High-voltage-resistant wide-temperature-range electrolyte of fast-charging type lithium battery, preparation method and application of high-voltage-resistant wide-temperature-range electrolyte

Abstract

The invention belongs to the technical field of lithium battery electrolytes, and relates to a high-voltage-resistant wide-temperature-range electrolyte of a fast-charging type lithium battery, a preparation method and application of the high-voltage-resistant wide-temperature-range electrolyte of the fast-charging type lithium battery. The organic solvent is a weakly-solvated fluorine-containing solvent, the organic solvent is a mixed solvent of cyclic fluoro-carbonate, chain fluoro-carbonate and a weakly-polar ether solvent, and the volume ratio of the cyclic fluoro-carbonate to the chain fluoro-carbonate to the weakly-polar ether solvent in the mixed solvent is (1-2): (2-4): (2-4); the lithium salt is lithium hexafluorophosphate; the additive comprises a lithium salt additive and / or a multivalent cation salt additive; the lithium salt additive does not contain lithium hexafluorophosphate; the application temperature of the electrolyte can be expanded to-30 DEG C to 70 DEG C, the electrolyte can be stably circulated at different temperatures, rapid charging and discharging are achieved, and the preparation method is simple, easy to implement and suitable for commercialized development.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery electrolytes, and relates to a high-voltage wide-temperature-range electrolyte for fast-charging lithium batteries, a preparation method and applications thereof. Background Art

[0002] In recent years, lithium-ion batteries (LIBs) with high energy density, high safety, wide-temperature-range adaptability and long cycle life have become the research focus in the energy storage field. With the rapid development of new energy technologies, the demand for energy density in next-generation energy storage devices has shown exponential growth, which has promoted breakthrough research on high-voltage cathode materials. Among them, cobalt-free LiNi 0.5 Mn 1.5 O4 (LNMO) has become a highly potential candidate material due to its high working voltage platform of 4.7 V (vs. Li / Li) and theoretical energy density of 650 Wh kg -1 . At the same time, the high-nickel ternary material LiNi 1-x-y Co x Mn y O2 (NCM) is regarded as the core cathode material for next-generation power lithium batteries due to its high specific capacity, low cost and excellent safety.

[0003] However, the engineering application of high-energy-density battery systems still faces multiple challenges. The performance degradation under high-voltage conditions is particularly prominent: traditional carbonate electrolytes undergo severe oxidative decomposition above 4.3 V, and the generated HF by-products will attack the surface of the cathode particles, resulting in the dissolution of Mn / Ni ions, triggering crystal structure collapse, interfacial side reactions and increased internal resistance, ultimately limiting the fast-charging ability of the battery. In addition, although the electrolyte based on EC has strong lithium salt dissolution ability, its strong coordination effect leads to an increase in the desolvation energy barrier of lithium ions, significantly reducing the ion migration kinetics. The narrow liquid-phase temperature window of commercial electrolytes further restricts the environmental adaptability of the battery. At low temperatures, the viscosity of the electrolyte surges, and the lithium-ion transport between the cathode material and the electrolyte is blocked; at high temperatures (>55 °C), the decomposition of LiPF6 and organic solvents is accelerated, resulting in rapid capacity decay. An ideal electrolyte system should meet the following core requirements: (1) have oxidation stability towards high-voltage cathodes; (2) form a stable inorganic interface layer through an anion-dominated solvation structure; (3) have low desolvation energy to ensure fast lithium-ion diffusion kinetics; (4) have a wide liquid-phase temperature range, low viscosity and high-temperature stability. Although some stage progress has been made in the field of electrolyte optimization, there are still significant challenges in achieving a synergistic breakthrough in high-voltage resistance, fast charging and wide-temperature-range performance through solvation structure design. Compared with traditional cathode modification methods, electrolyte engineering provides a more efficient technical path for solving the core problems of high-voltage battery systems by directly regulating the chemical behavior of the solid-liquid interface.

