Electrolyte additive composition, non-aqueous electrolyte containing same and secondary battery

Abstract

The invention provides an electrolyte additive composition, a non-aqueous electrolyte containing the same, and a secondary battery. The electrolyte additive composition includes a first compound and a second compound. The non-aqueous electrolyte provided by the invention has good thermal stability and electrochemical stability at high temperature, not only can effectively improve the compatibility of an electrode interface and the electrolyte, but also can inhibit the volume of a negative electrode material from generating large change in the embedding and de-embedding processes of lithium ions; the irreversible capacity loss and the severe deterioration of the cycle performance in the charge-discharge process are improved, so that the technical effects of comprehensively improving the high-temperature storage performance of the battery and improving the high-temperature cycle performance are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolyte materials, and particularly relates to an electrolyte additive composition, a non-aqueous electrolyte containing the same, and a secondary battery. Background Art

[0002] Lithium-ion secondary batteries not only well meet the development requirements of rapidly changing electronic products, but also have a broader application prospect in high-end fields such as hybrid electric vehicles, military, and aerospace. With the vigorous development of lithium-ion secondary batteries, their development directions are mainly divided into the following three directions: one is to develop power batteries with large capacity and high power; the second is to improve the electrochemical performance and service life of small batteries; the third is to accelerate the development of polymer battery systems to achieve the thinning of batteries and improve the safety of batteries.

[0003] Based on the above development trends, the further development of lithium-ion secondary batteries is closely related to the in-depth research and application of materials. Among them, the anode material of lithium-ion batteries is one of the factors restricting its development, and thus becomes one of the research hotspots. Therefore, improving the electrochemical performance of carbon-based anode materials is one of the important means to develop high-energy density battery systems.

[0004] In the lithium-ion secondary battery system, on the one hand, although natural graphite materials have the advantages of high capacity, high tap density, and low price, due to the inconsistent particle size of themselves and many defects on the surface, the compatibility between natural graphite materials and electrolytes is poor, and more side reactions occur. On the other hand, the reaction activity on the outer surface of the particles of natural graphite powder is uneven, and the crystal grain size is relatively large. During the charge and discharge process, the crystal structure on its surface is easily damaged, so there is a problem that the SEI film (i.e., solid electrolyte interface film, which can allow lithium ions to pass through but not electrons) formed on the surface covers unevenly, resulting in a low initial Coulomb efficiency and poor rate performance of the battery.

[0005] To solve the above problems, researchers have adjusted the composition of the electrolyte to improve the electrical properties of natural graphite materials. For example, CN101667661A discloses an electrolyte matching the natural graphite anode of a lithium-ion secondary battery, which optimizes the physical and chemical properties of the SEI film of the natural graphite anode by adding boron element-containing compounds, making the overall battery have good electrochemical properties. However, the above electrolyte cannot have good thermal stability and electrochemical stability at high temperatures, resulting in poor high-temperature performance of the battery.

[0006] Therefore, in this field, it is urgent to develop an electrolyte system to solve the above problems. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an electrolyte additive composition, a non-aqueous electrolyte containing the same, and a secondary battery. The non-aqueous electrolyte provided by the present invention has good thermal stability and electrochemical stability at high temperatures. It can not only effectively improve the compatibility between the electrode interface and the electrolyte, but also inhibit large volume changes during the insertion and extraction of lithium ions in the natural graphite anode material, improving the irreversible capacity loss and severe deterioration of the cycle performance during charge and discharge, thereby achieving the technical effects of comprehensively improving the high-temperature storage performance of the battery and improving the high-temperature cycle performance.

[0008] To achieve the purpose of this invention, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides an electrolyte additive composition, which includes a first compound having the structure shown in Formula I and a second compound having the structure shown in Formula II;

[0010]

[0011] In the structure shown in Formula I, R1 and R2 are each independently selected from a substituted or unsubstituted alkyl group having 1-10 carbon atoms, a substituted or unsubstituted alkenyl group having 2-10 carbon atoms, a substituted or unsubstituted alkynyl group having 2-10 carbon atoms, a substituted or unsubstituted aryl group having 6-10 carbon atoms, a substituted or unsubstituted five-membered heterocyclic group having 2-10 carbon atoms, or a substituted or unsubstituted six-membered heterocyclic group having 2-10 carbon atoms,

[0012] The substituted group is selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or a silicon-containing group;

[0013] In the structure shown in Formula II, R3 is selected from a substituted or unsubstituted alkylene group having 1-10 carbon atoms, a substituted or unsubstituted alkenylene group having 2-10 carbon atoms, a substituted or unsubstituted alkynylene group having 2-10 carbon atoms, a substituted or unsubstituted arylene group having 6-10 carbon atoms, or a substituted or unsubstituted heteroarylene group having 2-10 carbon atoms,

[0014] The substituted group is selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or a silicon-containing group;

[0015] X1 and X2 are each independently selected from halogen atoms.

[0016] By regulating the composition of the electrolyte additive composition, the present invention uses a first phosphate compound with a chain structure and a second phosphate compound with a cyclic structure in combination, and there is a synergistic effect between the first phosphate compound with a chain structure and the second phosphate compound with a cyclic structure. The electrolyte containing the above electrolyte additive composition can not only stabilize the battery positive electrode interface, but also complex acidic substances such as PF5 and POF3 in the electrolyte, thereby improving the stability of the electrolyte. At the same time, it can participate in the construction of the battery positive and negative electrode interface films, forming a composite film containing phosphate, lithium halide (such as lithium fluoride, lithium chloride, lithium bromide or lithium iodide) and organic matter, so it has the advantages of stable film formation and low impedance, and the formed positive and negative electrode interface films inhibit the side reactions of the electrolyte on the electrode side, thereby reducing the degree of gas production and expansion, and improving the charge and discharge cycle life and high-temperature storage performance of the battery.

