Fast charging electrolyte, lithium ion battery and preparation method and application of lithium ion battery

Abstract

The invention discloses a fast charging electrolyte, a lithium ion battery and a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. The fast charging electrolyte provided by the invention comprises an electrolyte lithium salt, an organic solvent and an additive, the types of the electrolyte lithium salt, the organic solvent and the additive are different; the additives comprise a first additive and a second additive; the first additive comprises at least one of an ester additive, a nitrile additive and a hydrofluoroether compound; the second additive comprises an inorganic salt additive; the addition amount of the first additive is 1-20% of the total mass of the fast charging electrolyte; the addition amount of the second additive is 0.01-5% of the total mass of the fast charging electrolyte. According to the invention, the first additive and the second additive are combined and added into the electrolyte, so that the cycling stability, the fast charging performance and the rate capability of the battery can be remarkably improved under the high voltage of more than or equal to 4.6 V.

Description

Technical Field

[0001] The present application belongs to the technical field of lithium-ion batteries, and in particular to a fast-charging electrolyte, a lithium-ion battery, and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries have attracted much attention due to their advantages such as high operating voltage and high energy density. Since Sony first launched commercial lithium-ion batteries in 1991, lithium-ion batteries have been widely used in various 3C consumer electronics products, electric vehicles, wind power, solar energy, power grids and other power generation equipment. With the rapid development of portable electronic technology and electric vehicles, people have higher and higher requirements for the safety, energy density and long life of lithium-ion batteries. In order to further improve the energy density of batteries, increasing the cutoff voltage of existing positive electrode materials or developing new high-voltage positive electrode materials is the key to achieving higher energy density of lithium-ion batteries.

[0003] However, the current increase in the operating voltage of lithium-ion batteries is limited by the antioxidant capacity of existing commercial electrolytes. In commercial electrolytes, although a high content of EC components can form an excellent and stable solid electrolyte interface (SEI interface) on one side of the graphite negative electrode, this component is unstable under high pressure and is prone to severe oxidative decomposition on the positive electrode surface, resulting in the formation of a high-impedance interface and a sharp capacity decay. At the same time, high pressure causes the dissolution of transition metals in the positive electrode material, which on the one hand damages the electrode structure and affects the stability of the battery. On the other hand, the dissolved metal cations will precipitate at the negative electrode, leading to the formation of metal dendrites, affecting the safety of the battery and limiting the application of electrolytes in the next generation of high-energy lithium-ion batteries. In addition, lithium cobalt oxide battery technology that can simultaneously achieve high energy density and efficient fast charging is an unmet need, especially at low temperatures, where slow ion migration kinetics and unstable electrode / electrolyte interfaces are considered to be the main causes of the above problems.

[0004] The above problems can be solved by regulating the composition of the electrolyte and using functional additives to form a uniform and stable electrode / electrolyte interface at the electrode / electrolyte interface, thereby inhibiting the occurrence of interfacial side reactions. In addition, the strategy of in-situ conversion of the electrode / electrolyte interface through appropriate electrolyte component regulation or additives is simple and efficient, and is more suitable for production and manufacturing in the battery industry. However, there are few reports on successful cases of the above solutions. Summary of the invention

[0005] To solve the above technical problems, the present application provides a fast-charging electrolyte, a lithium-ion battery, and a preparation method and application thereof. By adding functional additives to the electrolyte and utilizing the synergistic effect between multi-component additives, a stable electrode / electrolyte interface (positive electrode / electrolyte interface CEI and negative electrode / electrolyte interface SEI) for rapid lithium ion transmission can be constructed in situ on the positive and negative electrodes of the battery at the same time, thereby effectively isolating the electrode and the electrolyte, and achieving excellent cycle stability and ultra-fast charging performance of high-voltage lithium-ion batteries.

