Battery monomer, battery and electric device

Abstract

The embodiment of the invention provides a battery monomer, a battery and an electric device. The battery cell comprises an electrode assembly; an electrolyte; a case for accommodating the electrode assembly and the electrolyte; the battery monomer satisfies the following conditions: aa, the unit is mL / Ah, V total is the maximum volume capable of accommodating the electrolyte in the shell, and the unit is mL; the Vel is the volume of the electrolyte in the shell, and the unit is mL; the V gas is the reference gas production rate of the battery monomer, and the unit is mL; the CAP is the nominal capacity of the single battery, and the unit is Ah. According to the technical scheme, the internal pressure of the battery monomer can be reduced, so that the safety performance of the battery is improved. # imgabs0 #

Description

Battery cells, batteries and electrical devices Technical Field

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

[0002] In recent years, lithium batteries have been used in an increasingly diverse range of applications, including energy storage systems such as electricity, hydropower, thermal power, and solar power plants, as well as in electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. While lithium batteries have experienced significant growth, higher requirements have been placed on their safety and performance.

[0003] Therefore, how to improve the safety performance of batteries is an urgent problem that needs to be solved.

[0004] Summary of the Invention

[0005] The present application is made in view of the above-mentioned problems, and its purpose is to provide a battery cell, a battery and an electrical device that can improve the safety performance of the battery.

[0006] A first aspect of the present application provides a battery cell, comprising: an electrode assembly; an electrolyte; and a housing for accommodating the electrode assembly and the electrolyte; wherein the battery cell satisfies: Unit: mL / Ah, where V 总 is the maximum volume of the electrolyte that can be accommodated in the shell, unit: mL; Vel is the volume of the electrolyte in the shell, unit: mL; V 气 is the gas production of the battery cell, in mL; and CAP is the nominal capacity of the battery cell, in Ah.

[0007] In an embodiment of the present application, a battery cell includes an electrode assembly, an electrolyte, and a casing. The difference between the volume of electrolyte that can be accommodated within the casing, the volume of the electrolyte within the casing, and the gas production of the battery cell is no less than 0.5 times the nominal capacity of the battery cell. That is, after removing the electrolyte and the gas production from the battery cell, 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 no less than 0.5 mL / Ah. By constructing a relationship between the maximum volume of electrolyte that can be accommodated within the battery cell casing, the volume of electrolyte within the battery cell casing, and the gas production of the battery cell, the ratio of the difference between these three to the nominal capacity of the battery cell is no less than 0.5. This allows sufficient space to be reserved for the gas generated by the battery cell and the internal electrolyte during battery cell manufacturing, preventing high pressure inside the battery cell and reducing the possibility of battery explosion, thereby improving battery safety.

[0008] In one possible implementation, the battery cell satisfies: Unit: mL / Ah.

[0009] In the embodiments of this application, to prevent high pressure inside the battery cell housing, sufficient space is reserved 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 5mL / Ah, the internal pressure of the battery cell can be prevented from being too high while maintaining the normal battery capacity.

[0010] In one possible implementation, the battery cell satisfies: Unit: mL / Ah.

[0011] In the embodiment of the present application, by ensuring that the difference between the maximum volume of electrolyte that can be accommodated in the shell and the volume of electrolyte in the battery cell shell and the gas production of the battery cell is no more than twice the nominal capacity of the battery cell, it is possible to avoid the reserved space being too large, thereby affecting the capacity utilization and cycle performance of the battery cell.

[0012] In one possible implementation, the V 气 It is the total amount of gas generated by the battery cell at 25°C, 0.33C constant current and constant voltage charge and discharge cycle for 10 cycles.

[0013] In the embodiment of the present application, V 气 The gas production of the battery cell is measured by charging and discharging the battery cell at 25°C and 0.33C constant current and constant voltage for 10 cycles. 气 , that is, measuring the gas production of the battery in the first ten cycles under standard conditions. The process is simple and the results are accurate.

