Secondary battery and manufacturing method, manufacturing equipment, energy storage system and electrical equipment

Abstract

The embodiments of the present application relate to the field of secondary batteries, and provide a secondary battery and its manufacturing method, manufacturing equipment, energy storage system, and electrical equipment, wherein the manufacturing method of the secondary battery includes: providing a battery cell and injecting an electrolyte; performing a first detection step to obtain a first resistance value of the battery cell, judging whether the battery cell is a first self-discharge defective battery cell based on the first preset resistance value, if not, the battery cell is judged to be a first pass battery cell, and performing a formation treatment on the first pass battery cell; performing a second detection step to obtain a first open circuit voltage value of the first pass battery cell, judging whether the first pass battery cell is a second self-discharge defective battery cell based on the first preset open circuit voltage value, if not, it is judged to be a second pass battery cell; in the first detection step, the formation treatment, and the second detection step, the bare battery cell in the battery cell is tested at a first detection pressure and a first detection temperature. The present application can at least save the static time for measuring the K value, shorten the production cycle, and reduce production costs.

Description

Technical Field

[0001] The present application relates to the field of secondary batteries, and in particular to a secondary battery and a manufacturing method, manufacturing equipment, energy storage system and electrical equipment thereof. Background Art

[0002] Lithium-ion battery self-discharge refers to the spontaneous loss of capacity when left in an open circuit. If a single battery from the same batch, using essentially identical materials and process controls, exhibits significantly excessive self-discharge, it's likely due to a severe micro-short circuit caused by structural anomalies or electrochemical defects caused by component defects. Self-discharge testing is a crucial component of secondary battery manufacturing.

[0003] The current self-discharge detection method in the industry generally uses the open circuit voltage decay rate measurement method. The open circuit voltage is directly related to the battery's state of charge (SOC). It only needs to measure the rate of change of the battery's OCV over a period of time, that is, K = ΔOCV / Δt. The battery voltage change over a period of time is recorded, and the battery's self-discharge rate can be calculated through the voltage decay and the time interval between two voltage measurements. Usually, the battery needs to be left in a high-temperature environment for a period of time before self-discharge detection. The self-discharge detection process also requires a period of high-temperature standing to measure the rate of change of the battery's OCV during the standing time. The existing standing method generally takes 5 to 30 days, which occupies most of the manufacturing cycle of the secondary battery, resulting in high standing time costs and a long manufacturing cycle of the secondary battery.

[0004] Therefore, how to solve the problem of long manufacturing cycle of secondary batteries is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The embodiments of the present application provide a secondary battery and a manufacturing method, manufacturing equipment, energy storage system and electrical equipment thereof, which at least help to solve the problem of long manufacturing cycle of secondary batteries.

[0006] According to some embodiments of the present application, on one hand, a method for manufacturing a secondary battery is provided, comprising:

[0007] Providing a battery cell, the battery cell comprising a shell and a bare battery cell located in the shell, and injecting an electrolyte into the shell;

[0008] performing a first detection step to obtain a first resistance value of the battery cell; if the first resistance value is less than or equal to a first preset resistance value, the battery cell is determined to be a first self-discharge defective battery cell; if the first resistance value is greater than the first preset resistance value, the battery cell is determined to be a first pass battery cell, and a formation process is performed on the first pass battery cell;

[0009] Performing a formation treatment on the first pass battery cell, wherein the formation treatment is performed within a formation time and at a formation current;

[0010] performing a second detection step to obtain a first open circuit voltage value of the first passing cell; if the first open circuit voltage value is less than or equal to a first preset open circuit voltage value, the first passing cell is determined to be a second self-discharge defective cell; if the first open circuit voltage value is greater than the first preset open circuit voltage value, the first passing cell is determined to be a second passing cell;

[0011] Wherein, in the first detection step, the formation treatment and the second detection step, the bare cell is subjected to a first detection pressure and a first detection temperature.

[0012] In some embodiments, the first detection pressure is 0.1 MPa~0.8 MPa.

[0013] In some embodiments, the first detection temperature is 35°C to 50°C.

[0014] In some embodiments, the first preset resistance value is 0.15Ω-0.2Ω.

[0015] In some embodiments, the first preset open circuit voltage value is 2.0V-4.0V.

[0016] In some embodiments, the formation time is 200 min to 500 min, and the formation current is 0.1 C to 0.5 C.

[0017] In some embodiments, the first detection step further includes a second preset resistance value, wherein the second preset resistance value is greater than the first preset resistance value; if the first resistance value is greater than the first preset resistance value and less than or equal to the second preset resistance value, the first passing cell is determined to be a first suspected defective cell;

[0018] performing the formation treatment on the first suspected defective battery cell;

[0019] performing a charge adjustment step, discharging the first suspected defective cell to discharge the first suspected defective cell to a state of charge of 0; performing a recharge process on the first suspected defective cell, the recharge process being performed under a recharge time and a recharge current;

[0020] performing a third detection step to obtain a second open circuit voltage value of the first suspected defective battery cell; if the second open circuit voltage value is less than or equal to a second preset open circuit voltage value, the first suspected defective battery cell is determined to be a third self-discharging defective battery cell;

[0021] Wherein, in the charge adjustment step and the third detection step, the bare cell is tested at a second detection temperature and a second detection pressure.

[0022] In some embodiments, the second detection step further includes a third preset open circuit voltage value, wherein the third preset open circuit voltage value is greater than the first preset open circuit voltage value; if the first open circuit voltage value is greater than the first preset open circuit voltage value and less than or equal to the third preset open circuit voltage value, the second passing cell is determined to be a second suspected defective cell;

[0023] performing a charge adjustment step to discharge the second suspected defective cell to a state of charge of 0; and recharging the second suspected defective cell, wherein the recharging is performed at a recharging time and a recharging current;

[0024] performing a third detection step to obtain a second open circuit voltage value of the second suspected defective battery cell; if the second open circuit voltage value is less than or equal to a second preset open circuit voltage value, the second suspected defective battery cell is determined to be a third self-discharging defective battery cell;

[0025] Wherein, in the charge adjustment step and the third detection step, the bare cell is tested at a second detection temperature and a second detection pressure.

[0026] In some embodiments, the second preset resistance value is 0.2Ω-0.25Ω.

[0027] In some embodiments, the third preset open circuit voltage value is 2.0V-5.0V.

[0028] In some embodiments, the second detection pressure is 0.1-0.8 MPa; the second detection temperature is 20° C.-50° C.

