A method for forming an SEI film in a battery

Abstract

This invention relates to the field of battery technology and discloses a method for forming an SEI film in a battery, comprising the following steps: Step 1, surface pretreatment; Step 2, initial linear scanning; Step 3, SEI film reforming; Step 4, final linear scanning; Step 5, real-time monitoring; and Step 6, real-time adjustment. This invention ensures uniform SEI film formation on the electrode surface through a series of precise steps and technical measures during the SEI film formation process in the battery. A multi-segment scanning strategy is employed for the initial linear scanning, gradually increasing the voltage and performing multiple scans to effectively control the initial formation and uniformity of the SEI film. Quality inspection is performed using a scanning electron microscope (SEM), and feedback adjustments are made based on the inspection results to further ensure uniform SEI film formation and high performance. This achieves the beneficial effect of improving SEI film uniformity and ensuring uniform formation of the SEI film in different regions.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a method for forming an SEI film in a battery. Background Technology

[0002] Solid-state electrolyte interfaces (SEIs) are of paramount importance in lithium-ion batteries. On one hand, SEI films can exist stably in solvents, effectively inhibiting material dissolution and solvent molecule co-intercalation, protecting electrode materials, and thus significantly improving cycle stability and electrode lifespan. On the other hand, SEI films allow ions to pass through while inhibiting electrons, ensuring the formation of side reactions, guaranteeing continuous charge and discharge of the "rocking chair battery," and suppressing excessive lithium-ion consumption, thereby extending battery life.

[0003] To address the aforementioned technical problems, a battery formation method for forming a stable SEI film was discovered through a search. The method involves (1) applying a voltage to the electrodes of the battery to be formed and performing a linear scan to obtain a battery with a pre-constructed SEI film; (2) reforming the pre-constructed SEI film in the battery obtained in step (1) to obtain a battery with a reformed SEI film; and (3) applying a voltage to the electrodes of the reformed SEI film in step (2) and performing a linear scan to obtain the formed battery. The battery formation method for forming a stable SEI film provided by this invention can construct a very stable SEI film on the negative electrode surface, reducing irreversible capacity loss in the battery, and improving the wettability inside the battery, thus reducing the time cost of the battery fabrication process.

[0004] However, the aforementioned technical solution, which applies voltage to the electrode for linear scanning, does not form an SEI film uniformly in all areas, resulting in poor uniformity of the SEI film. In addition, multiple processing steps also affect the consistency of the SEI film. Especially in large-scale production, it is difficult to guarantee that every battery can obtain an SEI film of the same quality. Summary of the Invention

[0005] Technical problems to be solved:

[0006] To address the shortcomings of existing technologies, this invention provides a method for forming an SEI film in a battery, which has advantages such as improving the uniformity of the SEI film, enabling the SEI film to form uniformly in different regions, and real-time monitoring and adjustment of parameters at each step during large-scale production to ensure the consistency of the SEI film, thus solving the problems mentioned above.

[0007] Technical solution:

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for forming an SEI film in a battery, comprising the following steps:

[0009] Step 1: Surface pretreatment: Mechanical polishing is used to pretreat the surface of the electrode to be formed into a battery. Metal nanoparticles are then coated on the pretreated electrode surface to improve the conductivity and surface properties of the electrode.

[0010] Step 2, Initial Linear Scan: Apply voltage to the pretreated electrode for initial linear scan. Use a multi-segment scan strategy, gradually increasing the voltage. Adjust the scan speed according to the characteristics of the electrode material and electrolyte, from 0V to 1.0-1.5V, within the range of 5-50mV / s, to ensure the initial formation of the SEI film. Perform 3-5 scans to ensure the uniformity of the SEI film.

[0011] Step 3, SEI film reforming: The SEI film is reformed using a constant current charge-discharge method to improve its structure and stability. Based on the battery capacity, a current density in the range of 0.1-1C is selected, and 3-5 charge-discharge cycles are performed.

[0012] Step 4: Final linear scan: Apply voltage to the electrodes of the reformed SEI film cell to perform a final linear scan. According to the characteristics of the reformed SEI film, adjust the scan speed within the range of 10-100mV / s, gradually increasing it from 0V to 1.0-1.5V, and perform 2-3 scans to ensure the uniformity and stability of the SEI film.

