Battery cell, battery, and electric device

Abstract

Embodiments of the present application provide a battery monomer, a battery and a power consuming device. The battery monomer comprises an electrode assembly; an electrolyte; a shell for accommodating the electrode assembly and the electrolyte; the battery monomer satisfies aa, unit: mL / Ah, wherein, the V 总 is the maximum volume of the electrolyte that can be accommodated in the shell, unit: mL; the Vel is the volume of the electrolyte in the shell, unit: mL; the Vgas is the reference gas production of the battery monomer, unit: mL; and the CAP is the nominal capacity of the battery monomer, unit: Ah. The technical solution of the present application can reduce the internal pressure of the battery monomer, thereby improving the safety performance of the battery.

Description

Technical Field

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

[0002] In recent years, lithium batteries have been applied in an increasingly wide range of fields, such as energy storage systems in power, hydropower, thermal power generation, and solar power plants, as well as in electric bicycles, electric motorcycles, electric cars, military equipment, and aerospace. While lithium batteries have achieved tremendous development, higher requirements have also been placed on their safety performance and other aspects.

[0003] Therefore, improving battery safety is an urgent problem that needs to be solved. Summary of the Invention

[0004] This application is made in view of the above-mentioned issues, and its purpose is to provide a battery cell, a battery, and an electrical device that can improve the safety performance of the battery.

[0005] A first aspect of this application provides a battery cell, comprising: an electrode assembly; an electrolyte; and a housing for accommodating the electrode assembly and the electrolyte; the battery cell satisfies the following: Unit: mL / Ah, where V 总 The maximum volume of electrolyte that the casing can hold is expressed in mL; Vel is the volume of electrolyte within the casing, expressed in mL; V 气 The gas production of the battery cell is expressed in mL; CAP is the nominal capacity of the battery cell, expressed in Ah.

[0006] In this embodiment, the battery cell includes an electrode assembly, an electrolyte, and a casing. The difference between the volume of electrolyte that the casing can hold and the volume of electrolyte within the casing plus the gas production of the battery cell is not less than 0.5 times the nominal capacity of the battery cell. That is, after deducting the amount of electrolyte and the gas production, a certain volume remains within the battery cell casing, and the ratio of this remaining volume to the nominal capacity of the battery cell is not less than 0.5 mL / Ah. By establishing a relationship between the maximum volume of electrolyte that the battery cell casing can hold, the volume of electrolyte within the battery cell casing, and the gas production of the battery cell, ensuring that the ratio of the difference between these three to the nominal capacity of the battery cell is not less than 0.5, sufficient space can be reserved during battery cell manufacturing for the gas produced by the battery cell and the internal electrolyte, preventing the battery cell from being under high pressure and reducing the possibility of battery explosion, thereby improving battery safety performance.

[0007] In one possible implementation, the battery cell satisfies: Unit: mL / Ah.

[0008] In this embodiment, to prevent the battery cell casing from being under high pressure, sufficient space is provided for the electrolyte and gas production before the battery cell is used. However, if this reserved space is too large, it will affect the energy density of the battery cell. By ensuring that the ratio of this reserved space to the nominal capacity of the battery cell is no greater than 5 mL / Ah, both excessive internal pressure of the battery cell can be prevented, and the battery's capacity can be maintained at its normal level.

[0009] In one possible implementation, the battery cell satisfies: Unit: mL / Ah.

[0010] In this embodiment, by ensuring that the difference between the maximum volume of electrolyte that can be contained in the casing and the volume of electrolyte in the battery cell casing and the amount of gas produced by the battery cell is no greater than twice the nominal capacity of the battery cell, it is possible to avoid having too much reserved space, which would affect the capacity utilization and cycle performance of the battery cell.

[0011] In one possible implementation, the V 气 The total amount of gas generated by the battery cell during 10 charge-discharge cycles at 25°C and constant current and constant voltage of 0.33C is calculated.

