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

Abstract

The invention belongs to the technical field of energy storage, and provides a preparation method of a secondary battery, the secondary battery, an energy storage system and electric equipment. The method comprises the following steps: carrying out a pole piece baking process on a battery pole piece; whether a pole piece vacuum rolling process and a roll core vacuum hot pressing process are carried out after a pole piece baking process and before a battery core baking process is carried out is determined according to a battery positive electrode specific surface and / or battery coating lower roll moisture, and the pole piece vacuum rolling process is characterized in that in the pole piece rolling process, vacuum pumping is carried out and then dry gas is supplemented; the roll core vacuum hot-pressing process is characterized in that in the roll core hot-pressing treatment process, vacuumizing is conducted firstly, and then dry gas is supplemented; and carrying out a battery cell baking process, wherein in the step of the battery cell baking process, the initial battery cell is baked for a corresponding duration based on the water content of the battery cell before the battery cell is baked. The problem that in the preparation process of the secondary battery, the control precision of the water content of the battery cell is low is solved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a method for preparing a secondary battery, a secondary battery, an energy storage system, and electrical equipment. Background Art

[0002] Batteries are being used more and more widely in various fields. The requirements for battery performance in these multi-field applications are constantly increasing. Controlling the moisture content of battery cells is a key link in the battery manufacturing process.

[0003] In battery manufacturing, the moisture content of battery cells directly impacts the electrochemical performance and lifespan of the battery. Excessive moisture can lead to degradation of electrode materials, intensified hydrogen evolution reactions, and electrolyte decomposition, shortening battery life. Furthermore, improper moisture control can increase the battery's internal resistance, reducing its energy density and power output. Current solutions for controlling moisture content in battery cells have limitations, such as low precision. Summary of the Invention

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

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a method for preparing a secondary battery is provided, comprising: performing a pole piece baking process on a battery pole piece, wherein the pole piece baking process adopts a preset temperature to bake the battery pole piece obtained after the coating process; determining whether to perform a pole piece vacuum rolling process and a core vacuum hot pressing process after the pole piece baking process and before the battery core baking process according to the battery positive electrode ratio table and / or the battery coating roll moisture, wherein the battery positive electrode ratio table is the specific surface area of ​​the battery positive electrode piece, and the battery coating roll moisture is divided into the specific surface area after the pole piece baking process. The residual moisture content of the battery electrode when it is rolled up, the electrode vacuum rolling process is characterized by first evacuating the vacuum and then adding dry gas during the electrode rolling process, and the core vacuum hot pressing process is characterized by first evacuating the vacuum and then adding dry gas during the core hot pressing process, wherein the temperature value range of the temperature parameter of the rolling equipment during the electrode rolling process is different from the temperature value range of the temperature parameter of the hot pressing equipment during the core hot pressing process; the battery cell baking process is carried out, and in the steps of the battery cell baking process, the initial battery cell is baked for a corresponding time based on the moisture content of the battery cell before baking.

[0006] Furthermore, according to the battery positive electrode ratio table and / or the battery coating roll moisture content, it is determined whether to perform the electrode piece vacuum rolling process and the core winding vacuum hot pressing process after the electrode piece baking process and before the battery cell baking process, including: when the battery positive electrode ratio table is in a first preset ratio table range, and / or the battery coating roll moisture content is in a first preset moisture range, it is determined that the electrode piece vacuum rolling process and the core winding vacuum hot pressing process are not performed after the electrode piece baking process and before the battery cell baking process, and the electrode piece rolling process and the core winding hot pressing process are performed; when the battery positive electrode ratio table is in a second preset ratio table range, and / or the battery coating roll moisture content is in a second preset moisture range, it is determined that after the electrode piece baking process and before the battery cell baking process, the electrode piece vacuum rolling process and the core winding vacuum hot pressing process are performed. Before, the pole piece vacuum rolling process is not performed but the core vacuum hot pressing process is performed, and the pole piece rolling process is performed; when the battery positive electrode ratio is within the third preset ratio range, and / or the battery coating lower roll moisture is within the third preset moisture range, it is determined that the pole piece vacuum rolling process and the core vacuum hot pressing process are performed after the pole piece baking process and before the battery 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.

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

[0008] Furthermore, the steps of the electrode vacuum rolling process include: a vacuuming step: vacuuming the cavity where the roller press is located; a dry gas replenishing step: replenishing the dry gas into the cavity after the vacuuming step; and a rolling step: after the dry gas replenishing step, the battery electrode is unfolded and then rolled.

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

[0010] Furthermore, after performing the battery cell baking process, the method also includes: when obtaining the moisture content of the initial battery cell meets the requirements, performing the cumulative time of the battery cell baking process; when the cumulative time of the battery cell baking process is greater than the preset time, adjusting the parameters of the electrode vacuum rolling process and / or the parameters of the core vacuum hot pressing process, so that the battery cells of the same specifications are subjected to the battery cell baking process for a time less than or equal to the preset time in the subsequent preparation process, wherein the preset time is positively correlated with the battery positive electrode ratio table, and the preset time is 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 also includes: winding the diaphragm, the battery positive electrode sheet processed by the electrode baking process, and the battery negative electrode sheet and placing them into the shell to form a battery core, and the diaphragm is located between the battery positive electrode sheet and the battery negative electrode sheet.

[0012] Furthermore, a pole piece baking process is performed on the battery pole piece, and a preset temperature is used in the pole piece baking process to bake the battery pole piece obtained after the coating process, including: performing the pole piece baking process on the battery pole piece, and a first preset temperature is used in the pole piece baking process to bake the battery positive pole piece obtained after the coating process; performing the pole piece baking process on the battery pole piece, and a second preset temperature is used in the pole piece baking process to bake the battery negative pole piece obtained after the coating process, 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 parameter range of the battery cell baking process is 90-100°C.

[0015] Furthermore, the pressure parameter in the electrode vacuum rolling process has a pressure value ranging from 6.5 to 8.5 kPa, the temperature parameter has a temperature value ranging from 80 to 120 °C, and the vacuum pressure value ranges from -85 to -75 kPa.

[0016] Furthermore, the pressure parameter of the core vacuum hot pressing process has a pressure value range of 5.5 to 8.5t, the temperature parameter has a temperature value of 90 to 100°C, and the vacuum pressure value is -85 to -75KPa.

[0017] According to another aspect of the present application, a secondary battery is provided. The secondary battery is prepared by using any one of the methods for preparing a secondary battery.

[0018] According to another aspect of the present application, there is provided an energy storage system, comprising: at least one secondary battery as described above.

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

[0020] The beneficial effects of the present application are: the electrode rolling process in the prior art is replaced by a electrode vacuum rolling process, and the core hot pressing process is replaced by a core vacuum hot pressing process, and moisture is removed by vacuuming and filling with dry air, thereby improving the control accuracy of moisture content, and the baking time of the subsequent battery cell baking process can be greatly shortened, solving the problem of low control accuracy of battery cell moisture content in the secondary battery preparation process in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0022] Figure 1 A schematic flow chart of a method for preparing a secondary battery according to an embodiment of the present application is shown;

[0023] Figure 2 A schematic diagram showing a process flow of determining whether to perform a pole piece vacuum rolling process and a core vacuum hot pressing process in a method for preparing a secondary battery according to an embodiment of the present application is shown;

[0024] Figure 3 A flowchart of a specific method for preparing a secondary battery according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" 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 intervening elements may be present. Moreover, in the specification and claims, when it is described that an element is "connected to" another element, the element may be "directly connected to" the other element or "connected to" the other element through a third element.

[0028] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

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

[0030] In the description of the embodiments of the present application, “multiple” means more than two, unless otherwise clearly and specifically defined.

[0031] In the description of the embodiments of the present application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists, A and B exist at the same time, and B exists.

[0032] As described in the background technology, excessive water content in battery cells may lead to degradation of electrode materials, intensified hydrogen evolution reactions, and electrolyte decomposition, thereby shortening battery life. In addition, improper water content control may also increase the internal resistance of the battery, reducing its energy density and power output. To address the problem of low precision in controlling the water content of battery cells in the prior art secondary battery preparation process, the embodiments of the present application provide a method for preparing a secondary battery, a secondary battery, an energy storage system, and an electrical device.

[0033] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0034] Figure 1 FIG. 1 is a flow chart of a method for preparing a secondary battery according to an embodiment of the present application. Figure 1 As shown, the method includes the following steps:

[0035] Step S101: performing a pole piece baking process on the battery pole piece, wherein the pole piece baking process is performed by baking the battery pole piece obtained after the coating process at a preset temperature;

[0036] Specifically, in the early stages of battery manufacturing, the active material is coated onto the current collector (usually aluminum foil or copper foil) to form a positive electrode slurry or a negative electrode slurry, which is then dried to remove the solvent. This process is called coating. The electrode will have a certain amount of moisture after coating. The electrode baking process sets a specific temperature range, that is, the preset temperature, so that the preset temperature removes moisture from the electrode without damaging its physical properties and electrochemical performance. The setting of the preset temperature depends on the properties of the active material and the structure of the electrode.

[0037] The electrode baking process is the process of removing residual moisture from the electrode by heating under certain temperature and time conditions. This process is usually completed in an oven or special baking equipment to ensure that the moisture content in the electrode does not negatively affect battery performance in subsequent battery manufacturing steps.

