Electrolyte, sodium ion secondary battery, battery module, battery pack, and power consumption device

Abstract

The present application relates to an electrolyte for a secondary battery, comprising an electrolyte salt, an organic solvent, and an additive, wherein the additive comprises an amine-based compound and a sulfur-containing compound having a boiling point of 70° C. or less, the mass percentage of the sulfur-containing compound in the electrolyte is 0.06% to 8%, and the mass ratio of the sulfur-containing compound to the amine-based compound is 1:(0.08-13). The electrolyte of the present application can obviously improve the cycle performance of the secondary battery, reduce the volatilization of sulfur-containing gas, and further improve the storage performance of the secondary battery.

Description

[Technical field]

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

[0002] Due to the increasing demand for energy, the rising cost of refining fossil fuels, and the serious environmental pollution caused by the use of fossil energy, people are seeking environmentally friendly energy production and storage methods. Battery-based electrochemical energy storage technology has excellent characteristics such as high efficiency, flexible deployment, the ability to meet the demands of different power consumption grids, long cycle life, and low maintenance costs, and provides a viable solution to the energy storage problem, especially for grid-connected power generation using intermittent natural resources (e.g., wind energy, solar energy, etc.). Here, sodium-ion batteries are a promising energy storage battery system because they have the advantages of abundant sodium resources and low cost. Sodium-ion batteries are similar in structure to lithium-ion batteries, and include positive and negative electrodes that can absorb and release sodium ions, and an electrolyte that has a sodium ion transmission effect. Similar to lithium-ion batteries, during the first charging process, the products of reductive decomposition of the electrolyte form a passivation film at the negative electrode interface to prevent further reductive decomposition of the electrolyte, so the performance of this passivation film directly affects the performance of the battery.

[0003] The solvents currently commonly used in sodium ion batteries are linear carbonates and cyclic carbonates, and the components that form the passivation film at the negative electrode interface are mainly sodium alkyl carbonate (ROCO2Na) and sodium carbonate. However, sodium alkyl carbonate has a higher solubility in carbonate solvents than lithium alkyl carbonate. This makes the negative electrode interface passivation film of sodium ion batteries very unstable, and the electrolyte continuously undergoes side reactions with the negative electrode. As a result, the service life of sodium ion batteries is difficult to meet the actual application demands.

[0004] The technology of electrolyte additives for lithium-ion batteries has already matured, and some of the technology has already been used in sodium-ion battery electrolytes. S. Komaba et al. compared the improvement effects of well-known electrolyte additives in lithium-ion batteries, fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinylene carbonate (VC), and ethylene sulfite (ES), on sodium-ion batteries, and found that only fluoroethylene carbonate (FEC) has a significant effect on improving the life of sodium-ion batteries (ACS Applied Mater.Inter.,3(2011)4165-4168). CN109786827A reports the combined use of fluoroethylene carbonate, sultone-based compounds, and sulfate-based compounds. By utilizing the synergistic effect of these electrolyte additives, the positive and negative electrode interfaces of sodium-ion batteries have good stability, thereby achieving a good service life. However, the poly-organics formed by the reduction of these organic additives at the negative electrode significantly deteriorate the internal resistance of the battery core.

[0005] CN112310473A reports that non-metallic oxides are used in lithium ion battery electrolytes to increase the inorganic components in the negative electrode solid electrolyte interphase (SEI), and the non-metallic oxides include gaseous non-metallic oxides such as sulfur dioxide, sulfur trioxide, carbon dioxide, nitric oxide, nitrogen dioxide, and dinitrogen trioxide. Although these gaseous non-metallic oxides have a certain solubility in the electrolyte, they still have very strong volatility, and some of them in particular are not environmentally friendly and bring difficulties to the production and manufacturing process.

[0006] CN106415909A reported that adding a large amount of saturated sulfur dioxide to ionic liquid can improve the conductivity of inorganic electrolyte, thereby improving the battery core performance of sodium-sulfur dioxide secondary batteries, and low-volatility ionic liquid can suppress the gas generation problem in the battery core caused by the large amount of SO2 used. However, ionic liquid is expensive and incompatible with carbon material anodes, and cannot be directly used in conventional sodium ion batteries with amorphous carbon material anodes.

[0007] The electrolyte additives currently used in sodium ion secondary batteries have many problems in the application process, so there is an urgent need to develop new electrolytes for secondary batteries to improve the electrical performance of sodium ion secondary batteries and extend the service life of sodium ion secondary batteries. Summary of the Invention

[0008] The present application has been made in view of the above-mentioned problems, and an object of the application is to provide an electrolyte for a secondary battery, a sodium ion secondary battery, a battery module, a battery pack, and a power consuming device, and to improve the stability of the negative electrode interface passivation film of the sodium ion secondary battery in the electrolyte and to extend the service life of the sodium ion secondary battery.

[0009] In order to achieve the above object, a first aspect of the present application provides an electrolyte solution for a secondary battery, comprising an electrolyte salt, an organic solvent, and an additive. Here, the additive comprises an amine-based compound and a sulfur-containing compound having a boiling point of 70°C or less. The mass percentage of the sulfur-containing compound in the electrolyte solution is 0.06% to 8%, preferably 0.08% to 6%. The mass ratio of the sulfur-containing compound to the amine-based compound is 1:(0.08-13), preferably 1:(0.1-11), and more preferably 1:(0.5-2.5).

[0010] In another embodiment, the mass percentage of the amine compound in the electrolyte solution is 0.06% to 8%, preferably 0.08% to 6%.

[0011] In another embodiment, the total mass percentage of the amine-based compound and the sulfur-containing compound in the electrolyte is 0.5% to 10%, preferably 1% to 7%.

