Electrolyte and battery

Abstract

In order to solve the problem that the existing battery produces gas at high temperature and cannot be applied to the special scenario of not discharging at normal temperature and discharging at high temperature, the present invention provides an electrolyte and a battery, the electrolyte comprising a lithium salt, a solvent and an additive, the additive comprising vinylene carbonate, propylene sultone and 1,3,6-hexane trinitrile, based on the content of the electrolyte as 100%, the content of the additive is 0.5%~5%, the content of the vinylene carbonate is A%, the content of the propylene sultone is B%, the content of the 1,3,6-hexane trinitrile is C%, and the additive satisfies the following relationship: 1≤A+B≤3, 0.5≤B+C≤2, 1.5≤(A+C) / B≤6.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries, and in particular relates to an electrolyte and a battery. Background Art

[0002] Lithium-ion battery is a secondary battery that mainly relies on the movement of lithium ions between the positive and negative electrodes to work. It has the advantages of high operating voltage, high energy density, and environmental friendliness. It is widely used in the fields of 3C consumer batteries, power batteries, and energy storage batteries, and also has broad application prospects in the fields of aerospace, national defense, and military industry.

[0003] However, with the continuous advancement of technology, various mobile devices such as aircraft, ships, vehicles, and mobile communication devices often need to operate in high-temperature environments. At this time, a lithium-ion battery with excellent high-temperature performance is needed. In certain scenarios, a battery that does not discharge at room temperature but can only discharge at high temperatures is needed. The electrolyte in existing batteries can take into account the high and low temperature performance of high-voltage systems, but does not solve the problem of gas production at high temperatures. At the same time, it cannot be used in some special scenarios where it does not discharge at room temperature but discharges at high temperatures. Summary of the invention

[0004] In view of the problem that existing batteries generate gas at high temperatures and cannot be used in special scenarios where they do not discharge at room temperature but discharge at high temperatures, the present invention provides an electrolyte and a battery.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0006] On the one hand, the present invention provides an electrolyte, comprising a lithium salt, a solvent and an additive, wherein the additive comprises vinylene carbonate, propylene sultone and 1,3,6-hexane trinitrile, and based on the content of the electrolyte as 100%, the content of the additive is 0.5% to 5%, the content of the vinylene carbonate is A%, the content of the propylene sultone is B%, the content of the 1,3,6-hexane trinitrile is C%, and the additive satisfies the following relationship:

[0007] 1≤A+B≤3, 0.5≤B+C≤2, 1.5≤(A+C) / B≤6.

[0008] Optionally, the content of vinylene carbonate is 1% to 2%, the content of propylene sultone is 0.5% to 1%, and the content of 1,3,6-hexanetrinitrile is 0.5% to 1%.

[0009] Optionally, the additive further includes one or more of vinyl sulfate, succinonitrile, adiponitrile, 1,3-propane sultone, methylene disulfonate, ethylene glycol bis(propionitrile) ether, fluorinated ether, 2-methylmaleic anhydride, and triallyl phosphate.

[0010] Optionally, the content of the lithium salt is 10% to 30%, and the content of the solvent is 60% to 80%.

[0011] Optionally, the content of the lithium salt is 15% to 20%, the content of the solvent is 70% to 80%, and the content of the additive is 1% to 3%.

[0012] Optionally, the lithium salt includes at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl imide), lithium bis(trifluoromethylsulfonyl imide), lithium methanesulfonate, lithium trifluoromethylsulfonate, lithium fluorosulfonate, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium difluorophosphate, lithium difluorobis(oxalatophosphate), lithium chloroborane, and lithium tetraphenylborate.

[0013] Optionally, the solvent includes one or more of an ester solvent, an ether solvent, and a nitrile solvent;

[0014] The ester solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, vinylidene carbonate, fluoroethylene carbonate, methyl acetate, ethyl acetate, propyl acetate, and propyl propionate;

[0015] The ether solvent includes one or more of 1,3-dioxolane, 1,4-dioxolane, crown ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2-trifluoromethyltetrahydrofuran, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether;

[0016] The nitrile solvent includes one or more of acetonitrile, glutaronitrile and malononitrile.

[0017] Optionally, the solvent is selected from fluoroethylene carbonate, propylene carbonate and diethyl carbonate.

