CN115632166A - Flame-retardant electrolyte for lithium metal battery and preparation method and application thereof - Google Patents

Flame-retardant electrolyte for lithium metal battery and preparation method and application thereof Download PDF

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CN115632166A
CN115632166A CN202211100566.2A CN202211100566A CN115632166A CN 115632166 A CN115632166 A CN 115632166A CN 202211100566 A CN202211100566 A CN 202211100566A CN 115632166 A CN115632166 A CN 115632166A
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lithium
lithium metal
metal battery
carbonate
flame
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明军
邹业国
李茜
王立民
尹东明
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Changchun Institute of Applied Chemistry of CAS
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0034—Fluorinated solvents
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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Abstract

The invention provides a flame-retardant electrolyte for a lithium metal battery and a preparation method and application thereof, belonging to the technical field of lithium batteries. The electrolyte consists of lithium salt and an organic solvent, wherein the organic solvent comprises fluorinated cyclic carbonates, fluorinated chain carbonates and phosphazene derivatives. The invention provides a preparation method of a flame-retardant electrolyte for a lithium metal battery. The invention also provides application of the flame-retardant electrolyte for the lithium metal battery in a high-voltage lithium metal battery. The electrolyte in the invention takes fluorinated cyclic carbonate and fluorinated chain carbonate as main solvents, and greatly improves the oxidation resistance of the electrolyte based on the positive effect of introduced fluorine atoms, and is better matched with a high-voltage anode. More importantly, the fluorinated solvent can regulate the desolvation process of lithium ions, improve the deposition of the lithium ions on the surface of the lithium metal and reduce the formation of lithium dendrites.

Description

Flame-retardant electrolyte for lithium metal battery and preparation method and application thereof
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a flame-retardant electrolyte for a lithium metal battery and a preparation method and application thereof.
Background
With electric vehicles, energy storage and portable electronic products dealing with high energy densities (> 350Wh kg) -1 ) The demand for rechargeable batteries is increasing and the development of new battery systems is essential to overcome the disadvantages of commercial lithium ion batteries.
Compared with lithium ion batteries, the lithium metal batteries mainly adopt lithium metal as a negative electrode, and the specific capacity of the lithium metal batteries is as high as 3860mAh g -1 Is the specific capacity (372 mAh g) of the graphite cathode of the current commercial lithium ion battery -1 ) 10 times higher and has a very low redox potential (-3.04v vs. she), so more capacity can be output at the same mass. In addition, the energy density of the battery can be further improved by adopting a high-voltage positive electrode (such as a lithium cobaltate positive electrode, a ternary layered oxide positive electrode, a lithium-rich manganese-based positive electrode and the like) and a lithium metal negative electrode. However, at present, the commercial Ethylene Carbonate (EC) based electrolyte is easy to be applied to a high-voltage positive electrode (> 4.3V vs. Li/Li) + ) The surface is oxidized and decomposed, and side reaction is generated with the metal lithium, so that the electrolyte is greatly consumed in the circulation process, the internal resistance of the battery is increased, the polarization of the battery is intensified, and the coulombic efficiency and the circulation stability of the lithium metal negative electrode are reduced. Meanwhile, under the influence of solvation, lithium ions are easy to generate uneven deposition on the surface of the lithium metal negative electrode in the process of desolvation, so that dead lithium or lithium dendrites are caused. The growth of lithium dendrite and the accumulation of dead lithium can pierce through a diaphragm to cause a battery short circuit, so that a large amount of heat is generated instantaneously, organic electrolyte is easy to ignite to cause thermal runaway of the battery and even explosion, great potential safety hazards exist, and the development of the lithium metal battery is seriously hindered. The development of the flame-retardant electrolyte which is compatible with the high-voltage anode and matched with the lithium metal is expected to fundamentally solve the problem, and has practical application significance.
Disclosure of Invention
The invention aims to solve the problem that the conventional electrolyte is easy to cause combustion and explosion when applied to a lithium metal battery, and provides a flame-retardant nonaqueous electrolyte for the lithium metal battery and a preparation method thereof.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a flame-retardant electrolyte for a lithium metal battery is composed of lithium salt and an organic solvent, wherein the organic solvent comprises fluorinated cyclic carbonates, fluorinated chain carbonates and phosphazene derivatives.
