Sodium-ion battery formation method and device and sodium-ion battery

Abstract

The invention provides a sodium-ion battery formation method and device and a sodium-ion battery, and the formation method comprises the following steps: an initial voltage detection step: providing an assembled sodium-ion battery, detecting the positive and negative electrode placement positions and the initial voltage of the sodium-ion battery, and judging whether the initial voltage is greater than or equal to zero; a pre-charging step: if the initial voltage is less than zero, pre-charging the sodium ion battery in a stepped charging mode until the voltage of the pre-charged sodium ion battery is greater than or equal to zero within the maximum pre-charging times; and a formation step: performing formation on the sodium ion battery with the initial voltage greater than or equal to zero or the sodium ion battery with the voltage greater than or equal to zero after pre-charging, and performing negative pressure formation in a stepped charging mode. According to the sodium ion battery formation method and device and the sodium ion battery provided by the invention, compatibility with a lithium ion battery production line can be realized, the formation efficiency is improved, gas in the battery can be fully discharged, and the performance of the sodium ion battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a formation method and device for sodium-ion batteries and sodium-ion batteries. Background Art

[0002] As one of the most competitive batteries for developing large-scale fixed energy storage systems, sodium-ion batteries have the advantages of similar structural principles to lithium-ion batteries, close technical process routes, low research and production investment, and low material costs. In recent years, with the large-scale application of lithium-ion batteries in the field of electric vehicles, lithium resources have become increasingly scarce, and the price of lithium carbonate, the main raw material of lithium-ion batteries, has increased significantly, resulting in a substantial increase in the production costs of industrial chain enterprises.

[0003] Currently, according to the working principles of sodium-ion batteries and lithium-ion batteries, sodium-ion batteries and lithium-ion batteries can be produced on the same production line. However, in the formation equipment, since some sodium-ion batteries exhibit a certain negative voltage before formation, the positions of the positive and negative electrodes of the battery are defaulted to be incorrect, and the formation equipment cannot operate, so it cannot be effectively compatible with the lithium-ion production line. In addition, the gas generation of sodium-ion batteries mainly occurs in the consumption of moisture in the initial electrode sheet and the formation of the solid electrolyte interface (SEI) film. Secondly, during the first full charge process, gas is generated due to side reactions of the electrolyte on the surface of the positive electrode. If the gas cannot be effectively discharged during the formation process, it will cause battery interface problems, thereby affecting the performance of the battery. Summary of the Invention

[0004] The present invention provides a formation method, device and sodium-ion battery for sodium-ion batteries. By the formation method, device and sodium-ion battery provided by the present invention, compatibility with the lithium-ion battery production line can be achieved, the formation efficiency can be improved, and at the same time, it is beneficial to the full discharge of gas in the battery, thereby improving the performance of sodium-ion batteries.

[0005] To solve the above technical problems, the present invention provides a formation method for sodium-ion batteries, which at least includes:

[0006] Initial voltage detection step: providing an assembled sodium-ion battery, detecting the placement positions of the positive and negative electrodes and the initial voltage of the sodium-ion battery, and determining whether the initial voltage is greater than or equal to zero;

[0007] Pre-charging step: if the initial voltage is less than zero, then pre-charging the sodium-ion battery by a stepped charging method, and within the maximum number of pre-charging times, until the voltage of the pre-charged sodium-ion battery is greater than or equal to zero;

[0008] Formation step: The sodium-ion battery with an initial voltage greater than or equal to zero or the sodium-ion battery with a voltage greater than or equal to zero after pre-charging is formed, and a stepped charging method is used for negative pressure formation.

[0009] In an embodiment of the present invention, the pre-charging includes: the sodium-ion battery is charged at a first current for a first time and then charged at a second current for a second time.

[0010] In an embodiment of the present invention, the first current is 0.01C - 0.02C, and the first time is 10s - 30s;

[0011] And / or, the second current is 0.02C - 0.06C, the second time is 5s - 10s, and the second current is greater than the first current.

[0012] In an embodiment of the present invention, the ion battery is charged at a constant current under the first current and the second current.

[0013] In an embodiment of the present invention, the maximum number of pre-charging times is 3. If the number of pre-charging times is greater than the maximum number of pre-charging times, the sodium-ion battery is removed from the formation device.

[0014] In an embodiment of the present invention, the formation includes:

[0015] After charging at a first preset current for a first preset time, perform a first static time;

[0016] After constant current charging at a second preset for a second preset time, perform a second static time;

[0017] Constant current and constant voltage charge at a third preset current until full charge, the cut-off current is 0.05C, and after charging is completed, perform a third static time;

[0018] Discharge at a fourth preset current to a preset voltage and then perform a fourth static time; and

[0019] Charge at a fifth preset current to a preset state of charge.

[0020] In an embodiment of the present invention, the first preset current is 0.05C - 0.2C, and the first preset time is 10min - 30min;

[0021] And / or, the second preset current is 0.1C - 0.2C, and the second preset time is 1h - 3h;

[0022] And / or, the third preset current is 0.2C - 0.5C;

[0023] And / or, the fourth preset current is 0.33C;

[0024] And / or, the fifth preset current is 0.01C - 1C.

