Sodium ion battery electrolyte, secondary battery, battery module, battery pack, and power consumption device

Abstract

The present application provides a sodium ion battery electrolyte, having the formula NaBO a F x R y -z The present application also provides a secondary battery, a battery module, a battery pack, and a power consuming device using the sodium ion battery electrolyte.

Description

[Technical field]

[0001] The present application relates to the field of secondary battery technology, and in particular to a sodium ion battery electrolyte, a secondary battery, a battery module, a battery pack, and a power consuming device using the same. [Background technology]

[0002] In recent years, the demand for lithium ion batteries has been increasing, but the limited lithium resource has restricted the sustainable development of lithium ion batteries. As an important complement to lithium ion batteries, sodium ion secondary batteries have been attracting more and more attention. As a transport carrier of sodium ions in batteries, sodium ion battery electrolytes can improve or enhance various performances of batteries, and are an important component of sodium ion batteries. However, the sodium ion battery electrolytes used in the prior art have poor stability, especially antioxidation ability, and low solvation power of sodium ions, especially under high potentials, which is disadvantageous to the expansion of the potential window of sodium ion batteries, the improvement of Coulombic efficiency, and the improvement of cycle characteristics and safety performance. Therefore, how to provide an electrolyte that has good stability and can effectively adjust the solvation power of sodium ions at the same time remains a difficult problem to be solved by those skilled in the art. Summary of the Invention [Problem to be solved by the invention]

[0003] The present application has been made in view of the above problems, and aims to provide an electrolyte solution having good stability, particularly anti-oxidation property and good sodium ion solvation power, thereby widening the potential window of the corresponding sodium ion battery, improving the Coulombic efficiency, and improving the cycle characteristics and safety performance. [Means for solving the problem]

[0004] In order to achieve the above object, according to a first aspect of the present invention, there is provided a compound represented by the formula NaBO a F x R y-z a sodium ion battery electrolyte solution comprising a sodium salt of the above formula (I), a fluoroalkyl ether, and an ether other than the fluoroalkyl ether; Formula NaBO a F x R y -z In the sodium salt of the formula (I), 2a+x+y×z=2 or 4, 0≦a≦3, 0≦x≦4, 0≦y, 0≦z, and 0≦y×z≦4; and R is an oxalic acid group ( [ka] ), a phenyl group, a cyano group, a C1-C6-fluoroalkyl group, such as a trifluoromethyl group, a pentafluoroethyl group, a 2,2,2-trifluoroethyl group, a C1-C6-alkoxy group, such as a methoxy group, an ethoxy group, The other ethers are selectively selected from one or more of aliphatic ethers having 4 to 20 carbon atoms, alicyclic ethers having 3 to 8 carbon atoms, aromatic ethers having 7 to 20 carbon atoms, and crown ethers.

[0005] The electrolyte of the present application has good stability and sodium ion solvation power, which is advantageous for widening the potential window of the corresponding secondary battery, improving the Coulombic efficiency, and improving the cycle characteristics and safety performance.

[0006] In any embodiment, optionally, the sodium-ion battery electrolyte satisfies one or more of the following conditions (1) to (5):

[0007] (1) The above formula NaBO a F x R y -z The content of the sodium salt is 5 to 40 wt %, and may be 10 to 20 wt %.

[0008] (2) The content of the fluoroalkyl ether is 1 to 82 wt %, may be 1 to 48 wt %, may be 1 to 20 wt %, or may be 2 to 8 wt %.

[0009] (3) The above formula NaBO a F x R y -z The total content of the sodium salt and the fluoroalkyl ether is 10 to 95 wt %, may be 10 to 60 wt %, or may be 12 to 28 wt %.

[0010] (4) The content of the other ethers is 5 to 90 wt %, may be 40 to 90 wt %, or may be 72 to 88 wt %.

[0011] (5) The above formula NaBO a F x R y -z The concentration of the sodium salt is 0.5 to 8 mol / L, and may be 1 to 4 mol / L.

[0012] The contents in the conditions (1) to (4) are all relative to the total weight of the sodium ion battery electrolyte, and the total weight of each component in the sodium ion battery electrolyte is 100 wt %.

[0013] When the sodium ion battery electrolyte satisfies one or more of the above conditions, it is advantageous to further expand the potential window of the corresponding secondary battery, improve the Coulombic efficiency, and improve the cycle characteristics and safety performance.

[0014] In any embodiment, optionally, the formula NaBO a F x R y -z the mass ratio of the sodium salt to the fluoroalkyl ether is 1:0.08 to 6, may be 1:0.08 to 4, or may be 1:0.1 to 0.8; Alternatively, the mass ratio of the fluoroalkyl ether to the ether other than the fluoroalkyl ether is 1:0.06-90, may be 1:2-90, or may be 1:9-44.

[0015] When the ratio of each component in the sodium ion battery electrolyte satisfies one or more of the above conditions, it is advantageous to further expand the potential window of the corresponding secondary battery, improve the Coulombic efficiency, and improve the cycle characteristics and safety performance.

[0016] In any embodiment, optionally, the formula NaBO a F x R y -z is selected from one or more of sodium difluoroborate, sodium tetrafluoroborate, sodium dioxalatoborate, sodium difluorooxalatoborate, sodium tetraphenylborate, sodium tetracyanoborate, sodium tetra(trifluoromethyl)borate, sodium bis(trifluoromethyl)difluoroborate, sodium pentafluoroethyltrifluoroborate, sodium dicyanooxalatoborate, sodium methoxytricyanoborate, sodium ethoxytricyanoborate, sodium tetramethoxyborate, sodium tetraethoxyborate, sodium cyanotri(2,2,2-trifluoroethyl)borate; It may be one or more of sodium dioxalatoborate, sodium difluorooxalatoborate, sodium tetra(trifluoromethyl)borate, sodium bis(trifluoromethyl)difluoroborate, sodium dicyanooxalatoborate.

