Composite solid-state polymer electrolyte and preparation method and application thereof

Abstract

The application discloses a kind of composite solid-state polymer electrolyte and preparation method and application thereof.A kind of composite solid-state polymer electrolyte, preparation raw material includes trifluoromethanesulfonylimide lithium, polyvinylidene fluoride-hexafluoropropylene and modified cellulose derivative;Modified cellulose derivative is obtained by modification of organic modifier to cellulose derivative;Organic modifier includes at least one of N, N-dimethylformamide, dimethyl sulfoxide, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane.The composite solid-state polymer electrolyte of the application has high ionic conductivity, wide electrochemical window, excellent cycle performance of solid-state polymer electrolyte, and the highest stable value of electrochemical window can reach 4.8V.The interaction between modified cellulose derivative and LiTFSI, PVDF-HFP is stronger under high salt system, and the obtained system has higher electrochemical stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a composite solid-state polymer electrolyte and a preparation method and application thereof. BACKGROUND

[0002] Lithium metal has extremely high theoretical capacity and the lowest redox potential, and is considered to be a promising anode in the next generation of high-energy batteries. However, the reaction between the liquid electrolyte and lithium metal often causes battery failure, and the growth of Li dendrites during the use of the battery also causes short circuits of the battery, which poses a fire risk. In order to solve these problems, solid-state electrolytes are considered to be an ideal substitute for liquid electrolytes due to their inherent safety features and potential to prevent Li dendrite deposition and structural damage to the lithium anode. However, solid-state electrolytes have the problem of excessive interface impedance. The solid-state electrolyte and the electrode material exist in a solid state, so the effective contact between the electrode and the electrolyte is weak, and the ion transmission dynamics in the solid substance is low, which causes the problem of excessive interface impedance. High-salt polymer electrolytes based on polymers can effectively solve the above problems and have attracted widespread attention due to their excellent performance in various aspects. At present, the composite solid-state electrolyte in the high-salt system has good ionic conductivity at room temperature, but can only meet the needs of part of the use scenarios, and how to further improve the ionic conductivity is still the focus of research. SUMMARY

[0003] In order to further improve the ionic conductivity of the composite solid-state electrolyte, the purpose of the present application is to provide a composite solid-state polymer electrolyte, the second purpose of the present application is to provide a preparation method of the composite solid-state polymer electrolyte, and the third purpose of the present application is to provide an application of the composite solid-state polymer electrolyte.

[0004] In order to achieve the above-mentioned purposes, the technical scheme adopted by the present application is:

[0005] The first aspect of the present application provides a composite solid-state polymer electrolyte, and the preparation raw materials of the composite solid-state polymer electrolyte include lithium trifluoromethanesulfonimide, polyvinylidene fluoride-hexafluoropropylene and a modified cellulose derivative.

[0006] The modified cellulose derivative is obtained by modifying a cellulose derivative with an organic modifier; the organic modifier includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and 1,2-dimethoxyethane.

[0007] In the present application, the modified cellulose derivative is obtained by soaking and dissolving modification of the cellulose derivative with the organic modifier.

[0008] Preferably, in the composite solid-state polymer electrolyte, the cellulose derivative in the modified cellulose derivative includes at least one of methyl cellulose, cellulose acetate, cellulose acetate propionate, carboxymethyl cellulose, ethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose; further preferably, the cellulose derivative includes at least one of cellulose acetate, cellulose acetate propionate, ethyl cellulose and hydroxypropyl methyl cellulose.

[0009] Preferably, in the composite solid-state polymer electrolyte, the mass of the modified cellulose derivative is 1-20% of the mass of lithium trifluoromethanesulfonimide; further preferably, the mass of the modified cellulose derivative is 5-15% of the mass of lithium trifluoromethanesulfonimide; and still further preferably, the mass of the modified cellulose derivative is 8-12% of the mass of lithium trifluoromethanesulfonimide.