[0025] In an embodiment of the present invention, the sodium-ion battery is subjected to constant current charging or discharging at the first preset current, the second preset current, the fourth preset current, and the fifth preset current.

[0026] In an embodiment of the present invention, during the charging process of the sodium-ion battery at the first preset current, the second preset current, and the third preset current, negative pressure formation is adopted; or, after the sodium-ion battery is charged at the second preset current and the third preset current, exhaust treatment is respectively performed.

[0027] The present invention also provides a sodium-ion battery formation device, which at least includes:

[0028] A battery transmission unit, which includes a first transmission unit, a second transmission unit, a third transmission unit, and a fourth transmission unit;

[0029] A battery position detection unit, which is arranged at the starting position of the first transmission unit;

[0030] A battery voltage detection unit, which is arranged on one side of the battery position detection unit relative to the starting position;

[0031] A position adjustment unit, which includes a first adjustment unit and a second adjustment unit. The first adjustment unit is arranged between the battery position detection unit and the battery voltage detection unit, and the second adjustment unit is arranged on the side of the battery voltage detection unit far from the battery position detection unit; the rear end of the second adjustment unit is the second transmission unit or the third transmission unit;

[0032] A battery pre-charging unit, which is arranged between the third transmission unit and the fourth transmission unit; and

[0033] A formation unit, which is arranged at the rear ends of the second transmission unit and the fourth transmission unit.

[0034] In an embodiment of the present invention, a battery tray is arranged at the rear end of the second adjustment unit. The battery tray includes a first battery tray and a second battery tray. The first battery tray is arranged on the second transmission unit, and the second battery tray is arranged on the third transmission unit.

[0035] In an embodiment of the present invention, the placement directions of the sodium-ion battery in the first battery tray and the second battery tray are the same.

[0036] In an embodiment of the present invention, the battery pre-charging unit has a voltage acquisition mechanism and a rework alarm mechanism.

[0037] The present invention also provides a sodium-ion battery, which is formed by using the above-mentioned forming method or the above-mentioned forming device.

[0038] In summary, the present invention provides a method and a device for forming a sodium-ion battery and a sodium-ion battery, which can adjust the placement position of the sodium-ion battery so that the placement positions of the positive and negative electrodes of the sodium-ion battery match the battery voltage detection unit, and are compatible with the production of sodium-ion batteries in the assembly section and the forming section. The pre-charging of the negative voltage battery pack is carried out synchronously with the positive voltage battery pack, with less modification to the existing production line, easy to implement, and at the same time improving the forming efficiency during the production process. The negative voltage sodium-ion battery is pre-charged to achieve the positive voltage of the sodium-ion battery, and the lithium battery production line does not need to be modified too much, achieving compatibility with the lithium battery production line. At the same time, abnormal sodium-ion batteries can be picked out for manual judgment and processing, and the abnormal batteries can be judged in time, which can speed up the production speed and avoid the forming of faulty batteries, improving the forming efficiency. At the same time, it also prevents multiple pre-charging of sodium-ion batteries, which may lead to the problem that the forming process is not easy to control due to the premature entry of sodium-ion batteries into the forming stage. It is beneficial to fully discharge the gas in the battery, improve the battery interface performance, and thus improve the performance of the sodium-ion battery.

[0039] Of course, it is not necessary to achieve all the above advantages simultaneously when implementing any aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0041] Figure 1 It is a flowchart of the method for forming a sodium-ion battery in an embodiment of the present invention.

[0042] Figure 2 It is a schematic diagram of the device for a sodium-ion battery in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0044] It should be understood that the present invention can be implemented in different forms and should not be construed as limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

[0045] The technical solutions of the present invention will be further described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0046] Please refer to Figure 1 As shown, the present invention provides a method for forming a sodium-ion battery. The forming method at least includes steps S11 - S17.

[0047] Step S11: Provide an assembled sodium-ion battery.

[0048] Step S12: Detect the placement positions of the positive and negative electrodes of the sodium-ion battery and the initial voltage.

[0049] Step S13: Determine whether the initial voltage is ≥0.

[0050] Step S14: If the initial voltage is less than 0, perform pre-charging on the sodium-ion battery using a stepped charging method.

[0051] Step S15: Test the first voltage of the pre-charged sodium-ion battery.

[0052] Step S16: Within the maximum number of pre-charging times, determine whether the first voltage is ≥0. If the first voltage is greater than or equal to 0, proceed to step S17. If the first voltage is less than 0, repeat steps S14 - S15.

[0053] Step S17: Perform negative-pressure forming on the sodium-ion battery with an initial voltage greater than or equal to zero or the ion battery with a voltage greater than or equal to zero after pre-charging.

[0054] Please refer to Figure 1 As shown, in an embodiment of the present invention, in step S11, an assembled sodium-ion battery is provided. Among them, the assembled sodium-ion battery is, for example, a battery after processes such as cell drying, liquid injection, process sealing, and high-temperature infiltration.