[0017] The appropriate formula NaBO a F x R y -z By selecting the sodium salt of the above, it is advantageous to further widen the potential window of the corresponding secondary battery, improve the Coulombic efficiency, and improve the cycle characteristics and safety performance.

[0018] In any embodiment, optionally, the fluoroalkyl ether is selected from one or more of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, bis(2,2,2-trifluoroethyl) ether, 1,1,2,2,-tetrafluoroethyl-2,2,2-trifluoroethyl ether, methoxynonafluorobutane, and ethoxynonafluorobutane.

[0019] In any embodiment, the other ethers are optionally selected from one or more of ethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, crown ether; It may be one or more of ethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether.

[0020] By selecting appropriate fluoroalkyl ethers and other ethers, it is advantageous to further widen the potential window of the corresponding secondary battery, improve the Coulombic efficiency, and improve the cycle characteristics and safety performance.

[0021] In any embodiment, optionally, the sodium ion battery electrolyte does not contain a carbonate ester, or when a carbonate ester is present, the ratio of the weight percent content of the carbonate ester to the weight percent content of all the ether solvents is 1:9 to 3:2, and may be 1:6 to 1:1.

[0022] According to a second aspect of the present application, there is provided a sodium-ion secondary battery comprising the sodium-ion battery electrolyte of the first aspect of the present application.

[0023] According to a third aspect of the present application, there is provided a battery module including the sodium ion secondary battery according to the second aspect of the present application.

[0024] According to a fourth aspect of the present application, there is provided a battery pack including at least one of the sodium ion secondary battery according to the second aspect of the present application or the battery module according to the third aspect of the present application.

[0025] According to a fifth aspect of the present application, there is provided a power consumption device including at least one of the sodium ion secondary battery according to the second aspect of the present application, the battery module according to the third aspect of the present application, or the battery pack according to the fourth aspect of the present application. Effect of the Invention

[0026] The sodium ion battery electrolyte of the present application has the formula NaBO a F x R y -z The above substances act synergistically to improve the solvation power of sodium ions, improve the stability of the electrolyte, particularly the antioxidation property, and improve the self-discharge of the secondary battery in a high-temperature environment, thereby improving the cycle characteristics, expanding the potential window, and improving the Coulombic efficiency of the corresponding secondary battery.

[0027] The battery modules, battery packs and power consuming devices described herein include the sodium ion secondary batteries described herein and therefore have at least the same advantages as said secondary batteries. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application. [Diagram 2] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. [Diagram 3] FIG. 1 is a schematic diagram of a battery module according to an embodiment of the present application. [Figure 4] FIG. 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Diagram 5]FIG. 5 is an exploded view of the battery pack according to the embodiment of the present application shown in FIG. 4. [Figure 6] 1 is a schematic diagram of a power consuming device that uses a secondary battery as a power source according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, the embodiments specifically disclosing the sodium ion battery electrolyte, the secondary battery, the battery module, the battery pack, and the power consumption device using the same will be described in detail with reference to the drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and redundant description of substantially the same structure may be omitted. This is to prevent the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0030] The "ranges" disclosed herein are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner may or may not include the endpoints and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are recited for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Also, if minimum range values ​​1 and 2 are recited, and maximum range values ​​3, 4, and 5 are recited, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all contemplated. In this application, unless otherwise stated, the numerical range "a-b" means a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are recited herein, and "0-5" is merely a shorthand for combinations of these numerical values. Furthermore, expressing a parameter as an integer ≧2 is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0032] All technical features and optional technical features in the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0033] All steps in this application can be performed in sequence or randomly, and are preferably performed in sequence, unless otherwise stated. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in sequence, or may include steps (b) and (a) performed in sequence. For example, when the method may further include step (c), it means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0034] The terms "comprise" and "comprises" referred to in this application refer to both open and closed formats unless otherwise specified. For example, the terms "comprise" and "comprises" can indicate that other elements not listed may also be included or may include, or that only the listed elements may be included or may include.

[0035] In this application, unless otherwise stated, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied by either A being true (or present) and B being false (or absent), or A being false (or absent) and B being true (or present), or both A and B being true (or present).

[0036] In the course of research, the inventors have found that the conventional sodium ion battery electrolyte is insufficient in terms of stability, especially in terms of anti-oxidation, which is disadvantageous for improving the performance of the corresponding secondary battery. Through much research, the inventors have found that the electrolyte contains a compound of the formula NaBO a F x R y -zThe inventors have found that the inclusion of sodium salt of and ether compounds (including fluoroalkyl ethers and other ethers) at the same time is advantageous in significantly expanding the potential window of the corresponding secondary battery, improving the Coulombic efficiency, and improving the cycle characteristics and safety performance by utilizing the synergistic effect of each substance. Furthermore, the inventors have further studied the type, content and compounding ratio of each substance, and found that the battery performance can be further improved by adjusting these factors.