[0038] The battery electrode baking process, in which the coated electrode is baked at a preset temperature, effectively and precisely controls the electrode's moisture content. By setting an appropriate baking temperature, residual moisture and solvent from the coating process can be efficiently removed without compromising the electrode material's structure and performance, thereby ensuring the stability and consistency of the battery cell during subsequent manufacturing and 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 during production.

[0039] Step S102: determining whether to perform a pole piece vacuum rolling process and a core vacuum hot pressing process after the pole piece baking process and before the battery cell baking process according to the battery positive electrode ratio table and / or the battery coating roll moisture, wherein the battery positive electrode ratio table is the specific surface area of ​​the battery positive pole piece, the battery coating roll moisture is the moisture content remaining in the battery pole piece when it is rolled up after the pole piece baking process, the pole piece vacuum rolling process is characterized by first evacuating the vacuum and then adding dry gas during the pole piece rolling process, and the core vacuum hot pressing process is characterized by first evacuating the vacuum and then adding dry gas during the core hot pressing process;

[0040] Among them, the temperature of the rolling equipment during the above-mentioned pole piece rolling process is the temperature of the roller surface where the pole piece contacts the roller; the temperature of the hot pressing equipment during the above-mentioned core hot pressing process is the temperature of the hot press surface where the core contacts the hot press.

[0041] Specifically, first, decide whether to add an additional vacuum drying step based on the battery positive electrode specific surface area and / or the moisture content of the battery coating roll. The positive electrode specific surface area refers to the specific surface area of ​​the battery positive electrode sheet, which reflects the particle size and structural looseness of the material. The larger the specific surface area, the larger the contact area between the material and the environment, and the stronger the water absorption. If the battery positive electrode specific surface area is small and the moisture content is low after baking, it means that the material itself has weak water absorption, and baking is sufficient to control the moisture content, and no additional vacuum drying step is required; if the battery positive electrode specific surface area is large or the moisture content is high after baking, it is necessary to further remove the moisture in the electrode sheet and the core through the electrode sheet vacuum rolling process and / or the core vacuum hot pressing process to achieve more stringent moisture control standards.

[0042] The pole piece vacuum rolling process involves first evacuating the battery before traditional pole piece rolling, followed by the addition of dry gas. This process aims to accelerate the evaporation of residual moisture in the vacuum environment and prevent water vapor from recondensing by filling the pores with dry gas, thereby effectively reducing the moisture content within the pole piece. The core vacuum hot pressing process targets battery structures that have been wound into cores. This process also involves first evacuating the battery, then adding dry gas, and hot pressing at a specific temperature. This process aims to remove moisture from the core, particularly at the interface between the pole piece and the separator, thereby reducing the difficulty and time of cell baking.

[0043] The equipment temperature parameter ranges for the pole piece rolling process and the core hot pressing process are different. This is because the material composition and structural state of the pole piece and the core are different, and different temperature conditions are required to achieve the best drying effect while avoiding material damage.

[0044] By evaluating the specific surface area of ​​the battery positive electrode sheet (battery positive electrode specific surface area) and / or the moisture content of the electrode sheet after coating and unwinding (battery coating and unwinding moisture content), a strategy for dynamically adjusting the process flow is proposed. This strategy can not only flexibly adjust the drying process according to the characteristics of the positive electrode material to ensure that the final moisture content of the battery cell meets strict standards, but also reduce energy consumption and costs by reducing unnecessary heat treatment steps, thereby improving production efficiency.

[0045] Step S103: performing the above-mentioned cell baking process, in which the initial cells are baked for a corresponding time based on the moisture content of the cells before baking.

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

[0047] The moisture content of battery cells directly affects the baking time required. Lower moisture content can shorten the baking time, as less water means less time and energy required for evaporation. Conversely, higher moisture content requires a longer baking time to ensure sufficient evaporation, thus minimizing the impact of moisture on battery performance during subsequent manufacturing. The key to this strategy lies in accurately measuring the moisture content of the battery cells before baking, allowing for precise control of the baking time without wasting energy or compromising battery quality.

[0048] Testing the moisture content of battery cells before baking is a key step in ensuring moisture control quality during secondary battery preparation. The following are several common methods for measuring moisture content in battery cells, and how to develop appropriate baking strategies based on these measurement results:

[0049] Karl Fischer Titration: This is the most commonly used technique for measuring moisture content in solid, liquid, and gaseous samples. During the test, a battery cell sample is placed in a sealed container. A Karl Fischer reagent then reacts with the water in the sample. The amount of reagent consumed in the reaction is titrated to calculate the moisture content. The result is expressed in parts per million (ppm) and is commonly used to assess moisture content in battery cells before baking.

[0050] Microwave Moisture Testing: This method is a rapid, non-contact method for measuring moisture content. Microwaves are transmitted through a battery cell sample and the sample's absorption or reflection of the microwaves is used to determine its moisture content. This method is suitable for rapid screening of large batches of battery cells and provides immediate moisture content information.

[0051] Infrared Moisture Determination: This method is based on the principle that moisture absorbs infrared light of a specific wavelength. During the test, a battery cell sample is exposed to infrared radiation, and the moisture content is calculated based on the sample's absorption of the infrared light. This method is fast and accurate, making it suitable for real-time monitoring on the production line.

[0052] Resistivity method: Based on the principle that moisture affects the resistivity of battery cell materials, the moisture content is estimated by measuring the change in the resistivity of the battery cell. This method is suitable for continuous monitoring, but may not be as accurate 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 a preset threshold (e.g. 600ppm), the baking time can be reduced, and in some cases over-baking can even be avoided to prevent negative impacts on battery cell performance.

[0055] If the moisture content of the battery cell is higher than a preset threshold (for example, 600ppm) but lower than another more stringent standard (such as 800ppm), a standard or slightly longer baking time is required to ensure that the moisture is fully removed.

[0056] For battery cells with significantly higher moisture content (for example, more than 1000ppm), the baking time needs to be extended, and even a second baking may be required to ensure that the battery cells reach an ideal dry state before injecting the electrolyte.

[0057] During the cell baking process, the baking duration is dynamically adjusted based on the pre-baking moisture content, significantly enhancing the precision and flexibility of moisture management. This ensures that the cell moisture content meets the standard while avoiding the energy waste caused by overbaking and the potential adverse effects on battery materials. By precisely matching moisture content with baking time, production costs are optimized, production efficiency is improved, and battery consistency and reliability are ensured, significantly enhancing the battery's electrochemical performance and service life.

[0058] By precisely controlling the drying process, the moisture content in the battery manufacturing process is effectively managed, significantly improving battery performance and production efficiency. By implementing a pole piece baking process on the battery pole pieces, the initial drying of the pole pieces after coating is ensured. Depending on the specific surface area of ​​the battery's positive pole pieces and the amount of residual moisture after coating and unwinding, the choice of pole piece vacuum rolling process and core vacuum hot pressing process is made. These processes, by first vacuuming and then replenishing the drying gas, can specifically reduce the moisture content of highly absorbent materials or pole pieces with high residual moisture, without requiring such intensive drying in all cases, thus avoiding excessive resource consumption. The battery cell baking process dynamically adjusts the baking time based on the moisture content of the battery cells before baking, ensuring that each batch of battery cells reaches the ideal dry state, avoiding the problems of residual moisture or over-drying. In short, this embodiment replaces the electrode rolling process in the prior art with a electrode vacuum rolling process, and the core hot pressing process with a core vacuum hot pressing process, and removes moisture by vacuuming and filling with dry air, thereby improving the control accuracy of the moisture content, and the baking time of the subsequent battery cell baking process can be greatly shortened, solving the problem of low control accuracy of the moisture content of the battery cell in the secondary battery preparation process in the prior art.

[0059] In some embodiments, it is determined based on the battery positive electrode ratio table and / or the battery coating roll moisture content whether to perform the electrode sheet vacuum rolling process and the core roll vacuum hot pressing process after the above-mentioned electrode sheet baking process and before the battery cell baking process, such as Figure 2 As shown, the following steps are included:

[0060] Step S201: when the battery positive electrode ratio is within a first preset ratio range, and / or the battery coating lower roll moisture is within a first preset moisture range, determining that the electrode sheet vacuum rolling process and the core roll vacuum hot pressing process are not performed after the electrode sheet baking process and before the battery cell baking process, and the electrode sheet rolling process and the core roll hot pressing process are performed instead;

[0061] Step S202: when the battery positive electrode ratio is within a second preset ratio range, and / or the battery coating lower roll moisture is within a second preset moisture range, determining not to perform the electrode sheet vacuum rolling process but to perform the core roll vacuum hot pressing process after performing the electrode sheet baking process and before performing the battery cell baking process, and performing the electrode sheet rolling process;

[0062] Step S203: When the battery positive electrode ratio is within a third preset ratio range, and / or the battery coating lower roll moisture is within a third preset moisture range, determining to perform the electrode sheet vacuum rolling process and the core roll vacuum hot pressing process after performing the electrode sheet baking process and before performing the battery cell baking process;

[0063] Among them, the maximum value of the first preset ratio range is smaller than the minimum value of the above-mentioned second preset ratio range, and the maximum value of the above-mentioned second preset ratio range is smaller than the minimum value of the above-mentioned third preset ratio range; the maximum value of the above-mentioned first preset moisture range is smaller than the minimum value of the above-mentioned second preset moisture range, and the maximum value of the above-mentioned second preset moisture range is smaller than the minimum value of the above-mentioned third preset ratio range.

