Battery formation method, battery and electric device

Abstract

The invention provides a battery formation method, a battery and a power utilization device.The method can comprise the steps that a set voltage is used for conducting constant-voltage charging on the battery to be formed to a first set duration, and an infiltrated battery is obtained; the determination mode of the set voltage comprises the following steps: determining the set voltage based on the size parameter of the battery to be formed; wherein the battery to be formed is in an environment with set pressure and set temperature; and carrying out multi-stage constant current charging on the infiltrated battery to obtain a target battery.

Description

Technical Field

[0001] The present application relates to the technical field of battery manufacturing process, and in particular to a battery formation method, a battery and an electrical device. Background Art

[0002] After the battery is manufactured, it needs to be formed through chemical reaction to form a solid electrolyte interface (SEI) film.

[0003] However, the current formation method requires a relatively long time of first soaking and then charging. Summary of the invention

[0004] The purpose of the present application is to provide a battery formation method, a battery and an electrical device, which can improve the battery formation efficiency.

[0005] In a first aspect, the present invention provides a battery formation method, comprising: using a set voltage to perform constant voltage charging on a battery to be formed for a first set time to obtain a soaked battery; wherein the battery to be formed is in a set pressure and set temperature environment; a method for determining the set voltage comprises: determining the set voltage based on the size parameters of the battery to be formed; performing multiple stages of constant current charging on the soaked battery to obtain a target battery.

[0006] In the above implementation method, since the battery to be formed is placed in a set pressure and set temperature environment during the infiltration stage, the diffusion rate of the electrolyte in the gap between the electrode and the diaphragm in the battery to be formed can be increased, and the infiltration is accelerated by constant voltage charging, so that the electrolyte infiltration effect and the film forming speed can be improved as a whole; further, multiple stages of constant current charging are used to complete the battery formation. Furthermore, the set voltage of the constant voltage charging used for accelerated infiltration can be determined based on the size parameters of the battery to be formed, so that the determined set voltage can be more suitable for the needs of the currently formed battery to be formed, and can also better protect the formation safety of the battery to be formed.

[0007] In an optional embodiment, the first set time length is determined in a manner including: determining the first set time length based on a size parameter of the battery to be formed or the set voltage.

[0008] In the above implementation, the charging time of the constant voltage charging used for accelerated infiltration can be determined based on the size parameters of the battery to be formed, so that the constant voltage charging time can be more suitable for the currently formed battery to be formed, while satisfying the infiltration requirements and reducing the infiltration time.

[0009] In an optional embodiment, the size parameter includes the thickness of the battery to be formed; the thickness of the battery to be formed is directly proportional to the set voltage.

[0010] In an optional implementation, the set voltage has a value range of 0.1V to 0.35V.

[0011] In an optional implementation, the first set duration has a value range of 0.5h to 2.2h.

[0012] In an optional embodiment, the set pressure has a value range of -40Kpa to -36Kpa.

[0013] In the above implementation, the battery to be formed is in a negative pressure environment of -40Kpa to -36Kpa, which can discharge the gas generated by the battery during the formation process, reduce the interference of the gas generated by the formation on the infiltration, and improve the efficiency of the infiltration.

[0014] In an optional embodiment, the set temperature ranges from 40°C to 50°C.

[0015] In an optional embodiment, the constant current charging of the soaked battery in multiple stages to obtain a target battery includes: using a first set current to constantly charge the soaked battery to a first voltage to obtain a first formation battery; using a second set current to constantly charge the soaked battery to a second voltage to obtain a second formation battery; using a third set current to constantly charge the soaked battery to a third voltage to obtain a target battery; wherein the first set current is less than the second set current, and the second set current is less than the third set current; the first voltage is less than the second voltage, and the second voltage is less than the third voltage.

[0016] In an optional implementation, the value range of the first setting current includes 0.03C to 0.07C; the value range of the second setting current includes 0.08C to 0.2C; the value range of the third setting current includes 0.2C to 0.4C.

[0017] In an optional embodiment, the method further comprises: after each constant current charging, leaving the battery to rest for a second set time period.