[0010] Preferably, in the composite solid-state polymer electrolyte, the mass ratio of lithium trifluoromethanesulfonimide to polyvinylidene hexafluoropropylene is 1:(0.5-2.5); further preferably, the mass ratio of lithium trifluoromethanesulfonimide to polyvinylidene hexafluoropropylene is 1:(0.6-2); and still further preferably, the mass ratio of lithium trifluoromethanesulfonimide to polyvinylidene hexafluoropropylene is 1:(0.8-1.5).

[0011] Preferably, the composite solid-state polymer electrolyte has a sheet structure and a thickness of 90-115 μm; further preferably, the thickness is 95-110 μm; and still further preferably, the thickness is 100-105 μm.

[0012] The second aspect of the present application provides a preparation method of the composite solid-state polymer electrolyte, comprising the following steps:

[0013] (1) mixing and dissolving lithium trifluoromethanesulfonimide and polyvinylidene hexafluoropropylene in a solvent to obtain a mixed solution 1;

[0014] (2) mixing and stirring a cellulose derivative and an organic modifier to obtain a mixed solution 2;

[0015] (3) mixing and stirring the mixed solution 1 and the mixed solution 2, then scraping and coating into a film, and shaping to obtain the composite solid-state polymer electrolyte.

[0016] The preparation method of the composite solid-state polymer electrolyte can interchange the order of step (1) and step (2).

[0017] In the present application, the ion conductivity can be effectively improved after adding the modified cellulose derivative, and the ion conductivity is increased for the following reasons: (1) lithium trifluoromethanesulfonimide (LiTFSI) and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) will lose hydrogen fluoride to form a long chain of polymer in the solvent system. The hydroxyl group on the modified cellulose derivative will form a hydrogen bond with the fluorine atom on the long chain. Due to the hydrogen bond effect, the modified cellulose derivative is bound near the long chain of polymer. And the hydroxyl group at the other end of the modified cellulose derivative will combine with TFSI - The ion clusters make them arrange closely, thereby forming a long-range ordered flow anion skeleton, providing new Li + transport channels; (2) due to the plasticizing effect of the organic modifier, the bond length between atoms in the modified cellulose derivative is elongated, so that the crystallinity of the modified cellulose derivative after pre-dispersion in the organic modifier is effectively reduced, at the same time, the stretching of the bond length between the carbonyl oxygen and the adjacent oxygen in the modified cellulose derivative makes both oxygen atoms fully exposed to the outside system, providing new hopping sites for Li + . That is, while the overall crystallinity of the system is reduced, two new ion transport channels are also formed, so that the ion conductivity is effectively improved.

[0018] Preferably, in the preparation method of the composite solid-state polymer electrolyte, in step (1), the solvent includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and 1,2-dimethoxyethane.

[0019] Preferably, in the preparation method of the composite solid-state polymer electrolyte, in step (1), lithium trifluoromethanesulfonimide and polyvinylidene fluoride-hexafluoropropylene are mixed and dissolved in the solvent, and then stirred for 2-4 h to obtain a mixed solution 1.

[0020] Further preferably, in step (1), after lithium trifluoromethanesulfonimide and polyvinylidene fluoride-hexafluoropropylene are mixed and dissolved in the solvent, stirring is carried out at 50-70°C for 2-4 h to obtain the mixed solution 1; and further preferably, in step (1), after lithium trifluoromethanesulfonimide and polyvinylidene fluoride-hexafluoropropylene are mixed and dissolved in the solvent, stirring is carried out at 55-65°C for 2.5-3.5 h to obtain the mixed solution 1.

[0021] Preferably, in the preparation method of the composite solid-state polymer electrolyte, in step (2), after the cellulose derivative is mixed with the organic modifier, stirring is carried out for 2-4 h to obtain a mixed solution 2.

[0022] Further preferably, in step (2), after the cellulose derivative is mixed with the organic modifier, the mixture is stirred at 50-70℃ for 2-4h to obtain the mixed solution 2; further more preferably, in step (2), after the cellulose derivative is mixed with the organic modifier, the mixture is stirred at 55-65℃ for 2.5-3.5h to obtain the mixed solution 2.

