Difluoromethylated silane solvent electrolyte and its application in secondary batteries

Abstract

The application discloses a difluoromethylated silane solvent electrolyte and application thereof in a secondary battery, and relates to the technical field of battery preparation. The electrolyte of the difluoromethylated silane solvent forms a boundary phase of inorganic substances such as fluoride and silicon oxide on the surfaces of positive and negative electrodes, can not only inhibit the formation of negative electrode alkali metal dendrites and increase the stripping efficiency of alkali metal deposition, but also inhibit the degradation of the positive electrode structure, adapt to high-voltage positive electrode materials, and further improve the cycle stability of the secondary battery.

Description

Technical Field

[0001] This invention relates to the field of electrolyte technology, and in particular to a difluoromethylsilane solvent electrolyte and its application in secondary batteries. Background Technology

[0002] To address the urgent need for energy storage systems driven by global energy transition and carbon neutrality goals, developing rechargeable batteries with high energy density and high safety is crucial. Current commercially available rechargeable batteries are limited by their theoretical energy density, making it difficult to meet the higher energy density and cycle life requirements of future electric vehicles and large-scale energy storage. Against this backdrop, rechargeable batteries, such as alkali metal batteries, are showing great promise, with energy densities doubled compared to their alkali metal-ion counterparts, and are considered a key development direction for next-generation high-energy-density energy storage devices.

[0003] However, the commercialization of high-energy-density rechargeable batteries still faces a series of technical challenges. Taking alkali metal anodes as an example, their high reactivity leads to continuous interfacial side reactions with traditional organic electrolytes, forming an unstable, heterogeneous solid electrolyte interfacial film. This interface is prone to dynamic rupture and reconstruction during battery cycling, continuously consuming active metals and electrolytes, resulting in decreased coulombic efficiency, accelerated capacity decay, and shortened cycle life. Simultaneously, the growth of alkali metal dendrites may puncture the separator, causing internal short circuits and posing serious safety hazards. These interfacial problems have become common key technical bottlenecks restricting the development of high-energy-density rechargeable batteries.

[0004] In novel electrolyte designs, optimizing component ratios and solvation structures can effectively balance the relationship between ionic conductivity and interfacial stability. A well-designed electrolyte formulation promotes the formation of a stable interfacial phase, constructing a protective layer with excellent mechanical strength and high ionic conductivity. This effectively inhibits the growth of alkali metal dendrites and improves the uniformity and reversibility of alkali metal deposition and stripping. Coulombic efficiency is a key indicator of the reversibility of alkali metal secondary battery systems. Low efficiency means significant irreversible loss of active material per cycle, requiring the inclusion of excess alkali metal in the battery design for compensation. This not only increases costs but also significantly weakens the battery's energy density advantage. Currently, in various secondary battery systems, coulombic efficiency still falls short of commercial application requirements. Therefore, innovative electrolyte system design to construct a stable electrode-electrolyte interfacial phase, achieving high coulombic efficiency and cycle stability, is a core element in driving the development of next-generation high-energy-density secondary batteries.

[0005] In conclusion, developing novel electrolyte systems that can induce the formation of stable interfacial phases is of great strategic significance for addressing the key technical challenges currently faced by secondary batteries in terms of energy density, cycle life, and safety, and for promoting their industrialization. Summary of the Invention

[0006] To address the aforementioned issues, this application proposes an electrolyte suitable for secondary batteries, which is a mixture of difluoromethyl silane solvent and electrolyte salt, or a co-solvent.

[0007] Specifically, this application is implemented through the following scheme: A difluoromethylsilane solvent electrolyte comprises an electrolyte salt, a co-solvent, and a difluoromethylsilane solvent; The molar ratio of electrolyte salt to co-solvent is 1:1 to 1:10; The difluoromethyl silane solvent has a relative mass percentage of 5% to 75% of the electrolyte.

[0008] Preferably, the difluoromethylsilane solvent is: ; R1, R2, and R3 are selected from at least one of hydrogen, alkyl, haloalkyl, phenyl, and halophenyl.

[0009] Preferably, the electrolyte salt is at least one of the following metal salt molecules; The structural formula of the metal salt molecule includes: , , , , , and ; M is one of lithium, sodium, or potassium.

