Metal battery and electric device

Abstract

A metal battery and an electric device. The metal battery comprises a positive electrode sheet, a negative electrode sheet and an electrolyte, wherein the positive electrode sheet comprises a positive electrode film layer; the positive electrode film layer comprises a binder and a positive electrode active material; the positive electrode active material comprises a metal element; and on the basis of the total mass of the positive electrode film layer, the fluorine content of the positive electrode sheet is less than or equal to 385 ppm. During the charging process, metal ions are removed from the positive electrode active material, and the metal ions are reduced into and deposited as metal on the negative electrode sheet; and during the discharging process, the metal is oxidized into and dissolved as the metal ions. The difference between the lowest unoccupied molecular orbital energy level, i.e., LUMO2 energy level, of the solvent of the electrolyte and the lowest unoccupied molecular orbital energy level, i.e., LUMO1 energy level, of the metal state corresponding to the metal element in the positive electrode active material is y=LUMO2 energy level-LUMO1 energy level, where 0≤y. The metal battery has a relatively good discharge gram capacity and initial coulombic efficiency.

Description

Metal battery and powered device

[0001] Cross-reference to related applications

[0002] This application is based on the Chinese Patent Application No. 202410947172.3 filed on July 15, 2024, entitled “Metal battery and powered device”, which is incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of secondary batteries, in particular to a metal battery and a powered device. BACKGROUND

[0004] In recent years, secondary batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. Compared with traditional secondary batteries, metal batteries gradually enter people's field of vision due to their higher charge-discharge rate performance. In order to meet people's demand for electricity, it is of great significance to further improve the discharge gram capacity and the first coulomb efficiency of metal batteries. SUMMARY

[0005] The present application is made in view of the above-mentioned problems, and aims to solve at least one of the technical problems existing in the prior art. To this end, the present application provides a metal battery and a powered device. The metal battery of the present application has good discharge gram capacity and excellent first coulomb efficiency.

[0006] The first aspect of the present application provides a metal battery, the metal battery comprising a positive electrode sheet, a negative electrode sheet and an electrolyte, the positive electrode sheet comprising a positive electrode film layer, the positive electrode film layer comprising a binder and a positive electrode active material, the positive electrode active material comprising a metal element, and the fluorine content of the positive electrode sheet being less than or equal to 385 ppm based on the total mass of the positive electrode film layer.

[0007] During charging, the positive electrode active material releases metal ions, and the metal ions are reduced and deposited as metal at the negative electrode sheet. During discharging, the metal is oxidized and dissolved as metal ions.

[0008] The difference between the lowest unoccupied molecular orbital energy level LUMO2 of the solvent of the electrolyte and the lowest unoccupied molecular orbital energy level LUMO1 of the metal state corresponding to the metal element in the positive electrode active material is y = LUMO2 - LUMO1, and 0 ≤ y.

[0009] The metal element in the metal battery positive electrode active material can be stripped to form metal ions, such as sodium ions or lithium ions, which are reduced and deposited as metal on the negative electrode plate. Further, the metal can be oxidized and dissolved into metal ions, and the process is repeated to complete the charging and discharging process. The solvent of the electrolyte has a suitable LUMO energy level relationship with the metal state corresponding to the metal element in the positive electrode active material, which reduces the degree of side reaction with the negative electrode metal, thereby being more suitable for the negative electrode and helping to improve the electrical performance of the metal battery.

[0010] Meanwhile, the present application finds that the fluorine-containing substances in the positive electrode plate, such as fluorine-containing binders, are easy to dissolve in the solvent of the electrolyte of the present application. The dissolved fluorine-containing substances generally have a free capacity and can pass through the separator to the negative electrode plate side. The metal on the negative electrode plate is easy to react with the fluorine-containing group in the fluorine-containing substance, thereby causing the metal on the negative electrode to be consumed, which in turn reduces the discharge gram capacity of the metal battery. By controlling the fluorine content of the positive electrode plate to be less than or equal to 385 ppm, the present application helps to reduce the concentration of fluorine-containing substances in the electrolyte, thereby reducing the degree of side reaction with the negative electrode metal, helping to further reduce metal consumption, and thereby improving the discharge gram capacity and the first coulombic efficiency of the metal battery.

[0011] In any embodiment, the fluorine content of the positive electrode plate is less than or equal to 120 ppm based on the total mass of the positive electrode film layer.

[0012] When the fluorine content of the positive electrode plate of the present application is further reduced, it is helpful to further reduce the fluorine-containing substances dissolved in the electrolyte solvent, thereby reducing the side reaction with the negative electrode metal, reducing the metal loss, and further improving the discharge gram capacity and the first coulombic efficiency of the metal battery of the present application.

[0013] In any embodiment, 0.7≤y.

[0014] Further controlling the difference between the lowest unoccupied molecular orbital energy level of the metal state corresponding to the metal element in the positive electrode active material and the solvent of the electrolyte is helpful to further improve the compatibility of the electrolyte and the negative electrode, and to improve the discharge gram capacity and the first coulombic efficiency of the metal battery of the present application.

[0015] In any embodiment, the binder includes a first binder, and the first binder is a copolymer and / or a homopolymer, and in the monomers of the copolymer and the homopolymer, the substitution group of the fluorine element is less than or equal to 2.

[0016] In the positive electrode tab of the present application, the fluorine-containing substance that is easy to dissolve in the electrolyte solvent is mainly the binder. Controlling the amount of fluorine-containing substituents in the binder helps to balance the binding performance of the binder and reduce the amount of fluorine-containing groups dissolved in the electrolyte solvent, thereby helping to further reduce the side reaction of fluorine-containing groups with the negative metal, reduce metal loss, and further improve the discharge gram capacity and the first coulombic efficiency of the metal battery of the present application.

[0017] In any embodiment, the first binder includes at least one of a methyl methacrylate monomer copolymer and / or homopolymer, a saccharide monomer copolymer and / or homopolymer, an acrylic acid monomer copolymer and / or homopolymer, a styrene monomer copolymer and / or homopolymer, a butadiene monomer copolymer and / or homopolymer, a phenol monomer copolymer and / or homopolymer, an aldehyde monomer copolymer and / or homopolymer, a diatomic amine monomer copolymer and / or homopolymer, a diatomic anhydride monomer copolymer and / or homopolymer, a benzene ring monomer copolymer and / or homopolymer, or a derivative thereof, a modified product thereof.

[0018] In any embodiment, the first binder includes at least one of a polymethyl methacrylate, a carboxymethyl cellulose, a polyacrylic acid, a sodium alginate, a styrene-butadiene rubber, a polyvinyl alcohol, a phenolic resin, a polyimide, a styrene monomer-butadiene monomer-styrene monomer block copolymer, or a derivative thereof, a modified product thereof.

[0019] In any embodiment, the binder includes at least one of a carboxymethyl cellulose, a polyacrylic acid, a polyimide, a styrene monomer-butadiene monomer-styrene monomer block copolymer, or a derivative thereof, a modified product thereof.

[0020] When the binder includes the first binder of the above-mentioned type, better binding performance for forming the positive electrode film layer can be provided. At the same time, the amount of fluorine contained in the above-mentioned first binder meets the requirements of the present application, and specifically, when the positive electrode film layer includes the above-mentioned first binder, the amount of fluorine contained in the positive electrode tab meets the requirements of the present application. The application of the first binder of the above-mentioned type in the positive electrode film layer of the present application helps to further reduce the amount of fluorine-containing groups in the electrolyte solvent, thereby helping to further reduce the side reaction of fluorine-containing groups with the negative metal, reduce metal loss, and further improve the first coulombic efficiency of the metal battery of the present application. Among them, when the binder is selected from a styrene monomer-butadiene monomer-styrene monomer block copolymer, the metal battery of the present application has more excellent discharge gram capacity and first coulombic efficiency.

[0021] In any embodiment, the binder includes a second binder, and the second binder includes a fluorine-containing monomer copolymer and / or homopolymer.

[0022] When the fluorine content of the positive electrode tab of the present application is less than or equal to 385 ppm, the binder of the present application can also include a second binder of a fluorine-containing copolymer and / or homopolymer. Supplementing the second binder of the above type in the binder helps to increase the binding performance of the binder.

[0023] In any embodiment, the mass ratio of the first binder and the second binder is (1-0.5):(0-0.5).

[0024] In any embodiment, when the mass ratio of the first binder and the second binder is greater than or equal to 0.5:0.5, less than 0.6:0.4, the mass percentage content of the binder is less than or equal to 2%, greater than or equal to 0.5% based on the total mass of the positive electrode film layer; and / or

[0025] When the mass ratio of the first binder and the second binder is greater than or equal to 0.6:0.4, less than 0.7:0.3, the mass percentage content of the binder is less than or equal to 2.5%, greater than or equal to 0.5% based on the total mass of the positive electrode film layer; and / or

[0026] When the mass ratio of the first binder and the second binder is (1-0.7):(0-0.3), the mass percentage content of the binder is less than or equal to 3%, greater than or equal to 0.5% based on the total mass of the positive electrode film layer.

[0027] Controlling the first binder and the second binder within a suitable range helps to further balance the binding performance of the binder and the discharge gram capacity and the first coulomb efficiency of the metal battery of the present application.

[0028] In any embodiment, the mass percentage content of the binder is less than or equal to 3%, greater than or equal to 0.5% based on the total mass of the positive electrode film layer.

