High-entropy electrolyte, preparation method thereof and high-voltage lithium ion battery

Abstract

The invention is suitable for the technical field of materials, and provides a high-entropy electrolyte, a preparation method thereof and a high-voltage lithium ion battery. The high-entropy electrolyte comprises a lithium salt and a high-entropy solvent; the high-entropy solvent is composed of ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate and dipropyl carbonate. According to the present invention, the ethylene carbonate, the dimethyl carbonate, the ethyl methyl carbonate, the diethyl carbonate and the dipropyl carbonate are combined to form the high-entropy solvent system, the solvation structure is adjusted through the super entropy, the high-voltage interface charging and discharging are adapted, the novel positive electrode is matched, the high capacity retention rate requirement is met, the cycle stability and the energy density of the battery are significantly improved, and the service life of the battery is significantly prolonged.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of materials, and particularly relates to a high-entropy electrolyte and a preparation method thereof and a high-voltage lithium ion battery. BACKGROUND

[0002] A novel high-voltage positive electrode material of a lithium ion battery provides a broad prospect for developing a high-energy-density battery, but an interface reaction intensified at a high voltage becomes a key bottleneck, which restricts the practical application of the high-voltage positive electrode material above 4.4 V.

[0003] The voltage window of a commercial electrolyte is jointly affected by inherent electrochemical stability and chemical reactions with electrodes: for example, the electrochemical oxidation potential of a carbonate mixture on an inert metal surface such as Pt can reach about 5.5 V, but under the catalysis of transition metal elements of a positive electrode, oxidation easily occurs at a lower voltage, resulting in that the commercial electrolyte can only maintain about 4.3 V stability in an actual lithium ion battery. Under a high-voltage condition, the oxidized positive electrode surface releases oxygen molecules and oxygen radicals, which further react with the electrolyte; although solvent molecules such as ethylene carbonate (EC) can be oxidized and polymerized on the high-catalysis surface of the positive electrode to form polycarbonate protective substances to inhibit high-voltage side reactions, the stability of the polycarbonate at a high voltage is still insufficient.

[0004] Therefore, the commercial electrolyte is difficult to support the operation of a high-voltage lithium ion battery, and effective regulation of the interface reaction has become a core problem for realizing the application of the next generation of high-specific-energy batteries. SUMMARY

[0005] The purpose of the embodiment of the application is to provide a high-entropy electrolyte, which aims to solve the problem that the electrolyte in the existing high-voltage lithium ion battery is decomposed due to unstable interface, resulting in poor cycle performance.

[0006] The embodiment of the application is implemented in this way. A high-entropy electrolyte comprises a lithium salt and a high-entropy solvent; wherein the high-entropy solvent is composed of ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate and dipropyl carbonate.

[0007] Preferably, the molar concentration of the lithium salt is 1-2 mol / L.

[0008] Preferably, the molar ratio of the ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate and dipropyl carbonate is 1-48:1-36:1-30:1-25:1-20.

[0009] Another purpose of the embodiment of the application is a preparation method of the above-mentioned high-entropy electrolyte, comprising:

[0010] The ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate and dipropyl carbonate are mixed uniformly under inert atmosphere to obtain a high-entropy solvent;

[0011] 4A molecular sieve is added to the high-entropy solvent, heated to 50-80℃ and kept for 2-8 hours, and after cooling, lithium salt is added, and stirred at room temperature until the system is clear and transparent, to obtain a high-entropy electrolyte.

[0012] Another purpose of the embodiments of the present application is a high-voltage lithium ion battery, which comprises the high-entropy electrolyte, the positive electrode and the negative electrode described above.

[0013] Preferably, the positive electrode is a lithium-rich manganese-based layered positive electrode material.

