Nitrile-based high-voltage-tolerant eutectic gel electrolyte and application in lithium metal battery

Abstract

The application belongs to the technical field of new energy materials and devices, and discloses a nitrile-based eutectic gel electrolyte resistant to high voltage and application thereof in a lithium metal battery. The electrolyte is prepared by in-situ thermal polymerization of a gel precursor solution containing a specific structure nitrile-based solvent, a lithium salt, a polymerization monomer and an initiator; wherein the nitrile-based solvent is a nitrile compound without hydrogen atoms on the alpha carbon atom directly connected with the cyano group in the molecular structure, and without hydrogen atoms or only with low reactivity hydrogen atoms on the beta carbon atom. The application eliminates the risk of decomposition of nitrile at high voltage due to the oxidation and dehydrogenation of alpha-H by selecting a specific nitrile solvent without active hydrogen from the root of the molecular structure. The prepared nitrile-based eutectic gel electrolyte has an oxidation potential of 5V or above and is compatible with lithium metal, and can improve the cycle performance of high specific energy lithium metal.

Description

Technical Field

[0001] This invention belongs to the field of new energy materials and devices technology, specifically relating to a high-voltage-resistant nitrile-based eutectic gel electrolyte and its application in lithium metal batteries, matching high-voltage, high-capacity positive and high-capacity negative electrodes to achieve the assembly of high-energy-density, high-safety solid-state batteries. Background Technology

[0002] With the rapid development of portable electronic devices and electric vehicles, the market has placed higher demands on the energy density of lithium-ion batteries. Lithium metal batteries (LMBs) have become more popular due to the high theoretical specific capacity (3860 mAh·g) of lithium metal anodes. -1 Low electrode potential (-3.04 V vs. standard hydrogen electrode) and low density (0.534 g·cm³). -3 This has become the core direction for the next generation of high-energy-density energy storage batteries, and is expected to achieve a revolutionary breakthrough in energy density, meeting the urgent needs of electric vehicles, portable electronic devices and energy storage systems for high-energy-density batteries.

[0003] However, the practical application of lithium metal battery systems has long been constrained by a series of severe challenges. First, lithium metal has extremely high reactivity, leading to serious side reactions when in contact with conventional liquid electrolytes. This continuously consumes electrolyte and active lithium, resulting in low coulombic efficiency and rapid capacity decay. Second, lithium dendrites inevitably form during deposition / stripping, and dendrite growth can puncture the separator, causing internal short circuits and posing serious safety hazards. Third, when lithium metal batteries are paired with high-voltage cathode materials (such as lithium-rich manganese-based cathodes, with a voltage window of 3.0-4.8 V vs Li / Li),… + When high-energy-density batteries are used, the electrolyte must withstand both the strong reducing environment on the negative electrode side and the strong oxidizing environment on the positive electrode side, which places higher demands on the electrochemical stability of the electrolyte. Traditional liquid carbonate electrolytes are prone to oxidative decomposition above 4.5 V, and their flammable and explosive properties further exacerbate the safety risks of high-energy-density batteries.

[0004] Solid-state electrolytes are considered an effective way to solve the above problems due to their intrinsic safety and potential to suppress lithium dendrite formation. Among various solid-state electrolytes, eutectic gel electrolytes (DEGEs) are semi-solid electrolyte systems formed by the interaction of hydrogen bond donors and acceptors to create a eutectic solution system, which is then fixed by a polymer network. This type of electrolyte retains the non-flammability and high ionic conductivity (approximately 10) of the eutectic system. -3 mS·cm -1The system benefits from the advantages of eutectic electrolytes and also possesses good mechanical strength and interfacial stability thanks to the polymer network. However, the electrochemical window of conventional eutectic systems (such as urea / acetamide systems based on amides and alcohols) is typically below 4.5 V, making it difficult to match with high-voltage cathode materials. At high voltages, these electrolytes are highly susceptible to oxidative decomposition, leading to rapid degradation of battery performance.

