Application of fluorinated ether solvent and electrolyte in energy storage battery

Abstract

The application provides a fluorinated ether solvent and an electrolyte applied to energy storage batteries, especially lithium metal batteries, and the fluorinated ether solvent has a structure shown in formula I. By introducing at least one fluorine atom at both ends of an ether molecular chain, the fluorinated ether molecule has excellent salt solubility, the introduction of the fluorine atom can effectively reduce the electron cloud density of ether oxygen to improve the oxidation stability of the ether molecule, and excellent cycle stability of the high-voltage lithium metal battery is achieved; meanwhile, the locally strong polar fluorinated end group can interact with the cation of the salt to improve the ionic conductivity of the electrolyte, and the rapid charge-discharge performance of the high-voltage lithium metal battery is improved.

Description

Technical Field

[0001] This invention belongs to the field of energy storage battery technology, and particularly relates to a fluorinated ether solvent and electrolyte used in energy storage lithium metal batteries. Background Technology

[0002] Currently, lithium-ion batteries are highly competitive among various energy storage batteries. However, lithium-ion batteries using graphite anodes cannot meet the demands of various high-performance electric devices due to their limited energy density. In recent years, the use of lithium-ion batteries with high specific capacity (3860 mAh g⁻¹) has become increasingly important. -1 Lithium-metal batteries, using lithium metal as the negative electrode with a low potential (-3.04V compared to the standard hydrogen electrode), are considered one of the most promising next-generation energy storage batteries. However, the highly reactive lithium metal negative electrode reacts with virtually all available electrolytes, leading to low coulombic efficiency, poor cycle performance, and lithium dendrite growth. Furthermore, lithium-metal batteries require high-voltage and high-capacity positive electrode materials, such as nickel-rich NMC811, to maximize the overall energy density of the battery. However, with increasing the cutoff charging voltage of NMC811, side reactions between the positive electrode and the electrolyte become severe, inducing faster capacity decay. Therefore, the interfacial instability between the positive and negative electrodes and the electrolyte is crucial for the development and commercialization of high-energy-density lithium-metal batteries.

[0003] To alleviate the aforementioned problems, developing ether-based electrolytes, especially high-concentration or locally high-concentration electrolytes, is considered one of the effective ways to achieve cycle stability in high-voltage NMC811 lithium metal batteries. However, even in high-concentration or locally high-concentration electrolytes, some free ether molecules still exist, and the decomposition of unstable ether molecules may significantly affect the electrochemical performance of high-voltage lithium metal batteries. Furthermore, the low intrinsic ionic conductivity of high-concentration or locally high-concentration electrolytes also affects the fast charge-discharge performance of lithium metal batteries. Therefore, existing ether-based electrolytes still cannot be practically applied in lithium metal batteries.

[0004] The same problem exists in high-voltage lithium-ion batteries, sodium metal (or ion) batteries, potassium metal (or ion) batteries, magnesium metal batteries, and zinc metal battery energy storage systems based on organic electrolytes. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a fluorinated ether solvent and electrolyte for use in energy storage batteries, especially lithium metal batteries. The fluorinated ether solvent provided by the present invention has high salt solubility and oxidation stability, which significantly improves the oxidation resistance and fast charge and discharge capability of ether-based electrolytes, and further enhances the application of ether electrolytes in practical lithium metal batteries.

[0006] This invention provides a fluorinated ether solvent having the structure shown in Formula I:

[0007]

[0008] In Equation I, the values ​​of n1, n2, and n3 are independent and range from 1 to 3, and X = H or F.

[0009] Preferably, the fluoroether solvent is selected from bis(2-fluoroethoxy)ethane.

[0010] The present invention also provides a method for preparing the above-mentioned fluorinated ether solvents, comprising the following steps:

[0011] Chlorinated ethers, metal fluorides, and alcohols are mixed and reacted to obtain the reaction product;

[0012] The reaction products were filtered, extracted, and distilled under reduced pressure to obtain fluoroether solvents.