Preferably, the molar ratio of the lithium salt, the fluorinated cyclic carbonate, the fluorinated chain carbonate and the phosphazene derivative is 1 (2-6) to (0.1-0.7).
Preferably, the lithium salt is lithium tetrafluoroborate (LiBF) 4 ) Lithium perchlorate (LiClO) 4 ) Lithium hexafluorophosphate (LiPF) 6 ) Lithium bistrifluoromethanesulfonimide (LiTFSI), lithium bistrifluorosulfonimide (LiFSI), and lithium difluorooxalato borate (lidob).
Preferably, the fluorocyclic carbonate is at least one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC) and derivatives thereof.
Preferably, the first and second liquid crystal display panels are, the fluorinated chain carbonates are fluoroethyl carbonate (FEMC), 2-trifluoroethyl carbonate (MTFEC), 2-trifluoroethyl carbonate (ETFEC) at least one of bis (2, 2-trifluoroethyl) carbonate (DTFEC) and ethyl-propyl-2, 2-trifluorocarbonate (PTFEC) and derivatives thereof.
Preferably, the phosphazene derivative is at least one of methoxy pentafluorocyclotriphosphazene, ethoxy pentafluorocyclotriphosphazene (PFPN), trifluoroethoxy pentafluorocyclotriphosphazene, pentafluorophenoxy cyclotriphosphazene (POPFPN), pentafluoropropoxy pentafluorocyclotriphosphazene (HFPN), and a derivative thereof.
Preferably, the organic solvent comprises fluoroethylene carbonate (FEC), diethyl 2, 2-trifluorocarbonate (etec) and ethoxypentafluorocyclotriphosphazene (PFPN).
The invention provides a preparation method of a flame-retardant electrolyte for a lithium metal battery, which comprises the following steps:
under the protection of high-purity argon gas, uniformly mixing fluorinated cyclic carbonate, fluorinated chain carbonate and phosphazene derivative, adding lithium salt, fully oscillating, and magnetically stirring at room temperature to completely dissolve the lithium salt, thereby obtaining the flame-retardant electrolyte.
The invention also provides application of the flame-retardant electrolyte in a lithium metal battery.
Preferably, the lithium metal battery is a high voltage lithium metal battery composed of a lithium-based negative electrode and a separator (Celgard 2325);
the high voltage positive electrode of the high voltage lithium metal battery includes: lithium nickel manganese oxide (LiNi) 0.5 Mn 1.5 O 4 ) Lithium cobaltate (LiCoO) 2 ) Nickel cobalt manganese ternary positive electrode (LiNi) x Co y Mn z O 2 X + y + z = 1) and a lithium-rich manganese-based positive electrode (LiMnO · LiMO);
the negative electrode includes: at least one of a lithium metal wafer, a lithium tape, a lithium foil, porous lithium, a lithium alloy, or a lithium copper composite negative electrode.
The invention has the advantages of
The invention provides a flame-retardant electrolyte for a lithium metal battery and a preparation method and application thereof. Compared with the prior art, the electrolyte in the invention takes fluorinated cyclic carbonate and fluorinated chain carbonate as main solvents, and greatly improves the oxidation resistance of the electrolyte based on the positive effect of introduced fluorine atoms, and is better matched with a high-voltage anode. More importantly, the fluorinated solvent can regulate the desolvation process of lithium ions, improve the deposition of the lithium ions on the surface of the lithium metal and reduce the formation of lithium dendrites. Meanwhile, the electrolyte can easily form a stable passive film on the surface of the lithium metal, and the compatibility of the electrolyte and a lithium metal negative electrode is improved. In addition, the flame retardance of the electrolyte is further improved by adding a small amount of phosphazene derivative, and the comprehensive performance of the lithium metal battery can be improved, so that the obtained lithium metal battery has high energy density, high safety and high cycle stability.
