Battery monomer detection method, formation equipment and battery production line

Abstract

The invention discloses a battery monomer detection method, formation equipment and a battery production line, and the detection method comprises the steps: arranging a battery monomer on the formation equipment, enabling a negative pressure cup to be communicated with the interior of the battery monomer, carrying out the negative pressure preliminary detection of the battery monomer under a first test condition, and screening out the battery monomer which is qualified in preliminary detection, the first test condition comprises the steps of vacuumizing the battery monomers to a first preset negative pressure and preventing electrolyte in the battery monomers from entering a negative pressure cup under the first preset negative pressure, and the second test condition comprises the steps of performing negative pressure retest on the battery monomers qualified in primary test and screening out the battery monomers qualified in retest; the second test condition comprises that the battery monomer is vacuumized to a second preset negative pressure, the absolute value of the second preset negative pressure is greater than the absolute value of the first preset negative pressure, and the electrolyte in the battery monomer enters the negative pressure cup under the second preset negative pressure. According to the method, the single batteries are subjected to primary testing and secondary testing respectively, so that the single batteries with poor sealing performance can be screened out, and the condition of electrolyte leakage is reduced.

Description

Technical Field

[0001] The present application relates to the field of battery manufacturing technology, and in particular to a battery monomer detection method, formation equipment and battery production line. Background Art

[0002] With the development of new energy, more and more fields are using new energy as a power source. Due to its advantages such as high energy density, rechargeable, safe and environmentally friendly, battery devices are widely used in new energy vehicles, consumer electronics, energy storage systems and other fields.

[0003] In the related art, a battery device includes a plurality of battery cells. During the manufacturing process, the battery cells need to be subjected to formation operations in order to activate the battery cells. Before the formation operations are performed on the battery cells, the leakage rate of the battery cells needs to be tested. However, during the testing process, the battery cells with unqualified leakage rates may leak electrolyte, and the leaked electrolyte may contaminate other battery cells. Summary of the invention

[0004] In view of the above problems, the present application provides a battery cell detection method, formation equipment and battery production line, which solve the problem of electrolyte leakage in battery cells with unqualified leakage rates.

[0005] The first aspect of the present application provides a battery cell detection method, the detection method comprising:

[0006] placing the battery cells on a formation device;

[0007] Connecting the negative pressure cup of the formation equipment to the interior of the battery cell;

[0008] Under the first test condition, the battery cells are subjected to a negative pressure preliminary test, and the battery cells that pass the preliminary test are screened out, wherein the first test condition includes evacuating the battery cells to a first preset negative pressure, and under the first preset negative pressure, the electrolyte in the battery cells does not enter the negative pressure cup;

[0009] Under the second test condition, the battery cells that passed the initial test are retested under negative pressure, and the battery cells that passed the retest are screened out, wherein the second test condition includes evacuating the battery cells to a second preset negative pressure, the absolute value of the second preset negative pressure is greater than the absolute value of the first preset negative pressure, and under the second preset negative pressure, the electrolyte in the battery cells enters the negative pressure cup.

[0010] In the present application, the battery cells are initially tested using the first preset negative pressure, and the battery cells are screened for leakage without the electrolyte entering the negative pressure cup. The battery cells that have passed the initial test are then retested, and the battery cells are screened for leakage with the electrolyte entering the negative pressure cup. By performing initial and retests on the battery cells respectively, the battery cells with sealing problems can be screened out, thereby reducing the leakage of electrolyte in the battery cells during the test.

[0011] In some embodiments of the present application, under a first test condition, a negative pressure initial test is performed on a battery cell, and battery cells that pass the initial test are screened out, wherein the first test condition includes evacuating the battery cell to a first preset negative pressure, and under the first preset negative pressure, the electrolyte in the battery cell does not enter the negative pressure cup, and the step includes:

[0012] Perform the first vacuuming operation on the battery cell;

[0013] When the internal pressure of the battery cell reaches a first preset negative pressure, the first vacuuming operation is terminated;

[0014] Perform the first pressure maintenance operation on the battery cell and time the pressure maintenance process;

[0015] Calculate the initial leakage rate of the battery cell according to the first pressure holding time reaching the first preset time;

[0016] The battery cells that have been initially tested are screened based on their initial leakage rates to determine whether they are qualified.

[0017] With such an arrangement, the battery cells can be initially tested under conditions of low preset negative pressure, thereby screening out battery cells with sealing problems without the electrolyte entering the negative pressure cup, thereby reducing the situation where the electrolyte enters the negative pressure cup under high preset negative pressure conditions, causing leakage of the electrolyte in the battery cells during the test due to sealing problems of the battery cells.

[0018] In some embodiments of the present application, the step of screening whether the initially tested battery cells are qualified according to the initially tested leakage rate includes:

[0019] comparing the initial leak rate with a first preset value;

[0020] When the initial leakage rate is greater than or equal to the first preset value, the battery cell is determined to be unqualified in the initial test;

[0021] When the initial leak rate is less than the first preset value, the battery cell is determined to be qualified in the initial test.

[0022] By comparing the initial leakage rate of the battery cell with a preset first preset value, and judging whether there is a problem with the sealing of the battery cell based on the comparison result, it is possible to perform an initial screening of battery cells with sealing problems, thereby reducing the possibility of electrolyte leakage of the battery cell during the test due to sealing problems of the battery cell.

[0023] In some embodiments of the present application, in the step of comparing the initial leak rate with the first preset value, the first preset value is in the range of 2 kPa / min to 5 kPa / min. This arrangement can improve the accuracy of screening battery cells with sealing problems during the initial test of the battery cells, and further reduce the leakage of the electrolyte of the battery cells during the test.

[0024] In some embodiments of the present application, in the step of calculating the initial leakage rate of the battery cell according to the first pressure holding time reaching the first preset time, the first preset time is in the range of 60 seconds to 180 seconds.

[0025] Such an arrangement can provide a sufficient pressure-maintaining time for the battery cells during the initial test, further improving the accuracy of screening battery cells with sealing problems.

[0026] In some embodiments of the present application, according to the first pressure holding time reaching the first preset time, the step of calculating the initial leakage rate of the battery cell includes:

[0027] Acquire a first pressure value of the battery cell when the first vacuuming is completed;

[0028] Acquire a second pressure value of the battery cell when the first pressure-maintaining time reaches a first preset time;

[0029] Calculating a first difference between the first pressure value and the second pressure value, and taking an absolute value of the first difference as a first pressure difference;

[0030] A first ratio of the first pressure difference to the first preset time length is calculated, wherein the first ratio is an initial leak rate.

[0031] With such an arrangement, the leakage of the battery cell can be quantified during the initial test, and the sealing problem of the battery cell can be determined by data comparison, thereby further improving the accuracy of determining the battery cell with sealing problems.

[0032] In some embodiments of the present application, under the second test condition, the battery cells that have passed the initial test are retested under negative pressure, and the battery cells that have passed the retest are screened out, wherein the second test condition includes evacuating the battery cells to a second preset negative pressure, the absolute value of the second preset negative pressure is greater than the absolute value of the first preset negative pressure, and under the second preset negative pressure, the electrolyte in the battery cells enters the negative pressure cup:

[0033] Perform a second vacuuming operation on the battery cells that have passed the initial test;

[0034] When the internal pressure of the battery cell reaches a second preset negative pressure, the second vacuuming operation is terminated;

[0035] Performing a second pressure-maintaining operation on the battery cell and timing the pressure-maintaining process;

[0036] Calculate the retest leakage rate of the battery cell according to the second pressure holding time reaching the second preset time;

[0037] The retested battery cells are screened based on the retest leakage rate to determine whether they are qualified.

[0038] With such an arrangement, the battery cells can be retested under the condition of a high preset negative pressure, and the battery cells can be further screened, thereby increasing the detection rate of battery cells with sealing problems, and further reducing the failure rate of battery cells.

[0039] In some embodiments of the present application, the step of screening whether the retest of the battery cell is qualified according to the retest leakage rate includes:

[0040] Compare the retested leak rate with the second preset value;

[0041] When the retest leakage rate is greater than or equal to the second preset value, the battery cell is determined to be retested unqualified;

[0042] When the retest leakage rate is less than the second preset value, the battery cell is determined to be qualified in the retest.

[0043] By comparing the retested leakage rate of the battery cell with a preset second preset value and judging whether there is a problem with the sealing of the battery cell based on the comparison result, it is possible to re-screen the battery cells with sealing problems, thereby improving the detection rate of battery cells with sealing problems and reducing the situation where battery cell failures are caused by sealing problems of the battery cells.

[0044] In some embodiments of the present application, in the step of comparing the retested leakage rate with the second preset value, the second preset value is in the range of 2 kPa / min to 5 kPa / min. This arrangement can improve the accuracy of screening battery cells with sealing problems during the retest of battery cells, further reducing the occurrence of battery cell failures.

