Battery formation method and device

Abstract

The invention discloses a battery formation method and device, and relates to the technical field of batteries. The battery formation method comprises the steps that the reduction voltage lower limit and the reduction voltage upper limit of the two sides of a film forming peak of reactants in electrolyte are determined, and the reactants comprise at least two reaction components; and performing multiple charging and discharging operations within the range of the lower limit of the reduction voltage and the upper limit of the reduction voltage. Through the method, the quality of the SEI membrane can be improved, and the service life of the battery can be prolonged.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically to a battery formation method and apparatus. Background Technology

[0002] The negative electrode active material of lithium-ion batteries is often graphite. During the initial formation, graphite undergoes an irreversible side reaction with the electrolyte and forms an SEI (Solid Electrolyte Interface) layer.

[0003] In lithium-ion batteries, the SEI film plays a crucial role in protecting the electrodes, mitigating electrolyte decomposition, providing lithium-ion transport channels, and preventing lithium dendrite formation. The composition and structure of the SEI film control the charge transfer and ion transport processes in the battery, directly affecting its cycle life, stability, and other performance characteristics.

[0004] A high-quality SEI layer can effectively reduce irreversible lithium loss at the negative electrode during long-term battery cycle storage, thereby improving battery life. Summary of the Invention

[0005] In view of the above problems, this application provides a battery formation method and apparatus that can improve the film quality of the SEI layer.

[0006] In a first aspect, this application provides a battery formation method, comprising: determining a lower limit of reduction voltage and an upper limit of reduction voltage on both sides of the film formation peak of a reactant in an electrolyte, wherein the reactant includes at least two reactive components; and performing multiple charge and discharge operations within the range of the lower limit of reduction voltage and the upper limit of reduction voltage.

[0007] In the technical solution of this application embodiment, during the battery formation process, multiple charge and discharge operations are performed within the range of the lower and upper limits of the reduction voltage on both sides of the film-forming peak of the reactants. Different reactive components in the electrolyte have different film-forming abilities. The SEI film generated based on the reactive component with stronger film-forming ability has better quality. Therefore, by performing multiple charge and discharge operations within the range of the lower and upper limits of the reduction voltage, the reactive component with stronger film-forming ability occupies a larger proportion in the reaction, thereby increasing the proportion of the SEI film generated based on that component, improving the quality of the SEI film, effectively reducing the irreversible lithium consumption of the negative electrode during long-term battery cycle storage, and improving the battery's lifespan.

[0008] In some embodiments, performing multiple charge and discharge operations within the range of the lower limit and the upper limit of the restoration voltage includes: acquiring the current battery voltage; determining a target formation mode based on the current voltage, the target formation mode including a constant voltage charging mode, a constant current charging mode, and a constant voltage discharging mode; and executing the target formation mode.

[0009] In the technical solution of this application embodiment, the current state of the battery is understood by voltage detection during multiple charging and discharging operations, and then a matching formation mode is adopted to improve the matching degree between the formation mode and the battery state, which is beneficial to improve the formation efficiency and further improve the film formation quality of the SEI film.

[0010] In some embodiments, each charge-discharge operation includes: charging the battery to the lower limit of the reduction voltage of the reactant using a constant voltage; charging the battery to the upper limit of the reduction voltage of the reactant using a constant current; and discharging the battery to the lower limit of the reduction voltage of the reactant using a constant voltage.

[0011] In the technical solution of this application embodiment, constant voltage charging and discharging can reduce the gap between the reached voltage and the lower limit of the reduction voltage, and reduce the voltage change after resting; constant current charging can shorten the reaction time and improve the charging efficiency, which in turn helps to improve the formation efficiency of the battery.

[0012] In some embodiments, determining the target formation mode based on the current voltage includes: when the current voltage is determined to be the lower limit of the reduction voltage during constant current charging, the target formation mode is determined to be a constant voltage charging mode; when the current voltage is determined to be the lower limit of the reduction voltage during constant voltage charging, the target formation mode is determined to be a constant current charging mode; when the current voltage is determined to be the upper limit of the reduction voltage during constant current charging, the target formation mode is determined to be a constant voltage discharging mode; when the current voltage is determined to be the lower limit of the reduction voltage during constant voltage discharging, and the condition for stopping multiple charging and discharging has not been met, the target formation mode is determined to be a constant voltage charging mode.

[0013] In the technical solution of this application embodiment, by monitoring the current voltage in real time, the current voltage state of the battery can be determined in a timely manner, and then the corresponding charging and discharging mode can be switched. By switching to constant voltage charging and discharging mode in a timely manner, overcharging using constant current charging mode can be avoided, and the accuracy of reaching the lower limit of the reduction voltage can be improved. By switching to constant current charging mode in a timely manner, the reaction time can be shortened and the charging efficiency can be improved. Since the matching degree between the battery formation mode and the battery state is improved, it is beneficial to further improve the film formation quality of SEI film.

[0014] In some embodiments, performing multiple charge and discharge operations within the range of the lower limit and the upper limit of the restoration voltage further includes: stopping the charge and discharge within the range of the lower limit and the upper limit of the restoration voltage when the number of charge and discharge operations reaches the target number.

[0015] In the technical solution of this application embodiment, a cutoff condition is set for multiple charge and discharge operations within the range of the lower limit and upper limit of the reduction voltage to avoid falling into an infinite loop and affecting the formation progress.

[0016] In some embodiments, the battery formation method further includes: charging the battery by constant current charging; and performing multiple charge and discharge operations within the range of the lower and upper limits of the reduction voltage when the current voltage of the battery reaches the lower limit of the reduction voltage.

[0017] In the technical solution of this application embodiment, the battery is first charged to the lower limit of the reduction voltage using a constant current, which shortens the time for the battery to rise from a lower voltage to the lower limit of the reduction voltage and improves the efficiency of battery formation.

