Electrolyte additive, electrolyte and secondary battery

Abstract

An electrolyte additive, an electrolyte and a secondary battery. The electrolyte additive comprises a first component and a second component, wherein the first component is selected from a compound represented by formula I, and the second component is selected from a compound represented by formula II. The synergistic effect of the first component and the second component in the electrolyte additive can improve the high-temperature storage performance and cycle life of secondary batteries.

Description

Electrolyte additive, electrolyte and secondary battery

[0001] This application claims priority to the Chinese patent application No. 202411105029.6, filed on August 13, 2024, and entitled "Electrolyte additive, electrolyte and secondary battery", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of electrochemistry, in particular to an electrolyte additive, an electrolyte and a secondary battery. BACKGROUND

[0003] Lithium ion batteries are widely used in electronic products, electric vehicles and other fields due to their high voltage, large capacity, no memory effect and long service life. Despite the many advantages of lithium ion batteries, the low energy density and performance decline when working in high temperature environment have always plagued the development of lithium ion batteries. Increasing the working voltage of lithium ion batteries is an effective method to improve the energy density of the battery, but at the same time, it tends to accelerate the decomposition of the electrolyte and exacerbate the occurrence of side reactions, thereby affecting the service life and cycle performance of the lithium ion battery. Therefore, it is an urgent technical problem for those skilled in the art to develop a suitable electrolyte. SUMMARY

[0004] The purpose of the present application is to provide an electrolyte additive, an electrolyte and a secondary battery to improve the high-temperature storage performance and cycle life of the secondary battery. The specific technical solutions are as follows:

[0005] [According to Rule 26 Correction 03.03.2026] The first aspect of the present application provides an electrolyte additive comprising a first component and a second component;

[0006] [According to Rule 26 Correction 03.03.2026] The first component is selected from the compound shown in Formula I;

[0007] [According to Rule 26 Correction 03.03.2026] The second component is selected from the compound shown in Formula II;

[0008] wherein R1 is selected from halogen, C1-C6 alkyl unsubstituted or substituted with halogen;

[0009] R2 is selected from nitrogen or C6-C 12 arylene;

[0010] R3 or R4 is each independently selected from hydrogen, halogen, C1-C6 alkyl unsubstituted or substituted with R asubstituted C6-C a substituted C6-C 12 substituted C6-C a substituted C6-C a each independently selected from halogen, unsubstituted or halogen-substituted C1-C6 alkyl, C6-C 12 substituted C6-C substituted C6-C b or R c each independently selected from unsubstituted or halogen-substituted C1-C6 alkyl;

[0011] R6is selected from hydrogen, unsubstituted or halogen-substituted C1-C6 alkyl, unsubstituted or halogen-substituted C2-C6 alkenyl, unsubstituted or halogen-substituted C2-C6 alkynyl, cyano, unsubstituted or halogen-substituted C6-C 12 aryl;

[0012] R5is selected from

[0013] R d or R e each independently selected from hydrogen, unsubstituted or halogen-substituted C1-C6 alkyl, unsubstituted or halogen-substituted C2-C6 alkenyl, unsubstituted or halogen-substituted C2-C6 alkynyl, cyano, unsubstituted or halogen-substituted C6-C 12 aryl;

[0014] R f is selected from unsubstituted or halogen-substituted C1-C6 alkyl, unsubstituted or halogen-substituted C2-C6 alkenyl, unsubstituted or halogen-substituted C2-C6 alkynyl; n is 0, 1, 2, 3, 4 or 5.

[0015] In one embodiment of the present application, the mass ratio of the first component and the second component is (0.05-20):1, preferably (0.5-3):1.

[0016] In one embodiment of the present application, R1is selected from fluorine, unsubstituted or fluorine-substituted C1-C4 alkyl;

[0017] R2is selected from nitrogen or phenylene;

[0018] R3or R4are each independently selected from hydrogen, fluorine, unsubstituted or R a substituted C1-C4 alkyl, unsubstituted or R a substituted phenyl, unsubstituted or R a substituted sulfonyl; substituent R aeach independently selected from the group consisting of fluorine, unsubstituted or fluorine-substituted C1-C4 alkyl, phenyl, C1-C2 alkoxy, C2-C4 alkenyl, cyano, substituents R b or R c each independently selected from the group consisting of unsubstituted or fluorine-substituted C1-C4 alkyl;

[0019] R6is selected from the group consisting of hydrogen, unsubstituted or fluorine-substituted C1-C4 alkyl, unsubstituted or fluorine-substituted C2-C4 alkenyl, unsubstituted or fluorine-substituted C2-C4 alkynyl, cyano, unsubstituted or fluorine-substituted phenyl;

[0020] R d or R e each independently selected from the group consisting of hydrogen, unsubstituted or fluorine-substituted C1-C4 alkyl, unsubstituted or fluorine-substituted C2-C4 alkenyl, unsubstituted or fluorine-substituted C2-C4 alkynyl, cyano, unsubstituted or fluorine-substituted phenyl;

[0021] R f is selected from the group consisting of C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl; n is 0, 1, 2 or 3.

[0022] [Amended according to Rule 26 03.03.2026] In an embodiment of the present application, the first component is selected from at least one of the following compounds;

[0023] [Amended according to Rule 26 03.03.2026] In an embodiment of the present application, the second component is selected from at least one of the following compounds;

[0024] In an embodiment of the present application, the electrolyte additive further comprises a third component selected from at least one of vinylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, ethylene sulfate, 1,3-propane sultone, 1,3-propene sultone, ethylene sulfite, tris(trimethylsilyl)borate, lithium bisoxalato borate, lithium difluoro oxalato borate and lithium difluoro dioxalato phosphate.

[0025] In an embodiment of the present application, the mass ratio of the second component and the third component is (0.01-1.5):1, preferably (0.1-0.5):1.

[0026] The second aspect of the present application provides an electrolyte comprising the electrolyte additive of the first aspect of the present application; the mass percentage of the electrolyte additive in the electrolyte is 1% to 15%, preferably 3% to 8%, based on the mass of the electrolyte.

[0027] In an embodiment of the present application, at least one of the following features is satisfied:

[0028] (1) the mass percentage of the first component is A based on the mass of the electrolyte, 0.1%≤A≤2%, preferably 0.5%≤A≤1.5%;

[0029] (2) the mass percentage of the second component is B based on the mass of the electrolyte, 0.1%≤B≤1.5%, preferably 0.5%≤B≤1%;

[0030] (3) the mass percentage of the third component is C based on the mass of the electrolyte, 1%≤C≤10%, preferably 3%≤C≤5%.

