1 nanometers, or if the coating formation rate during heat treatment is found to be lower than the standard value of 1 hour, then the heat preservation period in the heat cycle is extended. The heat preservation time is extended far beyond the original predetermined heat preservation time. The additional extension is equal to the time interval required to increase the coating thickness to 50 nanometers divided by the number of nanometers added per second, measured in min / µm. This method of extension calculation ensures that the coating can form the ideal structure and performance characteristics that meet the design expectations. When the heat preservation ends and the product transitions to the self-cooling stage, in order to ensure the consistency and stability of product performance, the cooling rate must be controlled within the allowable range of variation. That is, the maximum natural cooling rate should be set to no higher than 50℃ / min and ensured to be no lower than 35℃ / min. This rate-limiting process can be precisely controlled by controlling the surrounding gas flow rate, ambient temperature, etc. Such control logic also follows the temperature curve optimization design principle and heat treatment quality control criteria.

[0054] The aforementioned dynamic temperature control adjustment strategy effectively ensures that the silicon-based anode material has an ideal microstructure and good cycle electrical performance. It reduces the occurrence of defective products while improving the consistency of finished products, and significantly reduces the difficulty of process operation, thus achieving the dual goals of intelligent operation of thermal control equipment and reliable improvement of product quality.

[0055] Reference Figure 10 The method of natural cooling after heat preservation is as follows: S1001. If the temperature does not drop by 500°C within 3 hours after heat preservation, it is determined to be poor cooling. Increase the nitrogen pressure by 5 psi to accelerate the cooling. S1002. If the temperature does not reach the standard cooling range of 600℃ after the maximum heat preservation time has been reached, further check whether there is a fault in the cooling equipment and carry out corresponding equipment maintenance. S1003. Before the final product is cooled to room temperature, this process must not be terminated until one of the following is resolved: the cooling process is uninterrupted, nitrogen protection is uninterrupted during the cooling process, and no cracks or agglomeration of particles appear after cooling. S1004. The range of temperature change fluctuation V during the cooling process is 1℃≤V≤5℃. If it exceeds this range, the temperature change shall be kept within the normal range by controlling the cooling environment conditions.

[0056] Specifically, if the temperature fails to drop by at least 500°C within 3 hours after the material has been insulated, it can be identified as an abnormal cooling situation. To correct this problem and ensure that the reactants quickly drop to a suitable safe operating temperature range, the nitrogen delivery pressure is increased. Typically, the nitrogen pressure in the system is increased by 5 psi to promote the cooling effect. The implementation of this pressure increase requires adjusting the nitrogen flow control system according to the parameters designed for the reaction device. If the material has completed its maximum insulation period, but the actual temperature of the material still exceeds the predetermined cooling standard range of 600°C, a comprehensive inspection should be conducted to check whether there are any problems with the method used in this stage. This includes, but is not limited to, the nitrogen delivery efficiency, the heat dissipation system, and other issues that may lead to insufficient heat reduction. Based on the corresponding tests and analyses, repair and improvement measures should be taken to ensure the normal progress of the reaction process. These diagnostic steps can be completed by monitoring the nitrogen flow rate in real time and recording the deviation between the actual temperature trend curve of the material and the preset standard value. Furthermore, the entire cooling process described above is closely monitored to ensure that the reactor temperature can be continuously reduced to room temperature. During this stage, it is necessary to maintain an uninterrupted cooling process and ensure a continuous supply of nitrogen to prevent outside air from seeping in and contaminating the finished product or causing dangerous accidents. By observing and recording the particle size, shape, and aggregation of the material during cooling, if obvious material structure damage or adhesion occurs, the operation that caused the problem should be immediately identified and corrected, such as adjusting the nitrogen inlet pressure or rate. In addition, the constant temperature conditions in the laboratory where the reactor is located during the entire process need to be monitored, and measures should be taken to regulate the temperature when it exceeds the standard set temperature variation range V, i.e., when the change value exceeds 1°C but does not exceed 5°C. Specifically, the environment can be kept constant and dry by changing the settings and adjustment of the air conditioning and ventilation system. These actions include starting or increasing the working intensity of the cooling fan, increasing the air flow rate, and adjusting the threshold setting value of the laboratory temperature control system, etc.