[0004] Therefore, there is a need for an electrolyte that can withstand high voltages, support fast charging, and operate stably over a wide temperature range to solve the above technical problems. Summary of the Invention

[0005] In view of the common problems faced by high-energy-density lithium-ion batteries, such as the decline in high-voltage performance, limited fast charging, and insufficient adaptability over a wide temperature range, the present invention proposes a fast-charging wide-temperature-range high-voltage electrolyte system with a rich anion solvation structure. By precisely regulating the solvation structure and interfacial chemical behavior, this electrolyte breaks through the performance bottleneck of traditional carbonate electrolytes. Its core components include lithium hexafluorophosphate as the main lithium salt to ensure high-voltage stability, organic / inorganic salts containing heteroatoms such as sulfur, boron, and nitrogen (such as LiTFSI, LiBOB) to enhance the interfacial film performance, and trans-difluoroethylene carbonate (DFEC); chain fluorinated carbonates, and fluorine-containing weakly polar solvents such as 2,2,2-trifluoroethyl methyl carbonate (FEMC) form a unique rich anion aggregate solvation sheath structure with the lithium salt and additives. During charge and discharge, this design decomposes to form a CEI / SEI film rich in inorganic substances such as F, B, and N, which has both high ionic conductivity and thermal stability, effectively inhibiting the oxidation and decomposition of the electrolyte and reducing the desolvation energy barrier of lithium ions. By optimizing the solvent system, the application temperature of this electrolyte can be extended to -30°C to 70°C, supporting fast charging capabilities above 5C. This electrolyte can stably cycle at different temperatures, enabling fast charge and discharge, and its preparation method is simple and easy to implement, making it suitable for commercial development.

[0006] The technical solution adopted by the present invention to solve the technical problems is: a high-voltage wide-temperature-range electrolyte for a fast-charging lithium battery, comprising: an organic solvent, a lithium salt, and an additive;

[0007] The organic solvent is a weakly solvating fluorine-containing solvent, and the organic solvent is a mixed solvent of a cyclic fluorinated carbonate, a chain fluorinated carbonate, and a weakly polar ether-based solvent. The volume ratio of the cyclic fluorinated carbonate, the chain fluorinated carbonate, and the weakly polar ether-based solvent in the mixed solvent is: (1 - 2):(2 - 4):(2 - 4); the lithium salt is lithium hexafluorophosphate; the additive includes: a lithium salt additive and / or a polyvalent cation salt additive; the lithium salt additive does not include lithium hexafluorophosphate.

[0008] Preferably, the cyclic fluorinated carbonate includes: fluoroethylene carbonate FEC, trans-difluoroethylene carbonate DFEC;

[0009] The chain fluorinated carbonate includes: 2,2,2-trifluoroethyl methyl carbonate FEMC;

[0010] The weakly polar ether-based solvent includes: 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether HFE, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether TTE, tetrahydrofuran THF, bis(2,2,2-trifluoroethyl) ether BTFE.

[0011] Preferably, the lithium salt additive includes: lithium difluoro(oxalato)borate, lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium tetrafluoroborate, lithium nitrate, lithium sulfide, lithium fluoride.

[0012] Preferably, the multivalent cation salt additive includes: magnesium bis(trifluoromethylsulfonyl)imide, zinc bis(trifluoromethanesulfonyl)imide, aluminum trifluoromethanesulfonate.

[0013] Preferably, the molar concentration of the lithium salt after being dissolved in the organic solvent is 1 - 2 mol / L; the molar concentration of the lithium salt additive after being dissolved in the organic solvent is 0.01 - 0.1 mol / L; the molar concentration of the multivalent cation salt additive after being dissolved in the organic solvent is 0.01 - 0.1 mol / L.

[0014] The present invention also discloses a preparation method of an electrolyte for a fast - charging lithium battery with high voltage and wide temperature range, which is used to prepare the above - mentioned electrolyte for a fast - charging lithium battery with high voltage and wide temperature range; the preparation method includes the following steps:

[0015] Step 1: Under anhydrous and anaerobic conditions, place the dried molecular sieve in the cyclic fluorocarbonate, linear fluorocarbonate, and weakly polar ether - based solvent respectively and let it stand to remove the moisture in each solvent.

