Preparation method of secondary battery, secondary battery, energy storage system and electric device

Abstract

The application belongs to the technical field of energy storage, and provides a preparation method of a secondary battery, a secondary battery, an energy storage system and a power utilization device. The method comprises: performing an electrode tab baking process on an electrode tab; determining, according to a battery positive electrode specific surface and / or battery coating lower roll moisture, whether to perform an electrode tab vacuum rolling process and a roll core vacuum hot pressing process after the electrode tab baking process and before a cell baking process; the electrode tab vacuum rolling process is characterized by vacuumizing first and then supplementing dry gas during the electrode tab rolling process; the roll core vacuum hot pressing process is characterized by vacuumizing first and then supplementing dry gas during the roll core hot pressing process; and performing the cell baking process, wherein the initial cell is baked for a corresponding time length based on the moisture content of the cell before the cell baking process in the step of the cell baking process. The problem of low control precision of the moisture content of the cell in the preparation process of the secondary battery is solved.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and more specifically, to a method for preparing a secondary battery, a secondary battery, an energy storage system, and an electrical device. Background Technology

[0002] Batteries are being used in a wider range of fields, and these multi-field applications are constantly raising the requirements for battery performance. Controlling moisture content in battery cells is a key aspect of the battery manufacturing process.

[0003] In battery manufacturing, the moisture content of the battery cell directly affects its electrochemical performance and lifespan. Excessive moisture can lead to the degradation of electrode materials, accelerated hydrogen evolution reaction, and electrolyte decomposition, thereby shortening battery life. Furthermore, improper moisture control can increase the battery's internal resistance, reducing its energy density and power output. Current methods for controlling the moisture content of battery cells still have limitations; for example, the precision of moisture control is relatively low. Summary of the Invention

[0004] The main objective of this application is to provide a method for preparing a secondary battery, a secondary battery, an energy storage system, and an electrical device, in order to solve the problem of low precision in controlling the moisture content of the battery cell in the preparation process of secondary batteries in the prior art.

[0005] To achieve the above objectives, according to one aspect of this application, a method for preparing a secondary battery is provided, comprising: performing an electrode baking process on battery electrodes, wherein the electrode baking process involves baking the battery electrodes obtained after a coating process at a preset temperature; determining, based on the battery positive electrode specific surface area and / or the battery coating under-coat moisture content, whether to perform an electrode vacuum rolling process and a core vacuum hot pressing process after the electrode baking process and before the cell baking process, wherein the battery positive electrode specific surface area refers to the specific surface area of ​​the battery positive electrode, and the battery coating under-coat moisture content refers to the amount of moisture after the electrode baking process. The residual moisture content of the battery electrode during winding; the electrode vacuum rolling process characterized by first evacuating the vacuum and then replenishing the drying gas during the electrode rolling process; the core vacuum hot pressing process characterized by first evacuating the vacuum and then replenishing the drying gas during the core hot pressing process; wherein the temperature range of the temperature parameters of the rolling equipment in the electrode rolling process is different from the temperature range of the hot pressing equipment in the core hot pressing process; the cell baking process is performed, wherein the initial cell is baked for a corresponding duration based on the cell moisture content before baking.

[0006] Further, determining whether to perform electrode vacuum rolling and core vacuum hot pressing processes after the electrode baking process and before the cell baking process, based on the battery positive electrode specificity and / or the moisture content of the battery coating roll, includes: if the battery positive electrode specificity is within a first preset specificity range, and / or the moisture content of the battery coating roll is within a first preset moisture range, determining that the electrode vacuum rolling and core vacuum hot pressing processes are not performed after the electrode baking process and before the cell baking process, but are performed instead; if the battery positive electrode specificity is within a second preset specificity range, and / or the moisture content of the battery coating roll is within a second preset moisture range, determining that the electrode baking process is performed after the cell baking process. Previously, the electrode vacuum rolling process was not performed, but the core vacuum hot pressing process was performed, along with the electrode rolling process. When the battery positive electrode specific gravity is within a third preset specific gravity range, and / or the moisture content of the battery coating roll is within a third preset moisture content range, it is determined that the electrode vacuum rolling process and the core vacuum hot pressing process should be performed after the electrode baking process and before the cell baking process. Wherein, the maximum value of the first preset specific gravity range is less than the minimum value of the second preset specific gravity range, and the maximum value of the second preset specific gravity range is less than the minimum value of the third preset specific gravity range; the maximum value of the first preset moisture content range is less than the minimum value of the second preset moisture content range, and the maximum value of the second preset moisture content range is less than the minimum value of the third preset specific gravity range.

[0007] Furthermore, the first preset moisture range is ≤600ppm, and the first preset specific surface area range is ≤0.5m. 2 / g; the second preset moisture range is 601–700 ppm, and the second preset specific surface area range is 0.6–1.0 m. 2 / g; the third preset moisture range is 701–800 ppm, and the third preset specific surface area range is 1.1–1.5 m. 2 / g.

[0008] Furthermore, the steps of the electrode vacuum rolling process include: a vacuuming step: evacuating the cavity where the rolling mill is located; a drying gas replenishment step: replenishing the cavity with drying gas after the vacuuming process; and a rolling step: unfolding the battery electrode after the drying gas replenishment step and then performing the rolling process.

[0009] Furthermore, the steps of the core vacuum hot pressing process include: a vacuuming step: evacuating the cavity where the hot press is located; a drying gas replenishment step: replenishing the cavity with the drying gas after the vacuuming process; and a hot pressing step: hot pressing the battery core after the drying gas replenishment step.

[0010] Furthermore, after performing the cell baking process, the method further includes: when the moisture content of the initial cell meets the requirements, performing the cumulative duration of the cell baking process; when the cumulative duration of the cell baking process exceeds a preset duration, adjusting the parameters of the electrode vacuum rolling process and / or the parameters of the core vacuum hot pressing process, so that the duration of the cell baking process for cells of the same specifications in subsequent preparation processes is less than or equal to the preset duration, wherein the preset duration is positively correlated with the specific gravity of the battery positive electrode and positively correlated with the moisture content of the battery coating roll.

[0011] Furthermore, after performing the electrode vacuum rolling process and before performing the core vacuum hot pressing process, the method further includes: winding the separator, the battery positive electrode sheet after the electrode baking process, and the battery negative electrode sheet and placing them into the housing to form a battery core, wherein the separator is located between the battery positive electrode sheet and the battery negative electrode sheet.

[0012] Furthermore, an electrode baking process is performed on the battery electrode sheets. The electrode baking process involves baking the battery electrode sheets obtained after the coating process at a preset temperature. This includes: baking the positive electrode sheet obtained after the coating process at a first preset temperature; and baking the negative electrode sheet obtained after the coating process at a second preset temperature, wherein the first preset temperature is greater than the second preset temperature.

[0013] Furthermore, the first preset temperature ranges from 165 to 175°C, and the second preset temperature ranges from 85 to 95°C.

[0014] Furthermore, the temperature parameters in the cell baking process are in the range of 90–100°C.

[0015] Furthermore, in the electrode vacuum rolling process, the pressure value of the pressure parameter ranges from 6.5 to 8.5t, the temperature value ranges from 80 to 120℃, and the vacuum pressure value ranges from -85 to -75KPa.

[0016] Furthermore, the pressure parameters of the vacuum hot pressing process for the core are in the range of 5.5 to 8.5t, the temperature parameters are in the range of 90 to 100℃, and the vacuum pressure is in the range of -85 to -75KPa.

[0017] According to another aspect of this application, a secondary battery is provided, which is prepared using any of the methods described above for preparing a secondary battery.

[0018] According to another aspect of this application, an energy storage system is provided, comprising: at least one of the aforementioned secondary batteries.

[0019] According to another aspect of this application, an electrical device is provided, comprising: at least one of the aforementioned secondary batteries or the aforementioned energy storage system.

[0020] The beneficial effects of this application are as follows: the electrode rolling process in the prior art is replaced by the electrode vacuum rolling process, and the core hot pressing process is replaced by the core vacuum hot pressing process. Moisture is removed by vacuuming and filling with dry air, which improves the control accuracy of moisture content. Furthermore, the baking time of the subsequent cell baking process can be greatly reduced, solving the problem of low control accuracy of cell moisture content in the prior art secondary battery manufacturing process. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0022] Figure 1 A schematic flowchart of a method for preparing a secondary battery according to an embodiment of this application is shown;

[0023] Figure 2 The diagram illustrates a process for determining whether to perform electrode vacuum rolling and core vacuum hot pressing processes in a method for preparing a secondary battery according to an embodiment of this application.

[0024] Figure 3 A flowchart illustrating a specific method for preparing a secondary battery according to an embodiment of this application is shown. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0028] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0029] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0030] In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0031] In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists, A and B exist simultaneously, and B exists.

[0032] As described in the background section, excessive moisture content in battery cells can lead to electrode material degradation, accelerated hydrogen evolution reaction, and electrolyte decomposition, thereby shortening battery life. Furthermore, improper moisture control can increase the battery's internal resistance, reducing its energy density and power output. To address the problem of low precision in controlling battery cell moisture content during the fabrication process of rechargeable batteries in the prior art, embodiments of this application provide a method for fabricating a rechargeable battery, a rechargeable battery, an energy storage system, and an electrical device.

[0033] 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.

[0034] Figure 1 This is a schematic flowchart illustrating a method for preparing a secondary battery according to an embodiment of this application. Figure 1 As shown, the method includes the following steps:

[0035] Step S101: Perform an electrode baking process on the battery electrode sheet. In the above electrode baking process, a preset temperature is used to bake the battery electrode sheet obtained after the coating process.

[0036] Specifically, in the early stages of battery manufacturing, active materials are coated onto current collectors (usually aluminum or copper foil) to form positive or negative electrode slurries, which are then dried to remove the solvent; this process is called coating. The coated electrodes will contain some moisture. The electrode baking process sets a specific temperature range, or preset temperature, to remove the moisture from the electrode without damaging its physical properties and electrochemical performance. The setting of the preset temperature depends specifically on the properties of the active materials and the structure of the electrode.

[0037] Electrode baking refers to the process of removing residual moisture from electrodes by heating them under specific temperature and time conditions. This process is usually carried out in an oven or specialized baking equipment to ensure that the moisture content in the electrodes does not negatively affect battery performance in subsequent battery manufacturing steps.

[0038] A baking process for battery electrodes, using a preset temperature to bake the coated electrodes, effectively and precisely controls the moisture content of the electrodes. By setting an appropriate baking temperature, residual moisture and solvents from the coating process can be efficiently removed without damaging the electrode material structure and performance. This ensures the stability and consistency of the battery cell in subsequent manufacturing processes, improving the battery's electrochemical performance and safety. Furthermore, baking at a preset temperature optimizes energy consumption, reduces unnecessary energy waste, and achieves energy conservation and emission reduction goals in the production process.