[0006] In order to achieve the above-mentioned invention object, this application provides the following technical solutions:

[0007] In one aspect, the present application provides a fast-charge electrolyte, the fast-charge electrolyte comprising an electrolyte lithium salt, an organic solvent and an additive;

[0008] The types of the electrolyte lithium salt, organic solvent and additive are different;

[0009] The additives include a first additive and a second additive;

[0010] The first additive includes at least one of an ester additive, a nitrile additive, and a hydrofluoroether compound;

[0011] The second additive includes an inorganic salt additive;

[0012] The amount of the first additive added is 1 to 20% of the total mass of the fast charge electrolyte;

[0013] The amount of the second additive added is 0.01 to 5% of the total mass of the fast charge electrolyte;

[0014] The mass ratio of the first additive to the second additive is 2 to 15:1.

[0015] Optionally, the amount of the first additive added is independently selected from any value of 1%, 5%, 10%, 15%, 20% of the total mass of the fast charge electrolyte or a range between any two of the above points.

[0016] Optionally, the amount of the second additive added is independently selected from any value of 0.01%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% of the total mass of the fast charge electrolyte or a range value between any two of the above points.

[0017] Optionally, the ester additive includes at least one of a sulfonate compound, a phosphate compound, and a fluorocarbonate compound.

[0018] Optionally, the sulfonate compound includes at least one of methyl methanesulfonate, ethyl methanesulfonate, n-butyl methanesulfonate, 1,3-propylene sultone, isopropyl methanesulfonate, methyl benzenesulfonate, ethyl benzenesulfonate, and p-toluenesulfonate.

[0019] Optionally, the phosphate compound includes at least one of 1-propyl phosphoric acid cyclic anhydride, tris(trimethylsilyl) phosphate, tris(vinyldimethylsilane) phosphate, phenol ether phosphate, tetramethylmethylene diphosphate, and fatty alcohol ether phosphate.

[0020] Optionally, the fluorinated carbonate compound includes at least one of bis(2,2,2-trifluoroethyl) carbonate, fluoroethylene carbonate, pentafluorophenyl carbonate, trifluoroethyl methyl carbonate, fluoroethyl acetate, bisfluoroethylene carbonate, fluorocarbamate, and bisperfluorophenyl carbonate.

[0021] Optionally, the nitrile additive includes at least one of suberonitrile, succinonitrile, glutaronitrile, adiponitrile, and fluoroadiponitrile.

[0022] Optionally, the hydrofluoroether compound includes at least one of methyl nonafluoroisobutyl ether, hexafluoropropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, ethyl nonafluorobutyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether.

[0023] Optionally, the inorganic salt additive includes at least one of a lithium-containing additive, a sulfur-containing additive, a phosphorus-containing additive, and a boron-containing additive.

[0024] Optionally, the lithium-containing additive includes at least one of lithium nitrate, lithium tetrafluoroborate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorophosphate, and lithium difluorobisfluorooxalatophosphate.

[0025] Optionally, the sulfur-containing additive includes at least one of bis(trifluoromethylsulfonyl)imide salt, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethylsulfonate)imide.

[0026] Optionally, the phosphorus-containing additive includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, sodium orthophosphate, sodium phosphite, and potassium phosphite.

[0027] Optionally, the boron-containing additive includes at least one of lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluorooxalatoborate, fluorinated lithium bis(malonate)borate salt, and lithium bis(2-fluoromalonate)borate.

[0028] Optionally, the amount of the electrolyte lithium salt used is 1 to 15% of the total mass of the fast-charge electrolyte.

[0029] Optionally, the amount of the electrolyte lithium salt is independently selected from any value of 1%, 5%, 8%, 10%, 12%, 15% of the total mass of the fast-charge electrolyte or a range between any two of the above points.

[0030] Optionally, the electrolyte lithium salt includes at least one of lithium tetrafluoroborate, lithium difluorooxalatoborate, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, fluorinated lithium bis(malonate)borate, and lithium bis(2-fluoromalonate)borate.

[0031] Optionally, the organic solvent includes a linear organic solvent and / or a cyclic organic solvent.

[0032] Preferably, the organic solvent includes a linear organic solvent and a cyclic organic solvent.

[0033] Optionally, the volume ratio of the linear organic solvent to the cyclic organic solvent is 0.5 to 4:1.

[0034] Optionally, the volume ratio of the linear organic solvent to the cyclic organic solvent is independently selected from any value of 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1 or a range between any two of the above points.