[0055] Please refer to Figure 1As shown, in an embodiment of the present invention, in steps S12 - S13, first detect the placement positions of the positive and negative electrodes of the sodium-ion battery. If the placement positions of the positive and negative electrodes of the sodium-ion battery do not meet the requirements, for example, the placement of the positive and negative electrodes is opposite to the detection positions in the battery voltage detection unit, then adjust the position of the sodium-ion battery. Then test the sodium-ion battery or the adjusted sodium-ion battery to obtain the initial voltage of the sodium-ion battery, and judge the magnitude of the initial voltage. In this embodiment, steps S11 - S13 are defined as the initial voltage detection steps.

[0056] Please refer to Figure 1 As shown, in an embodiment of the present invention, if in step S13, it is judged that the initial voltage of the sodium-ion battery is less than 0, group the sodium-ion batteries with negative voltage separately, and then proceed to step S14 to pre-charge the sodium-ion battery using a stepped charging method. In this embodiment, the charging current for pre-charging is, for example, 0.01C - 0.06C, and for example, it is charged in two stages. For example, first charge at the first current for the first time, and then charge at the second current for the second time, where the second current is, for example, greater than the first current, and for example, charge is carried out under the constant current conditions of the first current and the second current. In a specific embodiment of the present invention, the first current is, for example, 0.01C - 0.02C, the first time is, for example, 10s - 30s, the second current is, for example, 0.02C - 0.06C, and the second time is, for example, 5s - 10s. In other embodiments, during the pre-charging process, it may also include charging in three stages or four stages, etc. By pre-charging the sodium-ion battery using a stepped charging method, the negative voltage sodium-ion battery realizes a positive voltage through pre-charging, and the lithium-ion production line does not need to be modified too much, achieving compatibility with the lithium-ion production line. In this application, the unit C is used to represent the battery charge and discharge capacity ratio, and 1C represents the current intensity when the battery is fully discharged in one hour. For example, a battery with a nominal capacity of 2200 mA·h is discharged in one hour at 1C intensity to complete the discharge, and at this time the discharge current is 2200 mA. 0.1C means the discharge is completed in 10 hours, and at this time the discharge current is 220 mA.

[0057] Please refer to Figure 1As shown, in an embodiment of the present invention, after step S14, steps S15 - S16 are performed to test the voltage of the pre-charged sodium-ion battery, denoted as the first voltage, and determine the magnitude of the first voltage based on the maximum number of pre-charging times. If it is determined that the first voltage is less than 0, steps S14 - S15 are repeated to pre-charge the sodium-ion battery again. In this embodiment, the maximum number of pre-charging times for the sodium-ion battery is, for example, 3. That is, within the pre-charging with the maximum number of pre-charging times for the sodium-ion battery, the magnitude of the first voltage is determined. If the voltage is still less than 0 after pre-charging with the maximum number of pre-charging times, the sodium-ion battery is removed from the formation device and judged manually. Timely judgment of abnormal batteries can speed up the production speed and avoid the formation of faulty batteries, improving the formation efficiency. At the same time, it also prevents multiple pre-charging of the sodium-ion battery, which may cause the problem that the formation process is difficult to control due to the sodium-ion battery entering the formation stage prematurely. In this embodiment, steps S14 - S16 are defined as the pre-charging steps.

[0058] Please refer to Figure 1 As shown, in an embodiment of the present invention, in step S13, if it is determined that the initial voltage is greater than or equal to 0, the sodium-ion batteries are grouped and directly step S17 is performed to perform negative-pressure formation on the sodium-ion batteries using a stepped charging method. Or after steps S14 - S16, when the first voltage of the sodium-ion battery is greater than or equal to 0, the pre-charged sodium-ion batteries are grouped and then step S17 is performed. In this embodiment, step S17 is defined as the formation step.

[0059] Please refer to Figure 1 As shown, in an embodiment of the present invention, in step S17, a stepped charging method is used to perform negative-pressure formation on the sodium-ion batteries. In this embodiment, for example, a five-stage method is used for charging and forming. Process step a: After charging at the first preset current for the first preset time, perform a first static time. Process step b: After constant-current charging at the second preset for the second preset time, perform a second static time. Process step c: Constant-current and constant-voltage charge to full charge at the third preset current. The full charge voltage is, for example, 4.0V, and the cut-off current is, for example, 0.05C. After charging ends, perform a third static time. Process step d: Discharge at the fourth preset current to the preset voltage and then perform a fourth static time. Process step e: Charge at the fifth preset current to the preset state of charge (SOC), and the formation ends.

[0060] Please refer to Figure 1As shown, in an embodiment of the present invention, the first preset current is, for example, 0.05C - 0.2C, the first preset time is, for example, 10 min - 30 min, and the first standing time is, for example, 10 min - 30 min. The second preset current is, for example, 0.1C - 0.2C, the second preset time is, for example, 1 h - 3 h, and the second standing time is, for example, 10 min - 30 min. The third preset current is, for example, 0.2C - 0.5C, and the third standing time is, for example, 10 min - 30 min. The preset voltage is, for example, 1.5V, the fourth preset current is, for example, 0.33C, and the fourth standing time is, for example, 20 min - 40 min. The fifth preset current is any current from 0.01C to 1C, and the preset state of charge is, for example, 30% SOC, etc. Among them, in steps a, b, d, and e, for example, it is carried out under a constant current. In other embodiments, a variable current can also be selected for charging or discharging. In this embodiment, the first preset current and the second preset current are less than or equal to 0.2C, and the second preset current is, for example, greater than the first preset current. In the early stage of formation charging, due to the formation of moisture and SEI in the electrode sheet, a small current at the beginning is beneficial to the full discharge of gas in the battery, improving the battery interface performance, and thus improving the performance of the sodium-ion battery.

