A lithium-loving elastic electrolyte and its preparation method, and a solid-state lithium metal battery

Abstract

This invention relates to the field of energy storage device technology, and particularly to a lithium-loving elastic electrolyte and its preparation method, as well as a solid-state lithium metal battery. The lithium-loving elastic electrolyte comprises: an elastic electrolyte matrix and an MXene-rich coating covering the surface of the electrolyte matrix; wherein the elastic electrolyte matrix is ​​selected from at least one of natural rubber, nitrile rubber, hydrogenated nitrile rubber, silicone rubber, butyl rubber, and fluororubber; the MXene-rich coating is obtained by swelling an MXene film after impregnation in a lithium salt plasticizer solution, wherein the MXene film is composed of MXene-coated microspheres and a binder. This lithium-loving elastic electrolyte can improve the electrochemical performance and lifespan of the elastic electrolyte matrix, and optimize the overall battery performance of the lithium battery.

Description

Technical Field

[0001] This invention relates to the field of energy storage device technology, and in particular to a lithium-loving elastic electrolyte and its preparation method, and a solid-state lithium metal battery. Background Technology

[0002] Lightweight, rechargeable lithium metal batteries have garnered significant attention as candidates for high-performance batteries. Their substantial advantages are primarily attributed to their ultra-high energy density (3860 mAh / g) and the lowest electrochemical potential of lithium metal (-3.04V vs. standard hydrogen electrode). However, serious safety issues caused by uneven lithium deposition prevent rechargeable lithium metal batteries from being directly applied to traditional liquid organic electrolytes. Furthermore, the safety hazards of explosions and combustion in organic electrolytes caused by lithium dendrite short circuits pose a significant risk and limit the development of lithium metal batteries.

[0003] Compared to liquid electrolytes, solid electrolytes typically possess higher mechanical strength and thermal stability, and can prevent lithium dendrite infiltration, thus avoiding explosions, and have attracted considerable attention over the past few decades. Among various solid electrolytes, solid polymer electrolytes exhibit a series of advantages, such as good plasticity and adhesion, high stability, low density, and flexibility. Solid polymer electrolytes are considered a promising type of solid electrolyte. However, the practical application of solid polymer electrolytes is still hindered by slow ion transport and severe lithium anode / electrolyte interface reactions. Due to the high reducing power of metallic lithium, severe irreversible reduction reactions usually occur at the lithium anode / electrolyte interface, leading to polymer matrix decomposition and the formation of byproducts such as Li₂O, C₂H₄, and H₂. These undesirable byproducts result in increased interfacial impedance and roughened lithium surfaces.

[0004] Artificial interface modification layers not only suppress lithium dendrite growth in lithium metal anodes by improving mechanical properties, but also effectively promote rapid lithium-ion transport and uniform deposition at the interface due to their good lithiophilicity and low lithium-ion diffusion barrier. Although constructing compatible artificial interface layers in situ on lithium anodes is challenging, this strategy is crucial for addressing severe interface problems. Summary of the Invention

[0005] To address the aforementioned interface issues in lithium batteries, this invention provides a lithium-loving elastic electrolyte, its preparation method, and a solid-state lithium metal battery.

[0006] In a first aspect, a lithium-loving elastic electrolyte is provided, comprising: an elastic electrolyte matrix and an MXene-rich coating covering the surface of the electrolyte matrix; The elastic electrolyte matrix is ​​selected from at least one of natural rubber, nitrile rubber, hydrogenated nitrile rubber, silicone rubber, butyl rubber, and fluororubber. The MXene-rich coating is obtained by swelling an MXene coating in a lithium salt plasticizer solution, wherein the MXene coating is composed of MXene-coated microspheres and an adhesive.

[0007] As one embodiment of the invention, the MXene is selected from at least one of transition metal carbides, transition metal nitrides, and transition metal carbonitride ultrathin two-dimensional nanosheets; The surface of the microspheres carries a positive charge and is selected from at least one of polystyrene microspheres, polyvinyl chloride microspheres, silica microspheres, and titanium dioxide microspheres.

[0008] In one embodiment of the invention, the adhesive is selected from at least one of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, poly(methyl methacrylate), polyacrylonitrile, polyvinyl alcohol, and polyvinylpyrrolidone. The lithium salt is selected from at least one of LiTFSI, LiPF6, LiBF4, and LiClO4; the plasticizer is selected from at least one of ethylene glycol dimethyl ether, ethylene carbonate, dimethyl carbonate, diethyl carbonate, vinylene carbonate, vinyl ethylene carbonate, and propylene carbonate.

