Lithium battery pre-lithiation method

Abstract

The invention discloses a lithium battery pre-lithiation method, and belongs to the field of battery manufacturing. A lithium battery pre-lithiation method comprises the following steps: preparing a lithium-containing material in a vacuum environment, grinding and mixing to obtain a pre-lithiation material; coating the lithium battery negative electrode material with the pre-lithiated material by using an inert gas protection technology; controlling the discharge amount in the coating process based on an electrochemical lithium intercalation theory so as to accurately adjust the pre-lithiation amount; and performing high-temperature annealing treatment to enhance the performance of the lithium battery and remove organic solvent residues possibly introduced in the coating process. Through the scheme of the embodiment of the invention, the problems that the pre-lithiation amount is difficult to accurately control and impurities are possibly introduced in the pre-lithiation process of the existing lithium battery can be solved.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, and in particular to a method for pre-lithiation of lithium batteries. Background Technology

[0002] Lithium-ion battery pre-lithiation refers to the technology of pre-replenishing the negative electrode of the battery with lithium ions through chemical or physical means to compensate for lithium loss during the initial charge and discharge process, thereby improving the overall energy density. However, in the existing lithium-ion battery pre-lithiation process, how to accurately control the amount of pre-lithiation and avoid introducing other impurities during the process is a critical problem that urgently needs to be solved. For the former, if the amount of lithium replenishment cannot be well controlled, it may lead to over-lithiation or under-lithiation. Over-lithiation not only increases additional costs but also reduces safety, while under-lithiation leads to cycle performance degradation and fails to significantly improve the initial energy density. For the latter, the presence of impurities may increase the internal resistance of the battery and may cause safety problems such as short circuits and lithium plating. These problems greatly affect the overall performance and safety level of lithium-ion batteries. In view of this, the present invention is proposed. Summary of the Invention

[0003] The purpose of this invention is to solve the problems existing in the prior art by proposing a method for pre-lithiation of lithium batteries.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for pre-lithiation of lithium batteries includes the following steps: S101. Prepare lithium-containing materials in a vacuum environment and grind and mix them to obtain pre-lithiated materials; S102. Apply pre-lithiated material to lithium battery anode material using inert gas protection technology; S103. Based on the electrochemical lithium intercalation theory, the discharge amount during the coating process is controlled to precisely adjust the pre-lithiation amount; S104. Perform high-temperature annealing to enhance the performance of the lithium battery and remove any organic solvent residues that may have been introduced during the coating process.

[0005] Preferably, in step S102, the step of precisely adjusting the pre-lithiation amount includes: S201. Determine the target value of the preset discharge quantity. ; S202. Measure the discharge amount during the actual coating process. ; S203, Calculation of Deviation ; S204. Adjust the duration of pre-lithiation material coating based on the calculated deviation. Until It falls within the permissible range.

[0006] Furthermore, in step S204, adjusting the duration of the pre-lithiation material coating specifically includes the following steps: S301, if Greater than the preset positive deviation This reduces the coating speed and extends the duration; S302, if Within the set small deviation range If so, maintain the current coating state and fine-tune the duration; S303, if Less than the preset negative deviation This increases the coating speed and shortens the duration; S304. Repeat the above steps to adjust the pre-lithiation material coating in real time with precision.

[0007] Furthermore, the process of controlling the coating speed and coating duration includes: S401, if > According to the predefined ratio Slow down the current coating speed Adjusted coating speed ,in ; S402, if ,but If the deviation is within a negligible range, continue coating as planned. remain unchanged. Remain unchanged; S403, if According to the predefined ratio Increase the speed, adjust the coating speed ,in The above , The coefficients were obtained through experimental calibration.

[0008] Furthermore, the adjustment of the corresponding coating action when determining whether the deviation exceeds the allowable deviation value includes: S501, when If necessary, pause the coating process, reduce the discharge level to the preset low discharge point, and then restart the coating process. in, This is the maximum permissible positive deviation; S502. During the coating process, continuously monitor the coating status and record the deviation change curve. Determine whether emergency coating correction is needed based on the inflection point on the curve. S503, when And it has been maintained If the system is considered stable after one consecutive cycle, the coating will continue with the existing parameters until the predetermined coating thickness is achieved. ; in, This indicates the minimum permissible negative deviation of lithium content. This indicates the minimum permissible positive deviation of lithium content. This represents the minimum number of measurement cycles required to achieve a steady state. S504. If the above system stability conditions are not met, repeat the above dynamic deviation adjustment process to ensure that the discharge accuracy reaches the predetermined standard.

[0009] Preferably, in step S104, the high-temperature annealing process is as follows: S601, The temperature reaches the target annealing temperature by using a preset heating slope. ; S602, standby temperature a period of time To improve structural uniformity, infrared detection technology is used to ensure that there are no abnormalities. S603, Based on the temperature-resistance relationship: Determine whether a rapid cooling procedure is necessary to reduce harmful crystallization; S604. Slowly lower the furnace temperature until it is below the target annealing cooling temperature and complete the annealing process.