[0012] In this embodiment of the application, V 气 The gas production rate (V) of the battery cell is measured after 10 cycles of constant current and constant voltage charge-discharge at 25°C and 0.33C. 气 This involves measuring the gas production of a battery during its first ten cycles under standard conditions. The process is simple and the results are accurate.

[0013] In one possible implementation, the CAP is not less than 10 Ah.

[0014] In this embodiment of the application, the battery capacity can be guaranteed by ensuring that the nominal capacity of each battery cell is not less than 10Ah.

[0015] In one possible implementation, the ratio of Vel to CAP is 1.5-7.5 mL / Ah, optionally 2-5 mL / Ah.

[0016] In this embodiment of the application, by maintaining the ratio of the amount of electrolyte in the casing to the nominal capacity of the battery cell at 1.5-7.5 mL / Ah, especially 2-5 mL / Ah, the interfacial wettability within the battery cell can be guaranteed, while avoiding the increase in battery cost and the decrease in energy density caused by unlimited addition of electrolyte.

[0017] In one possible implementation, when the battery cell is a lithium battery, the ratio of Vel to CAP is 2-4 mL / Ah, optionally 2.5-3.5 mL / Ah.

[0018] In this embodiment of the application, when the battery cell is a lithium battery, the ratio of the amount of electrolyte in the battery cell casing to the nominal capacity of the battery cell is maintained at 2-4 mL / Ah, especially 2.5-3.5 mL / Ah. This can ensure the interfacial wettability within the battery cell and avoid the increase in battery cost and the decrease in energy density caused by unlimited addition of electrolyte.

[0019] In one possible implementation, when the battery cell is a sodium battery, the ratio of Vel to CAP is 1.5-5 mL / Ah, or optionally 2-5 mL / Ah.

[0020] In this embodiment of the application, when the battery cell is a sodium battery, the ratio of the amount of electrolyte in the battery cell casing to the nominal capacity of the battery cell is maintained at 1.5-5 mL / Ah, especially 2-5 mL / Ah. This can ensure the interfacial wettability within the battery cell and avoid the increase in battery cost and the decrease in energy density caused by unlimited addition of electrolyte.

[0021] In one possible implementation, the battery cell includes an electrode assembly, the electrode assembly including a negative electrode sheet; the negative electrode sheet is an alkali metal negative electrode.

[0022] In this embodiment of the application, by including an alkali metal negative electrode sheet in the battery cell, the technical solution of this application can also be applied to battery cells with alkali metal negative electrodes.

[0023] A second aspect of this application provides a battery comprising a battery cell described in any embodiment of the first aspect of this application.

[0024] A third aspect of this application provides an electrical device including the battery described in the second aspect of this application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a battery cell according to one embodiment of this application;

[0027] Figure 2 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0028] Figure 3 This is a schematic diagram of the structure of a battery according to one embodiment of this application;

[0029] Figure 4 This is a schematic diagram of the structure of an electrical device according to one embodiment of this application. Detailed Implementation

[0030] The following detailed description of embodiments of the battery cell, battery, and power-consuming device of this application, with appropriate reference to the accompanying drawings, may omit unnecessary details. For example, detailed descriptions of commonly known matters and repetitive descriptions of practically identical structures may be omitted. Furthermore, the 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.

[0031] 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 specific 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 expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​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.

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

[0033] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0034] Unless otherwise specified, all steps of 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 method may also include step (c), indicating 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.

[0035] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0036] The terms “above,” “below,” “greater than,” or “less than” used in this application include the number itself, such as “at least one” meaning one or more, and “at least one of A and B” meaning “A,” “B,” or “A and B.”

[0037] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0038] Alkali metal batteries, such as lithium and sodium batteries, are widely used in consumer electronics due to their advantages such as high energy density, high power density, and long cycle life. In recent years, with the continuous development of electric vehicles and energy storage systems, people are also constantly improving the safety performance of alkali metal batteries.

[0039] Existing alkali metal batteries inevitably generate a certain amount of gas due to continuous charge-discharge cycles. Excessive gas levels can lead to excessive internal pressure, battery bulging, and internal short circuits, thus impacting battery safety. Therefore, developing large-scale energy storage systems with high safety performance is of paramount importance.