[0045] In some embodiments of the present application, in the step of calculating the retest leakage rate of the battery cell according to the second pressure holding time reaching the second preset time, the second preset time is in the range of 60 seconds to 180 seconds.

[0046] Such an arrangement can ensure that the battery cells are kept under pressure for a sufficient period of time during the retest process, further improving the accuracy of screening battery cells with sealing problems.

[0047] In some embodiments of the present application, the step of calculating the retest leakage rate of the battery cell based on the second pressure holding time reaching the second preset time includes:

[0048] Acquire a third pressure value of the battery cell at the end of the second vacuuming;

[0049] Acquire a fourth pressure value of the battery cell when the second pressure-maintaining time reaches a second preset time;

[0050] Calculating a second difference between the third pressure value and the fourth pressure value, and taking an absolute value of the second difference as a second pressure difference;

[0051] A second ratio of the second pressure difference to the second preset time length is calculated, wherein the second ratio is the re-tested leak rate.

[0052] With such an arrangement, the leakage of the battery cell can be quantified during the retest process, and the sealing problem of the battery cell can be determined by data comparison, thereby further improving the accuracy of determining the battery cell with sealing problems.

[0053] In some embodiments of the present application, under a first test condition, a negative pressure initial test is performed on the battery monomer, and the battery monomer that passes the initial test is screened out, wherein the first test condition includes evacuating the battery monomer to a first preset negative pressure, and under the first preset negative pressure, the electrolyte in the battery monomer does not enter the negative pressure cup, and the step includes:

[0054] Get the type of battery cell;

[0055] According to the type of the battery cell, the test negative pressure is matched in the negative pressure database, and the test negative pressure is calibrated as the first preset negative pressure.

[0056] With such a configuration, the first preset negative pressure in the initial test of the battery cell can be matched according to the type of the battery cell, thereby enabling initial tests to be performed on different types of battery cells and effectively improving the accuracy of the initial test.

[0057] In some embodiments of the present application, according to the type of the battery cell, in the step of matching the test negative pressure in the negative pressure database and calibrating the test negative pressure as the first preset negative pressure, the step of establishing the negative pressure database includes:

[0058] Vacuum test various types of battery cells to obtain multiple test negative pressures;

[0059] A mapping relationship between the type of battery cells and the test negative pressure is established to form a negative pressure database.

[0060] Such an arrangement can achieve data matching for different types of battery cells, thereby achieving testing of different battery cells, and further improving the effective detection of the sealing properties of different types of battery cells.

[0061] In some embodiments of the present application, in the step of performing a vacuum test on a plurality of different types of battery cells to obtain a plurality of test negative pressures, the vacuum test includes:

[0062] placing the battery cells on a formation device;

[0063] The battery cell is vacuumed to allow the electrolyte in the battery cell to enter the negative pressure cup of the formation equipment;

[0064] According to the pressure in the battery cell reaching the calibrated negative pressure, the vacuuming operation on the battery cell is stopped, wherein the absolute value of the calibrated negative pressure is greater than the absolute value of the second preset negative pressure;

[0065] Increasing the internal pressure of the battery cell to make the electrolyte in the negative pressure cup flow back into the interior of the battery cell, and detecting the current liquid level of the electrolyte in the negative pressure cup and the current pressure value of the battery cell;

[0066] When the current liquid level is zero, the current pressure value is recorded as the test negative pressure.

[0067] Such an arrangement can prevent the electrolyte in the battery cell from entering the negative pressure cup during the initial test of the battery cell, so as to achieve the initial test of the battery cell without the electrolyte leaving the battery cell, thereby reducing the leakage of electrolyte caused by the sealing problem of the battery cell.

[0068] A second aspect of the present application provides a formation device, which is used to implement the above-mentioned battery cell detection method.

[0069] In the present application, before the formation equipment forms the battery cells, the sealing of the battery cells needs to be tested. In the process of testing the sealing of the battery cells, the battery cells are first preliminarily tested using a first preset negative pressure, and the battery cells are screened for leakage without the electrolyte entering the negative pressure cup. The battery cells that pass the preliminarily test are then retested, and the battery cells are screened for leakage with the electrolyte entering the negative pressure cup. By preliminarily testing and retesting the battery cells respectively, the battery cells with sealing problems can be screened out, thereby reducing the leakage of the electrolyte of the battery cells during the test.

[0070] The third aspect of the present application proposes a battery production line, comprising the above formation equipment.

[0071] In the present application, when processing the battery monomer, the battery monomer needs to be formed. Before the formation equipment forms the battery monomer, the sealing of the battery monomer needs to be tested. In the process of testing the sealing of the battery monomer, the battery monomer is firstly tested using a first preset negative pressure, and the battery monomer is screened for leakage under the premise that the electrolyte does not enter the negative pressure cup. The battery monomer that passes the initial test is then retested, and the battery monomer is screened for leakage under the premise that the electrolyte enters the negative pressure cup. By performing initial and retests on the battery monomers respectively, the battery monomers with sealing problems can be screened out, thereby reducing the leakage of the electrolyte of the battery monomer during the test.

[0072] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 The flowchart of a method for detecting a battery cell according to an embodiment of the present application is schematically shown;

[0074] Figure 2 A partial structural diagram of a battery production line according to an embodiment of the present application is schematically shown;

[0075] Figure 3 A partial structural diagram of a formation device according to an embodiment of the present application is schematically shown.

[0076] The reference numerals are as follows:

[0077] 1000. Battery production line;

[0078] 100. Formation equipment;

[0079] 10. Negative pressure cup;

[0080] 200. Battery cell; 201. Electrolyte. DETAILED DESCRIPTION

[0081] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0082] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0083] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0084] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0085] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0086] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0087] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0088] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0089] At present, from the perspective of market development, the application of battery devices is becoming more and more extensive. Battery devices are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of battery devices, the market demand is also constantly expanding.

[0090] In the related art, a battery device includes a plurality of battery cells. During the manufacturing process, the battery cells need to be subjected to formation operations in order to activate the battery cells. Before the formation operations are performed on the battery cells, the leakage rate of the battery cells needs to be tested. However, during the testing process, the battery cells with unqualified leakage rates may leak electrolyte, and the leaked electrolyte may contaminate other battery cells.

[0091] In order to solve the above problems, a method for detecting battery cells is proposed in the present application, including setting the battery cells on a formation device, and connecting the negative pressure cup of the formation device to the inside of the battery cells. Under a first test condition, the battery cells are initially tested under negative pressure, and the battery cells that pass the initial test are screened out, wherein the first test condition includes evacuating the battery cells to a first preset negative pressure, and the electrolyte in the battery cells does not enter the negative pressure cup under the first preset negative pressure. Under a second test condition, the battery cells that pass the initial test are retested under negative pressure, and the battery cells that pass the retest are screened out, wherein the second test condition includes evacuating the battery cells to a second preset negative pressure, and the absolute value of the second preset negative pressure is greater than the absolute value of the first preset negative pressure, and the electrolyte in the battery cells enters the negative pressure cup under the second preset negative pressure. First, the battery cells are initially tested using the first preset negative pressure, and the battery cells are screened for leakage under the premise that the electrolyte does not enter the negative pressure cup, and then the battery cells that pass the initial test are retested, and the battery cells are screened for leakage under the premise that the electrolyte enters the negative pressure cup. By performing initial and retests on the battery cells separately, it is possible to screen out battery cells with sealing problems, thereby reducing electrolyte leakage.

[0092] When the electrical equipment used by the battery device is a vehicle, the vehicle may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A motor, a controller and a battery device may be arranged inside the vehicle, and the controller is used to control the battery device to power the motor. For example, a battery device may be arranged at the bottom, front or rear of the vehicle. The battery device may be used to power the vehicle, for example, the battery device may be used as an operating power source for the vehicle, for the circuit system of the vehicle, for example, for the working power requirements during the start-up, navigation and operation of the vehicle. In another embodiment of the present application, the battery device may not only be used as an operating power source for the vehicle, but also as a driving power source for the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0093] The battery apparatus mentioned above may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include a plurality of battery cells, which are connected in series, in parallel or in mixed connection through a busbar.

[0094] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells.

[0095] As an example, the battery cell assembly may be a battery module, which is formed by arranging and fixing a plurality of battery cells to form an independent module. As an example, the battery module may be formed by bundling a plurality of battery cells by a cable tie.

[0096] In some embodiments, the battery device may be a battery pack, which includes a case and one or more battery cell assemblies, wherein the battery cell assemblies are accommodated in the case.

[0097] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box by fixing the battery module in the box.

[0098] As an example, the battery cell assembly may also be housed in the case by directly fixing a plurality of battery cells to the case.

[0099] As an example, the box may include a first box and a second box. The first box and the second box are buckled together to form a closed space inside the box to accommodate the battery cell assembly. The closed here means covered or closed, which can be sealed or unsealed. The first box can be a top cover or a bottom plate.