[0018] In another aspect, the present invention provides a battery comprising a positive electrode sheet, a negative electrode sheet, a separator and the electrolyte as described in any one of the above items.

[0019] Optionally, the positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes one or more of lithium cobalt oxide, lithium nickel manganese cobalt ternary material, lithium iron phosphate and lithium manganese oxide;

[0020] The negative electrode sheet includes a negative electrode active material, and the negative electrode active material includes one or more of graphite, hard carbon, soft carbon, graphene, mesophase carbon microspheres, silicon, silicon oxide, silicon-carbon composite material, silicon alloy, metallic lithium, and lithium alloy.

[0021] In the present invention, CN- in 1,3,6-hexanetrinitrile contained in the electrolyte can be complexed with high-valent metal ions, and the dissolution of metal ions can be inhibited under high temperature and high pressure. At the same time, CN- also has a high electronegativity and can be adsorbed on the surface of the positive electrode to form a CEI film to reduce the contact area between the electrolyte and the positive electrode and inhibit the occurrence of side reactions. In addition, CN- can also capture H protons to reduce the decomposition of LiPF6 and fluoroethylene carbonate, and the above inhibitory effect on battery side reactions can further reduce the gas production of the battery. The contained vinylene carbonate forms a stable solid electrolyte interface (SEI) film on the negative electrode surface of the battery. The SEI film can effectively prevent further decomposition of the electrolyte, reduce the capacity loss of the battery during the charge and discharge process, and thus improve the cycle stability and service life of the battery. The contained propene sulfonic acid lactone can form a more stable CEI with higher oxidation resistance and high temperature stability.

[0022] The present application uses the interaction of specific contents of vinylene carbonate, propylene sultone and 1,3,6-hexane trinitrile. At room temperature, the potential barrier of propylene sultone (PES) is high, resulting in secondary decomposition of PES on the negative electrode surface to generate inorganic substances such as Li2SO3, resulting in a decrease in battery cycle performance. Vinylene carbonate (VC) additives undergo a slow and persistent oxidative decomposition process during room temperature charging, resulting in gas generation and battery swelling, causing the battery capacity to decay rapidly, so that the battery using this electrolyte does not work at room temperature. At high temperatures, vinylene carbonate (VC), propylene sultone (PES) and 1,3,6-hexane trinitrile (HTCN) work together to form a thicker and more ordered organic / inorganic composite multilayer structure SEI film with better mechanical properties and more effective passivation of the negative electrode surface, thereby inhibiting continuous side reactions. At high temperatures, PES additives can reduce the ACIR and DCIR growth rates of the battery, inhibit the thermal expansion rate and cold expansion rate of the battery, and improve the capacity retention rate and recovery rate. At the same time, PES has a lower LUMO orbital and a high reduction potential, which makes it easy to reduce and form a film on the negative electrode surface, improve the stability of the electrode-electrolyte interface, effectively improve the performance of the battery under high temperature conditions, and inhibit the dissolution of transition metals, further improving the warm cycle capacity retention rate, so that the battery with the above electrolyte can work normally at high temperatures without producing gas. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] An embodiment of the present invention provides an electrolyte, comprising a lithium salt, a solvent and an additive, wherein the additive comprises vinylene carbonate (VC), propylene sultone (PES) and 1,3,6-hexane trinitrile (HTCN), and based on the content of the electrolyte as 100%, the content of the additive is 0.5% to 5%, the content of the vinylene carbonate is A%, the content of the propylene sultone is B%, the content of the 1,3,6-hexane trinitrile is C%, and the additive satisfies the following relationship:

[0025] 1≤A+B≤3, 0.5≤B+C≤2, 1.5≤(A+C) / B≤6.

[0026] In the present invention, CN- in 1,3,6-hexanetrinitrile contained in the electrolyte can be complexed with high-valent metal ions, and the dissolution of metal ions can be inhibited under high temperature and high pressure. At the same time, CN- also has a high electronegativity and can be adsorbed on the surface of the positive electrode to form a CEI film to reduce the contact area between the electrolyte and the positive electrode and inhibit the occurrence of side reactions. In addition, CN- can also capture H protons to reduce the decomposition of LiPF6 and fluoroethylene carbonate, and the above inhibitory effect on battery side reactions can further reduce the gas production of the battery. The contained vinylene carbonate forms a stable solid electrolyte interface (SEI) film on the negative electrode surface of the battery. The SEI film can effectively prevent further decomposition of the electrolyte, reduce the capacity loss of the battery during the charge and discharge process, and thus improve the cycle stability and service life of the battery. The contained propene sulfonic acid lactone can form a more stable CEI with higher oxidation resistance and high temperature stability.

