Secondary batteries, battery modules, battery packs, and power consumption devices

Abstract

This application provides a secondary battery, a battery module, a battery pack, and a power consumption device. The secondary battery comprises a positive electrode sheet and an electrolyte, the electrolyte comprising a film-forming additive, where the film resistance xΩ of the positive electrode sheet and the mass content y% of the film-forming additive based on the total mass of the electrolyte satisfy the relationship x*y≦25. The film resistance and film-forming additive of the secondary battery provided in this application satisfy the above relationship, and by adjusting the film resistance and film-forming additive of the secondary battery, the Coulomb efficiency, high-temperature cycle performance, and high-temperature storage performance of the battery can be improved.

Description

[Technical Field]

[0001] This application relates to the technical field of secondary batteries, and more particularly to secondary batteries, battery modules, battery packs, and power consumption devices. [Background technology]

[0002] In recent years, rechargeable batteries have been widely used in many fields, including energy storage and power generation systems such as hydroelectric power plants, thermal power plants, wind power plants, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. With the increasing use of rechargeable batteries, higher demands are being placed on energy density, cycle performance, and other aspects.

[0003] Rechargeable batteries typically consist of a positive electrode, a negative electrode, and an electrolyte. Metal ions move back and forth between the positive and negative electrodes to achieve charging and discharging. Therefore, the performance of a rechargeable battery is not determined by a single factor, but rather by the composition of the battery components and whether the parameters work together effectively. [Overview of the project]

[0004] This application has been made in view of the above-mentioned problems, and its purpose is to provide a secondary battery that improves the electrochemical performance of the secondary battery, particularly at high temperatures, by adjusting the parameters of different components of the secondary battery.

[0005] A first aspect of this application provides a secondary battery comprising a positive electrode sheet and an electrolyte, wherein the electrolyte comprises a film-forming additive, and the film resistance xΩ of the positive electrode sheet and the mass content y% of the film-forming additive based on the total mass of the electrolyte satisfy the relationship x*y≦25.

[0006] The applicant unexpectedly discovered a synergistic effect between the film resistance of the battery's positive electrode sheet and the content of the film-forming additive. By adjusting the amount of the film-forming additive according to the magnitude of the film resistance of the positive electrode sheet of a secondary battery, the overall performance of the battery, including Coulomb efficiency, cycle performance, and safety performance, can be reliably improved. By controlling the film resistance xΩ of the battery's positive electrode sheet and the mass content y% of the film-forming additive based on the total mass of the electrolyte to within the range of x*y≦25, capacity loss during the initial charge and discharge of the battery can be reduced, effectively improving the battery's Coulomb efficiency, high-temperature cycle performance, and high-temperature storage performance, while also suppressing dendrite formation in the battery and comprehensively improving the battery's safety performance and electrochemical performance.

[0007] In any embodiment, the mass content of the film-forming additive in the electrolyte is 0.2% to 5%, and optionally 0.5% to 2%, of the total mass of the electrolyte.

[0008] Batteries within the above mass content range exhibit excellent Coulomb efficiency, high-temperature performance, and the ability to suppress sodium dendrite formation.

[0009] In any embodiment, the film resistance of the positive electrode sheet is 50Ω or less, and optionally 10Ω or less.

[0010] Batteries with a positive electrode sheet film resistance of 50Ω or less exhibit excellent Coulomb efficiency, high-temperature performance, and ability to suppress sodium dendrite formation.

[0011] In any embodiment, the film-forming additive comprises one or more selected from sulfuric acid ester compounds, sulfonic acid ester compounds, and sulfite ester compounds.

[0012] Sulfuric acid ester compounds, sulfite ester compounds, and sulfonic acid ester compounds are preferentially reduced over electrolyte salts and solvents, forming a thin, uniform, and dense solid electrolyte interface (SEI) film on the negative electrode surface, thereby reducing direct contact between the negative electrode and the electrolyte. Furthermore, the salts formed in the SEI film from sulfuric acid ester compounds, sulfite ester compounds, and sulfonic acid ester compounds have high-temperature resistance and can effectively improve the electrochemical performance of the battery at high temperatures. By adding sulfuric acid ester compounds, sulfite ester compounds, and sulfonic acid ester compounds as additives, the Coulomb efficiency, high-temperature cycle performance, and high-temperature storage performance of the battery can be improved, and dendrite formation can be suppressed.

[0013] In any embodiment, the sulfate ester compound comprises one or more compounds selected from those represented by formula I. [ka] Here, n is any integer from 0 to 3, and R1 and R2 are independently hydrogen, fluorine, cyano group, olefin group, substituted or unsubstituted C, respectively. 1-6 alkyl group, [ka] Selected from.

[0014] In any embodiment, the sulfuric acid ester compound contains one or more selected from 1,3,2-dioxathiolane 2,2-dioxide, 4-methyl-1,3,2-dioxathiolane-2,2-dioxide, 4-fluoro-1,3,2-dioxathiolane-2,2-dioxide, 4-propyl-1,3,2-dioxathiolane-2,2-dioxide, 4,4'-bi-1,3,2-dioxathiolane 2,2,2'-2'-tetraoxide, 4-vinyl-1,3,2-dioxathiolane-2,2-dioxide, 4-ethyl-1,3,2-dioxathiolane 2,2-dioxide, 4,5-difluoro-1,3,2-dioxathiolane-2,2-dioxide, and 4-cyano-1,3,2-dioxathiolane-2,2-dioxide.

[0015] In any embodiment, the sulfonic acid ester compound contains one or more selected from salts having a sulfonic acid anion or compounds represented by Formula II and Formula III,

Chemical formula

Chemical formula

[0016] In any embodiment, the sulfonic acid ester compound includes one or more selected from 1,3-propanesultone, 3-fluoro-1,3-propanesultone, 1-methyl-1,3-propanesultone, 1,4-butanesultone, 1,4-butensulfonic acid sultone, 1-propene-1,3-sultone, methylenemethanedisulfonate, 3-(1-pyridinio)-1-propanesulfonate, and 1,4-butanediol dimethanesulfonate.

[0017] In any embodiment, the sulfite ester additive comprises one or more compounds selected from those represented by formula IV. [ka] Here, R7 and R8 are independently either substituted or non-substituted C. 1-6 Selected from alkyl groups, or R7 and R8, together with the oxygen to which they are bonded and the sulfur to which the oxygen is co-bonded, form a five-membered or six-membered ring, the ring optionally having a double bond, and the hydrogen on the ring optionally being a halogen, C 1-3 It is substituted with an alkyl group.