[0005] Nitrile solvents exhibit potential for matching high-voltage cathodes due to their high theoretical oxidation potential (>5 V). However, traditional nitrile solvents (such as acetonitrile CN and succinic acid SN) typically contain active hydrogen (α-H) on the carbon atom adjacent to the cyano group. These active hydrogens are easily activated in the strong oxidizing environment of the high-voltage cathode interface, inducing oxidative dehydrogenation, free radical reactions, and continuous decomposition of the nitrile solvent. This leads to electrolyte consumption, accumulation of by-products at the cathode interface, and increased interfacial impedance, severely affecting the cycle stability and capacity retention of the high-voltage cathode.

[0006] Therefore, how to improve the bulk stability of electrolytes and suppress their interfacial side reactions through molecular structure regulation, while achieving high voltage stability of nitrile electrolytes and compatibility with lithium metal anodes, has become a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0007] To address the problems of existing eutectic electrolytes, such as difficulty in simultaneously achieving high voltage stability and compatibility with lithium metal anodes, severe side reactions at high voltages, and poor reaction kinetics, this invention provides a nitrile-based eutectic gel electrolyte that can withstand high voltage and its application in lithium metal batteries. It prepares a nitrile-based eutectic gel electrolyte that can be matched with high-voltage, high-capacity cathodes, has good compatibility with lithium anodes, and exhibits excellent reaction kinetics, for use in assembling high-safety, high-energy-density solid-state batteries.

[0008] This invention utilizes nitrile solvent molecular structure design to regulate active hydrogen sites within the molecule, and combines this with a eutectic system construction and in-situ thermal polymerization crosslinking strategy to construct a nitrile eutectic gel electrolyte with a wide electrochemical window, high ionic conductivity, and excellent interfacial compatibility. This gel electrolyte effectively improves the bulk and interfacial stability of the electrolyte under high voltage conditions, suppresses side reactions at the high-voltage cathode interface, thereby achieving excellent cycle performance and capacity retention in high-energy-density lithium metal batteries. It represents a promising high-voltage lithium metal battery gel electrolyte and its preparation method.

[0009] The technical solution for achieving the present invention:

[0010] A first aspect of the present invention is to provide a nitrile eutectic gel electrolyte that can withstand high voltage, said electrolyte being prepared by in-situ polymerization of a gel precursor solution comprising the following components:

[0011] Solid lithium salt, wherein the solid lithium salt is a Lewis acid lithium salt with a hydrogen bond acceptor structure.

[0012] The polymerizable monomer is a multifunctional acrylate compound having carbon-carbon double bonds and ester groups or a fluorinated multifunctional acrylate crosslinking agent.

[0013] Polymerization initiator,

[0014] Nitrile solvents, wherein the nitrile solvents are nitrile solvents in which the α-carbon atom directly bonded to the cyano carbon in the molecular structure does not contain a hydrogen atom, and the β-carbon atom does not contain a hydrogen atom or only contains a hydrogen atom with low reactivity.

[0015] Functional additives.

[0016] Furthermore, the solid lithium salt includes, but is not limited to, one or more of lithium difluorosulfonylimide (LiFSI), lithium bis(trifluoromethanesulfonylimide) (LiTFSI), lithium bis(oxalate)borate (LiBOB), lithium difluorooxalateborate (LiDFOB), and lithium tetrafluoroborate (LiBF4).

[0017] Furthermore, the nitrile solvents include, but are not limited to, one or more of trimethylacetonitrile (TMA), triethylacetonitrile (TEAN), dimethylmalononitrile (DMMN), tetramethylbutadione (TMSN), 2,2,4,4-tetramethylglutaronitrile (TMPSN), 2,2,3,3-tetrafluorobutadione (TFSN), trifluoroacetonitrile (TFCN), and 1-cyano-1-ethylcyclopentane.

[0018] Furthermore, the polymerizing monomers include, but are not limited to, one or more of pentaerythritol tetraacrylate (PETEA), ethoxylated trimethylolpropane triacrylate (ETPTA), polyethylene glycol dimethacrylate (PEGDMA), and trimethylolpropane triacrylate (TMPTA).

[0019] Furthermore, the initiator is an azo radical thermal initiator, including but not limited to azobisisobutyronitrile (AIBN) and azobisisoheptanenitrile (ABVN).

[0020] Furthermore, the functional additives include, but are not limited to, one or more of fluoroethylene carbonate (FEC) and lithium nitrate (LiNO3).

