Electrolyte additive for secondary battery and use thereof

Abstract

An electrolyte additive and a use thereof. The electrolyte additive comprises a compound having the structure shown in formula 1, where X and Y are each independently selected from formula (II); and R is selected from an alkyl or haloalkyl group having 1-5 carbon atoms.

Description

Secondary battery electrolyte additive and application

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Chinese Patent Application No. 202411050808.0, filed on August 01, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of secondary batteries, in particular to an electrolyte additive and application. BACKGROUND

[0004] With the development of science and technology and the improvement of human living quality, green environmental protection is paid more and more attention, and the application range of secondary batteries is more and more extensive. For example, lithium ion batteries have obvious progress in speeding up the research of high energy density and power density, good safety characteristics, excellent cycle performance and wide temperature application, such as higher energy density, excellent cycle performance and good safety, which are widely used in 3C products, electric vehicles and hybrid vehicles and other equipment.

[0005] A secondary battery is composed of a positive electrode, a negative electrode, a separator and an electrolyte, and each component will greatly affect the performance. Among them, the solid electrolyte interface film (SEI) on the surface of the electrode has been widely studied and discussed. The performance of the SEI layer film between the electrode material and the electrolyte depends on its ionic conductivity, ion transfer number and stability to the electrolyte, etc. However, the inventors found that the existing electrode sheet still has problems such as low ionic conductivity of the surface passivation film (i.e. the above-mentioned SEI), easy decomposition, insufficient high-temperature cycle performance, etc., and a suitable electrolyte additive can help to solve such problems.

[0006] Therefore, how to develop a secondary battery electrolyte additive with film-forming properties and good ionic conductivity, stability and cycle performance is a problem to be solved. SUMMARY

[0007] Therefore, one object of the present disclosure is to provide an electrolyte additive, which contains a compound having a structure shown in Formula 1, i.e., a cyclic structure containing a sulfate group, a sulfite group or a carbonate group at both ends is connected together through a cyclic structure containing a ketone carbonyl group in the middle, wherein the ketone carbonyl group can coordinate with metal ions (e.g., lithium ions) in electrolyte salts, and is beneficial to the movement of the additive to the electrode surface with the current and the electrochemical reaction on the electrode surface; on one hand, when the cyclic structure undergoes an electrochemical reaction, the ester group-containing ring can be opened to react with electrolyte salts (e.g., lithium salts) in the electrolyte to form organic electrolyte salts (e.g., organic lithium salts); on the other hand, the cyclic ketone structure is opened to crosslink with organic matters in the battery or itself to form a double electrolyte salt (e.g., lithium salt) organic thin film with good stability, high structural strength and good ion permeability, thereby improving the high-temperature storage and high-temperature cycle performance of the battery.

[0008] Another object of the present disclosure is to provide an electrolyte.

[0009] Still another object of the present disclosure is to provide a secondary battery.

[0010] In a first aspect, embodiments of the present disclosure provide an electrolyte additive, which includes a compound having a structure shown in Formula 1:

[0011] wherein X and Y are each independently selected from R is selected from an alkyl group or a halogenated alkyl group having 1-5 carbon atoms.

[0012] In some embodiments, the electrolyte additive includes at least one of Compound 1-Compound 12:

[0013] In a second aspect, embodiments of the present disclosure provide an electrolyte, which includes a non-aqueous organic solvent, an electrolyte salt and the electrolyte additive according to any one of the preceding embodiments of the first aspect of the present disclosure.

[0014] In some embodiments, the compound having a structure shown in Formula 1 has a mass content of 0.05-10% in the electrolyte, which can be 0.1-5%.

[0015] In some embodiments, the non-aqueous organic solvent includes at least one of an ether solvent, a nitrile solvent, a carbonate solvent, a carboxylic acid ester solvent and a sulfone solvent.

[0016] In some embodiments, the electrolyte salt includes at least one of a lithium salt, a sodium salt, a potassium salt, a magnesium salt, a zinc salt and an aluminum salt, which can be a lithium salt or a sodium salt.

[0017] In some embodiments, the lithium salt comprises at least one of LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiClO4, LiAlCl4, LiCF3SO3, Li2B 10 Cl 10 , at least one of lithium salts of lower aliphatic carboxylic acids.

[0018] In some embodiments, when the electrolyte salt is a lithium salt, the concentration of the lithium salt in the electrolyte is 0.1-8 mol / L.

[0019] In some embodiments, the sodium salt comprises at least one of sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium bisfluorosulfonylimide, sodium trifluoromethylsulfonylimide.

[0020] In some embodiments, when the electrolyte salt is a sodium salt, and the concentration of the sodium salt in the electrolyte is 0.1-2 mol / L.

[0021] In some embodiments, the electrolyte further comprises an auxiliary additive selected from at least one of cyclic carbonate compounds, cyclic sulfate compounds, sulfonic acid lactone compounds, phosphate compounds, borate compounds, and nitrile compounds.

[0022] In some embodiments, the cyclic carbonate compound is selected from at least one of vinylene carbonate, vinyl ethylene carbonate, methylene vinyl carbonate, fluorinated vinyl carbonate, trifluoromethyl vinyl carbonate, bis-fluorinated vinyl carbonate, or a compound having a structure shown in Formula 2;

[0023] In Formula 2, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 are each independently selected from one of a hydrogen atom, a halogen atom, and a C1-C5 group.

[0024] In some embodiments, the cyclic sulfate compound is selected from at least one of vinyl sulfate, 4-methyl vinyl sulfate, propylene sulfate,

[0025] In some embodiments, the sulfonic acid lactone compound is selected from at least one of 1,3-propane sulfonic acid lactone, 1,4-butane sulfonic acid lactone, propylene-1,3-sulfonic acid lactone, ​at least one of the foregoing.

[0026] In some embodiments, the phosphate ester compound comprises a saturated phosphate ester compound and an unsaturated phosphate ester compound, wherein the saturated phosphate ester compound comprises tris(trimethylsilyl) phosphate, and the unsaturated phosphate ester compound comprises a compound having a structure shown in Formula 3:

[0027] In Formula 3, R 31 , R 32 , R 32 are each independently selected from a C1-C5 saturated hydrocarbon group, a C1-C5 unsaturated hydrocarbon group, a C1-C5 halogenated hydrocarbon group, or -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and at least one of the R 31 , the R 32 , the R 33 is an unsaturated hydrocarbon group.

[0028] In some embodiments, the borate ester compound comprises at least one of tris(trimethylsilyl) borate and tris(triethylsilyl) borate.

[0029] In some embodiments, the nitrile compound comprises at least one of butanedinitrile, pentanedinitrile, ethylene glycol bis(propionitrile) ether, hexanetristitnile, hexanedinitrile, heptanedinitrile, octanedinitrile, nonanedinitrile, and decanedinitrile.

[0030] In a third aspect, embodiments of the present disclosure provide a secondary battery, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is the electrolyte according to any one of the embodiments of the second aspect of the present disclosure.

[0031] In some embodiments, the secondary battery is selected from a lithium metal battery, a lithium ion battery, a lithium-sulfur battery, a sodium ion battery, a magnesium ion battery, a potassium ion battery, a zinc ion battery, or an aluminum-lithium battery.

[0032] In some embodiments, the secondary battery is a lithium ion battery, and the positive electrode active material of the secondary battery is selected from a lithium-containing sulfide, a lithium-containing selenide, a lithium-containing halide, LiFe 1-x’ M’ x’ PO4, LiMn 2-y’ M y’ O4, and LiNi x Co y Mn z M 1-x-y-zat least one of O2, wherein M' is selected from at least one of Mn, Mg, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V or Ti, M is selected from at least one of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V or Ti, and 0≤x' <1, 0≤y'≤1, 0≤y≤1, 0≤x≤1, 0≤z≤1, x+y+z≤1;

[0033] In some embodiments, the secondary battery is a sodium-ion battery, and the positive active material is selected from at least one of sodium-containing transition metal oxides, sodium-containing Prussian materials, sodium-containing phosphates, sodium-containing sulfates, and sodium-containing titanates.

