Battery cell, battery device, and electric device

Abstract

The invention discloses a battery monomer, a battery device and a power utilization device, in a first aspect of the application, the invention provides the battery monomer, which comprises a negative electrode piece, a positive electrode piece and a negative electrode piece, the electrolyte comprises a sodium salt and an inert solvent, and the inert solvent comprises at least one of compounds shown as a formula 1 and / or a formula 2; wherein a is 1, 2, 3 or 4; wherein b is 1 or 2, n1 and n2 are respectively and independently 1, 2 or 3, and n1 and n2 are not 1 at the same time. Therefore, the gas production problem of the battery monomer in the use and storage processes can be effectively relieved, and the cycle performance and the storage performance of the battery monomer are improved.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically to battery cells, battery devices, and electrical devices. Background Technology

[0002] Currently, lithium-ion batteries occupy a core position in the power battery market. However, as their application in consumer electronics, electric vehicles, and energy storage expands, lithium-ion batteries also face significant challenges, such as the increasing scarcity of lithium resources, rising prices of upstream materials, lagging development of recycling technologies, and low recycling rates of older batteries. Sodium-ion batteries, due to the abundant availability of sodium on Earth, are gaining attention. They utilize the intercalation and deintercalation of sodium ions between the positive and negative electrodes for charging and discharging. Furthermore, sodium resources are far more abundant and widely distributed than lithium, and their cost is significantly lower, giving them a crucial strategic position in cost-sensitive applications such as energy storage. However, many issues regarding the application of sodium-ion batteries still remain to be resolved.

[0003] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0004] In a first aspect of this application, a battery cell is provided, comprising: a negative electrode sheet, the negative electrode sheet including a negative current collector; and an electrolyte comprising: a sodium salt and an inert solvent, wherein the inert solvent comprises at least one compound shown in Formula 1 and / or Formula 2.

[0005] Where a is 1, 2, 3 or 4;

[0006] Where b is 1 or 2, n1 and n2 are 1, 2 or 3 independently, and n1 and n2 are not both 1.

[0007] This can effectively alleviate the gas generation problem of battery cells during use and storage, and improve the cycle performance and storage performance of battery cells.

[0008] In some embodiments, the inert solvent includes at least one selected from ethylene glycol di-tert-butyl ether, diethylene glycol di-tert-butyl ether, triethylene glycol di-tert-butyl ether, tetraethylene glycol di-tert-butyl ether, ethylene glycol isopropyl tert-butyl ether, ethylene glycol diisopropyl ether, ethylene glycol isopropyl ethyl ether, diethylene glycol isopropyl tert-butyl ether, diethylene glycol diisopropyl ether, and diethylene glycol isopropyl ethyl ether. This effectively suppresses side reactions between sodium metal and the electrolyte, improving the cycle performance and storage performance of the battery cell.

[0009] In some embodiments, the inert solvent includes at least one of ethylene glycol di-tert-butyl ether and diethylene glycol di-tert-butyl ether. This further suppresses side reactions between sodium metal and the electrolyte.

[0010] In some embodiments, the sodium salt comprises at least one selected from sodium perchlorate, sodium tetrafluoroborate, sodium hexafluorophosphate, sodium hexafluoroarsenate, sodium trifluoroacetate, sodium tetraphenylborate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide. This improves the electrochemical window, suppresses side reactions, and promotes more uniform sodium metal deposition.

[0011] In some embodiments, the inert solvent accounts for 7%-77% of the total mass of the electrolyte. Thus, the inert solvent can suppress side reactions between sodium metal and the electrolyte solvent.

[0012] In some embodiments, the inert solvent accounts for 10%-30% of the total mass of the electrolyte.

[0013] In some embodiments, the sodium salt accounts for 3%-40% of the total mass of the electrolyte. This provides a higher concentration of active sodium ions.

[0014] In some embodiments, the sodium salt accounts for 5%-30% of the total mass of the electrolyte.

[0015] In some embodiments, the electrolyte further comprises a coordination solvent, which includes at least one selected from the following: ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, ethylene carbonate, propylene carbonate, butene carbonate, vinylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, fluoroethylene carbonate, γ-butyrolactone, 1,3-propanesulfonate lactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate, ethyl butyrate, and dimethyl sulfoxide. This facilitates the complete dissolution of the sodium salt in the electrolyte and improves the ionic conductivity of the electrolyte.

[0016] In some embodiments, the coordination solvent includes at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol dimethyl ether.

[0017] In some embodiments, the mass percentage of the coordination solvent is 20%-90% based on the total mass of the electrolyte. Therefore, by adjusting the amount of coordination solvent, the solubility of the sodium salt and the ionic conductivity of the electrolyte can be improved.