[0014] The high-entropy electrolyte provided by the embodiments of the present application forms a high-entropy solvent system by combining ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate and dipropyl carbonate, reduces the energy that can be released by maintaining the original solvation structure of the electrolyte, increases the energy gradient of forming a favorable solvation structure, thereby expanding the electrochemical window of the electrolyte system; at the same time, the solvation structure can be adjusted by super-entropy under the original solvent system, to adapt to the charging and discharging process under the high-voltage interface, better match the new type of lithium ion battery positive electrode, meet the high capacity retention rate requirement, and significantly improve the cycle stability, energy density and service life of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The cycle capacity retention rate of the lithium-rich manganese-based layered positive electrode-lithium metal negative electrode lithium ion battery of Example 1, Example 2 and Comparative Example 1 of the present application is tested at a current density of 100mAg -1 ;

[0016] Figure 2 The cycle capacity retention rate of the lithium-rich manganese-based layered positive electrode-lithium metal negative electrode lithium ion battery of Example 1, Example 2 and Comparative Example 1 of the present application is tested at a current density of 1000mAg -1 ;

[0017] Figure 3 The solvation structure super-entropy numerical column chart of Comparative Example 1, Comparative Example 12, Example 1 and Example 2 of the present application shows that Example 1 and Example 2 achieve high-entropy effect. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0019] The embodiment of the present application is to solve the problem that the electrolyte in the existing high-voltage lithium ion battery decomposes due to unstable interface, resulting in poor cycle performance. A high-entropy electrolyte is provided, which forms a high-entropy solvent system by combining ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, and dipropyl carbonate. The high-entropy electrolyte can adjust the solvation structure under the original solvent system through hyper-entropy, adapt to the charging and discharging process under the high-pressure interface, and better match the new lithium ion battery positive electrode, meet the high capacity retention requirement, and significantly improve the cycle stability, energy density, and service life of the battery.

[0020] Specifically, the embodiment of the present application provides a high-entropy electrolyte suitable for the characteristics of a high-voltage positive electrode of a lithium ion battery, which comprises a lithium salt and a high-entropy solvent. The high-entropy solvent is composed of ethylene carbonate (EC), dimethyl carbonate (DMC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), and dipropyl carbonate (DPC). Preferably, the molar ratio of ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, and dipropyl carbonate is 1-48:1-36:1-30:1-25:1-20.

[0021] The lithium salt can be at least one of lithium bis(trifluoromethylsulfonyl), lithium bisfluorosulfonylimide, lithium hexafluorophosphate, lithium difluorophosphate, lithium hexafluoroborate, lithium bisoxalate borate, lithium difluoro(oxalato)borate, lithium trifluoromethanesulfonylimide, lithium bis(pentafluoroethanesulfonyl)imide, lithium tris(trifluoromethylsulfonyl)methide, lithium bis(trifluoromethylsulfonyl)imide, lithium hexafluoroantimonate, lithium hexafluoroarsenate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium nitrate, lithium carbonate, lithium sulfate, and lithium chloride; preferably at least one of lithium bis(trifluoromethylsulfonyl), lithium bisfluorosulfonylimide, and lithium hexafluorophosphate; and more preferably lithium hexafluorophosphate (LiPF6).

[0022] The molar concentration of the lithium salt is 0.5-2.5 mol / L; and further preferably 1-2 mol / L. Based on the preferred high-entropy combination of the above-mentioned ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, and dipropyl carbonate solvents, good optimization results can be achieved under different molar concentrations of lithium salt to adapt to the unconventional high-voltage positive electrode interface, which can exhibit high interface stability and excellent cycle stability.

[0023] It is worth noting that commercial electrolyte often uses the most suitable component in solute and solvent as commercial component, for example, lithium ion battery often uses lithium hexafluorophosphate (LiPF6) as solute and carbonate as solvent, wherein considering that the ion conductivity increases first and then decreases with the concentration, therefore 1 mol / L LiPF6 is the commonly used concentration. When the functional requirements and use conditions change, the electrolyte formula will be specially designed, such as flame retardant design and high pressure resistance design, but this will bring cost problems and weakening of some performance after changing components. In particular, the high-entropy electrolyte system described in the embodiments of the present application does not rely on species change and specific group design, but drives the solvation structure with intrinsic properties, which can universally adapt to the liquid electrolyte system, and meets the requirements of high interface stability and excellent cycle performance. The optimal high-entropy formula of carbonate provided by the embodiments of the present application is that the lithium salt is 1-2 mol / L LiPF6, the solvent is EC, DMC, EMC, DEC and DPC in a molar ratio of 1:1:1:1:1, 48:36:30:25:20. Fluorinated ethylene carbonate is not selected as a similar matrix due to the large difference in physicochemical properties after fluorination.