[0013] Step 5: Real-time monitoring: Monitor voltage, current, and temperature parameters in each step;

[0014] Step Six: Real-time Control: An automated control system is adopted to dynamically adjust the parameters of each step based on real-time monitoring data to ensure the consistency of the SEI film. Quality inspection is carried out after each step, and the uniformity and thickness of the SEI film are checked using a scanning electron microscope (SEM). Feedback adjustments are made based on the inspection results.

[0015] Preferably, step one further includes the following detailed steps:

[0016] S1.1 Electrode surface cleaning: Use acetone and ethanol to ultrasonically clean the electrode surface in sequence to remove organic contaminants and moisture, dry the electrode, and ensure that there is no residual solvent on the surface;

[0017] S1.2 Mechanical polishing: Fix the electrode on the polishing machine, select a coarse-grained polishing cloth (400 mesh) for preliminary polishing to remove surface unevenness and impurities, switch to a fine-grained polishing cloth (1000-2000 mesh) for continued polishing. During the polishing process, clean the electrode with deionized water every 3-5 minutes to remove particles and impurities generated during polishing.

[0018] S1.3 Surface roughness inspection: Use a surface roughness meter to inspect the surface roughness of the polished electrode to ensure that it meets the required flatness standard: Ra<0.1μm;

[0019] S1.4 Metal nanoparticle coating: Prepare a metal nanoparticle solution with a concentration determined according to experimental needs, usually 0.1-1 mg / mL. Immerse the polished electrode in the metal nanoparticle solution for coating. Place the coated electrode in a vacuum drying oven and set it to 60°C for 30 minutes for drying, so that the metal nanoparticles adhere to the electrode surface.

[0020] Preferably, the single-segment scan time in step two is calculated as follows:

[0021]

[0022] Where: t i v represents the scan time of the i-th segment, in seconds; i denoted as the scanning speed of the i-th segment, in millivolts per second.

[0023] Preferably, the total scan time in step two is calculated as follows:

[0024]

[0025] Where: T is the total scan time, in seconds; t i The scan time for the i-th segment is in seconds.

[0026] First segment: Voltage changes from 0V to 0.5V, voltage increment ΔV1 = 0.5V, scan speed v1 = 10mV / s, calculation time is:

[0027]

[0028] Second segment: Voltage increases from 0.5V to 1.0V, voltage increment ΔV2 = 0.5V; scan speed v2 = 20mV / s; calculation time is:

[0029] Preferably, the constant current charging-discharging calculation in step three is as follows:

[0030] Assuming the battery capacity is C, the current density is selected to be between 0.1C and 1C;

[0031] The constant current charging calculation is as follows:

[0032]

[0033] Where: t charge I represents the charging time, in hours; I represents the charging current, in milliamperes.

[0034] Discharge time t discharge Calculate using the same formula as above:

[0035] Preferably, the time for each cycle in step three is calculated as follows:

[0036] t cycle =t charge +t discharge

[0037] Where: t cycle It is the time of each charge-discharge cycle, in hours; t charge For charging time; t discharge Discharge time;

[0038] The total charge / discharge time T in step three total Total time for all periods:

[0039] T total =n×t cycle

[0040] Where: n is the total number of charge / discharge cycles, and t is the number of charge / discharge cycles performed; cycle The time for each charge / discharge cycle represents the duration required for a complete charge / discharge process.

[0041] Preferably, the scanning time in step four is calculated as follows:

[0042]

[0043] Where: t scan is the time for each scan, in seconds; v is the scan speed, in millivolts per second.

[0044] Preferably, in step four, the total scan time Ttotal is the total time for all scans:

[0045] T total =m×t scan

[0046] Wherein: T total This is the total scan time, in seconds; m is the number of scans performed.

[0047] Preferably, the SEI film thickness distribution calculation in step six is ​​as follows:

[0048] Let the thickness of the SEI film detected at multiple points be t. i Calculate the average thickness

[0049]

[0050] Where: the thickness of the SEI film is t i Average thickness is

[0051] Preferably, the standard deviation σ calculated in step six is:

[0052]

[0053] Where: the standard deviation is σ; the number of test points is n.

