Formation method of battery, battery, and electric device
By adding a static step at atmospheric pressure to the cell during the lithium battery formation process, the overflowing electrolyte flows back into the cell, solving the problem of electrolyte loss during formation and improving the electrochemical performance of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- EVE ENERGY CO LTD
- Filing Date
- 2026-04-09
- Publication Date
- 2026-07-21
AI Technical Summary
During the formation of lithium batteries, electrolyte loss significantly affects battery performance, leading to electrolyte spillage and loss during formation, which in turn affects the battery's electrochemical performance.
By adding a static step at atmospheric pressure during the formation process, the electrolyte that overflows during formation and evaporates into the vacuum pipeline flows back into the cell under gravity, reducing electrolyte loss.
It effectively reduces electrolyte loss during the formation process, improves the electrochemical performance of the battery, avoids equipment contamination and clogging problems, and enhances the overall performance of the battery.
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Figure SMS_1
Abstract
Description
Technical Field
[0001] This application belongs to the field of battery technology, specifically relating to battery formation methods, batteries, and electrical devices. Background Technology
[0002] Formation is an essential step in lithium battery production, playing a crucial role in determining battery performance. Especially for pouch lithium batteries and aluminum-cased prismatic batteries, formation not only activates electrode materials, improves the lithium battery interface, reduces self-discharge and cycle life, but also enhances cell rigidity and shapes the battery. However, the electrochemical reduction reaction during the initial formation of the SEI film generates gas. The presence of this gas can lead to electrolyte leakage, resulting in electrolyte loss during formation and severely impacting battery performance. Therefore, minimizing electrolyte loss during the formation stage is critical for improving battery performance. Summary of the Invention
[0003] This application aims to at least partially address one of the technical problems in related technologies. To this end, this application proposes a battery formation method, a battery, and an electrical device. The battery formation method of this application can reduce electrolyte loss to a certain extent, thereby contributing to improved battery performance.
[0004] A first aspect of this application proposes a method for forming a battery, comprising: After the battery cell is placed in the formation cabinet, the battery cell is drawn to a negative pressure of the first negative pressure and charged with a first constant current for a first time, with a cutoff voltage of 3200mV~4000mV. The second constant current is used to charge for a second time, with a cutoff voltage of 3200mV~4000mV; Depressurize the battery cell to normal pressure; Allow the battery cell to stand at normal pressure for at least 30 seconds, disconnect the liquid injection cup, the formation is complete, and discharge the battery cell.
[0005] The battery formation method of this application allows the battery cell to stand at atmospheric pressure for at least 30 seconds in the final stage of formation. Standing at atmospheric pressure allows the electrolyte that was drawn back during the formation process (i.e., the electrolyte that overflowed into the buffer cup under negative pressure and the electrolyte that evaporated into the vacuum pipeline) to flow back into the battery cell under the action of gravity, reducing the loss of electrolyte during the formation process and thus improving the electrochemical performance of the battery.
[0006] In addition, the battery formation method according to the above embodiments of this application may also have the following additional technical features: In some embodiments of this application, the battery cell is allowed to stand at atmospheric pressure for at least 80 seconds, the electrolyte filling cup is disconnected, the formation process is completed, and the battery cell is removed. This helps to further reduce electrolyte loss during the formation process, thereby improving the electrochemical performance of the battery.
[0007] In some embodiments of this application, the second constant current is used to charge the second time under the second negative voltage, the cutoff voltage is 3200mV~4000mV, and the second negative voltage is greater than the first negative voltage.
[0008] This helps to further reduce electrolyte loss during the formation process, thereby improving the electrochemical performance of the battery.
[0009] In some embodiments of this application, the battery formation method satisfies at least one of the following conditions: The first negative pressure is -90 kPa to -70 kPa; The second negative pressure is -80 kPa to -60 kPa; The first constant current is 0.001C~0.1C, where C is the rated capacity of the battery cell; The second constant current is 0.001C~0.5C, where C is the rated capacity of the battery cell; The first time is ≥120 min; The second time is ≥120 min.