[0014] In a possible implementation manner, the CAP is not less than 10 Ah.

[0015] In the embodiment of the present application, the capacity of the battery can be guaranteed by ensuring that the nominal capacity of the battery cell is not less than 10 Ah.

[0016] In one possible implementation, the ratio of the Vel to the CAP is 1.5-7.5 mL / Ah, optionally, 2-5 mL / Ah.

[0017] In the embodiment of the present application, by maintaining the ratio of the amount of electrolyte in the shell to the nominal capacity of the battery cell at 1.5-7.5 mL / Ah, especially 2-5 mL / Ah, it is possible to ensure the interface wettability within the battery cell and avoid the increase in battery cost and decrease in energy density caused by unlimited increase in electrolyte.

[0018] In a possible implementation, when the battery cell is a lithium battery, the ratio of the Vel to the CAP is 2-4 mL / Ah, optionally, 2.5-3.5 mL / Ah.

[0019] In the embodiment of the present application, when the battery cell is a lithium battery, the ratio of the amount of electrolyte in the battery cell shell to the nominal capacity of the battery cell is maintained at 2-4 mL / Ah, especially 2.5-3.5 mL / Ah. This can not only ensure the interface wettability within the battery cell, but also avoid the increase in battery cost and decrease in energy density caused by unlimited increase in electrolyte.

[0020] In a possible implementation manner, when the battery cell is a sodium battery, the ratio of the Vel to the CAP is 1.5-5 mL / Ah, optionally, 2-5 mL / Ah.

[0021] In the embodiment of the present application, when the battery cell is a sodium battery, the ratio of the amount of electrolyte in the battery cell shell to the nominal capacity of the battery cell is maintained at 1.5-5 mL / Ah, especially 2-5 mL / Ah. This can not only ensure the interface wettability within the battery cell, but also avoid the increase in battery cost and decrease in energy density caused by unlimited increase in electrolyte.

[0022] In a possible implementation, the battery cell includes an electrode assembly, the electrode assembly includes a negative electrode plate; and the negative electrode plate is an alkali metal negative electrode.

[0023] In the embodiment of the present application, by making the battery cell include a negative electrode plate of an alkali metal, the technical solution of the present application can also be applied to a battery cell with an alkali metal negative electrode.

[0024] A second aspect of the present application provides a battery, comprising the battery cell described in any one of the embodiments of the first aspect of the present application.

[0025] The third aspect of the present application provides an electrical device, comprising the battery described in the second aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0027] FIG1 is a schematic structural diagram of a battery cell according to an embodiment of the present application;

[0028] FIG2 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0029] FIG3 is a schematic structural diagram of a battery according to an embodiment of the present application;

[0030] FIG4 is a schematic structural diagram of an electric device according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] The following describes in detail embodiments of the battery cell, battery, and electrical device of the present application, with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially identical structures may be omitted. Furthermore, the accompanying drawings and the following description are provided to facilitate a thorough understanding of the present application by those skilled in the art and are not intended to limit the subject matter of the claims.

[0032] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of specific range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0034] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0035] Unless otherwise specified, all steps of the present 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 may include steps (b) and (a) performed sequentially. For example, the method may further 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 may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0036] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0037] The terms "above", "below", "greater than" or "less than" as used in this application are inclusive of the number, for example, "at least one" means one or more, and "at least one of A and B" means "A", "B" or "A and B".

[0038] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: 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).

[0039] Alkali metal batteries, such as lithium and sodium batteries, are widely used in consumer electronics due to their 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's understanding of the safety performance of alkali metal batteries has also been continuously improved.

[0040] Existing alkali metal batteries generate a certain amount of gas due to continuous charge and discharge cycles. Excessive gas buildup can lead to excessive internal pressure, bulging, and internal short circuits, compromising battery safety. Therefore, developing large-scale energy storage systems with high safety performance is crucial.

[0041] The battery cell, battery, and electrical device of the present application are described below with reference to the accompanying drawings.