[0064] Specifically, when the battery's positive electrode specific surface area is within a first preset specific surface area range, and / or the battery's coated and wound material has a moisture content within the first preset moisture range, this indicates that the positive electrode material has a small specific surface area and / or the moisture content after coating and winding is already low. Under these conditions, due to the material's inherently weak tendency to absorb water or low residual moisture, no additional vacuum drying process is required, allowing normal electrode sheet rolling and core hot pressing to proceed directly. This simplifies the manufacturing process while avoiding unnecessary drying energy and time.

[0065] When the battery positive electrode ratio is within the second preset ratio range, and / or the battery coating roll moisture is within the second preset moisture range, it is still not sufficient to require vacuum drying of both the pole piece and the core. However, in order to further control the moisture content, the vacuum drying step is only performed before the core is hot-pressed, that is, the core vacuum hot-pressing process is performed, while the pole piece is rolled in the conventional manner, that is, the pole piece vacuum rolling process is not performed. This method is highly targeted and can effectively control the moisture content inside the core without over-drying the pole piece, taking into account both efficiency and effect.

[0066] When the battery's positive electrode surface area is within the third preset surface area range, and / or the battery's coated lower roll moisture content is within the third preset moisture range, that is, when the positive electrode surface area is maximized or the coated lower roll moisture content is highest. Given that this material has a stronger water absorption capacity and a higher risk of residual moisture, a dual drying method of vacuum rolling of the electrode and vacuum hot pressing of the core is used in the process after electrode baking and before cell baking to ensure maximum moisture removal to meet stringent drying requirements.

[0067] Through the above steps, differentiated drying treatments based on the battery positive electrode specific surface and the moisture content of the battery coating roll are achieved, significantly improving the accuracy and efficiency of moisture control in the secondary battery preparation process. By setting different preset ranges and corresponding drying process intensities, it is possible to ensure the drying quality of the battery cells while avoiding resource waste and possible material damage caused by over-drying, thereby improving production efficiency and energy utilization efficiency. This hierarchical processing strategy not only enhances the flexibility of moisture control, but also ensures that the battery cells can reach the ideal moisture level even in the application scenario of highly absorbent materials, significantly improving the performance consistency of the battery and the controllability of the manufacturing process.

[0068] In some embodiments, the first preset moisture range is ≤600ppm. For example, the range is 590-600ppm, and the moisture content of the battery coating roll can be 592ppm, 595ppm and 598ppm. The first preset ratio range is ≤0.5m 2 / g, for example, select the range 0.3~0.5m 2 / g, the battery positive electrode ratio table can be selected as 0.3m 2 / g, 0.4m 2 / g and 0.5m 2 / g; The second preset moisture range is 601 to 700 ppm. For example, the range is 690 to 700 ppm. The specific moisture content of the battery coating roll can be 692 ppm, 696 ppm and 699 ppm. The second preset ratio range is 0.6 to 1.0 m 2 / g, for example, select the range 0.7~0.9m 2 / g, the specific ratio of the battery positive electrode can be selected as 0.7m 2 / g, 0.8m 2 / g and 0.9m 2 / g; The third preset moisture range is 701 to 800 ppm. For example, the range is 790 to 800 ppm. The specific moisture content of the battery coating roll can be 793 ppm, 795 ppm and 800 ppm. The third preset ratio range is 1.1 to 1.5 m 2 / g, for example, select the range 1.2~1.4m 2 / g, the specific ratio of the battery positive electrode 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 lower coating roll moisture content (≤600ppm), and the first preset specific surface area range includes a smaller positive electrode specific surface area (≤0.5m 2 / g). Within the first preset moisture range and the first preset ratio range, the battery cell material itself has a weak ability to absorb moisture, and the residual moisture after coating and winding is also small. Therefore, there is no need for additional electrode sheet vacuum rolling and core vacuum hot pressing after electrode baking. Only standard electrode sheet 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 content (601-700ppm), and the second preset specific surface area range is suitable for moderately increased positive electrode specific surface area (0.6-1.0m 2 Within the second preset moisture range and the second preset ratio range, the material's tendency to absorb water increases, and relatively more moisture remains after coating and unwinding. Therefore, after the electrode sheets are baked, only the core is subjected to a vacuum hot pressing process to specifically reduce the moisture inside the core, while the electrode sheet vacuum rolling process is unnecessary. This ensures the effectiveness of moisture control while avoiding unnecessary over-drying of the electrode sheets, maintaining the optimal condition of the battery assembly.

[0071] The second preset range is suitable for slightly higher moisture content (601-700ppm) and moderately increased positive electrode specific surface area (0.6-1.0m 2 / g). In this range, the material's tendency to absorb water increases, and relatively more moisture remains after coating and unwinding. Therefore, after the electrode is baked, 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 effective moisture control while avoiding 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 (701-800ppm), and the third preset specific surface area range is for high positive electrode specific surface area (1.1-1.5m 2 This type of material has strong water absorption and a high risk of residual moisture. Therefore, after the electrode is baked, two high-intensity drying processes are required: vacuum rolling of the electrode and vacuum hot pressing of the core. This ensures maximum moisture removal and prevents adverse effects caused by moisture during subsequent assembly, thereby ensuring high performance and stability of the battery.

[0073] By setting the above-mentioned preset moisture ranges and preset ratio ranges, refined management of moisture control in the battery preparation process is achieved, and the drying process can be flexibly adjusted according to material properties, which not only avoids unnecessary energy waste but also 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: vacuuming the cavity where the roller press is located; a dry gas replenishing step: replenishing the above-mentioned dry gas into the above-mentioned cavity after the above-mentioned vacuuming step; and a rolling step: after the above-mentioned dry gas replenishing step, the above-mentioned battery electrode is unfolded and then rolled.

[0075] Specifically, the vacuuming step involves extracting the air from the sealed chamber housing the roller press, creating a near-vacuum state. By reducing the air pressure within the chamber, the amount of moisture in the air is reduced, creating a dry environment that facilitates moisture control in the subsequent electrode sheets. The dry gas replenishment step involves replenishing dry gas into the chamber after the vacuuming step. Dry gas, typically a dehumidified inert gas such as nitrogen or dry air, is used to replace the humid air within the chamber, further ensuring that the electrode sheets do not absorb additional moisture from the environment. After the dry gas is replenished and the desired dryness is achieved, the battery electrode sheets are placed in the dry chamber for roller pressing. This process not only adjusts the thickness and density of the electrode sheets to meet battery manufacturing standards but also further evaporates any residual moisture within the electrode sheets in the dry gas environment, achieving optimal drying results. The physical forming of the electrode sheets in this environment effectively avoids structural instability or performance degradation caused by excessive moisture.

[0076] By implementing the electrode vacuum rolling process, the moisture management effect of the electrode in the secondary battery preparation process has been significantly improved. During the vacuuming step, the humidity of the cavity where the roller press is located is effectively reduced, creating a dry environment for subsequent processing. The subsequent dry gas replenishment step completely replaces the moisture in the cavity by introducing dry gas, ensuring that the electrode is in the optimal low-moisture state before contact rolling. The rolling step carried out in a dry gas environment not only achieves precise control of the physical morphology of the electrode, but also utilizes dry conditions to promote the discharge of residual moisture inside the electrode, thereby significantly reducing the initial moisture content before the battery cell is baked. Overall, this process effectively controls the moisture content of the electrode, reduces the time and energy consumption required for subsequent battery cell baking, and improves the efficiency of battery production and product quality.

[0077] In some embodiments, the steps of the above-mentioned core vacuum hot pressing process include: a vacuuming step: vacuuming the cavity where the hot press is located; a dry gas replenishing step: replenishing the above-mentioned dry gas into the above-mentioned cavity after the above-mentioned vacuuming step; and a hot pressing step: hot pressing the battery core after the above-mentioned dry gas replenishing step.

[0078] Among them, before the battery core is subjected to hot pressing treatment, a winding process is performed. Specifically, the winding process is to wind the diaphragm, the battery positive electrode sheet after the above-mentioned electrode baking process, and the battery negative electrode sheet and then place them into the shell to form a battery core.

[0079] In the core vacuum hot pressing process, the vacuuming step is to vacuum the cavity where the hot press is located, with the aim of reducing the moisture in the cavity. By vacuuming, the ambient humidity is reduced, preventing the battery core from absorbing additional moisture during the hot pressing process. The dry gas replenishing step is to replenish dry gas into the cavity after the vacuuming process is completed. The dry gas has been described in the dry gas replenishing step of the above-mentioned pole piece vacuum rolling process and will not be repeated here. The dry gas can replace the remaining moist gas in the cavity, further ensuring that the battery core is hot pressed in a water-free or low-moisture environment. The hot pressing step is to hot press the battery core after the dry gas is filled. Hot pressing not only helps to adjust and stabilize the structure of the core, making it tighter and flatter, but also, surrounded by dry gas, the hot pressing process helps to accelerate the volatilization of any residual moisture, thereby further reducing the moisture content of the core.

