A paper-based solid electrolyte with high electrical conductivity and flame retardancy, and its preparation method and application

Abstract

The present invention discloses a paper-based solid electrolyte with high electrical conductivity and flame retardant properties, as well as its preparation method and application, belonging to the field of energy storage materials and polymer technology. The present invention comprises mixing sulfonylimide lithiated cellulose, polyethylene glycol, additives, and lithiated clay, stirring, freeze-drying, impregnating with a crosslinking agent, and hot-pressing to obtain a paper-based solid electrolyte. The paper-based solid electrolyte prepared by the present invention has high electrical conductivity and excellent flame retardant properties and can be applied to all-solid-state lithium batteries. The preparation reaction conditions of the present invention are mild, and it can be used for industrial large-scale production, showing good practicality.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage materials and polymers, and specifically relates to a paper-based solid electrolyte with high electrical conductivity and flame retardancy, and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries are considered the most promising energy storage materials due to their high energy density and long cycle life. However, conventional lithium-ion liquid electrolytes can react with lithium metal, leading to the growth of lithium dendrites and serious safety concerns. Therefore, researchers have proposed using solid-state electrolytes to address the safety issues of lithium metal batteries.

[0003] Solid-state electrolytes, as solid ion conductors, can conduct lithium ions between the cathode and anode, thereby enabling the storage and release of electrical energy. However, the rigid interface between the solid-state electrolyte and lithium metal results in different ion transport channels. Furthermore, the internal ion transport rate is low, resulting in high interfacial impedance and low ionic conductivity.

[0004] Current research focuses on three major material systems: oxides (such as lithium lanthanum zirconium oxide), sulfides, and polymers (such as polyethylene glycol). These single systems often suffer from issues such as high interfacial resistance, poor stability, and low conductivity. Furthermore, these systems often require complex and demanding large-scale manufacturing processes, which increases the cost of industrial applications and hinders large-scale production. Cellulose is one of the most abundant renewable resources in nature, with applications in new materials, chemical raw materials, medicine, and the environment. It has attracted considerable attention due to its abundant availability, renewability, and biodegradability. The polar environment within cellulose molecules effectively promotes lithium ion delocalization, thereby enhancing the conductivity and energy density of lithium-ion batteries. Therefore, constructing solid-state electrolyte systems using cellulose as a polymer matrix to achieve stable operation of lithium metal batteries has become a key research topic in recent years, demonstrating excellent electrochemical performance. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide a paper-based solid electrolyte with advantages such as high ionic conductivity and flame retardant properties; the second technical problem to be solved by the present invention is to provide a method for preparing a paper-based solid electrolyte with high conductivity and flame retardant properties. The method has a simple process and mild reaction conditions and can be used for industrial large-scale production; the third technical problem to be solved by the present invention is the application of the paper-based solid electrolyte in lithium batteries, thereby achieving stable circulation of lithium batteries and solving the safety hazards of lithium batteries.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A method for preparing a paper-based solid electrolyte with high electrical conductivity and flame retardancy comprises the following steps:

[0008] 1) Using wood chemical pulp as raw material, lithium chloride and N,N-dimethylacetamide are added to dissolve the cellulose in the wood chemical pulp. Acryloyl chloride is added to the cellulose solution and reacted in an ice-water bath. Then, lithium p-styrene trifluoromethylsulfonyl imide and a photoinitiator are added and reacted under ultraviolet light. The solvent is then removed by rotary evaporation to obtain lithium sulfonyl imide cellulose.

[0009] 2) Adding clay and lithium hydroxide to a hydrogen peroxide solution, mixing and stirring, and dialyzing to obtain lithiated clay;

[0010] 3) mixing the sulfonimide lithiated cellulose obtained in step 1), the lithiated clay obtained in step (2), the additive, and polyethylene glycol, freeze-forming, and freeze-drying to obtain a composite electrolyte;

[0011] 4) adding a crosslinking agent to the composite electrolyte obtained in step 3) and hot pressing to obtain a paper-based solid electrolyte.

[0012] Furthermore, in step 1), the cellulose is selected from chemical pulp of eucalyptus and poplar, and has a molecular weight of 400,000-1,000,000.

[0013] Furthermore, in step 1), the molar ratio of acryloyl chloride to cellulose is 10:1 to 1:10; and the ice bath time is 6 to 12 hours.

[0014] Furthermore, in step 1), the photoinitiator is selected from one or more of benzoin dimethyl ether and 2,2-azobisisobutylamidine dihydrochloride.

[0015] Furthermore, in step 2), the clay is selected from one or more of lingshanite, montmorillonite and vermiculite; the stirring temperature is 50-120°C, and the stirring time is 6-24 hours.