[0016] Step 2: Mix the cyclic fluorocarbonate, linear fluorocarbonate, and weakly polar ether - based solvent according to the volume ratio of (1 - 2):(2 - 4):(2 - 4) and stir magnetically until evenly mixed to obtain a mixed solution A.

[0017] Step 3: Add the lithium salt and the additive to the solvent A, and through further stirring, configure an electrolyte for a fast - charging lithium battery with high voltage and wide temperature range.

[0018] Preferably, in the step 3, the molar concentration of the lithium salt is 1 - 2 mol / L, and the molar concentration of the additive is 0.01 - 0.1 mol / L.

[0019] The present invention also discloses a fast - charging lithium battery with high voltage and wide temperature range. The lithium battery uses the above - mentioned electrolyte for a fast - charging lithium battery with high voltage and wide temperature range, and the lithium battery includes: a positive electrode material, a negative electrode material, and a separator.

[0020] Preferably, the positive electrode material is a positive electrode material with high energy density, and the positive electrode material includes: cobalt - free lithium nickel manganate, ternary positive electrode material, and the ternary positive electrode material includes: NCM811, NCM9 series.

[0021] Preferably, the positive electrode material includes: LiNi 1 x y Co x Mn y O2, LiNi 1xy Cox Al y O2, LiMO2, where M = Ni, Co, Mn, 0 ≤ x < 1, 0 ≤ y < 1, 0 ≤ x + y < 1; the negative electrode active material is metallic lithium and lithium titanate.

[0022] The beneficial effects of the present invention are as follows:

[0023] The fast charging type high voltage wide temperature range electrolyte with weak solvation of the present invention enables the LNMO||Li button battery to still have a reversible specific capacity of 118.6 mAh g -1 at a charge-discharge rate of 5C within the voltage range of 3.5 - 5.0V. It has a capacity retention rate of 92.8% after 800 cycles at 2C, and an average Coulombic efficiency as high as 99.7%; at a high temperature of 70°C with 1C cycling for 120 times, it has a capacity retention rate of 88.7%. At a low temperature of -20°C with 0.2C cycling for 200 times, it has a capacity retention rate of 98.4%. In addition, for the NCM811||Li button battery within the voltage range of 3.0 - 4.3V, the average Coulombic efficiency is as high as 99.9%. Within the voltage range of 3 - 4.6V with 1C cycling for 200 times, it has a capacity retention rate of 87.4%, and the 5C discharge specific capacity reaches 189.8 mAh g -1 . Using the NCM(9 series)||Li battery, it has a capacity retention rate of 87.5% after 500 cycles within the voltage range of 3 - 4.3V, and the 10C discharge specific capacity can reach 175.5 mAh g -1 within the voltage range of 3 - 4.6V, which is much higher than the current high voltage fast charging electrolytes. In addition, since this electrolyte contains fluorine, it greatly expands the electrochemical window of the electrolyte and is not flammable, ensuring the safety of the electrolyte. Description of the Drawings

[0024] Figure 1 It is a linear sweep voltammetry (LSV) curve test graph of the examples and comparative examples of the high voltage wide temperature range electrolyte, preparation method and application of the fast charging type lithium battery of the present invention;

[0025] Figure 2 It is an optical graph of the solubility of different electrolytes of the examples and comparative examples of the present invention;

[0026] Figure 3 It is a flammability test graph of the examples and comparative examples of the present invention;

[0027] Figure 4 It is the first cycle charge-discharge curve at room temperature in the LNMO||Li battery of the examples and comparative examples of the present invention;

[0028] Figure 5 It is a room temperature cycle performance graph in the LNMO||Li battery of the examples and comparative examples of the present invention;

[0029] Figure 6 Room temperature rate performance graphs of the examples and comparative examples of the present invention in LNMO||Li batteries;