[0018] In any embodiment, the sulfite ester includes one or more selected from 1,3,2-dioxatian 2-oxide, 1,3,2-dioxathiolane 2-oxide, 4-methyl-1,3-dioxa-2-thia(IV)cyclohexane-2-one, dimethyl sulfite, and diethyl sulfite.

[0019] In any embodiment, the electrolyte further comprises a sodium salt and an ether-based solvent, wherein the molar concentration of the sodium salt is 0.5 mol / L to 4 mol / L, optionally 0.8 mol / L to 2 mol / L.

[0020] By controlling the molar concentration of sodium salt within an appropriate range, the Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance of the battery can be improved.

[0021] Molecules of ether-based solvents can establish a stable electrode / electrolyte interface on the negative electrode surface and form a stable SEI film, thereby reducing electrochemical polarization and improving the Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance of the battery.

[0022] In any embodiment, the sodium salt includes one or more selected from sodium hexafluorophosphate, sodium difluoro(oxalato)borate, sodium tetrafluoroborate, sodium bis(oxalato)borate, sodium perchlorate, sodium hexafluoroarsenate (V), sodium bis(fluorosulfonyl)imide, sodium trifluoromethanesulfonate, and sodium bis(trifluoromethanesulfonyl)imide.

[0023] In any embodiment, the ether solvent includes one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, crown ether, and fluorinated ether.

[0024] The molecules of the ether-based solvent contained in ether-based electrolytes can construct a stable electrode / electrolyte interface on the surface of sodium metal anodes (including non-anodes), carbon material anodes, and other non-carbon material anodes, forming a stable solid electrolyte interface (SEI). This reduces electrochemical polarization and improves the Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance of the battery.

[0025] In any embodiment, the positive electrode sheet comprises a positive electrode active material, the positive electrode active material comprising one or more selected from layered transition metal oxides, polyanionic compounds, or Prussian blue analogs.

[0026] In any embodiment, the secondary battery is either a lithium-ion battery or a sodium-ion battery.

[0027] In any embodiment, the secondary battery is a sodium metal battery without a negative electrode.

[0028] A second aspect of this application provides a battery module including the secondary battery of the first aspect.

[0029] A third aspect of this application provides a battery pack including a secondary battery of the first aspect or a battery module of the second aspect.

[0030] A fourth aspect of this application provides a power consumption device comprising at least one of a secondary battery according to the first aspect, a battery module according to the second aspect, or a battery pack according to the third aspect. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic diagram of a secondary battery according to one embodiment of the present application. [Figure 2] Figure 1 is an exploded view of a secondary battery according to one embodiment of this application. [Figure 3] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 4] This is a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 5] Figure 4 is an exploded view of a battery pack according to one embodiment of this application. [Figure 6] This is a schematic diagram of a power-consuming device in which a secondary battery, according to one embodiment of this application, is used as a power source. [Modes for carrying out the invention]

[0032] Embodiments of the secondary battery, battery module, battery pack, and power consumption device of this application will be described in detail below with reference to the drawings. Details that are not necessary may be omitted. For example, detailed descriptions of already well-known matters or repeated descriptions of substantially the same structure may be omitted. This is to avoid unnecessarily redundancy in the following description and to facilitate understanding for those skilled in the art. Furthermore, the drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter described in the claims.

[0033] The “range” disclosed herein is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit that define the boundary of a particular range. The range thus limited may or may not include an end value and can be any combination; that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are described for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also expected. Also, if the minimum range values ​​1 and 2 and the maximum range values ​​3, 4 and 5 are described, the following ranges, 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5, can all be expected. In this application, unless otherwise specified, the numerical range “a-b” means an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are listed in this specification, and "0 to 5" is merely an abbreviated representation of combinations of these numbers. Furthermore, when expressing that a parameter is 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.

[0034] All embodiments and any embodiments of this application can be combined to form new technical solutions unless otherwise specified.

[0035] All technical features and any technical features of this application can be combined with each other to form new technical solutions, unless otherwise specified.

[0036] The terms “includes” and “contains” as used in this application may be open-ended or closed-ended unless otherwise specified. For example, the terms “includes” and “contains” may indicate that other components not listed are included or that only the listed components are included or contain.

[0037] In this application, the term "or" is inclusive unless otherwise specified. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied by either A being true (or existing) and B being false (or not existing), A being false (or not existing) and B being true (or existing), or both A and B being true (or existing).

[0038] [Secondary battery] This application provides a secondary battery comprising a positive electrode sheet and an electrolyte, wherein the electrolyte contains a film-forming additive, and the film resistance xΩ of the positive electrode sheet and the mass content y% of the film-forming additive based on the total mass of the electrolyte satisfy the relationship x*y≦25.

[0039] In this specification, the term "film resistance" refers to the resistance of the positive electrode sheet. Film resistance can be measured by any known method, including but not limited to the single-probe method, the four-probe method, and the DC two-probe method, with a contact area of ​​49π mm² between the probe and the positive electrode sheet. 2 It is set to this. As an example, using the HIOKI BT23562 internal resistance tester, the film resistance R of the positive electrode sheet is measured. The upper and lower sides of the positive electrode sheet are sandwiched between the two conductive terminals of the tester, and pressure is applied to fix it in place. The diameter of the conductive terminals is set to 14 mm, and a pressure of 15 MPa to 27 MPa is applied to obtain the film resistance of the positive electrode sheet.

[0040] In this specification, the term "film-forming additive" refers to an additive that forms and improves an SEI film or CEI film on the negative electrode (or positive electrode). In an electrodeless sodium metal battery, the negative electrode active material is formed in situ by the initial desodium deposition of the positive electrode, and there is no active material to supply to the negative electrode. Therefore, the addition of a film-forming additive can significantly improve the Coulomb efficiency of an electrodeless sodium metal battery.

[0041] In this specification, the term "additive" refers to a component present in small amounts in the electrolyte, which may be a gas, liquid, or solid. Conceptually, the only difference between an additive, main solvent, and electrolyte salt is their content in the electrolyte; solvents or salts present in small amounts can be collectively referred to as additives.

[0042] The applicant unexpectedly discovered a synergistic effect between the film resistance of the battery's positive electrode sheet and the content of the film-forming additive. By adjusting the amount of the film-forming additive according to the magnitude of the film resistance of the positive electrode sheet of the secondary battery, the overall performance of the battery, including Coulomb efficiency and cycle performance, can be reliably improved. By controlling the film resistance xΩ of the battery's positive electrode sheet and the mass content y% of the film-forming additive based on the total mass of the electrolyte to within the range of x*y≦25, capacity loss during the initial charge and discharge of the battery can be reduced, effectively improving the battery's Coulomb efficiency, high-temperature cycle performance, and high-temperature storage performance, while also suppressing the formation of dendrites in the battery and comprehensively improving the battery's safety performance and electrochemical performance.