[0034] The electrolyte additive described in the present disclosure can at least bring the following beneficial effects:

[0035] The electrolyte additive contains a compound having a structure shown in Formula 1, i.e., a cyclic structure containing sulfate groups, sulfite groups or carbonate groups at both ends is connected together through a cyclic structure containing a ketone carbonyl group in the middle, wherein the ketone carbonyl group can coordinate with metal ions (e.g., lithium ions) in electrolyte salts, facilitating the movement of the additive to the electrode surface with the current and the electrochemical reaction on the electrode surface; at the same time, when the cyclic structure undergoes electrochemical reaction, it is empirically speculated that the ring-opening of the cyclic sulfate, cyclic sulfite and cyclic carbonate reacts with electrolyte salts (e.g., lithium salts) in the electrolyte to form organic electrolyte salts (e.g., organic lithium salts); in addition, the ring-opening of the cyclic ketone structure crosslinks with organic matter in the battery or itself to form a double-electrolyte salt (e.g., lithium salt) organic film with good stability, high structural strength and good ion permeability, thereby improving the high-temperature storage and high-temperature cycle performance of the battery.

[0036] Additional aspects and advantages of the present disclosure will be in part apparent and in part pointed out hereinafter. DETAILED DESCRIPTION

[0037] The embodiments of the present disclosure are described in detail below, which are exemplary and intended to explain the present disclosure, and cannot be understood as a limitation of the present disclosure.

[0038] In the present disclosure, the disclosure of numerical ranges includes all values within the range and the disclosure of further subdivided ranges, including the endpoints and subranges given for these ranges.

[0039] In the present disclosure, the raw materials, equipment, etc. involved, such as without special instructions, are raw materials, equipment that can be made by commercial means or known methods; the methods involved, such as without special instructions, are conventional methods.

[0040] Electrolyte additive

[0041] The electrolyte additive of the embodiments of the present disclosure comprises a compound having a structure shown in Formula 1:

[0042] wherein X and Y are each independently selected from R is selected from an alkyl group having 1-5 carbon atoms or a halogenated alkyl group.

[0043] In some embodiments, the alkyl group having 1-5 carbon atoms or the halogenated alkyl group having 1-5 carbon atoms can be -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-CH2-, etc.

[0044] In the embodiments of the present disclosure, the halogen in the halogenated alkyl group refers to F, Cl, Br or I.

[0045] In some embodiments, the electrolyte additive comprises at least one of Compound 1 to Compound 12:

[0046] A person skilled in the art can know the preparation method of the above-mentioned compound according to the common knowledge in the field of chemical synthesis, knowing the structural formula of the compound shown in Formula 1. For example, Compound 1 can be prepared by the following method:

[0047] Cyclohexanone is subjected to aldol condensation with 4-6 times the equivalent amount (e.g., 5 times the equivalent amount, etc.) of formaldehyde aqueous solution in the presence of 1-10 wt% (e.g., 5.5 wt%, etc.) calcium oxide at 30-80°C (e.g., 55°C, etc.) to prepare tetrahydroxymethyl cyclohexanone, and then the tetrahydroxymethyl cyclohexanone is reacted with 2-3 times the equivalent amount (e.g., 2.5 times the equivalent amount, etc.) of dichlorosulfoxide at 30-80°C (e.g., 55°C, etc.) to prepare a sulfite, which is oxidized with 2-3 times the equivalent amount (e.g., 2.5 times the equivalent amount, etc.) of hydrogen peroxide (e.g., hydrogen peroxide with a mass content of 20%) in the presence of 0.1-1 wt% (e.g., 0.5 wt%, etc.) tungstophosphoric acid to obtain a crude product of Compound 1, and Compound 1 is obtained after recrystallization.

[0048] As a non-limiting example, compound 2 can be prepared by the following method: aldol condensation of cyclopentanone with 4-6 equivalents (e.g., 5 equivalents, etc.) of an aqueous formaldehyde solution in the presence of 1-10 wt% (e.g., 5.5 wt%, etc.) of calcium oxide at 30-80 °C (e.g., 55 °C, etc.) to produce tetrahydroxymethyl cyclopentanone, followed by reaction of the tetrahydroxycyclopentanone with 2-3 equivalents (e.g., 2.5 equivalents, etc.) of dichlorosulfoxide at 30-80 °C (e.g., 55 °C, etc.) to produce crude compound 5, followed by oxidation of the crude compound 5 with 2-3 equivalents (e.g., 2.5 equivalents, etc.) of hydrogen peroxide (e.g., 20% hydrogen peroxide by mass) in the presence of 0.1-1 wt% (e.g., 0.5 wt%, etc.) of tungstophosphoric acid to produce crude compound 2, and recrystallization to produce compound 2.

[0049] As a non-limiting example, compound 3 can be prepared by the following method: aldol condensation of cyclohexanone with 4-6 equivalents (e.g., 5 equivalents, etc.) of an aqueous formaldehyde solution in the presence of 1-10 wt% (e.g., 5.5 wt%, etc.) of calcium oxide at 30-80 °C (e.g., 55 °C, etc.) to produce tetrahydroxymethyl cyclohexanone, followed by reaction of the tetrahydroxycyclohexanone with 2-10 equivalents (e.g., 6 equivalents, etc.) of dimethyl carbonate in the presence of 0.1-10 wt% (e.g., 5 wt%, etc.) of potassium carbonate by mass to produce crude compound 3, and recrystallization to produce compound 3.

[0050] As a non-limiting example, compound 4 can be prepared by the following method: aldol condensation of cyclohexanone with 4-6 equivalents (e.g., 5 equivalents, etc.) of an aqueous formaldehyde solution in the presence of 1-10 wt% (e.g., 5.5 wt%, etc.) of calcium oxide at 30-80 °C (e.g., 55 °C, etc.) to produce tetrahydroxymethyl cyclohexanone, followed by reaction of the tetrahydroxycyclohexanone with 0.5-2 equivalents (e.g., 1.2 equivalents, etc.) of dichlorosulfoxide at 30-80 °C (e.g., 55 °C, etc.) to produce crude compound 7, and recrystallization to produce compound 7, followed by reaction of the compound 7 with 2-10 equivalents (e.g., 6 equivalents, etc.) of dimethyl carbonate in the presence of 0.1-10 wt% (e.g., 5 wt%, etc.) of potassium carbonate by mass to produce a carbonate ester, followed by oxidation of the carbonate ester with 1-2 equivalents (e.g., 1 equivalent, etc.) of hydrogen peroxide (e.g., 20% hydrogen peroxide by mass) in the presence of 0.1-1 wt% (e.g., 0.5 wt%, etc.) of tungstophosphoric acid to produce crude compound 4, and recrystallization to produce compound 4.

[0051] As a non-limiting example, compound 5 can be made by aldol condensation of cyclopentanone with 4-6 equivalents (e.g., 5 equivalents, etc.) of formaldehyde aqueous solution in the presence of 1-10 wt% (e.g., 5.5 wt%, etc.) of calcium oxide at 30-80 °C (e.g., 55 °C, etc.) to make tetrahydroxymethyl cyclopentanone, which is then reacted with 2-3 equivalents (e.g., 1 equivalent, etc.) of dichloro sulfoxide at 30-80 °C (e.g., 55 °C, etc.) to make crude compound 5, which is recrystallized to give compound 5.

[0052] As a non-limiting example, compound 6 can be made by reacting cyclohexanone with 4-6 equivalents (e.g., 5 equivalents, etc.) of diethylamine sulfide trifluoride (DAST) at -10 to -78 °C (e.g., -20 °C, etc.) to make difluorocyclohexanone, which is then reacted with 4-6 equivalents (e.g., 5 equivalents, etc.) of paraformaldehyde in the presence of 1-10 wt% potassium hydroxide to make difluorotetrahydroxymethyl cyclohexanone, which is then reacted with 2-3 equivalents (e.g., 2.5 equivalents, etc.) of dichloro sulfoxide at 30-80 °C (e.g., 55 °C, etc.) to make the sulfite, which is then oxidized with 2 equivalents of meta-chloroperoxybenzoic acid (mCPBA) at 20-50 °C (e.g., 35 °C, etc.) to give crude compound 6, which is recrystallized to give compound 6.

[0053] As a non-limiting example, compound 7 can be made by aldol condensation of cyclohexanone with 4-6 equivalents (e.g., 5 equivalents, etc.) of formaldehyde aqueous solution in the presence of 1-10 wt% (e.g., 5.5 wt%, etc.) of calcium oxide at 30-80 °C (e.g., 55 °C, etc.) to make tetrahydroxymethyl cyclohexanone, which is then reacted with 0.5-1.5 equivalents (e.g., 1 equivalent, etc.) of dichloro sulfoxide at 30-80 °C (e.g., 55 °C, etc.) to make crude compound 7, which is recrystallized to give compound 7.