[0029] Controlling the content of the binder within a suitable range helps to provide suitable binding performance while reducing the fluorine content of the positive electrode tab. It helps to further reduce the capacity deterioration of the metal battery of the present application and improve its first coulomb efficiency.

[0030] In any embodiment, the electrolyte includes a solvent and a sodium salt dissolved in the solvent, and the solvent includes at least one ether compound of formula I, R1-(O-R3) n -O-R2 (I)

[0031] wherein R1 and R2 are each independently selected from C1-C6 alkyl, R3 is selected from C1-C6 alkylene, and n is selected from an integer from 1 to 5.

[0032] Unlike the ester solvents commonly used, the electrolyte solvent of the above general formula meets the LUOM energy level definition of the present application and has good compatibility with the negative electrode.

[0033] In any embodiment, R1 and R2 are each independently selected from methyl or ethyl, and R3 is selected from a linear C1-C5 alkylene group.

[0034] In any embodiment, R3 is selected from -CH2CH2-.

[0035] When the electrolyte of the metal battery of the present application has the above-mentioned solvent, the electrolyte of the metal battery of the present application has a more stable electrolyte window.

[0036] In any embodiment, the solvent comprises at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, pentaethylene glycol diethyl ether, or ethylene glycol dibutyl ether.

[0037] When the electrolyte of the metal battery of the present application has the above-mentioned solvent, the electrolyte of the present application has more excellent reduction stability, and has better interface compatibility with the negative electrode of the metal battery, especially the sodium metal battery.

[0038] In any embodiment, the sodium salt comprises at least one of NaPF6, NaFSI, NaTFSI, NaBF4, NaClO4, or NaOTf.

[0039] When the electrolyte comprises the above-mentioned sodium salt, it is helpful to further improve the conductivity of the electrolyte.

[0040] In any embodiment, the negative electrode tab is an inert material that does not participate in electrochemical reactions, and the negative electrode tab comprises a negative electrode current collector.

[0041] When the metal battery is a negative electrode-free metal battery, the electron transfer is only completed by the metal formed by the reduction and deposition of metal ions stripped from the positive electrode active material on the surface of its current collector. Therefore, the consumption of the metal deposited on the negative electrode tab of the negative electrode-free metal battery has a greater impact on the discharge gram capacity and the initial coulombic efficiency of the metal battery. When the negative electrode tab of the metal battery of the present application is an inert material that does not participate in electrochemical reactions, i.e., a negative electrode-free negative electrode tab, the design of the fluorine content of the positive electrode tab of the present application helps to better improve the discharge gram capacity and the initial coulombic efficiency of the metal battery, i.e., compared to the metal negative electrode metal battery, the design of the fluorine content of the positive electrode tab of the present application has a more beneficial improvement effect on the discharge gram capacity and the initial coulombic efficiency of the negative electrode-free metal battery.

[0042] In any embodiment, the negative electrode tab comprises a porous layer formed on the surface of the negative electrode tab, and the porous layer has micrometer, sub-micrometer, or nanometer level pores.

[0043] The porous layer has a large specific surface area, which is conducive to providing a larger deposition specific surface area for metal ions released from the positive active material, making the deposition of metal ions on the negative electrode sheet more uniform, effectively reducing the generation of negative electrode dendrites. In addition, the porous layer is also conducive to shortening the migration distance of metal ions during charging and discharging, and is conducive to reducing the diffusion resistance problem existing in the reaction process.

[0044] In any embodiment, the porous layer comprises a carbon-based material.

[0045] In any embodiment, the carbon-based material comprises at least one of carbon black, activated carbon, carbon nanotubes, carbon fibers, or graphite.

[0046] When the porous layer comprises a carbon-based material, the negative electrode sheet has more excellent electronic conductivity, and at the same time, the surface of the carbon-based material generally has functional groups such as -COOH and -OH, which have better affinity for metals, especially sodium metal, so that a more optimal deposition morphology can be formed.

[0047] In any embodiment, the negative electrode sheet comprises a negative electrode current collector and a negative active material disposed on at least one surface of the negative electrode current collector, and the negative active material comprises at least one of lithium, sodium, zinc, iron, chromium, manganese, tin, aluminum, copper, nickel, or alloys thereof, oxides thereof.

[0048] The fluorine content of the positive electrode sheet of the present application is also applicable to metal negative electrode metal batteries, i.e., batteries in which the negative electrode sheet comprises at least one negative active material of lithium, sodium, zinc, iron, chromium, manganese, tin, aluminum, copper, nickel, or alloys thereof, oxides thereof.

[0049] In any embodiment, the negative electrode current collector comprises a metal current collector, a carbon-based material current collector, a stainless steel current collector, or a composite current collector.

[0050] In any embodiment, the metal battery comprises at least one of a sodium metal battery and a lithium metal battery.

[0051] Sodium metal batteries and lithium metal batteries have good electrical properties. In ordinary sodium metal batteries and lithium metal batteries, because lithium metal and sodium metal have a certain reactivity, fluorine-containing groups dissolved in the electrolyte solvent are prone to side reactions with sodium metal / lithium metal on the negative electrode sheet, causing sodium loss / lithium loss and reducing the capacity of the lithium metal battery / sodium metal battery. By controlling the amount of fluorine in the positive electrode sheet of the lithium metal battery / sodium metal battery, the amount of fluorine-containing groups in the electrolyte solvent is effectively reduced, and the degree of side reaction with the negative electrode metal is reduced. The metal battery of the present application, especially the sodium metal battery, has good capacity and first coulombic efficiency.

[0052] In any embodiment, the positive active material comprises at least one of a polyanionic compound, a layered oxide, a Prussian blue type compound, or a modified compound thereof.

[0053] In any embodiment, the positive active material comprises Na a1 Ni b1 Fe c1 Mn d1 M1 e1 O f1 , Na x1 M2 y1 M3 y2 (X a2 O b2 ) z1 Z w1 , Prussian blue, Prussian white, or a modified compound thereof, wherein,

[0054] M comprises at least one of an active or / and an inert doping metal element, 0.85≤a1≤1, 0≤b1≤1, 0≤c1≤1, 0≤d1≤1, 0≤e1≤1, 1.8≤f1≤2, b1, c1, d1 and e1 are not 0 at the same time;

[0055] M2 comprises at least one of Ti, V, Cr, Mn, Fe, Ca, Mg, Al, Nb, Co, Zr, M3 comprises Ni, X comprises at least one of Si, S, P, As, B, Mo, W, Ge, Z comprises at least one of F, O, OH, 1≤x1≤7, 1≤y1≤4, 0≤y2≤0.05, 0.2≤a2 / b2≤0.3, 1≤z1≤4, 0≤w1≤7.

[0056] Since the chemical property of sodium is more active, when the metal battery of the present application is a sodium metal battery, the design of the fluorine content of the positive electrode sheet of the present application is more obvious in improving the consumption of the negative sodium metal. Compared with the traditional sodium metal battery, the sodium metal battery of the present application has better discharge capacity and first coulomb efficiency.

[0057] In any embodiment, the first coulomb efficiency of the metal battery is greater than or equal to 90%.

[0058] The second aspect of the present application provides a method for preparing the metal battery of the present application.

[0059] The third aspect of the present application provides a power utilization device, which comprises the metal battery of the present application or the metal battery prepared according to the method of the present application.

[0060] The above description is only a summary of the technical solutions of the present application. In order to enable one skilled in the art to better understand the technical means of the present application and to implement the same according to the contents of the description, and in order to enable the above and other purposes, characteristics and advantages of the present application to be more apparent and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0061] FIG. 1 is a schematic view of a secondary battery according to an embodiment of the present application.

[0062] FIG. 2 is an exploded view of the secondary battery according to an embodiment of the present application shown in FIG. 1.

[0063] FIG. 3 is a schematic view of a battery module according to an embodiment of the present application.

[0064] FIG. 4 is a schematic view of a battery pack according to an embodiment of the present application.

[0065] FIG. 5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 4.

[0066] FIG. 6 is a schematic view of an electrical device using the secondary battery according to an embodiment of the present application as a power source.

[0067] REFERENCE NUMERALS DESCRIPTION: 1: battery pack; 2: upper case; 3: lower case; 4: battery module; 5: secondary battery; 51: case; 52: electrode assembly; 53: top cap assembly. DETAILED DESCRIPTION

[0068] Hereinafter, embodiments of the positive electrode active material and the method of manufacturing the same, the positive electrode sheet, the secondary battery, the battery module, the battery pack, and the electrical device according to the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there can be cases where unnecessary detailed descriptions are omitted. For example, there can be cases where detailed descriptions of matters well known in the art, repeated descriptions of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0069] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0070] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0071] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0072] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0073] 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.

[0074] If not specifically stated, 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, any of the following satisfy the condition "A or B": 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).

[0075] Compared with traditional secondary batteries, metal batteries gradually enter the field of vision due to better charge-discharge rate performance. However, metal batteries still need to be further improved due to poor first coulomb efficiency. The fluorine content of the positive electrode sheet is reasonably designed in the application, which effectively improves the capacity and first coulomb efficiency of the metal battery.