[0039] Step S102: Determine whether to perform electrode vacuum rolling process and core vacuum hot pressing process after the above electrode baking process and before the cell baking process based on the battery positive electrode specific surface area and / or battery coating under-winding moisture content. The above battery positive electrode specific surface area refers to the specific surface area of ​​the battery positive electrode. The above battery coating under-winding moisture content refers to the moisture content remaining in the battery electrode when it is wound up after the above electrode baking process. The above electrode vacuum rolling process indicates that a vacuum is first drawn and then dry gas is added during the electrode rolling process. The above core vacuum hot pressing process indicates that a vacuum is first drawn and then dry gas is added during the core hot pressing process.

[0040] Wherein, the temperature of the rolling equipment in the above-mentioned electrode rolling process is the temperature of the roller surface where the electrode contacts the roller; the temperature of the hot pressing equipment in the above-mentioned core hot pressing process is the temperature of the hot pressing machine surface where the core contacts the hot pressing machine.

[0041] Specifically, the decision to add an additional vacuum drying step is made based on the specific surface area of ​​the battery's positive electrode and / or the moisture content of the battery coating roll. The specific surface area of ​​the positive electrode refers to the area of ​​the battery's positive electrode sheet, reflecting the particle size and structural looseness of the material. A larger specific surface area means a larger contact area between the material and the environment, resulting in stronger water absorption. If the specific surface area of ​​the battery's positive electrode is small and the moisture content after baking is low, it indicates that the material itself has weak water absorption, and baking is sufficient to control the moisture, eliminating the need for an additional vacuum drying step. If the specific surface area of ​​the battery's positive electrode is large or the moisture content after baking is high, it is necessary to further remove moisture from the electrode sheets and core through a vacuum rolling process and / or a vacuum hot pressing process for the core to achieve stricter moisture control standards.

[0042] The electrode vacuum rolling process involves evacuating the electrode before traditional electrode rolling and then adding dry gas. The purpose is to accelerate the evaporation of residual moisture through the vacuum environment and to fill the pores with dry gas to prevent moisture re-condensation, thereby effectively reducing the internal moisture content of the electrode. The core vacuum hot pressing process is for battery structures that have already been wound into cores. This process also involves evacuating the electrode, adding dry gas, and then hot pressing at a specific temperature. The aim is to remove moisture from the inside of the core, especially the interface moisture between the electrode and the separator, thus reducing the difficulty and time required for cell baking.

[0043] The temperature parameter ranges of the equipment in the electrode rolling process and the core hot pressing process are different because the material composition and structural state of the electrode and the core are different, requiring different temperature conditions to achieve the best drying effect while avoiding material damage.

[0044] By evaluating the specific surface area of ​​the battery cathode (specific surface area of ​​the battery cathode) and / or the moisture content of the electrode after coating and uncoating (moisture content of the battery coating and uncoating), a strategy for dynamically adjusting the process flow is proposed. This strategy not only allows for flexible adjustment of the drying process based on the characteristics of the cathode material to ensure that the final moisture content of the battery cell meets strict standards, but also reduces energy consumption and costs and improves production efficiency by reducing unnecessary heat treatment steps.

[0045] Step S103: Perform the above-mentioned cell baking process, wherein the initial cell is baked for a corresponding duration based on the cell moisture content before baking.

[0046] Specifically, the cell baking process is designed to further remove moisture from the cell, ensuring that the moisture content of the cell meets strict standards before electrolyte injection, thereby improving battery performance and safety. The baking time can be determined based on the cell's moisture content before baking—that is, the amount of water in the cell after assembly but before baking.

[0047] The moisture content of the battery cell directly affects the baking time required. Lower moisture content allows for shorter baking times, as less moisture means less time and energy is needed for evaporation. Conversely, higher moisture content necessitates longer baking times to ensure sufficient evaporation and prevent moisture from affecting battery performance during subsequent manufacturing processes. The key to this strategy is accurately measuring the moisture content of the cell before baking to precisely control the baking time, ensuring neither energy is wasted nor battery quality is compromised.

[0048] Testing the moisture content of battery cells before baking is a crucial step in ensuring quality moisture control during secondary battery manufacturing. Below are several common methods for measuring cell moisture content, and how to develop corresponding baking strategies based on these measurements:

[0049] Karl Fischer Titration: This is the most commonly used technique for measuring moisture content, suitable for determining the moisture in solid, liquid, and gaseous samples. During testing, the battery cell sample is placed in a sealed container, and then a Karl Fischer reagent is used to chemically react with the moisture in the sample. The moisture content is calculated based on the amount of reagent consumed in the titration. The measurement result is expressed in parts per million (ppm) and is typically used for assessing the moisture content of the battery cell before baking.

[0050] Microwave Moisture Testing: This is a rapid, non-contact method for measuring moisture content. It involves sending microwaves to a battery cell sample and determining its moisture content based on the sample's absorption or reflection of the microwaves. This method is suitable for rapid screening of large batches of battery cells and can provide immediate moisture content information.

[0051] Infrared moisture determination: This method is based on the principle that moisture absorbs infrared light of specific wavelengths. During testing, the battery cell sample is exposed to infrared radiation, and the moisture content is calculated based on the degree of infrared absorption. This method is fast and accurate, making it suitable for real-time monitoring on production lines.

[0052] Resistivity method: Based on the principle of the effect of moisture on the resistivity of battery cell materials, this method estimates the moisture content by measuring the change in the resistivity of the battery cell. This method is suitable for continuous monitoring, but its accuracy may not be as high as the Karl Fischer method.

[0053] After the test is completed and the moisture content of the battery cell before baking is obtained, the baking time is determined according to the following principles:

[0054] If the test results show that the moisture content of the battery cell is below the preset threshold (e.g., 600 ppm), the baking time can be reduced, and in some cases, over-baking can be avoided to prevent negative impacts on the battery cell performance.

[0055] If the moisture content of the battery cell is higher than a preset threshold (e.g., 600 ppm) but lower than another stricter standard (e.g., 800 ppm), a standard or slightly longer baking time should be used to ensure that the moisture is fully removed.

[0056] For battery cells with significantly high moisture content (e.g., exceeding 1000 ppm), the baking time needs to be extended, and a second baking may even be necessary to ensure that the battery cell reaches the ideal dry state before the electrolyte is injected.

[0057] During the cell baking process, the baking time is dynamically adjusted based on the cell's moisture content before baking, significantly enhancing the accuracy and flexibility of moisture management. This allows for ensuring that the cell's moisture content meets standards while avoiding energy waste and potential adverse effects on battery materials caused by over-baking. By precisely matching moisture content with baking time, production costs are optimized, production efficiency is improved, and battery consistency and reliability are ensured, thereby significantly enhancing the battery's electrochemical performance and lifespan.

[0058] By precisely controlling the drying process, the moisture content during battery manufacturing is effectively managed, significantly improving battery performance and production efficiency. An electrode baking process ensures the initial drying of the electrodes after coating. Based on the specific surface area of ​​the positive electrode and the residual moisture after coating and unwinding, the selection of electrode vacuum rolling and core vacuum hot pressing processes is made. These processes, by first vacuuming and then replenishing with drying gas, can specifically reduce moisture in highly absorbent materials or electrodes with high residual moisture, avoiding the need for such intensive drying in all cases and preventing excessive resource consumption. The cell baking process dynamically adjusts the baking time based on the cell's moisture content before baking, ensuring that each batch of cells reaches the ideal drying state and avoiding problems of residual moisture or over-drying. In short, this embodiment replaces the electrode rolling process in the prior art with the electrode vacuum rolling process, and the core hot pressing process with the core vacuum hot pressing process. Moisture is removed by vacuuming and filling with dry air, which improves the control accuracy of moisture content and greatly reduces the baking time of the subsequent cell baking process. This solves the problem of low control accuracy of cell moisture content in the prior art secondary battery manufacturing process.

[0059] In some embodiments, the determination of whether to perform electrode vacuum rolling and core vacuum hot pressing processes after the electrode baking process and before the cell baking process is based on the battery positive electrode specificity table and / or the moisture content of the battery coating roll, such as... Figure 2 As shown, it includes the following steps:

[0060] Step S201: When the battery positive electrode specificity is within the first preset specificity range, and / or the battery coating roll moisture is within the first preset moisture range, it is determined that after the electrode baking process and before the cell baking process, the electrode vacuum rolling process and the core vacuum hot pressing process will not be performed, and the electrode rolling process and the core hot pressing process will be performed.

[0061] Step S202: When the battery positive electrode specificity is within the second preset specificity range, and / or the battery coating roll moisture is within the second preset moisture range, it is determined that after the electrode baking process and before the cell baking process, the electrode vacuum rolling process is not performed, but the core vacuum hot pressing process is performed, and the electrode rolling process is performed.

[0062] Step S203: When the battery positive electrode specificity is within the third preset specificity range, and / or the battery coating roll moisture is within the third preset moisture range, determine that the electrode vacuum rolling process and the roll core vacuum hot pressing process shall be performed after the electrode baking process and before the cell baking process.

[0063] Wherein, the maximum value of the first preset ratio range is less than the minimum value of the second preset ratio range, and the maximum value of the second preset ratio range is less than the minimum value of the third preset ratio range; the maximum value of the first preset moisture range is less than the minimum value of the second preset moisture range, and the maximum value of the second preset moisture range is less than the minimum value of the third preset ratio range.

[0064] Specifically, when the specific surface area of ​​the battery positive electrode is within a first preset specific surface area range, and / or the moisture content of the battery coating roll is within a first preset moisture content range, it means that the specific surface area of ​​the positive electrode material is small, and / or the moisture content after coating roll is already low. Under these conditions, because the material itself has a weak tendency to absorb water, or the residual moisture content is low, no additional vacuum drying process is required, and normal electrode rolling and core hot pressing processes can be directly performed. This simplifies the process and avoids unnecessary drying energy and time consumption.

[0065] When the specific gravity of the battery positive electrode is within the second preset specific gravity range, and / or the moisture content of the battery coating roll is within the second preset moisture content range, it is still insufficient to require simultaneous vacuum drying of both the electrode sheet and the core. However, to further control moisture, a vacuum drying step is performed only before the core is hot-pressed, i.e., a core vacuum hot-pressing process is conducted, while the electrode sheet rolling is performed in the conventional manner, i.e., no electrode sheet vacuum rolling process is performed. This method is highly targeted and can effectively control the moisture inside the core without over-drying the electrode sheet, balancing efficiency and effectiveness.

