Sodium ion battery monomer, battery device and power utilization device

Abstract

The embodiment of the invention discloses a sodium ion battery monomer, a battery device and a power utilization device. Each sodium ion battery monomer comprises an electrolyte, a negative pole piece and a positive pole piece; the positive pole piece comprises a positive current collector and a positive film layer; the positive electrode film layer comprises phosphate, the phosphate comprises ferric sodium pyrophosphate and ferric sodium phosphate, and the mass ratio P of the ferric sodium phosphate to the ferric sodium pyrophosphate is greater than or equal to 0.2% and less than or equal to 5%; the conductivity C of the electrolyte at 25 + / -1 DEG C is greater than or equal to 7mS / cm and less than or equal to 20mS / cm; the electrolyte comprises sodium ion salt, the molecular weight N of anions of the sodium ion salt is larger than or equal to 150 and smaller than or equal to 300, and the mass ratio M of the sodium ion salt in the electrolyte is larger than or equal to 10% and smaller than or equal to 30%. According to the sodium ion battery monomer provided by the embodiment of the invention, the cycle performance and the storage life can be considered while the high-rate discharge performance requirement is met.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a sodium-ion battery cell, a battery device, and an electrical device. Background Technology

[0002] In recent years, with the gradual development and application of lithium-ion batteries from portable electronic devices to high-power electric vehicles, large-scale energy storage power stations, and smart grids, the demand for metallic lithium has been increasing across various industries. However, with the depletion of metallic lithium reserves and the increasing difficulty of mining, current metallic lithium resources can no longer meet the needs of the lithium battery industry. Sodium, which belongs to the same group as lithium, has similar chemical properties to lithium and is abundant. Therefore, sodium-ion batteries, which operate on a similar principle to lithium-ion batteries, are currently being developed, with the expectation that they will serve as an important supplement to lithium-ion batteries in large-scale energy storage applications.

[0003] Therefore, how to enable sodium-ion batteries to meet the requirements of high-rate discharge performance while also taking into account cycle performance and storage life is an urgent problem to be solved. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a sodium-ion battery cell, battery device and power device that can meet the requirements of high-rate discharge performance while taking into account cycle performance and storage life.

[0005] To achieve the above objectives, this application provides a sodium-ion battery cell, a battery device, and an electrical device.

[0006] The first aspect of this application provides a sodium-ion battery cell, including an electrolyte, a negative electrode, and a positive electrode; the positive electrode includes a positive current collector and a positive electrode film, the positive electrode film being located on at least one side of the positive current collector, and the thickness L of the positive electrode film on one side of the positive current collector satisfies: 50μm≤L≤125μm; the positive electrode film layer includes phosphate, the general formula of which is... Na a Fe b M c (PON d ) e (P2O7) f Phosphate salts include sodium ferric pyrophosphate and sodium ferric phosphate. The mass ratio P of sodium ferric phosphate to sodium ferric pyrophosphate satisfies: 0.2% ≤ P ≤ 5%. The conductivity C of the electrolyte at 25±1℃ satisfies: 7 mS / cm ≤ C ≤ 20 mS / cm. The electrolyte includes sodium ion salts. The molecular weight N of the anion of the sodium ion salt satisfies: 150 ≤ N ≤ 300. The mass percentage M of the sodium ion salt in the electrolyte satisfies: 10% ≤ M ≤ 30%.

[0007] In the embodiments of this application, the heterostructure formed by sodium iron pyrophosphate and sodium iron phosphate, along with the positive electrode film layer with a thickness within the aforementioned range, can improve the sodium ion diffusion capability within the positive electrode sheet. This results in a higher sodium ion transport rate and electronic conductivity within the positive electrode sheet, thereby improving the high-rate discharge performance of the sodium-ion battery cell. Furthermore, using a high-conductivity electrolyte in conjunction with the positive electrode active material phosphate can improve charge distribution uniformity, enhance ion conduction, and improve the cycle performance of the sodium-ion battery cell. Simultaneously, the sodium ion salt in the electrolyte includes anions with relatively large molecular weights. Generally, the larger the molecular weight of the anion salt compound, the larger the volume of the anion. Furthermore, the larger the size of the anion, the greater the steric hindrance of the salt compound and the weaker the interaction force between the cation and anion. The smaller the lattice energy of the salt, the easier it is for it to be dissociated by the solvent. This not only further enhances the sodium ion migration kinetics, but the sodium ion salt can also enter the electrolyte solvation structure, increasing the stability of the electrode / electrolyte interface film, thereby further improving the cycle performance and storage life of the sodium-ion battery cell. In summary, sodium-ion battery cells can meet the requirements of high-rate discharge performance while also taking into account cycle performance and storage life.

[0008] In some implementations, M satisfies: 13% ≤ M ≤ 23%.

[0009] In the embodiments of this application, the mass percentage of sodium ion salt in the electrolyte is within the above-mentioned range, and the sodium ion battery cell can have higher discharge power performance, cycle performance and storage life.

