Additive composition, electrolyte comprising same, and battery

Abstract

The present application provides an additive composition, an electrolyte comprising same, and a battery. The additive composition comprises a first additive and a second additive, wherein the first additive comprises a compound having a structure as shown in formula 1, and the second additive comprises a silane-based additive. The additive composition provided in the present application is applied to the electrolyte, thereby improving the cycle performance and the high-temperature performance of the battery.

Description

Additive composition, electrolyte and battery thereof

[0001] The present application claims priority to the Chinese patent application No. 202410648928.4 filed on May 23, 2024, and entitled "Additive composition, electrolyte and battery thereof", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to an additive composition, in particular to an additive composition, electrolyte and battery thereof, and belongs to the technical field of secondary batteries. BACKGROUND

[0003] Lithium ion batteries and sodium ion batteries are widely used in 3C, power, energy storage and other fields as green conversion media of chemical energy and electrical energy due to their long cycle life, environmental sustainability, no memory effect and other advantages. The demand for energy density of lithium ion batteries and sodium ion batteries is gradually increasing, making high-temperature high-voltage and long-cycle systems an important direction for future lithium ion batteries and sodium ion batteries.

[0004] The commonly used method at present is to add an additive to the electrolyte to improve the electrochemical performance of lithium ion batteries and sodium ion batteries. However, there are still some problems to be solved in the practical application of a single additive, such as the possibility of causing high-temperature gas generation, large room temperature and low temperature internal resistance and poor cycle performance of the battery during operation, thereby degrading the cycle performance and high-temperature performance of the battery.

[0005] Therefore, it is urgent to develop an additive composition that can improve the cycle performance and high-temperature performance of the battery. SUMMARY

[0006] The present application provides an additive composition, which is applied to an electrolyte and can improve the cycle performance and high-temperature performance of the battery.

[0007] The present application provides an electrolyte, which can improve the cycle performance and high-temperature performance of the battery.

[0008] The present application provides a battery, which has excellent cycle performance and high-temperature performance.

[0009] The present application provides an additive composition, wherein the additive composition comprises a first additive and a second additive; the first additive comprises a compound having a structure shown in Formula 1:

[0010] wherein R1is selected from one of -R, -OR, R is selected from one of substituted or unsubstituted C1-C7alkyl, substituted or unsubstituted C2-C7alkenyl, substituted or unsubstituted C2-C6alkynyl; R2-R5are each independently selected from one of halogen, substituted or unsubstituted C1-C6alkyl; M is an alkali metal; Y + is a monovalent cation;

[0011] The second additive includes a silane-based additive.

[0012] The silane-based additive contains an unsaturated bond.

[0013] The additive composition as described above, wherein the second additive includes at least one of a silane additive having a structure according to Formula 2, Formula 3, Formula 4:

[0014] wherein R6-R 11 are each independently selected from one of substituted or unsubstituted C1-C12alkyl, substituted or unsubstituted C2-C12alkenyl, substituted or unsubstituted C2-C12alkynyl, substituted or unsubstituted C1-C12alkoxy, substituted or unsubstituted C6-C12aromatic, substituted or unsubstituted C6-C12aromatic oxy, R6-R 11 include one of halogen, amino, hydroxyl, and the silane additive having a structure according to Formula 2 contains at least 2 unsaturations;

[0015] R 12 -R 15 are each independently selected from one of substituted or unsubstituted C1-C12alkyl, substituted or unsubstituted C2-C12alkenyl, substituted or unsubstituted C2-C12alkynyl, substituted or unsubstituted C1-C12alkoxy, substituted or unsubstituted C6-C12aromatic, substituted or unsubstituted C6-C12aromatic oxy, R 12 -R 15 include one of halogen, hydroxyl, and the silane additive having a structure according to Formula 3 contains at least 2 unsaturations;

[0016] R 16 , R 17 , R 18 are each independently selected from one of vinyl, methoxyethyl, substituted or unsubstituted C1-C5alkyl, and the silane additive having a structure according to Formula 4 contains at least 3 unsaturations.

[0017] The additive composition as described above, wherein R1 is selected from one of substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C2-C6 alkenyl; at least one of R2-R5 comprises a halogen; M is selected from one of Li, Na, K; Y+ is N+R a R b R c R d , R a -R d each independently selected from one of H, halogen, substituted or unsubstituted C1-C7 alkyl, substituted or unsubstituted C2-C7 alkenyl, substituted or unsubstituted C2-C6 alkynyl, R a -R d comprises at least one hydrogen.

[0018] The additive composition as described above, wherein R1 is selected from one of substituted or unsubstituted C2-C6 alkenyl; each of R2-R5 is independently selected from a halogen; M is Li; Y + is N + R a R b R c R d , R a is hydrogen, R b -R d each independently selected from C1-C3 alkyl.

[0019] The additive composition as described above, wherein at least two of R6-R 11 comprise carbon-carbon double bonds;

[0020] and / or, at least two of R 12 -R 15 comprise carbon-carbon double bonds;

[0021] and / or, the silane additive of the structure of Formula 4 comprises at least three carbon-carbon double bonds.

[0022] The additive composition as described above, wherein the first additive comprises a compound of the structure of Formula 5 to Formula 8:

[0023] The additive composition as described above, wherein the silane additive of the structure of Formula 2 comprises at least one of tetramethyldivinyl disiloxane, dimethyltetraethenyl disiloxane, dimethyldivinyl difluorocarbosiloxane, divinyltetrafluorocarbosiloxane;

[0024] and / or, the silane additive of the structure of Formula 3 comprises at least one of divinyl dimethyl silane, triethenyl methyl silane, tetraethenyl silane;

[0025] and / or the silane additive having the structure of Formula 4 includes at least one of tris(dimethylvinylsilyl) phosphate, bis(dimethylvinylsilyl) methoxy phosphate, tris(dimethyl(methoxyethyl)silyl) phosphate, bis(dimethyl(methoxyethyl)silyl) methoxy phosphate, bis(dimethylvinylsilyl) phosphate dimer, and bis(dimethyl(methoxyethyl)silyl) phosphate dimer.

[0026] The present application provides an electrolyte, wherein the electrolyte includes a lithium salt or a sodium salt, an organic solvent, and an additive composition as described above.

[0027] The electrolyte as described above, wherein the mass percentage content of the first additive in the electrolyte is 0.1-3%; and / or,

[0028] The mass percentage content of the second additive in the electrolyte is 0.03-3%.

[0029] The electrolyte as described above, wherein the second additive includes a silane additive having the structure of Formula 2, Formula 3, and the mass ratio of the silane additives having the structure of Formula 2, Formula 3 is (1.5-2.0):1;

[0030] and / or the second additive includes a silane additive having the structure of Formula 2, Formula 4, and the mass ratio of the silane additives having the structure of Formula 2, Formula 4 is (0.5-1.5):1;

[0031] and / or the second additive includes a silane additive having the structure of Formula 3, Formula 4, and the mass ratio of the silane additives having the structure of Formula 3, Formula 4 is (0.5-1.5):1;

[0032] and / or the second additive includes a silane additive having the structure of Formula 2, Formula 3, Formula 4, and the mass ratio of the silane additives having the structure of Formula 2, Formula 3, Formula 4 is (0.5-1.5):(0.5-1.5):1.