[0040] The following description, with reference to the accompanying drawings, illustrates the battery cell, battery, and power device of this application.

[0041] The battery cell in this application can be a lithium-ion battery, a lithium metal battery, a sodium-ion battery, etc. This application does not limit the type of battery; the following explanation uses a lithium-ion battery as an example.

[0042] [Battery cell]

[0043] The first aspect of this application provides a battery cell 100. Figure 1 This is a schematic diagram of the structure of a battery cell according to one embodiment of this application, as shown below. Figure 1 As shown, the battery cell 100 includes: an electrode assembly 11; an electrolyte; and a housing 12 for containing the electrode assembly 11 and the electrolyte; the battery cell 100 satisfies the following: Unit: mL / Ah, where V 总 V represents the maximum volume of electrolyte that the casing 12 can hold, in mL; Vel represents the volume of electrolyte within the casing 12, in mL; V 气 CAP represents the gas production of battery cell 100, in mL; CAP represents the nominal capacity of battery cell 100, in Ah.

[0044] The applicant discovered that by making the V of the battery cell 100 总 Vel, V 气 The ratio of the difference between the three to the nominal capacity of the battery cell 100 is not less than 0.5, which can improve the internal pressure of the battery cell 100, prevent the internal pressure of the battery cell 100 from being too high, and thus improve the safety performance of the battery cell 100.

[0045] It should be noted here that V 总 This refers to the maximum volume of electrolyte that the casing 12 can hold. In other words, it is the total remaining volume inside the casing 12 after removing mechanical parts, electrode components 11, and other materials when the battery cell 100 is in a fully discharged state, i.e., at 0% SOC. The mechanical parts include, but are not limited to, connecting pieces and safety structural components.

[0046] In addition, the nominal capacity of battery cell 100 refers to the product of the total current output by battery cell 100 when it is fully charged and discharged at a constant current and constant voltage of 0.33C to the termination voltage, and the discharge time.

[0047] By establishing a relationship between the maximum volume of electrolyte that can be contained within the casing 12 of the battery cell 100, the volume of electrolyte within the casing 12 of the battery cell 100, and the gas production of the battery cell 100, the ratio of the difference between these three to the nominal capacity of the battery cell 100 is not less than 0.5. This allows sufficient space to be reserved for the gas and internal electrolyte produced by the battery cell 100 during manufacturing, preventing the battery cell 100 from being under high pressure and reducing the possibility of battery explosion, thereby improving the safety performance of the battery cell 100. At the same time, expressing the relationship as the ratio of volume to nominal capacity makes the relationship universal and standardized.

[0048] In some implementations, the battery cell 100 satisfies: Unit: mL / Ah.

[0049] In the above scheme, to prevent the battery cell 100 from being under high pressure inside the casing 12, sufficient space is reserved for the electrolyte and gas production before the battery cell 100 is used. However, if this reserved space is too large, it will affect the energy density of the battery cell 100. By ensuring that the ratio of this reserved space to the nominal capacity of the battery cell 100 is no greater than 5 mL / Ah, both excessive internal pressure in the battery cell 100 and normal capacity utilization of the battery cell 100 can be guaranteed.

[0050] In some implementations, the battery cell 100 satisfies: Unit: mL / Ah.

[0051] In the above scheme, by ensuring that the difference between the maximum volume of electrolyte that can be contained in the casing 12 and the volume of electrolyte in the casing 12 of the battery cell 100 and the amount of gas produced by the battery cell 100 is no more than twice the nominal capacity of the battery cell 100, it is possible to avoid having too much reserved space, which would affect the capacity utilization and cycle performance of the battery cell.

[0052] In some implementations, V 气 This refers to the total amount of gas generated by a single battery cell (100 cells) during 10 charge-discharge cycles at 25°C and constant current / constant voltage (0.33C).