[0023] Preferably, in the preparation method of the composite solid-state polymer electrolyte, in step (3), after the mixed solution 1 and the mixed solution 2 are mixed, the mixture is stirred for 2-4h.

[0024] Further preferably, in step (3), after the mixed solution 1 and the mixed solution 2 are mixed, the mixture is stirred at 50-70℃ for 2-4h; further more preferably, in step (3), after the mixed solution 1 and the mixed solution 2 are mixed, the mixture is stirred at 55-65℃ for 2.5-3.5h.

[0025] Preferably, in the preparation method of the composite solid-state polymer electrolyte, in step (3), after the mixed solution 1 and the mixed solution 2 are mixed, the mixture is stirred at 50-70℃ for 2-4h; further more preferably, in step (3), after the mixed solution 1 and the mixed solution 2 are mixed, the mixture is stirred at 55-65℃ for 2.5-3.5h.

[0026] The third aspect of the present application provides the use of the composite solid-state polymer electrolyte in the preparation of a lithium battery.

[0027] The present application has the following beneficial effects:

[0028] The composite solid-state polymer electrolyte of the present application has high ionic conductivity. Firstly, in a high salt system, the cation / anion association is enhanced, which can form a unique and fast ion transport channel and ion transport network. Secondly, after the cellulose derivative is modified, the bond length of the cellulose derivative is stretched. After the modified cellulose derivative is added, the modified cellulose derivative can interact with the anion of LiTFSI, promote the dissociation of LiTFSI, and increase the content of Li ions; the hydroxyl group of the modified cellulose derivative interacts with the F atom of PVDF-HFP to form a hydrogen bond, which reduces the crystallinity of PVDF-HFP, thereby creating more new ion transport pathways and obtaining very high ionic conductivity.

[0029] The composite solid-state polymer electrolyte of the present application has a wide electrochemical window when used in a lithium battery, and the stable value of the electrochemical window can reach 4.8V. The interaction between the modified cellulose derivative, LiTFSI and PVDF-HFP is stronger in a high salt system, and the obtained system has higher electrochemical stability.

[0030] The composite solid-state polymer electrolyte of the application has excellent cycle performance, the discharge specific capacity of the battery assembled by the modified cellulose derivative solid-state electrolyte is maintained at 160.5 mAh / g, the capacity retention rate is 96%, the electrolyte contacts with Li electrode and LiFePO4 electrode to form a stable interface layer, so that the discharge specific capacity is stable during the cycle process.

[0031] The application uses cellulose derivatives as fillers, which are biodegradable, environment-friendly, non-toxic, and meet the current concept of green chemistry. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Impedance spectrum of the electrolyte membrane prepared for Example 1.

[0033] Figure 2 Impedance spectrum of the electrolyte membrane prepared for Example 2.

[0034] Figure 3 Impedance spectrum of the electrolyte membrane prepared for Example 3.

[0035] Figure 4 LSV graph of the electrolyte membrane prepared for Example 1.

[0036] Figure 5 LSV graph of the electrolyte membrane prepared for Example 2.

[0037] Figure 6 LSV graph of the electrolyte membrane prepared for Example 3.

[0038] Figure 7 Cycle specific capacity graph of the electrolyte membrane prepared for Example 1.

[0039] Figure 8 Cycle specific capacity graph of the electrolyte membrane prepared for Example 2.

[0040] Figure 9 Cycle specific capacity graph of the electrolyte membrane prepared for Example 3. DETAILED DESCRIPTION

[0041] The technical solutions in the examples of the application will be described clearly and completely below. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0042] Example 1

[0043] This embodiment provides a preparation method of a composite solid-state polymer electrolyte membrane, and a pre-mixed composite hydroxypropyl methyl cellulose high-salt solid-state electrolyte membrane is prepared, and the specific process is as follows:

[0044] (1) Take 1.250 g of DMF and 0.330 g of LiTFSI in a small bottle, and after the LiTFSI is dissolved by slight shaking, add 0.300 g of PVDF-HFP.

[0045] (2) Take another bottle and weigh 0.500 g of DMF and a certain mass fraction of hydroxypropyl methyl cellulose (hydroxypropyl methyl cellulose / PVDF-HFP = 10%), and pre-mix the hydroxypropyl methyl cellulose with the DMF.

