Modified polyvinylidene fluoride-hexafluoropropylene composite ion gel polymer electrolyte doped with two-dimensional carbon material and preparation method and application thereof

Abstract

The invention belongs to the field of solid electrolyte technology, and specifically relates to a modified polyvinylidene fluoride-hexafluoropropylene composite ion gel polymer electrolyte doped with two-dimensional carbon materials, and its preparation method and application. The present invention realizes the modification of polyvinylidene fluoride-hexafluoropropylene-based ion gel electrolyte by doping with titanium carbide through a simple solution casting method. The introduction of two-dimensional carbon material doping simultaneously realizes the regulation of material structure and the construction of safety performance. The preparation of composite electrolytes for application in lithium metal batteries not only effectively improves the ionic conductivity and lithium ion transmission efficiency, but also ensures the cycle stability and safety of lithium metal batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid electrolytes, and specifically relates to a modified polyvinylidene fluoride-hexafluoropropylene composite ion gel polymer electrolyte doped with two-dimensional carbon materials, and a preparation method and application thereof. Background Art

[0002] With the development of mobile devices and new energy vehicles, energy storage systems have put forward higher requirements for energy density and safety. Among them, lithium metal is used as the anode material of future rechargeable batteries because of its light weight (0.53g cm -3 ), low standard reduction potential (-3.04V), and (3860mAh g -1 ) have attracted widespread attention due to their high theoretical storage capacity. However, several key challenges still hinder their practical application. Using traditional organic-based liquid electrolytes, their flammability and leakage can lead to serious safety threats. In addition, the uneven formation of lithium dendrites during lithium plating / stripping, mainly due to the uneven distribution of lithium ions on the lithium metal surface, leads to short circuits and limits the cycle life. The realization of high-safety lithium-based batteries requires more stable and safer electrolytes, among which non-flammable solid-state electrolytes are one of the most promising candidates.

[0003] Compared to liquid electrolytes, solid-state electrolytes offer several unique advantages, including thermal resistance, chemical and electrochemical stability, and mechanical robustness. Furthermore, solid-state electrolytes enable uniform and dispersed ion transport and lithium ion flux, making them ideal for dendrite-free lithium electrodeposition and long-term cycling stability. Therefore, replacing liquid electrolytes with solid-state electrolytes is considered a reasonable approach to address sustainability and safety concerns. However, solid-state electrolytes exhibit several inherent disadvantages, namely, large interfacial resistance, low ionic conductivity, and demanding processing capabilities. Therefore, the design of new solid-state electrolyte prototypes with high ionic conductivity, stable interfacial contact, and mechanical stability is urgently needed for next-generation solid-state lithium metal batteries. To overcome fabrication challenges and mitigate volume fluctuations, rigid ceramic particles were incorporated into readily processable polymer segments. To address the challenges of poor interfacial contact and low conductivity, ionic liquids with excellent flame resistance and high ionic conductivity were introduced as additives, exhibiting excellent wettability to the electrode. By rationally manipulating the decomposition of ionic liquid-based electrolytes, a well-defined solid electrolyte interphase with a high lithium fluoride content was constructed in situ. The lithium anode, covered by the lithium fluoride-rich solid electrolyte interphase, exhibited a uniform and smooth morphology, facilitating deposition during cycling. Based on the above considerations, the application of solid electrolytes involving ionic liquids is conducive to solving various problems existing in solid electrolytes and has great potential in lithium metal batteries with good cycle stability and operational safety. Summary of the Invention

[0004] In order to solve the problems and shortcomings of large interface resistance and low ionic conductivity of solid electrolytes, the present invention provides a modified polyvinylidene fluoride-hexafluoropropylene composite ion gel polymer electrolyte doped with two-dimensional carbon materials, and its preparation method and application. The present invention realizes the modification of polyvinylidene fluoride-hexafluoropropylene-based ion gel electrolyte by doping with titanium carbide through a simple solution casting method. The introduction of two-dimensional carbon material doping simultaneously realizes the regulation of material structure and the construction of safety performance. The preparation of composite electrolytes for application in lithium metal batteries not only effectively improves the ionic conductivity and lithium ion transmission efficiency, but also ensures the cycle stability and safety of lithium metal batteries.