Drawings
FIG. 1 is a self-extinguishing test of comparative example 1 and example 1;
FIG. 2 is a graph showing the cycle performance of a Li/NCM811 lithium metal battery assembled from comparative example 1 and example 1;
FIG. 3 is the coulombic efficiency during cycling of a Li/Cu cell assembled from comparative example 1 and example 1;
fig. 4 is a graph of lithium metal morphology deposited in comparative example 1 and example 1.
Detailed Description
A flame-retardant electrolyte for a lithium metal battery is composed of lithium salt and an organic solvent, wherein the organic solvent comprises fluorinated cyclic carbonates, fluorinated chain carbonates and phosphazene derivatives.
According to the present invention, the molar ratio of the lithium salt, fluorinated cyclic carbonates, fluorinated chain carbonates, and phosphazene derivative is preferably 1: (2-6): (0.1-0.7), more preferably 1: (3-5) from (0.2-0.6), most preferably from 1: (3.2-4), (3.8-4.5) and (0.4-0.5). In the solvent proportioning process, the dosage of the phosphazene derivative is strictly controlled, the performance of the battery is determined by the dosage of the phosphazene derivative, and when the content of the phosphazene derivative is too high, the conductivity of the electrolyte is reduced, so that the cycling stability of the battery is reduced; when the content of the phosphazene derivative is too low, it is difficult to suppress decomposition of the electrolyte, and degradation of the battery performance is also caused.
According to the invention, the lithium salt is preferably lithium tetrafluoroborate (LiBF) 4 ) Lithium perchlorate (LiClO) 4 ) Lithium hexafluorophosphate (LiPF) 6 ) Lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium bistrifluoromethanesulfonylimide (LiFSI), and lithium difluorooxalatoborate (lidob), more preferably lithium hexafluorophosphate (LiPF) 6 )。
According to the present invention, the fluorocyclic carbonate is preferably at least one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC) and derivatives thereof.
In accordance with the present invention, there is provided, the fluorinated chain carbonates are preferably methyl ethyl fluoro carbonate (FEMC), bis (2, 2-trifluoroethyl) carbonate (TFEC), ethylene bis fluoro carbonate (DFEC), ethylene fluoro carbonate (FEC) at least one of trifluoroethyl ethylene carbonate (TFPC), ethyl methyl 2, 2-trifluorocarbonate (MTFEC), diethyl 2, 2-trifluorocarbonate (ETFEC), and ethyl propyl 2, 2-trifluorocarbonate (PTFEC).
According to the present invention, the phosphazene derivative is preferably at least one of methoxy pentafluorocyclotriphosphazene, ethoxy pentafluorocyclotriphosphazene (PFPN), trifluoroethoxy pentafluorocyclotriphosphazene, pentafluorophenoxy cyclotriphosphazene (poppfpn), pentafluoropropoxy pentafluorocyclotriphosphazene (HFPN), and a derivative thereof.
According to the invention, the organic solvent is preferably fluoroethylene carbonate (FEC), diethyl 2, 2-trifluorocarbonate (ETFEC) and ethoxypentafluorocyclotriphosphazene (PFPN).
According to the invention, the electrolyte takes fluorinated cyclic carbonate and fluorinated chain carbonate as main solvents, and the oxidation resistance of the electrolyte is greatly improved based on the positive effect of introduced fluorine atoms, so that the electrolyte is better matched with a high-voltage positive electrode. More importantly, the fluorinated solvent can regulate the desolvation process of lithium ions, improve the deposition of the lithium ions on the surface of the lithium metal and reduce the formation of lithium dendrites. Meanwhile, the electrolyte easily forms a stable passive film on the surface of the metal lithium, and the compatibility of the electrolyte and the metal lithium cathode is improved. In addition, the flame retardance of the electrolyte is further improved by adding a small amount of phosphazene derivative, and the comprehensive performance of the lithium metal battery can be improved.
The invention also provides a preparation method of the flame-retardant electrolyte for the lithium metal battery, which comprises the following steps: under the environment of high-purity argon protection, uniformly mixing fluorinated cyclic carbonate, fluorinated chain carbonate and phosphazene derivative, adding lithium salt, fully oscillating, and magnetically stirring at room temperature, wherein the stirring time is preferably 12 hours, so that the lithium salt is completely dissolved, and the flame-retardant electrolyte can be obtained.