[0100] As an example, the box body may include a top cover, a frame and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that a closed space is formed inside the box body to accommodate the battery cell assembly.

[0101] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0102] The technical solutions described in the embodiments of the present application are applicable to various electrical devices that use battery cells, such as mobile phones, portable devices, laptop computers, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, for example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.

[0103] In some embodiments of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0104] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiments of the present application.

[0105] In some embodiments of the present application, a battery cell includes a shell, a pressure relief mechanism, an electrode assembly and an insulating member, the shell includes a plurality of side walls, the plurality of side walls include a first side wall, a pressure relief mechanism is provided on the first side wall, the pressure relief mechanism is configured to open or close according to whether the internal pressure of the shell reaches a pressure threshold, the electrode assembly is arranged inside the shell, the insulating member is arranged inside the shell and between the shell and the electrode assembly, and is used to insulate and isolate the shell and the electrode assembly, and the insulating member abuts against the electrode assembly.

[0106] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery, etc. There is no special limitation in this application.

[0107] The electrode assembly includes a positive electrode, a negative electrode, and a separator, which is arranged between the negative electrode and the positive electrode. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0108] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0109] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0110] As an example, the positive electrode current collector may be a metal foil, a conductive polymer material, a carbon material or a composite current collector. For example, as a metal foil, a pure metal, an alloy, a surface-treated metal, including but not limited to stainless steel, copper, aluminum, nickel, titanium or silver, etc., may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0111] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) and at least one of its modified compounds. The modified compound refers to a substance obtained by modifying the above substances by means of doping or coating.

[0112] In some embodiments, the positive electrode may be a foamed metal. The foamed metal may be a foamed nickel, a foamed copper, a foamed aluminum, a foamed alloy, or a foamed carbon. When the foamed metal is used as the positive electrode, the positive electrode active material may not be disposed on the surface of the foamed metal, but of course, the positive electrode active material may also be disposed. As an example, the positive electrode active material is filled or / and deposited in the foamed metal.

[0113] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0114] As an example, the negative electrode current collector may be a metal foil, a conductive polymer material, a carbon material or a composite current collector. For example, as the metal foil, a pure metal, an alloy, a surface-treated metal, including but not limited to stainless steel, copper, aluminum, nickel, titanium or silver, etc., may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0115] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0116] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0117] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0118] In some embodiments, the negative electrode may be a foam metal. The foam metal may be foam nickel, foam copper, foam aluminum, foam alloy, or foam carbon, etc. When the foam metal is used as the negative electrode sheet, the surface of the foam metal may not be provided with a negative electrode active material, but of course, a negative electrode active material may also be provided.

[0119] As an example, a negative electrode active material may be filled and / or deposited in the negative electrode current collector.

[0120] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0121] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0122] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical stability and mechanical stability can be selected.

[0123] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without special restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without special restrictions. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surface of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be coated on the surface of the separator.

[0124] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0125] The electrode assembly may be a wound structure, a laminated structure, or a mixed structure of a wound structure and a laminated structure.

[0126] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0127] In some embodiments, the electrode assembly is a laminate structure.

[0128] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets may be alternately stacked.

[0129] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0130] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded sections that are stacked.

[0131] As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0132] As an example, the separator may be disposed continuously, and disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0133] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0134] In some embodiments, the electrode sheet of the electrode assembly is provided with a tab, which can lead current out of the electrode assembly. The tab includes a positive tab and a negative tab.

[0135] In some embodiments, a pressure relief mechanism is provided on the housing, and the pressure relief mechanism is used to discharge the internal gas of the battery cell.

[0136] As an example, when the internal pressure or temperature of the battery cell reaches a predetermined threshold, it is actuated to release the internal pressure or temperature. When the internal pressure or temperature of the battery cell reaches a predetermined threshold, the pressure relief mechanism performs an action or a weak structure provided in the pressure relief mechanism is destroyed, thereby forming an opening or channel for the internal pressure or temperature to be released. The threshold design varies according to different design requirements. The threshold may depend on one or more materials of the positive electrode sheet, negative electrode sheet, electrolyte and separator in the battery cell.

[0137] As an example, the pressure relief mechanism may be integrally formed with the housing.

[0138] As an example, the pressure relief mechanism may also be separately provided and connected to the housing.

[0139] The "actuation" mentioned in this application means that the pressure relief mechanism is in action or activated to a certain state, so that the internal pressure and temperature of the battery cell can be released. The action produced by the pressure relief mechanism may include but is not limited to: the components in the pressure relief mechanism move to form an exhaust channel, at least a part of the pressure relief mechanism ruptures, breaks, is torn or opened, etc. When the pressure relief mechanism is actuated, the high-temperature and high-pressure substances inside the battery cell will be discharged from the actuated part as emissions. In this way, the battery cell can be depressurized and cooled under controllable pressure or temperature, thereby reducing the potential for more serious accidents.

[0140] In some embodiments, when the outer shell is a non-sealed structure, the pressure relief mechanism can be set as a through hole to discharge the gas inside the battery cell.

[0141] The emissions from the battery cells mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode sheets, fragments of separators, high-temperature and high-pressure gases produced by the reaction, flames, and the like.

[0142] The positive electrode tab and the negative electrode tab can be led out from the same end of the electrode sheet, or can be led out from opposite ends of the electrode sheet respectively.

[0143] The structures of the positive electrode tab and the negative electrode tab may be the same or different. Taking the positive electrode tab as an example, the positive electrode tab may include multiple positive electrode tab layers, and multiple positive electrode tab layers are stacked together to form the positive electrode tab. The positive electrode tab may include at least two parts, one part is located between the main body of the pole piece and the insulating member, and the other part is located between the insulating member and the electrode lead-out member.

[0144] The insulating member can insulate at least part of the pole ear from the end face of the main body, thereby reducing the risk of the pole ear being inserted into the main body when the battery cell is affected by external impact, vibration, etc., thereby reducing the risk of short circuit in the battery cell and helping to improve the reliability of the battery cell.

[0145] The insulating member may be an integral structure or a split structure. As an example, the insulating member is formed by connecting a plurality of independently formed parts. As another example, the insulating member is integrally formed by stamping.

[0146] For example, the insulating part is a plastic part, and the insulating part which is a plastic part is integrally formed by injection molding. The processing of the plastic part is convenient, and the manufacturing cost of the plastic part is low.

[0147] In some embodiments of the present application, the housing includes a shell and an end cover, the shell has an opening, the end cover is connected to the shell and closes the opening, the end cover constitutes a first side wall, and the pressure relief mechanism is arranged on the end cover.

[0148] In some embodiments of the present application, the shell can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell) or an aluminum-plastic film, etc. In some embodiments, the shell can be a sealed structure or a non-sealed structure. As an example, when the shell is a non-sealed structure, the shell plays a role in protecting the electrode assembly, and a sealed bag is also included between the shell and the electrode assembly, and the sealed bag is used to encapsulate the electrode assembly and the electrolyte. Specifically, the sealed bag can be a bag-shaped insulating member or an aluminum-plastic film. When the shell is a sealed structure, it is used to encapsulate components such as the electrode assembly and the electrolyte. The shell may be provided with one or more openings. One or more end caps may also be provided.

[0149] In addition, the connection methods between the end cover and the shell include but are not limited to snap connection, bonding, welding or connection via a connector.

[0150] In some embodiments of the present application, the battery cell further includes an electrode terminal, which is disposed on the end cap and electrically connected to the electrode assembly. The electrode terminal is electrically connected to the pole tab of the electrode assembly. The electrode terminal may be directly connected to the pole tab or indirectly connected to the pole tab through a current collecting member. The electrode terminal may be disposed on the end cap or on the housing. In the embodiments shown in the present application, the electrode terminal is disposed on the end cap.

[0151] In order for the battery cells to work properly, the battery cells need to be formed, and the battery cells are formed on a formation device.

[0152] After the battery cell is filled with liquid, it needs to be activated by the first charge and a dense SEI film (solid electrolyte interphase) is formed at the anode to ensure the cycle life of the battery cell, thereby completing the formation operation of the battery cell.

[0153] During the first charging process of a battery cell, the electrolyte inside the battery cell participates in the redox reaction to generate a large amount of gas. In order to discharge the generated gas in a timely and effective manner during the process, it is necessary to perform a leakage rate test on the battery cell before the process starts, that is, the formation leak detection process.

[0154] During the test, the suction nozzle of the negative pressure cup of the formation equipment is pressed against the liquid injection hole, the negative pressure valve of the pipe connected to the negative pressure cup is opened, and the vacuum is drawn to the set value to maintain the pressure. After maintaining the pressure for a certain period of time, it is determined whether the leakage rate of the battery cell is qualified. If the leakage rate is qualified, the next step of the process is continued; if the leakage rate is unqualified, the formation press is directly disengaged and an alarm is sounded.