[0027] The present application uses the interaction of specific contents of vinylene carbonate, propylene sultone and 1,3,6-hexane trinitrile. At room temperature, the potential barrier of propylene sultone (PES) is high, resulting in secondary decomposition of PES on the negative electrode surface to generate inorganic substances such as Li2SO3, resulting in a decrease in battery cycle performance. Vinylene carbonate (VC) additives undergo a slow and persistent oxidative decomposition process during room temperature charging, resulting in gas generation and battery swelling, causing the battery capacity to decay rapidly, so that the battery using this electrolyte does not work at room temperature. At high temperatures, vinylene carbonate (VC), propylene sultone (PES) and 1,3,6-hexane trinitrile (HTCN) work together to form a thicker and more ordered organic / inorganic composite multilayer structure SEI film with better mechanical properties and more effective passivation of the negative electrode surface, thereby inhibiting continuous side reactions. At high temperatures, PES additives can reduce the ACIR and DCIR growth rates of the battery, inhibit the thermal expansion rate and cold expansion rate of the battery, and improve the capacity retention rate and recovery rate. At the same time, PES has a lower LUMO orbital and a high reduction potential, which makes it easy to reduce and form a film on the negative electrode surface, improve the stability of the electrode-electrolyte interface, effectively improve the performance of the battery under high temperature conditions, and inhibit the dissolution of transition metals, further improving the warm cycle capacity retention rate, so that the battery with the above electrolyte can work normally at high temperatures without producing gas.

[0028] Specifically, the content of the additive includes but is not limited to 0.5%, 0.8%, 1.0%, 1.5%, 2.0%, 2.2%, 2.5%, 3.0%, 3.2%, 3.5%, 3.8%, 4.0%, 4.2%, 4.5%, 4.8% or 5.0%.

[0029] In some embodiments, the content of vinylene carbonate is 1% to 2%, the content of propylene sultone is 0.5% to 1%, and the content of 1,3,6-hexanetrinitrile is 0.5% to 1%. The electrolyte meeting the above conditions can further inhibit the occurrence of side reactions, reduce the gas production of the battery, and improve the cycle life of the battery.

[0030] Specifically, the content of vinylene carbonate includes, but is not limited to, 1%, 1.2%, 1.4%, 1.6%, 1.8% or 2%. The content of propylene sultone includes, but is not limited to, 0.5%, 0.7%, 0.9% or 1%. The content of 1,3,6-hexanetrinitrile includes, but is not limited to, 0.5%, 0.7%, 0.9% or 1%.

[0031] In some embodiments, the additives also include one or more of vinyl sulfate (DTD), succinonitrile (SN), adiponitrile (ADN), 1,3-propane sultone (PS), methylene disulfonate (MMDS), ethylene glycol bis (propionitrile) ether (EGBE), fluorinated ether (D2), 2-methylmaleic anhydride (DMMA), and triallyl phosphate (TAP). By adding the above additives, the occurrence of side reactions of the electrolyte during the charge and discharge process can be further suppressed, the generation of gas can be reduced, the expansion rate of the battery can be improved, and the overcharge safety performance of the electrochemical device at high temperature can be improved. And the battery has a certain high voltage window, which can effectively improve the storage performance of the battery under high temperature conditions.

[0032] In some embodiments, the content of the lithium salt is 10% to 30%, and the content of the solvent is 60% to 80%. By limiting the content of the lithium salt and the solvent, the concentration of the lithium salt is adjusted. The concentration of the lithium salt in the electrolyte is not particularly limited, but when the content of the lithium salt is less than 10%, the number of mobile lithium ions in the electrolyte is insufficient. When the content of the lithium salt is higher than 30%, the viscosity of the electrolyte may increase, resulting in an increase in the impedance of the electrolyte, which reduces the migration rate of lithium ions and may reduce the performance of the battery.