[0010] In some embodiments of this application, the formation temperature is ≤60°C.
[0011] In some embodiments of this application, after charging with a second constant current for a second time and the cutoff voltage is 3200mV~4000mV, before depressurizing the cell to atmospheric pressure, the method further includes: allowing the cell to stand for a third time, the third time being ≥1min.
[0012] In some embodiments of this application, after the battery cell is placed in the first negative pressure formation cabinet, and before the first time of charging with the first constant current and before the cutoff voltage is 3200mV~4000mV, the method further includes: letting the battery cell stand still for a fourth time, the fourth time being ≥1min.
[0013] In some embodiments of this application, after the first charging time with a first constant current and a cutoff voltage of 3200mV~4000mV, and before the second charging time with a second constant current and a cutoff voltage of 3200mV~4000mV, the method further includes: The battery cell is left to stand for a fifth time, the fifth time being ≥1 minute.
[0014] In some embodiments of this application, the battery formation method satisfies at least one of the following conditions: Before the battery cell is placed in the formation cabinet, the electrolyte content in the battery cell is 300g / 100Ah~350g / 100Ah; The negative pressure is drawn using a negative pressure pump that connects a suction nozzle, a buffer cup, and a vacuum pipeline. Before drawing the negative pressure, the suction nozzle is inspected. If crystals or foreign objects appear on the surface of the suction nozzle, the nozzle is cleaned or replaced.
[0015] In a second aspect, this application proposes a battery obtained by the formation method of a previous battery. Consequently, this battery exhibits excellent electrochemical performance.
[0016] A third aspect of this application provides an electrical device comprising the aforementioned battery. Therefore, this electrical device exhibits excellent electrochemical performance. Detailed Implementation
[0017] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and intended to explain this application, and should not be construed as limiting this application.
[0018] During the formation process, the cell releases gases (such as H2, CO, etc.) and generates heat. The gas production inside the cell creates a high-pressure and high-temperature environment, while the external buffer cup is in a relatively low-pressure state (connected to the vacuum line). This pressure and temperature difference forces the electrolyte inside the cell to be forced out along with the gas through the injection hole or venting channel and into the buffer cup. Some of the electrolyte will also evaporate and condense in the vacuum line. This electrolyte cannot flow back, which will directly cause electrolyte loss and affect the battery performance.
[0019] Based on the above understanding, the inventors considered increasing the settling time of the battery cell after the conventional formation process, so that the residual electrolyte in the pipeline and injection cup can flow back into the battery cell, thereby reducing the amount of electrolyte loss.
[0020] Therefore, in the first aspect of this application, a method for forming a battery is proposed, comprising: S10: After placing the battery cell into the formation cabinet, draw the negative pressure of the battery cell to the first negative pressure, and charge it with the first constant current for the first time, with a cutoff voltage of 3200mV~4000mV.
[0021] In this step, during the initial stage of formation, the cell is charged with a small current (i.e., a first constant current) under a first negative voltage environment, at which point the base layer of the SEI film begins to form on the surface of the negative electrode.
[0022] In some embodiments, the first constant current is 0.001C to 0.1C, specifically, it can be 0.001C, 0.01C, 0.05C, 0.1C, or any two thereof, where C is the rated capacity of the cell. Controlling the first constant current within the above range ensures that lithium ions slowly embed into the negative electrode surface, allowing the solvent and additives in the electrolyte to gradually react on the negative electrode surface, forming a dense and uniform SEI film. Because the chemical reaction on the negative electrode surface is unstable during the first charge, if a large current is used for charging from the beginning, the reaction will be too vigorous, easily leading to abnormalities such as pinholes, cracks, or localized excessive thickness in the formed SEI film, affecting subsequent battery performance.
