Electrolyte, secondary battery, and electric device

Abstract

The invention provides an electrolyte, a secondary battery and an electric device. The electrolyte comprises a solvent, a lithium salt and a diluent, and the diluent comprises a diluent containing a silicon-carbon bond, a diluent containing a silicon-oxygen bond and a diluent containing a silicon-nitrogen bond. The molar ratio of the silicon-carbon-bond-containing diluent to the silicon-oxygen-bond-containing diluent to the silicon-nitrogen-bond-containing diluent is (0.15-0.45): (0.15-0.45): 0. According to the invention, the migration radius of a lithium ion solvation structure is reduced by controlling the molar ratio of the silicon-carbon-bond-containing diluent to the silicon-oxygen-bond-containing diluent to the silicon-nitrogen-bond-containing diluent through the diversification of the silane diluent structure; therefore, the diffusion coefficient and the ionic conductivity of lithium ions in the electrolyte are improved, and the battery performance at low temperature / high rate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary batteries, and more particularly, to an electrolyte, a secondary battery, and a device. Background Art

[0002] Lithium batteries have been widely used in smartphones, unmanned aerial vehicles, and hybrid electric vehicles. However, with the development of society, lithium-ion batteries with low energy density can no longer meet the requirements. Developing high-energy-density lithium-ion / lithium-metal batteries and their compatible electrolytes has become the main research direction.

[0003] Using a locally high-concentration electrolyte system can effectively improve the cycling performance and thermal safety performance of high-energy-density battery systems. However, due to the use of a large amount of solvent components that do not dissociate lithium salts in the locally high-concentration electrolyte, the overall conductivity of the electrolyte decreases significantly. Therefore, it is very important to develop a locally high-concentration electrolyte system with high conductivity, high stability, and excellent low-temperature performance. Summary of the Invention

[0004] The present invention aims to provide an electrolyte, a secondary battery, and a device to solve the problems of low conductivity, poor stability, and poor low-temperature performance of existing locally high-concentration electrolytes.

[0005] In a first aspect of the present application, there is provided an electrolyte. Based on the total weight of the electrolyte, the electrolyte includes a solvent, a lithium salt, and a diluent. The diluent includes a silicon-carbon bond-containing diluent, a silicon-oxygen bond-containing diluent, and a silicon-nitrogen bond-containing diluent. Based on the total molar amount of the diluent, the molar ratio of the silicon-carbon bond-containing diluent, the silicon-oxygen bond-containing diluent, and the silicon-nitrogen bond-containing diluent is (0.15 - 0.45):(0.15 - 0.45):(0.15 - 0.45).

[0006] In a preferred embodiment, based on the total molar amount of the diluent, the molar ratio of the silicon-carbon bond-containing diluent, the silicon-oxygen bond-containing diluent, and the silicon-nitrogen bond-containing diluent is (0.2 - 0.4):(0.2 - 0.4):(0.2 - 0.4).

[0007] In a second aspect of the present application, there is also provided a secondary battery including the electrolyte provided by the present application.

[0008] In a third aspect of the present application, there is provided a device including the secondary battery provided by the present application.

[0009] Advantageous Effects:

[0010] Through the diversification of the structure of the silane diluent, the present invention controls the molar ratio of the silane-carbon bond diluent, the silane-oxygen bond diluent, and the silane-nitrogen bond diluent to reduce the migration radius of the lithium-ion solvation structure, thereby increasing the diffusion coefficient and ionic conductivity of lithium ions in the electrolyte, and thus improving the battery performance at low temperature / high rate. Detailed implementation manners

[0011] For the sake of simplicity, only some numerical ranges are disclosed in this application. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, and similarly any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, each separately disclosed point or single numerical value itself can be used as a lower limit or an upper limit and combined with any other point or single numerical value or combined with other lower limits or upper limits to form a range not explicitly recited.

[0012] In this context, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0013] In the description herein, unless otherwise specified, "above" and "below" include the recited number.

[0014] Unless otherwise specified, the terms used in this application have the well-known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values of the various parameters mentioned in this application can be measured by various commonly used measurement methods in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0015] The list of items connected by the terms "at least one of", "at least one kind of" or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A, or only B, or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A, or only B, or only C, or only A and B (excluding C), or only A and C (excluding B), or only B and C (excluding A), or all of A, B, and C. Item A can include a single component or multiple components. Item B can include a single component or multiple components. Item C can include a single component or multiple components.