[0076] [metal battery]

[0077] Based on this, the application provides a metal battery, the metal battery of the application comprises a positive electrode sheet, a negative electrode sheet and an electrolyte, the positive electrode sheet comprises a positive electrode film layer, the positive electrode film layer comprises a binder and a positive electrode active material, the positive electrode active material comprises a metal element, and the fluorine content of the positive electrode sheet is less than or equal to 385 ppm based on the total mass of the positive electrode film layer as a calculation basis;

[0078] During the charging process, the positive electrode active material releases metal ions, and the metal ions are reduced and deposited as metal on the negative electrode sheet, and during the discharging process, the metal is oxidized and dissolved as metal ions;

[0079] The difference between the lowest unoccupied molecular orbital energy level LUMO2 of the solvent of the electrolyte and the lowest unoccupied molecular orbital energy level LUMO1 of the metal state corresponding to the metal element in the positive electrode active material is y=LUMO2-LUMO1, 0≤y.

[0080] As used herein, the term "lowest unoccupied molecular orbital energy level" or "LUMO energy level" refers to the energy level of the molecular orbital with the lowest energy. The LUMO energy level is numerically equivalent to the electron affinity of the molecule, and the lower the LUMO energy level, the easier it is for the substance to obtain electrons, which can be used to judge the reduction resistance of the substance, and the lower the energy level, the easier it is to be reduced.

[0081] Whether the positive electrode tab contains fluorine element can be measured by methods and devices known in the art. For example, it can be detected by infrared spectroscopy. Specifically, the infrared light beam is transmitted through the surface of the positive electrode tab to a depth of zero microns (ATR is Ge crystal), for example 700 nm, the percentage transmittance of infrared light versus wave number curve is recorded to obtain the infrared spectrum, and the infrared spectrum is analyzed to determine whether the positive electrode tab contains fluorine. The obtained infrared spectrum can be analyzed for functional groups according to the national standard GB / T6040-2002 General Rules for Infrared Spectroscopy Analysis Method. Further, the fluorine content of the positive electrode tab can be detected by inductively coupled plasma (ICP) test, which can be specifically referred to YS / T1006.2-2014, GB / T23367.2-2009 or YS / T1028.5-2015, using inductively coupled plasma emission spectrometer (iCAP 740), and measuring according to the instrument instruction to obtain the fluorine content of the positive electrode tab.

[0082] The lowest unoccupied molecular orbital energy level of the material can be obtained by methods known in the art, for example, it can be obtained according to first principle theoretical calculation, which can be specifically referred to Diphenyl Ketone towards Ultra-stable Hard Carbon Anodes for Sodium-Ion Batteries (Angewandte Chemie, 2022. DOI: 10.1002 / anie.202214717), and is calculated by using density functional theory (DFT). As an example, the theoretical calculation is based on Gaussian 09 software and is performed by using Becke three-parameter-Lee-Yang-Parr (B3LYP) hybrid functional. In order to obtain accurate geometric structure, no symmetry constraint is applied during the structure optimization process. The convergence thresholds of energy and force are 1.0×10-5 a.u. and 1.0×10-3 a.u. per atom, respectively. The basis set is 6-31G(d). and In addition, the atomic properties are represented by 6-311+G(d) basis set. The dispersion-corrected density functional theory (DFT-D2) calculation is performed using Vienna ab initio simulation package (VASP), which adopts generalized gradient approximation (GGA) and Perdew-Burke-Eznerhof (PBE) functional (GGA-PBE) to describe the exchange correlation energy of electrons. The interaction between atomic nucleus and electron is handled by using projected augmented wave method (PAW). The k points on the Brillouin zone are 5×5×1, and the energy cutoff is 400 eV. The atomic positions and cell vectors are fully optimized until all force components are less than 0.01 eV / Å. According to the above simulation calculation method, the LUMO energy level of the material can be obtained.

[0083] During the charging and discharging process, the extraction of metal ions from the positive active material and the reduction deposition and oxidation dissolution process of the metal ions on the negative electrode sheet can be detected by methods and devices known in the art. For example, the test can be performed by using X-ray photoelectron spectroscopy (XPS). Specifically, the unformed negative electrode and the fully charged negative electrode containing the plating layer are detected by XPS, the valence state of the metal element, such as sodium element, is analyzed, the ionic state and the metallic state of the metal element are identified, and it is determined whether the redox reaction occurs.

[0084] In some embodiments, the metal element includes a sodium element. In some embodiments, the metal element includes a lithium element.

[0085] In some embodiments, the metal ion includes a sodium ion. In some embodiments, the metal ion includes a lithium ion.

[0086] In some embodiments, during the charging process, the metal element is extracted from the positive active material to form metal ions, the metal ions are reduced and deposited as metal on the negative electrode sheet, and during the discharging process, the metal is oxidized and dissolved as metal ions.

[0087] In some embodiments, the metallic state of the metal element refers to the elemental form with a valence of 0. In some specific embodiments, the metallic state of the sodium metal element refers to sodium metal, and the metallic state of the lithium metal element refers to lithium metal.

[0088] The metal element in the positive active material of the metal battery is extracted to form metal ions, such as sodium ions or lithium ions, which are reduced and deposited as metal on the negative electrode sheet. Further, the metal can be oxidized and dissolved as metal ions, and the cycle is repeated to complete the charging and discharging process. The solvent of the electrolyte has a suitable LUMO energy level relationship with the metallic state of the metal element in the positive active material, which reduces the degree of side reaction with the negative metal, thereby being more suitable for the negative electrode and helping to improve the electrical performance of the metal battery. At the same time, it is found that the fluorine-containing substance in the positive electrode sheet, such as the fluorine-containing binder, is easily dissolved in the electrolyte solvent of the present application. The dissolved fluorine-containing substance generally has a free capacity and can pass through the separator to the negative electrode sheet. The metal on the negative electrode sheet is easily reduced with the fluorine-containing group in the fluorine-containing substance, which causes the metal on the negative electrode to be consumed, thereby reducing the discharge gram capacity of the metal battery. By controlling the fluorine content of the positive electrode sheet to be less than or equal to 385 ppm, the concentration of the fluorine-containing substance in the electrolyte solvent is reduced, thereby reducing the degree of side reaction of the negative metal, helping to reduce metal consumption, and further improving the discharge gram capacity and the first coulombic efficiency of the metal battery.

[0089] In some embodiments, the fluorine content of the positive electrode sheet is less than or equal to 120 ppm based on the total mass of the positive electrode film layer.

[0090] In some embodiments, the fluorine content of the cathode sheet can be 385 ppm, 375 ppm, 365 ppm, 355 ppm, 345 ppm, 335 ppm, 325 ppm, 315 ppm, 300 ppm, 285 ppm, 265 ppm, 245 ppm, 225 ppm, 205 ppm, 185 ppm, 165 ppm, 145 ppm, 125 ppm, 120 ppm, 105 ppm, 85 ppm, 65 ppm, 45 ppm, 25 ppm, 15 ppm, 0 ppm, or a value within a range defined by any two of the foregoing fluorine contents, based on the total mass of the cathode film layer.

[0091] When the fluorine content of the cathode sheet of the present application is further reduced, the amount of fluorine-containing substances dissolved in the electrolyte solvent is further reduced, thereby reducing the degree of side reactions of the negative electrode metal, reducing metal loss, and further improving the discharge gram capacity and the initial coulombic efficiency of the metal battery of the present application.

[0092] In some embodiments, 0.7≤y.

[0093] In some embodiments, 0.1≤y, 0.2≤y, 0.3≤y, 0.4≤y, 0.5≤y, 0.6≤y, or 0.7≤y.

[0094] Further controlling the difference between the metal state corresponding to the metal element in the cathode active material and the lowest unoccupied molecular orbital energy level of the solvent of the electrolyte is beneficial to further improve the compatibility of the solvent of the electrolyte and the negative electrode, and improve the discharge gram capacity and the initial coulombic efficiency of the metal battery of the present application.

[0095] In some embodiments, the binder includes a first binder, and the first binder is a copolymer and / or a homopolymer, and in the monomers of the copolymer and the homopolymer, the number of substituents of fluorine elements is less than or equal to 2.

[0096] As used herein, the term "copolymer" refers to a polymer formed by two or more monomers participating in a polymerization reaction, which includes two or more monomer units. According to the arrangement of monomers in the copolymer molecular chain, the copolymer can be divided into random copolymer, alternating copolymer, block copolymer and graft copolymer.

[0097] As used herein, the term "homopolymer" refers to a polymer formed by polymerization of one monomer.

[0098] As used herein, the term "polymer" includes on the one hand a collection of macromolecules that are chemically uniform but differ in the degree of polymerization, molar mass, and chain length, which are prepared by polymerization reactions. The term also includes on the other hand derivatives of such a collection of macromolecules formed by polymerization reactions, i.e. compounds that can be obtained by reaction, e.g. addition or substitution, of functional groups in the above macromolecules and can be chemically uniform or chemically non-uniform.

[0099] In some embodiments, the first binder is a copolymer, and in monomers of the copolymer, the number of substituents containing fluorine elements is less than or equal to 2.

[0100] In some embodiments, in monomers of the copolymer, the number of substituents containing fluorine elements can be 2, 1 or 0.

[0101] In some embodiments, the first binder is a homopolymer, and in monomers of the homopolymer, the number of substituents containing fluorine elements is less than or equal to 2.

[0102] In some embodiments, in monomers of the homopolymer, the number of substituents containing fluorine elements can be 2, 1 or 0.

[0103] In the positive electrode tab of the present application, the fluorine-containing substance that is easy to dissolve in the electrolyte solvent is mainly the binder. Controlling the number of fluorine-containing substituents in the binder helps to balance the binding performance of the binder and reduce the number of fluorine-containing groups dissolved in the electrolyte, thereby helping to further reduce the degree of side reactions of the negative metal, reduce metal loss, and further improve the discharge gram capacity and the first coulombic efficiency of the metal battery of the present application.