[0012] In other embodiments, the amine-based compound is selected from one or more of the following compounds of formula I, II, and III: TIFF2025501361000001.tif38148 Here, R1 to R3, R8, R9, R 15 and R 16 may each independently be substituted with the following substituents: A hydrogen atom, a halogen atom, a nitro group, and C1-C 20 Alkyl groups, C2-C 20 Alkenyl groups, C6-C 26 Aryl groups, C1-C 20 Alkylene carboxyl group, carbonyl C1-C 20 Alkyl groups, and C6-C 26 An aryloxy group, preferably a C1-C6 alkyl group, and optionally one or more groups selected from halogen atoms, hydroxyl groups, amino groups, nitro groups, sulfonic acid groups, and sulfonyl groups. And R1 and R2 or R3, R8 and R9, R 15 and R 16 are linked by chemical bonds from C1 to C 20 Alkylene group, C2-C 20 Alkenylene group, C6-C 26 Arylene group, carbonyl C1-C 20 Alkylene groups, and C6-C 26 It is possible to form an aryleneoxy group, preferably a C1-C6 alkylene group, wherein the substituents may be further optionally substituted with one or more groups selected from a C1-C6 alkyl group, a halogen atom, a hydroxyl group, an amino group, a nitro group, a carboxyl group, a sulfonic acid group, and a sulfonyl group. R4-R7 and R 10 -R 14 may be independently substituted with the following substituents: C1-C 20 Alkylene group, C2-C 20 Alkenylene group, C6-C 26 Arylene group, carbonyl C1-C 20 Alkylene groups, and C6-C 26 A group selected from an aryleneoxy group, preferably a C1-C6 alkylene group, wherein the substituents are further optionally one or more groups selected from a C1-C6 alkyl group, a halogen atom, a hydroxyl group, an amino group, a nitro group, a carboxyl group, a sulfonic acid group, and a sulfonyl group. The halogen atoms are selected from one or more of F, Cl, and Br.

[0013] In other embodiments, the compound of formula I is selected from one or more of triethylamine, triethanolamine, diethylamine, diethanolamine, monoethylamine, monoethanolamine, 5-(diethylamino)pentylamine, 1-methylpyrrolidine, and triallylamine. The compound of formula II is selected from one or more of triethylenediamine, 2-methyltriethylenediamine, 1,2-dimethylpiperazine, N-ethylpiperazine, 1-allylpiperazine, piperazine, and 1-ethylhomopiperazine. The compound of formula III is selected from one or more of hexamethylenetetramine, 1,3,6,8-tetraazatricyclo[4.3.1.13,8]undecane (CAS number 125251-91-4), 3,7-dimethyl-1,3,5,7-tetraazabicyclo[3.3.1]nonane (CAS number 124469-89-2), 1,3,5,7-tetraazabicyclo[3.3.1]nonane-3-methylamine (CAS number 69470-05-9), and N,N'-dinitrosopentamethylenetetramine.

[0014] In another embodiment, the molecular weight of the sulfur-containing compound is from 50 g / mol to 200 g / mol.

[0015] In other embodiments, the sulfur-containing compound is selected from one or more of sulfur hexafluoride (SF), sulfur tetrafluoride (SF), sulfuryl fluoride (SOF), sulfur dioxide (SO), sulfur trioxide (SO), carbon disulfide (CS), dimethyl sulfide (CHSCH), methyl ethyl sulfide (CHSCHCH), sulfur monofluoride (SF), sulfur difluoride (SF), thionyl fluoride (SOF), and thionyl tetrafluoride (SOF).

[0016] In another embodiment, the electrolyte salt is NaPF6, NaBF4, NaN(SO2F)2 (NaFSI), NaClO4, NaAsF6, NaB(C2O4)2 (NaBOB), NaBF2(C2O4) (NaDFOB), NaN(SO2R F )2, and NaN(SO2F)(SO2R F ), where R F is C b F 2b+1 b is an integer of 1 to 10, preferably an integer of 1 to 3, and more preferably RF is -CF3, -C2F5 or -CF2CF2CF3. In other embodiments, the organic solvent comprises a carbonate-based organic solvent.

[0017] In another embodiment, the carbonate-based organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, and butylene carbonate.

[0018] In another embodiment, the electrolyte further comprises fluoroethylene carbonate, the mass percentage of which in the electrolyte is 0.01% to 10%, preferably 0.1% to 8%.

[0019] A second aspect of the present application provides a sodium ion secondary battery comprising a positive electrode plate, a separator, a negative electrode plate, and the secondary battery electrolyte according to the first aspect of the present application.

[0020] A third aspect of the present application provides a battery module, the battery module including the sodium ion secondary battery according to the second aspect of the present application.

[0021] A fourth aspect of the present application provides a battery pack, the battery pack including the battery module according to the third aspect of the present application.

[0022] A fifth aspect of the present application provides a power consumption device, the power consumption device including at least one selected from 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.

[0023] The electrolyte of the present application can obviously improve the cycle performance of the sodium ion secondary battery, and also reduce the volatilization of the sulfur-containing compounds, so as to further improve the storage performance of the sodium ion secondary battery. [Brief description of the drawings]

[0024] [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 shown in FIG. 4 according to an embodiment of the present application. [Figure 6] 1 is a schematic diagram of a power consuming device in which a secondary battery is used as a power source according to an embodiment of the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, embodiments of the electrolyte for a secondary battery, the sodium ion secondary battery, the battery module, the battery pack, and the power consumption device of the present application will be described in detail and specifically disclosed with appropriate reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and duplicated description of structures that are actually the same may be omitted. This is to avoid the following description becoming unnecessarily long and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to allow those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0026] The "ranges" disclosed in this application are defined in the form of lower and upper limits. 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. Such a defined range may or may not include the end values, and any combination is possible. That is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also envisaged. It is noted that if 1 and 2 are listed as the minimum range values, and 3, 4, and 5 are listed as the maximum range values, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all envisaged. In this application, unless otherwise specified, a numerical range "a-b" represents a shorthand representation of any combination of real numbers a-b, where a and b are both real numbers. For example, the numerical range "0-5" represents a list of all real numbers between "0-5" already listed in this specification, and "0-5" is a shorthand for combinations of these numerical values. Also, 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.

[0027] Unless otherwise stated, all the embodiments and preferred embodiments in this application can be combined with each other to form a new technical solution.

[0028] Unless otherwise stated, all technical features and preferred technical features of this application can be combined with each other to form a new technical solution.

[0029] Unless otherwise stated, the terms "comprise" and "include" referred to in this application may be open ended or closed ended. For example, the terms "comprise" and "include" may further include or include other ingredients not listed, or may include or include only the ingredients listed.

[0030] Unless otherwise stated, in this application, "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied if A is true (or exists) and B is false (or does not exist), if A is false (or does not exist) but B is true (or exists), or if both A and B are true (or exist).

[0031] Unless otherwise stated, all operations in this application are carried out at room temperature (25° C.) and pressure (101 kPa).