[0054] As a non-limiting example, compound 8 can be made by reacting cyclopentanone with 4-6 equivalents (e.g., 5 equivalents, etc.) of diethylamine sulfide trifluoride (DAST) to make difluorocyclopentanone, which is then reacted with 4.1 equivalents of paraformaldehyde to make difluorotetrahydroxymethyl cyclopentanone, which is then reacted with 2-3 equivalents (e.g., 2.5 equivalents, etc.) of dichloro sulfoxide at 30-80 °C (e.g., 55 °C, etc.) to make the sulfite, which is then oxidized with 2 equivalents of meta-chloroperoxybenzoic acid (mCPBA) at 20-50 °C (e.g., 35 °C, etc.) to give crude compound 8, which is recrystallized to give compound 8.

[0055] As a non-limiting example, compound 9 can be prepared by the following method: cyclobutanone is subjected to aldol condensation with 4-6 equivalents (e.g., 5 equivalents, etc.) of an aqueous formaldehyde solution in the presence of 1-10 wt% (e.g., 5.5 wt%, etc.) of calcium oxide at 30-80°C (e.g., 55°C, etc.) to prepare tetrahydroxymethyl cyclobutanone, which is then subjected to reaction with 2-3 equivalents (e.g., 1 equivalent, etc.) of dichloro sulfoxide at 30-80°C (e.g., 55°C, etc.) to prepare a sulfite ester, which is then subjected to oxidation with 2-3 equivalents (e.g., 1 equivalent, etc.) of hydrogen peroxide (e.g., hydrogen peroxide with a hydrogen peroxide mass content of 20%) in the presence of 0.1-1 wt% (e.g., 0.5 wt%, etc.) of phosphotungstic acid to obtain crude compound 9, which is recrystallized to obtain compound 9.

[0056] As a non-limiting example, compound 10 can be prepared by the following method: cycloheptanone is subjected to aldol condensation with 4-6 equivalents (e.g., 5 equivalents, etc.) of an aqueous formaldehyde solution in the presence of 1-10 wt% (e.g., 5 wt%, etc.) of a catalyst potassium hydroxide to prepare tetrahydroxymethyl cyclohexanone, which is then subjected to reaction with 2.2 equivalents of dichloro sulfoxide to prepare a sulfite ester, which is then subjected to oxidation with 2-3 equivalents (e.g., 2.5 equivalents, etc.) of hydrogen peroxide (e.g., hydrogen peroxide with a hydrogen peroxide mass content of 20%) in the presence of 0.1-1 wt% (e.g., 0.5 wt%, etc.) of phosphotungstic acid to obtain a sulfite ester, which is recrystallized to obtain compound 10.

[0057] As a non-limiting example, compound 11 can be prepared by the following method: cycloheptanone is subjected to aldol condensation with 4-6 equivalents (e.g., 5 equivalents, etc.) of an aqueous formaldehyde solution in the presence of 1-10 wt% (e.g., 5.5 wt%, etc.) of calcium oxide at 30-80°C (e.g., 55°C, etc.) to prepare tetrahydroxymethyl cycloheptanone, which is then subjected to reaction with 2-10 equivalents (e.g., 6 equivalents, etc.) of dimethyl carbonate in the presence of 0.1-10 wt% (e.g., 5 wt%, etc.) of potassium carbonate to obtain crude compound 11, which is recrystallized to obtain compound 11.

[0058] As a non-limiting example, compound 12 can be prepared by the following method: cyclooctanone is subjected to aldol condensation with 4-6 equivalents (e.g., 5 equivalents, etc.) of an aqueous formaldehyde solution in the presence of 1-10 wt% (e.g., 5.5 wt%, etc.) of calcium oxide at 30-80°C (e.g., 55°C, etc.) to prepare tetrahydroxymethyl cyclooctanone, which is then subjected to reaction with 2-10 equivalents (e.g., 6 equivalents, etc.) of dimethyl carbonate in the presence of 0.1-10 wt% (e.g., 5 wt%, etc.) of potassium carbonate to obtain crude compound 12, which is recrystallized to obtain compound 12.

[0059] The above-mentioned equivalents and mass fractions are relative to the main reactant.

[0060] The electrolyte additive of the embodiments of the present disclosure contains a compound having a structure shown in Formula 1, i.e., a cyclic structure containing a sulfate group, a sulfite group or a carbonate group at both ends is connected together through a cyclic structure containing a ketone carbonyl group in the middle, wherein the ketone carbonyl group can coordinate with metal ions (e.g., lithium ions) in electrolyte salts, facilitating the movement of the additive to the electrode surface along with the current and the electrochemical reaction on the electrode surface; at the same time, when the cyclic structure undergoes electrochemical reaction, it is empirically speculated that the ring-opening of the cyclic sulfate, the cyclic sulfite and the cyclic carbonate reacts with electrolyte salts (e.g., lithium salts) in the electrolyte to form organic electrolyte salts (e.g., organic lithium salts); at the same time, the ring-opening of the cyclic ketone structure crosslinks with organic matters in the battery or itself to form a double electrolyte salt (e.g., lithium salt) organic film with good stability, high structural strength and good ion permeability, thereby improving the high-temperature storage and high-temperature cycle performance of the battery.

[0061] <electrolyte>

[0062] The electrolyte of the embodiments of the present disclosure includes a non-aqueous organic solvent, an electrolyte salt and the electrolyte additive of the embodiments of the present disclosure.

[0063] In some embodiments, the mass content of the compound having a structure shown in Formula 1 in the electrolyte is 0.05-10% based on 100% of the total mass of the electrolyte, including but not limited to 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5% or 10%.

[0064] In the embodiments of the present disclosure, when the content of the compound having a structure shown in Formula 1 is within the above range, the stability of the film formed on the electrode surface can be effectively maintained, and the battery performance can be improved; if the content of the compound having a structure shown in Formula 1 is too low, it is difficult to significantly improve the performance of the battery; if the content of the compound having a structure shown in Formula 1 is too high, it may affect the function of other substances in the electrolyte due to excessive decomposition products.

[0065] As an optional example, the mass content of the compound having a structure shown in Formula 1 in the electrolyte is 0.1-5% based on 100% of the total mass of the electrolyte.

[0066] In some embodiments, the electrolyte salt includes but is not limited to at least one of lithium salts, sodium salts, potassium salts, magnesium salts, zinc salts and aluminum salts, etc.

[0067] As an optional example, the electrolyte salt is a lithium salt or a sodium salt.

[0068] The alkali metal ions dissociated from the electrolyte salt in the electrolyte solution are deintercalated and intercalated between the positive electrode and the negative electrode to complete the charge and discharge cycle. The concentration of the electrolyte salt directly affects the transfer speed of the alkali metal ions, and the transfer speed of the alkali metal ions affects the potential change of the negative electrode. During the fast charging of the battery, it is necessary to increase the moving speed of the alkali metal ions as much as possible to prevent the formation of lithium dendrites caused by the rapid drop of the potential of the negative electrode, which brings potential safety hazards to the battery, and also prevents the rapid decay of the cycle capacity of the battery. When the content of the electrolyte salt is too low, the intercalation and deintercalation efficiency of the alkali metal ions between the positive electrode and the negative electrode will be reduced, which cannot meet the demand of fast charging of the battery; when the content of the electrolyte salt is too high, the viscosity of the non-aqueous electrolyte will increase, which is also not conducive to the improvement of the intercalation and deintercalation efficiency of the alkali metal ions, and increases the internal resistance of the battery.

[0069] In some embodiments, the lithium salt includes, but is not limited to, at least one of LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiClO4, LiAlCl4, LiCF3SO3, Li2B 10 Cl 10 , lithium salt of low aliphatic carboxylic acid, etc.

[0070] In some embodiments, when the electrolyte salt is a lithium salt, the concentration of the lithium salt in the electrolyte solution is 0.1-8 mol / L, including but not limited to 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, 6 mol / L, 6.5 mol / L, 7 mol / L, 7.5 mol / L or 8 mol / L, etc.

[0071] As an optional example, when the electrolyte salt is a lithium salt, the concentration of the lithium salt in the electrolyte solution is 0.5-2.5 mol / L.

[0072] In some embodiments, the sodium salt includes, but is not limited to, at least one of sodium perchlorate (NaClO4), sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium bisfluorosulfonylimide (NaFSI), sodium trifluoromethylsulfonate (NaOTf), sodium bis-trifluoromethylsulfonylimide (NaTFSI), etc.