[0104] In some embodiments, the first binder includes at least one of a methyl methacrylate monomer copolymer and / or homopolymer, a saccharide monomer copolymer and / or homopolymer, an acrylic acid monomer copolymer and / or homopolymer, a styrene monomer copolymer and / or homopolymer, a butadiene monomer copolymer and / or homopolymer, a vinyl alcohol monomer copolymer and / or homopolymer, a phenol monomer copolymer and / or homopolymer, an aldehyde monomer copolymer and / or homopolymer, a diatomic amine monomer copolymer and / or homopolymer, a diatomic anhydride monomer copolymer and / or homopolymer, a benzene ring monomer copolymer and / or homopolymer, or a derivative thereof, a modified product thereof.

[0105] In some embodiments, the first binder includes at least one of a methyl methacrylate monomer homopolymer, a saccharide monomer homopolymer, a mannuronic acid monomer and guluronic acid monomer copolymer, an acrylic acid monomer homopolymer, a styrene monomer and butadiene monomer copolymer, a vinyl alcohol monomer homopolymer, a phenol monomer and aldehyde monomer copolymer, a diamine monomer and dianhydride monomer copolymer, or a benzene ring monomer copolymer. In some embodiments, the first binder includes at least one of a methyl methacrylate monomer homopolymer, an acrylic acid monomer homopolymer, a diamine monomer and dianhydride monomer copolymer, or a benzene ring monomer copolymer.

[0106] In some embodiments, the first binder includes at least one of polymethyl methacrylate (PMMA), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), sodium alginate (SA), styrene butadiene rubber (SBR), polyvinyl alcohol (PVA), phenol formaldehyde resin, polyimide (PI), styrene monomer-butadiene monomer-styrene monomer block copolymer (SBS), or a derivative thereof, a modified material thereof.

[0107] In some embodiments, the first binder includes at least one of carboxymethyl cellulose, polyacrylic acid, polyimide, styrene monomer-butadiene monomer-styrene monomer block copolymer, or a derivative thereof, a modified material thereof.

[0108] As used herein, the term "derivative" refers to a substance derived from an original molecule by substituting a group, such as a hydrogen atom, on the original molecule with another group.

[0109] As used herein, the term "modified material" refers to a substance formed by further modifying an original molecule by different means, such as physical or chemical means, to change some physical or chemical properties thereof.

[0110] In some embodiments, the weight average molecular weight of the binder is 30-2 million.

[0111] In some embodiments, the weight average molecular weight of the binder can be 30 million, 50 million, 70 million, 90 million, 100 million, 120 million, 140 million, 160 million, 180 million, 200 million, or a value within a range composed of any two of the above weight average molecular weights.

[0112] When the binder includes the first binder of the above type, good binding performance for forming the positive electrode film layer can be provided. Meanwhile, the fluorine content of the first binder described above meets the needs of the present application, and specifically, when the positive electrode film layer includes the first binder described above, the fluorine content of the positive electrode sheet meets the needs of the present application. The application of the first binder of the above type in the positive electrode film layer of the present application helps to further reduce the amount of fluorine-containing groups in the electrolyte solvent, thereby helping to further reduce the degree of side reactions of the negative metal, reduce metal loss, and further improve the first coulombic efficiency of the metal battery of the present application. Among them, when the first binder is selected from styrene monomer-diene monomer-styrene monomer block copolymer, the metal battery of the present application has more excellent discharge gram capacity and first coulombic efficiency.

[0113] In some embodiments, the binder includes a second binder, the second binder including a fluorine-containing monomer copolymer and / or homopolymer.

[0114] In some embodiments, the second binder includes at least one of a vinylidene fluoride monomer copolymer and / or homopolymer, a hexafluoropropylene monomer copolymer and / or homopolymer, a fluorovinyl monomer copolymer and / or homopolymer, a trifluoroethylene monomer copolymer and / or homopolymer, a perfluoromethyl isopropyl ether monomer homopolymer and / or copolymer, a tetrafluoroethylene monomer copolymer and / or homopolymer, a fluorovinyl ester monomer copolymer and / or homopolymer, a methyl methacrylate monomer copolymer and / or homopolymer, a fluorostyrene monomer copolymer or fluorobenzene monomer copolymer and / or homopolymer, or a derivative thereof, a modification thereof.

[0115] In some embodiments, the second binder includes at least one of a vinylidene fluoride monomer copolymer and / or homopolymer, a hexafluoropropylene monomer copolymer, a fluorovinyl monomer copolymer, a trifluoroethylene monomer copolymer, a perfluoromethyl isopropyl ether monomer homopolymer, a tetrafluoroethylene monomer copolymer, a fluorovinyl ester monomer copolymer, a methyl methacrylate monomer copolymer, a fluorostyrene monomer copolymer or fluorobenzene monomer copolymer, or a derivative thereof, a modification thereof.

[0116] In some embodiments, the second binder includes at least one of a vinylidene fluoride, a polyvinylidene fluoride-hexafluoropropylene, a polyfluorovinyl-trifluoroethylene, a polyperfluoromethyl isopropyl ether, a polyvinylidene fluoride-tetrafluoroethylene, a polyacrylic acid-fluorovinyl ester, a polymethyl methacrylate-fluorostyrene, a polystyrene-fluorostyrene, a polyester-fluorovinyl ester, a polyimide-fluorobenzene, or a derivative thereof, a modification thereof.

[0117] In some embodiments, the second binder includes a vinylidene fluoride (PVDF).

[0118] When the fluorine content of the positive electrode tab of the present application is less than or equal to 385 ppm, the binder of the present application can also include a second binder of a fluorine-containing copolymer and / or homopolymer. Supplementing the second binder of the above type in the binder helps to increase the binding performance of the binder.

[0119] In some embodiments, the mass ratio of the first binder and the second binder is (1-0.5):(0-0.5).

[0120] In some embodiments, the mass ratio of the first binder and the second binder can be 1:0, 0.9:0.1, 0.8:0.2, 0.7:0.3, 0.6:0.4, or 0.5:0.5.

[0121] Controlling the first binder and the second binder within a suitable range helps to further balance the binding performance of the binder and the discharge specific capacity and the first coulombic efficiency of the metal battery of the present application.

[0122] In some embodiments, the mass percentage of the binder is less than or equal to 3% and greater than or equal to 0.5% based on the total mass of the positive electrode film layer.

[0123] In some embodiments, the mass percentage of the binder can be 3%, 2.5%, 2%, 1.5%, 1%, 0.5%, or a value within a range consisting of any two of the above mass percentages, based on the total mass of the positive electrode film layer.

[0124] In some embodiments, when the mass ratio of the first binder and the second binder is greater than or equal to 0.5:0.5 and less than 0.6:0.4, the mass percentage of the binder is less than or equal to 2% and greater than or equal to 0.5% based on the total mass of the positive electrode film layer.

[0125] In some embodiments, when the mass ratio of the first binder and the second binder is greater than or equal to 0.6:0.4 and less than 0.7:0.3, the mass percentage of the binder is less than or equal to 2.5% and greater than or equal to 0.5% based on the total mass of the positive electrode film layer.

[0126] In some embodiments, when the mass ratio of the first binder and the second binder is (1-0.7):(0-0.3), the mass percentage of the binder is less than or equal to 3% and greater than or equal to 0.5%.

[0127] Controlling the content of the binder within a suitable range helps to provide suitable binding performance while reducing the fluorine content of the positive electrode tab. This helps to further reduce the capacity deterioration of the metal battery of the present application and improve its first coulombic efficiency.

[0128] [Electrolyte]

[0129] In some embodiments, the electrolyte comprises a solvent and a sodium salt dissolved in the solvent, the solvent comprising at least one ether compound of Formula I, R1-(0-R3) n -O-R2 (I)

[0130] wherein R1and R2are each independently selected from C1-C6alkyl, R3is selected from C1-C6alkylene, and n is selected from an integer from 1 to 5.

[0131] As used herein, the term "C1-C6alkyl" refers to a straight or branched chain hydrocarbon chain radical consisting solely of carbon and hydrogen atoms, no unsaturation, having from one to six carbon atoms, and attached to the rest of the molecule by a single bond. The terms "C1-C5alkyl", "C1-C4alkyl", "C1-C3alkyl", "C1-C2alkyl" are to be interpreted accordingly. Examples of C1-C6alkyl include, but are not limited to: methyl, ethyl, n-propyl, 1-methylethyl (iso-propyl), n-butyl, n-pentyl, or 1,1-dimethylethyl (tert-butyl).

[0132] As used herein, the term "C1-C6alkylene" refers to a C1-C6divalent alkyl radical. Any alkyl radical can generate an alkylene radical by the loss of one hydrogen atom from a carbon that creates a hemiacetal bond. The terms "C1-C5alkylene", "C1-C4alkylene", "C1-C3alkylene", "C1-C2alkylene" are to be interpreted accordingly. Examples of C1-C6alkylene include, but are not limited to: -CH2-, -CH(CH3)-, -C(CH3)2-, -CH2CH2-, -CH2-CH(CH3)-, -CH2C(CH3)2-, -CH2CH2CH2-, -CH2CH2CH2CH2-.