[0043] In some embodiments, the mass content of the film-forming additive in the electrolyte is 0.2% to 5% of the total mass of the electrolyte. In some embodiments, the mass content of the film-forming additive in the electrolyte may be any of 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5% of the total mass of the electrolyte. The upper and lower limits of the range of mass content of the film-forming additive in the electrolyte can be arbitrarily selected from the above values.

[0044] By controlling the mass content of the film-forming additive in the electrolyte to an appropriate range, it is possible to avoid the decrease in SEI film stability caused by a low mass content of the film-forming additive, as well as the increase in electrolyte viscosity, decrease in ionic conductivity, decrease in kinetic performance, excessive thickness of the SEI film, and increase in internal battery resistance caused by a high mass content of the film-forming additive. Batteries within the above mass content range exhibit excellent Coulomb efficiency, high-temperature performance, and sodium dendrite formation suppression ability.

[0045] In some embodiments, the mass content of the film-forming additive in the electrolyte is 0.5% to 2% of the total mass of the electrolyte. When the mass content of the film-forming additive in the electrolyte is within this range, the Coulomb efficiency of the battery is further improved, the high-temperature cycle capacity retention rate and high-temperature storage capacity retention rate are further improved, and the high-temperature cycle resistance is further reduced.

[0046] In some embodiments, the film resistance of the positive electrode sheet is 50Ω or less. In some embodiments, the film resistance of the positive electrode sheet can be arbitrarily selected from 1Ω, 2Ω, 3Ω, 5Ω, 10Ω, 15Ω, 20Ω, 25Ω, 30Ω, 35Ω, 40Ω, 45Ω, and 50Ω.

[0047] Batteries with a positive electrode sheet film resistance of 50Ω or less exhibit excellent Coulomb efficiency, high-temperature performance, and ability to suppress sodium dendrite formation.

[0048] In some embodiments, the film resistance of the positive electrode sheet is 10Ω or less. When the film resistance of the positive electrode sheet is 10Ω or less, the Coulomb efficiency, high-temperature cycle capacity retention rate, and high-temperature storage capacity retention rate of the battery are further improved, and the high-temperature cycle internal resistance and high-temperature storage internal resistance are further reduced.

[0049] In some embodiments, the film-forming additive comprises one or more selected from sulfuric acid ester compounds, sulfonic acid ester compounds, and sulfite ester compounds.

[0050] In this specification, the term "sulfate ester compound" is defined as follows: [ka] This refers to compounds that contain a specific group.

[0051] In this specification, the term "sulfonic acid ester compound" is defined as follows: [ka] base or [ka] This refers to compounds that contain [the specified element].

[0052] In this specification, the term "sulfite ester compound" is defined as follows: [ka] This refers to compounds that contain a specific group.

[0053] Sulfuric acid ester compounds, sulfite ester compounds, and sulfonic acid ester compounds are preferentially reduced over electrolyte salts and solvents, forming a thin, uniform, and dense SEI film on the negative electrode surface, thereby reducing direct contact between the negative electrode and the electrolyte. Furthermore, the salts formed in the SEI film from sulfuric acid ester compounds, sulfite ester compounds, and sulfonic acid ester compounds have high-temperature resistance and can effectively improve the electrochemical performance of the battery at high temperatures. By adding sulfuric acid ester compounds, sulfite ester compounds, and sulfonic acid ester compounds as additives, the Coulomb efficiency, high-temperature cycle performance, and high-temperature storage performance of the battery can be improved, and dendrite formation can be suppressed. In particular, in the case of a negative electrode-less sodium metal battery, the addition of sulfuric acid ester compounds, sulfite ester compounds, and sulfonic acid ester compounds can be effectively combined with the negative electrode current collector to significantly improve sodium loss in the battery due to the solvent, thereby improving the Coulomb efficiency and high-temperature performance of the battery.

[0054] In some embodiments, the sulfate compound includes one or more selected from the compounds represented by Formula I,

Chemical formula

Chemical formula

[0055] As used herein, the term "cyano group" refers to -CN.

[0056] As used herein, the term "olefin group" refers to an unsaturated hydrocarbon group having at least one carbon-carbon double bond.

[0057] As used herein, the term "C 1-6 alkyl group" refers to a straight-chain or branched-chain hydrocarbon chain group composed only of carbon atoms and hydrogen atoms without unsaturation in the group, having 1 to 6 carbon atoms, and bonded to the rest of the molecule by a single bond.

[0058] As used herein, the term "substituted" means that at least one hydrogen atom of the compound or chemical moiety is substituted by another chemical moiety with a substituent, where the substituents are each independently a hydroxyl group, a mercapto group, an amino group, a cyano group, a nitro group, an aldehyde group, a halogen atom, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, C 1-6 alkyl group, C 1-6 selected from alkoxy groups.

[0059] In some embodiments, when n is 0, the carbon atom bonded to R1 and the carbon atom bonded to R2 are directly bonded by a single bond.

[0060] In some embodiments, R1 and R2 are independently hydrogen, fluorine, cyano group, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, vinyl group, propenyl group, [ka] Selected from.

[0061] In some embodiments, the sulfate ester compound is 1,3,2-dioxathiolane 2,2-dioxide (DTD), [ka] ), 4-methyl-1,3,2-dioxathiolane-2,2-dioxide (MeDTD, [ka] ), 4-fluoro-1,3,2-dioxathiolan-2,2-dioxide (FDTD, [ka] ), 4-propyl-1,3,2-dioxathiolan-2,2-dioxide (PEGLST, [ka] ), 4,4'-Bi-1,3,2-dioxathiolane 2,2,2'-2'-tetraoxide (BiDTD, [ka] ), 4-vinyl-1,3,2-dioxathiolane-2,2-dioxide (VDTD, [ka] ), 4-ethyl-1,3,2-dioxathiolane 2,2-dioxide (EtDTD, [ka] ), 4,5-difluoro-1,3,2-dioxathiolan-2,2-dioxide (DFDTD, [ka] ), 4-cyano-1,3,2-dioxathiolane-2,2-dioxide (CDTD, [ka] Includes one or more selected from ).

[0062] The above-mentioned sulfate ester compounds exhibit excellent film-forming properties in secondary batteries, effectively improving the Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance of the batteries. Furthermore, they suppress dendrite formation in the batteries, comprehensively improving the safety and electrochemical performance of the batteries.