[0053] In the above scheme, V 气 The gas production rate (V) of battery cell 100 is measured after 10 cycles of constant current and constant voltage charge-discharge at 25°C and 0.33C. 气 This involves measuring the gas production of a single battery cell during the first ten cycles under standard conditions. The process is simple and the results are accurate.

[0054] It should be noted here that V 气 This refers to the amount of gas produced by a battery after multiple charge-discharge cycles in its "fresh state." The "fresh state" of a battery refers to a state in which the SEI film has been formed but the battery has not yet undergone charge-discharge cycles.

[0055] Additionally, V 气 The total amount of gas generated can also be accumulated over 20, 30, or 100 constant current and constant voltage charge-discharge cycles at 25°C and 0.33°C; this application does not limit this. 气 It can also be the amount of gas produced by the battery cell 100 after a certain capacity has been consumed. This certain capacity can be 10%, 20%, or 50%, and this application does not limit it.

[0056] In some implementations, CAP is not less than 10 Ah.

[0057] In the above scheme, the battery capacity can be guaranteed by ensuring that the nominal capacity of the battery cell 100 is not less than 10Ah.

[0058] In some embodiments, the ratio of Vel to CAP is 1.5-7.5 mL / Ah, and optionally, it is 2-5 mL / Ah.

[0059] In the above scheme, by keeping the ratio of the amount of electrolyte in the casing 12 to the nominal capacity of the battery cell 100 at 1.5-7.5 mL / Ah, especially 2-5 mL / Ah, the interfacial wettability within the battery cell 100 can be guaranteed, while avoiding the increase in battery cost and the decrease in energy density caused by unlimited addition of electrolyte.

[0060] In some embodiments, when the battery cell 100 is a lithium battery, the ratio of Vel to CAP is 2-4 mL / Ah, optionally 2.5-3.5 mL / Ah.

[0061] In the above scheme, when the battery cell 100 is a lithium battery, the ratio of the electrolyte volume in the casing 12 of the battery cell 100 to the nominal capacity of the battery cell 100 is maintained at 2-4 mL / Ah, especially 2.5-3.5 mL / Ah. This can ensure the interfacial wettability within the battery cell 100 and avoid the increase in battery cost and the decrease in energy density caused by unlimited addition of electrolyte.

[0062] In some embodiments, when the battery cell 100 is a sodium battery, the Vel to CAP ratio is 1.5-5 mL / Ah, or optionally 2-5 mL / Ah.

[0063] In the above scheme, when the battery cell 100 is a sodium battery, the ratio of the electrolyte volume in the casing 12 of the battery cell 100 to the nominal capacity of the battery cell 100 is maintained at 1.5-5 mL / Ah, especially 2-5 mL / Ah. This can ensure the interfacial wettability within the battery cell 100 and avoid the increase in battery cost and the decrease in energy density caused by unlimited addition of electrolyte.

[0064] This application does not impose any particular restrictions on the type of battery. It can be a sodium battery, such as a sodium metal battery or a sodium ion battery; it can also be a lithium battery, such as a lithium metal battery or a lithium ion battery; or it can be a ternary polymer battery, such as an NCM system, etc.

[0065] [Positive electrode plate]

[0066] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0067] As an example, the positive current collector has 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 current collector.

[0068] 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.).

[0069] In some embodiments, the positive electrode active material may be a known battery positive electrode active material. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0070] In some embodiments, the positive electrode active material may also include at least one of the following materials: 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.

[0071] In some embodiments, the transition metal in the sodium transition metal oxide can be at least one selected from Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. For example, the sodium transition metal oxide is Na. x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0 < x ≤ 1.

[0072] 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. The transition metal 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 may include at least one of F, Cl and Br.

[0073] In some embodiments, the polyanionic compound may also be a tetrahedral compound containing sodium ions (YO4). 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, which may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and 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).

[0074] Prussian blue compounds can 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.

[0075] In some embodiments, the positive electrode film 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.

[0076] In some embodiments, the positive electrode film 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.