[0010] Furthermore, in step S204, the allowable range is the target interval. ,in, This refers to the permissible error threshold for the pre-lithiated lithium content. This represents the maximum permissible deviation of the measured lithium content from the target value. This refers to the maximum permissible deviation of the measured lithium content from the target value.

[0011] Furthermore, in calculating the deviation after, like Then reduce the duration. ; like Then increase the duration. When the duration Reaching maximum allowable duration If so, no additional operation will be performed; Recording deviation To assess the accuracy of the discharge quantity and correct the coating process in real time accordingly; exist and Under the premise that the target range has been accurately adjusted, it is determined that the target range has been accurately adjusted.

[0012] Preferably, in recording deviation This includes: If in In this measurement, at least one The measurement satisfies This confirms that the precise adjustment has been completed. and It is an even number; like If the discharge process is unstable, it is necessary to pause and check the coating parameter settings. exist The results of three consecutive measurements fell on When the range is within the specified range, further reduce the error threshold. And start measuring again; exist fall into If the temperature falls within the target range for five consecutive cycles after the initial phase, it is determined that the final pre-lithiation amount has been precisely adjusted, and the high-temperature annealing step continues.

[0013] Further, the actual discharge amount is calculated according to the following steps: S1001, Set an actual discharge efficiency If η is greater than or equal to the set discharge efficiency threshold If the pre-lithiation process can effectively control the amount of pre-lithiation, the discharge quantity meets the conditions and the process continues. S1002, if ,but If the discharge efficiency is low, it is determined that it still meets the deviation requirements within the precise control range of pre-lithiation adjustment. S1003, such as ,and If this is the case, there is an internal abnormality in the battery, and repair measures need to be taken. S1004, if fall into Scope, and If the value is 0%, it is considered a serious imbalance. The pre-lithiation process should be stopped immediately and a system diagnostic should be performed. The deviation The measurements include: Test and record the charge accumulation increment corresponding to the coating process every 5 minutes. ; Algorithm calculation bias , in, This represents the amount of charge generated under ideal conditions corresponding to the complete reaction of the pre-lithiated material. This is the integral value of the actual measured cumulative discharge. once The adjustment process should be stopped immediately. If all 5 tests meet the conditions of the previous step, or if the cumulative testing time reaches 30 minutes and remains stable each time, then the adjustment is considered complete and the pre-lithiation amount has been precisely controlled.

[0014] Compared with the prior art, the present invention provides a method for pre-lithiation of lithium batteries, which has the following beneficial effects: 1. The lithium battery pre-lithiation method includes preparing lithium-containing materials in a vacuum environment and grinding and mixing them to obtain pre-lithiation materials. Then, the pre-lithiation materials are coated onto the negative electrode material of the lithium battery using inert gas protection technology. Next, based on the electrochemical lithium intercalation theory, the discharge amount during the coating process is controlled to precisely adjust the pre-lithiation amount. High-temperature annealing is then performed to enhance the performance of the lithium battery and remove any organic solvent residues that may be introduced during the coating process. The solution in this application can solve the problems of difficulty in accurately controlling the pre-lithiation amount and the possible introduction of impurities in the existing lithium battery pre-lithiation process. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of a lithium battery pre-lithiation method proposed in this invention; Figure 2 This is a flowchart illustrating the steps for precisely adjusting the pre-lithiation amount in this invention. Figure 3 This is a flowchart illustrating the steps for adjusting the duration of pre-lithiation material coating in this invention. Figure 4 This is a flowchart illustrating the process of controlling the coating speed and coating duration in this invention; Figure 5 This is a flowchart illustrating the adjustment process for the corresponding coating action in determining whether the deviation exceeds the allowable deviation value in this invention. Figure 6 This is a flowchart of the high-temperature annealing process in this invention; Figure 7 In this invention, the deviation is calculated The following flowchart; Figure 8 In this invention, the recording deviation The following flowchart; Figure 9 This is a schematic diagram of the process for calculating the actual discharge amount in this invention. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] 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.

[0018] Example: Reference Figure 1 A method for pre-lithiation of lithium batteries includes the following steps: S101. Prepare lithium-containing materials in a vacuum environment and grind and mix them to obtain pre-lithiated materials; Specifically, preparation work is carried out in a vacuum environment completely isolated from harmful substances such as air and water vapor, and the purity and uniformity of lithium-containing raw materials are ensured. When preparing the materials required for pre-lithiation, lithium-containing materials suitable for the lithium replenishment function of the negative electrode active components of lithium batteries are selected, such as lithium metal foil or Li metal particles, alloy materials, etc. The lithium-containing raw materials are thoroughly mechanically ground and precisely mixed in proportion to produce fine-grained pre-lithiation powder materials, and the quality of each batch of mixture is kept stable and consistent.

[0019] In this application, lithium metal powder with a particle size of about 0.5 mm is used as the main source of lithium replenishment, and it is mixed with inorganic lithium salt in a specific ratio. The mixture is stirred for a long time with the help of a special grinding device until the predetermined particle size requirement is met, so as to obtain a lithium battery negative electrode pre-lithiation material with uniform and fine mixing and good stability. S102. Apply pre-lithiated material to lithium battery anode material using inert gas protection technology; S103. Based on the electrochemical lithium intercalation theory, the discharge amount during the coating process is controlled to precisely adjust the pre-lithiation amount; S104. Perform high-temperature annealing to enhance the performance of the lithium battery and remove any organic solvent residues that may have been introduced during the coating process.