[0066] When the specific surface area of ​​the battery positive electrode is within the third preset range, and / or the moisture content of the battery coating roll is within the third preset range, which represents the case of the maximum specific surface area of ​​the positive electrode or the highest moisture content of the coating roll, a dual drying method of electrode vacuum rolling and core vacuum hot pressing is used simultaneously in the process after electrode baking and before cell baking to ensure maximum moisture removal and meet stringent drying requirements.

[0067] Through the above steps, differentiated drying treatment based on the specific surface area of ​​the battery cathode and the moisture content of the battery coating roll is achieved, significantly improving the accuracy and efficiency of moisture control in the secondary battery manufacturing process. By setting different preset ranges and corresponding drying process intensities, the drying quality of the battery cells can be guaranteed while avoiding resource waste and potential material damage caused by over-drying, thus improving production efficiency and energy utilization efficiency. This graded processing strategy not only enhances the flexibility of moisture control but also ensures that the battery cells achieve ideal moisture levels even in applications using highly absorbent materials, significantly improving battery performance consistency and the controllability of the manufacturing process.

[0068] In some embodiments, the aforementioned first preset moisture range is ≤600ppm, for example, a range of 590~600ppm, and the specific moisture content of the lower roll of battery coating can be selected as 592ppm, 595ppm, and 598ppm; the aforementioned first preset specific surface area range is ≤0.5m. 2 / g, for example, select a range of 0.3 to 0.5m 2 / g, the specific ratio of the positive electrode of the battery can be selected as 0.3m. 2 / g, 0.4m 2 / g and 0.5m 2 / g; the second preset moisture range is 601-700 ppm, for example, a range of 690-700 ppm. Specifically, the moisture content of the lower roll of battery coating can be selected as 692 ppm, 696 ppm, or 699 ppm. The second preset specific surface area range is 0.6-1.0 m. 2 / g, for example, select a range of 0.7 to 0.9m 2 / g, the specific ratio of the positive electrode of the battery can be selected as 0.7m. 2 / g, 0.8m 2 / g and 0.9m 2 / g; the third preset moisture range is 701-800 ppm, for example, a range of 790-800 ppm. Specifically, the moisture content of the lower roll of battery coating can be selected as 793 ppm, 795 ppm, or 800 ppm. The third preset specific surface area range is 1.1-1.5m. 2 / g, for example, select a range of 1.2 to 1.4m 2 / g, the specific ratio of the positive electrode of the battery can be selected as 1.2m. 2 / g, 1.3m 2 / g and 1.4m 2 / g.

[0069] Specifically, the first preset moisture range includes a low moisture content in the coated roll (≤600ppm), and the first preset specific surface area range includes a small positive electrode specific surface area (≤0.5m²). 2 / g). Within the first preset moisture range and the first preset ratio range, the cell material itself has a weak ability to absorb moisture, and there is less residual moisture after coating and unwinding. Therefore, it is not necessary to perform additional electrode vacuum rolling and core vacuum hot pressing after electrode baking. Only standard electrode rolling and core hot pressing are required, which simplifies the production process and saves energy.

[0070] The second preset moisture range is suitable for slightly higher moisture contents (601–700 ppm), and the second preset specific surface area range is suitable for moderately increased cathode specific surface areas (0.6–1.0 m²). 2 / g). Within the second preset moisture range and the second preset specific ratio range, the material's water absorption tendency increases, and the residual moisture after coating and unwinding is also relatively greater. Therefore, after the electrode baking, only the core is subjected to a vacuum hot pressing process to specifically reduce the moisture inside the core, while the electrode vacuum rolling process is unnecessary. This ensures the effectiveness of moisture control and avoids unnecessary over-drying of the electrode, maintaining the optimal condition of the battery assembly.

[0071] The second preset range is suitable for slightly higher moisture content (601–700 ppm) and moderately increased cathode specific surface area (0.6–1.0 m²). 2 / g). In this range, the material's tendency to absorb water increases, and there is relatively more residual moisture after coating and unwinding. Therefore, after the electrode baking, only the core is subjected to vacuum hot pressing to reduce the moisture inside the core, while the electrode vacuum rolling process is unnecessary. This ensures the effectiveness of moisture control and avoids unnecessary over-drying of the electrode, maintaining the optimal condition of the battery assembly.

[0072] The third preset moisture range is for high moisture content (701–800 ppm), and the third preset specific surface area range is for high cathode specific surface area (1.1–1.5 m²). 2 These materials have strong water absorption and a high risk of moisture residue. Therefore, after the electrode is baked, two high-intensity drying processes, namely electrode vacuum rolling and core vacuum hot pressing, need to be carried out simultaneously to ensure maximum removal of moisture and prevent adverse effects caused by moisture during subsequent assembly, thereby ensuring the high performance and stability of the battery.

[0073] By setting the above preset moisture range and preset ratio range, precise management of moisture control during battery manufacturing is achieved. The drying process can be flexibly adjusted according to material characteristics, which avoids unnecessary energy waste and ensures the consistency and high quality of battery production.

[0074] In some embodiments, the steps of the above-mentioned electrode vacuum rolling process include: a vacuuming step: evacuating the cavity in which the rolling mill is located; a drying gas replenishment step: replenishing the cavity with the above-mentioned drying gas after the above-mentioned vacuuming process; and a rolling step: unfolding the battery electrode after the above-mentioned drying gas replenishment step and then performing the rolling process.

[0075] Specifically, the vacuuming step involves removing air from the sealed chamber of the rolling mill, creating a near-vacuum state. Lowering the pressure within the chamber reduces moisture molecules in the air, creating a dry environment beneficial for subsequent electrode moisture control. The drying gas replenishment step, following the vacuuming, involves adding drying gas to the chamber. This drying gas is typically a dehumidified inert gas, such as nitrogen or dry air, to replace the humid air inside the chamber, further ensuring the electrodes do not absorb additional moisture from the environment. After replenishing the drying gas and achieving the desired dryness, the battery electrodes are placed in the dry chamber for rolling. This process not only adjusts the thickness and density of the electrodes to meet battery manufacturing standards but also helps evaporate any residual moisture inside the electrodes in the dry gas environment, achieving better drying results. The physical forming of the electrodes under these conditions effectively avoids structural instability or performance degradation caused by excessive moisture.

[0076] By implementing a vacuum rolling process for electrodes, the moisture management of electrodes during secondary battery manufacturing has been significantly improved. The vacuuming step effectively reduces the humidity within the rolling mill chamber, creating a dry environment for subsequent processing. The subsequent replenishment of drying gas completely replaces the moisture in the chamber, ensuring the electrodes are in an optimal low-moisture state before rolling. The rolling process, conducted in a dry gas environment, not only achieves precise control over the physical morphology of the electrodes but also promotes the removal of residual moisture from the electrodes, thereby significantly reducing the initial moisture content before cell baking. Overall, this process effectively controls electrode moisture, reduces the time and energy required for subsequent cell baking, and improves battery production efficiency and product quality.

[0077] In some embodiments, the steps of the above-mentioned core vacuum hot pressing process include: a vacuuming step: evacuating the cavity in which the hot press is located; a drying gas replenishment step: replenishing the cavity with the above-mentioned drying gas after the vacuuming process; and a hot pressing step: hot pressing the battery core after the above-mentioned drying gas replenishment step.

[0078] Before the battery core is hot-pressed, it is wound. Specifically, the winding process involves winding the separator, the positive electrode sheet of the battery after the above-mentioned electrode baking process, and the negative electrode sheet of the battery and then placing them into the casing to form the battery core.

[0079] In the vacuum hot pressing process for battery cores, the vacuuming step involves evacuating the cavity containing the hot press to reduce moisture within the cavity. Vacuuming lowers the ambient humidity, preventing the battery core from absorbing additional moisture during hot pressing. The drying gas replenishment step involves adding drying gas to the cavity after the vacuuming process. The drying gas process has already been described in the section on replenishing drying gas in the electrode vacuum rolling process and will not be repeated here. The drying gas replaces any remaining moist gas in the cavity, further ensuring that the battery core undergoes hot pressing in a water-free or low-moisture environment. The hot pressing step involves hot pressing the battery core after the drying gas has been filled. Hot pressing not only helps adjust and stabilize the core's structure, making it tighter and flatter, but also, surrounded by drying gas, accelerates the evaporation of any residual moisture, further reducing the core's moisture content.

[0080] The vacuum hot-pressing process for battery cores significantly reduces moisture absorption during hot pressing by evacuating the press chamber and replenishing it with drying gas before hot pressing, thereby improving the quality of rechargeable batteries. Firstly, it creates a water-free or low-moisture hot-pressing environment, effectively preventing moisture gain in the core due to ambient humidity, thus avoiding the complexity and energy consumption of subsequent cell baking. The introduction of drying gas ensures that the humidity within the core's pores and material interfaces remains low, facilitating rapid evaporation of residual moisture and achieving more efficient moisture control during hot pressing. The hot pressing step, conducted surrounded by drying gas, not only enhances the structural stability of the core but also further reduces its moisture content. In short, the vacuum hot-pressing process for battery cores effectively reduces production costs and improves battery reliability and performance.

[0081] Traditional drying gas supply systems are typically static, operating under specific parameters and unable to adapt to varying demands from different materials or production stages. To address this, some embodiments introduce a highly tunable drying gas circulation system. This system dynamically adjusts the flow rate, temperature, and drying degree of the drying gas based on real-time material characteristics (e.g., specific surface area of ​​the battery cathode, moisture content of the coating roll), process stage, and external environmental conditions (e.g., air humidity) to ensure optimal drying results. A series of humidity, temperature, and gas composition sensors are deployed, covering all critical nodes from electrode preparation to cell assembly, collecting data in real-time and transmitting it to the central control system. A machine learning-based dynamic control algorithm is developed to predict the optimal drying conditions for materials based on real-time data and adaptively adjust parameters in the drying gas circulation system, such as gas flow rate and heating power. After use, the drying gas is regenerated and dried through a recycling unit. The regenerated gas is then recycled according to current drying needs, forming a highly efficient closed-loop system and reducing energy waste.

[0082] In some embodiments, after performing the above-described cell baking process, the method further includes: when the moisture content of the initial cell meets the requirements, performing the cumulative duration of the cell baking process; if the cumulative duration of the cell baking process exceeds a preset duration, adjusting the parameters of the electrode vacuum rolling process and / or the parameters of the core vacuum hot pressing process, so that the duration of the cell baking process for cells of the same specifications in subsequent manufacturing processes is less than or equal to the preset duration, wherein the preset duration is positively correlated with the specific gravity of the battery positive electrode and positively correlated with the moisture content of the battery coating roll.