[0017] In the present invention, the range of the number of carbon atoms defined in R1, R2 and R3 above refers to any integer within the defined range. For example, when the number of carbon atoms is 1-10, the number of carbon atoms can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; when the number of carbon atoms is 2-10, the number of carbon atoms can be 2, 3, 4, 5, 6, 7, 8, 9 or 10; when the number of carbon atoms is 6-10, it means that the number of carbon atoms can be 6, 7, 8, 9 or 10.

[0018] In the present invention, X1 and X2 are each independently selected from halogen atoms, and can be any one of, for example, fluorine atom, chlorine atom, bromine atom or iodine atom.

[0019] The preparation method of the first compound of the structure shown in Formula I and the second compound of the structure shown in Formula II of the present invention includes the following steps: reacting phosphoryl halide and a hydroxy compound (including a mono-hydroxy compound or a di-hydroxy compound) in a first solvent (including n-pentane, n-hexane, dichloromethane, toluene, xylene or chlorobenzene, etc.) for 1-12 h, the mass percentage of water in the system during the reaction is less than 0.05%, the reaction temperature is -10-70 °C, the reaction pressure is 1-99 kPa, and the first solvent is removed under reduced pressure at a pressure of 0.1-1 kPa to obtain the product.

[0020] When the raw material is a monohydroxy compound, the resulting product is of structural formula I. The structural formula of the monohydroxy compound is R4-OH, where R4 is selected from substituted or unsubstituted alkyl groups with 1-10 carbon atoms, substituted or unsubstituted alkenyl groups with 2-10 carbon atoms, substituted or unsubstituted alkynyl groups with 2-10 carbon atoms, substituted or unsubstituted aryl groups with 6-10 carbon atoms, substituted or unsubstituted five-membered heterocyclic groups with 2-10 carbon atoms, or substituted or unsubstituted six-membered heterocyclic groups with 2-10 carbon atoms. The substituted groups are selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or silicon-containing groups.

[0021] When the raw material is a dihydroxy compound, the resulting product is of structural formula II. The structure of the dihydroxy compound is HO-R5-OH; where R5 is selected from substituted or unsubstituted alkylene groups with 1-10 carbon atoms, substituted or unsubstituted alkenylene groups with 2-10 carbon atoms, substituted or unsubstituted alkynylene groups with 2-10 carbon atoms, substituted or unsubstituted arylene groups with 6-10 carbon atoms, or substituted or unsubstituted heteroarylene groups with 2-10 carbon atoms. The substituted groups are selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or silicon-containing groups.

[0022] Preferably, in the structure shown by formula I, R1 and R2 are each independently selected from substituted or unsubstituted alkyl groups with 1-6 carbon atoms, substituted or unsubstituted alkenyl groups with 2-6 carbon atoms, substituted or unsubstituted alkynyl groups with 2-6 carbon atoms, substituted or unsubstituted phenyl groups, substituted or unsubstituted five-membered heterocyclic groups with 2-8 carbon atoms, or substituted or unsubstituted six-membered heterocyclic groups with 2-8 carbon atoms. The substituted groups are selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or silicon-containing groups.

[0023] Preferably, the silicon-containing group is an alkylsilyl group with 1-10 carbon atoms and / or an alkylsiloxy group with 1-10 carbon atoms, preferably an alkylsilyl group with 1-6 carbon atoms and / or an alkylsiloxy group with 1-6 carbon atoms.

[0024] In the present invention, the range of carbon atom numbers defined for the above silicon-containing groups refers to any integer within the defined range. For example, when the carbon atom number is 1-10, the carbon atom number can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0025] In one embodiment, in the structure represented by Formula I, R1 and R2 are each independently selected from, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, cyclopropyl, 1-methylcyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, vinyl, 2-propenyl, 3-butenyl, 2-butenyl, 2-(methyl)-2-propenyl, cyclopentenyl, 2-propynyl, 3-butynyl, 2-fluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl, 3-fluoropropyl, 3,3,3-trifluoropropyl, 2,2,3,3-tetrafluoropropyl, 2,2,3,3,3-pentafluoropropyl, 2,2-difluoropropyl, 1,1,1-trifluoroisopropyl, hexafluoroisopropyl, 4,4,4-trifluorobutyl, 3,3,4,4,4-pentafluorobutyl, 2,2,3,4,4,4-hexafluorobutyl, 2,2,3,3,4,4,4-heptafluorobutyl, 2-(cyano)ethyl, 2-(acetoxy)ethyl, acetylethyl, 3-(acetoxy)propyl, acetylpropyl, 4-(acetoxy)-2-butenyl, 4-(acetoxy)-2-butynyl, 2-(methanesulfonyloxy)ethyl, 2-(methanesulfonyl)ethyl, 3-(methanesulfonyloxy)propyl, 3-(methanesulfonyl)propyl, 4-(methanesulfonyloxy)-2-butenyl, 4-(methanesulfonyloxy)-2-butynyl, trimethylsilyl, (trimethylsilyl)methyl, (trimethylsilyl)ethyl, (trimethylsilyl)propyl, 2-(trimethylsiloxy)ethyl, 3-(trimethylsiloxy)propyl, 4-(trimethylsilyl)-2-butenyl, 4-(trimethylsilyl)-2-butynyl, phenyl, 2-fluorophenyl, 2,4-difluorophenyl, 2,6-difluorophenyl, 2,5-difluorophenyl, 2-(cyano)phenyl, 3-(cyano)phenyl, 4-(cyano)phenyl, 2-(acetyl)phenyl, 3-(acetyl)phenyl, 4-(acetyl)phenyl, 2-(acetoxy)phenyl, 3-(acetoxy)phenyl, 4-(acetoxy)phenyl, 2-(methanesulfonyloxy)phenyl, 3-(methanesulfonyloxy)phenyl, 4-(methanesulfonyloxy)phenyl, 2-(trimethylsiloxy)phenyl, 3-(trimethylsiloxy)phenyl or 4-(trimethylsiloxy)phenyl. These groups include their cis-trans isomers, R / S chiral isomers, isomers formed by different substitution positions on the carbon chain, and conformational isomers caused by the rotation of chemical bonds.