[0020] Specifically, the negative electrode is pre-treated by coating under the protection of inert gases such as argon, so that the pre-mixed metal or lithium alloy particles are evenly covered on the surface of the entire negative electrode structure to form a stable protective film. During the coating operation, the speed and density of the spraying material are precisely controlled by an automatic control spray gun to ensure that the thickness of the deposited film is suitable for the requirements of the subsequent electrochemical reduction reaction. After this, the entire assembly is completed and purified by a drying process before being placed in a special pyrolysis tank for the next step of processing.

[0021] In this application, an automated roll-to-roll device is used to assemble a pre-fabricated cathode or anode plate containing a uniform film of a predetermined thickness and send it into a specially designed molding chamber. During this process, the surrounding environment is kept full of stable rare elements such as argon or neon to eliminate all external influences. Then, according to preset parameters, the heater is turned on to gradually raise the temperature to the range of 200°C to 600°C and maintain it for a sufficient time until the film layer is fully coupled with the substrate and the surface is smooth and flat without obvious wrinkles. The set temperature is then further increased to over 700°C to completely vaporize and escape the organic media present inside, thus achieving an ideal inorganic treatment process.

[0022] The above detailed steps optimize the implementation process of the lithium battery negative electrode pre-lithiation process. Under vacuum and inert atmosphere conditions, the purification and homogeneous distribution of lithium ions are ensured, and the introduction of contaminants is avoided. In addition, the discharge capacity is accurately adjusted by rigorously calculating and monitoring current and voltage parameters in real time, thereby effectively achieving the expected lithium replenishment target. This will greatly help overcome the inherent problems of conventional technologies, such as the inability to precisely control dosage accuracy and the unavoidable introduction of external contaminants. The overall method solves the problem of accurately controlling the pre-lithiation amount through a series of strict control measures, while ensuring that no new impurities are introduced, greatly improving and enhancing the safety and reliability standards of pre-lithiation batteries.

[0023] Reference Figure 2 In step S102, the step of precisely adjusting the pre-lithiation amount includes: S201. Determine the target value of the preset discharge quantity. Based on the characteristics of the cathode material to be pre-lithiated and the specific needs of pre-lithiation, the required preset discharge amount is determined. This value is set according to factors such as battery type, quality of active material and required capacity compensation. For example, when manufacturing a power battery with high energy density and expected significant first-efficiency loss, a higher target discharge amount may be preset. S202. Measure the discharge amount during the actual coating process. During the pre-lithiation process of the positive electrode or positive electrode active material, a high-precision coulometer, galvanometer, or other appropriate instruments are used to monitor and record the total current discharge involved in the coating process as the actual discharge amount. This measurement is typically performed under stable, controlled conditions, such as within a specific temperature range, and is recorded continuously throughout the coating process. S203, Calculation of Deviation The deviation is obtained by comparing the target discharge amount with the actual discharge amount achieved during the coating process and obtaining the difference between the actual process and the expected amount. If the actual effect of pre-lithiation is less than the target, then A positive value indicates a negative value indicates a negative value indicates a negative value. This step can be performed by comparing and calculating a single data point in real time, or by continuously tracking the overall average deviation in the entire pre-lithiation process in real time to dynamically adjust the control conditions of subsequent pre-lithiation operations. S204. Adjust the duration of pre-lithiation material coating based on the calculated deviation. Until If the calculated deviation falls within the acceptable range, and if it exceeds a predefined tolerance limit, the coating parameters will be changed automatically or manually via the human-machine interface settings. Specifically, the coating time can be extended or reduced to adjust the overall discharge amount of the coating process, thereby allowing... The goal is to get as close to zero as possible, or to fall within a pre-specified target threshold range. This correction may require iterative iterations until satisfactory accuracy is achieved. Typically, this process is automated by programming the pre-lithiation equipment, using software programs to effectively control the parameters of the entire coating process, ensuring the consistency and stability of the battery products. For example, if the initial pre-lithiation material coating time is set to 10 minutes, and the calculated deviation is large, it is found that an additional 3 minutes is needed. Therefore, the coating time is extended to 13 minutes to meet the required pre-lithiation effect and discharge target, thereby ensuring good consistency in the mass-produced finished products.

[0024] In this way, through the above series of precise control and dynamic adjustment processes, the consistency of battery pre-lithiation treatment and the accurate implementation of the preset plan are effectively guaranteed.

[0025] Reference Figure 3 In step S204, adjusting the duration of the pre-lithiation material coating specifically includes the following steps: S301, if Greater than the preset positive deviation This reduces the coating speed and extends the duration; S302, if Within the set small deviation range If so, maintain the current coating state and fine-tune the duration; S303, if Less than the preset negative deviation This increases the coating speed and shortens the duration; S304. Repeat the above steps to adjust the pre-lithiation material coating in real time with precision.