[0031] The third aspect of the present application provides a secondary battery, comprising a positive electrode sheet, a negative electrode sheet, a separator and the electrolyte of the second aspect of the present application; wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode material layer arranged on at least one surface of the negative electrode current collector, the negative electrode material layer comprises a negative electrode active material selected from at least one of a silicon-based material, a carbon-based material and a lithium-containing metal composite oxide; the positive electrode sheet comprises a positive electrode current collector and a positive electrode material layer arranged on at least one surface of the positive electrode current collector, the positive electrode material layer comprises a positive electrode active material selected from at least one of lithium manganate, lithium nickel cobalt manganate ternary material, lithium nickel manganate, lithium-rich manganese-based material and lithium cobaltate.

[0032] The beneficial effects of the present application are:

[0033] The present application provides an electrolyte additive, an electrolyte and a secondary battery. The electrolyte additive of the present application comprises a first component and a second component. When applied to an electrolyte, the first component alone generates a large amount of lithium-containing inorganic components (including lithium fluoride, lithium sulfate, etc.), which improves the high-temperature stability of the solid electrolyte interface film, but also increases the impedance of the solid electrolyte interface film. However, the addition of the second component in the electrolyte additive can eliminate part of the lithium-containing inorganic components, and the silicon-oxygen component in the second component can replace the negative effects of the reduced stability caused by the reduction of lithium-containing inorganic components, thereby improving the high-temperature storage performance and cycle life of the secondary battery without affecting the stability of the solid electrolyte interface film. In addition, the second component can also eliminate by-products in the electrolyte and reduce the gas production problem caused by the first component. The electrolyte additive of the present application comprises the first component and the second component, and the synergistic effect of the first component and the second component can improve the high-temperature storage performance and cycle life of the secondary battery.

[0034] Preferably, the electrolyte additive of this application may further include a third component. The third component can generate a flexible solid electrolyte interface film with good compatibility with the lithium-containing inorganic components formed by the first component. While improving the flexibility of the solid electrolyte interface film, it also improves its stability (the third component generates a flexible solid electrolyte interface film, and the large amount of lithium-containing inorganic components generated by the first component can serve as a framework to improve stability), thus better isolating side reactions at the battery interface. Simultaneously, the second component can eliminate some of the lithium-containing inorganic components, and the silicon-oxygen components in the second component can replace the negative effect of reduced stability caused by the reduction of lithium-containing inorganic components. Therefore, without affecting the stability of the solid electrolyte interface film, it reduces impedance and provides lithium-ion channels to accelerate lithium-ion transport. Preferably, the electrolyte additive of this application simultaneously includes the first, second, and third components. The synergistic effect of the first, second, and third components can better improve the high-temperature storage performance and cycle life of the secondary battery.

[0035] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Detailed Implementation

[0036] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0037] [Amended according to Rule 26 03.03.2026] The first aspect of this application provides an electrolyte additive, which includes a first component and a second component;

[0038] [Amended according to Rule 26 03.03.2026] The first component is selected from the compounds represented by Formula I;

[0039] [Amended according to Rule 26 03.03.2026] The second component is selected from the compounds shown in Formula II;

[0040] R1 is selected from halogens, unsubstituted or halogen-substituted C1-C6 alkyl groups;

[0041] R2 is selected from nitrogen or C6-C. 12 Alpha-aryl;

[0042] R3 or R4 are each independently selected from hydrogen, halogen, unsubstituted or R-substituted. a Substituted C1-C6 alkyl, unsubstituted or R a Replacement C6-C12 aryl, unsubstituted or R a Substituted sulfonyl group; substituent R a Each is independently selected from halogens, unsubstituted or halogenated C1-C6 alkyl groups, C6-C 12 Aryl, C1-C2 alkoxy, C2-C6 alkenyl, cyano Substituent R b Or R c Each is independently selected from unsubstituted or halogen-substituted C1-C6 alkyl groups;

[0043] R6 is selected from hydrogen, unsubstituted or halogenated C1-C6 alkyl, unsubstituted or halogenated C2-C6 alkenyl, unsubstituted or halogenated C2-C6 alkynyl, cyano, unsubstituted or halogenated C6-C 12 Aryl;

[0044] R5 is selected from

[0045] R d Or R e Each is independently selected from hydrogen, unsubstituted or halogenated C1-C6 alkyl, unsubstituted or halogenated C2-C6 alkenyl, unsubstituted or halogenated C2-C6 alkynyl, cyano, unsubstituted or halogenated C6-C 12 Aryl;

[0046] R f Selected from unsubstituted or halogenated C1-C6 alkyl, unsubstituted or halogenated C2-C6 alkenyl, unsubstituted or halogenated C2-C6 alkynyl; n is 0, 1, 2, 3, 4 or 5.

[0047] The first component of the present application is a sulfonyl additive, the S-C bond or S-N bond in the additive is easy to break, generating lithium-containing inorganic components (including LiF and Li2SO4 components) that are beneficial to improve the solid electrolyte interface film. The solid electrolyte interface film can also prevent the dissolution of transition metal ions and reduce the side reactions between the battery interfaces; but the additive is prone to hydrolysis, which can generate components that destroy the solid electrolyte interface film. In addition, the breaking of the S-N bond or S-C bond also generates by-products that are easy to decompose and produce gas, which greatly affects the high-temperature performance of the battery. The second component of the present application is an effective film-forming additive that can participate in the construction of a stable solid electrolyte interface film, eliminate HF / H2O in the electrolyte, and reduce the destructive effect of HF on the electrode material. The additive molecule contains a silane component, which can eliminate the LiF component in the interface film, remove excess LiF components to reduce battery impedance, and the large number of Si-O bonds in the second component have good stability, so the negative effects caused by the elimination of LiF can also be offset. The electrolyte additive of the present application simultaneously includes the first component and the second component, the second component can eliminate part of the lithium-containing inorganic components generated by the first component, and the silicon-oxygen component in the second component can replace the negative effects of the reduced stability caused by the reduction of lithium-containing inorganic components, thereby improving the high-temperature storage performance and cycle life of the secondary battery without affecting the stability of the solid electrolyte interface film, while also providing lithium ion channels and accelerating the transport of lithium ions. In addition, the second component can also eliminate by-products in the electrolyte and reduce the gas production problem caused by the first component. In summary, the electrolyte additive of the present application simultaneously includes the first component and the second component, and the synergistic effect of the first component and the second component can improve the high-temperature storage performance and cycle life of the secondary battery.