[0054] Compared with the prior art, the present invention provides a method for forming an SEI film in a battery, which has the following beneficial effects:

[0055] 1. This invention ensures the uniform formation of the SEI film on the electrode surface through a series of meticulous steps and technical measures during the formation of the SEI film in the battery. First, surface pretreatment includes electrode surface cleaning, mechanical polishing, and metal nanoparticle coating. These measures improve the smoothness and activity of the electrode surface, laying the foundation for the uniform formation of the SEI film. Next, a multi-segment scanning strategy is employed for initial linear scanning, gradually increasing the voltage and performing multiple scans to effectively control the initial formation and uniformity of the SEI film. Subsequently, the SEI film is restructured using a constant current charge-discharge method to further improve its structure and stability. Finally, the uniform distribution of the SEI film is ensured by dynamically adjusting the current density. In the final linear scanning process, the scanning speed is adjusted and multiple scans are performed to ensure the final uniformity and stability of the SEI film. Simultaneously, voltage, current, and temperature parameters are monitored in real time throughout the process, and an automated control system dynamically adjusts process parameters to ensure the consistency of the SEI film. Finally, quality inspection is performed using a scanning electron microscope (SEM), and adjustments are made based on the inspection results to further ensure the uniform formation and high performance of the SEI film. Through these comprehensive measures, the uniformity of the SEI film in different regions is effectively improved, thereby enhancing the overall performance and lifespan of the battery, achieving the beneficial effect of improving SEI film uniformity and ensuring its uniform formation in different regions.

[0056] 2. This invention achieves real-time monitoring and adjustment of parameters at each step in large-scale production by integrating an automated control system and high-precision monitoring equipment, combined with advanced data analysis and feedback mechanisms, ensuring the consistency of the SEI film. Specific measures include: using a highly integrated automated control system to collect key parameters such as voltage, current, and temperature in real time; monitoring the electrode surface state and the SEI film formation process using high-precision sensors and real-time imaging technology; establishing a big data platform to analyze production data using machine learning and artificial intelligence algorithms, predicting problems, and optimizing process parameters; performing real-time inspections after each step using automated quality inspection equipment, feeding the results back to the control system, and dynamically adjusting subsequent process parameters; and simultaneously training operators to ensure their proficiency in operating the equipment, and regularly maintaining and calibrating the monitoring equipment to ensure its accuracy and reliability. Through these comprehensive measures, the beneficial effect of real-time monitoring and adjustment of parameters at each step in large-scale production is achieved, ensuring the consistency of the SEI film. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the steps of the present invention; Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Please see Figure 1 A method for forming an SEI film in a battery, comprising the following steps:

[0060] Step 1: Surface pretreatment: Mechanical polishing is used to pretreat the surface of the electrode to be formed into a battery. Metal nanoparticles are then coated on the pretreated electrode surface to improve the conductivity and surface properties of the electrode.

[0061] Step 2, Initial Linear Scan: Apply voltage to the pretreated electrode for initial linear scan. Use a multi-segment scan strategy, gradually increasing the voltage. Adjust the scan speed according to the characteristics of the electrode material and electrolyte, from 0V to 1.0-1.5V, within the range of 5-50mV / s, to ensure the initial formation of the SEI film. Perform 3-5 scans to ensure the uniformity of the SEI film.

[0062] Step 3, SEI film reforming: The SEI film is reformed using a constant current charge-discharge method to improve its structure and stability. Based on the battery capacity, a current density in the range of 0.1-1C is selected, and 3-5 charge-discharge cycles are performed.

[0063] Step 4: Final linear scan: Apply voltage to the electrodes of the reformed SEI film cell to perform a final linear scan. According to the characteristics of the reformed SEI film, adjust the scan speed within the range of 10-100mV / s, gradually increasing it from 0V to 1.0-1.5V, and perform 2-3 scans to ensure the uniformity and stability of the SEI film.