[0009] As one embodiment of the invention, the thickness of the MXene coating ranges from 100 to 10000 nm; the thickness of the elastic electrolyte matrix ranges from 20 to 1000 μm.

[0010] Secondly, a method for preparing a lithium-loving elastic electrolyte is provided, comprising the following steps: (1) Preparation of elastic electrolyte matrix; (2) Preparation of MXene-coated microspheres (MXene@microspheres), the steps include: ① A dispersion of MXene was prepared using a selective etching method; ② After adding the MXene dispersion to a positively charged cationic microsphere solution, electrostatic self-assembly is performed under stirring conditions, and MXene@microspheres are obtained after drying. (3) Prepare a dispersion of MXene@microspheres and binder and prepare an MXene coating on the surface of the elastic electrolyte matrix HNBR by spraying. Then place it on a glass plate for hot pressing. (4) The hot-pressed film is immersed in a lithium salt plasticizer solution and fully swollen to obtain the lithium-loving elastic electrolyte.

[0011] In one embodiment of the invention, in step ②, the concentrations of both the MXene dispersion and the microsphere solution are 1 mg / mL, and the volume ratio of the MXene dispersion to the microsphere solution is 10 mL:(80~120) mL.

[0012] As one embodiment of the invention, in step (3), the mass ratio of MXene@microspheres to adhesive is 1:(0.02~10).

[0013] As one embodiment of the invention, in step (4), the pressure range of hot pressing is 10~1000MPa, the temperature range is 30~400℃, and the time range is 10~120min; The concentration range of the lithium salt plasticizer is 0.1~5 mol / L, and the volume of the lithium salt plasticizer is 8~12 mL.

[0014] Thirdly, a solid-state lithium metal battery is provided, comprising a lithium-loving elastic electrolyte as described in the first aspect.

[0015] By combining negatively charged MXene nanosheets with positively charged microspheres using electrostatic self-assembly technology, monodisperse composite microspheres are formed. These microspheres are then dispersed in an organic solution containing a polymer binder, and an artificial interface modification layer—an MXene coating—is formed on the surface of an elastic electrolyte substrate through spraying and hot pressing. This MXene coating isolates the lithium metal from direct contact with the electrolyte substrate. Furthermore, the MXene-based network layer (MXene-coated microspheres) is rich in polar functional groups, which react with the swollen lithium salt through Lewis acid-base interactions, thereby establishing efficient lithium-ion transport channels. This ensures that lithium ions can be rapidly and uniformly transported to the lithium metal surface and uniformly nucleate and grow under the guidance of the lithium-loving MXene, effectively suppressing the formation of lithium dendrites. Using the lithium-loving elastic electrolyte provided by this invention can significantly improve the cycle life, rate performance, and safety of lithium metal batteries. In addition, the MXene-rich coating can also improve the mechanical properties of the electrolyte surface.

[0016] The lithium metal battery employing the lithium-loving elastic electrolyte of the present invention has the following beneficial technical effects: (1) The present invention significantly improves the mechanical properties of the electrolyte by designing a rich MXene coating, enabling the electrolyte to withstand greater mechanical pressure without breaking, thereby enhancing the structural stability and long-term cycle performance of lithium metal batteries.

[0017] (2) The present invention significantly optimizes the migration performance of lithium ions at the electrolyte interface by constructing an efficient lithium ion transport channel between the electrolyte and metallic lithium.

[0018] (3) Due to the guiding effect of the MXene coating, lithium ions are uniformly nucleated and grown on the surface of lithium metal, which significantly inhibits the formation of lithium dendrites. This greatly improves the safety and stability of the battery and provides an effective solid electrolyte material solution for realizing the practical application of high-performance lithium metal batteries. Attached Figure Description

[0019] Figure 1 Scanning electron microscope images of polystyrene microspheres at different magnifications; where a) is 5000x magnification and b) is 40000x magnification.

[0020] Figure 2 Scanning electron microscope images of MXene@PS microspheres at different magnifications: a) 10,000x magnification, b) 40,000x magnification.

[0021] Figure 3 This is a transmission electron microscope image of MXene@PS microspheres.

[0022] Figure 4 The images are scanning electron microscope images of the HNBR surface at different magnifications: a) 250x magnification and b) 2000x magnification.

[0023] Figure 5 Scanning electron microscope images of the MXene / HNBR surface at different magnifications: a) 1000x magnification, b) 10000x magnification.