[0013] Preferably, the chloroether is one of bis(chloromethoxy)methane, bis(2-chloroethoxy)methane, bis(chloromethoxy)ethane, bis(2-chloroethoxy)ethane, bis(chloromethoxy)propane, bis(2-chloroethoxy)propane, 1-chloro-2-(methoxymethoxy)ethane, (methoxymethoxy)chloromethane, 2-methoxyethoxymethylchloro, 1-(2-chloroethoxy)-2-methoxyethane, and 1-(2-chloroethoxy)-2-ethoxyethane;

[0014] The metal fluoride is one or more of lithium fluoride, sodium fluoride, potassium fluoride, and cesium fluoride;

[0015] The alcohol is one or more of ethylene glycol, polyethylene glycol, diethylene glycol, and tetraethylene glycol.

[0016] Preferably, the reaction temperature is 80–200°C and the reaction time is 2–16 hours;

[0017] The molar ratio of the chloro ether to the metal fluoride is 1:1 to 1:10;

[0018] The molar volume ratio of the metal fluoride to the alcohol is 0.1 mol: 10-100 mL.

[0019] The present invention also provides an electrolyte containing a fluorinated ether solvent, comprising a fluorinated ether solvent having the structure shown in Formula I.

[0020]

[0021] In Equation I, the values ​​of n1, n2, and n3 are independent and range from 1 to 3, and X = H or F.

[0022] Preferably, the electrolyte further includes an electrolyte salt and a diluent.

[0023] Preferably, the electrolyte salt is one or more of lithium salt, sodium salt, potassium salt, magnesium salt, and zinc salt; the lithium salt is selected from Li2SO4, LiClO4, LiNO3, LiF, LiCF3SO3, LiPF6, Li(FSO2)2N, LiBF4, Li(CF3CF2SO2)2N, or Li(CF3SO2)2N; the sodium salt is selected from NaClO4, NaNO3, NaF, Na(FSO2)2N, Na(CF3CF2SO2)2N, NaPF6, Na2SO4, or NaCF3SO3; the potassium salt is selected from KNO3, KClO4, KPF6, K(FSO2)2N, K(CF3SO2)2N, K2SO4, KF, or KCl; the magnesium salt is selected from Mg(CF3SO3)2, MgCl2, or MgSO4; and the zinc salt is selected from Zn(CF3SO3)2, ZnSO4, or Zn(CH3OO)2.

[0024] The diluent is selected from one or more of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, tri(2,2,2-trifluoroethyl) orthoformate, 1H,1H,5H-octafluoropentyl acrylate-1,1,2,2-tetrafluoroethyl ether, fluorobenzene, and 1,3,5-trifluorobenzene.

[0025] Preferably, the molar ratio of electrolyte salt to fluoroether solvent is 1:0.1 to 1:10, and the molar ratio of fluoroether solvent to diluent is 1:0 to 1:10.

[0026] The present invention also provides an energy storage battery comprising a fluorinated ether solvent having the structure shown in Formula I.

[0027]

[0028] In Equation I, the values ​​of n1, n2, and n3 are independent and range from 1 to 3, and X = H or F;

[0029] The energy storage battery is selected from lithium metal batteries, high-voltage lithium-ion batteries based on organic electrolytes, sodium metal (or ion) batteries, potassium metal (or ion) batteries, magnesium metal batteries, and zinc metal battery energy storage systems.

[0030] Compared with existing technologies, this invention provides a fluorinated ether solvent and electrolyte for use in energy storage batteries, especially lithium metal batteries. The fluorinated ether solvent has the structure shown in Formula I. This invention ensures that the fluorinated ether molecule has excellent salt-dissolving ability by introducing at least one fluorine atom at each end of the ether molecular chain. Furthermore, the introduction of fluorine atoms effectively reduces the electron cloud density of the ether oxygen, thereby improving the oxidative stability of the ether molecule and achieving excellent cycle stability in high-voltage lithium metal batteries. Simultaneously, the locally highly polar fluorinated end groups can interact with the cations of the salt to improve the ionic conductivity of the electrolyte, thus enhancing the fast charge-discharge performance of high-voltage lithium metal batteries. Attached Figure Description

[0031] Figure 1 It is the product synthesized in Example 2. 1 H, 13 C 19 NMR characterization spectrum of F;

[0032] Figure 2 This is a comparison graph of linear scan voltammetry tests of the traditional ether-based local high-concentration electrolyte in Example 1 and the fluorinated ether-based local high-concentration electrolyte in Example 2.