[0005] A method for preparing a modified polyvinylidene fluoride-hexafluoropropylene composite ion gel polymer electrolyte doped with a two-dimensional carbon material comprises the following steps:

[0006] 1) dissolving an organic electrolyte lithium salt in an ionic liquid to obtain a transparent solution;

[0007] 2) uniformly dispersing the two-dimensional carbon material in a solvent to obtain a uniformly dispersed colloidal solution;

[0008] 3) adding the transparent solution obtained in step 1) and the polyvinylidene fluoride-hexafluoropropylene copolymer to the colloidal solution obtained in step 2) to obtain a uniform viscous solution, casting the solution onto a glass plate, and vacuum drying to obtain a composite ion gel polymer electrolyte.

[0009] Based on the above technical solution:

[0010] The above technical solution uses simple stirring ultrasound and solution casting methods to achieve the doping of two-dimensional carbon materials, thereby simultaneously achieving the regulation of material structure and the construction of safety performance, and realizing the doping of two-dimensional carbon materials into polyvinylidene fluoride-hexafluoropropylene networks. The three-dimensional porous polymer network designed by doping with two-dimensional carbon materials has the characteristics of high ionic conductivity, rapid lithium ion transport rate, and excellent thermal stability. At the same time, the introduction of synergistic ionic liquids achieves good wettability of the electrodes and constructs a solid electrolyte interphase layer with a high lithium fluoride content in situ.

[0011] The composite ion gel polymer electrolyte obtained by the above technical solution exhibits excellent electrochemical and safety properties, which not only improves the cycle stability of lithium metal batteries but also solves their existing safety hazards; the three-dimensional porous network structure formed by the introduction of two-dimensional carbon materials provides more ion transport channels, ensuring that the composite ion gel polymer electrolyte also has excellent ionic conductivity and lithium ion transport performance at room temperature; at the same time, the simple solution casting method avoids the problems of cumbersome and lengthy experimental steps, uneven distribution of two-dimensional carbon materials, and unstable polymer structure, thereby significantly improving the various performances of lithium metal batteries.

[0012] Specifically, in step 1), the organic electrolyte lithium salt includes but is not limited to: any one of lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate or lithium hexafluorophosphate.

[0013] Specifically, in step 1), the ionic liquid includes but is not limited to:

[0014] Quaternary ammonium bis(trifluoromethanesulfonyl)imide salts, such as trimethylbis(trifluoromethanesulfonyl)imide salt or tetramethylbis(trifluoromethanesulfonyl)imide salt;

[0015] Morpholine bis(trifluoromethanesulfonyl)imide salts, such as N-ethyl, methylmorpholine bis(trifluoromethanesulfonyl)imide salt, N-propyl, methylmorpholine bis(trifluoromethanesulfonyl)imide salt or N-butyl, methylmorpholine bis(trifluoromethanesulfonyl)imide salt;

[0016] Imidazole bis(trifluoromethanesulfonyl)imide salts, for example 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt or 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt;

[0017] Any one of the pyrrole bis(trifluoromethanesulfonyl)imide salts, such as 1-ethyl-3-methylpyrrole bis(trifluoromethanesulfonyl)imide salt, 1-propyl-3-methylpyrrole bis(trifluoromethanesulfonyl)imide salt, or 1-butyl-3-methylpyrrole bis(trifluoromethanesulfonyl)imide salt.

[0018] Specifically, in step 1), the concentration of the organic electrolyte lithium salt in the ionic liquid is 0.9-1.1M.

[0019] Specifically, in step 2), the two-dimensional carbon material includes but is not limited to: any one of a single layer or multilayer structure of niobium carbide, vanadium carbide, molybdenum carbide, and tantalum carbide.

[0020] The surface of two-dimensional carbon materials is rich in a variety of polar groups. After mixing, they form a porous structure through hydrogen bonding forces, and on the other hand, they utilize them to bind to cations in ionic liquids, so that only anions and lithium cations migrate in the polymer network.

[0021] Specifically, in step 2), the solvent includes but is not limited to: any one of N,N-dimethylformamide, tetrahydrofuran, or acetone.

[0022] Specifically, in step 2), the mass percentage concentration of the two-dimensional carbon material in the solvent is 0.5% to 1.5%.

[0023] Specifically, in step 3), the mass ratio of the ionic liquid to the polyvinylidene fluoride-hexafluoropropylene copolymer is 1:(1-3). Too high an amount of ionic liquid will result in too low a mechanical strength of the polymer, while too low an amount will result in suboptimal electrochemical performance.