[0024] Figure 6 The images are scanning electron microscope (SEM) images and energy-dispersive X-ray spectra of the MXene / HNBR surface; where a) is the SEM image and b) is the energy-dispersive X-ray spectra.

[0025] Figure 7 The images are scanning electron microscope (SEM) images and energy-dispersive X-ray spectra of the cross-section of the MXene-rich coating; where a) is the SEM image and b) is the energy-dispersive X-ray spectra.

[0026] Figure 8 A schematic diagram of the structure of an MXene-rich coating for a lithiophilic elastic electrolyte to enhance surface mechanical properties.

[0027] Figure 9 The stretching curves of the MXene / HNBR electrolyte are shown.

[0028] Figure 10 The curve of MXene / HNBR electrolyte after 10,000 compression cycles at 10% strain.

[0029] Figure 11 Nanoindentation test curves for MXene / HNBR electrolyte.

[0030] Figure 12 The puncture stress-strain curves are for MXene / HNBR electrolyte and elastic electrolyte matrix HNBR.

[0031] Figure 13The CCD test curves are for symmetric lithium metal batteries with MXene / HNBR electrolyte and HNBR elastic electrolyte matrix at room temperature.

[0032] Figure 14 The figures show the rate cycling performance curves of symmetric lithium metal batteries with MXene / HNBR electrolyte and HNBR elastic electrolyte matrix at room temperature.

[0033] Figure 15 For lithium metal symmetric cells based on MXene / HNBR electrolyte at 0.1 mA / cm 2 0.1mAh / cm 2 The following is a cycle curve.

[0034] Figure 16 The cycling curves of the full cell based on MXene / HNBR electrolyte at 0.5C are shown. Detailed Implementation

[0035] The technical solution of the present invention is illustrated below through specific embodiments. It should be understood that one or more steps mentioned in the present invention do not preclude the existence of other methods and steps before or after the combined steps, or that other methods and steps may be inserted between these explicitly mentioned steps. It should also be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Unless otherwise stated, the numbering of each method step is only for the purpose of identifying each method step, and not for limiting the order of each method or limiting the scope of the present invention. Changes or adjustments to their relative relationships, without substantial changes to the technical content, can also be considered as within the scope of the present invention.

[0036] The raw materials and instruments used in the examples are not subject to any specific restrictions on their source; they can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0037] Example 1 This embodiment provides a lithium-loving elastic electrolyte, which includes an elastic electrolyte matrix and an MXene-rich coating covering the surface of the electrolyte matrix. The MXene-rich coating is composed of MXene-coated microspheres, a binder, a lithium salt, and a plasticizer. The MXene coating is tightly bonded to the elastic matrix during hot pressing to form an integrated structure.

[0038] In some implementations, MXene-coated microspheres (morphologically as shown) Figure 1 , Figure 2 and Figure 3 As shown), preferably, MXene is selected from at least one of transition metal carbides, transition metal nitrides, and transition metal carbonitride ultrathin two-dimensional nanosheets; the elastic electrolyte matrix (morphology as shown) Figure 4The microspheres shown are selected from natural rubber, nitrile rubber, hydrogenated nitrile rubber, silicone rubber, butyl rubber, and fluororubber; the surface of the microspheres is positively charged and is selected from at least one of polymer microspheres, such as polystyrene microspheres, polyvinyl chloride microspheres, or inorganic microspheres (silica microspheres, titanium dioxide microspheres); The adhesive is selected from at least one of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, poly(methyl methacrylate), polyacrylonitrile, polyvinyl alcohol, and polyvinylpyrrolidone; the lithium salt is selected from at least one of LiTFSI, LiPF6, LiBF4, and LiClO4; and the plasticizer is selected from at least one of ethylene glycol dimethyl ether, ethylene carbonate, dimethyl carbonate, diethyl carbonate, vinylene carbonate, vinyl ethylene carbonate, and propylene carbonate.

[0039] In some embodiments, the mass ratio of MXene-coated microspheres to binder is between 1:10 and 50:1, i.e., 1:(0.02~10), the concentration of the lithium salt plasticizer ranges from 0.1 to 5 mol / L, and the MXene-coated microspheres and binder fully swell the lithium salt plasticizer solution. Due to the close packing of the MXene-coated microspheres during the hot-pressing process, a low-torsion structure is produced (e.g., Figure 5 , Figure 6 and Figure 7 (as shown), and sandwiched the polymer adhesive attached to the MXene nanosheet in the middle.