[0018] In some embodiments, the mass percentage of the coordination solvent is 30%-80% based on the total mass of the electrolyte.

[0019] In some embodiments, the electrolyte further comprises ether additives, including C2-C7 fluoroalkyl ethers. This helps to form a structurally stable solid electrolyte interface film on the surface of the negative electrode active material, improving the cycle performance of the battery cell.

[0020] In some embodiments, the C2-C7 fluoroalkyl ethers include 1,1,2,2-tetrafluoroethyl methyl ether, 2,2,3,3-tetrafluoropropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, bis-(2,2,2-trifluoroethyl) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, methyl nonafluorobutyl ether, bis-(1,1,2,2-tetrafluoroethyl) ether, difluoromethyl-2,2,2-trifluoroethyl ether, 1,1,1,3,3,3-hexafluoro-2(fluoromethoxy)propane, and 1,1,2,3,3,3-pentafluoro At least one of the following: propyl-2,2,2-trifluoroethyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, 2,2,3,3-tetrafluoro-1-methoxypropane, 1,1,2,3,3,3-pentafluoropropyl ethyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, 1,1,2,3,3,3-hexafluoropropyl methyl ether, ethyl perfluorobutyl ether, ethyl nonafluorobutyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, 1,1,2,3,3,3-pentafluoropropyl-2,2,2-trifluoroethyl ether, 2,2,3,3,3-pentafluoropropyl difluoromethyl ether, and 2,2,2-trifluoroethyl ethyl ether.

[0021] In some embodiments, the ether additives account for 0.1%-4% of the total mass of the electrolyte.

[0022] In some embodiments, the ether additives account for 0.5%-3% of the total mass of the electrolyte.

[0023] In some embodiments, the electrolyte has an ionic conductivity greater than or equal to 0.5 mS / cm. This facilitates the rapid movement of sodium ions in the electrolyte, thereby increasing the power density of the battery cell.

[0024] In some embodiments, the battery further includes a positive electrode sheet, which comprises a positive current collector and a positive active material layer located on at least one side of the positive current collector. The positive active material layer comprises a positive active material, which includes at least one of a sodium-containing polyanionic compound and a sodium-containing layered oxide. This improves the cycle stability of the battery and increases its energy density.

[0025] In some embodiments, the positive electrode active material comprises a sodium-containing polyanionic compound. This improves the compatibility between the positive electrode active material and the electrolyte, thereby enhancing battery lifespan.

[0026] In some embodiments, the battery cell is a sodium-free negative electrode battery cell. Therefore, the battery cell has a high energy density.

[0027] In a second aspect, this application proposes a battery device comprising the aforementioned battery cell, wherein the battery device includes at least one of a battery module, a battery pack, and an energy storage device. Thus, this battery device possesses all the features and advantages of the aforementioned battery cell, which will not be repeated here.

[0028] In a third aspect, this application proposes an electrical device comprising the aforementioned battery cell. Therefore, this electrical device possesses all the features and advantages of the aforementioned battery cell, which will not be repeated here. Attached Figure Description

[0029] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0030] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0031] Figure 2 yes Figure 1 An exploded view of a battery cell according to an embodiment of this application is shown;

[0032] Figure 3 This is a schematic diagram of a battery module according to an embodiment of this application;

[0033] Figure 4 This is a schematic diagram of a battery pack according to an embodiment of this application;

[0034] Figure 5 yes Figure 4 An exploded view of a battery pack according to an embodiment of this application is shown;

[0035] Figure 6 This is a schematic diagram of an electrical device in which a battery is used as a power source, according to an embodiment of this application.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery module; 5. Individual battery cell;

[0038] 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0039] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. 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 to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0040] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0041] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0042] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.

[0043] 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.

[0044] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0045] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0046] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0047] Electrodeless sodium batteries offer advantages such as high energy density and low cost. Specifically, an electrodeless sodium battery refers to a battery in which no negative electrode active material layer is actively placed on the negative electrode side during the manufacturing process of the battery cell. For example, no negative electrode active material layer is added to the surface of the negative electrode current collector through coating or deposition processes during the manufacturing of the battery cell. During battery charging, sodium ions in the positive electrode active material layer migrate to the surface of the negative electrode current collector and deposit to form a sodium metal layer. During battery discharge, the metallic sodium in the sodium metal layer can be converted into sodium ions and re-intercalated into the positive electrode, thus achieving cyclic charging and discharging. Compared to other sodium batteries, electrodeless sodium batteries have higher energy density due to the absence of a pre-placed negative electrode active material layer. However, when an electrodeless sodium battery is charged, the surface of the negative electrode current collector contains highly chemically reactive sodium metal. The sodium metal reacts with the electrolyte to produce a large amount of hydrogen gas, resulting in poor cycle performance and storage performance under charged conditions, and may even severely deteriorate battery safety performance.