The invention also provides application of the flame-retardant electrolyte in a lithium metal battery.
According to the invention, the lithium metal battery is a high-voltage lithium metal battery consisting of a lithium-based negative electrode and a diaphragm (Celgard 2325);
the high voltage positive electrode of the high voltage lithium metal battery includes: lithium nickel manganese oxide (LiNi) 0.5 Mn 1.5 O 4 ) Lithium cobaltate (LiCoO) 2 ) Nickel cobalt manganese ternary positive electrode (LiNi) x Co y Mn z O 2 X + y + z = 1) and a lithium-rich manganese-based positive electrode (LiMnO · LiMO), and is more preferably LiNi 0.8 Co 0.1 Mn 0.1 (NCM811)。
According to the present invention, the lithium-based negative electrode of the above-described high-voltage lithium metal battery includes: at least one of a lithium metal disk, a lithium tape, a lithium foil, porous lithium, a lithium alloy, or a lithium copper composite negative electrode, and more preferably a lithium metal disk.
The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.
Example 1
Under the protection of high-purity argon, uniformly mixing FEC, ETFEC and PFPN solvents, and adding a certain amount of lithium salt LiPF 6 And fully shaking, and magnetically stirring at room temperature for 12 hours to completely dissolve the lithium salt, thereby obtaining the flame-retardant electrolyte. Wherein, liPF 6 The molar ratio of FEC, ETFEC and PFPN is 1.
Battery assembly and performance testing: with LiNi 0.8 Co 0.1 Mn 0.1 Is a positive electrode material; the lithium metal wafer was used as a negative electrode, and 40 μ 1 of the flame-retardant electrolyte for a lithium metal battery prepared in example 1 was added to the wafer to form a high-voltage lithium metal battery. The battery is further activated by charging and discharging 2 times and 3 times at 0.1C and 0.2C respectively at room temperature of 25 deg.C and constant temperature of 2.8V to 4.4V, and then charging and discharging at 0.3C/0.5C for a long period of time. The capacity retention rate of the battery after 200 cycles was calculated, wherein the N-th capacity retention rate (%) of the battery cycle was not = N-th-week discharge capacity/first-week discharge capacity × 100%.
And (3) testing the stability of the electrolyte: copper foil (Cu) is used as a positive electrode, a lithium metal wafer is used as a negative electrode, and 40 mu of the flame-retardant electrolyte for the lithium metal battery prepared in the example 1 is added1, forming a Li/Cu battery, and testing the cyclic coulombic efficiency of the Li/Cu battery. At room temperature 25 deg.C, at 0.5mA cm -2 The current is discharged for 10 times in the voltage range of 0-1.0V to complete the activation, and then 0.5mA cm -2 Discharging for 2h with current, and discharging again at 0.5mA cm -2 And continuously performing 150 cycles when the current is charged to 1.0V, and finally obtaining the change rule of the coulomb efficiency.
Example 2
Under the protection of high-purity argon, uniformly mixing FEC, ETFEC and PFPN solvents, and adding a certain amount of lithium salt LiPF 6 And (3) fully shaking, and magnetically stirring at room temperature for 12 hours to completely dissolve the lithium salt, thus obtaining the flame-retardant electrolyte. Wherein, liPF 6 And the molar ratio of FEC, ETFEC and PFPN is 1.
The flame-retardant electrolyte for a lithium metal battery prepared in example 2 was used to assemble a lithium metal battery and to perform a performance test in the same manner as in example 1.
Example 3
Under the protection of high-purity argon, uniformly mixing FEC, ETFEC and PFPN solvents, and adding a certain amount of lithium salt LiPF 6 And (3) fully shaking, and magnetically stirring at room temperature for 12 hours to completely dissolve the lithium salt, thus obtaining the flame-retardant electrolyte. Wherein, liPF 6 The molar ratio of FEC, ETFEC and PFPN is 1.
The flame-retardant electrolyte for a lithium metal battery prepared in example 3 was used to assemble a lithium metal battery and to perform a performance test in the same manner as in example 1.