[0030] Figure 7 High temperature 60°C cycle performance graphs of the examples and comparative examples of the present invention in LNMO||Li batteries;

[0031] Figure 8 High temperature 70°C cycle performance graphs of the examples and comparative examples of the present invention in LNMO||Li batteries;

[0032] Figure 9 Low temperature -20°C cycle performance graphs of the examples and comparative examples of the present invention in LNMO||Li batteries;

[0033] Figure 10 Charge and discharge curves at different temperatures of the examples and comparative examples of the present invention in LNMO||Li batteries;

[0034] Figure 11 3 - 4.3V voltage range cycle performance graphs of the examples and comparative examples of the present invention in NCM811||Li batteries;

[0035] Figure 12 3 - 4.6V voltage range cycle performance graphs of the examples and comparative examples of the present invention in NCM811||Li batteries;

[0036] Figure 13 3 - 4.6V voltage range rate performance graphs of the examples and comparative examples of the present invention in NCM811||Li batteries;

[0037] Figure 14 3 - 4.3V voltage range cycle performance graphs of the examples and comparative examples of the present invention in NCM(9 series)||Li batteries;

[0038] Figure 15 3 - 4.6V voltage range rate performance graphs of the examples and comparative examples of the present invention in NCM(9 series)||Li batteries;

[0039] Figure 16 TEM graphs of the positive electrode material CEI after room temperature cycling of the examples and comparative examples of the present invention. Detailed implementation manners

[0040] Next, the relevant technologies in the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0041] Reference Figures 1 to 16 As shown, this specific embodiment is applicable to the high-voltage wide-temperature-range electrolyte of a fast-charging lithium battery, including a solvent and a solute;

[0042] Among them, the organic solvent is a weakly solvating fluorinated solvent, including cyclic fluorinated carbonates, fluoroethylene carbonate (FEC), trans-difluoroethylene carbonate (DFEC), with a total volume accounting for 10% - 20% of the mixed solvent; chain-like fluorinated carbonates, 2,2,2-trifluoroethyl methyl carbonate (FEMC), with a volume accounting for 20% - 40% of the mixed solvent; weakly polar ether-based solvents, at least one of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (HFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), tetrahydrofuran (THF), bis(2,2,2-trifluoroethyl) ether (BTFE), etc., with a volume accounting for 20% - 40% of the mixed solvent. In addition, the main solute lithium salt in the electrolyte is lithium hexafluorophosphate LiPF6. The additives are one or more of lithium salt additives and multivalent cation salt additives. Among them, the lithium salt additives include at least one of lithium difluorooxalate borate LiDFOB, lithium difluorophosphate LiPO2F2, lithium bis(fluorosulfonyl)imide LiFSI, lithium bis(trifluoromethylsulfonyl)imide LiTFSI, lithium tetrafluoroborate LiBF4, lithium nitrate LiNO3, lithium sulfide Li2S, lithium fluoride LiF. The multivalent cation salt additives include magnesium bis(trifluoromethylsulfonyl)imide (Mg(TFSI)2), zinc bis(trifluoromethanesulfonylimide) (Zn(TFSI)2), aluminum trifluoromethanesulfonate Al(OTf)3.

[0043] In the preparation process of the electrode, the corresponding cathode material, conductive agent, and binder are first weighed in an agate mortar according to a mass ratio of 8:1:1, and an appropriate amount of N-methylpyrrolidone solvent (NMP) is added and mixed evenly to form a uniform and viscous slurry; then the slurry is evenly coated on the aluminum foil and dried in an 80°C oven, and finally the required cathode sheet is obtained through cutting and weighing. And the test method adopted in the present invention is the 2025 coin cell test, using the electrolyte described in the present invention to assemble a metal lithium battery with a lithium nickel manganate material or a ternary high-nickel material as the cathode and a lithium metal sheet as the anode.