[0048] In an embodiment of the present application, the mass ratio of the first component and the second component is (0.05-20):1, preferably (0.5-3):1. For example, the mass ratio of the first component and the second component can be 0.05:1, 0.08:1, 0.1:1, 0.3:1, 0.5:1, 0.8:1, 1:1, 3:1, 5:1, 8:1, 10:1, 13:1, 15:1, 18:1, 20:1 or a range composed of any two of the above values. By limiting the mass ratio of the first component and the second component within the above range, the first component and the second component can better play a synergistic effect, further improving the high-temperature storage performance and cycle life of the secondary battery.

[0049] In the present application, the term "halogen" means a fluorine, chlorine, bromine or iodine atom.

[0050] In an embodiment of the present application, R1 is selected from fluorine, C1-C4 alkyl unsubstituted or substituted with fluorine;

[0051] R2 is selected from nitrogen or phenylene;

[0052] R3or R4are each independently selected from the group consisting of hydrogen, fluorine, unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R a unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R a unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R a unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R a unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R b unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R c unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R

[0053] R6is selected from the group consisting of hydrogen, unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, cyano, unsubstituted or substituted phenyl;

[0054] R d unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R e unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R

[0055] R f unsubstituted or substituted C1-C4alkyl, unsubstituted or substituted phenyl, unsubstituted or substituted C1-C2alkoxy, unsubstituted or substituted C2-C4alkenyl, unsubstituted or substituted C2-C4alkynyl, unsubstituted or substituted sulfonyl; the substituents R

[0056] The electrolyte comprising the above-mentioned first component and the second component is applied to a secondary battery, and the first component and the second component can further improve the high-temperature storage performance and cycle life of the secondary battery while not affecting other performances.

[0057] [Corrected according to Rule 26 03.03.2026] In an embodiment of the present application, the first component is selected from at least one of the following compounds;

[0058] The electrolyte comprising the above-mentioned first component is applied to a secondary battery, and the first component can make the secondary battery have higher high-temperature storage performance and cycle life while not affecting other performances.

[0059] [Corrected according to Rule 26 03.03.2026] In an embodiment of the present application, the second component is selected from at least one of the following compounds;

[0060] The electrolyte including the second component is applied to the secondary battery, so that the secondary battery has higher high-temperature storage performance and cycle life without affecting other performances.

[0061] In an embodiment of the present application, the electrolyte additive further includes a third component selected from at least one of vinylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, ethylene sulfate, 1,3-propane sultone, 1,3-propene sultone, vinyl sulfite, tris(trimethylsilyl)borate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, and lithium difluorodioxalate phosphate.

[0062] The electrolyte additive of the present application further includes a third component. The ester additive of the third component can generate a flexible solid electrolyte interface film, which can better isolate the side reactions of the battery interface, and also can reduce the expansion of silicon particles, improve the stability of the cycle, the salt additive can generate more lithium-containing components on the surface of the interface film, which is conducive to the transport of lithium ions, and also fills the interface film, making it more dense. The first component, the second component and the third component are used together to form a dense interface film which can better isolate the dissolution of transition metal ions. In summary, the electrolyte additive of the present application simultaneously includes the first component, the second component and the third component, and the synergistic effect of the first component, the second component and the third component can better improve the high-temperature storage performance and cycle life of the secondary battery.

[0063] In an embodiment of the present application, the mass ratio of the second component to the third component is (0.01-1.5):1, preferably (0.1-0.5):1. For example, the mass ratio of the second component to the third component can be 0.01:1, 0.03:1, 0.05:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, or a range composed of any two of the above values. By limiting the mass ratio of the first component, the second component and the third component within the above range, the first component, the second component and the third component better play a synergistic effect, further improving the high-temperature storage performance and cycle life of the secondary battery.

[0064] The second aspect of the present application provides an electrolyte, which comprises the electrolyte additive of the first aspect of the present application; the mass percentage of the electrolyte additive is 1% to 15%, preferably 3% to 8%, based on the mass of the electrolyte. For example, the mass percentage of the electrolyte additive can be 1%, 3%, 5%, 8%, 10%, 13%, 15%, or a range between any two of them, based on the mass of the electrolyte. The amount of electrolyte additive is within the above range, which can make the secondary battery have higher high-temperature storage performance and cycle life without affecting other performances.

[0065] In an embodiment of the present application, the mass percentage of the first component is A, 0.1%≤A≤2%, preferably 0.5%≤A≤1.5%, based on the mass of the electrolyte. For example, the mass percentage A of the first component can be 0.1%, 0.5%, 1%, 1.5%, 2%, or a range between any two of them, based on the mass of the electrolyte.

[0066] In an embodiment of the present application, the mass percentage of the second component is B, 0.1%≤B≤1.5%, preferably 0.5%≤B≤1%, based on the mass of the electrolyte. For example, the mass percentage B of the second component can be 0.1%, 0.5%, 1%, 1.5%, or a range between any two of them, based on the mass of the electrolyte.

[0067] In an embodiment of the present application, the mass percentage of the third component is C, 1%≤C≤10%, preferably 3%≤C≤5%, based on the mass of the electrolyte. For example, the mass percentage C of the third component can be 1%, 3%, 5%, 8%, 10%, or a range between any two of them, based on the mass of the electrolyte.

[0068] On the basis of adding the first additive and the second additive, further adding the third additive and limiting the third additive within the scope of the present application can better exert the synergistic effect between the components without affecting other performances, and further make the secondary battery have higher high-temperature storage performance and cycle life.

[0069] In an embodiment of the present application, the electrolyte further comprises a lithium salt, which is not particularly limited in the present application as long as it can achieve the purpose of the present application. For example, the lithium salt can include but is not limited to at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium bisfluorosulfonylimide, and lithium bistrifluoromethanesulfonylimide.

[0070] The content of the lithium salt in the electrolyte is not particularly limited in the present application, as long as the purpose of the present application can be achieved. For example, the mass percentage of the lithium salt is 10% to 15%, preferably 12% to 15%, based on the mass of the electrolyte.

[0071] In an embodiment of the present application, the electrolyte further comprises a non-aqueous solvent, which is not particularly limited in the present application, as long as the purpose of the present application can be achieved. For example, the non-aqueous solvent can be selected from, but not limited to, at least one of propylene carbonate, ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, fluoroethylene carbonate, γ-butyrolactone, sulfolane, methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, and butyl butyrate.

[0072] The content of the non-aqueous solvent in the electrolyte is not particularly limited in the present application, as long as the purpose of the present application can be achieved. For example, the mass percentage of the non-aqueous solvent is 72% to 88%, preferably 78% to 84%, based on the mass of the electrolyte.

[0073] The preparation method of the electrolyte of the present application is not particularly limited, as long as the purpose of the present application can be achieved. For example, the various solvents in the electrolyte can be mixed, and then the electrolyte lithium salt and additives and other substances are added and uniformly mixed.