[0018] In an optional embodiment, the positive electrode active material of the battery to be formed is lithium nickel cobalt manganese oxide, the first voltage ranges from 2.9V to 3.1V, the second voltage ranges from 3.3V to 3.4V; the third voltage ranges from 3.7V to 3.9V; or the positive electrode active material of the battery to be formed is lithium iron phosphate, the first voltage ranges from 2.9V to 3.1V, the second voltage ranges from 3.2V to 3.3V; the third voltage ranges from 3.31V to 3.4V.

[0019] In the above implementation, a step-by-step approach can be adopted to gradually increase the current of the constant current charging used in the formation.

[0020] In a second aspect, the present invention provides a battery, wherein the battery is obtained by the formation method described in any one of the aforementioned embodiments.

[0021] In a third aspect, the present invention provides an electrical device comprising the battery described in the aforementioned embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic diagram of the structure of a vehicle according to some embodiments of the present application; Figure 2 A schematic diagram of the exploded structure of a battery according to some embodiments of the present application; Figure 3 A schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application; Figure 4 A flow chart of a battery formation method provided for some embodiments of the present application; Figure 5 An optional flow chart of step 420 of the battery formation method provided in some embodiments of the present application.

[0024] Icon: 1000-vehicle; 100-battery; 200-controller; 300-motor; 10-housing; 11-first part; 12-second part; 20-battery cell; 21-end cover; 22-housing; 23-cell assembly; 21a-electrode terminal; 23a-ear; XX direction; YY direction; ZZ direction. DETAILED DESCRIPTION

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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).

[0031] 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. They 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.

[0032] 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 those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0033] In the battery manufacturing process, the assembled battery needs to go through three processes of injection, formation and aging to produce a finished battery. Injection is the process of injecting electrolyte into the vacuum-dried deep dehydrated battery shell, formation is the process of charging the battery after injection, and aging is the process of leaving the formed battery at a certain temperature for a period of time.

[0034] In the formation stage, during the first charge and discharge process of the battery, when the electrode material and the electrolyte react at the solid-liquid interface, a passivation layer covering the surface of the electrode material is formed. This passivation layer is the solid electrolyte interface (SEI) membrane. The SEI membrane is a key component in the battery. It forms a thin film between the battery's electrode and the electrolyte, which prevents excessive chemical reactions inside the battery. It also prevents the dissolution of the electrode material and the decomposition of the electrolyte, thereby maintaining the stability of the battery.

[0035] Before entering the charging stage of formation, the battery needs to be left to stand for a long time to achieve the effect of infiltration. After the infiltration is completed, the battery is charged to form. However, this implementation method may take about 24 hours in the infiltration stage, which means that if a good formation effect is required, it will take a long time.

[0036] Based on the above research, the embodiments of the present application can provide a battery formation method, a battery and an electrical device, which can improve the efficiency of battery formation by using constant voltage charging to achieve rapid infiltration before formal charging and formation.

[0037] The battery cells disclosed in the embodiments of the present application can be used, but not limited to, in electrical devices such as vehicles, ships or aircraft. A power supply system comprising the battery cells and batteries disclosed in the present application can be used to form the electrical device.

[0038] The embodiment of the present application provides an electric device using a battery as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0039] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0040] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application. Vehicle 1000 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 battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0041] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0042] Please refer to Figure 2 , Figure 2Schematic diagram of the exploded structure of the battery provided for some embodiments of the present application. The battery 100 includes a box 10 and a battery cell 20, and the battery cell 20 is contained in the box 10. Among them, the box 10 is used to provide a storage space for the battery cell 20, and the box 10 can adopt a variety of structures. In some embodiments, the box 10 may include a first part 11 and a second part 12, the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space for accommodating the battery cell 20. The second part 12 can be a hollow structure with one end open, the first part 11 can be a plate-like structure, and the first part 11 covers the open side of the second part 12, so that the first part 11 and the second part 12 jointly define a storage space; the first part 11 and the second part 12 can also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the box 10 formed by the first part 11 and the second part 12 can be in a variety of shapes, such as a cylinder, a cuboid, etc.

[0043] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.

[0044] Each battery cell 20 may be a secondary battery or a primary battery, or a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0045] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the exploded structure of a battery cell 20 provided in some embodiments of the present application. Figure 3 In the example shown, a schematic diagram of the exploded structure of the battery cell 20 is presented in a three-dimensional space formed by the X direction, the Y direction, and the Z direction. The battery cell 20 refers to the smallest unit that constitutes the battery. Figure 3 The battery cell 20 includes an end cover 21, a shell 22, a battery cell assembly 23 and other functional components.