[0077] The positive electrode sheet in this application can be prepared according to conventional methods in the art. For example, the positive electrode film layer is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is typically formed by dispersing the positive electrode material, optional conductive agent, optional binder, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to it.

[0078] The positive electrode sheet of this application does not exclude additional functional layers besides the positive electrode film layer. For example, in some embodiments, the positive electrode sheet of this application further includes a conductive undercoat layer (e.g., composed of a conductive agent and a binder) sandwiched between the positive current collector and the positive electrode film layer and disposed on the surface of the positive current collector. In other embodiments, the positive electrode sheet of this application further includes a protective layer covering the surface of the positive electrode film layer.

[0079] 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.

[0080] [Negative electrode plate]

[0081] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0082] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0083] 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 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 (copper, copper 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.), or a current collector that combines supporting capacity and functional elements, such as carbon cloth, carbon film, carbonaceous material, porous current collector, alloy-modified current collector, and lithium-philic / sodium-modified current collector.

[0084] In some embodiments, the negative electrode sheet can be a rolled metal foil or a metal powder coated with an inert layer on the surface and applied to the current collector; it can be a negative electrode with a functional coating, such as a carbon material coating (including single-arm, multi-arm 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-philic / sodium-philic metal composite coating, etc.

[0085] In some embodiments, the negative electrode is an alkali metal negative electrode. This alkali metal negative electrode can be formed by pre-depositing an alkali metal layer on the surface of the current collector, or it can be a negative current collector on which an alkali metal layer is generated during charging and discharging. This application does not limit this specific embodiment.

[0086] In some embodiments, the negative electrode active material may be a 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, tin-based materials, and lithium titanate, 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.

[0087] In some embodiments, the negative electrode film layer may optionally include a binder. 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).

[0088] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0089] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0090] 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, 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.

[0091] In some embodiments, the positive electrode, negative electrode, and separator can be fabricated into electrode assembly 12 by a winding process or a stacking process.

[0092] In some embodiments, the battery cell 100 may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly 12 and the electrolyte.

[0093] In some embodiments, the outer packaging of battery 100 can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery 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.

[0094] Electrolyte

[0095] The electrolyte acts as a conductor of active ions between the positive and negative electrodes. The electrolyte used in the secondary battery of this application can be any electrolyte known in the prior art.

[0096] 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.

[0097] In some embodiments, as an example, the electrolyte salt may be a lithium salt, including at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(FSO2)2), lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2), lithium trifluoromethanesulfonate (CF3SO3Li), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiDFOB, LiBC2O4F2), lithium dioxalate borate (LiBOB, LiB(C2O4)2), lithium difluorodioxalate phosphate (LiDODFP, Li(C2O4)2PF2), and lithium tetrafluorooxalate phosphate (LiOTFP, LiC2O4PF4).

[0098] In some embodiments, as an example, the electrolyte salt may also be a sodium salt, including but not limited to at least one selected from NaPF6, NaClO4, NaBCl4, NaSO3CF3, and Na(CH3)C6H4SO3. One of the sodium salts may be used alone, or two or more may be used simultaneously.

[0099] In some embodiments, as examples, the organic solvent includes, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), fluoroethylene carbonate (FEC), 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.

[0100] 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.

[0101] As an example, 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).

[0102] 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.

[0103] [Isolation membrane]

[0104] The separator is positioned between the positive and negative electrodes, primarily serving to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through. This application does not impose any particular restriction on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0105] In some embodiments, the material of the separator can be selected from one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride, but is not limited to these. The separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. In some embodiments, an organic / inorganic composite coating, including a ceramic particle coating or a metal oxide coating, can also be provided on the separator.

[0106] This application does not impose any particular limitation on the shape of the battery cell 100; it can be cylindrical, square, or any other shape. For example, Figure 2 A schematic diagram of a battery cell according to one embodiment of this application.