[0074] The third aspect of the present application provides a secondary battery, which comprises a positive electrode sheet, a negative electrode sheet, a separator, and the electrolyte of the second aspect of the present application; wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode material layer arranged on at least one surface of the negative electrode current collector, the negative electrode material layer comprises a negative electrode active material, and the negative electrode active material is selected from at least one of a silicon-based material, a carbon-based material, and a lithium-containing metal composite oxide; the positive electrode sheet comprises a positive electrode current collector and a positive electrode material layer arranged on at least one surface of the positive electrode current collector, the positive electrode material layer comprises a positive electrode active material, and the positive electrode active material is selected from at least one of lithium manganate, lithium nickel cobalt manganate ternary material, lithium nickel manganate, lithium-rich manganese-based material, and lithium cobaltate.

[0075] The silicon-based material, the carbon-based material, or the lithium-containing metal composite oxide is not particularly limited in the present application, as long as the purpose of the present application can be achieved. For example, the silicon-based material can include, but not limited to, at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys; the carbon-based material can include, but not limited to, at least one of artificial graphite, natural graphite, soft carbon, hard carbon, and mesophase carbon microbeads; and the lithium-containing metal composite oxide can include, but not limited to, at least one of lithium titanate and metallic lithium.

[0076] The positive electrode active material and the negative electrode active material of the application are matched with the electrolyte additive of the application, further improving the high-temperature storage performance and cycle life of the secondary battery.

[0077] It should be noted that in the specific embodiments of the application, the lithium ion battery is taken as an example of the secondary battery to explain the application, but the secondary battery of the application is not limited to the lithium ion battery. The specific technical solutions are as follows:

[0078] The conductive agent is not particularly limited in the application, as long as the purpose of the application can be achieved, for example, the conductive agent can be selected from, but not limited to, at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. The above-mentioned carbon nanotubes can include, but are not limited to, single-walled carbon nanotubes and / or multi-walled carbon nanotubes. The above-mentioned carbon fibers can include, but are not limited to, vapor grown carbon fibers (VGCF) and / or nanocarbon fibers.

[0079] The binder is not particularly limited in the application, as long as the purpose of the application can be achieved, for example, the binder can be selected from, but not limited to, at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylic ester resin.

[0080] In the application, the "positive electrode material layer arranged on at least one surface of the positive electrode current collector" means that the positive electrode material layer can be arranged on one surface of the positive electrode current collector along the thickness direction of the positive electrode current collector, or can be arranged on two surfaces of the positive electrode current collector along the thickness direction of the positive electrode current collector. It should be noted that the "surface" here can be the entire area of the surface of the positive electrode current collector, or can be part of the area of the surface of the positive electrode current collector, which is not particularly limited in the application, as long as the purpose of the application can be achieved.

[0081] The positive current collector is not particularly limited in the present application, as long as the object of the present application can be achieved. For example, the positive current collector can be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil, an aluminum alloy foil, a carbon-coated aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0082] The positive material layer can further include a conductive agent and a binder, and the kind of the conductive agent and the binder is not particularly limited in the present application, as long as the object of the present application can be achieved. For example, it can be at least one of the above-mentioned conductive agent and the above-mentioned binder. The mass ratio of the positive active material, the conductive agent, and the binder in the positive material layer is not particularly limited in the present application, and a person skilled in the art can select according to the actual need, as long as the object of the present application can be achieved.

[0083] The thickness of the positive current collector and the positive material layer is not particularly limited in the present application, as long as the object of the present application can be achieved. For example, the thickness of the positive current collector is 5 μm to 20 μm, and the thickness of the single-sided positive material layer is 20 μm to 90 μm.

[0084] Optionally, the positive electrode sheet can further include a conductive layer, and the conductive layer is located between the positive current collector and the positive material layer. The composition of the conductive layer is not particularly limited, and it can be a commonly used conductive layer in the art. The conductive layer includes a conductive agent and a binder. The conductive agent and the binder in the conductive layer are not particularly limited in the present application, and for example, it can be at least one of the above-mentioned conductive agent and the above-mentioned binder.

[0085] In an embodiment of the present application, the compaction density of the positive electrode sheet is 2 g / cm 3 ~ 5 g / cm 3 .

[0086] In the present application, the secondary battery further includes a separator. The separator is not particularly limited in the present application, as long as the object of the present application can be achieved. For example, the material of the separator can be selected from, but not limited to, at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The number of layers of the separator is not particularly limited in the present application, as long as the object of the present application can be achieved. For example, the separator can be a single-layer film, or a multi-layer composite film.

[0087] In some embodiments of the present application, the separator can include a substrate layer and a surface treatment layer. The substrate layer is not particularly limited in the present application as long as the object of the present application can be achieved. For example, the substrate layer can be selected from, but not limited to, at least one of polyethylene, polypropylene, polyvinylidene fluoride, and polyacrylonitrile.

[0088] Optionally, a surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer is not particularly limited in the present application as long as the object of the present application can be achieved. For example, the surface treatment layer can be selected from, but not limited to, at least one of conductive carbon, aluminum trioxide, and Li 6.4 La3Zr 1.4 Ta 0.6 O 12 (LLZTO).

[0089] In the present application, the thickness of the separator is not particularly limited as long as the object of the present application can be achieved, for example, the thickness of the separator can be 5 μm to 10 μm.

[0090] In the present application, the above-mentioned "negative electrode material layer provided on at least one surface of the negative electrode current collector" means that the negative electrode material layer can be provided on one surface of the negative electrode current collector along the thickness direction of the negative electrode current collector, or can be provided on two surfaces of the negative electrode current collector along the thickness direction of the negative electrode current collector. It should be noted that the "surface" here can be the entire area of the surface of the negative electrode current collector, or can be part of the area of the surface of the negative electrode current collector, and the present application is not particularly limited as long as the object of the present application can be achieved.

[0091] The negative electrode current collector is not particularly limited in the present application as long as the object of the present application can be achieved, for example, the negative electrode current collector can adopt a metal foil or a composite current collector. For example, as a metal foil, a copper foil, an aluminum alloy foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, etc.) on a polymer material base (such as a base of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0092] In some embodiments of the present application, the negative electrode material layer can further include a conductive agent and a binder, and the types of the conductive agent and the binder are not particularly limited in the present application as long as the object of the present application can be achieved, for example, can be at least one of the above-mentioned conductive agent and the above-mentioned binder. The mass ratio of the negative electrode active material, the conductive agent, and the binder in the negative electrode material layer is not particularly limited in the present application, and those skilled in the art can select according to actual needs as long as the object of the present application can be achieved.