[0018] In some embodiments, the number of film-forming peaks of the reactants is greater than 1. According to the order of the voltage of the film-forming peaks from low to high, for multiple film-forming peaks, the operation of determining the lower limit of reduction voltage and the upper limit of reduction voltage and charging and discharging multiple times within the range of the lower limit of reduction voltage and the upper limit of reduction voltage is performed respectively.

[0019] In the technical solution of this application embodiment, repeated charge and discharge operations are performed on multiple film formation peaks within the range of the lower limit and upper limit of the reduction voltage, so that sufficient reduction can be carried out at each corresponding reduction potential, which further improves the film formation quality of the SEI film and is conducive to further improving the service life of the battery.

[0020] In some embodiments, the battery formation method further includes: performing operations to determine a lower limit and an upper limit of reduction voltage for a film formation peak and performing multiple charge and discharge operations within the range of the lower limit and the upper limit of reduction voltage; if the current film formation peak is not the film formation peak with the highest voltage value of the reactant, then charging the battery by constant current charging, and when the current voltage of the battery reaches the lower limit of the reduction voltage of the next film formation peak, performing operations to determine a lower limit and an upper limit of reduction voltage for the next film formation peak and performing multiple charge and discharge operations within the range of the lower limit and the upper limit of reduction voltage.

[0021] In the technical solution of this application embodiment, after performing multiple charge and discharge operations within the range of the lower and upper limits of the reduction voltage for a film formation peak, the battery is quickly charged to the lower limit of the reduction voltage of the next film formation peak by a constant current, which shortens the time to enter the upper and lower limits of the reduction voltage of the next film formation peak and improves the battery formation efficiency.

[0022] In some embodiments, the reaction components include at least one of LiFSI (lithium bisfluorosulfonylimide) / LiTFSI (lithium bistrifluoromethanesulfonylimide), LiBF4 (lithium tetrafluoroborate), LiClO4 (lithium perchlorate), LiAsF6 (lithium hexafluoroarsenate), LiCF3SO3 (lithium trifluoromethanesulfonate), LiFePO4 (lithium iron phosphate), and LiCoO2 (lithium cobalt oxide).

[0023] In the technical solution of this application embodiment, different reactive components have different film-forming abilities. By repeatedly charging and discharging within the range of the lower limit and upper limit of the reduction voltage, the SEI film generated by the reactive component with stronger film-forming ability occupies a larger portion, thereby improving the proportion of inorganic components in the SEI and improving the quality of the SEI film.

[0024] In some embodiments, performing multiple charge and discharge operations within the range of the lower and upper reduction voltage limits includes: charging the battery to the lower reduction voltage limit of the reactant using a constant voltage; charging the battery to the upper reduction voltage limit of the first reactant using a constant current; and discharging the battery to the lower reduction voltage limit of the first reactant using a constant voltage, wherein the range between the lower and upper reduction voltage limits of the first reactant is smaller than the range between the lower and upper reduction voltage limits of the reactant.

[0025] In the technical solution of this application embodiment, the voltage range of multiple charge and discharge operations is controlled more within the upper and lower limits of the reduction voltage of the first reaction component, which is more conducive to the participation of the first reaction component in film formation, further increasing the specific gravity of the SEI film obtained based on the first reaction component. Since the performance of the SEI film generated based on the first reaction component is higher than that of the solid electrolyte interface SEI film generated based on the second reaction component in the reactants, the quality of the SEI film can be improved.

[0026] In some embodiments, the battery formation method meets at least one of the following: the lower limit of the reduction voltage is the voltage at which the slope of the voltage differential capacity increases becomes greater than or equal to a predetermined slope threshold on the side where the voltage is less than the voltage corresponding to the film formation peak; or, the upper limit of the reduction voltage is the valley voltage of the voltage differential capacity on the side where the voltage is greater than the voltage corresponding to the film formation peak.

[0027] In the technical solution of this application embodiment, the voltage at which the slope of the voltage differential capacity rises becomes greater than or equal to a predetermined slope threshold when the voltage is less than the voltage corresponding to the film formation peak is used as the lower limit of the reduction voltage, and the voltage at the valley value of the voltage differential capacity when the voltage is greater than the voltage corresponding to the film formation peak is used as the upper limit of the reduction voltage. By charging and discharging multiple times within the range of the upper and lower limits of the reduction voltage, the voltage range with high efficiency of the reduction reaction is fully utilized, thereby improving the reaction efficiency.

[0028] Secondly, this application provides a battery formation apparatus, including an oscillating charge-discharge module, configured to: determine the lower limit of reduction voltage and the upper limit of reduction voltage on both sides of the film formation peak of the reactants in the electrolyte, wherein the reactants include at least two reactive components; and perform multiple charge and discharge operations within the range of the lower limit of reduction voltage and the upper limit of reduction voltage.

[0029] In the technical solution of this application embodiment, during the battery formation process, multiple charge and discharge operations are performed within the range of the lower and upper limits of the reduction voltage on both sides of the film-forming peak of the reactants. Different reactive components in the electrolyte have different film-forming abilities. The SEI film generated based on the reactive component with stronger film-forming ability has better quality. Therefore, by performing multiple charge and discharge operations within the range of the lower and upper limits of the reduction voltage, the reactive component with stronger film-forming ability occupies a larger proportion in the reaction, thereby increasing the proportion of the SEI film generated based on that component, improving the quality of the SEI film, effectively reducing the irreversible lithium consumption of the negative electrode during long-term battery cycle storage, and improving the battery's lifespan.

[0030] In some embodiments, the battery formation apparatus further includes a constant current charging module configured to: charge the battery by constant current charging; and activate an oscillating charge-discharge module when the current voltage of the battery reaches the lower limit of the reduction voltage.

[0031] In the technical solution of this application embodiment, the battery is first charged to the lower limit of the reduction voltage using a constant current, which shortens the time for the battery to rise from a lower voltage to the lower limit of the reduction voltage and improves the efficiency of battery formation.