[0023] In some embodiments, the initial charging time is ≥120 min, specifically 120 min, 150 min, 200 min, 300 min, 500 min, etc. This charging time generally ensures that the solvent and additives in the electrolyte gradually decompose on the negative electrode surface, forming a moderately thick and structurally stable SEI film. Simultaneously, it allows the electrolyte to penetrate more uniformly into the electrode interior, laying the foundation for the subsequent high-current charging stage.
[0024] In some embodiments, the first negative pressure is -90 kPa to -70 kPa, specifically -90 kPa, -85 kPa, -83 kPa, -80 kPa, -78 kPa, -75 kPa, -70 kPa, or any range between the two. This negative pressure environment can stably remove the gas generated during SEI film formation while ensuring that too much electrolyte is not removed. Insufficient negative pressure during formation may result in the generated gas not being removed in time, causing a rapid increase in internal pressure and leading to greater electrolyte leakage. Conversely, excessive negative pressure may cause the electrolyte to decompose too quickly, resulting in a loose SEI film and affecting battery performance.
[0025] In some embodiments, after the battery cell is placed in the first negative pressure formation cabinet and before the small current charging, the battery cell is left to stand in the formation cabinet for a fourth time, the fourth time being ≥1 minute (specifically, it can be 1 minute, 5 minutes, 10 minutes, 30 minutes, etc.). The standing time allows the pressure inside the battery cell to reach equilibrium with the negative pressure environment of the formation cabinet, thereby ensuring the smooth progress of the subsequent formation process. At the same time, the standing time can also further make the electrolyte evenly distributed in the battery cell, thereby improving the battery performance.
[0026] In some embodiments, after the low-current charging is completed, the battery cell can be left to stand in a negative pressure environment for a fifth time, the fifth time being ≥1 minute (specifically, it can be 1 minute, 5 minutes, 10 minutes, 30 minutes, etc.). During the low-current charging process, side reaction gases are generated. At this time, leaving the cell to stand allows the side reaction gases sufficient time to diffuse out from the pores of the electrode or the micropores of the separator, which helps to improve the adhesion between the battery electrode and the separator, thereby improving the battery performance.
[0027] In some embodiments, the negative pressure is applied using a suction nozzle, which is tightly connected to the cell's electrolyte filling port through a sealing and pressing mechanism. A vacuuming device is connected to the suction nozzle and the buffer cup to create a sealed negative pressure environment. To enhance sealing, the contact end of the suction nozzle is typically made of electrolyte-resistant rubber or fluoropolymer. However, lithium salts (such as LiPF6) in the electrolyte can crystallize on the nozzle surface, and long-term use may also cause deformation of the nozzle's rubber sealing end. Both of these situations directly compromise the sealing performance between the suction nozzle and the filling port. With poor sealing, the airflow velocity increases abnormally during vacuuming, and the high-speed airflow directly carries the electrolyte out of the cell, causing electrolyte overflow and further increasing electrolyte loss during the formation stage. Therefore, the suction nozzle should be inspected during negative pressure application. When crystals appear on the nozzle surface, it needs to be cleaned or replaced to reduce electrolyte loss during battery formation.
[0028] S20: Charge for a second time with a second constant current, with a cutoff voltage of 3200mV~4000mV.
[0029] In this step, the battery cell is charged with a large current (i.e., the second constant current), which makes the initially formed SEI film denser. At the same time, the electrolyte in each area inside the battery cell is fully wetted, and the active materials of the electrodes are fully activated, which helps to improve the capacity and cycle stability of the battery cell.
[0030] In some embodiments, the second constant current charging for the second time can continue under the first negative pressure condition, or the pressure can be released to the second negative pressure before the second constant current charging process is performed, wherein the second negative pressure is greater than the first negative pressure. Gradually increasing the negative pressure during the formation process helps to further reduce electrolyte loss.