[0016] The term "C1-C6 alkyl" includes, but is not limited to: methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, neopentyl, cyclopentyl, methylcyclopentyl, n-hexyl, isohexyl, cyclohexyl, etc.

[0017] The term "C1-C6 alkoxy" includes, but is not limited to: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentyloxy, isopentyloxy or n-hexyloxy, etc.

[0018] The term "C2-C6 alkenyl" includes, but is not limited to: vinyl, propenyl, butenyl, pentenyl or hexenyl, etc.

[0019] The term "C2-C6 alkynyl" includes, but is not limited to: ethynyl, propynyl, butynyl, pentynyl or hexynyl, etc.

[0020] The term "C3-C6 cycloalkyl" includes, but is not limited to: cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl, etc.

[0021] The term "C6-C 12 aryl" includes, but is not limited to: phenyl or naphthyl, etc.

[0022] The term "substituted or unsubstituted" means that the functional group described after this term may or may not have substituents. For example, "substituted or unsubstituted C1-C6 alkyl" means C1-C6 alkyl with substituents or unsubstituted C1-C6 alkyl. Among them, the number of substituents can be one or more than two, and the substituents include at least one of halogen, carbonyl and amino. It should be understood that when the number of substituents is greater than 1, each substituent can be the same or different.

[0023] Unless otherwise specified, the terms used in this application have the well-known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values of the various parameters mentioned in this application can be measured by various common measurement methods in the art (for example, they can be tested according to the methods given in the embodiments of this application). It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0024] I. Electrolyte

[0025] To solve the above technical problems, the present application provides an electrolyte, which includes a solvent, a lithium salt, and a diluent. The diluent includes a silicon-carbon bond-containing diluent, a silicon-oxygen bond-containing diluent, and a silicon-nitrogen bond-containing diluent. Based on the total molar amount of the diluent, the molar ratio of the silicon-carbon bond-containing diluent, the silicon-oxygen bond-containing diluent, and the silicon-nitrogen bond-containing diluent is (0.15 - 0.45):(0.15 - 0.45):(0.15 - 0.45). Exemplarily, based on the total molar amount of the diluent, the molar ratio of the silicon-carbon bond-containing diluent, the silicon-oxygen bond-containing diluent, and the silicon-nitrogen bond-containing diluent can be selected as 0.34:0.33:0.33, 0.33:0.33:0.34, 0.15:0.45:0.4, 0.33:0.34:0.33, 0.2:0.4:0.4, 0.4:0.2:0.4, 0.4:0.4:0.2, 0.45:0.15:0.4, 0.45:0.4:0.15.

[0026] The present application forms a high-entropy effect by controlling the molar ratio of the three different diluents within the range of 0.15 - 0.45. The three cooperate to destroy the lithium-ion solvation structure, and the formed lithium-ion solvation diameter is relatively small. According to the Stokes-Einstein equation and the Nernst-Einstein equation, the smaller the lithium-ion solvation diameter, the larger the diffusion coefficient, and the higher the lithium-ion conductivity. When the total amount of the diluent is certain, when the molar ratio of one of the diluents is less than 0.15, the high-entropy effect of the electrolyte decreases, and the destructive effect on the solvation structure is relatively low, thus the conductivity cannot be effectively improved.

[0027] When using a diluent with a relatively low molecular polarity, it tends to form a single solvated ion cluster, while the silane diluent has a relatively large molecular polarity and is more likely to form a complex solvated ion cluster, which is intuitively manifested as an increase in the polarizability of the compound molecule, thereby increasing the overall high-entropy degree of the electrolyte. On the premise that the mass fraction of the silane diluent in the total amount of the electrolyte is the same, the more types of silane diluents, the larger the composite polarizability of the silane diluent, the higher the conductivity, and thus the better the performance at low temperatures.

[0028] In a preferred embodiment of the present application, based on the total molar amount of the diluent, the molar ratio of the silicon-carbon bond-containing diluent, the silicon-oxygen bond-containing diluent, and the silicon-nitrogen bond-containing diluent is (0.2 - 0.4):(0.2 - 0.4):(0.2 - 0.4).