[0073] In some embodiments, when the electrolyte salt is a sodium salt, and the concentration of the sodium salt in the electrolyte is 0.1-2 mol / L, including but not limited to 0.1 mol / L, 0.4 mol / L, 0.5 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, or 2 mol / L, etc.

[0074] As an optional example, when the electrolyte salt is a sodium salt, and the concentration of the sodium salt in the electrolyte is 0.4-1.5 mol / L.

[0075] In some embodiments, the electrolyte further includes an auxiliary additive, which includes but is not limited to at least one of a cyclic carbonate compound, a cyclic sulfate compound, a sulfonic acid lactone compound, a phosphate ester compound, a borate ester compound, and a nitrile compound, etc.

[0076] In some embodiments, the cyclic carbonate compound includes but is not limited to at least one of vinylene carbonate, vinyl ethylene carbonate, methylene vinyl carbonate, fluoro vinyl carbonate, trifluoromethyl vinyl carbonate, difluoro vinyl carbonate, or a compound having a structure shown in Formula 2, etc.

[0077] In Formula 2, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 is each independently selected from one of a hydrogen atom, a halogen atom, and a C1-C5 group.

[0078] As a non-limiting enumeration, the C1-C5 group includes but is not limited to a C1-C5 cyano group, a C1-C5 ester group, a C1-C5 alkyl group, a trifluoromethyl group, or a C1-C5 sulfonate group, etc.

[0079] In embodiments of the present disclosure, the term “cyano group” refers to -CN.

[0080] In embodiments of the present disclosure, the term “ester group” is a functional group of an ester in a carboxylic acid derivative, with a structural formula of -COOR (R is generally an alkyl group or other non-H group).

[0081] In embodiments of the present disclosure, the term “sulfonate group” refers to a group of Formula -O-SO2-R i , where R i is an alkyl group, etc.

[0082] As an optional example, the compound having a structure shown in Formula 2 includes, but is not limited to, at least one of the compounds shown in the following compounds 2-1 to 2-6:

[0083] In some embodiments, the cyclic sulfate compound is at least one selected from the group consisting of ethylene sulfate, 4-methyl ethylene sulfate, propylene sulfate,

[0084] In some embodiments, the sulfonic acid lactone compound is at least one selected from the group consisting of 1,3-propane sulfonic acid lactone, 1,4-butane sulfonic acid lactone, propenyl-1,3-sulfonic acid lactone,

[0085] In some embodiments, the phosphoric acid ester compound includes a saturated phosphoric acid ester compound and an unsaturated phosphoric acid ester compound, wherein the saturated phosphoric acid ester compound includes tris(trimethylsilyl)phosphate, and the unsaturated phosphoric acid ester compound includes a compound having a structure shown in Formula 3:

[0086] In Formula 3, R 31 , R 32 , and R 32 are each independently selected from a C1-C5 saturated hydrocarbon group, a C1-C5 unsaturated hydrocarbon group, a C1-C5 halogenated hydrocarbon group, or -Si(C m H 2m+1 )3, m is a natural number of 1 to 3, and R 31 , R 32 , and R 33 are each independently selected from a C1-C5 saturated hydrocarbon group, a C1-C5 unsaturated hydrocarbon group, a C1-C5 halogenated hydrocarbon group, or -Si(C

[0087] In the embodiments of the present disclosure, the term "saturated hydrocarbon group" also referred to as an alkyl group, refers to a straight chain or branched alkyl radical containing 1 to 5 carbon atoms. For example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, and the like.

[0088] In the embodiments of the present disclosure, the term "unsaturated hydrocarbon group" refers to a hydrocarbon compound containing a carbon-carbon double bond or a carbon-carbon triple bond in the molecule.

[0089] As a non-limiting enumeration, the number of carbon atoms in the C1-C5 unsaturated hydrocarbon group and the C1-C5 halogenated hydrocarbon group is 1, 2, 3, 4, or 5. For example, the C1-C5 unsaturated hydrocarbon group includes, but is not limited to, a vinyl group, an ethynyl group, a propenyl group, a 2-methyl propenyl group, a 1,4-butadienyl group, a propynyl group, and the like. The C1-C5 halogenated hydrocarbon group includes, but is not limited to, a trifluoromethyl group, a trifluoroethyl group, a monofluorinated propyl group, a monofluorinated butyl group, or a difluorinated pentyl group, and the like.

[0090] ​​As a non-limiting example, m has a value of 1, 2, or 3, i.e., Si(C m H 2m+1 )3is Si(CH3)3, Si(C2H5)3, or Si(C3H7)3.

[0091] As an optional example, the compound having the structure of Formula 3 includes, but is not limited to, at least one of tripropargyl phosphate, dipropargyl methyl phosphate, dipropargyl ethyl phosphate, dipropargyl propyl phosphate, dipropargyl trifluoromethyl phosphate, dipropargyl-2,2,2-trifluoroethyl phosphate, dipropargyl-3,3,3-trifluoropropyl phosphate, dipropargyl hexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2,2,2-trifluoroethyl phosphate, diallyl-3,3,3-trifluoropropyl phosphate, diallyl hexafluoroisopropyl phosphate, and the like.

[0092] In some embodiments, the borate compound includes, but is not limited to, at least one of tris(trimethylsilyl) borate, tris(triethylsilyl) borate, and the like.

[0093] In some embodiments, the nitrile compound includes, but is not limited to, at least one of butanedinitrile, pentanedinitrile, ethylene glycol bis(propionitrile) ether, hexanetristitnile, hexanedinitrile, heptanedinitrile, octanedinitrile, nonanedinitrile, decanedinitrile, and the like.

[0094] In the embodiments of the present disclosure, the content of the auxiliary additive in the electrolyte, based on the total mass of the electrolyte being 100%, varies depending on the selection of the substance type of the auxiliary additive. Specifically, in some embodiments, when the auxiliary additive is selected from at least one of other substances in the above-mentioned cyclic carbonate compounds, cyclic sulfate compounds, sulfonic acid lactone compounds, phosphate compounds, borate compounds, and nitrile compounds, other than fluoroethylene carbonate, the content of any of the optional substances in the non-aqueous electrolyte is 10% or less, including but not limited to 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, 10%, and the like; optionally, the content of any of the above-mentioned optional substances in the non-aqueous electrolyte is 0.1-5%, further optionally 0.1%-3%. In other embodiments, when the auxiliary additive is selected to be fluoroethylene carbonate, the content of fluoroethylene carbonate, based on the total mass of the electrolyte being 100%, is 0.05%-30%, including but not limited to 0.05%, 1%, 2.5%, 5%, 7.5%, 10%, 12.5%, 15%, 17.5%, 20%, 22.5%, 25%, 27.5%, or 30%, and the like.

[0095] In the electrolyte of the embodiments of the present disclosure, compared to single addition or combination of other existing additives, the compound represented by the above-mentioned structural formula 1 and the above-mentioned auxiliary additive exhibit obvious synergistic effect in improving the performance of the battery, indicating that the compound represented by the structural formula 1 and the auxiliary additive can form a film together on the electrode surface to compensate for the film formation defects of single addition, and obtain a more stable passivation film.

[0096] In some embodiments, the non-aqueous organic solvent includes but is not limited to at least one of ether solvents, nitrile solvents, carbonate solvents, carboxylate solvents, and sulfone solvents.

[0097] In some embodiments, the ether solvent includes a cyclic ether or a chain ether.

[0098] As a non-limiting enumeration, the cyclic ether specifically can be but is not limited to at least one of 1,3-dioxolane (DOL), 1,4-dioxane (DX), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), 2-trifluoromethyltetrahydrofuran (2-CF3-THF), and the like.

[0099] As a non-limiting enumeration, the chain ether can be, but is not limited to, at least one of dimethoxymethane (DMM), 1,2-dimethoxyethane (DME), diethylene glycol dimethyl ether (TEGDME), and the like.

[0100] As a non-limiting enumeration, the nitrile-based solvent can be, but is not limited to, at least one of acetonitrile, glutaronitrile, malonitrile, and the like.

[0101] In some embodiments, the carbonate-based solvent includes, but is not limited to, a cyclic carbonate or a chain carbonate.

[0102] As a non-limiting enumeration, the cyclic carbonate can be, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), butylene carbonate (BC), and the like.

[0103] As a non-limiting enumeration, the chain carbonate can be, but is not limited to, at least one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), and the like.

[0104] As a non-limiting enumeration, the carboxylic acid ester-based solvent can be, but is not limited to, at least one of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), butyl propionate, and the like.