[0033] The electrolyte as described above, wherein the electrolyte further includes an auxiliary additive, and the auxiliary additive includes at least one of 1,3-propane sultone, fluoroethylene carbonate, vinylene carbonate, 1,3-propene sultone, tris(trimethylsilyl) phosphate, tris(trimethylsilyl) borate, vinyl sulfate, lithium difluorodioxalate phosphate, lithium difluorophosphate, lithium difluoroborate oxalate, vinyl sulfite;

[0034] The mass percentage content of the auxiliary additive in the electrolyte is 0.03-3.2%.

[0035] The application also provides a battery comprising the electrolyte as described above.

[0036] The battery as described above, wherein the battery further comprises a positive active material and a negative active material, the positive active material comprises at least one of lithium cobaltate, lithium iron phosphate and ternary material; or the positive active material comprises at least one of layered oxides, Prussian white, Prussian blue or polyanion material.

[0037] The negative active material comprises at least one of artificial graphite, natural graphite, soft carbon, hard carbon, mesocarbon microbeads, silicon-based material, tin-based material and lithium titanate.

[0038] The application is applied to the electrolyte by combining the compound with formula 1 with the silane additive, and the two are synergized, which can generate SEI film rich in inorganic-organic structure, and can reduce the impedance of the battery, thereby improving the cycle performance and high-temperature performance of the battery.

[0039] The electrolyte of the application comprises the additive composition described above, which can improve the cycle performance and high-temperature performance of the battery.

[0040] The battery of the application is prepared based on the electrolyte as described above, which presents excellent cycle performance and high-temperature performance. DETAILED DESCRIPTION

[0041] To make the purpose, technical solutions and advantages of the application clearer, the technical solutions in the embodiments of the application will be described clearly and completely below in combination with the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0042] The application provides an additive composition, which comprises a first additive and a second additive; the first additive comprises a compound with the structure shown in formula 1:

[0043] wherein R1 is selected from one of -R and -OR, R is selected from one of substituted or unsubstituted C1-C7 alkyl, substituted or unsubstituted C2-C7 alkenyl and substituted or unsubstituted C2-C6 alkynyl; R2-R5 are each independently selected from one of halogen and substituted or unsubstituted C1-C6 alkyl; M is an alkali metal; Y + is a monovalent cation;

[0044] The second additive comprises a silane additive.

[0045] The additive composition of the present application includes a first additive and a second additive, the first additive is a compound having a structure shown in Formula 1, and the second additive includes a silane-based additive. R1 of the present application is selected from one of -R, -OR, and R is selected from one of substituted or unsubstituted C1-C7 alkyl, substituted or unsubstituted C2-C7 alkenyl, and substituted or unsubstituted C2-C6 alkynyl; wherein the substituted or unsubstituted C1-C7 alkyl refers to a chain alkyl having a substitution group or being unsubstituted with a carbon number of 1-7 or a ring alkyl having a substitution group or being unsubstituted with a carbon number of 3-7; the substituted or unsubstituted C2-C7 alkenyl of the present application refers to a chain alkenyl having a substitution group or being unsubstituted with a carbon number of 2-7 or a ring alkenyl having a substitution group or being unsubstituted with a carbon number of 3-7; the substituted or unsubstituted C2-C6 alkynyl of the present application refers to a chain alkynyl having a substitution group or being unsubstituted with a carbon number of 2-6 or a ring alkynyl having a substitution group or being unsubstituted with a carbon number of 3-6; when specified as a hydrocarbon group having a specific carbon number, all geometric isomers having the carbon number are included. The present application does not limit the category of the substitution group, which can be selected according to actual needs, for example, the substitution group can be selected from a halogen atom, a nitrile group, a nitro group, an amino group, a carboxyl group, a hydroxyl group, a thiol group, a formyl group, or a phosphoric acid group, etc., that is, R1 can be selected from -CH3, -CH2CH3, -CF3, -CH=CH2, -CH=CF2, -CH≡C-CH3, -C≡C-CF3, -OCH3, -OCH2CH3, -OCF3, -OCH=CH2, -OCH=CF2, -OCH≡C-CH3, -OC≡C-CF3, -CH2CH2OH, -CH2CH2NH2, etc.

[0046] R2-R5 of the present application are each independently selected from one of halogen, substituted or unsubstituted C1-C6 alkyl; wherein the substituted or unsubstituted C1-C6 alkyl refers to a chain alkyl having a substitution group or being unsubstituted with a carbon number of 1-6 or a ring alkyl having a substitution group or being unsubstituted with a carbon number of 3-7. When specified as a hydrocarbon group having a specific carbon number, all geometric isomers having the carbon number are included. The present application does not limit the category of the substitution group, which can be selected according to actual needs, that is, R2-R5 can be selected from -CH3, -CH2CH3, -CF3, -CH2CH2OH, -CH2CH2NH2, -CH2CH2NO2, -F, -Cl, -Br, etc. M of the present application is an alkali metal, that is, M can be selected from lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

[0047] According to the above-described scheme provided in this application, the additive composition is applied to an electrolyte, which enables the battery to exhibit excellent cycle performance and high-temperature performance. The applicant has analyzed the principle behind this and believes the reason may lie in the synergistic effect of combining a compound having the structure of Formula 1 with a silane-based additive. This synergistic effect generates a more stable SEI film with lower impedance, protecting the negative electrode and preventing side reactions between the electrolyte and the negative electrode, thereby improving the battery's cycle performance and high-temperature performance.

[0048] In one specific embodiment, the silane additive contains unsaturated bonds. In this application, unsaturated bonds refer to covalent bonds formed by atoms sharing more than one pair of electrons, such as carbon-carbon double bonds, carbon-oxygen double bonds, and carbon-nitrogen double bonds. When the silane additive contains unsaturated bonds, it can more easily participate in the construction of the SEI film, thereby more easily generating a dense, stable, and low-impedance SEI film, thus improving the battery's cycle performance and high-temperature performance.

[0049] In one specific embodiment, the second additive includes at least one of the silane additives having the structures shown in Formulas 2, 3, and 4:

[0050] Among them, R6-R 11 Each of the following is independently selected from substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C2-C12 alkenyl, substituted or unsubstituted C2-C12 alkynyl, substituted or unsubstituted C1-C12 alkoxy, substituted or unsubstituted C6-C12 aryl, substituted or unsubstituted C6-C12 aryloxy, R6-R 11 The substituents include one of halogen, amino, and hydroxyl groups, and the silane additive having the structure shown in Formula 2 contains at least two degrees of unsaturation.