[0032] In some embodiments, the battery formation apparatus includes multiple oscillating charge-discharge modules. Each oscillating charge-discharge module performs multiple charge-discharge operations within the range of the lower and upper limits of the reduction voltage for a film formation peak, wherein the number of film formation peaks of the reactants is greater than 1.

[0033] In the technical solution of this application embodiment, repeated charge and discharge operations are performed on multiple film formation peaks within the range of the lower limit and upper limit of the reduction voltage, so that sufficient reduction can be carried out at each corresponding reduction potential, which further improves the film formation quality of the SEI film and is conducive to further improving the service life of the battery.

[0034] In some embodiments, a constant current charging module is included between every two oscillating charge-discharge modules. The constant current charging module is configured to charge the battery by constant current charging after the previous oscillating charge-discharge module has completed its charge-discharge cycle, and to activate the next oscillating charge-discharge module when the current voltage of the battery reaches the lower limit of the reduction voltage of the next film formation peak.

[0035] In the technical solution of this application embodiment, after performing multiple charge and discharge operations within the range of the lower and upper limits of the reduction voltage for a film formation peak, the battery is quickly charged to the lower limit of the reduction voltage of the next film formation peak by a constant current, which shortens the time to enter the upper and lower limits of the reduction voltage of the next film formation peak and improves the battery formation efficiency.

[0036] In some embodiments, the battery formation apparatus meets at least one of the following: the lower limit of the reduction voltage is the voltage at which the slope of the voltage differential capacity rises becomes greater than or equal to a predetermined slope threshold on the side where the voltage is less than the voltage corresponding to the film formation peak; or the upper limit of the reduction voltage is the valley voltage of the voltage differential capacity on the side where the voltage is greater than the voltage corresponding to the film formation peak.

[0037] In the technical solution of this application embodiment, the voltage at which the slope of the voltage differential capacity rises becomes greater than or equal to a predetermined slope threshold when the voltage is less than the voltage corresponding to the film formation peak is used as the lower limit of the reduction voltage, and the voltage at the valley value of the voltage differential capacity when the voltage is greater than the voltage corresponding to the film formation peak is used as the upper limit of the reduction voltage. By charging and discharging multiple times within the range of the upper and lower limits of the reduction voltage, the voltage range with high efficiency of the reduction reaction is fully utilized, thereby improving the reaction efficiency.

[0038] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0039] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0040] Figure 1 This is a flowchart of a battery formation method according to some embodiments of this application.

[0041] Figure 2 This is a schematic diagram of the DQ / DV-V curves of the LiPF6 / LiFSI / LiTFSI electrolyte in some embodiments of this application.

[0042] Figure 3 This is a flowchart of a battery formation method for some other embodiments of this application.

[0043] Figure 4 This is a schematic flowchart of a battery formation method according to some embodiments of this application.

[0044] Figure 5 This is a schematic diagram of a battery formation apparatus according to some embodiments of this application.

[0045] Figure 6 This is a schematic diagram of a battery formation apparatus according to other embodiments of this application. Detailed Implementation

[0046] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0048] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0049] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0050] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0051] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0052] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0053] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0054] The structure of the SEI membrane consists of two or more layers of different materials:

[0055] Inner layer: The organic layer is relatively dense and is composed of inorganic products such as Li2CO3, LiF, Li2O, and LiOH;

[0056] Outer layer: loose or porous structure, composed of organic compounds such as lithium acetate and polymers.

[0057] The formation of the SEI film consumes some lithium ions, increasing the irreversible capacity during the initial charge-discharge cycle and reducing the charge-discharge efficiency of the electrode material. Furthermore, the SEI film is insoluble in organic solvents, remaining stable in organic electrolyte solutions. Solvent molecules have difficulty passing through this passivation film, effectively preventing co-intercalation of solvent molecules and avoiding damage to the electrode material caused by this process. This, in turn, improves the electrode's cycle performance and lifespan. Therefore, the SEI film has a significant impact on the performance of electrode materials.

[0058] To coordinate the performance of lithium-ion batteries to meet diverse market demands, battery electrolytes are often formulated using a combination of multiple lithium salts. The inventors of this application noted that the composition and properties of the SEI (Sediment In Sheath) are primarily influenced by the solvent within the solvation sheath and the complex products of anion decomposition. When the holding potential matches the decomposition potential of the anions, the anions preferentially decompose, forming an inorganic anion-derived SEI. Through studies of electrolyte formation curves, DQ / DV-V curves, and comparisons of the film quality of SEI films obtained based on different lithium salts, the inventors of this application found that the composition used in the experiment, exhibiting a higher film formation peak (i.e., higher film formation efficiency at its peak), resulted in an SEI film with better performance.

[0059] To address this characteristic, this application proposes a battery formation method and apparatus. By maintaining the reaction voltage more near the film-forming peak of the electrolyte reactants, it is beneficial for the more efficient film-forming components to participate in the reaction preferentially, thereby increasing the proportion of the generated SEI film based on the more efficient film-forming components, thus improving the film quality of the SEI film, effectively reducing the irreversible lithium consumption of the negative electrode during long-term battery cycle storage, and improving the battery's lifespan.

[0060] Battery cells produced using the battery formation method and apparatus of this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft, thereby improving the stability of battery performance and battery life.

[0061] Flowcharts of some embodiments of the battery formation method of this application are as follows: Figure 1 As shown.

[0062] In step S11, the lower and upper limits of the reduction voltage on both sides of the film-forming peak of the reactants in the electrolyte are determined. The reactants in the electrolyte include at least two reactive components. The amplitudes of the film-forming peaks differ for different reactive components, and the voltages corresponding to these peaks may also differ. The voltage corresponding to the film-forming peak is the potential at which the reaction rate of the reacting anions is highest. In some embodiments, the reduction reaction rate of the reactive components at different voltages can be tested through prior experiments to determine the voltage at which the reaction rate is highest as the voltage corresponding to the film-forming peak. In some embodiments, any method from related technologies can be used to obtain the voltage differential capacity (DQ / DV) curve, and the peak value of this curve is the film-forming peak.