[0029] In some embodiments, the second open circuit voltage is 2.5V to 4.5V.

[0030] In some embodiments, the charging time is 200 min to 400 min, and the charging current is 0.2C to 0.5C.

[0031] In some embodiments, after providing the battery cell, the battery cell is subjected to a static treatment;

[0032] Wherein, during the static treatment, the bare battery cell is subjected to the first detection pressure and the first detection temperature; and the static treatment time of the battery cell is 27 hours to 36 hours.

[0033] According to some embodiments of the present application, another aspect of the present application further provides a secondary battery, wherein the secondary battery is obtained by the manufacturing method of the secondary battery as described above, and the secondary battery includes a battery cell, wherein the battery cell includes:

[0034] A housing having an accommodating cavity therein;

[0035] A bare battery cell, the bare battery cell being accommodated in the accommodation cavity;

[0036] An electrolyte is contained in the containing cavity, and the bare battery cell is at least partially immersed in the electrolyte.

[0037] According to some embodiments of the present application, another aspect of the present application further provides a manufacturing device, wherein the manufacturing device is used to implement the manufacturing method of the secondary battery as described above, and the manufacturing device includes:

[0038] A pressure control device, used to clamp the battery cell and adjust the pressure value applied to the bare battery cell in the battery cell; the pressure control device includes an upper pressure plate and a lower pressure plate, the upper pressure plate and the lower pressure plate are arranged opposite to each other to clamp the battery cell;

[0039] A thermostatic device, comprising a temperature regulating module, a water supply pipeline, and a water return pipeline; the temperature regulating module is connected to the water supply pipeline and the water return pipeline to form a loop, a thermal fluid circulates in the loop, and the temperature regulating module regulates the temperature of the thermal fluid;

[0040] Wherein, a flow channel is provided in the upper pressing plate and the lower pressing plate, the water inlet of the flow channel is connected to the water supply pipeline, and the water outlet of the flow channel is connected to the return pipeline to adjust the temperature of the bare battery cell.

[0041] In some embodiments, a temperature and pressure collection device is further included to collect the temperature and pressure of the battery cell, wherein the temperature and pressure collection device includes a temperature and pressure probe, and the temperature and pressure probe is in contact with the battery cell;

[0042] An electrical performance detection device is electrically connected to the battery cell and is used to detect the resistance value and open circuit voltage value of the battery cell.

[0043] According to some embodiments of the present application, the embodiments of the present application further provide an energy storage system, including a secondary battery obtained by the manufacturing method of the secondary battery as described above, or the secondary battery described above.

[0044] According to some embodiments of the present application, the embodiments of the present application further provide an electrical device, including a secondary battery obtained by the secondary battery manufacturing method as described above, or the secondary battery described above.

[0045] The technical solution provided by the embodiment of the present application has at least the following advantages: the temperature state and pressure state of the battery cell after the liquid injection treatment are adjusted and maintained at the same state, the battery cell in this state is subjected to a formation treatment, and the resistance value and open circuit voltage value are respectively detected before and after the formation treatment, and the preset resistance value and the preset open circuit voltage value are respectively compared to determine whether the battery cell is a self-discharging poor battery cell. Compared with the self-discharge detection method of measuring the K value of the secondary battery in the related art, the embodiment of the present application does not require the K value to determine whether the battery cell is a self-discharging poor battery cell, eliminating the static time required in the process of measuring the K value of the secondary battery, and eliminating the energy consumption cost generated during the static process, greatly shortening the manufacturing cycle of the secondary battery, and thus reducing the production cost of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 A diagram showing the steps of a method for manufacturing a secondary battery according to an embodiment of the present application;

[0048] Figure 2 A diagram of steps for detecting a suspected defective battery cell in a method for manufacturing a secondary battery provided in an embodiment of the present application;

[0049] Figure 3 A schematic cross-sectional view of a manufacturing device provided in an embodiment of the present application;

[0050] Figure 4 This is a cross-sectional schematic diagram of an upper pressing plate in a manufacturing device provided in an embodiment of the present application.

[0051] Explanation of reference numerals: 100 , battery cell; 200 , pressure control device; 210 , upper pressing plate; 220 , lower pressing plate; 201 , flow channel; 310 , thermal fluid. DETAILED DESCRIPTION

[0052] As can be seen from the background technology, the self-discharge detection of secondary batteries uses the measurement of the battery's OCV change rate K value over a period of time (K = ΔOCV / Δt) to determine whether the secondary battery is a self-discharging battery. The static time required for the battery self-discharge detection occupies a large part of the secondary battery manufacturing cycle, resulting in high static time costs and a long secondary battery manufacturing cycle.

[0053] Typically, the processes before self-discharge testing of secondary batteries include formation treatment and capacity separation treatment. Formation treatment involves charging the battery with a standard formation current, activating the electrode materials through electrochemical reactions and forming a solid electrolyte interface membrane (SEI) on the negative electrode surface. Capacity separation treatment involves fully charging the formed battery for the first time, then discharging it with a standard discharge current until it is fully discharged. The capacity of the secondary battery is determined by the discharge time and discharge current.

[0054] First, the difference between the K value measured on a secondary battery after the capacity separation process and the K value measured on the secondary battery after the formation process is simply whether the secondary battery has been fully charged. However, the difference between a secondary battery after the formation process and a secondary battery after the capacity separation process is only in the state of charge (SOC), which does not affect the self-discharge of the secondary battery. Therefore, a secondary battery after the formation process can be used to detect whether it is a self-discharging defective battery.

[0055] Secondly, the self-discharge detection method of measuring the K value of secondary batteries in related technologies is applicable to secondary batteries manufactured using different processes and under different environmental conditions. However, before and after the formation process, within the same batch of cells, using the same manufacturing process (including the formation process) and under the same environmental conditions, differences in resistance or open-circuit voltage can occur between qualified cells and cells with self-discharge failure. Therefore, if the manufacturing process and environmental conditions of the secondary batteries in the same batch are consistent, there is no need to measure the K value; the resistance or open-circuit voltage alone can be used to determine whether a secondary battery has self-discharge failure.