[0042] The battery cells of the present application may be lithium-ion batteries, lithium metal batteries, sodium-ion batteries, etc., which are not limited in the present application. The following description will be made using lithium-ion batteries as an example.

[0043] [Battery Cell]

[0044] The first aspect of the present application provides a battery cell 100. FIG1 is a schematic structural diagram of a battery cell according to an embodiment of the present application. As shown in FIG1 , the battery cell 100 includes: an electrode assembly 11; an electrolyte; and a housing 12 for accommodating the electrode assembly 11 and the electrolyte. The battery cell 100 satisfies: Unit: mL / Ah, where V 总 Vel is the maximum volume of electrolyte that can be accommodated in the shell 12, unit: mL; Vel is the volume of electrolyte in the shell 12, unit: mL; V 气 is the gas production of the battery cell 100, unit: mL; CAP is the nominal capacity of the battery cell 100, unit: Ah.

[0045] The applicant has found that by making the V 总 、Vel、V 气 The ratio of the difference between the three and 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 and prevent the internal pressure of the battery cell 100 from being too high, thereby improving the safety performance of the battery cell 100.

[0046] It should be noted here that V 总 The maximum volume of electrolyte that can be accommodated in the housing 12. This refers to the remaining volume of the housing 12 after removing mechanical components, the electrode assembly 11, and other materials when the battery cell 100 is fully discharged, i.e., when the battery cell 100 is at 0% SOC. Mechanical components include, but are not limited to, connectors and safety components.

[0047] In addition, the nominal capacity of the battery cell 100 refers to the product of the total current that can be output by the 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.

[0048] By constructing a relationship between the maximum volume of electrolyte that can be accommodated in the shell 12 of the battery cell 100, the volume of the electrolyte in the shell 12 of the battery cell 100 and the gas production of the battery cell 100, the ratio of the difference between the three to the nominal capacity of the battery cell 100 is not less than 0.5. In this way, when the battery cell 100 is manufactured, sufficient space can be reserved for the gas generated by the battery cell 100 and the internal electrolyte, preventing the battery cell 100 from being in a high-voltage state 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 can make the relationship universal and normalized.

[0049] In some embodiments, the battery cell 100 satisfies: Unit: mL / Ah.

[0050] In the above solution, to prevent high pressure inside the housing 12 of the battery cell 100, 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, the energy density of the battery cell 100 will be affected. 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, the internal pressure of the battery cell 100 can be prevented from being excessively high while ensuring that the capacity of the battery cell 100 is fully utilized.

[0051] In some embodiments, the battery cell 100 satisfies: Unit: mL / Ah.

[0052] In the above scheme, by ensuring that the difference between the maximum volume of electrolyte that can be accommodated in the shell 12 and the volume of electrolyte in the shell 12 of the battery cell 100 and the gas production of the battery cell 100 is no more than twice the nominal capacity of the battery cell 100, it is possible to avoid the reserved space being too large, thereby affecting the capacity utilization and cycle performance of the battery cell.

[0053] In some embodiments, V 气 It is the total amount of gas generated by the battery cell 100 at 25°C, 0.33C constant current and constant voltage charge and discharge cycle for 10 cycles.

[0054] In the above scheme, V 气 The gas production of the battery cell 100 is measured by charging and discharging the battery cell 100 at 25°C and 0.33C constant current and constant voltage for 10 cycles. 气 , that is, measuring the gas production of the first ten cycles of 100 battery cells under standard conditions. The process is simple and the results are accurate.

[0055] It should be noted here that V 气 It is the amount of gas generated by the battery in a "fresh state" after multiple charge and discharge cycles. The "fresh state" of the battery refers to the state where the SEI film has been formed on the battery but has not yet undergone charge and discharge cycles.

[0056] In addition, V 气 It can also be the total amount of gas generated by 20, 30 or 100 cycles of constant current and constant voltage charge and discharge at 25°C, 0.33C, which is not limited in this application. 气 It can also be the amount of gas generated after the battery cell 100 consumes a certain capacity. The certain capacity can be 10%, 20% or 50%, and this application does not limit this.