Example 4
Under the protection of high-purity argon, uniformly mixing FEC, ETFEC and PFPN solvents, and adding a certain amount of lithium salt LiPF 6 And fully shaking, and magnetically stirring at room temperature for 12 hours to completely dissolve the lithium salt, thereby obtaining the flame-retardant electrolyte. Wherein, liPF 6 The molar ratio of FEC, ETFEC and PFPN is 1.
The flame-retardant electrolyte for a lithium metal battery prepared in example 4 was used to assemble a lithium metal battery and to perform a performance test in the same manner as in example 1.
Comparative example 1
In the high-purity argon gas protection ringUnder the condition, uniformly mixing Ethylene Carbonate (EC) and diethyl carbonate (DEC) solvents, and adding a certain amount of lithium salt LiPF 6 And fully shaking, and magnetically stirring at room temperature for 12 hours to completely dissolve the lithium salt, thereby obtaining the commercial ethylene carbonate-based electrolyte. Wherein, liPF 6 EC and DEC in a 1.
The commercial carbonate-based electrolyte prepared in comparative example 1 was used to assemble a lithium metal battery and to perform a performance test in accordance with the method of example 1.
Comparative example 2
Under the environment of high-purity argon protection, FEC and ETFEC solvents are mixed evenly, and a certain amount of lithium salt LiPF is added 6 And fully shaking, and magnetically stirring at room temperature for 12 hours to completely dissolve the lithium salt, thereby obtaining the nonaqueous electrolyte. Wherein, liPF 6 The molar ratio of FEC to ETFEC is 1.
The nonaqueous electrolytic solution prepared in comparative example 2 was used to assemble a lithium metal battery and to perform a performance test in the same manner as in example 1.
Comparative example 3
Under the protection of high-purity argon, uniformly mixing FEC, ETFEC and PFPN solvents, and adding a certain amount of lithium salt LiPF 6 And fully shaking, and magnetically stirring at room temperature for 12 hours to completely dissolve the lithium salt, thereby obtaining the nonaqueous electrolyte. Wherein, liPF 6 And the molar ratio of FEC, ETFEC and PFPN is 1.
The nonaqueous electrolytic solution prepared in comparative example 3 was used to assemble a lithium metal battery and to perform a performance test in the same manner as in example 1.
Comparative example 4
Under the protection of high-purity argon, uniformly mixing FEC, ETFEC and PFPN solvents, and adding a certain amount of lithium salt LiPF 6 And fully shaking, and magnetically stirring at room temperature for 12 hours to completely dissolve the lithium salt, thereby obtaining the nonaqueous electrolyte. Wherein, liPF 6 The molar ratio of FEC, ETFEC and PFPN is 1.5.
The nonaqueous electrolytic solution prepared in comparative example 4 was used to assemble a lithium metal battery and to perform a performance test in the same manner as in example 1.
The above examples 1 to 4 and comparative examples 1 to 4 were subjected to flame retardancy test: the above 100ul of electrolyte was ignited by a flame gun, the flame was left after 3 seconds, the self-extinguishing time was measured by a stopwatch, and the average value was measured by 3 repetitions, the results of which are shown in table 1 below:
TABLE 1
Figure BDA0003840179670000071
FIG. 1 is a self-extinguishing test of comparative example 1 and example 1, as can be seen from FIG. 1 and Table 1: the fluoro carbonate solvent does not burn the electrolyte with or without the phosphazene flame retardant compared to conventional solvents (EC and DEC).
The batteries of examples 1-4 and comparative examples 1-4 were subjected to long cycle performance tests in a voltage range of 2.8V to 4.4V, as shown in table 2:
TABLE 2
Figure BDA0003840179670000081
FIG. 2 is a graph showing the cycle performance of a Li/NCM811 lithium metal battery assembled from comparative example 1 and example 1; FIG. 3 is the coulombic efficiency during cycling of a Li/Cu cell assembled from comparative example 1 and example 1; fig. 4 is a graph of lithium metal morphology deposited in comparative example 1 and example 1. As can be seen from the cycle performance shown in table 2 and fig. 2, the electrolyte prepared in the example of the present invention can be better matched with the high voltage positive electrode than the comparative example. In addition, it can be seen from fig. 4 that the metallic lithium deposited in the example electrolyte is more uniform than the comparative example, no significant lithium dendrites are generated, further demonstrating the high compatibility of the example electrolyte with metallic lithium. The phenomenon also proves that the electrolyte disclosed by the invention not only can enable the high-voltage lithium metal battery to output ultrahigh energy, but also has higher cycling stability, and better meets the requirements of the market on the high-energy density and high-safety battery.