[0026] Preferably, in the structure represented by Formula II, R3 is selected from a substituted or unsubstituted alkylene group having 1-6 carbon atoms, a substituted or unsubstituted alkenylene group having 2-6 carbon atoms, a substituted or unsubstituted alkynylene group having 2-6 carbon atoms, a substituted or unsubstituted arylene group having 6-10 carbon atoms, or a substituted or unsubstituted heteroarylene group having 2-8 carbon atoms, wherein the substituted groups are selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl or a silicon-containing group.

[0027] Preferably, the silicon-containing group is an alkylsilyl group having 1 to 10 carbon atoms and / or an alkylsiloxy group having 1 to 10 carbon atoms, preferably an alkylsilyl group having 1 to 6 carbon atoms and / or an alkylsiloxy group having 1 to 6 carbon atoms.

[0028] In the present invention, the range of the number of carbon atoms defined in the above silicon-containing group refers to any integer within the defined range. For example, when the number of carbon atoms is 1 to 10, the number of carbon atoms can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0029] In one embodiment, R3 in the structure of formula II in the structure of formula I is exemplarily selected from methylene, 1,2-ethylene, 1,3-propylene, 1,2-propyl, 1,4-butylene, 1,3-butylene, 1,2-butylene, 2-methyl-1,3-propylene, 1,2-dimethyl-1,2-ethylene, 1,5-pentylene, 2,2-dimethyl-1,3-propylene, 2,4-pentylene, cyclopropylidene, 1-methylcyclopropylidene, 1,2-cyclobutylene, 1,2-cyclopentylene, 2-cyclopropyl-1,3-propylene, 1,2-cyclohexylene, 1,6-hexylene, 2,5-hexylene, 2,2-diethyl-1,3-propylene, 1,2-vinylidene, 1,2-propenylene, 2,3-propenylene, 1,4-2-butenylene, 3,4-1-butenylene, 2,5-3-hexenylene, 1,4-2-butynylene, 1-fluoro-1,2-ethylene, 1,2-difluoro-1,2-ethylene, 2-fluoro-1,3-propylene, 1,2-phenylene, 3-fluoro-1,2-phenylene, 4-fluoro-1,2-phenylene, 3,4,5,6-tetrafluoro-1,2-phenylene, 3-cyano-1,2-phenylene, 3-cyano-1,2-ethylene, 3-acetoxy-1,2-propylene, 3-methanesulfonyloxy-1,2-propylene, 3-fluorosulfonyloxy-1,2-propylene, 3-trimethylsiloxy-1,2-propylene.

[0030] Preferably, in the structure of formula I, R1 and R2 are each independently selected from a substituted alkyl group having 1 to 6 carbon atoms, a substituted alkenyl group having 2 to 6 carbon atoms, a substituted alkynyl group having 2 to 6 carbon atoms, a substituted phenyl group, a substituted five-membered heterocyclic group having 2 to 8 carbon atoms, or a substituted six-membered heterocyclic group having 2 to 8 carbon atoms, wherein the substituted group is selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or a silicon-containing group.

[0031] Preferably, the silicon-containing group is an alkylsilyl group having 1 to 10 carbon atoms and / or an alkylsiloxy group having 1 to 10 carbon atoms, preferably an alkylsilyl group having 1 to 4 carbon atoms and / or an alkylsiloxy group having 1 to 4 carbon atoms.

[0032] Preferably, in the structure shown in Formula II, R3 is selected from a substituted alkylene group having 1-4 carbon atoms, a substituted alkenylene group having 2-6 carbon atoms, a substituted alkynylene group having 2-6 carbon atoms, a substituted arylene group having 6-10 carbon atoms, or a substituted heteroarylene group having 2-8 carbon atoms, wherein the substituted group is selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or a silicon-containing group.

[0033] Preferably, the silicon-containing group is an alkylsilyl group having 1-10 carbon atoms and / or an alkylsiloxy group having 1-10 carbon atoms, preferably an alkylsilyl group having 1-4 carbon atoms and / or an alkylsiloxy group having 1-4 carbon atoms.

[0034] In the present invention, when the structures of R1, R2, and R3 in the above first compound and second compound contain substituents, it can further improve the comprehensive performance of the battery. For example, when the substituent is a carbonyl group, a sulfonyl group, or a silicon-containing group, it makes the second phosphate compound with a cyclic structure easier to form a film on the surfaces of the positive and negative electrodes, thereby enhancing the cycle performance of the battery; for example, the compound with a cyano group as the substituent can stabilize the positive electrode interface, complex the dissolved transition metal ions, reduce the catalytic dissolution and decomposition of the transition metal, and thus improve the gas generation problem during battery storage.

[0035] Preferably, the electrolyte additive composition further includes a film-forming additive.

[0036] In the present invention, the film-forming additive used is a commonly used film-forming additive in the art. It can not only inhibit the decomposition of the electrolyte, thereby protecting the positive and negative electrode materials, inhibiting gas generation, and reducing impedance, but also improve the high-temperature or low-temperature performance of the battery and enhance the storage stability of the electrolyte.

[0037] In addition, by adding the first compound, the second compound, and the film-forming additive to the electrolyte in the present invention, and utilizing the synergistic effect among the above-mentioned various additives, a stable electrolyte interface film can be further formed on the surfaces of the positive and negative electrodes, thereby stabilizing the interface between the electrode and the electrolyte, inhibiting the decomposition reaction of the electrolyte, reducing the interface impedance of the battery. In particular, it can form a dense passivation film in a high-temperature and high-pressure environment, greatly improving the interface compatibility of natural graphite materials in the electrolyte, effectively inhibiting the oxidation decomposition reaction of the electrolyte, and improving the large volume change of natural graphite materials during the insertion and extraction of lithium ions, thereby improving the high-temperature storage performance and cycle performance of lithium-ion batteries.