[0056] The present application provides a method for manufacturing a secondary battery, wherein the temperature and pressure states of the same batch of battery cells that have completed the liquid injection process are adjusted to the same standard state, the battery cells in the standard state are subjected to a formation process, and the resistance value and open circuit voltage value are detected before and after the formation process, respectively. The resistance value and the open circuit voltage value of the qualified battery cells are compared with the preset resistance value and the preset open circuit voltage value of the qualified battery cells to determine whether the battery cells are self-discharging poor battery cells. Compared with the self-discharge detection method of measuring the K value of the secondary battery in the related art, the embodiment of the present application can determine whether the battery cells are self-discharging poor battery cells without the K value, eliminating the need for the standing time required in the process of measuring the K value of the secondary battery, and eliminating the energy consumption cost generated during the standing process, greatly shortening the manufacturing cycle of the secondary battery, and thereby reducing the production cost of the secondary battery.

[0057] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly indicate the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined. Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0058] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0059] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0060] In the description of the embodiments of the present application, the technical terms "center," "longitudinal," "transverse," "length," "width," "thickness," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplification of the embodiments of the present application. They are not intended to indicate or imply that the devices or elements referred to must have, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the embodiments of the present application. For example, if the device or element in the figure is inverted, then an element described as being "below," "beneath," "under," or "below" another element or feature would be oriented "above" or "on top" of the other element or feature. Therefore, the term "below" can encompass both above and below orientations, depending on the context in which the term is used, as will be apparent to one of ordinary skill in the art. Materials can be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatially relative descriptors used herein should be interpreted accordingly.

[0061] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0062] In the accompanying drawings corresponding to the embodiments of the present application, the thickness and area of ​​each layer are exaggerated for better understanding and ease of description. In addition, when a component is described as being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0063] In the description of the embodiments of the present application, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may be further included. A second component is formed or provided above or on the first component, or a second component is formed or provided on the surface of the first component, or a second component is formed or provided on one side of the first component. Embodiments in which the first component and the second component are in direct contact may be included, and embodiments in which additional components may be provided between the first component and the second component so that the first component and the second component may not be in direct contact may also be included. For the sake of simplicity and clarity, various components may be arbitrarily drawn in different proportions. In the accompanying drawings, some layers / components may be omitted for simplicity. Unless otherwise specified, a second component is formed or provided on the surface of the first component, which means that the first component is in direct contact with the second component. Among them, the above-mentioned "components" may refer to layers, films, regions, parts, structures, etc.

[0064] The terms used herein in the description of the various embodiments are intended only to describe the specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is intended to include the plural form unless the context clearly indicates otherwise. A component includes a layer, film, region, or plate.

[0065] The following detailed description of the various embodiments of the present application is provided in conjunction with the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present application to facilitate a better understanding of the present application. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0066] Figure 1A diagram showing the steps of a method for manufacturing a secondary battery provided in an embodiment of the present application.

[0067] refer to Figure 1 , the semiconductor structure includes:

[0068] Providing a battery cell, the battery cell comprising a shell and a bare battery cell located in the shell, and injecting an electrolyte into the shell;

[0069] performing a first detection step to obtain a first resistance value of the battery cell; if the first resistance value is less than or equal to a first preset resistance value, the battery cell is determined to be a first self-discharge defective battery cell; if the first resistance value is greater than the first preset resistance value, the battery cell is determined to be a first pass battery cell, and a formation process is performed on the first pass battery cell;

[0070] Performing a formation treatment on the first pass battery cell, wherein the formation treatment is performed within a formation time and at a formation current;

[0071] performing a second detection step to obtain a first open circuit voltage value of the first passing cell; if the first open circuit voltage value is less than or equal to a first preset open circuit voltage value, the first passing cell is determined to be a second self-discharge defective cell; if the first open circuit voltage value is greater than the first preset open circuit voltage value, the first passing cell is determined to be a second passing cell;

[0072] Wherein, in the first detection step, the formation treatment and the second detection step, the bare cell is subjected to a first detection pressure and a first detection temperature.

[0073] In the embodiment of the present application, the battery cells are adjusted to the same environmental conditions of the first detection pressure and the first detection temperature in the first detection step, the formation treatment, and the second detection step, and the influence of external environmental factors on the battery cells is eliminated in the first detection step, the formation treatment, and the second detection step. The resistance value and the open circuit voltage value of the battery cells before and after the formation treatment are detected to determine whether they are self-discharging defective battery cells. Compared with the detection method in the related art that requires static measurement of the K value, the present application does not require static time and will not generate energy loss due to static self-discharge, which greatly shortens the manufacturing cycle of the secondary battery and thereby reduces the production cost of the secondary battery.

[0074] It should be noted that cells with poor self-discharge refer to cells with severe self-discharge, not cells with internal self-discharge. Severe self-discharge can reduce the cell's electrical and safety performance and shorten its service life. Qualified cells may also have slight internal self-discharge, but this slight self-discharge will not significantly affect the cell's electrical performance, safety, or service life.

[0075] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings.

[0076] Reference Figure 1 As shown, Figure 1 A diagram showing the steps of a method for manufacturing a secondary battery provided in an embodiment of the present application is shown.

[0077] In step S1, a battery cell is provided. The battery cell includes a housing and a bare battery cell. The housing has a receiving cavity, and the bare battery cell is disposed within the cavity. The battery cell in this state is a semi-finished battery cell and has not yet been injected with electrolyte.

[0078] The battery core is subjected to a liquid injection process, and an electrolyte is injected into the accommodating cavity of the shell so that at least a portion of the bare battery core is immersed in the electrolyte.

[0079] The electrolyte can be a sodium ion electrolyte or a lithium ion electrolyte, or other medium that can achieve charge balance in the battery cell through ion conduction. Accordingly, the battery cell after the electrolyte is injected can be a sodium ion battery cell or a lithium ion battery cell, or other battery cell that can be recharged to activate the active material after discharge and continue to be used.

[0080] Among them, the bare cell is the core component of the cell to achieve the charging and discharging function. The bare cell includes a positive electrode sheet, a separator and a negative electrode sheet. The separator separates the positive electrode sheet from the negative electrode sheet. The bare cell can be a wound structure, in which the positive electrode sheet, the separator and the negative electrode sheet are stacked in sequence and wound more than two times to form a bare cell. The bare cell can also be a laminated structure, in which multiple positive and negative electrode sheets are provided, and multiple positive and negative electrode sheets are alternately stacked, and the separator separates adjacent positive and negative electrode sheets.

[0081] It should be noted that during the liquid injection process of the battery cell, the volume of electrolyte injected into the housing cavity of the shell can be the same as the volume of the electrolyte in the finished battery cell, or it can be less than the amount of electrolyte in the finished battery cell. In other words, the liquid injection process of the battery cell in the embodiment of the present application can be a single injection of the battery cell during the entire battery cell production process, without the need for further injection of the battery cell in subsequent production processes; or it can be the first injection of multiple injections of the battery cell, with the battery cell being injected at least once in subsequent production processes, without specific limitations here.