[0029] Since the diluent used in the current local high-concentration electrolyte has a relatively high boiling point, its low-temperature performance is poor. In some embodiments of the present application, the boiling point of the diluent is less than 150 °C.

[0030] In some embodiments of the present application, the viscosity of the diluent is less than 1.5 mPa·s.

[0031] In some embodiments of the present application, the dielectric constant of the diluent is greater than 3.

[0032] In some embodiments of the present application, based on the total mass of the electrolyte, the content of the diluent is 20 wt% to 75 wt%.

[0033] In the foregoing content of the present application, the silane diluent has been described from the perspectives of the molar ratio, boiling point, viscosity, and dielectric constant among various diluents. In order to better elaborate on the silane diluent, the applicant has also studied the structure of the silane diluent.

[0034] In some embodiments of the present application, the silicon-carbon bond-containing diluent is at least one of the organic compounds having the structure shown in Formula I.

[0035]

[0036] Among them, R1 is selected from fluoro C1-C6 alkyl, phenyl, or C2-C6 alkenyl, and R2, R3, and R4 are each independently selected from C1-C6 alkyl and C2-C6 alkenyl.

[0037] Preferably, the silicon-carbon bond-containing diluent includes at least one of (trifluoromethyl)trimethylsilane, triethyl(trifluoromethyl)silane, (difluoromethyl)trimethylsilane, (chlorodifluoromethyl)trimethylsilane, trimethyl(pentafluoroethyl)silane, trimethylphenylsilane, and tetravinylsilane.

[0038] In some embodiments of the present application, the silicon-oxygen bond-containing diluent is at least one of the organic compounds having the structure shown in Formula II and the organic compounds having the structure shown in Formula III.

[0039]

[0040] Among them, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 , R 14 are each independently selected from C1-C6 alkyl.

[0041] In a preferred embodiment, the silicon-oxygen bond-containing diluent includes at least one of trimethylmethoxysilane, trimethylethoxysilane, trimethylpropoxysilane, isopropoxythimethylsilane, tert-butoxythimethylsilane, hexamethyldisiloxane, and tetramethyldivinyldisiloxane.

[0042] In some embodiments of the present application, the silicon-nitrogen bond-containing diluent is at least one of the organic compounds having the structure shown in Formula IV, the organic compounds having the structure shown in Formula V, and the organic compounds having the structure shown in Formula VI.

[0043]

[0044] Among them, R 15 、R 16 、R 17 、R 18 、R 19 、R20、R 21 、R 22 、R 23 、R 24 、R25、R 26 、R27、R 28 、R 29 、R 30 、R 31 、R 32 are each independently selected from C1-C6 alkyl groups.

[0045] In a preferred embodiment, the silazane diluent includes but is not limited to at least one of heptamethyldisilazane, N,N-dimethyltrimethylsilylamine, and bis(dimethylamino)dimethylsilane.

[0046] From the perspective of the mass percentage content of the silane diluent, it is known through research that based on the total weight of the electrolyte, the weight percentage content of the silane diluent is 20 wt% to 75 wt%. If the mass percentage content of the silane diluent is too small, the wettability of the electrolyte on the electrode sheet is poor, while if the mass percentage content is too large, the wettability of the electrolyte on the electrode sheet is good, but the overall ability of the electrolyte to dissociate the lithium salt becomes weak, resulting in a decrease in conductivity instead. Limiting the mass percentage content of the silane diluent within the above range can ensure that the electrolyte has a large conductivity, excellent wettability of the electrode sheet, and good electrical conductivity.

[0047] The organic solvent in the electrolyte provided by this application can be of the types commonly used in the art, including but not limited to at least one of carbonate organic compounds, ether organic compounds, phosphate organic compounds, nitrile organic compounds, sulfone organic compounds, and amide organic compounds. Preferably, the organic solvent includes but is not limited to at least one of diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, methyl ethyl carbonate, methyl acetate, methyl propionate, ethyl acetate, ethyl propionate, propyl acetate, propyl propionate, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, butylene carbonate, ethylene glycol dimethyl ether, tetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, dimethyl methylphosphonate, acetonitrile, sulfolane, methyl ethyl sulfone, dimethylformamide, and dimethylacetamide. Based on the total mass of the electrolyte, the mass content of the solvent is 8 wt% to 80 wt%; and / or

[0048] The lithium salt in the electrolyte provided by the present application can be of the types commonly used in the art, including but not limited to at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium tetrafluoroborate, and lithium trifluoromethanesulfonate. Based on the total mass of the electrolyte, the mass content of the lithium salt is 7.5 wt% to 31 wt%.