[0155] However, since the maximum negative pressure used in the formation process is generally large, the electrolyte will be drawn into the negative pressure cup under high negative pressure. When there is a problem with the sealing of the battery cell, air will enter the negative pressure cup. After the pressure holding test, the electrolyte in the negative pressure cup cannot be completely "sucked" into the interior of the battery cell. At the same time, due to unqualified leakage rate, the formation press is disengaged. When the suction nozzle is disengaged, the residual electrolyte in the negative pressure cup will spray onto the top cover of the battery cell, causing the battery cell to be scrapped, which increases the defective rate of the battery cell.

[0156] like Figures 1 to 3 As shown, some embodiments of the present application provide a method for detecting a battery cell 200, the method comprising:

[0157] S10 : placing the battery cell 200 on the formation equipment 100 .

[0158] Specifically, before performing the formation operation on the battery cell 200, it is necessary to test the sealing of the battery cell 200. When performing the sealing test, the battery cell 200 is placed on the formation equipment 100, and the formation press fixes the battery cell 200 on the formation equipment 100, thereby fixing the position of the battery cell 200, so as to test the sealing of the battery cell 200.

[0159] S20 : ​​connecting the negative pressure cup 10 of the formation equipment 100 to the interior of the battery cell 200 .

[0160] Specifically, after the battery cell 200 is fixed on the formation equipment 100, the sealing of the battery cell 200 needs to be tested before the formation operation is performed on the battery cell 200. The negative pressure cup 10 of the vacuum pumping device of the formation equipment 100 cooperates with the battery cell 200, and the interior of the battery cell 200 is connected to the negative pressure cup 10, so that the vacuum pumping device can perform a vacuum operation on the battery cell 200, thereby completing the sealing test of the battery cell 200.

[0161] Furthermore, the negative pressure cup 10 includes a pressure nozzle, which is pressed against the end cover of the battery cell 200 and is connected to the injection hole on the end cover. The vacuum device performs a vacuum operation on the battery cell 200 through the pressure nozzle on the negative pressure cup 10, so as to detect the sealing of the battery cell 200 under the vacuum condition.

[0162] S30: Under a first test condition, the battery cell 200 is subjected to an initial negative pressure test, and the battery cells 200 that pass the initial test are screened out, wherein the first test condition includes evacuating the battery cell 200 to a first preset negative pressure, under which the electrolyte 201 in the battery cell 200 does not enter the negative pressure cup 10.

[0163] Specifically, the battery cell 200 is initially tested for negative pressure under the first test condition. During the test, the vacuum pumping device performs a vacuum operation on the battery cell 200. When the pressure inside the battery cell 200 reaches the first preset negative pressure, the vacuum pumping device stops vacuuming the battery cell 200. At this time, the electrolyte 201 inside the battery cell 200 has not left the interior of the battery cell 200 and entered the negative pressure cup 10.

[0164] In the present application, when the internal pressure of the battery cell 200 reaches the first preset negative pressure, the electrolyte 201 in the battery cell 200 will not flow out from the injection hole on the end cover.

[0165] Under the first test condition, since the electrolyte 201 inside the battery cell 200 does not enter the negative pressure cup 10, the battery cell 200 is tested under this test condition, which can screen out the battery cells 200 with poor sealing, thereby reducing the situation where the electrolyte 201 of the battery cells 200 with poor sealing enters the negative pressure cup 10 and causes leakage of the electrolyte 201.

[0166] It should be understood that during the negative pressure test, the vacuum pumping device performs a vacuum operation on the battery cell 200, and the internal pressure of the battery cell 200 is less than zero. When the internal pressure of the battery cell 200 reaches the first preset negative pressure, the vacuum pumping device stops operating, and the first preset negative pressure at this time is also less than zero.

[0167] In some embodiments of the present application, under a first test condition, a negative pressure initial test is performed on the battery cell 200, and the battery cell 200 that passes the initial test is screened out, wherein the first test condition includes evacuating the battery cell 200 to a first preset negative pressure, and under the first preset negative pressure, the electrolyte 201 in the battery cell 200 does not enter the negative pressure cup 10, specifically including the following steps:

[0168] S31: Obtain the type of the battery cell 200 .

[0169] Specifically, different types of battery cells 200 need to be tested under different test parameters to improve the accuracy of the test. Based on this, it is necessary to obtain the type of the battery cell 200 to match the corresponding test parameters according to the type of the battery cell 200.

[0170] S32: According to the type of the battery cell 200 , match the test negative pressure in the negative pressure database, and calibrate the test negative pressure as the first preset negative pressure.

[0171] With such configuration, the first preset negative pressure during the initial test of the battery cell 200 can be matched according to the type of the battery cell 200, thereby enabling initial tests on different types of battery cells 200 and effectively improving the accuracy of the initial test.

[0172] Furthermore, the negative pressure database is stored in the control device of the formation equipment 100, and the type of the corresponding battery cell 200 is input. The control device matches the type of the battery cell 200 with the data in the negative pressure database so that the battery cell 200 matches the best first preset negative pressure.

[0173] Among them, the negative pressure database is established through the following steps:

[0174] S01: Performing a vacuum test on a plurality of different types of battery cells 200 to obtain a plurality of test negative pressures.

[0175] Specifically, on the formation equipment 100, a vacuum test is performed on the battery cell 200. When the liquid level of the electrolyte 201 of the battery cell 200 reaches the highest liquid level of the battery cell 200 (that is, the critical position where the electrolyte 201 is about to flow out of the battery cell 200), the internal pressure of the current type of battery cell 200 is recorded. The internal pressure is the test negative pressure (the first preset negative pressure). By replacing different types of battery cells 200, multiple test negative pressures can be obtained.

[0176] S02: Establishing a mapping relationship between the type of the battery cell 200 and the test negative pressure to form a negative pressure database.

[0177] Specifically, a mapping relationship is formed between the type of each battery cell 200 and its corresponding test negative pressure, thereby forming a negative pressure database.

[0178] Such an arrangement can achieve data matching for different types of battery cells 200 , thereby achieving testing of different battery cells 200 , and further improving the effective detection of the sealing properties of different types of battery cells 200 .

[0179] In some embodiments of the present application, a vacuum test is performed on a plurality of different types of battery cells 200 to obtain a plurality of test negative pressures. The vacuum test includes:

[0180] S011 : placing the battery cell 200 on the formation equipment 100 .

[0181] Specifically, the battery cell 200 is fixed on the formation equipment 100 , and the vacuum device of the formation equipment 100 is connected to the interior of the battery through the injection hole on the end cover of the battery cell 200 , so that the vacuum device performs a vacuum operation on the battery cell 200 .

[0182] S012 : vacuumizing the battery cell 200 so that the electrolyte 201 in the battery cell 200 enters the negative pressure cup 10 of the formation equipment 100 .

[0183] S013: according to the pressure in the battery cell 200 reaching the calibrated negative pressure, the vacuuming operation on the battery cell 200 is stopped, wherein the absolute value of the calibrated negative pressure is greater than the absolute value of the second preset negative pressure.

[0184] S014 : increasing the internal pressure of the battery cell 200 to make the electrolyte 201 in the negative pressure cup 10 flow back into the battery cell 200 , and detecting the current liquid level of the electrolyte 201 in the negative pressure cup 10 and the current pressure value of the battery cell 200 .

[0185] S015: When the current liquid level is zero, the current pressure value is recorded as the test negative pressure.

[0186] Such a configuration can prevent the electrolyte 201 in the battery cell 200 from entering the negative pressure cup 10 during the initial test of the battery cell 200, so as to achieve the initial test of the battery cell 200 without the electrolyte 201 leaving the battery cell 200, thereby reducing the leakage of the electrolyte 201 due to the sealing problem of the battery cell 200.

[0187] S33: performing a first vacuuming operation on the battery cell 200 .

[0188] Specifically, the battery cell 200 is fixed on the formation equipment 100, and the vacuum pumping device of the formation equipment 100 is connected to the interior of the battery cell 200. The battery cell 200 is initially tested under the first test condition. The vacuum pumping device is operated to vacuum the battery cell 200 so that the interior of the battery cell 200 is in a negative pressure state, so as to detect the sealing of the battery cell 200.

[0189] It should be understood that, under the first test condition, when the vacuum extraction device performs a vacuum extraction operation on the battery cell 200 , the outer shell of the battery cell 200 may or may not be deformed.

[0190] S34: When the internal pressure of the battery cell 200 reaches the first preset negative pressure, the first vacuuming operation is terminated.

[0191] Specifically, the battery cell 200 is initially tested under a first test condition, the vacuum pumping device performs a vacuum pumping operation on the battery cell 200, and the internal pressure of the battery cell 200 is detected during the vacuum pumping process. When the internal pressure of the battery cell 200 reaches a first preset negative pressure, the vacuum pumping device is stopped to stop the vacuum pumping operation, so as to test the sealing of the battery cell 200.