[0038] Preferably, the film-forming additive is selected from any one or a combination of at least two of vinylene carbonate, fluoroethylene carbonate, ethylene ethylene carbonate, 1,3-propane sultone, 1,4-butane sultone, 2,4-butane sultone, 1,3-propene sultone, methylene methanedisulfonate, ethylene sulfate, ethylene sulfite, butanedinitrile, adiponitrile, 1,3,6-hexanetricarbonitrile, 1,2,3-tris(2-cyanooxy)propane, ethylene glycol bis(propionitrile) ether, tris(trimethylsilyl) phosphate, tris(trimethylsilyl) borate or tetravinylsilane, preferably any one or a combination of at least two of vinylene carbonate, fluoroethylene carbonate or tetravinylsilane.

[0039] In a second aspect, the present invention provides a non-aqueous electrolyte, the non-aqueous electrolyte includes an additive, and the additive includes the electrolyte additive composition according to the first aspect.

[0040] Preferably, the non-aqueous electrolyte further includes a metal salt and an organic solvent.

[0041] Preferably, the metal salt is a lithium salt and / or a sodium salt.

[0042] Preferably, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the first compound having the structure shown in Formula I is 0.001-10 wt.%, preferably 0.1-5 wt.%, and can be, for example, 0.001 wt.%, 0.002 wt.%, 0.005 wt.%, 0.008 wt.%, 0.01%, 0.05%, 0.08%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 1 wt.%, 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 4 wt.%, 4.5 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, etc.

[0043] In the present invention, by regulating the mass percentage content of the first compound, the electrolyte maintains a small viscosity, improves the high-temperature performance of the battery while ensuring the normal-temperature and low-temperature performance. If the content is too low, it will be difficult to play a role, and conversely, the film will be too thick and the impedance will increase.

[0044] Preferably, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the second compound having the structure shown in Formula II is 0.001-10 wt.%, preferably 0.1-5 wt.%, and can be, for example, 0.001 wt.%, 0.002 wt.%, 0.005 wt.%, 0.008 wt.%, 0.01%, 0.05%, 0.08%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 1 wt.%, 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 4 wt.%, 4.5 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, etc.

[0045] In the present invention, by regulating the mass percentage content of the second compound, the electrolyte can maintain high ionic conductivity and form a stable protective film on the surfaces of the positive and negative electrodes. If the content is too low, it will be difficult to play a role, and conversely, it will increase the viscosity of the electrolyte, the film will be too thick, and the impedance will increase.

[0046] Preferably, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the film-forming additive is 0.001-10 wt.%, and can be, for example, 0.001 wt.%, 0.002 wt.%, 0.005 wt.%, 0.008 wt.%, 0.01%, 0.05%, 0.08%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 1 wt.%, 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 4 wt.%, 4.5 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, etc.

[0047] Preferably, the lithium salt includes any one or a combination of at least two of lithium hexafluorophosphate, lithium perchlorate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluorobis(oxalato)phosphate, lithium tris(oxalato)phosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, or lithium bis(fluorosulfonyl)imide.

[0048] In the present invention, there is a synergistic effect among various lithium salts, thus improving the thermal stability of lithium hexafluorophosphate. Among them, sulfonimide lithium salts have higher conductivity, higher electrochemical stability, thermal stability and hydrolysis resistance. The addition of boric acid lithium salts can not only inhibit the decomposition and corrosion of the electrolyte on the current collector aluminum foil, but also form a stable SEI film on the surfaces of the positive and negative electrodes. In addition, the combined lithium salts of phosphoric acid lithium salts and sulfonimide lithium salts can form a thinner and more uniform SEI film at the battery interface, thereby effectively reducing the interfacial impedance and reducing the damage of dendrites to the battery structure, thus enhancing the stability of the electrolyte.

[0049] Preferably, the sodium salt includes any one or a combination of at least two of sodium hexafluorophosphate, sodium perchlorate, sodium difluorophosphate, sodium difluorobis(oxalato)phosphate, sodium tetrafluoroxalate phosphate, sodium trioxalate phosphate, sodium bis(oxalato)borate, sodium difluoro(oxalato)borate, sodium tetrafluoroborate, sodium bis(trifluoromethanesulfonyl)imide or sodium bis(fluorosulfonyl)imide.

[0050] Preferably, the concentration of the metal salt in the non-aqueous electrolyte is 0.5 - 1.5 mol / L, and can be, for example, 0.5 mol / L, 0.6 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, etc.

[0051] Preferably, the organic solvent includes any one or a combination of at least two of ethylene carbonate, propylene carbonate, butylene carbonate, pentylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, methyl formate, ethyl formate, ethyl acetate, ethyl propionate, propyl propionate, butyl propionate, isobutyl propionate, pentyl propionate, isopentyl propionate, ethyl isopropylacetate, butyl n-butyrate, butyl isobutyrate, pentyl n-butyrate, isopentyl n-butyrate, ethyl n-butyrate, ethyl isobutyrate, ethyl valerate, propyl valerate, isopropyl isovalerate, ethyl isovalerate, γ-butyrolactone, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, 1,4-dioxane or tetrahydrofuran.

[0052] In the third aspect, the present invention provides a secondary battery, and the secondary battery includes the non-aqueous electrolyte according to the second aspect.

[0053] Preferably, the secondary battery further includes a positive electrode, a negative electrode and a separator.

[0054] Preferably, the negative electrode includes a natural graphite material.

[0055] In the present invention, the natural graphite material may be selected from any one or a combination of two of coated natural graphite or uncoated natural graphite materials.

[0056] The positive electrode of the present invention includes a positive electrode current collector and a positive electrode film attached to at least one surface of the positive electrode current collector. The raw materials of the positive electrode film include a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is selected from one or more of lithium nickel cobalt manganese oxide, lithium iron phosphate, or lithium iron manganese phosphate.