[0010] In some implementations, P satisfies: 0.2% ≤ P ≤ 2%.

[0011] In the embodiments of this application, the mass ratio of sodium iron phosphate to sodium iron pyrophosphate is within the above-mentioned range, and the sodium-ion battery cell can have higher discharge power performance while taking into account high-temperature storage life.

[0012] In some implementations, L satisfies: 60μm≤L≤100μm.

[0013] In the embodiments of this application, the thickness of the positive electrode film is within the above-mentioned range, and the sodium-ion battery cell can have higher discharge power performance.

[0014] In some embodiments, the Dv50 of the phosphate satisfies: 1 μm ≤ Dv50 ≤ 18 μm. Alternatively, the Dv50 satisfies: 7 μm ≤ Dv50 ≤ 11 μm.

[0015] In the embodiments of this application, the particle size of the phosphate is within the above-mentioned range, which can improve the power performance of a single sodium-ion battery cell while taking into account the life performance of the sodium-ion battery.

[0016] In some embodiments, the sodium ion salt comprises sodium bis(fluorosulfonyl)imide and / or sodium bis(fluorosulfonyl)imide. (Trifluoromethylsulfonyl)imide sodium.

[0017] In some embodiments, the sodium-ion battery cell further includes: a housing, which is a hollow structure with an opening, and the electrolyte, negative electrode, and positive electrode are contained within the housing; and a top cover that closes the opening.

[0018] A second aspect of this application provides a battery device including a sodium-ion battery cell from the first aspect of this application.

[0019] A third aspect of this application provides an electrical device comprising a sodium-ion battery cell of the first aspect of this application and / or a battery device of the second aspect of this application.

[0020] In some embodiments, the sodium-ion battery cell or battery device is powered by the start-stop power supply of the electrical device. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a sodium-ion battery cell according to one embodiment of this application.

[0022] Figure 2 This is a schematic diagram of a sodium-ion battery cell according to one embodiment of this application.

[0023] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application.

[0024] Figure 4 This is a schematic diagram of a battery device according to one embodiment of this application.

[0025] Figure 5 yes Figure 4 An exploded view of a battery device according to an embodiment of this application is shown.

[0026] Figure 6 This is a schematic diagram of an electrical device in which a single battery cell is used as a power source according to one embodiment of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1 Battery assembly; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Sodium-ion battery cell; 51 Negative electrode; 52 Separator; 53 Positive electrode. Detailed Implementation

[0029] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the electrode plates, battery cells, battery modules, battery devices, and power-consuming devices of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0030] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0032] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0033] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0034] In recent years, with the gradual development and application of lithium-ion batteries from portable electronic devices to high-power electric vehicles, large-scale energy storage power stations, and smart grids, the demand for metallic lithium has been increasing across various industries. However, with the depletion of metallic lithium reserves and the increasing difficulty of mining, current metallic lithium resources can no longer meet the needs of the lithium battery industry. Sodium, which belongs to the same group as lithium, has similar chemical properties to lithium and is abundant. Therefore, sodium-ion batteries, which operate on a similar principle to lithium-ion batteries, are currently being developed, with the expectation that they will serve as an important supplement to lithium-ion batteries in large-scale energy storage applications.

[0035] During their research on the performance of sodium-ion batteries, the applicant discovered that sodium-ion battery cells exhibit better low-temperature discharge performance when phosphate is used as the positive electrode active material. However, under high-power discharge scenarios, the cycle life performance of phosphate-treated sodium-ion battery cells may deteriorate. Related technologies can address cycle life performance requirements by increasing the particle size of phosphate; however, this approach may affect the high-rate discharge performance of sodium-ion battery cells.

[0036] In view of this, embodiments of this application provide a sodium-ion battery cell, including an electrolyte, a negative electrode, and a positive electrode; the positive electrode includes a positive current collector and a positive electrode film, the positive electrode film being located on at least one side of the positive current collector, and the thickness L of the positive electrode film on one side of the positive current collector satisfies: 50μm≤L≤125μm; the positive electrode film includes phosphate, the general formula of which is... Na a Fe b M c (PON d ) e (P2O7) fThe phosphates include sodium iron pyrophosphate and sodium iron phosphate, with the mass ratio P of sodium iron phosphate to sodium iron pyrophosphate satisfying: 0.2% ≤ P ≤ 5%; the electrolyte conductivity C at 25±1℃ satisfies: 7 mS / cm ≤ C ≤ 20 mS / cm; the electrolyte includes sodium ion salt, with the molecular weight N of the sodium ion salt anion satisfying: 140 ≤ N ≤ 300, and the mass percentage M of the sodium ion salt in the electrolyte satisfying: 10% ≤ M ≤ 30%. The sodium-ion battery cell provided in this application embodiment can meet the requirements of high-rate discharge performance while also taking into account cycle performance and storage life.