[0080] The core vacuum hot pressing process significantly reduces the moisture absorption of the battery core during the hot pressing process by evacuating the hot press cavity and replenishing dry gas before hot pressing, thereby improving the preparation quality of secondary batteries. First, a water-free or low-moisture hot pressing environment is created, which effectively prevents the core from increasing moisture during the hot pressing device due to ambient humidity, avoiding the complexity and energy consumption of subsequent battery cell baking. The introduction of dry gas ensures that the humidity of the internal pores and material interfaces of the core is maintained at a low level, which helps to quickly volatilize residual moisture, thereby achieving more efficient moisture control during the hot pressing process. The hot pressing step is carried out in the presence of dry gas, which not only enhances the structural stability of the core, but also further reduces its moisture content. In short, the core vacuum hot pressing process effectively reduces production costs and improves the reliability and performance of batteries.

[0081] Traditional drying gas supply systems are typically static, operating under specific parameters and unable to adapt to the changing requirements of different materials or production stages. To this end, some embodiments incorporate a highly tunable drying gas circulation system that dynamically adjusts the drying gas flow rate, temperature, and drying level based on real-time material properties (such as the specific surface area of ​​the battery cathode and the moisture content of the coating roll), process stage, and external environmental conditions (such as air humidity) to ensure optimal drying results. By deploying a series of humidity, temperature, and gas composition sensors covering key nodes from electrode preparation to cell assembly, data is collected in real time and transmitted to a central control system. A dynamic control algorithm based on machine learning is developed that predicts the optimal drying conditions for the material based on real-time data collected and adaptively adjusts 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 recovery unit. The regenerated gas is then recycled based on current drying requirements, forming an efficient closed-loop system that reduces energy waste.

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

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

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

[0085] In order to reduce the baking time of subsequent batches of battery cells to within the preset time, parameter fine-tuning is performed from two aspects:

[0086] Adjustment of the electrode vacuum rolling process parameters: including increasing the vacuum depth, 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 water and moisture from the electrode.

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

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

[0089] The whole process of parameter adjustment is described below through a specific example:

[0090] Initial setting: The preset duration is 12 hours (based on the current battery positive electrode ratio of 2000m 2 / kg, when the moisture content of the coated roll is 800ppm), the goal is that the cumulative baking time of the same specification battery cells in the next cycle shall not exceed 12 hours.

[0091] Implementation process:

[0092] Moisture content testing after the battery cell baking process: After the battery cell baking process is completed, the moisture content of the battery cell is immediately tested using a Karl Fischer moisture tester. Assume that the moisture content of the battery cell obtained in this test is 450ppm and the baking time is 15 hours.

[0093] Adjustment of pole piece vacuum rolling process parameters:

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

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

[0096] Temperature Adjustment: Raising the core hot-pressing temperature from 95°C to 100°C enhances moisture evaporation while maintaining a range that does not damage the material structure. Pressure Adjustment: Adjusting the vacuum pressure during the preheating and hot-pressing process from -0.07MPa to -0.08MPa more effectively locks in and removes moisture from the core. Time Adjustment: Increasing the preheating and hot-pressing dwell time from 10 minutes to 15 minutes ensures that as much moisture as possible is removed from the core during the hot-pressing process.

[0097] Verify again: In the next cycle of battery cell preparation, vacuum roll pressing of the electrode and vacuum hot pressing of the core are performed according to the adjusted parameters. After completing these processes, the battery cells are baked again, and the changes in moisture content are monitored in real time until the moisture content meets 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 around 350ppm, meeting the preset time requirements and significantly improving the efficiency and effectiveness of moisture control.

[0099] By fine-tuning the parameters of the early 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, thereby improving the efficiency and economy of the entire battery preparation process, while also ensuring the performance stability and reliability of the battery products.

[0100] In traditional processes, the baking time of battery cells is usually fixed. Regardless of the specific surface area of ​​the battery cell's positive electrode material or the moisture content during the coating and unwinding stage, the baking process is carried out according to a predetermined cycle. This may not only lead to energy waste, but for materials with strong water absorption, incomplete moisture removal may also affect battery performance and life. In this embodiment, after the battery cell is baked, the moisture content of the battery cell is immediately detected 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 battery cell has absorbed a lot of water in the early process or the moisture removal efficiency is low. At this time, by adjusting the key parameters in the vacuum rolling process of the electrode sheet and the vacuum hot pressing process of the core, such as temperature, pressure and time, the efficiency of these drying steps can be significantly improved, thereby reducing the time required for subsequent battery cell baking and ensuring that the baking time of the same battery cell specifications in the next round of preparation process can be controlled within a preset reasonable range. The setting of the preset time takes into account the two key factors of the specific surface area of ​​the positive electrode material and the moisture content during the coating and unwinding, making the process adjustment more scientific and reasonable. By adjusting the parameters of the initial electrode sheet vacuum rolling process and / or the core winding vacuum hot pressing process, moisture accumulation can be reduced at the source, making baking easier. This closed-loop feedback mechanism enables precise management of battery cell moisture, improving battery production efficiency and energy utilization while also ensuring battery performance. This is particularly true when processing highly hygroscopic cathode materials, preventing moisture-related battery safety and performance issues.

[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 above-mentioned method further includes: winding the diaphragm, the battery positive electrode sheet processed by the above-mentioned electrode baking process, and the battery negative electrode sheet and placing them into the shell to form a battery core, and the above-mentioned diaphragm is located between the above-mentioned battery positive electrode sheet and the above-mentioned battery negative electrode sheet.

[0102] Specifically, after the vacuum rolling process, the positive and negative electrode sheets are dried to reduce moisture content and enhance the performance and stability of the battery 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 physically separates the positive and negative electrodes, preventing short circuits while allowing ions to flow freely, playing a vital role in charge transport within the battery. Next, using specialized winding equipment, the positive and negative electrode sheets with separators are wound in a specific order and pattern to form a tightly packed battery core. The winding process ensures that the separator is evenly distributed to avoid gaps or wrinkles between the positive and negative electrode sheets, which could affect the battery's internal structure and performance. The wound battery core is then placed in a battery casing. The casing not only encapsulates and protects the core, but also provides the necessary mechanical strength and sealing to protect the battery from external environmental factors.

[0103] During this process, the correct placement of the separator and the tight winding process are crucial, as they directly affect the structural integrity of the battery core, internal impedance, and ultimately the safety and performance of the battery. In particular, since the pole pieces are dried during the vacuum rolling process, the matching and tightness of the separator and pole pieces during winding are extremely important for maintaining a low moisture state in the battery cell. This reduces the amount of moisture that needs to be removed during the subsequent vacuum hot pressing process, thereby reducing the difficulty and energy consumption of the battery cell baking and improving the efficiency of the entire production process.

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

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

[0106] Positive electrodes typically contain more reactive chemical components, such as lithium iron phosphate (LFP), and have a larger surface area. This means they contain higher moisture content and are more difficult to remove. Therefore, a higher first preset temperature is used for baking to accelerate the evaporation rate of moisture and ensure that the moisture content of the positive electrode is minimized 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 and more sensitive to high temperatures, which can easily lead to expansion between graphite layers or structural damage. Therefore, baking the negative electrode at a lower second preset temperature effectively removes moisture while avoiding potential damage to the material, maintaining good electronic conductivity and ion transport capabilities.

[0108] The selection of the first preset temperature and the second preset temperature is based on the characteristics of the positive and negative electrode materials of the battery and the efficiency requirements of moisture removal. By accurately setting different baking temperatures, it is possible to achieve efficient removal and control of moisture based on the respective 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. The higher first preset temperature helps to quickly evaporate the moisture in the positive electrode, while the lower second preset temperature avoids overheating of the negative electrode, protecting the original properties of the material and preventing unnecessary chemical or physical changes. Differentiated temperature control can adjust the baking time according to the characteristics of the material, avoiding the waste of time 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 165-175°C, for example, 167°C, 169°C, 172°C and 175°C can be specifically selected, and the range of the second preset temperature is 85-95°C, for example, 85°C, 88°C, 90°C and 92°C can be specifically selected.

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

[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 of negative electrode sheets (such as graphite materials) is much lower. This is because graphite is more susceptible to structural damage at higher temperatures, affecting its performance as a negative electrode material. The temperature range of 85 to 95°C ensures gentle evaporation of water while avoiding expansion or structural deformation between graphite layers, maintaining its good conductivity and lithium storage capacity as a negative electrode for lithium-ion batteries. Graphite materials have strong thermal stability, but at temperatures close to 100°C, the evaporation rate of water in graphite accelerates. At the same time, excessively high temperatures will cause the interaction between graphite particles to intensify, resulting in changes in interlayer spacing and a decrease in material performance. Therefore, 95°C is used as the upper temperature limit to remove moisture while preserving the original structure of the graphite material to the greatest extent possible. The second preset temperature can 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 water evaporation while maintaining a temperature that does not significantly change the graphite interlayer spacing or damage the structure. Considering the high temperature sensitivity of graphite, the 90°C setting avoids problems such as particle expansion or interlayer adhesion caused by overheating. These problems directly affect the electrochemical performance of the battery, such as reducing energy density and shortening cycle life.