[0105] As a non-limiting enumeration, the sulfone-based solvent includes, but is not limited to, at least one of dimethyl sulfoxide, sulfolane, diethyl sulfone, methyl ethyl sulfone, or dimethyl sulfone, and the like.

[0106] <Secondary battery>

[0107] The secondary battery of the embodiments of the present disclosure includes a positive electrode, a negative electrode, and an electrolyte, and the electrolyte is the electrolyte of the embodiments of the present disclosure.

[0108] In some embodiments, the secondary battery is selected from a lithium metal battery, a lithium ion battery, a lithium-sulfur battery, a sodium ion battery, a magnesium ion battery, a potassium ion battery, a zinc ion battery, or an aluminum-lithium battery.

[0109] In some embodiments, the above-mentioned positive electrode includes a positive electrode material layer, and the positive electrode material layer includes a positive electrode active material. The type and content of the positive electrode active material are not particularly limited, and can be selected according to actual needs. As long as it is a positive electrode active material or a conversion-type positive electrode material capable of reversibly intercalating / deintercalating metal ions (lithium ions, sodium ions, potassium ions, magnesium ions, zinc ions, aluminum ions, etc.), it can be used.

[0110] As an optional example, the secondary battery is a lithium ion battery, and the positive active material of the secondary battery includes, but is not limited to, at least one of lithium-containing sulfides, lithium-containing selenides, lithium-containing halides, LiFe 1-x’ M’ x’ PO4, LiMn 2-y’ M y’ O4, and LiNi x Co y Mn z M 1-x-y-z O2, etc., wherein M’ includes, but is not limited to, at least one of Mn, Mg, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, or Ti, etc., M includes, but is not limited to, at least one of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, or Ti, etc., and 0≤x’<1, 0≤y’≤1, 0≤y≤1, 0≤x≤1, 0≤z≤1, x+y+z≤1.

[0111] As a non-limiting enumeration, the values of x’, y’, y, x, z, x+y+z include, but are not limited to, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, etc.

[0112] As an optional example, when the secondary battery is a lithium ion battery, the positive active material of the secondary battery can be selected from at least one of LiCoO2, LiFePO4, LiFe 0.8 Mn 0.2 PO4, LiMn2O4, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.5 Co 0.2 Mn 0.2 Al 0.1 O2, LiNi 0.5 Co 0.2 Al 0.3 O2.

[0113] In other embodiments, the secondary battery is a sodium ion battery, and the positive active material includes, but is not limited to, at least one of sodium-containing transition metal oxides, sodium-containing Prussian materials, sodium-containing phosphates, sodium-containing sulfates, sodium-containing titanates, etc.

[0114] In some embodiments, the sodium-containing transition metal oxide can be Na a T b O c wherein T includes, but is not limited to, at least one of Cr, Fe, Co, Ni, Cu, Mn, Sn, Mo, Sb, V, etc., 1

[0115] By way of non-limiting example, a can have a value that includes, but is not limited to, 1, 3, 5, 8, or 10, etc.; b can have a value that includes, but is not limited to, 1, 2, 3, 4, or 5, etc.; and c can have a value that includes, but is not limited to, 1, 3, 5, 7, 10, 13, 15, or 19, etc.

[0116] Optionally, the sodium-containing transition metal oxide is NaNi m Fe n Mn p O2(m+n+p = 1, 0 m Co n Mn p O2(m+n+p = 1, 0

[0117] By way of non-limiting example, m, n, and p can each have a value that includes, but is not limited to, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, etc.

[0118] In some embodiments, the sodium-containing Prussian analog material can have a molecular formula of Na d Q[Q'(CN)6] · fH2O, wherein Q is a transition metal, Q' is a transition metal, 0 < d e

[0119] By way of non-limiting example, Q and Q' can each include, but are not limited to, at least one of Cr, Fe, Co, Ni, Cu, Mn, Mo, V, Ti, Zr, etc.

[0120] By way of non-limiting example, d can have a value that includes, but is not limited to, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.3, 1.5, 1.8, or 2, etc.

[0121] By way of non-limiting example, e can have a value that includes, but is not limited to, 0.8, 0.85, 0.9, or 0.95, etc.

[0122] By way of non-limiting example, f can have a value that includes, but is not limited to, 0.1, 0.5, 1, 5, 10, 15, or 20, etc.

[0123] ​Optionally, the sodium-containing prussian-type material is Na h Mn[Fe(CN)6] i • jH2O (0 < h < 2, 0 < i < 1, 0 < j < 10) or Na h Fe[Fe(CN)6] i • jH2O (0 < h < 2, 0 < i < 1, 0 < j < 10).

[0124] As non-limiting examples, h can include but is not limited to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.3, 1.5, 1.8, or 2, etc.

[0125] As non-limiting examples, i can include but is not limited to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, etc.

[0126] As non-limiting examples, j can include but is not limited to 0.1, 0.5, 1, 3, 5, 8, or 10, etc.

[0127] In some embodiments, the sodium-containing phosphate has a chemical formula of Na3(GO 1-k PO4)2F 1+2k , 0 < k < 1, and G is selected from at least one of Al, V, Ge, Fe, Ga. As an optional example, the sodium-containing phosphate is Na3(VPO4)2F3 or Na3(VOPO4)2F.

[0128] As non-limiting examples, k can include but is not limited to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, etc.

[0129] In other embodiments, the sodium-containing phosphate has a chemical formula of Na2JPO4F, J is selected from at least one of Fe, Mn. As an optional example, the sodium-containing phosphate is Na2FePO4F or Na2MnPO4F.

[0130] In some embodiments, the sodium-containing titanate material includes but is not limited to at least one of Na2Ti3O7, Na2Ti6O 13 , Na4Ti5O 12 , Li4Ti5O 12 , NaTi2(PO4)3, etc.

[0131] In some embodiments, the sodium-containing sulfate has a chemical formula of Na2Z(SO4)2·2H2O, Z can be selected from at least one of Cr, Fe, Co, Ni, Cu, Mn, Sn, Mo, Sb, V.

[0132] In some embodiments, the positive electrode further comprises a positive electrode current collector, and the positive electrode material layer is disposed on a surface of the positive electrode current collector.

[0133] In some embodiments, the positive electrode current collector is selected from an electron-conducting metal material, and optionally, the positive electrode current collector comprises at least one of Al, Ni, tin, copper, and stainless steel. As an optional example, the positive electrode current collector is selected from an aluminum foil.

[0134] In some embodiments, the positive electrode active material layer further comprises a positive electrode binder and a positive electrode conductive agent, and the positive electrode active material, the positive electrode binder, and the positive electrode conductive agent are blended to obtain the positive electrode material layer.

[0135] In some embodiments, the positive electrode binder comprises at least one of polyvinylidene fluoride, a copolymer of polyvinylidene fluoride, polytetrafluoroethylene, a copolymer of polyvinylidene fluoride-hexafluoropropylene, a copolymer of tetrafluoroethylene-hexafluoropropylene, a copolymer of tetrafluoroethylene-perfluoroalkyl vinyl ether, a copolymer of ethylene-tetrafluoroethylene, a copolymer of polyvinylidene fluoride-tetrafluoroethylene, a copolymer of polyvinylidene fluoride-trifluoroethylene, a copolymer of polyvinylidene fluoride-trichloroethylene, a copolymer of polyvinylidene fluoride-fluoroethylene, a copolymer of polyvinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, a thermoplastic polyimide, a thermoplastic resin such as polyethylene and polypropylene, an acrylic resin, and a styrene butadiene rubber.

[0136] In some embodiments, the positive electrode conductive agent comprises at least one of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fibers, carbon nanotubes, graphene, or reduced graphene oxide.

[0137] In some embodiments, the negative electrode comprises a negative electrode material layer, and the negative electrode material layer comprises a negative electrode active material, which is not particularly limited in type and content, and can be selected according to actual needs.

[0138] In optional embodiments, the secondary battery is a lithium ion battery, and the negative electrode active material comprises at least one of a carbon-based negative electrode, a silicon-based negative electrode, a tin-based negative electrode, a lithium negative electrode, and the like. The carbon-based negative electrode can comprise graphite, hard carbon, soft carbon, graphene, mesocarbon microbeads, and the like; the silicon-based negative electrode can comprise a silicon material, an oxide of silicon, a silicon-carbon composite material, a silicon alloy material, and the like; the tin-based negative electrode can comprise tin, tin-carbon, tin-oxygen, a tin metal compound; and the lithium negative electrode can comprise metallic lithium or a lithium alloy. The lithium alloy can be at least one of a lithium-silicon alloy, a lithium-sodium alloy, a lithium-potassium alloy, a lithium-aluminum alloy, a lithium-tin alloy, and a lithium-indium alloy.