[0082] After step S1, the method further includes:

[0083] Step S11 , controlling the pressure and temperature of the battery cell so that the battery cell is at a first detection pressure and a first detection temperature.

[0084] Step S12: performing a static treatment on the battery cell at the first detection pressure and the first detection temperature.

[0085] In step S11 , the battery cell is placed in a manufacturing device (shown below), which can control the temperature and pressure of the battery cell so that the battery cell is under environmental conditions of a first detection temperature and a first detection pressure.

[0086] It should be noted that, when the battery cell is under the environmental conditions of the first detection temperature and the first detection pressure, the bare battery cell inside the corresponding battery cell is also under the environmental conditions of the first detection temperature and the first detection pressure.

[0087] In summary, the manufacturing equipment controls the pressure and temperature of the battery cells to maintain them stably at the first detection pressure and temperature during this and subsequent steps. By adjusting the pressure and temperature of all battery cells to a uniform first detection pressure and temperature, the accuracy of the test results is improved, preventing environmental factors from influencing or biasing the test results. The test results include other electrical properties of the battery cells, such as resistance and open-circuit voltage.

[0088] It should be understood that the finished battery cells or the battery packs formed by assembling the finished battery cells need to be packaged or packed so that the size of the finished battery cells or battery packs meet the factory requirements. After the packaging or packing process, the bare battery cells inside the battery cells will be pressurized, so that the distance between the electrode and the diaphragm of the bare battery cells is reduced. The first detection pressure applied to the battery cells in this application is to simulate the pressure state of the finished battery cells or the finished battery cells in the battery pack, and the distance between the electrode and the diaphragm is reduced. If there are impurities, foreign matter, burrs or diaphragm folding and other bad physical structures inside the battery cells, the reduction in the distance between the electrode and the diaphragm under the first detection pressure will cause the impurities, foreign matter, burrs to pierce the diaphragm or the diaphragm to fold, resulting in bad physical structures such as causing a short circuit between the pole pieces.

[0089] The first detection temperature is a high temperature that can activate the electrode material and accelerate the side reactions inside the battery cell, wherein the side reactions include side reactions that can increase the self-discharge of the battery cell.

[0090] In step S12, the battery cells are subjected to a static treatment at the first detection pressure and the first detection temperature. The static treatment can allow the chemical reactions within the battery cells to reach a state of equilibrium, thereby improving the effect of the subsequent chemical treatment of the battery cells. At the same time, the static treatment of the battery cells can keep the performance of the battery cells of the same batch consistent before measurement, thereby improving the accuracy of subsequent determination results. In addition, the static treatment at the high temperature of the first detection temperature can accelerate the side reactions within the battery cells, avoiding the situation where the electrical performance of the battery cells produced by the factory deteriorates rapidly in a short period of time due to incomplete side reactions.

[0091] In some embodiments, the first detection pressure is 0.1 MPa to 0.8 MPa. Optionally, the first detection pressure is 0.2 MPa to 0.6 MPa, and the first detection pressure can be 0.2 MPa, 0.4 MPa, 0.5 MPa, or 0.6 MPa.

[0092] In some embodiments, the first detection temperature is 35° C. to 50° C. Optionally, the first detection temperature is 43° C. to 47° C., and the first detection temperature may be 43° C., 44° C., 45° C., or 46° C.

[0093] In step S2, the battery cell undergoes a first inspection step, measuring the resistance of the battery cell to obtain a first resistance value, i.e., the internal resistance of the battery cell. The measured first resistance value is compared with a first preset resistance value. If the first resistance value of the battery cell is greater than the first preset resistance value, the battery cell is determined to be a first passing battery cell and is sent to the next process. If the first resistance value of the battery cell is less than or equal to the first preset resistance value, the battery cell is determined to be a first self-discharging defective battery cell.

[0094] The first resistance value of the first self-discharging poor battery cell is less than the first preset resistance value, indicating that a short circuit occurs between some of the electrodes in the first self-discharging poor battery cell. If the first self-discharging poor battery cell is charged, a more serious self-discharge will occur inside the first self-discharging poor battery cell than in a qualified battery cell. Usually, the reasons for the small first resistance value of the first self-discharging poor battery cell include the presence of foreign matter, burrs piercing the diaphragm, or folding of the diaphragm, which causes a short circuit between the electrodes, thereby causing the first self-discharging poor battery cell to self-discharge poorly. The short circuit caused by the above-mentioned poor physical structure will reduce the internal resistance of the battery cell. The present application measures the first resistance value of the battery cell by the first detection step and compares it with the first preset resistance value to determine whether the battery cell is the first self-discharging poor battery cell caused by a poor physical structure. Compared with the self-discharge detection method of measuring the K value in the related art, the present application is simpler and more convenient, takes less time, and greatly reduces production costs.

[0095] In the first testing step of the battery cell, the battery cell and the bare battery cell in the battery cell are tested at a first testing pressure and a first testing temperature.

[0096] It should be noted that the state of charge (SOC) of the battery cell after the liquid injection treatment is 0 or infinitely close to 0. In this state, the open circuit voltage of the battery cell is very low, making it difficult to measure the open circuit voltage of the battery cell or the measured value inaccurate. The electrical parameters of the battery cell after the liquid injection treatment that are easy to measure and do not affect its state of charge include resistance. Therefore, the first resistance value of the battery cell is measured in step S2.

[0097] It should also be noted that the first preset resistance value is the resistance value of a qualified battery cell. The method for obtaining the first preset resistance value includes measuring the qualified battery cell or calculating it through the battery cell material performance, which is not specifically limited here.

[0098] In some embodiments, the first preset resistance value is 0.15Ω to 0.2Ω. Optionally, the first preset resistance value is 0.17Ω to 0.19Ω, and the first preset resistance value can be 0.17Ω, 0.175Ω, 0.18Ω, or 0.185Ω.

[0099] In step S3 , a formation treatment is performed on the first passing cell, and a formation current is applied to the first passing cell during a formation time.

[0100] The formation treatment transforms the battery cell from a material combination state after the injection treatment into a stable electrochemical system by charging the battery cell with a low current. The electrolyte reacts on the motor surface to form an SEI membrane. The SEI membrane is a multi-layer structure with a porous outer layer and a dense inner layer. The SEI (Solid Electrolyte Interface) membrane prevents the electrolyte from continuously decomposing, reducing ion consumption while improving the cycle life and safety of the battery cell. During the formation treatment of the first-pass battery cell, the first-pass battery cell and the bare battery cell within the first-pass battery cell are tested at the first test pressure and the first test temperature.