[0048] Related technologies control the composition of the SEI (Solid Electrolyte Interface) on the sodium metal surface to block contact between the sodium metal and the electrolyte, thereby reducing the rate of side reactions between them. However, since anode-less sodium batteries undergo sodium metal layer deposition and stripping in each charge-discharge cycle, the SEI component formed on the sodium metal surface during the previous charge-discharge cycle cannot be fully utilized in the next cycle. Conversely, the formation of some new SEI on the sodium metal surface in each cycle consumes active sodium ions, as well as solvents and additives in the electrolyte, inevitably leading to a deterioration in battery cycle performance. Furthermore, the venting valve design increases battery cost and does not fundamentally solve the cell gas expansion problem.

[0049] In this application, a high-temperature gas production test was first conducted on the electrolyte. The test results showed that the electrolyte produced virtually no gas when stored alone at high temperatures, eliminating the possibility of gas production caused by the decomposition of the electrolyte itself at high temperatures. Secondly, only the solvent molecules in the electrolyte contained hydrogen, indicating that the gas production originated from a side reaction between the solvent and sodium metal. Finally, by comparing the correspondence between the solvent consumption and the gas production volume in the battery cell, a near 1:1 linear relationship was found, meaning that every 1 mol of solvent consumed corresponds to the production of 1 mol of H2. Based on the above investigation, it is shown that the hydrogen production problem in a negative electrode-less sodium battery mainly stems from the chemical reaction between sodium metal and the electrolyte solvent. Therefore, the electrolyte formulation is optimized in this application, and compounds as shown in Formula 1 and / or Formula 2 are used as electrolyte solvents for negative electrode-free sodium batteries. By controlling the number of active hydrogen atoms in the solvent that react with sodium metal at high temperature to produce gas, the side reaction activity between the solvent and sodium metal in the electrolyte is effectively reduced, and the side reaction between the electrolyte and sodium metal is significantly reduced, thereby reducing the generation of hydrogen gas and improving the poor gas expansion of battery cells.

[0050] In a first aspect of this application, a battery cell is provided, comprising: a negative electrode sheet, the negative electrode sheet including a negative current collector; and an electrolyte comprising: a sodium salt and an inert solvent, wherein the inert solvent comprises at least one compound shown in Formula 1 and / or Formula 2.

[0051] Where a is 1, 2, 3 or 4;

[0052] Where b is 1 or 2, n1 and n2 are 1, 2 or 3 independently, and n1 and n2 are not both 1.

[0053] By designing the solvent molecule structure, methyl groups are used to partially or completely replace the active hydrogen atoms in the solvent molecule that react with sodium metal. As a result, when the compounds shown in Formula 1 and / or Formula 2 are used as the solvent for the electrolyte, the number of active hydrogen atoms in the solvent that will react with sodium metal to produce gas at high temperatures is reduced. This can effectively suppress the side reactions between the electrolyte solvent and sodium metal, thereby alleviating the gas generation problem of the battery cell during use and storage, and improving the cycle performance and storage performance of the battery cell.

[0054] As an example, taking ethylene glycol dimethyl ether as the electrolyte solvent, a sodium-ion battery without a negative electrode was assembled. Gas production tests at 60°C revealed that this solvent reacts with sodium metal to produce hydrogen gas. Ethylene glycol dimethyl ether contains hydrogen in two chemical environments: ① terminal methyl hydrogen, and ② ethylidene hydrogen between oxygen and oxygen. By methylating hydrogen in different chemical environments (e.g., by methylating ethylene glycol dimethyl ether with iodomethane under the action of a catalyst such as aluminum trichloride), two solvent molecules, ethylene glycol di-tert-butyl ether (TBE) and neohexylene glycol dimethyl ether (1,1,2,2-tetramethyl-1,2-dimethoxyethane, PDE), were obtained. Using these two solvent molecules as electrolyte solvents and assembling them using the same process, a sodium-ion battery without a negative electrode was obtained. Gas production tests at 60°C showed that TBE did not react with sodium metal to produce hydrogen gas, while PDE did react with sodium metal to produce hydrogen gas. Therefore, active hydrogen can be defined as the hydrogen atom on an alkyl group directly attached to O.

[0055] As an example, the 60℃ storage gas generation test can be performed using the following method: The battery is placed in a 60℃ constant temperature chamber for formation treatment and storage testing. The formation steps are as follows: charge at a constant current rate of 0.1C to 3.6V, then discharge at a constant current rate of 0.1C to 1.5V. Subsequently, the storage gas generation test is performed as follows: charge at a constant current rate of 1C to 3.6V, then place in a 60℃ constant temperature chamber. Record the gas generation amount every 6 days. The change in the gas generation amount can reflect the gas generation situation inside the battery cell.