[0139] In an optional embodiment, the secondary battery is a sodium ion battery, and the negative electrode active material includes, but is not limited to, at least one of metal sodium, graphite, soft carbon, hard carbon, carbon fiber, mesocarbon microbeads, silicon-based material, tin-based material, lithium titanate, or other metal capable of forming an alloy with sodium, etc. The alloy material can also be at least one of Si, Ge, Sn, Pb, Sb, and C. The graphite can be at least one of artificial graphite, natural graphite, and modified graphite. The silicon-based material can be at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, and silicon alloy. The tin-based material can be at least one of elemental tin, tin oxide compound, and tin alloy.

[0140] In some embodiments, the negative electrode further includes a negative electrode current collector, and the negative electrode material layer is disposed on a surface of the negative electrode current collector. The material of the negative electrode current collector can be the same as that of the positive electrode current collector, which is not repeated here.

[0141] In some embodiments, the negative electrode material layer further includes a negative electrode binder and a negative electrode conductive agent, and the negative electrode active material, the negative electrode binder, and the negative electrode conductive agent are blended to obtain the negative electrode material layer. The negative electrode binder and the negative electrode conductive agent can be the same as the positive electrode binder and the positive electrode conductive agent, respectively, which is not repeated here.

[0142] In some embodiments, the secondary battery further includes a separator between the positive electrode and the negative electrode.

[0143] In some embodiments, the separator can be a conventional separator, which can be a ceramic separator, a polymer separator, a non-woven fabric, an inorganic-organic composite separator, etc., including but not limited to a single-layer PP (polypropylene) separator, a single-layer PE (polyethylene) separator, a double-layer PP / PE separator, a double-layer PP / PP separator, and a three-layer PP / PE / PP separator, etc.

[0144] The secondary battery of the embodiments of the present disclosure uses the electrolyte of the embodiments of the present disclosure. The compound shown in Structural Formula 1 can form a passivation film with excellent performance on the positive electrode and the negative electrode, thereby effectively improving the high-temperature storage performance and the high-temperature cycle performance of the battery and improving the power characteristics of the battery. In addition, due to the use of the electrolyte of the embodiments of the present disclosure, it is reasonably speculated that the coordination of the ketone carbonyl group in the compound shown in Structural Formula 1 with the metal (e.g., lithium) in the electrolyte salt can move to the electrode surface with the current to undergo an electrochemical reaction, the cyclic sulfate, cyclic sulfite, and cyclic carbonate are opened to form an organic sulfate / sulfite / carbonate electrolyte salt (e.g., lithium sulfate), and at the same time, the ketone carbonyl group is opened and crosslinked to form a double electrolyte salt (e.g., lithium salt) organic film with good stability, high structural strength, and good ion permeability, thereby improving the high-temperature storage and high-temperature cycle performance of the battery.

[0145] Certain features of the present disclosure are further illustrated in the following non-limiting examples.

[0146] I. Performance Test

[0147] 1. Test of High Temperature Cycle Performance

[0148] The test method is as follows: after formation, the battery is placed at 45°C for 2h, then charged at a rate of 0.5C to 4.0V, then charged at constant voltage until the current is 0.03C, then discharged at a current of 1C to 1.5V, and the cycle is repeated 1000 times.

[0149] The initial discharge capacity D1, initial battery volume V1, retention capacity D2 after 1000 cycles, recovery capacity D3, and battery volume V2 after cycling are measured.

[0150] The calculation formula is as follows:

[0151] Capacity retention rate (%) of the battery after 1000 cycles = capacity D2 / initial capacity D1 x 100%;

[0152] Capacity recovery rate (%) of the battery after 1000 cycles = capacity D3 / initial capacity D1 x 100%

[0153] Volume expansion rate (%) = (battery volume V2 after cycling-initial battery volume V1) / initial battery volume V1 x 100%.

[0154] 2. Test of High Temperature Storage Performance

[0155] The test method is as follows: after formation, the battery is charged at a current of 0.5C to 4.0V at room temperature, then charged at constant voltage until the current is 0.03C, then discharged at a current of 1C to 1.5V, the initial discharge capacity D1, initial battery volume V1, and initial impedance F1 are measured, then charged to full capacity, and stored at 60°C for 30 days, then discharged at 1C to 3V, the retention capacity D2, recovery capacity D3, impedance F2 after storage, and battery volume V2 after storage are measured.

[0156] The calculation formula is as follows:

[0157] Battery capacity retention rate (%) = retention capacity D2 / initial capacity D1 x 100%;

[0158] Battery capacity recovery rate (%) = recovery capacity D3 / initial capacity D1 x 100%;

[0159] Volume expansion rate (%) = (battery volume V2 after storage-initial battery volume V1) / initial battery volume V1 x 100%;

[0160] Internal resistance growth rate (%) = Impedance after storage F2 / Initial impedance F1 × 100%.

[0161] II. Examples and Comparative Examples

[0162] The compounds involved in each embodiment and comparative example are shown in Table 1:

[0163] Table 1 shows the compounds involved in each example and comparative example.

[0164] 1. Lithium-ion batteries (Examples 1-20 and Comparative Examples 1-9)

[0165] Example 1

[0166] <Methods for preparing electrolyte>

[0167] The electrolyte preparation method of this embodiment is as follows: ethylene carbonate (EC), diethyl carbonate (DEC) and methyl ethyl carbonate (EMC) are mixed in a mass ratio of EC:DEC:EMC = 0.9:1:1, and then lithium hexafluorophosphate (LiPF6) is added to a molar concentration of 1.1 mol / L. Based on the total weight of the electrolyte being 100%, 0.05% of an additive, namely compound 1, is added.

[0168] <Preparation Methods of Lithium-ion Batteries>

[0169] The method for preparing a lithium-ion battery in this embodiment includes the following steps:

[0170] 1) Preparation of the positive electrode: Lithium nickel cobalt manganese oxide (LiNiO) was mixed with the positive electrode active material in a mass ratio of 93:4:3. 0.5 Co 0.2 Mn 0.3 O2, conductive carbon black Super-P, and the binder polyvinylidene fluoride (PVDF) were dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry with a viscosity of approximately 6000 mPa·s. The slurry was uniformly coated on opposite surfaces of an 18 μm thick aluminum foil, dried, calendered, and vacuum dried. Aluminum leads were then welded onto the foil using an ultrasonic welder to obtain a positive electrode sheet with a thickness of 120 μm.

[0171] 2) Preparation of the negative electrode:

[0172] The negative active material artificial graphite, conductive carbon black Super-P, binder styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were mixed in a mass ratio of 94:1:2.5:2.5, and then dispersed in deionized water to obtain a negative electrode slurry with a viscosity of about 4000 mPa.s. The slurry was coated on the opposite two sides of a copper foil with a thickness of 8 μm, dried, calendered and vacuum dried, and then a nickel lead was welded on the electrode plate using an ultrasonic welding machine to obtain a negative electrode plate with a thickness of 120 μm.

[0173] 3) Preparation of the battery cell:

[0174] A three-layer PP / PE / PP separator with a thickness of 20 μm was placed between the positive electrode and the negative electrode, and then the sandwich structure of the positive electrode, the negative electrode and the separator was wound, and the wound body was flattened and placed in an aluminum foil packaging bag, and vacuum baked at 75 °C for 48 h to obtain a battery cell to be injected with liquid.

[0175] 4) Liquid injection and formation of the battery cell:

[0176] The electrolyte prepared in this example was injected into the battery cell in a glove box with the dew point controlled below -40 °C, and vacuum packaged and left for 24 h.

[0177] Then the first charge conventional formation was carried out in the following steps: 0.05 C constant current charging for 180 min, 0.2 C constant current charging to 3.95 V, twice vacuum sealing, and then further constant current charging to 4.2 V at a current of 0.2 C, and after standing at room temperature for 24 h, constant current discharging to 3.0 V at a current of 0.2 C, to obtain a LiNi 0.5 Co 0.2 Mn 0.3 O2 / artificial graphite lithium ion battery.

[0178] Examples 2-20 and Comparative Examples 1-8 are basically the same as Example 1, except that the substance selection and amount of some additives are different. It should be noted that the additives here include the compound shown in structural formula 1 (electrolyte additive) and / or auxiliary additive).