[0083] Specifically, after the cell baking process is completed, the moisture content of the cells must be tested and recorded immediately to confirm whether it meets the preset qualification standard. If the moisture content of the cells reaches or falls below the required level in the first test, the cumulative baking time from the start of baking to meeting the conditions must be recorded for subsequent parameter adjustments.

[0084] If the cumulative baking time (actual baking time) of the battery cell exceeds the preset time, it indicates that the current electrode vacuum rolling process and core vacuum hot pressing process have insufficient moisture control, and parameter optimization is required. The preset time is related to the specific surface area of ​​the battery cathode material. The larger the specific surface area of ​​the cathode material, the stronger its water absorption, and therefore the preset time should be extended accordingly, and vice versa. At the same time, the preset time is also positively correlated with the moisture content of the battery after coating and unwinding; that is, the higher the initial moisture content, the longer the preset time.

[0085] To reduce the baking time of subsequent batches of battery cells to within the preset time, parameters were fine-tuned in two aspects:

[0086] Adjustments to electrode vacuum rolling process parameters include increasing the depth of vacuuming, extending the time for vacuuming and replenishing drying gas, or increasing the flow rate of drying gas during the rolling process to more thoroughly remove moisture and humidity from the electrode.

[0087] Adjustment of core vacuum hot pressing process parameters: This involves further optimizing the conditions for vacuuming and replenishing drying gas, as well as fine-tuning the temperature and time of hot pressing, in order to better control the moisture content of the core and ensure that moisture removal is easier and faster during the subsequent baking process.

[0088] This closed-loop feedback mechanism can ensure that the moisture content of the battery cells meets the standards while reducing unnecessary baking energy consumption, thereby improving the overall efficiency and economy of battery production.

[0089] The following specific example illustrates the entire process of parameter adjustment:

[0090] Initial settings: Preset duration is 12 hours (based on the current battery positive electrode specific gravity of 2000m). 2 / kg (when the moisture content of the coated roll is 800ppm), the goal is to ensure that the cumulative baking time of the same specification cells in the next cycle does not exceed 12 hours.

[0091] Implementation process:

[0092] Moisture content testing after cell baking process: Immediately after the cell baking process is completed, the moisture content of the cells is tested using a Karl Fischer moisture meter. Assume the measured moisture content is 450 ppm and the baking time is 15 hours.

[0093] Adjustment of electrode vacuum rolling process parameters:

[0094] Temperature adjustment: Increased from 70℃ to 85℃ to accelerate moisture evaporation. Pressure adjustment: Increased vacuum pressure from -0.08MPa to -0.09MPa to improve moisture removal efficiency. Time adjustment: Extended vacuum treatment time from 15 minutes to 20 minutes per batch to ensure more moisture is removed before hot pressing.

[0095] Adjustment of vacuum hot pressing process parameters for the core:

[0096] Temperature Adjustment: The hot-pressing temperature of the core is increased from 95℃ to 100℃ to enhance moisture evaporation while maintaining it within a range that will not damage the material structure. Pressure Adjustment: The vacuum pressure during the preheating and hot-pressing process is adjusted from -0.07MPa to -0.08MPa to more effectively lock in and remove moisture from inside the core. Time Adjustment: The dwell time during preheating and hot-pressing is increased from 10 minutes to 15 minutes to ensure that as much moisture as possible is expelled from the core during the hot-pressing process.

[0097] Further verification: In the next cycle of cell preparation, the electrode vacuum rolling and core vacuum hot pressing were performed according to the adjusted parameters mentioned above. After completing the above processes, the cells were baked again, and the change in moisture content was monitored in real time until the moisture content met the standard.

[0098] Results analysis: The results showed that the baking time of the battery cells prepared according to the optimized parameters was shortened to 10 hours, and the moisture content was stabilized at about 350 ppm, which met the preset time requirements and significantly improved the efficiency and effect of moisture control.

[0099] By finely adjusting the parameters of the initial drying process, the total time required for subsequent baking of the battery cells can be effectively reduced, while ensuring that the moisture content of the battery cells is within a reasonable range. This improves the efficiency and economy of the entire battery manufacturing process, and also ensures the performance stability and reliability of the battery products.

[0100] In traditional processes, the cell baking time is usually fixed. Regardless of the specific surface area of ​​the cathode material or the moisture content during the coating roll-up stage, the baking process proceeds according to a predetermined cycle. This can not only lead to energy waste, but also, for highly hygroscopic materials, incomplete moisture removal can affect battery performance and lifespan. In this embodiment, however, the cell moisture content is monitored in real-time after baking, and data on the cumulative baking time is collected, providing a basis for dynamic adjustment of process parameters. If the baking time exceeds the preset time, it means that the cell absorbed a lot of moisture in the early stages, or the moisture removal efficiency was low. In this case, adjusting key parameters such as temperature, pressure, and time in the electrode vacuum rolling process and the core vacuum hot pressing process can significantly improve the efficiency of these drying steps, thereby reducing the time required for subsequent cell baking and ensuring that the baking time for the same cell specifications in the next preparation process can be controlled within a preset reasonable range. The preset time setting considers two key factors: the specific surface area of ​​the cathode material and the moisture content during coating roll-up, making process adjustments more scientific and reasonable. By adjusting the parameters of the initial electrode vacuum rolling process and / or the core vacuum hot pressing process, moisture accumulation can be reduced at the source, lowering the baking difficulty. This closed-loop feedback mechanism enables precise management of cell moisture control, which not only improves battery production efficiency and energy utilization but also ensures battery performance. Especially when dealing with highly hygroscopic cathode materials, it can prevent battery safety and performance issues caused by moisture.

[0101] In some embodiments, after performing the above-mentioned electrode vacuum rolling process and before performing the above-mentioned core vacuum hot pressing process, the method further includes: winding the separator, the battery positive electrode sheet after the above-mentioned electrode baking process, and the battery negative electrode sheet and placing them into the housing to form a battery core, wherein the separator is located between the battery positive electrode sheet and the battery negative electrode sheet.

[0102] Specifically, after the vacuum rolling process of the electrodes, both the positive and negative electrode sheets have been dried to reduce moisture content and enhance the performance and stability of the cell. Next, before forming the battery core, the dried positive and negative electrode sheets are precisely matched and wound with the separator material. First, a layer of separator material is precisely placed between the positive and negative electrode sheets. The separator's function is to physically isolate the positive and negative electrodes, preventing short circuits, while allowing ions to pass freely; it is a crucial component of charge transport within the battery. Then, using specialized winding equipment, the positive and negative electrode sheets with the separator are wound in a specific order and according to certain rules to form a tightly packed battery core. The winding process must ensure that the separator is evenly distributed, avoiding gaps or wrinkles between the positive and negative electrode sheets, which would affect the battery's internal structure and performance. The wound battery core is then placed into the battery casing. The battery casing not only encapsulates and protects the core but also provides the necessary mechanical strength and sealing to prevent external environmental factors from affecting the battery.

[0103] In the above process, the correct placement and tight winding of the separator are crucial, as they directly affect the structural integrity, internal impedance, and final safety and performance of the battery cell. Especially since the electrodes have already been dried during the vacuum rolling process, the matching degree and tightness of the separator and electrodes during winding are extremely important for maintaining the low moisture content of the cell. This reduces the amount of water that needs to be removed in the subsequent vacuum hot pressing process, thereby reducing the baking difficulty and energy consumption of the cell and improving the efficiency of the entire manufacturing process.

[0104] In some embodiments, a battery electrode baking process is performed, wherein the battery electrode obtained after the coating process is baked at a preset temperature, including: performing the electrode baking process on the battery electrode, wherein the positive electrode obtained after the coating process is baked at a first preset temperature; and performing the electrode baking process on the battery electrode, wherein the negative electrode obtained after the coating process is baked at a second preset temperature, wherein the first preset temperature is greater than the second preset temperature.

[0105] Specifically, in the production process of secondary batteries, the electrode baking process is a key step used to remove excess moisture from the coated electrodes. Because the material properties of the positive and negative electrodes differ, their sensitivity to temperature and their moisture removal requirements also differ. Therefore, using a first preset temperature and a second preset temperature to bake the positive and negative electrodes separately allows for more efficient and targeted moisture control.

[0106] Positive electrode sheets typically contain highly reactive chemical components, such as lithium iron phosphate (LFP), and have a large specific surface area, meaning they have a high moisture content and are more difficult to remove. Therefore, baking at a relatively high initial preset temperature aims to accelerate the evaporation rate of moisture, ensuring that the moisture content of the positive electrode sheet is reduced to a minimum without damaging the chemical properties and physical structure of the material.

[0107] Compared to positive electrodes, negative electrodes (such as graphite negative electrodes) are less sensitive to moisture but more sensitive to high temperatures, which can easily lead to interlayer expansion or structural damage in graphite. Therefore, baking the negative electrode at a lower second preset temperature can effectively remove moisture while avoiding potential damage to the material and maintaining good electronic conductivity and ion transport capabilities.

[0108] The selection of the first and second preset temperatures is based on the characteristics of the battery's positive and negative electrode materials and the required efficiency for moisture removal. By precisely setting different baking temperatures, efficient moisture removal and control can be achieved for the specific characteristics of the positive and negative electrodes, thereby reducing the moisture content of the final battery cell and improving the overall performance and safety of the battery. A higher first preset temperature helps to quickly evaporate moisture in the positive electrode, while a lower second preset temperature avoids overheating of the negative electrode, protecting the original properties of the materials and preventing unnecessary chemical or physical changes. Differentiated temperature control can adjust the baking time according to the characteristics of the materials, avoiding the time waste and increased energy consumption that may result from uniform high-temperature baking, and helping to improve the overall efficiency and economic benefits of battery production.

[0109] In some embodiments, the range of the first preset temperature is 165 to 175°C, for example, 167°C, 169°C, 172°C and 175°C can be selected, and the range of the second preset temperature is 85 to 95°C, for example, 85°C, 88°C, 90°C and 92°C can be selected.