[0033] Figure 3 This is a comparison chart of the cycle stability and coulombic efficiency of polycrystalline NMC811 batteries using the traditional ether-based local high-concentration electrolyte in Example 1 and the fluorinated ether-based local high-concentration electrolyte in Example 2 at 4.6V and C / 3.

[0034] Figure 4 This is a comparison chart of the cycle stability and coulombic efficiency of a monocrystalline NMC811 battery using a traditional ether-based localized high-concentration electrolyte in Example 1 and a fluorinated ether-based localized high-concentration electrolyte in Example 2 at 4.7V and C / 3.

[0035] Figure 5 This is the first charge-discharge curve of the polycrystalline NMC811 battery at 4.6V and C / 3 using the conventional ether-based localized high-concentration electrolyte in Example 1.

[0036] Figure 6 This is a comparison chart of the ionic conductivity of the traditional ether-based local high-concentration electrolyte in Example 1 and the fluorinated ether-based local high-concentration electrolyte in Example 2 at different temperature ranges;

[0037] Figure 7 This is a comparison chart of the charge-discharge curves of polycrystalline NMC811 batteries at 4.5V and 1C using the traditional ether-based localized high-concentration electrolyte in Example 1 and the fluorinated ether-based localized high-concentration electrolyte in Example 2.

[0038] Figure 8This is a comparison chart of the cycle stability and coulombic efficiency of polycrystalline NMC811 batteries using the traditional ether-based local high-concentration electrolyte in Example 1 and the fluorinated ether-based local high-concentration electrolyte in Example 2 at 4.6V and 1C.

[0039] Figure 9 This is a graph showing the cycle stability and coulombic efficiency of the polycrystalline NMC811 battery using the locally high concentration of fluorinated ether electrolyte in Example 2 at 4.6V and 2C.

[0040] Figure 10 This is a comparison chart of the rate performance of polycrystalline NMC811 batteries at 4.6V using fluorinated ether-based locally high-concentration electrolytes in Example 2.

[0041] Figure 11 This is a comparison graph of linear scan voltammetry tests of the traditional ether-based dilute concentration electrolyte in Example 10 and the fluorinated ether-based dilute concentration electrolyte in Example 11. Detailed Implementation

[0042] This invention provides a fluorinated ether solvent having the structure shown in Formula I:

[0043]

[0044] In Equation I, the values ​​of n1, n2, and n3 are independent and range from 1 to 3, and X = H or F.

[0045] In some specific embodiments of the present invention, the fluorinated ether solvent is selected from bis(2-fluoroethoxy)ethane.

[0046] The present invention also provides a method for preparing the fluoroether solvent, comprising the following steps:

[0047] Chlorinated ethers, metal fluorides, and alcohols are mixed and reacted to obtain the reaction product;

[0048] The reaction products were filtered, extracted, and distilled under reduced pressure to obtain fluoroether solvents.

[0049] The chloroether is one of bis(chloromethoxy)methane, bis(2-chloroethoxy)methane, bis(chloromethoxy)ethane, bis(2-chloroethoxy)ethane, bis(chloromethoxy)propane, bis(2-chloroethoxy)propane, 1-chloro-2-(methoxymethoxy)ethane, (methoxymethoxy)chloromethane, 2-methoxyethoxymethylchloro, 1-(2-chloroethoxy)-2-methoxyethane, and 1-(2-chloroethoxy)-2-ethoxyethane, preferably bis(2-chloroethoxy)ethane.

[0050] The metal fluoride is one or more of lithium fluoride, sodium fluoride, potassium fluoride, and cesium fluoride, preferably potassium fluoride.

[0051] The alcohol is one or more of ethylene glycol, polyethylene glycol, diethylene glycol, and tetraethylene triethylene glycol, preferably tetraethylene triethylene glycol.

[0052] The molar ratio of the chloroether to the metal fluoride is 1:1 to 1:10, preferably 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, or any value between 1:1 and 1:10;

[0053] The molar volume ratio of the metal fluoride to the alcohol is 0.1 mol: 10 to 100 mL, preferably 0.1 mol: 10 mL, 0.1 mol: 25 mL, 0.1 mol: 50 mL, 0.1 mol: 75 mL, 0.1 mol: 100 mL, or any value between 0.1 mol: 10 and 100 mL.