[0037] The sodium-ion battery cell, battery module, battery, and power-consuming device of this application are described below with appropriate reference to the accompanying drawings.

[0038] Typically, a sodium-ion battery cell includes a positive electrode, a negative electrode, an electrolyte, and a separator. 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.

[0039] Sodium-ion battery cell

[0040] In one embodiment of this application, a sodium-ion battery cell 5 is proposed. Figure 1 This is a schematic diagram of the structure of a sodium-ion battery cell according to an embodiment of this application. The sodium-ion battery cell 5 includes a negative electrode 51, a separator 52, a positive electrode 53, and an electrolyte.

[0041] The positive electrode 53 includes a positive current collector and a positive electrode film layer. The positive electrode film layer is located on at least one side of the positive current collector, and the thickness L of the positive electrode film layer on one side of the positive current collector satisfies: 50μm≤L≤125μm; the positive electrode film layer includes phosphate, the general formula of which is... Na a Fe b M c (PON d ) e (P2O7) f Phosphates include sodium ferric pyrophosphate and sodium ferric phosphate, and the mass ratio P of sodium ferric phosphate to sodium ferric pyrophosphate satisfies: 0.2% ≤ P ≤ 5%.

[0042] Optionally, 60μm≤L≤100μm.

[0043] Optionally, 0.2% ≤ P ≤ 2%.

[0044] L can be 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, or any value within the above range. P can be 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, or any value within the above range.

[0045] Specifically, the positive electrode film layer is disposed on at least one side of the surface of the positive electrode current collector. As an example, the positive electrode current collector may have two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0046] Specifically, the mass ratio of sodium iron phosphate to sodium iron pyrophosphate can also be referred to as the ratio of the mass percentage of sodium iron phosphate in phosphate to the mass percentage of sodium iron pyrophosphate in phosphate.

[0047] In the design of the positive electrode, the phosphate includes sodium iron pyrophosphate and sodium iron phosphate. Sodium iron phosphate has a lower sodium ion migration potential barrier, and sodium iron pyrophosphate and sodium iron phosphate can form a heterostructure, thereby improving the sodium ion diffusion capacity within the positive electrode active material, reducing charge transfer impedance, and improving the power performance of the sodium-ion battery cell. Furthermore, sodium iron phosphate also has good thermal stability, which is beneficial for improving the high-temperature storage life of the cell. In addition, while maintaining the energy density of the battery cell, a thinner positive electrode film can increase the sodium ion transport rate within the positive electrode, thereby further improving the power performance of the sodium-ion battery cell.

[0048] The conductivity C of the electrolyte at 25±1℃ satisfies: 7 mS / cm ≤ C ≤ 20 mS / cm. The electrolyte includes sodium ion salts, the molecular weight N of the sodium ion salt anion satisfies: 150 ≤ N ≤ 300, and the mass percentage M of the sodium ion salt in the electrolyte satisfies: 10% ≤ M ≤ 30%.

[0049] Optionally, 13% ≤ M ≤ 23%.

[0050] C can be 7 mS / cm, 10 mS / cm, 15 mS / cm, 20 mS / cm, or any value within the above range. N can be 150, 180, 220, 260, 300, or any value within the above range. M can be 10%, 13%, 14%, 15%, 17%, 20%, 23%, 25%, 30%, or any value within the above range.

[0051] In electrolyte design, using a high-conductivity electrolyte in conjunction with phosphate, the positive electrode active material, allows for interaction with the phosphate positive electrode surface, improving charge distribution uniformity and thus enhancing ion conduction and cycle performance of sodium-ion battery cells. Simultaneously, the sodium ion salt in the electrolyte contains relatively large molecular weight anions; generally, the larger the molecular weight of the anion salt compound, the larger the anion volume. Furthermore, larger anion sizes lead to greater steric hindrance in the salt compound and weaker interactions between cations and anions, resulting in lower lattice energy and easier dissociation by the electrolyte solvent. This not only further enhances sodium ion migration kinetics but also allows the sodium ion salt to enter the electrolyte solvation structure, increasing the stability of the electrode / electrolyte interface film, thereby further improving the cycle performance and storage life of sodium-ion battery cells.