[0061] Please refer to Figure 1 As shown, in an embodiment of the present invention, during the formation process, if the sodium-ion battery is a hard-shell battery, then in steps a, b, and c, negative-pressure formation is adopted, and the negative-pressure vacuum degree of the hard-shell battery is, for example, -0.7 Mpa to -0.9 Mpa. If the sodium-ion battery is a soft-pack battery, exhaust treatment is carried out respectively after the end of steps b and c, and the exhaust pressure of the soft-pack battery is, for example, 0.3 Mpa - 0.5 Mpa, the vacuum degree is, for example, less than or equal to -0.9 Mpa, and the vacuum time is, for example, 5 s - 10 s. Through stepwise charging, the charging efficiency is improved. Through negative-pressure full charge, it is beneficial to the discharge of gas during the first full charge, which can shorten the formation time and achieve large-scale continuous production.

[0062] Please refer to Figure 1 As shown, in an embodiment of the present invention, after the formation of the sodium-ion battery, the sodium-ion battery is subjected to process sealing, aging, and subsequent manufacturing processes.

[0063] Please refer to Figure 2As shown in the figure, the present invention further provides a formation device for a sodium-ion battery. The formation device 100 includes a battery transmission unit, a battery position detection unit 12, a battery voltage detection unit 13, a position adjustment unit, a battery pre-charging unit 16, and a formation unit 17. Among them, the battery transmission unit includes a first transmission unit 101, a second transmission unit 102, a third transmission unit 103, and a fourth transmission unit 104. The transmission unit is, for example, a conveyor belt, etc., for transmitting the sodium-ion battery before formation. In this embodiment, the first transmission unit 101 and the second transmission unit 102 are, for example, located on the same straight line, the third transmission unit 103 and the fourth transmission unit 104 are, for example, located on the same straight line, and the first transmission unit 101 and the third transmission unit 103 are, for example, arranged in parallel. Through the sodium-ion battery formation device provided by the present invention, by adding a battery voltage detection unit, a position adjustment unit, and a battery pre-charging unit, only a slight modification to the production line is required, and it is easy to achieve the production line compatibility between sodium-ion batteries and lithium-ion batteries.

[0064] Please refer to Figure 2 As shown in the figure, in an embodiment of the present invention, the battery position detection unit 12, the battery voltage detection unit 13, and the position adjustment unit act on the first transmission unit 101, and the battery position detection unit 12 is located at the starting position of the first transmission unit 101. The position adjustment unit includes a first adjustment unit 141 and a second adjustment unit 142. The first adjustment unit 141 is arranged between the battery position detection unit 12 and the battery voltage detection unit 13, and is used to adjust the sodium-ion battery after the battery position detection unit 12. The second adjustment unit 142 is arranged on the side of the battery voltage detection unit 13 away from the battery position detection unit 12. A battery tray is provided at the rear end of the second adjustment unit 142. The battery tray includes a first battery tray 151 and a second battery tray 152. Among them, the first battery tray 151 is arranged on the second transmission unit 102, the rear end of the second transmission unit 102 is the formation unit 17, the second battery tray 152 is arranged on the third transmission unit 103, the rear end of the third transmission unit 103 is the battery pre-charging unit 16, and the fourth transmission unit 104 is arranged between the battery pre-charging unit 16 and the formation unit 17. The second adjustment unit 142 adjusts the sodium-ion battery after the battery voltage detection unit 13 to different transmission units to complete the formation of sodium-ion batteries with different initial voltage characteristics.

[0065] Please refer to Figure 2As shown, in an embodiment of the present invention, the first transmission unit 101 is connected to an assembly unit (not shown in the figure), and the assembled sodium-ion battery enters the first transmission unit 101. The arrow direction in the figure indicates the transmission direction of the battery, and the starting position is defined as the end of the first transmission unit 101 pointing in the transmission direction. At the starting position of the first transmission unit 101, the battery position detection unit 12 detects the positive and negative electrode placement positions of the sodium-ion battery. If the battery position detection unit 12 monitors that the placement positions of the positive and negative electrodes of the sodium-ion battery do not meet the requirements, the first adjustment unit 141 adjusts the position of the sodium-ion battery. In an embodiment of the present invention, the battery position detection unit 12 uses, for example, a Charge Coupled Device (CCD) camera to determine the position, and the first adjustment unit 141 can adjust the position of the battery by 180° according to the information detected by the battery position detection unit 12. Through the battery position detection unit and the first adjustment unit, the placement position of the sodium-ion battery can be adjusted so that the positive and negative electrode positions of the sodium-ion battery match the battery voltage detection unit 13, avoiding the sodium-ion battery due to the mismatch between the positive and negative electrode positions and the battery voltage detection unit, reducing the initial voltage measurement error, and being compatible with the production of sodium-ion batteries in the assembly section and the formation section.