[0057] Reference Figure 11 The specific requirements for crushing the silicon-carbon composite material finally obtained in step S104 include: S1101. After measuring the hardness H of the silicon-carbon composite material sample, select a suitable crushing method. When H is below 35HBW (10kgf / mm²), [further details are needed]. 2 When processing, use a gentler grinder; S1102. In silicon-carbon composite material samples, if the proportion of particles with a diameter greater than 20 μm above the target range exceeds 2% of the total mass, fine crushing methods should be used to reprocess them to meet the standard. S1103. Comprehensively evaluate crushing efficiency and final product performance to ensure that the average size d of the crushed particles remains 1μm < d < 20μm, in order to achieve ideal electrochemical performance. To ensure the desired technical performance of the obtained silicon-carbon composite material, its initial properties, particularly its hardness value H, need to be determined first. This value should be measured using appropriate testing methods before crushing. If the measured hardness H of the sample is lower than the standard 35 HBW, it is equivalent to 10 kgf / mm². 2 If the sample is relatively soft, then a gentler, less damaging crushing or grinding device should be selected to process it.

[0058] After initial crushing, the particle size of the resulting powder needs to be tested. If the proportion of particles larger than 20 μm exceeds the allowable deviation limit of 2% in the total amount, it indicates that some particles are too large and may affect the overall electrochemical performance of the material. At this time, more refined operations are needed, such as using more efficient crushing methods to further reduce these oversized particles until they meet the specifications.

[0059] Throughout the process, it is also necessary to constantly balance the relationship between efficiency and finished product quality. On the one hand, it is necessary to ensure that the overall crushing and processing time is short and the output per unit time is high. On the other hand, it is also necessary to ensure that the size of the crushed particles is uniformly distributed in the range of 1 to 20 micrometers. This can reduce production costs and improve the practical application efficiency of materials while taking into account both requirements. Particles within this range can significantly optimize the cycle stability and overall specific capacity performance of the negative extreme, thus laying the foundation for the subsequent preparation of key components required for lithium-ion batteries with excellent electrical performance.

[0060] In actual operation, when using this device, it is essential to first ensure a stable working environment, i.e., an inert gas atmosphere, to minimize the impact of air on the reaction materials. Then, following the operating procedure described in claim 1, the specific workflow is as follows: First, the pre-prepared nano-silicon particles, as the main active ingredient, are thoroughly mixed with a pre-determined carbon source in a dedicated mixer. This process requires not only uniform distribution of the mixture but also ensuring that it remains under the protection of an inert gas throughout the mixing process. After thorough mixing, the next step in the resulting solid powder mixture is a heat treatment process, which is carried out in an inert atmosphere-protected chamber or furnace. This process gradually raises the temperature of the mixture to a preset working temperature and maintains it for a certain period. During the heat treatment process… The process involves promoting the uniform coating of carbon molecules onto silicon particles under certain conditions, forming a carbon coating layer. This carbon coating effectively inhibits the direct exposure of active silicon particles, reduces structural damage during charging and discharging, and significantly improves the stability of the silicon-carbon composite. After the high-temperature process is completed, the next step is to use a cooling system to slowly cool the heated sample back to room temperature, ensuring the integrity of the silicon-carbon material structure and preventing damage due to rapid temperature drop. Finally, the material, now cooled to ambient temperature, is placed in a mechanical crushing mechanism for pulverization to meet the final particle size requirements. Combined with a sieving process, a negative electrode product within the predetermined size range is obtained. This series of rigorous steps constitutes a silicon-based negative electrode material production process, aiming to provide solid technical support for the development and application of high-performance lithium battery negative electrodes.