[0052] In the embodiments of this application, the heterostructure formed by sodium iron pyrophosphate and sodium iron phosphate, along with the positive electrode film layer with a thickness within the aforementioned range, can improve the sodium ion diffusion capability within the positive electrode sheet. This results in a higher sodium ion transport rate and electronic conductivity within the positive electrode sheet, thereby improving the high-rate discharge performance of the sodium-ion battery cell. Furthermore, using a high-conductivity electrolyte in conjunction with the positive electrode active material phosphate can improve charge distribution uniformity, enhance ion conduction, and improve the cycle performance of the sodium-ion battery cell. Simultaneously, the sodium ion salt in the electrolyte includes anions with relatively large molecular weights. Generally, the larger the molecular weight of the anion salt compound, the larger the volume of the anion. Furthermore, the larger the size of the anion, the greater the steric hindrance of the salt compound and the weaker the interaction force between the cation and anion, resulting in a smaller lattice energy of the salt, making it easier to be dissociated by the electrolyte solvent. This not only further enhances the sodium ion migration kinetics, but the sodium ion salt can also enter the electrolyte solvation structure, increasing the stability of the electrode / electrolyte interface film, thereby further improving the cycle performance and storage life of the sodium-ion battery cell. In summary, sodium-ion battery cells can meet the requirements of high-rate discharge performance while also taking into account cycle performance and storage life.

[0053] The conductivity of the electrolyte can be obtained by testing the electrolyte using a conductivity meter, referring to the method in GB / T 1.1-2009.

[0054] The sodium ion salt content and the molecular weight of the anions in the above-mentioned electrolytes can be obtained by testing and analyzing the anions in the electrolytes using ion chromatography analysis methods, referring to the General Rules for Ion Chromatography Analysis (JY / T 020-1996) in the General Rules for Analytical Instrumentation of Modern Instruments.

[0055] In some embodiments, the Dv50 of the phosphate satisfies: 1 μm ≤ Dv50 ≤ 18 μm. Alternatively, the Dv50 satisfies: 7 μm ≤ Dv50 ≤ 11 μm.

[0056] Dv50 can be 1μm, 5μm, 7μm, 10μm, 11μm, 15μm, 18μm or any value within the above range.

[0057] Larger phosphate particles can improve the cycle performance and storage performance of sodium-ion battery cells. However, excessively large cathode active material particle size may also increase the sodium-ion transport path, potentially reducing the discharge power performance of sodium-ion battery cells.

[0058] In the embodiments of this application, the particle size of the phosphate is within the above-mentioned range, which can improve the power performance of a single sodium-ion battery cell while taking into account the life performance of the sodium-ion battery.

[0059] In some embodiments, the sodium ion salt includes sodium bis(fluorosulfonyl)imide and / or sodium bis(trifluoromethylsulfonyl)imide.

[0060] Specifically, the sodium ion salt in the electrolyte may include only sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide, or both sodium bis(fluorosulfonyl)imide and sodium bis(trifluoromethylsulfonyl)imide.

[0061] In some embodiments, the electrolyte also includes sodium hexafluorophosphate.

[0062] Specifically, the electrolyte may also include both sodium ion salt and sodium hexafluorophosphate as described in the above embodiments.

[0063] In some embodiments, the sodium-ion battery cell 5 further includes: a housing, which is a hollow structure with an opening, and the electrolyte, negative electrode 51 and positive electrode 53 are housed within the housing; and a top cover that closes the opening.

[0064] [Positive electrode plate]

[0065] The positive electrode includes a positive current collector and a positive electrode film layer disposed on the positive current collector. The positive electrode can be the aforementioned positive electrode 53.

[0066] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0067] In some embodiments, the positive electrode film layer may employ positive electrode active materials known in the art for use in batteries. As an example, the positive electrode active material may include at least one of the following: sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more.

[0068] In some embodiments, the transition metal in the sodium transition metal oxide can be At least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Sodium transition metal oxides, for example, are Na. x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0 < x ≤ 1.

[0069] In some embodiments, the polyanionic compound may be a sodium ion, a transition metal ion, or a tetrahedral (YO4) compound. n- A class of compounds with anionic units. Transition metals can be... At least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si; n represents (YO4). n- The valence state. Polyanionic compounds can also have sodium ions, transition metal ions, or tetrahedral (YO4) ions. n- A class of compounds containing anionic units and halide anions. Transition metals may include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y may include at least one of P, S, and Si, where n represents (YO4). n- The valence state; halogens can include at least one of F, Cl, and Br. Polyanionic compounds can also have sodium ions, tetrahedral (YO4) valence states. n- Anionic unit, polyhedral unit (ZO) y ) m+ And a class of compounds with optional halide anions. Y can include at least one of P, S, and Si, and n represents (YO4). n- The valence state; Z represents a transition metal, including metals that can be... At least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, where m represents (ZO) y ) m+The valence state; halogens can include at least one of F, Cl, and Br. Examples of polyanionic compounds include NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2 (P2O7), NaM'PO4F (M' includes one or more of V, Fe, Mn, and Ni), and Na3(VO4) y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0070] In some embodiments, Prussian blue compounds may contain sodium ions, transition metal ions, and cyanide ions (CN). - A class of compounds. Transition metals include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Prussian blue compounds are, for example, Na. a Me b Me' c (CN)6, wherein Me and Me' each independently include at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0071] In some embodiments, the positive electrode active material layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0072] In some embodiments, the positive electrode active material layer may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0073] In some embodiments, the positive electrode sheet can be prepared by dispersing the positive active material, conductive agent, binder and any other components in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0074] [Negative electrode plate]

[0075] The negative electrode sheet includes a negative current collector and a layer of negative active material disposed on the negative current collector.