[0063] The lower and upper limits of reduction voltage can be preset values ​​for the film-forming peak of the reactants, or they can be values ​​calculated based on the slopes of the rise and fall of the film-forming peaks on both sides.

[0064] In some embodiments, the lower limit of the reduction voltage can be the voltage on the side where the voltage is less than the voltage corresponding to the film formation peak, or the voltage when the slope of the DQ / DV rises is greater than or equal to a predetermined slope threshold; the upper limit of the reduction voltage can be the voltage on the side where the voltage is greater than the voltage corresponding to the film formation peak, or the valley voltage of DQ / DV, i.e., the voltage corresponding to the inflection point where DQ / DV falls to rise.

[0065] For example, such as Figure 2 The figure shows the DQ / DV-V curves of LiPF6 / LiFSI / LiTFSI electrolytes. For each electrolyte, the lower limit and upper limit of reduction voltage corresponding to the film formation peak shown in the figure can be determined.

[0066] In some embodiments, the film-forming peaks of the reactants in the electrolyte and the corresponding reduction voltage range between the upper and lower limits of the reduction voltage can be determined by pre-testing the electrolyte, and then recorded and set for reading and use during the battery formation process.

[0067] In step S12, multiple charge and discharge operations are performed within the range of the lower and upper limits of the reduction voltage. In some embodiments, the battery can be charged first from the lower limit of the reduction voltage, with the upper limit of the charge being the upper limit of the reduction voltage; then the battery can be discharged, with the lower limit of the discharge being the lower limit of the reduction voltage. Through repeated charge and discharge, formation near the film formation peak voltage is completed.

[0068] In some embodiments, during each charge and discharge operation in step S12, the current battery voltage can be acquired, and a target formation mode can be determined and executed based on the current voltage. The target formation mode includes a constant-voltage charging mode, a constant-current charging mode, and a constant-voltage discharging mode. For example, multiple voltage thresholds can be set, and the target formation mode is adjusted when the current voltage is detected to reach a voltage threshold. In some embodiments, the voltage value for constant-voltage charging is the lower limit of the restoration voltage, and the voltage value for constant-voltage discharging is the lower limit of the restoration voltage. In some embodiments, the current value for constant-current charging in step S12 can be set or adjusted based on experience and experimentation, for example, setting a small current of 0.01C for charging. By employing this method, the current state of the battery can be understood through voltage detection during multiple charge and discharge operations, and a matching formation mode can be adopted, improving the matching degree between the battery formation mode and the battery state, which is beneficial for improving formation efficiency and further improving the film quality of the SEI film.

[0069] In some embodiments, the procedure for each charge / discharge operation can be as follows: Figure 3 As shown in the image.

[0070] In step 201, the battery is charged to the lower limit of the reduction voltage of the reactants using a constant voltage.

[0071] In some embodiments, after charging to the lower limit of the reduction voltage is completed, the battery can be left to stand for a predetermined period of time to allow the battery state to stabilize.

[0072] In step 202, the battery is charged to the upper limit of the reduction voltage of the reactants using a constant current.

[0073] In some embodiments, after charging to the upper limit of the restoration voltage is completed, the battery can be left uncharged for a predetermined period of time to allow the battery state to stabilize.

[0074] In step 203, the battery is discharged to the lower limit of the reduction voltage of the reactants using a constant voltage.

[0075] In some embodiments, after discharging to the lower limit of the reduction voltage, the battery can be left to stand for a predetermined period of time to allow the battery state to stabilize.

[0076] In step 204, it is determined whether the condition for stopping multiple charge-discharge cycles has been met. If the condition is met, the repeated charge-discharge cycles for the current film formation peak end; if the condition is not met, the process returns to step 201.

[0077] In some embodiments, the condition for stopping multiple charge-discharge cycles can be that the number of repeated charge-discharge cycles reaches a target number, which can be a preset number of cycles, not less than 2. In some embodiments, this number can be 3 or more cycles. The SEI film formation quality will further improve with the increase of the number of repetitions within the threshold range. For example, repeating the charge-discharge operation 3 times can achieve a higher SEI film formation quality compared to repeating it 2 times.

[0078] In some embodiments, the target number can be determined experimentally. For example, the target number can be determined by the number of repeated charge-discharge cycles when the film-forming peak of the reactant in the electrolyte disappears after the reaction (e.g., the amplitude of the film-forming peak is less than a predetermined amplitude threshold). By using the amplitude of the film-forming peak as the criterion for determining the cutoff condition, the reactants can react more fully within the range of the lower and upper limits of the reduction voltage, thereby improving the film-forming quality of the SEI film.

[0079] The methods in the above embodiments of this application, through constant voltage charging and discharging, can reduce the gap between the reached voltage and the lower limit of the reduction voltage, and reduce voltage changes after resting; through constant current charging, the reaction time can be shortened and the charging efficiency can be improved, which is conducive to improving the formation efficiency of the battery. In addition, a cutoff condition is set for multiple charge and discharge operations within the range of the lower and upper limits of the reduction voltage to avoid getting stuck in a dead loop and affecting the formation progress.

[0080] In some embodiments, the switching between constant voltage and constant current charging / discharging operations described above can be determined by the currently used charging / discharging mode and the current voltage. For example, in step 201 above, if the current voltage is determined to be the lower limit of the restoration voltage during constant current charging, the target formation mode is determined to be the constant voltage charging mode; in step 202 above, if the current voltage is determined to be the lower limit of the restoration voltage during constant voltage charging, the target formation mode is determined to be the constant current charging mode; in step 203 above, if the current voltage is determined to be the upper limit of the restoration voltage during constant current charging, the target formation mode is determined to be the constant voltage discharging mode; in step 204 above, if the current voltage is determined to be the lower limit of the restoration voltage during constant voltage discharging, and the condition for stopping multiple charging and discharging operations has not been met, the target formation mode is determined to be the constant voltage charging mode.