[0035] Optionally, the linear organic solvent includes at least one of trifluoroethyl methyl carbonate, methyl formate, ethyl acetate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate and ethyl butyrate.

[0036] Optionally, the cyclic organic solvent includes at least one of ethylene carbonate, propylene carbonate, γ-butyrolactone, phenyl acetate and 1,4-butanesultone.

[0037] In a second aspect, the present application provides a method for preparing the above-mentioned fast-charge electrolyte, comprising the following steps:

[0038] A mixture containing lithium salt, organic solvent and additives is dissolved to obtain the fast charge electrolyte.

[0039] Optionally, the dissolving is performed in an inert gas atmosphere.

[0040] Optionally, H2O≤0.1, O2≤0.1 in the inert gas atmosphere.

[0041] Optionally, the inert gas comprises argon.

[0042] In a third aspect, the present application provides a fast-charging lithium-ion battery, the fast-charging lithium-ion battery comprising a positive electrode, a negative electrode, a separator and an electrolyte;

[0043] The electrolyte is selected from the above-mentioned fast-charge electrolyte.

[0044] Optionally, the positive electrode comprises lithium cobalt oxide.

[0045] Optionally, the negative electrode includes at least one of artificial graphite, natural graphite, hard carbon, and silicon.

[0046] Optionally, the diaphragm comprises a polypropylene-based film.

[0047] Optionally, the current of the fast-charging lithium-ion battery is ≥5C.

[0048] In a fourth aspect, the present application provides an application of the above-mentioned fast-charging electrolyte in improving the fast-charging performance of high-voltage lithium-ion batteries.

[0049] Optionally, the application process is to inject the fast-charge electrolyte into a high-voltage lithium-ion battery.

[0050] Optionally, the injection amount of the fast charge electrolyte is 10 to 50 g / Ah.

[0051] Optionally, the injection amount of the fast charge electrolyte is independently selected from any value among 10g / Ah, 15g / Ah, 20g / Ah, 25g / Ah, 30g / Ah, 35g / Ah, 40g / Ah, 45g / Ah, 50g / Ah or a range value between any two of the above points.

[0052] Compared with the prior art, this application has the following beneficial effects:

[0053] (1) In the electrolyte provided by the present application, the first additive decomposes earlier in the electrolyte due to its lower LUMO energy level, and the highly mechanically stable SEI film generated by it can also reduce the interfacial impedance, accelerate the transmission of ions and electrons, and enhance the fast charging capability; the second additive can decompose on the positive electrode surface at above 4.3V to form a layer of inorganic-rich, uniform, dense, and fast lithium ion-transmitting positive electrode interface film, which can effectively stabilize the interface of high-voltage lithium cobalt oxide and inhibit the dissolution of transition metals. At the same time, its good conductivity can effectively reduce the negative electrode interface impedance and improve the power density of the entire battery.

[0054] (2) The present application adds the first additive and the second additive together into the electrolyte, which can significantly improve the cycle stability, fast charge and rate performance of the battery at a high voltage of ≥4.6V.

[0055] (3) In the electrolyte provided in the present application, the mixture of multiple lithium salts or additives can change the properties of the electrolyte solution, such as ionic conductivity, solubility and viscosity, and synergistically improve the positive electrode / electrolyte interface (CEI) and the negative electrode SEI interface by affecting the electrode / electrolyte interface and the electrode material surface interface.

[0056] (4) The preparation method of the electrolyte provided in this application is simple, efficient and highly operable. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0058] Figure 1 This is the LSV curve diagram of the basic electrolyte 2, the electrolyte of Example 1, and the electrolyte of Example 2 of this application. DETAILED DESCRIPTION

[0059] The present application is further described below in conjunction with specific embodiments. The following are only a few embodiments of the present application, and are not intended to limit the present application in any form. Although the present application discloses the following preferred embodiments, they are not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the above disclosed technical content to make some changes or modifications are equivalent to equivalent implementation cases and are within the scope of the technical solution.

[0060] Unless otherwise specified, the raw materials in the examples of the present application were purchased from commercial sources and used directly without any special treatment.

[0061] Unless otherwise specified, the analysis methods in the examples all adopt conventional settings and conventional analysis methods of instruments or equipment.

