CN115440505B - A method for preparing cellulose-based gel electrolyte - Google Patents

Abstract

The invention discloses a preparation method of a cellulose-based gel electrolyte, which comprises the steps of adding microcrystalline cellulose into ionic liquid and cosolvent, heating and stirring until the microcrystalline cellulose is dissolved to obtain cellulose solution; adding an antisolvent into the cellulose solution, stirring until solid is separated out, filtering, and washing a filter cake with deionized water to obtain regenerated cellulose; adding sulfuric acid aqueous solution into regenerated cellulose, heating to 90-95 ℃ in water bath after ultrasonic treatment, adding flexible matrix material, stirring for 1-5h to obtain cellulose/flexible matrix material/sulfuric acid mixed solution, pouring into a mould, and naturally drying to obtain cellulose-based gel electrolyte; the cellulose-based gel polymer electrolyte prepared by the invention has stable property, high ionic conductivity, good flexibility and small electrolyte leakage risk, and compared with gel electrolyte without cellulose, the specific capacitance is improved by 55-80%, and the ionic conductivity is improved by 50-80%, so that the cellulose-based gel polymer electrolyte has good application prospect.

Description

A method for preparing cellulose-based gel electrolyte

(I) Technical field

The invention relates to a method for preparing a cellulose-based gel electrolyte.

(II) Background technology

In recent years, flexible wearable electronic products have shown broad market prospects. Gel polymer electrolytes have attracted increasing attention due to their flexibility, high conductivity and reduced risk of liquid electrolyte leakage. Gel polymer electrolytes are composed of polymers and liquid electrolytes. The polymer matrix chains can be cross-linked with each other, and this structure prevents electrolyte leakage through physical or chemical entanglement. However, in practical applications, gel polymer electrolytes still have the disadvantage of insufficient mechanical strength, and there is also a lot of room for improvement in electrochemical performance.

Cellulose is the most abundant material in nature. It is considered to be one of the most suitable candidate materials for synthesizing green products because of its many characteristics such as renewability, non-toxicity, biodegradability, colloidal stability and low cost. Cellulose is a natural polymer with multiple hydroxyls. Due to the hydrogen bonds between hydroxyls and water molecules, it has a strong water retention capacity and can be used to absorb electrolytes. In addition, if the two electrodes are connected by a network structure composed of cellulose, the mechanical strength of the gel can be improved while allowing free ions to migrate quickly through the fiber network to achieve charge adsorption. Improve the ionic conductivity of the gel electrolyte. However, natural cellulose often has a large particle size and is difficult to dissolve in general solvents, which is not conducive to the subsequent preparation of cellulose-based materials. The traditional dissolution process has a low dissolution efficiency and will cause pollution to the environment. Therefore, we need to find a way to treat cellulose to improve its dissolution efficiency without polluting the environment, and to enable it to be better used in the preparation of electrolyte gels.

(III) Summary of the invention

The object of the present invention is to provide a method for preparing a cellulose-based gel electrolyte, which can efficiently dissolve cellulose, so that the gel electrolyte has good electrochemical properties and flexibility and can avoid the risk of leakage of liquid electrolyte when preparing flexible supercapacitors.

The technical solution adopted by the present invention is:

The present invention provides a method for preparing a cellulose-based gel electrolyte, which is carried out according to the following steps: (1) adding microcrystalline cellulose to an ionic liquid and a cosolvent, heating and stirring until dissolved, and obtaining a cellulose solution; the ionic liquid comprises one or a mixture of 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium diethyl phosphate or 1-ethyl-3-methylimidazolium tetrafluoroborate; the cosolvent is one or a mixture of dimethyl sulfoxide, dimethylformamide or dimethylacetamide; (2) adding an antisolvent to the cellulose solution of step (1), stirring until solids are precipitated, and filtering (preferably through a filter membrane with a pore size of 0.02 μm) to obtain a cellulose solution; (3) adding sulfuric acid aqueous solution to the regenerated cellulose of step (2), ultrasonicating at 20-30° C. and 200-380 W for 5-10 min to obtain a mixed solution after ultrasonication; (4) heating the mixed solution after ultrasonication in step (3) to 90-95° C. in a water bath, adding a flexible matrix material, stirring for 1-5 h to obtain a cellulose/flexible matrix material/sulfuric acid mixed solution, pouring it into a mold, and drying it naturally to obtain a cellulose-based gel electrolyte; the flexible matrix material comprises one or a mixture of polyvinyl alcohol, polyacrylamide, polyethyleneimine, polyethylene oxide or polyurethane acrylate.