[0061] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a silicon-based anode material, characterized in that, Includes the following steps: S101. Mix the nano-silicon particles and the carbon source evenly in an inert gas atmosphere to form a mixture; S102. The mixture obtained above is subjected to heat treatment to achieve carbon coating on silicon particles; S103. After heat treatment, the product is cooled to room temperature under an inert atmosphere to obtain a silicon-carbon composite material. S104. The cooled silicon-carbon composite material is crushed and sieved to prepare anode materials with the required particle size range.

2. The method for preparing a silicon-based anode material according to claim 1, characterized in that, In step S102, the specific operation of heat treatment of the mixture is as follows: S201. Place the mixture containing nano-silicon particles and carbon source into the reactor, and keep the temperature inside the reactor within the preset temperature range. S202. Control the reaction temperature inside the reactor to be higher than the first set threshold and keep it at that temperature for a duration of the first time period. S203. Control the reaction temperature to drop below the second set threshold and keep it at that temperature to cure the carbon coating. The holding time is the second time period. S204. Allow the mixture to heat up naturally and stabilize under an inert gas atmosphere.

3. The method for preparing a silicon-based anode material according to claim 2, characterized in that, The specific operation of step S202 is as follows: S301. Detect the actual heating temperature inside the reactor. ; S302, if the actual heating temperature Equal to or higher than the predefined maximum target reaction temperature Then the temperature control program will be activated; in, ; S303. Start the heat preservation countdown timer, and wait until the specified heat preservation time is reached. Previously maintained the highest target reaction temperature The heating process; in, , This indicates the preset total insulation time; S304. After the heat preservation time is over, reduce the power supply and gradually cool down.

4. The method for preparing a silicon-based anode material according to claim 3, characterized in that, In step S301, the actual heating temperature inside the reactor is detected. The operation is as follows: S401. Continuously measure the temperature change inside the reactor using thermocouples and record it as the current temperature. ; S402. Continuously measure and record until detected. If so, then perform the heat preservation operation; in, Indicates the temperature control tolerance value; S403, when Immediately implement cooling measures to keep the temperature below [a certain level]. ; in This indicates the maximum temperature difference control threshold, ensuring... Always ; S404. Maintain the temperature within the set range until the preset total holding time is reached. The process ends, and heating is immediately stopped.

5. The method for preparing a silicon-based anode material according to claim 4, characterized in that, The specific operation of step S404 is as follows: S501, if If the temperature is high, continue the heat preservation operation; otherwise, proceed with the cooling process. S502, Ensure that during the insulation period... ; in, This indicates the set lower limit of temperature difference tolerance; S503, real-time monitoring and power adjustment based on current temperature to ensure ; S504. After the insulation period is completed, gradually adjust the equipment temperature down to the predetermined level and begin natural cooling.

6. The method for preparing a silicon-based anode material according to claim 2, characterized in that, In step S104, the specific operation process for crushing and sieving the cooled silicon-carbon composite material is as follows: S601. Place the cooled silicon-carbon composite material into a crushing device and crush it; S602. The crushed product is screened and classified to ensure that the particle size of the obtained product is within the pre-designed range. If the particle size exceeds the set standard, the crushing operation is returned. S603. Place the product particles that meet the standard into a drying device to remove any residual moisture. S604. Store and package the finished products that have undergone the above processing and meet all size requirements for further use or direct shipment. In step S102, the specific operation of heat treating the mixture further includes: S701, Set the heating temperature range from 500 degrees Celsius to 1000 degrees Celsius; S702. Place the above mixture into a tube furnace and keep it at a set temperature for a certain period of time, specifically 1 to 4 hours. S703. If the temperature during the heating process is below 500 degrees Celsius or above 1000 degrees Celsius, the temperature within the range shall be reset and the heat treatment shall be restarted. S704. After being kept at a certain temperature for a certain period of time, allow it to cool naturally or with nitrogen to a temperature of 600 degrees Celsius or below, and continue with subsequent cooling steps until it reaches room temperature.