[0179] Wherein:

[0180] Examples 1-9 and Comparative Examples 1-5 investigate the effects of different contents of the compound shown in structural formula 1 of the present disclosure, the use of the same electrolyte additive in a specific amount of the present disclosure in combination with an auxiliary additive, the use of no additives, and the use of only an auxiliary additive on the high-temperature cycle performance of lithium ion batteries, as shown in Table 2.

[0181] Table 2 Substance and parameter selection, high-temperature cycle performance of Examples 1-9 and Comparative Examples 1-5

[0182] According to Table 2:

[0183] The test results of Comparative Examples 1-8 show that as the amount of compound 1 of structural formula 1 increases, the volume expansion rate of the lithium ion battery first decreases and then increases, and the capacity retention rate and the capacity recovery rate first increase and then decrease, indicating that too much or too little amount of compound 1 of structural formula 1 can improve the high-temperature cycle performance of the lithium ion battery. In particular, when the amount of compound 1 of structural formula 1 is 0.5-5 wt%, the lithium ion battery has the optimal high-temperature cycle performance.

[0184] The test results of Comparative Examples 1-8 and Comparative Examples 1-4 show that compared with traditional vinylene carbonate (VC), vinyl sulfate (DTD), and 1,3-propane sulfonate (PS), using compound 1 of structural formula 1 provided by the present disclosure as an additive can more significantly improve the cycle performance of the lithium ion battery at high temperature, indicating that the passivation film formed by compound 1 of structural formula 1 is more stable and has more excellent lithium ion permeability.

[0185] The test results of Comparative Example 9 and Comparative Example 5 show that using compound 1 of structural formula 1 provided by the present disclosure and vinyl carbonate (VC) as additives can further improve the cycle performance of the lithium ion battery at high temperature compared with using DTD and vinyl carbonate (VC) as additives.

[0186] Examples 4, 11-21, and Comparative Examples 1-4 investigate the influence of different compounds of structural formula 1 provided by the present disclosure on the high-temperature cycle performance of the lithium ion battery under three conditions of the same content, without any additives, and using only auxiliary additives. The specific conditions are shown in Table 3.

[0187] Table 3: Part of substances and parameters selected for Examples 4, 10-20, and Comparative Examples 1-4, and high-temperature cycle performance

[0188] According to Table 3:

[0189] The test results of Comparative Examples 4, 10-20, and Comparative Examples 1-4 show that compared with lithium ion batteries without additives or with existing additives, using the compound of structural formula 1 provided by the present disclosure as an additive, the obtained lithium ion battery has good high-temperature cycle performance.

[0190] Comparative Example 6 (the ring containing a carbonyl group in structural formula 1 is replaced by a non-cyclic structure containing a carbonyl group)

[0191] This comparative example is basically the same as Example 4, except that:

[0192] Compound 13 is used to replace compound 1 in the electrolyte.

[0193] Comparative Example 7 (the ring containing carbonyl group in the intermediate of structural formula 2 is replaced by a ring structure not containing carbonyl group)

[0194] This comparative example is basically the same as Example 4, except that:

[0195] Compound 14 is used to replace compound 1 in the electrolyte.

[0196] Comparative Example 8 (the ring containing carbonyl group in the intermediate of structural formula 1 is replaced by a non-cyclic structure containing carbonyl group)

[0197] This comparative example is basically the same as Example 9, except that:

[0198] Compound 13 is used to replace compound 1 in the electrolyte.

[0199] Comparative Example 9 (the ring containing carbonyl group in the intermediate of structural formula 1 is replaced by a ring structure not containing carbonyl group)

[0200] This comparative example is basically the same as Example 9, except that:

[0201] Compound 14 is used to replace compound 1 in the electrolyte.

[0202] The high-temperature cycle performance test results of the lithium ion batteries corresponding to Examples 4, 9 and Comparative Examples 6-9 are shown in Table 4.

[0203] Table 4. Selection of some substances and parameters, high-temperature cycle performance of Examples 4, 9 and Comparative Examples 6-9

[0204] As can be seen from Table 4, from Examples 4, 9 and Comparative Examples 5, 7, it can be seen that only the carbonyl group structure, its high-temperature cycle performance is also better than the currently used additive, but not as good as the effect of compound 1, it is speculated that without the ring structure, the cross-linked structure formed after oxidation of the carbonyl group is not as stable as compound 1; from Examples 4, 9 and Comparative Examples 6, 8, it can be seen that only the ring structure, its high-temperature cycle performance is comparable to the currently used additive, not as good as the effect of compound 1, it is speculated that without the carbonyl group structure, the cross-linked structure cannot be formed, resulting in a film strength not as good as compound 1.

[0205] 2. Sodium ion battery (Examples 21-40 and Comparative Examples 10-15)

[0206] Example 21

[0207] <Method for preparing an electrolyte>

[0208] Vinyl carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of EC:DEC:EMC = 1:1:1, then sodium hexafluorophosphate (NaPF6) was added to a molar concentration of 1 mol / L, 1.0% of an additive was added based on the total weight of the electrolyte, and the additive was compound 1.

[0209] <Method for manufacturing sodium-ion battery>

[0210] The method for manufacturing a sodium-ion battery of the present embodiment includes the following steps:

[0211] 1) Preparation of positive electrode sheet:

[0212] The positive electrode active material Na3V2(PO4)3, conductive carbon black Super-P and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 94:3:3, and then dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry with a viscosity of about 8000 mPa.s. The slurry was uniformly coated on both sides of a 15 μm aluminum foil, dried, calendered and vacuum dried, and then an aluminum lead was welded on using an ultrasonic welding machine to obtain a positive electrode sheet with a thickness of 150 μm.

[0213] 2) Preparation of negative electrode sheet:

[0214] The negative electrode active material spherical hard carbon, conductive carbon black Super-P, binder styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were mixed in a mass ratio of 97:1:1:1, and then dispersed in deionized water to obtain a negative electrode slurry with a viscosity of about 5000 mPa.s. The slurry was coated on both sides of a 15 μm aluminum foil, dried, calendered and vacuum dried, and then a nickel lead was welded on using an ultrasonic welding machine to obtain a negative electrode sheet with a thickness of 150 μm.

[0215] 4) The positive electrode sheet, separator (20 μm three-layer PP / PE / PP separator), negative electrode sheet were stacked in order, packaged with aluminum plastic film, baked, injected, placed, formed, jig shaped, sealed, and capacity tested to complete the preparation of the sodium-ion battery.

[0216] Examples 21-40 and Comparative Examples 10-15 are basically the same as Example 21, except that the choice of substances and the amount of some additives are different. It should be noted that the additives here include the compound shown in structural formula 1 (electrolyte additive) and / or auxiliary additive).

[0217] wherein:

[0218] Examples 21-32 and Comparative Examples 10, 11 investigate the effect of different amounts of the compound of structural formula 1 of the present disclosure, the same amount of the compound of structural formula 1 of the present disclosure without any additive, and only the auxiliary additive on the high-temperature storage performance of the sodium ion battery, as shown in Table 5.

[0219] Table 5: Part of the material and parameter selection, high-temperature storage performance of Examples 21-32 and Comparative Examples 10, 11

[0220] According to Table 5:

[0221] The test results of Examples 21-32 and Comparative Examples 10, 11 show that, compared with the sodium ion battery without any additive or with the existing additive, the sodium ion battery obtained by using the compound of structural formula 1 provided by the present disclosure as the additive has better high-temperature storage performance.

[0222] Examples 21, 33-40 and Comparative Examples 10, 11 investigate the effect of different amounts of the compound of structural formula 1 of the present disclosure, the same amount of the compound of structural formula 1 of the present disclosure with a specific amount of the electrolyte additive of the present disclosure combined with the auxiliary additive, without any additive, and only the auxiliary additive on the high-temperature storage performance of the sodium ion battery, as shown in Table 6.

[0223] Table 6: Part of the material and parameter selection, high-temperature storage performance of Examples 21, 33-40 and Comparative Examples 10, 11

[0224] According to Table 6:

[0225] The test results of Comparative Examples 21, 33-40 show that, as the amount of the compound 1 of structural formula 1 increases, the volume expansion rate and the internal resistance increase rate of the lithium ion battery first decrease and then increase, and the capacity retention rate first increases and then decreases, indicating that too much or too little additive amount can improve the high-temperature storage performance of the sodium ion battery and reduce the internal resistance increase, especially when the additive amount of the compound 1 of structural formula 1 is 0.5-5%, the sodium ion battery has the optimal impedance reduction and high-temperature storage performance.