[0064] Step 5: Real-time monitoring: Monitor voltage, current, and temperature parameters in each step;

[0065] Step Six: Real-time Control: An automated control system is adopted to dynamically adjust the parameters of each step based on real-time monitoring data to ensure the consistency of the SEI film. Quality inspection is carried out after each step, and the uniformity and thickness of the SEI film are checked using a scanning electron microscope (SEM). Feedback adjustments are made based on the inspection results.

[0066] In the process of forming an SEI film in a battery, a series of meticulous steps and technical measures are employed to ensure the uniform formation of the SEI film on the electrode surface. First, surface pretreatment includes electrode surface cleaning, mechanical polishing, and metal nanoparticle coating. These measures improve the smoothness and activity of the electrode surface, laying the foundation for uniform SEI film formation. Next, a multi-segment scanning strategy is used for the initial linear scan, gradually increasing the voltage and performing multiple scans to effectively control the initial formation and uniformity of the SEI film. Subsequently, the SEI film is reformed using a constant current charge-discharge method to further improve its structure and stability, and the uniform distribution of the SEI film is ensured by dynamically adjusting the current density. Finally, in the linear scan, the scan speed is adjusted and multiple scans are performed to ensure the final uniformity and stability of the SEI film.

[0067] Throughout the process, voltage, current, and temperature parameters are monitored in real time, and an automated control system dynamically adjusts process parameters to ensure the consistency of the SEI film. Finally, quality inspection is performed using scanning electron microscopy (SEM), and adjustments are made based on the inspection results to further ensure uniform SEI film formation and high performance.

[0068] Specifically, step one also includes the following detailed steps:

[0069] S1.1 Electrode surface cleaning: Use acetone and ethanol to ultrasonically clean the electrode surface in sequence to remove organic contaminants and moisture, dry the electrode, and ensure that there is no residual solvent on the surface;

[0070] S1.2 Mechanical polishing: Fix the electrode on the polishing machine, select a coarse-grained polishing cloth (400 mesh) for preliminary polishing to remove surface unevenness and impurities, switch to a fine-grained polishing cloth (1000-2000 mesh) for continued polishing. During the polishing process, clean the electrode with deionized water every 3-5 minutes to remove particles and impurities generated during polishing.

[0071] S1.3 Surface roughness inspection: Use a surface roughness meter to inspect the surface roughness of the polished electrode to ensure that it meets the required flatness standard: Ra<0.1μm;

[0072] S1.4 Metal nanoparticle coating: Prepare a metal nanoparticle solution with a concentration determined according to experimental needs, usually 0.1-1 mg / mL. Immerse the polished electrode in the metal nanoparticle solution for coating. Place the coated electrode in a vacuum drying oven and set it to 60°C for 30 minutes for drying, so that the metal nanoparticles adhere to the electrode surface.

[0073] Automated control system

[0074] Integrated control platform: Utilizing a highly integrated control system, it is capable of collecting and processing data from each step in real time. These systems typically include PLCs (Programmable Logic Controllers), SCADA (Supervisory and Data Acquisition Systems), and MES (Manufacturing Execution Systems).

[0075] Sensors and monitoring devices are set up at each step to collect data on key parameters such as voltage, current, temperature, and electrode surface roughness in real time. This data is transmitted to the central control platform via wired or wireless network.

[0076] The control system analyzes real-time data and automatically adjusts process parameters. For example, during the electrode surface pretreatment stage, the system can automatically adjust the polishing time and polishing cloth particle size based on feedback from the surface roughness meter.

[0077] High-precision sensors are used to monitor electrode surface cleanliness, polishing effect, and the distribution of metal nanoparticles on the electrode surface. For example, optical or electrochemical sensors are used to monitor the state of the electrode surface.

[0078] During SEI film formation, real-time imaging techniques (such as infrared imaging and electrochemical impedance spectroscopy, EIS) are used to monitor the formation process and uniformity of the SEI film. These techniques can provide detailed information about the SEI film formation process.

[0079] Establish a big data platform to store and analyze various data from the production process. Use machine learning and artificial intelligence algorithms to analyze data trends and patterns, predict potential problems, and propose optimization suggestions.

[0080] After each step, real-time monitoring data is compared with preset standards to identify deviations and adjust process parameters in a timely manner. For example, after the SEI membrane reforming step, the uniformity and thickness of the SEI membrane are detected by SEM, and the detection results are fed back to the control system to dynamically adjust the constant current charging and discharging parameters.