[0046] The end cap 21 refers to a component that covers the opening of the shell 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the shell 22 to match the shell 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 21 is not easily deformed when squeezed and collided, so that the battery cell 20 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals 21a can be provided on the end cap 21. The electrode terminal 21a can be used to electrically connect to the battery cell assembly 23 for outputting or inputting electrical energy of the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The material of the end cap 21 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this. In some embodiments, an insulating member may be provided inside the end cap 21, and the insulating member may be used to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be plastic, rubber, or the like.

[0047] The shell 22 is a component used to cooperate with the end cover 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the battery cell assembly 23, electrolyte and other components. The shell 22 and the end cover 21 can be independent components, and an opening can be set on the shell 22, and the internal environment of the battery cell 20 is formed by covering the opening with the end cover 21 at the opening. Without limitation, the end cover 21 and the shell 22 can also be integrated. Specifically, the end cover 21 and the shell 22 can form a common connection surface before other components are put into the shell, and when the interior of the shell 22 needs to be encapsulated, the end cover 21 covers the shell 22. The shell 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 22 can be determined according to the specific shape and size of the battery cell assembly 23. The material of the shell 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0048] The battery cell assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more battery cell assemblies 23 may be contained in the housing 22. The battery cell assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the battery cell assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab 23a. The positive tab and the negative tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive active material and the negative active material react with the electrolyte, and the tab 23a connects the electrode terminals to form a current loop.

[0049] See also Figure 4 , is a flow chart of the battery formation method provided in the embodiment of the present application. Figure 4 The specific process shown is described in detail.

[0050] Step 410 , using a set voltage to perform constant voltage charging on the battery to be formed for a first set time to obtain a soaked battery.

[0051] The battery to be formed is in a set pressure and set temperature environment.

[0052] Constant voltage charging can mean that the voltage remains constant during the charging process.

[0053] The set voltage can also be adaptively adjusted based on actual needs. Optionally, the set voltage can also be determined based on the type of battery to be formed. For example, since batteries with higher energy density have higher charging efficiency, more electrical energy can be charged in a shorter time. For batteries with higher energy density, the set voltage can be smaller; for batteries with lower energy density, the set voltage can be larger. For example, the energy density of a ternary lithium battery is greater than that of a lithium iron phosphate battery. When the battery to be formed is a ternary lithium battery, the set voltage selected can be smaller than the set voltage selected when the battery to be formed is a lithium iron phosphate battery.

[0054] The first set duration can be adaptively adjusted based on actual needs.

[0055] Optionally, the wetting state of the battery to be formed may be observed in real time, and the first set time length may be adjusted based on the wetting state.

[0056] Optionally, the first set time length can also be determined based on the type of the battery to be formed. For example, since batteries with higher energy density have higher charging efficiency, more electrical energy can be charged in a shorter time. For batteries with higher energy density, the first set time length can be shorter; for batteries with lower energy density, the first set time length can be longer. For example, the first set time length selected when the battery to be formed is a ternary lithium battery can be shorter than the first set time length selected when the battery to be formed is a lithium iron phosphate battery.

[0057] In order to improve the wetting effect of the battery to be formed and increase the diffusion of the electrolyte in the gap between the electrode and the diaphragm, thereby facilitating the electrolyte to fully infiltrate the positive electrode, the battery to be formed can be placed vertically to reduce the gravity effect of the electrolyte.

[0058] Step 420 , performing multiple stages of constant current charging on the soaked battery to obtain a target battery.

[0059] The values ​​of the charging current used in the multiple stages of constant current charging may be different.

[0060] Constant current charging means that the current remains constant during the charging process.

[0061] Among them, the value of the charging current can be different according to the charging progress of the battery to be formed. As the charging proceeds, the current used in the next constant current charging is greater than the charging current used in the previous constant current charging. For example, step 420 involves three stages of constant current charging, and the current used in the three constant current charging gradually increases. Constant current charging is performed by gradually increasing the current, first using a small current for constant current charging to form a dense, stable and uniform SEI film, and then using a larger current and constant current charging to realize the SEI film repair process, which helps to improve the density of the SEI film and is beneficial to improving the quality of the SEI film.