[0051] R 12 -R 15 Each of the following is independently selected from substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C2-C12 alkenyl, substituted or unsubstituted C2-C12 alkynyl, substituted or unsubstituted C1-C12 alkoxy, substituted or unsubstituted C6-C12 aryl, substituted or unsubstituted C6-C12 aryloxy, R 12 -R 15 The substituents include one of halogens and hydroxyl groups, and the silane additive having the structure shown in Formula 3 contains at least two degrees of unsaturation.

[0052] R 16 R 17 R 18each independently selected from one of vinyl, methoxyethyl, substituted or unsubstituted C1-C5 alkyl, and having a structure shown in Formula 4, and the silane additive having at least 3 unsaturations.

[0053] R6-R 11 each independently selected from one of substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C2-C12 alkenyl, substituted or unsubstituted C2-C12 alkynyl, substituted or unsubstituted C1-C12 alkoxy, substituted or unsubstituted C6-C12 aryl, substituted or unsubstituted C6-C12 aryloxy, R6-R 11 include one of halogen, amino, hydroxyl. Wherein, the substituted or unsubstituted C1-C12 alkyl of the present application refers to a chain alkyl having a substituent or being unsubstituted with carbon number of 1-12, or a cyclic alkyl having a substituent or being unsubstituted with carbon number of 3-12; the substituted or unsubstituted C2-C12 alkenyl of the present application refers to a chain alkenyl having a substituent or being unsubstituted with carbon number of 2-12, or a cyclic alkenyl having a substituent or being unsubstituted with carbon number of 3-12; the substituted or unsubstituted C2-C12 alkynyl of the present application refers to a chain alkynyl having a substituent or being unsubstituted with carbon number of 2-12, or a cyclic alkynyl having a substituent or being unsubstituted with carbon number of 3-12; the substituted or unsubstituted C1-C12 alkoxy of the present application refers to an alkoxy having a substituent or being unsubstituted with carbon number of 1-12; the substituted or unsubstituted C6-C12 aryl of the present application refers to an aryl having a substituent or being unsubstituted with carbon number of 6-12; the substituted or unsubstituted C6-C12 aryloxy of the present application refers to an aryloxy having a substituent or being unsubstituted with carbon number of 6-12; the substituent of the present application includes one of halogen, amino, hydroxyl. When specified as a hydrocarbon group with a specific carbon number, all geometric isomers with the carbon number are included. For example, R6-R 11 may each independently be selected from -CH3, -CH2CH3, -CF3, -CH=CH2, -CH=CF2, -CH≡C-CH3, -C≡C-CF3, -OCH3, -OCH2CH3, -OCF3, -C6H5, -CH2-C6H5, -OC6H5, -OCH2C6H5, -CCl3, -CH2CH2NH2, -CH2CH2OH, and the like. The silane additive having a structure shown in Formula 2 of the present application has at least 2 unsaturations, for example, at least two carbon-carbon double bonds, or at least one carbon-carbon triple bond, or at least one phenyl group, and the like, in the silane additive of Formula 2.

[0054] R6-R 12 -R 15each independently selected from the group consisting of substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C2-C12 alkenyl, substituted or unsubstituted C2-C12 alkynyl, substituted or unsubstituted C1-C12 alkoxy, substituted or unsubstituted C6-C12 aryl, substituted or unsubstituted C6-C12 aryloxy, R 12 -R 15 The substituents in -R 11 include one of halogen, hydroxyl, and the silane additive having the structure of Formula 3 contains at least two degrees of unsaturation. In the present application, the substituted or unsubstituted C1-C12 alkyl refers to a chain alkyl having a substituent or being unsubstituted with a carbon number of 1-12, or a cyclic alkyl having a substituent or being unsubstituted with a carbon number of 3-12; the substituted or unsubstituted C2-C12 alkenyl refers to a chain alkenyl having a substituent or being unsubstituted with a carbon number of 2-12, or a cyclic alkenyl having a substituent or being unsubstituted with a carbon number of 3-12; the substituted or unsubstituted C2-C12 alkynyl refers to a chain alkynyl having a substituent or being unsubstituted with a carbon number of 2-12, or a cyclic alkynyl having a substituent or being unsubstituted with a carbon number of 3-12; the substituted or unsubstituted C1-C12 alkoxy refers to an alkoxy having a substituent or being unsubstituted with a carbon number of 1-12; the substituted or unsubstituted C6-C12 aryl refers to an aryl having a substituent or being unsubstituted with a carbon number of 6-12; the substituted or unsubstituted C6-C12 aryloxy refers to an aryloxy having a substituent or being unsubstituted with a carbon number of 6-12; the substituents in the present application include one of halogen, hydroxyl, for example, can be selected from fluorine, chlorine, bromine, iodine, hydroxyl. When specified as a hydrocarbon group having a specific carbon number, all geometric isomers having the carbon number are included. For example, R 16 , R 17 , R 18 each independently selected from the group consisting of -CH3, -CH2CH3, -CF3, -CH=CH2, -CH=CF2, -CH≡C-CH3, -C≡C-CF3, -OCH3, -OCH2CH3, -OCF3, -C6H5, -CH2-C6H5, -OC6H5, -OCH2C6H5, -CH2CH2OH, and the like. The silane additive having the structure of Formula 3 in the present application contains at least two degrees of unsaturation, for example, contains at least two carbon-carbon double bonds, or at least one carbon-carbon triple bond, or at least one phenyl group, and the like, in the silane additive of Formula 3.

[0055] The R 16 , R 17 , R 18The silane additive having at least 3 unsaturations independently selected from one of vinyl, methoxyethyl, substituted or unsubstituted C1-C5 alkyl, and having the structure of Formula 4. Herein, the substituted or unsubstituted C1-C5 alkyl refers to a chain alkyl having a substitution group or being unsubstituted having a carbon number of 1-5, or a cyclic alkyl having a substitution group or being unsubstituted having a carbon number of 3-5. The type of substitution group is not limited herein and can be selected as desired. When a hydrocarbon group having a specific carbon number is specified, all geometric isomers having that carbon number are included. For example, R 16 , R 17 , R 18 may be independently selected from -CH3, -CH2CH3, -CF3, -CH2CH2OH, -CH2CH2NH2, -CH=CH2, -CH2CH2OCH3, and the like.