[0081] After each step, quality inspection is performed using automated equipment. For example, after electrode surface pretreatment, an automated surface roughness meter is used to check surface smoothness. After SEI film formation, automated SEM equipment is used to check the thickness and uniformity of the SEI film.

[0082] Based on the quality inspection results, the control system adjusts the process parameters of subsequent steps in real time. If the SEI film thickness is found to be uneven in the final linear scan, the control system can adjust the scanning speed or the number of scans to ensure the uniformity of the SEI film.

[0083] Specifically, the single-segment scan time in step two is calculated as follows:

[0084]

[0085] Where: t i v represents the scan time of the i-th segment, in seconds; i denoted as the scanning speed of the i-th segment, in millivolts per second.

[0086] Specifically, the total scan time in step two is calculated as follows:

[0087]

[0088] Where: T is the total scan time, in seconds; t i The scan time for the i-th segment is in seconds.

[0089] First segment: Voltage changes from 0V to 0.5V, voltage increment ΔV1 = 0.5V, scan speed v1 = 10mV / s, calculation time is:

[0090]

[0091] Second segment: Voltage increases from 0.5V to 1.0V, voltage increment ΔV2 = 0.5V; scan speed v2 = 20mV / s; calculation time is:

[0092] Specifically, the constant current charging-discharging calculation in step three is as follows:

[0093] Assuming the battery capacity is C, the current density is selected to be between 0.1C and 1C;

[0094] The constant current charging calculation is as follows:

[0095]

[0096] Where: t charge I represents the charging time, in hours; I represents the charging current, in milliamperes.

[0097] Discharge time t discharge Calculate using the same formula as above:

[0098] Specifically, the time for each cycle in step three is calculated as follows:

[0099] t cycle =t charge +t discharge

[0100] Where: t cycle It is the time of each charge-discharge cycle, in hours; t charge For charging time; t discharge Discharge time;

[0101] The total charge / discharge time T in step three total Total time for all periods:

[0102] T total =n×t cycle

[0103] Where: n is the total number of charge / discharge cycles, and t is the number of charge / discharge cycles performed; cycle The time for each charge / discharge cycle represents the duration required for a complete charge / discharge process.

[0104] Specifically, the scan time in step four is calculated as follows:

[0105]

[0106] Where: t scan is the time for each scan, in seconds; v is the scan speed, in millivolts per second.

[0107] Specifically, in step four, the total scan time Ttotal is the total time for all scans:

[0108] T total =m×t scan

[0109] Wherein: T total This is the total scan time, in seconds; m is the number of scans performed.

[0110] Specifically, the SEI film thickness distribution calculation in step six is ​​as follows:

[0111] Let the thickness of the SEI film detected at multiple points be t.i Calculate the average thickness

[0112]

[0113] Where: the thickness of the SEI film is t i Average thickness is

[0114] Specifically, in step six, the standard deviation σ is calculated as follows:

[0115]

[0116] Where: the standard deviation is σ; the number of test points is n.

[0117] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for forming an SEI film in a battery, characterized in that, Includes the following steps: Step 1: Surface pretreatment: Mechanical polishing is used to pretreat the surface of the electrode to be formed into a battery. Metal nanoparticles are then coated on the pretreated electrode surface to improve the conductivity and surface properties of the electrode. Step 2, Initial Linear Scan: Apply voltage to the pretreated electrode for initial linear scan. Use a multi-segment scan strategy, gradually increase the voltage, and adjust the scan speed according to the characteristics of the electrode material and electrolyte. The voltage is 5-50 mV / s, gradually increasing from 0V to 1.0-1.5V to ensure the initial formation of the SEI film. Perform 3-5 scans to ensure the uniformity of the SEI film. Step 3, SEI film reforming: The SEI film is reformed using a constant current charge-discharge method to improve its structure and stability. Based on the battery capacity, a current density in the range of 0.1-1C is selected, and 3-5 charge-discharge cycles are performed. Step 4: Final linear scan: Apply voltage to the electrodes of the reformed SEI film cell to perform a final linear scan. According to the characteristics of the reformed SEI film, adjust the scan speed within the range of 10-100mV / s, gradually increasing it from 0V to 1.0-1.5V, and perform 2-3 scans to ensure the uniformity and stability of the SEI film. Step 5: Real-time monitoring: Monitor voltage, current, and temperature parameters in each step; Step Six: Real-time Control: An automated control system is adopted to dynamically adjust the parameters of each step based on real-time monitoring data to ensure the consistency of the SEI film. Quality inspection is carried out after each step, and scanning electron microscope (SEM) is used to check the uniformity and thickness of the SEI film. Feedback adjustments are made based on the inspection results. The constant current charging-discharging calculation in step three is as follows: Assuming the battery capacity is C, the current density is chosen to be between 0.1C and 1C; The constant current charging calculation is as follows: ， in: Charging time, in hours; Discharge time The same formula is used for calculation: ; It is the charging current, measured in milliamperes (mA).