[0040] Example 2 This embodiment provides a lithium-loving elastic electrolyte with the following structure: Figure 8 As shown, its preparation method includes the following steps: (1) Preparation of elastic electrolyte matrix HNBR HNBR was dissolved in chlorobenzene to obtain a mixed solution with a concentration of 0.05 g / mL. Then, HVA-2 (1.5 wt.% vs HNBR) and BIBP (2.5 wt.% vs HNBR) were added to the aforementioned mixed solution and stirred at room temperature for 1 h to obtain a solution. The elastic electrolyte matrix HNBR with a thickness of 400 μm was prepared by casting.

[0041] (2) Preparation of MXene-coated microspheres: MXene@PS microspheres ① Preparation of MXene dispersion using selective etching: In an ice-water bath, LiF and 9 mol / L HCl solution were added to a polytetrafluoroethylene container and stirred for 30 min to ensure thorough mixing. The ratio of LiF to HCl was 1 g: 20 mL. Then, V2AIC powder was added in batches (the molar ratio of V2AIC powder to LiF was 1:7.5), and the reaction temperature was controlled to not exceed 35℃. The mixture was stirred for 36 h. After the reaction, the product was centrifuged multiple times, and the precipitate was washed with argon-containing deionized water until the pH of the upper liquid was >5. The lower product was redispersed in water and sonicated for 1 h under argon protection. Then, it was centrifuged at 3500 rpm for 30 min to obtain a uniformly dispersed MXene-V2C dispersion with a concentration of 1 mg / mL.

[0042] ② Add 10 mL of the aforementioned 1 mg / mL MXene-V2C dispersion to 100 mL of PS microsphere solution (1 mg / mL), and perform electrostatic self-assembly under stirring at 500 rpm. Then, dry the obtained MXene@PS microspheres in a freeze dryer for 7 days, and finally vacuum dry them at 60 °C for 24 h.

[0043] (3) Preparation of MXene coating PVP was weighed according to the MXene@PS microsphere:PVP mass ratio of 1:0.05; MXene@PS microspheres and PVP were added to 0.5 mL of isopropanol dispersion, stirred for 30 min and then sonicated for 30 min to obtain MXene@PS / PVP solution; a film was prepared on the surface of elastic electrolyte substrate HNBR using the MXene@PS / PVP solution by spraying, and then hot-pressed at 150℃ for 60 min at a pressure range of 10 to 1000 MPa to obtain an MXene coating with a thickness of 550 nm.

[0044] (4) Preparation of MXene / HNBR electrolyte The film obtained in step (3) was placed in 10 mL of 2 mol / L LiTFSI-PC solution to swell for 12 h, and finally an MXene / HNBR electrolyte including an elastic electrolyte matrix and an MXene-rich coating covering the surface of the electrolyte matrix was obtained.

[0045] The elastic electrolyte matrix HNBR obtained in step (1) was characterized by SEM, and the aforementioned results were obtained. Figure 4 Scanning electron microscope (SEM) images of the polystyrene microspheres and MXene@PS microspheres from step (2); SEM characterization of the polystyrene microspheres and MXene@PS microspheres obtained in step (2) yielded the aforementioned... Figure 1 and Figure 2 The scanning electron microscope image shows the MXene@PS microspheres after TEM characterization, yielding the aforementioned results. Figure 3Transmission electron microscope image; SEM and EDS characterization of the MXene / HNBR electrolyte obtained in step (4) yielded the aforementioned Figure 5 , Figure 6 and Figure 7 Scanning electron microscope image and energy-dispersive X-ray spectrum.

[0046] Example 3 This embodiment provides an elastic electrolyte with the following structure: Figure 8 As shown, its preparation method includes the following steps: (1) Preparation of elastic electrolyte matrix HBR HBR was dissolved in chlorobenzene to obtain a mixed solution with a concentration of 0.05 g / mL. Then, HVA-2 (1.5 wt.% vs HNBR) and BIBP (2.5 wt.% vs HNBR) were added to the aforementioned mixed solution and stirred at room temperature for 1 h to obtain a solution. An elastic electrolyte matrix HNBR with a thickness of 20 μm was prepared by casting.