[0076] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0077] In some embodiments, the negative electrode active material layer includes a negative electrode active material. The negative electrode active material may be any negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, and tin-based materials, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0078] In some embodiments, the negative electrode active material layer may optionally include a binder. As an example, the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0079] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0080] In some embodiments, the negative electrode active material layer may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0081] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material layer, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0082] Electrolyte

[0083] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte may include fluoroethylene carbonate (FEC) and the lithium-containing compound described in any of the above embodiments. The electrolyte can be the electrolyte found in the above embodiments.

[0084] In some embodiments, the electrolyte includes an organic solvent, a sodium electrolyte salt, and optional additives. The types of organic solvent, sodium electrolyte salt, and additives are not specifically limited and can be selected according to requirements.

[0085] In some embodiments, as examples, the electrolyte salt includes, but is not limited to, at least one of sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide. One of the above electrolyte salts may be used alone, or two or more may be used simultaneously.

[0086] In some embodiments, as examples, the organic solvent includes, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE). One of the above organic solvents may be used alone, or two or more may be used simultaneously. Optionally, two or more of the above organic solvents may be used simultaneously.

[0087] In some embodiments, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0088] In some embodiments, as examples, the additives include, but are not limited to, at least one of fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), vinyl sulfate (DTD), propylene sulfate, vinyl sulfite (ES), 1,3-propanesulfonate lactone (PS), 1,3-propenesulfonate lactone (PST), sulfonate cyclic quaternary ammonium salts, succinic anhydride, succinic anhydride (SN), adiponitrile (AND), tris(trimethylsilane) phosphate (TMSP), and tris(trimethylsilane) borate (TMSB).

[0089] The electrolyte can be prepared according to conventional methods in the art. For example, an organic solvent, a sodium electrolyte salt, and optional additives can be mixed evenly to obtain an electrolyte. There are no particular restrictions on the order of addition of the materials; for example, the sodium electrolyte salt and optional additives can be added to the organic solvent and mixed evenly to obtain an electrolyte; or, the sodium electrolyte salt can be added to the organic solvent first, and then the optional additives can be added to the organic solvent and mixed evenly to obtain an electrolyte.

[0090] [Isolation membrane]

[0091] In some embodiments, the battery cell also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0092] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0093] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0094] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0095] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0096] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 2 The sodium-ion battery cell 5 is an example. The sodium-ion battery cell 5 may include a housing. A positive electrode, a negative electrode, and a separator can be formed into an electrode assembly using a winding or stacking process. The electrode assembly is encapsulated within the housing. The sodium-ion battery cell 5 may contain one or more electrode assemblies, which can be selected by those skilled in the art according to specific practical needs.

[0097] In some embodiments, sodium-ion battery cells can be assembled into battery modules, and the number of sodium-ion battery cells contained in a battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0098] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple sodium-ion battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple sodium-ion battery cells 5 can be fixed in place using fasteners.

[0099] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple sodium-ion battery cells 5 are received.

[0100] In some embodiments, the battery modules described above can also be assembled into a battery device. The number of battery modules contained in the battery device can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery device.

[0101] Figure 4 and Figure 5 This is battery device 1 as an example. (See reference...) Figure 4 and Figure 5 The battery device 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper box 2 and a lower box 3, the upper box 2 covering the lower box 3 to form a closed space for accommodating the battery modules 4 and / or sodium-ion battery cells 5. The multiple battery modules 4 may be arranged in any manner within the battery box.

[0102] In addition, this application also provides an electrical device, which includes at least one of the battery cell, battery module, or battery device provided in this application. The battery cell, battery module, or battery device can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), 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.), electric trains, ships and satellites, energy storage systems, etc.

[0103] As the electrical device, a single battery cell, a battery module, or a battery can be selected according to its usage requirements.

[0104] Figure 6This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of individual battery cells, a battery device or battery module can be used.

[0105] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0106] In some embodiments, the sodium-ion battery cell or battery device is powered by the start-stop power supply of the electrical device.

[0107] Specifically, the power supply for starting and stopping electrical devices may include the sodium-ion battery cells described in the above embodiments and / or battery devices containing the sodium-ion battery cells described in the above embodiments.

[0108] [Example]

[0109] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0110] Example 1

[0111] (1) Preparation of negative electrode sheet

[0112] Hard carbon (negative electrode active material), acetylene black (conductive agent), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethyl cellulose (CMC-Na) (thickener) were mixed and homogenized in a weight ratio of 90:4:4:2 to obtain a negative electrode film slurry. This negative electrode active material slurry was then coated onto a negative electrode current collector and dried in an oven at 100°C, controlling the water content to be less than 150 ppm, to obtain the negative electrode sheet.