7. The method for preparing a silicon-based anode material according to claim 6, characterized in that, It also includes a method for measuring the degree of uniformity of mixing in step S101, specifically: S801. If the detected mixing uniformity is lower than the set standard, increase the heating start temperature and reduce the heat preservation time to improve the wrapping uniformity. Among them, the heating start temperature is at least higher than the minimum value. 1, and 50℃≤ 1≤200℃; S802. If the mixing uniformity meets or exceeds the set standard, maintain the standard heat treatment temperature and extend the holding time.

2. To ensure adequate coverage; Among them, 5h≤ 2≤3.5h; S803. If the carbon layer thickness of the final product is greater than 0.5 nanometers, it is judged that the heat treatment effect is better than expected; otherwise, fine-tuning is made according to the insufficient thickness. S804. Set a thickness difference E. If the thickness difference E is less than 0 nanometers or greater than 0.1 nanometers, adjust the heat treatment conditions and repeat the heat treatment steps until the requirements in step S803 are met. Wherein, the thickness difference E = target minimum thickness - actual thickness.

8. The method for preparing a silicon-based anode material according to claim 7, characterized in that, When the thickness difference of the carbon layer E < 0 or E > 0.1 nm, the control and correction of the temperature change caused by the adjustment of the heat treatment temperature during the process of adjusting the heat treatment conditions are further limited as follows: S901. If the temperature change value does not conform to the range during the adjustment process, the actual temperature setting shall be corrected according to the mixing state, i.e., the temperature correction amount. 3 = (Target mixing uniformity - Measured mixing uniformity) × 1% × Temperature increment coefficient α; Where α is an adjustment value ranging from 1 to 0.9; S902, if calculated based on the measured mixing state 1. Error corresponding to the theoretical value of the mixed state with the set standard 1. Adjust the correction amount for the heating start temperature based on the measured deviation value E of the actual carbon layer thickness: 3 Correction = (0.5 nm - actual thickness) / 10 × 1% × heating start temperature; Among them, 50℃≤ 1≤150℃; S903. If the actual carbon coating thickness is less than 0.1 nanometers below the standard thickness or the carbon coating thickness increase rate is too slow, i.e. If 2 < 1 hour, then extend the heat preservation time to 2 + (50nm / μm heat treatment process thickness increase rate) / reciprocal of thickness increase per minute; S904. The maximum rate of natural cooling after heat preservation is limited to v (℃ / min), and v satisfies: 35℃ / min < v < 50℃ / min.

9. The method for preparing a silicon-based anode material according to claim 8, characterized in that, In step S904, the method of natural cooling after heat preservation is as follows: S1001. If the temperature does not drop by 500°C within 3 hours after heat preservation, it is determined to be poor cooling. Increase the nitrogen pressure by 5 psi to accelerate the cooling. S1002. If the temperature does not reach the standard cooling range of 600℃ after the maximum heat preservation time has been reached, further check whether there is a fault in the cooling equipment and carry out corresponding equipment maintenance. S1003. Before the final product is cooled to room temperature, this process must not be terminated until one of the following is resolved: the cooling process is uninterrupted, nitrogen protection is uninterrupted during the cooling process, and no cracks or agglomeration of particles appear after cooling. S1004. The range of temperature change fluctuation V during the cooling process is 1℃≤V≤5℃. If it exceeds this range, the temperature change shall be kept within the normal range by controlling the cooling environment conditions.

10. The method for preparing a silicon-based anode material according to claim 9, characterized in that, The specific requirements for crushing the silicon-carbon composite material finally obtained in step S104 include: S1101. After measuring the hardness H of the silicon-carbon composite material sample, select a suitable crushing method. When H is below 35HBW (10kgf / mm²), [further details are needed]. 2 When processing, use a gentler grinder; S1102. In silicon-carbon composite material samples, if the proportion of particles with a diameter greater than 20 μm above the target range exceeds 2% of the total mass, fine crushing methods should be used to reprocess them to meet the standard. S1103. Comprehensively evaluate crushing efficiency and final product performance to ensure that the average size d of crushed particles remains 1μm < d < 20μm in order to achieve ideal electrochemical performance.

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