[0031] Specifically, the second negative pressure is -80 kPa to -60 kPa. For example, it can be -80 kPa, -75 kPa, -70 kPa, -65 kPa, -60 kPa, or any range between two of these. A second negative pressure within the above range can basically ensure the smooth progress of the second constant current charging process.
[0032] In some embodiments, the second constant current is 0.001C to 0.5C, specifically, it can be a range of 0.001C, 0.005C, 0.01C, 0.05C, 0.1C, 0.5C, or any two of them. A high current within this range ensures a more complete reaction inside the cell, driving more lithium ions to escape from the positive electrode and migrate to the negative electrode at a faster rate, thereby further improving the battery capacity.
[0033] In some embodiments, the second time is ≥120 min, specifically, it can be 120 min, 150 min, 200 min, 300 min, 500 min, etc. The above charging time can basically ensure that the reaction inside the cell is sufficient, the active material of the electrode is fully activated, and thus ensure the battery capacity.
[0034] S30: Depressurize the battery cell to atmospheric pressure.
[0035] In this step, the battery is depressurized to atmospheric pressure after completing the charging and discharging process.
[0036] In some embodiments, after charging with a second constant current for a second time, and after the cutoff voltage is 3200mV~4000mV, before depressurizing the cell to atmospheric pressure, the method further includes: allowing the cell to stand for a third time, the third time being ≥1 minute (specifically, it can be 1 minute, 5 minutes, 10 minutes, 30 minutes, etc.), and finally depressurizing the cell to atmospheric pressure. Specifically, after charging is completed, a small amount of undischarged reaction gas may still remain inside the cell. Allowing the cell to stand under negative pressure for a certain period of time can continuously remove these gases, which helps to further ensure the structural integrity of the cell.
[0037] S40: Allow the battery cell to stand at atmospheric pressure for at least 30 seconds, disconnect the liquid injection cup, the formation is complete, and remove the battery cell.
[0038] In this step, allowing the battery cell to stand at atmospheric pressure allows the electrolyte that was drawn back during the initial formation process (i.e., electrolyte that overflowed into the buffer cup under negative pressure and electrolyte that evaporated into the vacuum lines) to flow back into the battery cell under gravity, further reducing electrolyte loss. Without this atmospheric pressure standing step, the electrolyte in the buffer cup and vacuum lines cannot flow back into the battery cell, resulting in a significant waste of electrolyte. Furthermore, this electrolyte will solidify and accumulate in the buffer cup and vacuum lines, and may even drip onto the equipment surface, causing blockages and contamination.
[0039] Specifically, the settling time can be 30s, 40s, 50s, 60s, 80s, 100s, 120s, 150s, 200s, 250s, 300s, or any combination thereof. These times generally ensure that most of the electrolyte remaining in the buffer cup and vacuum tubing flows back into the cell under gravity. Furthermore, a settling time of 80s or more helps to further reduce electrolyte loss. More specific settling times can be determined based on actual needs.
[0040] In some embodiments, the battery cell needs to be injected with electrolyte before the battery formation method of this application. The electrolyte content in the battery cell is 300g / 100Ah to 350g / 100Ah, specifically 300g / 100Ah, 310g / 100Ah, 320g / 100Ah, 330g / 100Ah, 340g / 100Ah, 350g / 100Ah, etc. If too much electrolyte is injected, the electrolyte level inside the battery cell may increase, and under the subsequent negative pressure, more electrolyte will flow back into the injection cup or equipment. Therefore, it is necessary to ensure that the amount of electrolyte injected is within the target range, thereby further reducing electrolyte loss and reducing costs to a certain extent.
[0041] In a second aspect, this application provides a battery obtained by the aforementioned battery formation method. Consequently, this battery exhibits excellent electrochemical performance.