[0024] The embodiments of the present application also provide a preparation method of the above-mentioned high-entropy electrolyte, comprising:

[0025] Under an inert atmosphere, ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate and dipropyl carbonate are uniformly mixed to obtain a high-entropy solvent;

[0026] 4A molecular sieves are added to the high-entropy solvent, heated to 50-80°C and kept for 2-8 hours, and then lithium salt is added after cooling, and stirred at room temperature until the system is clear and transparent, thereby obtaining a high-entropy electrolyte.

[0027] The above steps are carried out in an argon-filled glove box, and the water content and oxygen content are both below 0.1 ppm. It should be noted that after water removal is completed, the 4A molecular sieves can be removed or retained, which only serves the function of water removal in this process, and the specific amount can be adjusted by the person skilled in the art according to the initial water content of the organic solvent and the actual water removal requirement.

[0028] The embodiments of the present application also provide a high-pressure lithium ion battery comprising the above-mentioned high-entropy electrolyte.

[0029] In the present application, the high-voltage lithium ion battery comprises the high-entropy electrolyte, and other components and structures can be known. For example, the positive electrode of the high-voltage lithium ion battery is made of at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium manganese oxide, lithium nickel manganese oxide, lithium cobalt oxide, nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, and at least one of sulfur positive electrode, sulfur carbon positive electrode, air positive electrode, and the like, preferably, the positive electrode is a lithium-rich manganese-based layered positive electrode material. The negative electrode is made of at least one of metal lithium, graphite, silicon negative electrode, silicon-carbon negative electrode, silicon monoxide and lithium titanate, preferably, the negative electrode is made of metal lithium. The separator is made of one of polyethylene, polypropylene, PP / PE / PP three-layer composite film and glass fiber film.

[0030] The high-entropy electrolyte, the preparation method thereof and the high-voltage lithium ion battery provided by the present application are described in detail through specific examples. In the examples, the experimental methods used are conventional methods unless otherwise specified; the materials, reagents and the like used are conventional products that can be obtained from commercial channels unless otherwise specified.

[0031] Example 1

[0032] The high-entropy electrolyte is composed of a lithium salt and a high-entropy solvent, wherein the lithium salt is 1 mol / L LiPF6, and the high-entropy solvent is EC, DMC, EMC, DEC and DPC in a molar ratio of 1:1:1:1:1.

[0033] In an argon-filled glove box, EC, DMC, EMC, DEC and DPC taken in a molar ratio of 1:1:1:1:1 were mixed uniformly to obtain a high-entropy solvent; 4A molecular sieves were added to the high-entropy solvent, heated to 50°C and kept for 2 hours, then 1 mol / L LiPF6 was added after cooling, stirred at room temperature until the system was clear and transparent, and a high-entropy electrolyte was obtained.

[0034] Example 2

[0035] The high-entropy electrolyte is composed of a lithium salt and a high-entropy solvent, wherein the lithium salt is 2 mol / L LiPF6, and the high-entropy solvent is EC, DMC, EMC, DEC and DPC in a molar ratio of 1:1:1:1:1.

[0036] In an argon-filled glove box, EC, DMC, EMC, DEC and DPC taken in a molar ratio of 1:1:1:1:1 were mixed uniformly to obtain a high-entropy solvent; 4A molecular sieves were added to the high-entropy solvent, heated to 50°C and kept for 2 hours, then 2 mol / L LiPF6 was added after cooling, stirred at room temperature until the system was clear and transparent, and a high-entropy electrolyte was obtained.

[0037] Example 3

[0038] The high-entropy electrolyte is composed of a lithium salt and a high-entropy solvent, wherein the lithium salt is 1 mol / L LiPF6, and the high-entropy solvent is EC, DMC, EMC, DEC and DPC in a molar ratio of 48:36:30:25:20.

[0039] In an argon-filled glove box, EC, DMC, EMC, DEC and DPC in a molar ratio of 48:36:30:25:20 were uniformly mixed to obtain a high-entropy solvent; 4A molecular sieves were added to the high-entropy solvent, heated to 50°C and kept for 2 hours, and then 2 mol / L LiPF6 was added after cooling, and stirred at room temperature until the system was clear and transparent, thereby obtaining a high-entropy electrolyte.

[0040] Comparative Example 1

[0041] The electrolyte is composed of a lithium salt and a solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is EC and DMC in a molar ratio of 1:1.