[0056] In some embodiments, the hydrogen atoms on the alkyl groups directly connected to O in the compound shown in Formula 1 are all replaced by methyl groups. Therefore, the compound produces less active hydrogen gas when reacting with sodium metal at high temperatures, which can effectively improve the high-temperature storage performance and cycle performance of the battery cell.

[0057] In some embodiments, the hydrogen atoms on the alkyl group directly attached to O in the compound of Formula 2 are partially replaced by methyl groups, thereby improving the high-temperature storage performance and cycle performance of the battery cell. At the same time, because some active hydrogen atoms are still retained, the compound has high solubility for sodium salts, which helps to fully dissolve the sodium salts.

[0058] As an example, when b is 1, the compound shown in Equation 2 is as follows:

[0059]

[0060] n1 and n2 are independently 1, 2 or 3, and n1 and n2 are not both 1 at the same time.

[0061] As an example, when b is 2, the compound represented by Equation 2 is as follows.

[0062] n1 and n2 are independently 1, 2 or 3, and n1 and n2 are not both 1 at the same time.

[0063] In some embodiments, the inert solvent may include at least one of ethylene glycol di-tert-butyl ether, diethylene glycol di-tert-butyl ether, triethylene glycol di-tert-butyl ether, tetraethylene glycol di-tert-butyl ether, ethylene glycol isopropyl tert-butyl ether, ethylene glycol diisopropyl ether, ethylene glycol isopropyl ethyl ether, diethylene glycol isopropyl tert-butyl ether, diethylene glycol diisopropyl ether, and diethylene glycol isopropyl ethyl ether. Therefore, by controlling the number of active hydrogen atoms in the solvent that react with sodium metal to produce gas at high temperatures, the occurrence of side reactions between sodium metal and the electrolyte can be effectively suppressed, improving the cycle performance and storage performance of the battery cell.

[0064] As an example, an inert solvent can be obtained by reacting ethylene glycol dimethyl ether with iodoalkane in the presence of a catalyst such as aluminum trichloride (methyl substitution).

[0065] In some embodiments, the inert solvent includes at least one of ethylene glycol di-tert-butyl ether and diethylene glycol di-tert-butyl ether. This further suppresses side reactions between sodium metal and the electrolyte.

[0066] In some embodiments, the sodium salt comprises at least one selected from sodium perchlorate, sodium tetrafluoroborate, sodium hexafluorophosphate, sodium hexafluoroarsenate, sodium trifluoroacetate, sodium tetraphenylborate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide. This improves the electrochemical window, suppresses side reactions, and promotes more uniform sodium metal deposition.

[0067] By using the aforementioned sodium salt as the electrolyte salt, it is helpful to achieve efficient deposition and stripping of the sodium metal layer on the surface of the negative electrode current collector during charging and discharging, which is suitable for sodium-free electrical systems.

[0068] In some embodiments, the inert solvent accounts for 7%-77% of the total mass of the electrolyte. Thus, the inert solvent can suppress side reactions between sodium metal and the electrolyte solvent.

[0069] As an example, based on the total mass of the electrolyte, the mass percentage of the inert solvent can be 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 77%.

[0070] In some embodiments, the inert solvent accounts for 10%-30% of the total mass of the electrolyte.

[0071] In some embodiments, the sodium salt accounts for 3%-40% of the total mass of the electrolyte. Therefore, the sodium salt can provide more active sodium ions, improving the ionic conductivity of the electrolyte.

[0072] As an example, based on the total mass of the electrolyte, the mass percentage of the sodium salt can be 3%, 5%, 7%, 10%, 13%, 15%, 17%, 20%, 23%, 25%, 27%, 30%, 33%, 35%, 37%, or 40%.

[0073] In some embodiments, the sodium salt accounts for 5%-30% of the total mass of the electrolyte.

[0074] In some embodiments, the electrolyte further comprises a coordination solvent, which includes at least one selected from the following: ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, ethylene carbonate, propylene carbonate, butene carbonate, vinylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, fluoroethylene carbonate, γ-butyrolactone, 1,3-propanesulfonate lactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate, ethyl butyrate, and dimethyl sulfoxide. This facilitates the complete dissolution of the sodium salt in the electrolyte and improves the ionic conductivity of the electrolyte.

[0075] The use of a coordination solvent helps the sodium salt to dissociate and dissolve in the electrolyte, so that the ionic conductivity of the electrolyte can meet the requirements.

[0076] In some embodiments, the coordination solvent includes at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol dimethyl ether.