[0042] According to the embodiments of this application, it can be understood that the specific type of battery is not particularly limited, and it can be a primary battery or a secondary battery; the shape of the battery can be a cylindrical battery, a square battery, or other batteries of any shape, and according to the outer packaging, the battery can be a hard-shell battery, a soft-pack battery, etc. In other embodiments, the battery can be a lithium-ion battery, a sodium-ion battery, etc.
[0043] Typically, a battery includes a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode, negative electrode, and separator are fabricated into electrode assemblies using winding or stacking processes. The electrode assemblies and electrolyte are housed in an outer package. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and extracting. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.
[0044] The positive electrode in the battery may include a positive current collector and a positive active material layer, wherein the positive active material layer is disposed on at least one surface of the positive current collector.
[0045] In some embodiments, the positive electrode current collector can be a metal current collector or a composite current collector. For example, metal current collectors include, but are not limited to, aluminum foil current collectors, which have strong electrochemical stability, do not undergo side reactions with the positive electrode material or electrolyte, and can maintain the stability of the positive electrode current collector for a long time; composite current collectors may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. Composite current collectors can be formed by forming metal materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
[0046] In some embodiments, the positive electrode active material layer may include positive electrode active material, binder and conductive agent, and may also include additives with specific functions and effects, such as thickeners, sodium supplements, film-forming additives, flame retardants, high temperature / low temperature stabilizers, etc., as needed.
[0047] As an example, the positive electrode active material includes at least one of the following: layered structure positive electrode active materials (e.g., nickel-cobalt-manganese ternary positive electrode materials, nickel-cobalt-aluminum ternary positive electrode materials, lithium nickel oxide / sodium, lithium cobalt oxide / sodium, lithium manganese oxide / sodium, lithium-rich / sodium layered and rock salt phase layered materials), olivine-type phosphate active materials (e.g., lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, etc.), and spinel structure positive electrode active materials (e.g., spinel lithium manganese oxide, spinel lithium nickel manganese oxide, lithium-rich spinel lithium manganese oxide, and lithium nickel manganese oxide, etc.). It is understood that the above-mentioned positive electrode active materials may further include doping elements and coating layers. As a specific example, the positive electrode active material includes lithium iron phosphate. Therefore, the battery has better cycle stability and safety performance.
[0048] As an example, the binder in the positive electrode active material layer may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.
[0049] As an example, the conductive agent in the positive electrode active material layer may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
[0050] In some embodiments, the electrolyte may include lithium salts and solvents. Furthermore, additives with specific functions, such as film-forming additives, lithium replenishing agents, flame retardants, and thermal stability additives, may be added to the electrolyte as needed. As an example, the electrolyte may include lithium salts, solvents, and additives.
[0051] In some embodiments, the lithium salt may include lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate, etc. Lithium salts can provide lithium ions to lithium-ion batteries, support electrolyte stability and electrochemical reactions, help form a protective SEI film, improve conductivity, and enhance the safety of lithium-ion batteries.
[0052] In some embodiments, the solvent may include carbonates, fluorocarbonates, etc. This allows for the thorough dissolution of lithium salts, provides an ion transport medium, and also helps improve the electrochemical and safety performance of lithium-ion batteries.
[0053] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer disposed on at least one side surface of the negative electrode current collector. As an example, the negative electrode active material layer may include a negative electrode material, a thickener, a conductive agent, and a binder.
[0054] Specifically, the negative electrode current collector can be a metal foil, such as copper foil. Copper has excellent conductivity, which can efficiently transfer electrons from the negative electrode, reduce the internal resistance of the electrode, and improve the rate performance of the battery. At the same time, copper will not undergo side reactions with the negative electrode material. The negative electrode material can include carbon-based materials, silicon-based materials, tin-based materials, etc. The binder in the negative electrode material layer can include, but is not limited to, at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethyl methacrylate (PMAA), and carboxymethyl chitosan (CMCS). The conductive agent in the negative electrode material layer can include, but is not limited to, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
[0055] In a third aspect of this application, an electrical device is proposed, comprising the aforementioned positive electrode or the aforementioned battery. Therefore, the electrical device has high capacity and energy density.