[0226] The test results of Comparative Example 21 and Comparative Examples 10, 11 show that, compared with the traditional fluoroethylene carbonate (FEC), using the compound 1 of structural formula 1 provided by the present disclosure as the additive can more obviously improve the high-temperature performance of the sodium ion battery, indicating that the passivation film formed by the compound 1 of structural formula 1 has more excellent low impedance and sodium ion permeability.

[0227] The test results of Comparative Example 40 and Example 21 show that the compound 1 of structural formula 1 provided by the present disclosure and fluoroethylene carbonate (FEC) can further improve the high-temperature storage performance of the sodium ion battery when used in synergy.

[0228] Comparative Example 12 (intermediate ring containing carbonyl group in structural formula 1 replaced by non-cyclic structure containing carbonyl group)

[0229] This comparative example is substantially the same as Example 33, except that:

[0230] Compound 13 is used to replace compound 1 in the electrolyte.

[0231] Comparative Example 13 (intermediate ring containing carbonyl group in structural formula 2 replaced by non-cyclic structure not containing carbonyl group)

[0232] This comparative example is substantially the same as Example 21, except that:

[0233] Compound 14 is used to replace compound 1 in the electrolyte.

[0234] Comparative Example 14 (intermediate ring containing carbonyl group in structural formula 1 replaced by non-cyclic structure containing carbonyl group)

[0235] This comparative example is substantially the same as Example 33, except that:

[0236] Compound 13 is used to replace compound 1 in the electrolyte.

[0237] Comparative Example 15 (intermediate ring containing carbonyl group in structural formula 1 replaced by non-cyclic structure not containing carbonyl group)

[0238] This comparative example is substantially the same as Example 21, except that:

[0239] Compound 14 is used to replace compound 1 in the electrolyte.

[0240] The high-temperature cycle performance test results of the sodium ion batteries corresponding to Examples 21, 33 and Comparative Examples 10-15 are shown in Table 7.

[0241] Table 7. Selection of some substances and parameters, high-temperature storage performance of Examples 21, 33 and Comparative Examples 11-15

[0242] As can be seen from Table 7, from Examples 21 and Comparative Examples 10, 11, 13, 15, it can be seen that only the carbonyl structure has better high-temperature storage performance than the currently used additive, but not as good as compound 1. It is speculated that the cross-linked structure formed by the oxidation of the non-cyclic carbonyl group is not as stable as compound 1, and the non-cyclic structure without carbonyl group cannot form a cross-linked structure and the film strength is not as good as compound 1.

[0243] From Examples 33 and Comparative Examples 10, 12, 14, it can be seen that only the carbonyl structure, reducing the high-temperature storage performance of the additive is better than that of no additive, but is not as good as that of Compound 1, it is speculated that the crosslinking structure formed after the oxidation of the carbonyl group without a cyclic structure is not as stable as that of Compound 1, and the film strength without a carbonyl structure cannot form a crosslinking structure and is not as good as that of Compound 1.

[0244] In the present disclosure, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, all embodiments of the present disclosure can be performed independently, and those skilled in the art can combine and perform the different embodiments or examples described in the present specification and the features of the different embodiments or examples within the scope of the present disclosure without contradiction, and all of them are considered to be within the scope of protection required by the present disclosure.

[0245] Although the embodiments of the present disclosure have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present disclosure, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present disclosure.

Claims

1. An electrolyte additive comprising a compound having the structure shown in Formula 1: wherein X, Y are each independently selected from the group consisting of R is selected from an alkyl group or a halogenated alkyl group having 1 to 5 carbon atoms.

2. The electrolyte additive according to claim 1, wherein, The electrolyte additive includes at least one of Compound 1 to Compound 12:

3. An electrolyte solution comprising a non-aqueous organic solvent, an electrolyte salt, and an electrolyte solution additive according to any one of claims 1 to 2.

4. The electrolyte of claim 3, wherein, The compound having the structure shown in Formula 1 is present in the electrolyte solution in a mass content of 0.05 to 10%; and / or, the non-aqueous organic solvent comprises at least one of an ether solvent, a nitrile solvent, a carbonate solvent, a carboxylate solvent, and a sulfone solvent; and / or, the electrolyte salt comprises at least one of a lithium salt, a sodium salt, a potassium salt, a magnesium salt, a zinc salt, and an aluminum salt.

5. The electrolyte of claim 4, wherein, The compound having the structure shown in Formula 1 is present in the electrolyte solution in a mass content of 0.1 to 5%; and / or, the electrolyte salt is a lithium salt or a sodium salt; and / or the lithium salt comprises at least one of LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiClO4, LiAlCl4, LiCF3SO3, Li2B 10 Cl 10 , a lithium salt of a lower aliphatic carboxylic acid; and / or, the sodium salt comprises at least one of sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium bisfluorosulfonimide, sodium trifluoromethylsulfonate, and sodium bis-trifluoromethylsulfonimide.

6. The electrolyte of claim 5, wherein, The electrolyte salt is a lithium salt, and the concentration of the lithium salt in the electrolyte solution is 0.1 to 8 mol / L; or, the electrolyte salt is a sodium salt, and the concentration of the sodium salt in the electrolyte solution is 0.1 to 2 mol / L.

7. The electrolyte according to any one of claims 2 to 6, wherein, The auxiliary additive is selected from at least one of a cyclic carbonate compound, a cyclic sulfate compound, a sulfonic acid lactone compound, a phosphate compound, a borate compound, and a nitrile compound.

8. The electrolyte of claim 7, wherein, the cyclic carbonate compound is selected from at least one of vinylene carbonate, vinyl ethylene carbonate, methylene vinyl carbonate, fluoroethylene carbonate, trifluoromethyl ethylene carbonate, difluoroethylene carbonate, or a compound having a structure shown in Formula 2; In formula 2, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 are each independently selected from one of a hydrogen atom, a halogen atom, a C1-C5 group; And / or, the cyclic sulfate compound is selected from vinyl sulfate, 4-methylvinyl sulfate, propylene sulfate, etc. at least one of a cyclic carbonate compound, a cyclic sulfate compound, a sulfonic acid lactone compound, a phosphate compound, a borate compound, and a nitrile compound. and / or the sulfolane compound is selected from 1,3-propane sulfolane, 1,4-butane sulfolane, propenyl-1,3-sulfonic acid lactone, at least one of a cyclic carbonate compound, a cyclic sulfate compound, a sulfonic acid lactone compound, a phosphate compound, a borate compound, and a nitrile compound. and / or, the phosphate-based compound includes a saturated phosphate-based compound and an unsaturated phosphate-based compound, wherein the saturated phosphate-based compound includes tris(trimethylsilyl) phosphate, and the unsaturated phosphate-based compound includes a compound having a structure according to Formula 3: in formula 3, R 31 , R 32 , R 32 each independently is selected from a C1-C5 saturated hydrocarbon group, a C1-C5 unsaturated hydrocarbon group, a C1-C5 halogenated hydrocarbon group, or -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and at least one of the R 31 , the R 32 , the R 33 is an unsaturated hydrocarbon group; and / or, the borate compound comprises at least one of tris(trimethylsilyl) borate and tris(triethylsilyl) borate; and / or, the nitrile compound comprises at least one of butanedinitrile, pentanedinitrile, ethylene glycol bis(propionitrile) ether, hexanetristitnitrile, hexanedinitrile, heptanedinitrile, octanedinitrile, nonanedinitrile, and decanedinitrile.

9. A secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein The electrolyte solution is the electrolyte solution according to any one of claims 1 to 8.

10. The secondary battery according to claim 9, wherein The secondary battery is selected from a lithium metal battery, a lithium ion battery, a lithium-sulfur battery, a sodium ion battery, a magnesium ion battery, a potassium ion battery, a zinc ion battery, or an aluminum-lithium battery.

11. The secondary battery according to claim 9, wherein The secondary battery is a lithium ion battery, the positive active material of the secondary battery is selected from at least one of lithium-containing sulfides, lithium-containing selenides, lithium-containing halides, LiFe 1-x’ M' x’ PO4, LiMn 2-y’ M y’ O4and LiNi x Co y Mn z M 1- x-y-z O2, wherein M' is selected from at least one of Mn, Mg, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V or Ti, M is selected from at least one of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V or Ti, and 0 or, the secondary battery is a sodium ion battery, and the positive electrode active material is selected from at least one of a sodium-containing transition metal oxide, a sodium-containing Prussian material, a sodium-containing phosphate, a sodium-containing sulfate, and a sodium-containing titanate.

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