[0101] In the present application, the formation treatment of the first-pass battery cell is performed at the first detection pressure and the first detection temperature, and the formation time and formation current of the first-pass battery cell formation treatment are unified, and the formation effect of the formation treatment on the first-pass battery cell is unified, so as to avoid inconsistent electrical performance of the first-pass battery cell after the formation treatment, and inconsistent standards for subsequent judgment of whether the battery cell is a self-discharging poor battery cell.

[0102] In some embodiments, the formation time is 200 min to 500 min. Optionally, the formation time is 270 min to 350 min, and the formation time can be 270 min, 300 min, 330 min, or 350 min.

[0103] In some embodiments, the formation current is 0.1C to 0.5C. Optionally, the formation current is 0.15C to 0.3C, and the formation current can be 0.15C, 0.2C, 0.25C, or 0.3C. It should be noted that the unit "C" here represents the charge and discharge rate of the battery, and C is the abbreviation of capacity, which represents the capacity of the battery. The value of 1C is equal to the capacity of the battery cell itself.

[0104] In step S4, a second testing step is performed on the first passing cell, measuring the open circuit voltage of the first passing cell to obtain a first open circuit voltage value. The measured first open circuit voltage value is compared with a first preset open circuit voltage value. If the first open circuit voltage value of the first passing cell is greater than the first preset open circuit voltage value, the first passing cell is determined to be a second passing cell and the second cell is sent to the next process. If the first open circuit voltage value of the first passing cell is less than or equal to the first preset open circuit voltage value, the first passing cell is determined to be a second self-discharge defective cell.

[0105] The second self-discharge poor cell is a cell that has undergone the first detection step and the formation treatment. The first open circuit voltage value of the second self-discharge poor cell is less than the first preset open circuit voltage value, indicating that the first self-discharge poor cell has adverse electrochemical reactions or adverse electrochemical components such as local decomposition of electrode active materials, excessive water content in the electrolyte, or excessive impurities in the electrolyte. The above-mentioned adverse electrochemical reactions and adverse electrochemical components will cause the second self-discharge poor cell to have a poor self-discharge phenomenon. The present application detects the first open circuit voltage value of the first through cell after the formation treatment through the second detection step to determine whether the first through cell is the second self-discharge poor cell caused by an adverse electrochemical reaction or an unwanted electrochemical component. Compared with the self-discharge detection method of measuring the K value in the related art, the detection process of the present application is simple, convenient, and has low time cost, which greatly reduces the production cost. Among them, in the second detection step of the first through cell, the first through cell and the bare cell in the first through cell are tested at the first detection pressure and the first detection temperature.

[0106] It should be noted that the first pass cell is carried out under the formation time and formation current in the formation treatment, that is, the first pass cell undergoes charging with a small current formation current in the formation treatment. The first pass cell after the formation treatment has a certain state of charge, and the first pass cell has a certain amount of electricity inside. The open circuit voltage of the first pass cell in this state is easy to measure, so the first open circuit voltage value of the first pass cell is measured in the second detection step.

[0107] It should also be noted that the first preset open circuit voltage value is the open circuit voltage value of a qualified battery cell. The method for obtaining the first preset open circuit voltage value includes measuring the qualified battery cell or calculating it through the battery cell material performance, which is not specifically limited here.

[0108] In some embodiments, the first preset open circuit voltage value is 2.0 V to 4.0 V. Optionally, the first preset open circuit voltage value is 3.0 V to 3.3 V, and the first preset open circuit voltage value may be 3.0 V, 3.1 V, 3.2 V, or 3.3 V.

[0109] Furthermore, in the first detection step of step S2, a second preset resistance value is also included, and the second preset resistance value is greater than the first preset resistance value. If the first detection resistance value of the battery cell is greater than the first preset resistance value and less than or equal to the second preset resistance value, the battery cell is determined to be a first suspected defective battery cell. The first suspected defective battery cell is subjected to the formation treatment in step S3, and the first suspected defective battery cell is placed under the environmental conditions of the first detection temperature and the first detection temperature, and a formation current is applied to the first suspected defective battery cell within the formation time.

[0110] like Figure 2 As shown, Figure 2 A diagram illustrating the steps involved in a secondary battery manufacturing method provided by an embodiment of the present application, in the case of suspected defective cells. After the first and second inspection steps, the finished cells are processed to form finished cells. However, some of the finished cells are determined to be self-discharging defective cells upon inspection. The inventors discovered that although the first detection resistance values ​​or first detection open-circuit voltage values ​​obtained in the first and second inspection steps for the self-discharging defective cells are greater than the first preset resistance value or first preset open-circuit voltage value, the first detection resistance value or first detection open-circuit voltage value of the self-discharging defective cells is close to the first preset resistance value or first preset open-circuit voltage value. However, the inventors also discovered that not all cells with first detection resistance values ​​or first detection open-circuit voltage values ​​close to the first preset resistance value or first preset open-circuit voltage value are self-discharging defective cells, and some cells are determined to be qualified upon inspection. Therefore, some cells with first detection resistance values ​​or first detection open-circuit voltage values ​​within a range close to the first preset resistance value or first preset open-circuit voltage value still have the risk of self-discharging defective cells after being processed into finished cells, and all cells within this range are determined to be suspected defective cells.

[0111] Furthermore, the suspected defective battery cell includes a first suspected defective battery cell and a second suspected defective battery cell.

[0112] The present application further includes step S21, which is performed after step S2 and includes a second preset resistance value, the second preset resistance value being greater than the first preset resistance value. After determining that the battery cell is the first passing battery cell, if the first detection resistance value of the first passing battery cell is less than or equal to the second preset resistance value, the first passing battery cell is determined to be the first suspected defective battery cell; if the first detection resistance value of the first passing battery cell is greater than the second preset resistance value, the first passing battery cell is sent to the next process step.

[0113] The present application further includes step S41, which is performed after step S4 and includes a second preset open-circuit voltage value, the second preset open-circuit voltage value being greater than the first preset open-circuit voltage value. After determining that the first passing cell is the second passing cell, if the first detected open-circuit voltage value of the second passing cell is less than or equal to the second preset open-circuit voltage value, the second passing cell is determined to be a second suspected defective cell; if the first detected open-circuit voltage value of the second passing cell is greater than the second preset open-circuit voltage value, the second passing cell is determined to be a qualified cell.