[0081] By monitoring the current voltage in real time, the current voltage state of the battery can be determined in a timely manner, and then the corresponding charging and discharging modes can be switched. By switching to constant voltage charging and discharging modes in a timely manner, overcharging using constant current charging can be avoided, and the accuracy of reaching the lower limit of the reduction voltage can be improved. By switching to constant current charging mode in a timely manner, the reaction time can be shortened and the charging efficiency can be improved. Since the matching degree between the battery formation mode and the battery state is improved, it is beneficial to further improve the film formation quality of the SEI film.

[0082] In some embodiments, the reactive components include at least one of LiFSI, LiTFSI, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiFePO4, and LiCoO2. For example, it may include at least one of LiFSI / LiTFSI, as well as one or more other reactive components. Different reactive components possess different film-forming abilities. Through multiple charge-discharge cycles within the range of the lower and upper limits of the reduction voltage, the SEI film generated by the reactive component with stronger film-forming ability occupies a larger proportion, thereby improving the proportion of inorganic components in the SEI and enhancing the quality of the SEI film.

[0083] In some embodiments, the reactive components include at least one of LiFSI / LiTFSI and LiPF6. For example... Figure 2 As shown, a film-forming peak for LiFSI / LiTFSI exists at approximately 2.21V, which is related to FSI. － With TFSI －The anion reduction peak corresponds to the following: The film-forming peak amplitude of LiFSI / LiTFSI is higher than that of LiPF6. Therefore, during each charge-discharge process within the range of the lower and upper reduction voltage limits, LiFSI / LiTFSI preferentially participates in the reaction over LiPF6. This results in a larger proportion of the SEI film formed based on LiFSI / LiTFSI. Since the amount of SEI film that can be formed is limited, the number of SEI films that can be formed based on LiPF6 is reduced. Considering that LiFSI / LiTFSI can improve the performance of the SEI film, this method can improve the component ratio in the SEI film and enhance its performance.

[0084] In addition, by using the methods in the above embodiments, the requirements for the proportion of components in the electrolyte of multiple reaction components can be reduced. For example, if the price of LiFSI is too high, low-component LiFSI can be mixed with LiPF6, and then the film can be formed based on the preferential formation of LiFSI, thereby reducing costs and improving the performance of the SEI film.

[0085] In some embodiments, the term "first reactant" refers to a reactant component in the reactants that has high film-forming efficiency and can produce higher quality films, such as LiFSI / LiTFSI; the term "second reactant" refers to other reactant components in the reactants besides the first reactant, such as LiPF6. In step 202 above, the battery can be charged to the upper limit of the reduction voltage of the first reactant using a constant current; in step 203 above, the battery is discharged to the lower limit of the reduction voltage of the first reactant using a constant voltage.

[0086] In the technical solution of this application embodiment, the voltage range of multiple charge and discharge operations is controlled more within the upper and lower limits of the reduction voltage of the first reaction component, which is more conducive to the first reaction component participating in film formation and further increases the specific gravity of the SEI film obtained based on the first reaction component. Since the quality of the SEI film generated based on the first reaction component is higher than the quality of the solid electrolyte interface SEI film generated based on the second reaction component in the reactants, the quality of the SEI film can be further improved.

[0087] In some embodiments, the quality (or film quality) of the SEI film mentioned in this application refers to the performance of the battery with the SEI film. For example, the quality of the SEI film can be evaluated based on the capacity retention rate of the battery with the SEI film at the same number of cycles, or the number of cycles required for the battery with the SEI film to decay to a predetermined capacity retention rate.

[0088] In the technical solution of this application embodiment, during the battery formation process, multiple charge and discharge operations are performed within the range of the lower and upper limits of the reduction voltage on both sides of the film-forming peak of the reactants. Different reactive components in the electrolyte have different film-forming abilities. The SEI film generated based on the reactive component with stronger film-forming ability has better quality. Therefore, by performing multiple charge and discharge operations within the range of the lower and upper limits of the reduction voltage, the reactive component with stronger film-forming ability occupies a larger proportion in the reaction, thereby increasing the proportion of the SEI film generated based on that component, improving the quality of the SEI film, effectively reducing the irreversible lithium consumption of the negative electrode during long-term battery cycle storage, and improving the battery's lifespan.

[0089] In some embodiments, before performing multiple charge and discharge operations within the range of the lower and upper limits of the restoration voltage, a constant current charging mode can be used to charge the battery to a predetermined voltage, which can be the lower limit of the restoration voltage. This shortens the time it takes for the battery to rise from a lower voltage to the lower limit of the restoration voltage, thereby improving the efficiency of battery formation. Since the voltage measured in the constant current charging mode may contain dummy voltages, during the process of performing multiple charge and discharge operations within the range of the lower and upper limits of the restoration voltage, first charging to the lower limit of the restoration voltage with a constant voltage can reduce the difference between the achieved voltage and the lower limit of the restoration voltage, reduce voltage changes after resting, and improve the stability of the voltage range during multiple charge and discharge operations.

[0090] In some embodiments, if there are multiple film-forming peaks of the reactants, then during the charging process, according to the voltage of the film-forming peaks from low to high, multiple charge-discharge operations can be performed for each of the multiple film-forming peaks, determining a lower limit and an upper limit of the reduction voltage and performing multiple charge-discharge operations within the range of the lower and upper limits of the reduction voltage. Each charge-discharge operation can be as shown in any of the embodiments described above. The scheme in the embodiments of this disclosure enables sufficient reduction to be performed at each corresponding reduction potential, further improving the film-forming quality of the SEI film and thus contributing to a further increase in battery life.

[0091] For example, for each film-forming peak, its upper and lower limits of reduction voltage are determined. Then, when the battery is charged to the lower limit of the reduction voltage of a certain film-forming peak, multiple charge and discharge operations are performed within the range of the lower and upper limits of the reduction voltage of that film-forming peak. This further improves the film-forming quality of the SEI film and is conducive to further improving the battery's service life.