[0054] A mixture of chloroether, metal fluoride, and alcohol is reacted to obtain the reaction product. The reaction temperature is 80–200°C, preferably 80, 100, 120, 140, 160, 180, or 200°C, or any value between 80 and 200°C, and the reaction time is 2–16 hours, preferably 2, 4, 6, 8, 10, 12, 14, or 16 hours, or any value between 2 and 16 hours.

[0055] After the reaction is complete, the reaction product is obtained. Then, the reaction product is filtered to remove unreacted metal fluorides, and the filtered product is obtained.

[0056] The filtered material is then washed, preferably by extraction with anhydrous diethyl ether. The extraction is preferably performed three times. The ether is then removed by rotary evaporation under reduced pressure to obtain the crude product.

[0057] Finally, the crude product is distilled under reduced pressure to obtain fluoroether solvents. The temperature at which the product is collected by reduced pressure distillation is 30℃~80℃, preferably 30, 40, 50, 60, 70, 80℃, or any value between 30℃ and 80℃.

[0058] The present invention also provides an electrolyte containing a fluorinated ether solvent, comprising a fluorinated ether solvent having the structure shown in Formula I.

[0059]

[0060] In Equation I, the values ​​of n1, n2, and n3 are independent and range from 1 to 3, and X = H or F.

[0061] The specific description of the fluorinated ether solvents is as described above and will not be repeated here.

[0062] In this invention, the fluorinated ether-based locally high-concentration electrolyte also includes electrolyte salts and diluents.

[0063] The electrolyte salt is one or more of lithium salt, sodium salt, potassium salt, magnesium salt, and zinc salt; the lithium salt is selected from Li2SO4, LiClO4, LiNO3, LiF, LiCF3SO3, LiPF6, Li(FSO2)2N, LiBF4, Li(CF3CF2SO2)2N, or Li(CF3SO2)2N; the sodium salt is selected from NaClO4, NaNO3, NaF, Na(FSO2)2N, Na(CF3CF2SO2)2N, NaPF6, Na2SO4, or NaCF3SO3; the potassium salt is selected from KNO3, KClO4, KPF6, K(FSO2)2N, K(CF3SO2)2N, K2SO4, KF, or KCl; the magnesium salt is selected from Mg(CF3SO3)2, MgCl2, or MgSO4; and the zinc salt is selected from Zn(CF3SO3)2, ZnSO4, or Zn(CH3OO)2.

[0064] The diluent is selected from one or more of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, tri(2,2,2-trifluoroethyl) orthoformate, 1H,1H,5H-octafluoropentyl acrylate-1,1,2,2-tetrafluoroethyl ether, fluorobenzene, and 1,3,5-trifluorobenzene.

[0065] The molar ratio of the electrolyte salt to the fluoroether solvent is 1:0.1 to 1:10, preferably 1:0.1, 1:0.3, 1:0.5, 1:0.8, 1:1, 1:3, 1:5, 1:8, 1:10, or any value between 1:0.1 and 1:10.

[0066] The molar ratio of the fluoroether solvent to the diluent is 1:0 to 1:10, preferably 1:0, 1:0.1, 1:0.3, 1:0.5, 1:0.8, 1:1, 1:3, 1:5, 1:8, 1:10, or any value between 1:0 and 1:10.

[0067] The present invention also provides an energy storage battery comprising a fluorinated ether solvent having the structure shown in Formula I.

[0068]

[0069] In Equation I, the values ​​of n1, n2, and n3 are independent and range from 1 to 3, and X = H or F;

[0070] The energy storage battery is selected from lithium metal batteries, high-voltage lithium-ion batteries based on organic electrolytes, sodium metal (or ion) batteries, potassium metal (or ion) batteries, magnesium metal batteries, and zinc metal battery energy storage systems.