[0021] A second aspect of the present invention provides a method for preparing a nitrile eutectic gel electrolyte that can withstand high voltage, the specific steps of which are as follows:

[0022] (1) Under the protection of an inert gas, the nitrile hydrogen bond donor solvent and the hydrogen bond acceptor lithium salt are mixed evenly to obtain a homogeneous nitrile eutectic precursor solution 1.

[0023] (2) Add high voltage resistant polymer monomer, initiator and functional additive to precursor solution 1 in sequence, and stir continuously to obtain homogeneous precursor solution 2;

[0024] (3) Inject the precursor solution 2 into the battery cell housing with high voltage, high capacity positive electrode and high capacity negative electrode. After assembly in an inert atmosphere, allow it to stand at 50-100 °C for 0.5-3 hours for in-situ thermal polymerization to obtain a high voltage nitrile eutectic gel-based solid battery.

[0025] Furthermore, the amounts of each substance in the precursor solution 1 are as follows, calculated in molar ratios:

[0026] Nitrile solvents: lithium salts = (0.5~8):(1~10);

[0027] Furthermore, the amounts of the two substances in the precursor solution, expressed as mass fractions, are as follows:

[0028] High voltage resistant polymer monomers: 0.5-10 wt%

[0029] Initiator: 0.1-2 wt%

[0030] Functional additives: 0.1-15 wt%

[0031] A third aspect of the present invention is to provide the application of the high-voltage-resistant nitrile eutectic gel electrolyte in a lithium metal battery, the lithium metal battery comprising a positive electrode, a negative electrode, a separator, and a high-voltage-resistant nitrile eutectic gel electrolyte.

[0032] Furthermore, the positive electrode material is a high-voltage, high-capacity inorganic material, including but not limited to one or more of lithium-rich manganese-based positive electrode materials (LRMO), nickel-cobalt-manganese-based ternary positive electrode materials (NCM), and lithium cobalt oxide positive electrode materials (LCO). The negative electrode material includes but is not limited to one or more of high-capacity lithium metal, lithium-based alloys, and silicon-carbon composite materials.

[0033] Furthermore, the battery casing of the present invention includes, but is not limited to, one of the following: button cell battery, pouch cell battery, cylindrical battery, stacked battery, and wound battery.

[0034] Furthermore, the battery cell casing includes, but is not limited to, CR2032 button cell, the separator is a 12 μm thick polypropylene ceramic separator, and the amount of precursor solution 2 is 10 μL-100 μL.

[0035] Furthermore, the entire process of solution preparation and battery installation described in this invention is carried out under an inert atmosphere, which is nitrogen or argon.

[0036] Advantages and beneficial effects of the present invention:

[0037] (1) This invention constructs a nitrile eutectic gel electrolyte with a wide electrochemical window, high ionic conductivity and excellent interfacial compatibility by regulating the molecular structure of nitrile molecules, by limiting the active hydrogen sites in the molecular structure, and by combining the construction of eutectic systems and in-situ thermal polymerization crosslinking strategies.

[0038] (2) The high-voltage nitrile eutectic gel electrolyte provided by the present invention has a wide electrochemical window, high ionic conductivity and good cycle performance. At the same time, it achieves high voltage stability of the electrolyte and compatibility with lithium metal anode, and constructs a matching high voltage, high capacity positive electrode and high capacity anode to realize the assembly of high specific energy and high safety solid-state battery. Attached Figure Description

[0039] Figure 1 Optical images of a nitrile eutectic electrolyte that has not polymerized at room temperature (left) and a nitrile eutectic gel electrolyte that has undergone in-situ thermal polymerization (right);

[0040] Figure 2 DSC analysis chromatograms of high-voltage nitrile eutectic gel electrolyte (Example 1) and trimethylacetonitrile pure solvent;

[0041] Figure 3 Linear sweep voltammetry (LSV) curves for high-voltage resistant nitrile eutectic gel electrolytes;

[0042] Figure 4 The results of coulombic efficiency tests of Li||Cu half-cells in high-voltage nitrile eutectic gel electrolytes and nitrile gel electrolytes (Comparative Example 1) using the Aurbach method are shown in the figure.