[0110] Specifically, the battery positive electrode sheet obtained after the coating process is baked at a first preset temperature, which is in the range of 165-175℃, a suitable temperature for baking the positive electrode sheet. Positive electrode materials, whether lithium iron phosphate (LFP) or other types, typically have high water absorption and chemical activity, requiring baking at high temperatures to ensure complete moisture removal. However, excessively high temperatures can damage the material structure and affect battery performance. A temperature of 165-175℃ effectively evaporates moisture while remaining within a range that does not significantly damage the structure of most positive electrode materials. High temperatures can accelerate moisture evaporation, but it is also necessary to avoid exceeding the material's temperature resistance limit. The temperature range of 165-175℃ is derived from a comprehensive consideration of the thermal stability and moisture evaporation characteristics of the positive electrode material, balancing the need for moisture removal efficiency with the requirement to maintain good material performance. Specifically, the first preset temperature can be selected from 165℃, 168℃, 170℃, and 174℃, with 170℃ being preferred, effectively balancing the need for moisture removal efficiency and the requirement to maintain material performance. At 170℃, the evaporation rate of moisture reaches an optimal level, while the risk of structural damage to the cathode material is relatively low, thus ensuring a high degree of assurance for battery production efficiency and final product quality. At 170℃, moisture in the cathode sheet can be removed more thoroughly, reducing the moisture content in subsequent battery manufacturing processes.

[0111] The battery negative electrode sheet obtained after the coating process is baked at a second preset temperature, ranging from 85 to 95°C. In comparison, the baking temperature for negative electrode sheets (such as graphite materials) is much lower because graphite is more susceptible to structural damage at higher temperatures, affecting its performance as a negative electrode material. The temperature range of 85–95°C ensures gentle evaporation of moisture while avoiding expansion or structural deformation between graphite layers, maintaining its good conductivity and lithium storage capacity as a lithium-ion battery negative electrode. Graphite materials have strong thermal stability, but at temperatures close to 100°C, the evaporation rate of moisture in graphite accelerates. Simultaneously, excessively high temperatures intensify the interaction between graphite particles, leading to changes in interlayer spacing and a decline in material properties. Therefore, 95°C, as the upper temperature limit, can remove moisture while preserving the original structure of the graphite material to the greatest extent. The second preset temperature can specifically be selected from 85°C, 88°C, 90°C, and 95°C, with 90°C being preferred. Compared to other temperatures in the 85–95°C range, 90°C provides sufficient heat to accelerate moisture evaporation while remaining at a level that does not cause significant changes in graphite interlayer spacing or structural damage. Considering graphite's high temperature sensitivity, the 90°C setting avoids overheating-induced particle expansion or interlayer adhesion problems, which directly affect the battery's electrochemical performance, such as reduced energy density and shortened cycle life.

[0112] By setting different baking temperatures, this differentiated control strategy can provide customized baking conditions based on the material characteristics of the positive and negative electrodes. This ensures both efficiency and material quality during the moisture removal process. The different temperature requirements of the positive and negative electrodes during baking allow for more intelligent energy allocation, avoiding unnecessary high-temperature baking, thus saving energy consumption and reducing production costs. In summary, setting different temperature ranges significantly improves the accuracy and efficiency of moisture control in secondary battery production, reduces battery performance loss due to moisture issues, and ultimately enhances the overall battery quality and production efficiency.

[0113] In some embodiments, the temperature parameters in the above-mentioned cell baking process are in the range of 90 to 100°C, for example, 90°C, 93°C, 96°C and 100°C can be selected.

[0114] Specifically, the temperature parameter of 90–100°C was set after comprehensively considering the thermal stability of the cell materials, the moisture evaporation rate, and cost-effectiveness. This temperature range ensures that the cell materials (such as positive and negative electrodes, separators, and electrolyte components) will not undergo structural changes or performance degradation due to overheating during the moisture removal process. For example, the separator may experience thermal shrinkage at higher temperatures, affecting the cell's geometry and the integrity of its internal structure. Within the 90–100°C temperature range, the moisture evaporation rate is significantly increased, ensuring that the battery reaches the ideal drying level within a reasonable baking time. This is because within the 90–100°C range, the kinetic energy of water molecules increases, and the intermolecular attraction weakens, making it easier for moisture to escape from the cell materials. The baking process consumes a large amount of energy; therefore, the selection of the temperature must not only consider the effectiveness of moisture removal but also comprehensively evaluate energy consumption and production costs. The 90–100°C range was determined after a cost-effectiveness analysis, achieving efficient moisture removal without excessive energy waste.

[0115] Choosing 90–100℃ as the baking temperature range for battery cells reflects a comprehensive consideration of cell material characteristics, production efficiency, and cost-effectiveness. Within this range, controlling the temperature allows for finding the optimal balance between moisture removal and protecting the cell material's performance. This 90–100℃ temperature range ensures efficient and safe removal of moisture from the cells, which is crucial for improving the overall performance and quality of the secondary battery. It contributes to enhancing battery consistency and reliability, extending cycle life, and increasing energy and power density.

[0116] In some embodiments, the pressure value of the pressure parameter in the above-mentioned electrode vacuum rolling process is in the range of 6.5 to 8.5t, for example, 6.6t, 7.1t, 7.6t and 8.4t can be selected; the temperature value of the temperature parameter is in the range of 80 to 120°C, for example, the range of 90 to 100°C can be selected, for example, 90°C, 92°C, 97°C and 100°C can be selected; and the vacuum pressure value is in the range of -85 to -75 kPa, for example, -84 kPa, -80 kPa, -79 kPa and -75 kPa can be selected.

[0117] Specifically, the electrode vacuum rolling process aims to shape and compact the electrode by applying pressure in a vacuum environment, while simultaneously removing air and moisture from the electrode's interior, thereby improving its density and uniformity. The pressure range of 6.5–8.5 tons (t) was determined after process optimization to ensure sufficient compaction of the electrode material, forming a uniform and dense structure, while avoiding excessive pressure that could cause material deformation or damage, affecting battery performance. Within this pressure range of 6.5–8.5 tons, the internal structure of the electrode is more stable, and its conductivity and mechanical strength are improved, which is beneficial for increasing battery energy density and cycle life.

[0118] Temperature parameters affect the electrode's shaping and moisture removal capabilities. During the vacuum rolling process, increased temperature helps soften the electrode material, making it easier to compact, and simultaneously accelerates moisture evaporation. The temperature range of 80–120°C is set based on the electrode material's thermal stability and moisture evaporation characteristics. 80°C is the lower limit for initiating moisture evaporation and material shaping, while 120°C is the upper limit to prevent overheating and structural damage. At suitable temperatures, the electrode's moisture content can be effectively controlled, and the material's physical properties are optimized, thereby improving battery stability and safety.

[0119] The temperature parameter ranges from 80 to 120°C, for example, 80 to 95°C, specifically 80°C, 85°C, 90°C, and 92°C, with 90°C being preferred. 90°C provides sufficient heat to accelerate moisture evaporation while maintaining a level that avoids overheating the material. At this temperature, moisture can be removed more efficiently, reducing the time and energy consumption of subsequent baking processes. 90°C balances the need for material softening with the risk of material decomposition, ensuring that the electrode maintains good physical and chemical properties during compaction.

[0120] In summary, the temperature parameters in the electrode vacuum rolling process are set between 80 and 120°C, with 90°C being preferred. This temperature setting comprehensively considers the need for moisture removal, the protection of the material's physicochemical properties, and the stability and repeatability of the process. This temperature parameter setting helps improve the performance of the secondary battery, extend its cycle life, and enhance its safety.

[0121] The vacuum pressure setting creates a low-oxygen environment to reduce residual air during electrode compaction and promote moisture evaporation. This is because moisture evaporates more easily in low-pressure environments. A vacuum pressure of -85 to -75 kPa ensures that the gas inside the electrode is fully removed, while this vacuum level does not exert excessive pressure on the electrode material, thus avoiding damage. Rolling in a vacuum environment not only improves the density of the electrode but also significantly reduces internal moisture, thereby improving the electrochemical performance and safety of the battery during charging and discharging.

[0122] Within the vacuum pressure range of -85 to -75 kPa, specifically -84 kPa, -80 kPa, -78 kPa, and -74 kPa can be selected, with -80 kPa being the preferred option. -80 kPa provides a sufficiently low pressure environment to remove air and moisture from the electrode to a large extent without damaging the electrode structure. This helps to form a more uniform and dense electrode, improving the electrochemical performance and stability of the battery. While lower vacuum pressure can further improve gas removal efficiency, it may also introduce greater stress into the electrode material, leading to changes or damage to the microstructure. A vacuum pressure of -80 kPa effectively removes gas while maintaining the microstructure of the material, ensuring that battery performance is not affected.

[0123] The vacuum rolling process parameters for electrodes, including pressure values ​​of 6.5–8.5t, temperature values ​​of 80–120℃, and vacuum pressure values ​​of -85–-75 kPa, significantly improve moisture control and electrode density during battery production. Precise control of pressure, temperature, and vacuum not only effectively removes moisture and air from the electrode interior, reducing baking difficulty, but also optimizes the electrode's microstructure and improves the bonding strength between materials, thereby enhancing the battery's energy density, cycle stability, and safety. Specifically, the pressure setting ensures uniform material compaction, the temperature range accelerates moisture evaporation without damaging material performance, and the vacuum pressure effectively removes internal gases. These three factors work synergistically to achieve efficient moisture management during battery production, reduce baking energy consumption, lower production costs, and provide solid technical support for the high-quality and efficient manufacturing of rechargeable batteries.

[0124] In some embodiments, the pressure value of the pressure parameter in the above-mentioned core vacuum hot pressing process is in the range of 5.5 to 8.5t, for example, the range is selected as 6.5 to 7.5t, specifically 6.5t, 6.7t, 7.1t and 7.5t; the temperature parameter is in the range of 90 to 100℃, for example, 92℃, 95℃, 98℃ and 100℃; and the vacuum pressure is in the range of -85 to -75Kpa, for example, -85Kpa, -83Kpa, -80Kpa and -72Kpa.

[0125] Specifically, during the vacuum hot pressing process of the core, the pressure parameter serves to tightly bond the positive and negative electrode sheets and the separator, eliminating internal voids and improving the core's density. The pressure range is set between 5.5 and 8.5 tons (t) to ensure effective bonding of the core's layers while avoiding material deformation or damage that might occur due to excessive pressure. This pressure range effectively enhances the compactness of the battery's internal structure, reduces internal resistance, and thus improves the battery's electrochemical performance and energy density. The temperature parameter (90–100°C) aims to utilize the heating effect during hot pressing to promote the softening of the electrode sheets and separator, making them easier to shape according to the desired structure, while simultaneously accelerating moisture evaporation and reducing the core's moisture content. The 90–100°C temperature range is chosen to balance the need for material softening with the avoidance of thermal damage, ensuring the integrity of the material structure and the stability of its function, while effectively controlling and removing moisture, thus improving the battery's safety and consistency.