[0037] [Electrolyte] According to a first aspect of the present application, a compound of the formula NaBO a F x R y -z a sodium ion battery electrolyte solution comprising a sodium salt of the above formula (I), a fluoroalkyl ether, and an ether other than the fluoroalkyl ether; Formula NaBO a F x R y -z In the sodium salt of the formula (I), 2a+x+y×z=2 or 4, 0≦a≦3, 0≦x≦4, 0≦y, 0≦z, and 0≦y×z≦4; and R is an oxalic acid group ( [ka] ), a phenyl group, a cyano group, a C1-C6-fluoroalkyl group, such as a trifluoromethyl group, a pentafluoroethyl group, a 2,2,2-trifluoroethyl group, a C1-C6-alkoxy group, such as a methoxy group, an ethoxy group, The other ethers are selectively selected from one or more of aliphatic ethers having 4 to 20 carbon atoms, alicyclic ethers having 3 to 8 carbon atoms, aromatic ethers having 7 to 20 carbon atoms, and crown ethers.

[0038] The sodium ion battery electrolyte of the present application has the formula NaBO a F x R y -zIn the electrolyte, the ether solvent includes the sodium salt of the formula NaBO a F x R y -z It can form a solvation structure with the sodium salt of the above, which is advantageous to improve the solvation power of sodium ions, thereby promoting the free movement of sodium ions, reducing the consumption of active sodium ions, and improving the cycle characteristics of the corresponding battery.

[0039] The electrolyte of the present application has the formula NaBO a F x R y -z The sodium salt helps to reduce the self-discharge of the corresponding secondary battery in a high temperature environment, and improves the capacity retention characteristics, thereby improving the coulombic efficiency.

[0040] The electrolyte of the present application comprises fluoroalkyl ether, which has high antioxidant capacity and can associate with boric acid anions, reducing the number of molecules of other ethers in the solvent and structure formed, thereby greatly improving the stability of the electrolyte, especially the antioxidant capacity. The improvement of the stability of the electrolyte, especially the antioxidant capacity, is helpful in widening the potential window of the corresponding secondary battery.

[0041] At the same time, the fluoroalkyl ether introduces a large amount of fluorine ions into the electrolyte, thereby promoting the formation of a stable NaF-rich interfacial film on the surface of the negative electrode. The stable NaF-rich interfacial film is favorable for inhibiting side reactions, thereby avoiding the side reaction products from covering the surface of the negative electrode, avoiding the sodium ion aggregation caused by the blocking of the sodium ion migration channel, and reducing the formation of sodium dendrites, which is not only favorable for improving the safety performance of the corresponding secondary battery, but also favorable for reducing the consumption of active sodium ions, thereby improving the cycle characteristics.

[0042] In addition, ether solvent molecules (including fluoroalkyl ether) can build a stable electrode / electrolyte interface on the surface of sodium metal negative electrodes (including non-negative electrodes), carbon material negative electrodes and other non-carbon material negative electrodes, forming a stable solid electrolyte interface film (SEI, Solid Electrolyte Interface) and reducing electrochemical polarization. In particular, for graphite systems, sodium ions and ether solvent molecules can generate a highly reversible co-intercalation reaction in graphite to form a stable graphite ternary intercalation compound, thereby improving the stability of the corresponding negative electrodes of secondary batteries.

[0043] In addition, the formula NaBO a F x R y -z In the sodium salt of the formula (I), 0≦a≦3 and may be 0. -z is the valence of the R group, e.g., when R is a cyano group, -z is -1, when R is a methoxy group or an ethoxy group, -z is -1, and when R is an oxalic acid group, -z is -2.

[0044] In a further alternative embodiment, a, x, y, and z are all integers.

[0045] It should be noted that, as understood by those skilled in the art, in the electrolyte of the present application, fluoroalkyl ether and other ethers are present at the same time, but there is no specific requirement for the ratio of the two, and the two can be mixed in any ratio to achieve the technical goal of the present application, but fluoroalkyl ether is more expensive. In order to further optimize the technical effect and take into account the cost-effectiveness, the inventors have conducted research on the content and mixing ratio of each component as follows:

[0046] In some embodiments, optionally, the sodium-ion battery electrolyte of the present application satisfies one or more of the following conditions (1) to (5):

[0047] (1) The above formula NaBO a F xR y -z The content of the sodium salt is 5 to 40 wt %, and may be 10 to 20 wt %.

[0048] (2) The content of the fluoroalkyl ether is 1 to 82 wt %, may be 1 to 48 wt %, may be 1 to 20 wt %, or may be 2 to 8 wt %.

[0049] (3) The above formula NaBO a F x R y -z The total content of the sodium salt and the fluoroalkyl ether is 10 to 95 wt %, may be 10 to 60 wt %, or may be 12 to 28 wt %.

[0050] (4) The content of the other ethers is 5 to 90 wt %, may be 40 to 90 wt %, or may be 72 to 88 wt %.

[0051] (5) The above formula NaBO a F x R y -z The concentration of the sodium salt is 0.5 to 8 mol / L, and may be 1 to 4 mol / L.

[0052] The contents in the conditions (1) to (4) are all relative to the total weight of the sodium ion battery electrolyte, and the total weight of each component in the sodium ion battery electrolyte is 100 wt %.

[0053] When the sodium ion battery electrolyte satisfies one or more of the above conditions, it is advantageous to further expand the potential window of the corresponding secondary battery, improve the Coulombic efficiency, and improve the cycle characteristics and safety performance.

[0054] As an example, the total weight of the sodium ion battery electrolyte is a F x R y -zThe content of the sodium salt may be 5 wt%, 10 wt%, 11.5 wt%, 12 wt%, 12.5 wt%, 14.5 wt%, 20 wt%, 23 wt%, 40 wt%, or a range consisting of any two of these.

[0055] As an example, the content of the fluoroalkyl ether may be 1 wt%, 2 wt%, 5 wt%, 8 wt%, 20 wt%, 48 wt%, 82 wt%, or a range consisting of any two of these, relative to the total weight of the sodium ion battery electrolyte.