[0010] Preferably, the co-solvent is at least one of the following molecules containing characteristic functional groups; Structural formulas of molecules containing characteristic functional groups include: , , , , , , , , and ; Among them, R1-R 23 It is independently selected from at least one of hydrogen, halogen, alkyl, haloalkyl, phenyl, halophenyl, ether, carbonyl, carboxyl, ester, nitro, and amino.

[0011] A difluoromethylsilane solvent electrolyte is used in the preparation of secondary batteries.

[0012] In summary, the difluoromethyl silane solvent electrolyte of the present invention and its application in secondary batteries have the following advantages compared with conventional technologies: 1. When difluoromethylsilane is oxidized and decomposed, it can generate an interfacial phase rich in inorganic substances such as fluorides and silicon oxides, thereby inhibiting the degradation of the cathode material and improving the high voltage stability of the cathode material; 2. Low-fluorinated methyl groups can exhibit weak coordination with alkali metal ions, thereby increasing the diffusion rate of alkali metal ions. The interfacial phase formed by the decomposition of the electrolyte, which is rich in inorganic substances such as fluorides and silicon oxides, can reduce the severe side reactions between the alkali metal negative electrode and the electrolyte, thereby improving the deposition and stripping efficiency of alkali metal ions.

[0013] The technical method of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0014] Figure 1 The lithium deposition stripping coulombic efficiency of Li / / Cu coin cell 1 varies with the number of cycles. Figure 2 The lithium deposition stripping coulombic efficiency of Li / / Cu coin cell 2 is shown as a function of cycle number; Figure 3 The lithium deposition stripping coulombic efficiency of Li / / Cu coin cell 3 varies with the number of cycles; Figure 4 The it curve and electrochemical impedance spectroscopy of Li / / Li coin cell 1 are shown. Figure 5 The it curve and electrochemical impedance spectroscopy of Li / / Li coin cell 2 are shown. Figure 6 The it curve and electrochemical impedance spectroscopy of Li / / Li coin cell 3 are shown. Figure 7 The Li / / LiNi electrolytes of Examples 1, 1, and 2 are shown. 0.8 Co 0.1 Mn 0.1 The specific capacity of an O2 full cell varies with the number of cycle cycles; Figure 8 The Li / / LiNi electrolyte of Example 1 is shown. 0.8 Co 0.1 Mn 0.1 Charge and discharge curves of O2 full battery; Figure 9 The specific capacity of the Li / / LiCoO2 full cell with the electrolyte of Example 1 as a function of cycle number and its charge-discharge curve are shown. Figure 9 (a) in the figure is a graph showing the specific capacity as a function of the number of cycles. Figure 9 (b) in the graph is the charge-discharge curve; Figure 10 The specific capacity of the Li / / LiMn2O4 full cell with the electrolyte of Example 1 as a function of cycle number and its charge-discharge curve are shown. Figure 10 (a) in the figure is a graph showing the specific capacity as a function of the number of cycles. Figure 10 (b) in the graph is the charge-discharge curve; Figure 11 The specific capacity of the Li / / LiFePO4 full cell with the electrolyte of Example 1 as a function of cycle number and its charge-discharge curve are shown. Figure 11 (a) in the figure is a graph showing the specific capacity as a function of the number of cycles. Figure 11 (b) in the graph is the charge-discharge curve; Figure 12 The specific capacity of the Li / / Graphite half-cell with the electrolyte of Example 1 as a function of cycle number and its charge-discharge curve are shown. Figure 12 (a) in the figure is a graph showing the specific capacity as a function of the number of cycles. Figure 12 (b) in the graph is the charge-discharge curve; Figure 13 The Li / / LiNi electrolyte of Example 1 is shown. 0.8 Co 0.1 Mn 0.1 X-ray photoelectron spectroscopy signal on the surface of the lithium anode after 5 cycles of the O2 full cell. Figure 13 (a) in the figure is the F1s X-ray photoelectron spectrum signal of the negative electrode surface. Figure 13 (b) in the figure is the N1s X-ray photoelectron spectrum signal of the negative electrode surface. Figure 13 (c) in the figure is the O1s X-ray photoelectron spectrum signal of the negative electrode surface. Figure 13 (d) in the figure is the Si2p X-ray photoelectron spectrum signal of the negative electrode surface; Figure 14 The Li / / LiNi electrolyte of Example 1 is shown. 0.8 Co 0.1 Mn 0.1 X-ray photoelectron spectroscopy signal on the positive electrode surface after 5 cycles of the O2 full cell. Figure 14 (a) in the image is the F1s X-ray photoelectron spectrum of the positive electrode surface. Figure 14 (b) in the diagram is the N1s X-ray photoelectron spectrum of the positive electrode surface. Figure 14 (c) in the diagram is the O1s X-ray photoelectron spectrum of the positive electrode surface. Figure 14 (d) in the figure is the Si2p X-ray photoelectron spectrum signal of the positive electrode surface. Detailed Implementation