[0062] Preparation of basic electrolyte 1: In an argon-protected glove box (H2O≤0.1, O2≤0.1), organic carbonate solvents ethylene carbonate EC and diethyl carbonate DEC were mixed in a volume ratio of 1:1 and stirred evenly. Then, electrolyte lithium salt lithium hexafluorophosphate LiPF6 (concentration of 1.2 mol / L) was slowly added to the mixed solution and stirred until completely dissolved to obtain basic electrolyte 1.

[0063] Preparation of basic electrolyte 2: In an argon-protected glove box (H2O≤0.1, O2≤0.1), organic carbonate solvent ethylene carbonate EC and trifluoroethyl methyl carbonate FEMC were mixed as solvents in a volume ratio of 1:1 and stirred evenly. Then, the electrolyte lithium salt lithium hexafluorophosphate LiPF6 (concentration of 1.2 mol / L) was slowly added to the mixed solution and stirred until completely dissolved to obtain basic electrolyte 2.

[0064] Example 1

[0065] In the basic electrolyte 2, 5wt% of 1,3-propylene sulfone (hereinafter referred to as compound 1), 2wt% of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (hereinafter referred to as compound 2) and 0.8wt% of lithium difluorophosphate (hereinafter referred to as compound 5) were added to obtain the fast-charge electrolyte of this embodiment.

[0066] Example 2

[0067] In the basic electrolyte 2, 5wt% of fluoroethylene carbonate (hereinafter referred to as compound 3), 2wt% of compound 2, 0.8wt% of compound 5 and 0.5wt% of lithium tetrafluoroborate (hereinafter referred to as compound 6) were added to obtain the fast-charge electrolyte of this embodiment.

[0068] Example 3

[0069] 2 wt % of compound 2 and 0.8 wt % of compound 5 were added to the basic electrolyte 1 to obtain the fast-charge electrolyte of this embodiment.

[0070] Comparative Example 1

[0071] In the basic electrolyte 1, 5 wt% of compound 1 and 2 wt% of compound 2 were added to obtain the electrolyte of this comparative example.

[0072] Comparative Example 2

[0073] 5 wt % of compound 3 and 2 wt % of compound 2 were added to the basic electrolyte 1 to obtain the electrolyte of this comparative example.

[0074] Comparative Example 3

[0075] In the basic electrolyte 1, 5 wt% of compound 1 and 2 wt% of suberonitrile (hereinafter referred to as compound 4) were added to obtain the electrolyte of this comparative example.

[0076] Comparative Example 4

[0077] 15 wt % of compound 3 and 5 wt % of compound 2 were added to the basic electrolyte 1 to obtain the electrolyte of this comparative example.

[0078] Comparative Example 5

[0079] In the basic electrolyte 2, 5 wt% of compound 1 and 2 wt% of compound 2 were added to obtain the electrolyte of this comparative example.

[0080] Comparative Example 6

[0081] 15 wt % of compound 3 and 5 wt % of compound 2 were added to the basic electrolyte 2 to obtain the electrolyte of this comparative example.

[0082] Comparative Example 7

[0083] 5 wt % of compound 3 and 2 wt % of compound 4 were added to the basic electrolyte 2 to obtain the electrolyte of this comparative example.

[0084] Comparative Example 8

[0085] 15 wt % of compound 3 and 5 wt % of compound 2 were added to the basic electrolyte 1 to obtain the electrolyte of this comparative example.

[0086] Comparative Example 9

[0087] 1 wt % of compound 1 and 2 wt % of compound 3 were added to the basic electrolyte 1 to obtain the electrolyte of this comparative example.

[0088] Comparative Example 10

[0089] The only difference from Comparative Example 1 is that the mass of the lithium salt used accounts for 15% of the total mass of the electrolyte.

[0090] Comparative Example 11

[0091] The only difference from Comparative Example 1 is that the solvent used is only ethyl methyl carbonate (EMC).

[0092] Comparative Example 12

[0093] 5 wt % of compound 3 was added to the basic electrolyte 1 to obtain the electrolyte of this comparative example.