[0046] (3) Place the two bottles of solution in a 60°C water bath and stir for 3 h, and after the pre-dispersion is completed, mix the two bottles of solution and continue to stir in a 60°C water bath for 3 h.

[0047] (4) After the above mixed solution is uniformly mixed, place it in a glove box, vacuumize and degas, and then pour it on a clean glass plate, and use a 400 μm high stainless steel scraper to scrape and coat a film. Then immediately place the glass plate and the liquid film together in a constant temperature and humidity chamber at 25°C and 80% humidity for 3 h to obtain a preliminarily shaped electrolyte film.

[0048] (5) After the above film is peeled off from the glass plate, it is placed in a 60°C vacuum drying box for 24 h to remove the residual solvent, and an electrolyte film with a thickness of about 100 μm is obtained.

[0049] Example 2

[0050] The present embodiment provides a preparation method of a composite solid-state polymer electrolyte film, and a high-salt solid-state electrolyte film is prepared, and the specific process is as follows:

[0051] (1) Take 1.500 g of DMF and 0.330 g of LiTFSI in a small bottle, and after the LiTFSI is dissolved by slight shaking, add 0.300 g of PVDF-HFP to obtain a mixed solution.

[0052] (2) Place the solution in a 60°C water bath and stir for 3 h.

[0053] (3) After the stirring is completed, place it in a glove box, vacuumize and degas, and then pour it on a clean glass plate, and use a 400 μm high stainless steel scraper to scrape and coat a film. Then immediately place the glass plate and the liquid film together in a constant temperature and humidity chamber at 25°C and 80% humidity for 3 h to obtain a preliminarily shaped electrolyte film.

[0054] (4) After the above film is peeled off from the glass plate, it is placed in a 60°C vacuum drying box for 24 h to remove the residual solvent, and an electrolyte film with a thickness of about 100 μm is obtained.

[0055] Example 3

[0056] The embodiment provides a preparation method of a composite solid-state polymer electrolyte film, and a low-salt cellulose acetate propionate electrolyte film is prepared through the method, and the specific process is as follows:

[0057] (1) 1.0 g of PVDF-HFP is dissolved in 9 mL of NMP (N-methyl pyrrolidone) to obtain a mixed solution.

[0058] (2) The solution is stirred for 2 h under a 50°C water bath to obtain a uniform solution.

[0059] (3) Cellulose acetate propionate (CAP) is dissolved in the solution (CAP / PVDF-HFP=20%).

[0060] (4) 0.4 g of LiTFSI is mixed with the solution.

[0061] (5) The solution is stirred for 8 h under a 50°C water bath.

[0062] (6) The mixed precursor is laid on a polytetrafluoroethylene culture dish and vacuum dried at 80°C for 8 h to obtain a low-salt cellulose acetate propionate electrolyte.

[0063] Example 4

[0064] The embodiment provides a preparation method of a composite solid-state polymer electrolyte film, and a pre-mixed composite cellulose acetate high-salt solid-state electrolyte film is prepared through the method, and the specific process is as follows:

[0065] (1) 1.250 g of DMF and 0.330 g of LiTFSI are respectively weighed in a vial, and 0.300 g of PVDF-HFP is added after the LiTFSI is dissolved by slight shaking.

[0066] (2) Another vial is used to weigh 0.500 g of DMF and a certain mass fraction of cellulose acetate (cellulose acetate / PVDF-HFP=10%, 20%, 30%), and the cellulose acetate is pre-mixed with the DMF.

[0067] (3) The two solutions are placed in a 60°C water bath and stirred for 3 h, and after the pre-dispersion is completed, the two solutions are mixed and continuously stirred in a 60°C water bath for 3 h.

[0068] (4) After the mixed solution is uniformly mixed, it is placed in a glove box, vacuumized and degassed, and then poured on a clean glass plate to form a film by using a 400 μm high stainless steel scraper. Subsequently, the glass plate and the liquid film are immediately placed in a constant temperature and humidity box with a temperature of 25°C and a humidity of 80% for 3 h to obtain a preliminarily shaped electrolyte film.