[0107] Please continue to refer to Figure 1 In some embodiments, the outer packaging may include a housing 12 and a cover 13. The housing 12 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 12 has an opening communicating with the receiving cavity, and the cover 13 can be placed over the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator may be formed into an electrode assembly 11 by a winding process or a stacking process. The electrode assembly 11 is encapsulated within the receiving cavity. The number of electrode assemblies 11 contained in the battery cell 100 may be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0108] Figure 3 This is a schematic diagram of the structure of a battery 300 according to one embodiment of this application. Figure 3 As shown, in the battery 300, multiple battery cells 100 can be arranged sequentially along the length of the battery 300. Of course, they can also be arranged in any other manner. Furthermore, the multiple battery cells 100 can be fixed in place using fasteners.

[0109] Please continue to refer to Figure 3 The battery 300 may include a battery box and a plurality of battery cells 100 disposed within the battery box. The battery box includes an upper box 301 and a lower box 302, the upper box 301 covering the lower box 302 to form a closed space for accommodating the battery cells 100. The plurality of battery cells 100 may be arranged in any manner within the battery box.

[0110] In some embodiments, the battery cells 100 can be assembled into a battery module. The number of battery cells 100 contained in the battery module 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 module.

[0111] In addition, this application also provides an electrical device, which includes at least one of the positive electrode active material, battery cell, or battery provided in this application. The battery cell or battery 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.

[0112] For example, Figure 4 This is a structural schematic diagram of a vehicle according to one embodiment of this application. For example... Figure 4 As shown, vehicle 1 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A motor 400, a controller 600, and a battery 300 can be installed inside vehicle 1. The controller 600 controls the battery 300 to supply power to the motor 400. For example, the battery 300 can be installed at the bottom, front, or rear of vehicle 1. The battery 300 can be used to power vehicle 1; for example, it can serve as the operating power source for the vehicle 1's electrical system, such as for the power requirements of starting, navigation, and operation. In another embodiment of this application, the battery 300 can not only serve as the operating power source for vehicle 1 but also as the driving power source, replacing or partially replacing gasoline or natural gas to provide driving power to vehicle 1.

[0113] As the electrical device, the positive electrode active material, battery cell or battery can be selected according to its usage requirements.

[0114] The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the battery, battery cells or batteries can be used.

[0115] 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.

[0116] [Example]

[0117] 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.

[0118] 1) Preparation of sodium metal batteries

[0119] [Example 1]

[0120] 1.1) Preparation of positive electrode: Na3V2(PO)4 (NVP), conductive agent acetylene black, and binder are dissolved in N-methylpyrrolidone (NMP) at a weight ratio of 97%:1%:2% and thoroughly mixed to prepare a positive electrode slurry; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0121] 1.2) Preparation of negative electrode: The conductive carbon tube dispersion (conductive carbon content 2%) and the thickener sodium carboxymethyl cellulose (CMC) are thoroughly mixed in an appropriate amount of deionized water solvent system at a weight ratio of 95%:5%. The viscosity of the slurry is controlled at 2000-8000 mPa·s. The mixture is then coated on Cu foil and dried, with the thickness controlled at 1µm-20µm to obtain the negative electrode sheet.

[0122] 1.3) Electrolyte: Ethyl carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 30%:70% and dissolved in 1M NaPF6.

[0123] 1.4) Separator: 20µm PE porous polymer film.

[0124] 1.5) Assembly: Stack the positive electrode, separator, and negative electrode in sequence, with the separator positioned between the positive and negative electrodes for isolation. Wind the electrodes to obtain the electrode assembly. Place the electrode assembly into the designed housing and add electrolyte inside. Then, hot-press at 100℃ and 250MPa for 2 minutes to obtain the sodium metal battery; wherein, V 总 The volume was 184 mL, and the Vel volume was 52.3 mL.

[0125] [Example 2]

[0126] The sodium metal battery in Example 2 was prepared in the same way as in Example 1, except that the Vel was 58.2 mL.

[0127] [Example 3]

[0128] The sodium metal battery in Example 3 was prepared in the same way as in Example 1, except that the Vel was 61.2 mL.