[0192] S35: performing the first pressure maintaining operation on the battery cell 200 and timing the pressure maintaining process.

[0193] Specifically, the battery cell 200 is initially tested under the first test condition, and the vacuum pumping device performs a vacuum pumping operation on the battery cell 200. When the internal pressure of the battery cell 200 reaches a first preset negative pressure, the vacuum pumping device is stopped, so that the battery cell 200 enters a first pressure-maintaining state, and timing is performed when the vacuum pumping device stops running, so as to time the first pressure-maintaining time of the battery cell 200, and the leakage rate of the battery cell 200 is calculated using the first pressure-maintaining time, and the sealing of the battery cell 200 is judged based on the calculated leakage rate, so as to screen out the battery cell 200 with sealing problems.

[0194] S36: Calculating the initial leakage rate of the battery cell 200 according to the first pressure maintenance time reaching the first preset time.

[0195] Specifically, the battery cell 200 is initially tested under the first test condition. After the vacuum pumping device completes the vacuum pumping operation on the battery cell 200, the battery cell 200 enters a pressure holding state, and timing is performed from the time when the vacuum pumping device stops. When the first pressure holding time reaches a first preset time, the initial leakage rate of the battery cell 200 is calculated.

[0196] In some embodiments of the present application, the first preset duration is in the range of 60 seconds to 180 seconds.

[0197] By setting the first preset time in the range of 60 seconds to 180 seconds, the battery cells 200 can be kept under pressure for a sufficient time during the initial test, thereby further improving the accuracy of screening the battery cells 200 with sealing problems.

[0198] It should be pointed out that the first preset duration can be 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 110 seconds, 120 seconds, 130 seconds, 140 seconds, 150 seconds, 160 seconds, 170 seconds, or 180 seconds.

[0199] The step of calculating the initial leakage rate of the battery cell 200 according to the first pressure holding time reaching the first preset time specifically includes the following steps:

[0200] S361: Acquire a first pressure value of the battery cell 200 when the first vacuuming is completed.

[0201] Specifically, the battery cell 200 is initially tested under the first test condition. After the vacuum pumping device completes the vacuum pumping operation on the battery cell 200, the battery cell 200 enters a pressure-maintaining state, and timing is performed from the time when the vacuum pumping device stops. The internal pressure of the battery cell 200 at the start of timing is obtained, and the pressure is recorded as a first pressure value.

[0202] It should be understood that the first pressure value is the maximum pressure value of the battery cell 200 in the pressure-maintaining state. During the pressure-maintaining period, the internal pressure of the battery cell 200 will decrease. The sealing of the battery cell 200 is judged based on the pressure change inside the battery cell 200, thereby improving the accuracy of the judgment.

[0203] S362: Obtain a second pressure value of the battery cell 200 when the first pressure-maintaining time reaches a first preset time.

[0204] Specifically, the battery cell 200 is initially tested under the first test condition. After the vacuum pumping device completes the vacuum pumping operation on the battery cell 200, the battery cell 200 enters a pressure-maintaining state, and timing is performed from the time when the vacuum pumping device stops. The internal pressure of the battery cell 200 at the start of timing is obtained, and the pressure is recorded as a first pressure value. When the pressure-maintaining state of the battery cell 200 reaches a first pressure-maintaining time, the internal pressure of the battery cell 200 at this moment is obtained and recorded as a second pressure value.

[0205] It should be understood that the second pressure value is the minimum pressure value of the battery cell 200 in the pressure-maintaining state within the first pressure-maintaining time period.

[0206] S363: Calculate a first difference between the first pressure value and the second pressure value, and take an absolute value of the first difference as a first pressure difference.

[0207] Specifically, the absolute value of the first pressure value is greater than or equal to the absolute value of the second pressure value. During the calculation process, the second pressure value is subtracted from the first pressure value to obtain a first difference, which is a negative value. The first pressure difference is obtained by taking the absolute value of the first difference, and the first pressure difference is used to determine whether there is a problem with the sealing of the battery cell 200.

[0208] S364: Calculate a first ratio of the first pressure difference to the first preset time length, wherein the first ratio is an initial leak rate.

[0209] Specifically, during the calculation, the first pressure value is subtracted from the second pressure value to obtain a first difference, and the absolute value of the first difference is taken to obtain a first pressure difference, and then the first pressure difference is divided by a first preset time length to obtain the pressure change rate of the battery cell 200 during the pressure maintenance period under the first test condition. The pressure change rate is the initial leakage rate of the battery cell 200. The sealing of the battery cell 200 is judged based on the initial leakage rate, thereby screening out battery cells 200 with sealing problems.

[0210] In the step of calculating the initial leakage rate of the battery cell 200 based on the first pressure holding time reaching the first preset time, by setting steps S361 to S364, the leakage situation of the battery cell 200 can be quantified in the initial test process, and the data comparison can be used to determine whether there is a problem with the sealing of the battery cell 200, thereby further improving the accuracy of determining the battery cell 200 with sealing problems.

[0211] S37: Screening whether the initially tested battery cells 200 are qualified according to the initially tested leakage rate.

[0212] In some embodiments of the present application, the step of screening whether the initially tested battery cells 200 are qualified according to the initially tested leakage rate specifically includes the following steps:

[0213] S371: Compare the initial leak rate with the first preset value.

[0214] Specifically, the battery cell 200 is initially tested under the first test condition. After the vacuum pumping device completes the vacuum pumping operation on the battery cell 200, the battery cell 200 enters a pressure-maintaining state, and timing is performed from the time when the vacuum pumping device stops, the internal pressure of the battery cell 200 at the start of timing is obtained, and the pressure is recorded as a first pressure value. When the pressure-maintaining state of the battery cell 200 reaches a first pressure-maintaining time, a second pressure value of the battery cell 200 is recorded, a first pressure difference of the battery cell 200 is calculated based on the first pressure value and the second pressure value, and the initial leakage rate is obtained by the ratio of the first pressure difference to the first preset time.

[0215] The initial leakage rate is compared with the first preset value, and the sealing performance of the battery is judged according to the comparison result.

[0216] It should be understood that the comparison between the initial leak rate and the first preset value is a comparison of the numerical values ​​of the two.

[0217] In some embodiments of the present application, the first preset value is in the range of 2 kPa / min to 5 kPa / min. Such a setting can improve the accuracy of screening battery cells 200 with sealing problems during the initial test of the battery cells 200, and further reduce the leakage of the electrolyte 201 of the battery cells 200 during the test.

[0218] It should be pointed out that the first preset value can specifically be 2 kPa / min, 2.5 kPa / min, 3 kPa / min, 3.5 kPa / min, 4 kPa / min, 4.5 kPa / min, or 5 kPa / min.

[0219] S372: When the initial leak rate is greater than or equal to the first preset value, the battery cell 200 is determined to be unqualified in the initial test.

[0220] Specifically, when the initial leak rate is greater than or equal to the first preset value, the battery cell 200 is determined to be unqualified in the initial test, and the unqualified battery cell 200 is separated from the formation equipment 100 to discharge the battery cell 200 with sealing problems.

[0221] S373: When the initial leakage rate is less than the first preset value, the battery cell 200 is determined to be qualified in the initial test.

[0222] Specifically, when the initial leak rate is less than the first preset value, the battery cell 200 is determined to be qualified in the initial test, and the qualified battery cell 200 is kept on the formation equipment 100 so as to be retested.

[0223] In the step of screening whether the battery cell 200 is qualified in the initial test according to the initial test leakage rate, steps S371 to S373 are set, by comparing the initial test leakage rate of the battery cell 200 with a preset first preset value, and judging whether there is a problem with the sealing of the battery cell 200 according to the comparison result, thereby achieving initial screening of the battery cell 200 with sealing problems, thereby reducing the situation where the electrolyte 201 of the battery cell 200 leaks during the test due to the sealing problems of the battery cell 200.

[0224] Under the first test condition, the battery cell 200 is initially tested under negative pressure, and the battery cells 200 that pass the initial test are screened out, wherein the first test condition includes evacuating the battery cell 200 to a first preset negative pressure, and in the step of the electrolyte 201 in the battery cell 200 not entering the negative pressure cup 10 under the first preset negative pressure, by setting steps S31 to S37, the battery cell 200 can be initially tested under the condition of a low preset negative pressure, thereby screening out the battery cell 200 with sealing problems when the electrolyte 201 does not enter the negative pressure cup 10, thereby reducing the situation where the electrolyte 201 of the battery cell 200 leaks during the test due to the sealing problems of the battery cell 200 after the electrolyte 201 enters the negative pressure cup 10 under the condition of high preset negative pressure.

[0225] S40: Under the second test condition, the battery cells 200 that have passed the initial test are retested under negative pressure, and the battery cells 200 that have passed the retest are screened out, wherein the second test condition includes evacuating the battery cells 200 to a second preset negative pressure, the absolute value of the second preset negative pressure is greater than the absolute value of the first preset negative pressure, and under the second preset negative pressure, the electrolyte 201 in the battery cells 200 enters the negative pressure cup 10.