[0113] (2) Preparation of positive electrode sheet

[0114] The positive electrode active material (sodium phosphate composite material, wherein the Dv50 of the sodium phosphate composite material is 9 μm, and the sodium phosphate composite material includes NaFePO4 and Na4Fe3(PO4)2P2O7, with a mass ratio of NaFePO4 to Na4Fe3(PO4)2P2O7 of 2%), conductive agent acetylene black, and binder polyvinylidene fluoride were mixed in a solvent N-methylpyrrolidone (NMP) at a weight ratio of 90:5:5 and thoroughly stirred to prepare the positive electrode active material. The positive electrode active material was uniformly coated onto the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet. The average thickness of the carbon coating material on the positive electrode active material was 3 nm. The thickness of the positive electrode film layer on one side of the positive electrode current collector was 80 μm.

[0115] (3) Separating membrane

[0116] A polyethylene film layer is used as the isolation membrane.

[0117] (4) Electrolyte

[0118] An electrolyte was prepared by mixing propylene carbonate, dimethyl carbonate, methyl acetate, and sodium bis(fluorosulfonyl)imide in a mass ratio of 27:31:26:17 in an argon atmosphere glove box (H2O content <10ppm, O2 content <1ppm). The conductivity of the electrolyte was 15.43 mS / cm.

[0119] (5) Preparation of battery cells

[0120] The positive electrode, separator, and negative electrode are arranged in the order of "separator—negative electrode—separator—positive electrode," so that the separator acts as a barrier between the positive and negative electrodes. One end of the positive electrode, negative electrode, and two separators is fixed to the discharge roller, and the other end is stacked together and fixed to the winding shaft. A motor is used to rotate the winding shaft to wind the positive electrode, negative electrode, and two separators. After baking, electrolyte injection, and formation, a single battery cell is obtained.

[0121] Examples 2-5

[0122] The differences between Examples 2-5 and Example 1 are: different electrolyte conductivity and different mass percentage of sodium ion salt in the electrolyte.

[0123] Example 6

[0124] The difference between Example 6 and Example 1 is that the electrolyte conductivity is different, the mass ratio of sodium ion salt in the electrolyte is different, and the sodium ion salt component is sodium bis(trifluoromethyl)sulfonylimide.

[0125] Comparative Example 1

[0126] The differences between Comparative Example 1 and Example 1 are: the thickness of the positive electrode film layer on one side of the positive electrode current collector is 130 μm, the electrolyte conductivity is different, the mass ratio of sodium ion salt in the electrolyte is different, and the sodium ion salt component is sodium hexafluorophosphate.

[0127] The specific parameters of the battery cells in Examples 1-6 and Comparative Example 1 are shown in Table 1 below.

[0128] Table 1: Specific parameters of Examples 1-6 and Comparative Example 1

[0129] In addition, the battery cells in Examples 1-6 and Comparative Example 1 were subjected to performance tests. The test results are shown in Table 2 below.

[0130] Table 2: Performance test results of Examples 1-6 and Comparative Example 1

[0131] Referring to Examples 1-6 and Comparative Example 1, compared to Comparative Example 1, in Examples 1-6, when the electrolyte contains sodium ion salts with the aforementioned conductivity and a relatively large molecular weight anion at the aforementioned mass percentage, the sodium-ion battery cells in Examples 1-6 exhibit higher cycle capacity retention and high-temperature storage capacity retention, thus demonstrating that the sodium-ion battery cells in Examples 1-6 have better cycle performance and storage life. Furthermore, the sodium-ion battery cells in Examples 1-6 also exhibit a higher minimum voltage after high-rate discharge at low temperature and low SOC, thus demonstrating that the sodium-ion battery cells in Examples 1-6 also have higher discharge power at low temperature and low SOC. Further, referring to Examples 1-6, when the mass percentage of the aforementioned sodium ion salt in the electrolyte is within the range of Examples 3 and 4, the sodium-ion battery cells exhibit superior discharge power, cycle capacity retention, and high-temperature storage capacity retention.

[0132] Examples 7-8

[0133] The difference between Examples 7-8 and Example 1 is that the mass ratio of sodium iron phosphate to sodium iron pyrophosphate is different.

[0134] The specific parameters of the battery cells in Examples 7-8 above are shown in Table 3 below.

[0135] Table 3: Specific parameters of Examples 7-8

[0136] In addition, the battery cells in Examples 7-8 above were subjected to performance tests. The test results are shown in Table 4 below.