[0056] According to the above scheme provided in the present application, when the second additive comprises at least one of the compounds of formula 2, formula 3, formula 4, the lithium ion battery has excellent cycle performance and high temperature performance. The applicant analyzes the principle and considers that the reason may be that the silane additive with formula 2 structure can react with trace water and HF in the electrolyte, inhibit the decomposition of trace water and HF on the electrolyte, improve the stability of the electrolyte, thereby inhibiting the gas production problem of the battery; the silane additive with formula 3 structure contains at least two unsaturations, which can form a network or a three-dimensional crosslinking, thereby forming a more dense and stable SEI film on the electrode surface, avoiding the entry of lithium ions into the negative electrode, improving the cycle performance of the battery, and avoiding the side reaction of the electrolyte with the positive electrode and the negative electrode, thereby inhibiting the gas production of the battery and improving the high temperature performance of the battery; the silane additive with formula 4 structure can reduce the acidity of the electrolyte, avoid the damage of acidic substances in the electrolyte to the active material in the positive and negative electrodes and the accelerated decomposition of the electrolyte, thereby inhibiting the high temperature gas production of the battery, and the SEI film formed therein has a P-O-Si special structure, which is beneficial to the removal of peroxide ions in the electrolyte. However, the common feature of the second additive is that the SEI film formed by the Si-O bond or C=C bond or P—O—Si structure is too dense, which leads to too high impedance of the overall battery. In order to modify the SEI film formed by the second additive, the first additive is introduced, the LUMO energy level of the first additive is lower, it is easier to be reduced before the solvent, and the SEI film forming potential of the first additive is earlier than that of the second additive, which can form a uniform inorganic matter dominated SEI interface rich in sulfate and phosphate before the second additive. Then the second additive can continue to form a film on the SEI film rich in inorganic matter formed by the first additive, forming an inorganic matter + organic matter layer, and the thickness of the inorganic matter + organic matter layer is uniform and moderate, thereby reducing the impedance of the battery. That is, the compound with formula 1 is combined with at least one of the silane additives with formula 2, formula 3, formula 4, so that the two can synergistically act to hinder the entry of lithium ions into the negative electrode, thereby improving the capacity retention rate of the battery and improving the cycle performance of the battery. Compared with the SEI film formed by a single additive, the structure of the SEI film is more stable and the impedance is lower, thereby avoiding the side reaction of the electrolyte with the negative electrode, improving the cycle performance and high temperature performance of the battery.

[0057] In a particular embodiment, R1 is selected from one of substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C2-C6 alkenyl; at least one of R2-R5 comprises a halogen; M is selected from one of Li, Na, K; Y + is N + R a R b R c R d , R a-R d each independently selected from one of H, halogen, substituted or unsubstituted C1-C7 alkyl, substituted or unsubstituted C2-C7 alkenyl, substituted or unsubstituted C2-C6 alkynyl, R a -R d at least one of which is hydrogen.

[0058] R a -R d at least one of which is hydrogen means that R a -R d at least one of which is hydrogen, and the remaining three functional groups are each independently selected from one of halogen, substituted or unsubstituted C1-C7 alkyl, substituted or unsubstituted C2-C7 alkenyl, substituted or unsubstituted C2-C6 alkynyl.

[0059] When the first additive comprises a compound having the above structural formula, the first additive can further synergize with the second additive to generate a more uniform and lower impedance SEI film, thereby further reducing the impedance of the battery and further improving the cycle performance of the battery.

[0060] In one embodiment, R1 is selected from substituted or unsubstituted C2-C6 alkenyl; R2-R5 are each independently selected from halogen; M is Li; Y + is N + R a R b R c R d , R a is hydrogen, R b -R d are each independently selected from C1-C3 alkyl. When the first additive comprises a compound having the above structural formula, a SEI film with higher lithium conductivity and more stable structure can be generated, thereby making the cycle performance of the battery more optimal.

[0061] In one embodiment, R6-R 11 at least two carbon-carbon double bonds. When the second additive comprises a silane additive of Formula 2 having the above structural formula, the carbon-carbon double bonds in the silane additive of Formula 2 can improve the reducing capacity of the silane additive of Formula 2, thereby further improving the thermal stability of the silane additive of Formula 2 and the thermal stability of the electrolyte to a greater extent. After being used in combination with the first additive, the silane additive of Formula 2 can further synergize with the first additive to form a SEI film with more stable structure and lower impedance, thereby making the battery exhibit more optimal high-temperature performance.

[0062] In one embodiment, R 12 -R 15The silane additive of formula 3 includes at least two carbon-carbon double bonds. When the silane additive of formula 3 has the above structure, the silane additive of formula 3 can form more stable network or three-dimensional cross-linking, thereby participating in the construction of a more compact and stable SEI film, more effectively preventing lithium ions from entering the interior of the negative electrode and preventing the production of gas from the electrolyte, and better synergizing with the first additive to improve the cycle performance and high-temperature performance of the battery.

[0063] In a specific embodiment, the silane additive of the structure of formula 4 includes at least three carbon-carbon double bonds. When the silane additive of formula 4 has the above structure, the silane additive of formula 4 can further reduce the acidity of the electrolyte, more effectively inhibit the high-temperature gas production of the battery, improve the high-temperature performance of the battery, more effectively remove lithium oxides and peroxide ions in the electrolyte, and better combine with the additive of formula 1 to further improve the cycle performance and high-temperature performance of the battery.

[0064] In a specific embodiment, the first additive includes a compound of the structure of formula 5 to formula 8:

[0065] When the first additive includes at least one of the compounds of the structure of formula 5 to formula 8, it can dissociate into a corresponding nitrogen-containing cation group and an anion containing lithium difluorophosphate and vinyl sulfuric acid in water. The nitrogen-containing cation group has the effect of adjusting the acidity and alkalinity of the electrolyte and improving the electrical conductivity, and the dissociation increases the free lithium ions in the solution, thereby improving the cycle performance of the battery. When R2, R3, R4, and R5 are F atoms, a difluorophosphate group is introduced, and esters of the difluorophosphate group have a certain impedance reduction effect, thereby further improving the performance of the compound of the structure of formula 5 to formula 8 in reducing the impedance of the battery. Therefore, the first additive can further synergize with the second additive to generate SEI films and CEI films with lower impedance and more uniform structure, thereby further improving the cycle performance and high-temperature performance of the battery.

[0066] When the first additive includes a compound of the structure of formula 5, the triethylamine salt is a strong base weak acid salt and has ionicity, which can dissociate into triethylamine and an anion containing lithium difluorophosphate and vinyl sulfuric acid in water. This property enables the triethylamine salt to have the effect of adjusting the acidity and alkalinity of the electrolyte and improving the electrical conductivity, and the dissociation increases the free lithium ions in the solution, thereby improving the cycle performance of the battery. When R2, R3, R4, and R5 are F atoms, a difluorophosphate group is introduced, and esters of the difluorophosphate group have a certain impedance reduction effect, thereby further improving the performance of the compound of the structure of formula 5 in reducing the impedance of the battery. Therefore, the compound of formula 5 can further synergize with the second additive to generate SEI films and CEI films with lower impedance and more uniform structure, thereby further improving the cycle performance and high-temperature performance of the battery.

[0067] In one specific embodiment, the silane additive having the structure of Formula 2 includes at least one of tetramethyldivinyldisiloxane, dimethyltetravinyl disiloxane, dimethyldivinyl difluorocarbosiloxane, divinyl tetrafluorocarbosiloxane. When the silane additive having the structure of Formula 2 is selected from the above-mentioned silane additives, the silane additive has higher thermal stability, thereby being able to more greatly improve the thermal stability of the electrolyte, avoid the gas production problem of the battery, and make the high-temperature performance of the battery more optimal; meanwhile, the silane additive is able to be used in combination with the first additive to generate an SEI film with lower impedance and more dense and uniform, thereby further improving the cycle performance of the battery.