[0071] This invention ensures the excellent salt-dissolving ability of fluorinated ether molecules by introducing at least one fluorine atom at each end of the ether molecular chain. Furthermore, the introduction of fluorine atoms can effectively reduce the electron cloud density of the ether oxygen to improve the oxidation stability of the ether molecule, thus achieving excellent cycle stability of high-voltage lithium metal batteries. At the same time, the locally highly polar fluorinated end groups can interact with the cations of the salt to improve the ionic conductivity of the electrolyte, thereby enhancing the fast charge and discharge performance of high-voltage lithium metal batteries.

[0072] This invention discloses a fluorinated ether solvent and electrolyte that, when applied to energy storage batteries, particularly lithium metal batteries, significantly improves the oxidative stability and ionic conductivity of the electrolyte, resulting in superior high-voltage cycle performance and rapid charge-discharge capability for lithium metal batteries. This invention has the potential for large-scale production and holds significant application prospects in practical lithium metal batteries.

[0073] To further understand the present invention, the application of the fluorinated ether solvents and electrolytes provided by the present invention in energy storage batteries is described below with reference to the embodiments. The scope of protection of the present invention is not limited to the following embodiments.

[0074] Example 1:

[0075] This embodiment provides a conventional ether-based locally high-concentration electrolyte, with the following composition: the electrolyte solute is lithium difluorosulfonylimide, the solvent is a conventional ether solvent (ethylene glycol diethyl ether), and the diluent is 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether. Lithium difluorosulfonylimide, solvent, and diluent are weighed and prepared to form a conventional ether-based locally high-concentration electrolyte. The ratio of salt to ethylene glycol diethyl ether to diluent in the locally high-concentration electrolyte is 1:1:3 (molar ratio of salt to ethylene glycol diethyl ether to diluent). A linear sweep voltammetry test is then performed.

[0076] Example 2:

[0077] A method for preparing a fluoroether solvent is as follows:

[0078] 0.08 mol of bis(2-chloroethoxy)ethane, 0.32 mol of potassium fluoride, and 80 mL of tetraethylene glycol were mixed and reacted in an oil bath at 180 °C for 8.5 h. The resulting mixture was filtered to remove unreacted potassium fluoride, extracted three times with diethyl ether, and the diethyl ether was removed by rotary evaporation under reduced pressure to obtain a crude product. The crude product was then distilled under reduced pressure, and the liquid collected at 50 °C was used to obtain the final product, bis(2-fluoroethoxy)ethane.

[0079] The product obtained by synthesis 1H, 13 C 19 The NMR characterization results of F are as follows: Figure 1 As shown in the figure, the spectrum demonstrates the successful synthesis of bis(2-fluoroethoxy)ethane.

[0080] This embodiment provides a fluorinated ether-based locally high-concentration electrolyte, the composition of which is as follows: the electrolyte solute is lithium bis(2-fluoroethoxy)imide, the solvent is the aforementioned fluorinated ether solvent, and the diluent is 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether. Lithium bis(2-fluoroethoxy)imide, solvent, and diluent are weighed and prepared to form a fluorinated ether-based locally high-concentration electrolyte. The ratio of salt:bis(2-fluoroethoxy)ethane:diluent in the locally high-concentration electrolyte is 1:1.65:3 (salt:bis(2-fluoroethoxy)ethane:diluent, molar ratio), and a linear sweep voltammetry test is performed.

[0081] Test results are as follows Figure 2 As shown, the electrolyte in Example 2 has higher oxidation stability compared to the electrolyte in Example 1.

[0082] Example 3:

[0083] The fluorinated ether-based locally high-concentration electrolyte from Example 2 was selected as the experimental group for this example, while the traditional ether-based locally high-concentration electrolyte from Example 1 was used as the control group. Polycrystalline NCM811 (LiNi) was used. 0.8 Co 0.1 Mn 0.1 O2 was used as the positive electrode and Li metal (450 micrometers) was used as the negative electrode. Charge-discharge cycle tests were conducted at 4.6V and C / 3 rate.

[0084] Test results are as follows Figure 3 As shown, the fluorinated ether-based locally high-concentration electrolyte in Example 2 exhibits excellent cycling stability at 4.6V.

[0085] Test results are as follows Figure 4 As shown, the traditional ether-based local high-concentration electrolyte in Example 1 exhibits significant overcharging, which is caused by the unstable decomposition of the traditional ether solvent.