Furthermore, in step (1), the mass ratio of microcrystalline cellulose to ionic liquid is 1:5-20, preferably 1:10-20; and the mass ratio of microcrystalline cellulose to cosolvent is 1:20-1:120, preferably 1:50-1:60.

Further, the ionic liquid in step (1) is 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, or a mixture of 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium chloride in a mass ratio of 1:0.5.

Furthermore, step (1) is heated to 40-85°C, preferably 60-85°C.

Furthermore, the co-solvent in step (1) is dimethyl sulfoxide, dimethylformamide, dimethylacetamide, or a mixture of dimethyl sulfoxide and dimethylformamide in a mass ratio of 1:1.

Furthermore, the volume amount of the anti-solvent in step (2) is 1-6 L/g based on the mass of the microcrystalline cellulose in step (1); the anti-solvent is deionized water, ethanol, ether, acetone, benzene, or a mixture of deionized water and ethanol in a volume ratio of 1:1.

Furthermore, the concentration of the aqueous sulfuric acid solution in step (3) is 1-2 mol/L, and the volume of the aqueous sulfuric acid solution is 0.1-1 L/g, preferably 0.1-0.4 L/g, based on the mass of the microcrystalline cellulose in step (1).

Furthermore, the ultrasonic conditions in step (3) are 20-25° C. and 200-300 W for 10 min.

Furthermore, the mass ratio of the flexible matrix material in step (4) to the microcrystalline cellulose in step (1) is 10-50:1, preferably 15-45:1. The stirring time in step (4) is 1-2h.

Furthermore, the mold in step (4) is a glass square dish; the natural drying time is 10-12 hours.

Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

(1) The traditional method has a low efficiency in dissolving cellulose and usually needs to be carried out at high temperature (140-180°C), which will cause serious harm to the environment. The present invention uses a mixed solvent of ionic liquid and co-solvent to dissolve cellulose, which has a high dissolving ability and dissolving efficiency, can be carried out at low temperature (40-85°C), and will not cause harm to the environment, which is green and environmentally friendly; the addition of co-solvent effectively reduces the viscosity of the ionic liquid, helps to speed up the dissolution rate, reduce the dissolution temperature, and thus avoid the decomposition of the ionic liquid and cellulose. If the cellulose cannot be dissolved after the ionic liquid is removed, the dissolution efficiency will be reduced after the co-solvent is removed, and the dissolution time will increase by more than 3 times.

(2) The cellulose-based gel polymer electrolyte prepared by the present invention has stable properties, high ionic conductivity, good flexibility, and low risk of electrolyte leakage. Compared with the gel electrolyte without cellulose, the specific capacitance is increased by 55% to 80%, and the ionic conductivity is increased by 50% to 80%, and has good application prospects.

(IV) Specific implementation methods

The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

The microcrystalline cellulose used in the examples of the present invention is produced by Aladdin, with a CAS number of 9004-34-6. Before use, it was dried at 60° C. to a water content of less than 1%.

The room temperature of the present invention is 25-30°C.

Embodiment 1,

1. Cellulose-based gel electrolyte

(1) Weigh 0.1 g of microcrystalline cellulose and add it to a mixed solvent consisting of 1 g of 1-ethyl-3-methylimidazolium acetate and 5 g of dimethyl sulfoxide. Heat and stir in a 60° C. water bath until it is completely dissolved to obtain a homogeneous cellulose solution.

(2) Add 200 mL of deionized water to the cellulose solution in step (1) and stir continuously. A large amount of white flocculent solid precipitates. The solid is filtered with a filter membrane with a pore size of 0.02 μm. The filter cake is then washed with deionized water to obtain regenerated cellulose.

(3) Put all the regenerated cellulose obtained in step (2) into a beaker, add 25 mL of 1 mol/L sulfuric acid aqueous solution into the beaker, and ultrasonicate at 20° C. and 200 W for 10 minutes to obtain a mixed solution after ultrasonication.

(4) placing the beaker containing the entire mixed solution after ultrasonication in step (3) in a water bath and heating it to 95° C., adding 2.5 g of polyvinyl alcohol thereto, and stirring continuously for 2 hours to obtain a cellulose/polyvinyl alcohol/sulfuric acid mixed solution.

(5) The entire mixed solution of step (4) was poured into a glass square dish (length 2 cm, width 2 cm, height 10 cm) by casting method and dried at room temperature for 12 h to obtain a cellulose-based gel electrolyte with dimensions of 8 cm in length, 1.5 cm in width, and 1.5 cm in thickness.