[0043] Figure 5 Graphs showing the constant potential fluctuation test of LRMO||Li cells from 4.0 to 5.6 V;

[0044] Figure 6 The first and fifth charge-discharge curves of a high-voltage nitrile eutectic gel electrolyte LRMO||Li full cell are shown.

[0045] Figure 7 A comparison chart of full-cell capacity retention versus cycle count for high-voltage nitrile eutectic gel electrolyte and ordinary nitrile gel electrolyte (Comparative Example 2);

[0046] Figure 8 The curves are symmetrical battery cycle curves for Example 3, Comparative Example 1, and Comparative Example 3. Detailed Implementation

[0047] To further illustrate the technical means employed by the present invention to achieve the above-mentioned objectives, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are merely illustrative and are not intended to limit the scope of protection of the present invention. The scope of protection of the present invention includes, but is not limited to, the following embodiments.

[0048] Example 1

[0049] The preparation steps of a high-voltage resistant nitrile-based eutectic gel electrolyte for lithium metal batteries are as follows:

[0050] (1) 0.4116 g of lithium salt LiTFSI, 0.0557 g of lithium salt LiDFOB and 1.19 g of trimethylacetonitrile were mixed evenly in a glove box under an inert atmosphere to obtain a homogeneous eutectic precursor solution 1 of nitrile.

[0051] (2) Add 0.1657 g of fluoroethylene carbonate, 27 mg of high voltage resistant polymerizable monomer PETEA and 1.9 mg of initiator AIBN to the nitrile eutectic precursor solution 1 in sequence, and stir continuously to obtain homogeneous precursor solution 2;

[0052] (3) The precursor solution 2, which was stirred evenly in the reagent bottle, was placed in an oven at 60 °C for 3 hours for in-situ thermal polymerization to obtain optical images of nitrile eutectic gel-based materials resistant to high voltage.

[0053] The nitrile eutectic gel electrolyte obtained by thermal polymerization in Example 1 was subjected to differential scanning calorimetry (DSC) testing. The test temperature range was -100 to 250 °C, the test environment was nitrogen, and the heating rate was 5 °C / min. -1 .

[0054] Figure 1 Optical images are shown of the precursor solution 2 in the reagent bottle of Example 1, which is an unpolymerized nitrile eutectic electrolyte (left) at room temperature and a nitrile eutectic gel electrolyte (right) after polymerization at 60 °C for 3 h. It can be seen that the preparation of the nitrile eutectic electrolyte and the polymerization of the gel electrolyte are completed. Figure 2 The DSC analysis of the nitrile eutectic gel electrolyte and trimethylacetonitrile after polymerization in Example 1 is shown. It can be seen that the nitrile gel electrolyte has a lower melting point (-70.12 °C) than trimethylacetonitrile (19.41 °C).

[0055] Example 2

[0056] The unheated precursor solution 2 from Example 1 was used to assemble an SS||Li half-cell. The positive electrode was a stainless steel gasket (SS), and the negative electrode was a lithium metal disc with a diameter of 14 mm and a thickness of 450 μm. The electrochemical stability window of the SS||Li half-cell was tested. The amount of precursor solution 2 used was 80 μL. The battery casing was a commercial CR2032 button cell. The battery was sealed under 0.65 tons of pressure and placed in a 60 ℃ oven for 3 h until in-situ thermal polymerization was completed. The separator was a 12 μm thick polypropylene ceramic separator. The preferred injection tool was a pipette with a volume of 100 μL.

[0057] An SS||Li half-cell was used to test the electrochemical stability window, and after assembly, it was used at 0.2 mV s. -1 LSV testing was performed using an electrochemical workstation within the sweep speed and 2-7 V voltage test range. Figure 3 The LSV curve for Example 2 shows that Example 2 has a high voltage stability with an electrochemical window greater than 5 V.