[0057] In some embodiments, the CAP is no less than 10 Ah.

[0058] In the above solution, the battery capacity can be guaranteed by ensuring that the nominal capacity of the battery cell 100 is not less than 10 Ah.

[0059] In some embodiments, the ratio of Vel to the CAP is 1.5-7.5 mL / Ah, optionally, 2-5 mL / Ah.

[0060] In the above scheme, by maintaining the ratio of the amount of electrolyte in the shell 12 to the nominal capacity of the battery cell 100 at 1.5-7.5 mL / Ah, especially 2-5 mL / Ah, it is possible to ensure the interface wettability in the battery cell 100 while avoiding the increase in battery cost and reduction in energy density caused by unlimited increase in electrolyte.

[0061] 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.

[0062] In the above scheme, when the battery cell 100 is a lithium battery, the ratio of the amount of electrolyte in the battery cell 100 shell 12 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 not only ensure the interface wettability in the battery cell 100, but also avoid the increase in battery cost and reduction in energy density caused by unlimited increase in electrolyte.

[0063] In some embodiments, when the battery cell 100 is a sodium battery, the ratio of Vel to CAP is 1.5-5 mL / Ah, optionally 2-5 mL / Ah.

[0064] In the above solution, when the battery cell 100 is a sodium battery, the ratio of the amount of electrolyte in the battery cell 100 shell 12 to the nominal capacity of the battery cell 100 is maintained at 1.5-5 mL / Ah, especially 2-5 mL / Ah. This can not only ensure the interface wettability in the battery cell 100, but also avoid the increase in battery cost and reduction in energy density caused by unlimited increase in electrolyte.

[0065] The present application has no 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.

[0066] [Positive electrode]

[0067] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes a positive electrode active material.

[0068] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0069] In some embodiments, the positive electrode 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 material base and a metal layer formed on at least one surface of the polymer material base. 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 material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0070] In some embodiments, the positive electrode active material may adopt the positive electrode active material for batteries that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional 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. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0071] In some embodiments, the positive electrode active material may also include at least one of the following materials: a sodium transition metal oxide, a polyanionic compound, and a Prussian blue compound. However, this application is not limited to these materials; 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.

[0072] In some embodiments, the transition metal in the sodium transition metal oxide may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. For example, the sodium transition metal oxide is Na x MO2, wherein M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0<x≤1.

[0073] In some embodiments, the polyanionic compound may be a compound having sodium ions, transition metal ions and tetrahedral (YO4) 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 polyanionic compound can also be a compound with sodium ions, transition metal ions, tetrahedral (YO4) n- A class of compounds of anion units and halogen anions. 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, and n represents (YO4) n- valence state; the halogen may include at least one of F, Cl and Br.

[0074] In some embodiments, the polyanionic compound may also be a compound having sodium ions, tetrahedral (YO4) n- Anion unit, polyhedron unit (ZO y ) m+ and an optional halogen anion. Y may include at least one of P, S and Si, and n represents (YO4) n-valence state; Z represents a transition metal, including at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, m represents (ZO y ) m+ The halogen may be 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(VO y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0075] Prussian blue compounds can be sodium ions, transition metal ions and cyanide ions (CN - ) compounds. The transition metal may 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' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0<a≤2, 0<b<1, 0<c<1.

[0076] In some embodiments, the positive electrode film layer may further optionally include a conductive agent. 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.

[0077] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0078] The positive electrode sheets herein 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, drying, and cold pressing. The positive electrode slurry is typically formed by dispersing the positive electrode material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring them uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP).

[0079] The positive electrode sheet of the present application does not exclude other additional functional layers in addition to the positive electrode film layer. For example, in some embodiments, the positive electrode sheet of the present application further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) sandwiched between the positive electrode current collector and the positive electrode film layer and disposed on the surface of the positive electrode current collector. In other embodiments, the positive electrode sheet of the present application further includes a protective layer covering the surface of the positive electrode film layer.