[0057] The negative electrode includes a negative electrode current collector and a negative electrode film attached to at least one surface of the negative electrode current collector. The raw materials of the negative electrode film include a negative electrode active material, a conductive agent, and a binder. In the present invention, there are no specific limitations on the positive electrode current collector, negative electrode current collector, conductive agent, binder, separator, etc., and they can be any type of material known in the existing lithium-ion battery or sodium-ion battery technology, as long as they are used to prepare a lithium-ion battery or sodium-ion battery with energy storage function. For example, the positive electrode current collector can be aluminum foil, the negative electrode current collector can be copper foil, and the separator can be a polyethylene (PE) microporous film, a polypropylene (PP) microporous film, etc.; the positive electrode, separator, and negative electrode can be assembled into a bare battery cell by known methods such as winding or stacking in the art, and then the electrolyte is injected to obtain a battery cell. After that, the battery cell is encapsulated, statically placed, formed, second-sealed, shaped, capacity tested, etc. according to the manufacturing process requirements of the battery cell to complete the preparation of the lithium-ion battery or sodium-ion battery.

[0058] The non-aqueous electrolyte provided by the present invention suppresses the volume expansion phenomenon of the natural graphite material during the insertion and extraction of lithium ions or sodium ions, improves the irreversible capacity loss and the severe deterioration of the cycle performance during the charge and discharge process of the battery, thereby achieving the effect of improving the high-temperature storage performance and high-temperature cycle performance of the natural graphite battery system.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] The present invention provides an electrolyte additive composition. The halogenated phosphate ester structure has a relatively high oxidation resistance potential, which can improve the overall oxidation resistance stability of the electrolyte. Moreover, the halogenated phosphate ester structure forms P and halogen atom free radicals that can scavenge the oxygen free radicals decomposing the electrolyte, inhibiting the gas generation during the circulation and storage of the electrolyte. The halogenated phosphate ester can complex with metals to protect the positive electrode, and form a stable and low-impedance composite protective film composed of phosphate, lithium halide and organic substances on reduction at the negative electrode, inhibiting the cracking of the negative electrode and the reduction decomposition of the electrolyte at the negative electrode, while ensuring the rapid transmission of metal ions. The first phosphate ester compound with a chain structure and the second phosphate ester compound with a cyclic structure cooperate to exert a synergistic effect, enabling the electrolyte to have a relatively high conductivity and a relatively low viscosity, while improving the high-temperature cycle and high-temperature storage of the battery, ensuring the performance of the battery at normal temperature and low temperature. By regulating the composition of the electrolyte additive composition, the balance between the protection of the positive and negative electrodes and the formation of a stable low-impedance film is achieved, comprehensively improving the high-temperature cycle and high-temperature storage performance of the battery. Detailed Embodiments

[0061] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0062] In the ranges disclosed in the present invention, the endpoints and any values of the ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0063] The present invention will be further described in detail below in conjunction with specific embodiments. The specific structural formula of the first compound in the following embodiments is:

[0064]

[0065] The specific structural formula of the second compound in the following embodiments is:

[0066]

[0067] Example 1

[0068] This example provides an electrolyte additive composition and its non-aqueous electrolyte. The preparation method of the non-aqueous electrolyte is as follows:

[0069] In a glove box filled with argon (water content < 1 ppm, oxygen content < 1 ppm), a lithium salt and non-aqueous solvent solution was prepared according to a mass ratio of ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) of 3:2:5, 0.5 mo / L lithium hexafluorophosphate (LiPF6), 0.5 mol / L lithium bis(fluorosulfonyl)imide (LiFSI), and 0.05 mol / L lithium difluoro(oxalato)borate (LiDFOB). Based on the total mass of the non-aqueous electrolyte being 100%, 0.5% of the I-2 first compound, 1% of the II-5 second compound, 1% of vinylene carbonate (VC), and 2% of fluoroethylene carbonate (FEC) were added and mixed evenly to obtain the non-aqueous electrolyte.

[0070] Example 2

[0071] This example provides an electrolyte additive composition and its non-aqueous electrolyte. The preparation method of the non-aqueous electrolyte is as follows:

[0072] In a glove box filled with argon (water content < 1 ppm, oxygen content < 1 ppm), a lithium salt and non-aqueous solvent solution was prepared according to a mass ratio of ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) of 3:2:5, 0.5 mo / L lithium hexafluorophosphate (LiPF6), 0.5 mol / L lithium bis(fluorosulfonyl)imide (LiFSI), and 0.05 mol / L lithium difluoro(oxalato)borate (LiDFOB). Based on the total mass of the non-aqueous electrolyte being 100%, 0.1% of the I-2 first compound, 0.1% of the II-5 second compound, 1% of vinylene carbonate (VC), and 2% of fluoroethylene carbonate (FEC) were added and mixed evenly to obtain the non-aqueous electrolyte.

[0073] Example 3

[0074] This example provides an electrolyte additive composition and its non-aqueous electrolyte. The preparation method of the non-aqueous electrolyte is as follows:

[0075] In a glove box filled with argon (water content < 1 ppm, oxygen content < 1 ppm), a lithium salt and non-aqueous solvent solution was prepared according to a mass ratio of ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) of 3:2:5, 0.5 mo / L lithium hexafluorophosphate (LiPF6), 0.5 mol / L lithium bis(fluorosulfonyl)imide (LiFSI), and 0.05 mol / L lithium difluoro(oxalato)borate (LiDFOB). Based on the total mass of the non-aqueous electrolyte being 100%, 5% of the I-2 first compound, 5% of the II-5 second compound, 1% of vinylene carbonate (VC), and 2% of fluoroethylene carbonate (FEC) were added and mixed evenly to obtain the non-aqueous electrolyte.

[0076] Example 4

[0077] The difference between this example and Example 1 is that the first compound is replaced with an I-1 substituted first compound of equal content, and the others are the same as in Example 1.

[0078] Example 5

[0079] The difference between this example and Example 1 is that the second compound is replaced with a II-3 substituted second compound of equal content, and the others are the same as in Example 1.

[0080] Example 6

[0081] The difference between this example and Example 1 is that the first compound is replaced with an I-3 compound of equal content, and the others are the same as in Example 1.

[0082] Example 7

[0083] The difference between this example and Example 1 is that the second compound is replaced with a II-1 compound of equal content, and the others are the same as in Example 1.

[0084] Example 8

[0085] The difference between this example and Example 1 is that the second compound is replaced with a II-2 compound of equal content, and the others are the same as in Example 1.