[0093] In some embodiments of the present application, the negative material layer can further include a conductive agent, a binder, and a thickening agent. The present application does not have a particular limitation on the types of the conductive agent and the binder as long as the purpose of the present application can be achieved. For example, the conductive agent and the binder can be at least one of the above-mentioned conductive agents and the above-mentioned binders. The thickening agent can include, but is not limited to, at least one of sodium carboxymethyl cellulose and lithium carboxymethyl cellulose. The present application does not have a particular limitation on the mass ratio of the negative active material, the conductive agent, the binder, and the thickening agent in the negative material layer, and a person skilled in the art can select according to actual needs as long as the purpose of the present application can be achieved.

[0094] The present application does not have a particular limitation on the thickness of the negative material layer as long as the purpose of the present application can be achieved. For example, the thickness of the single-sided negative material layer is 30 μm to 125 μm.

[0095] The present application does not have a particular limitation on the thickness of the negative current collector as long as the purpose of the present application can be achieved. For example, the thickness of the negative current collector is 4 μm to 10 μm.

[0096] Optionally, the negative electrode sheet can further include a conductive layer between the negative current collector and the negative material layer. The present application does not have a particular limitation on the composition of the conductive layer, which can be a commonly used conductive layer in the art. For example, the conductive layer includes a conductive agent and a binder. The present application does not have a particular limitation on the conductive agent and the binder in the conductive layer, which can be at least one of the above-mentioned conductive agents and the above-mentioned binders.

[0097] In some embodiments of the present application, the compaction density of the negative electrode sheet is 1 g / cm 3 ~ 4 g / cm 3 .

[0098] The secondary battery further includes a shell for accommodating the positive electrode sheet, the separator, the negative electrode sheet, and the electrolyte, and other components known in the art of secondary batteries, and the present application does not limit the above-mentioned other components. The present application does not have a particular limitation on the shell, which can be a shell known in the art as long as the purpose of the present application can be achieved. For example, the shell can be a hard shell or a flexible shell. The material of the hard shell can be metal, and the present application does not limit the type of metal, which can use a metal hard shell known in the art as long as the purpose of the present application can be achieved. The flexible shell can be a metal plastic film, such as an aluminum plastic film, a steel plastic film, etc.

[0099] The preparation process of the secondary battery of the present application is well known to those skilled in the art, and the present application is not particularly limited, for example, the preparation process of the secondary battery can include but is not limited to the following steps: stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and winding, folding and the like as needed to obtain an electrode assembly of a wound structure, placing the electrode assembly into a case, injecting an electrolyte into the case and sealing, forming, sorting to obtain a secondary battery.

[0100] In some embodiments of the present application, the secondary battery of the present application can be suitable for a high voltage system, with a voltage range of 4.2-4.6V.

[0101] The fourth aspect of the present application provides an electronic device comprising the secondary battery of the third aspect of the present application.

[0102] The electronic device of the present application is not particularly limited, and can be any electronic device known in the art. In some embodiments, the electronic device can include but is not limited to a notebook computer, a pen input computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile machine, a portable copying machine, a portable printer, a head-mounted stereo headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power supply, an electric motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, a lighting appliance, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a household large storage battery or a lithium ion capacitor, etc.

[0103] Embodiments

[0104] Hereinafter, embodiments and comparative examples are given to more specifically explain the embodiments of the present application. Various tests and evaluations were carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are on a mass basis.

[0105] Test methods and apparatus:

[0106] Normal temperature cycle performance test

[0107] The lithium ion battery was placed in a 25°C constant temperature test box and allowed to stand for 30 minutes to allow the lithium ion battery to reach a constant temperature. It was charged at 1.0C constant current to 4.4V, then charged at constant voltage 4.4V to a cutoff current of 0.05C, allowed to stand for 5 minutes, discharged at 1.0C constant current to 2.75V, and the discharge capacity C1 was recorded. This step was repeated for 500 cycles, and the discharge capacity C2 after 500 cycles was recorded, and the cycle capacity retention rate of the lithium ion battery was calculated. Normal temperature cycle capacity retention rate = C2 / C1 x 100%.

[0108] High temperature cycle performance test

[0109] The lithium ion battery was placed in a 45°C constant temperature test box and allowed to stand for 60 minutes to allow the lithium ion battery to reach a constant temperature. Charged at 1.0C constant current to 4.4V, then charged at constant voltage 4.4V to the cutoff current of 0.05C, and allowed to stand for 5 minutes, discharged at 1.0C constant current to 2.75V, and recorded as the discharge capacity C3. The above steps were repeated for 300 cycles, and the discharge capacity C4 after 300 cycles was recorded, and the cycle capacity retention rate of the lithium ion battery was calculated. High-temperature cycle capacity retention rate = C4 / C3 x 100%.

[0110] High-temperature storage performance test

[0111] The lithium ion battery was placed in a 25°C constant temperature test box and allowed to stand for 30 minutes to allow the lithium ion battery to reach a constant temperature. Charged at 1.0C constant current to 4.4V, then charged at constant voltage 4.4V to the cutoff current of 0.05C, and allowed to stand for 5 minutes, discharged at 1.0C constant current to 2.75V, and recorded as the discharge capacity C5. Charged at 1.0C constant current to 4.4V, then charged at constant voltage 4.4V to the cutoff current of 0.05C, and the thickness of the lithium ion battery was measured as hi, then the lithium ion battery was transferred to 60°C and allowed to stand for 28 days, and the thickness of the lithium ion battery was measured as h2, then discharged at 1.0C constant current to 2.75V, and the discharge capacity was recorded as C6. High-temperature storage capacity retention rate = C6 / C5 x 100%, and high-temperature storage thickness expansion rate = (h2-h1) / h1 x 100%.

[0112] High-temperature storage direct current internal resistance (DCIR) growth rate

[0113] The lithium ion battery was placed in a 25°C constant temperature test box and allowed to stand for 30 minutes to allow the lithium ion battery to reach a constant temperature. Charged at 1.0C constant current to 4.4V, then charged at constant voltage 4.4V to the cutoff current of 0.05C, and allowed to stand for 5 minutes, discharged at 1.0C constant current to 2.75V, and recorded as the discharge capacity C5. Charged at 1.0C constant current to 4.4V, then charged at constant voltage 4.4V to the cutoff current of 0.05C, and the thickness of the lithium ion battery was measured as hi, then the lithium ion battery was transferred to 60°C and allowed to stand for 28 days, and the thickness of the lithium ion battery was measured as h2, then discharged at 1.0C constant current to 2.75V, and the discharge capacity was recorded as C6. High-temperature storage capacity retention rate = C6 / C5 x 100%, and high-temperature storage thickness expansion rate = (h2-h1) / h1 x 100%. 2C ) discharged at 2C rate for 10s, and the voltage values before and after 2C rate discharge were recorded as V1 and V2, respectively, and the DCIR1 of the lithium ion battery at 50% state of charge (SOC) was calculated (the calculation formula of DCIR1 is: DCIR1 = (V1-V2) / I 2C ).