[0063] In some embodiments, the sulfate ester compound is selected from one or more of 1,3,2-dioxathiolane-2,2-dioxide, 4-methyl-1,3,2-dioxathiolane-2,2-dioxide, 4-fluoro-1,3,2-dioxathiolane-2,2-dioxide, 4-cyano-1,3,2-dioxathiolane-2,2-dioxide, and 4-vinyl-1,3,2-dioxathiolane-2,2-dioxide.

[0064] The above-mentioned sulfate ester compounds are particularly suitable for electrodeless batteries and can significantly improve the Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance of electrodeless batteries.

[0065] In some embodiments, the sulfonic acid ester compound includes a salt having a sulfonic acid anion, or one or more compounds selected from those represented by formulas II and III. [ka] Here, p is any integer from 0 to 5, and R3 and R4 are independently permutations or non-permutations of C. 1-6 Selected from alkyl groups, [ka] Here, R5 and R6, together with the sulfur and oxygen to which they are bonded, form a 4-membered, 5-membered, or 6-membered ring, which optionally has a double bond and optionally contains one or two sulfonic acid ester groups, and the hydrogen on the ring optionally contains a halogen, C 1-3 It is substituted with an alkyl group.

[0066] In this specification, "C 1-3 The term "alkyl group" is "C 1-6 This can be understood by referring to the definition of the term "alkyl group".

[0067] In this specification, the term "halogen" may refer to F, Cl, Br, or I.

[0068] In some embodiments, p is selected from 1, 2, or 3.

[0069] In some embodiments, R3 and R4 are independently selected from hydrogen, fluorine, cyano group, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, vinyl group, and propenyl group.

[0070] In some embodiments, the sulfonic acid ester compound is 1,3-propanesultone (1,3-PS, [ka] ), 3-fluoro-1,3-propanesultone (FPS, [ka] ), 1-Methyl-1,3-propanesultone(2,4-BS, [ka] ), 1,4-butanesultone (BS, [ka] ), 1,4-butensulfonic acid sultone (BST, [ka] ), 1-propene-1,3-sultone (PES, [ka] ), methylene methane disulfonate (MMDS, [ka] ), 3-(1-pyridinio)-1-propanesulfonate (PPS, [ka] ), 1,4-butanediol dimethanesulfonate (BDDMS, [ka] Includes one or more selected from ).

[0071] The above-mentioned sulfonic acid ester compounds exhibit excellent film-forming properties in secondary batteries, effectively improving the Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance of the batteries. Furthermore, they suppress dendrite formation in the batteries, comprehensively improving the safety and electrochemical performance of the batteries.

[0072] In some embodiments, the sulfonic acid ester compound is selected from one or more of 3-fluoro-1,3-propanesultone, 1-methyl-1,3-propanesultone, 1-propene-1,3-sultone, methylenemethanedisulfonate, 3-(1-pyridinio)-1-propanesultone, and 1,3-propanesultone.

[0073] The above-mentioned sulfonic acid ester compounds are particularly applicable to electrodeless batteries, and can significantly improve the Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance of electrodeless batteries.

[0074] In some embodiments, the sulfite ester compound comprises one or more compounds selected from those represented by formula IV. [ka] Here, R7 and R8 are independently either substituted or non-substituted C. 1-6 Selected from alkyl groups, or R7 and R8, together with the oxygen to which they are bonded and the sulfur to which the oxygen is co-bonded, form a five-membered or six-membered ring, the ring optionally having a double bond, and the hydrogen on the ring optionally being a halogen, C 1-3 It is substituted with an alkyl group.

[0075] In some embodiments, the sulfite ester is 1,3,2-dioxatian 2-oxide [ka] , 1,3,2-dioxathiolane 2-oxide (ES, [ka] ), 4-methyl-1,3-dioxa-2-thia(IV)cyclohexane-2-one (PS, [ka] ), dimethyl sulfite (DMS, [ka] ), diethyl sulfite (DES, [ka] Includes one or more selected from ).

[0076] The above-mentioned sulfite ester compounds exhibit excellent film-forming properties in secondary batteries, effectively improving the Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance of the batteries. Furthermore, they suppress dendrite formation in the batteries, comprehensively improving the safety and electrochemical performance of the batteries.

[0077] In some embodiments, the electrolyte further comprises a sodium salt and an ether-based solvent, where the molar concentration of the sodium salt is 0.5 mol / L to 4 mol / L, and optionally 0.8 mol / L to 2 mol / L.

[0078] In this specification, the term "ether-based solvent" refers to an organic solvent containing an ether bond.

[0079] In some embodiments, the molar concentrations of the sodium salt are 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, and 4 mol / L.

[0080] By controlling the molar concentration of sodium salt within an appropriate range, the Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance of the battery can be improved.

[0081] Molecules of ether-based solvents can construct a stable electrode / electrolyte interface on the negative electrode surface, forming a stable solid electrolyte interface (SEI). This reduces electrochemical polarization and improves the Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance of the battery.

[0082] Taking a non-negative sodium metal battery as an example, ether-based solvents have good compatibility with the sodium metal negative electrode, effectively passivating the sodium metal and forming a thin, uniform, and dense SEI film on the surface of the sodium metal. This further prevents the formation of sodium dendrites and prevents the SEI film from thickening further due to the growth and evolution of sodium dendrites, which would affect ion conduction.

[0083] In some embodiments, the sodium salt includes one or more of the following: sodium hexafluorophosphate (NaPF6), sodium difluoro(oxalato)borate (NaDFOB), sodium tetrafluoroborate (NaBF4), sodium bis(oxalato)borate (NaBOB), sodium perchlorate (NaClO4), sodium hexafluoroar(V)ate (NaAsF6), sodium bis(fluorosulfonyl)imide (NaFSI), sodium trifluoromethanesulfonate (NaOTf), and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI).

[0084] In some embodiments, the ether solvent includes one or more of the following: ethylene glycol dimethyl ether (DME), ethylene glycol diethyl ether (DEE), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (TRGDME), tetraethylene glycol dimethyl ether (TEGDME), 1,3-dioxolane (DOL), tetrahydrofuran (THF), methyltetrahydrofuran (MeTHF), diphenyl ether, crown ether, and fluorinated ether.

[0085] Fluorinated ethers refer to ether-based solvents containing fluorine. In some embodiments, fluorinated ethers include one or more of the following: 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, bis(2,2,2-trifluoroethyl) ether, methyl nonafluorobutyl ether, and ethyl nonafluorobutyl ether.

[0086] In some embodiments, the ether solvent includes one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane, and tetrahydrofuran.

[0087] In some embodiments, the electrolyte includes a solvent other than an ether-based solvent. Non-limiting examples of other solvents include at least one selected from vinylene carbonate, ethylene carbonate, propylene carbonate, ethylmethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, γ-butyrolactone, sulfolane, dimethyl sulfone, ethylmethyl sulfone, and diethyl sulfone.