[0114] The present application further detects and processes the first suspected defective battery cell and the second suspected defective battery cell to improve the qualified rate of the finished battery cells.

[0115] Furthermore, the manufacturing method of the secondary battery also includes:

[0116] Step S51, performing charge adjustment on the suspected defective battery cells after the formation treatment, discharging the suspected defective battery cells and then performing a recharging treatment;

[0117] In step S52, a third detection step is performed on the suspected defective battery cell to obtain a second open circuit voltage value of the suspected defective battery cell. If the second open circuit voltage value is less than or equal to the second preset open circuit voltage value, the suspected defective battery cell is determined to be a third self-discharge defective battery cell; if the second open circuit voltage value is greater than the second preset open circuit voltage value, the suspected defective battery cell is determined to be a qualified battery cell.

[0118] In the charge adjustment step and the third detection step, the suspected defective battery cells and the bare battery cells in the suspected defective battery cells are tested at the second detection temperature and the second detection pressure.

[0119] In step S51, the suspected defective cells after the formation process are subjected to charge adjustment, and the suspected defective cells are discharged until the suspected defective cells are completely discharged, that is, the suspected defective cells are discharged to a state of charge of 0. The suspected defective cells are then subjected to a recharge process, and the suspected defective cells are recharged with a recharge current within a recharge time. Through the above charge adjustment steps, the state of charge of the suspected defective cells is adjusted to a uniform state.

[0120] In step S52, a third detection step is performed on the suspected defective battery cell after the charge adjustment process, and the open circuit voltage of the suspected defective battery cell is measured to obtain a second open circuit voltage value of the suspected defective battery cell. If the suspected defective battery cell has a self-discharge problem, its power loss value will be much greater than that of a normal battery cell, resulting in a lower open circuit voltage value measured later. The measured second open circuit voltage value is compared with the second preset open circuit voltage value. If the second open circuit voltage value is less than or equal to the second preset open circuit voltage value, it indicates that the suspected defective battery cell has a self-discharge problem, and the suspected defective battery cell is determined to be a third self-discharge defective battery cell. If the second open circuit voltage value is greater than the second preset open circuit voltage value, the suspected defective battery cell is determined to be a qualified battery cell.

[0121] During the charge adjustment process and the third detection step, the suspected defective battery cell is placed in a manufacturing device, and the temperature and pressure of the suspected defective battery cell are controlled by the manufacturing device so that the suspected defective battery cell and the bare battery cell within the first suspected defective battery cell are subjected to the second detection temperature and the second detection pressure. By unifying the external environmental conditions of the suspected defective battery cell in the charge adjustment process and the third detection step, the second open-circuit voltage value obtained in the third detection step is not affected by the external environmental conditions, thereby improving the accuracy of the detection result.

[0122] It should be noted that the second detection temperature can be the same as or different from the first detection temperature. The second detection temperature can be a temperature range close to the ambient temperature. Since the first suspected defective battery cell in the static treatment in step S12 and the formation treatment in step S3 are both carried out at the high-temperature first detection temperature, the side reactions in the first suspected defective battery cell have been completely reacted and the chemical reactions inside it have reached a state of equilibrium. Therefore, the second detection temperature in the third detection step does not need to be maintained at the high temperature of the first detection temperature. It is only necessary to ensure that the ambient temperature of the first suspected defective battery cell is uniform. The second detection pressure is the pressure value of the simulated battery cell in the finished product state. The second detection pressure and the first detection pressure can be equal or different, and again no specific limitation is made.

[0123] This application further refines the criteria for determining whether a cell is a self-discharging defective cell, screens out suspected defective cells, and further adjusts, tests, and determines these cells, thereby improving the accuracy of this application's determination of whether a cell is a self-discharging defective cell and increasing the product's pass rate. Furthermore, this application's charge adjustment, testing, and determination of defective cells eliminates the need for the resting time required by related self-discharging defect detection methods that measure the K value, shortening the production cycle and reducing production costs.

[0124] For the first suspected defective cell, the present application further includes step S31, which is performed after the first passing cell is determined to be the first suspected defective cell in step S21 and before step S51. In step S31, before the first suspected defective cell is subjected to the charge adjustment process and the third detection step, the first suspected defective cell is subjected to a formation process, and the formation process conditions for the first suspected defective cell are the same as the formation process conditions for the first passing cell. That is, a formation current is applied to the first suspected defective cell within the formation time, and the formation process of the first suspected defective cell is performed at the first detection temperature and the first detection pressure.

[0125] Because the second suspected defective battery cell has undergone formation treatment, the formation treatment conditions of the first suspected defective battery cell in this application are the same as the formation treatment conditions of the first passing battery cell or the second suspected defective battery cell, ensuring that the formation effect of the first suspected defective battery cell is the same as the formation effect of the second suspected defective battery cell, eliminating the interference of external factors on the detection and judgment results, so that the first suspected defective battery cell and the second suspected defective battery cell can be detected and judged with the same standard in the third detection step, simplifying the process and thus reducing production costs.

[0126] In some embodiments, the second preset resistance value is 0.2Ω to 0.25Ω. Optionally, the first preset resistance value is 0.175Ω to 0.195Ω, and the first preset resistance value can be 0.175Ω, 0.18Ω, 0.185Ω, or 0.19Ω.

[0127] In some embodiments, the second preset open circuit voltage value is 2.5 V to 4.5 V. Optionally, the second preset open circuit voltage value is 3.0 V to 4.0 V, and the second preset open circuit voltage value may be 3.0 V, 3.3 V, 3.6 V, or 4.0 V.

[0128] In some embodiments, the third preset open circuit voltage value is 2.0 V to 5.0 V. Optionally, the third preset open circuit voltage value is 2.5 V to 4.5 V, and the third preset open circuit voltage value can be 2.5 V, 3.0 V, 3.5 V, or 4.0 V.

[0129] In some embodiments, the second detection pressure is 0.1 MPa to 0.8 MPa. Optionally, the second detection pressure is 0.2 MPa to 0.6 MPa, and the second detection pressure can be 0.2 MPa, 0.4 MPa, 0.5 MPa, or 0.6 MPa.

[0130] In some embodiments, the second detection temperature is 20° C. to 50° C. Optionally, the second detection temperature is 25° C. to 47° C., and the second detection temperature may be 25° C., 35° C., 40° C., or 47° C.

[0131] In some embodiments, the charging time is 200 min to 400 min. Optionally, the charging time is 270 min to 350 min, and the charging time can be 270 min, 290 min, 310 min, or 340 min.