[0024] Specifically, in step 3), the mass of the two-dimensional carbon material is 1% to 3% of the polyvinylidene fluoride-hexafluoropropylene copolymer. Adding too much of the two-dimensional carbon material can cause filler agglomeration and deposition, resulting in blockage and reduced electrochemical performance. Adding too little can result in suboptimal electrochemical performance.

[0025] Specifically, in step 3), the solution is uniformly dispersed by ultrasound or vigorous stirring, the vacuum drying reaction temperature is 60-80° C., and the reaction time is 12 h to 24 h.

[0026] The present invention also provides a composite ion gel polymer electrolyte prepared according to the above preparation method.

[0027] The present invention also provides applications of the composite ion gel polymer electrolyte for preparing lithium metal batteries, lithium sulfur batteries, or supercapacitors. It can also be used in conjunction with corresponding organic electrolyte sodium salts to prepare sodium metal batteries.

[0028] The present invention also provides an application of the composite ion gel polymer electrolyte as a solid-state lithium metal battery electrolyte.

[0029] The present invention has the following advantages and positive effects:

[0030] 1. The present invention uses a simple stirring ultrasound and solution casting method to evenly disperse the two-dimensional carbon material and ionic liquid into the polyvinylidene fluoride-hexafluoropropylene polymer network without the use of other additives, thus solving the problems of high interface resistance of solid electrolytes and low ionic conductivity at room temperature;

[0031] 2. The present invention introduces two-dimensional carbon materials. On the one hand, it realizes the influence of titanium carbide on the polyvinylidene fluoride-hexafluoropropylene polymer network, obtains a three-dimensional porous network structure, and ensures the transmission channel of lithium ions in long cycles; on the other hand, it promotes the separation of bis(trifluoromethanesulfonyl)imide anions in the ionic liquid. Through the reduction and decomposition of free bis(trifluoromethanesulfonyl)imide salt anions, a lithium fluoride-rich solid electrolyte phase layer is formed in situ, which can effectively inhibit the growth of lithium dendrites and promote the cycle stability of the battery.

[0032] 3. The highly thermally conductive two-dimensional carbon material of the present invention forms a dense oxide / carbon layer at high temperatures, and the introduced ionic liquid makes the composite ion gel electrolyte flame retardant, which can prevent overheating, short circuits and mechanical damage, effectively ensuring the safety of lithium metal batteries;

[0033] 4. The preparation process of the present invention is simple, does not require lengthy and complicated experimental steps, has the characteristics of mild conditions, controllable process and high universality, and is easy to achieve industrial mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A scanning electron microscope image showing the composite solid electrolyte in Example 1 of the present invention;

[0035] Figure 2 Fourier transform infrared spectra of the composite solid electrolyte in Example 1 of the present invention, and the ion gel and titanium carbide in Comparative Example 1;

[0036] Figure 3 The thermogravimetric analysis spectrum and differential scanning calorimetry analysis spectrum of the composite solid electrolyte in Example 1 of the present invention and the ion gel in Comparative Example 1 are shown;

[0037] Figure 4 A graph showing the combustion performance test of the composite solid electrolyte and the commercial polypropylene separator in Example 1 of the present invention;

[0038] Figure 5 The impedance spectrum and linear sweep voltammetry curve of the composite solid electrolyte in Example 1 of the present invention and the impedance spectrum of the ion gel in Comparative Example 1 are shown;

[0039] Figure 6 A comparison chart showing the lithium ion transference numbers of the composite solid electrolyte in Example 1 of the present invention and the ion gel in Comparative Example 1;

[0040] Figure 7 A graph showing the capacity decay of the composite solid electrolyte in Example 1 of the present invention and the ion gel in Comparative Example 1 after 200 cycles;

[0041] Figure 8 Graphs showing the mechanical properties of the composite solid electrolyte in Example 1 of the present invention and the ion gel in Comparative Example 1.