[0133] In some embodiments, R1and R2are each independently selected from C6alkyl, C5alkyl, C4alkyl, C3alkyl, ethyl group, or methyl group. In some embodiments, R1and R2are each independently selected from methyl, ethyl, n-propyl, iso-propyl, 1-methylethyl (iso-propyl), n-butyl, n-pentyl, or 1,1-dimethylethyl (tert-butyl). In some embodiments, R1and R2are each independently selected from methyl or ethyl.

[0134] In some embodiments, R3is selected from C6alkylene, C5alkylene, C4alkylene, C3alkylene, ethylene, or methylene. In some embodiments, R3is selected from -CH2-, -CH(CH3)-, -C(CH3)2-, -CH2CH2-, -CH2-CH(CH3)-, -CH2C(CH3)2-, -CH2CH2CH2-, -CH2CH2CH2CH2-.

[0135] In some embodiments, R3 is selected from a linear C1-C5 alkylene group. In some embodiments, R3 is selected from a linear C6 alkylene group, a linear C5 alkylene group, a linear C4 alkylene group, a linear C3 alkylene group, a linear C2 alkylene group, or a linear C1 alkylene group.

[0136] In some embodiments, n is selected from 1, 2, 3, 4, or 5.

[0137] Different from the commonly used ester electrolyte solvent, the electrolyte solvent of the above general formula meets the LUOM energy level defined in the present application, and has good compatibility with the negative electrode.

[0138] In some embodiments, R1 and R2 are each independently selected from a methyl group or an ethyl group, and R3 is selected from a linear C1-C5 alkylene group.

[0139] In some embodiments, R3 is selected from -CH2CH2-.

[0140] When the solvent of the present application has the above structure, the electrolyte of the present application has a relatively stable structural basis, and can provide a more stable electrochemical window.

[0141] In some embodiments, the solvent includes at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, pentaethylene glycol diethyl ether, or ethylene glycol dibutyl ether.

[0142] When the solvent of the electrolyte of the metal battery of the present application has the above solvent, the electrolyte of the present application can have better reduction stability and better compatibility with the alkali metal negative electrode.

[0143] In some embodiments, the sodium salt includes at least one of NaPF6, NaFSI, NaTFSI, NaBF4, NaClO4, or NaOTf.

[0144] When the electrolyte includes the above sodium salt, it is helpful to further improve the conductivity of the electrolyte.

[0145] In some embodiments, the electrolyte can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive capable of improving certain performance of the battery, such as an additive for improving the overcharge performance of the battery, an additive for improving the high-temperature or low-temperature performance of the battery, etc.

[0146] [Negative electrode sheet]

[0147] In some embodiments, the negative electrode sheet is an inert material that does not participate in an electrochemical reaction, and the negative electrode sheet includes a negative electrode current collector.

[0148] As used herein, the term "negative electrode tab-free" refers to a negative electrode tab that is pre-deposited with no active material layer and forms a deposited metal on the surface of the negative electrode tab by the first operation.

[0149] When the metal battery is a negative electrode tab-free metal battery, the electron transfer is completed only by the metal formed by the reduction deposition of metal ions stripped from the positive electrode active material on the surface of its current collector. Therefore, the consumption of the deposited metal on the negative electrode tab of the negative electrode tab-free metal battery has a greater impact on the discharge gram capacity and the first coulombic efficiency of the metal battery. When the negative electrode tab of the metal battery of the present application is an inert material that does not participate in the electrochemical reaction, i.e., a negative electrode tab-free negative electrode tab, the design of the fluorine content of the positive electrode tab of the present application helps to better improve the discharge gram capacity and the first coulombic efficiency of the metal battery, i.e., compared to the metal negative electrode metal battery, the design of the fluorine content of the positive electrode tab of the present application has a more beneficial improvement effect on the discharge gram capacity and the first coulombic efficiency of the negative electrode tab-free metal battery.

[0150] In some embodiments, the negative electrode tab comprises a porous layer formed on the surface of the negative electrode tab, the porous layer having micrometer, sub-micrometer or nanometer scale pores.

[0151] As used herein, the term "micrometer scale" refers to an average diameter of the pores being 1-999 micrometers.

[0152] As used herein, the term "sub-micrometer scale" refers to an average diameter of the pores being 0.1-1 micrometer. In some specific embodiments, the sub-micrometer scale overlaps with the nanometer scale, which can be understood in light of the specific circumstances.

[0153] As used herein, the term "nanometer scale" refers to an average diameter of the pores being 1-999 nanometers. In some specific embodiments, the nanometer scale overlaps with the sub-micrometer scale, which can be understood in light of the specific circumstances.

[0154] In some embodiments, the thickness of the porous layer is 0.05-1 mm.

[0155] In some embodiments, the thickness of the porous layer can be 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, or a value within a range defined by any two of the above thicknesses.

[0156] In some embodiments, the micrometer or sub-micrometer scale pores account for 50-95% of the volume of the porous layer. In some embodiments, the micrometer or sub-micrometer scale pores account for 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or a value within a range between any two of the aforementioned values.

[0157] In some embodiments, the nanometer scale pores account for 10-99% of the volume of the porous layer. In some embodiments, the nanometer scale pores account for 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, or a value within a range between any two of the aforementioned values.

[0158] The porous layer has a large specific surface area, which is conducive to providing a larger deposition specific surface area for metal ions released from the positive active material, so that the metal ions are more uniformly deposited on the negative electrode sheet, effectively reducing the generation of negative electrode dendrites. In addition, the porous layer is also conducive to shortening the migration distance of metal ions during charging and discharging, and is conducive to reducing the diffusion resistance problem existing in the reaction process.

[0159] In some embodiments, the porous layer comprises a carbon-based material.

[0160] In some embodiments, the carbon-based material comprises at least one of carbon black, activated carbon, carbon nanotubes, carbon fibers, or graphite.

[0161] When the porous layer comprises a carbon-based material, it is conducive to improving the surface electronic conductivity. At the same time, the surface of the carbon-based material generally has functional groups such as carboxyl and hydroxyl groups, which have better affinity for metal deposition, such as sodium metal, so that a better deposition morphology can be formed.

[0162] In some embodiments, the carbon-based material comprises activated carbon. In some embodiments, the activated carbon comprises activated carbon felt or activated carbon fiber cloth.

[0163] Activated carbon has a porous structure and has a large specific surface area, and is relatively inexpensive.

[0164] In some embodiments, the carbon-based material comprises carbon black. In some embodiments, the carbon black comprises Ketjen black.

[0165] Ketjen black has a large specific surface area and good adsorption capacity, which helps the metal ions to be more uniformly deposited on the negative electrode sheet.

[0166] In some embodiments, the negative electrode tab includes a negative current collector and a negative active material disposed on at least one surface of the negative current collector, the negative active material including at least one of lithium, sodium, zinc, iron, chromium, manganese, tin, aluminum, copper, nickel, or an alloy thereof, an oxide thereof.

[0167] As used herein, the term "alloy" refers to a solid product having metallic properties obtained by mixing and melting one metal with another or several metals or non-metals, and then cooling and solidifying.

[0168] As used herein, the term "oxide" refers to a compound composed of two elements, one of which is oxygen. Specifically, when the other element is a metal element, the resulting oxide is a metal oxide.

[0169] The amount of fluorine in the positive electrode tab of the present application is also applicable to metal negative metal batteries, i.e., batteries in which the negative electrode tab includes at least one negative active material of lithium, sodium, zinc, iron, chromium, manganese, tin, aluminum, copper, nickel, or an alloy thereof, an oxide thereof.

[0170] In some embodiments, the negative current collector includes a metal current collector, a carbon-based material current collector, a stainless steel current collector, or a composite current collector.

[0171] In some embodiments, the metal current collector includes at least one of copper, aluminum, an aluminum alloy, iron, an iron alloy, tin, a tin alloy, zinc, a zinc alloy, nickel, a nickel alloy, manganese, a manganese alloy, lead, a lead alloy, antimony, an antimony alloy, cadmium, a cadmium alloy, bismuth, a bismuth alloy.

[0172] In some embodiments, the carbon-based material in the carbon-based material current collector includes a graphite material.

[0173] In some embodiments, the composite current collector includes a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, a copper alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, a silver alloy, etc.) on a polymer material base layer (such as a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0174] [Positive electrode tab]

[0175] In some embodiments, the metal battery includes at least one of a sodium metal battery, a lithium metal battery.

[0176] As used herein, the term "sodium metal battery" refers to a metal battery in which sodium ions serve as charge carriers.

[0177] When used in this document, the term "lithium metal battery" refers to a metal battery that uses lithium ions as charge carriers.

[0178] Sodium metal batteries and lithium metal batteries exhibit good electrical performance. In conventional sodium metal and lithium metal batteries, due to the reactivity of lithium and sodium metals, fluorine-containing groups dissolved in the electrolyte solvent readily react with sodium / lithium metal on the negative electrode, causing sodium / lithium loss and reducing the capacity of the lithium / sodium metal battery. This application effectively reduces the amount of fluorine-containing groups in the electrolyte solvent by controlling the fluorine content on the positive electrode of the lithium / sodium metal battery, thereby reducing the degree of side reactions with the negative electrode metal. The metal batteries of this application, especially sodium metal batteries, exhibit good capacity and initial coulombic efficiency.

[0179] In some implementations, the metal battery includes a sodium metal battery.

[0180] In some embodiments, the positive electrode active material includes at least one of polyanionic compounds, layered oxides, Prussian blue compounds, or modified compounds thereof.

[0181] In some implementations, the positive electrode active material may be used alone or in combination of two or more.