[0112] By setting different baking temperatures, this differentiated control strategy can provide customized baking conditions based on the material properties of the positive and negative electrodes, thereby ensuring efficiency and maintaining material quality during the moisture removal process. The different temperature requirements of the positive and negative electrodes during the baking process enable more intelligent allocation of energy use, avoiding unnecessary high-temperature baking, thereby saving energy consumption and reducing production costs. In short, by setting different temperature ranges, the moisture control accuracy and efficiency in secondary battery production are greatly improved, reducing battery performance losses caused by moisture problems, and thus improving the overall quality and production efficiency of the battery.

[0113] In some embodiments, the temperature parameter in the above-mentioned battery cell baking process ranges from 90 to 100° C., for example, specifically 90° C., 93° C., 96° C., and 100° C. may be selected.

[0114] Specifically, the temperature parameter of 90-100°C was set after comprehensively considering the thermal stability of the battery cell materials, the water evaporation rate, and cost-effectiveness. This temperature range ensures that the battery cell materials (such as the positive and negative electrodes, separators, and electrolyte components) do not undergo structural changes or performance degradation due to overheating during the water removal process. For example, the separator may shrink at higher temperatures, affecting the geometric dimensions and internal structural integrity of the battery cell. Within the temperature range of 90-100°C, the water evaporation rate is significantly increased, ensuring that the battery reaches the ideal dryness 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 water to escape from the battery cell materials. The baking process consumes a lot of energy, so the temperature selection must not only consider the water removal effect, but also comprehensively evaluate energy consumption and production costs. The 90-100°C temperature range was determined after a cost-benefit analysis to achieve efficient water removal without excessive energy waste.

[0115] The selection of a cell baking temperature range of 90-100°C is a comprehensive consideration of cell material properties, production efficiency, and cost-effectiveness. By controlling the temperature within this range, the optimal balance between removing moisture and protecting the cell material properties can be achieved. This temperature range ensures efficient and safe removal of moisture from the cell, which is crucial for improving the overall performance and quality of secondary batteries. It also helps enhance the consistency and reliability of secondary batteries, prolonging their cycle life, and increasing their energy and power density.

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

[0117] Specifically, the pole piece vacuum rolling process aims to shape and compact the pole piece by applying a certain pressure and coordinating with a vacuum environment, while removing the air and moisture inside the pole piece to improve the density and consistency of the pole piece. The pressure value range of 6.5 to 8.5 tons (t) is determined after process optimization, which can ensure that the pole piece material is fully compacted to form a uniform and dense structure, while avoiding excessive pressure that causes deformation or damage to the material and affects battery performance. Within the pressure range of 6.5 to 8.5t, the internal structure of the pole piece is more stable, and the electrical conductivity and mechanical strength are improved, which is conducive to improving the battery energy density and cycle life.

[0118] Temperature parameters affect the shaping ability and moisture removal ability of the pole piece. During the pole piece vacuum rolling process, the increase in temperature helps to soften the pole piece material, making it easier to compact, while accelerating the evaporation of water. The temperature range of 80 to 120°C is set according to the thermal stability and moisture evaporation characteristics of the pole piece material. 80°C is the lower limit for promoting moisture evaporation and material shaping, while 120°C is the upper limit for avoiding structural damage caused by overheating of the material. At an appropriate temperature, the moisture content of the pole piece can be effectively controlled, and at the same time, the physical properties of the material are optimized, thereby improving the stability and safety of the battery.

[0119] The temperature parameter has a temperature range of 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 water evaporation while maintaining a level that does not overheat the material. At this temperature, moisture can be removed more efficiently, reducing the time and energy consumption of subsequent baking processes. 90°C can balance the need to soften the material and avoid the risk of material decomposition, ensuring that the electrode maintains good physical and chemical properties during the compaction process.

[0120] In summary, the temperature parameter in the electrode vacuum rolling process is set between 80°C and 120°C, preferably 90°C, taking into account the need to remove moisture, protect the physical and chemical properties of the material, and ensure process stability and repeatability. This temperature parameter setting helps improve secondary battery performance, extend its cycle life, and ensure safe use.

[0121] The vacuum pressure value is set to create a low-oxygen environment to reduce the amount of air trapped in the electrode during compaction and promote moisture evaporation. This is because moisture evaporates more easily in a low-pressure environment. A vacuum pressure value of -85 to -75 kPa ensures that the gas inside the electrode is fully extracted. At the same time, this vacuum level does not cause excessive pressure on the electrode material, avoiding damage to the material. 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 -75KPa, -84KPa, -80KPa, -78KPa and -74KPa can be specifically selected, with -80KPa being preferred. -80KPa provides a sufficiently low pressure environment that can remove air and moisture inside the electrode to a large extent without damaging the electrode structure. This helps to form more uniform and dense electrodes, improving the electrochemical performance and stability of the battery. Although lower vacuum pressures can further improve gas removal efficiency, they may also cause greater stress to the electrode material, leading to changes or damage to the microstructure. A vacuum pressure value of -80KPa can effectively remove gas while keeping the microstructure of the material intact, ensuring that battery performance is not affected.

[0123] The pole piece vacuum rolling process parameters, including a pressure value of 6.5 to 8.5 tons, a temperature value of 80 to 120 degrees Celsius, and a vacuum pressure value of -85 to -75 kPa, significantly improve the moisture control and pole piece density during the battery production process. Through the precise control of pressure, temperature, and vacuum degree, not only the moisture and air inside the pole piece are effectively removed, reducing the difficulty of baking, but also the microstructure of the pole piece is optimized, and the bonding strength between materials is improved, thereby enhancing the energy density, cycle stability, and safety of the battery. Among them, the setting of the pressure value ensures the uniform compaction of the material, the selection of the temperature range accelerates the evaporation of water without damaging the material performance, and the vacuum pressure value effectively extracts the internal gas. The synergistic effect of the three realizes efficient moisture management in the battery production process, reduces baking energy consumption, reduces production costs, and provides solid technical support for the high-quality and efficient manufacturing of secondary batteries.

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

[0125] Specifically, during the vacuum hot pressing process of the core, the role of the pressure parameter is to fit the positive and negative electrodes and the diaphragm tightly together, eliminate internal gaps, and improve the density of the core. The pressure value range is set to 5.5 to 8.5 tons (t), which ensures the effective bonding of the various layers of the core material while avoiding deformation or damage to the material that may be caused by excessive pressure. The pressure range of 5.5 to 8.5t can effectively improve the compactness of the internal structure of the battery, reduce internal resistance, and thus improve the electrochemical performance and energy density of the battery. The purpose of setting the temperature parameter (90 to 100°C) is to use the heating effect to promote the softening of the electrode and diaphragm during the hot pressing process, making it easier to shape them according to the required structure, while accelerating water evaporation and reducing the moisture content of the core. The temperature range of 90 to 100°C is selected to balance the contradiction between the need to soften the material and avoid thermal damage to the material, ensure the integrity of the material structure and the stability of the function, and effectively control and remove moisture to improve the safety and consistency of the battery.

[0126] During the core vacuum hot pressing process, the vacuum pressure is set to -85 to -75 kPa to create a low-pressure environment during hot pressing. This helps further remove air and moisture from the core, reduces air bubbles, and improves material contact. This vacuum pressure range effectively reduces gas content and residual moisture inside the core, minimizing side reactions during battery charging and discharging, thereby improving battery stability and lifespan.

[0127] The parameters of the core-wound vacuum hot pressing process (pressure 5.5-8.5t, temperature 90-100°C, and vacuum pressure -85-75kPa) work together to significantly improve the density of the battery's internal structure, 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 vacuum pressure further eliminates internal residual gas. The synergistic effect of these three factors helps reduce the battery's internal resistance, increase energy density, and extend the battery's cycle life. It also reduces energy consumption and costs during the baking process, ultimately improving the production efficiency and quality of the finished product.

[0128] To avoid potential blind spots associated with a single moisture detection point, a multi-level moisture detection and response system is established. In some embodiments, multiple detection points are set up at different stages of battery manufacturing, such as after pole powder drying, after pole piece coating, before and after roller pressing, and before and after hot pressing. Each detection point has its own independent moisture detection equipment and 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, extending the drying time, or raising the drying temperature, to restore the moisture content to a safe range as quickly as possible. A graded response mechanism: Level 1 response: Minor exceedance, with a rapid response to adjust the drying air flow or temperature to the normal range by slightly adjusting the drying air flow or temperature. Level 2 response: Moderate exceedance, in addition to adjusting the drying air parameters, additional pre-drying before hot pressing will be initiated to enhance local moisture removal. Level 3 response: Severe exceedance, the system will suspend the current production batch and perform thorough oven drying or introduce special desiccant for deep dehydration until the moisture content fully meets the standard before continuing production.