[0126] During the vacuum hot pressing process of the battery core, the vacuum pressure value is set to -85 to -75 kPa to establish a low-pressure environment during hot pressing. This facilitates the removal of air and moisture from inside the core, reduces the presence of air bubbles, and improves the tight contact of the materials. The vacuum pressure range of -85 to -75 kPa effectively reduces the gas content and residual moisture inside the core, minimizes side reactions during battery charging and discharging, and improves battery stability and lifespan.

[0127] The parameter settings of the core vacuum hot pressing process (pressure 5.5~8.5t, temperature 90~100℃, vacuum pressure -85~-75KPa) work together to significantly improve the internal structural density of the battery, effectively control moisture, and optimize overall battery performance. The pressure range ensures good adhesion between materials, temperature control accelerates moisture removal, and the application of the vacuum pressure further eliminates residual gas. The synergistic effect of these three factors helps reduce the battery's internal resistance, increase energy density, and extend cycle life, while simultaneously reducing energy consumption and costs during the baking process, thus improving the overall production efficiency and finished product quality of rechargeable batteries.

[0128] To avoid potential blind spots from a single moisture detection point, a multi-level moisture detection and response system is established. In some embodiments, multiple detection points are set at different stages of battery manufacturing, such as after electrode powder drying, after electrode coating, before and after rolling, and before and after hot pressing. Each detection point has its own independent moisture detection equipment and a preset moisture threshold. When the detected moisture content exceeds the preset threshold, an emergency drying procedure is automatically initiated, such as increasing the drying air flow rate, extending the drying time, or increasing the drying temperature, to restore the moisture content to a safe range as quickly as possible. The tiered response mechanism is as follows: Level 1 response: Slight exceedance; a rapid response is achieved by slightly adjusting the drying air flow rate or temperature to bring it back to the normal range. Level 2 response: Moderate exceedance; in addition to adjusting the drying air parameters, additional pre-drying before hot pressing is initiated to enhance localized moisture removal. Level 3 response: Severe exceedance; the system will suspend the current production batch for thorough oven drying or introduce a special desiccant for deep dehydration until the moisture content fully meets the standard before resuming production.

[0129] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the secondary battery preparation method of this application will be described in detail below with reference to specific embodiments.

[0130] This embodiment relates to a specific method for preparing a secondary battery, such as... Figure 3As shown, the positive and negative electrode active materials are first dried to remove moisture, preventing it from affecting the subsequent slurry performance and battery quality, and ensuring the stability of the electrode powder's physicochemical properties. The dried positive and negative electrode active materials are then mixed with binders, conductive agents, solvents, etc., and processed through stirring to create uniform and stable positive and negative electrode slurries, providing suitable materials for coating. The positive and negative electrode slurries are uniformly coated onto current collectors (such as positive aluminum foil and negative copper foil) to form a coating of a certain thickness and shape, constructing the basic structure for the battery reaction. The coated positive and negative electrode sheets are baked, followed by a vacuum rolling process, where a vacuum is first drawn and then dry gas is added during the rolling process. The separator, the battery positive electrode sheet after the electrode baking process, and the battery negative electrode sheet are wound and placed into the casing to form a battery core, with the separator located between the positive and negative electrode sheets. Subsequently, a preheating and hot pressing process, namely a core vacuum hot pressing process (where a vacuum is first drawn and then dry gas is added during the core hot pressing process), is performed. The pre-treated battery cell assembly, including the positive electrode, negative electrode, and separator, is combined with other necessary battery components to form a complete battery cell unit. A cell baking process (cell drying) is then performed, where the initial cell is baked for a corresponding duration based on its pre-baking moisture content. Electrolyte is injected into the assembled battery casing, serving as a medium for ion transport and ensuring ion movement during charging and discharging. Next is the formation step, which involves initial charging of the electrolyte-injected battery to form a stable solid electrolyte interface film. This film protects the electrodes and suppresses side reactions. Then comes the capacity grading step, which tests the battery's capacity, internal resistance, and other performance indicators to screen qualified products and differentiate between different capacity levels for subsequent matching and application. After capacity grading, the batteries undergo comprehensive performance testing, including voltage, internal resistance, self-discharge, and cycle performance, to ensure product quality. Qualified batteries are then packaged and coated to protect them, facilitate storage, transportation, and subsequent assembly and use. The following examples will further illustrate the beneficial effects of this application.

[0131] Example 1

[0132] The specific surface area of ​​the cathode material is between 0.6 and 1.0 m². 2The moisture content in the / g range is suitable for materials with moderate water absorption. The initial coating moisture content (coating roll moisture) of the positive electrode is controlled at 690-700 ppm. Standard graphite material is used for the negative electrode, and its properties and moisture control methods are not changed. It is assumed that the initial moisture content is equivalent to or slightly higher than that of the positive electrode material. A coating machine is used to ensure uniform slurry distribution and initial drying, but vacuum drying technology is not used. The positive and negative electrode sheets are mechanically rolled at room temperature without vacuum drying to maintain the original physical properties and chemical composition of the materials. In the preheating and hot pressing stage before entering the winding process, the positive and negative electrode sheets are sent to a vacuum hot pressing equipment with a set temperature of 90℃, a pressure of 7.0 tons, and a vacuum pressure of -80KPa for processing. Through this step, the moisture on the surface and inside of the electrode sheets is effectively removed, preparing materials with lower moisture content for subsequent winding and baking. After optimization before hot pressing, the baking time of the battery cells at 90℃ was significantly reduced. The specific baking time, based on experimental results, ranged from 6 to 8 hours, with the moisture content controlled at 590-600 ppm before baking. Compared with traditional processes, this significantly shortened the baking cycle, reduced energy consumption, and ensured the battery's moisture content standards.

[0133] Comparative Example 1

[0134] The specific surface area of ​​the cathode material is also between 0.6 and 1.0 m². 2 The material properties are the same as in Example 1, within the / g range. The initial coating moisture content (coating roll moisture) of the positive electrode is controlled at 690-700 ppm, the same as in Example 1. Standard graphite material is used for the negative electrode, and no additional moisture control measures are taken; the initial moisture content is comparable to that of the positive electrode material. The positive and negative electrode sheets are processed using standard coating techniques and drying equipment, without any vacuum drying or preheating / hot pressing drying treatment. The electrode sheets are mechanically rolled at room temperature without additional vacuum drying steps. Vacuum drying technology is not used before preheating / hot pressing; the core is hot pressed under conventional conditions. Without preheating / hot pressing drying optimization, the moisture content of the cell before baking is estimated to be 790-800 ppm. To meet the moisture standard, the cell must be baked at 90°C for a relatively long time, specifically between 18 and 20 hours according to experimental data. The extended baking time not only increases energy consumption but may also adversely affect the long-term performance of the battery.

[0135] The comparison results between Example 1 and Comparative Example 1 are shown in Table 1:

[0136] Table 1 Comparison results between Example 1 and Comparative Example 1

[0137]

[0138] Example 2

[0139] The specific surface area of ​​the cathode material is between 1.1 and 1.5 m². 2 Materials in the / g range exhibit stronger hygroscopicity due to their larger surface area. The initial coating moisture content (coating roll moisture) of the positive electrode is controlled at 790–800 ppm, indicating a relatively high initial moisture content. The negative electrode material uses standard graphite, without altering its properties or moisture control methods. Vacuum drying technology is employed before rolling and preheating / hot pressing to deeply remove internal moisture from the material, reducing the difficulty of subsequent baking. Through a two-stage vacuum drying process, the pre-baking moisture content is optimized to 490–500 ppm, significantly lower than the initial moisture content, providing a foundation for subsequent rapid baking. Due to effective moisture control in the early stages, the baking time of the battery cell at 90°C can be shortened to 6 hours, significantly reducing energy consumption and processing time compared to traditional processes.

[0140] Comparative Example 2

[0141] The specific surface area of ​​the cathode material is also between 1.1 and 1.5 m². 2 The material exhibits the same material properties as in Example 2, with a strong initial moisture absorption capacity. The initial coating moisture content (coating roll moisture) of the positive electrode is controlled at 790–800 ppm, the same as in Example 2. Standard graphite material is used for the negative electrode, and no additional moisture control measures are taken. Vacuum drying technology is only introduced before preheating and hot pressing, but no vacuum drying treatment is performed before rolling, which limits the comprehensiveness of moisture control. Although vacuum drying is performed before preheating and hot pressing, the moisture control effect before baking is not as significant as in Example 2 due to the lack of a drying step before rolling, and the expected moisture content is between 640 and 650 ppm. Due to the high moisture content before baking, the cell needs to be baked at 90°C for at least 12 hours to reach the ideal moisture standard, which is a significant increase compared to the 6-hour baking time in Example 2.

[0142] Comparative Example 3

[0143] The specific surface area of ​​the cathode material is also between 1.1 and 1.5 m². 2 The material in the / g range has the same material properties as in Example 2, exhibiting strong initial moisture absorption. The initial coating moisture content (coating roll moisture) of the positive electrode is controlled at 790–800 ppm, the same as in Example 2. Standard graphite material is used for the negative electrode, and no additional moisture control measures are taken. Vacuum drying is only performed before preheating and hot pressing; no vacuum drying is performed before rolling, which may result in some moisture remaining inside the electrode. Due to the lack of a vacuum drying step before rolling, the moisture content before baking in Comparative Example 3 is relatively high, expected to be between 740 and 750 ppm. To remove more moisture, the baking time of the cell at 90°C needs to be extended to 12–14 hours, a significant increase compared to Example 2, resulting in a corresponding increase in energy consumption.

[0144] The comparison results between Example 2 and Comparative Example 2 are shown in Table 2:

[0145] Table 2 Comparison results between Example 2 and Comparative Example 2

[0146]

[0147] The comparison results between Example 2 and Comparative Example 3 are shown in Table 3:

[0148] Table 3 Comparison results between Example 2 and Comparative Example 3

[0149]

[0150] Therefore, Embodiment 1 of this application has technical advantages in both pre-baking moisture content and baking time.