Under the same conditions, the microcrystalline cellulose in step (1) was removed, and the other conditions were the same to obtain a control gel electrolyte.

2. Ionic conductivity

Using carbon paper (1.5cm×8cm) as an electrode, 1.5cm×7cm×2cm of gel electrolyte was cut from the cellulose-based gel electrolyte prepared in step 1 and sandwiched between two pieces of carbon paper to form a simple capacitor. At 20°C and a scan rate of 20mv/s, the specific capacitance of the cellulose-based gel electrolyte was 78F/g and the ionic conductivity was 2.3mS/cm; the specific capacitance of the control gel electrolyte was 48F/g and the ionic conductivity was 1.5mS/cm; the specific capacitance of the cellulose-based gel electrolyte was increased by 62.5% compared with the control group without cellulose addition, and the ionic conductivity was increased by 53.3%.

Embodiment 2,

1. Cellulose-based gel electrolyte

(1) Weigh 0.1 g of microcrystalline cellulose and add it to a mixed solvent consisting of 1.2 g of 1-butyl-3-methylimidazolium chloride and 6 g of dimethylformamide, and heat and stir in a 75° C. water bath until it is completely dissolved to obtain a homogeneous cellulose solution.

(2) Add 250 mL of ethanol to the entire cellulose solution in step (1) and continue stirring. A large amount of white flocculent solid precipitates, which is filtered through a filter membrane with a pore size of 0.02 μm. The filter cake is then washed with deionized water to obtain regenerated cellulose.

(3) Put all the regenerated cellulose obtained in step (2) into a beaker, add 30 mL of 1 mol/L sulfuric acid aqueous solution, and ultrasonicate at 20° C. and 250 W for 10 minutes to obtain a mixed solution after ultrasonication.

(4) The beaker containing the ultrasonically mixed solution in step (3) was placed in a water bath and heated to 95° C. 3.5 g of polyacrylamide was added thereto, and the mixture was stirred and kept warm for 3 hours to obtain a cellulose/polyacrylamide/sulfuric acid mixed solution.

(5) The mixed solution of step (4) was poured into a glass square dish (length 2 cm, width 2 cm, height 10 cm) by casting method and dried at room temperature for 10 h to obtain a cellulose-based gel electrolyte with a length of 8 cm, a width of 1.5 cm, and a thickness of 1.5 cm.

2. Ionic conductivity

The same method as in Example 1 was used, with carbon paper (1.5 cm × 8 cm) as an electrode, and 1.5 cm × 7 cm × 2 cm of gel electrolyte was cut from the cellulose-based gel electrolyte prepared in step 1, and sandwiched between two pieces of carbon paper to form a simple capacitor. The obtained cellulose-based gel electrolyte had a specific capacitance of 83 F/g and an ionic conductivity of 2.6 mS/cm at a scan rate of 20 ° C and 20 mv/s, while the specific capacitance of the control gel electrolyte was 50 F/g and the ionic conductivity was 1.6 mS/cm. The specific capacitance was increased by 66.0% compared with the control group without cellulose addition, and the ionic conductivity was increased by 62.5%.

Embodiment 3,

1. Cellulose-based gel electrolyte

(1) Weigh 0.15 g of microcrystalline cellulose and add it to a mixed solvent consisting of 1 g of 1-ethyl-3-methylimidazolium acetate, 0.5 g of 1-butyl-3-methylimidazolium chloride and 5.5 g of dimethyl sulfoxide, and heat and stir in a water bath at 85° C. until it is completely dissolved to obtain a homogeneous cellulose solution.

(2) Add 200 mL of deionized water to the entire cellulose solution in step (1) and continue stirring. A large amount of white flocculent solid precipitates, which is filtered through a filter membrane with a pore size of 0.02 μm. The filter cake is then washed with deionized water to obtain regenerated cellulose.

(3) Put all the regenerated cellulose obtained in step (2) into a beaker, add 25 mL of 1 mol/L sulfuric acid aqueous solution, and ultrasonicate at 25° C. and 300 W for 10 minutes to obtain a mixed solution after ultrasonication.

(4) placing the beaker containing the ultrasonically mixed solution in step (3) in a water bath and heating it to 95° C., adding 2.5 g of polyvinyl alcohol thereto, and stirring and keeping warm for 2 hours to obtain a cellulose/polyvinyl alcohol/sulfuric acid mixed solution.