[0088] In some embodiments, the electrolyte optionally includes other additives that can improve specific performance characteristics of the battery, such as additives that improve the battery's overcharge characteristics and additives that improve the thermal stability of the electrolyte.

[0089] In some embodiments, the positive electrode sheet includes a positive electrode active material, which comprises one or more selected from layered transition metal oxides, polyanionic compounds, or Prussian blue analogs.

[0090] The transition metal contained in the layered transition metal oxide may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Optionally, the layered transition metal oxide may be, for example, Na x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, 0 <x≦1である。

[0091] Polyanionic compounds include metal ions, transition metal ions, and tetrahedral (YO4) ions. n- It may be one of the compounds having an anionic unit. The metal ion may be any one of sodium ions, lithium ions, potassium ions, or zinc ions, the transition metal may be any at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y may be any at least one of P, S, and Si, and n is (YO4) n- This shows the valence state.

[0092] Prussian blue compounds contain sodium ions, transition metal ions, and cyanogen ions (CN - ) may be one of the compounds having ). The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Prussian blue compounds are, for example, Na a Me b Me' c(CN)6, where Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 <a≦2、0<b<1、0<c<1である。

[0093] In some embodiments, the secondary battery is a lithium-ion battery or a sodium-ion battery.

[0094] A lithium-ion battery is a type of battery in which lithium ions move between the positive and negative electrodes.

[0095] A sodium-ion battery is a type of battery in which sodium ions move between the positive and negative electrodes.

[0096] In some embodiments, the secondary battery is a negative electrode-less sodium metal battery. The negative electrode-less sodium metal battery does not use a negative electrode active material, but uses only a negative electrode current collector as the negative electrode. The negative electrode sodium plating is completed during the initial charging process and returns to the positive electrode during discharge, thereby enabling the charge-discharge cycle. Because there is no negative electrode material and only a negative electrode current collector is used, the negative electrode-less battery effectively overcomes the drawbacks of sodium metal batteries and can achieve a higher energy density than a metallic sodium negative electrode. However, because the negative electrode-less battery lacks a negative electrode, it often suffers from problems such as low Coulomb efficiency and severe sodium dendrite formation. This application creatively solves these problems and significantly improves the high-temperature performance of the negative electrode-less battery.

[0097] In some embodiments, the current collector of a non-negative sodium metal battery includes at least one of the following: metal foil, metal foam current collector, metal mesh current collector, carbon felt current collector, carbon cloth current collector, carbon paper current collector, and composite current collector.

[0098] In some embodiments, the metal foil may optionally be copper foil, aluminum foil, stainless steel foil, iron foil, zinc foil, or titanium foil, and the metal foam current collector may optionally be copper foam, aluminum foam, zinc foam, etc. The metal mesh current collector may optionally be copper mesh or aluminum mesh. The composite current collector includes a current collector having a bottom coating or a current collector having a polymer base film. The composite current collector can have a "sandwich" structure with a polymer base film in the center and metal foil on both sides thereof. The composite current collector may also have metal foil on one side of the polymer base film. The polymer base film may optionally be one of the following: polyamide, polyester terephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly-p-phenylene terephthalamide, ethylene propylene rubber, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, or polycarbonate.

[0099] In some embodiments, the secondary battery may include an enclosure. This enclosure can be used to enclose the electrode assembly and electrolyte.

[0100] In some embodiments, the casing of the secondary battery may be a hard shell, such as a rigid plastic shell, an aluminum shell, or a steel shell. Alternatively, the casing of the secondary battery may be a soft pack, such as a pouch soft pack. The material of the soft pack may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0101] This application does not particularly limit the shape of the secondary battery, and it can be cylindrical, prismatic, or any other shape. For example, Figure 1 shows a prismatic secondary battery 5 as an example.

[0102] In some embodiments, referring to Figure 2, the exterior may include a shell 51 and a cover plate 53. Here, the shell 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates enclose a housing chamber. The shell 51 has an opening that communicates with the housing chamber, and the cover plate 53 may be provided over the opening to close the housing chamber. The positive electrode sheet, negative electrode sheet and separator can be formed into an electrode assembly 52 by a winding or lamination process. The electrode assembly 52 is sealed within the housing chamber. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and can be selected according to practical needs by those skilled in the art.

[0103] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, the specific number of which can be selected by those skilled in the art based on the application and capacity of the battery module.

[0104] Figure 3 shows an example of a battery module 4. Referring to Figure 3, in the battery module 4, the multiple secondary batteries 5 may be arranged sequentially along the length of the battery module 4. Of course, they may be arranged in any other way. Furthermore, the multiple secondary batteries 5 can be fixed together with fasteners.

[0105] Optionally, the battery module 4 may further include a casing having a housing space for housing a plurality of secondary batteries 5.

[0106] In some embodiments, the above-described battery modules can be further assembled into a battery pack, the number of battery modules included in the battery pack may be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery pack.

[0107] Figures 4 and 5 show an example of a battery pack 1. Referring to Figures 4 and 5, the battery pack 1 may include a battery case and a plurality of battery modules 4 provided within the battery case. The battery case includes an upper case 2 and a lower case, the upper case 2 being provided on top of the lower case 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged within the battery case in any manner.

[0108] Furthermore, this application further provides power-consuming devices, each comprising at least one of the secondary batteries, battery modules, or battery packs provided herein. The secondary batteries, battery modules, or battery packs can be used as a power source for the power-consuming device or as an energy storage unit for the power-consuming device. Power-consuming devices include, but are not limited to, mobile devices (such as mobile phones and laptops), electric vehicles (such as battery electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, and electric trucks), electric trains, ships, satellites, and energy storage systems.

[0109] As a power-consuming device, users can choose between a secondary battery, battery module, or battery pack depending on their usage needs.

[0110] Figure 6 shows an example of a power-consuming device. This power-consuming device is a battery-powered electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In this power-consuming device, a battery pack or battery module can be used to meet the requirements for high power output and high energy density of secondary batteries.

[0111] Other examples of devices may include mobile phones, tablets, and laptop computers. These devices are typically required to be lightweight and thin, and can use rechargeable batteries as a power source.

[0112] Examples The following describes embodiments of this application. The embodiments described below are illustrative and are used solely for the purpose of interpreting this application and are not intended to limit it. Where specific techniques or conditions are not shown in the embodiments, they shall be carried out in accordance with the techniques and conditions described in the literature of the art or in the instruction manuals of the products. For reagents and equipment whose manufacturers are not specified, commercially available conventional products shall be used. The following embodiments show only cases where the secondary battery is a sodium-ion battery, but this application is not limited thereto.