[0092] In some embodiments, after performing operations to determine the lower and upper limits of the reduction voltage and repeatedly charge and discharge within the range of the lower and upper limits of the reduction voltage for a film-forming peak, it is determined whether the current film-forming peak is the film-forming peak with the highest voltage value of the reactants. If the current film-forming peak is not the film-forming peak with the highest voltage value of the reactants, the battery is charged by constant current charging, and when the current voltage of the battery reaches the lower limit of the reduction voltage of the next film-forming peak, the operations to determine the lower and upper limits of the reduction voltage and repeatedly charge and discharge within the range of the lower and upper limits of the reduction voltage are performed for the next film-forming peak. In some embodiments, if the current film-forming peak is the film-forming peak with the highest voltage value of the reactants, the battery is charged to the cutoff SOC (State of Charge), completing the charging process in the formation operation.

[0093] In the technical solution of this application embodiment, after performing multiple charge and discharge operations within the range of the lower and upper limits of the reduction voltage for a film formation peak, the battery is quickly charged to the lower limit of the reduction voltage of the next film formation peak by a constant current, which shortens the time to enter the upper and lower limits of the reduction voltage of the next film formation peak and improves the battery formation efficiency.

[0094] For example, such as Figure 4 As shown, in steps 401-402, the battery formation operation is initiated by heating the formation furnace and turning on the high vacuum, thereby placing the battery cell to the target temperature.

[0095] In 403-404, the constant current charging mode is activated. The battery is charged to the lower limit of the reduction voltage of the first voltage peak (film formation peak) arranged in ascending order of voltage through constant current charging, and the voltage is marked.

[0096] Furthermore, in step 405, multiple charge-discharge processes are performed between the lower limit and the upper limit of the restoration voltage. In some embodiments, each charge-discharge process is as follows: Figure 4 The processing flow within the oscillation module is as follows: First, a constant voltage charging mode is used to charge the battery to the lower limit of the restoration voltage. After a period of rest, a constant current charging mode is used to charge the battery to the upper limit of the restoration voltage. After a period of rest, a constant voltage discharging mode is used to discharge the battery to the lower limit of the restoration voltage. After a period of rest, the next cycle of the oscillation module begins. If the cycle termination condition is reached, step 406 is executed, and the battery is rested for a period of time.

[0097] The processes 407-409 are similar to those in 403-405 above. A constant current charging mode is used to charge the battery to the lower limit of the reduction voltage of the second voltage peak (film formation peak) arranged in ascending order of voltage. Then, the battery is repeatedly charged and discharged using an oscillation module. If a third film formation peak exists, processes 403-405 are repeated, with the number of executions matching the number of film formation peaks. After completing the charge and discharge within the range from the lower to the upper limit of the reduction voltage of the last film formation peak, process 420 is executed.

[0098] In 420-423, the battery is charged to the cutoff SOC by constant current charging, and then cooling and vacuum release processes are performed to complete the battery formation process.

[0099] The above embodiments of this application provide a complete battery formation process. Based on this formation process, after charging to the decomposition potential of anions with a small current during the formation stage, the electrode potential can be repeatedly oscillated within the range of the anion decomposition potential through a small-range constant voltage charge-discharge mode. This promotes the decomposition of the target components at this decomposition potential, which are then enriched on the anode surface during the lithium-ion solvation-desolvation process to form an initial SEI film. This effectively improves the component ratio in the SEI, enhances the film quality, and thus improves battery performance.

[0100] To verify the effectiveness of the proposed solution, the inventors fabricated an experimental battery and performed formation using both relevant technologies and the methods mentioned in this application. The fabrication process is as follows. The battery fabrication process mentioned in this application is merely an experimental example and is not intended to limit the scope of the application, nor does it constitute an undue restriction on the application.

[0101] (1) Preparation of positive electrode

[0102] The active material, conductive agent acetylene black, and binder PVDF were mixed in a weight ratio of 94:4:2. N-methylpyrrolidone solvent was added, and the mixture was thoroughly stirred to obtain a homogeneous positive electrode slurry. This slurry was then coated onto both surfaces of the positive electrode current collector aluminum foil. The coating weight of the positive electrode slurry was 0.224 g / 1540.25 mm. 2 (Based on weight excluding solvent), then dried and cold-pressed to obtain the positive electrode sheet.

[0103] (2) Preparation of negative electrode

[0104] Artificial graphite (specific capacity 340 mAh / g), conductive agent acetylene black, and binder SBR+CMC were mixed in a weight ratio of 95:1.5:3.1:0.4. Deionized water was added as solvent, and the mixture was stirred thoroughly to obtain a negative electrode slurry. This slurry was then coated onto both surfaces of the copper foil used as the negative electrode current collector. The coating weight of the negative electrode slurry was 0.136 g / 1540.25 mm. 2(Based on weight excluding solvent), the negative electrode sheet is obtained after drying and cold pressing.

[0105] (3) Electrolyte preparation

[0106] In an argon atmosphere glove box with a water content of <10ppm, EC, PC, and DMC were mixed in a weight ratio of EC:PC:DMC = 3:3:3. Then, LiPF6, VC, DTD, and PS were added to the mixed organic solvent and stirred until homogeneous to obtain the electrolyte. The concentration of LiPF6 in the lithium-ion battery electrolyte was 1 mol / L, and the mass percentages of VC, DTD, and PS were 3%, 1%, and 1%, respectively.

[0107] (4) Preparation of the separating membrane

[0108] Polyethylene porous membrane is used as the separation membrane.

[0109] (5) Preparation of lithium-ion secondary batteries

[0110] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. These are then wound to obtain a bare cell. The bare cell is placed in an outer package, infused with prepared electrolyte, and sealed for formation to obtain a lithium-ion secondary battery.

[0111] Furthermore, the performance of the lithium-ion secondary battery was verified, and the verification process is as follows. This verification process is merely an example of a feasible verification method and is not intended to limit the scope of this application.