[0058] Example 3

[0059] The unheated precursor solution 2 from Example 1 was used to assemble a Li||Cu half-cell. The Li||Cu half-cell was assembled with copper foil (Cu) as the positive electrode and lithium metal discs with a diameter of 14 mm and a thickness of 450 μm as the negative electrode. Coulombic efficiency tests were conducted. The amount of precursor solution 2 used was 80 μL. The battery casing was a commercial CR2032 button cell. The battery was sealed under 0.8 tons of pressure and placed in a 60 ℃ oven for 3 h until in-situ thermal polymerization was completed. The separator was a 12 μm thick polypropylene ceramic separator. The preferred injection tool was a pipette with a volume of 100 μL.

[0060] The Li||Cu half-cell used for testing coulombic efficiency was assembled at 0.5 mA cm⁻¹. -2 0.5 mAh cm -2 The current density was measured, and cyclic testing was conducted using the Aurbach method. Figure 4 The coulomb efficiency curves for Example 3 and Comparative Example 1 show that the average coulomb efficiency of Example 3 is 98.72%, which is significantly better than that of Comparative Example 3 (90.54%).

[0061] Example 4

[0062] The unheated precursor solution 2 from Example 1 was used to assemble an LRMO||Li battery, with lithium-rich manganese-based material (LRMO) as the cathode and a cathode loading of 9 mg / cm³. -2LRMO||Li batteries were assembled using lithium metal wafers with a diameter of 10 mm and a negative electrode diameter of 14 mm and a thickness of 450 μm. Constant potential floating test and charge-discharge cycle test were conducted. The precursor solution 2 volume was 80 μL. The battery casing used commercial CR2032 button cell. After the battery was sealed under 0.8 tons of pressure, it was placed in a 60 ℃ oven and left to stand for 3 hours until in-situ thermal polymerization was completed. The separator was a 12 μm thick polypropylene ceramic separator. The preferred injection tool was a pipette with a volume of 100 μL.

[0063] The LRMO||Li cells used for potentiostatic floating tests were evaluated for their electrochemical window by potentiostatic floating tests at 4.0–5.6 V after assembly. Figure 5 The graph shows the constant potential fluctuation test of the LRMO||Li battery in Example 4 from 4.0 to 5.6 V. Under a voltage fluctuation of 5 V, the battery can still exhibit a negligible leakage current density, proving the high voltage resistance potential of nitrile eutectic gel electrolytes.

[0064] The assembled full battery was activated at 0.1 C for 3 cycles, then subjected to charge-discharge cycles at 0.5 C, with a voltage range of 2-4.8 V. 1 C = 250 mAh g⁻¹ -1 . Figure 6 The above are the charge / discharge curves for the first and fifth cycles of Example 4. The discharge capacity in the first cycle exceeds 250 mAh g. -1 It reached 304.9 mAh g. -1 It has the feasibility of high specific energy applications. Figure 7 The capacity retention rate changes during full-cell charge-discharge cycles of Example 4 and Comparative Example 2 are shown. After 40 cycles, the capacity retention rate of Example 4 is 88.4%, which is significantly better than that of Comparative Example 2 (76.1%).

[0065] Comparative Example 1

[0066] The preparation method and application steps of a nitrile gel electrolyte are as follows:

[0067] (1) 0.4116 g of lithium salt LiTFSI, 0.0557 g of lithium salt LiDFOB and 0.97 g of acetonitrile were mixed evenly in a glove box under an inert atmosphere to obtain a homogeneous nitrile precursor solution 1.

[0068] (2) Add 0.1437 g of fluoroethylene carbonate, 22 mg of high voltage resistant polymerizable monomer PETEA and 1.5 mg of initiator AIBN to nitrile precursor solution 1 in sequence, and stir continuously to obtain homogeneous precursor solution 2;

[0069] (3) The precursor solution 2, which was stirred evenly in the reagent bottle, was placed in an oven at 60 °C for 3 hours for in-situ thermal polymerization.

[0070] The unheated precursor solution 2 from Comparative Example 1 was used to assemble a Li||Cu half-cell. The Li||Cu half-cell was assembled with copper foil (Cu) as the positive electrode and lithium metal discs with a diameter of 14 mm and a thickness of 450 μm as the negative electrode. Coulombic efficiency tests were conducted. The amount of precursor solution 2 used was 80 μL. The battery casing was a commercial CR2032 button cell. The battery was sealed under 0.8 tons of pressure and placed in a 60 ℃ oven for 3 h until in-situ thermal polymerization was completed. The separator was a 12 μm thick polypropylene ceramic separator. The preferred injection tool was a pipette with a volume of 100 μL.