[0114] Then the lithium ion battery was transferred to 60°C and allowed to stand for 7 days, and after 3 weeks of 1.0C constant current charge and discharge (charged at 1.0C to 4.4V, then charged at constant voltage 4.4V to the cutoff current of 0.05C, allowed to stand for 5 minutes, discharged at 1.0C constant current to 2.75V, and cycled for 3 weeks), the lithium ion battery was charged at 1.0C constant current to 4.4V, allowed to stand for 5 minutes, then discharged at 1.0C for 30 minutes, allowed to stand for 1 hour, then discharged at 2C rate corresponding current (I 2C) discharge 10s, record the voltage values before and after 2C rate discharge V3 and V4 respectively, calculate the DCIR2 of the battery at 50% SOC (the calculation formula of DCIR2 is: DCIR2 = (V3-V4) / I 2C ).

[0115] DCIR growth rate = (DCIR2-DCIR1) / DCIR1 x 100%.

[0116] Example 1-1

[0117] Preparation of electrolyte

[0118] In an argon atmosphere glove box (water content <10 ppm, oxygen content <1 ppm), non-aqueous organic solvents ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) were mixed uniformly in a mass ratio of 3:5:2, then the first component compound I-1 and the second component compound II-1 were added and mixed uniformly, and then lithium salt lithium hexafluorophosphate was added, dissolved and mixed uniformly to obtain an electrolyte; wherein the mass percentage of lithium salt lithium hexafluorophosphate was 12.5% based on the mass of the electrolyte, the mass percentage A of the first component compound I-1 was 0.05%, the mass percentage B of the second component compound II-1 was 1%, and the balance was non-aqueous organic solvent.

[0119] Preparation of positive electrode sheet

[0120] The positive active material lithium nickel cobalt manganese oxide (NCM613), the binder polyvinylidene fluoride (PVDF), the conductive agent acetylene black, and the conductive agent single-walled carbon nanotube (SWCNT) were mixed in a mass ratio of 95:1.5:3:0.5, N-methyl pyrrolidone (NMP) was added as a solvent, and a slurry with a solid content of 65 wt% was prepared. After uniform stirring in a vacuum, a positive electrode slurry was obtained. The positive electrode slurry was uniformly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 16 μm, and after baking in an oven with different temperature gradients (90°C, 100°C, 85°C in turn) at a speed of 2200 mm / min, it was dried at 120°C. A positive electrode sheet with a single coated positive electrode material layer was obtained. Then the above steps were repeated on the other surface of the aluminum foil, and a positive electrode sheet with a double coated positive electrode material layer was obtained. After cutting and welding the tabs, a positive electrode sheet with a size of 258 mm x 54 mm was obtained for use. The compaction density of the positive electrode material layer was 3.4 g / cm 3 , and the thickness of the single positive electrode material layer was 37 μm.

[0121] Preparation of negative electrode sheet

[0122] The negative active material artificial graphite (BTR S360-L1), thickening agent sodium carboxymethyl cellulose (CMC-Na), binder styrene-butadiene rubber, and conductive agent acetylene black were mixed in a mass ratio of 95:1.5:2:1.5, deionized water was added as a solvent, and a slurry with a solid content of 49 wt% was prepared. After uniform vacuum stirring, a negative electrode slurry was obtained. The negative electrode slurry was uniformly coated on one surface of a negative electrode current collector copper foil with a thickness of 9 μm, dried at 85°C, and a negative electrode sheet with a single-sided coated negative electrode material layer was obtained. Then, the above steps were repeated on the other surface of the copper foil, and a negative electrode sheet with a double-sided coated negative electrode material layer was obtained. After cutting and welding the tabs, a negative electrode sheet with a size of 264 mm x 58 mm was obtained for use. The compacted density of the negative electrode material layer was 1.5 g / cm 3 , and the thickness of the single-sided negative electrode material layer was 50 μm.

[0123] <Preparation of a separator>

[0124] A polyethylene (provided by Xingliang Material Co., Ltd.) with a thickness of 8 μm was used as a separator.

[0125] <Preparation of a lithium ion battery>

[0126] The positive electrode sheet, the separator, and the negative electrode sheet prepared above were stacked in order, with the separator between the positive electrode sheet and the negative electrode sheet to play a separating role, and then wound. The positive tab was connected to the positive electrode sheet, and the negative tab was connected to the negative electrode sheet, and an electrode assembly was obtained. The electrode assembly was placed in an aluminum plastic film, and the positive tab and the negative tab were led out from the inside space of the aluminum plastic film to the outside space of the aluminum plastic film. After removing the water at 85°C, the electrolyte prepared above was injected, vacuum sealed, and left to stand for 24 hours. Then, a pressure of 3 kg / cm 2 was applied at 45°C, and formation was performed by charging at 0.1C for 6.5 hours. Then, the lithium ion battery was sorted by discharging (charged at 0.1C to 4.4V, then charged at 4.4V to the cutoff current 0.05C, left to stand for 5 minutes, discharged at 0.5C to 2.75V; then charged at 0.5C to 4.4V, then charged at 4.4V to the cutoff current 0.05C, left to stand for 5 minutes, discharged at 1.0C to 2.75V; then charged at 1.0C to 4.4V, then charged at 4.4V to the cutoff current 0.05C, left to stand for 5 minutes, discharged at 1.0C to 2.75V), and the lithium ion battery was obtained.

[0127] Examples 1-2 to 1-41

[0128] Except that the types and mass percentages of the first component and the second component in the <Preparation of an electrolyte> were adjusted according to Table 1, the mass percentage of the non-aqueous organic solvent changed accordingly, and the mass percentage of the lithium salt remained unchanged, the rest was the same as in Example 1-1.

[0129] Examples 1-42

[0130] <Preparation of electrolyte>

[0131] In an argon atmosphere glove box (water content <10 ppm, oxygen content <1 ppm), non-aqueous organic solvents ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) were mixed uniformly in a mass ratio of 3:5:2, then the first component compound of formula I-1 and the second component compound of formula II-1 were mixed uniformly, and then lithium salt lithium hexafluorophosphate was added, dissolved and mixed uniformly to obtain an electrolyte; wherein, based on the mass of the electrolyte, the mass percentage of lithium salt lithium hexafluorophosphate was 12.5%, the mass percentage A of the first component compound of formula I-1 was 0.5%, the mass percentage B of the second component compound of formula II-1 was 0.5%, and the balance was non-aqueous organic solvent.