[0112] (1) At 25℃, the lithium-ion secondary battery is first charged at a constant current of 1C (i.e., the current value at which the theoretical capacity is completely discharged within 1 hour) to a voltage of 3.65V, and then charged at a constant voltage of 3.65V to a current of 0.05C. After standing for 5 minutes, the lithium-ion secondary battery is discharged at a constant current of 1C to a voltage of 2.5V. This is one charge-discharge cycle, and the discharge capacity of this cycle is the discharge capacity of the first cycle. The lithium-ion secondary battery is subjected to multiple charge-discharge cycles in the above manner until the discharge capacity of the lithium-ion secondary battery decays to 80%, and the number of cycles of the lithium-ion secondary battery is recorded.

[0113] (2) High-temperature cycle performance test of lithium-ion secondary batteries

[0114] At 60℃, the lithium-ion secondary battery was first charged at a constant current of 1C (i.e., the current value at which the theoretical capacity is completely discharged within 1 hour) to a voltage of 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C. After resting for 5 minutes, the lithium-ion secondary battery was discharged at a constant current of 1C to a voltage of 2.5V. This constitutes one charge-discharge cycle, and the discharge capacity of this cycle is the discharge capacity of the first cycle. The lithium-ion secondary battery was subjected to multiple charge-discharge cycles using the above method, and the discharge capacity of the 500th cycle was measured.

[0115] The capacity retention rate of a lithium-ion secondary battery after 500 cycles at 60℃ = (discharge capacity of the 500th cycle / discharge capacity of the first cycle) × 100%.

[0116] Verification showed that, compared to related technologies, the formation method described in this application improved the battery capacity retention by approximately 2% after 500 cycles.

[0117] Through comparative experiments comparing the formation methods in related technologies with those proposed in this application, the inventors verified that the battery with the formation method proposed in this application can withstand more cycles even when the discharge capacity decays to 80%; and the capacity retention rate of the battery after 500 cycles is significantly higher than that of the battery formed using related technologies.

[0118] This application also proposes a battery formation device 50, such as Figure 5 As shown in the image.

[0119] The battery formation apparatus 52 includes an oscillating charge-discharge module capable of determining the lower and upper limits of the reduction voltage on both sides of the film formation peak of the reactants in the electrolyte. The reactants include at least two reactive components. Within the range of the lower and upper limits of the reduction voltage, multiple charge-discharge operations are performed. In some embodiments, the oscillating charge-discharge module can perform step S12 described above, and... Figure 3 Operation in any of the embodiments shown.

[0120] In the technical solution of this application embodiment, during the battery formation process, multiple charge and discharge operations are performed within the range of the lower and upper limits of the reduction voltage on both sides of the film-forming peak of the reactants. Different reactive components in the electrolyte have different film-forming abilities. The SEI film generated based on the reactive component with stronger film-forming ability has better quality. Therefore, by performing multiple charge and discharge operations within the range of the lower and upper limits of the reduction voltage, the reactive component with stronger film-forming ability occupies a larger proportion in the reaction, thereby increasing the proportion of the SEI film generated based on that component, improving the quality of the SEI film, effectively reducing the irreversible lithium consumption of the negative electrode during long-term battery cycle storage, and improving the battery's lifespan.

[0121] In some embodiments, the battery formation apparatus further includes a constant current charging module 51, which can charge the battery by constant current charging and then activate the oscillating charge-discharge module 52 when the current voltage of the battery reaches the lower limit of the reduction voltage.

[0122] In the technical solution of this application embodiment, the battery is first charged to the lower limit of the reduction voltage using a constant current, which shortens the time for the battery to rise from a lower voltage to the lower limit of the reduction voltage and improves the efficiency of battery formation.

[0123] In some embodiments, such as Figure 6 As shown, the battery formation apparatus 50 includes multiple oscillating charge-discharge modules 521 to 52n, where n is a positive integer. Each oscillating charge-discharge module performs multiple charge-discharge operations within the range of the lower and upper limits of the reduction voltage for a single film formation peak. The number of film formation peaks of the reactants is greater than 1.

[0124] In the technical solution of this application embodiment, repeated charge and discharge operations are performed on multiple film formation peaks within the range of the lower limit and upper limit of the reduction voltage, so that sufficient reduction can be carried out at each corresponding reduction potential, which further improves the film formation quality of the SEI film and is conducive to further improving the service life of the battery.

[0125] In some embodiments, such as Figure 6 As shown, the battery formation apparatus 50 also includes multiple constant current charging modules 511 to 51n. In addition to the constant current charging module 511 connected in the execution order before the oscillating charge-discharge module 521, there is a constant current charging module between every two oscillating charge-discharge modules. The constant current charging module can charge the battery by constant current charging after the previous oscillating charge-discharge module has finished charging and discharging, and activate the next oscillating charge-discharge module when the current voltage of the battery reaches the lower limit of the reduction voltage of the next film formation peak.

[0126] In the technical solution of this application embodiment, after performing multiple charge and discharge operations within the range of the lower and upper limits of the reduction voltage for a film formation peak, the battery is quickly charged to the lower limit of the reduction voltage of the next film formation peak by a constant current, which shortens the time to enter the upper and lower limits of the reduction voltage of the next film formation peak and improves the battery formation efficiency.

[0127] In some embodiments, the battery formation apparatus 50 further includes a constant current charging module 51(n+1), which is connected after the last oscillating charge-discharge module 52n in the execution order. After the oscillating charge-discharge module 52n completes the charge-discharge within the range from the lower limit to the upper limit of the reduction voltage of the last film formation peak, the constant current charging module 51(n+1) charges the battery to the cutoff SOC through constant current charging, thereby completing the battery formation process.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery formation method, comprising: Determine the lower limit and upper limit of reduction voltage on both sides of the film-forming peak of the reactants in the electrolyte, wherein the reactants include at least two reactive components; Within the range of the lower limit and the upper limit of the restoration voltage, multiple charge and discharge operations are performed.