[0132] In some embodiments, the supplemental current is 0.2C to 0.5C. Optionally, the supplemental current is 0.3C to 0.4C, and the supplemental current may be 0.3C, 0.32C, 0.35C, or 0.4C.

[0133] In order to better illustrate the beneficial effects brought about by the embodiments of the present application, the following corresponding embodiments and comparative examples are provided for illustration, and specific reference is made to Table 1 below:

[0134] Table 1:

[0135]

[0136] From the comparison between Example 1 and Comparative Example 1 in Table 1, it can be seen that the production cycle time used by the solution adopted in the embodiment of the present application is much shorter than the production cycle time used by the solution for measuring the K value in Comparative Example 1, and the self-discharge defect screening rate of the embodiment of the present application is 100%, which is also significantly higher than the self-discharge defect screening rate of Comparative Example 1. Therefore, it can be concluded that the embodiment of the present application greatly shortens the manufacturing cycle of the secondary battery, reduces the production cost of the secondary battery, and also improves the self-discharge defect screening rate, thereby avoiding the increase in repair and maintenance costs caused by the release of self-discharge defective batteries into the market, thereby improving the reliability of the product.

[0137] Accordingly, another embodiment of the present application further provides a manufacturing apparatus that can be used to implement the secondary battery manufacturing method provided in the above embodiment. The manufacturing apparatus will be described in detail below with reference to the accompanying drawings. For portions corresponding to the secondary battery manufacturing method, please refer to the aforementioned description and will not be described in detail below.

[0138] Reference Figure 3 and Figure 4 As shown, Figure 3 A cross-sectional schematic diagram of a manufacturing device provided in an embodiment of the present application is shown. Figure 4 A cross-sectional schematic diagram of a pressure control device in a manufacturing apparatus provided in an embodiment of the present application is shown. The manufacturing apparatus is used to set battery cells and control their temperature and pressure, thereby preventing the impact of external environmental factors on detection and determination, and improving determination accuracy. The manufacturing apparatus includes: a pressure control device 200, a constant temperature device, a temperature and pressure acquisition device, and an electrical performance detection device.

[0139] The pressure control device 200 is used to control the pressure of the battery cell 100. The pressure control device 200 includes an upper pressing plate 210 and a lower pressing plate 220 that are arranged relative to each other. The upper pressing plate 210 and the lower pressing plate 220 are arranged to form a receiving cavity. The battery cell 100 is arranged in the receiving cavity and clamped between the upper pressing plate 210 and the lower pressing plate 220. The upper pressing plate 210 and the lower pressing plate 220 clamp the battery cell 100 and apply pressure to the battery cell 100, so that the battery cell 100 is in an environmental condition of a certain pressure value. For example, in step S11, the pressure control device 200 clamps the battery cell 100 and applies pressure to the battery cell 100, so that the battery cell 100 is in an environmental condition of a first detection pressure; in steps S51 and S52, the pressure control device 200 clamps the suspected defective battery cell and applies pressure to the suspected defective battery cell, so that the suspected defective battery cell is in an environmental condition of a second detection pressure.

[0140] It should be noted that the battery cell 100 clamped by the pressure control device 200 can be a battery cell in any step or in any state in the above-mentioned secondary battery manufacturing method, such as battery cell 100, the first passing battery cell, the first suspected defective battery cell, the second passing battery cell, the second suspected defective battery cell, etc., and no specific limitation is made here.

[0141] A thermostat (not shown) is used to control the temperature of the battery cell 100. The thermostat includes a temperature adjustment module, a water supply line, and a water return line. A flow channel 201 is provided within the upper and lower pressure plates 210 and 220. The water inlet of the flow channel 201 is connected to the water supply line, and the water outlet of the flow channel 201 is connected to the water return line. The temperature adjustment module is positioned between the water supply and return lines, connecting them. The water supply line, flow channel 201, and return line form a loop through which a thermal fluid 310 circulates. The temperature adjustment module adjusts the temperature of the thermal fluid 310 within the loop. The thermostat first exchanges heat between the thermal fluid 310 within the flow channel 201 and between the upper and lower pressure plates 210 and 220, and then exchanges heat between the upper and lower pressure plates 210 and 220 and the battery cell 100 held between them, thereby controlling the temperature of the battery cell 100. The thermostat controls the temperature of the battery cell 100 so that the battery cell 100 is in an environment at a certain temperature. For example, in step S11, the thermostat controls the temperature of the battery cell 100 so that the battery cell 100 is in an environment at a first detection temperature. In steps S51 and S52, the thermostat controls the temperature of the suspected defective battery cell so that the suspected defective battery cell is in an environment at a second detection temperature.

[0142] The temperature and pressure acquisition device (not shown in the figure) is used to collect the temperature and pressure of the battery cell 100. The temperature and pressure acquisition device includes a temperature and pressure probe, which is in contact with the battery cell 100. The temperature and pressure acquisition device collects the temperature and pressure of the battery cell 100 in real time. When the temperature and pressure of the battery cell 100 fluctuate during the manufacturing process (such as chemical formation treatment), the temperature and pressure acquisition device sends a signal to the pressure control device 200 and the constant temperature device. The pressure control device 200 and the constant temperature device receive the signal and make corresponding adjustments to quickly adjust the temperature and pressure of the battery cell 100 to the target temperature (such as the first detection temperature and the second detection temperature) and the target pressure (such as the first detection pressure and the second detection pressure). This avoids the battery cell 100 from having inconsistent environmental conditions for detection and judgment due to large fluctuations in temperature and pressure during the manufacturing process, causing external environmental conditions to affect the detection results, thereby affecting the accuracy of the judgment results.

[0143] An electrical performance detection device (not shown) is electrically connected to the battery cell 100 , and is used to detect electrical performance values ​​of the battery cell 100 , such as resistance value and open circuit voltage value.

[0144] Correspondingly, another embodiment of the present application further provides a secondary battery, which can be obtained by the above-mentioned secondary battery manufacturing method. The secondary battery includes a battery cell, which includes: a shell, a bare battery cell and an electrolyte. The shell has a storage cavity inside. The bare battery cell is installed in the storage cavity. The bare battery cell includes a stacked positive electrode sheet, a separator and a negative electrode sheet. The electrolyte is contained in the storage cavity, and the bare battery cell is at least partially immersed in the electrolyte.