[0129] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the implementation process of the secondary battery preparation method of the present 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 subsequent slurry performance and battery quality, and ensuring the stability of the electrode powder's physical and chemical properties. The dried positive and negative electrode active materials are then mixed with a binder, conductive agent, solvent, and other materials, respectively, and stirred to form uniform, stable positive and negative electrode slurries, providing suitable materials for coating. The positive and negative electrode slurries are evenly coated onto current collectors (such as positive electrode aluminum foil and negative electrode copper foil), forming a coating of a desired thickness and shape, establishing the basic structure for the battery reaction. The coated positive and negative electrode sheets are then baked, followed by vacuum rolling. This involves first applying vacuum and then replenishing dry gas during the rolling process. The separator, the positive and negative electrode sheets (after the baking process), and the battery casing are then wound to form a battery core, with the separator positioned between the positive and negative electrode sheets. This is followed by preheating and hot pressing, a process known as core vacuum hot pressing (which involves first applying vacuum and then replenishing dry gas). The pre-treated battery cell components, including the positive electrode sheet, negative electrode sheet, and separator, are combined with other necessary battery components to form a complete battery cell unit. A battery cell baking process (battery cell drying) is performed. During the battery cell baking process, the initial battery cells are baked for a corresponding period of time based on the moisture content of the battery cells before baking. Electrolyte is injected into the assembled battery housing. The electrolyte acts as a medium for ion transmission, ensuring the movement of ions during the battery's charge and discharge process. This is followed by the formation step, which involves performing the initial charge and other operations on the battery after the electrolyte injection to form a stable solid electrolyte interface film. The solid electrolyte interface film can protect the electrodes and inhibit side reactions. The capacity separation step is then followed, which involves testing the battery's performance indicators such as capacity and internal resistance to screen out qualified products and distinguish different capacity levels for subsequent matching and application. The batteries after capacity separation are subjected to comprehensive performance testing, such as voltage, internal resistance, self-discharge, and cycle performance, to ensure product quality. Batteries that pass the test are packaged and coated, etc., to protect the battery and 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 positive electrode material is between 0.6 and 1.0 m 2 / g range, suitable for moderately hygroscopic materials. The initial coating moisture of the positive electrode (moisture content during rolling after coating) is controlled at 690-700ppm. Standard graphite material is used as the negative electrode material without changing its properties or moisture control method. 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 distribution of the slurry and initial drying is performed at the same time, but vacuum drying technology is not used. The positive and negative electrode sheets are mechanically rolled at room temperature without introducing vacuum drying to maintain the original physical properties and chemical composition of the material. 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°C, 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 sheet is effectively removed, preparing materials with lower moisture for subsequent winding and baking. Through pre-pressing optimization, the baking time of the battery cells at 90°C has been significantly reduced, with the specific baking time recorded as between 6 and 8 hours based on experimental results. The moisture content before baking is controlled at 590-600ppm. Compared with traditional processes, this significantly shortens the baking cycle and reduces energy consumption while ensuring the battery's moisture content meets standards.

[0133] Comparative Example 1

[0134] The specific surface area of ​​the positive electrode material is also between 0.6 and 1.0 m 2 / g range, and has the same material properties as Example 1. The initial coating moisture of the positive electrode (moisture content after coating) is controlled at 690-700ppm, which is the same as Example 1. Standard graphite material is used as the negative electrode material, and no additional moisture control measures are taken. The initial moisture content is equivalent to that of the positive electrode material. The positive and negative electrode sheets are processed using standard coating technology and drying equipment, and no vacuum drying or drying treatment before preheating and hot pressing is introduced. The sheets are mechanically rolled at room temperature without an additional vacuum drying step. Vacuum drying technology is not used before preheating and hot pressing, and the core is hot pressed under conventional conditions. In the absence of drying optimization before hot pressing, the moisture content of the battery cell before baking is estimated to be 790-800ppm. In order to meet the moisture standard, the battery cell must be baked at 90°C for a long time. The specific baking time is recorded as between 18 hours and 20 hours based on experimental data. The extension of baking time not only increases energy consumption, but may also have an adverse effect on the long-term performance of the battery.

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

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

[0137]

[0138] Example 2

[0139] The specific surface area of ​​the positive electrode material is between 1.1 and 1.5 m 2 / g range, this type of material has stronger hygroscopicity due to its large surface area. The initial coating moisture of the positive electrode (moisture content after coating) is controlled at 790-800ppm, with a higher initial moisture content. The negative electrode material uses standard graphite material without changing its properties or moisture control method. Vacuum drying technology is used before rolling and before preheating and hot pressing to deeply remove moisture from the inside of the material and reduce the difficulty of subsequent baking. After a two-stage vacuum drying treatment, the moisture content before baking is optimized to 490-500ppm, which is significantly lower than the initial moisture content, which provides a basis for subsequent rapid baking. Since the moisture content is effectively controlled in the early stage, the baking time of the battery cell at 90°C can be shortened to 6 hours, which greatly reduces energy consumption and processing time compared to traditional processes.

[0140] Comparative Example 2

[0141] The specific surface area of ​​the positive electrode material is also between 1.1 and 1.5 m 2 / g range, has the same material properties as Example 2, and initially has a strong moisture absorption capacity. The initial coating moisture of the positive electrode (moisture content after coating) is controlled at 790-800ppm, the same as Example 2. Standard graphite material is used as the negative electrode material, and no additional moisture control measures are taken. Vacuum drying technology was introduced only before preheating and hot pressing, and no vacuum drying treatment was performed before rolling, which limited the comprehensiveness of moisture control. Although vacuum drying was performed before preheating and hot pressing, due to the lack of a drying step before rolling, the moisture control effect before baking was not as significant as in Example 2, and the moisture content was expected to be between 640 and 650ppm. Due to the high moisture content before baking, it takes at least 12 hours for the battery cell to reach the ideal moisture standard after baking at 90°C, 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 positive electrode material is also between 1.1 and 1.5 m 2 / g range, and has the same material properties as Example 2, and initially has a strong moisture absorption capacity. The initial coating moisture of the positive electrode (moisture content during coating and rolling) is controlled at 790-800ppm, the same as Example 2. Standard graphite material is used as the negative electrode material, and no additional moisture control measures are taken. Vacuum drying treatment is only used before preheating and hot pressing, and no vacuum drying is performed before rolling, which may cause some moisture to remain inside the electrode piece. Due to the lack of a vacuum drying step before rolling, the moisture content of Comparative Example 3 before baking is higher, and is expected to be between 740 and 750ppm. In order to remove more moisture, the baking time of the battery cell at 90°C needs to be extended to 12 to 14 hours. Compared with Example 2, the baking time is significantly increased, and the energy consumption also increases accordingly.

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

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

[0146]

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

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

[0149]

[0150] Therefore, Example 1 of the present application has technical advantages in terms of both moisture before baking and baking time.

[0151] The embodiment of the present application also provides a device for preparing a secondary battery, which includes a pole piece baking device, a pole piece vacuum rolling device, a core vacuum hot pressing device and a battery cell baking device. The pole piece baking device is used to perform the steps of the pole piece baking process, in which the above-mentioned battery pole piece obtained after the coating process is baked at a preset temperature; the pole piece vacuum rolling device is used to perform the steps of the pole piece vacuum rolling process; the core vacuum hot pressing device is used to perform the steps of the core vacuum hot pressing process; according to the battery positive electrode ratio table and / or the battery coating roll moisture, it is determined whether to perform the pole piece vacuum rolling process and the core vacuum hot pressing process after the pole piece baking process and before the battery cell baking process, wherein the battery positive electrode ratio table is the specific surface area of ​​the battery positive electrode, and the battery coating roll moisture is divided into the pole piece baking process and the battery coating roll moisture. The residual moisture content of the battery electrode when it is rolled up after the process is processed. The electrode vacuum rolling process is characterized by first evacuating the vacuum and then adding dry gas during the electrode rolling process. The core vacuum hot pressing process is characterized by first evacuating the vacuum and then adding dry gas during the core hot pressing process. Among them, the temperature value range of the temperature parameter of the rolling equipment during the electrode rolling process is different from the temperature value range of the temperature parameter of the hot pressing equipment during the core hot pressing process; the battery cell baking equipment is used to execute the steps of the battery cell baking process, and in the steps of the battery cell baking process, the initial battery cell is baked for a corresponding time based on the moisture content of the battery cell before baking.

[0152] By precisely controlling the drying process, the moisture content in the battery manufacturing process is effectively managed, significantly improving battery performance and production efficiency. By implementing a pole piece baking process on the battery pole pieces, the initial drying of the pole pieces after coating is ensured. Depending on the specific surface area of ​​the battery's positive pole pieces and the amount of residual moisture after coating and unwinding, the choice of pole piece vacuum rolling process and core vacuum hot pressing process is made. These processes, by first vacuuming and then replenishing the drying gas, can specifically reduce the moisture content of highly absorbent materials or pole pieces with high residual moisture, without requiring such intensive drying in all cases, thus avoiding excessive resource consumption. The battery cell baking process dynamically adjusts the baking time based on the moisture content of the battery cells before baking, ensuring that each batch of battery cells reaches the ideal dry state, avoiding the problems of residual moisture or over-drying. In short, this embodiment replaces the electrode rolling process in the prior art with a electrode vacuum rolling process, and the core hot pressing process with a core vacuum hot pressing process, and removes moisture by vacuuming and filling with dry air, thereby improving the control accuracy of the moisture content, and the baking time of the subsequent battery cell baking process can be greatly shortened, solving the problem of low control accuracy of the moisture content of the battery cell in the secondary battery preparation process in the prior art.