[0129] [Example 4]

[0130] The sodium metal battery in Example 4 was prepared using the same method as in Example 1, except that the Vel was 64.1 mL.

[0131] [Example 5]

[0132] The sodium metal battery in Example 5 was prepared in the same way as in Example 1, except that the Vel was 87.6 mL.

[0133] [Example 6]

[0134] The sodium metal battery in Example 6 was prepared in the same way as in Example 1, except that the Vel was 111 mL.

[0135] [Example 7]

[0136] The sodium metal battery in Example 7 was prepared using the same method as in Example 1, except that the Vel was 126 mL.

[0137] [Example 8]

[0138] The sodium metal battery in Example 8 was prepared using the same method as in Example 1, except that the Vel was 141 mL.

[0139] [Example 9]

[0140] The preparation method of the sodium metal battery in Example 9 is the same as that in Example 1, except that V 总 It is 220mL.

[0141] [Comparative Example 1]

[0142] The sodium metal battery of Comparative Example 1 was prepared in the same way as that of Example 1, except that the Vel was 152 mL.

[0143] [Comparative Example 2]

[0144] The sodium metal battery of Comparative Example 2 was prepared in the same way as that of Example 1, except that the Vel was 155 mL.

[0145] 2.) Physical characterization of sodium metal batteries

[0146] 2.1).V 总 Measurement

[0147] At room temperature, after assembling all the mechanical parts, electrode components, and other materials into the housing, water is poured into the housing until it is full. The volume of water poured in is V. 总 .

[0148] 2.2).V 气 Measurement

[0149] Measure V using the displacement method 气The specific method is as follows: At room temperature, charge the sodium metal battery to 3.65V using a constant current and constant voltage of 0.33C, then discharge it to 2.5V using a constant current of 0.33C, repeating this process 10 times. Connect the sodium metal battery (after 10 charge-discharge cycles), a sealed wide-mouth glass bottle (No. 1), and a wide-mouth glass bottle (No. 2) sequentially through a graduated cylinder. Bottle No. 1 is empty, while bottle No. 2 contains liquid, such as water. The volume of liquid collected in the graduated cylinder is V. 气 .

[0150] 3.) Performance Characterization of Sodium Metal Batteries

[0151] 3.1) Internal pressure of the battery

[0152] At room temperature, after the battery cells have undergone 200 cycles, they are removed from the fully charged state and left to stand for 24 hours. Then, using a handheld internal stress gauge, the instantaneous pressure is read by piercing the explosion-proof valve with a needle. The test results are shown in [link to test data]. Figure 1 .

[0153] Table 1 Internal pressures of sodium metal batteries in Examples 1-9 and Comparative Examples 1-2

[0154]

[0155]

[0156] Note: 1.36* indicates that the explosion-proof valve burst before the battery reached 200 cycles.

[0157] As can be seen from Examples 1-9 and Comparative Examples 1-2, when the battery's (V) 总 -Vel-V 气 When the CAP value is greater than 0.5, the internal pressure of the battery is relatively low; and as (V 总 -Vel-V 气 The larger the CAP value, the lower the internal pressure of the battery, which helps to reduce the probability of battery explosion and improve battery safety performance.

[0158] 3.2) Battery cycle performance

[0159] At room temperature, charge the battery to 3.65V at a constant current and constant voltage of 0.33C, let it rest for 10 minutes, then discharge it to 2.5V at a constant current and constant voltage of 0.33C, and let it rest for another 10 minutes. Record the number of cycles when the battery reaches 80% capacity. Please refer to Table 2 for the test results.

[0160] Table 2 Cycle performance of sodium metal batteries in Examples 1-9 and Comparative Examples 1-2

[0161]

[0162]

[0163] Note: 210 cycles* and 100 cycles* indicate that the battery will not be circulated to 80% of its remaining capacity before an explosion-proof test is initiated.

[0164] Valve rupture.