[0026] The amount of lithium replenishment required for pre-lithiation is measured and calculated in real time during the coating process. The deviation from the target lithium replenishment amount is used to determine whether the value falls within the target range. The region with a positive deviation or above, and the area experiencing small fluctuations. The deviation is still below the negative range. This assessment will serve as the basis for adjusting the coating parameters.

[0027] Once the specific deviation is calculated and categorized, the corresponding response measures will be automatically triggered. If the deviation is determined... Exceeding the preset positive deviation If the coating speed is automatically slowed down and the coating process time is moderately increased to improve the amount of lithium replenishment; conversely, if the deviation is calculated... In a narrower In between, the system only needs to slightly vary the coating duration to maintain the stability of the coating process; if The value is too low, meaning it has reached the preset deviation in the negative direction. When the coating speed is reduced, the system accelerates the coating process and reduces excess lithium content by correspondingly shortening the coating time.

[0028] Throughout the coating process, the actual performance of the coating is repeatedly monitored and evaluated using the above process, and parameters are adjusted in a timely manner according to the actual situation to ensure that the lithium replenishment accuracy reaches the optimal level. Through this closed-loop dynamic adjustment method, more precise and controllable pre-lithiation treatment is achieved in the battery production stage.

[0029] Reference Figure 4 The process of controlling the coating speed and coating duration includes: S401, if > According to the predefined ratio Slow down the current coating speed Adjusted coating speed ,in ; S402, if ,but If the deviation is within a negligible range, continue coating as planned. remain unchanged. This approach maintains the normal pre-lithiation process while reducing the process complexity and resource consumption caused by unnecessary speed variations, thereby optimizing the overall process efficiency and cost. S403, if According to the predefined ratio Increase the speed, adjust the coating speed ,in The above , The coefficients were obtained through experimental calibration.

[0030] Based on the above description, in order to ensure process precision and reduce the risk of over-lithiation, the pre-calculated ratio is used. Adjust the speed by reducing the coating speed. To achieve compensatory mitigation, in this adjustment, A pre-defined positive coefficient, not exceeding 1, is used to ensure that the speed is not too slow and affects the overall coating process efficiency. It is obtained through calibration in experiments to ensure consistency in process and battery performance.

[0031] When monitored Below the predefined deviation limit This indicates that the accumulated amount is lower than the preset value, which may affect the total amount of pre-lithiation. In order to make up for the deviation in the lithiation process in time, it is necessary to quickly correct it by increasing the coating speed. Therefore, a predefined adjustment ratio is used. This is also a coefficient determined in a laboratory environment; based on this parameter, the coating rate is increased to compensate for insufficient lithium ions. And through actual testing, it has been verified that the coating rate adjustment can be effective. This real-time adjustment method can ensure that the required lithium ion is accurately measured during the battery pre-lithiation process, thereby improving production consistency and the performance stability of the finished battery.

[0032] Reference Figure 5 The adjustment of the corresponding coating action when determining whether the deviation exceeds the allowable deviation value includes: S501, when If necessary, pause the coating process, reduce the discharge level to the preset low discharge point, and then restart the coating process. in, The maximum permissible positive deviation is set at 0.5%. When the actual capacity difference exceeds the maximum permissible positive deviation, the system pauses the coating process and adjusts the discharge amount of the lithium-ion battery negative electrode to a lower set value before restarting the coating process. This process avoids the adverse effects of accumulated errors on the coating quality. S502. During the coating process, continuously monitor the coating status and record the deviation change curve. Determine whether emergency coating correction is needed based on the inflection point on the curve. The system can identify abnormal changes in the deviation curve according to preset rules and determine whether parameter calibration or more precise manual adjustment should be performed immediately. S503, when And it has been maintained During a continuous cycle, the equipment can be considered to be operating stably. Therefore, there is no need to adjust the coating speed or other key parameters. Continue coating under the current operating conditions until the expected target coating thickness is reached. Maintain the existing parameters and continue coating until the predetermined coating thickness is achieved. ; in, This indicates the minimum permissible negative deviation of lithium content. This indicates the minimum permissible positive deviation of lithium content. This represents the minimum number of measurement cycles required to achieve a steady state. S504. If the above system stability conditions are not met, repeat the above dynamic deviation adjustment process to ensure that the discharge accuracy reaches the predetermined standard.

[0033] These steps effectively control energy deviation during the coating process, achieving precision and efficiency in the pre-lithiation process. For example, if the goal is to uniformly deposit a layer of lithium metal onto the electrode surface to compensate for energy reduction caused by the loss of active materials during cycle life, the above process can help us dynamically adjust the amount of lithium metal coating to maintain a high capacity retention rate and extend the overall service life.