[0182] In some embodiments, the combination can be used to mix two or more positive electrode active materials to form a single positive electrode film, or the two or more positive electrode active materials can be used to form two or more positive electrode film layers respectively.

[0183] In some embodiments, the positive electrode active material includes Na. a1 Ni b1 Fe c1 Mn d1 M1 e1 O f1 Na x1 M2 y1 M3 y2 (X a2 O b2 ) z1 Z w1 Prussian blue, Prussian white, or at least one of their modified compounds, wherein,

[0184] M includes at least one of active and / or inert doped metal elements, 0.85≤a1≤1, 0≤b1≤1, 0≤c1≤1, 0≤d1≤1, 0≤e1≤1, 1.8≤f1≤2, where b1, c1, d1 and e1 are not simultaneously 0;

[0185] M2 includes at least one of Ti, V, Cr, Mn, Fe, Ca, Mg, Al, Nb, Co, Zr, M3 includes Ni, X includes at least one of Si, S, P, As, B, Mo, W, Ge, Z includes at least one of F, O, OH, 1

[0186] In some embodiments, the polyanionic compound includes Na x1 M2 y1 M3 y2 (X a2 O b2 ) z1 Z w1 or a modified compound thereof, wherein M2 includes at least one of Ti, V, Cr, Mn, Fe, Ca, Mg, Al, Nb, Co, Zr, M3 includes Ni, X includes at least one of Si, S, P, As, B, Mo, W, Ge, Z includes at least one of F, O, OH, 1

[0187] In some embodiments, x1 can be 1, 2, 3, 4, 5, 6, 7, or a value in a range between any two of the aforementioned x1.

[0188] In some embodiments, y1 can be 1, 1.5, 2, 2.5, 3, 3.5, 4, or a value in a range between any two of the aforementioned y1.

[0189] In some embodiments, y2 can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, or a value in a range between any two of the aforementioned y2.

[0190] In some embodiments, a2 / b2 can be 0.2, 0.22, 0.24, 0.25, 0.26, 0.28, 0.3, or a value in a range between any two of the aforementioned a2 / b2.

[0191] In some embodiments, z1 can be 1, 1.5, 2, 2.5, 3, 3.5, 4, or a value in a range between any two of the aforementioned z1.

[0192] In some embodiments, w1 can be 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, or a value in a range between any two of the aforementioned w1.

[0193] In some embodiments, the polyanionic compound includes at least one of Na8Fe4(P207)5, NaFeP04, NaMnP04, NaCoP04, Na4Fe3(P04)20?, Na3V2(P04)2F3, Na3V2(P04)3, or modified compounds thereof.

[0194] In some embodiments, the layered oxide includes a layered transition metal oxide. In some embodiments, the layered oxide includes Na a1 Ni b1 Fe c1 Mn d1 M1 e1 O f1 or modified compounds thereof, wherein M includes at least one of an active or / and inactive doping metal element, 0.85

[0195] In some embodiments, the active or / and inactive doping metal element includes at least one of Co, Zn, V, Cr, Al, Sc, Sn, Sb, Zr, Nb, Ti, Mg, Cu, Ru, Ir, or Ca.

[0196] In some embodiments, a1 can be 0.85, 0.87, 0.9, 0.93, 0.96, 0.99, 1, or a value in a range between any two of the foregoing a1 values.

[0197] In some embodiments, b1 can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a value in a range between any two of the foregoing b1 values.

[0198] In some embodiments, c1 can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a value in a range between any two of the foregoing c1 values.

[0199] In some embodiments, d1 can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a value in a range between any two of the foregoing d1 values.

[0200] In some embodiments, e1 can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a value in a range between any two of the foregoing e1 values.

[0201] In some embodiments, f1 can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a value in a range between any two of the foregoing f1.

[0202] In some embodiments, the positive active material comprises Na a1 Ni b1 Fe c1 Mn d1 M1 e1 O f1 , or a modified compound thereof, wherein M comprises at least one of an active or / and inert doped metal element, 0.85≤a1≤1, 0≤b1≤0.3, 0≤c1≤0.4, 0≤d1≤0.4, 0≤e1≤0.1, 1.8≤f1≤2, b1, c1, d1 and e1 are not zero at the same time.

[0203] In some embodiments, the layered oxide comprises at least one of NaFeO2, NaCoO2, NaCrO2, NaMnO2, or NaNiO2.

[0204] Since the chemical properties of sodium are more active, when the metal battery of the present application is a sodium metal battery, the design of the fluorine content of the positive electrode plate of the present application is more obvious for the improvement of the consumption of the negative sodium metal. Compared with the traditional sodium metal battery, the sodium metal battery of the present application has better capacity and first coulomb efficiency.

[0205] In some embodiments, the metal battery comprises a lithium metal battery.

[0206] In some embodiments, the positive active material comprises at least one of an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and a modified compound thereof.

[0207] In some embodiments, the lithium transition metal oxide comprises a lithium cobalt oxide (such as LiCoO2), a lithium nickel oxide (such as LiNiO2), a lithium manganese oxide (such as LiMnO2, LiMn2O4), a lithium nickel cobalt oxide, a lithium manganese cobalt oxide, a lithium nickel manganese oxide, a lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(also can be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also can be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also can be referred to as NCM 211 ), LiNi0.6 Co 0.2 Mn 0.2 O2(also can be referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to as NCM 811 ), or lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2).

[0208] In some embodiments, the lithium-containing phosphate of olivine structure includes at least one of lithium iron phosphate (such as LiFePO4(also can be referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, or a composite of lithium manganese iron phosphate and carbon.

[0209] In some embodiments, the positive electrode tab includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and the positive electrode film layer further includes a conductive agent.

[0210] By way of example, the positive electrode current collector has two opposite surfaces in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0211] In some embodiments, the positive electrode current collector can be a conductive carbon sheet, a metal foil, a carbon-coated metal foil, a porous metal plate, or a composite current collector. The conductive carbon material of the conductive carbon sheet can be selected from one or more of Super P, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers. The metal material of the metal foil, the carbon-coated metal foil, and the porous metal plate is independently selected from at least one of copper, aluminum, nickel, and stainless steel. The composite current collector can be a composite current collector formed by combining a metal foil and a polymer-based film.

[0212] In some embodiments, the conductive agent can include at least one of super conductive carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0213] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the additive, the conductive agent, the binder, and any other components, in a solvent (such as N-methyl pyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and then drying, cold pressing, and the like to obtain the positive electrode tab.

[0214] In some embodiments, the metal battery has a first coulombic efficiency of greater than or equal to 90%.

[0215] The first coulombic efficiency of the metal battery can be measured by methods and instruments known in the art. The specific operation can refer to the first charge-discharge test at a certain temperature (for example, 25°C), after the battery is assembled and rested for a certain time (for example, 10 hours). First, charge the secondary battery to a certain voltage (for example, 3.65V) at a certain constant current (for example, 0.33C), and then further charge at a constant voltage (for example, 3.65V) to a certain current (for example, 0.05C), and record the charge capacity value as C1; then discharge at a constant current (for example, 0.33C) to the lower limit cutoff voltage (for example, 1.5V), and record the discharge capacity value as C2, the first coulombic efficiency FCE = C2 / C1.

[0216] The metal battery of the present application has a good first coulombic efficiency, which is better than that of conventional metal batteries on the market.

[0217] The present application also provides a method for preparing the metal battery of the present application.

[0218] In some embodiments, the method comprises the steps of providing a positive electrode sheet, a negative electrode sheet and a separator film, and preparing a metal battery by a winding process or a stacking process using the positive electrode sheet, the negative electrode sheet and the separator film.

[0219] The shape of the metal battery of the present application is not particularly limited, which can be cylindrical, square or any other shape. For example, FIG. 1 is a metal battery 5 of square structure as an example.

[0220] In some embodiments, referring to FIG. 2, the outer package can include a shell 51 and a cover plate 53. The shell 51 can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate form an accommodation cavity. The shell 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can be arranged on the opening to close the accommodation cavity. The positive electrode sheet, the negative electrode sheet and the separator film can form an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the accommodation cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the metal battery 5 can be one or more, which can be selected by those skilled in the art according to the specific actual needs.

[0221] In some embodiments, the metal battery can be assembled into a battery module, and the number of metal batteries 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.

[0222] FIG. 3 is a battery module 4 as an example. Referring to FIG. 3, in the battery module 4, a plurality of metal batteries 5 can be arranged in series along the length direction of the battery module 4. Of course, the arrangement can be made in any other manner. The plurality of metal batteries 5 can be further fixed by fasteners.

[0223] Optionally, the battery module 4 can further include a housing having an accommodation space, and the plurality of metal batteries 5 can be accommodated in the accommodation space.

[0224] In some embodiments, the above-described battery module can be assembled into a battery pack, and the number of battery modules contained in the battery pack 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 pack.

[0225] FIGS. 4 and 5 are a battery pack 1 as an example. Referring to FIGS. 4 and 5, the battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be arranged on the lower box body 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0226] [Separator]

[0227] In some embodiments, the metal battery further includes a separator. The type of the separator is not particularly limited in the present application, and any known porous structure separator having good chemical stability and mechanical stability can be selected.

[0228] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0229] In some embodiments, the positive electrode tab, the negative electrode tab, and the separator can be made into an electrode assembly by a winding process or a stacking process.

[0230] In some embodiments, the metal battery can include an outer package. The outer package can be used to package the above-mentioned electrode assembly and electrolyte.