[0066] Please refer to Figure 2 As shown, in an embodiment of the present invention, when the position placement of the sodium-ion battery is adjusted accurately, the sodium-ion battery passes through the battery voltage detection unit 13 to detect the initial voltage of the sodium ions. If the initial voltage of the sodium-ion battery is greater than or equal to 0, the second adjustment unit 142 provided on the side of the battery voltage detection unit 13 away from the first adjustment unit 141 places the sodium-ion battery on the first battery tray 151, and the first battery tray 151 transports the sodium-ion battery to the formation unit 17 through the movement of the second transmission unit 102. If the initial voltage of the sodium-ion battery is less than 0, the second adjustment unit 142 places the sodium-ion battery on the second battery tray 152, and then through the movement of the third transmission unit 103, transports the sodium-ion battery to the battery pre-charging unit 16. Among them, the placement directions of the sodium-ion battery in the first battery tray 151 and the second battery tray 152 are the same. In an embodiment of the present invention, the first adjustment unit 141 and the second adjustment unit 142 are, for example, robotic arms.

[0067] Please refer to Figure 2As shown, in an embodiment of the present invention, when the sodium-ion battery enters the battery pre-charging unit 16, the negatively charged sodium-ion battery is pre-charged step by step. In this embodiment, the battery pre-charging unit 16 has a voltage acquisition mechanism. After the battery pre-charging is completed, the battery voltage will be acquired. If the voltage of the sodium-ion battery is greater than or equal to 0 after pre-charging, the sodium-ion battery is transferred from the battery pre-charging unit 16 to the formation unit 17 through the fourth transmission unit 104. If the voltage of the sodium-ion battery is still less than 0, a new pre-charging process will continue for the sodium-ion battery. In an embodiment of the present invention, the battery pre-charging unit 16 has a rework alarm mechanism. When the pre-charging times of the sodium-ion battery reach the maximum pre-charging times, if the voltage of the sodium-ion battery is still negative, the rework alarm mechanism is triggered, and the abnormal battery is picked out manually for judgment and processing. In this application, the pre-charging of the negative voltage battery pack is synchronized with the positive voltage battery pack, with less modification to the existing production line and improved formation efficiency during the production process at the same time.

[0068] The present invention also provides a sodium-ion battery, including a positive electrode plate, a separator, a negative electrode plate and an electrolyte. The separator is located between the positive electrode plate and the negative electrode plate, and the electrolyte is filled between the positive electrode plate, the separator and the negative electrode plate. Stack the positive electrode plate, the separator and the negative electrode plate in sequence, with the separator in the middle of the positive electrode plate and the negative electrode plate to play an isolation role, and obtain a bare battery core through stacking or winding. The bare battery core is installed in a shell or an aluminum-plastic film, then baked to remove water, injected with the electrolyte and sealed, and after process sealing and high-temperature infiltration, a sodium-ion battery is obtained.

[0069] In an embodiment of the present invention, the positive electrode plate includes a positive electrode material, a positive electrode current collector, an adhesive, a conductive agent, etc. The positive electrode current collector is, for example, a foil material formed after surface treatment of nickel, titanium, aluminum, silver, stainless steel, carbon, etc. In addition to the foil material, the positive electrode current collector can also be used in any one or a combination of multiple forms such as film-like, net-like, porous, foam or non-woven fabric. Among them, the thickness of the positive electrode current collector is, for example, 8μm - 15μm. In this embodiment, the positive electrode current collector is, for example, aluminum foil, and the thickness of the aluminum foil is, for example, 13μm.

[0070] In an embodiment of the present invention, the positive electrode material includes at least one of sodium compounds such as layered metal oxide type, polyanion type or Prussian compound type materials, and is also, for example, selected from NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, Na 2 / 3 Fe1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaMn2O4, NaNi 1 / 2 Mn 3 / 2 O2, at least one or a combination of at least two of NaFePO4, NaMnPO4, NaCoPO4, Na2FePO4F, Na2MnPO4F or Na2CoPO4F. The binder is selected from, for example, any one or more of Polyvinylidene Fluoride (PVDF), Polyamide (PA), Polyacrylonitrile (PAN), Polyacrylate, Polyvinylether, PolymethylMethacrylate (PMMA), Ethylene-Propylene-Diene Terpolymer (EPDM), Polyhexafluoropropylene or Polymerized Styrene Butadiene Rubber (SBR), etc. The conductive agent is selected from, for example, any one or more of carbon black, acetylene black, carbon nanotubes and graphene, etc.

[0071] In an embodiment of the present invention, the positive electrode material is, for example, NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, the binder is selected from, for example, polyvinylidene fluoride, and the conductive agent is selected from, for example, carbon black. After mixing the positive electrode material, carbon black and polyvinylidene fluoride in a mass ratio of, for example, 97:2:1, an organic solvent is added and stirred until the system becomes homogeneous to obtain a positive electrode slurry. Among them, the organic solvent is selected from, for example, N-Methylpyrrolidone (NMP). The positive electrode slurry is uniformly coated on a 13 μm aluminum foil, dried, and then through processes such as rolling and die-cutting, a positive electrode plate is obtained.