[0042] Figure 9 The X-ray photoelectron spectrum of the surface F1s of the composite solid electrolyte after long-term cycling in Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0043] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0044] Example 1

[0045] This embodiment describes in detail a modified polyvinylidene fluoride-hexafluoropropylene composite ion gel polymer electrolyte doped with a two-dimensional carbon material (hereinafter referred to as a composite solid electrolyte) and a preparation method thereof, including the following steps:

[0046] 6 mg of titanium carbide was dissolved in 6 g of N,N-dimethylformamide and ultrasonically formed into a uniform colloidal solution; then 1.15 g of lithium bis(trifluoromethanesulfonyl)imide was added to 4 mL of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and ultrasonically obtained a uniform clear solution; 0.6 g of polyvinylidene fluoride-hexafluoropropylene and 1.2 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt solution were added to the titanium carbide N,N-dimethylformamide solution, stirred until a viscous solution was formed, and then spread on a glass plate and dried in a vacuum drying oven at 60°C for 24 hours to finally obtain a composite solid electrolyte.

[0047] The scanning electron microscope image of the composite solid electrolyte prepared in this Example 1 is as follows Figure 1 As shown, it can be clearly seen that the composite solid electrolyte presents a three-dimensional porous network structure;

[0048] The Fourier transform infrared spectra of the composite solid electrolyte and titanium carbide prepared in this Example 1 are as follows: Figure 2 As shown, the characteristic peaks of titanium carbide correspond to polar groups such as OH, C=O, CF, and CO, at 1072, 1180 cm -1 The vibration band at corresponds to the symmetric stretching of CF2. The interaction between the PVDF-HFP matrix and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide leads to the shift of the characteristic peaks in the composite solid electrolyte, indicating the successful and uniform mixing of PVDF-HFP, ionic liquid and titanium carbide.

[0049] The thermogravimetric analysis spectrum and differential scanning calorimetry analysis spectrum of the composite solid electrolyte prepared in this Example 1 are as follows: Figure 3 As shown, the thermal stability temperature of the composite solid electrolyte is 350℃ (as shown in Figure 3 a), the glass transition temperature is 124.6℃ (e.g. Figure 3 b, this obvious glass transition temperature can be used to determine that it is a solid electrolyte), indicating that the introduction of titanium carbide will transform polyvinylidene fluoride from a non-polar α phase to a polar β phase. The β-phase polyvinylidene fluoride can provide a stronger dipole moment and produce better electrical interaction with the ionic liquid, thereby increasing the melting temperature of the composite solid electrolyte;

[0050] The combustion performance test diagram of the composite solid electrolyte and commercial polypropylene separator prepared in this Example 1 is as follows: Figure 4 As shown in the figure, the commercial polypropylene separator shrinks severely and burns in an open flame, while the composite solid electrolyte has no obvious deformation, indicating that the composite solid electrolyte has good flame retardancy.

[0051] The linear sweep voltammetry curve of the composite solid electrolyte prepared in Example 1 is as follows: Figure 5As shown in b, the electrochemical stability window of the composite solid electrolyte is 4.7 V, indicating that the composite solid electrolyte provides a basis for the application of various cathode materials in lithium metal batteries;

[0052] The impedance spectrum obtained by assembling a stainless steel symmetrical battery with a composite solid electrolyte in Example 1 is as follows Figure 5 As shown in a, through the formula The ionic conductivity of the composite solid electrolyte was calculated to be 1.54×10 -3 S cm -1 , where R is the resistance of the composite solid electrolyte obtained from the impedance spectrum (i.e., the intercept on the x-axis), L is the thickness of the composite solid electrolyte, and S is the contact area between the stainless steel electrode and the electrolyte. This indicates that the porous network structure formed after the introduction of titanium carbide provides more ion transport channels.

[0053] The lithium ion migration number of the button-type lithium symmetric battery (CR2032) assembled with the composite solid electrolyte in this Example 1 is shown in the figure Figure 6 As shown in a, through the formula The calculated lithium ion transference number of the composite solid electrolyte is 0.67, where ΔV is the applied polarization voltage (ΔV = 10 mV), I0 and I S are the initial current and steady-state current, R0 and R S is the initial resistance and steady-state resistance, indicating that the introduction of titanium carbide enhances charge transport and improves the transmission efficiency of lithium ions. At the same time, the introduction of ionic liquid also reduces the interface resistance. The higher lithium ion transfer number can reduce lithium deposition and inhibit the growth of lithium dendrites, making the composite solid electrolyte have better electrochemical stability.