[0062] In the above-mentioned embodiment of the present application, since before the constant current charging formation is formally used, the formation pretreatment will be carried out, so that the battery to be formed can be placed in a better infiltration state, and the constant current charging formation stage can be entered in a better infiltration state, and the effect of constant current charging formation can also be improved. In addition, in the infiltration stage, it can be placed in a negative pressure and set temperature environment, in a negative pressure environment, and the negative pressure environment is conducive to removing the gas generated by the battery to be formed during the infiltration process, accelerating the electrolyte penetration, and improving the infiltration speed, and in a constant temperature state, the electrolyte diffusion of the battery to be formed can be accelerated, and the infiltration speed of the battery to be formed can also be further improved.

[0063] In an optional embodiment, the method for determining the set voltage used in the infiltration stage may include: determining the set voltage based on the size parameters of the battery to be formed.

[0064] In this embodiment, the set voltage used by the thicker battery to be formed is not less than the set voltage used by the thinner battery to be formed. For example, the size parameter includes the thickness of the battery to be formed; the thickness of the battery to be formed is proportional to the set voltage.

[0065] Exemplarily, the battery to be formed may be in a flat body, a rectangular parallelepiped, or the like, and the size parameter may include the thickness of the battery to be formed. For example, the thicker the thickness of the battery to be formed, the larger the value of the set voltage may be; the smaller the thickness of the battery to be formed, the smaller the value of the set voltage may be.

[0066] Exemplarily, the battery to be formed may be a cylinder, and the size parameter may include the diameter of the battery to be formed. For example, the larger the diameter of the battery to be formed, the larger the value of the set voltage may be; the smaller the diameter of the battery to be formed, the smaller the value of the set voltage may be.

[0067] Optionally, the value range of the set voltage includes 0.1 V to 0.35 V. Exemplarily, the value of the set voltage can be any value of 0.08 V, 0.1 V, 0.15 V, 0.2 V, 0.22 V, 0.23 V, 0.23 V, 0.25 V, 0.28 V, 0.3 V, 0.31 V, 0.33 V, 0.35 V or between any two values, wherein the set voltage can be actually selected according to the specific battery thickness.

[0068] Increasing the electric field at both ends of the cathode and cathode accelerates the diffusion of the electrolyte in the battery cell. The greater the thickness of the battery to be formed, the greater the distance between the cathode and cathode. When the thickness of the battery to be formed is greater, a relatively larger set voltage can be selected to achieve infiltration by constant voltage charging, and infiltration can be achieved more quickly. In the above implementation, if a voltage of 0.1V is used as the voltage for constant voltage charging, a longer constant voltage charging is used to achieve a more adequate infiltration effect; if a voltage of 0.35V is used as the voltage for constant voltage charging, a shorter constant voltage charging is used to achieve a more adequate infiltration effect. Using a higher voltage can achieve a faster decomposition of the electrolyte, and charging with a lower voltage can achieve a more stable and slow decomposition of the electrolyte. Therefore, different voltages can be selected for constant voltage charging based on actual efficiency requirements. In this embodiment, the set voltage is a smaller value, less than or equal to 0.35V, which can achieve accelerated infiltration without forming an SEI film in advance.

[0069] In some examples, the set voltages selected for different battery thicknesses may be as shown in Table 1 below.

[0070] Table 1

[0071] In the example shown in Table 1 above, when the battery thickness is less than or equal to 20mm, the set voltage value selected can be the same value, 0.1V is selected. When the battery thickness is greater than or equal to 60mm, the set voltage value selected can be the same value, 0.33V is selected. Constant voltage charging at the above voltages can improve the wetting efficiency of the battery to be formed without forming an SEI film. In the example shown in Table 1 above, the set voltage does not increase uniformly with the increase of the battery thickness. The set voltage used for some cells of different thicknesses can also be the same.

[0072] In an optional embodiment, the method for determining the first set time length used in the infiltration stage includes: determining the first set time length based on the size parameters or the set voltage of the battery to be formed.