(5) The mixed solution of step (4) was poured into a glass square dish (length 2 cm, width 2 cm, height 10 cm) by casting method and dried at room temperature for 11 h to obtain a cellulose-based gel electrolyte with a length of 8 cm, a width of 1.5 cm, and a thickness of 1.5 cm.

2. Ionic conductivity

The same method as in Example 1 was used, with carbon paper (1.5 cm × 8 cm) as an electrode, and 1.5 cm × 7 cm × 2 cm of gel electrolyte was cut from the cellulose-based gel electrolyte prepared in step 1, and sandwiched between two pieces of carbon paper to form a simple capacitor. The specific capacitance of the obtained gel electrolyte at 20°C and a scan rate of 20 mv/s was 88 F/g, and the ionic conductivity was 2.8 mS/cm. The specific capacitance of the control gel electrolyte was 50 F/g, and the ionic conductivity was 1.6 mS/cm. The specific capacitance was increased by 76.0% compared with the control group without cellulose addition, and the ionic conductivity was increased by 75.0%.

Embodiment 4,

1. Cellulose-based gel electrolyte

(1) Weigh 0.05 g of microcrystalline cellulose and add it to a mixed solvent consisting of 1 g of 1-allyl-3-methylimidazolium chloride and 6 g of dimethylacetamide, and heat and stir in a 60° C. water bath until it is completely dissolved to obtain a homogeneous cellulose solution.

(2) 300 mL of ether was added to the cellulose solution in step (1) and stirred continuously. A large amount of white flocculent solid was precipitated and filtered with a filter membrane with a pore size of 0.02 μm. The filter cake was then washed with deionized water to obtain regenerated cellulose.

(3) Put all the regenerated cellulose obtained in step (2) into a beaker, add 20 mL of 1 mol/L sulfuric acid aqueous solution, and ultrasonicate at 20° C. and 300 W for 10 minutes to obtain a mixed solution after ultrasonication.

(4) The beaker containing the ultrasonically treated mixed solution in step (3) was placed in a water bath and heated to 95° C. 2.2 g of polyethyleneimine was added thereto, and the mixture was stirred and kept warm for 2 hours to obtain a cellulose/polyethyleneimine/sulfuric acid mixed solution.

(5) The mixed solution of step (4) was poured into a glass square dish (length 2 cm, width 2 cm, height 10 cm) by casting method and dried at room temperature for 10 h to obtain a cellulose-based gel electrolyte with a length of 8 cm, a width of 1.5 cm, and a thickness of 1.5 cm.

2. Ionic conductivity

The same method as in Example 1 was used, with carbon paper (1.5 cm × 8 cm) as an electrode, and 1.5 cm × 7 cm × 2 cm of gel electrolyte was cut from the cellulose-based gel electrolyte prepared in step 1, and sandwiched between two sheets of carbon paper to form a simple capacitor. The specific capacitance of the obtained gel electrolyte at 20°C and a scan rate of 20 mv/s was 64 F/g, and the ionic conductivity was 2.1 mS/cm. The specific capacitance of the control gel electrolyte was 41 F/g, and the ionic conductivity was 1.4 mS/cm. The specific capacitance was increased by 56.1% compared with the control group without cellulose addition, and the ionic conductivity was increased by 50.0%.

Embodiment 5,

1. Cellulose-based gel electrolyte

(1) Weigh 0.1 g of microcrystalline cellulose and add it to a mixed solvent consisting of 1 g of 1-ethyl-3-methylimidazole diethyl phosphate and 5 g of dimethyl sulfoxide, and heat and stir in a 60° C. water bath until it is completely dissolved to obtain a homogeneous cellulose solution.

(2) 100 mL of deionized water and 100 mL of ethanol were added to the cellulose solution in step (1) and stirred continuously. A large amount of white flocculent solid was precipitated and filtered with a filter membrane with a pore size of 0.02 μm. The filter cake was then washed with deionized water to obtain regenerated cellulose.

(3) Put all the regenerated cellulose obtained in step (2) into a beaker, add 25 mL of 1 mol/L sulfuric acid aqueous solution, and ultrasonicate at 25° C. and 200 W for 10 minutes to obtain a mixed solution after ultrasonication.

(4) placing the beaker containing the ultrasonically mixed solution in step (3) in a water bath and heating it to 90° C., adding 2.5 g of polyvinyl alcohol thereto, and stirring and keeping warm for 2 hours to obtain a cellulose/polyvinyl alcohol/sulfuric acid mixed solution.