[0231] In some embodiments, the outer package of the metal battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the metal battery can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate, etc. can be listed.

[0232] [Electric device]

[0233] The application also provides a power-using device comprising the metal battery of the application or the metal battery prepared according to the method of the application.

[0234] In some embodiments, the power-using device of the embodiments of the application can further comprise at least one of a secondary battery, a battery module or a battery pack. The secondary battery, the battery module or the battery pack can be used as a power source of the power-using device or as an energy storage unit of the power-using device. The power-using device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0235] As the power-using device, the secondary battery, the battery module or the battery pack can be selected according to the use requirement thereof.

[0236] FIG. 6 is a power-using device as an example. The power-using device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirement of high power and high energy density of the secondary battery for the power-using device, a battery pack or a battery module can be used.

[0237] As another example of the device, it can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and a secondary battery can be used as a power source.

[0238] Embodiments

[0239] Hereinafter, the embodiments of the application are described. The embodiments described below are exemplary and are only used to explain the application and cannot be understood as a limitation of the application. If the specific technology or condition is not specified in the embodiments, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0240] I. Preparation method

[0241] Embodiment 1

[0242] 1) Preparation of the positive electrode tab

[0243] The positive electrode active material sodium iron pyrophosphate, the conductive agent carbon black (Super P) and the binder polyacrylic acid (PAA) were mixed in N-methylpyrrolidone at a mass percentage of 96:3:3 by fully stirring to form a uniform positive electrode slurry; the positive electrode slurry was coated on the surface of the positive electrode current collector aluminum foil, and the coating weight was 20 mg / cm 2 , single-sided coating, and after drying, cold pressing and slitting, the positive electrode tab was obtained.

[0244] 2) Preparation of the negative electrode sheet

[0245] Carbon nanotubes (CNT) and sodium carboxymethyl cellulose were mixed in deionized water at a weight ratio of 50:50 and stirred thoroughly to form a porous layer slurry. The porous layer slurry was coated on the surface of the negative current collector copper foil, and the coating thickness of the porous layer was 5 μm. After coating, drying, cold pressing, and slitting, the negative electrode sheet was obtained.

[0246] 3) Preparation of the electrolyte

[0247] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), sodium salt sodium hexafluorophosphate NaPF6 was dissolved in ethylene glycol dimethyl ether (DME) and stirred uniformly to obtain an electrolyte with a sodium salt concentration of 1 mol / L.

[0248] 4) Preparation of the separator

[0249] A porous polyethylene film was used as the separator.

[0250] 5) Preparation of the battery

[0251] The above positive electrode sheet, separator, and negative electrode sheet were stacked in order to form a button cell, thereby obtaining the sodium metal battery without a negative electrode of Example 1.

[0252] The metal batteries of Examples 2 to 4 were prepared in a similar manner to that of Example 1, but the type of binder was adjusted, as shown in Table 1.

[0253] The metal batteries of Examples 5 to 6 were prepared in a similar manner to that of Example 1, but the amount of binder added and / or the type of binder was adjusted, as shown in Table 1.

[0254] The metal battery of Example 7 was prepared in a similar manner to that of Example 1, but the type of solvent in the electrolyte was adjusted to diethylene glycol dimethyl ether (DEGDME), as shown in Table 1.

[0255] The metal battery of Example 8 was prepared in a similar manner to that of Example 1, but the porous layer material of the negative electrode sheet was adjusted to conductive carbon black (SP), as shown in Table 1.

[0256] The metal battery of Example 9 was prepared in a similar manner to that of Example 1, but the negative electrode sheet was replaced with a sodium metal sheet, which was placed as the negative electrode on a stainless steel gasket during battery assembly, and the other parameters were the same as those of the metal battery without a negative electrode.

[0257] The metal battery of Comparative Example 1 was prepared in a similar manner to that of Example 1, but the type of binder was adjusted, and the binder of Comparative Example 1 was PVDF, as shown in Table 1.

[0258] The metal battery of Comparative Example 2 was prepared in a similar manner to that of Example 1, but the type of binder was adjusted. The binder of Comparative Example 2 was a mixture of polyimide and polyvinylidene fluoride at a mass ratio of 0.6:0.4, as shown in Table 1.

[0259] The metal battery of Comparative Example 3 was prepared in a similar manner to that of Example 1, but the types of binder and electrolyte were adjusted. The binder of Comparative Example 3 was a mixture of polyimide and polyvinylidene fluoride at a mass ratio of 0.6:0.4, and the electrolyte was propylene carbonate (PC), as shown in Table 1.

[0260] The metal battery of Comparative Example 4 was prepared in a similar manner to that of Example 1, but the type of electrolyte was adjusted. The electrolyte of Comparative Example 4 was propylene carbonate (PC), as shown in Table 1.

[0261] II. Battery performance test

[0262] 1. Fluorine content test of positive electrode sheet

[0263] Whether the positive electrode sheet contains fluorine can be detected by a Fourier transform infrared spectrometer (IS10). The specific operation is as follows: an infrared beam penetrates the surface of the positive electrode sheet to a depth of 700 nm (ATR is Ge crystal), and the percentage transmittance of infrared light versus wave number is recorded to obtain an infrared spectrum. Functional group analysis is performed on the infrared spectrum according to the national standard GB / T6040-2002 General infrared spectroscopy analysis method to obtain a conclusion on whether the positive electrode sheet contains fluorine.

[0264] The fluorine content of the positive electrode sheet can be detected by inductively coupled plasma (ICP) test. The test can be performed in accordance with YS / T1006.2-2014, GB / T23367.2-2009, or YS / T1028.5-2015, using an inductively coupled plasma emission spectrometer (iCAP 740) in accordance with the instrument instructions to obtain the fluorine content of the positive electrode sheet.

[0265] 2. LUMO energy level calculation

[0266] The LUMO energy level of each substance can be obtained according to first-principle theoretical calculation, specifically, the energy level density functional theory (DFT) calculation. The theoretical calculation is based on Gaussian 09 software, and the Becke three-parameter-Lee-Yang-Parr (B3LYP) hybrid functional is used. In order to obtain accurate geometric structure, no symmetry constraint is applied during the structure optimization process. The energy and force convergence thresholds are 1.0E-06 and 1.0E-03 respectively for each atom and In addition, the atomic properties are represented by 6-311+G(d) basis sets. The dispersion-corrected density functional theory (DFT-D2) calculation is performed using the Vienna ab initio simulation package (VASP), using the generalized gradient approximation (GGA) and Perdew-Burke-Eznerhof (PBE) functional (GGA-PBE) to describe the exchange-correlation energy of electrons. The projected augmented wave method (PAW) is used to handle the interaction between atomic nuclei and electrons. The k points on the Brillouin zone are 5x5x1, and the energy cutoff is 400 eV. The atomic positions and unit cell vectors are fully optimized until all force components are less than 0.01 eV / Å. According to the above simulation calculation method, the LUMO energy level of the substance can be obtained.

[0267] The LUMO energy level of the metal state corresponding to the metal element and / or the solvent of the electrolyte in the present application can also be obtained from the books and documents disclosed in the prior art.

[0268] Through calculation, the LUMO1 energy level of Example 1-Example 9, Comparative Example 1-4 is -0.57.

[0269] y = LUMO2 energy level - LUMO1 energy level.

[0270] 3. Performance test of the battery

[0271] (1) Charge gram capacity, discharge gram capacity and first coulombic efficiency test

[0272] After the battery is assembled and placed for 10 hours at 25°C, the first charge and discharge test is performed. First, charge the secondary battery to 3.65V at a constant current of 0.33C, and then further charge to a current of 0.05C at a constant voltage of 3.65V, and record the charge capacity value as C1; then discharge to the lower limit cutoff voltage of 1.5V at a constant current of 0.33C, and record the discharge capacity value C2, the first coulombic efficiency FCE = C2 / C1.

[0273] The step of reading the charge and discharge corresponds to the gram capacity data, i.e., the charge gram capacity and the discharge gram capacity (if only the capacity value can be read, the capacity needs to be divided by the mass of the positive electrode material providing all activities).

[0274] III. Analysis of test results of each embodiment and comparative example

[0275] The batteries of each embodiment and comparative example were prepared according to the above method, and each performance parameter was measured. The metal battery related parameters are shown in Table 1, and the battery performance test results are shown in Table 2.

[0276] Table 1 Metal battery parameter table

[0277] Table 2 Metal battery performance test table

[0278] According to the above table results, it can be known from Examples 1-9 and Comparative Example 3 that, taking the total mass of the positive electrode film layer as the calculation basis, controlling the fluorine content of the positive electrode sheet to be less than or equal to 385 ppm, and controlling the difference between the lowest unoccupied molecular orbital energy level LUMO2 of the solvent of the electrolyte and the lowest unoccupied molecular orbital energy level LUMO1 of the metal state corresponding to the metal element in the positive electrode active material to be greater than or equal to 0, helps to improve the adaptability of the electrolyte and the negative electrode, reduce the concentration of the fluorine-containing group dissolved in the solvent of the electrolyte, reduce the degree of side reaction of the negative electrode metal, reduce the consumption of the negative electrode metal, improve the discharge gram capacity and the first coulomb efficiency of the metal battery.

[0279] It can be known from Examples 1-9 and Comparative Examples 1-2 that, taking the total mass of the positive electrode film layer as the calculation basis, controlling the fluorine content of the positive electrode sheet to be less than or equal to 385 ppm, helps to improve the discharge gram capacity and the first coulomb efficiency of the metal battery.