[0047] (2) Preparation of MXene@PVC microspheres ① Preparation of MXene dispersion using selective etching: In an ice-water bath, LiF and 9 mol / L HCl solution were added to a polytetrafluoroethylene container and stirred for 30 min to ensure thorough mixing. The ratio of LiF to HCl was 1 g: 20 mL. Then, Ti3AlCN powder was added in batches (the molar ratio of Ti3AlCN powder to LiF was 1:6), and the reaction temperature was controlled to not exceed 35℃. The mixture was stirred for 36 h. After the reaction, the product was centrifuged multiple times, and the precipitate was washed with argon-containing deionized water until the pH of the upper liquid was >5. The lower product was redispersed in water and sonicated for 1 h under argon protection. Then, it was centrifuged at 3500 rpm for 30 min to obtain a uniformly dispersed MXene-Ti3CN dispersion with a concentration of 1 mg / mL.

[0048] ② Add 10 mL of the aforementioned 1 mg / mL MXene-Ti3CN dispersion to 80 mL of polystyrene PVC solution (1 mg / mL), and perform electrostatic self-assembly under stirring at 500 rpm. Then, dry the obtained MXene@PVC microspheres in a freeze dryer for 7 days, and finally vacuum dry them at 60 °C for 24 h.

[0049] (3) Preparation of MXene coating PVDF was weighed according to the MXene@PVC microsphere:PVDF mass ratio of 1:10; MXene@PVC microspheres and PVDF were added to 0.5 mL of isopropanol dispersion, stirred for 30 min and then sonicated for 30 min to obtain MXene@PVC / PVDF solution; a film was prepared on the surface of the elastic electrolyte substrate HBR using the MXene@PVC / PVDF solution by spraying, and then hot-pressed at 30℃ for 120 min at a pressure range of 10 to 1000 MPa to obtain an MXene coating with a thickness of 100 nm.

[0050] (4) Preparation of MXene / HBR electrolyte The film obtained in step (3) was placed in 8 mL of 5 mol / L LiBF4-DME solution and swollen for 10 h to finally obtain MXene / HBR electrolyte.

[0051] Example 4 This embodiment provides a lithium elastic electrolyte with the following structure: Figure 8 As shown, its preparation method includes the following steps: (1) Preparation of elastic electrolyte matrix IIR HBR was dissolved in chlorobenzene to obtain a mixed solution with a concentration of 0.05 g / mL. Then, HVA-2 (1.5 wt.% vs HNBR) and BIBP (2.5 wt.% vs HNBR) were added to the aforementioned mixed solution and stirred at room temperature for 1 h to obtain a solution. An elastic electrolyte matrix IIR with a thickness of 1000 μm was prepared by casting.

[0052] (2) Preparation of MXene@TiO2 microspheres ① Preparation of MXene dispersion using selective etching: In an ice-water bath, LiF and 9 mol / L HCl solution were added to a polytetrafluoroethylene container and stirred for 30 min to ensure thorough mixing. The ratio of LiF to HCl was 1 g: 20 mL. Then, Ti2AlN powder was added in batches (the molar ratio of Ti3AlCN powder to LiF was 1:8), and the reaction temperature was controlled to not exceed 35℃. The mixture was stirred for 36 h. After the reaction, the product was centrifuged multiple times, and the precipitate was washed with argon-containing deionized water until the pH of the upper liquid was >5. The lower product was redispersed in water and sonicated for 1 h under argon protection, followed by centrifugation at 3500 rpm for 30 min to obtain a uniformly dispersed MXene-Ti2N dispersion with a concentration of 1 mg / mL.

[0053] ② Quantitatively add 10 mL of the aforementioned 1 mg / mL MXene-Ti3C2 dispersion to 120 mL of TiO2 microsphere solution (1 mg / mL). -1In the process, electrostatic self-assembly was carried out under stirring at 500 rpm, and then the obtained MXene@TiO2 microspheres were dried in a freeze dryer for 7 days and finally vacuum dried at 60℃ for 24 hours.

[0054] (3) Preparation of MXene coating Weigh PVP according to the mass ratio of MXene@TiO2 microspheres to PVA of 1:0.02; add MXene@TiO2 microspheres and PVA to 0.5 mL of isopropanol dispersion, stir for 30 min and then sonicate for 30 min to obtain MXene@TiO2 / PVA solution; A thin film was prepared on the surface of an elastic electrolyte substrate IIR using a spraying method with MXene@TiO2 / PVA solution, and then hot-pressed at 400℃ for 10 min at a pressure range of 10 to 1000 MPa to obtain an MXene coating with a thickness of 10000 nm.