[0080] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0081] [Negative electrode]

[0082] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0083] As an example, the negative electrode current collector has two surfaces opposite to each other in its 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.

[0084] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.), or a current collector that combines support capabilities with functional elements, such as carbon cloth, carbon film, carbonaceous, porous current collector, alloyed modified current collector, lithium / sodium-philic modified current collector.

[0085] In some embodiments, the negative electrode plate can be a rolled metal foil or a surface coated with an inert layer of metal powder coated on the current collector; it can be a functional coating negative electrode, such as a carbon material coating (including single-arm, multi-arm conductive carbon tubes, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers, soft carbon and hard carbon, etc.), lithium-philic / sodium-philic metal composite coating, etc.

[0086] In some embodiments, the negative electrode plate is an alkali metal negative electrode. The alkali metal negative electrode can be a current collector with an alkali metal layer pre-applied thereon, or it can be a negative electrode current collector that forms an alkali metal layer on the negative electrode current collector during charge and discharge. This application is not limited to this.

[0087] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. 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, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional 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.

[0088] In some embodiments, the negative electrode film layer may further 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).

[0089] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0090] In some embodiments, the negative electrode film layer may optionally further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0091] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0092] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into the electrode assembly 12 by a winding process or a lamination process.

[0093] In some embodiments, the battery cell 100 may include an outer packaging that can be used to encapsulate the electrode assembly 12 and the electrolyte.

[0094] In some embodiments, the outer packaging of the battery 100 may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the secondary battery may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0095] [Electrolyte]

[0096] The electrolyte plays a role in conducting active ions between the positive electrode and the negative electrode. The electrolyte that can be used in the secondary battery of the present application can be an electrolyte known in the prior art.

[0097] In some embodiments, the electrolyte includes an organic solvent, a sodium electrolyte salt, and optional additives. The types of the organic solvent, the sodium electrolyte salt, and the additives are not particularly limited and can be selected according to needs.

[0098] 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 bisfluorosulfonyl imide (LiFSI, LiN(FSO2)2), lithium bistrifluoromethanesulfonyl imide (LiN(CF3SO2)2), lithium trifluoromethanesulfonate (CF3SO3Li), lithium difluorophosphate (LiPO2F2), lithium difluorooxalatoborate (LiDFOB, LiBC2O4F2), lithium dioxalatoborate (LiBOB, LiB(C2O4)2), lithium difluorodioxalatophosphate (LiDODFP, Li(C2O4)2PF2) and lithium tetrafluorooxalatophosphate (LiOTFP, LiC2O4PF4).

[0099] In some embodiments, as an example, the electrolyte salt may be a sodium salt, including but not limited to at least one of 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.

[0100] In some embodiments, as an example, 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), butylene 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). The above organic solvents can be used alone or in combination. Alternatively, two or more organic solvents are used in combination.

[0101] 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 properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0102] As an example, the additive includes but is not limited to at least one of fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), diethylene sulfate (DTD), propylene sulfate, vinyl sulfite (ES), 1,3-propane sultone (PS), 1,3-propene sultone (PST), sulfonate cyclic quaternary ammonium salt, succinic anhydride, succinonitrile (SN), adiponitrile (AND), tris(trimethylsilyl) phosphate (TMSP), and tris(trimethylsilyl) borate (TMSB).

[0103] The electrolyte solution can be prepared according to conventional methods in the art. For example, an organic solvent, a sodium electrolyte salt, and optional additives can be uniformly mixed to obtain the electrolyte solution. The order in which the materials are added is not particularly limited. For example, the sodium electrolyte salt and the optional additives can be added to the organic solvent and mixed uniformly to obtain the electrolyte solution; alternatively, the sodium electrolyte salt can be first added to the organic solvent, and then the optional additives can be added to the organic solvent and mixed uniformly to obtain the electrolyte solution.