[0086] Example 9

[0087] The difference between this example and Example 1 is that the film-forming additives vinylene carbonate and fluoroethylene carbonate are not used, and the content of the non-aqueous solvent is adaptively adjusted so that the total mass percentage of the total system is 100%, and the others are the same as in Example 1.

[0088] Example 10

[0089] The difference between this example and Example 1 is that both lithium difluoro(oxalato)borate and lithium bis(fluorosulfonyl)imide are replaced with lithium hexafluorophosphate of equal content, and the others are the same as in Example 1.

[0090] Example 11

[0091] The difference between this example and Example 1 is that based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage of the first compound is 0.001 wt.%, and the content of the organic solvent is adaptively adjusted so that the total mass percentage of the non-aqueous electrolyte is 100%, and the others are the same as in Example 1.

[0092] Example 12

[0093] The difference between this embodiment and Embodiment 1 is that, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the first compound is 0.05 wt.%, and the content of the organic solvent is adaptively adjusted so that the total mass percentage content of the non-aqueous electrolyte is 100%, and the others are the same as in Embodiment 1.

[0094] Embodiment 13

[0095] The difference between this embodiment and Embodiment 1 is that, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the first compound is 3 wt.%, and the content of the organic solvent is adaptively adjusted so that the total mass percentage content of the non-aqueous electrolyte is 100%, and the others are the same as in Embodiment 1.

[0096] Embodiment 14

[0097] The difference between this embodiment and Embodiment 1 is that, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the first compound is 10 wt.%, and the content of the organic solvent is adaptively adjusted so that the total mass percentage content of the non-aqueous electrolyte is 100%, and the others are the same as in Embodiment 1.

[0098] Embodiment 15

[0099] The difference between this embodiment and Embodiment 1 is that, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the second compound is 0.001 wt.%, and the content of the organic solvent is adaptively adjusted so that the total mass percentage content of the non-aqueous electrolyte is 100%, and the others are the same as in Embodiment 1.

[0100] Embodiment 16

[0101] The difference between this embodiment and Embodiment 1 is that, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the second compound is 0.05 wt.%, and the content of the organic solvent is adaptively adjusted so that the total mass percentage content of the non-aqueous electrolyte is 100%, and the others are the same as in Embodiment 1.

[0102] Embodiment 17

[0103] The difference between this embodiment and Embodiment 1 is that, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the second compound is 3 wt.%, and the content of the organic solvent is adaptively adjusted so that the total mass percentage content of the non-aqueous electrolyte is 100%, and the others are the same as in Embodiment 1.

[0104] Embodiment 18

[0105] The difference between this example and Example 1 is that, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage of the second compound is 10 wt.%, and the content of the organic solvent is adaptively adjusted so that the total mass percentage of the non-aqueous electrolyte is 100%, and the others are the same as in Example 1.

[0106] Example 19

[0107] The difference between this example and Example 1 is that the first compound is replaced with an equal content of I-4, and the second compound is replaced with an equal content of II-4 compound, and the others are the same as in Example 1.

[0108] Example 20

[0109] The difference between this example and Example 1 is that the first compound is replaced with an equal content of I-5, and the second compound is replaced with an equal content of II-4 compound, and the others are the same as in Example 1.

[0110] Comparative Example 1

[0111] The difference between this comparative example and Example 1 is that the first compound is replaced with an equal content of the second compound, and the others are the same as in Example 1.

[0112] Comparative Example 2

[0113] The difference between this comparative example and Example 1 is that the second compound is replaced with an equal content of the first compound, and the others are the same as in Example 1.

[0114] Comparative Example 3

[0115] The difference between this comparative example and Example 1 is that the first and second compounds are replaced with an equal content of Compound A, and the structural formula is shown below, and the others are the same as in Example 1:

[0116]

[0117] Comparative Example 4

[0118] The difference between this comparative example and Example 1 is that the first and second compounds are replaced with an equal content of Compound B, and the structural formula is shown below, and the others are the same as in Example 1:

[0119]

[0120] The specific electrolyte compositions of the above Examples 1 to 20 and Comparative Examples 1 to 4 are shown in Table 1.

[0121] Table 1

[0122]

[0123]

[0124]

[0125] Application Examples 1 - 20 and Comparative Application Examples 1 - 4

[0126] Lithium - ion batteries were prepared from the non - aqueous electrolytes provided in Examples 1 - 20 and Comparative Examples 1 - 4. The preparation method is as follows:

[0127] The positive electrode active material LiCo 0.8 Ni 0.1 Mn 0.1 O4 (high - nickel ternary cathode material), conductive agents CNTs, Super P, and binder PVDF were added to N - methylpyrrolidone solvent (NMP) according to the mass ratio of active material:conductive agent:binder of 95:1.5:1:2.5, and mechanically stirred for 3 h to form a stable slurry. Then the slurry was evenly coated on a metal aluminum foil, vacuum - dried at 80 °C for 2 h, and roll - pressed at a compaction density of 2.35 g / cm 3 Finally, it was die - cut into a specified size to obtain the positive electrode sheet.

[0128] Using natural graphite (uncoated) as the negative electrode active material, conductive agent Super P, thickener CMC, and binder SBR, according to the mass ratio of active material:conductive agent:thickener:binder of 96.7:1:0.5:1.8, added to deionized water as the solvent, mechanically stirred for 3 h to form a stable slurry. Then the slurry was evenly coated on a metal copper foil, vacuum - dried at 80 °C for 2 h, the electrode sheet was dried, and roll - pressed at a compaction density of 1.55 g / cm 3 Finally, it was die - cut into a specified size to obtain the negative electrode sheet.