[0056] In some embodiments, the specific type of electrical device is not particularly limited and can be any device that uses a battery as a power source or energy storage unit. Examples of electrical devices include, but are not limited to, electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), mobile terminals (e.g., mobile phones, laptops, game consoles, wearable devices, etc.), drones, aerospace equipment, satellites, ships, energy storage systems, and so on.
[0057] It is understood that, in addition to the battery mentioned above, the electrical device also includes other necessary structures and components, all of which can be made with reference to conventional technologies. For example, an electric vehicle may include a body, chassis, tires, navigation system, radar system, steering system, braking system, lubrication system, cooling system, driving system, etc., which will not be described in detail here.
[0058] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.
[0059] Example 1 Preparation of the positive electrode sheet: The positive electrode active material NCM811, conductive graphite, PVDF, and PMAA were mixed in a mass ratio of 96.8:1.5:1.5:0.2. First, the mixture was dry-mixed, then a suitable amount of solvent was added for wet mixing to obtain a positive electrode slurry. The solid content of the positive electrode slurry was controlled to be 65%. Further, the positive electrode slurry was coated onto aluminum foil (6 micrometers thick), dried at 100°C, and rolled. Finally, it was die-cut according to the cell size to obtain the positive electrode sheet, which was then placed in a nitrogen oven at 110°C for later use. The double-sided areal density of the positive electrode sheet was 40 mg / cm³. 2 The compacted density is 2.30 g / cm³. 3 .
[0060] Preparation of the negative electrode sheet: A slurry was prepared by mixing hard carbon, carbon nanotubes, and SBR in a mass ratio of 96.5:1.0:2.5. The mixture was first dry-mixed, then wet-mixed with an appropriate amount of solvent to obtain the negative electrode slurry, with a solid content controlled at 55%. The negative electrode slurry was then coated onto a 6μm thick copper foil, dried at 100℃, and rolled. Finally, it was die-cut to the cell dimensions to obtain the negative electrode sheet, which was then placed in a nitrogen oven at 110℃ for later use. The double-sided areal density of the negative electrode sheet was 13 mg / cm³. 2 The compacted density is 1.50 g / cm³. 3 .
[0061] Electrolyte preparation: LiPF6:EC:EA:VC = 14%wt:70%wt:10%wt:6%wt.
[0062] Cell assembly: A lamination process is used, with one more negative electrode than positive electrode. The number of electrodes is calculated based on a design capacity of 100Ah. The cells are stacked in the following order: separator, negative electrode, separator, positive electrode, separator, negative electrode. After hot pressing, tab welding, and encapsulation, the moisture content is controlled below 300ppm. The cells are then injected with electrolyte, with a volume of 350g.
[0063] Formation process: Place the battery cell in the formation cabinet, draw the negative pressure of the battery cell to the first negative pressure (-85KPa), let it stand for 5 minutes, and then charge it with a constant current of 0.1C for 120 minutes. The cutoff voltage is 3650mV. Let the battery cells stand for 5 minutes; When charged with a constant current of 0.5C for 120 minutes, the cutoff voltage is 3650mV; After letting the battery cells stand for 5 minutes, depressurize the formation cabinet to atmospheric pressure; Allow the battery cell to stand at normal pressure for 80 seconds to complete the formation process, then remove the battery cell.
[0064] Examples 2-13 Same as Example 1, the main differences are shown in Table 1.
[0065] Example 14 Same as Example 1, the main differences are shown in Table 1, and the amount of electrolyte injected is 300g.
[0066] Example 15 Same as Example 1, the main differences are shown in Table 1, and the amount of electrolyte injected is 330g.
[0067] Example 16 Similar to Example 1, the main difference is that: before formation, it was checked that there were crystals in the injection cup, but the injection cup was not cleaned or replaced.