[0104] [Isolation film]

[0105] The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through. This application does not impose any particular restrictions on the type of separator; any known porous separator with good chemical and mechanical stability can be used.

[0106] In some embodiments, the material of the isolation membrane can be selected from one or more of, but not limited to, glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different. In some embodiments, the isolation membrane can also be provided with an organic / inorganic composite coating, including a ceramic particle coating or a metal oxide coating.

[0107] The present application has no particular limitation on the shape of the battery cell 100 , which can be cylindrical, square, or any other shape. For example, FIG2 is a schematic diagram of a battery cell according to an embodiment of the present application.

[0108] Please continue to refer to Figure 1. In some embodiments, the outer packaging may include a shell 12 and a cover plate 13. The shell 12 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The shell 12 has an opening connected to the receiving cavity, and the cover plate 13 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 11 through a winding process or a lamination process. The electrode assembly 11 is encapsulated in the receiving cavity. The number of electrode assemblies 11 contained in the battery cell 100 can be one or more, and those skilled in the art can select according to specific actual needs.

[0109] Figure 3 is a schematic diagram of the structure of a battery 300 according to one embodiment of the present application. As shown in Figure 3 , in battery 300, multiple battery cells 100 may be arranged sequentially along the length of battery 300. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 100 may be secured together using fasteners.

[0110] Continuing with Figure 3 , a 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 body 301 and a lower box body 302. The upper box body 301 can cover the lower box body 302 and form an enclosed space for accommodating the battery cells 100. The plurality of battery cells 100 may be arranged in any manner within the battery box.

[0111] In some embodiments, the battery cells 100 may be assembled into a battery module first. The battery module may contain one or more battery cells 100. The specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0112] In addition, the present application also provides an electric device, which includes at least one of the positive electrode active material, battery cell, or battery provided in the present application. The battery cell or battery can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may include 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., but is not limited thereto.

[0113] For example, FIG4 is a schematic structural diagram of a vehicle according to an embodiment of the present application. As shown in FIG4 , the vehicle 1 can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A motor 400, a controller 600 and a battery 300 can be provided inside the vehicle 1, and the controller 600 is used to control the battery 300 to supply power to the motor 400. For example, a battery 300 can be provided at the bottom, front or rear of the vehicle 1. The battery 300 can be used to power the vehicle 1, for example, the battery 300 can be used as an operating power source for the vehicle 1, for the circuit system of the vehicle 1, for example, for the working power requirements during the start-up, navigation and operation of the vehicle 1. In another embodiment of the present application, the battery 300 can not only be used as an operating power source for the vehicle 1, but also as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0114] As the electrical device, a positive electrode active material, a battery cell or a battery can be selected according to its usage requirements.

[0115] The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the electric device's requirements for high power and high energy density of the battery, a battery cell or a battery can be used.

[0116] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0117] [Example]

[0118] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0119] 1). Preparation of sodium metal batteries

[0120] [Example 1]

[0121] 1.1) Preparation of the positive electrode: Na3V2(PO)4(NVP), conductive agent acetylene black, and binder are dissolved in solvent N-methylpyrrolidone (NMP) in a weight ratio of 97%:1%:2%, and the mixture is thoroughly stirred and mixed to prepare a positive electrode slurry; the positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil, and then dried, cold pressed, and cut to obtain a positive electrode sheet.

[0122] 1.2) Preparation of the negative electrode: Conductive carbon tube dispersion (conductive carbon content 2%) and thickener carbon methyl cellulose sodium (CMC) are thoroughly stirred and mixed in an appropriate amount of deionized water solvent system at a weight ratio of 95%:5%. The slurry viscosity is controlled to 2000-8000mPa·s. The slurry is coated on Cu foil and dried to a thickness of 1μm-20μm to obtain a negative electrode sheet.

[0123] 1.3) Electrolyte: Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of 30%:70% and dissolved in 1M NaPF6.

[0124] 1.4). Diaphragm: 20um PE porous polymer film.