[0129] Using a PP / PE composite film as the separator, according to the N / P ratio of 1.12, the above - mentioned positive electrode sheet, separator, and negative electrode sheet were stacked in sequence into a winding machine, with the separator placed between the positive electrode sheet and the negative electrode sheet, and a bare battery cell was wound. The bare battery cell was placed in an aluminum - plastic film package and then baked in a vacuum oven to ensure that the moisture content of the electrode sheets in the battery cell did not exceed 200 ppm. Then, the above non - aqueous electrolyte was injected into the battery cell in a vacuum glove box to obtain a battery cell with a capacity of 1200 mAh. After that, the battery cell was encapsulated, static - placed, formed, second - sealed, shaped, and capacity - tested according to the requirements of the battery cell process to complete the preparation of the lithium - ion battery.

[0130] Test Conditions

[0131] The lithium - ion batteries prepared in Application Examples 1 - 20 and Comparative Application Examples 1 - 4 were tested for their electrochemical performance. The test method is as follows:

[0132] High-temperature storage performance for 28 days:

[0133] Temperature: 60°C ± 2°C; Relative humidity: ≤75%; Atmospheric pressure: 86 kPa to 106 kPa. The test is carried out in the following three steps:

[0134] (1) After formation, the battery is charged at a constant current of 0.33C and constant voltage until the limiting voltage reaches 4.2V at room temperature of 25°C. Charging ends when the cut-off current drops to 0.02C. After a 5-minute rest, it is discharged at a constant current until the cut-off voltage of 3.0V is reached. Record the discharge capacity, and measure and record the battery voltage, internal resistance, and thickness. Take this discharge capacity as the initial capacity C1, and rest for 5 minutes;

[0135] (2) Charge at a constant current of 0.33C and constant voltage until the limiting voltage reaches 4.2V. Charging ends when the cut-off current drops to 0.02C. Measure the volume V0 of the battery before high-temperature storage using the water displacement method. After the battery is left open at 60 ± 2°C for 28 days, take out the battery, rest at room temperature for 5 hours, and measure and record the battery voltage, internal resistance, thickness, and the volume V1 after storage;

[0136] (3) At room temperature of 25°C, discharge at a constant current of 0.33C until the cut-off voltage of 3.0V is reached. Rest for 5 minutes and record the discharge capacity C2;

[0137] Then charge at a constant current of 0.33C and constant voltage until the limiting voltage reaches 4.2V. Charging ends when the cut-off current drops to 0.02C. Discharge at a constant current of 0.33C until the cut-off voltage of 3.0V is reached. Rest for 5 minutes between charge and discharge. After 2 cycles, the test ends, and record the highest discharge capacity C3.

[0138] Capacity retention rate = C2 / C1; Capacity recovery rate = C3 / C1;

[0139] Volume change rate (%) = (V1 – V0) / V0 × 100%.

[0140] High-temperature cycling performance:

[0141] Temperature: 45°C ± 1°C, Relative humidity: ≤75%, Atmospheric pressure: 86 kPa to 106 kPa. After formation, the battery is charged at a constant current of 0.5C and constant voltage to 4.2V with a cut-off current of 0.02C, and then discharged at a constant current of 1C to 3.0V. Rest for 5 minutes between charge and discharge, and cycle 800 times accordingly.

[0142] The test results are shown in Table 1:

[0143] Table 1

[0144]

[0145]

[0146] As can be seen from Table 1, in the present invention, by adding a first compound, a second compound and a film-forming additive with specific structures and contents to the electrolyte and combining them, the synergistic effect among the above-mentioned various additives is utilized to improve the high-temperature storage and high-temperature cycling performance of the natural graphite battery system.

[0147] Among them, by comparing Examples 1-3 with Examples 4-8, it is shown that when the structures of R1, R2 and R3 in the first compound and the second compound contain substituents, the comprehensive performance of the battery can be further improved.

[0148] By comparing Example 1 with Example 9, it can be known that there is a synergistic effect between the film-forming additive and the first compound and the second compound. It can not only inhibit the decomposition of the electrolyte, thereby protecting the positive and negative electrode materials, thus inhibiting gas generation and reducing impedance, but also improve the high-temperature or low-temperature performance of the battery and improve the storage stability performance of the electrolyte.

[0149] By comparing Example 1 with Example 10, it can be known that the use of pure lithium hexafluorophosphate results in poor thermal stability of the electrolyte and poor film-forming property of the SEI film, and thus the performance of the battery deteriorates.

[0150] By comparing Example 1 with Examples 11-14, it is shown that the optimal content range of the first compound is 0.1-5 wt.%. Similarly, by comparing Example 1 with Examples 15-18, the optimal content range of the second compound is 0.1-5 wt.%.

[0151] By comparing Example 1 with Comparative Examples 1-2, it can be known that a single first compound or second compound cannot achieve all the technical effects.

[0152] By comparing Example 1 with Comparative Examples 3-4, it can be known that the electrolyte prepared with the additives disclosed in the prior art has serious gas generation phenomenon.

[0153] The applicant declares that the present invention uses the above-mentioned examples to illustrate the process method of the present invention, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the raw materials selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. An electrolyte additive composition, characterized in that, The electrolyte additive composition includes a first compound having the structure shown in Formula I and a second compound having the structure shown in Formula II; In the structure shown in Formula I, R1 and R2 are each independently selected from a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted five-membered heterocyclic group having 2 to 10 carbon atoms, or a substituted or unsubstituted six-membered heterocyclic group having 2 to 10 carbon atoms, The substituted group is selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or a silicon-containing group; In the structure shown in Formula II, R3 is selected from a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 10 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 10 carbon atoms, or a substituted or unsubstituted heteroarylene group having 2 to 10 carbon atoms, The substituted group is selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or a silicon-containing group; X1 and X2 are each independently selected from halogen atoms.