[0145] Accordingly, another embodiment of the present application further provides an energy storage system, which includes a plurality of secondary batteries, which can be obtained by the above-mentioned secondary battery manufacturing method or are the above-mentioned secondary batteries. It should be noted that the parts that are the same or corresponding to the above-mentioned embodiments are not repeated here.

[0146] Correspondingly, another embodiment of the present application further provides an electrical device, which includes a plurality of secondary batteries, which can be obtained by the above-mentioned secondary battery manufacturing method or are the above-mentioned secondary batteries. It should be noted that the parts that are the same or corresponding to the above-mentioned embodiments are not repeated here.

[0147] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present application, and that in actual applications, various changes in form and detail may be made thereto without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A method for manufacturing a secondary battery, characterized in that: include: Providing a battery cell, the battery cell comprising a shell and a bare battery cell located in the shell, and injecting an electrolyte into the shell; performing a first detection step to obtain a first resistance value of the battery cell; if the first resistance value is less than or equal to a first preset resistance value, the battery cell is determined to be a first self-discharge defective battery cell; if the first resistance value is greater than the first preset resistance value, the battery cell is determined to be a first pass battery cell, and a formation process is performed on the first pass battery cell; Performing the formation treatment on the first pass cell, wherein the formation treatment is performed within a formation time and at a formation current; the formation time is 200 min to 500 min, and the formation current is 0.1 C to 0.5 C; performing a second detection step to obtain a first open circuit voltage value of the first passing cell; if the first open circuit voltage value is less than or equal to a first preset open circuit voltage value, the first passing cell is determined to be a second self-discharge defective cell; if the first open circuit voltage value is greater than the first preset open circuit voltage value, the first passing cell is determined to be a second passing cell; Wherein, in the first detection step, the formation treatment and the second detection step, the bare cell is tested at a first detection pressure and a first detection temperature, the first detection pressure is 0.1MPa~0.8MPa; the first detection temperature is 35℃~50℃; The first preset resistance value is 0.15Ω~0.2Ω; the first preset open circuit voltage value is 2.0V~4.0V; The first detection step further includes a second preset resistance value, the second preset resistance value being greater than the first preset resistance value; if the first resistance value is greater than the first preset resistance value and less than or equal to the second preset resistance value, the first passing cell is determined to be a first suspected defective cell; the second preset resistance value is 0.2Ω to 0.25Ω; performing the formation treatment on the first suspected defective battery cell; Performing a charge adjustment step, discharging the first suspected defective cell to a state of charge of 0; performing a recharge process on the first suspected defective cell, wherein the recharge process is performed under a recharge time and a recharge current; the recharge time is 200 minutes to 400 minutes, and the recharge current is 0.2C to 0.5C; performing a third detection step to obtain a second open circuit voltage value of the first suspected defective battery cell; if the second open circuit voltage value is less than or equal to a second preset open circuit voltage value, the first suspected defective battery cell is determined to be a third self-discharging defective battery cell; the second open circuit voltage value is 2.5V to 4.5V; In the charge adjustment step and the third detection step, the bare cell is tested at a second detection temperature and a second detection pressure; the second detection pressure is 0.1 MPa to 0.8 MPa; and the second detection temperature is 20° C. to 50° C.

2. The method for manufacturing a secondary battery according to claim 1, wherein: The second detection step further includes a third preset open circuit voltage value, wherein the third preset open circuit voltage value is greater than the first preset open circuit voltage value; if the first open circuit voltage value is greater than the first preset open circuit voltage value and less than or equal to the third preset open circuit voltage value, the second passing cell is determined to be a second suspected defective cell; performing a charge adjustment step to discharge the second suspected defective cell to a state of charge of 0; and recharging the second suspected defective cell, wherein the recharging is performed at a recharging time and a recharging current; performing a third detection step to obtain a second open circuit voltage value of the second suspected defective battery cell; if the second open circuit voltage value is less than or equal to a second preset open circuit voltage value, the second suspected defective battery cell is determined to be a third self-discharging defective battery cell; Wherein, in the charge adjustment step and the third detection step, the bare cell is tested at a second detection temperature and a second detection pressure.

3. The method for manufacturing a secondary battery according to claim 2, wherein: The third preset open circuit voltage value is 2.0V~5.0V.

4. The method for manufacturing a secondary battery according to claim 1, wherein: After providing the battery cell, performing a static treatment on the battery cell; Wherein, during the static treatment, the bare battery cell is subjected to the first detection pressure and the first detection temperature; and the static treatment time of the battery cell is 27 hours to 36 hours.

5. A secondary battery, characterized in that: The secondary battery is obtained by the manufacturing method of a secondary battery according to any one of claims 1 to 4, and the secondary battery comprises a battery cell, and the battery cell comprises: A housing having an accommodating cavity therein; A bare battery cell, the bare battery cell being accommodated in the accommodating cavity; An electrolyte is contained in the containing cavity, and the bare battery cell is at least partially immersed in the electrolyte.

6. A manufacturing device, characterized in that: The manufacturing equipment is used to implement the manufacturing method of the secondary battery according to any one of claims 1 to 4, and the manufacturing equipment includes: A pressure control device, used to clamp the battery cell and adjust the pressure value applied to the bare battery cell in the battery cell; the pressure control device includes an upper pressure plate and a lower pressure plate, the upper pressure plate and the lower pressure plate are arranged opposite to each other to clamp the battery cell; A thermostatic device, comprising a temperature regulating module, a water supply pipeline, and a water return pipeline; the temperature regulating module is connected to the water supply pipeline and the water return pipeline to form a loop, a thermal fluid circulates in the loop, and the temperature regulating module regulates the temperature of the thermal fluid; Wherein, a flow channel is provided in the upper pressing plate and the lower pressing plate, the water inlet of the flow channel is connected to the water supply pipeline, and the water outlet of the flow channel is connected to the return pipeline to adjust the temperature of the bare battery cell.

7. The manufacturing equipment according to claim 6, characterized in that Also includes: A temperature and pressure collection device for collecting the temperature and pressure of the battery cell, the temperature and pressure collection device comprising a temperature and pressure probe, the temperature and pressure probe being in contact with the battery cell; An electrical performance detection device is electrically connected to the battery cell and is used to detect the resistance value and open circuit voltage value of the battery cell.

8. An energy storage system, characterized in that: A secondary battery obtained by the method for manufacturing a secondary battery according to any one of claims 1 to 4, or a secondary battery according to claim 5.

9. An electrical device, characterized in that: A secondary battery obtained by the method for manufacturing a secondary battery according to any one of claims 1 to 4, or a secondary battery according to claim 5.

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