[0034] Reference Figure 6 In step S104, the high-temperature annealing process is as follows: S601, The temperature reaches the target annealing temperature by using a preset heating slope. ; S602, standby temperature a period of time To improve structural uniformity, infrared detection technology is used to ensure the absence of abnormalities. At this stage, advanced monitoring methods are introduced, such as non-contact far-infrared thermal imagers, to monitor for any unwanted chemical reactions or temperature gradient changes inside the lithium battery, preventing process defects caused by overheating. Assuming this isothermal holding period is 1.5 hours, continuous monitoring of the temperature of all parts of the furnace exterior is necessary during this period to maintain a balanced and stable temperature and avoid the formation of hot spots. S603, Based on the temperature-resistance relationship: Determine whether a rapid cooling procedure is necessary to reduce harmful crystallization; S604. Slowly lower the furnace temperature until it is below the target annealing cooling temperature and complete the annealing process.

[0035] By controlling the heat treatment equipment to gradually increase the temperature according to the preset heating slope, the temperature rise in the furnace environment is stable and controllable, and the temperature can accurately reach the predetermined target annealing temperature within a predetermined time. For example, in a specific lithium battery manufacturing environment, it can be set to increase by 5°C per minute until the system reads a stable temperature display value of 400°C as the constant temperature stage.

[0036] In the above process, when the monitored data trend indicates that it is necessary to initiate a protective forced cooling step to suppress the trend that may adversely affect the crystal structure, the rapid cooling program is initiated after the isothermal annealing stage is completed. If the current resistance level is confirmed to be higher than the expected threshold by detection, the fan-assisted cooling measure can be activated.

[0037] To reduce residual stress and ensure the integrity of the battery structure, the overall temperature of the furnace is gradually lowered until it is below the temperature required for subsequent processes to complete the entire pre-lithiation process. For example, the system temperature is restored to room temperature or below 100°C at a rate of about 2°C / min to achieve a good transition effect.

[0038] The combined effect of the above steps can effectively improve the crystallization quality of materials, thereby enhancing the overall technical specifications of lithium-ion battery products.

[0039] In step S204, the allowable range is the target interval. ,in, This refers to the permissible error threshold for the pre-lithiated lithium content. This represents the maximum permissible deviation of the measured lithium content from the target value. This refers to the maximum permissible deviation of the measured lithium content from the target value.

[0040] Specifically, the first step is to determine the preset target value for discharge. This target value is typically determined based on the desired pre-lithiation level and the specific requirements of subsequent battery performance. The optimal value is then obtained through process design and battery performance simulation. For example, assuming calculations or experiments show that the optimal discharge value for a certain pre-lithiation application is 0.1 Ah, then... It is set to 0.1Ah to ensure that the coated battery can achieve the expected pre-lithiation effect.

[0041] In the actual implementation process, the instantaneous and cumulative discharge amounts during the coating process are measured. This usually requires the use of an ammeter or coulomb meter with real-time data acquisition capabilities and high accuracy to monitor and ensure the accuracy of the measured values; for example, suppose that in an experimental operation, it is found that the actual cumulative discharge amount during a certain period of the coating process is 0.085Ah.

[0042] Next, by comparing the target value Compared with measured values The difference between That is, calculate the deviation To assess whether the actual effect of pre-lithiation matches the expectations and to quantify the degree of deviation between the two; If we use the data from the previous example, the deviation is calculated as 0.1Ah - 0.085Ah = 0.015Ah. Based on the calculated deviation value, it can be determined that the discharge amount is insufficient to meet the preset standard, and the coating operation still needs to be continued to meet the target discharge amount requirement.

[0043] Finally, based on the calculated difference And its positive or negative, take measures to adjust the operating parameters of the pre-lithiated material coating, such as time and rate, until the deviation falls within the preset target range. So far, in the actual operating environment It is a very small positive number or equal to zero, representing the minimum acceptable deviation limit to ensure precise control of the final coating effect to meet the pre-lithiation requirements.

[0044] In summary, in the lithium-ion pre-lithiation process based on electrochemical principles, by comparing and analyzing the target value and the real-time measured value, and making timely corrections based on the deviation, the consistency of the pre-lithiation effect and the controllability of its performance in battery pack production can be significantly improved.

[0045] Reference Figure 7 In calculating the deviation after, like Then reduce the duration. ; like Then increase the duration. When the duration Reaching maximum allowable duration If so, no additional operation will be performed; Recording deviation To assess the accuracy of the discharge quantity and correct the coating process in real time accordingly; exist and Under the premise that the target range has been accurately adjusted, it is determined that the target range has been accurately adjusted.

[0046] This invention proposes an improved lithium battery pre-lithiation method, which is based on the calculated deviation between the actual injected capacity and the target capacity. To make real-time adjustments; specifically, if the calculated Exceeding a predefined threshold The system will automatically shorten the preset coating duration. This dynamic control ensures that the amount of pre-lithiated charge injected into the lithium battery during the coating process can more accurately approach the ideal value designed. Furthermore, deviations were monitored during the pre-lithiation process. In the case of, if This indicates that the amount of lithium ions injected during the coating process basically meets the expected target, and at this time, it is not necessary to monitor the coating time. Make changes, but this deviation should be recorded and used as feedback for future use. If the coating time is significantly lower than the preset allowable threshold, the coating time will be appropriately increased. To improve capacity utilization under discharge current, it's important to note that this time adjustment has an upper limit. It has reached its maximum allowable length, that is, reached or exceeded the theoretical upper limit. At that point, it will be impossible to extend the battery life accordingly, in order to prevent the battery structure from becoming less stable due to overcharging and discharging.