[0069] (5) The film was peeled off from the glass plate and placed in a vacuum drying oven at 60°C for 24 h to remove the residual solvent, obtaining an electrolyte film with a thickness of about 100 μm.

[0070] Performance test:

[0071] 1. LiFeP04electrode was used as cathode, and lithium ion battery for ion alternating current impedance spectrum test (lithium ion conductivity) was assembled according to the sequence of cathode shell, spring, gasket, solid electrolyte film, gasket, anode shell. At room temperature, CHI660E type electrochemical workstation was used for alternating current impedance spectrum test, the frequency of alternating current impedance spectrum test was 106Hz, and the amplitude was 5mV; the impedance spectrum of the electrolyte film prepared in Example 1-3 was shown in Figures 1-3

[0072] 2. Lithium ion battery for measuring electrochemical window was assembled according to the sequence of cathode shell, spring, gasket, solid electrolyte film, lithium sheet, anode shell. At room temperature, CHI660E type electrochemical workstation was used for LSV, the voltage range of LSV test (electrochemical window) was 2V-5.5V, and the scanning speed was 0.1mV / s; the LSV graph of the electrolyte film prepared in Example 1-3 was shown in Figures 4-6

[0073] 3. Lithium ion battery for measuring cycle performance was assembled according to the sequence of cathode shell, spring, gasket, solid electrolyte film, lithium sheet, anode shell. All the batteries were pressed under the press machine with a pressure of 50N. At room temperature, blue-dye battery test system was used for cycle performance test of the batteries, the voltage for testing cycle performance of the batteries was 2.5V-3.5V, and the current was 0.2C; the cycle specific capacity graph of the electrolyte film prepared in Example 1-3 was shown in Figures 7-9

[0074] The performance test data of Example 1-3 was shown in Table 1; the performance test data of different cellulose acetate addition amounts in Example 4 was shown in Table 2.

[0075] Table 1

[0076]

[0077] Table 2

[0078]

[0079]

[0080] As shown in Table 1, at room temperature, the ion conductivity of Example 1 was high, the ion conductivity of the pre-mixed cellulose derivative solid electrolyte at room temperature 25°C was as high as 4.33×10 -4 S cm -1 ​​​This is because, first, in the high salt system, the cation / anion association is enhanced, which can form a unique, fast ion transport channel and ion transport network; second, the cellulose derivative is mixed with the organic solvent, which stretches the bond length of the cellulose derivative, and after the addition of the cellulose derivative, the cellulose derivative can interact with the anion of LiTFSI to promote the dissociation of LiTFSI and increase the content of Li ions; the hydroxyl group of the cellulose derivative interacts with the F atom of PVDF-HFP to form a hydrogen bond, which reduces the crystallinity of PVDF-HFP, thereby creating more new ion transport pathways, and a very high ionic conductivity solid-state polymer electrolyte is obtained.

[0081] The electrochemical window of Example 1 is wide, and the electrochemical window of the pre-mixed cellulose derivative solid-state electrolyte is as high as 4.8V. The interaction between the pre-mixed cellulose derivative and LiTFSI, PVDF-HFP is stronger in the high salt system, and the electrochemical stability of the obtained system is higher.

[0082] The cycle performance of Example 1 is excellent, and the discharge specific capacity of the battery assembled by the pre-mixed cellulose derivative solid-state electrolyte is maintained at 160.5mAh.g-1, and the capacity retention rate is 96%. The electrolyte contacts the Li electrode and the LiFePO4 electrode to form a stable interface layer, so the discharge specific capacity is stable during the cycle process.

[0083] The ionic conductivity of Example 2 is only 1.13×10 -4 S.cm -1 Although Example 2 forms a unique lithium ion transport channel by the interaction between the lithium salt and the polymer in the high salt system, the type of lithium ion transport channel is relatively single, mainly the interaction between the large volume anion TFSI to form anion clusters for transporting lithium ions.