[0077] In some embodiments, the mass percentage of the coordination solvent is 20%-90% based on the total mass of the electrolyte. Therefore, by adjusting the amount of coordination solvent, the solubility of the sodium salt and the ionic conductivity of the electrolyte can be improved.

[0078] As an example, based on the total mass of the electrolyte, the mass percentage of the coordination solvent is 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%.

[0079] In some embodiments, the mass percentage of the coordination solvent is 30%-80% based on the total mass of the electrolyte.

[0080] In some embodiments, the electrolyte further comprises ether additives, including C2-C7 fluoroalkyl ethers. This helps to form a structurally stable solid electrolyte interface film on the surface of the negative electrode active material, improving the cycle performance of the battery cell.

[0081] C2-C7 fluoroalkyl ether additives can undergo a weak chemical reaction with sodium metal to form an SEI film containing inorganic components such as NaF on the sodium metal surface. This helps to reduce the reactivity between the sodium metal deposited on the negative electrode and the electrolyte, thereby reducing the high-temperature gas generation of the battery cell.

[0082] In some embodiments, the C2-C7 fluoroalkyl ethers include 1,1,2,2-tetrafluoroethyl methyl ether, 2,2,3,3-tetrafluoropropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, bis-(2,2,2-trifluoroethyl) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, methyl nonafluorobutyl ether, bis-(1,1,2,2-tetrafluoroethyl) ether, difluoromethyl-2,2,2-trifluoroethyl ether, 1,1,1,3,3,3-hexafluoro-2(fluoromethoxy)propane, and 1,1,2,3,3,3-pentafluoro At least one of the following: propyl-2,2,2-trifluoroethyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, 2,2,3,3-tetrafluoro-1-methoxypropane, 1,1,2,3,3,3-pentafluoropropyl ethyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, 1,1,2,3,3,3-hexafluoropropyl methyl ether, ethyl perfluorobutyl ether, ethyl nonafluorobutyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, 1,1,2,3,3,3-pentafluoropropyl-2,2,2-trifluoroethyl ether, 2,2,3,3,3-pentafluoropropyl difluoromethyl ether, and 2,2,2-trifluoroethyl ethyl ether.

[0083] In some embodiments, the ether additives account for 0.1%-4% of the total mass of the electrolyte.

[0084] As an example, based on the total mass of the electrolyte, the mass percentage of the ether additive can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, or 4%.

[0085] In some embodiments, the ether additives account for 0.5%-3% of the total mass of the electrolyte.

[0086] In some embodiments, the electrolyte has an ionic conductivity greater than or equal to 0.5 mS / cm. This facilitates the rapid movement of sodium ions in the electrolyte, thereby increasing the power density of the battery cell.

[0087] As an example, the conductivity of the electrolyte can be directly tested using methods known in the art. For instance, the electrolyte can be transferred to a centrifuge tube and placed at -30°C and atmospheric pressure (0.1 MPa) for 30 minutes. The ionic conductivity of the electrolyte can then be tested using a Leici DDSJ-318 conductivity meter. Specifically, the conductivity electrode is washed with deionized water and rinsed with anhydrous ethanol to remove any residual water. After the electrode is dry, it is vertically inserted into the centrifuge tube containing the electrolyte to be tested, ensuring that the platinum electrode is submerged below the surface of the electrolyte. Once the instrument reading stabilizes, the result is recorded. The measurement is repeated three times, and the average value is taken.

[0088] [Negative electrode plate]

[0089] In some embodiments, the negative electrode may include a negative current collector, which may be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium may be used. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector may include a polymeric material substrate and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0090] In some embodiments, in order to improve the performance of a single battery cell, the negative electrode sheet may include a negative current collector and a functional coating disposed on at least one side of the surface of the negative current collector. The functional coating may include a carbon material coating (carbon materials include single-walled conductive carbon nanotubes, multi-walled conductive carbon nanotubes, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers, soft carbon and hard carbon, etc.), a lithium-loving / sodium-loving metal composite coating, etc.

[0091] In some embodiments, the negative electrode current collector can be a composite current collector. For example, the composite current collector may include at least one of carbon cloth, carbon film, carbonaceous material, porous current collector, alloyed modified current collector, and lithium-philic / sodium-modified current collector.

[0092] [Positive electrode plate]

[0093] In some embodiments, the battery cell includes a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer located on at least one side of the positive current collector, the positive active material layer including a positive active material.

[0094] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0095] 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.).

[0096] In some embodiments, the positive electrode active material includes at least one of a sodium-containing polyanionic compound and a sodium-containing layered oxide. This can improve the cycle stability of the battery and increase its energy density. However, this application is not limited to these materials; other conventional materials that can be used as positive electrode active materials, as well as corresponding modified materials, can also be used. The modified compounds for the above-mentioned materials can be those used for doping modification and / or surface coating modification.