[0068] In one specific embodiment, the silane additive having the structure of Formula 3 includes at least one of divinyl dimethylsilane, trivinyl methylsilane, and tetra-vinyl silane. When the silane additive of Formula 3 is selected from the above-mentioned compounds, the silane additive is able to further match the compounds of Formula 1 and Formula 2 to generate an SEI film with lower impedance and more dense and uniform, and is also able to generate a CEI film with more optimal performance, more greatly inhibit the side reactions occurring when the positive and negative electrodes contact the electrolyte, and thereby more greatly improve the cycle performance and high-temperature performance of the battery.

[0069] In one specific embodiment, the silane additive having the structure of Formula 4 includes at least one of tris(dimethylvinylsilyl) phosphate, bis(dimethylvinylsilyl) methoxy phosphate, tris(dimethyl(methoxyethyl)silyl) phosphate, bis(dimethyl(methoxyethyl)silyl) methoxy phosphate, dimethylvinylsilyl) phosphate dimer, and bis(dimethyl(methoxyethyl)silyl) phosphate dimer. When the silane additive of Formula 4 is selected from the above-mentioned compounds, the silane additive of Formula 4 is able to better combine with the hydrofluoric acid in the electrolyte, more greatly reduce the acidity of the electrolyte, thereby further avoid the influence of the hydrofluoric acid on the positive and negative active materials and the electrolyte, inhibit the gas production of the battery, make the high-temperature performance of the battery more optimal, and simultaneously generate SEI films and CEI films with higher lithium-ion conductivity, and more greatly improve the cycle performance of the battery.

[0070] The application also provides an electrolyte including a lithium salt or a sodium salt, an organic solvent, and the above-mentioned additive composition.

[0071] If the electrolyte of the present application is applied to a lithium ion battery, the electrolyte of the present application includes a lithium salt and an organic solvent, wherein the lithium salt can be a lithium salt commonly used in the art, such as lithium hexafluorophosphate, lithium bisfluorosulfonylimide, lithium tetrafluoroborate, and lithium difluoro(oxalato)borate, etc., and the present application does not make too many choices. If the electrolyte of the present application is applied to a sodium ion battery, the electrolyte of the present application includes a sodium salt and an organic solvent, wherein the sodium salt can be a sodium salt commonly used in the art, such as sodium hexafluorophosphate, sodium perchlorate, and sodium bisfluorosulfonylimide. The organic solvent is used to dissolve the lithium salt or the sodium salt to prepare an electrolyte with good conductivity, which can be an organic solvent commonly used in the art, such as carbonates, carboxylic acid esters, and ethers, etc., and the present application does not make too many choices.

[0072] When the electrolyte includes the above-mentioned additive composition, the electrolyte can improve the cycle performance and high-temperature performance of the battery.

[0073] In a specific embodiment, the mass percentage content of the first additive in the electrolyte is 0.1-3%, such as 0.1%, 0.25%, 0.5%, 0.75%, 1%, 1.25%, 1.5%, 1.75%, 2%, 2.25%, 2.5%, 2.75%, or 3%, etc.; and / or, the mass percentage content of the second additive in the electrolyte is 0.03-3%, such as 0.03%, 0.05%, 0.1%, 0.25%, 0.5%, 0.75%, 1%, 1.25%, 1.5%, 1.75%, 2%, 2.25%, 2.5%, 2.75%, or 3%, etc. When the first additive and the second additive are respectively within the above-mentioned range, the first additive and the second additive further synergize to generate an SEI film with lower impedance and more stable structure, further avoiding side reactions between the electrolyte and the negative electrode, thereby making the cycle performance of the battery more optimal, and more effectively inhibiting the gas generation problem of the battery, further improving the high-temperature performance of the battery.

[0074] In a specific embodiment, the second additive includes a silane additive with the structure shown in Formula 2 and Formula 3, and the mass ratio of the silane additives shown in Formula 2 and Formula 3 is (1.5-2.0):1, such as 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, or 2.0:1, etc. When the second additive includes the silane additives of Formula 2 and Formula 3, and the mass ratio is within the above-mentioned range, the compounds of Formula 1, Formula 2, and Formula 3 further synergize, making the lithium-conducting performance of the generated SEI film more optimal, thereby making the impedance of the battery lower and the cycle performance more optimal, while improving the thermal stability of the electrolyte, thereby improving the high-temperature performance of the battery, and generating a CEI film with more optimal performance, further improving the cycle performance of the battery.

[0075] In one embodiment, the second additive comprises a silane additive having the structure of Formula 2, Formula 4, and the mass ratio of the silane additive of Formula 2, Formula 4 is (0.5-1.5):1, for example, the mass ratio of the silane additive of Formula 2, Formula 4 is 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5:1, etc. When the second additive comprises the silane additive of Formula 2, Formula 4, and the mass ratio is within the above range, the compounds of Formula 1, Formula 2, Formula 4 further synergize, so that the lithium-conducting properties of the SEI film and the CEI film of the battery are more optimal, and the thermal stability of the electrolyte and the acidity of the battery can be further improved, thereby more greatly improving the cycle performance and high-temperature performance of the battery.

[0076] In one embodiment, the second additive comprises a silane additive having the structure of Formula 3, Formula 4, and the mass ratio of the silane additive of Formula 3, Formula 4 is (0.5-1.5):1, for example, the mass ratio of the silane additive of Formula 3, Formula 4 is 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5:1, etc. When the second additive comprises the silane additive of Formula 3, Formula 4, and the mass ratio is within the above range, the compounds of Formula 1, Formula 3, Formula 4 further synergize, so that the lithium-conducting properties of the SEI film and the CEI film of the battery are more optimal, and the SEI film and the CEI film are more dense and stable, and the acidity of the battery and the lithium oxide and superoxide ion in the electrolyte can be further reduced, thereby more greatly improving the cycle performance and high-temperature performance of the battery.

[0077] In one embodiment, the second additive comprises silane additives having the structures shown in Formula 2, Formula 3, and Formula 4, and the mass ratio of the silane additives shown in Formula 2, Formula 3, and Formula 4 is (0.5-1.5):(0.5-1.5):1, such as 0.5:0.5:1, 0.6:0.6:1, 0.7:0.7:1, 0.8:0.8:1, 0.9:0.9:1, 1:1:1, 1.1:1.1:1, 1.2:1.2:1, 1.3:1.3:1, 1.4:1.4:1, 1.5:1.5:1, 0.5:1.5:1, 0.5:1:1, 1:0.5:1, 1:1.5:1, 1.5:0.5:1, 1.5:1:1, etc. When the second additive comprises silane additives shown in Formula 2, Formula 3, and Formula 4, and the mass ratio is within the above range, the compounds shown in Formula 1, Formula 2, Formula 3, and Formula 4 further synergize, and the SEI film and CEI film with lower impedance can be formed, and the stability of the electrolyte can be improved, and the acidity of the battery can be reduced to a greater extent, so that the battery exhibits better cycle performance and high-temperature performance.