[0113] 1. Manufacturing Method Example 1 (1) Preparation of the positive electrode sheet The total weight of the polyvinylidene fluoride binder, carbon black conductive agent, and positive electrode active material Na4Fe3(PO4)2P2O7 is 100 parts by weight, and 10 parts by weight of the polyvinylidene fluoride binder is N - A paste was prepared by thoroughly dissolving methylpyrrolidone, adding 10 parts by weight of a carbon black-based conductive agent and 780 parts by weight of the positive electrode active material Na4Fe3(PO4)2P2O, and uniformly dispersing it. The paste was uniformly applied to the surface of aluminum foil, and then transferred to a vacuum drying oven for complete drying. The resulting sheet was roller-pressed and punched to obtain a positive electrode sheet.

[0114] (2) Fabrication of the negative electrode sheet The total weight of the negative electrode paste was set to 100 parts by weight. 4 parts by weight of carbon nanotube material and 1.6 parts by weight of sodium carboxymethylcellulose, a polymer binder, were added to water and stirred to form a uniform paste. The paste was then applied to the surface of copper foil, and after being completely dried in a vacuum drying oven, it was punched out to obtain a negative electrode sheet.

[0115] (3) Preparation of electrolyte In a glove box under an argon atmosphere (H2O < 0.1 ppm, O2 < 0.1 ppm), sodium hexafluorophosphate (NaPF6), a sodium salt, and 1,3-propanesultone (1,3-PS) were dissolved in ethylene glycol dimethyl ether (DME), an organic solvent, and uniformly stirred to obtain an electrolyte with a sodium salt concentration of 1 mol / L, i.e., the electrolyte of Example 1.

[0116] (4) Separator A polypropylene film was used as the separator.

[0117] (5) Making a battery The positive electrode sheet, separator, and negative electrode sheet are stacked in that order, with the separator acting as a separator between the positive and negative electrode sheets, and the electrolyte is added to assemble the stacked battery.

[0118] Examples 2-37 The steps in Examples 2 to 37 are the same as those in Example 1, except for the difference in the electrolyte formulation method. Here, the film resistance of the positive electrode sheet is adjusted by adjusting the compression density of the positive electrode sheet.

[0119] Comparative Examples 1-4 The steps in Comparative Examples 1 to 4 are the same as those in Example 1, except for the method of compounding the electrolyte. The specific parameters are shown in Table 1.

[0120] 2. Battery performance test 1. Film resistance test The positive electrode sheet was sandwiched between the two conductive terminals of a HIOKI BT23562 internal resistance tester, and pressure was applied to fix it in place. The diameter of the conductive terminals was set to 14 mm, and the resistance R of the positive electrode sheet was measured by applying a pressure of 15 MPa to 27 MPa.

[0121] 2. Coulomb efficiency Using Example 1 as an example, the prepared sodium secondary battery was charged to 3.7V at 25°C with a constant current of 1 / 3C, then charged again at a constant voltage of 3.7V until the current dropped to 0.05C to obtain the initial charge capacity (Cc1), and then discharged to 2.5V with a constant current of 1 / 3C to obtain the initial discharge capacity (Cd1). The Coulomb efficiency of the sodium battery was then calculated according to the following formula.

[0122] Coulomb efficiency of a sodium battery = Initial discharge capacity (Cd1) / Initial charge capacity (Cc1) * 100% The test procedures for comparative examples and other examples are the same as described above.

[0123] 3. High-temperature cycle capacity maintenance rate Using Example 1 as an example, a sodium battery was charged to 3.7V at 45°C with a constant current of 1C, then charged again at a constant voltage of 3.7V until the current dropped to 0.05C, and discharged to 2.5V with a constant current of 1C to obtain the initial cycle discharge capacity (Cd1). After repeating the charge-discharge cycle up to the nth cycle, the discharge capacity of the sodium battery after the nth cycle was obtained and recorded as Cdn, and the capacity retention rate of the sodium battery was calculated according to the following formula.

[0124] Capacity retention rate = Discharge capacity after n cycles (Cdn) / Initial cycle discharge capacity (Cd1) * 100% In this application, the high-temperature cycle capacity retention rate refers to the capacity retention rate of the battery after 100 cycles at high temperatures.

[0125] The test procedures for comparative examples and other examples are the same as described above.

[0126] 4. High-temperature cycle DCR DC internal resistance (DCR) is the resistance of the current inside the cell. When the battery discharge process ends, the battery voltage rebounds due to the presence of polarization. In the DC impedance method, the internal resistance of the battery is calculated using the voltage difference between the instantaneous voltage before the end of discharge and the stable voltage after the end of discharge during the intermittent discharge process of the battery.

[0127] Using Example 1 as an example, a sodium-ion battery was charged to 3.7V at 25°C with a constant current of 1C, then charged again at a constant voltage of 3.7V until the current dropped to 0.05C, discharged to 2.5V with a constant current of 1C, then left for 5 minutes (stabilization time), and the next cycle was continued. In each cycle, the battery voltage before discharge stopped and the battery voltage after stabilization were recorded, and the DC impedance was calculated using the following formula. R = ΔU / I (where ΔU is the voltage difference, R is the DC resistance, and I is the discharge current)

[0128] The high-temperature cycle DCR measured in this application is the DC impedance of the battery after 100 cycles at high temperature.

[0129] The measurement process for comparative examples and other examples is the same as described above.

[0130] 5. Sodium dendrites The sodium battery described above, after 100 cycles, was decomposed in a glove box under an argon atmosphere (H2O < 0.1 ppm, O2 < 0.1 ppm), and the surface morphology of the negative electrode sheet was visually observed to determine whether or not sodium dendrites had formed.

[0131] If there are no white spots on the negative electrode sheet, sodium dendrites are judged to be "absent".

[0132] If there are scattered white spots on the negative electrode sheet, the sodium dendrites are judged to be "slight."

[0133] If the negative electrode sheet has a dense concentration of white spots, sodium dendrites are judged to be "severe."

[0134] The test procedures for comparative examples and other examples are the same as described above.