[0044] Example

[0045] Example 1

[0046] The preparation of a high-voltage wide-temperature-range electrolyte applicable to a fast-charging lithium battery, and its preparation method is as follows:

[0047] Take vinyl difluoride carbonate (DFEC), 2,2,2-trifluoroethyl methyl carbonate (FEMC), and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) organic solvents according to the volume ratio of DFEC:FEMC:TTE = 2:4:4 and add them to a reagent bottle equipped with a magnetic stirrer, and stir for 5 h to mix evenly. Weigh a certain amount of LiPF6 and add it to the solvent to prepare an electrolyte with a concentration of 1 mol / L. Subsequently, weigh a certain amount of lithium difluoro(oxalato)borate LiDFOB to make the molar concentration 0.02 mol / L. Then add a certain amount of magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2) additive with a concentration of Mg(TFSI)2 being 0.02 mol / L. After all the electrolyte solutes are dissolved, a high-voltage and wide-temperature-range electrolyte suitable for fast-charging lithium batteries is obtained.

[0048] Example 2

[0049] The difference between Example 2 and Example 1 lies in the different concentrations of the additives. Among them, the molar concentration of the added lithium difluoro(oxalato)borate LiDFOB is 0.05 mol / L. A high-voltage and wide-temperature-range electrolyte for fast-charging lithium batteries is prepared by stirring and mixing.

[0050] Example 3

[0051] The difference between Example 3 and Example 1 lies in the different concentrations of the additives. Among them, the molar concentration of the added lithium difluoro(oxalato)borate LiDFOB is 0.1 mol / L. A high-voltage and wide-temperature-range electrolyte for fast-charging lithium batteries is prepared by stirring and mixing.

[0052] Example 4

[0053] The difference between Example 4 and Example 1 lies in the different concentrations of the lithium salt. Among them, the molar concentration of the added lithium hexafluorophosphate is 2 mol / L. A high-voltage and wide-temperature-range electrolyte for fast-charging lithium batteries is prepared by stirring and mixing.

[0054] Comparative Example 1

[0055] Prepare a commercial electrolyte in Comparative Example 1. Mix ethylene carbonate EC and dimethyl carbonate DMC solvents evenly according to a certain volume ratio (EC:DMC = 1:1 volume ratio), and then weigh a certain amount of LiPF6 and add it to the solvent, and prepare a commercial electrolyte with a concentration of 1 mol / L by stirring.

[0056] Comparative Example 2

[0057] The difference between Comparative Example 2 and Comparative Example 1 lies in the type of solvent. Trans-difluoroethylene carbonate (DFEC), 2,2,2-trifluoroethyl methyl carbonate (FEMC), and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) organic solvents were taken out according to the volume ratio of DFEC:FEMC:TTE = 2:4:4 and added to a reagent bottle equipped with a magnetic stirrer, and stirred for 5 h to mix evenly. A certain amount of LiPF6 was weighed and added to the solvent to prepare an electrolyte solution with a concentration of 1 mol / L.

[0058] Comparative Example 3

[0059] The difference between Comparative Example 3 and Comparative Example 2 lies in the additive. A certain amount of lithium difluoro(oxalato)borate (LiDFOB) was added on the basis of Comparative Example 2 to prepare an electrolyte solution, and the molar concentration was 0.02 mol / L.

[0060] Comparative Example 4

[0061] The difference between Comparative Example 4 and Comparative Example 3 lies in the type of additive. Magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2) was added on the basis of Comparative Example 2 to prepare a high-voltage and wide-temperature-range electrolyte suitable for fast-charging lithium-ion batteries, and the concentration of Mg(TFSI)2 was 0.02 mol / L.

[0062] Assembly of coin cells: The assembly of the cells was carried out in a glove box filled with argon gas for protection (H2O < 1×10 -6 , O2 < 1×10 -6 ). The electrolyte injection volume was 60 μl. The negative electrode was a lithium metal sheet with a diameter of 14 mm, the separator was a PP separator with a diameter of 16 mm, and the model of the battery case was CR2025.