[0032] Unexpectedly, the inventors have found that when a sulfur-containing compound with a low boiling point (e.g., ≦70° C.) is added to the electrolyte of a sodium-ion battery, the passivation film on the negative electrode can be more stabilized, thereby significantly extending the cycle life of the sodium-ion battery. Without being bound by any theory, it is currently believed that sulfur-containing compounds are not resistant to oxidation and reduction and have a very good diffusion rate. Therefore, they react preferentially with the negative electrode surface over the carbonate solvent to form an inorganic salt product of sulfur-containing sodium. Therefore, it is believed that the solubility of such inorganic salts in carbonate solvents is lower than that of sodium alkyl carbonate.

[0033] In addition, compared with the sulfur-containing compounds with high boiling points commonly used in the art, the sulfur-containing compounds with low boiling points can effectively improve the internal resistance of the battery and significantly improve the room temperature cycle performance, because the sulfur-containing compounds with low boiling points can not only reduce the viscosity of the electrolyte, but also form a stable negative electrode passivation film with low internal resistance.

[0034] However, such low boiling point sulfur-containing compounds are highly volatile even after being dissolved in electrolyte, and if they leak during battery core production, they will cause environmental pollution. In addition, high atmospheric pressure will also cause the battery core to bulge, which will lead to safety issues. The inventors have also unexpectedly discovered that when the amine-based compound and low boiling point sulfur-containing compound of the present application are used simultaneously in sodium ion battery electrolyte, they not only do not degrade the electrical performance of the sodium ion secondary battery, but also significantly extend the cycle and storage life of the sodium ion battery, and significantly reduce the volatilization of the low boiling point sulfur-containing compound.

[0035] Therefore, a first aspect of the present application provides an electrolyte solution for a secondary battery, comprising an electrolyte salt, an organic solvent, and an additive. Here, the additive contains an amine compound and a sulfur-containing compound having a boiling point of 70° C. or less. The mass percentage of the sulfur-containing compound in the electrolyte is 0.06% to 8%, preferably 0.08% to 6%, and more preferably 0.1% to 2%. The mass ratio of the sulfur-containing compound to the amine compound is 1:(0.08-13), preferably 1:(0.1-11), more preferably 1:(0.3-6), and even more preferably 1:(0.5-2.5).

[0036] If the mass percentage of the sulfur-containing compound is too low, the content is too small, so the positive and negative electrode passivation film formed is not sufficient to prevent further reaction of the electrolyte, and the improvement of the battery performance is not obvious.If the mass percentage is too high, the reaction products generated by oxidative decomposition are deposited on the positive electrode, increasing the film resistance at the interface between the positive electrode active material layer and the electrolyte, thereby deteriorating the battery performance.

[0037] Since the nitrogen atom in the amine-based compound contains a lone pair of electrons, the amine-based substance is a typical Lewis base. The amine-based compound is added to the electrolyte, which acts as a complex with the low-boiling sulfur-containing compound in the electrolyte to significantly reduce the volatility of the low-boiling sulfur-containing compound.

[0038] In some embodiments, the mass percentage of the amine compound in the electrolyte solution is 0.06% to 8%, preferably 0.08% to 6%, and more preferably 1% to 4.5%.

[0039] By setting the content of the amine-based compound within the above range, on the one hand, it is possible to provide a sufficient amount of the amine-based compound and the sulfur-containing compound to complex with each other, thereby further improving the effect of suppressing the volatilization of the sulfur-containing compound, and on the other hand, it is possible to further improve the cycle performance by controlling the content of the amine-based compound that is not resistant to oxidation.

[0040] In some embodiments, the total mass percentage of the amine-based compound and the sulfur-containing compound in the electrolyte is 0.5% to 10%, preferably 1% to 7%.

[0041] In this application, the detection of low boiling point sulfur-containing compounds in the electrolyte is performed by referring to GT / T 17040-2008 "Determination of sulfur content in petroleum and petroleum products by energy dispersive X-ray fluorescence spectroscopy". A reference curve is made according to the relationship between X-ray fluorescence intensity and the content of the reference sample, and the unknown sample is quantified.

[0042] In this application, "a sulfur-containing compound having a boiling point of 70° C. or less" means a sulfur-containing compound having a boiling point of 70° C. or less measured under normal pressure.

[0043] In this application, the boiling point can be measured according to GB / T 616-2006.

[0044] In some embodiments, the sulfur-containing compound is a gas at ambient pressure and temperature.

[0045] In some embodiments, the amine-based compound is selected from one or more of the following compounds of formula I, II, and III: TIFF2025501361000002.tif38148 Here, R1 to R3, R8, R9, R 15 and R 16 may be independently substituted with the following substituents: a hydrogen atom, a halogen atom, a nitro group, and C1-C 20 Alkyl groups, C2-C 20 Alkenyl groups, C6-C 26 Aryl groups, C1-C 20 Alkylene carboxyl group, carbonyl C1-C 20 Alkyl groups, and C6-C 26 An aryloxy group, preferably a C1-C6 alkyl group, and optionally one or more groups selected from halogen atoms, hydroxyl groups, amino groups, nitro groups, sulfonic acid groups, and sulfonyl groups. R1 and R2 or R3, R8 and R9, R 15 and R 16 are linked by chemical bonds from C1 to C 20 Alkylene group, C2-C 20 Alkenylene group, C6-C 26 Arylene group, carbonyl C1-C 20 Alkylene groups, and C6-C 26 It is possible to form an aryleneoxy group, preferably a C1-C6 alkylene group, where the substituents can be further optionally substituted with one or more of a C1-C6 alkyl group, a halogen atom, a hydroxyl group, an amino group, a nitro group, a carboxyl group, a sulfonic acid group, and a sulfonyl group. R4-R7 and R 10 -R 14 are each independently substituted with: C1-C 20 Alkylene group, C2-C 20 Alkenylene group, C6-C 26 Arylene group, carbonyl C1-C 20 Alkylene groups, and C6-C 26A group selected from an aryleneoxy group, preferably a C1-C6 alkylene group, wherein the substituents may be further optionally substituted with one or more groups selected from a C1-C6 alkyl group, a halogen atom, a hydroxyl group, an amino group, a nitro group, a carboxyl group, a sulfonic acid group, and a sulfonyl group. The halogen atoms are selected from one or more of F, Cl, and Br.