[0073] Exemplarily, the battery to be formed can be in the shape of a flat body, a cuboid, etc., and the size parameter can include the thickness of the battery to be formed. For example, the thicker the thickness of the battery to be formed, the larger the value of the first setting duration can be; the smaller the thickness of the battery to be formed, the smaller the value of the first setting duration can be. Since the infiltration speed of the battery is faster than the infiltration speed of the battery after the thickness is smaller, the smaller the thickness of the battery to be formed, the smaller the value of the first setting duration can be, thereby saving the infiltration time and improving the infiltration efficiency. For batteries with thicker thickness, a relatively longer first setting duration can be selected to achieve more complete infiltration.

[0074] Exemplarily, the battery to be formed may be a cylinder, and the size parameter may include the diameter of the battery to be formed. For example, the larger the diameter of the battery to be formed, the larger the value of the first set time length may be; the smaller the diameter of the battery to be formed, the smaller the value of the first set time length may be.

[0075] Optionally, the value range of the first set time length includes 0.5h to 2.2h. Exemplarily, the value of the first set time length can be any value of 0.5h, 0.7h, 0.8h, 1h, 1.2h, 1.3h, 1.5h, 1.8h, 2h, 2.2h or between any two values, wherein the first set time length can be actually selected according to the specific battery thickness.

[0076] In the above implementation, if 0.5h is selected, the immersion time can be shorter, which can improve the immersion efficiency; if 2.2h is selected, a shorter time than the static immersion time can achieve a more adequate immersion effect. In actual implementation, constant voltage charging can also be performed with appropriate voltage to achieve adequate immersion.

[0077] In this embodiment, the first set time length used by the thicker formation battery is not less than the first set time length used by the thinner formation battery.

[0078] In some examples, the first set time length selected for different battery thicknesses may be as shown in Table 2 below.

[0079] Table 2

[0080] In the example shown in Table 1 above, when the battery thickness is less than or equal to 20mm, the first set time value selected can be the same value, and 0.7h is selected. When the battery thickness is greater than or equal to 60mm, the first set time value selected can be the same value, and 2h is selected. In the example shown in Table 2 above, the first set time may not increase uniformly with the increase of battery thickness. The first set time used for some batteries of different thicknesses may be the same. Of course, during actual infiltration, an appropriate constant voltage and constant voltage charging duration can be selected based on the thickness of the battery to be formed, so as to achieve better infiltration of the battery to be formed in less time.

[0081] In the above implementation, the constant voltage charging voltage is adaptively adjusted based on the thickness of the battery to be formed, thereby achieving constant voltage charging power. After the charging power is increased, the electric field strength is increased to increase the wetting effect and improve the wetting efficiency of the battery to be formed.

[0082] In some optional embodiments, the set pressure selected in the infiltration stage has a value range of -40Kpa to -36Kpa. For example, the set pressure can be any value of -40Kpa, -38Kpa, -37Kpa, -36Kpa or between any two values, wherein the set pressure can be actually selected according to the amount of gas generated by the specific battery infiltration. In the negative pressure environment under the above pressure values ​​actually selected, the gas generated in the infiltration stage can be discharged more effectively and quickly.

[0083] In some optional embodiments, the range of the set temperature selected in the infiltration stage includes 40°C to 50°C. Exemplarily, the set temperature can be any value of 40°C, 41°C, 43°C, 45°C, 47°C, 48°C, 50°C or between any two values, wherein the set temperature can be actually selected according to the specific battery infiltration environment requirements. For example, if the temperature of the battery to be formed in the environment is required to reach 45°C, the ambient temperature can be adaptively adjusted so that the temperature of the battery to be formed at this temperature can reach 45°C.

[0084] For example, the temperature in the immersion environment can be raised to 45° C. so as to improve the electrolyte infiltration effect and the film formation speed.

[0085] In order to further improve the formation effect and efficiency of the battery to be formed, three different constant currents can be used in the constant current charging stage to achieve three stages of constant current charging. Figure 5 As shown, the above step 420 may include steps 421 to 425 .

[0086] Step 421, use a first set current to perform constant current charging on the soaked battery to a first voltage to obtain a first formed battery.

[0087] Constant current charging means that the current remains constant during the charging process.

[0088] Step 423, use a second set current to perform constant current charging on the soaked battery to a second voltage to obtain a second formed battery.

[0089] Step 425 , use a third set current to perform constant current charging on the soaked battery to a third voltage to obtain a target battery.