[0033] Specifically, the content of lithium salt includes but is not limited to 10%, 13%, 16%, 18%, 20%, 25%, 27% or 30%. The content of solvent includes but is not limited to 60%, 64%, 66%, 68%, 70%, 71%, 72%, 73%, 74%, 75%, 77% or 80%.

[0034] In a preferred embodiment, the content of the lithium salt is 15% to 20%, the content of the solvent is 70% to 80%, and the content of the additive is 1% to 3%. The electrolyte that meets the above conditions ensures the migration rate of lithium ions and further improves the electrochemical performance of the battery.

[0035] In some embodiments, the lithium salt includes at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl imide), lithium bis(trifluoromethylsulfonyl imide), lithium methanesulfonate, lithium trifluoromethylsulfonate, lithium fluorosulfonate, lithium bis(oxalate borate), lithium difluorooxalate borate, lithium difluorophosphate, lithium difluorobis(oxalate phosphate), lithium chloroborane, and lithium tetraphenylborate. By selecting the above-mentioned ionizable lithium salts, the amount of lithium ions that can migrate in the electrolyte is guaranteed.

[0036] Preferably, the lithium salt is selected from lithium hexafluorophosphate.

[0037] In some embodiments, the solvent includes one or more of an ester solvent, an ether solvent, and a nitrile solvent;

[0038] The ester solvent includes one or more of ethylene carbonate (EC), propylene carbonate (PCA), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propylene carbonate (PC), vinylene carbonate (VEC), fluoroethylene carbonate (FEC), methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), and propyl propionate (PP);

[0039] The ether solvent includes one or more of 1,3-dioxolane, 1,4-dioxolane, crown ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2-trifluoromethyltetrahydrofuran, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether;

[0040] The nitrile solvent includes one or more of acetonitrile, glutaronitrile and malononitrile.

[0041] The content of ester solvent, ether solvent and nitrile solvent has no particular restrictions, and is arbitrary in the scope of not significantly destroying lithium ion battery effect of the present invention, but the lower limit of its content in the case of using a kind of alone is relative to the total amount of solvent of nonaqueous electrolytic solution, and usually volume ratio is more than 3%, and preferred volume ratio is more than 5%.By setting this scope, can avoid causing specific conductivity reduction due to the dielectric constant reduction of nonaqueous electrolytic solution, be easy to make the high current discharge characteristic of nonaqueous electrolyte battery, stability with respect to negative pole, cycle characteristics reach good scope.In addition, the upper limit usually volume ratio is less than 90%, preferred volume ratio is less than 85%, more preferably volume ratio is less than 80%.By setting this scope, can improve the oxidation / reduction tolerance of nonaqueous electrolytic solution, thus contribute to the stability when improving high temperature preservation.

[0042] In a preferred embodiment, the solvent is selected from fluoroethylene carbonate, propylene carbonate and diethyl carbonate. By selecting the above solvents for use, the viscosity of the electrolyte is guaranteed to be within an appropriate range, which helps to achieve a good output characteristic of the battery.

[0043] On the other hand, an embodiment of the present invention provides a battery, comprising a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte as described in any one of the above items.

[0044] In some embodiments, the positive electrode sheet includes a positive electrode active material, which includes one or more of lithium cobalt oxide, lithium nickel manganese cobalt ternary material, lithium iron phosphate and lithium manganese oxide, which helps to improve the high temperature cycle performance of the battery.

[0045] The negative electrode sheet includes a negative electrode active material, and the negative electrode active material includes one or more of graphite, hard carbon, soft carbon, graphene, mesophase carbon microspheres, silicon, silicon oxide, silicon-carbon composite material, silicon alloy, metallic lithium, and lithium alloy.

[0046] It should be noted that the materials disclosed above are only exemplary, and the positive electrode active material and the negative electrode active material may be any other suitable material.

[0047] The present invention is further described below by way of examples.

[0048] Example

[0049] This embodiment is used to illustrate the electrolyte and battery disclosed in the present invention, and includes the following operating steps:

[0050] Preparation of electrolyte

[0051] In a glove box filled with argon (O2 < 1ppm, H2O < 1ppm), the solvent FEC + PC + DEC is mixed evenly by shaking and stirring in a mass ratio of 30:40:30 to obtain a mixed solvent. LiPF6 is slowly added to the mixed solvent to obtain a mixed solution. Finally, additives are added to the mixed solution to obtain the electrolyte.