[0015] The technical method of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0016] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0017] Techniques, systems, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the instruction manual.

[0018] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0019] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0020] This application takes an electrolyte containing difluoromethylsilane solvent as an example and compares it with advanced electrolytes containing fluorinated ether and trifluoromethylsilane solvents to illustrate its superior electrochemical properties and application prospects in lithium metal secondary batteries.

[0021] Example 1 LiFSI-DME-DFS electrolyte.

[0022] The method for preparing an electrolyte containing difluoromethylsilane solvent in this embodiment is as follows: In an argon-atmospheric glove box, lithium bis(fluorosulfonyl)imide (LiFSI), dimethyl ethylene glycol (DME), and difluoromethyltrimethylsilane (DFS) were weighed in a molar ratio of 1:1.2:3 and stirred at room temperature until a clear and transparent electrolyte was formed.

[0023] Comparative Example 1 LiFSI-DME-TFS electrolyte.

[0024] The method for preparing an electrolyte containing trifluoromethylsilane solvent in this embodiment is as follows: In an argon-atmospheric glove box, lithium bis(fluorosulfonyl)imide (LiFSI), dimethyl ethylene glycol (DME), and trifluoromethyltrimethylsilane (TFS) were weighed in a molar ratio of 1:1.5:3 and stirred at room temperature until a clear and transparent electrolyte was formed.

[0025] Comparative Example 2 LiFSI-DME-TTE electrolyte.

[0026] The method for preparing an electrolyte containing a fluorinated ether solvent in this embodiment is as follows: In an argon-atmospheric glove box, lithium bis(fluorosulfonyl)imide (LiFSI), dimethyl ethylene glycol (DME), and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) were weighed in a molar ratio of 1:1.2:3 and stirred at room temperature until a clear and transparent electrolyte was formed.

[0027] Performance testing: Assemble Li / / Cu coin cells and test lithium deposition stripping efficiency.

[0028] The Li / / Cu coin cell assembly method used is as follows: lithium is used as the negative electrode, copper foil is used as the positive electrode, polyethylene separator, stainless steel gasket and spring are used, and 70 μL of the electrolyte of Example 1, Comparative Example 1 and Comparative Example 2 are injected respectively to assemble Li / / Cu coin cell 1, Li / / Cu coin cell 2 and Li / / Cu coin cell 3.

[0029] The test conditions for the Li / / Cu coin cells were as follows: the coin cells were subjected to constant current charge-discharge tests on the Newway battery testing system, with a charge-discharge current density of 1 mA cm⁻¹. -2 The lithium deposition capacity is 1 mAh cm⁻¹ -2 The test voltage range is -1 to 1V.

[0030] The lithium deposition stripping coulombic efficiency is calculated by dividing the measured stripped lithium capacity by the deposited lithium capacity.

[0031] The average lithium deposition stripping coulombic efficiency is calculated as follows: the total stripped lithium capacity obtained from the test is divided by the total deposited lithium capacity.

[0032] Figure 1 The lithium deposition stripping coulombic efficiency of Li / / Cu coin cell 1 is shown as a function of cycle number.

[0033] Figure 2 The lithium deposition stripping coulombic efficiency of Li / / Cu coin cell 2 is shown as a function of cycle number.

[0034] Figure 3 The lithium deposition stripping coulombic efficiency of Li / / Cu coin cell 3 is shown as a function of cycle number.