[0046] In this application, "C1-C 20 "Alkyl group" means a saturated straight or branched chain hydrocarbon having 1 to 20 carbon atoms, including, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,2-dimethylpropyl, 1,3-dimethylbutyl, 1,4-dimethylbutyl, 2,3-dimethylbutyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethylbutyl, and 2-ethylbutyl groups. More preferably, it means an alkyl group having 1 to 4 carbon atoms, for example, in particular, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group or a tert-butyl group. 20 The alkylene group is the C1-C 20 It is a divalent group of "alkyl group."

[0047] In this application, "C2-C 20The term "alkenyl group" refers to an unsaturated straight or branched chain hydrocarbon group having 2 to 20 carbon atoms and having one double bond at any position. Examples include, but are not limited to, ethylene, aryl, 1-isopropenyl, isoisopropenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1,3-butadienyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1,3-pentadienyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, and 1,4-hexadienyl groups. 20 The term "alkenylene group" refers to the above "C2-C 20 The term "alkenyl group" refers to a divalent group of "alkenyl group."

[0048] In this application, "C6-C 26 The term "aryl group" means a monocyclic, bicyclic or polycyclic aromatic system having 6 to 26 carbon atoms. Examples include, but are not limited to, phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, tert-butylphenyl, naphthyl, anthracenyl and phenanthryl groups. Preferred are phenyl, methylphenyl, ethylphenyl and n-propylphenyl groups. "C6-C 26 The "arylene group" refers to the above "C6-C 26 “aryl group” refers to a divalent group of “aryl group.”

[0049] In this application, "C6-C 26The term "aryloxy group" refers to an aromatic hydrocarbon group having 6 to 26 carbon atoms and at least one oxygen atom. Examples of the aryloxy group include, but are not limited to, methoxyphenyl, ethoxyphenyl, propoxyphenyl, isopropoxyphenyl, butoxyphenyl, isobutoxyphenyl, tert-butoxyphenyl, methoxynaphthyl, ethoxynaphthyl, propoxynaphthyl, isopropoxynaphthyl, butoxynaphthyl, isobutoxynaphthyl, methoxyanthracenyl, ethoxyanthracenyl, propoxyanthracenyl, methoxyphenanthryl, ethoxyphenanthryl, and propoxyphenanthryl. The C6-C 26 The aryleneoxy group is defined as the C6-C 26 The term "aryloxy group" refers to a divalent group of an "aryloxy group."

[0050] In this application, "chemical bond" may refer to various chemical bonds familiar to those of skill in the art, such as a single bond, double bond, or triple bond formed between carbon atoms or a carbon atom and another heteroatom.

[0051] In some embodiments, the compound of formula I is selected from one or more of triethylamine, triethanolamine, diethylamine, diethanolamine, monoethylamine, monoethanolamine, 5-(diethylamino)pentylamine, 1-methylpyrrolidine, and triallylamine. The compound of formula II is selected from one or more of triethylenediamine, 2-methyltriethylenediamine, 1,2-dimethylpiperazine, N-ethylpiperazine, 1-allylpiperazine, piperazine, and 1-ethylhomopiperazine. The compound of formula III is selected from one or more of hexamethylenetetramine, 1,3,6,8-tetraazatricyclo[4.3.1.13,8]undecane (CAS number 125251-91-4), 3,7-dimethyl-1,3,5,7-tetraazabicyclo[3.3.1]nonane (CAS number 124469-89-2), 1,3,5,7-tetraazabicyclo[3.3.1]nonane-3-methylamine (CAS number 69470-05-9), and N,N'-dinitrosopentamethylenetetramine.

[0052] In some embodiments, the molecular weight of the sulfur-containing compound is from 50 g / mol to 200 g / mol, preferably from 52 g / mol to 100 g / mol.

[0053] In some embodiments, the sulfur-containing compound is selected from one or more of sulfur hexafluoride (SF), sulfur tetrafluoride (SF), sulfuryl fluoride (SOF), sulfur dioxide (SO), sulfur trioxide (SO), carbon disulfide (CS), dimethyl sulfide (CHSCH), methyl ethyl sulfide (CHSCHCH), sulfur monofluoride (SF), sulfur difluoride (SF), thionyl fluoride (SOF), and thionyl tetrafluoride (SOF).

[0054] In some embodiments, the electrolyte salt is NaPF6, NaBF4, NaN(SO2F)2 (NaFSI), NaClO4, NaAsF6, NaB(C2O4)2 (NaBOB), NaBF2(C2O4) (NaDFOB), NaN(SO2R F )2, and NaN(SO2F)(SO2R F ), where R F is C b F 2b+1 where b is an integer from 1 to 10, preferably an integer from 1 to 3, and more preferably R F is -CF3, -C2F5 or -CF2CF2CF3. Preferably, the electrolyte salt is selected from one or more of NaPF6, NaN(SO2F)2, NaN(CF3SO2)2, NaB(C2O4)2, and NaBF2(C2O4). More preferably, the electrolyte salt is selected from one or more of NaPF6, NaN(SO2F)2, and NaBF2(C2O4).

[0055] In some embodiments, the amine-based compound is selected from one or more of triethylamine, triethanolamine, diethylamine, diethanolamine, monoethylamine, monoethanolamine, triethylenediamine, and hexamethylenetetramine, preferably one or more of triethylamine, triethanolamine, diethanolamine, triethylenediamine, and hexamethylenetetramine.

[0056] In some embodiments, the molecular weight of the amine-based compound is from 40 g / mol to 200 g / mol, preferably from 44 g / mol to 190 g / mol.

[0057] In the present application, the molecular weights of the sulfur-containing compound and the amine-based compound are measured by a method commonly used in the art, for example, by a gas chromatograph mass spectrometer.

[0058] In some embodiments, the sulfur-containing compound is selected from one or more of sulfur hexafluoride (SF6), sulfur tetrafluoride (SF4), sulfur fluoride (SO2F2), sulfur dioxide (SO2), sulfur trioxide (SO3), carbon disulfide (CS2), dimethyl sulfide (CH2SCH3), methyl ethyl sulfide (CH2SCH2CH3), sulfur monofluoride (S2F2), sulfur difluoride (SF2), thionyl fluoride (SOF2), and thionyl tetrafluoride (SOF4).Preferably, the sulfur hexafluoride (SF6), sulfur tetrafluoride (SF4), sulfur fluoride (SO2F2), sulfur dioxide (SO2), and sulfur trioxide (SO3).