[0135] 6. High temperature storage capacity retention rate In Example 1, a sodium battery was charged to 3.7V at 25°C with a constant current of 1C, then charged at a constant voltage of 3.7V until the current decreased to 0.05C, and discharged to 2.5V with a constant current of 1C to obtain the discharge capacity (Cda) before storage. In this step, the sodium battery was charged to 3.7V at 25°C with a constant current of 1C, then charged at a constant voltage of 3.7V until the current decreased to 0.05C, and the battery was charged to 100% SOC. The batteries were stored in a constant temperature environment of 45°C for 60 days. After 60 days, the batteries were removed from the constant temperature environment of 45°C, cooled to room temperature, and then charged to 3.7V with a constant current of 1C at 25°C. Subsequently, they were charged again with a constant voltage of 3.7V until the current dropped to 0.05C, and then discharged to 2.5V with a constant current of 1C. The discharge capacity of the sodium batteries after 60 days of storage was obtained and recorded as Cdb, and the capacity retention rate of the sodium batteries was calculated according to the following formula.

[0136] Capacity retention rate = Discharge capacity after 60 days of storage (Cdb) / Discharge capacity before storage (Cda) * 100%.

[0137] The test procedures for comparative examples and other examples are the same as described above.

[0138] 7, high temperature storage DCR Using Example 1 as an example, the sodium battery, which had been stored at 45°C for 60 days as described above, was charged to 3.7V at 25°C with a constant current of 1C. Then, it was charged again with a constant voltage of 3.7V until the current dropped to 0.05C, discharged to 2.5V with a constant current of 1C, and then left for 5 minutes (stabilization time). The battery voltage before discharge stopped and the battery voltage after the battery voltage stabilized were recorded, and the DC impedance was calculated using the following formula. R = ΔU / I (where ΔU is the voltage difference, R is the DC resistance, and I is the discharge current)

[0139] The test procedures for comparative examples and other examples are the same as described above.

[0140] III. Test Results The test results for the above examples and comparative examples are shown in Table 1.

[0141] [Table 1-1] [Table 1-2] As can be seen from Table 1, the positive electrode film resistance xΩ of the non-negative sodium batteries of Examples 1 to 37 and the mass content y% of the film-forming additive based on the total mass of the electrolyte satisfy the relationship x*y≦25. Compared with Comparative Examples 1 to 4, the sodium batteries of Examples 1 to 37 exhibit high Coulomb efficiency, high-temperature cycle capacity retention rate and high-temperature storage capacity retention rate, low high-temperature cycle DC internal resistance (DCR) and high-temperature storage DCR, and do not contain sodium dendrites on the sheet.

[0142] As can be seen from Examples 1 to 5, when the mass content of the film-forming additive in the electrolyte is 0.2% to 5% based on the total mass of the electrolyte, the battery exhibits excellent Coulombic efficiency, high-temperature performance, and sodium dendrite formation suppression ability. When the mass content of the film-forming additive in the electrolyte is 0.5% to 2% based on the total mass of the electrolyte, the Coulombic efficiency of the battery is further improved, the high-temperature cycle capacity retention rate and high-temperature storage capacity retention rate are further improved, and the high-temperature cycle resistance is further reduced.

[0143] As can be seen from Examples 1 to 37, when the film resistance of the positive electrode sheet is 50 Ω or less, the battery exhibits excellent Coulomb efficiency, high-temperature performance, and ability to suppress sodium dendrite formation. As can be seen from a comparison of Examples 1, 6, 7 and Example 8, when the film resistance of the positive electrode sheet is 10 Ω or less, the Coulomb efficiency, high-temperature cycle capacity retention rate, and high-temperature storage capacity retention rate of the battery are further improved, and the high-temperature cycle internal resistance and high-temperature storage internal resistance are further reduced.

[0144] It should be noted that in Comparative Examples 1 and 2, although the film-forming additive content y% of the non-negative electrode sodium battery and the internal resistance xΩ of the positive electrode film are within the above range, the relationship x*y≦25 is not satisfied. As a result, although the performance is improved compared to Comparative Examples 3 and 4, the Coulomb efficiency of the battery cannot be increased to 90% or more to meet practical requirements.

[0145] As can be seen from Examples 1 to 37, the film-forming additive comprises one or more compounds selected from sulfuric acid ester compounds, sulfonic acid ester compounds, and sulfite ester compounds. As can be seen from the comparison between Examples 1 to 37 and Comparative Examples 3 to 4, the above film-forming additive significantly improved Coulomb efficiency, high-temperature performance, and sodium dendrite formation suppression ability.

[0146] As can be seen from the comparison of Examples 1, 13-22 and Example 23, sulfuric acid ester compounds and sulfonic acid ester compounds are more effective than sulfite ester compounds in improving Coulomb efficiency and high-temperature battery performance. Here, 3-fluoro-1,3-propanesultone (FPS), 4-methyl-1,3,2-dioxathiolane-2,2-dioxide (MeDTD), and 4-fluoro-1,3,2-dioxathiolane-2,2-dioxide (FDTD) can further increase the Coulomb efficiency of electrodeless batteries to over 93% and the high-temperature cycle capacity retention rate to over 91%. 1-propene-1,3-sultone (PES) and 1,3,2-dioxathiolane-2,2-dioxide (DTD) can increase the Coulomb efficiency of electrodeless batteries to over 94% and the high-temperature cycle capacity retention rate to over 92%. 1,3-propanesultone (1,3-PS) can increase the Coulomb efficiency of non-negative electrode batteries to over 95% and the high-temperature cycle capacity retention rate to over 93%.

[0147] As can be seen from the comparison between Examples 24-27 and Example 28, ether-based solvents are more suitable for electrodeless sodium batteries than ester-based solvents and contribute to improving the Coulomb efficiency and electrochemical performance of electrodeless sodium batteries. Ethylene glycol dimethyl ether (DME) and diethylene glycol dimethyl ether (DEGDME) contained in ether-based solvents showed excellent compatibility with electrodeless sodium batteries and significantly improved the Coulomb efficiency and high-temperature cycle capacity retention rate of electrodeless sodium batteries.

[0148] As can be seen from Examples 1, 29-32, when the molar concentration of the electrolyte sodium salt is 0.5 mol / L to 4 mol / L, the electrodeless sodium battery can effectively ensure excellent Coulombic efficiency, high-temperature performance, and sodium dendrite growth inhibition ability. As can be seen from a comparison between Examples 1, 30, 31 and Examples 29, 32, when the molar concentration of the electrolyte sodium salt is 0.8 mol / L to 2 mol / L, the Coulombic efficiency of the electrodeless sodium battery improved to over 91%, and the high-temperature cycle capacity retention rate improved to over 90%, demonstrating superior electrochemical performance.

[0149] As can be seen from Examples 33-37, sodium salts such as sodium hexafluorophosphate (NaPF6), sodium difluoro(oxalato)borate (NaDFOB), sodium tetrafluoroborate (NaBF4), sodium bis(fluorosulfonyl)imide (NaFSI), sodium trifluoromethanesulfonate (NaOTf), and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) are applicable to the technical solutions provided in this application, and negative electrode batteries using these as electrolyte salts all exhibited excellent Coulomb efficiency, high-temperature cycling performance, and high-temperature storage performance.