[0052] Production of positive electrode:

[0053] The positive electrode material lithium cobalt oxide (NCM), the conductive agent CNT, and the adhesive PVDF are fully stirred and mixed in an NMP solvent at a mass ratio of 97:1.5:1.5, and the slurry is coated on at least one side of the positive electrode current collector Al foil. After drying, rolling, die-cutting and other processes, a positive electrode sheet that meets the requirements is obtained.

[0054] Negative electrode production:

[0055] The negative electrode material graphite, conductive agent SP, thickener CMC, and adhesive SBR are mixed in a proper amount of deionized water solvent at a mass ratio of 96.3:1:1.2:1.5, and are fully stirred to obtain a uniform negative electrode slurry. The slurry is coated on at least one side of the negative electrode current collector Cu foil. After drying, rolling, die cutting and other processes, a usable negative electrode sheet is obtained.

[0056] Lithium-ion battery production:

[0057] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in sequence to obtain a bare cell. The bare cell is placed in an outer packaging bag, dried at high temperature until the water content of the electrode sheet is less than 500ppm, and then injected with the above electrolyte. After vacuum packaging, standing, forming, shaping and other processes, the preparation of the secondary battery is completed.

[0058] Examples 1-9

[0059] The examples are used to illustrate the electrolyte and battery disclosed in the present invention, and include most of the operating steps in the above examples, except that the formula in Table 1 is used.

[0060] Comparative Examples 1-7

[0061] The comparative example is used to compare and illustrate the electrolyte and battery disclosed in the present invention, and includes most of the operating steps in the above embodiments, except that the formula in Table 1 is used.

[0062] Table 1

[0063]

[0064] Performance Testing

[0065] 1. The sodium ion batteries prepared in the above examples and comparative examples were subjected to the following performance tests:

[0066] High temperature cycle test method: charge to 4.4V at 1C constant current and constant voltage at 45℃, with a cut-off current of 0.05C, let stand for 5 minutes, then discharge to 3V at 1C, and cycle for 500 cycles. Record the first cycle discharge capacity C1 and the first cycle charge capacity C2, then the first efficiency = C2 / C1*100%; capacity retention rate = discharge capacity of the specified number of cycles / C3*100%; cycle life = the number of cycles when the battery capacity retention rate reaches 80%.

[0067] High temperature storage test method: At room temperature (25°C), charge and discharge once at 0.2C and record the battery discharge capacity C3, then charge to 4.4V at 0.2C constant current and constant voltage, and store the battery in a 45°C constant temperature test chamber for 28 days before taking it out. After the battery returns to normal temperature, use the drainage method to test the battery gas production.

[0068] The test results are shown in Table 2.

[0069] Table 2

[0070]

[0071] The results of Examples 1 to 9 and Comparative Examples 1 to 7 show that the electrolytes prepared in the Examples are used in batteries and exhibit better high-temperature cycle and storage performance than the comparative examples as a whole, proving that the additives used in the present invention can achieve the characteristics that the battery does not work at room temperature, can work normally at high temperature and produces less gas.

[0072] The results of Examples 1 and 7 show that increasing the amount of 1,3,6-hexane tricarbonitrile added can significantly improve the high-temperature cycle life of the battery. This is mainly because it can form a stable CEI film on the positive electrode surface, prevent effective metal ion dissolution under high temperature and high pressure, and protect the crystal structure of the positive electrode material. It is an ideal choice for improving the high-temperature performance of the battery.

[0073] The results of Examples 5 and 6 show that when the content of vinylene carbonate additive is too high, the high temperature cycle life will be reduced. This is because more VC will lead to an increase in the organic components of the SEI film, and the impedance will continue to increase, affecting the battery capacity.

[0074] The results of Examples 2, 3, and 4 show that the contents of propylene sultone and vinylene carbonate should be maintained within a certain range. At the same time, when the nitrile additive forms a blending system with the carbonate additive, it may affect the conductivity and flame retardant properties of the electrolyte, resulting in a decrease in battery capacity and a worse cycle life.