(5) The mixed solution of step (4) was poured into a glass square dish (length 2 cm, width 2 cm, height 10 cm) by casting method and dried at room temperature for 12 h to obtain a cellulose-based gel electrolyte with a length of 8 cm, a width of 1.5 cm, and a thickness of 1.5 cm.

2. Ionic conductivity

The same method as in Example 1 was used, with carbon paper (1.5 cm × 8 cm) as an electrode, and 1.5 cm × 7 cm × 2 cm of gel electrolyte was cut from the cellulose-based gel electrolyte prepared in step 1, and sandwiched between two pieces of carbon paper to form a simple capacitor. The specific capacitance of the obtained gel electrolyte at 20°C and a scan rate of 20 mv/s was 75 F/g, and the ionic conductivity was 2.2 mS/cm. The specific capacitance of the control gel electrolyte was 47 F/g, and the ionic conductivity was 1.4 mS/cm. The specific capacitance was increased by 59.6% compared with the control group without cellulose addition, and the ionic conductivity was increased by 57.1%.

Embodiment 6,

1. Cellulose-based gel electrolyte

(1) Weigh 0.1 g of microcrystalline cellulose and add it to a mixed solvent consisting of 1 g of 1-ethyl-3-methylimidazolium tetrafluoroborate, 3 g of dimethyl sulfoxide and 3 g of dimethylformamide, and heat and stir in a 70° C. water bath until it is completely dissolved to obtain a homogeneous cellulose solution.

(2) 150 mL of acetone was added to the cellulose solution in step (1) and the mixture was stirred continuously. A large amount of white flocculent solid was precipitated and filtered through a filter membrane with a pore size of 0.02 μm. The filter cake was then washed with deionized water to obtain regenerated cellulose.

(3) Put all the regenerated cellulose obtained in step (2) into a beaker, add 25 mL of 1.5 mol/L sulfuric acid aqueous solution, and ultrasonicate at 25° C. and 300 W for 10 minutes to obtain a mixed solution after ultrasonication.

(4) The mixed solution after ultrasonication in step (3) is placed in a water bath and heated to 95° C., 2.5 g of polyethylene oxide is added thereto, and the mixture is stirred and kept warm for 2 hours to obtain a cellulose/polyethylene oxide/sulfuric acid mixed solution.

(5) The mixed solution of step (4) was poured into a glass square dish (length 2 cm, width 2 cm, height 10 cm) by casting method and dried at room temperature for 12 h to obtain a cellulose-based gel electrolyte (length 8 cm, width 1.5 cm, thickness 1.5 cm).

2. Ionic conductivity

The same method as in Example 1 was used, with carbon paper (1.5 cm × 8 cm) as an electrode, and 1.5 cm × 7 cm × 2 cm of gel electrolyte was cut from the cellulose-based gel electrolyte prepared in step 1, and sandwiched between two pieces of carbon paper to form a simple capacitor. The specific capacitance of the obtained gel electrolyte at 20°C and a scan rate of 20 mv/s was 70 F/g, and the ionic conductivity was 2.1 mS/cm. The specific capacitance of the control gel electrolyte was 43 F/g, and the ionic conductivity was 1.3 mS/cm. The specific capacitance was increased by 62.7% compared with the control group without cellulose addition, and the ionic conductivity was increased by 61.5%.

Embodiment 7,

1. Cellulose-based gel electrolyte

(1) Weigh 0.1 g of microcrystalline cellulose and add it to a mixed solvent consisting of 1 g of 1-ethyl-3-methylimidazolium acetate and 5 g of dimethyl sulfoxide. Heat and stir in a water bath at 80° C. until the cellulose is completely dissolved to obtain a homogeneous cellulose solution.

(2) 100 mL of deionized water was added to the cellulose solution in step (1) and stirred continuously. A large amount of white flocculent solid was precipitated and filtered with a filter membrane with a pore size of 0.02 μm. The filter cake was then washed with deionized water to obtain regenerated cellulose.

(3) The regenerated cellulose obtained in step (2) was placed in a beaker, 30 mL of 1.5 mol/L sulfuric acid aqueous solution was added, and ultrasonicated at 20° C. and 250 W for 10 minutes to obtain a mixed solution after ultrasonication.

(4) placing the beaker containing the ultrasonically treated mixed solution in step (3) in a water bath and heating it to 95° C., adding 1.0 g of polyurethane acrylate and 2 g of polyvinyl alcohol thereto, and stirring and keeping the mixture warm for 2 hours to obtain a cellulose/polyurethane acrylate/polyvinyl alcohol/sulfuric acid mixed solution.