[0059] In any one of the embodiments, the electrolyte salt is NaPF6, NaBF4, NaN(SO2F)2 (abbreviated as NaFSI), NaClO4, NaAsF6, NaB(C2O4)2 (abbreviated as NaBOB), NaBF2(C2O4) (abbreviated as NaDFOB), NaN(SO2R F )2, and NaN(SO2F)(SO2R F ), where R F is C b F 2b+1 and b is an integer of 1 to 10, preferably an integer of 1 to 3. More preferably, R F is -CF3, -C2F5 or -CF2CF2CF3. Preferably, the electrolyte salt is selected from one or more of NaPF6, NaN(SO2F)2, NaN(CF3SO2)2, NaB(C2O4)2, and NaBF2(C2O4). More preferably, the electrolyte salt is selected from one or more of NaPF6, NaN(SO2F)2, and NaBF2(C2O4).

[0060] In some embodiments, the mass percentage of the electrolyte in the electrolytic solution is from 3% to 30%, preferably from 5% to 15%.

[0061] In some embodiments, the organic solvent comprises a carbonate-based organic solvent. Preferably, the organic solvent is a carbonate-based organic solvent.

[0062] In some embodiments, the mass percentage of the carbonate-based organic solvent in the organic solvent is 50% to 100%, preferably 60% to 95%, more preferably 65% ​​to 90%, and even more preferably 70% to 85%.

[0063] In some embodiments, the carbonate-based organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, and butylene carbonate.

[0064] In some embodiments, the mass percentage of the organic solvent in the electrolyte is from 50% to 97%, preferably from 60% to 90%.

[0065] In some embodiments, the organic solvent further comprises one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, 1,3-dioxolane, tetrahydrofuran, ethylene glycol dimethyl ether, and acetonitrile, and the mass percentage thereof in the organic solvent is 0.5% to 50%, preferably 3% to 30%, more preferably 5% to 20%, and even more preferably 8% to 15%.

[0066] In some embodiments, the electrolyte further comprises fluoroethylene carbonate (CAS number 114435-02-8), the mass percentage of which in the electrolyte is 0.01% to 10%, more preferably 0.1% to 8%, and even more preferably 0.5% to 5%.

[0067] By using fluoroethylene carbonate and a sulfur-containing compound in combination, a single layer passivation film with excellent toughness and high strength can be formed on the surface of the positive electrode and the negative electrode. The sulfur-containing compound can suppress the reduction of fluoroethylene carbonate near the passivation film, and further suppress the deterioration of internal resistance caused by fluoroethylene carbonate. When the content of fluoroethylene carbonate is within the above range, the interface passivation film can be properly formed, further reaction of the electrolyte can be prevented, and cycle performance can be further improved.

[0068] In some embodiments, the electrolyte solution further preferably contains additives. For example, the additives may include anode film-forming additives and cathode film-forming additives, and may further include additives that can improve some performance of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high temperature or low temperature performance of the battery, etc.

[0069] A second aspect of the present application provides a sodium ion secondary battery comprising a positive electrode plate, a separator, a negative electrode plate, and the secondary battery electrolyte according to the first aspect of the present application.

[0070] [Positive electrode plate] A positive electrode plate generally includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0071] For example, the positive electrode current collector has two opposing surfaces in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on either one or both of the two opposing surfaces of the positive electrode current collector.

[0072] In some embodiments, the positive electrode current collector may employ a metal foil sheet or a composite current collector. For example, an aluminum foil may be employed as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, polyethylene (PE), etc.).

[0073] In some embodiments, the positive electrode active material may be any positive electrode active material known in the art for use in batteries. For example, the positive electrode active material may include at least one of sodium transition metal oxides, polyanion-type compounds, and Prussian blue-based compounds. However, the present application is not limited to these materials, and may further include other conventionally known materials that can be used as positive electrode active materials in sodium ion batteries.

[0074] In some embodiments, in the sodium transition metal oxide, the transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. x M y O2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu; <x≦1であり、0.5<y≦1.5である。

[0075] In some embodiments, the polyanionic compound comprises sodium ions, transition metal ions, and tetrahedral (YO4) ions. n- The anion unit may be one type of compound. 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- Represents the valence of.

[0076] In some embodiments, the polyanionic compound further comprises a sodium ion, a transition metal ion, a tetrahedral (YO4) ion, n- It may be a single compound having an anion unit and 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. n is (YO4) n- and the halogen may be at least one of F, Cl, and Br.

[0077] In some embodiments, the polyanionic compound further comprises sodium ions, tetrahedral (YO4) n- Anionic unit, polyhedral unit (ZO y ) m+ and an optional halogen anion. Y may be at least one of P, S, and Si. 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. m represents a valence of (ZO y ) m+ and the halogen may be at least one of F, Cl, and Br.

[0078] In some embodiments, 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 At least one of (0≦y≦1).

[0079] In some embodiments, the Prussian blue based compound comprises 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. The Prussian blue compound 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であり、0<b<1であり、0<c<1である。

[0080] In some embodiments, the positive electrode membrane layer further preferably includes an adhesive. For example, the adhesive may include 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.

[0081] In some embodiments, the positive electrode membrane layer further preferably includes a conductive agent. By way of example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0082] In some embodiments, the positive electrode plate can be manufactured in the following manner: The components for manufacturing the positive electrode plate, such as the positive electrode active material, conductive agent, adhesive, and other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, and the positive electrode slurry is coated on a positive electrode current collector, and the positive electrode plate is obtained after processes such as drying and cold pressing.

[0083] [Negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0084] For 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 disposed on either one or both of the two opposing surfaces of the negative electrode current collector.

[0085] In some embodiments, the negative electrode current collector may employ a metal foil sheet or a composite current collector. For example, a copper foil may be employed as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, polyethylene (PE), etc.).

[0086] In some embodiments, the negative electrode active material may be a negative electrode active material used in batteries known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicone-based materials, tin-based materials, and lithium titanate. The silicone-based material may be selected from at least one of silicone alone, silicone oxide, silicone carbon composite, silicone nitrogen composite, and silicone alloy. The tin-based material may be selected from at least one of tin alone, 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 battery negative electrode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.