[0049] II. Secondary battery

[0050] The second aspect of the present application also provides a secondary battery, including a positive electrode, a negative electrode, a separator, and the electrolyte provided by the present application. Since the electrolyte provided by the present application has a high ionic conductivity, applying it to the preparation of a secondary battery can effectively extend its low-temperature cycle life.

[0051] According to some embodiments of the present application, the secondary battery is a lithium secondary battery. In some embodiments, the lithium secondary battery includes but is not limited to: a lithium metal secondary battery, a lithium-ion secondary battery, a lithium polymer secondary battery, or a lithium-ion polymer secondary battery.

[0052] According to some embodiments of the present application, the secondary battery may include an outer package, and the outer package can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic, such as one or several of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc.

[0053] According to some embodiments of the present application, the shape of the secondary battery is not particularly limited, and it can be cylindrical, square, or any other arbitrary shape.

[0054] In some embodiments, the present application also provides a battery module. The battery module includes the above-mentioned secondary battery. Since the battery module of the present application uses the above-mentioned secondary battery, it has at least the same advantages as the secondary battery. The number of secondary batteries included in the battery module of the present application can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0055] In some embodiments, the present application also provides a battery pack, which includes the above-mentioned battery module. The number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0056] In some embodiments, the devices of the present application include but are not limited to: all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors.

[0057] III. Device

[0058] The third aspect of the present application further provides a device, including a power source formed by using the secondary battery provided by the present application. Since the secondary battery provided by the present application has a long cycle life, using it as the power source of the electrical device can significantly improve its economic effect.

[0059] In some embodiments, the electrical device includes, but is not limited to: electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, energy storage systems, etc. In order to meet the device's requirements for high power and high energy density of the secondary battery, a battery pack or a battery module can be used.

[0060] In some other embodiments, the electrical device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires being thin and light, and a secondary battery can be used as the power source.

[0061] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0062] Embodiment 1

[0063] Hexamethyldisiloxane / isopropoxytrimethylsilane / trimethylmethoxysilane / LiFSI / DMC were mixed and stirred according to the mass fractions of 11.4%: 27.7%: 25.4%: 15.5%: 20% to form a homogeneous and stable electrolyte solution.

[0064] Embodiment 2

[0065] Hexamethyldisiloxane / heptamethyldisilazane / (trifluoromethyl) trimethylsilane / LiFSI / DMC were mixed and stirred according to the mass fractions of 21.6%: 24.0%: 18.9%: 15.5%: 20% to form a homogeneous and stable electrolyte solution.

[0066] Embodiment 3

[0067] Hexamethyldisiloxane / heptamethyldisilazane / (trifluoromethyl) trimethylsilane / LiFSI / EC were mixed and stirred according to the mass fractions of 13.1%: 28.4%: 23.0%: 15.5%: 20% to form a homogeneous and stable electrolyte solution.

[0068] Embodiment 4

[0069] Hexamethyldisiloxane / isopropoxytrimethylsilane / trimethylmethoxysilane / LiFSI / EC were mixed and stirred according to the mass fractions of 10.3%: 41.8%: 23%: 15.5%: 9.5% to form a homogeneous and stable electrolyte solution.

[0070] Comparative Example 1

[0071] Hexamethyldisiloxane / LiFSI / DMC was mixed and stirred at a mass fraction of 64.5%:15.5%:20% to form a homogeneous and stable electrolyte solution.

[0072] Comparative Example 2

[0073] Hexamethyldisiloxane / heptamethyldisilazane / LiFSI / DMC was mixed and stirred at a mass fraction of 31%:33.5%:15.5%:20% to form a homogeneous and stable electrolyte solution.

[0074] Comparative Example 3

[0075] Hexamethyldisiloxane / heptamethyldisilazane / (trifluoromethyl)trimethylsilane / LiFSI / EC was mixed and stirred at a mass fraction of 6.5%:35.2%:22.8%:15.5%:20% to form a homogeneous and stable electrolyte solution.