[0084] The ionic conductivity of Example 3 is only 6.78×10 -5 S.cm -1 In Example 3, the content of lithium salt is low, and the anion clusters in the high salt system are not formed, so this ion channel is lacking; in addition, the cellulose derivative (cellulose acetate) belongs to a polymer, which has a high crystallinity itself, and if it is not treated in advance, the transport of lithium ions cannot achieve good results, so it will inhibit its effect on lithium ion transport.

[0085] It can be seen from Table 2 that the performance of the composite solid-state polymer electrolyte is related to the amount of the modified cellulose derivative. When the amount of the modified cellulose derivative is not more than 10% of the mass of PVDF-HFP, the ionic conductivity becomes larger with the increase of the amount of the addition. When the amount exceeds 10%, the ionic conductivity becomes smaller with the increase of the amount of the addition. When the amount exceeds 20%, the ionic conductivity of the modified cellulose derivative is only slightly larger than that without the addition. Therefore, the amount of the modified cellulose derivative should be not more than 20% of the mass of PVDF-HFP.

[0086] The preferred embodiments of the present application have been described above with the purpose of not limiting the present application, and the present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A composite solid polymer electrolyte, characterized in that, The composite solid polymer electrolyte is prepared from the following raw materials: lithium trifluoromethanesulfonylimide, polyvinylidene fluoride-hexafluoropropylene, modified cellulose derivatives, and solvents; The modified cellulose derivative is obtained by soaking and dissolving the cellulose derivative with an organic modifier; the organic modifier includes at least one of dimethyl sulfoxide, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and 1,2-dimethoxyethane; the cellulose derivative includes at least one of methylcellulose, cellulose acetate, cellulose acetate propionate, carboxymethyl cellulose, ethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methylcellulose. The mass of the cellulose derivative is 1-20% of the mass of lithium trifluoromethanesulfonylimide; The mass ratio of lithium trifluoromethanesulfonylimide to polyvinylidene fluoride-hexafluoropropylene is 1:(0.5-2.5). The composite solid polymer electrolyte is prepared by a method comprising the following steps: (1) Lithium trifluoromethanesulfonylimide and polyvinylidene fluoride-hexafluoropropylene are mixed and dissolved in a solvent to obtain mixture 1; (2) The cellulose derivative and the organic modifier were mixed and stirred to obtain mixture 2; (3) Mix the mixture 1 and the mixture 2, stir, then coat them into a film and shape them to obtain the composite solid polymer electrolyte; Steps (1) and (2) can be interchanged.

2. The composite solid polymer electrolyte according to claim 1, characterized in that, The composite solid polymer electrolyte has a sheet-like structure with a thickness of 90-115 μm.

3. The method for preparing the composite solid polymer electrolyte according to claim 1 or 2, characterized in that, Includes the following steps: (1) Lithium trifluoromethanesulfonylimide and polyvinylidene fluoride-hexafluoropropylene are mixed and dissolved in a solvent to obtain mixture 1; (2) The cellulose derivative and the organic modifier were mixed and stirred to obtain mixture 2; (3) Mix the mixture 1 and the mixture 2, stir, then coat them into a film and shape them to obtain the composite solid polymer electrolyte.

4. The method for preparing the composite solid polymer electrolyte according to claim 3, characterized in that, In step (1), the solvent includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and 1,2-dimethoxyethane.

5. The method for preparing the composite solid polymer electrolyte according to claim 3, characterized in that, In step (1), the lithium trifluoromethanesulfonylimide and polyvinylidene fluoride-hexafluoropropylene are mixed and dissolved in a solvent and stirred for 2-4 hours to obtain mixture 1.

6. The method for preparing the composite solid polymer electrolyte according to claim 3, characterized in that, In step (2), the cellulose derivative is mixed with the organic modifier and stirred for 2-4 hours to obtain mixture 2.

7. The method for preparing the composite solid polymer electrolyte according to claim 3, characterized in that, In step (3), after mixing liquid 1 and mixing liquid 2, stir for 2-4 hours.

8. The application of the composite solid polymer electrolyte according to claim 1 or 2 in the preparation of lithium batteries.

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