[0087] In some embodiments, the negative electrode membrane layer further preferably includes an adhesive. By way of example, the adhesive may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0088] In some embodiments, the negative electrode film layer further preferably includes a conductive agent. For example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0089] In some embodiments, the negative electrode membrane layer further preferably contains other auxiliary agents, such as a thickening agent (eg, sodium carboxymethylcellulose (CMC-Na)).

[0090] In some embodiments, the negative electrode plate can be manufactured in the following manner: Components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, and the negative electrode slurry is coated on a negative electrode current collector, and the negative electrode plate is obtained after processes such as drying and cold pressing.

[0091] [Separator] The secondary battery further includes a separator. The present application does not particularly limit the type of the separator, and any known porous structure separator having good chemical stability and mechanical stability may be selected.

[0092] In some embodiments, the material of the separator may be at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single layer film or a multi-layer composite film, and there is no particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, and there is no particular limitation.

[0093] In some embodiments, the positive plates, negative plates, and separators can be fabricated into an electrode assembly by a winding or lamination process.

[0094] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0095] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic. Examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0096] The present application is not particularly limited to 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.

[0097] In some embodiments, referring to FIG. 2, the exterior body may include a case 51 and a cover plate 53. The case 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate surround and form a receiving cavity. The case 51 has an opening communicating with the receiving cavity. The cover plate 53 may be installed on the opening to seal the receiving cavity. The positive electrode plate, the negative electrode plate and the separator may form an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. An electrolyte is infiltrated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art may specifically select according to actual needs.

[0098] A third aspect of the present application provides a battery module, the battery module including the secondary battery according to the second aspect of the present application.

[0099] In some embodiments, the secondary batteries may be assembled into a battery module. The number of secondary batteries included in the battery module may be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0100] Fig. 3 shows an example of a battery module 4. Referring to Fig. 3, in the battery module 4, the multiple secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the multiple secondary batteries 5 may be fixed by fasteners.

[0101] Preferably, the battery module 4 may further include a housing having an accommodation space, and the multiple secondary batteries 5 are accommodated in this accommodation space.

[0102] A fourth aspect of the present application provides a battery pack, the battery pack including the battery module according to the third aspect of the present application.

[0103] In some embodiments, the battery modules may 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 according to the application and capacity of the battery pack.

[0104] 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 box and a plurality of battery modules 4 installed in the battery box. The battery box may include an upper housing 2 and a lower housing 3, and the upper housing 2 is covered by 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 box in any manner.

[0105] A fifth aspect of the present application provides a power consumption device. The power consumption device includes at least one selected from the sodium ion secondary battery described in the second aspect of the present application, the battery module described in the third aspect of the present application, or the battery pack described in the fourth aspect of the present application. The sodium ion secondary battery, the battery module, or the battery pack may be used as a power source for the power consumption device, or may be used as an energy storage unit for the power consumption device. The power consumption device may include, but is not limited to, a mobile device (e.g., a mobile phone, a laptop, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0106] The power consumption device can be selected as a secondary battery, a battery module, or a battery pack according to its usage demand.

[0107] 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. A battery pack or a battery module can be employed to meet the demand for high power output and high energy density of the secondary battery of the power consumption device.

[0108] [Example] The following is a description of the examples of the present application. The following examples are illustrative and are only for interpreting the present application, and should not be understood as limitations on the present application. In the examples, if no specific techniques or conditions are specified, they are performed according to techniques or conditions described in the literature in the field or according to product specifications. The reagents or instruments used are not specified by manufacturer, and are all ordinary products that are commercially available.

[0109] Secondary battery manufacturing (1) Preparation of positive electrode plate: Sodium vanadium phosphate (Na3V2(PO4)3) as an active material, acetylene black as a conductive agent, and polyvinylidene fluoride (PVDF) as an adhesive were thoroughly mixed in a N-methylpyrrolidone solvent system in a weight ratio of 90:5:5. The solid content of the slurry was 45%. After the slurry was mixed uniformly, it was coated on an aluminum foil. The coating weight was 9 mg / cm. 2 Then, it was dried by blowing air at 130℃, and finally, it was cold pressed and slit to obtain a positive electrode plate with a diaphragm width of 81 mm.

[0110] (2) Preparation of negative electrode plate: The active material, hard carbon, conductive agent, acetylene black, adhesive, styrene butadiene rubber (SBR), and thickener, sodium carboxymethyl cellulose (CMC), were thoroughly mixed in a deionized water solvent system in a weight ratio of 90:4:4:2. The solid content of the slurry was 50%. After the slurry was mixed uniformly, it was coated on an aluminum foil. The coating weight was 4.5 mg / cm. 2 Then, it was dried by blowing air at 130°C, and finally, it was cold pressed and slit to obtain a negative electrode plate with a diaphragm width of 85 mm.

[0111] (3) Separator: A PE porous poly film was used as the separator, and the slit width of the separator was 91 mm.

[0112] (4) Electrolyte: The electrolytes prepared in the following Comparative Examples and Examples were used.

[0113] (5) Full cell production: A positive electrode plate, a separator, and a negative electrode plate were stacked in this order. A separator was placed between the positive and negative electrodes to provide insulation, and the stack was wound to obtain a bare cell. The bare cell was placed in an exterior body, and the prepared electrolyte was injected and packaged. The amount of electrolyte injected was 4 g / Ah.

[0114] Comparative Example 1 Preparation of electrolyte: Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of 30:70, and 1 M of NaPF6 sodium salt was dissolved in the mixture. The prepared electrolyte was used for manufacturing the secondary battery described above.

[0115] Comparative Example 2 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference was that the electrolyte was prepared based on Comparative Example 1, and 1 mass % of sulfur dioxide (SO2) was added based on the total weight of the electrolyte.

[0116] Comparative Example 3 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference was that the electrolyte was prepared based on Comparative Example 1, and 0.05 mass% of sulfur dioxide (SO2) was added based on the total weight of the electrolyte.

[0117] Comparative Example 4 An electrolyte and a sodium ion secondary battery were manufactured basically according to the same method as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, and 10 mass% of sulfur dioxide (SO2) was added based on the total weight of the electrolyte.

[0118] Comparative Example 5 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference was that the electrolyte was prepared based on Comparative Example 1, and 1 mass % of 1,3-propane sultone (PS) was added based on the total weight of the electrolyte.