[0125] 1.5) Assembly: Stack the positive electrode sheet, separator, and negative electrode sheet in order, with the separator placed between the positive and negative electrodes to act as a separator. Wind the electrode assembly, place the electrode assembly in a designed housing, and add electrolyte into the housing. Then, hot press at 100°C and 250MPa for 2 minutes to obtain a sodium metal battery; wherein, V 总 is 184mL and Vel is 52.3mL.

[0126] [Example 2]

[0127] The preparation method of the sodium metal battery of Example 2 is the same as that of Example 1, except that Vel is 58.2 mL.

[0128] [Example 3]

[0129] The preparation method of the sodium metal battery of Example 3 is the same as that of Example 1, except that Vel is 61.2 mL.

[0130] [Example 4]

[0131] The preparation method of the sodium metal battery of Example 4 is the same as that of Example 1, except that Vel is 64.1 mL.

[0132] [Example 5]

[0133] The preparation method of the sodium metal battery of Example 5 is the same as that of Example 1, except that Vel is 87.6 mL.

[0134] [Example 6]

[0135] The preparation method of the sodium metal battery of Example 6 is the same as that of Example 1, except that Vel is 111 mL.

[0136] [Example 7]

[0137] The preparation method of the sodium metal battery of Example 7 is the same as that of Example 1, except that Vel is 126 mL.

[0138] [Example 8]

[0139] The preparation method of the sodium metal battery of Example 8 is the same as that of Example 1, except that Vel is 141 mL.

[0140] [Example 9]

[0141] The preparation method of the sodium metal battery of Example 9 is the same as that of Example 1, except that V 总 is 220mL.

[0142] [Comparative Example 1]

[0143] The preparation method of the sodium metal battery of Comparative Example 1 is the same as that of Example 1, except that Vel is 152 mL.

[0144] [Comparative Example 2]

[0145] The preparation method of the sodium metal battery of Comparative Example 2 is the same as that of Example 1, except that Vel is 155 mL.

[0146] 2.) Physical Characterization of Sodium Metal Batteries

[0147] 2.1).V 总 Measurement

[0148] At room temperature, after mechanical parts, electrode components and other materials are placed in the shell, water is poured into the shell until it is full. The volume of water injected is calculated as V 总 .

[0149] 2.2).V 气 Measurement

[0150] Measuring V using the water displacement method 气The specific method is as follows: at room temperature, charge to 3.65V at a constant current and constant voltage of 0.33C, then discharge to 2.5V at a constant current of 0.33C, and repeat 10 times. Connect the sodium metal battery after 10 charge and discharge cycles, the sealed wide-mouth glass bottle No. 1, and the wide-mouth glass bottle No. 2 to the measuring cylinder in turn through the measuring cylinder; among them, the wide-mouth glass bottle No. 1 is an empty bottle, and the wide-mouth glass bottle No. 2 contains liquid, such as water. The volume of liquid collected in the measuring cylinder is V 气 .

[0151] 3.) Performance characterization of sodium metal batteries

[0152] 3.1) Battery internal pressure

[0153] At room temperature, after 200 cycles, a fully charged battery cell was removed and left to rest for 24 hours. A handheld internal stress gauge was then used to pierce the explosion-proof valve with a needle to read the instantaneous pressure. The internal pressure data of the battery was measured. The test results are shown in Figure 1.

[0154] Table 1 Internal pressure of sodium metal batteries of Examples 1-9 and Comparative Examples 1-2 Note: 1.36* means that the explosion-proof valve of the battery exploded before the battery cycle reached 200 cycles.

[0155] According to Examples 1-9 and Comparative Examples 1-2, when the battery (V 总 -Vel-V 气 ) / CAP value is greater than 0.5, the internal pressure of the battery is relatively small; and as (V 总 -Vel-V 气 The larger the value of ) / CAP is, the lower the pressure inside the battery will be, which is beneficial to reduce the probability of battery explosion and improve the safety performance of the battery.