[0056] As an example, the total weight of the sodium ion battery electrolyte is a F x R y -z The total content of the sodium salt and the fluoroalkyl ether may be 10 wt%, 12 wt%, 12.7 wt%, 13.6 wt%, 15 wt%, 16.5 wt%, 17.5 wt%, 20 wt%, 25 wt%, 28 wt%, 32 wt%, 48 wt%, 60 wt%, 95 wt%, or a range consisting of any two of these.

[0057] For example, the content of the other ethers may be 5 wt%, 40 wt%, 68 wt%, 72 wt%, 75 wt%, 82.5 wt%, 83.5 wt%, 85 wt%, 86.4 wt%, 87.3 wt%, 88 wt%, 90 wt%, or a range consisting of any two of them, based on the total weight of the sodium ion battery electrolyte.

[0058] As an example, the formula NaBO a F x R y -z The concentration of the sodium salt may be 0.5M (ie, mol / L), 1M, 1.5M, 4M, 8M, or a range consisting of any two of these.

[0059] In some embodiments, optionally, the formula NaBO a F x R y-z The mass ratio of the sodium salt of the formula NaBO to the fluoroalkyl ether is 1:0.08-6, may be 1:0.08 to 4, or may be 1:0.1 to 0.8. a F x R y -z The mass ratio of the sodium salt of the above to the fluoroalkyl ether may be 1:0.08, 1:0.1, 1:0.125, 1:0.17, 1:0.2, 1:0.25, 1:0.4, 1:0.44, 1:0.5, 1:0.66, 1:0.8, 1:1, 1:3.8, 1:4, 1:5.6, 1:6, or a range consisting of any two of these.

[0060] In some embodiments, the mass ratio of the fluoroalkyl ether to the ethers other than the fluoroalkyl ether is optionally 1:0.06 to 90, 1:2 to 90, or 1:9 to 44. As an example, the mass ratio of the fluoroalkyl ether to the ethers other than the fluoroalkyl ether may be 1:0.06, 1:0.84, 1:2, 1:3.4, 1:9, 1:10, 1:11, 1:14.4, 1:15, 1:16.5, 1:16.7, 1:18, 1:43.2, 1:44, 1:87.3, 1:90, or a range consisting of any two of these.

[0061] When the ratio of each component in the sodium ion battery electrolyte satisfies one or more of the above conditions, it is advantageous to further expand the potential window of the corresponding secondary battery, improve the Coulombic efficiency, and improve the cycle characteristics and safety performance.

[0062] In some embodiments, optionally, the formula NaBO a F x R y -zis selected from one or more of sodium difluoroborate, sodium tetrafluoroborate, sodium dioxalatoborate, sodium difluorooxalatoborate, sodium tetraphenylborate, sodium tetracyanoborate, sodium tetra(trifluoromethyl)borate, sodium bis(trifluoromethyl)difluoroborate, sodium pentafluoroethyltrifluoroborate, sodium dicyanooxalatoborate, sodium methoxytricyanoborate, sodium ethoxytricyanoborate, sodium tetramethoxyborate, sodium tetraethoxyborate, sodium cyanotri(2,2,2-trifluoroethyl)borate; It may be one or more of sodium dioxalatoborate, sodium difluorooxalatoborate, sodium tetra(trifluoromethyl)borate, sodium bis(trifluoromethyl)difluoroborate, sodium dicyanooxalatoborate.

[0063] The appropriate formula NaBO a F x R y -z By selecting the sodium salt of the above, it is advantageous to further widen the potential window of the corresponding secondary battery, improve the Coulombic efficiency, and improve the cycle characteristics and safety performance.

[0064] In some embodiments, optionally, the fluoroalkyl ether is selected from one or more of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, bis(2,2,2-trifluoroethyl) ether, 1,1,2,2,-tetrafluoroethyl-2,2,2-trifluoroethyl ether, methoxynonafluorobutane, and ethoxynonafluorobutane.

[0065] In some embodiments, optionally, the other ethers are selected from one or more of ethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, crown ether, and may be one or more of ethylene glycol diethyl ether, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether.

[0066] By selecting appropriate fluoroalkyl ethers and other ethers, it is advantageous to further widen the potential window of the corresponding secondary battery, improve the Coulombic efficiency, and improve the cycle characteristics and safety performance.

[0067] Optionally, in some embodiments, the fluoroalkyl ether and the other ethers are liquids at room temperature.

[0068] In some embodiments, optionally, the sodium-ion battery electrolyte does not contain a carbonate ester, or when a carbonate ester is present, the ratio of the weight percent content of the carbonate ester to the weight percent content of all ether solvents is 1:9 to 3:2, and may be 1:6 to 1:1.

[0069] When the electrolyte does not contain a carbonate ester or the mass ratio of the carbonate ester to the ether solvent is within the above range, it is advantageous to further expand the potential window of the corresponding secondary battery, improve the Coulombic efficiency, and improve the cycle characteristics and safety performance.

[0070] The sodium ion battery electrolyte of the present application may be prepared by a method commonly used in the art. For example, the electrolyte may be prepared by the following method: In an inert gas atmosphere, a solution of the formula NaBO a F x R y -zThe sodium salt of the formula NaBO and the fluoroalkyl ether are added to the ethers other than the fluoroalkyl ether, and the mixture is homogeneously mixed to obtain a solution of the formula NaBO a F x R y -z The concentration of the sodium salt is set to 0.5 to 8 mol / L, or may be 1 to 4 mol / L, to obtain the electrolyte solution described in the present application.