[0090] The first set current is smaller than the second set current, and the second set current is smaller than the third set current; the first voltage is smaller than the second voltage, and the second voltage is smaller than the third voltage.

[0091] Optionally, the value range of the first set current includes 0.03C to 0.07C. Exemplarily, the value of the first set current can be any value of 0.03C, 0.05C, 0.06C, 0.07C or between any two values, wherein the first set current can be actually selected according to the specific battery thickness or battery type.

[0092] Among them, since the electrode material is in an unactivated state and the internal structure is unstable during the initial charging of the battery, the value of the first set current used in the constant current charging in the first stage is within a small range, which can slowly form the SEI film and improve the safety of the battery to be formed. If a smaller current of 0.03C is selected, the SEI film can be formed more evenly, slowly and stably, and if a larger current of 0.07C is selected, the SEI film can be formed relatively quickly, but this value is a smaller value compared to the rated capacity of the battery, so the charging safety of the battery to be formed can also be better maintained.

[0093] Optionally, the value range of the second set current includes 0.08C to 0.2C. Exemplarily, the value of the second set current can be any value of 0.08C, 0.09C, 0.1C, 0.13C, 0.15C, 0.2C or between any two values, wherein the second set current can be actually selected according to the specific battery thickness or battery type.

[0094] As charging progresses, the active materials inside the battery to be formed are gradually fully utilized, and the polarization phenomenon on the electrode surface will also change. At this time, appropriately increasing the current can speed up the charging speed and improve the charging efficiency. At the same time, it can also make the chemical reaction inside the battery more sufficient and uniform, so that the SEI film can be formed more quickly and stably. In the second stage of constant current charging, when a constant current of 0.08C is selected, the safety and stability of the battery to be formed can be improved; if a constant current of 0.2C is selected, a larger charging current can be selected within the safety range to make the formation efficiency of the SEI film higher. In actual formation, this stage also adaptively selects a value between 0.08C and 0.2C as the constant current charging current based on the constant current charging situation in the first stage.

[0095] Optionally, the value range of the third set current includes 0.2C to 0.4C. Exemplarily, the value of the third set current can be any value of 0.2C, 0.22C, 0.25C, 0.29C, 0.3C, 0.33C, 0.4C or between any two values, wherein the third set current can be actually selected according to the specific battery thickness or battery type.

[0096] In the above implementation, the charging current of the constant current charging in multiple stages gradually increases, which can effectively control the charging speed of the battery and avoid overcharging or undercharging. It can also better enable the battery to obtain stable current input at the initial stage of charging, which is conducive to the uniformity of the chemical reaction inside the battery, improves the consistency of the battery, and can also make the formed SEI film more uniform and dense.

[0097] Optionally, after each constant current charging, the battery is left to stand for a second set time. It can be understood that after step 421, the battery to be formed can be left to stand for the second set time; after step 423, the battery to be formed can be left to stand for the second set time; after step 425, the battery to be formed can be left to stand for the second set time.

[0098] The second set time length can be any value of 5 minutes, 7 minutes, 9 minutes, 10 minutes, 12 minutes, 15 minutes, or between any two values.

[0099] By allowing the constant current charging between the two stages to be buffered by a standing buffer step after each constant current charging, there is a conversion process between the constant current charging steps of the two stages, which is conducive to eliminating polarization. In the above implementation, it can be allowed to stand for 5 to 15 minutes, and a shorter time can be used to better achieve the formation of the SEI film. A shorter time of 5 minutes can achieve a more efficient formation, and a relatively longer time of 15 minutes can better eliminate polarization and improve the density and uniformity of the SEI film.

[0100] Batteries of different systems have different energy densities and charging efficiencies, and the selection of parameters required for the formation of different battery systems may also be different.

[0101] In some embodiments, the positive electrode active material of the battery to be formed is lithium nickel cobalt manganese oxide, the first voltage ranges from 2.9V to 3.1V, the second voltage ranges from 3.3V to 3.4V; and the third voltage ranges from 3.7V to 3.9V.

[0102] Exemplarily, the value of the first voltage may be any one of 2.9V, 2.95V, 3V, and 3.1V, or between any two values, wherein the first voltage may be actually selected according to a specific battery formation progress.