[0156] 3.2) Battery cycle performance

[0157] At room temperature, charge the battery to 3.65V at 0.33C constant current and constant voltage. After 10 minutes, discharge it to 2.5V at 0.33C constant current and constant voltage. Then, let it rest for another 10 minutes. Record the number of cycles when the battery reaches 80% capacity. For the test results, see Table 2.

[0158] Table 2 Cycling performance of sodium metal batteries of Examples 1-9 and Comparative Examples 1-2 Note: 210 cycles* and 100 cycles* mean that the explosion-proof valve exploded before the battery was cycled to 80% of the remaining capacity.

[0159] According to Examples 1-9 and Comparative Examples 1-2, when the battery (V 总 -Vel-V气 When the value of Vel / CAP is greater than 0.5, the internal pressure of the battery is relatively small, and the cycle performance of the battery is better. According to Examples 5-7, when the value of Vel / CAP of the battery is maintained at 2.5-4.5, the cycle performance of the battery is better; according to Examples 1 and 9, when the value of Vel / CAP of the battery is maintained at 2.5-4.5, the cycle performance of the battery is better. 总 -Vel-V 气 When the value of ) / CAP is greater than 5, the cycle performance of the battery is significantly reduced.

[0160] 3.3) Battery capacity utilization

[0161] At room temperature, charge the battery to 3.65V at a constant current and voltage of 0.33C, let it rest for 10 minutes, then discharge it to 2.5V at a constant current of 0.33C, let it rest for another 10 minutes. Calculate the capacity of this cycle. Repeat this cycle five times and take the average of the five capacities. See Table 3 for the test results.

[0162] Table 3 Capacity of sodium metal batteries of Examples 1-9 and Comparative Examples 1-2

[0163] According to 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 capacity.

[0164] According to the above embodiments, by making the battery cell (V 总 -Vel-V 气 ) / CAP value is greater than 0.5, further, (V 总 -Vel-V 气 ) / CAP is greater than 0.5 and less than 5, and Vel / CAP is greater than 2, which can make the battery have both high safety performance and long cycle performance without affecting the normal capacity of the battery.

[0165] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A battery cell, comprising: Electrode assembly; Electrolyte; A housing for containing the electrode assembly and the electrolyte; The battery cell meets the following requirements: Unit: mL / Ah, in, The V 总 The maximum volume of the electrolyte that can be contained in the shell, unit: mL; Vel is the volume of the electrolyte in the shell, unit: mL; The V 气 is the gas production of the battery cell, unit: mL; The CAP is the nominal capacity of the battery cell, in Ah.

2. The battery cell according to claim 1, wherein: The battery cell meets the following requirements: Unit: mL / Ah.

3. The battery cell according to claim 1 or 2, wherein: The battery cell meets the following requirements: Unit: mL / Ah.

4. The battery cell according to any one of claims 1 to 3, wherein: The V 气 It is the total amount of gas generated when the battery cell is charged and discharged for 10 cycles at 0.33C constant current and constant voltage at 25°C.

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

6. The battery cell according to any one of claims 1 to 5, wherein: The ratio of the Vel to the CAP is 1.5-7.5 mL / Ah, optionally, 2-5 mL / Ah.

7. The battery cell according to claim 6, wherein: When the battery cell is a lithium battery, the ratio of the Vel to the CAP is 2-4 mL / Ah, and optionally, 2.5-3.5 mL / Ah.

8. The battery cell according to claim 6, wherein: When the battery cell is a sodium battery, the ratio of the Vel to the CAP is 1.5-5 mL / Ah, optionally, 2-5 mL / Ah.

9. The battery cell according to any one of claims 1 to 8, wherein: The battery cell comprises an electrode assembly, and the electrode assembly comprises a negative electrode plate; The negative electrode plate is an alkali metal negative electrode.

10. A battery, wherein: include: A plurality of battery cells according to any one of claims 1 to 9.

11. An electrical device, wherein: include: The battery as claimed in claim 10, wherein the battery is used in the electrical device to provide electrical energy or store energy.

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