[0047] After each adjustment of the duration, a new deviation is calculated, and the coating time and coating conditions are adjusted again based on this, thus achieving dynamic adjustment. At the same time, the deviation value after each iteration is recorded to analyze the accuracy of pre-lithiation and to fine-tune in real time based on the recorded data to further reduce potential cumulative errors in subsequent processes. When finally achieving the coating effect, the deviation must be less than or equal to the set threshold, and its absolute value must be within 5 times the set deviation range to be considered to have reached the ideal target coating state.

[0048] The pre-lithiation method implemented through the above steps can effectively improve the reliability of the pre-charge process and the consistency of battery product quality. Furthermore, it can flexibly handle various unexpected variables in actual production processes while maintaining stable performance. For example, in a lithium battery assembly line, when inaccurate lithium injection is found in a certain process, i.e. If the lithium ion deposition is too high, the algorithm will shorten the coating cycle on the corresponding battery electrode in real time, thereby reducing resource waste caused by excessive charging; conversely, if the lithium ion deposition is found to be low, such as... If the deviation is much smaller than expected, the coating cycle can be increased as needed until the established standard is met. The whole process not only avoids a series of errors caused by manual adjustment, but also greatly improves manufacturing efficiency and economic benefits.

[0049] Reference Figure 8 In recording deviation This includes: By recording deviations at different cycles during the pre-lithiation process To conduct an accuracy assessment, specifically, if in In this measurement, at least one The measurement satisfies This confirms that the precise adjustment has been completed. and The number is even; this condition ensures that in a sufficient number of tests, most of the deviations are close to zero. like If the discharge process is considered unstable, the entire pre-lithiation process needs to be paused in order to conduct a comprehensive inspection and adjustment of key process parameters such as coating, so as to ensure that the system operates in a stable state. exist The results of three consecutive measurements fell on If the error is within the specified range, it indicates that stability and repeatability have been achieved at the current error threshold. Therefore, the error threshold standard is lowered to a lower level for more rigorous testing. Simultaneously, the nth iteration of the calculation is restarted to confirm whether the optimization effect still meets the high standard requirements, i.e., the error threshold is further lowered. And start measuring again; exist fall into The fact that the entire system was accurately controlled after five consecutive cycles following the initial phase further proves that the precise control of the entire system has reached the expected target after the series of minor adjustments and error reduction steps mentioned above. Therefore, it is determined that the final pre-lithiation amount has been precisely adjusted, and the high-temperature annealing step is continued, thus ending the entire process of lithium battery pre-lithiation.

[0050] Reference Figure 9 Calculate the actual discharge amount according to the following steps: S1001, Set an actual discharge efficiency If η is greater than or equal to the set discharge efficiency threshold If the pre-lithiation process can effectively control the amount of pre-lithiation, the discharge quantity meets the conditions and the process continues. S1002, if ,but If the discharge efficiency is low, it is determined that it still meets the deviation requirements within the precise control range of pre-lithiation adjustment. S1003, such as ,and If this is the case, there is an internal abnormality in the battery, and repair measures need to be taken. S1004, if fall into Scope, and If the value is 0%, it is considered a serious imbalance. The pre-lithiation process should be stopped immediately and a system diagnostic should be performed. It is particularly important to emphasize that when fall into Scope, and When the 0% threshold is reached, it indicates that the current pre-lithiation balance has been disrupted to an extremely serious degree. In order to ensure the overall coating process and the safety and reliability of the lithium battery, the process should be terminated immediately, and a rigorous diagnostic analysis should be performed on the entire system to identify the specific problems and ensure that the battery product achieves the expected design performance and meets the safety production requirements.

[0051] Assuming a preset ideal minimum discharge efficiency value =85%, permissible maximum discharge difference If the value is ±0.1Ah, then according to the above characteristic steps, after the coating process is completed and the discharge efficiency and discharge quantity error are calculated through the aforementioned steps, if the actual discharge rate η is 85% or higher, and the absolute difference value of the discharge quantity is... Less than or equal to 0.025Ah, which means that the actual efficiency is near the upper limit of the allowable deviation but still meets the specification requirements; When the actual detection result of η is 60%, at the same time The value falls within the range of [−0.03,+0.03]Ah. Although the value of η is low, it is still within the tolerable range. If the test shows that η drops to 30%, while the actual discharge quantity is incorrect... If the threshold is exceeded by +0.2Ah, the internal battery status should be checked for any malfunctions to prevent potential dangerous situations. Finally, assuming that η decreases to only 20%, the actual discharge quantity deviates... When the battery capacity reaches +2.5Ah or higher, the current battery process is considered to be in an extremely unstable stage, and may even face a safety crisis. In this case, the coating process should be stopped in time, the entire equipment should be thoroughly diagnosed to eliminate potential hazards, and the normal operation of subsequent processes should be ensured.