[0055] (4) Preparation of MXene / IIR electrolyte The film obtained in step (3) was placed in 12 mL of 0.1 mol / L LiBF4-DME solution and swollen for 30 h to finally obtain MXene / IIR electrolyte.

[0056] Comparative Example 1 This embodiment provides an elastic electrolyte, the preparation method of which includes the following steps: (1) Preparation of elastic electrolyte matrix HNBR HNBR was dissolved in chlorobenzene to obtain a mixed solution with a concentration of 0.05 g / mL. Then, HVA-2 (1.5 wt.% vs HNBR) and BIBP (2.5 wt.% vs HNBR) were added to the aforementioned mixed solution and stirred at room temperature for 1 h to obtain a solution. The elastic electrolyte matrix HNBR with a thickness of 400 μm was prepared by casting.

[0057] (2) Preparation of electrolytes The elastic electrolyte matrix HNBR obtained in step (1) was placed in 10 mL of 2 mol / L LiTFSI-PC solution and swollen for 12 h to obtain the elastic electrolyte.

[0058] Comparative Example 2 (1) Preparation of MXene-coated microspheres: MXene@PS microspheres ① Preparation of MXene dispersion using selective etching: In an ice-water bath, LiF and 9 mol / L HCl solution were added to a polytetrafluoroethylene container and stirred for 30 min to ensure thorough mixing. The ratio of LiF to HCl was 1 g: 20 mL. Then, V2AIC powder was added in batches (the molar ratio of V2AIC powder to LiF was 1:7.5), and the reaction temperature was controlled to not exceed 35℃. The mixture was stirred for 36 h. After the reaction, the product was centrifuged multiple times, and the precipitate was washed with argon-containing deionized water until the pH of the upper liquid was >5. The lower product was redispersed in water and sonicated for 1 h under argon protection. Then, it was centrifuged at 3500 rpm for 30 min to obtain a uniformly dispersed MXene-V2C dispersion with a concentration of 1 mg / mL.

[0059] ② Add 10 mL of the aforementioned 1 mg / mL MXene-V2C dispersion to 100 mL of PS microsphere solution (1 mg / mL), and perform electrostatic self-assembly under stirring at 500 rpm. Then, dry the obtained MXene@PS microspheres in a freeze dryer for 7 days, and finally vacuum dry them at 60 °C for 24 h.

[0060] (3) Preparation of modified elastic electrolyte matrix HNBR HNBR was dissolved in chlorobenzene to obtain a mixed solution with a concentration of 0.05 g / mL. Then, MXene@PS microspheres, PVP powder (MXene@PS microspheres:PVP mass ratio of 1:0.05), MXene@PS / PVP solution, HVA-2 (1.5 wt.% vs HNBR) and BIBP vulcanizing agent (2.5 wt.% vs HNBR) were added to the above mixed solution and stirred at room temperature for 1 h to obtain a solution. The modified elastic electrolyte matrix HNBR with a thickness of 400 μm was prepared by casting.

[0061] (3) Preparation of electrolytes The modified elastic electrolyte matrix HNBR was swollen in 10 mL of 2 mol / L LiTFSI-PC solution for 12 h to obtain the elastic electrolyte.

[0062] Test Example 1 Mechanical properties of the electrolytes obtained in Examples 2-4, as well as Comparative Examples 1 and 2, were tested, including tensile testing, compression cycle testing, nanoindentation testing, and puncture performance testing. The test results are shown in Table 1.

[0063] Table 1 Mechanical Performance Test Results Among them, the partial performance test results of the MXene / HNBR electrolyte obtained in Example 2 are as follows: Figures 9-12 As shown. By Figure 9 The tensile test results show that the tensile strength of the MXene / HNBR electrolyte obtained in Example 1 is 0.56 MPa, and the elongation at break is 704%. Figure 10 Compression cycle tests show that the MXene / HNBR electrolyte obtained in Example 1 exhibits excellent normal stress durability, capable of withstanding pressures up to 10,000 cycles, and the time-compression deformation curve still shows a linear relationship at the 10,000th cycle; Figure 11 Nanoindentation tests show that the MXene / HNBR electrolyte obtained in Example 1 has a high elastic modulus of up to 0.18 GPa. Therefore, the MXene / HNBR electrolyte obtained in this embodiment of the invention has excellent mechanical properties by constructing a physical barrier.