2. The battery formation method according to claim 1, wherein, Performing multiple charge and discharge operations within the range of the lower limit and the upper limit of the restoration voltage includes: Get the current battery voltage; The target formation mode is determined based on the current voltage, and the target formation mode includes constant voltage charging mode, constant current charging mode and constant voltage discharging mode; Perform the target transformation into a pattern.

3. The battery formation method according to claim 1 or 2, wherein, Each charge / discharge operation includes: The battery is charged to the lower limit of the reduction voltage of the reactants using a constant voltage. The battery is charged to the upper limit of the reduction voltage of the reactants using a constant current; and The battery is discharged to the lower limit of the reduction voltage of the reactants using a constant voltage.

4. The battery formation method according to claim 2, wherein, The step of determining the target formation mode based on the current voltage includes: When the current voltage is determined to be the lower limit of the restoration voltage during constant current charging, the target formation mode is determined to be constant voltage charging mode. When the current voltage is determined to be the lower limit of the restoration voltage during constant voltage charging, the target formation mode is determined to be constant current charging mode. When the current voltage is determined to be the upper limit of the restoration voltage during constant current charging, the target formation mode is determined to be constant voltage discharge mode. If, during constant voltage discharge, the current voltage is determined to be the lower limit of the reduction voltage, and the conditions for stopping the multiple charging and discharging operations have not been met, then the target formation mode is determined to be constant voltage charging mode.

5. The battery formation method according to claim 2, wherein, The step of performing multiple charge and discharge operations within the range of the lower limit and the upper limit of the restoration voltage further includes: When the target number of charge and discharge cycles is reached, charging and discharging within the range of the lower limit and the upper limit of the restoration voltage shall be stopped.

6. The battery formation method according to claim 1, further comprising: The battery is charged by constant current charging. If the current voltage of the battery reaches the lower limit of the restoration voltage, perform multiple charge and discharge operations within the range of the lower limit of the restoration voltage and the upper limit of the restoration voltage.

7. The battery formation method according to claim 1, wherein, The number of film-forming peaks of the reactants is greater than 1. According to the order of voltage of the film formation peak from low to high, for multiple film formation peaks, the operation of determining the lower limit of reduction voltage and the upper limit of reduction voltage and charging and discharging multiple times within the range of the lower limit of reduction voltage and the upper limit of reduction voltage is performed.

8. The battery formation method according to claim 7, further comprising: For a given film-forming peak, perform the operation of determining a lower limit and an upper limit of reduction voltage, and then repeatedly charge and discharge within the range of the lower limit and the upper limit of reduction voltage; If the current film-forming peak is not the film-forming peak with the highest voltage value of the reactant, the battery is charged by constant current charging, and when the current voltage of the battery reaches the lower limit of the reduction voltage of the next film-forming peak, the operation of determining the lower limit and upper limit of the reduction voltage and charging and discharging multiple times within the range of the lower limit and upper limit of the reduction voltage is performed for the next film-forming peak.

9. The battery formation method according to claim 1, wherein, The reaction components include at least one of LiFSI, LiTFSI, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiFePO4, and LiCoO2.

10. The battery formation method according to claim 9, wherein, Performing multiple charge and discharge operations within the range of the lower limit and the upper limit of the restoration voltage includes: The battery is charged to the lower limit of the reduction voltage of the reactants using a constant voltage. The battery is charged to the upper limit of the reduction voltage of the first reaction component using a constant current; and The battery is discharged to the lower limit of the reduction voltage of the first reactive component using a constant voltage. Wherein, the range between the lower limit of the reduction voltage of the first reactive component and the upper limit of the reduction voltage of the first reactive component is smaller than the range between the lower limit of the reduction voltage of the reactant and the lower limit of the reduction voltage of the reactant.

11. The battery formation method according to claim 1, wherein, The method meets at least one of the following criteria: The lower limit of the reduction voltage is: the voltage at which the slope of the voltage differential capacity rise becomes greater than or equal to a predetermined slope threshold on the side where the voltage is less than the voltage corresponding to the film formation peak; or The upper limit of the reduction voltage is: the valley voltage of the voltage differential capacity on the side where the voltage is greater than the voltage corresponding to the film formation peak.

12. A battery formation apparatus, comprising an oscillating charge-discharge module, configured to: Determine the lower and upper limits of reduction voltage on both sides of the film-forming peak of the reactants in the electrolyte; Within the range of the lower limit and the upper limit of the reduction voltage, multiple charge and discharge operations are performed, and the reactants include at least two reactive components.

13. The battery formation apparatus according to claim 12, further comprising a constant current charging module configured as follows: The battery is charged by constant current charging. When the current voltage of the battery reaches the lower limit of the reduction voltage, the oscillation charge-discharge module is activated.

14. The battery formation apparatus according to claim 13, wherein, The battery formation device includes multiple oscillation charge / discharge modules. Each of the oscillating charge-discharge modules performs multiple charge-discharge operations within the range of a given reduction voltage threshold and an upper reduction voltage threshold for a single film formation peak. The number of film-forming peaks of the reactants is greater than 1.

15. The battery formation apparatus according to claim 14, wherein, A constant current charging module is included between every two oscillating charge / discharge modules, and the constant current charging module is configured to: After the previous oscillating charge-discharge module completes its charge-discharge cycle, the battery is charged by constant current charging, and when the current voltage of the battery reaches the lower limit of the reduction voltage of the next film formation peak, the next oscillating charge-discharge module is activated.

16. The battery formation apparatus according to claim 11, wherein, The device meets at least one of the following criteria: The lower limit of the reduction voltage is: the voltage at which the slope of the voltage differential capacity rise becomes greater than or equal to a predetermined slope threshold on the side where the voltage is less than the voltage corresponding to the film formation peak; or The upper limit of the reduction voltage is: the valley voltage of the voltage differential capacity on the side where the voltage is greater than the voltage corresponding to the film formation peak.

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