(5) The mixed solution of step (4) was poured into a glass dish (length 2 cm, width 2 cm, height 10 cm) by casting method and dried at room temperature for 12 h to obtain a cellulose-based gel electrolyte (length 8.5 cm, width 1.5 cm, thickness 1.5 cm).

2. Ionic conductivity

The same method as in Example 1 was used, with carbon paper (1.5 cm × 8 cm) as an electrode, and 1.5 cm × 7 cm × 2 cm of gel electrolyte was cut from the cellulose-based gel electrolyte prepared in step 1, and sandwiched between two sheets of carbon paper to form a simple capacitor. The specific capacitance of the obtained gel electrolyte at 20°C and a scan rate of 20 mv/s was 82 F/g, and the ionic conductivity was 2.7 mS/cm. The specific capacitance of the control gel electrolyte was 47 F/g, and the ionic conductivity was 1.5 mS/cm. The specific capacitance was increased by 74.5% compared with the control group without cellulose addition, and the ionic conductivity was increased by 80.0%.

Claims (9)

1. A method for preparing a cellulose-based gel electrolyte, comprising the steps of: (1) Adding microcrystalline cellulose into ionic liquid and cosolvent, heating and stirring until dissolving to obtain cellulose solution; the cosolvent is one or a mixture of more of dimethyl sulfoxide, dimethylformamide or dimethylacetamide; (2) Adding an antisolvent into the cellulose solution in the step (1), stirring until solid is separated out, filtering, and washing a filter cake with deionized water to obtain regenerated cellulose; the antisolvent is one or a mixture of more of deionized water, ethanol, diethyl ether, acetone and benzene; (3) Adding sulfuric acid aqueous solution into the regenerated cellulose in the step (2), and performing ultrasonic treatment at 20-30 ℃ and 200-380W for 5-10min to obtain ultrasonic mixed solution; (4) Heating the mixed solution obtained after ultrasonic treatment in the step (3) to 90-95 ℃ in a water bath, adding the flexible matrix material, stirring for 1-5h to obtain a cellulose/flexible matrix material/sulfuric acid mixed solution, pouring the mixed solution into a mould, and naturally drying to obtain the cellulose-based gel electrolyte; the flexible matrix material comprises one or a mixture of several of polyvinyl alcohol, polyacrylamide, polyethyleneimine, polyethylene oxide or polyurethane acrylic ester.

2. The method for preparing a cellulose-based gel electrolyte according to claim 1, wherein the mass ratio of the microcrystalline cellulose to the ionic liquid in the step (1) is 1:5-20; the mass ratio of the microcrystalline cellulose to the cosolvent is 1:20-1:120.

3. The method for preparing a cellulose-based gel electrolyte according to claim 1, wherein the ionic liquid in the step (1) is one or a mixture of several of 1-ethyl-3-methylimidazole acetate, 1-butyl-3-methylimidazole chloride, 1-allyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazole diethyl phosphate or 1-ethyl-3-methylimidazole tetrafluoroborate.

4. The method for producing a cellulose-based gel electrolyte according to claim 1, wherein step (1) is heated to 40 to 85 ℃.

5. The method for preparing a cellulose-based gel electrolyte according to claim 1, wherein the cosolvent in step (1) is one of dimethyl sulfoxide, dimethylformamide and dimethylacetamide, or a mixture of dimethyl sulfoxide and dimethylformamide in a mass ratio of 1:1.

6. The method of preparing a cellulose-based gel electrolyte according to claim 1, wherein the antisolvent volume of step (2) is 1 to 6L/g based on the mass of the microcrystalline cellulose of step (1); the antisolvent is one of deionized water, ethanol, diethyl ether, acetone and benzene, or the mixture of deionized water and ethanol in a volume ratio of 1:1.

7. The method for producing a cellulose-based gel electrolyte according to claim 1, wherein the concentration of the aqueous sulfuric acid solution in the step (3) is 1 to 2mol/L, and the volume amount of the aqueous sulfuric acid solution is 0.1 to 1L/g based on the mass of the microcrystalline cellulose in the step (1).

8. The method for preparing a cellulose-based gel electrolyte according to claim 1, wherein the ultrasonic conditions in the step (3) are ultrasonic at 20 to 25 ℃ for 10 minutes at 200 to 300W.

9. The method for preparing a cellulose-based gel electrolyte according to claim 1, wherein the mass ratio of the flexible matrix material of step (4) to the microcrystalline cellulose of step (1) is 10-50:1.