[0103] Exemplarily, the value of the second voltage may be any one of 3.3V, 3.35V, and 3.4V, or between any two values, wherein the second voltage may be actually selected according to the specific progress of battery formation.

[0104] Exemplarily, the value of the third voltage may be any value among 3.7V, 3.75V, 3.8V, 3.85V, and 3.9V, or between any two values, wherein the third voltage may be actually selected according to the specific progress of battery formation.

[0105] Among the above values, a value with a smaller cutoff voltage can be selected on the basis of being able to form an SEI film, so as to achieve faster formation of the SEI film.

[0106] In some embodiments, the positive electrode active material of the battery to be formed is lithium iron phosphate, the first voltage ranges from 2.9V to 3.1V, the second voltage ranges from 3.2V to 3.3V, and the third voltage ranges from 3.31V to 3.4V.

[0107] Exemplarily, the value of the first voltage may be any one of 2.9V, 2.95V, 3V, and 3.1V, or between any two values, wherein the first voltage may be actually selected according to the specific progress of battery formation.

[0108] Exemplarily, the value of the second voltage may be any one of 3.2V, 3.25V, and 3.3V, or between any two values, wherein the second voltage may be actually selected according to the specific progress of battery formation.

[0109] Exemplarily, the value of the third voltage may be any one of 3.31V, 3.35V, 3.38V, and 3.4V, or between any two values, wherein the third voltage may be actually selected according to the specific progress of battery formation.

[0110] In the above implementation, through multiple stages of constant current charging, the formation of the SEI film can be achieved by charging in stages at a relatively stable speed, so that the formed SEI film can be denser and more uniform, reducing the loss of irreversible capacity, improving the state of charge (SOC) of the battery, and ensuring the stable performance of the battery cell at a higher voltage.

[0111] The following is a description of the entire process of battery formation with some examples: For example, the positive electrode active material of the battery to be formed is lithium nickel cobalt manganese oxide, and the thickness of the battery to be formed is in the range of 25-30mm: Formation pretreatment process: Place the formed battery vertically, adjust the pressure of the formation furnace to -37.5Kpa, and discharge the gas generated during the formation process by adjusting the negative pressure. Adjust the battery cell temperature to 45°C to improve the electrolyte infiltration effect and film formation speed. Then, perform constant voltage charging at a constant voltage of 0.22V for 1h to accelerate the electrolyte infiltration.

[0112] Formal formation process: In the first stage, constant current charging is performed at a constant current of 0.05C to a voltage of 3V to initially form the SEI film on the surface of the negative electrode, and then it is allowed to stand for 10 minutes; in the second stage, constant current charging is performed at a constant current of 0.1C to a voltage of 3.4V to continue to form and stabilize the SEI film, while increasing the SOC of the battery cell, and then it is allowed to stand for 10 minutes; in the third stage, constant current charging is performed at a constant current of 0.33C to a voltage of 3.85V to further increase the SOC of the battery cell, and then it is allowed to stand for 10 minutes.

[0113] The energy density of the battery to be formed whose positive electrode active material is lithium nickel cobalt manganese oxide is higher, and the cut-off voltage during formation is also relatively higher.

[0114] Take the case where the cathode active material of the battery to be formed is lithium iron phosphate and the thickness of the battery to be formed is in the range of 25-30mm as an example: Formation pretreatment process: Place the formed battery vertically, adjust the pressure of the formation furnace to -37.5Kpa, and discharge the gas generated during the formation process by adjusting the negative pressure. Adjust the battery cell temperature to 45°C to improve the electrolyte infiltration effect and film formation speed. Then, perform constant voltage charging at a constant voltage of 0.22V for 1h to accelerate the electrolyte infiltration.

[0115] Formal formation process: In the first stage, constant current charging is performed at a constant current of 0.05C to a voltage of 3V to initially form the SEI film on the surface of the negative electrode, and then it is allowed to stand for 10 minutes; in the second stage, constant current charging is performed at a constant current of 0.1C to a voltage of 3.25V to continue to form and stabilize the SEI film, while increasing the SOC of the battery cell, and then it is allowed to stand for 10 minutes; in the third stage, constant current charging is performed at a constant current of 0.33C to a voltage of 3.35V to further increase the SOC of the battery cell, and then it is allowed to stand for 10 minutes.