[0094] Comparative Example 13

[0095] 2 wt % of compound 2 was added to the basic electrolyte 1 to obtain the electrolyte of this comparative example.

[0096] Comparative Example 14

[0097] 0.8 wt % of compound 5 was added to the basic electrolyte 2 to obtain the electrolyte of this comparative example.

[0098] Comparative Example 15

[0099] 0.8 wt % of compound 5 was added to the basic electrolyte 1 to obtain the electrolyte of this comparative example.

[0100] Experimental Example 1

[0101] The lithium ion batteries prepared in the above Examples 1 to 3 and Comparative Examples 1 to 15 were subjected to the following related experiments:

[0102] (1) Room temperature cycle performance test: After activation at 0.2C for 3 cycles at 25°C, the battery was cycled at a rate of 1C with a charge and discharge voltage range of 3 to 4.6V.

[0103] (2) Room temperature cycle performance test: After activation at 0.2C for 3 cycles at 25°C, the battery was cycled at a rate of 3C with a charge and discharge voltage range of 3 to 4.6V.

[0104] The results of the above electrochemical performance tests are shown in Table 1.

[0105] Table 1 Comparison of electrochemical performance of electrolytes of Examples 1 to 3 and Comparative Examples 1 to 15

[0106]

[0107] It can be seen from the test results of Examples 1 to 3 and Comparative Example 4 in Table 1 that adding boron- or phosphorus-containing functional additives to the electrolyte can significantly improve the cycle stability and fast charging performance of lithium cobalt oxide at a high voltage of 4.6 V. The reason is that the boron (phosphorus)-containing additives can preferentially oxidize and decompose solvent molecules to form a film on the electrode surface, thereby passivating the electrode / electrolyte interface, inhibiting the decomposition of the electrolyte under high pressure and the occurrence of side reactions, and at the same time effectively inhibiting the damage to the positive electrode structure, thereby improving the cycle stability of lithium-ion batteries.

[0108] It can be seen from the test results of Base 1 (i.e., Basic Electrolyte 1) and Comparative Example 12 in Table 1 that the addition of film-forming additive fluoroethylene carbonate FEC to the electrolyte significantly improves the cycle stability and fast charging capability of 4.6V high-voltage lithium cobalt oxide. This is because the SEI film generated by FEC contains a high content of LiF components, has good mechanical stability, and can also reduce interface impedance.

[0109] It can be seen from the four groups of experimental data of Basis 1, Example 3, Comparative Example 13, and Comparative Example 15 in Table 1 as well as the four groups of experimental data of Basis 2, Example 1, Comparative Example 5, and Comparative Example 14 that the simultaneous addition of the first additive and the second additive to the electrolyte can synergistically regulate the positive electrode CEI and the negative electrode SEI interface by affecting the electrode / electrolyte interface and the electrode material surface interface, thereby effectively improving the cycle stability and fast charging performance of lithium cobalt oxide under high pressure.

[0110] In summary, the electrolyte provided by the present invention can effectively improve the cycle stability and fast charging performance of 4.6V lithium cobalt oxide by optimizing the electrolyte composition and additives and utilizing the synergistic effect between multiple components, and has broad application prospects.

[0111] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A fast-charge electrolyte, characterized in that: The fast-charge electrolyte comprises an electrolyte lithium salt, an organic solvent and an additive; The types of the electrolyte lithium salt, organic solvent and additive are different; The additives include a first additive and a second additive; The first additive includes at least one of an ester additive, a nitrile additive, and a hydrofluoroether compound; The second additive includes an inorganic salt additive; The amount of the first additive added is 1 to 20% of the total mass of the fast charge electrolyte; The amount of the second additive added is 0.01 to 5% of the total mass of the fast charge electrolyte; The mass ratio of the first additive to the second additive is 2 to 15:

1.