[0072] In an embodiment of the present invention, the negative electrode tab includes, for example, a negative electrode current collector, a negative electrode material, a binder, a conductive agent, a thickening agent, etc. The negative electrode current collector is, for example, selected from a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foam copper current collector, an aluminum foil current collector, a stainless steel current collector, etc., and the thickness of the negative electrode current collector is, for example, 8 μm - 15 μm. In this embodiment, the negative electrode current collector is, for example, an aluminum foil, and the thickness of the aluminum foil is, for example, 13 μm. The binder is, for example, selected from any one or more of polyvinylidene fluoride, polyamide, polypropylene, polyacrylate, polyethylene ether, polymethyl methacrylate, polyhexafluoropropylene, or polymerized styrene butadiene rubber (SBR), etc. The conductive agent is, for example, selected from any one or more of conductive carbon black, acetylene black, carbon nanotubes, mesophase carbon microspheres, or graphene, etc. The thickening agent is, for example, selected from any one or more of sodium carboxymethyl cellulose (CMC) or polyacrylic acid, etc.

[0073] In an embodiment of the present invention, the negative electrode material is, for example, selected from non-graphite carbon, and the non-graphite carbon is, for example, soft carbon or hard carbon. In other embodiments, the negative electrode material can be any other known negative electrode active material for sodium ion batteries. Among them, the negative electrode material includes, for example, carbon materials such as non-graphite carbon, graphite, carbon black, and carbon nanotubes, and can also be an element alloyed with sodium. In this embodiment, the negative electrode material is, for example, hard carbon, the binder is selected as polymerized styrene butadiene rubber, the conductive agent is, for example, selected from conductive carbon black, and the thickening agent is, for example, selected from sodium carboxymethyl cellulose. After mixing hard carbon, the binder, the conductive agent, and the thickening agent in a mass ratio of 96:2:1:1 and compressing them onto an aluminum foil with a thickness of 13 μm, a negative electrode tab is obtained through processes such as die cutting.

[0074] In an embodiment of the present invention, the separator is, for example, a polyethylene (PE) membrane, a polypropylene (PP) membrane, a glass fiber membrane, a polyethylene membrane, or a composite membrane, etc., and the thickness of the separator is, for example, 9 μm - 15 μm.

[0075] In an embodiment of the present invention, the electrolyte includes an organic solvent, a sodium salt, and an additive. Among them, the organic solvent includes, for example, any one or a combination of at least two of ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC), or diethyl carbonate (DEC). The sodium salt is, for example, sodium hexafluorophosphate, and the additive includes, for example, at least one of film-forming additives such as 1,3-propanesultone (PS), ethylene sulfate (DTD), fluoroethylene carbonate (FEC), or vinylene carbonate (VC). In this embodiment, the organic solvent is a mixed solution of EC, DEC, and DMC with a volume ratio of 1:1:1. In an argon atmosphere glove box with a water content <10 ppm, fully dried sodium hexafluorophosphate is dissolved in the above mixed solution, and then 1,3-propanesultone and vinylene carbonate are added. After mixing evenly, an electrolyte is obtained, where the concentration of NaPF6 is 1 mol / L, the mass content of 1,3-propanesultone in the electrolyte is 0.1%-3%, and the mass content of vinylene carbonate in the electrolyte is 0.1%-3%.

[0076] Hereinafter, the present invention will be more specifically explained by reference to embodiments, which should not be construed as restrictive. Appropriate modifications can be made within the scope consistent with the gist of the present invention, and all of them fall within the technical scope of the present invention.

[0077] Example 1

[0078] Take NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3O2, polyvinylidene fluoride, and carbon black are mixed in a mass ratio of 97:2:1. Then, NMP is added and stirred until the system becomes homogeneous to obtain the positive electrode paste. The paste is evenly coated on a 13-μm aluminum foil, dried, and then processed through rolling and die-cutting to obtain the positive electrode plate. Hard carbon, styrene-butadiene rubber, conductive carbon black, and sodium carboxymethyl cellulose are mixed in a mass ratio of 96:2:1:1 and then pressed onto a 13-μm aluminum foil. Through processes such as die-cutting, the negative electrode plate is obtained. A mixed solution of EC, DEC, and DMC with a volume ratio of 1:1:1 is prepared. In an argon atmosphere glove box with a water content of <10 ppm, fully dried sodium hexafluorophosphate is dissolved in the above mixed solution, and then 1,3-propane sultone and vinylene carbonate are added. After mixing evenly, the electrolyte is obtained, where the concentration of NaPF6 is 1 mol / L, the mass content of 1,3-propane sultone in the electrolyte is 1%, and the mass content of vinylene carbonate in the electrolyte is 0.5%.

[0079] The positive electrode plate, polyethylene separator, and negative electrode plate are assembled into a 20-Ah bare battery cell in a Z-shaped stacking manner. Subsequently, through processes such as hot pressing, welding, and casing, a square battery cell is prepared. After drying the battery cell, it is filled with electrolyte, hermetically sealed, and subjected to high-temperature soaking to obtain a hard-shell sodium-ion battery.