[0075] Example 8: The battery performance is reduced due to excessive addition of HTCN. This is mainly because the main chain structure is composed of C atoms, which will greatly limit the transmission of Li+, slow down the charging and discharging speed, and reduce the actual available capacity of the battery. At the same time, it will lead to the formation of lithium dendrites, which will pierce the diaphragm and cause an internal short circuit in the battery, thereby affecting the cycle life of the battery at high temperature.

[0076] It can be seen from the test results of Example 1 and Comparative Examples 1-7 that when one or two of the additives are removed, the battery will work normally at room temperature, and it is also necessary to pay attention to the ratio between the carbonate additive and the nitrile additive. When the content of vinylene carbonate, propene sultone and 1,3,6-hexane trinitrile and their relationship are within the protection scope of this application, the additives in the present invention can be decomposed at the positive electrode interface to form a stable CEI film, which alleviates a series of malignant side reactions between the positive electrode surface and the electrolyte, thereby improving the battery cycle life. At the same time, the additives of the present invention can also form a stable low-impedance SEI film. From the perspective of volume test after high temperature test, the generation of gas is effectively suppressed, thereby further improving the high temperature performance of the battery.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An electrolyte, characterized in that: The invention comprises a lithium salt, a solvent and an additive, wherein the additive comprises vinylene carbonate, propylene sultone and 1,3,6-hexane trinitrile. Based on the content of the electrolyte being 100%, the content of the additive is 0.5% to 5%, the content of the vinylene carbonate is A%, the content of the propylene sultone is B%, the content of the 1,3,6-hexane trinitrile is C%, and the additive satisfies the following relationship: 1≤A+B≤3, 0.5≤B+C≤2, 1.5≤(A+C) / B≤6.

2. The electrolyte according to claim 1, characterized in that The content of the vinylene carbonate is 1% to 2%, the content of the propylene sultone is 0.5% to 1%, and the content of the 1,3,6-hexanetrinitrile is 0.5% to 1%.

3. The electrolyte according to claim 1, characterized in that The additives further include one or more of vinyl sulfate, succinonitrile, adiponitrile, 1,3-propane sultone, methylene disulfonate, ethylene glycol bis(propionitrile) ether, fluorine-containing ether, 2-methylmaleic anhydride, and triallyl phosphate.

4. The electrolyte according to claim 1, characterized in that The content of the lithium salt is 10% to 30%, and the content of the solvent is 60% to 80%.

5. The electrolyte according to claim 4, characterized in that The content of the lithium salt is 15% to 20%, the content of the solvent is 70% to 80%, and the content of the additive is 1% to 3%.

6. The electrolyte according to claim 1, characterized in that The lithium salt includes at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl imide), lithium bis(trifluoromethylsulfonyl imide), lithium methanesulfonate, lithium trifluoromethylsulfonate, lithium fluorosulfonate, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium difluorophosphate, lithium difluorobis(oxalatophosphate), lithium chloroborane, and lithium tetraphenylborate.

7. The electrolyte according to claim 1, characterized in that The solvent includes one or more of an ester solvent, an ether solvent, and a nitrile solvent; The ester solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, vinylidene carbonate, fluoroethylene carbonate, methyl acetate, ethyl acetate, propyl acetate, and propyl propionate; The ether solvent includes one or more of 1,3-dioxolane, 1,4-dioxolane, crown ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2-trifluoromethyltetrahydrofuran, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether; The nitrile solvent includes one or more of acetonitrile, glutaronitrile and malononitrile.

8. The electrolyte according to claim 7, characterized in that The solvent is selected from fluoroethylene carbonate, propylene carbonate and diethyl carbonate.

9. A battery, characterized in that: The invention comprises a positive electrode sheet, a negative electrode sheet, a separator and the electrolyte according to any one of claims 1 to 8.

10. The battery according to claim 9, characterized in that The positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes one or more of lithium cobalt oxide, lithium nickel manganese cobalt ternary material, lithium iron phosphate and lithium manganese oxide; The negative electrode sheet includes a negative electrode active material, and the negative electrode active material includes one or more of graphite, hard carbon, soft carbon, graphene, mesophase carbon microspheres, silicon, silicon oxide, silicon-carbon composite material, silicon alloy, metallic lithium, and lithium alloy.

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