[0078] In one embodiment, the electrolyte further comprises an auxiliary additive, and the auxiliary additive comprises at least one of 1,3-propane sultone (PS), fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propene sultone (PST), tris(trimethylsilyl) phosphate (TMSP), tris(trimethylsilyl) borate (TMSB), vinyl sulfate (DTD), lithium difluorodioxalate phosphate (LiODFP), lithium difluorophosphate (LiPO2F2), lithium difluorophosphate borate (LiODFB), and ethylene sulfite (ES). When the above-mentioned additive is further added to the electrolyte, the performance of the SEI film can be further improved, so that the SEI film has lower impedance and a more stable structure, thereby further improving the cycle performance and high-temperature performance of the battery.

[0079] In one embodiment, the mass percentage of the auxiliary additive in the electrolyte is 0.03-3.2%, such as 0.03%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or 3.2%. When the mass percentage of the auxiliary additive is within the above range, the auxiliary additive can further synergize with the first additive and the second additive, so that the SEI film of the battery has better performance, thereby making the battery exhibit higher cycle performance and high-temperature performance.

[0080] In one embodiment, the electrolyte of the present application further comprises a lithium salt or a sodium salt. The present application does not limit the specific selection of the lithium salt or the sodium salt, for example, the lithium salt can include at least one of LiPF6, LiBF4, LiFSI, LiTFSI, LiAsF6, LiClO4, LiCF3SO3, LiBOB, LiTDI, and Li2PFO3, and the sodium salt can include at least one of sodium perchlorate, sodium bis(oxalate)borate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide, and sodium bis(fluoro sulfonyl)imide. The addition of the lithium salt or the sodium salt can improve the conductivity and stability of the electrolyte, thereby improving the cycle performance of the battery. When the electrolyte is applied to a lithium ion battery, the mass percentage of the lithium salt in the electrolyte is 12-18%, for example, 12%, 13%, 14%, 15%, 16%, 17%, or 18%. When the electrolyte is applied to a sodium ion battery, the mass percentage of the sodium salt in the electrolyte is 12-18%. When the lithium salt or the sodium salt is within the above range, the conductivity and stability of the electrolyte can be further improved, thereby further improving the cycle performance of the battery.

[0081] In one embodiment, the electrolyte of the present application further comprises an organic solvent, which includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl propionate, propyl propionate, methyl acetate, ethyl acetate, propyl acetate, and methyl propionate. When the above-mentioned solvent is selected as the electrolyte solvent, the solubility of the lithium salt in the electrolyte can be improved, and the conductivity of the electrolyte can be improved, thereby further improving the cycle performance of the battery. The mass percentage of the organic solvent in the electrolyte is 50-80%, for example, 50%, 55%, 60%, 65%, 70%, 75%, or 80%. When the mass percentage of the organic solvent is within the above range, the conductivity of the electrolyte can be further improved, thereby further improving the cycle performance of the battery.

[0082] The present application also provides a battery comprising the above-mentioned electrolyte. The battery exhibits excellent cycle performance and high-temperature performance.

[0083] In one embodiment, in addition to the electrolyte provided by the present application, a positive electrode sheet, a negative electrode sheet, and a separator are further included. During the charging and discharging process of the battery, active ions are embedded and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuiting between the positive electrode and the negative electrode, while allowing ions to pass through. Specifically:

[0084] The positive electrode tab includes a positive electrode current collector and a positive electrode active material layer arranged on the surface of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material, and the mass fraction of nickel element in the positive electrode active material is greater than or equal to 40%. When the mass fraction of nickel element in the positive electrode active material is in the above range, the cost of the positive electrode active material is low, and the specific capacity is obviously improved. However, the thermal stability of the positive electrode active material with high nickel content is poor, and transition metal dissolution and micro-cracks occur at high temperature. By using the above electrolyte, a uniform and strong CEI film can be formed in situ on the positive electrode active material, and a uniform and strong SEI film can be formed on the surface of the negative electrode active material. While achieving low cost and high capacity, the cycle performance of the battery is also effectively improved.

[0085] In a specific embodiment, when the battery is a lithium ion battery, the positive electrode active material includes at least one of lithium cobaltate, lithium iron phosphate and ternary material.

[0086] Further, the positive electrode active material satisfies the general formula Li a Ni b Co c M1 d M2 e O f R g , wherein 1≤a≤1.2, 0.6<b<1, 0<c<1, 0<d<1, 0≤e≤0.2, b+c+d+e=1, 1≤f≤2, 0≤g≤1, f+g=2; M1 includes Mn and / or Al, M2 includes at least one of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb, and R includes at least one of N, F, S and Cl.

[0087] Further, the positive electrode active material includes LiNi 0.7 Co 0.1 Mn 0.2 O2(NCM712), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.9 Co 0.05 Mn 0.05 O2.

[0088] In a specific embodiment, when the battery is a sodium ion battery, the positive electrode active material includes at least one of layered oxide, Prussian white, Prussian blue or polyanion material.

[0089] Further, the positive electrode active material includes Nax1 M1O2, Na x2 at least one of M2[M3(CN)6], NaFePO4, Na3V2(PO4)3, Na2M4P2O7, Na2Fe2(SO4)3, Na2M4(SO4)2·2H2O, wherein: 0 < x1≤ 1, M1 includes at least one of Ni, Co, Mn, Fe, Cu, 0 < x2< 6, M2 includes at least one of Ni, Fe, Mn, M3 includes at least one of Fe, Mn, M4 includes at least one of Fe, Co, Mn, Cu.

[0090] Further, the positive active material includes at least one of NaNiO2, NaFeO2, Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2, Na 2 / 3 Fe 1 / 2 Mn 1 / 2 O2.

[0091] In one embodiment, the positive current collector includes a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be used. The composite current collector includes 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 (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0092] In one embodiment, the positive active material layer further includes a binder including at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic ester resin.

[0093] In one embodiment, the positive active material layer further includes a conductive agent. For example, the conductive agent includes at least one of super P, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0094] The negative electrode tab includes a negative current collector and a negative active material layer disposed on a surface of the negative current collector, the negative active material layer including a negative active material. The negative active material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon, mesocarbon microbeads, silicon-based material, tin-based material, and lithium titanate.

[0095] In a specific embodiment, the negative active material layer can further include a binder, a conductive agent, and other additives. For example, the binder can include at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS); the conductive agent includes at least one of super-p, acetylene black, carbon black, ketjen black, carbon dots, single-walled carbon nanotubes, graphene, and carbon nanofibers; and the additive includes a thickening agent such as sodium carboxymethyl cellulose (CMC-Na) or the like.