[0086] Example 4:

[0087] The fluorinated ether-based locally high-concentration electrolyte from Example 2 was selected as the experimental group for this example, while the traditional ether-based locally high-concentration electrolyte from Example 1 was used as the control group. Single-crystal NCM811 (LiNi) was used as the experimental group. 0.8 Co 0.1 Mn 0.1 O2 was used as the positive electrode and Li metal (450 micrometers) was used as the negative electrode. Charge-discharge cycle tests were conducted at 4.7V and C / 3 rate.

[0088] Test results are as follows Figure 5 As shown, the fluorinated ether-based localized high-concentration electrolyte in Example 2 can still maintain good cycle performance at 4.7V, while the traditional ether-based localized high-concentration electrolyte in Example 1 cannot work properly, and the battery capacity is significantly reduced.

[0089] Example 5:

[0090] The fluorinated ether-based locally high-concentration electrolyte from Example 2 was selected as the experimental group in this example, while the traditional ether-based locally high-concentration electrolyte from Example 1 was used as the control group. The ionic conductivity of the electrolyte was tested at different temperatures.

[0091] Test results are as follows Figure 6 As shown, the fluorinated ether-based locally high-concentration electrolyte in Example 2 exhibits higher ionic conductivity over a wide temperature range of -30℃ to 30℃, especially at room temperature.

[0092] Example 6:

[0093] The fluorinated ether-based locally high-concentration electrolyte from Example 2 was selected as the experimental group for this example, while the traditional ether-based locally high-concentration electrolyte from Example 1 was used as the control group. Polycrystalline NCM811 (LiNi) was used. 0.8 Co 0.1 Mn 0.1 O2) was used as the positive electrode and Li metal (450 micrometers) was used as the negative electrode. Charge-discharge cycle tests were conducted at 4.5V and 1C rate to obtain charge-discharge curves.

[0094] Test results are as follows Figure 7 As shown, the conventional ether-based locally high-concentration electrolyte in Example 1, like the fluorinated ether-based locally high-concentration electrolyte in Example 2, did not undergo oxidative decomposition during the first charge at 4.5V. However, during cycling, the conventional ether-based locally high-concentration electrolyte in Example 1 exhibited a larger charge-discharge plateau voltage difference, which was due to greater polarization during charge-discharge cycling.

[0095] Example 7:

[0096] The fluorinated ether-based locally high-concentration electrolyte from Example 2 was selected as the experimental group for this example, while the traditional ether-based locally high-concentration electrolyte from Example 1 was used as the control group. Polycrystalline NCM811 (LiNi) was used. 0.8 Co 0.1 Mn 0.1 O2 was used as the positive electrode and Li metal (450 micrometers) was used as the negative electrode. Charge-discharge cycle tests were conducted at 4.6V and 1C rate.

[0097] Test results are as follows Figure 8As shown, the fluorinated ether local high-concentration electrolyte in Example 2 exhibits excellent cycling performance under rapid charge-discharge and high voltage conditions, while the conventional ether local high-concentration electrolyte in Example 1 cannot undergo long-term cycling.

[0098] Example 8:

[0099] The fluorinated ether-based locally high-concentration electrolyte from Example 2 was selected as the research object for this example. Polycrystalline NCM811 (LiNi) was used as the electrolyte. 0.8 Co 0.1 Mn 0.1 O2 was used as the positive electrode and Li metal (450 micrometers) was used as the negative electrode. Charge-discharge cycle tests were conducted at 4.6V and 2C rate.

[0100] The test results are shown in Figure 9. The fluorinated ether-based local high-concentration electrolyte in Example 2 has excellent high voltage and high-rate charge-discharge cycle stability.

[0101] Example 9:

[0102] The fluorinated ether-based locally high-concentration electrolyte from Example 2 was selected as the experimental group for this example, while the traditional ether-based locally high-concentration electrolyte from Example 1 was used as the control group. Polycrystalline NCM811 (LiNi) was used. 0.8 Co 0.1 Mn 0.1 O2 was used as the positive electrode, and Li metal (450 micrometers) was used as the negative electrode. The charge and discharge rate was tested at 4.6V.