[0042] In an argon-filled glove box, EC and DMC in a molar ratio of 1:1 were uniformly mixed to obtain a solvent; 4A molecular sieves were added to the solvent, heated to 50°C and kept for 2 hours, and then 1 mol / L LiPF6 was added after cooling, and stirred at room temperature until the system was clear and transparent, thereby obtaining an electrolyte.

[0043] Comparative Example 2

[0044] The electrolyte is composed of a lithium salt and a solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is EC and DEC in a molar ratio of 1:1.

[0045] In an argon-filled glove box, EC and DEC in a molar ratio of 1:1 were uniformly mixed to obtain a solvent; 4A molecular sieves were added to the solvent, heated to 50°C and kept for 2 hours, and then 1 mol / L LiPF6 was added after cooling, and stirred at room temperature until the system was clear and transparent, thereby obtaining an electrolyte.

[0046] Comparative Example 3

[0047] The electrolyte is composed of a lithium salt and a solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is EC, DMC and EMC in a molar ratio of 1:1:1.

[0048] In an argon-filled glove box, EC, DMC and EMC in a molar ratio of 1:1:1 were uniformly mixed to obtain a solvent; 4A molecular sieves were added to the solvent, heated to 50°C and kept for 2 hours, and then 1 mol / L LiPF6 was added after cooling, and stirred at room temperature until the system was clear and transparent, thereby obtaining an electrolyte.

[0049] Comparative Example 4

[0050] The electrolyte is composed of lithium salt and solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is EC, DMC and DEC in a molar ratio of 1:1:1.

[0051] In an argon-filled glove box, EC, DMC and DEC in a molar ratio of 1:1:1 were uniformly mixed to obtain a solvent; 4A molecular sieve was added to the solvent, heated to 50°C and kept for 2 hours, then 1 mol / L LiPF6 was added after cooling, stirred at room temperature until the system was clear and transparent, to obtain the electrolyte.

[0052] Comparative Example 5

[0053] The electrolyte is composed of lithium salt and solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is EC, DMC and DPC in a molar ratio of 1:1:1.

[0054] In an argon-filled glove box, EC, DMC and DPC in a molar ratio of 1:1:1 were uniformly mixed to obtain a solvent; 4A molecular sieve was added to the solvent, heated to 50°C and kept for 2 hours, then 1 mol / L LiPF6 was added after cooling, stirred at room temperature until the system was clear and transparent, to obtain the electrolyte.

[0055] Comparative Example 6

[0056] The electrolyte is composed of lithium salt and solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is EC, EMC and DEC in a molar ratio of 1:1:1.

[0057] In an argon-filled glove box, EC, EMC and DEC in a molar ratio of 1:1:1 were uniformly mixed to obtain a solvent; 4A molecular sieve was added to the solvent, heated to 50°C and kept for 2 hours, then 1 mol / L LiPF6 was added after cooling, stirred at room temperature until the system was clear and transparent, to obtain the electrolyte.

[0058] Comparative Example 7

[0059] The electrolyte is composed of lithium salt and solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is EC, DMC, EMC and DEC in a molar ratio of 1:1:1:1.

[0060] In an argon-filled glove box, EC, DMC, EMC and DEC in a molar ratio of 1:1:1:1 were uniformly mixed to obtain a solvent; 4A molecular sieve was added to the solvent, heated to 50°C and kept for 2 hours, then 1 mol / L LiPF6 was added after cooling, stirred at room temperature until the system was clear and transparent, to obtain the electrolyte.

[0061] Comparative Example 8

[0062] The electrolyte is composed of lithium salt and solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is EC, DMC, EMC and DPC in a molar ratio of 1:1:1:1.

[0063] In an argon-filled glove box, EC, DMC, EMC and DPC in a molar ratio of 1:1:1:1 were uniformly mixed to obtain a solvent; 4A molecular sieve was added to the solvent, heated to 50°C and kept for 2 hours, and then 1 mol / L LiPF6 was added after cooling, stirred at room temperature until the system was clear and transparent, to obtain the electrolyte.

[0064] Comparative Example 9

[0065] The electrolyte is composed of lithium salt and solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is EC, DMC, DEC and DPC in a molar ratio of 1:1:1:1.

[0066] In an argon-filled glove box, EC, DMC, DEC and DPC in a molar ratio of 1:1:1:1 were uniformly mixed to obtain a solvent; 4A molecular sieve was added to the solvent, heated to 50°C and kept for 2 hours, and then 1 mol / L LiPF6 was added after cooling, stirred at room temperature until the system was clear and transparent, to obtain the electrolyte.