[0153] In some embodiments, the secondary battery preparation device includes a pole piece rolling device and a core hot pressing device. When the positive electrode ratio of the battery is within a first preset ratio range, and / or the moisture content of the battery coating is within a first preset moisture range, it is determined that after the pole piece baking process and before the battery cell baking process, the pole piece vacuum rolling device does not perform the pole piece vacuum rolling process, the core vacuum hot pressing device does not perform the core vacuum hot pressing process, the pole piece rolling device performs the pole piece rolling process, and the core hot pressing device performs the core hot pressing process.

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

[0155] When the battery positive electrode ratio is within the third preset ratio range, and / or the battery coating lower roll moisture is within the third preset moisture range, determining that after the electrode baking process and before the battery cell baking process, the electrode vacuum rolling device performs the electrode vacuum rolling process, and the core vacuum hot pressing device performs the core vacuum hot pressing process;

[0156] Among them, the maximum value of the first preset ratio range is smaller than the minimum value of the above-mentioned second preset ratio range, and the maximum value of the above-mentioned second preset ratio range is smaller than the minimum value of the above-mentioned third preset ratio range; the maximum value of the above-mentioned first preset moisture range is smaller than the minimum value of the above-mentioned second preset moisture range, and the maximum value of the above-mentioned second preset moisture range is smaller than the minimum value of the above-mentioned third preset ratio range.

[0157] The above equipment enables differentiated drying treatment based on the battery positive electrode specific surface and the moisture content of the battery coating roll, significantly improving the accuracy and efficiency of moisture control in the secondary battery preparation process. By setting different preset ranges and corresponding drying process intensities, it is possible to ensure the drying quality of the battery cells while avoiding resource waste and possible material damage caused by over-drying, thereby improving production efficiency and energy utilization efficiency. This hierarchical processing strategy not only enhances the flexibility of moisture control, but also ensures that the battery cells can reach the ideal moisture level even in the application scenario of highly absorbent materials, significantly improving the performance consistency of the battery and the controllability of the manufacturing process.

[0158] The first preset moisture range is ≤600ppm, and the first preset ratio range is ≤0.5m 2 / g; the second preset moisture range is 601~700ppm, the second preset ratio range is 0.6~1.0m 2 / g; the third preset moisture range is 701~800ppm, the third preset ratio range is 1.1~1.5m 2 / g.

[0159] By setting the above-mentioned preset moisture ranges and preset ratio ranges, refined management of moisture control in the battery preparation process is achieved, and the drying process can be flexibly adjusted according to material properties, which not only avoids unnecessary energy waste but also ensures the consistency and high quality of battery production.

[0160] In some embodiments, the electrode sheet vacuum rolling equipment includes a vacuum pumping sub-equipment, a dry gas supply sub-equipment, and a rolling sub-equipment. The vacuum pumping sub-equipment is used to perform a vacuuming step, evacuating the chamber of the roller press; the dry gas supply sub-equipment is used to perform a dry gas supply step, replenishing the dry gas into the chamber after the vacuuming step; and the rolling sub-equipment is used to perform a rolling step, after which the battery electrode sheets are unfolded and rolled.

[0161] By implementing the electrode vacuum rolling process, the moisture management effect of the electrode in the secondary battery preparation process has been significantly improved. During the vacuuming step, the humidity of the cavity where the roller press is located is effectively reduced, creating a dry environment for subsequent processing. The subsequent dry gas replenishment step completely replaces the moisture in the cavity by introducing dry gas, ensuring that the electrode is in the optimal low-moisture state before contact rolling. The rolling step carried out in a dry gas environment not only achieves precise control of the physical morphology of the electrode, but also utilizes dry conditions to promote the discharge of residual moisture inside the electrode, thereby significantly reducing the initial moisture content before the battery cell is baked. Overall, this process effectively controls the moisture content of the electrode, reduces the time and energy consumption required for subsequent battery cell baking, and improves the efficiency of battery production and product quality.

[0162] In some embodiments, the core vacuum hot pressing apparatus includes a vacuum pumping sub-device, a dry gas replenishing sub-device, and a hot pressing sub-device. The vacuum pumping sub-device is used to perform a vacuuming step, evacuating the chamber of the hot press; the dry gas replenishing sub-device is used to perform a dry gas replenishing step, replenishing the dry gas into the chamber after the vacuuming step; and the hot pressing sub-device is used to perform a hot pressing step, hot pressing the battery core after the dry gas replenishing step.

[0163] The core vacuum hot pressing process significantly reduces the moisture absorption of the battery core during the hot pressing process by evacuating the hot press cavity and replenishing dry gas before hot pressing, thereby improving the preparation quality of secondary batteries. First, a water-free or low-moisture hot pressing environment is created, which effectively prevents the core from increasing moisture during the hot pressing device due to ambient humidity, avoiding the complexity and energy consumption of subsequent battery cell baking. The introduction of dry gas ensures that the humidity of the internal pores and material interfaces of the core is maintained at a low level, which helps to quickly volatilize residual moisture, thereby achieving more efficient moisture control during the hot pressing process. The hot pressing step is carried out in the presence of dry gas, which not only enhances the structural stability of the core, but also further reduces its moisture content. In short, the core vacuum hot pressing process effectively reduces production costs and improves the reliability and performance of batteries.

[0164] In some embodiments, the above-mentioned device is also used to obtain the cumulative time of the above-mentioned battery cell baking process when the moisture content of the above-mentioned initial battery cell meets the requirements; when the cumulative time of the above-mentioned battery cell baking process is greater than the preset time, the parameters of the above-mentioned electrode vacuum rolling process and / or the parameters of the above-mentioned core vacuum hot pressing process are adjusted so that the battery cells of the same specifications are subjected to the above-mentioned battery cell baking process in the subsequent preparation process for a time less than or equal to the above-mentioned preset time, wherein the above-mentioned preset time is positively correlated with the above-mentioned battery positive electrode ratio table, and the above-mentioned preset time is positively correlated with the moisture content of the above-mentioned battery coating roll.

[0165] In traditional processes, the baking time of battery cells is usually fixed. Regardless of the specific surface area of ​​the battery cell's positive electrode material or the moisture content during the coating and unwinding stage, the baking process is carried out according to a predetermined cycle. This may not only lead to energy waste, but for materials with strong water absorption, incomplete moisture removal may also affect battery performance and life. In this embodiment, after the battery cell is baked, the moisture content of the battery cell is immediately detected 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 battery cell has absorbed a lot of water in the early process or the moisture removal efficiency is low. At this time, by adjusting the key parameters in the vacuum rolling process of the electrode sheet and the vacuum hot pressing process of the core, such as temperature, pressure and time, the efficiency of these drying steps can be significantly improved, thereby reducing the time required for subsequent battery cell baking and ensuring that the baking time of the same battery cell specifications in the next round of preparation process can be controlled within a preset reasonable range. The setting of the preset time takes into account the two key factors of the specific surface area of ​​the positive electrode material and the moisture content during the coating and unwinding, making the process adjustment more scientific and reasonable. By adjusting the parameters of the initial electrode sheet vacuum rolling process and / or the core winding vacuum hot pressing process, moisture accumulation can be reduced at the source, making baking easier. This closed-loop feedback mechanism enables precise management of battery cell moisture, improving battery production efficiency and energy utilization while also ensuring battery performance. This is particularly true when processing highly hygroscopic cathode materials, preventing moisture-related battery safety and performance issues.

[0166] In some embodiments, the above-mentioned device is also used to wind the diaphragm, the battery positive electrode sheet processed by the above-mentioned electrode sheet baking process, and the battery negative electrode sheet and place them into the shell after the above-mentioned electrode sheet vacuum rolling process and before the above-mentioned core vacuum hot pressing process to form a battery core, and the above-mentioned diaphragm is located between the above-mentioned battery positive electrode sheet and the above-mentioned battery negative electrode sheet.

[0167] During this process, the correct placement of the separator and the tight winding process are crucial, as they directly affect the structural integrity of the battery core, internal impedance, and ultimately the safety and performance of the battery. In particular, since the pole pieces are dried during the vacuum rolling process, the matching and tightness of the separator and pole pieces during winding are extremely important for maintaining a low moisture state in the battery cell. This reduces the amount of moisture that needs to be removed during the subsequent vacuum hot pressing process, thereby reducing the difficulty and energy consumption of the battery cell baking and improving the efficiency of the entire production process.

[0168] In some embodiments, the above-mentioned electrode baking equipment is used to perform the above-mentioned electrode baking process on the above-mentioned battery electrode, and the first preset temperature is used in the above-mentioned electrode baking process to bake the above-mentioned battery positive electrode obtained after the coating process; the above-mentioned electrode baking process is performed on the above-mentioned battery electrode, and the second preset temperature is used in the above-mentioned electrode baking process to bake the battery negative electrode obtained after the coating process, wherein the above-mentioned first preset temperature is greater than the above-mentioned second preset temperature.

[0169] The selection of the first preset temperature and the second preset temperature is based on the characteristics of the positive and negative electrode materials of the battery and the efficiency requirements of moisture removal. By accurately setting different baking temperatures, it is possible to achieve efficient removal and control of moisture based on the respective 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. The higher first preset temperature helps to quickly evaporate the moisture in the positive electrode, while the lower second preset temperature avoids overheating of the negative electrode, protecting the original properties of the material and preventing unnecessary chemical or physical changes. Differentiated temperature control can adjust the baking time according to the characteristics of the material, avoiding the waste of time 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°C to 175°C, and the second preset temperature ranges from 85°C to 95°C.