[0150] This application is not limited to the embodiments described above. The embodiments described above are merely examples, and embodiments that have substantially the same configuration as the technical idea and achieve the same effects within the scope of the technical solutions of this application are included in the technical scope of this application. Furthermore, other methods of constructing embodiments by adding various modifications that a person skilled in the art could conceive, or by combining some of the components of the embodiments, without departing from the spirit of this application, are also included in the scope of this application. [Explanation of symbols]

[0151] 1 battery pack 2 Upper Case 3 Lower Case 4 battery modules 5 secondary battery 51 shells 52 Electrode Assembly 53 Cover Plate

Claims

1. It comprises a positive electrode sheet and an electrolyte, the electrolyte comprising a film-forming additive, A secondary battery characterized in that the film resistance xΩ of the positive electrode sheet and the mass content y% of the film-forming additive based on the total mass of the electrolyte satisfy the relationship x * y ≤ 25.

2. The secondary battery according to claim 1, characterized in that the mass content of the film-forming additive contained in the electrolyte is 0.2% to 5%, and optionally 0.5% to 2%, of the total mass of the electrolyte.

3. The secondary battery according to claim 1 or 2, characterized in that the film resistance of the positive electrode sheet is 50 Ω or less, and optionally 10 Ω or less.

4. The secondary battery according to any one of claims 1 to 3, characterized in that the film-forming additive includes one or more of a sulfate ester compound, a sulfonic acid ester compound, and a sulfite ester compound.

5. The aforementioned sulfate ester compound comprises one or more compounds represented by formula I, 【Chemistry 1】 Here, n is any integer from 0 to 3, and R １ , R ２ Each of these independently consists of hydrogen, fluorine, cyano group, olefin group, and substituted or unsubstituted C. １－６ alkyl group, 【Chemistry 2】 A secondary battery according to claim 4, characterized by being selected from the above.

6. The secondary battery according to claim 4 or 5, characterized in that the sulfate ester compound comprises one or more of the following: 1,3,2-dioxathiolane 2,2-dioxide, 4-methyl-1,3,2-dioxathiolane-2,2-dioxide, 4-fluoro-1,3,2-dioxathiolane-2,2-dioxide, 4-propyl-1,3,2-dioxathiolane-2,2-dioxide, 4,4'-bi-1,3,2-dioxathiolane 2,2,2'-2'-tetraoxide, 4-vinyl-1,3,2-dioxathiolane-2,2-dioxide, 4-ethyl-1,3,2-dioxathiolane 2,2-dioxide, 4,5-difluoro-1,3,2-dioxathiolane-2,2-dioxide, and 4-cyano-1,3,2-dioxathiolane-2,2-dioxide.

7. The aforementioned sulfonic acid ester compound includes a salt having a sulfonic acid anion, or one or more compounds selected from those represented by formulas II and III. 【Transformation 3】 Here, p is any integer from 0 to 5, and R ３ , R ４ Each of these independently represents a substitution or non-substitution of C. １－６ Selected from alkyl groups, 【Chemistry 4】 Here, R ５ and R ６ together with the sulfur and oxygen to which they are attached form a 4-, 5- or 6-membered ring, the ring optionally having a double bond and optionally containing one or two sulfonic acid ester groups, and the hydrogen on the ring is optionally halogen, C １－３ substituted with an alkyl group, The secondary battery according to any one of claims 4 to 6, characterized in that.

8. The secondary battery according to any one of claims 4 to 7, characterized in that the sulfonic acid ester compound comprises one or more selected from 1,3-propanesultone, 3-fluoro-1,3-propanesultone, 1-methyl-1,3-propanesultone, 1,4-butanesultone, 1,4-butensulfonic acid sultone, 1-propene-1,3-sultone, methylenemethanedisulfonate, 3-(1-pyridinio)-1-propanesulfonate, and 1,4-butanediol dimethanesulfonate.

9. The aforementioned sulfite ester compound comprises one or more compounds selected from the compounds represented by formula IV, 【Transformation 5】 Here, R ７ , R ８ Each of these independently represents a substitution or non-substitution of C. １－６ Selected from alkyl groups, or R ７ and R ８ These, together with the oxygen to which they are bonded, and the sulfur to which the oxygen is co-bonded, form a five-membered or six-membered ring, the ring optionally having a double bond, and the hydrogen on the ring optionally being a halogen, C １－３ A secondary battery according to any one of claims 4 to 8, characterized in that it is substituted with an alkyl group.

10. The secondary battery according to any one of claims 4 to 9, characterized in that the sulfite ester comprises one or more selected from 1,3,2-dioxatian 2-oxide, 1,3,2-dioxathiolane 2-oxide, 4-methyl-1,3-dioxa-2-thia(IV)cyclohexane-2-one, dimethyl sulfite, and diethyl sulfite.

11. The secondary battery according to any one of claims 1 to 10, wherein the electrolyte further comprises a sodium salt and an ether-based solvent, wherein the molar concentration of the sodium salt is 0.5 mol / L to 4 mol / L, and optionally 0.8 mol / L to 2 mol / L.

12. The secondary battery according to claim 11, characterized in that the sodium salt comprises one or more selected from sodium hexafluorophosphate, sodium difluoro(oxalato)borate, sodium tetrafluoroborate, sodium bis(oxalato)borate, sodium perchlorate, sodium hexafluoroarsenate (V), sodium bis(fluorosulfonyl)imide, sodium trifluoromethanesulfonate, and sodium bis(trifluoromethanesulfonyl)imide.

13. The secondary battery according to claim 11 or 12, characterized in that the ether-based solvent includes one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, crown ether, and fluorinated ether.

14. The secondary battery according to any one of claims 1 to 13, wherein the positive electrode sheet comprises a positive electrode active material, and the positive electrode active material comprises one or more selected from layered transition metal oxides, polyanionic compounds, or Prussian blue analogs.

15. The secondary battery according to any one of claims 1 to 14, characterized in that the secondary battery is either a lithium-ion battery or a sodium-ion battery.

16. The secondary battery according to any one of claims 1 to 15, characterized in that the secondary battery is a sodium metal battery without a negative electrode.

17. A battery module characterized by including a secondary battery according to any one of claims 1 to 16.

18. A battery pack characterized by including a secondary battery according to any one of claims 1 to 16 or a battery module according to claim 17.

19. A power consumption device characterized by comprising at least one selected from a secondary battery according to any one of claims 1 to 16, a battery module according to claim 17, or a battery pack according to claim 18.

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