[0071] [Secondary battery] According to a second aspect of the present application, there is provided a sodium ion secondary battery comprising the electrolyte according to the first aspect of the present application. In general, in addition to the electrolyte, the secondary battery further comprises a positive electrode sheet, a negative electrode sheet and a separator.

[0072] The secondary battery can be manufactured by a method commonly used in the art, for example, a positive electrode sheet, a negative electrode sheet and a separator can be manufactured into an electrode assembly through a winding process or a lamination process, and then an electrolyte can be injected into the electrode assembly and sealed to obtain a secondary battery.

[0073] Each of the above-mentioned components of the secondary battery will be described below.

[0074] [Positive electrode sheet] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector and including a positive electrode active material.

[0075] As an example, the positive electrode current collector has two opposing surfaces in the thickness direction of itself, and the positive electrode film layer is provided on either one or both of the two opposing surfaces of the positive electrode current collector.

[0076] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. The metal foil can be, for example, an aluminum foil. The composite current collector can include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0077] In this application, the positive electrode material is Na + Examples of the positive electrode active material include transition metal oxides, polyanion compounds, Prussian blue analogues, and the like.

[0078] In some embodiments, the positive electrode active material is a transition metal oxide. x MO2 or Na y Examples of the oxides include sodium-containing composite oxides represented by M2O4 (M is a transition metal, 0≦x≦1, 0≦y≦2), spinel-like oxides, metal sulfides with layered structures, and olivine structures. For example, sodium cobalt oxides such as NaCoO2, sodium manganese oxides such as NaMn2O4, sodium nickel oxides such as NaNiO2, and Na 4 / 3 Ti 5 / 3 Examples of such oxides include sodium titanium oxides such as O4, sodium manganese nickel composite oxides, sodium manganese nickel cobalt composite oxides, and materials having an olivine crystal structure such as NaMPO4 (M=Fe, Mn, Ni).

[0079] In some embodiments, the positive electrode active material is optionally a sodium-containing composite oxide having a layered structure or a spinel-like structure, such as NaCoO2, NaMn2O4, NaNiO2, NaNi 1 / 2 Mn 1 / 2Sodium manganese nickel composite oxides, such as NaNi O2 l / 3 Mn 1 / 3 Co 1 / 3 O2, NaNi 0.6 Mn 0.2 Co 0.2 Sodium manganese nickel cobalt composite oxide, represented by NaNi 1-x-y-z Co x Al y Mg z O2 (wherein 0≦x≦1, 0≦y≦0.1, 0≦z≦0.1, 0≦1-xyz≦1). The scope of the present application also includes sodium-containing composite oxides in which some of the constituent elements in the sodium-containing composite oxides are replaced with additive elements such as Ge, Ti, Zr, Mg, Al, Mo, and Sn.

[0080] In some embodiments, the positive electrode active material is optionally a polyanionic compound. In one example, the polyanionic compound is a compound that contains sodium ions, transition metal ions, and a tetrahedral (YO4) n- The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y may be at least one of P, S, and Si, and n is (YO4) n- Polyanionic compounds further include sodium ions, transition metal ions, and tetrahedral (YO4) n- The anion unit may be a type of compound having a halogen anion. The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y may be at least one of P, S, and Si, and n is (YO4) n- The halogen may be at least one of F, Cl, or Br. The polyanionic compound may further include a sodium ion, a tetrahedral (YO4) n- Anionic unit, polyhedral unit (ZO y ) m+and optionally a class of compounds having a halogen anion. Y may be at least one of P, S, and Si, and n is (YO4) n- Z represents a transition metal and may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and m represents a valence of (ZO y ) m+ and the halogen may be at least one of F, Cl, and Br. The polyanionic compounds include, for example, NaFePO4, Na3V2(PO4)3, NaM'PO4F (wherein M' is one or more of V, Fe, Mn, and Ni), and Na3(VO y )2(PO4)2F 3-2y (0≦y≦1).

[0081] In some embodiments, the positive electrode active material is optionally a Prussian blue analog. As an example, Prussian blue compounds react with sodium ions, transition metal ions, and cyanide ions (CN - The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Prussian blue compounds may be, 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; <a≦2、0<b<1、0<c<1である。

[0082] In some embodiments, the positive electrode film layer may further include a binder, for example, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0083] In some embodiments, the binder optionally comprises 0.1 to 3.5% of the total weight of the positive electrode film layer, and may alternatively comprise 0.5 to 2.5%.

[0084] In some embodiments, the positive electrode film layer may further include a conductive agent, for example, at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0085] In some embodiments, the conductive agent optionally accounts for 0.05 to 5% of the total weight of the positive electrode film layer, and may be 0.5 to 3%.

[0086] In some embodiments, the positive electrode sheet can be manufactured by the following method: Components for manufacturing the positive electrode sheet, such as a positive electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode paste, which is then applied to a positive electrode current collector, and the positive electrode sheet can be obtained through steps such as drying and cold pressing.

[0087] [Negative electrode sheet] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector and including a negative electrode active material.

[0088] As an example, the negative electrode current collector has two opposing surfaces in the thickness direction of the negative electrode current collector, and the negative electrode film layer is provided on either one or both of the two opposing surfaces of the negative electrode current collector.

[0089] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. The metal foil can be, for example, a copper foil. The composite current collector can include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0090] In some embodiments, the anode may include sodium metal anodes (including no anodes), carbon material anodes, and other non-carbon material anodes.