[0096] The type of the separation film is not particularly limited in the present application, and any porous structure separation film having good chemical stability and mechanical stability can be selected. For example, the material of the separation film includes at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separation film can be a single layer film or a multi-layer composite film.

[0097] The battery of the present application can include a battery cell form, a battery module form, and a battery pack form.

[0098] Example 1

[0099] The electrolyte provided by the present embodiment includes: a lithium salt lithium hexafluorophosphate with a mass percentage of 14.5%, an organic solvent including EC, PC, EMC, and DEC with a mass ratio of EC:PC:EMC:DEC = 1.5:1.5:5:2, a compound (CAS: 2681338-34-9) with a structure shown in Formula 5 with a mass percentage of 0.3%, and tetramethyldivinyldisiloxane with a mass percentage of 0.05%.

[0100] The preparation method of the electrolyte of the present embodiment includes: in an argon-filled glove box (moisture <10 ppm, oxygen <1 ppm), mixing the solvents EC:PC:EMC:DEC uniformly according to a mass ratio of 1.5:1.5:5:2, rapidly adding lithium salt and additives into the mixed solvent, and uniformly mixing and stirring to obtain the electrolyte.

[0101] The electrolyte formulations provided by Examples 1-88 and Comparative Examples 1-5 are basically the same as those of Example 1, and the specific parameters are shown in Table 1.

[0102] Table 1

[0103] Note: " / " in Table 1 indicates that the corresponding substance or parameter does not exist.

[0104] Test Example 1

[0105] Preparation of positive electrode sheet: the positive electrode active material NCM811, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black were mixed in a weight ratio of 96.5:2:1.5, N-methyl pyrrolidone (NMP) was added, and stirring was performed under the action of a vacuum stirrer until the mixed system became a positive electrode slurry with uniform fluidity; the positive electrode slurry was uniformly coated on an aluminum foil with a thickness of 7 μm; the aluminum foil coated with the positive electrode slurry was dried in an oven at 120 °C for 8 h. Finally, after rolling, the positive electrode sheet was controlled to have a compaction density of 3.5 g / cm 3 , and the positive electrode sheet was obtained by slitting.

[0106] Preparation of negative electrode sheet: the negative electrode active material artificial graphite, the thickening agent sodium carboxymethyl cellulose (CMC-Na), the binder styrene-butadiene rubber, the conductive agent acetylene black, and the conductive agent single-walled carbon nanotube were mixed in a weight ratio of 95.9:1:2:1:0.1, deionized water was added, and a negative electrode slurry was obtained under the action of a vacuum stirrer; the negative electrode slurry was uniformly coated on a copper foil with a thickness of 6 μm; the copper foil coated with the negative electrode slurry was dried at 85 °C for 5 h. Finally, after rolling, the negative electrode sheet was controlled to have a compaction density of 1.5 g / cm 3 , and the negative electrode sheet was obtained by slitting.

[0107] A polyethylene separator film with a thickness of 8 μm was selected.

[0108] Preparation of lithium ion battery: the positive electrode sheet, the separator film, and the negative electrode sheet prepared above were wound to obtain a bare cell without liquid injection; the bare cell was placed in an outer package, and the electrolyte of Example 1-75, Example 77-88, and Comparative Example 1-5 above was injected into the dried bare cell, and the lithium ion battery was obtained after processes such as vacuum packaging, standing, formation, shaping, and sorting.

[0109] Test Example 2

[0110] Preparation of positive electrode sheet: the positive electrode active material Na[Ni 1 / 3 Fe 1 / 3 Mn 1 / 3 ]O2, the conductive agent carbon black, the carbon nanotube, and the binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 94.5:3.5:1.8:0.2, N-methyl pyrrolidone (NMP) was added, and stirring was performed under the action of a vacuum stirrer until the mixed system became a positive electrode slurry with uniform fluidity; the positive electrode slurry was uniformly coated on an aluminum foil with a thickness of 7 μm; the aluminum foil coated with the positive electrode slurry was dried in an oven at 120 °C for 8 h. Finally, after rolling, the positive electrode sheet was controlled to have a compaction density of 3.5 g / cm 3 , and the positive electrode sheet was obtained by slitting.

[0111] Negative electrode sheet preparation: the negative active material hard carbon, thickening agent (CMC), binder styrene-butadiene rubber, and conductive agent carbon black were mixed in a weight ratio of 95:2:1.5:1.5, deionized water was added, and a negative electrode slurry was obtained under the action of a vacuum stirrer; the negative electrode slurry was uniformly coated on a copper foil with a thickness of 6 μm; the copper foil coated with the negative electrode slurry was dried at 85 °C for 5 h. Finally, the negative electrode sheet was obtained by rolling, and the compaction density of the negative electrode sheet was controlled to be 1.5 g / cm3. 3 The negative electrode sheet was obtained by slitting.

[0112] A polyethylene separator film with a thickness of 8 μm was selected.

[0113] Sodium ion battery preparation: the prepared positive electrode sheet, separator film, and negative electrode sheet were wound to obtain a non-liquid-injected bare cell; the bare cell was placed in an outer package, the electrolyte of Example 76 was injected into the dried bare cell, and the sodium ion battery was obtained by vacuum packaging, standing, formation, shaping, sorting, and other processes.

[0114] Test Example 3

[0115] The batteries in Examples 1-88 and Comparative Examples 1-5 were subjected to electrochemical performance tests, and the test results are shown in Table 2:

[0116] 1. 60 °C storage test: the battery was placed in a 25 °C environment, discharged at 1C constant current to a cutoff voltage of 2.5 V, and then rested for 5 min; the battery was then charged at 1C constant current and constant voltage to an upper limit voltage of 4.5 V, and the cutoff current was 0.05C; the initial full-charge soft package battery was immersed in a liquid, and the mass of the discharged liquid was calculated by the drainage method as m1; the battery was placed in a 60 °C high-temperature oven for 20 days, and the mass of the discharged liquid was measured as m2; the calculation formula is as follows: gas production (ml) = (m2-m1) / p.

[0117] 2. 25 °C ambient temperature cycle test: the battery was placed in a 25 °C environment and rested for 3 h; then the battery was charged at 1C constant current and constant voltage to an upper limit voltage of 4.5 V, and the cutoff current was 0.05C; the battery was fully charged and rested for 5 min; then the battery was discharged at 1C constant current to a cutoff voltage of 2.5 V; the highest discharge capacity of the first 3 cycles was recorded as the initial capacity Q1; when the cycle reached 500 times, the last discharge capacity Q2 of the battery was recorded. The calculation formula is as follows: capacity retention rate (%) = Q2 / Q1 x 100%.