[0076] Comparative Example 4

[0077] Hexamethyldisiloxane / isopropoxytrimethylsilane / trimethylmethoxysilane / LiFSI / EC was mixed and stirred at a mass fraction of 7.6%:37.8%:19.1%:15.5%:20% to form a homogeneous and stable electrolyte solution.

[0078] Comparative Example 5

[0079] Hexamethyldisiloxane / isopropoxytrimethylsilane / trimethylmethoxysilane / LiFSI / DMC was mixed and stirred at a mass fraction of 0.4%:1.7%:0.9%:15.5%:81.5% to form a homogeneous and stable electrolyte solution. Performance Test:

[0080] Comparative Example 6

[0081] Hexamethyldisiloxane / isopropoxytrimethylsilane / trimethylmethoxysilane / LiFSI / EC was mixed and stirred at a mass fraction of 0.7%:2.8%:1.5%:15.5%:79.5% to form a homogeneous and stable electrolyte solution.

[0082] Comparative Example 7

[0083] Hexamethyldisiloxane / isopropoxytrimethylsilane / trimethylmethoxysilane / LiFSI / DMC was mixed and stirred at a mass fraction of 10.9%:44.3%:24.3%:15.5%:5%. The electrolyte solution failed to form a stable solution.

[0084] Preparation of the positive electrode:

[0085] Mix the cathode ternary high-nickel active material, conductive carbon black, and binder polyvinylidene chloride in a mass ratio of 97.5∶1.5∶1.0, and disperse the mixture in N-methylpyrrolidone (NMP) to obtain the cathode slurry. Then, evenly coat the cathode slurry on both surfaces of the aluminum foil, and after drying, rolling, and vacuum drying, obtain the cathode.

[0086] Preparation of the anode:

[0087] Mix the mixed silicon-carbon material, conductive carbon black, binders (styrene-butadiene rubber, polyacrylic acid), and sodium carboxymethyl cellulose in a mass ratio of 96.0∶1.0∶2.4∶0.6, and disperse the mixture in deionized water to obtain the anode slurry. Coat the anode slurry on both surfaces of the copper foil, and after drying, rolling, and vacuum drying, obtain the anode.

[0088] Preparation of the lithium-ion battery:

[0089] Place a three-layer separator with a thickness of 11 μm (a polyethylene PE porous polymer film is used as the separator) between the above-mentioned cathode and anode. Then, perform a lamination process on the sandwich structure composed of the cathode, separator, and anode, and then put it into an aluminum-plastic film packaging bag. Bake it in a vacuum at 75°C for 48 hours to obtain the battery cell to be injected with electrolyte. Inject the above-prepared electrolyte into the battery cell, perform vacuum packaging, and let it stand at room temperature for 12 hours and at a high temperature of 45°C for 12 hours. Then, through the formation and grading steps, obtain the lithium-ion battery; among them, the formation and grading steps are: constant current charge at 0.05C for 120 minutes, constant current and constant voltage charge at 0.1C until 4.2V, discharge at 0.2C until 2.5V, and the formation is completed. Let it stand at a high temperature for 24 hours, constant current and constant voltage charge at 0.1C until 4.2V, constant current discharge at 0.2C until 2.5V, constant current and constant voltage charge at 0.1C until 4.2V, constant current discharge at 0.2C until 2.5V, and cycle twice to complete the grading.

[0090] Low-temperature cycle capacity retention rate test:

[0091] Under low-temperature (-10°C) conditions, charge the prepared lithium-ion battery at a constant current and constant voltage of 1C until 4.25V, and then discharge it at a constant current of 1C until 2.5V. After 500 charge-discharge cycles, calculate the capacity retention rate after the 500th cycle according to the following formula: discharge capacity after the 500th cycle / discharge capacity of the first cycle × 100%. The test results are shown in Table 1.

[0092]

[0093] Table 1

[0094] It can be seen by comparing Examples 2 to 3 and Comparative Examples 1 to 2 that the ionic conductivity and low-temperature cycle performance of the electrolyte after using three diluents are better; it can be seen by comparing Examples 1 to 4 and Comparative Examples 3 to 4 that when the molar ratios of the three diluents in the electrolyte are within a certain range, the performance of the electrolyte is better; it can be seen by comparing Examples 1 to 4 and Comparative Examples 5 to 7 that the advantages of multiple diluents can be highlighted only when the total mass fraction of the silane diluent in the electrolyte is within a reasonable range, thereby improving its cycle performance.