2. A fast-charge electrolyte according to claim 1, characterized in that: The ester additive includes at least one of a sulfonate compound, a phosphate compound, and a fluorocarbonate compound; Preferably, the sulfonate compound includes at least one of methyl methanesulfonate, ethyl methanesulfonate, n-butyl methanesulfonate, 1,3-propylene sultone, isopropyl methanesulfonate, methyl benzenesulfonate, ethyl benzenesulfonate, and p-toluenesulfonate; Preferably, the phosphate compound includes at least one of 1-propyl phosphoric acid cyclic anhydride, tris(trimethylsilyl) phosphate, tris(vinyldimethylsilane) phosphate, phenol ether phosphate, tetramethyl methylene diphosphate, and fatty alcohol ether phosphate; Preferably, the fluorinated carbonate compound includes at least one of bis(2,2,2-trifluoroethyl) carbonate, fluoroethylene carbonate, pentafluorophenyl carbonate, trifluoroethyl methyl carbonate, fluoroethyl acetate, bisfluoroethylene carbonate, fluorocarbamate, and bisperfluorophenyl carbonate; Preferably, the nitrile additive includes at least one of suberonitrile, succinonitrile, glutaronitrile, adiponitrile, and fluoroadiponitrile; Preferably, the hydrofluoroether compound includes at least one of methyl nonafluoroisobutyl ether, hexafluoropropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, ethyl nonafluorobutyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether.

3. A fast-charge electrolyte according to claim 1, characterized in that: The inorganic salt additive includes at least one of a lithium-containing additive, a sulfur-containing additive, a phosphorus-containing additive, and a boron-containing additive; Preferably, the lithium-containing additive includes at least one of lithium nitrate, lithium tetrafluoroborate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorophosphate, and lithium difluorobisfluorooxalatophosphate; Preferably, the sulfur-containing additive includes at least one of bis(trifluoromethylsulfonyl)imide salt, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethylsulfonate)imide; Preferably, the phosphorus-containing additive includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, sodium orthophosphate, sodium phosphite, and potassium phosphite; Preferably, the boron-containing additive includes at least one of lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluorooxalatoborate, fluorinated lithium bis(malonate)borate salt, and lithium bis(2-fluoromalonate)borate.

4. A fast-charge electrolyte according to claim 1, characterized in that: The amount of the electrolyte lithium salt is 1 to 15% of the total mass of the fast charge electrolyte; Preferably, the electrolyte lithium salt includes at least one of lithium tetrafluoroborate, lithium difluorooxalatoborate, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, fluorinated lithium bis(malonate)borate, and lithium bis(2-fluoromalonate)borate.

5. A fast-charge electrolyte according to claim 1, characterized in that: The organic solvent includes a linear organic solvent and / or a cyclic organic solvent.

6. A fast-charge electrolyte according to claim 6, characterized in that: The linear organic solvent comprises at least one of trifluoroethyl methyl carbonate, methyl formate, ethyl acetate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, and ethyl butyrate; Preferably, the cyclic organic solvent includes at least one of ethylene carbonate, propylene carbonate, γ-butyrolactone, phenyl acetate, and 1,4-butanesultone.

7. A method for preparing a fast-charge electrolyte according to any one of claims 1 to 6, characterized in that: The steps include: A mixture containing lithium salt, organic solvent and additives is dissolved to obtain the fast charge electrolyte.

8. The method for preparing a fast-charge electrolyte according to claim 7, characterized in that: The dissolving is carried out in an inert gas atmosphere; Preferably, H2O≤0.1, O2≤0.1 in the inert gas atmosphere; Preferably, the inert gas comprises argon.

9. A fast-charge lithium-ion battery, characterized in that: The fast-charge lithium-ion battery comprises a positive electrode, a negative electrode, a separator and an electrolyte; The electrolyte is selected from a fast-charge electrolyte according to any one of claims 1 to 6; Preferably, the positive electrode comprises lithium cobalt oxide; Preferably, the negative electrode comprises at least one of artificial graphite, natural graphite, hard carbon, and silicon; Preferably, the diaphragm comprises a polypropylene-based film; Preferably, the current of the fast-charging lithium-ion battery is ≥5C.

10. Use of the fast-charging electrolyte according to any one of claims 1 to 6 in improving the fast-charging performance of high-voltage lithium-ion batteries; Preferably, the application process is to inject the fast-charge electrolyte into a high-voltage lithium-ion battery; Preferably, the injection amount of the fast charge electrolyte is 10 to 50 g / Ah.

Images