[0091] In this application, the term "no negative electrode" means that the secondary battery does not need to use a negative electrode material and can achieve a higher energy density (based on the same energy). Without being bound by any theory, the working principle of the no negative electrode battery is as follows: The sodium ions in the sodium-rich positive electrode material pass through the separator during charging, combine with the electrons transmitted through the external circuit to form sodium metal, and then deposit on the current collector. The discharge process is the opposite, and the metallic sodium on the current collector dissolves and returns to the electrolyte, passes through the separator, and is then inserted back into the positive electrode material.

[0092] In some embodiments, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, etc. The silicon-based material may be selected from at least one of silicon, silicon oxide, silicon carbon composite, silicon nitrogen composite, and silicon alloy. The tin-based material may be selected from at least one of tin, tin oxide, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material of a battery may be used. These negative electrode active materials may be used alone or in combination of two or more types.

[0093] In some embodiments, the negative electrode active material comprises hard carbon.

[0094] In some embodiments, the negative electrode film layer may further include an optional binder, which may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0095] In some embodiments, the binder optionally comprises 0.1 to 3.5% of the total weight of the negative electrode film layer, optionally 0.5 to 2.5%.

[0096] In some embodiments, the negative electrode film layer may further include an optional conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0097] In some embodiments, the conductive agent optionally comprises 0.05 to 5% of the total weight of the negative electrode film layer, optionally 0.5 to 3%.

[0098] In some embodiments, the negative electrode sheet can be manufactured by the following method: Components for manufacturing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode paste, which is then applied to a negative electrode current collector, and the negative electrode sheet can be obtained through steps such as drying and cold pressing.

[0099] [Separator] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous structure separator having good chemical stability and mechanical stability can be selected.

[0100] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven 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 each layer can be the same or different, and is not particularly limited.

[0101] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be fabricated into an electrode assembly via a winding or lamination process.

[0102] In some embodiments, the secondary battery may include a housing material, which is used to encapsulate the electrode assembly and the electrolyte.

[0103] In some embodiments, the exterior material of the secondary battery may be a hard case such as a hard plastic case, an aluminum case, a steel case, etc. The exterior material of the secondary battery may be a soft pack such as a pouch-type soft pack. The material of the soft pack may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0104] The present application does not particularly limit the shape of the secondary battery, and the secondary battery may be cylindrical, rectangular, or any other shape. For example, FIG. 1 shows a secondary battery 5 having a rectangular structure as an example.

[0105] In some embodiments, referring to FIG. 2, the exterior material may include a housing 51 and a cover plate 53. The housing 51 includes a bottom plate and a side plate connected to the bottom plate, and a receiving cavity surrounded by the bottom plate and the side plate is formed. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can cover the opening to seal the receiving cavity. The electrode assembly 52 may be formed from a positive electrode sheet, a negative electrode sheet and a separator through a winding process or a stacking process. The electrode assembly 52 is sealed in the receiving cavity. The electrolyte is impregnated in 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 by those skilled in the art according to specific practical requirements.

[0106] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries included in the battery module can be one or more, with the specific number being selectable by those skilled in the art according to the application and capacity of the battery module.

[0107] Fig. 3 shows an example of a battery module 4. Referring to Fig. 3, in the battery module 4, a plurality of secondary batteries 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they may be arranged in any other manner. The plurality of secondary batteries 5 can be fixed by fasteners.

[0108] Optionally, the battery module 4 may further include an outer case having an accommodation space in which a plurality of secondary batteries 5 are accommodated.

[0109] In some embodiments, the battery modules can be further assembled into a battery pack, and the number of battery modules included 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.

[0110] 4 and 5 show an example of a battery pack 1. Referring to Fig. 4 and Fig. 5, the battery pack 1 may include a battery case and a plurality of battery modules 4 installed in the battery case. The battery case includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be placed over the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery case in any manner.

[0111] The present application further provides a power consuming device including at least one of the secondary battery, battery module, or battery pack according to the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consuming device, or may be used as an energy storage element for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships, satellites, energy storage systems, etc.

[0112] The power consumption device can be selected as a secondary battery, a battery module or a battery pack according to its usage requirements.

[0113] 6 shows an example of a power consumption device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements for the secondary battery of the power consumption device, a battery pack or a battery module can be used.

[0114] Other examples of the device may be a mobile phone, a tablet computer, a notebook computer, etc. Such devices are generally required to be lightweight and thin, and can use a secondary battery as a power source. EXAMPLES

[0115] The following is a description of the examples of the present application. The examples described below are illustrative and are only intended to explain the present application, and should not be understood as limiting the present application. If no specific techniques or conditions are shown in the examples, they are carried out according to the techniques or conditions described in the literature in this field, or according to the product instructions. If no manufacturer is listed for the reagents or equipment used, they are all commercially available general products.

[0116] Example 1 Electrolyte production In a glove box with an argon atmosphere (HO<0.1 ppm, O<0.1 ppm), sodium difluorooxalatoborate (NaDFOB) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether were dissolved in ethylene glycol dimethyl ether, an organic solvent, and the solution was stirred uniformly to obtain a solution in which the content of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether was 5 wt% (based on the total weight of the electrolyte) and the concentration of sodium difluorooxalatoborate was 1.5 mol / L, i.e., the electrolyte of Example 1, and the content of ethylene glycol dimethyl ether was 83.5 wt% based on the total weight of the electrolyte.