[0095] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An electrolyte solution, characterized in that, The electrolyte includes a solvent, a lithium salt, and a diluent. The diluent includes a silicon-carbon bond-containing diluent, a silicon-oxygen bond-containing diluent, and a silicon-nitrogen bond-containing diluent. Based on the total molar amount of the diluent, the molar ratio of the silicon-carbon bond-containing diluent, the silicon-oxygen bond-containing diluent, and the silicon-nitrogen bond-containing diluent is (0.15 to 0.45):(0.15 to 0.45):(0.15 to 0.45).

2. The electrolyte solution according to claim 1, characterized in that, Based on the total molar amount of the diluent, the molar ratio of the silicon-carbon bond-containing diluent, the silicon-oxygen bond-containing diluent, and the silicon-nitrogen bond-containing diluent is (0.2 to 0.4):(0.2 to 0.4):(0.2 to 0.4).

3. The electrolyte solution according to claim 1, characterized in that, The boiling point of the diluent is less than 150 °C; and / or The viscosity of the diluent is less than 1.5 mPa·s; and / or The dielectric constant of the diluent is greater than 3.

4. The electrolyte solution according to claim 1, characterized in that, Based on the total mass of the electrolyte, the content of the diluent is 20 wt% to 75 wt%.

5. The electrolyte solution according to claim 1, characterized in that, The diluent satisfies at least one of the following conditions: 1) The silicon-carbon bond-containing diluent is at least one of the organic compounds having the structure shown in Formula I, wherein, R1 is selected from fluoro C1-C6 alkyl, phenyl, or C2-C6 alkenyl, and R2, R3, and R4 are each independently selected from C1-C6 alkyl and C2-C6 alkenyl. 2) The silicon-oxygen bond-containing diluent is at least one of the organic compounds having the structure shown in Formula II and the organic compounds having the structure shown in Formula III, Among them, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 , R 14 are each independently selected from C1-C6 alkyl groups. 3) The silicon-nitrogen bond-containing diluent is at least one of the organic compounds having the structure shown in Formula IV, the organic compounds having the structure shown in Formula V, and the organic compounds having the structure shown in Formula VI, Among them, R 15 , R 16 , R 17 , R 18 , R 19 , R 20 , R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R 29 , R 30 , R 31 , R 32 are each independently selected from C1-C6 alkyl groups.

6. The electrolyte solution according to claim 5, characterized in that, The diluent satisfies at least one of the following conditions: 1) The silicon-carbon bond-containing diluent includes at least one of (trifluoromethyl)trimethylsilane, triethyl(trifluoromethyl)silane, (difluoromethyl)trimethylsilane, (chlorodifluoromethyl)trimethylsilane, trimethyl(pentafluoroethyl)silane, trimethylphenylsilane, and tetravinylsilane. 2) The silicon-oxygen bond-containing diluent includes at least one of trimethylmethoxysilane, trimethylethoxysilane, trimethylpropoxysilane, isopropoxythimethylsilane, tert-butoxythimethylsilane, hexamethyldisiloxane, and tetramethyldivinyldisiloxane. 3) The silicon-nitrogen bond-containing diluent includes at least one of heptamethyldisilazane, N,N-dimethyltrimethylsilylamine, and bis(dimethylamino)dimethylsilane.

7. The electrolyte solution according to claim 1, characterized in that, The solvent includes at least one of carbonate solvents, ether solvents, phosphate solvents, nitrile solvents, sulfone solvents, amide solvents, and siloxane solvents; and / or The lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorooxalate borate, lithium bis(oxalate) borate, lithium tetrafluoroborate, and lithium trifluoromethanesulfonate.

8. The electrolyte solution according to claim 7, characterized in that, Based on the total mass of the electrolyte, the mass content of the solvent is 8 wt% to 80 wt%; and / or Based on the total mass of the electrolyte, the mass content of the lithium salt is 7.5 wt% to 31 wt%.

9. A secondary battery, characterized in that, The secondary battery includes the electrolyte according to any one of claims 1 to 8.

10. A device, characterized in that, The device includes the secondary battery according to claim 9.

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