[0097] In some embodiments, the positive electrode active material comprises a sodium-containing polyanionic compound. This improves the compatibility between the positive electrode active material and the electrolyte, thus enhancing battery lifespan. The sodium-containing polyanionic compound possesses a stable framework structure, resisting volume changes during charge and discharge, thereby providing good cycle stability, reducing material pulverization and shedding, and extending cycle life. Furthermore, the upper limit of the operating voltage range of the sodium-containing polyanionic compound is no greater than 3.8V, while the oxidation potential of ether-based electrolytes is approximately 4V, thus enabling the sodium-containing polyanionic compound to be well compatible with the aforementioned electrolyte systems.

[0098] In some embodiments, the sodium-containing layered oxide comprises a sodium transition metal oxide, wherein the transition metal in the sodium transition metal oxide may be at least one selected from Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, and Cu. The chemical formula of the sodium transition metal oxide may satisfy Na x MO2, wherein M includes at least one of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, and Cu, and 0 < x ≤ 1. The structure of sodium-containing layered oxides allows for a large number of sodium ions to be inserted and extracted, providing high specific capacity and good rate performance, maintaining stable capacity output at high current densities.

[0099] In some embodiments, the sodium-containing polyanionic compound may be a compound containing sodium ions, transition metal ions, and a tetrahedral (YO4) structure. n-A class of compounds with anionic units. The transition metal 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; n represents (YO4). n- The price state.

[0100] In some embodiments, the sodium-containing polyanionic compound may also be a tetrahedral compound containing sodium ions, transition metal ions, or YO4. 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 of halogens can include at least one of F, Cl, and Br.

[0101] In some embodiments, the sodium-containing polyanionic compound may also be a tetrahedral (YO4) compound containing sodium ions. n- Anionic unit, polyhedral unit (ZO) y ) m+ And a class of compounds with optional halide anions. M 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, and n represents (YO4). n- The valence state, Z represents transition metal, m represents (ZO) y ) m+ The valence state of halogens can include at least one of F, Cl, and Br.

[0102] As an example, sodium-containing polyanionic compounds can satisfy the chemical formulas NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7), NaM'PO4F (M' includes at least one of V, Fe, Mn and Ni), and Na3(VO4)2(PO4)3 ... y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0103] During the charging and discharging process of a battery, sodium (Na) undergoes insertion / extraction and consumption, resulting in varying molar Na content at different discharge states. In the examples of positive electrode active materials in this application, the molar Na content refers to the initial state of the material, i.e., the state before material addition. After charge-discharge cycles, the molar Na content changes when the positive electrode active material is applied to the battery system.

[0104] In the examples of positive electrode active materials for sodium-ion batteries in this application, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate.

[0105] In some embodiments, the positive electrode active material layer may optionally include a binder.

[0106] As an example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0107] In some embodiments, the positive electrode active material layer may optionally include a conductive agent.

[0108] As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0109] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as 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 electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0110] [Isolation membrane]

[0111] In some embodiments, the battery also includes a separator. This application does not impose any particular limitation on the type of separator; any porous separator with good chemical and mechanical stability can be selected.

[0112] In some embodiments, the material of the separator includes at least one selected from 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.

[0113] In some embodiments, the battery cell 5 can be a sodium-free battery cell.

[0114] In a second aspect, this application proposes a battery device comprising the aforementioned battery cell, wherein the battery device includes at least one of a battery module, a battery pack, and an energy storage device. Thus, this battery device possesses all the features and advantages of the aforementioned battery cell, which will not be repeated here.

[0115] The battery device of this application includes battery cell form, battery module form, and battery pack form. The battery cell, battery module, and battery pack of this application will be described below with appropriate reference to the accompanying drawings.

[0116] This application does not impose any particular limitation on the shape of the battery cell 5; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 The example shown is a square-structured battery cell 5.

[0117] In some embodiments, refer to Figure 2 The outer packaging may include a housing 51 and a top cover assembly 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can cover the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator can be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0118] In some embodiments, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly by a winding process or a stacking process.

[0119] In some embodiments, a single battery cell may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0120] In some embodiments, the outer packaging of the battery cell can be a hard 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 soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0121] In some embodiments, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0122] Figure 3 This is battery module 4 as an example. (See reference...) Figure 3 In battery module 4, multiple battery cells can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other way. Furthermore, these multiple battery cells can be fixed in place using fasteners.

[0123] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells are housed.

[0124] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack 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 pack.