[0035] Table 1 summarizes the average lithium deposition stripping coulombic efficiency of the electrolytes in the above embodiments and comparative examples in Li / / Cu coin cells. Among them, coin cell 1 has an average lithium deposition stripping coulombic efficiency of up to 99.11%, exhibiting the highest reversibility. The electrolyte of the present invention containing difluoromethylsilane solvent has better lithium anode stability than the electrolytes containing trifluoromethylsilane and fluorinated ether solvents.

[0036] Table 1. Average lithium deposition stripping coulombic efficiency of the electrolyte in Li / / Cu coin cells

[0037] Assemble Li / / Li coin cells and test lithium-ion transference number.

[0038] The Li / / Li coin cell assembly method used is as follows: lithium is used as the negative electrode and positive electrode, polyethylene separator, stainless steel gasket and spring, and 70 μL of electrolyte of Example 1, Comparative Example 1 and Comparative Example 2 are injected respectively to assemble Li / / Li coin cell 1, Li / / Li coin cell 2 and Li / / Li coin cell 3.

[0039] The test conditions for the Li / / Li coin cells were as follows: The assembled coin cells were left to stand for 12 hours. The positive and negative terminals were short-circuited with wires until the open-circuit voltage reached 0V. The electrochemical impedance spectroscopy (EIS) of the cells was measured using a Biologic electrochemical workstation. The intrinsic solution impedance value R0 of the electrolyte was obtained by fitting using the equivalent circuit method. The cells were kept at a constant potential of 10mV ΔV, and the current-time (it) curve was obtained. The initial current I0 and steady-state current It of the curve were also analyzed. s Where I0 is the current value at t=0, I s This represents the current value after the battery's it curve has stabilized. After stopping the it curve test, short-circuit the positive and negative terminals of the battery with a wire until the open-circuit voltage balances to 0V. Then, measure the battery's electrochemical impedance spectroscopy to obtain the battery impedance R at this point. s .

[0040] Lithium-ion transference number (t) Li + The calculation method for ) is as follows: .

[0041] Figure 4 The it curve and electrochemical impedance spectroscopy of Li / / Li coin cell 1 are shown.

[0042] Figure 5 The it curve and electrochemical impedance spectroscopy of Li / / Li coin cell 2 are shown.

[0043] Figure 6 The it curve and electrochemical impedance spectroscopy of the Li / / Li coin cell 3 are shown.

[0044] Table 2 summarizes the lithium-ion transference numbers of the electrolytes in the above-described embodiments and comparative examples in Li / / Li coin cells.

[0045] The electrolyte in Example 1 has a lithium-ion transference number of 0.42, which is higher than that of the comparative electrolyte. The electrolyte of the present invention containing difluoromethylsilane solvent has lower concentration polarization during charge and discharge processes compared with the electrolyte containing trifluoromethylsilane and fluorinated ether solvent, thus reducing the internal resistance of the battery.

[0046] Table 2 Lithium-ion transference numbers in the electrolyte of Li / / Li coin cells

[0047] Assemble Pt / / Pt symmetrical electrodes to test lithium-ion conductivity.

[0048] The Pt / / Pt symmetric cell assembly method used is as follows: a custom mold is used to fix the two Pt electrodes at both ends, keeping them at a certain distance L, with the effective contact area of ​​the Pt electrodes being A. Then, the electrolytes of Example 1, Comparative Example 1, and Comparative Example 2 are injected respectively until the Pt electrodes are completely submerged. After sealing, Pt / / Pt symmetric cell 1, Pt / / Pt symmetric cell 2, and Pt / / Pt symmetric cell 3 are obtained.

[0049] The testing method for the Pt / / Pt symmetric cell was as follows: the assembled cell was placed in a 25°C constant temperature oven and left to stand for 1 hour. The AC impedance spectrum of the cell was measured using an electrochemical workstation to obtain the intrinsic impedance R of the electrolyte. b .

[0050] The formula for calculating lithium-ion conductivity is: .

[0051] Table 3 summarizes the lithium-ion conductivity of the electrolytes in the examples and comparative examples.

[0052] The electrolyte in Example 1 exhibited a high 3.67 mS / cm-1. -1 The lithium-ion conductivity of this electrolyte is higher than that of the comparative electrolyte. The electrolyte of this invention containing difluoromethylsilane solvent is beneficial to improving the charge-discharge rate of the battery.