[0063] The electrolytes obtained above were applied to high-voltage lithium nickel manganese oxide and high-nickel ternary lithium-ion batteries, and electrochemical performance tests were carried out:

[0064] Figure 1 The linear sweep voltammetry (LSV) results shown indicate that the oxidation current increase of the electrolyte in Example 1 after 4.0 V is significantly lower than that of commercial Comparative Example 1. The wide electrochemical window (>5.0 V) constructed by its fluorinated solvent system provides a basis for the stable operation of 5 V-class lithium nickel manganese oxide (LNMO) materials. It is worth noting that in Comparative Example 2, the electrolyte was turbid due to the insufficient solubility of lithium difluoro(oxalato)borate (LiDFOB) in the weakly solvating fluorinated system. In Example 1, by introducing magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2), the dissolution behavior of LiDFOB was significantly improved by the strong coordination effect of polyvalent cations ( Figure 2)。This synergistic effect promotes the formation of a CEI / SEI film rich in S, N, and F elements in the electrolyte. Meanwhile, the flammability test ( Figure 3 ) shows that the electrolyte of the example is non-flammable, and the safety is essentially improved.

[0065] The electrochemical performance test ( Figures 4 - 10 ) further verifies the comprehensive advantages of this electrolyte: in the LNMO||Li half-cell, the composite additive of 0.02 mol / L Mg(TFSI)2 and LiDFOB can significantly improve the first-cycle Coulombic efficiency, up to 99.7%, reduce the voltage polarization and improve the rate performance, and can still provide a discharge specific capacity of 118.6 mAh g -1 at 5C. In terms of cycle stability, the capacity retention rate is 92.8% after 800 cycles at 2C, 89.5% after 170 cycles at 60°C, 88.7% after 120 cycles at 70°C, and 98.4% after 200 cycles at -20°C / 0.2C, showing excellent wide-temperature adaptability. The electrochemical performance test for high-nickel ternary materials shows ( Figures 11 - 15 ) that the NCM811||Li battery has a capacity retention rate of 85.3% after 600 cycles in the voltage range of 1C and 3 - 4.3V, and a capacity retention rate of 87.4% after 200 cycles at 4.6V high voltage, and the 5C discharge specific capacity reaches 189.8 mAh g -1 ; Similarly, the NCM9 series||Li lithium battery has a capacity retention rate of 87.5% and a Coulombic efficiency of 99.9% after 500 cycles at 1C, and the 10C discharge specific capacity can reach 175.5 mAh g -1 . Interface analysis shows that the CEI film formed by the electrolyte of the example is thinner and more uniform, and rich in inorganic components ( Figure 16 ), which can effectively inhibit the dissolution of Mn / Ni ions and side reactions of the electrolyte. Its unique anion-dominated solvation structure not only reduces the desolvation energy barrier of lithium ions but also enhances the interface stability through the synergistic anion effect.

[0066] In summary, the present invention ensures the rapid desolvation of lithium ions in the electrolyte and a wide electrochemical window through a weakly polar fluorinated solvent; promotes the rapid dissolution of salts and the formation of a positive electrolyte membrane with high ionic conductivity through the introduction of additives, enabling fast charging and discharging of lithium batteries at high rates and making great progress in the wide-temperature application of -30°C to 70°C; therefore, the present invention combines soluble lithium salts and their additives, multivalent cation salt additives, weakly solvating fluorinated carbonates, and ether solvents through reasonable ratio combinations and optimizations, enabling the electrolyte to achieve long cycle life and high Coulombic efficiency of lithium batteries in the fields of high voltage, fast charging, and wide temperature.

[0067] It should be emphasized that the above are only the preferred embodiments of the present invention, and there is no limitation to the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. The high-voltage and wide-temperature-range electrolyte for fast-charging lithium batteries, characterized in that, Comprising: an organic solvent, a lithium salt, and an additive; the organic solvent is a weakly solvating fluorinated solvent, and the organic solvent is a mixed solvent of a cyclic fluorinated carbonate, a linear fluorinated carbonate, and a weakly polar ether-based solvent. The volume ratio of the cyclic fluorinated carbonate, the linear fluorinated carbonate, and the weakly polar ether-based solvent in the mixed solvent is: (1-2):(2-4):(2-4); the lithium salt is lithium hexafluorophosphate; the additive includes: a lithium salt additive and / or a multivalent cation salt additive; the lithium salt additive does not include lithium hexafluorophosphate.