[0116] The above are just two examples of process flow diagrams. In actual formation, the thickness of the battery to be formed may be different, and there are also different set voltage values ​​used in step 410 to achieve wetting by constant voltage charging. Table 3 below shows a comparison of the wetting conditions of some embodiments and comparative examples under different conditions. Among them, each embodiment uses different set voltages for constant voltage charging under different battery thicknesses, and the selection of the duration of constant voltage charging corresponding to different set voltages may also be different. Each comparative example is a case where wetting is achieved without using constant voltage charging.

[0117] Table 3

[0118] It can be seen from Table 3 above that the time required for the infiltration achieved in each embodiment is much shorter than the time required for the infiltration of the comparative example.

[0119] In various embodiments, if the batteries have different thicknesses, and if the same charging time is used to perform constant voltage charging on the batteries, a thicker battery will require a greater constant voltage value.

[0120] Under the condition of the same battery thickness, to achieve the same degree of complete infiltration, the comparative example 2 takes 14 hours, while the examples 1 and 6 can achieve complete infiltration after one hour and two hours. When the battery thickness of the example 3 is thicker than that of the comparative example 2, the example 3 uses a constant voltage of 0.33V for constant voltage charging, and it only takes one hour to achieve complete infiltration, while the comparative example 2 needs to stand for 14 hours to achieve complete infiltration.

[0121] By comparing the above embodiment with the comparative example, it can be understood that the constant voltage charging method of the embodiment of the present application can shorten the time required for time immersion, thereby achieving the effect of improving the battery formation efficiency.

[0122] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0123] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A battery formation method, characterized in that: include: Using a set voltage to perform constant voltage charging on the battery to be formed for a first set time to obtain a soaked battery; wherein the battery to be formed is in a set pressure and set temperature environment; the method for determining the set voltage includes: determining the set voltage based on the size parameters of the battery to be formed; The soaked battery is subjected to multiple stages of constant current charging to obtain a target battery.

2. The method according to claim 1, characterized in that The method for determining the first set duration includes: A first set time period is determined based on the size parameters of the battery to be formed or the set voltage.

3. The method according to claim 1, characterized in that The size parameter includes the thickness of the battery to be formed; the thickness of the battery to be formed is proportional to the set voltage.

4. The method according to claim 1, characterized in that: The set voltage has a value range of 0.1V to 0.35V.

5. The method according to claim 1, characterized in that The value range of the first set time length includes 0.5h to 2.2h.

6. The method according to claim 1, characterized in that The set pressure has a value range of -40Kpa to -36Kpa.

7. The method according to claim 1, characterized in that The set temperature ranges from 40°C to 50°C.

8. The method according to any one of claims 1 to 7, characterized in that: The step of performing multiple stages of constant current charging on the soaked battery to obtain a target battery comprises: Using a first set current to perform constant current charging on the soaked battery to a first voltage, to obtain a first formation battery; Using a second set current to perform constant current charging on the soaked battery to a second voltage, to obtain a second formation battery; The target battery is obtained by performing constant current charging on the soaked battery to a third voltage using a third set current; wherein the first set current is less than the second set current, and the second set current is less than the third set current; and the first voltage is less than the second voltage, and the second voltage is less than the third voltage.

9. The method according to claim 8, characterized in that The value range of the first setting current includes 0.03C to 0.07C; the value range of the second setting current includes 0.08C to 0.2C; the value range of the third setting current includes 0.2C to 0.4C.

10. The method according to claim 8, characterized in that The method further comprises: After each constant current charging, the battery is left to stand for a second set time.

11. The method according to claim 8, characterized in that The positive electrode active material of the battery to be formed is lithium nickel cobalt manganese oxide, the first voltage ranges from 2.9V to 3.1V, the second voltage ranges from 3.3V to 3.4V; the third voltage ranges from 3.7V to 3.9V; or The positive electrode active material of the battery to be formed is lithium iron phosphate, the first voltage ranges from 2.9V to 3.1V, the second voltage ranges from 3.2V to 3.3V; and the third voltage ranges from 3.31V to 3.4V.

12. A battery, characterized in that: The battery is obtained by the formation method according to any one of claims 1 to 11.

13. An electrical device, characterized in that: A battery comprising the battery of claim 12.

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