[0119] Comparative Example 6 An electrolyte and a sodium ion secondary battery were manufactured basically by the same method as in Comparative Example 1. The difference is that the preparation of this electrolyte was based on Comparative Example 1, and 1 mass% of ethylene sulfate (DTD) was added based on the total weight of the electrolyte.

[0120] Comparative Example 7 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the preparation of this electrolyte was based on Comparative Example 1, and 1 mass % of fluoroethylene carbonate (FEC) was added based on the total weight of the electrolyte.

[0121] Comparative Example 8 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, and 3 mass% of fluoroethylene carbonate (FEC) was added based on the total weight of the electrolyte.

[0122] Comparative Example 9 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the preparation of this electrolyte was based on Comparative Example 1, and 10 mass% of fluoroethylene carbonate (FEC) was added based on the total weight of the electrolyte.

[0123] Comparative Example 10 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, and 1 mass% of 1,3-propane sultone (PS), 1 mass% of ethylene sulfate (DTD), and 1 mass% of fluoroethylene carbonate (FEC) were added based on the total weight of the electrolyte.

[0124] Example 1 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, with 1 mass% SO2 and 0.1 mass% triethylamine added based on the total weight of the electrolyte.

[0125] Example 2 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, and 1 mass % of SO2 and 1 mass % of triethylamine were added based on the total weight of the electrolyte.

[0126] Example 3 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, with 1 mass% SO2 and 2 mass% triethylamine added based on the total weight of the electrolyte.

[0127] Example 4 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, with 1 mass% SO2 and 5 mass% triethylamine added based on the total weight of the electrolyte.

[0128] Example 5 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, and 0.1 mass % of SO2 and 1 mass % of triethylamine were added based on the total weight of the electrolyte.

[0129] Example 6 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, and 2 mass% SO2 and 1 mass% triethylamine were added based on the total weight of the electrolyte.

[0130] Example 7 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, and 5 mass% SO2 and 1 mass% triethylamine were added based on the total weight of the electrolyte.

[0131] Example 8 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, and 1 mass % of SO2F2 and 1 mass % of triethylamine were added based on the total weight of the electrolyte.

[0132] Example 9 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the preparation of this electrolyte was based on Comparative Example 1, and 1 mass % of SF4 and 1 mass % of triethanolamine were added based on the total weight of the electrolyte.

[0133] Example 10 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference was that the preparation of this electrolyte was based on Comparative Example 1, and 1 mass % of SF6 and 1 mass % of diethanolamine were added based on the total weight of the electrolyte.

[0134] Example 11 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference was that the electrolyte was prepared based on Comparative Example 1, and 1 mass % of CS2 and 1 mass % of triethylenediamine were added based on the total weight of the electrolyte.

[0135] Example 12 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference was that the electrolyte was prepared based on Comparative Example 1, and 1 mass % of SO3 and 1 mass % of hexamethylenetetramine were added based on the total weight of the electrolyte.

[0136] Example 13 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the preparation of this electrolyte was based on Comparative Example 1, and 1 mass % of SO3, 1 mass % of hexamethylenetetramine, and 1 mass % of fluoroethylene carbonate (FEC) were added based on the total weight of the electrolyte.

[0137] Example 14 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the preparation of this electrolyte was based on Comparative Example 1, and 1 mass% of SO3, 1 mass% of hexamethylenetetramine, and 3 mass% of fluoroethylene carbonate (FEC) were added based on the total weight of the electrolyte.

[0138] Example 15 An electrolyte and a sodium ion secondary battery were manufactured basically in the same manner as in Comparative Example 1. The difference is that the electrolyte was prepared based on Comparative Example 1, and 1 mass% of SO3, 1 mass% of hexamethylenetetramine, and 10 mass% of fluoroethylene carbonate (FEC) were added based on the total weight of the electrolyte.

[0139] Cycle capacity retention rate of sodium-ion secondary batteries Fresh sodium ion secondary batteries manufactured in the examples and comparative examples were left at 25°C for 5 minutes. They were charged to 4.2V at a constant current of 1C rate, and then charged at a constant voltage until the current was 0.05C or less. They were then left at rest for 5 minutes, and discharged to 2.0V at a constant current of 1C rate. This was one charge-discharge cycle, and the discharge capacity at this time was taken as the discharge capacity of the first cycle of the sodium ion secondary battery. The sodium ion secondary battery was subjected to 800 cycle charge-discharge tests according to the above method, and the discharge capacity of each cycle was recorded. The capacity retention rate (%) after the sodium ion secondary battery was cycled 800 times at 25°C and 1C / 1C was = 800th cycle discharge capacity / 1st cycle discharge capacity × 100%.

[0140] DC internal resistance test for sodium ion secondary batteries At 25°C, a fresh sodium ion secondary battery was left for 5 minutes, charged at a constant current of 1C rate to 4.2V, and then charged at a constant voltage until the current was 0.05C or less. At this time, the state of charge (SOC) of the battery was 100%. After that, it was left for 5 minutes and discharged at a constant current of 1C rate to adjust the state of charge (SOC) of the sodium ion secondary battery to 50%.

[0141] The sodium ion secondary battery at 50% SOC was left for 10 minutes and then discharged for 30 seconds at a constant current of 4 C. The voltage U1 at the last second of leaving the battery, the voltage U2 at the last second of the constant current discharge at 4 C, and the current I of the constant current discharge at 4 C were recorded.

[0142] The DC internal resistance of a sodium ion secondary battery discharged for 30 seconds at a constant current of 4C rate at 25°C and 50% SOC was (U2-U1) / I.

[0143] Detection of sulfur-containing substances in the air The GT-1000 pump suction type combined gas detector was placed 10 cm above the electrolyte level and the test results were read.

[0144] [Table 1]

[0145] As can be seen from the comparison of the experimental results of Comparative Examples 1-2, 5-6, and 10 with those of Examples 1-4 and 13, the use of a sulfur-containing compound with a low boiling point, compared with PS / DTD, a commonly used sulfur-containing compound, can effectively improve the internal resistance of the battery and significantly improve the room temperature cycle performance. This is because the sulfur-containing compound with a low boiling point can not only reduce the viscosity of the electrolyte, but also form a negative electrode passivation film with a stable low internal resistance.