[0165] As can be seen from Examples 1-9 and Comparative Examples 1-2, when the battery's (V) 总 -Vel-V 气 When the Vel / CAP value is greater than 0.5, the internal pressure of the battery is relatively low, and the battery cycle performance is better. According to Examples 5-7, when the Vel / CAP value of the battery is maintained between 2.5 and 4.5, the battery cycle performance is even better; according to Examples 1 and 9, when the (V... 总 -Vel-V 气 When the CAP value is greater than 5, the cycle performance of the battery is significantly reduced.

[0166] 3.3) Battery capacity utilization

[0167] At room temperature, charge the capacitor to 3.65V at a constant current and constant voltage of 0.33C, let it rest for 10 minutes, then discharge it to 2.5V at a constant current of 0.33C, and let it rest for another 10 minutes. Calculate the capacity of this cycle. Repeat this cycle 5 times and take the average of the 5 capacities. Please refer to Table 3 for the test results.

[0168] Table 3. Capacity utilization of sodium metal batteries in Examples 1-9 and Comparative Examples 1-2

[0169]

[0170] As can be seen from Examples 1-9 and Comparative Examples 1-2, when the Vel / CAP value of the sodium battery is maintained at 2-5, especially 2.5-4.7, the internal pressure of the battery can be reduced without affecting the battery's capacity.

[0171] As can be seen from the above embodiments, by making the battery cell (V 总 -Vel-V 气 If the value of ) / CAP is greater than 0.5, then further, (V 总 -Vel-V 气 A Vel / CAP value greater than 0.5 and less than 5, and a Vel / CAP value greater than 2, can enable the battery to achieve both high safety performance and long cycle performance without affecting its normal capacity.

[0172] 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, comprising: an electrode assembly; an electrolyte; a housing for containing the electrode assembly and the electrolyte; the battery cell satisfies: , in mL / Ah, wherein, The V 总 is the maximum volume of the electrolyte that can be accommodated in the housing, in mL; The Vel V is the volume of the electrolyte in the housing, in mL; The V 气 Gas production of the battery cell, unit: mL; The CAP Cn is the nominal capacity of the battery cell in Ah.

2. The battery cell of claim 1, wherein, the battery cell satisfies: , in mL / Ah.

3. The battery cell of claim 1 or 2, wherein, the battery cell satisfies: , in mL / Ah.

4. The battery cell of any one of claims 1 to 3, wherein, The V 气 The total amount of gas generated by the battery cell at 25°C under constant current and constant voltage charging and discharging at 0.33C for 10 cycles in total.

5. The battery cell of any one of claims 1 to 4, wherein, The CAP not less than 10 Ah.

6. The battery cell of any one of claims 1 to 5, wherein, The Vel With the CAP The ratio is 1.5-7.5 mL / Ah.

7. The battery cell of any one of claims 1 to 5, wherein, The Vel The ratio of the specific surface area to the specific capacity of the CAP 2-5 mL / Ah.

8. The battery cell of claim 6 or 7, wherein, In case the battery cell is a lithium battery, the Vel The ratio of the specific capacity of the CAP is 2-4 mL / Ah.

9. The battery cell of claim 6 or 7, wherein, In the case where the battery cell is a lithium battery, the Vel The ratio of the volume of the electrolyte solution to the CAP is 2.5-3.5 mL / Ah.

10. The battery cell of claim 6 or 7, wherein, In the case where the battery cell is a sodium battery, the Vel The ratio of the specific surface area of the CAP is 1.5-5 mL / Ah.

11. The battery cell of claim 6 or 7, wherein, In case the battery cell is a sodium battery, the Vel The ratio of the specific capacity of the CAP is 2-5 mL / Ah.

12. The battery cell of any one of claims 1-11, wherein, the battery cell comprises an electrode assembly, the electrode assembly comprising a negative electrode; the negative electrode is an alkali metal negative electrode.

13. A battery, wherein, comprising: a plurality of battery cells as claimed in any one of claims 1 to 12.

14. An electrical device, comprising: comprising: a battery as claimed in claim 13, the battery being used in the electrical device to provide electrical energy or to store energy.

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