2. The high-voltage wide-temperature-range electrolyte for the fast-charging lithium battery according to claim 1, wherein the cyclic fluorinated carbonate includes: fluoroethylene carbonate FEC, trans-difluoroethylene carbonate DFEC; the linear fluorinated carbonate includes: 2,2,2-trifluoroethyl methyl carbonate FEMC; the weakly polar ether-based solvent includes: 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether HFE, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether TTE, tetrahydrofuran THF, bis(2,2,2-trifluoroethyl) ether BTFE.

3. The high-voltage wide-temperature electrolyte for the fast-charging lithium battery according to claim 1, wherein the lithium salt additive includes: lithium difluorooxalate borate, lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium tetrafluoroborate, lithium nitrate, lithium sulfide, lithium fluoride.

4. The high-voltage wide-temperature-range electrolyte for the fast-charging lithium battery according to claim 1, characterized in that, the multivalent cation salt additive includes: magnesium bis(trifluoromethylsulfonyl)imide, zinc bis(trifluoromethanesulfonylimide), aluminum trifluoromethanesulfonate.

5. The high-voltage wide-temperature-range electrolyte for the fast-charging lithium battery according to claim 1, wherein the molar concentration of the lithium salt dissolved in the organic solvent is 1-2 mol / L; the molar concentration of the lithium salt additive dissolved in the organic solvent is 0.01-0.1 mol / L; the molar concentration of the multivalent cation salt additive dissolved in the organic solvent is 0.01-0.1 mol / L.

6. A preparation method of a high-voltage and wide-temperature-range electrolyte for a fast-charging lithium battery, characterized in that, the preparation method is used to prepare the high-voltage wide-temperature-range electrolyte according to any one of claims 1 to 5; the preparation method includes the following steps: Step 1, under anhydrous and anaerobic conditions, place the dried molecular sieve in the cyclic fluorinated carbonate, the linear fluorinated carbonate, and the weakly polar ether-based solvent respectively and let it stand to remove the moisture in each solvent; Step 2, mix the cyclic fluorinated carbonate, the linear fluorinated carbonate, and the weakly polar ether-based solvent according to the volume ratio (1-2):(2-4):(2-4) and stir magnetically until evenly mixed to obtain a mixed solution A; Step 3, add the lithium salt and the additive to the solvent A and stir again to prepare a high-voltage wide-temperature-range electrolyte for a fast-charging lithium battery.

7. The preparation method of the high-voltage wide-temperature-range electrolyte for a fast-charging lithium battery according to claim 6, characterized in that, In the said Step 3, the molar concentration of the lithium salt is 1-2 mol / L, and the molar concentration of the additive is 0.01-0.1 mol / L.

8. A fast-charging high-voltage wide-temperature lithium battery, characterized in that, the lithium battery uses the high-voltage wide-temperature-range electrolyte according to any one of claims 1 to 5, and the lithium battery includes: a positive electrode material, a negative electrode material, and a separator.

9. A fast-charging high-voltage wide-temperature lithium battery according to claim 8, characterized in that, the positive electrode material is a high-energy-density positive electrode material, and the positive electrode material includes: cobalt-free lithium nickel manganate, ternary positive electrode material, and the ternary positive electrode material includes: NCM811, NCM9 series.

10. A fast-charging high-voltage wide-temperature lithium battery according to claim 8, characterized in that, The positive electrode material includes: LiNi 1xy Co x Mn y O2, LiNi 1xy Co x Al y O2, LiMO2, where M = Ni, Co, Mn, 0 ≤ x < 1, 0 ≤ y < 1, 0 ≤ x + y < 1; the negative electrode active material is metallic lithium and lithium titanate.

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