[0226] Specifically, in the present application, the battery cells 200 are initially tested using the first preset negative pressure, and the battery cells 200 are screened for leakage without the electrolyte 201 entering the negative pressure cup 10. Then, the battery cells 200 that have passed the initial test are retested, and the battery cells 200 are screened for leakage without the electrolyte 201 entering the negative pressure cup 10. By performing initial and retests on the battery cells 200, the battery cells 200 with sealing problems can be screened out, thereby reducing the leakage of the electrolyte 201 of the battery cells 200 during the test.

[0227] In the present application, when the internal pressure of the battery cell 200 reaches the second preset negative pressure, the electrolyte 201 in the battery cell 200 will flow out from the injection hole on the end cover and enter the negative pressure cup 10. When the re-test is completed, the pressure in the battery cell 200 returns to normal. At this time, the electrolyte 201 in the negative pressure cup 10 flows back into the battery cell 200, thereby reducing the overflow of the electrolyte 201.

[0228] Under the second test condition, since the electrolyte 201 inside the battery cell 200 enters the negative pressure cup 10, testing the battery cell 200 under this test condition can further screen out the battery cell 200 with poor sealing, thereby reducing the problem of battery cell 200 failure due to unqualified sealing.

[0229] It should be understood that during the negative pressure test, the vacuum pumping device performs a vacuum operation on the battery cell 200, and the internal pressure of the battery cell 200 is less than zero. When the internal pressure of the battery cell 200 reaches the second preset negative pressure, the vacuum pumping device stops operating, and the second preset negative pressure at this time is also less than zero.

[0230] In some embodiments of the present application, under the second test condition, the battery cells 200 that have passed the initial test are retested under negative pressure, and the battery cells 200 that have passed the retest are screened out, wherein the second test condition includes evacuating the battery cells 200 to a second preset negative pressure, the absolute value of the second preset negative pressure is greater than the absolute value of the first preset negative pressure, and under the second preset negative pressure, the electrolyte 201 in the battery cells 200 enters the negative pressure cup 10, specifically including the following steps:

[0231] S41: performing a second vacuuming operation on the battery cells 200 that have passed the initial test.

[0232] Specifically, the battery cell 200 is fixed on the formation equipment 100, and the vacuum pumping device of the formation equipment 100 is connected to the interior of the battery cell 200. The battery cell 200 is initially tested under the first test condition, and the vacuum pumping device is operated to vacuum the battery cell 200 so that the interior of the battery cell 200 is in a negative pressure state, so as to detect the sealing of the battery cell 200. When the battery cell 200 passes the initial test, the vacuum pumping device performs a second vacuum pumping operation on the battery cell 200 that has passed the initial test.

[0233] It should be understood that, under the second test condition, when the vacuum extraction device performs a vacuum extraction operation on the battery cell 200 , the outer shell of the battery cell 200 may be deformed.

[0234] S42: When the internal pressure of the battery cell 200 reaches the second preset negative pressure, the second vacuuming operation is terminated.

[0235] Specifically, the battery cell 200 is retested under the second test condition, the vacuum pumping device performs a vacuum pumping operation on the battery cell 200, and the internal pressure of the battery cell 200 is detected during the vacuum pumping process. When the internal pressure of the battery cell 200 reaches a second preset negative pressure, the vacuum pumping device is stopped to stop the vacuum pumping operation, so as to test the sealing of the battery cell 200.

[0236] It should be noted that the second preset negative pressure is greater than or equal to the maximum negative pressure capacity of the vacuum pumping device, and the second preset negative pressure is less than or equal to the maximum negative pressure used in the formation process.

[0237] S43: performing a second pressure maintaining operation on the battery cell 200 and timing the pressure maintaining process.

[0238] Specifically, the battery cell 200 is retested under the second test condition, and the vacuum pumping device performs a vacuum pumping operation on the battery cell 200. When the internal pressure of the battery cell 200 reaches the second preset negative pressure, the vacuum pumping device is stopped, so that the battery cell 200 enters the second pressure holding state, and timing is performed when the vacuum pumping device stops running, so as to time the second pressure holding time of the battery cell 200, and the leakage rate of the battery cell 200 is calculated using the second pressure holding time, and the sealing of the battery cell 200 is judged based on the calculated leakage rate, so as to screen out the battery cell 200 with sealing problems.

[0239] S44: Calculating the retest leakage rate of the battery cell 200 according to the second pressure maintaining time reaching the second preset time.

[0240] Specifically, the battery cell 200 is retested under the second test condition. After the vacuum pumping device completes the vacuum pumping operation on the battery cell 200, the battery cell 200 enters a pressure holding state, and timing is started from when the vacuum pumping device stops. When the second pressure holding time reaches a second preset time, the retest leakage rate of the battery cell 200 is calculated.

[0241] In some embodiments of the present application, the second preset duration is in the range of 60 seconds to 180 seconds.

[0242] By setting the second preset time in the range of 60 seconds to 180 seconds, the battery cells 200 can be kept under pressure for a sufficient period of time during the retest, thereby further improving the accuracy of screening the battery cells 200 with sealing problems.

[0243] It should be noted that the second preset duration can be 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 110 seconds, 120 seconds, 130 seconds, 140 seconds, 150 seconds, 160 seconds, 170 seconds, or 180 seconds.

[0244] The step of calculating the retest leakage rate of the battery cell 200 according to the second pressure holding time reaching the second preset time specifically includes the following steps:

[0245] S441: Acquire a third pressure value of the battery cell 200 when the second vacuuming is completed.

[0246] Specifically, the battery cell 200 is retested under the second test condition. After the vacuum pumping device completes the vacuum pumping operation on the battery cell 200, the battery cell 200 enters a pressure maintaining state, and timing is performed from the time when the vacuum pumping device stops. The internal pressure of the battery cell 200 at the start of timing is obtained, and the pressure is recorded as the third pressure value.

[0247] It should be understood that the third pressure value is the maximum pressure value of the battery cell 200 in the pressure maintaining state. During the pressure maintaining period, the internal pressure of the battery cell 200 will decrease. The sealing of the battery cell 200 is judged based on the pressure change inside the battery cell 200, thereby improving the accuracy of the judgment.

[0248] S442: Obtaining a fourth pressure value of the battery cell 200 when the second pressure-maintaining time reaches a second preset time;

[0249] Specifically, the battery cell 200 is retested under the second test condition. After the vacuum pumping device completes the vacuum pumping operation on the battery cell 200, the battery cell 200 enters a pressure-maintaining state, and timing is performed from the time when the vacuum pumping device stops. The internal pressure of the battery cell 200 at the start of timing is obtained, and the pressure is recorded as a third pressure value. When the pressure-maintaining state of the battery cell 200 reaches the second pressure-maintaining time, the internal pressure of the battery cell 200 at this moment is obtained and the pressure is recorded as a fourth pressure value.

[0250] It should be understood that the fourth pressure value is the minimum pressure value of the battery cell 200 in the pressure-maintaining state within the second pressure-maintaining time period.

[0251] S443: Calculate a second difference between the third pressure value and the fourth pressure value, and take an absolute value of the second difference as a second pressure difference.

[0252] Specifically, the absolute value of the third pressure value is greater than or equal to the absolute value of the fourth pressure value. During the calculation process, the fourth pressure value is subtracted from the third pressure value to obtain a second difference, which is a negative value. The second pressure difference is obtained by taking the absolute value of the second difference, and the second pressure difference is used to determine whether there is a problem with the sealing of the battery cell 200.

[0253] S444: Calculate a second ratio of the second pressure difference to the second preset time length, wherein the second ratio is the re-measured leakage rate.

[0254] Specifically, during the calculation, the fourth pressure value is subtracted from the third pressure value to obtain a second difference, and the second difference is taken as the absolute value to obtain the second pressure difference, and then the second pressure difference is divided by the second preset time length to obtain the pressure change rate of the battery cell 200 during the pressure maintenance period under the second test condition. The pressure change rate is the re-tested leakage rate of the battery cell 200. The sealing of the battery cell 200 is judged based on the re-tested leakage rate, thereby screening out the battery cell 200 with sealing problems.

[0255] In the step of calculating the retest leakage rate of the battery cell 200 based on the second pressure holding time reaching the second preset time, by setting steps S441 to S444, the leakage situation of the battery cell 200 can be quantified in the process of the retest, and it is possible to judge whether there is a problem with the sealing of the battery cell 200 by data comparison, thereby further improving the accuracy of judging the battery cell 200 with sealing problems.

[0256] S45: Screening whether the battery cells 200 are qualified in the retest according to the retest leakage rate.