[0071] The Li||Cu half-cell used for testing coulombic efficiency was assembled at 0.5 mA cm⁻¹. -2 0.5 mAh cm -2 The current density was measured, and cyclic testing was conducted using the Aurbach method. Figure 4 The coulomb efficiency curves for Example 3 and Comparative Example 1 show that the average coulomb efficiency of Example 3 is 98.72%, which is significantly better than that of Comparative Example 3 (90.54%).

[0072] Comparative Example 2

[0073] The unheated precursor solution 2 from Comparative Example 1 was used to assemble an LRMO||Li battery, with lithium-rich manganese-based material (LRMO) as the cathode and a cathode loading of 9 mg cm⁻¹. -2 LRMO||Li batteries were assembled from lithium metal wafers with a diameter of 10 mm and a negative electrode diameter of 14 mm and a thickness of 450 μm for charge-discharge cycle testing. The precursor solution 2 was used in a volume of 80 μL. The battery casing was made of commercial CR2032 button cell. The battery was sealed under 0.8 tons of pressure and then placed in a 60 ℃ oven for 3 h until in-situ thermal polymerization was completed. The separator was a 12 μm thick polypropylene ceramic separator. The preferred injection tool was a pipette with a volume of 100 μL.

[0074] The assembled full battery was activated at 0.1 C for 3 cycles, then subjected to charge-discharge cycles at 0.5 C, with a voltage range of 2-4.8 V. 1 C = 250 mAh g⁻¹ -1 . Figure 7 The capacity retention rate changes during full-cell charge-discharge cycles of Example 4 and Comparative Example 2 are shown. After 50 cycles, the capacity retention rate of Example 4 is 85.7%, which is significantly better than that of Comparative Example 2 (76.1%).

[0075] Comparative Example 3

[0076] The preparation method and application steps of a conventional nitrile gel electrolyte are as follows:

[0077] (1) 0.4726 g of lithium salt LiTFSI, 0.0531 g of lithium salt LiDFOB and 0.5274 g of succinate were mixed evenly in an inert atmosphere glove box to obtain a homogeneous nitrile precursor solution 1.

[0078] (2) Add 0.15 g of fluoroethylene carbonate, 20 mg of high voltage resistant polymerizable monomer PETEA and 1.5 mg of initiator AIBN to nitrile precursor solution 1 in sequence, and stir continuously to obtain homogeneous precursor solution 2;

[0079] (3) The precursor solution 2, which was stirred evenly in the reagent bottle, was placed in an oven at 60 °C for 3 hours for in-situ thermal polymerization.

[0080] The unheated precursor solution 2 from Examples 1, 3, and 2 were used to assemble Li||Li symmetric batteries. The Li||Li symmetric batteries were assembled using lithium metal discs with a diameter of 14 mm and a thickness of 450 μm as both the positive and negative electrodes. Symmetric battery cycle tests were conducted. The amount of precursor solution 2 used was 80 μL. The battery casing was a commercial CR2032 button cell. The battery was sealed under 0.8 tons of pressure and placed in a 60 °C oven for 3 h until in-situ thermal polymerization was completed. The separator was a 12 μm thick polypropylene ceramic separator. The preferred injection tool was a pipette with a volume of 100 μL.

[0081] A Li||Li symmetric cell was used to test the cycling of symmetric cells, assembled at 0.5 mA cm⁻¹. -2 0.5 mAh cm -2 Cyclic tests were conducted on the current density. Figure 8 The cycling curves of the symmetrical batteries in Example 3, Comparative Example 1, and Comparative Example 3 show that the symmetrical battery in Example 3 can cycle stably for more than 800 hours, while both Comparative Example 1 and Comparative Example 3 experienced punctures within 600 hours and could not operate normally.

[0082] The above description is only a preferred embodiment of the present invention. Without departing from the technical design and core principles of the present invention, those skilled in the art can make reasonable structural adjustments and process optimizations for raw material systems such as hydrogen bond donor lithium salts, low-activity nitrile solvents, multifunctional additives, multifunctional polymerization monomers, and polymerization initiators. Such equivalent substitutions and adaptive improvements are also included in the scope of protection of the present invention.