[0054] The capacity decay of the lithium iron phosphate button battery (CR2032) assembled with the composite solid electrolyte in Example 1 after 200 cycles is shown in the figure. Figure 7 As shown in Figure 2, the maximum discharge capacity of the composite solid electrolyte button battery can reach 151 mAh g -1 , and it can maintain 97.8% of its capacity after 200 cycles, indicating that the composite solid electrolyte button battery has excellent capacity retention rate, which provides the possibility for the realization of stable lithium metal batteries.

[0055] In this embodiment 1, a button-type lithium symmetrical battery (CR2032) assembled with a composite solid electrolyte was subjected to a long-cycle stability performance test. Under the test conditions of fixed current density and fixed area capacity, the composite solid electrolyte lithium symmetrical battery can perform long-term stable lithium plating / stripping performance, and presents a smooth voltage curve with almost no obvious voltage fluctuation, indicating that the composite solid electrolyte has good electrochemical stability, laying a solid foundation for achieving long-cycle stability of lithium metal batteries. At the same time, after the cycle is completed, the button-type lithium symmetrical battery is disassembled, and the chemical element composition of the SEI layer formed on the surface of the composite solid electrolyte is tested by X-ray photoelectron spectroscopy. It can be clearly seen through Figure 9 It can be seen that the SEI layer contains LiF. A simple comparison of the peak areas confirms that the SEI layer has a higher content of LiF.

[0056] Example 2

[0057] This embodiment describes in detail a modified polyvinylidene fluoride-hexafluoropropylene composite ion gel polymer electrolyte doped with a two-dimensional carbon material (hereinafter referred to as a composite solid electrolyte) and a preparation method thereof, including the following steps:

[0058] 6 mg of titanium carbide was dissolved in 6 g of N,N-dimethylformamide and ultrasonically formed into a uniform colloidal solution; then 1.15 g of lithium bis(trifluoromethanesulfonyl)imide was added to 4 mL of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and ultrasonically obtained a uniform and clear solution; 0.6 g of polyvinylidene fluoride-hexafluoropropylene and 0.6 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt solution were added to the titanium carbide N,N-dimethylformamide solution, stirred until a viscous solution was formed, and then spread on a glass plate and dried in a vacuum drying oven at 80°C for 12 hours to finally obtain a composite solid electrolyte.

[0059] Example 3

[0060] This embodiment describes in detail a modified polyvinylidene fluoride-hexafluoropropylene composite ion gel polymer electrolyte doped with a two-dimensional carbon material (hereinafter referred to as a composite solid electrolyte) and a preparation method thereof, including the following steps:

[0061] 12 mg of titanium carbide was dissolved in 6 g of N,N-dimethylformamide and ultrasonically formed into a uniform colloidal solution; then 1.15 g of lithium bis(trifluoromethanesulfonyl)imide was added to 4 mL of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and ultrasonically obtained a uniform and clear solution; 0.6 g of polyvinylidene fluoride-hexafluoropropylene and 1.2 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt solution were added to the titanium carbide N,N-dimethylformamide solution, stirred until a viscous solution was obtained, and then spread on a glass plate and dried in a vacuum drying oven at 80°C for 12 hours to finally obtain a composite solid electrolyte.

[0062] Example 4

[0063] This embodiment describes in detail a modified polyvinylidene fluoride-hexafluoropropylene composite ion gel polymer electrolyte doped with a two-dimensional carbon material (hereinafter referred to as a composite solid electrolyte) and a preparation method thereof, including the following steps:

[0064] 3 mg of titanium carbide was dissolved in 6 g of N,N-dimethylformamide and ultrasonically formed into a uniform colloidal solution; then 1.15 g of lithium bis(trifluoromethanesulfonyl)imide was added to 4 mL of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and ultrasonically obtained a uniform clear solution; 0.6 g of polyvinylidene fluoride-hexafluoropropylene and 0.6 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt solution were added to the titanium carbide N,N-dimethylformamide solution, stirred until a viscous solution was formed, and then spread on a glass plate and dried in a vacuum drying oven at 60°C for 24 hours to finally obtain a composite solid electrolyte.

[0065] Comparative Example 1

[0066] In this comparative example, no two-dimensional carbon material is added, and the preparation method of the electrolyte includes the following steps:

[0067] 1.15 g of lithium bis(trifluoromethanesulfonyl)imide was added to 4 mL of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and ultrasonically obtained a uniform and clear solution; 0.6 g of polyvinylidene fluoride-hexafluoropropylene and 1.2 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt solution were added to the N,N-dimethylformamide solution, stirred until a viscous solution was formed, and then spread on a glass plate and dried in a vacuum drying oven at 80°C for 12 h to finally obtain a comparative example composite solid electrolyte.