[0118] Table 2

[0119] As can be seen from Table 2, according to the comparison of Examples 1-48, Examples 77-81, Examples 84-86 and Comparative Examples 1-4, and the comparison of Examples 49-65 and Comparative Example 5, the first additive and the second additive can synergistically work to make the cycle performance and high-temperature performance of the battery better; according to the comparison of Examples 66-71, 75, 82 and 83, the addition of the third additive can further improve the cycle performance and high-temperature performance of the battery; according to the comparison of Examples 72-74, when the mass percentage content of the lithium salt is in the range of 12-18%, the cycle performance and high-temperature performance of the battery can be further improved. In summary, the electrolyte provided by the present application can significantly improve the cycle performance and high-temperature performance of the battery.

[0120] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An additive composition characterized in that, The additive composition includes a first additive and a second additive; the first additive includes a compound having a structure shown in Formula 1: wherein R1is selected from one of -R, -OR, R is selected from one of substituted or unsubstituted C1-C7alkyl, substituted or unsubstituted C2-C7alkenyl, substituted or unsubstituted C2-C6alkynyl; R2-R5are each independently selected from one of halogen, substituted or unsubstituted C1-C6alkyl; M is an alkali metal; Y + is a monovalent cation; The second additive comprises a silane-based additive.

2. The additive composition of claim 1, wherein The silane-based additive contains an unsaturated bond.

3. The additive composition of claim 2, wherein The second additive includes at least one of silane additives having structures shown in Formula 2, Formula 3, Formula 4: Among them, R6-R 11 Each of the following is independently selected from substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C2-C12 alkenyl, substituted or unsubstituted C2-C12 alkynyl, substituted or unsubstituted C1-C12 alkoxy, substituted or unsubstituted C6-C12 aryl, substituted or unsubstituted C6-C12 aryloxy, R6-R 11 The substituents include one of halogen, amino, and hydroxyl groups, and the silane additive having the structure shown in Formula 2 contains at least two degrees of unsaturation. R 12 -R 15 each independently selected from substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C2-C12 alkenyl, substituted or unsubstituted C2-C12 alkynyl, substituted or unsubstituted C1-C12 alkoxy, substituted or unsubstituted C6-C12 aryl, substituted or unsubstituted C6-C12 aryloxy, R 12 -R 15 substituents in -R include one of halogen, hydroxyl, and the silane additive having the structure shown in Formula 3 contains at least 2 unsaturations. R 16 , R 17 , R 18 each independently is selected from one of vinyl, methoxyethyl, substituted or unsubstituted C1-C5 alkyl, and the silane additive having the structure of Formula 4 contains at least 3 unsaturations.

4. The additive composition according to any one of claims 1 to 3, characterized in that, R1is selected from one of substituted or unsubstituted C1-C6alkyl, substituted or unsubstituted C2-C6alkenyl; at least one of R2-R5comprises a halogen; M is selected from one of Li, Na, K; Y + is N + R a R b R c R d , R a -R d each independently selected from one of H, halogen, substituted or unsubstituted C1-C7alkyl, substituted or unsubstituted C2-C7alkenyl, substituted or unsubstituted C2-C6alkynyl, R a -R d comprises at least one hydrogen.

5. The additive composition of claim 4, wherein R1is selected from substituted or unsubstituted C2-C6alkenyl; R2-R5are each independently selected from halogen; M is Li; Y + is N + R a R b R c R d , R a is hydrogen, R b -R d are each independently selected from C1-C3alkyl.

6. The additive composition of any one of claims 2, 3, 5, wherein, R6-R 11 comprising at least two carbon-carbon double bonds; and / or, R 12 -R 15 comprising at least two carbon-carbon double bonds; And / or, the silane additive with the structure shown in formula 4 contains at least three carbon-carbon double bonds.

7. The additive composition according to any one of claims 1 to 3, 5, characterized in that, The first additive includes a compound having a structure according to Formula 5 to Formula 8:

8. The additive composition of any one of claim 7, characterized in that, The silane additive with the structure shown in formula 2 comprises at least one of tetramethyldivinyl disiloxane, dimethyltetra-vinyl disiloxane, dimethyl divinyl difluorocarbon-based siloxane, di-vinyl tetrafluorocarbon-based siloxane; And / or, the silane additive with the structure shown in formula 3 comprises at least one of di-vinyl dimethyl silane, tri-vinyl methyl silane, tetra-vinyl silane; And / or, the silane additive with the structure shown in formula 4 comprises at least one of tris(dimethyl vinyl silyl) phosphate, bis(dimethyl vinyl silyl) methoxy phosphate, tris(dimethyl(methoxy ethyl) silyl) phosphate, bis(dimethyl(methoxy ethyl) silyl) methoxy phosphate, di(dimethyl vinyl silyl) phosphate dimer, and di(dimethyl(methoxy ethyl) silyl) phosphate dimer.

9. An electrolyte, characterized by The electrolyte comprises a lithium salt or a sodium salt, an organic solvent, and the additive composition of any one of claims 1-8.

10. The electrolyte of claim 9, wherein, The mass percentage content of the first additive in the electrolyte is 0.1-3%; and / or, The mass percentage content of the second additive in the electrolyte is 0.03-3%.

11. The electrolyte according to claim 9 or 10, characterized in that The second additive contains silane additives with the structures shown in formula 2 and formula 3, and the mass ratio of the silane additives with the structures shown in formula 2 and formula 3 is (1.5-2.0):1; And / or, the second additive contains silane additives with the structures shown in formula 2 and formula 4, and the mass ratio of the silane additives with the structures shown in formula 2 and formula 4 is (0.5-1.5):1; And / or, the second additive contains silane additives with the structures shown in formula 3 and formula 4, and the mass ratio of the silane additives with the structures shown in formula 3 and formula 4 is (0.5-1.5):1; And / or, the second additive contains silane additives with the structures shown in formula 2, formula 3, and formula 4, and the mass ratio of the silane additives with the structures shown in formula 2, formula 3, and formula 4 is (0.5-1.5):(0.5-1.5):

1.

12. The electrolyte according to any one of claims 9 to 11, characterized in that, The electrolyte further comprises an auxiliary additive, and the auxiliary additive comprises at least one of 1,3-propane sultone, fluoroethylene carbonate, vinylene carbonate, 1,3-propene sultone, tris(trimethyl silyl) phosphate, tris(trimethyl silyl) borate, vinyl sulfate, lithium difluoro dioxalate phosphate, lithium difluorophosphate, lithium difluoro oxalate borate, vinyl sulfite; The mass percentage content of the auxiliary additive in the electrolyte is 0.03-3.2%.

13. A battery, characterized by The electrolyte comprises the electrolyte of any one of claims 9-12.

14. The battery of claim 13, wherein, The battery further comprises a positive electrode active material and a negative electrode active material, and the positive electrode active material comprises at least one of lithium cobaltate, lithium iron phosphate, and a ternary material; or, the positive electrode active material comprises at least one of a layered oxide, prussian white, prussian blue, or a polyanion material. The negative active material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon, mesocarbon microbeads, a silicon-based material, a tin-based material, and lithium titanate. The negative active material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon, mesocarbon microbeads, a silicon-based material, a tin-based material, and lithium titanate.

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