2. The electrolyte additive composition according to claim 1, wherein In the structure shown in Formula I, R1 and R2 are each independently selected from a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 6 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted five-membered heterocyclic group having 2 to 8 carbon atoms, or a substituted or unsubstituted six-membered heterocyclic group having 2 to 8 carbon atoms. The substituted group is selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or a silicon-containing group; Preferably, the silicon-containing group is an alkylsilyl group having 1 to 10 carbon atoms and / or an alkylsiloxy group having 1 to 10 carbon atoms, preferably an alkylsilyl group having 1 to 6 carbon atoms and / or an alkylsiloxy group having 1 to 6 carbon atoms; Preferably, in the structure shown in Formula II, R3 is selected from a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 6 carbon atoms, a substituted or unsubstituted alkynylene group having 2 to 6 carbon atoms, a substituted or unsubstituted arylene group having 6 to 10 carbon atoms, or a substituted or unsubstituted heteroarylene group having 2 to 8 carbon atoms. The substituted group is selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or a silicon-containing group; Preferably, the silicon-containing group is an alkylsilyl group having 1 to 10 carbon atoms and / or an alkylsiloxy group having 1 to 10 carbon atoms, preferably an alkylsilyl group having 1 to 6 carbon atoms and / or an alkylsiloxy group having 1 to 6 carbon atoms.

3. The electrolyte additive composition according to claim 2, characterized in that, In the structure shown by formula I, R1 and R2 are each independently selected from a substituted alkyl group having 1 to 6 carbon atoms, a substituted alkenyl group having 2 to 6 carbon atoms, a substituted alkynyl group having 2 to 6 carbon atoms, a substituted phenyl group, a substituted five-membered heterocyclic group having 2 to 8 carbon atoms, or a substituted six-membered heterocyclic group having 2 to 8 carbon atoms. The substituted group is selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or a silicon-containing group. Preferably, the silicon-containing group is an alkylsilyl group having 1 to 10 carbon atoms and / or an alkylsiloxy group having 1 to 10 carbon atoms, preferably an alkylsilyl group having 1 to 4 carbon atoms and / or an alkylsiloxy group having 1 to 4 carbon atoms. Preferably, in the structure shown by formula II, R3 is selected from a substituted alkylene group having 1 to 4 carbon atoms, a substituted alkenylene group having 2 to 6 carbon atoms, a substituted alkynylene group having 2 to 6 carbon atoms, a substituted arylene group having 6 to 10 carbon atoms, or a substituted heteroarylene group having 2 to 8 carbon atoms. The substituted group is selected from any one or a combination of at least two of halogen, cyano, sulfonyl, carbonyl, or a silicon-containing group. Preferably, the silicon-containing group is an alkylsilyl group having 1 to 10 carbon atoms and / or an alkylsiloxy group having 1 to 10 carbon atoms, preferably an alkylsilyl group having 1 to 4 carbon atoms and / or an alkylsiloxy group having 1 to 4 carbon atoms.

4. The electrolyte additive composition according to any one of claims 1-3, characterized in that The electrolyte additive composition further includes a film-forming additive. Preferably, the film-forming additive is selected from any one or a combination of at least two of vinylene carbonate, fluoroethylene carbonate, ethylene carbonate ethyl ester, 1,3-propane sultone, 1,4-butane sultone, 2,4-butane sultone, 1,3-propene sultone, methylene methanedisulfonate, ethylene sulfate, ethylene sulfite, succinonitrile, adiponitrile, 1,3,6-hexanetricarbonitrile, 1,2,3-tris(2-cyanoethoxy)propane, ethylene glycol bis(propionitrile) ether, tris(trimethylsilyl) phosphate, tris(trimethylsilyl) borate, or tetravinylsilane, preferably any one or a combination of at least two of vinylene carbonate, fluoroethylene carbonate, or tetravinylsilane.

5. A non-aqueous electrolyte, characterized in that, The non-aqueous electrolyte includes an additive, and the additive includes the electrolyte additive composition according to any one of claims 1 to 4.

6. The non-aqueous electrolyte according to claim 5, characterized in that, The non-aqueous electrolyte further includes a metal salt and an organic solvent. Preferably, the metal salt is a lithium salt and / or a sodium salt. Preferably, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the first compound having the structure shown by formula I is 0.001 to 10 wt.%, preferably 0.1 to 5 wt.%. Preferably, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the second compound having the structure shown by formula II is 0.001 to 10 wt.%, preferably 0.1 to 5 wt.%. Preferably, based on the total mass of the non-aqueous electrolyte being 100%, the mass percentage content of the film-forming additive is 0.001 to 10 wt.%.

7. The non-aqueous electrolyte according to claim 5 or 6, characterized in that, The lithium salt includes any one or a combination of at least two of lithium hexafluorophosphate, lithium perchlorate, lithium difluorophosphate, lithium difluoro(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, lithium trioxalato phosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, or lithium bis(fluorosulfonyl)imide; Preferably, the sodium salt includes any one or a combination of at least two of sodium hexafluorophosphate, sodium perchlorate, sodium difluorophosphate, sodium difluoro(oxalato)phosphate, sodium tetrafluoro(oxalato)phosphate, sodium trioxalato phosphate, sodium bis(oxalato)borate, sodium difluoro(oxalato)borate, sodium tetrafluoroborate, sodium bis(trifluoromethanesulfonyl)imide, or sodium bis(fluorosulfonyl)imide; Preferably, the concentration of the metal salt in the non-aqueous electrolyte is 0.5 to 1.5 mol / L.

8. The non-aqueous electrolyte according to any one of claims 5 to 7, characterized in that, The organic solvent includes any one or a combination of at least two of ethylene carbonate, propylene carbonate, butylene carbonate, pentylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, methyl formate, ethyl formate, ethyl acetate, ethyl propionate, propyl propionate, butyl propionate, isobutyl propionate, pentyl propionate, isopentyl propionate, ethyl isopropylacetate, butyl n-butyrate, butyl isobutyrate, pentyl n-butyrate, isopentyl n-butyrate, ethyl n-butyrate, ethyl isobutyrate, ethyl valerate, propyl valerate, isopropyl valerate, ethyl isovalerate, γ-butyrolactone, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, 1,4-dioxane, or tetrahydrofuran.

9. A secondary battery, characterized in that, The secondary battery includes the non-aqueous electrolyte according to any one of claims 5-8.

10. The secondary battery according to claim 9, characterized in that, The secondary battery further includes a positive electrode, a negative electrode, and a separator; Preferably, the negative electrode includes a natural graphite material.

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