[0068] The Fourier transform infrared spectrum of the ion gel prepared in this comparative example 1 is as follows Figure 2 As shown, at 776 and 1402 cm -1 The characteristic peak at 835 cm-1 was assigned to the α-phase crystal of polyvinylidene fluoride-hexafluoropropylene, while the peak at 835 cm-1 was assigned to the α-phase crystal of polyvinylidene fluoride-hexafluoropropylene. -1 The band at is amorphous phase, indicating that the addition of ionic liquid will not change the structure of polyvinylidene fluoride-hexafluoropropylene polymer network; the thermogravimetric analysis spectrum and differential scanning calorimetry analysis spectrum of ion gel are shown in Figure 2. Figure 3 As shown, the thermal stability temperature of the comparative composite solid electrolyte is 320°C (as shown in FIG. Figure 3 a), the glass transition temperature is 107.8℃ (e.g. Figure 3 b); The impedance spectrum obtained by assembling a stainless steel symmetrical battery with ion gel is shown in Figure 5 As shown in a, through the formula The ionic conductivity of the composite solid electrolyte was calculated to be 5.1×10-4 Scm -1 , where R is the resistance of the composite solid electrolyte obtained from the impedance spectrum (i.e., the intercept on the x-axis), L is the thickness of the composite solid electrolyte, and S is the contact area between the stainless steel electrode and the electrolyte; the lithium ion migration number of the button-type lithium symmetric battery (CR2032) assembled with ion gel is shown in the figure. Figure 6 As shown in b, through the formula The calculated lithium ion transference number of the ion gel is 0.45, where ΔV is the applied polarization voltage (ΔV = 10 mV), I0 and I S are the initial current and steady-state current, R0 and R S is the initial resistance and steady-state resistance; the capacity decay of the lithium iron phosphate button battery (CR2032) assembled with ion gel after 200 cycles is shown in the figure Figure 7 As shown in Figure 2, the maximum discharge capacity of the composite solid electrolyte button battery can reach 148.4 mAh g -1 , and can maintain 94.6% of its capacity after 200 cycles.

[0069] The above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a modified polyvinylidene fluoride-hexafluoropropylene composite ion gel polymer electrolyte doped with a two-dimensional carbon material, characterized in that: The specific steps are as follows: 1) dissolving the organic electrolyte lithium bis(trifluoromethanesulfonyl)imide in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt to obtain a transparent solution; 2) uniformly dispersing the two-dimensional carbon material titanium carbide in a solvent N,N-dimethylformamide to obtain a uniformly dispersed colloidal solution, wherein the weight percentage concentration of titanium carbide in the solvent is 0.5% to 1.5%; 3) adding the transparent solution obtained in step 1) and the polyvinylidene fluoride-hexafluoropropylene copolymer to the colloidal solution obtained in step 2) to obtain a uniform viscous solution, casting the solution onto a glass plate, and vacuum drying the reaction to obtain a composite ion gel polymer electrolyte, wherein the mass of titanium carbide is 1% to 3% of the polyvinylidene fluoride-hexafluoropropylene copolymer.

2. The preparation method according to claim 1, wherein: In step 1), the concentration of the organic electrolyte lithium salt in the ionic liquid is 0.9-1.1 M.

3. The preparation method according to claim 1, wherein: In step 3), the mass ratio of the ionic liquid to the polyvinylidene fluoride-hexafluoropropylene copolymer in the transparent solution is 1:(1-3).

4. The preparation method according to claim 1, characterized in that In step 3), the solution is uniformly dispersed by ultrasound or vigorous stirring, the temperature of the vacuum drying reaction is 60-80° C., and the time of the vacuum drying reaction is 12 h to 24 h. 5 . A composite ion gel polymer electrolyte prepared according to the preparation method according to any one of claims 1 to 4 .

6. An application of the composite ion gel polymer electrolyte according to claim 5, characterized in that: Used to prepare lithium metal batteries, lithium sulfur batteries, sodium metal batteries or supercapacitors.

7. The use of the composite ion gel polymer electrolyte according to claim 6, characterized in that: As a solid-state lithium metal battery electrolyte.

Images