[0125] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 The battery pack 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, with the upper box 2 covering the lower box 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0126] In a third aspect, this application proposes an electrical device comprising the aforementioned battery cell. Therefore, this electrical device possesses all the features and advantages of the aforementioned battery cell, which will not be repeated here.

[0127] Battery cells, battery modules, and battery packs can be used as power sources for electrical devices or as energy storage units for electrical devices. Electrical devices can include, but are not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as 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.

[0128] As an electrical device, batteries, battery modules, or battery packs can be selected according to their usage requirements.

[0129] Figure 6 This is an example of an electrical device. Such a 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 the battery, a battery pack or battery module can be used.

[0130] 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.

[0131] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of 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 whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0132] Example 1

[0133] Preparation of the positive electrode sheet: The positive electrode active material Na4Fe3(PO4)2(P2O7), the binder polyvinylidene fluoride (PVDF), and the conductive agent conductive carbon black (Super-P) are mixed evenly in N-methylpyrrolidone (NMP) solvent at a mass ratio of 96:2:2 to prepare the positive electrode slurry. This slurry is then coated onto the surface of aluminum foil using an extrusion coating machine according to the required mass per unit area of ​​the positive electrode active material, and dried. Finally, the coated electrode sheet is pressed using a cold press at a density of 2.5 g / cm³. 3 The positive electrode sheet is prepared by cold pressing after compaction.

[0134] Preparation of the negative electrode sheet: Single-walled carbon nanotubes were added to deionized water and stirred to form a uniform negative electrode slurry. The negative electrode slurry was coated onto a negative electrode current collector, dried, and cut to obtain a negative electrode sheet with a functional coating on the surface. The areal density of the functional coating was 25 g / m². 2 .

[0135] Preparation of the separator: A polyethylene film with a thickness of 9 μm was used as the separator.

[0136] Preparation of electrolyte: Sodium hexafluorophosphate, ethylene glycol dimethyl ether, and ethylene glycol di-tert-butyl ether were mixed evenly in a mass ratio of 2:9:9 in an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm) to prepare the electrolyte.

[0137] Assembly of a single battery cell: The positive electrode, separator, and negative electrode are wound together to form an electrode assembly. The separator is placed between the positive and negative electrode to provide isolation. The tabs are welded on, and the electrode assembly is installed in an aluminum shell and baked at 80°C to remove water. Then, the electrolyte is injected and the shell is sealed. The battery cell is then subjected to a series of processes including settling, hot and cold pressing, formation, and shaping to obtain the single battery cell.

[0138] Examples 2-15 and Comparative Examples 1-2 are consistent with Example 1, with differences shown in Tables 1-1 and 1-2:

[0139] Table 1-1

[0140]

[0141]

[0142] Table 1-2

[0143]

[0144] The aforementioned battery cells were subjected to the following tests, and the test results are shown in Table 2:

[0145] (1) Room temperature cycle performance: At 25℃ and normal pressure (0.1MPa), the battery is charged at a constant current of 1C to a voltage of 3.6V, and then discharged at a constant current of 1C to a voltage of 1.5V. This constitutes one charge-discharge cycle. The initial discharge capacity is taken as 100%, and the charge-discharge cycle is repeated 2000 times. The test is then stopped, and the cycle capacity retention rate is recorded. The room temperature capacity retention rate is used as the indicator to evaluate the room temperature cycle performance of the battery.

[0146] (2) High-temperature storage gas generation test: The 60℃ storage gas generation test can be performed using the following test method: Place the battery in a 60℃ constant temperature chamber for formation treatment and storage test. The formation steps are as follows: charge to 3.6V with a constant current at a rate of 0.1C, then discharge to 1.5V with a constant current at a rate of 0.1C, and then perform the storage gas generation test. The test steps are as follows: charge to 3.6V with a constant current at a rate of 1C, and then place in a 60℃ constant temperature chamber. Record the gas generation amount once every 6 days.

[0147] Table 2

[0148]

[0149] Test results show that, compared with the batteries in Comparative Examples 1-2, the batteries in Examples 1-15 have slightly affected the cycle performance due to the addition of inert solvent, but significantly suppressed gas generation during use and storage, and the batteries have better overall performance.

[0150] 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 battery cell, characterized in that, include: An electrolyte comprising: a sodium salt and an inert solvent, wherein the inert solvent comprises at least one of the compounds shown in Formula 1 and / or Formula 2; Where a is 1, 2, 3 or 4; Where b is 1 or 2, n1 and n2 are 1, 2 or 3 independently, and n1 and n2 are not both 1.