[0280] It can be known from Examples 1-9 and Comparative Example 4 that, controlling the difference between the lowest unoccupied molecular orbital energy level LUMO2 of the solvent of the electrolyte and the lowest unoccupied molecular orbital energy level LUMO1 of the metal state corresponding to the metal element in the positive electrode active material to be greater than or equal to 0, helps to improve the adaptability of the electrolyte and the negative electrode, improve the discharge gram capacity and the first coulomb efficiency of the metal battery.

[0281] As can be seen from Examples 1-6, when the fluorine content of the positive electrode sheet is less than or equal to 120 ppm, it is helpful to further improve the discharge gram capacity and the first coulombic efficiency of the metal battery. Among them, the metal battery of the application can be applied to various binders described in the application, for example, a binder including only the first binder PAA, SBS, CMC or a binder including a combination of the first binder and the second binder. As can be seen from Examples 5 and 6, when the mass percentage of the binder is less than or equal to 3% and greater than or equal to 0%, the metal battery of the application has good discharge gram capacity and first coulombic efficiency.

[0282] As can be seen from Examples 1 and 7, the metal battery of the application can be applied to various electrolyte solvents described in the application.

[0283] As can be seen from Examples 1 and 8, the porous layer in the negative electrode sheet of the application is suitable for various porous layer materials described in the application, such as carbon nanotubes or carbon black.

[0284] As can be seen from Examples 1 and 9, the metal battery of the application is suitable for negative electrode-free and metal negative electrode. When the negative electrode is a metal negative electrode, the metal battery of the application has higher discharge gram capacity and first coulombic efficiency.

[0285] It should be noted that the application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having the same technical idea and playing the same role and effect within the scope of the technical solution of the application are all included in the technical scope of the application. In addition, within the scope of the main idea of the application, various modifications of the embodiments that can be thought of by those skilled in the art, and other ways constructed by combining part of the constituent elements in the embodiments are also included in the scope of the application.

Claims

1. A metal battery, characterized by, The metal battery comprises a positive electrode sheet, a negative electrode sheet, and an electrolyte, the positive electrode sheet comprises a positive electrode film layer, the positive electrode film layer comprises a binder and a positive electrode active material, the positive electrode active material comprises a metal element, and the fluorine content of the positive electrode sheet is less than or equal to 385 ppm based on the total mass of the positive electrode film layer; During the charging process, the positive electrode active material releases metal ions, the metal ions are reduced and deposited as metal on the negative electrode sheet, and during the discharging process, the metal is oxidized and dissolved into the metal ions; The difference between the lowest unoccupied molecular orbital energy level LUMO2 of the solvent of the electrolyte and the lowest unoccupied molecular orbital energy level LUMO1 of the metal state corresponding to the metal element in the positive electrode active material is y = LUMO2 - LUMO1, and 0 ≤ y.

2. The metal battery of claim 1, wherein, The fluorine content of the positive electrode sheet is less than or equal to 120 ppm based on the total mass of the positive electrode film layer.

3. The metal battery of claim 1 or 2, wherein, 0.7≤y。 4. The metal battery of any one of claims 1-3, wherein, The binder comprises a first binder, the first binder is a copolymer and / or a homopolymer, and in the monomers of the copolymer and the homopolymer, the substitution group of the fluorine element is less than or equal to 2.

5. The metal battery of any one of claims 1-4, wherein, The first binder comprises at least one of a methyl methacrylate monomer copolymer and / or a homopolymer, a sugar monomer copolymer and / or a homopolymer, an acrylic acid monomer copolymer and / or a homopolymer, a styrene monomer copolymer and / or a homopolymer, a butadiene monomer copolymer and / or a homopolymer, a phenol monomer copolymer and / or a homopolymer, an aldehyde monomer copolymer and / or a homopolymer, a diatomic amine monomer copolymer and / or a homopolymer, a diatomic anhydride monomer copolymer and / or a homopolymer, a benzene ring monomer copolymer and / or a homopolymer, or derivatives thereof, modified products thereof.

6. The metal battery of any one of claims 1-5, wherein, The first binder comprises at least one of polymethyl methacrylate, carboxymethyl cellulose, polyacrylic acid, sodium alginate, butadiene rubber, polyvinyl alcohol, phenolic resin, polyimide, styrene monomer-butadiene monomer-styrene monomer block copolymer, or derivatives thereof, modified products thereof.

7. The metal battery of any one of claims 1-6, wherein, The first binder comprises at least one of carboxymethyl cellulose, polyacrylic acid, polyimide, styrene monomer-butadiene monomer-styrene monomer block copolymer, or derivatives thereof, modified products thereof.

8. The metal battery of any one of claims 1-7, wherein, The binder comprises a second binder, and the second binder comprises a fluorine-containing monomer copolymer and / or a homopolymer.

9. The metal battery of any one of claims 1-8, the mass ratio of the first binder to the second binder is (1-0.5):(0-0.5).

10. The metal battery of any one of claims 1-9, wherein, The mass percentage of the binder is less than or equal to 3% and greater than or equal to 0.5% based on the total mass of the positive electrode film layer.

11. The metal battery of any one of claims 1-10, wherein, When the mass ratio of the first binder to the second binder is greater than or equal to 0.5:0.5 and less than 0.6:0.4, the mass percentage of the binder is less than or equal to 2% and greater than or equal to 0.5% based on the total mass of the positive electrode film layer; and / or when the mass ratio of the first binder and the second binder is greater than or equal to 0.6:0.4, less than 0.7:0.3, the mass percentage of the binder is less than or equal to 2.5%, greater than or equal to 0.5% based on the total mass of the positive electrode film layer; and / or when the mass ratio of the first binder and the second binder is (1-0.7):(0-0.3), the mass percentage of the binder is less than or equal to 3%, greater than or equal to 0.5% based on the total mass of the positive electrode film layer.

12. The metal battery of any one of claims 1-11, wherein, The electrolyte comprises a solvent and a sodium salt dissolved in the solvent, the solvent comprising at least one ether compound of formula I, R1-(O-R3) n -O-R2 (I) wherein R1 and R2 are each independently selected from C1-C6 alkyl, R3 is selected from C1-C6 alkylene, and n is selected from an integer from 1 to 5.

13. The metal battery of claim 12, wherein, R1 and R2 are each independently selected from methyl or ethyl, and R3 is selected from a linear C1-C5 alkylene.

14. The metal battery of claim 12 or 13, wherein, R3 is selected from -CH2CH2-.

15. The metal battery of any one of claims 12-14, wherein, The solvent includes at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, pentaethylene glycol diethyl ether, or ethylene glycol dibutyl ether.

16. The metal battery of any one of claims 12-15, wherein, The sodium salt includes at least one of NaPF6, NaFSI, NaTFSI, NaBF4, NaClO4, or NaOTf.

17. The metal battery of any one of claims 1-16, wherein, The negative electrode tab is an inert material that does not participate in an electrochemical reaction, and the negative electrode tab includes a negative electrode current collector.

18. The metal battery of claim 17, wherein, The negative electrode tab includes a porous layer formed on the surface of the negative electrode tab, and the porous layer has micrometer, submicrometer, or nanometer level pores.

19. The metal battery of claim 17 or 18, wherein, The porous layer includes a carbon-based material.

20. The metal battery of claim 19, wherein, The carbon-based material includes at least one of carbon black, activated carbon, carbon nanotubes, carbon fibers, or graphite.

21. The metal battery of any one of claims 1-16, wherein, The negative electrode tab includes a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector, and the negative electrode active material includes at least one of lithium, sodium, zinc, iron, chromium, manganese, tin, aluminum, copper, nickel, or an alloy thereof, or an oxide thereof.

22. The metal battery of any one of claims 17-21, wherein, The negative electrode current collector includes a metal current collector, a carbon-based material current collector, or a stainless steel current collector.

23. The metal battery of any one of claims 1-22, wherein, The metal battery includes at least one of a sodium metal battery or a lithium metal battery.

24. The metal battery of any one of claims 1-23, wherein, The positive electrode active material includes at least one of a polyanion compound, a layered oxide, a Prussian blue compound, or a modified compound thereof.

25. The metal battery of claim 24, wherein, The positive active material includes Na a1 Ni b1 Fe c1 Mn d1 M1 e1 O f1 , Na x1 M2 y1 M3 y2 (X a2 O b2 ) z1 Z w1 , Prussian blue, Prussian white, or at least one of modified compounds thereof, wherein, M includes at least one of an active or / and inert doped metal element, 0.85≤a1≤1, 0≤b1≤1, 0≤c1≤1, 0≤d1≤1, 0≤e1≤1, 1.8≤f1≤2, b1, c1, d1, and e1 are not zero at the same time; M2 includes at least one of Ti, V, Cr, Mn, Fe, Ca, Mg, Al, Nb, Co, Zr, M3 includes Ni, X includes at least one of Si, S, P, As, B, Mo, W, Ge, Z includes at least one of F, O, OH, 1≤x1≤7, 1≤y1≤4, 0≤y2≤0.05, 0.2≤a2 / b2≤0.3, 1≤z1≤4, 0≤w1≤7.

26. The metal battery of any one of claims 1-25, wherein, The metal battery has a first coulombic efficiency greater than or equal to 90%.

27. A method of making a metal battery as in any of claims 1-26.

28. An electrical device, comprising: The electrical device comprises a metal battery as in any of claims 1-26 or made according to the method of claim 27.

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