[0067] Comparative Example 10

[0068] The electrolyte is composed of lithium salt and solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is EC, PC, DMC, EMC, DEC and DPC in a molar ratio of 0.5:0.5:1:1:1:1.

[0069] In an argon-filled glove box, EC, PC, DMC, EMC, DEC and DPC in a molar ratio of 0.5:0.5:1:1:1:1 were uniformly mixed to obtain a solvent; 4A molecular sieve was added to the solvent, heated to 50°C and kept for 2 hours, and then 1 mol / L LiPF6 was added after cooling, stirred at room temperature until the system was clear and transparent, to obtain the electrolyte.

[0070] Comparative Example 11

[0071] The electrolyte is composed of lithium salt and solvent, wherein the lithium salt is 1 mol / L LiPF6, and the solvent is PC, DMC, EMC, DEC and DPC in a molar ratio of 1:1:1:1:1.

[0072] In an argon-filled glove box, EC, DMC, EMC, DEC, DPC in a 1:1:1:1:1 molar ratio were mixed uniformly to obtain a solvent; 4A molecular sieves were added to the solvent, heated to 50°C and kept for 2 hours, and then 1 mol / L LiPF6 was added after cooling. The system was stirred at room temperature until it was clear and transparent, and an electrolyte was obtained.

[0073] Comparative Example 12

[0074] The electrolyte was composed of a lithium salt and a solvent, wherein the lithium salt was 3 mol / L LiPF6, and the solvent was EC, DMC, EMC, DEC, DPC in a 1:1:1:1:1 molar ratio.

[0075] In an argon-filled glove box, EC, DMC, EMC, DEC, DPC in a 1:1:1:1:1 molar ratio were mixed uniformly to obtain a solvent; 4A molecular sieves were added to the solvent, heated to 50°C and kept for 2 hours, and then 3 mol / L LiPF6 was added after cooling. The system was stirred at room temperature until it was clear and transparent, and an electrolyte was obtained.

[0076] Comparative Example 13

[0077] The electrolyte was composed of a lithium salt and a solvent, wherein the lithium salt was 1 mol / L LiPF6, and the solvent was EC, DMC, EMC, DEC in a 48:36:30:25 molar ratio.

[0078] In an argon-filled glove box, EC, DMC, EMC, DEC in a 48:36:30:25 molar ratio were mixed uniformly to obtain a solvent; 4A molecular sieves were added to the solvent, heated to 50°C and kept for 2 hours, and then 1 mol / L LiPF6 was added after cooling. The system was stirred at room temperature until it was clear and transparent, and an electrolyte was obtained.

[0079] Comparative Example 14

[0080] The electrolyte was composed of a lithium salt and a solvent, wherein the lithium salt was 1 mol / L LiPF6, and the solvent was EC, DMC in a 4:3 molar ratio.

[0081] In an argon-filled glove box, EC, DMC in a 4:3 molar ratio were mixed uniformly to obtain a solvent; 4A molecular sieves were added to the solvent, heated to 50°C and kept for 2 hours, and then 1 mol / L LiPF6 was added after cooling. The system was stirred at room temperature until it was clear and transparent, and an electrolyte was obtained.

[0082] The electrolytes obtained in Examples 1-3 and Comparative Examples 1-14 above were used for electrochemical performance test, with a lithium-rich manganese-based layered material as the positive electrode, lithium metal as the negative electrode, and PP as the separator, to assemble a CR2025 type button cell.-1 and 1000 mAg -1 The current density of 0.1C Figures 1-2

[0083] The lithium ion battery was assembled according to the following steps:

[0084] The positive sheet was cut into a 12 mm diameter round sheet by a sheet punching machine, and then dried in a 80°C air oven for 24 h to remove water, and then transferred to a vacuum drying oven at 80°C for 12 h to further remove trace amounts of water, and then transferred to a glove box, and then assembled into a button cell according to the order of "positive shell-positive sheet-separator-50 μL electrolyte-separator-50 μL electrolyte-negative sheet / negative current collector-stainless steel gasket-spring-negative shell", and then sealed with a sealing machine. The main composition of the positive electrode is: positive active material (lithium-rich manganese-based layered material): Super P: PVDF = 8: 1: 1.