[0103] As shown in Test Result 10, the fluorinated ether local high-concentration electrolyte in Example 2 can release a higher capacity than the traditional ether local high-concentration electrolyte in Example 1 at different expansion rates.

[0104] Example 10:

[0105] This embodiment provides a conventional ether-based local high-concentration electrolyte, the composition of which is as follows: the electrolyte solvent is a conventional ether solvent (ethylene glycol diethyl ether), and the solute is lithium difluorosulfonylimide; lithium difluorosulfonylimide is weighed and dissolved in the solvent to prepare a conventional ether-based dilute concentration electrolyte, wherein the concentration of the electrolyte is 1 mole of lithium difluorosulfonylimide per liter of ethylene glycol diethyl ether, and a linear sweep voltammetry test is performed.

[0106] Example 11:

[0107] This embodiment provides a dilute concentration electrolyte based on fluorinated ethers, the composition of which is as follows: the electrolyte solvent is the fluorinated ether solvent in Example 2, and the solute is lithium difluorosulfonylimide; lithium difluorosulfonylimide is weighed, dissolved in the solvent, and prepared into a dilute concentration electrolyte based on fluorinated ethers, wherein the concentration of the electrolyte is 1 mole of lithium difluorosulfonylimide per liter of fluorinated ether solvent, and a linear sweep voltammetry test is performed.

[0108] Test results are as follows Figure 11 As shown, the electrolyte in Example 11 has higher oxidation stability compared to the electrolyte in Example 10.

[0109] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fluorinated ether-based locally high-concentration electrolyte, characterized in that, The composition consists of: electrolyte salts, fluorinated ether solvents, and diluents; The fluoroether solvent is selected from bis(2-fluoroethoxy)ethane; The diluent is selected from one or more of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, and 1H,1H,5H-octafluoropentyl acrylate-1,1,2,2-tetrafluoroethyl ether.

2. The fluorinated ether-based locally high-concentration electrolyte according to claim 1, wherein the preparation method of the fluorinated ether solvent comprises the following steps: Chlorinated ethers, metal fluorides, and alcohols are mixed and reacted to obtain the reaction product; The reaction products were filtered, extracted, and distilled under reduced pressure to obtain fluoroether solvents.

3. The electrolyte according to claim 2, characterized in that, The chloroether is bis(2-chloroethoxy)ethane; The metal fluoride is one or more of lithium fluoride, sodium fluoride, potassium fluoride, and cesium fluoride; The alcohol is one or more of ethylene glycol, polyethylene glycol, diethylene glycol, and tetraethylene glycol.

4. The electrolyte according to claim 2, characterized in that, The reaction is carried out at a temperature of 80~200℃ for 2~16 hours. The molar ratio of the chloro ether to the metal fluoride is 1:1 to 1:10; The molar volume ratio of the metal fluoride to the alcohol is 0.1 mol: 10~100 mL.

5. The electrolyte according to claim 1, characterized in that, The electrolyte salt is one or more of lithium salt, sodium salt, potassium salt, magnesium salt, and zinc salt; the lithium salt is selected from Li2SO4, LiClO4, LiNO3, LiF, LiCF3SO3, LiPF6, Li(FSO2)2N, LiBF4, Li(CF3CF2SO2)2N, or Li(CF3SO2)2N; the sodium salt is selected from NaClO4, NaNO3, NaF, Na(FSO2)2N, Na(CF3CF2SO2)2N, NaPF6, Na2SO4, or NaCF3SO3; the potassium salt is selected from KNO3, KClO4, KPF6, K(FSO2)2N, K(CF3SO2)2N, K2SO4, KF, or KCl; the magnesium salt is selected from Mg(CF3SO3)2, MgCl2, or MgSO4; and the zinc salt is selected from Zn(CF3SO3)2, ZnSO4, or Zn(CH3OO)2.

6. The electrolyte according to claim 1, characterized in that, The molar ratio of electrolyte salt to fluorinated ether solvent is 1:0.1 to 1:10, and the molar ratio of fluorinated ether solvent to diluent is 1:0.1 to 1:

10.

7. A lithium metal battery, characterized in that, Includes the fluorinated ether-based locally high-concentration electrolyte as described in claim 1.

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