[0151] This application also provides a secondary battery manufacturing apparatus, which includes an electrode baking device, an electrode vacuum rolling device, a core vacuum hot pressing device, and a cell baking device. The electrode baking device performs the electrode baking process, in which the battery electrodes obtained after the coating process are baked at a preset temperature. The electrode vacuum rolling device performs the electrode vacuum rolling process. The core vacuum hot pressing device performs the core vacuum hot pressing process. The device determines whether to perform the electrode vacuum rolling process and the core vacuum hot pressing process after the electrode baking process and before the cell baking process, based on the battery positive electrode specific surface area and / or the battery coating moisture content after the coating process. The battery positive electrode specific surface area refers to the specific surface area of ​​the battery positive electrode, and the battery coating moisture content refers to the amount of moisture after the electrode baking process. The residual moisture content of the battery electrode sheets during winding after processing; the electrode sheet vacuum rolling process characterizes the process of first evacuating the vacuum and then replenishing the dry gas during the electrode sheet rolling process; the core vacuum hot pressing process characterizes the process of first evacuating the vacuum and then replenishing the dry gas during the core hot pressing process. The temperature range of the rolling equipment in the electrode sheet rolling process differs from the temperature range of the hot pressing equipment in the core hot pressing process. The cell baking equipment is used to execute the cell baking process steps, in which the initial cell is baked for a corresponding duration based on the cell moisture content before baking.

[0152] By precisely controlling the drying process, the moisture content during battery manufacturing is effectively managed, significantly improving battery performance and production efficiency. An electrode baking process ensures the initial drying of the electrodes after coating. Based on the specific surface area of ​​the positive electrode and the residual moisture after coating and unwinding, the selection of electrode vacuum rolling and core vacuum hot pressing processes is made. These processes, by first vacuuming and then replenishing with drying gas, can specifically reduce moisture in highly absorbent materials or electrodes with high residual moisture, avoiding the need for such intensive drying in all cases and preventing excessive resource consumption. The cell baking process dynamically adjusts the baking time based on the cell's moisture content before baking, ensuring that each batch of cells reaches the ideal drying state and avoiding problems of residual moisture or over-drying. In short, this embodiment replaces the electrode rolling process in the prior art with the electrode vacuum rolling process, and the core hot pressing process with the core vacuum hot pressing process. Moisture is removed by vacuuming and filling with dry air, which improves the control accuracy of moisture content and greatly reduces the baking time of the subsequent cell baking process. This solves the problem of low control accuracy of cell moisture content in the prior art secondary battery manufacturing process.

[0153] In some embodiments, the apparatus for preparing the secondary battery includes an electrode rolling mill and a core hot pressing mill. When the specific gravity of the positive electrode of the battery is within a first preset specific gravity range, and / or the moisture content of the battery coating roll is within a first preset moisture content range, it is determined that after the electrode baking process and before the cell baking process, the electrode vacuum rolling mill does not perform the electrode vacuum rolling process, the core vacuum hot pressing mill does not perform the core vacuum hot pressing process, the electrode rolling mill performs the electrode rolling process, and the core hot pressing mill performs the core hot pressing process.

[0154] When the positive electrode ratio of the battery is within the second preset ratio range, and / or the moisture content of the battery coating roll is within the second preset moisture content range, it is determined that after the electrode baking process and before the cell baking process, the electrode vacuum rolling equipment does not perform the electrode vacuum rolling process step, but the core vacuum hot pressing equipment performs the core vacuum hot pressing process step, and the electrode rolling equipment performs the electrode rolling process step.

[0155] When the positive electrode ratio of the battery is within the third preset ratio range, and / or the moisture content of the battery coating roll is within the third preset moisture content range, it is determined that after the electrode baking process and before the cell baking process, the electrode vacuum rolling equipment performs the electrode vacuum rolling process, and the core vacuum hot pressing equipment performs the core vacuum hot pressing process.

[0156] Wherein, the maximum value of the first preset ratio range is less than the minimum value of the second preset ratio range, and the maximum value of the second preset ratio range is less than the minimum value of the third preset ratio range; the maximum value of the first preset moisture range is less than the minimum value of the second preset moisture range, and the maximum value of the second preset moisture range is less than the minimum value of the third preset ratio range.

[0157] The aforementioned equipment enables differentiated drying processes based on the specific surface area of ​​the battery cathode and the moisture content of the battery coating roll, significantly improving the accuracy and efficiency of moisture control in the secondary battery manufacturing process. By setting different preset ranges and corresponding drying process intensities, the drying quality of the battery cells can be guaranteed while avoiding resource waste and potential material damage caused by over-drying, thus improving production efficiency and energy utilization efficiency. This tiered processing strategy not only enhances the flexibility of moisture control but also ensures that the battery cells achieve ideal moisture levels even in applications using highly absorbent materials, significantly improving battery performance consistency and the controllability of the manufacturing process.

[0158] The aforementioned first preset moisture range is ≤600ppm, and the aforementioned first preset specific surface area range is ≤0.5m. 2 / g; the second preset moisture range is 601–700 ppm, and the second preset specific surface area range is 0.6–1.0 m. 2 / g; the above-mentioned third preset moisture range is 701~800ppm, and the above-mentioned third preset specific surface area range is 1.1~1.5m. 2 / g.

[0159] By setting the above preset moisture range and preset ratio range, precise management of moisture control during battery manufacturing is achieved. The drying process can be flexibly adjusted according to material characteristics, which avoids unnecessary energy waste and ensures the consistency and high quality of battery production.

[0160] In some embodiments, the aforementioned electrode vacuum rolling equipment includes a vacuum pumping sub-equipment, a drying gas replenishment sub-equipment, and a rolling equipment. The vacuum pumping sub-equipment performs a vacuum pumping step, evacuating the cavity in which the rolling mill is located; the drying gas replenishment sub-equipment performs a drying gas replenishment step, replenishing the cavity with the aforementioned drying gas after the aforementioned vacuum pumping step; the rolling equipment performs a rolling step, unfolding the battery electrode after the aforementioned drying gas replenishment step and then performing the rolling process.

[0161] By implementing a vacuum rolling process for electrodes, the moisture management of electrodes during secondary battery manufacturing has been significantly improved. The vacuuming step effectively reduces the humidity within the rolling mill chamber, creating a dry environment for subsequent processing. The subsequent replenishment of drying gas completely replaces the moisture in the chamber, ensuring the electrodes are in an optimal low-moisture state before rolling. The rolling process, conducted in a dry gas environment, not only achieves precise control over the physical morphology of the electrodes but also promotes the removal of residual moisture from the electrodes, thereby significantly reducing the initial moisture content before cell baking. Overall, this process effectively controls electrode moisture, reduces the time and energy required for subsequent cell baking, and improves battery production efficiency and product quality.

[0162] In some embodiments, the aforementioned core vacuum hot pressing equipment includes a vacuum pumping sub-equipment, a dry gas replenishment sub-equipment, and a hot pressing sub-equipment. The vacuum pumping sub-equipment performs a vacuum pumping step, evacuating the cavity containing the hot press; the dry gas replenishment sub-equipment performs a dry gas replenishment step, replenishing the cavity with the dry gas after the vacuum pumping process; and the hot pressing sub-equipment performs a hot pressing step, hot pressing the battery core after the dry gas replenishment step.

[0163] The vacuum hot-pressing process for battery cores significantly reduces moisture absorption during hot pressing by evacuating the press chamber and replenishing it with drying gas before hot pressing, thereby improving the quality of rechargeable batteries. Firstly, it creates a water-free or low-moisture hot-pressing environment, effectively preventing moisture gain in the core due to ambient humidity, thus avoiding the complexity and energy consumption of subsequent cell baking. The introduction of drying gas ensures that the humidity within the core's pores and material interfaces remains low, facilitating rapid evaporation of residual moisture and achieving more efficient moisture control during hot pressing. The hot pressing step, conducted surrounded by drying gas, not only enhances the structural stability of the core but also further reduces its moisture content. In short, the vacuum hot-pressing process for battery cores effectively reduces production costs and improves battery reliability and performance.

[0164] In some embodiments, the above-described apparatus is further configured to determine the cumulative duration of the cell baking process when the moisture content of the initial cell meets the requirements; and to adjust the parameters of the electrode vacuum rolling process and / or the parameters of the core vacuum hot pressing process when the cumulative duration of the cell baking process exceeds a preset duration, so that the duration of the cell baking process in subsequent manufacturing processes for cells of the same specifications is less than or equal to the preset duration, wherein the preset duration is positively correlated with the specific gravity of the battery cathode and positively correlated with the moisture content of the battery coating roll.

[0165] In traditional processes, the cell baking time is usually fixed. Regardless of the specific surface area of ​​the cathode material or the moisture content during the coating roll-up stage, the baking process proceeds according to a predetermined cycle. This can not only lead to energy waste, but also, for highly hygroscopic materials, incomplete moisture removal can affect battery performance and lifespan. In this embodiment, however, the cell moisture content is monitored in real-time after baking, and data on the cumulative baking time is collected, providing a basis for dynamic adjustment of process parameters. If the baking time exceeds the preset time, it means that the cell absorbed a lot of moisture in the early stages, or the moisture removal efficiency was low. In this case, adjusting key parameters such as temperature, pressure, and time in the electrode vacuum rolling process and the core vacuum hot pressing process can significantly improve the efficiency of these drying steps, thereby reducing the time required for subsequent cell baking and ensuring that the baking time for the same cell specifications in the next preparation process can be controlled within a preset reasonable range. The preset time setting considers two key factors: the specific surface area of ​​the cathode material and the moisture content during coating roll-up, making process adjustments more scientific and reasonable. By adjusting the parameters of the initial electrode vacuum rolling process and / or the core vacuum hot pressing process, moisture accumulation can be reduced at the source, lowering the baking difficulty. This closed-loop feedback mechanism enables precise management of cell moisture control, which not only improves battery production efficiency and energy utilization but also ensures battery performance. Especially when dealing with highly hygroscopic cathode materials, it can prevent battery safety and performance issues caused by moisture.

[0166] In some embodiments, the above-described apparatus is further used to wind and place the separator, the battery positive electrode sheet after the above-described electrode sheet baking process, and the battery negative electrode sheet into a housing after performing the above-described electrode sheet vacuum rolling process and before performing the above-described core vacuum hot pressing process, thereby forming a battery core, wherein the separator is located between the above-described battery positive electrode sheet and the above-described battery negative electrode sheet.

[0167] In the above process, the correct placement and tight winding of the separator are crucial, as they directly affect the structural integrity, internal impedance, and final safety and performance of the battery cell. Especially since the electrodes have already been dried during the vacuum rolling process, the matching degree and tightness of the separator and electrodes during winding are extremely important for maintaining the low moisture content of the cell. This reduces the amount of water that needs to be removed in the subsequent vacuum hot pressing process, thereby reducing the baking difficulty and energy consumption of the cell and improving the efficiency of the entire manufacturing process.

[0168] In some embodiments, the electrode baking equipment is used to perform the electrode baking process on the battery electrode, wherein the positive electrode obtained after the coating process is baked at a first preset temperature; the electrode baking process is performed on the battery electrode, wherein the negative electrode obtained after the coating process is baked at a second preset temperature, wherein the first preset temperature is greater than the second preset temperature.