2. The method for forming an SEI film in a battery according to claim 1, characterized in that: Step one also includes the following detailed steps: S1.1 Electrode surface cleaning: Use acetone and ethanol to ultrasonically clean the electrode surface in sequence to remove organic contaminants and moisture, dry the electrode, and ensure that there is no residual solvent on the surface; S1.2 Mechanical polishing: Fix the electrode on the polishing machine, select a coarse-grained polishing cloth (400 mesh) for preliminary polishing to remove surface unevenness and impurities, switch to a fine-grained polishing cloth (1000-2000 mesh) for continued polishing. During the polishing process, clean the electrode with deionized water every 3-5 minutes to remove particles and impurities generated during polishing. S1.3 Surface roughness inspection: Use a surface roughness meter to inspect the surface roughness of the polished electrode to ensure that it meets the required flatness standard: Ra<0.1μm; S1.4 Metal nanoparticle coating: Prepare a metal nanoparticle solution with a concentration of 0.1-1 mg / mL, immerse the polished electrode in the metal nanoparticle solution for coating, place the coated electrode in a vacuum drying oven, set 60°C for 30 minutes for drying, so that the metal nanoparticles adhere to the electrode surface.

3. The method for forming an SEI film in a battery according to claim 1, characterized in that: The single-segment scan time in step two is calculated as follows: ， in: For the first The scanning time of the segment, in seconds; For the first The scanning speed of the segment is measured in millivolts per second.

4. The method for forming an SEI film in a battery according to claim 1, characterized in that: The total scanning time in step two is calculated as follows: ， in: Total scan time, in seconds; For the first The scanning time of the segment, in seconds; First segment: Voltage changes from 0V to 0.5V, voltage increment ΔV1 = 0.5V, scan speed v1 = 10mV / s, calculation time is: ， Second segment: Voltage increases from 0.5V to 1.0V, voltage increment ΔV2 = 0.5V; scan speed v2 = 20mV / s; calculation time is: 。 5. A method for forming an SEI film in a battery according to claim 4, characterized in that: The time for each cycle in step three is calculated as follows: ， in: This is the time for each charge / discharge cycle, in hours. This refers to charging time; Discharge time; The total charge / discharge time in step three Total time for all periods: ， in: The total number of charge / discharge cycles is the number of charge / discharge cycles performed. The time for each charge / discharge cycle represents the duration required for a complete charge / discharge process.

6. The method for forming an SEI film in a battery according to claim 1, characterized in that: The scanning time in step four is calculated as follows: ， in: It is the time for each scan, in seconds; It is the scanning speed, measured in millivolts per second.

7. A method for forming an SEI film in a battery according to claim 6, characterized in that: The total scanning time in step four Total time for all scans: ， in: This is the total scan time, in seconds; The number of scans performed.

8. The method for forming an SEI film in a battery according to claim 1, characterized in that: The SEI film thickness distribution calculation in step six is ​​as follows: Assume the SEI film thickness at multiple points is detected. Calculate the average thickness : ， Where: SEI film thickness is Average thickness is The number of testing sites is .

9. A method for forming an SEI film in a battery according to claim 8, characterized in that: The standard deviation is calculated in step six. for: ， Where: standard deviation is The number of testing points is .

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