[0064] Furthermore, the present invention also conducts puncture performance tests on the elastic electrolyte matrix HNBR and MXene / HNBR electrolyte obtained from Example 2, such as... Figure 12 As shown, by Figure 12 The puncture stress-strain curves show that the MXene / HNBR electrolyte obtained in Example 2 has high puncture strength. The puncture strength of the pure HNBR electrolyte is 34.18 gf, while that of the MXene / HNBR electrolyte is as high as 59.74 gf. This good puncture resistance can not only effectively block the penetration of lithium dendrites and reduce the risk of short circuits, but also resist external forces such as squeezing and collisions during the use, transportation and storage of the battery, providing reliable safety protection for the battery system.

[0065] Application Example 1 This application example uses the electrolytes obtained in Example 2, Comparative Example 1, and Comparative Example 2 to assemble lithium metal half-cells. The specific steps include: (1) Electrode preparation: Lithium metal sheets are cut into 10mm diameter discs as electrode sheets.

[0066] (2) Preparation of electrolytes: The electrolytes obtained in Example 2, Comparative Example 1 and Comparative Example 2 were used respectively.

[0067] (3) Battery assembly: The above materials are assembled into a CR2030 half-cell in the order of negative electrode shell, lithium sheet, electrolyte, gasket, spring sheet and positive electrode shell.

[0068] The electrochemical windows of the three types of half-cells were tested using linear sweep voltammetry, and the results are shown in Table 2.

[0069] Table 2 Electrochemical windows of half-cells As shown in Table 2, the electrochemical window obtained using Example 1 is the highest, reaching 4.3V.

[0070] Application Example 2 In this application example, lithium metal symmetric batteries are assembled using the MXene / HNBR electrolyte obtained in Example 2 and the elastic electrolyte substrate HNBR obtained in Example 2. The assembly method of the symmetric lithium metal battery is similar to that in Application Example 1, except that the battery is assembled in the following order: negative electrode shell, lithium sheet, electrolyte (the aforementioned MXene / HNBR electrolyte or elastic electrolyte substrate HNBR), lithium sheet, gasket, spring sheet, and positive electrode shell to form a CR2030 model symmetric battery.

[0071] Critical current density (CCD) tests and rate cycling performance tests at different current densities were conducted on the two types of symmetrical cells mentioned above. In the CCD tests, the current density was gradually increased by 0.1 mA / cm² per step. 2 With a fixed charge / discharge time of 0.5 hours, the current density ranged from 0.1 to 1.0 mA / cm² during rate cycling performance testing. 2 The fixed deposition capacity is 0.5 mA / cm³. 2 The test results are as follows Figure 13 and Figure 14 As shown.

[0072] Depend on Figure 13 It can be seen that the CCD value of the symmetric lithium metal battery using MXene / HNBR electrolyte is 1.5 mA / cm². 2 The CCD value is higher than that of symmetric lithium metal batteries using the elastic electrolyte matrix HNBR (0.9 mA / cm²). 2 The reason is that when the current density increases to 0.9 mA / cm², 2 At that time, the voltage curve of the HNBR symmetric lithium metal battery with a purely elastic electrolyte matrix collapsed and short-circuited, due to the formation of dead lithium and lithium dendrites at the interface; while the symmetric lithium metal battery with MXene / HNBR electrolyte could still operate stably at higher current densities without significant deterioration, exhibiting higher interface stability. This is because the abundant polar functional groups contained in the lithium-loving MXene can automatically regulate the distribution of Li⁺ at the interface, promoting uniform deposition and stripping of lithium metal; Depend on Figure 14 It can be seen that the symmetric lithium metal battery using MXene / HNBR electrolyte exhibits stable cycling characteristics at all tested current densities, and its polarization voltage is consistently lower than that of the symmetric lithium metal battery using the elastic electrolyte matrix HNBR; furthermore, when the current density decreases to 0.1 mA / cm², the polarization voltage remains stable. 2At that time, the polarization voltage of the symmetric lithium metal battery using the MXene / HNBR electrolyte was almost identical to the initial test value. Therefore, the MXene / HNBR electrolyte exhibits high interfacial stability and good lithium affinity.

[0073] Furthermore, the lithium metal symmetric cell obtained using the MXene / HNBR electrolyte achieved a speed of 0.1 mA / cm². 2 Constant current charge-discharge cycle tests were performed at current density, and the results are as follows: Figure 15 As shown, the cycle performance is 6000h.

[0074] Application Example 3 This application example uses the electrolytes obtained in Example 2 and Comparative Example 1 to assemble lithium metal full batteries. The specific steps include: (1) Electrode preparation: Lithium metal sheets were cut into 10mm diameter discs as negative electrodes, and commercial lithium iron phosphate electrode sheets were cut into 1mm discs as positive electrodes.