2. The battery cell according to claim 1, characterized in that, The inert solvent includes at least one of ethylene glycol di-tert-butyl ether, diethylene glycol di-tert-butyl ether, triethylene glycol di-tert-butyl ether, tetraethylene glycol di-tert-butyl ether, ethylene glycol isopropyl tert-butyl ether, ethylene glycol diisopropyl ether, ethylene glycol isopropyl ethyl ether, diethylene glycol isopropyl tert-butyl ether, diethylene glycol diisopropyl ether, and diethylene glycol isopropyl ethyl ether.

3. The battery cell according to claim 2, characterized in that, The inert solvent includes at least one of ethylene glycol di-tert-butyl ether and diethylene glycol di-tert-butyl ether.

4. The battery cell according to any one of claims 1-3, characterized in that, The sodium salt includes at least one of sodium perchlorate, sodium tetrafluoroborate, sodium hexafluorophosphate, sodium hexafluoroarsenate, sodium trifluoroacetate, sodium tetraphenylborate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide.

5. The battery cell according to any one of claims 1-4, characterized in that, Based on the total mass of the electrolyte, the inert solvent accounts for 7%-77% of the mass.

6. The battery cell according to claim 5, characterized in that, Based on the total mass of the electrolyte, the inert solvent accounts for 10%-30% of the total mass.

7. The battery cell according to any one of claims 1-5, characterized in that, Based on the total mass of the electrolyte, the sodium salt accounts for 3%-40% of the total mass.

8. The battery cell according to claim 7, characterized in that, Based on the total mass of the electrolyte, the sodium salt accounts for 5%-30% of the total mass.

9. The battery cell according to any one of claims 1-8, characterized in that, The electrolyte further comprises a coordination solvent, which includes at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, ethylene carbonate, propylene carbonate, butene carbonate, vinylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, fluoroethylene carbonate, γ-butyrolactone, 1,3-propanesulfonate lactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate, ethyl butyrate, and dimethyl sulfoxide.

10. The battery cell according to claim 9, characterized in that, The coordination solvent includes at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol dimethyl ether.

11. The battery cell according to claim 9 or 10, characterized in that, Based on the total mass of the electrolyte, the mass percentage of the coordination solvent is 20%-90%.

12. The battery cell according to claim 11, characterized in that, The mass percentage of the coordination solvent is 30%-80% based on the total mass of the electrolyte.

13. The battery cell according to any one of claims 1-12, characterized in that, The electrolyte further includes ether additives, which include C2-C7 fluoroalkyl ethers.

14. The battery cell according to claim 13, characterized in that, The C2-C7 fluoroalkyl ethers include 1,1,2,2-tetrafluoroethyl methyl ether, 2,2,3,3-tetrafluoropropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, bis-(2,2,2-trifluoroethyl) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, methyl nonafluorobutyl ether, bis-(1,1,2,2-tetrafluoroethyl) ether, difluoromethyl-2,2,2-trifluoroethyl ether, 1,1,1,3,3,3-hexafluoro-2(fluoromethoxy)propane, and 1,1,2,3,3,3-pentafluoropropyl-2 At least one of the following: 2,2-trifluoroethyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, 2,2,3,3-tetrafluoro-1-methoxypropane, 1,1,2,3,3,3-pentafluoropropyl ethyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, 1,1,2,3,3,3-hexafluoropropyl methyl ether, ethyl perfluorobutyl ether, ethyl nonafluorobutyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, 1,1,2,3,3,3-pentafluoropropyl-2,2,2-trifluoroethyl ether, 2,2,3,3,3-pentafluoropropyl difluoromethyl ether, and 2,2,2-trifluoroethyl ethyl ether.

15. The battery cell according to claim 13 or 14, characterized in that, Based on the total mass of the electrolyte, the mass percentage of the ether additive is 0.1%-4%.

16. The battery cell according to claim 15, characterized in that, Based on the total mass of the electrolyte, the mass percentage of the ether additive is 0.5%-3%.

17. The battery cell according to any one of claims 1-16, characterized in that, The electrolyte has an ionic conductivity greater than or equal to 0.5 mS / cm.

18. The battery cell according to any one of claims 1-17, characterized in that, The device further includes a positive electrode sheet, which includes a positive current collector and a positive active material layer located on at least one side of the positive current collector. The positive active material layer includes a positive active material, which includes at least one of a sodium-containing polyanionic compound and a sodium-containing layered oxide.

19. The battery cell according to claim 18, characterized in that, The positive electrode active material includes a sodium-containing polyanionic compound.

20. The battery cell according to any one of claims 1-19, characterized in that, The battery cell is a sodium-free negative electrode battery cell.

21. A battery device, characterized in that, The battery device includes the battery cell according to any one of claims 1-20, and the battery device includes at least one of battery module, battery pack, and energy storage device.

22. An electrical appliance, characterized in that, Includes the battery cell as described in any one of claims 1-20.

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