[0132] <Preparation of positive electrode sheet>

[0133] The positive active material lithium cobaltate, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black were mixed in a mass ratio of 97.3:1.2:1.5, N-methyl pyrrolidone (NMP) was added as a solvent, and a slurry with a solid content of 68.4 wt% was prepared. After uniform stirring in a vacuum, a positive electrode slurry was obtained. The positive electrode slurry was uniformly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 16 μm. After baking in an oven with different temperature gradients (in order of 90°C, 100°C, and 85°C) at a speed of 2200 mm / min, the positive electrode slurry was dried at 120°C. A positive electrode sheet with a single coated positive electrode material layer was obtained. Then, the above steps were repeated on the other surface of the aluminum foil, and a positive electrode sheet with a double coated positive electrode material layer was obtained. After cutting and welding the tabs, a positive electrode sheet with a size of 558 mm x 55 mm was obtained for use. The compaction density of the positive electrode material layer was 4.15 g / cm 3 , and the thickness of the single positive electrode material layer was 36 μm.

[0134] <Preparation of negative electrode sheet>

[0135] The negative active material artificial graphite (BTR S360-L1), thickening agent sodium carboxymethyl cellulose (CMC-Na), binder styrene-butadiene rubber, conductive agent acetylene black, and conductive agent single-walled carbon nanotube (SWCNT) were mixed in a mass ratio of 95.9:1:2:1:0.1, deionized water was added as a solvent, and a slurry with a solid content of 49 wt% was prepared. After uniform vacuum stirring, a negative electrode slurry was obtained. The negative electrode slurry was uniformly coated on one surface of a negative electrode current collector copper foil with a thickness of 9 μm, and was dried at 85°C to obtain a negative electrode sheet with a single-side coated negative electrode material layer. Then, the above steps were repeated on the other surface of the copper foil to obtain a negative electrode sheet with a double-side coated negative electrode material layer. After cutting and welding the tabs, a negative electrode sheet with a size of 708 mm x 59 mm was obtained for use. The compacted density of the negative electrode material layer was 1.6 g / cm 3 , and the thickness of the single-side negative electrode material layer was 63.5 μm.

[0136] <Preparation of a separator>

[0137] A polyethylene with a thickness of 8 μm (provided by Xingliu Material Co., Ltd.) was used as a separator.

[0138] <Preparation of a lithium ion battery>

[0139] The positive electrode sheet, the separator, and the negative electrode sheet prepared above were stacked in order with the separator between the positive electrode sheet and the negative electrode sheet to play a role of isolation, and were then wound. The positive tab was connected to the positive electrode sheet, and the negative tab was connected to the negative electrode sheet to obtain an electrode assembly. The electrode assembly was placed in an aluminum plastic film, and the positive tab and the negative tab were led out from the inside space of the aluminum plastic film to the outside space of the aluminum plastic film. After removing the water at 85°C, the electrolyte prepared above was injected, and the vacuum sealing, standing for 24 hours, and application of a pressure of 3 kg / cm 2 at 45°C were performed. Formation was carried out by constant current charging at 0.1 C for 6.5 hours, and then the lithium ion battery was obtained by sorting (constant current charging at 0.1 C to 4.4 V, constant voltage charging at 4.4 V to a cutoff current of 0.05 C, standing for 5 minutes, constant current discharging at 0.5 C to 2.75 V; constant current charging at 0.5 C to 4.4 V, constant voltage charging at 4.4 V to a cutoff current of 0.05 C, standing for 5 minutes, constant current discharging at 1.0 C to 2.75 V; constant current charging at 1.0 C to 4.4 V, constant voltage charging at 4.4 V to a cutoff current of 0.05 C, standing for 5 minutes, constant current discharging at 1.0 C to 2.75 V).

[0140] Examples 2-1 to 2-23

[0141] The same as Example 1-7 except that the third component was added in the preparation of electrolyte solution as shown in Table 2, the kind and mass percentage of the third component were adjusted according to Table 2, the mass percentage of non-aqueous organic solvent was changed accordingly, and the mass percentage of lithium salt was unchanged.

[0142] Comparative Example 1

[0143] The same as Example 1-1 except that the second component was not added in the preparation of electrolyte solution, the mass percentage of the first component was adjusted according to Table 1, the mass percentage of non-aqueous organic solvent was changed accordingly, and the mass percentage of lithium salt was unchanged.

[0144] Comparative Example 2

[0145] The same as Example 1-1 except that the first component was not added in the preparation of electrolyte solution, the mass percentage of the second component was adjusted according to Table 1, the mass percentage of non-aqueous organic solvent was changed accordingly, and the mass percentage of lithium salt was unchanged.

[0146] Comparative Example 3

[0147] The same as Example 1-42 except that the first component was not added in the preparation of electrolyte solution, the mass percentage of the second component was adjusted according to Table 1, the mass percentage of non-aqueous organic solvent was changed accordingly, and the mass percentage of lithium salt was unchanged.

[0148] Comparative Example 4

[0149] The same as Example 1-42 except that the second component was not added in the preparation of electrolyte solution, the mass percentage of the first component was adjusted according to Table 1, the mass percentage of non-aqueous organic solvent was changed accordingly, and the mass percentage of lithium salt was unchanged.

[0150] The preparation parameters and performance parameters of each example and comparative example are shown in Table 1 to Table 2.

[0151] As can be seen from Examples 1-1 to 1-42, Comparative Examples 1 to 4, the electrolyte with only the first component or the second component added is applied to the lithium ion battery, and the lithium ion battery has a lower capacity retention rate at room temperature, a high-temperature cycle capacity retention rate, a high-temperature storage capacity retention rate, and a higher high-temperature storage thickness expansion rate and a high-temperature storage DCIR increase rate. The electrolyte with the first component and the second component added simultaneously is applied to the lithium ion battery, and the lithium ion battery has a higher capacity retention rate at room temperature, a high-temperature cycle capacity retention rate, and a high-temperature storage capacity retention rate, and a lower high-temperature storage thickness expansion rate and a high-temperature storage DCIR increase rate. The above results show that the combination of the first component and the second component can improve the high-temperature storage performance and cycle life of the lithium ion battery.