Claims

1. A nitrile eutectic gel electrolyte that can withstand high voltage, characterized in that, The electrolyte is prepared by in-situ polymerization of a gel precursor solution containing the following components: Solid lithium salt, wherein the solid lithium salt is a Lewis acid lithium salt with a hydrogen bond acceptor structure. The polymerizable monomer is a multifunctional acrylate compound having carbon-carbon double bonds and ester groups or a fluorinated multifunctional acrylate crosslinking agent. Polymerization initiator, Nitrile solvents, wherein the nitrile solvents are nitrile solvents in which the α-carbon atom directly bonded to the cyano carbon in the molecular structure does not contain a hydrogen atom, and the β-carbon atom does not contain a hydrogen atom or only contains a hydrogen atom with low reactivity. Functional additives.

2. The high-voltage-resistant nitrile eutectic gel electrolyte according to claim 1, characterized in that, The nitrile solvent is one or more of trimethylacetonitrile, triethylacetonitrile, dimethylmalonium, tetramethylbutadione, 2,2,4,4-tetramethylglutaronitrile, 2,2,3,3-tetrafluorobutadione, trifluoroacetonitrile, and 1-cyano-1-ethylcyclopentane.

3. The high-voltage-resistant nitrile eutectic gel electrolyte according to claim 1, characterized in that, The solid lithium salt is one or more of lithium dibis(fluorosulfonyl)imide, lithium di(trifluoromethanesulfonyl)imide, lithium bis(oxalate)borate, lithium difluorooxalateborate, and lithium tetrafluoroborate.

4. The nitrile eutectic gel electrolyte with high voltage tolerance according to claim 1, characterized in that, The polymer monomer is one or more of pentaerythritol tetraacrylate, ethoxylated trimethylolpropane triacrylate, polyethylene glycol dimethacrylate, and trimethylolpropane triacrylate.

5. The high-voltage-resistant nitrile eutectic gel electrolyte according to claim 1, characterized in that, The polymerization initiator is an azo radical-type thermal initiator.

6. The high-voltage-resistant nitrile eutectic gel electrolyte according to claim 1, characterized in that, The functional additives are selected from one or two of fluoroethylene carbonate and lithium nitrate.

7. The method for preparing a high-voltage-resistant nitrile eutectic gel electrolyte according to any one of claims 1 to 6, characterized in that, The steps include the following: (1) Mix solid lithium salt with nitrile solvent in a molar ratio and stir under an inert atmosphere until completely dissolved to form a homogeneous eutectic precursor solution 1; (2) Add polymer monomer, polymerization initiator and functional additive to precursor solution 1 in sequence, and stir continuously to obtain homogeneous precursor solution 2; (3) The precursor solution 2 was allowed to stand at 50-100 °C for 0.5-3 hours for in-situ thermal polymerization to obtain a high-voltage resistant nitrile eutectic gel electrolyte; The molar ratios of the components in the precursor solution 1 are as follows: Nitrile solvents: lithium salts = (0.5~8):(1~10); The mass fraction ratios of the components in the precursor solution 2 are as follows: Polymer monomer: 0.5-10 wt% Initiator: 0.1-2.0 wt% Functional additives: 1-10 wt%.

8. The application of the high-voltage-resistant nitrile-based eutectic gel electrolyte according to any one of claims 1 to 6 in lithium metal batteries, characterized in that, Lithium metal batteries consist of a positive electrode, a negative electrode, a separator, and a nitrile-based eutectic gel electrolyte that can withstand high voltage.

9. The application according to claim 8, characterized in that, The positive electrode material is one or more of lithium-rich manganese-based positive electrode materials, nickel-cobalt-manganese-based ternary positive electrode materials, and lithium cobalt oxide positive electrode materials, and the negative electrode material is one or more of lithium metal, lithium-based alloys, and silicon-carbon composite materials.

10. The application according to claim 8, characterized in that, The lithium metal battery is one of the following: button cell battery, pouch cell battery, cylindrical battery, stacked battery, and wound battery.

Images