[0052] The deviation The measurements include: Test and record the charge accumulation increment corresponding to the coating process every 5 minutes. ; Algorithm calculation bias , in, This represents the amount of charge generated under ideal conditions corresponding to the complete reaction of the pre-lithiated material. This is the integral value of the actual measured cumulative discharge. once The adjustment process should be stopped immediately. If all 5 tests meet the conditions of the previous step, or if the cumulative testing time reaches 30 minutes and remains stable each time, then the adjustment is considered complete and the pre-lithiation amount has been precisely controlled.

[0053] The charge increment generated every 5 minutes during the coating process This is to monitor the current accumulation during the entire pre-lithiation process. This means that data will be collected in real time to quantify the specific current generated by the reduction reaction on the surface of the coated material, and these transient data will be stored for later use. For example, a dedicated battery management system can be set up during the coating process to continuously sample and record the actual current increment generated during the coating process every 5 minutes, and these data will be labeled and stored one by one.

[0054] Continuous recording within a specific time period Summing and comparing the total pre-lithiation charge under ideal conditions Determine the deviation between the two The specific calculation form is expressed as , here It is the ideal total charge calculated theoretically, representing the total amount of electricity required to achieve 100% pre-lithiation of the material; while the actual charge increment... The accumulated value over time reflects the actual total charge accumulation during the coating process. This algorithm can be embedded in a dedicated control program for continuous comparison and analysis in the background, and output the result in real time. The values ​​are provided to the operator for reference.

[0055] In acquiring Based on this, through discriminant To confirm whether the current state has achieved the desired adjustment effect; here, It is a pre-set error threshold, if If the value is less than the preset threshold, the adjustment operation stops. This indicates that the actual response of the system is very close to the theoretically expected pre-lithiation level, which can avoid the risk of overcharging or undercharging. The stop function can be executed by setting the discrimination conditions in the control system, thereby effectively controlling the magnitude of the deviation to ensure the consistency and safety performance of the battery.

[0056] The above-mentioned determination process should be repeated at least 5 times, with continuous observation for at least 30 minutes each time. If the results are consistent each time... Changes within a preset threshold Once the process is complete, the process is considered finished. The purpose of this repeated testing is to further ensure the reliability and accuracy of the pre-lithiation operation. Once all the above criteria are met, it can be confirmed that the lithium-ion compensation of the coated material is complete. This step can display a confirmation message on the control system interface to the engineers, indicating that they have achieved precise control of pre-lithiation and can safely proceed to the next process flow.

[0057] In actual operation, when this device is used, the workflow of a lithium battery pre-lithiation method begins in the preparation stage. First, in a vacuum environment specifically designed to prevent contamination from air and other impurities, high-performance pulverizing and mixing equipment is used to finely grind and uniformly mix the lithium-containing material, forming a highly dispersed, appropriately sized, and chemically active pre-lithiated material. To ensure the effectiveness and safety of this process, this step must be strictly maintained under high purity conditions to avoid any potential sources of contamination affecting the quality of subsequent processing and the final product performance. Next, after obtaining the required standard material, the system uses a precision coating machine equipped with an advanced inert gas control system to tightly and uniformly coat it onto the prepared and pre-cleaned negative electrode material. By continuously supplying appropriate amounts of inactive components such as nitrogen and argon, a stable and controllable working chamber that completely isolates the possibility of external gas exchange is constructed, ensuring good isolation conditions throughout the coating process and avoiding any adverse interference factors such as moisture or oxygen that could damage the material. Subsequently... A novel pulsed heating control mode is constructed by combining a precision current regulator and real-time temperature sensing technology. This method, with millisecond-level reaction time and nanometer-level precision, quantitatively releases electrons from the negative electrode sheet coated with pre-lithiated material. During this process, the system can flexibly adjust the number of electrons generated in each unit area according to a pre-set program to achieve perfect control of the required precise dosage level, effectively eliminating the common problems of overshoot or short supply, thus significantly improving the consistency and reliability of the overall product while reducing energy consumption. The final step involves continuous curing using a high-temperature treatment facility within a specific temperature range. This not only enhances the overall structural stability but, more importantly, accelerates the removal of residual harmful small molecule liquids such as organic solvents, helping to purify the surface and reduce the probability of abnormal risks during normal use. After the entire process is completed, a new type of pre-lithiated lithium battery product with excellent quality and better cycle stability and energy conversion efficiency is obtained.

[0058] 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 pre-lithiation of lithium batteries, characterized in that, Includes the following steps: S101. Prepare lithium-containing materials in a vacuum environment and grind and mix them to obtain pre-lithiated materials; S102. Apply pre-lithiated material to lithium battery anode material using inert gas protection technology; S103. Based on the electrochemical lithium intercalation theory, the discharge amount during the coating process is controlled to precisely adjust the pre-lithiation amount; S104. Perform high-temperature annealing to enhance the performance of the lithium battery and remove any organic solvent residues that may have been introduced during the coating process.

2. The lithium battery pre-lithiation method according to claim 1, characterized in that, In step S102, the step of precisely adjusting the pre-lithiation amount includes: S201. Determine the target value of the preset discharge quantity. ; S202. Measure the discharge amount during the actual coating process. ; S203, Calculation of Deviation ; S204. Adjust the duration of pre-lithiation material coating based on the calculated deviation. Until It falls within the permissible range.