[0075] (2) Preparation of electrolytes: The electrolytes obtained in Example 2 and Comparative Example 1 were used respectively.

[0076] (3) Battery assembly: The above materials are assembled into a CR2030 model full battery in the order of negative electrode shell, lithium sheet, electrolyte, gasket, positive electrode, spring sheet and positive electrode shell.

[0077] Cyclic performance tests were conducted on the two types of full cells mentioned above, such as... Figure 16 As shown, the full cell using the electrolyte of Example 2 exhibited an initial capacity of 150.3 mAh / g under 0.5C conditions and remained stable for 600 cycles with a capacity retention rate as high as 96.3%. In contrast, the full cell using the electrolyte of Comparative Example 1 had an initial capacity of 149.3 mAh / g under the same conditions, and its discharge capacity showed a significant decline with increasing cycle number, with a capacity retention rate of only 12.3% after 600 cycles.

Claims

1. A lithiophilic elastic electrolyte, characterized in that, It includes: An elastic electrolyte matrix and an MXene-rich coating covering the surface of the electrolyte matrix; The elastic electrolyte matrix is ​​selected from at least one of natural rubber, nitrile rubber, hydrogenated nitrile rubber, silicone rubber, butyl rubber, and fluororubber. The MXene-rich coating is obtained by swelling an MXene film in a lithium salt plasticizer solution, wherein the MXene film is composed of MXene-coated microspheres and an adhesive. The preparation method of the lithiophilic elastic electrolyte includes the following steps: (1) Preparation of elastic electrolyte matrix; (2) Preparation of MXene-coated microspheres (MXene@microspheres), the steps include: ① A dispersion of MXene was prepared using a selective etching method; ② After adding the MXene dispersion to a positively charged cationic microsphere solution, electrostatic self-assembly is performed under stirring conditions, and MXene@microspheres are obtained after drying. (3) Prepare a dispersion of MXene@microspheres and adhesive and prepare an MXene coating on the surface of an elastic electrolyte matrix by spraying. Then place it on a glass plate for hot pressing. The pressure range of hot pressing is 10~1000MPa, the temperature range is 30~400℃, and the time range is 10~120min. The MXene coating is tightly bonded to the elastic matrix during the hot pressing process to form a film with an integrated structure. (4) The hot-pressed film obtained in step (3) is immersed in a lithium salt plasticizer solution and fully swollen to obtain the lithium-loving elastic electrolyte; the concentration range of the lithium salt plasticizer is 0.1~5 mol / L and the volume of the lithium salt plasticizer is 8~12 mL.

2. The lithiophilic elastic electrolyte according to claim 1, characterized in that, The MXene is selected from at least one of transition metal carbides, transition metal nitrides, and transition metal carbonitride ultrathin two-dimensional nanosheets; The surface of the microspheres carries a positive charge and is selected from at least one of polystyrene microspheres, polyvinyl chloride microspheres, silica microspheres, and titanium dioxide microspheres.

3. The lithium-loving elastic electrolyte according to claim 1, characterized in that, The adhesive is selected from at least one of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, poly(methyl methacrylate), polyacrylonitrile, polyvinyl alcohol, and polyvinylpyrrolidone.

4. The lithiophilic elastic electrolyte according to claim 1, characterized in that, The lithium salt is selected from at least one of LiTFSI, LiPF6, LiBF4, and LiClO4; the plasticizer is selected from at least one of ethylene glycol dimethyl ether, ethylene carbonate, dimethyl carbonate, diethyl carbonate (DEC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), and propylene carbonate.

5. The lithiophilic elastic electrolyte according to claim 1, characterized in that, The thickness of the MXene coating ranges from 100 to 10000 nm; the thickness of the elastic electrolyte matrix ranges from 20 to 1000 μm.

6. The lithiophilic elastic electrolyte according to claim 1, characterized in that, In step ②, the concentration of both the MXene dispersion and the microsphere solution is 1 mg / mL, and the volume ratio of the MXene dispersion to the microsphere solution is 10 mL:(80~120) mL.

7. The lithium-loving elastic electrolyte according to claim 1, characterized in that, In step (3), the mass ratio of MXene@microspheres to adhesive is 1:(0.02~10).

8. A solid-state lithium metal battery, characterized in that, It includes the lithium-loving elastic electrolyte as described in any one of claims 1 to 7.

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