In summary, the preferred embodiments of the present invention are described above, but the scope of the present invention is not limited thereto, and any modifications, equivalents, improvements, etc. made by those skilled in the art within the technical scope of the present invention as disclosed herein, and the technical solution and the inventive concept thereof should be covered by the scope of the present invention.

Claims (10)

1. The flame-retardant electrolyte for the lithium metal battery consists of lithium salt and an organic solvent, and is characterized in that the organic solvent comprises fluorinated cyclic carbonates, fluorinated chain carbonates and phosphazene derivatives.
2. The flame retardant electrolyte for lithium metal batteries according to claim 1, wherein the molar ratio of the lithium salt to the fluorinated cyclic carbonates to the fluorinated chain carbonates to the phosphazene derivatives is 1 (2-6) to (0.1-0.7).
3. The flame-retardant electrolyte for a lithium metal battery according to claim 1, wherein the lithium salt is at least one of lithium tetrafluoroborate, lithium perchlorate, lithium hexafluorophosphate, lithium bistrifluoromethanesulfonylimide, and lithium difluorooxalatoborate.
4. The flame-retardant electrolyte for a lithium metal battery according to claim 1, wherein the fluorinated cyclic carbonate is at least one of fluoroethylene carbonate, difluoroethylene carbonate, trifluoromethyl ethylene carbonate and derivatives thereof.
5. The flame retardant electrolyte for a lithium metal battery according to claim 1, wherein the fluorinated chain carbonate is at least one of fluoroethyl carbonate, 2-trifluoroethyl carbonate, bis (2, 2-trifluoroethyl) carbonate, and 2, 2-trifluoroethyl carbonate and derivatives thereof.
6. The flame retardant electrolyte for a lithium metal battery according to claim 1, wherein the phosphazene derivative is at least one of methoxy pentafluorocyclotriphosphazene, ethoxy pentafluorocyclotriphosphazene, trifluoroethoxy pentafluorocyclotriphosphazene, pentafluorophenoxy cyclotriphosphazene, pentafluoropropoxy pentafluorocyclotriphosphazene and a derivative thereof.
7. The flame retardant electrolyte for a lithium metal battery according to claim 1, wherein the organic solvent comprises fluoroethylene carbonate, diethyl 2, 2-trifluorocarbonate and ethoxypentafluorocyclotriphosphazene.
8. The method for preparing a flame-retardant electrolyte for a lithium metal battery according to claim 1, comprising the steps of:
under the protection of high-purity argon gas, uniformly mixing fluorinated cyclic carbonate, fluorinated chain carbonate and phosphazene derivative, adding lithium salt, fully oscillating, and magnetically stirring at room temperature to completely dissolve the lithium salt, thereby obtaining the flame-retardant electrolyte.
9. Use of the flame retardant electrolyte of claim 1 in a lithium metal battery.
10. The use of the flame retardant electrolyte in a lithium metal battery according to claim 9, wherein the lithium metal battery is a high voltage lithium metal battery comprising a lithium-based negative electrode and a separator;
the high voltage positive electrode of the high voltage lithium metal battery includes: at least one of a lithium nickel manganese oxide, a lithium cobalt oxide, a nickel cobalt manganese ternary positive electrode and a lithium-rich manganese-based positive electrode;
the negative electrode includes: at least one of a lithium metal disk, a lithium tape, a lithium foil, porous lithium, a lithium alloy, or a lithium copper composite negative electrode.
CN202211100566.2A 2022-09-09 2022-09-09 Flame-retardant electrolyte for lithium metal battery and preparation method and application thereof Pending CN115632166A (en)

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