3. The lithium battery pre-lithiation method according to claim 2, characterized in that, In step S204, adjusting the duration of the pre-lithiation material coating specifically includes the following steps: S301, if Greater than the preset positive deviation This reduces the coating speed and extends the duration; S302, if Within the set small deviation range If so, maintain the current coating state and fine-tune the duration; S303, if Less than the preset negative deviation This increases the coating speed and shortens the duration; S304. Repeat the above steps to adjust the pre-lithiation material coating in real time with precision.

4. The lithium battery pre-lithiation method according to claim 3, characterized in that, The process of controlling coating speed and coating duration includes: S401, if > According to the predefined ratio Slow down the current coating speed Adjusted coating speed Q, where ; S402, if ,but If the deviation is within a negligible range, continue coating as planned. remain unchanged. Remain unchanged; S403, if According to the predefined ratio Increase the speed, adjust the coating speed ,in The above , The coefficients were obtained through experimental calibration.

5. A lithium battery pre-lithiation method according to claim 4, characterized in that, Adjustments to the corresponding coating action to determine whether the deviation exceeds the allowable deviation value include: S501, when If necessary, pause the coating process, reduce the discharge level to the preset low discharge point, and then restart the coating process. in, This is the maximum permissible positive deviation; S502. During the coating process, continuously monitor the coating status and record the deviation change curve. Determine whether emergency coating correction is needed based on the inflection point on the curve. S503, when And it has been maintained If the system is considered stable after one consecutive cycle, the coating will continue with the existing parameters until the predetermined coating thickness is achieved. ; in, This indicates the minimum permissible negative deviation of lithium content. This indicates the minimum permissible positive deviation of lithium content. This represents the minimum number of measurement cycles required to achieve a steady state. S504. If the above system stability conditions are not met, repeat the above dynamic deviation adjustment process to ensure that the discharge accuracy reaches the predetermined standard.

6. The lithium battery pre-lithiation method according to claim 1, characterized in that, In step S104, the high-temperature annealing process is as follows: S601, The temperature reaches the target annealing temperature by using a preset heating slope. ; S602, standby temperature a period of time To improve structural uniformity, infrared detection technology is used to ensure that there are no abnormalities. S603, Based on the temperature-resistance relationship: Determine whether a rapid cooling procedure is necessary to reduce harmful crystallization; S604. Slowly lower the furnace temperature until it is below the target annealing cooling temperature and complete the annealing process.

7. A lithium battery pre-lithiation method according to claim 4, characterized in that, In step S204, the allowable range is the target interval. ,in, This refers to the permissible error threshold for the pre-lithiated lithium content. This represents the maximum permissible deviation of the measured lithium content from the target value. This refers to the maximum permissible deviation of the measured lithium content from the target value.

8. A lithium battery pre-lithiation method according to claim 7, characterized in that, In calculating deviation after, like Then reduce the duration. ; like Then increase the duration. When the duration Reaching maximum allowable duration If so, no additional operation will be performed; Recording deviation To assess the accuracy of the discharge quantity and correct the coating process in real time accordingly; exist and Under the premise that the target range has been accurately adjusted, it is determined that the target range has been accurately adjusted.

9. A lithium battery pre-lithiation method according to claim 8, characterized in that, Recording deviations The following includes: If in In this measurement, at least one The measurement satisfies This confirms that the precise adjustment has been completed. and It is an even number; like If the discharge process is unstable, it is necessary to pause and check the coating parameter settings. exist The results of three consecutive measurements fell on When within the range, further reduce the error threshold. And start measuring again; exist fall into If the temperature falls within the target range for five consecutive cycles after the initial phase, it is determined that the final pre-lithiation amount has been precisely adjusted, and the high-temperature annealing step continues.

10. A lithium battery pre-lithiation method according to claim 9, characterized in that, Calculate the actual discharge amount using the following steps: S1001, Set an actual discharge efficiency If η is greater than or equal to the set discharge efficiency threshold If the pre-lithiation process can effectively control the amount of pre-lithiation, the discharge quantity meets the conditions and the process continues. S1002, if ,but If the discharge efficiency is low, it is determined that it still meets the deviation requirements within the precise control range of pre-lithiation adjustment. S1003, such as ,and If this is the case, there is an internal abnormality in the battery, and repair measures need to be taken. S1004, if fall into Scope, and If the ratio reaches 70%, it is considered a serious imbalance, and the pre-lithiation process should be stopped immediately and a system diagnostic should be performed. The deviation The measurements include: Test and record the charge accumulation increment corresponding to the coating process every 5 minutes. ; Algorithm calculation bias , in, This represents the amount of charge generated under ideal conditions corresponding to the complete reaction of the pre-lithiated material. This is the integral value of the actual measured cumulative discharge. once The adjustment process should be stopped immediately. If all 5 tests meet the conditions of the previous step, or if the cumulative testing time reaches 30 minutes and remains stable each time, then the adjustment is considered complete and the pre-lithiation amount has been precisely controlled.

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