[0068] Example 17 Same as Example 1, the main difference is that the amount of electrolyte injected is 370g.
[0069] Examples 18-22 Same as Example 1, the main differences are shown in Table 1.
[0070] Comparative Example 1 Same as Example 1, the main differences are shown in Table 1.
[0071] Test methods Electrolyte loss: The cell is weighed immediately after electrolyte injection and recorded as W1. The cell is weighed after formation and recorded as W2. The electrolyte loss is W1-W2.
[0072] Table 1
[0073] Conclusion: As can be seen from Examples 1-22 and Comparative Example 1, the battery formation method of this application can reduce the electrolyte loss during the battery formation process.
[0074] In the description of this invention, it should be understood that the 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" are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.
[0075] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0076] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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, an electrical connection, or a connection that allows communication between them; 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, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0077] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0078] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0079] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A method for forming a battery, characterized in that, include: After the battery cell is placed in the formation cabinet, the battery cell is drawn to a negative pressure of the first negative pressure and charged with a first constant current for a first time, with a cutoff voltage of 3200mV~4000mV. The second constant current is used to charge for a second time, with a cutoff voltage of 3200mV~4000mV; Depressurize the battery cell to normal pressure; Allow the battery cell to stand at normal pressure for at least 30 seconds, disconnect the liquid injection cup, the formation is complete, and remove the battery cell.
2. The battery formation method according to claim 1, characterized in that, Allow the battery cell to stand at normal pressure for at least 80 seconds, disconnect the liquid injection cup, the formation is complete, and remove the battery cell.
3. The battery formation method according to claim 1 or 2, characterized in that, Under the second negative voltage, the second constant current is used to charge for a second time, and the cutoff voltage is 3200mV~4000mV, and the second negative voltage is greater than the first negative voltage.
4. The battery formation method according to claim 3, characterized in that, At least one of the following conditions must be met: The first negative pressure is -90 kPa to -70 kPa; The second negative pressure is -80 kPa to -60 kPa; The first constant current is 0.001C~0.1C, where C is the rated capacity of the battery cell; The second constant current is 0.001C~0.5C, where C is the rated capacity of the battery cell; The first time is ≥120 min; The second time is ≥120 min.
5. The battery formation method according to claim 1, characterized in that, The temperature during battery formation is ≤60℃.
6. The battery formation method according to claim 1, characterized in that, After charging with a second constant current for a second time, and after the cutoff voltage is 3200mV~4000mV, before depressurizing the cell to atmospheric pressure, the process further includes: allowing the cell to stand for a third time, the third time being ≥1min.
7. The battery formation method according to claim 1, characterized in that, After the cell is placed in the first negative voltage formation cabinet, and before the first time of charging with the first constant current, the cutoff voltage is 3200mV~4000mV, the process further includes: The battery cell is left to stand for a fourth time, the fourth time being ≥1 minute.
8. The battery formation method according to claim 1, characterized in that, After the first charging time with the first constant current, when the cutoff voltage is 3200mV~4000mV, and before the second charging time with the second constant current, when the cutoff voltage is 3200mV~4000mV, the method further includes: The battery cell is left to stand for a fifth time, the fifth time being ≥1 minute.
9. The battery formation method according to claim 1, characterized in that, At least one of the following conditions must be met: Before the battery cell is placed in the formation cabinet, the electrolyte content in the battery cell is 300g / 100Ah~350g / 100Ah; The negative pressure is drawn using a negative pressure pump that connects a suction nozzle, a buffer cup, and a vacuum pipeline. Before drawing the negative pressure, the suction nozzle is inspected. If crystals or foreign objects appear on the surface of the suction nozzle, the nozzle is cleaned or replaced.
10. A battery, characterized in that, It is obtained by the battery formation method described in any one of claims 1 to 9.
11. An electrical appliance, characterized in that, Includes the battery as described in claim 10.