[0080] The sodium-ion battery after high-temperature soaking is transported to the battery position detection unit 12 by the first transport unit 101 to detect whether the positive and negative electrode placement positions are correct. If the positions are correct, it enters the battery voltage detection unit 13 for voltage detection. If placed reversely, the position is adjusted by the first adjustment unit 141. After the battery voltage detection unit 13 collects the voltage, if the battery voltage is positive, it is transported by the second adjustment unit 142 to the first battery tray 151 for tray assembly, and then enters the formation unit 17 through the second transport unit 102. If the collected voltage is negative, it is transported by the second adjustment unit 142 to the second battery tray 152 for tray assembly, and then enters the battery pre-charging unit 16 through the third transport unit 103 for battery pre-charging. The pre-charging is carried out according to the pre-charging process steps. After the pre-charging is completed, the qualified batteries are transferred to the formation unit 17 by the fourth transport unit 104.

[0081] Pre-charging process steps: The sodium-ion battery is pre-charged with a current of 0.02C for 10 s, then switched to 0.04C and continued to be charged for 8 s. After the charging is completed, it is left standing for 30 s, and then the battery voltage is collected by the battery pre-charging unit 16. If all the battery voltages are positive, it enters the formation unit 17 through the fourth transport unit 104. If there are negative battery voltages, the pre-charging process steps are continued until all the battery voltages are positive. If there are still negative-voltage batteries after repeating 2 times, the battery pre-charging unit 16 issues an alarm, and the abnormal batteries are manually picked out for judgment and processing.

[0082] Formation: The batteries that have gone through the pre-charging step or not are grouped and formed. Step a: Charge with a current of 0.05C for 30 minutes, and then let it stand for 10 minutes after charging. Step b: Continue to charge with 0.1C for 3 hours, and then let it stand for 10 minutes after charging. Step c: Charge with constant current and constant voltage of 0.33C until 4.0V, with a cut-off current of 0.05C, and then let it stand for 10 minutes after charging. Step d: Discharge with a current of 0.33C to 1.5V and then let it stand for 30 minutes. Step e: Charge with 0.3C for 1 hour until 30% SOC and then the formation ends. During steps a, b, and c, the formation is carried out under negative pressure, and the negative pressure vacuum degree is -0.75 Mpa.

[0083] After the formation ends, the batteries are subjected to process sealing, aging, and subsequent manufacturing processes.

[0084] Example 2

[0085] The difference from Example 1 is that the pre-charging step and the charge and discharge steps in the formation process are adjusted as follows.

[0086] Pre-charging step: Pre-charge the battery with a current of 0.01C for 20 seconds, and then switch to 0.06C to continue charging for 5 seconds.

[0087] Formation: Step a: Charge with a current of 0.1C for 15 minutes, and then let it stand for 10 minutes after charging. Step b: Continue to charge with 0.15C for 2 hours, and then let it stand for 10 minutes after charging. Step c: Charge with constant current and constant voltage of 0.33C until 4.0V, with a cut-off current of 0.05C, and then let it stand for 10 minutes after charging. Step d: Discharge with a current of 0.5C to 1.5V and then let it stand for 30 minutes. Step e: Charge with 0.2C for 1.5 hours until 30% SOC.

[0088] The remaining steps are the same as those in Example 1.

[0089] Example 3

[0090] The difference from Example 1 is that the pre-charging step and the charge and discharge steps in the formation process are adjusted as follows.

[0091] Pre-charging step: Pre-charge the battery with a current of 0.15C for 15 seconds, and then switch to 0.04C to continue charging for 7 seconds.

[0092] Formation: Process step a: Charge at a current of 0.15C for 10 min, and let it stand for 10 min after charging. Process step b: Continue charging at 0.2C for 1.5 h, and let it stand for 30 min after charging. Process step c: Charge at constant current and constant voltage of 0.5C until 4.0V, with a cut-off current of 0.05C, and let it stand for 30 min after charging. Process step d: Discharge at a current of 0.5C to 1.5V and then let it stand for 30 min. Process step e: Charge at 0.1C for 3 h to 30% SOC.

[0093] The remaining steps are the same as those in Embodiment 1.

[0094] In summary, the present invention provides a formation method, device and sodium-ion battery for sodium-ion batteries. Through the battery position detection unit and the first adjustment unit, the placement position of the sodium-ion battery can be adjusted, so that the positions of the positive and negative electrodes of the sodium-ion battery match the battery voltage detection unit, avoiding the problem that the initial voltage measurement error is increased due to the mismatch between the positions of the positive and negative electrodes of the sodium-ion battery and the battery voltage detection unit, and being compatible with the production of sodium-ion batteries in the assembly section and the formation section. By detecting and judging the initial voltage, the pre-charging of the negative voltage battery pack is carried out synchronously with the positive voltage battery pack, with less modification to the existing production line, being easy to implement, and improving the formation efficiency during the production process at the same time. The sodium-ion battery is pre-charged by a stepped charging method, and the negative voltage sodium-ion battery is pre-charged to achieve a positive voltage of the sodium-ion battery, without much modification to the lithium battery production line, and being compatible with the lithium battery production line. At the same time, through the rework alarm mechanism, abnormal sodium-ion batteries are picked out and judged and processed manually, judging the abnormal batteries in time, which can speed up the production speed, avoid the formation of faulty batteries at the same time, and improve the formation efficiency. It also prevents multiple pre-charging of sodium-ion batteries, which may cause the problem that the formation process is not easy to control due to the sodium-ion battery entering the formation stage in advance. Through stepped formation, and a small current at the initial stage of charging is beneficial to the full discharge of gas in the battery, improving the battery interface performance, and thus improving the performance of the sodium-ion battery.