[0053] Table 3 Lithium-ion conductivity of the electrolyte

[0054] Assemble coin cells and test the cycle stability of electrode materials.

[0055] The electrode sheet was prepared as follows: electrode material powder, conductive carbon black, and polytetrafluoroethylene binder were weighed and ground in a mass ratio of 96:2:2, N-methylpyrrolidone was added, and the mixture was stirred to obtain a slurry. The slurry was then uniformly coated onto aluminum foil and dried in a 100°C forced-air oven for 12 hours. Finally, it was stamped into a circular positive electrode sheet. Based on the above method, nickel-cobalt-manganese ternary oxide (LiNi) was used. 0.8 Co 0.1 Mn 0.1 The positive electrode sheet was obtained by combining O2, lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), and lithium iron phosphate (LiFePO4), with a loading of approximately 5.4 mAh cm⁻¹. -2 The corresponding graphite electrode sheet was obtained using graphite electrode material powder, with a loading capacity of approximately 2 mAh cm⁻¹. -2 .

[0056] The Li full cell used was assembled as follows: 20 μm lithium was used as the negative electrode, the above-obtained positive electrode sheet was used as the positive electrode, and 70 μL of electrolyte from Example 1, Comparative Example 1 or Comparative Example 2 was injected into the polyethylene separator, stainless steel gasket and spring sheet respectively to form a coin cell.

[0057] The Li half-cell used was assembled as follows: 300 μm lithium was used as the negative electrode, the graphite electrode sheet obtained above was used as the positive electrode, and 70 μL of the electrolyte of Example 1 was injected into the polyethylene separator, stainless steel gasket and spring sheet to form a coin cell.

[0058] The test conditions for the batteries used were as follows: the assembled coin cells were left to stand for 8 hours, then cycled 3 times at a 0.1C charge-discharge rate, followed by cycles at a 0.2C charge-discharge rate and a 0.3C discharge-discharge rate. Among them, LiNi... 0.8 Co 0.1 Mn 0.1 The 1C of an O2 full cell is 220 mA g. -1 The test voltage range is 2.8-4.5V.

[0059] The 1C of the LiCoO2 full cell is 180 mA g. -1 The test voltage range is 2.8-4.5V.

[0060] The 1C of the LiMn2O4 full cell is 140 mA g. -1 The test voltage range is 3-4.3V.

[0061] The 1C of the LiFePO4 full cell is 150 mA g. -1 The test voltage range is 2.8-4.2V.

[0062] The Graphite half-cell has a 1C value of 370 mA g. -1 The test voltage range is 0.01-2.5V.

[0063] Figure 7 The Li / / LiNi electrolytes of Example 1, Comparative Example 1, and Comparative Example 2 are shown. 0.8 Co 0.1 Mn 0.1 The specific capacity of the O2 full cell varies with the number of cycles, with the electrolyte of Example 1 exhibiting the best capacity retention rate, which is higher than that of the comparative electrolyte.

[0064] Figure 8 The electrolyte in Example 1 shows Li / / LiNi 0.8 Co 0.1 Mn 0.1 The charge-discharge curves of the O2 full battery at different cycle numbers show that the electrolyte containing difluoromethyl silane solvent proposed in this invention has an optimizing effect on both the positive and negative electrode interfaces, significantly improving the cycle stability of high energy density lithium batteries.

[0065] Figure 9 The specific capacity of the Li / / LiCoO2 full cell with the electrolyte of Example 1 as a function of the number of cycles is shown, as well as the charge-discharge curves at different numbers of cycles.

[0066] Figure 10 The specific capacity of the Li / / LiMn2O4 full cell with the electrolyte of Example 1 as a function of the number of cycles is shown, as well as the charge-discharge curves at different numbers of cycles.

[0067] Figure 11 The specific capacity of the Li / / LiFePO4 full cell with the electrolyte of Example 1 as a function of the number of cycles is shown, as well as the charge-discharge curves at different numbers of cycles.

[0068] Figure 12 The specific capacity of the Li / / Graphite half-cell with the electrolyte of Example 1 as a function of cycle number and its charge-discharge curves at different cycle numbers are shown.

[0069] It can be seen that the above electrode materials all have good capacity retention after 20 cycles in the electrolyte of Example 1, indicating that the electrolyte containing difluoromethyl silane solvent proposed in this invention has broad compatibility with different electrode materials.