[0152] As can be seen from Examples 1-7, Examples 2-1 to 2-23, the electrolyte with the first component, the second component, and the third component added simultaneously is applied to the lithium ion battery, and the lithium ion battery has a higher capacity retention rate at room temperature, a high-temperature cycle capacity retention rate, and a high-temperature storage capacity retention rate, and a lower high-temperature storage thickness expansion rate and a high-temperature storage DCIR increase rate. The above results show that the combination of the first component, the second component, and the third component can make the lithium ion battery have better high-temperature storage performance and cycle life.

[0153] It should be noted that the relational terms herein such as first and second, and the like are used only to differentiate one entity or operation from another, and do not necessarily require or imply that any such actual relationship or order exists between or among the entities or operations. Also, the terms "comprising", "containing", or any other similar term are intended to encompass non-exclusive inclusion, such that a process, method, or article that comprises a list of elements does not necessarily include only those elements, but can include other elements not expressly listed or inherent to such process, method, or article.

[0154] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. [Corrected according to Rule 26 03.03.2026] An electrolyte additive comprising a first component and a second component; said first component is selected from the group consisting of compounds of formula I; said second component is selected from the group consisting of compounds of formula II; wherein R1is selected from halogen, C1-C6alkyl unsubstituted or substituted with halogen; R2is selected from nitrogen or C6-Ci8-aryl; 12 heteroaryl; and R2is selected from nitrogen or C6-Ci8-aryl; R3 or R4 are each independently selected from hydrogen, halogen, unsubstituted or R-substituted. a Substituted C1-C6 alkyl, unsubstituted or R a Replacement C6-C 12 aryl, unsubstituted or R a Substituted sulfonyl group; substituent R a Each is independently selected from halogens, unsubstituted or halogenated C1-C6 alkyl groups, C6-C 12 Aryl, C1-C2 alkoxy, C2-C6 alkenyl, cyano substituents R b or R c each independently selected from C1-C6alkyl unsubstituted or substituted by halogen; R6 is selected from hydrogen, unsubstituted or halogenated C1-C6 alkyl, unsubstituted or halogenated C2-C6 alkenyl, unsubstituted or halogenated C2-C6 alkynyl, cyano, unsubstituted or halogenated C6-C 12 Aryl; R5is selected from R d or R e Each is independently selected from hydrogen, unsubstituted or halogenated C1-C6 alkyl, unsubstituted or halogenated C2-C6 alkenyl, unsubstituted or halogenated C2-C6 alkynyl, cyano, unsubstituted or halogenated C6-C 12 Aryl; R f selected from the group consisting of C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, C3-C6cycloalkyl, C4-C8alkylcycloalkyl, C4-C8cycloalkylalkyl, C5-C10alkylcycloalkylalkyl, C6-C10cycloalkylcycloalkylalkyl, C3-C6cycloalkenyl, C4-C8alkylcycloalkenyl, C4-C8cycloalkylalkyl, C5-C10alkylcycloalkylalkyl, C6-C10cycloalkylcyc 2. The electrolyte additive according to claim 1, wherein, a mass ratio of the first component and the second component is (0.05-20):1, preferably (0.5-3):

1.

3. The electrolyte additive according to claim 1, wherein, R1is selected from fluorine, C1-C4alkyl unsubstituted or substituted with fluorine; R2is selected from nitrogen or phenylene; R3 or R4 are each independently selected from hydrogen, fluorine, unsubstituted or R-substituted. a Substituted C1-C4 alkyl, unsubstituted or R a Substituted phenyl, unsubstituted or R a Substituted sulfonyl group; substituent R a Each is independently selected from fluorine, unsubstituted or fluorinated C1-C4 alkyl, phenyl, C1-C2 alkoxy, C2-C4 alkenyl, cyano, substituents R b or R c each independently selected from C1-C4 alkyl unsubstituted or substituted by fluorine; R6is selected from hydrogen, C1-C4alkyl unsubstituted or substituted with fluorine, C2-C4alkenyl unsubstituted or substituted with fluorine, C2-C4alkynyl unsubstituted or substituted with fluorine, cyano, phenyl unsubstituted or substituted with fluorine; R d or R e each independently is selected from the group consisting of hydrogen, C1-C4-alkyl which is unsubstituted or substituted by fluorine, C2-C4-alkenyl which is unsubstituted or substituted by fluorine, C2-C4-alkynyl which is unsubstituted or substituted by fluorine, cyano, phenyl which is unsubstituted or substituted by fluorine; R f selected from the group consisting of C1-C4-alkyl, C2-C4-alkenyl, C2-C4-alkynyl; n is 0, 1, 2 or 3.

4. The electrolyte additive according to claim 1, wherein The first component is selected from at least one of the following compounds; 5. The electrolyte additive according to claim 1, wherein The second component is selected from at least one of the following compounds:

6. The electrolyte additive according to claim 1, wherein, the electrolyte additive further comprises a third component selected from at least one of vinylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, ethylene sulfate, 1,3- propanesultone, 1,3-propene sultone, ethylene sulfite, tris(trimethylsilyl)borate, lithium bisoxalate borate, lithium difluoro oxalate borate, and lithium difluorodi oxalate phosphate.

7. The electrolyte additive according to claim 6, wherein, a mass ratio of the second component and the third component is (0.01-1.5):1, preferably (0.1-0.5):

1.

8. An electrolyte comprising the electrolyte additive according to any one of claims 1 to 7; a mass percentage of the electrolyte additive is 1% to 15%, preferably 3% to 8%, based on a mass of the electrolyte.

9. The electrolyte according to claim 8, which satisfies at least one of the following characteristics: (1) a mass percentage of the first component is A, 0.1%≤A≤2%, preferably 0.5%≤A≤1.5%, based on a mass of the electrolyte; (2) a mass percentage of the second component is B, 0.1%≤B≤1.5%, preferably 0.5%≤B≤1%, based on a mass of the electrolyte; (3) a mass percentage of the third component is C, 1%≤C≤10%, preferably 3%≤C≤5%, based on a mass of the electrolyte.

10. A secondary battery comprising a positive electrode sheet, a negative electrode sheet, a separator, and the electrolyte solution according to any one of claims 8 to 9; wherein, the negative electrode tab comprises a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, the negative electrode material layer comprising a negative electrode active material selected from at least one of a silicon-based material, a carbon-based material, and a lithium-containing metal composite oxide; the positive electrode tab comprises a positive electrode current collector and a positive electrode material layer disposed on at least one surface of the positive electrode current collector, the positive electrode material layer comprising a positive electrode active material selected from at least one of lithium manganate, lithium nickel cobalt manganese ternary material, lithium nickel manganate, lithium-rich manganese-based material, and lithium cobaltate.

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