[0257] In some embodiments of the present application, the step of screening whether the battery cell 200 is qualified in the initial test according to the retest leakage rate specifically includes the following steps:

[0258] S451: Compare the retested leak rate with the second preset value.

[0259] Specifically, the battery cell 200 is retested under the second test condition. After the vacuum pumping device completes the vacuum pumping operation on the battery cell 200, the battery cell 200 enters a pressure-maintaining state, and timing is performed from the time when the vacuum pumping device stops, the internal pressure of the battery cell 200 at the start of timing is obtained, and the pressure is recorded as a third pressure value. When the pressure-maintaining state of the battery cell 200 reaches a second pressure-maintaining time, a fourth pressure value of the battery cell 200 is recorded, and a second pressure difference of the battery cell 200 is calculated based on the third pressure value and the fourth pressure value, and the retest leakage rate is obtained by the ratio of the second pressure difference to the second preset time.

[0260] The retested leakage rate is compared with the second preset value, and the sealing performance of the battery is judged according to the comparison result.

[0261] It should be understood that the comparison between the re-tested leakage rate and the second preset value is a comparison of the numerical values ​​of the two.

[0262] In some embodiments of the present application, the second preset value is in the range of 2 kPa / min to 5 kPa / min. In this way, the accuracy of screening battery cells 200 with sealing problems can be improved during the retest of the battery cells 200, and the leakage of the electrolyte 201 of the battery cells 200 during the test can be further reduced.

[0263] It should be pointed out that the second preset value can specifically be 2 kPa / min, 2.5 kPa / min, 3 kPa / min, 3.5 kPa / min, 4 kPa / min, 4.5 kPa / min, or 5 kPa / min.

[0264] S452: When the retest leakage rate is greater than or equal to the second preset value, it is determined that the battery cell 200 is unqualified in the retest.

[0265] Specifically, when the retested leakage rate is greater than or equal to the second preset value, the battery cell 200 is determined to have failed the initial test, and the battery cell 200 that has failed the initial test is separated from the formation equipment 100 to discharge the battery cell 200 with sealing problems.

[0266] S453: When the retested leakage rate is less than the second preset value, it is determined that the battery cell 200 is qualified in the retest.

[0267] Specifically, when the retested leakage rate is less than the second preset value, the battery cell 200 is determined to be qualified in the initial test, and the qualified battery cell 200 is kept on the formation equipment 100 so as to perform a formation operation on the qualified retested battery cell 200.

[0268] Under the second test condition, in the step of screening whether the retest of the battery cell 200 is qualified according to the retest leakage rate, steps S451 to S453 are set, by comparing the retest leakage rate of the battery cell 200 with a preset second preset value, and judging whether there is a problem with the sealing of the battery cell 200 according to the comparison result, thereby rescreening the battery cell 200 with the sealing problem, improving the detection rate of the battery cell 200 with the sealing problem, and reducing the situation where the battery cell 200 fails due to the sealing problem of the battery cell 200.

[0269] Under the second test condition, the battery cells 200 that have passed the initial test are retested under negative pressure, and the battery cells 200 that have passed the retest are screened out, wherein the second test condition includes evacuating the battery cells 200 to a second preset negative pressure, the absolute value of the second preset negative pressure is greater than the absolute value of the first preset negative pressure, and under the second preset negative pressure, the electrolyte 201 in the battery cells 200 enters the negative pressure cup 10. In the step, by setting steps S41 to S45, the battery cells 200 can be retested under the condition of a high preset negative pressure, so as to achieve further screening of the battery cells 200, thereby improving the detection rate of battery cells 200 with sealing problems, thereby reducing the failure rate of the battery cells 200.

[0270] When testing the sealing performance of the battery cell 200 , the battery cell 200 is firstly placed on the formation equipment 100 and the negative pressure cup 10 of the vacuum device of the formation equipment 100 is connected to the interior of the battery cell 200 . A first vacuuming operation is performed on the battery cell 200. When the internal pressure of the battery cell 200 reaches -45±5 kPa, the first vacuuming operation is terminated. A first pressure-maintaining operation is performed on the battery cell 200 and the pressure-maintaining process is timed. When the first pressure-maintaining time reaches 60 seconds, a first pressure value of the battery cell 200 is obtained when the first vacuuming is completed. A second pressure value of the battery cell 200 is obtained when the first pressure-maintaining time reaches a first preset time. A first difference between the first pressure value and the second pressure value is calculated, and an absolute value of the first difference is taken to obtain a first pressure difference. A first ratio of the first pressure difference to the first preset time is calculated, wherein the first ratio is an initial leak rate. The initial leak rate is compared with a first preset value, and the first preset value is 3 kPa / minute. When the initial leak rate is greater than or equal to the first preset value, the battery cell 200 is determined to be unqualified in the initial test. When the initial leak rate is less than the first preset value, the battery cell 200 is determined to be qualified in the initial test.

[0271] Under the second test condition, a second vacuuming operation is performed on the battery cell 200 that has passed the initial test. When the internal pressure of the battery cell 200 reaches -80±5 kPa, the second vacuuming operation is terminated, and a second pressure-maintaining operation is performed on the battery cell 200 and the pressure-maintaining process is timed. When the second pressure-maintaining time reaches 60 seconds, a third pressure value of the battery cell 200 at the end of the second vacuuming is obtained, and a fourth pressure value of the battery cell 200 when the second pressure-maintaining time reaches a second preset time is obtained. The second difference between the third pressure value and the fourth pressure value is calculated, and the absolute value of the second difference is taken to obtain a second pressure difference. The second ratio of the second pressure difference to the second preset time is calculated, wherein the second ratio is the retest leakage rate. The retest leakage rate is compared with the second preset value, and the second preset value is 3 kPa / minute. When the retest leakage rate is greater than or equal to the second preset value, the battery cell 200 is determined to be unqualified in the retest, and when the retest leakage rate is less than the second preset value, the battery cell 200 is determined to be qualified in the retest.

[0272] A second aspect of the present application provides a formation device 100 , which is used to implement the above-mentioned detection method of the battery cell 200 .

[0273] In the present application, before the formation equipment 100 forms the battery cell 200, it is necessary to first test the sealing of the battery cell 200. In the process of testing the sealing of the battery cell 200, the battery cell 200 is first preliminarily tested using a first preset negative pressure, and the battery cell 200 is screened for leakage without the electrolyte 201 entering the negative pressure cup 10. The battery cell 200 that passes the preliminarily test is then retested, and the battery cell 200 is screened for leakage without the electrolyte 201 entering the negative pressure cup 10. By preliminarily testing and retesting the battery cell 200, respectively, the battery cell 200 with sealing problems can be screened out, thereby reducing the leakage of the electrolyte 201 of the battery cell 200 during the test.

[0274] A third aspect of the present application proposes a battery production line 1000 , comprising the above-mentioned formation equipment 100 .

[0275] In the present application, when processing the battery cell 200, the battery cell 200 needs to be formed. Before the formation equipment 100 forms the battery cell 200, the sealing of the battery cell 200 needs to be tested. In the process of testing the sealing of the battery cell 200, the battery cell 200 is firstly tested using a first preset negative pressure, and the battery cell 200 is screened for leakage on the premise that the electrolyte 201 does not enter the negative pressure cup 10. Then, the battery cell 200 that passes the initial test is retested, and the battery cell 200 is screened for leakage on the premise that the electrolyte 201 enters the negative pressure cup 10. By performing initial and retests on the battery cell 200 respectively, the battery cell 200 with sealing problems can be screened out, thereby reducing the leakage of the electrolyte 201 of the battery cell 200 during the test.

[0276] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below.

[0277] In the implementation mode of the present application, Figures 1 to 3 As shown, the present application proposes a method for detecting a battery cell 200, and the method comprises the following steps:

[0278] The battery cell 200 is disposed on the formation equipment 100 , and the negative pressure cup 10 of the vacuum pump of the formation equipment 100 is in communication with the interior of the battery cell 200 .

[0279] Under the first test condition, the battery cell 200 is subjected to a first vacuum pumping operation. When the internal pressure of the battery cell 200 reaches a first preset negative pressure, the first vacuum pumping operation is terminated. The battery cell 200 is subjected to a first pressure holding operation and the pressure holding process is timed. When the first pressure holding time reaches a first preset time (the first preset time is in the range of 60 seconds to 180 seconds), a first pressure value of the battery cell 200 is obtained when the first vacuum pumping is completed. When the first pressure holding time reaches the first preset time, a second pressure value of the battery cell 200 is obtained when the first pressure holding time reaches the first preset time. A first difference between the first pressure value and the second pressure value is calculated, and an absolute value of the first difference is taken to obtain a first pressure difference. A first ratio of the first pressure difference to the first preset time is calculated, wherein the first ratio is an initial leak rate. The initial leak rate is compared with a first preset value (the first preset value is in the range of 2 kPa / min to 5 kPa / min). When the initial leak rate is greater than or equal to the first preset value, the battery cell 200 is determined to be unqualified in the initial test. When the initial leak rate is less than the first preset value, the battery cell 200 is determined to be qualified in the initial test.