[0070] X-ray photoelectron spectroscopy was used to characterize the surface composition of the positive and negative electrode sheets after cycling.

[0071] Preparation method of positive and negative electrodes: Using the electrolyte of Example 1, Li / / LiNi was obtained by full-cell assembly method.0.8 Co 0.1 Mn 0.1 O2 button cells were left to stand for 8 hours and then cycled 3 times at a charge-discharge rate of 0.1C. The cells were then disassembled using a button cell disassembly tool to obtain the positive and negative electrodes after cycling. The electrodes were then washed three times in DME solvent and finally vacuum dried at room temperature for 5 minutes to obtain the electrode to be tested.

[0072] The testing method for the positive and negative electrodes was as follows: the electrodes to be tested were placed in the vacuum transfer stage of the Thermo Fisher X-ray photoelectron spectrometer, and the F1s, N1s, O1s, and Si2p X-ray photoelectron spectrometers were measured on the surfaces of the lithium anode and NCM cathode after different etching times under the conditions of 120W power, 25kV electron beam accelerating voltage, and 1keV single ion mode.

[0073] Figure 13 The Li / / LiNi electrolyte of Example 1 is shown. 0.8 Co 0.1 Mn 0.1 X-ray photoelectron spectroscopy (XPS) signals of F1s, N1s, O1s, and Si2p on the surface of the lithium anode after 5 cycles of the O2 full cell.

[0074] Figure 14 The Li / / LiNi electrolyte of Example 1 is shown. 0.8 Co 0.1 Mn 0.1 X-ray photoelectron spectroscopy (XPS) signals of F1s, N1s, O1s, and Si2p on the positive electrode surface after 5 cycles of the O2 full cell.

[0075] The above results indicate that the electrolyte of Example 1 forms a matrix rich in Li-F, Li-O, and N-SO on both the positive and negative electrode surfaces. x Li-N, Si-O x The inorganic interphase can suppress the continuous side reactions between the negative electrode lithium and the electrolyte and the growth of lithium dendrites, and can suppress the degradation of the positive electrode layered structure under high voltage, indicating that the electrolyte containing difluoromethyl silane solvent has a synergistic enhancing effect on the stability of the positive and negative electrode materials.

[0076] The electrolyte containing difluoromethylsilane solvent has the characteristics of high ionic conductivity, high ion mobility, high alkali metal deposition and stripping efficiency, and high voltage stability, and its application prospects in secondary batteries are broad.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical methods of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical methods of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical methods to deviate from the spirit and scope of the technical methods of the present invention.

Claims

1. A difluoromethylsilane solvent electrolyte, characterized in that, Including electrolyte salts, co-solvents, and difluoromethylsilane solvents; The molar ratio of electrolyte salt to co-solvent is 1:1 to 1:10; The difluoromethyl silane solvent has a relative mass percentage of 5% to 75% of the electrolyte.

2. The difluoromethylsilane solvent electrolyte according to claim 1, characterized in that, The difluoromethylsilane solvent is: 。 3. The difluoromethylsilane solvent electrolyte according to claim 2, characterized in that, R1, R2, and R3 are each selected from at least one of hydrogen, alkyl, haloalkyl, phenyl, and halophenyl.

4. The difluoromethylsilane solvent electrolyte according to claim 1, characterized in that, The electrolyte salt is at least one of the following metal salt molecules; The structural formula of the metal salt molecule includes: , , , , , and .

5. The difluoromethylsilane solvent electrolyte according to claim 4, characterized in that, M is one of lithium, sodium, or potassium.

6. The difluoromethylsilane solvent electrolyte according to claim 1, characterized in that, The cosolvent is at least one of the following molecules containing characteristic functional groups; Structural formulas of molecules containing characteristic functional groups include: , , , , , , , , and .

7. The difluoromethylsilane solvent electrolyte according to claim 6, characterized in that, R1-R 23 It is independently selected from at least one of hydrogen, halogen, alkyl, haloalkyl, phenyl, halophenyl, ether, carbonyl, carboxyl, ester, nitro, and amino.

8. A difluoromethylsilane solvent electrolyte as described in any one of claims 1-7, characterized in that, The electrolyte is used in the preparation of secondary batteries.

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