[0095] The above description is only the preferred embodiments of the present application and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept, such as the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present application. Except for the technical features described in the specification, the remaining technical features are known to those skilled in the art. To highlight the innovative features of the present invention, the remaining technical features are not described in detail herein.

Claims

1. A method for forming a sodium-ion battery, characterized in that, At least include the following steps: Initial voltage detection step: Provide the assembled sodium-ion battery, detect the placement positions of the positive and negative electrodes of the sodium-ion battery and the initial voltage, and determine whether the initial voltage is greater than or equal to zero; Pre-charging step: If the initial voltage is less than zero, pre-charge the sodium-ion battery in a stepped charging manner, and within the maximum number of pre-charging times, until the voltage of the pre-charged sodium-ion battery is greater than or equal to zero; Formation step: Perform formation on the sodium-ion battery with an initial voltage greater than or equal to zero or the sodium-ion battery with a voltage greater than or equal to zero after pre-charging, and perform negative-pressure formation in a stepped charging manner.

2. The formation method of the sodium ion battery according to claim 1, wherein, The pre-charging includes: The sodium-ion battery is charged at a first current for a first time, and then charged at a second current for a second time.

3. The formation method of the sodium-ion battery according to claim 2, wherein, The first current is 0.01C - 0.02C, and the first time is 10s - 30s; And / or, the second current is 0.02C - 0.06C, the second time is 5s - 10s, and the second current is greater than the first current.

4. The formation method of the sodium-ion battery according to claim 2, wherein, The ion battery is charged at a constant current at the first current and the second current.

5. The formation method of the sodium-ion battery according to claim 1, characterized in that, The maximum number of pre-charging times is 3. If the number of pre-charging times is greater than the maximum number of pre-charging times, the sodium-ion battery is picked out from the formation device.

6. The formation method of the sodium-ion battery according to claim 1, wherein The formation includes: After charging at a first preset current for a first preset time, perform a first static time; After constant current charging at a second preset for a second preset time, perform a second static time; Charge at a third preset current with constant current and constant voltage until full charge, the cut-off current is 0.05C, and perform a third static time after charging ends; Discharge at a fourth preset current to a preset voltage and then perform a fourth static time; and Charge at a fifth preset current to a preset state of charge.

7. The formation method of the sodium-ion battery according to claim 6, characterized in that, The first preset current is 0.05C - 0.2C, and the first preset time is 10min - 30min; And / or, the second preset current is 0.1C - 0.2C, and the second preset time is 1h - 3h; And / or, the third preset current is 0.2C - 0.5C; And / or, the fourth preset current is 0.33C; And / or, the fifth preset current is 0.01C - 1C.

8. The formation method of the sodium ion battery according to claim 6, characterized in that, The sodium-ion battery is charged or discharged at a constant current at the first preset current, the second preset current, the fourth preset current, and the fifth preset current.

9. The formation method of the sodium-ion battery according to claim 6, wherein, During the charging process of the sodium-ion battery at the first preset current, the second preset current, and the third preset current, negative-pressure formation is adopted; Or, after charging the sodium-ion battery at the second preset current and the third preset current, exhaust treatment is performed respectively.

10. A sodium-ion battery formation device, characterized in that, At least include: A battery transmission unit, which includes a first transmission unit, a second transmission unit, a third transmission unit, and a fourth transmission unit; A battery position detection unit, which is arranged at the starting position of the first transmission unit; A battery voltage detection unit, which is arranged on one side of the battery position detection unit relative to the starting position; A position adjustment unit, which includes a first adjustment unit and a second adjustment unit. The first adjustment unit is disposed between the battery position detection unit and the battery voltage detection unit, and the second adjustment unit is disposed on a side of the battery voltage detection unit away from the battery position detection unit; the rear end of the second adjustment unit is the second transmission unit or the third transmission unit; A battery pre-charging unit, which is disposed between the third transmission unit and the fourth transmission unit; and A formation unit, which is disposed at the rear ends of the second transmission unit and the fourth transmission unit.

11. The formation device for sodium-ion battery according to claim 10, characterized in that, A battery tray is provided at the rear end of the second adjustment unit. The battery tray includes a first battery tray and a second battery tray. The first battery tray is disposed on the second transmission unit, and the second battery tray is disposed on the third transmission unit.

12. The formation device for a sodium-ion battery according to claim 11, characterized in that, The sodium-ion batteries are placed in the same direction in the first battery tray and the second battery tray.

13. The formation device for a sodium-ion battery according to claim 10, characterized in that, The battery pre-charging unit has a voltage acquisition mechanism and a rework alarm mechanism.

14. A sodium-ion battery, characterized in that, Performing formation by using the formation method according to any one of claims 1-9, or performing formation by using the formation device according to any one of claims 10-13.

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