[0280] Under the second test condition, a second vacuuming operation is performed on the battery cell 200 that has passed the initial test. When the internal pressure of the battery cell 200 reaches the second preset negative pressure, the second vacuuming operation is ended. A second pressure holding operation is performed on the battery cell 200 and the pressure holding process is timed. When the second pressure holding time reaches the second preset time (the second preset time is in the range of 60 seconds to 180 seconds), a third pressure value of the battery cell 200 at the end of the second vacuuming is obtained, and when the second pressure holding time reaches the second preset time, the third pressure value of the battery cell 200 is obtained. 00, calculate the second difference between the third pressure value and the fourth pressure value, and take the absolute value of the second difference to obtain the second pressure difference, calculate the second ratio of the second pressure difference to the second preset time length, wherein the second ratio is the re-test leakage rate, compare the re-test leakage rate and the second preset value (the second preset value is in the range of 2 kPa / min to 5 kPa / min), when the re-test leakage rate is greater than or equal to the second preset value, determine that the battery cell 200 is re-tested and unqualified, and when the re-test leakage rate is less than the second preset value, determine that the battery cell 200 is re-tested and qualified.

[0281] In the present application, during the process of testing the sealing of the battery cell 200, the battery cell 200 is first preliminarily tested using the first preset negative pressure, and the battery cell 200 is screened for leakage without the electrolyte 201 entering the negative pressure cup 10, and then the battery cell 200 that has passed the preliminarily tested is retested, and the battery cell 200 is screened for leakage without the electrolyte 201 entering the negative pressure cup 10. By preliminarily testing and retesting the battery cell 200, respectively, the battery cell 200 with sealing problems can be screened out, thereby reducing the leakage of the electrolyte 201 of the battery cell 200 during the test process.

[0282] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for detecting a battery cell, characterized in that: The detection method comprises: placing the battery cells on a formation device; Connecting the negative pressure cup of the formation equipment to the interior of the battery cell; Under the first test condition, the battery cells are subjected to a negative pressure preliminary test, and the battery cells that pass the preliminary test are screened out, wherein the first test condition includes evacuating the battery cells to a first preset negative pressure, and under the first preset negative pressure, the electrolyte in the battery cells does not enter the negative pressure cup; Under the second test condition, the battery cells that passed the initial test are retested under negative pressure, and the battery cells that passed the retest are screened out, wherein the second test condition includes evacuating the battery cells to a second preset negative pressure, the absolute value of the second preset negative pressure is greater than the absolute value of the first preset negative pressure, and under the second preset negative pressure, the electrolyte in the battery cells enters the negative pressure cup.

2. The battery cell detection method according to claim 1, characterized in that: Under the first test condition, the battery cells are subjected to a negative pressure preliminary test, and the battery cells that pass the preliminary test are screened out, wherein the first test condition includes evacuating the battery cells to a first preset negative pressure, and the electrolyte in the battery cells does not enter the negative pressure cup under the first preset negative pressure, and the steps include: Perform the first vacuuming operation on the battery cell; When the internal pressure of the battery cell reaches a first preset negative pressure, the first vacuuming operation is terminated; Perform the first pressure maintenance operation on the battery cell and time the pressure maintenance process; Calculate the initial leakage rate of the battery cell according to the first pressure holding time reaching the first preset time; The qualified battery cells of the initial test are screened according to the initial leakage rate.

3. The battery cell detection method according to claim 2, characterized in that: The steps of screening whether the initially tested battery cells are qualified according to the initial leakage rate include: comparing the initial leak rate with a first preset value; When the initial leakage rate is greater than or equal to the first preset value, the battery cell is determined to be unqualified in the initial test; When the initial leak rate is less than the first preset value, the battery cell is determined to be qualified in the initial test.

4. The battery cell detection method according to claim 3, characterized in that: In the step of comparing the initial leak rate with a first preset value, the first preset value is in the range of 2 kPa / min to 5 kPa / min.

5. The battery cell detection method according to claim 2, characterized in that: In the step of calculating the initial leakage rate of the battery cell according to the first pressure holding time reaching the first preset time, the first preset time is in the range of 60 seconds to 180 seconds.

6. The battery cell detection method according to claim 2, characterized in that: According to the first pressure holding time reaching the first preset time, the step of calculating the initial leakage rate of the battery cell includes: Obtaining a first pressure value of the battery cell when the first vacuuming is completed; Acquire a second pressure value of the battery cell when the first pressure-maintaining time reaches a first preset time; Calculating a first difference between the first pressure value and the second pressure value, and taking an absolute value of the first difference as a first pressure difference; A first ratio of the first pressure difference to the first preset time length is calculated, wherein the first ratio is an initial leak rate.

7. The battery cell detection method according to claim 1, characterized in that: Under the second test condition, the battery cells that have passed the initial test are retested under negative pressure, and the battery cells that have passed the retest are screened out, wherein the second test condition includes evacuating the battery cells to a second preset negative pressure, the absolute value of the second preset negative pressure is greater than the absolute value of the first preset negative pressure, and under the second preset negative pressure, the electrolyte in the battery cells enters the negative pressure cup: Perform a second vacuuming operation on the battery cells that have passed the initial test; When the internal pressure of the battery cell reaches a second preset negative pressure, the second vacuuming operation is terminated; Performing a second pressure-maintaining operation on the battery cell and timing the pressure-maintaining process; Calculate the retest leakage rate of the battery cell according to the second pressure holding time reaching the second preset time; The retested battery cells are screened to see whether they are qualified based on the retest leakage rate.

8. The battery cell detection method according to claim 7, characterized in that: The steps of screening whether the battery cells are qualified according to the retest leakage rate include: Compare the retested leak rate with the second preset value; When the retest leakage rate is greater than or equal to the second preset value, the battery cell is determined to be retested unqualified; When the retest leakage rate is less than the second preset value, the battery cell is determined to be qualified in the retest.

9. The battery cell detection method according to claim 8, characterized in that: In the step of comparing the retested leak rate with a second preset value, the second preset value is within a range of 2 kPa / min to 5 kPa / min.

10. The battery cell detection method according to claim 6, characterized in that: In the step of calculating the retest leakage rate of the battery cell according to the second pressure holding time reaching the second preset time, the second preset time is in the range of 60 seconds to 180 seconds.

11. The battery cell detection method according to claim 7, characterized in that: The step of calculating the retest leakage rate of the battery cell according to the second pressure holding time reaching the second preset time includes: Acquire a third pressure value of the battery cell at the end of the second vacuuming; Acquire a fourth pressure value of the battery cell when the second pressure-maintaining time reaches a second preset time; Calculating a second difference between the third pressure value and the fourth pressure value, and taking an absolute value of the second difference as a second pressure difference; A second ratio of the second pressure difference to the second preset time length is calculated, wherein the second ratio is the re-tested leak rate.

12. The battery cell detection method according to any one of claims 1 to 11, characterized in that: Under the first test condition, the battery cells are initially tested under negative pressure, and the battery cells that pass the initial test are screened out, wherein the first test condition includes evacuating the battery cells to a first preset negative pressure, and the electrolyte in the battery cells does not enter the negative pressure cup under the first preset negative pressure, and the step includes: Get the type of battery cell; According to the type of the battery cell, the test negative pressure is matched in the negative pressure database, and the test negative pressure is calibrated as the first preset negative pressure.

13. The battery cell detection method according to claim 12, characterized in that: According to the type of the battery cell, in the step of matching the test negative pressure in the negative pressure database and calibrating the test negative pressure as the first preset negative pressure, the step of establishing the negative pressure database includes: Vacuum test various types of battery cells to obtain multiple test negative pressures; A mapping relationship between the type of battery cell and the test negative pressure is established to form a negative pressure database.

14. The battery cell detection method according to claim 13, characterized in that: In the step of performing vacuum tests on various types of battery cells to obtain multiple test negative pressures, the vacuum tests include: placing the battery cells on a formation device; The battery cell is vacuumed to allow the electrolyte in the battery cell to enter the negative pressure cup of the formation equipment; According to the pressure in the battery cell reaching the calibrated negative pressure, the vacuuming operation on the battery cell is stopped, wherein the absolute value of the calibrated negative pressure is greater than the absolute value of the second preset negative pressure; Increasing the internal pressure of the battery cell to make the electrolyte in the negative pressure cup flow back into the interior of the battery cell, and detecting the current liquid level of the electrolyte in the negative pressure cup and the current pressure value of the battery cell; When the current liquid level is zero, the current pressure value is recorded as the test negative pressure.

15. A chemical formation device, characterized in that: The formation equipment is used to implement the battery cell detection method according to any one of claims 1 to 14.

16. A battery production line, characterized in that: Comprising the chemical formation equipment according to claim 15.

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