[0137] Table 4: Performance test results of Examples 7-8

[0138] As shown in Examples 1 and 7-8, when the mass ratio of sodium iron phosphate to sodium iron pyrophosphate is within the aforementioned range, the sodium-ion battery cells in Examples 1 and 7-8 exhibit good cycle capacity retention and high-temperature storage capacity retention, thus demonstrating that the sodium-ion battery cells in Examples 1 and 7-8 possess excellent cycle performance and storage life. Furthermore, the sodium-ion battery cells in Examples 1 and 7-8 also exhibit good minimum voltage after high-rate discharge under low-temperature, low-SOC conditions, thus demonstrating that the sodium-ion battery cells in Examples 1 and 7-8 also possess good discharge power under low-temperature, low-SOC conditions. Further, as shown in Examples 1 and 7-8, when the mass ratio of sodium iron phosphate to sodium iron pyrophosphate is within the range of Examples 1 and 7, the sodium-ion battery cells exhibit even better discharge power, cycle capacity retention, and high-temperature storage capacity retention.

[0139] Examples 9-12

[0140] The difference between Examples 9-12 and Example 1 is that the thickness of the positive electrode film layer is different on one side of the positive electrode current collector.

[0141] The specific parameters of the battery cells in Examples 9-12 above are shown in Table 5 below.

[0142] Table 5: Specific parameters of Examples 9-12

[0143] In addition, the battery cells in Examples 9-12 above were subjected to performance tests. The test results are shown in Table 6 below.

[0144] Table 6: Performance Test Results of Examples 9-12

[0145] Referring to Examples 1 and 9-12, in Examples 1 and 9-12, when the thickness of the positive electrode film layer on one side of the positive electrode current collector is within the aforementioned range, the sodium-ion battery cell exhibits a good minimum voltage after high-rate discharge under low-temperature and low-SOC conditions, thus proving that the sodium-ion battery cells in Examples 1 and 9-12 have good discharge power under low-temperature and low-SOC conditions. Furthermore, referring to Examples 1 and 9-12, when the thickness of the positive electrode film layer on one side of the positive electrode current collector is within the range of Examples 10 and 11, the sodium-ion battery cell exhibits even better discharge power under low-temperature and low-SOC conditions.

[0146] Examples 13-16

[0147] The difference between Examples 13-16 and Example 1 is that the Dv50 of the sodium phosphate composite material is different.

[0148] The specific parameters of the battery cells in Examples 13-16 above are shown in Table 7 below.

[0149] Table 7: Specific parameters of Examples 13-16

[0150] In addition, the battery cells in Examples 13-16 above were subjected to performance tests. The test results are shown in Table 8 below.

[0151] Table 8: Performance Test Results of Examples 13-16

[0152] As shown in Examples 1 and 13-16, when the particle size distribution of sodium phosphate is within the aforementioned range, the sodium-ion battery cells, under low temperature and low SOC conditions, can simultaneously exhibit good minimum voltage after high-rate discharge, cycle capacity retention, and high-temperature storage capacity retention. This demonstrates that the sodium-ion battery cells in Examples 1 and 13-16 can simultaneously achieve good discharge power, cycle performance, and storage life. Furthermore, as shown in Examples 1 and 13-16, when the particle size distribution of sodium phosphate is within the range of Examples 14 and 15, the sodium-ion battery cells, under low temperature and low SOC conditions, can simultaneously exhibit even better discharge power, cycle performance, and storage life.

[0153] Examples 17-19

[0154] The difference between Examples 17-19 and Example 1 is that the electrolyte conductivity is different.

[0155] The specific parameters of the battery cells in the above embodiments 17-19 are shown in Table 9 below.

[0156] Table 9: Specific parameters of Examples 17-19

[0157] In addition, the battery cells in Examples 17-19 above were subjected to performance tests. The test results are shown in Table 10 below.

[0158] Table 10: Performance test results of Examples 17-19

[0159] As shown in Examples 1 and 17-19, when the conductivity of the electrolyte is within the aforementioned range, the sodium-ion battery cells in Examples 1 and 17-19 exhibit good cycle capacity retention and high-temperature storage capacity retention, thus demonstrating that the sodium-ion battery cells in Examples 1 and 17-19 possess excellent cycle performance and storage life. Furthermore, the sodium-ion battery cells in Examples 1 and 17-19 also exhibit good minimum voltage after high-rate discharge under low-temperature and low-SOC conditions, thus demonstrating that the sodium-ion battery cells in Examples 1 and 17-19 also possess good discharge power under low-temperature and low-SOC conditions.

[0160] [Testing methods for individual battery cell parameters]

[0161] The battery cells being tested can be either freshly assembled and unformed, or they can be battery cells removed from electrical devices (such as vehicles).

[0162] (1) Testing of discharge power of sodium-ion battery cells under low temperature and low SOC conditions

[0163] Under a 25℃ testing environment, the sodium-ion battery cells prepared above were left to stand for 5 minutes, then charged at a constant current rate of 0.33C to 3.65V, and then charged at a constant voltage rate until the current was less than or equal to 0.05C. After that, they were left to stand for 5 minutes, then discharged at a constant current rate of 0.33C to 1.5V. The discharge capacity of this discharge was recorded as the battery capacity C0. Then, the battery cells were charged at a constant current rate of 0.33C to 0.5C0Ah, adjusting the battery cell capacity to 50% SOC. After standing for 5 minutes, the testing environment temperature was adjusted to -10℃ and left to stand for another 2 hours. Then, they were discharged at a rate of 16.7C for 10 seconds, and the lowest discharge voltage was extracted. The lowest discharge voltage represents the discharge power level.