[0146] As can be seen from the comparison of the experimental results of Comparative Examples 2-4 and Examples 1-7, when the content of SO2 is 0.05 mass% (see Comparative Example 3), the improvement on the internal resistance and cycle performance of the battery core is not obvious. This is because the content of SO2 is too small, and the negative electrode passivation film formed is not sufficient to prevent further reaction of the electrolyte. When the content of SO2 is 10 mass% (see Comparative Example 4), the cycle performance is deteriorated. This is because the internal resistance increases due to the excessive amount of additive, and furthermore, the negative electrode precipitates sodium in the 1C / 1C cycle.

[0147] As can be seen from the experimental results of Examples 1 to 12, the amine-based compound was able to significantly reduce the volatilization of gaseous sulfur-containing compounds.

[0148] As can be seen from the experimental results of Comparative Examples 7-9 and Examples 13-15, by adding the additive FEC in addition to SO2, the cycle life can be further extended and the internal resistance of the battery core can be slightly increased. The main reason for this is that FEC and SO2 form a single layer passivation film with excellent toughness and high strength on the surface of the positive and negative electrodes, and the reduction potential of SO2 is higher than that of FEC, which suppresses the reduction near the FEC passivation film and further suppresses the deterioration of the internal resistance caused by FEC.

[0149] As can be seen from the experimental results of Comparative Example 2 and Examples 8 to 12, the storage and cycle performance could be improved for other low boiling point sulfur-containing compounds.

[0150] The present application is not limited to the above-mentioned embodiment. The above-mentioned embodiment is an example, and any embodiment having substantially the same configuration as the technical idea described in the claims of the present application and having the same effect is included in the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiment and other methods configured by combining some of the components in the embodiment are also included in the scope of the present application, within the scope of the present application. [Explanation of symbols]

[0151] 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 secondary battery, 51 case, 52 electrode assembly, 53 cover plate

Claims

1. An electrolyte for a secondary battery, The electrolyte includes an electrolyte salt, an organic solvent, and an additive, The additive includes an amine compound and a sulfur-containing compound having a boiling point of 70° C. or less, The mass percentage of the sulfur-containing compound in the electrolyte is 0.06% to 8%; The mass ratio of the sulfur-containing compound to the amine compound is 1:(0.08 to 13).

2. The electrolyte according to claim 1 , wherein the mass percentage of the amine compound in the electrolyte is 0.06% to 8%.

3. 3. The electrolyte solution according to claim 1, wherein a total mass percentage of the amine compound and the sulfur-containing compound in the electrolyte solution is 0.5% to 10%.

4. The amine-based compound is an electrolyte solution selected from one or more of the following compounds of formula I, II, and III: R １ ~R ３ , R ８ , R ９ , R １５ , and R １６ each independently represents the following substituents: a hydrogen atom, a halogen atom, a nitro group, and C １ -C ２０ Alkyl group, C ２ -C ２０ Alkenyl group, C ６ -C ２６ Aryl group, C １ -C ２０ Alkylene carboxyl group, carbonyl C １ -C ２０ Alkyl group, C ６ -C ２６ aryloxy groups, R １ and R ２ Or R ３ , R ８ and R ９ , R １５ and R １６ are connected by chemical bonds to form C １ -C ２０ Alkylene group, C ２ -C ２０ Alkenylene group, C ６ -C ２６ Arylene group, carbonyl C １ -C ２０ Alkylene group, C ６ -C ２６ can form an aryleneoxy group, R ４ -R ７ and R １０ -R １４ Each independently represents one of the following substituents: １ -C ２０ Alkylene group, C ２ -C ２０ Alkenylene group, C ６ -C ２６ Arylene group, carbonyl C １ -C ２０ Alkylene group, C ６ -C ２６ aryleneoxy groups, The electrolyte solution according to any one of claims 1 to 3.

5. The compound of formula I is selected from one or more of triethylamine, triethanolamine, diethylamine, diethanolamine, monoethylamine, monoethanolamine, 5-(diethylamino)pentylamine, 1-methylpyrrolidine, and triallylamine; The compound of formula II is selected from one or more of triethylenediamine, 2-methyltriethylenediamine, 1,2-dimethylpiperazine, N-ethylpiperazine, 1-allylpiperazine, piperazine, and 1-ethylhomopiperazine; 5. The electrolyte of claim 1, wherein the compound of formula III is selected from one or more of hexamethylenetetramine, 1,3,6,8-tetraazatricyclo[4.3.1.13,8]undecane, 3,7-dimethyl-1,3,5,7-tetraazabicyclo[3.3.1]nonane, 1,3,5,7-tetraazabicyclo[3.3.1]nonane-3-methylamine, and N,N'-dinitrosopentamethylenetetramine.

6. 6. The electrolyte solution according to claim 1, wherein the molecular weight of the sulfur-containing compound is from 50 g / mol to 200 g / mol.

7. 7. The electrolyte of claim 1, wherein the sulfur-containing compound is selected from one or more of sulfur hexafluoride, sulfur tetrafluoride, sulfuryl fluoride, sulfur dioxide, sulfur trioxide, carbon disulfide, dimethyl sulfide, methyl ethyl sulfide, sulfur monofluoride, sulfur difluoride, thionyl fluoride, and thionyl tetrafluoride.

8. The electrolyte salt is NaPF ６ , NaBF ４ , NaN(SO ２ F) ２ , NaClO ４ , NaAsF ６ , NaB(C ２ O ４ ) ２ , NaBF ２ (C ２ O ４ ), NaN(SO ２ R Ｆ ) ２ , and NaN(SO ２ F) (SO ２ R Ｆ ), wherein R Ｆ is C ｂ F ２ｂ＋１ and b is an integer from 1 to 10.

9. The electrolyte solution according to claim 1 , wherein the organic solvent comprises a carbonate-based organic solvent.

10. 10. The electrolyte solution according to claim 1, wherein the carbonate-based organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, and butylene carbonate.

11. The electrolyte according to claim 1 , further comprising fluoroethylene carbonate, the mass percentage of which in the electrolyte is from 0.01% to 10%.

12. A secondary battery comprising a positive electrode plate, a separator, a negative electrode plate, and the electrolyte solution according to claim 1 .

13. A battery module comprising the secondary battery according to claim 12.

14. A battery pack comprising the battery module according to claim 13.

15. A power consuming device comprising at least one selected from the group consisting of the secondary battery according to claim 12, the battery module according to claim 13, and the battery pack according to claim 14.

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