[0171] By setting different baking temperatures, this differentiated control strategy can provide customized baking conditions based on the material properties of the positive and negative electrodes, thereby ensuring efficiency and maintaining material quality during the moisture removal process. The different temperature requirements of the positive and negative electrodes during the baking process enable more intelligent allocation of energy use, avoiding unnecessary high-temperature baking, thereby saving energy consumption and reducing production costs. In short, by setting different temperature ranges, the moisture control accuracy and efficiency in secondary battery production are greatly improved, reducing battery performance losses caused by moisture problems, and thus improving the overall quality and production efficiency of the battery.

[0172] In some embodiments, the temperature parameter in the battery cell baking process ranges from 90° C. to 100° C.

[0173] The selection of a cell baking temperature range of 90-100°C is a comprehensive consideration of cell material properties, production efficiency, and cost-effectiveness. By controlling the temperature within this range, the optimal balance between removing moisture and protecting the cell material properties can be achieved. This temperature range ensures efficient and safe removal of moisture from the cell, which is crucial for improving the overall performance and quality of secondary batteries. It also helps enhance the consistency and reliability of secondary batteries, prolonging their cycle life, and increasing their energy and power density.

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

[0175] The pole piece vacuum rolling process parameters, including a pressure value of 6.5 to 8.5 tons, a temperature value of 80 to 120 degrees Celsius, and a vacuum pressure value of -85 to -75 kPa, significantly improve the moisture control and pole piece density during the battery production process. Through the precise control of pressure, temperature, and vacuum degree, not only the moisture and air inside the pole piece are effectively removed, reducing the difficulty of baking, but also the microstructure of the pole piece is optimized, and the bonding strength between materials is improved, thereby enhancing the energy density, cycle stability, and safety of the battery. Among them, the setting of the pressure value ensures the uniform compaction of the material, the selection of the temperature range accelerates the evaporation of water without damaging the material performance, and the vacuum pressure value effectively extracts the internal gas. The synergistic effect of the three realizes efficient moisture management in the battery production process, reduces baking energy consumption, reduces production costs, and provides solid technical support for the high-quality and efficient manufacturing of secondary batteries.

[0176] In some embodiments, the pressure parameter of the core vacuum hot pressing process is in the range of 5.5 to 8.5t, the temperature parameter is in the range of 90 to 100°C, and the vacuum pressure is in the range of -85 to -75KPa.

[0177] The parameters of the core-wound vacuum hot pressing process (pressure 5.5-8.5t, temperature 90-100°C, and vacuum pressure -85-75kPa) work together to significantly improve the density of the battery's internal structure, 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 vacuum pressure further eliminates internal residual gas. The synergistic effect of these three factors helps reduce the battery's internal resistance, increase energy density, and extend the battery's cycle life. It also reduces energy consumption and costs during the baking process, ultimately improving the production efficiency and quality of the finished product.

[0178] An embodiment of the present application further provides a secondary battery, which is prepared by using any of the above-mentioned methods for preparing a secondary battery.

[0179] An embodiment of the present application also provides an energy storage system, comprising at least one of the above-mentioned secondary batteries.

[0180] An embodiment of the present application further provides an electrical device comprising at least one of the above-mentioned secondary batteries or the above-mentioned energy storage system.

[0181] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0182] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a secondary battery, characterized in that: include: Performing a pole piece baking process on the battery pole piece, wherein the pole piece baking process adopts a preset temperature to bake the battery pole piece obtained after the coating process; Determine whether to perform a pole piece vacuum rolling process and a core vacuum hot pressing process after the pole piece baking process and before the battery cell baking process according to the battery positive electrode ratio table and / or the battery coating roll moisture, wherein the battery positive electrode ratio table is the specific surface area of ​​the battery positive pole piece, the battery coating roll moisture is the residual moisture content of the battery pole piece when it is rolled up after the pole piece baking process, the pole piece vacuum rolling process is characterized by first evacuating the vacuum and then adding dry gas during the pole piece rolling process, and the core vacuum hot pressing process is characterized by first evacuating the vacuum and then adding dry gas during the core hot pressing process; The battery cell baking process is performed, wherein the initial battery cells are baked for a corresponding time based on the moisture content of the battery cells before baking.

2. The method for preparing a secondary battery according to claim 1, wherein: Determining whether to perform a pole piece vacuum rolling process and a core vacuum hot pressing process after performing the pole piece baking process and before performing the battery cell baking process based on the battery positive electrode ratio table and / or the battery coating lower roll moisture content includes: When the battery positive electrode ratio is within a first preset ratio range, and / or the battery coating lower roll moisture is within a first preset moisture range, determining that after the electrode baking process and before the battery cell baking process, the electrode sheet vacuum rolling process and the core vacuum hot pressing process are not performed, and the electrode sheet rolling process and the core hot pressing process are performed instead; When the battery positive electrode ratio is within a second preset ratio range, and / or the battery coating lower roll moisture is within a second preset moisture range, determining that after the electrode sheet baking process and before the battery cell baking process, the electrode sheet vacuum rolling process is not performed but the core roll vacuum hot pressing process is performed, and the electrode sheet rolling process is performed; When the battery positive electrode ratio is within a third preset ratio range, and / or the battery coating lower roll moisture is within a third preset moisture range, determining to perform the electrode sheet vacuum rolling process and the core roll vacuum hot pressing process after performing the electrode sheet baking process and before performing the battery cell baking process; Among them, the maximum value of the first preset ratio range is smaller than the minimum value of the second preset ratio range, and the maximum value of the second preset ratio range is smaller than the minimum value of the third preset ratio range; the maximum value of the first preset moisture range is smaller than the minimum value of the second preset moisture range, and the maximum value of the second preset moisture range is smaller than the minimum value of the third preset ratio range.

3. The method for preparing a secondary battery according to claim 2, wherein: The first preset moisture range is ≤600ppm, and the first preset ratio range is ≤0.5m 2 / g; The second preset moisture range is 601-700 ppm, and the second preset ratio range is 0.6-1.0m 2 / g; The third preset moisture range is 701-800 ppm, and the third preset ratio range is 1.1-1.5m 2 / g.

4. The method for preparing a secondary battery according to claim 1, wherein: The steps of the pole piece vacuum rolling process include: Vacuuming step: vacuuming the cavity where the roller press is located; A step of replenishing dry gas: replenishing the dry gas into the chamber after the vacuuming process; Rolling step: rolling the battery pole piece after performing the drying gas supplementing step.

5. The method for preparing a secondary battery according to claim 1, wherein: The steps of the core vacuum hot pressing process include: Vacuuming step: vacuuming the cavity where the hot press is located; A step of replenishing dry gas: replenishing the dry gas into the chamber after the vacuuming process; Hot pressing step: After the dry gas supplementation step, the battery core is subjected to hot pressing.

6. The method for preparing a secondary battery according to claim 1, wherein: After performing the battery cell baking process, the method further includes: Obtaining the cumulative time of the battery cell baking process when the moisture content of the initial battery cell meets the requirement; When the cumulative duration of the battery cell baking process is greater than the preset duration, the parameters of the electrode vacuum rolling process and / or the parameters of the core vacuum hot pressing process are adjusted so that the duration of the battery cell baking process for battery cells of the same specification in the subsequent preparation process is less than or equal to the preset duration, wherein the preset duration is positively correlated with the battery positive electrode ratio table, and the preset duration is positively correlated with the moisture content of the battery coating roll.

7. The method for preparing a secondary battery according to claim 1, wherein: After performing the pole piece vacuum rolling process and before performing the core vacuum hot pressing process, the method further includes: The separator, the battery positive electrode sheet processed by the electrode sheet baking process, and the battery negative electrode sheet are wound and placed into a shell to form a battery roll core, and the separator is located between the battery positive electrode sheet and the battery negative electrode sheet.

8. The method for preparing a secondary battery according to claim 1, wherein: The battery electrode is subjected to a electrode baking process, wherein the electrode baking process uses a preset temperature to bake the battery electrode obtained after the coating process, including: Performing the electrode baking process on the battery electrode, wherein the electrode baking process adopts a first preset temperature to bake the battery positive electrode obtained after the coating process; The battery electrode is subjected to the electrode baking process, wherein a second preset temperature is used to bake the battery negative electrode obtained after the coating process, wherein the first preset temperature is greater than the second preset temperature.

9. The method for preparing a secondary battery according to claim 8, wherein: 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, wherein: The temperature parameter range of the battery cell baking process is 90-100°C.

11. The method for preparing a secondary battery according to any one of claims 1 to 10, characterized in that: The pressure parameter in the electrode vacuum rolling process has a pressure value ranging from 6.5 to 8.5 kPa, the temperature parameter has a temperature value ranging from 80 to 120 °C, and the vacuum pressure value ranges from -85 to -75 kPa.

12. The method for preparing a secondary battery according to any one of claims 1 to 10, characterized in that: The pressure parameter of the core vacuum hot pressing process has a pressure value range of 5.5 to 8.5t, the temperature parameter has a temperature value of 90 to 100°C, and the vacuum pressure value is -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 according to claim 13.

15. An electrical device, characterized in that: include: At least one secondary battery according to claim 13 or the energy storage system according to claim 14.

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