[0164] (2) Test of capacity retention of sodium-ion battery cells at 25°C

[0165] At 25°C, the sodium-ion battery cell prepared above is charged to 3.65V with a constant current of 0.33C, and then charged with a constant voltage of 3.65V until the current drops to 0.05C. After standing for 5 minutes, it is discharged to 1.5V with a constant current of 1C. This is the first charge / discharge cycle of the battery. The discharge capacity of this cycle is recorded as the discharge capacity C0 of the battery in the first cycle. The above steps are repeated for the same battery. The discharge capacity C1 of the battery after 1000 cycles is recorded. The capacity retention rate after 1000 cycles is (C1 / C0)×100%.

[0166] (3) Test of the rate of change of storage capacity of sodium-ion battery cells at 60℃ high temperature and high pressure

[0167] At 25°C, the sodium-ion battery cells prepared above were left to stand for 5 minutes, then discharged at a constant current rate of 0.33C to 1.5V, and then charged at a constant current rate of 1 / 3C to 3.65V. At 3.65V, they were charged at a constant voltage until the current was less than 0.05C. After standing for 5 minutes, they were discharged at a constant current rate of 0.33C to 1.5V. This discharge capacity is recorded as the battery's initial discharge capacity C0. The battery was then charged at a constant current rate of 0.33C to 3.65V, and then charged at a constant voltage rate of 3.65V until the current was less than 0.05C. It was then stored at 60°C in a constant temperature chamber for 3 months. After this high-temperature storage, the sodium-ion battery was cooled to 25°C and discharged at a constant current rate of 0.33C to 1.5V. This discharge capacity is recorded as the battery's discharge capacity after high-temperature storage C1. The capacity retention rate of a sodium-ion battery after storage at 3.65V at 60℃ is calculated using the following formula: Capacity retention rate (%) of sodium-ion battery after high-temperature storage at 60℃ = (C1 / C0) × 100%.

[0168] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A sodium-ion battery cell, characterized in that, It includes a positive electrode, an electrolyte, and a negative electrode; among which, The positive electrode includes a positive current collector and a positive electrode film layer. The positive electrode film layer is located on at least one side of the positive current collector, and the thickness L of the positive electrode film layer on one side of the positive current collector satisfies: 50 μm ≤ L ≤ 125 μm. The positive electrode film layer includes a phosphate, and the general formula of the phosphate is Na. a Fe b M c (PON d ) e (P2O7) f The phosphate includes sodium iron pyrophosphate and sodium iron phosphate, and the mass ratio P of sodium iron phosphate to sodium iron pyrophosphate satisfies: 0.2% ≤ P ≤ 5%. The conductivity C of the electrolyte at 25±1℃ satisfies: 7mS / cm≤C≤20mS / cm; the electrolyte comprises a sodium ion salt, and the molecular weight N of the anion of the sodium ion salt satisfies: 150≤N≤300, and the mass percentage M of the sodium ion salt in the electrolyte satisfies: 10%≤M≤30%.

2. The sodium-ion battery cell according to claim 1, characterized in that, M satisfies: 13% ≤ M ≤ 23%.

3. The sodium-ion battery cell according to claim 1 or 2, characterized in that, P satisfies: 0.2% ≤ P ≤ 2%.

4. The sodium-ion battery cell according to any one of claims 1-3, characterized in that, L satisfies: 60μm≤L≤100μm.

5. The sodium-ion battery cell according to any one of claims 1-4, characterized in that, The Dv50 of the phosphate satisfies: 1μm≤Dv50≤18μm.

6. The sodium-ion battery cell according to claim 5, characterized in that, Dv50 satisfies: 7μm≤Dv50≤11μm.

7. The sodium-ion battery cell according to any one of claims 1-6, characterized in that, The sodium ion salt includes sodium bis(fluorosulfonyl)imide and / or sodium bis(trifluoromethylsulfonyl)imide.

8. The sodium-ion battery cell according to any one of claims 1-7, characterized in that, The sodium-ion battery cell also includes: The housing is a hollow structure with an opening, and the electrolyte, the negative electrode, and the positive electrode are housed within the housing. A top cover that closes the opening.

9. A battery device, characterized in that, Includes the sodium-ion battery cell according to any one of claims 1-8.

10. An electrical device, characterized in that, It includes at least one of the following: a sodium-ion battery cell according to any one of claims 1-8, or a battery device according to claim 9.

11. The electrical appliance according to claim 10, characterized in that, The sodium-ion battery cell or the battery device serves as the start-stop power source for the electrical device.

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