[0117] Manufacture of sodium ion secondary batteries [Production of positive electrode sheets] A paste is produced by thoroughly dissolving 10 wt% polyvinylidene fluoride (based on the total weight of the entire paste formulation excluding N-methylpyrrolidone) binder in N-methylpyrrolidone, adding 10 wt% carbon black conductive agent and 80 wt% positive electrode active material Na4Fe3(PO4)2(P2O7) and dispersing them uniformly. The paste is then evenly applied to the surface of an aluminum foil, and transferred to a vacuum dryer for complete drying. The resulting polar sheet is roll pressed and punched out to obtain a positive electrode sheet. The surface density of the positive electrode paste applied to the resulting positive electrode sheet is 0.3 g / 1540.25 mm 2 It is.

[0118] [Manufacturing of negative electrode sheets] The carbon material coating layer is manufactured as follows. First, 5 g of hard carbon material is placed in 50 mL of a mixed solution of concentrated sulfuric acid (mass fraction 98.3%) and concentrated nitric acid (mass fraction 68%) in a volume ratio of 3:1 and stirred for 4 h. Next, the carbon material is carefully removed and washed with deionized water, filtered, and then placed in an oven and dried at 80°C. 2 g of the obtained carbon material and 3 g of styrene butadiene rubber (SBR) are added to N-methylpyrrolidone and stirred to form a uniform paste. Next, the paste is applied on a copper foil and dried to obtain the carbon material coating layer to be used, with a coating amount of 0.010 g / 1540.25 mm. 2 It is.

[0119] The sodium metal alloy active material is prepared as follows: In an Ar atmosphere, metallic sodium is placed in a stainless steel crucible and heated to 200°C to completely dissolve. Then, the sodium bismuth alloy component powder is added to the liquid sodium metal and thoroughly stirred for 2 hours to ensure that the metal powder and metallic sodium liquid are uniformly mixed. After cooling in an Ar protective atmosphere, the sodium metal alloy active material is obtained. The bismuth content in the sodium metal alloy active material is 5% by weight.

[0120] The sodium metal alloy active material is compounded on the surface of the carbon material coating layer by cold pressing to obtain a sodium metal negative electrode sheet. In the obtained negative electrode sheet, the surface density of the sodium metal alloy active material on the carbon material coating layer is 0.025 g / 1540.25 mm 2 It is.

[0121] [Separator] Polypropylene film (purchased from Shanghai Enji Co., Ltd.) is used as the separator.

[0122] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, the separator is placed between the positive electrode sheet and the negative electrode sheet to play the role of isolation, and the electrolyte is added to assemble a three-layer laminate battery. The size of the obtained secondary battery is 60 mm x 55 mm x 5 mm.

[0123] Examples 2 to 20 Except for the different electrolyte formulations, the other steps of Examples 2 to 20 are the same as those of Example 1, and the details are as shown in Table 1.

[0124] Comparative Examples 1 to 4 Other than the different electrolyte formulations, the other steps of Comparative Examples 1 to 4 are the same as those of Example 1.

[0125] Battery performance test method 1. Potential window The electrolyte must be able to exist stably within the range of the operating voltage of the battery, and the voltage range within which the electrolyte is electrically and chemically stable is generally called the potential window.

[0126] The potential window test mainly involves measuring a cyclic voltammogram. The potential of the investigation electrode is controlled to sweep the potential in the negative direction at a rate of V (1 mV / s) starting from Ei (start potential), and then after a time t (t is automatically generated by the test system according to the voltage range), the sweep direction is changed and the potential returns to the start potential at the same rate. Then the potential is reversed again and swept repeatedly 50 times, and the region where no redox peak appears is detected and the obtained potential window is obtained.

[0127] 2. Coulombic efficiency Taking Example 1 as an example, the prepared sodium ion secondary battery is charged to 4.15V at 25°C with a constant current of 1 / 3C, and then charged to a constant voltage of 4.15V until the current drops to 0.05C to obtain the initial charge capacity (Cc), and then discharged to 2.5V with a constant current of 1 / 3C to obtain the initial discharge capacity (Cd), and the Coulombic efficiency of the sodium ion battery is calculated according to the following formula:

[0128] Coulombic efficiency of a sodium-ion battery = initial discharge capacity (Cd) / initial charge capacity (Cc) x 100%.

[0129] The test procedures for the comparative example and other examples are the same as those described above.

[0130] 3. Capacity retention rate Taking Example 1 as an example, the sodium ion battery is charged at 25°C with a constant current of 1C to 4.15V, then charged at a constant voltage of 4.15V until the current drops to 0.05C, and then discharged at a constant current of 1C to 2.5V to obtain the initial discharge capacity (Cd1). This charge and discharge is repeated up to n cycles, and the discharge capacity of the sodium ion battery after n cycles is obtained and recorded as Cdn, and the capacity retention rate of the sodium ion battery is calculated according to the following formula:

[0131] Capacity retention rate = discharge capacity after n cycles (Cdn) / discharge capacity at 1st cycle (Cd1) × 100%.

[0132] The test procedures for the comparative example and other examples are the same as those described above. The data in Table 1 were measured after 200 cycles according to the above method.

[0133] 4. Sodium dendrites The sodium-ion battery after 200 cycles is disassembled in an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm) and the morphology of the surface of the negative electrode sheet is visually observed to determine whether sodium dendrites have been formed. If there are no white dots on the negative electrode sheet, it is determined that there are no sodium dendrites, if there are sparse white dots on the negative electrode sheet, the sodium dendrite condition is determined to be minor, and if there are many densely packed white dots on the negative electrode sheet, the sodium dendrite condition is determined to be serious.