[0169] The selection of the first and second preset temperatures is based on the characteristics of the battery's positive and negative electrode materials and the required efficiency for moisture removal. By precisely setting different baking temperatures, efficient moisture removal and control can be achieved for the specific characteristics of the positive and negative electrodes, thereby reducing the moisture content of the final battery cell and improving the overall performance and safety of the battery. A higher first preset temperature helps to quickly evaporate moisture in the positive electrode, while a lower second preset temperature avoids overheating of the negative electrode, protecting the original properties of the materials and preventing unnecessary chemical or physical changes. Differentiated temperature control can adjust the baking time according to the characteristics of the materials, avoiding the time waste and increased energy consumption that may result from uniform high-temperature baking, and helping to improve the overall efficiency and economic benefits of battery production.

[0170] In some embodiments, the first preset temperature ranges from 165 to 175°C, and the second preset temperature ranges from 85 to 95°C.

[0171] By setting different baking temperatures, this differentiated control strategy can provide customized baking conditions based on the material characteristics of the positive and negative electrodes. This ensures both efficiency and material quality during the moisture removal process. The different temperature requirements of the positive and negative electrodes during baking allow for more intelligent energy allocation, avoiding unnecessary high-temperature baking, thus saving energy consumption and reducing production costs. In summary, setting different temperature ranges significantly improves the accuracy and efficiency of moisture control in secondary battery production, reduces battery performance loss due to moisture issues, and ultimately enhances the overall battery quality and production efficiency.

[0172] In some embodiments, the temperature parameters in the above-described cell baking process range from 90 to 100°C.

[0173] Choosing 90–100℃ as the baking temperature range for battery cells reflects a comprehensive consideration of cell material characteristics, production efficiency, and cost-effectiveness. Within this range, controlling the temperature allows for finding the optimal balance between moisture removal and protecting the cell material's performance. This 90–100℃ temperature range ensures efficient and safe removal of moisture from the cells, which is crucial for improving the overall performance and quality of the secondary battery. It contributes to enhancing battery consistency and reliability, extending cycle life, and increasing energy and power density.

[0174] In some embodiments, the pressure value of the pressure parameter in the above-mentioned electrode vacuum rolling process ranges from 6.5 to 8.5t, the temperature value ranges from 80 to 120°C, and the vacuum pressure value ranges from -85 to -75KPa.

[0175] The vacuum rolling process parameters for electrodes, including pressure values ​​of 6.5–8.5t, temperature values ​​of 80–120℃, and vacuum pressure values ​​of -85–-75 kPa, significantly improve moisture control and electrode density during battery production. Precise control of pressure, temperature, and vacuum not only effectively removes moisture and air from the electrode interior, reducing baking difficulty, but also optimizes the electrode's microstructure and improves the bonding strength between materials, thereby enhancing the battery's energy density, cycle stability, and safety. Specifically, the pressure setting ensures uniform material compaction, the temperature range accelerates moisture evaporation without damaging material performance, and the vacuum pressure effectively removes internal gases. These three factors work synergistically to achieve efficient moisture management during battery production, reduce baking energy consumption, lower production costs, and provide solid technical support for the high-quality and efficient manufacturing of rechargeable batteries.

[0176] In some embodiments, the pressure parameters of the above-mentioned core vacuum hot pressing process range from 5.5 to 8.5t, the temperature parameters range from 90 to 100°C, and the vacuum pressure ranges from -85 to -75 kPa.

[0177] The parameter settings of the core vacuum hot pressing process (pressure 5.5~8.5t, temperature 90~100℃, vacuum pressure -85~-75KPa) work together to significantly improve the internal structural density of the battery, effectively control moisture, and optimize overall battery performance. The pressure range ensures good adhesion between materials, temperature control accelerates moisture removal, and the application of the vacuum pressure further eliminates residual gas. The synergistic effect of these three factors helps reduce the battery's internal resistance, increase energy density, and extend cycle life, while simultaneously reducing energy consumption and costs during the baking process, thus improving the overall production efficiency and finished product quality of rechargeable batteries.

[0178] This application also provides a secondary battery, which is prepared using any of the above-described methods for preparing a secondary battery.

[0179] This application also provides an energy storage system, including at least one of the above-described secondary batteries.

[0180] This application also provides an electrical device, including at least one of the above-described secondary batteries or the above-described energy storage system.

[0181] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0182] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a secondary battery, characterized in that, include: A battery electrode baking process is performed, wherein the battery electrode obtained after coating process is baked at a preset temperature in the step of the electrode baking process. Based on the battery positive electrode specific surface area and / or the battery coating under-winding moisture content, it is determined whether to perform the electrode vacuum rolling process and the core vacuum hot pressing process after the electrode baking process and before the cell baking process. The battery positive electrode specific surface area refers to the specific surface area of ​​the battery positive electrode sheet. The battery coating under-winding moisture content refers to the moisture content remaining on the battery electrode sheet during winding after the electrode baking process. The electrode vacuum rolling process represents the process of first evacuating a vacuum and then replenishing with drying gas during the electrode rolling process. The core vacuum hot pressing process represents the process of first evacuating a vacuum and then replenishing with drying gas during the core hot pressing process. The cell baking process is carried out, wherein the initial cell is baked for a corresponding duration based on the cell moisture content before baking.

2. The method for preparing a secondary battery according to claim 1, characterized in that, Based on the battery positive electrode specificity table and / or the moisture content of the battery coating roll, determine whether to perform an electrode vacuum rolling process and a core vacuum hot pressing process after the electrode baking process and before the cell baking process, including: If the specific ratio of the positive electrode of the battery is within the first preset specific ratio range, and / or the moisture content of the battery coating roll is within the first preset moisture content range, it is determined that the electrode vacuum rolling process and the core vacuum hot pressing process will not be performed after the electrode baking process and before the cell baking process, but the electrode rolling process and the core hot pressing process will be performed. If the battery positive electrode specificity is within the second preset specificity range, and / or the battery coating roll moisture is within the second preset moisture range, it is determined that after the electrode baking process and before the cell baking process, the electrode vacuum rolling process will not be performed, but the core vacuum hot pressing process will be performed, and the electrode rolling process will be performed. If the battery positive electrode specificity is within a third preset specificity range, and / or the battery coating roll moisture is within a third preset moisture range, it is determined that the electrode vacuum rolling process and the roll core vacuum hot pressing process shall be performed after the electrode baking process and before the cell baking process. Wherein, the maximum value of the first preset ratio range is less than the minimum value of the second preset ratio range, and the maximum value of the second preset ratio range is less than the minimum value of the third preset ratio range; the maximum value of the first preset moisture range is less than the minimum value of the second preset moisture range, and the maximum value of the second preset moisture range is less than the minimum value of the third preset ratio range.

3. The method for preparing a secondary battery according to claim 2, characterized in that, The first preset moisture range is ≤600ppm, and the first preset specific surface area range is ≤0.5m. 2 / g; The second preset moisture range is 601–700 ppm, and the second preset specific gravity range is 0.6–1.0 m. 2 / g; The third preset moisture range is 701–800 ppm, and the third preset specific gravity range is 1.1–1.5 m. 2 / g.

4. The method for preparing a secondary battery according to claim 1, characterized in that, The steps of the electrode vacuum rolling process include: Vacuuming step: Vacuuming is performed on the cavity where the roller press is located; The step of replenishing the drying gas is as follows: After the vacuuming process is performed, the drying gas is replenished into the cavity; Rolling step: After the supplementary drying gas step, the battery electrode is subjected to rolling treatment.

5. The method for preparing a secondary battery according to claim 1, characterized in that, The steps of the vacuum hot pressing process for the core include: Vacuuming step: Vacuuming is performed on the cavity containing the hot press; The step of replenishing the drying gas is as follows: After the vacuuming process is performed, the drying gas is replenished into the cavity; Hot pressing step: After the replenishment of drying gas step, the battery core is subjected to hot pressing treatment.

6. The method for preparing a secondary battery according to claim 1, characterized in that, After performing the cell baking process, the method further includes: The cumulative time for the cell baking process is determined when the initial cell moisture content meets the requirements. If the cumulative time of the cell baking process exceeds the preset time, the parameters of the electrode vacuum rolling process and / or the parameters of the core vacuum hot pressing process are adjusted so that the time of the cell baking process in the subsequent preparation process for cells of the same specifications is less than or equal to the preset time. The preset time is positively correlated with the specific gravity of the battery positive electrode and positively correlated with the moisture content of the battery coating roll.

7. The method for preparing a secondary battery according to claim 1, characterized in that, After the electrode vacuum rolling process and before the core vacuum hot pressing process, the method further includes: The separator, the positive electrode sheet of the battery after the electrode baking process, and the negative electrode sheet of the battery are wound and placed into the housing to form a battery core, with the separator located between the positive electrode sheet and the negative electrode sheet of the battery.

8. The method for preparing a secondary battery according to claim 1, characterized in that, A battery electrode baking process is performed, wherein the battery electrode obtained after the coating process is baked at a preset temperature, including: The battery electrode is subjected to the electrode baking process, wherein the battery positive electrode obtained after the coating process is baked at a first preset temperature in the step of the electrode baking process. The battery electrode sheet is subjected to the electrode baking process, wherein the battery negative electrode sheet obtained after the coating process is baked at a second preset temperature, and the first preset temperature is greater than the second preset temperature.

9. The method for preparing a secondary battery according to claim 8, characterized in that, The first preset temperature ranges from 165 to 175°C, and the second preset temperature ranges from 85 to 95°C.

10. The method for preparing a secondary battery according to claim 1, characterized in that, The temperature parameters in the cell baking process are in the range of 90 to 100°C.

11. The method for preparing a secondary battery according to any one of claims 1 to 10, characterized in that, The pressure parameters in the electrode vacuum rolling process range from 6.5 to 8.5t, the temperature parameters range from 80 to 120℃, and the vacuum pressure ranges from -85 to -75KPa.

12. The method for preparing a secondary battery according to any one of claims 1 to 10, characterized in that, The pressure parameters of the vacuum hot pressing process for the core are in the range of 5.5 to 8.5t, the temperature parameters are in the range of 90 to 100℃, and the vacuum pressure is in the range of -85 to -75KPa.

13. A secondary battery, characterized in that, The secondary battery is prepared by the method for preparing a secondary battery according to any one of claims 1 to 12.

14. An energy storage system, characterized in that, include: At least one secondary battery as described in claim 13.

15. An electrical appliance, characterized in that, include: At least one secondary battery as described in claim 13 or an energy storage system as described in claim 14.

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