[0085] Table 1

[0086]

[0087] The super-entropy value of the solvent system of the above-mentioned examples 1-2, comparative example 1 and comparative example 12 was tested according to the following method: first, assemble a H-shaped device, and then connect the two sides of the device through a PP separator, and then add the same electrolyte to be tested to the two sides of the device to ensure that the electrolyte on both sides is the same height and higher than the top of the middle channel; then insert a temperature measuring device and a potential measuring device (which includes a stainless steel rod and a fixed lithium sheet) into the two sides of the device, and connect the temperature measuring device with a temperature measuring instrument and the potential measuring device with a potential meter, and then start the equipment to continuously measure the temperature difference and potential difference on both sides; next, the electrolyte tank on one side of the device is heated, and each heating of 10°C is taken as a measurement point, and the next heating is carried out after the voltage difference and temperature difference on both sides are stable, and the heating range is controlled at 35-85°C; finally, the temperature difference of each stable measurement point is taken as the independent variable, and the voltage difference is taken as the dependent variable to carry out data fitting, and the fitting slope is linearly related to the entropy value change of the solvent structure formed by the electrolyte The test results are shown in Table 1 and Figure 3 It is shown that the electrolytes of examples 1 and 2 can achieve high entropy effect.

[0088] ​In summary, the high-entropy electrolyte system provided by the embodiments of the present application can be universally adapted to liquid electrolyte systems by virtue of intrinsic characteristic driving solvation structure, while meeting the requirements of high interface stability and excellent cycle performance. Among them, embodiments 1-2 correspond to the optimal high-entropy formula of carbonates, specifically, the lithium salt uses 1-2 mol / L LiPF6, and the solvents are EC, DMC, EMC, DEC and DPC with a molar ratio of 1:1:1:1:1, 48:36:30:25:20.

[0089] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent of the present application. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

[0090] The above only describes the preferred embodiments of the present application, and does not limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A high-entropy electrolyte, characterized in that, The high-entropy electrolyte comprises lithium salt and a high-entropy solvent; wherein the high-entropy solvent is composed of ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and dipropyl carbonate.

2. The high-entropy electrolyte according to claim 1, characterized in that, The molar concentration of the lithium salt is 0.5–2.5 mol / L.

3. The high-entropy electrolyte according to claim 1, characterized in that, The molar concentration of the lithium salt is 1–2 mol / L.

4. The high-entropy electrolyte according to claim 1, characterized in that, The molar ratio of ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and dipropyl carbonate is 1-48:1-36:1-30:1-25:1-20.

5. The high-entropy electrolyte according to claim 1, characterized in that, The lithium salt is at least one of the following: lithium bis(trifluoromethanesulfonyl), lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium difluorophosphate, lithium hexafluoroborate, lithium bis(oxalate)borate, lithium difluoro(oxalate)borate, lithium trifluoromethanesulfonylimide, lithium bis(pentafluoroethanesulfonyl)imide, lithium tri(trifluoromethanesulfonyl)methyl, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluoroantimonyate, lithium hexafluoroarsenate, lithium perchlorate, lithium trifluoropotassium sulfonate, lithium nitrate, lithium carbonate, lithium sulfate, and lithium chloride.

6. The high-entropy electrolyte according to claim 1, characterized in that, The lithium salt is at least one of bis(trifluoromethanesulfonyl)lithium, bisfluorosulfonylimidelithium, and lithium hexafluorophosphate.

7. The high-entropy electrolyte according to claim 1, characterized in that, The lithium salt is lithium hexafluorophosphate.

8. A method for preparing the high-entropy electrolyte according to any one of claims 1-7, characterized in that, include: In an inert atmosphere, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and dipropyl carbonate are mixed evenly to obtain a high-entropy solvent. Add 4A molecular sieve to the high-entropy solvent, heat to 50-80℃ and maintain for 2-8 hours, cool and add lithium salt, and stir at room temperature until the system is clear and transparent to obtain the high-entropy electrolyte.

9. A high-voltage lithium-ion battery, characterized in that, The high-voltage lithium-ion battery includes the high-entropy electrolyte, positive electrode, and negative electrode as described in any one of claims 1-7.

10. The high-voltage lithium-ion battery according to claim 9, characterized in that, The cathode is a lithium-rich manganese-based basal cathode material.

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