[0134] [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4] [Table 1-5]

[0135] As can be seen from Table 1, the formula NaBO a F x R y -z A sodium ion secondary battery corresponding to an electrolyte solution containing sodium salt of the formula NaBO, fluoroalkyl ether, and ethers other than fluoroalkyl ether has a wider potential window, coulombic efficiency, cycle characteristics, and safety performance. a F x R y -z By further adjusting the concentration of sodium salt, the content and type of fluoroalkyl ether, the performance of the secondary battery can be further improved. At the same time, as can be seen from Table 1, compared with carbonate-based additives, fluoroalkyl ether is more advantageous in improving battery performance.

[0136] The present application is not limited to the above-mentioned embodiment. The above-mentioned embodiment is merely an example, and any embodiment that has substantially the same configuration as the technical idea and exhibits the same effect within the scope of the technical solution of the present application is included in the technical scope of the present application. In addition, various modifications that a person skilled in the art can conceive of are added to the embodiment, and other forms constructed by combining some of the components in the embodiment are also included in the scope of the present application, as long as they do not deviate from the gist of the present application. [Explanation of symbols]

[0137] 1 Battery pack 2 Upper case 3 Lower case 4 Battery Module 5 Secondary battery 51 Housing 52 Electrode Assembly 53 Cap Assembly

Claims

1. Formula NaBO ａ F ｘ R ｙ －ｚ and the sodium salt of A fluoroalkyl ether; and other ethers other than fluoroalkyl ethers, The formula NaBO ａ F ｘ R ｙ －ｚ In the sodium salt of the formula (I), 2a+x+y×z=2 or 4, 0≦a≦3, 0≦x≦4, 0≦y, 0≦z, and 0≦y×z≦4; R is an oxalic acid group ( 【Chemistry 1】 ), a phenyl group, a cyano group, C １ -C ６ -fluoroalkyl groups such as trifluoromethyl, pentafluoroethyl, 2,2,2-trifluoroethyl, C １ -C ６ - selected from one or more of the following alkoxy groups, e.g. methoxy, ethoxy groups; The other ethers are selectively selected from one or more of an aliphatic ether having 4 to 20 carbon atoms, an alicyclic ether having 3 to 8 carbon atoms, an aromatic ether having 7 to 20 carbon atoms, and a crown ether.

2. The formula NaBO ａ F ｘ R ｙ －ｚ The content of the sodium salt of the above is 5 to 40 wt %, and may be 10 to 20 wt %. The content of the fluoroalkyl ether is 1 to 82 wt %, may be 1 to 48 wt %, may be 1 to 20 wt %, or may be 2 to 8 wt %; and (2) The formula NaBO ａ F ｘ R ｙ －ｚ and the fluoroalkyl ether, the total content of the sodium salt of the above is 10 to 95 wt %, may be 10 to 60 wt %, or may be 12 to 28 wt %; and The content of the other ethers is 5 to 90 wt %, may be 40 to 90 wt %, or may be 72 to 88 wt %. Condition (4) The formula NaBO ａ F ｘ R ｙ －ｚ The concentration of the sodium salt of is 0.5 to 8 mol / L, and may be 1 to 4 mol / L. The sodium ion battery electrolyte according to claim 1, wherein the contents in the conditions (1) to (4) are all based on the total weight of the sodium ion battery electrolyte, and the total weight of each component in the sodium ion battery electrolyte is 100 wt %.

3. The formula NaBO ａ F ｘ R ｙ －ｚ the mass ratio of the sodium salt of the formula (I) to the fluoroalkyl ether is 1:0.08-6, may be 1:0.08-4, or may be 1:0.1-0.8; Alternatively, the mass ratio of the fluoroalkyl ether to the ether other than the fluoroalkyl ether is 1:0.06-90, may be 1:2-90, or may be 1:9-44. The sodium ion battery electrolyte according to claim 1.

4. The formula NaBO ａ F ｘ R ｙ －ｚ is selected from one or more of sodium difluoroborate, sodium tetrafluoroborate, sodium dioxalatoborate, sodium difluorooxalatoborate, sodium tetraphenylborate, sodium tetracyanoborate, sodium tetra(trifluoromethyl)borate, sodium bis(trifluoromethyl)difluoroborate, sodium pentafluoroethyltrifluoroborate, sodium dicyanooxalatoborate, sodium methoxytricyanoborate, sodium ethoxytricyanoborate, sodium tetramethoxyborate, sodium tetraethoxyborate, sodium cyanotri(2,2,2-trifluoroethyl)borate; 2. The sodium-ion battery electrolyte of claim 1, which may be one or more of sodium dioxalatoborate, sodium difluorooxalatoborate, sodium tetra(trifluoromethyl)borate, sodium bis(trifluoromethyl)difluoroborate, sodium dicyanooxalatoborate.

5. 2. The sodium ion battery electrolyte of claim 1, wherein the fluoroalkyl ether is selected from one or more of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, bis(2,2,2-trifluoroethyl)ether, 1,1,2,2,-tetrafluoroethyl-2,2,2-trifluoroethyl ether, methoxynonafluorobutane, ethoxynonafluorobutane.

6. the other ethers are selected from one or more of ethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, crown ether; 10. The sodium-ion battery electrolyte of claim 1, which may be one or more of ethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether.

7. 2. The sodium ion battery electrolyte of claim 1, which is free of carbonate ester, or when carbonate ester is present, the ratio of the weight percent content of carbonate ester to the weight percent content of all ether solvents is 1:9 to 3:2, and may be 1:6 to 1:

1.

8. A sodium ion secondary battery comprising the electrolyte solution according to any one of claims 1 to 7.

9. A battery module comprising the sodium ion secondary battery according to claim 8.

10. A battery pack comprising the sodium ion secondary battery according to claim 8.

11. A power consuming device comprising the sodium ion secondary battery according to claim 8.

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