[0016] Furthermore, in step 2), the additive is selected from one or more of succinonitrile, ethylene carbonate, fluoroethylene carbonate and propylene carbonate.

[0017] Furthermore, in step 3), the molecular weight of polyethylene glycol is 200-10,000; and the mass ratio of sulfonimide lithiated cellulose, lithiated clay, additive and polyethylene glycol is 20:20:1:2-20:20:5:10.

[0018] Furthermore, in step 4), the cross-linking agent is selected from one or more of glutaraldehyde, hexamethylene diisocyanate, and isophorone diisocyanate; the hot pressing temperature is 120-180° C., and the pressure is 50-100 MPa.

[0019] Furthermore, the method for preparing the paper-based solid electrolyte with high electrical conductivity and flame retardancy, and the prepared paper-based solid electrolyte.

[0020] Furthermore, the paper-based solid electrolyte is used in lithium battery electrodes.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The paper-based solid electrolyte prepared by the present invention has an excellent ionic conductivity of 5.50×10 -4 S cm -1 , low interfacial impedance of 35 Ω and good flame retardant properties.

[0023] (2) The raw materials for preparing the paper-based solid electrolyte in the present invention are easily available, the reaction conditions are mild, the preparation process is simple, and it can be industrialized and produced on a large scale.

[0024] (3) The sulfonimide lithiated cellulose used in the present invention is a cellulose derivative that is biodegradable and non-toxic, thereby reducing environmental pollution during industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an AC impedance curve of the paper-based solid electrolyte prepared in Example 9 of the present application;

[0026] Figure 2 This is a heat release curve of the paper-based solid electrolyte prepared in Example 9 of the present application. DETAILED DESCRIPTION

[0027] The present invention will be further illustrated below with reference to specific examples. The examples are implemented based on the technical solutions of the present invention. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0028] In the following examples, lithium chloride (≥99.9%), N,N-dimethylacetamide (≥99.8%), succinonitrile (≥99%), 2,2-azobisisobutylamidine dihydrochloride (≥97%), hexamethylene diisocyanate (≥99%), propylene carbonate (≥99.7%), and isophorone diisocyanate (≥99%) were all purchased from Aladdin; benzoin dimethyl ether (99%), montmorillonite (sodium base), lithium hydroxide (99.5%), polyethylene glycol, glutaraldehyde solution, kaolinite, ethylene carbonate (99.99%), and vermiculite (20-40 mesh) were all purchased from Maclean; and hydrogen peroxide solution was purchased from Nanjing Chemical Reagent Co., Ltd.

[0029] In the following examples, the preparation process of wood chemical pulp is as follows: 2 g of debarked wood chips are added to 500 ml of a mixed solution of 100 g / L sodium hydroxide and 50 g / L sodium sulfide, the temperature is raised to 165° C., and the temperature is kept for 90 min.

[0030] The preparation process of lithium p-styrene trifluoromethylsulfonyl imide in the following example is as follows: sodium p-styrene sulfonate, thionyl chloride and trifluoromethanesulfonamide are reacted and lithiation is performed to obtain lithium p-styrene trifluoromethylsulfonyl imide.

[0031] Example 1

[0032] A method for preparing a paper-based solid electrolyte with high electrical conductivity and flame retardancy comprises the following steps:

[0033] (1) Eucalyptus chemical pulp (M w =400000 g / mol) as raw material, lithium chloride and N,N-dimethylacetamide were added at 150 ℃ to dissolve cellulose in eucalyptus chemical pulp. The mass ratio of eucalyptus chemical pulp, lithium chloride and N,N-dimethylacetamide was 1:4:46. After filtration, a cellulose solution was obtained. Acryloyl chloride was added dropwise to the cellulose solution (the molar ratio of acryloyl chloride to cellulose was 10:1). The mixture was reacted in an ice-water bath (0 ℃) for 6 h. Then, lithium p-styrene trifluoromethylsulfonyl imide and 0.1 g of benzoin dimethyl ether were added to the solution in the same molar amount as acryloyl chloride. The mixture was reacted under ultraviolet light for 3 h. The solvent was removed by rotary evaporation to obtain sulfonyl imide lithiated cellulose.

[0034] (2) 1 g of montmorillonite and 10 g of lithium hydroxide were added to 100 mL of hydrogen peroxide solution (30 wt%), stirred at 120 °C for 12 h, and dialyzed for 3 days to obtain lithiated montmorillonite.

[0035] (3) The sulfonimide lithiated cellulose obtained in step (1), the lithiated montmorillonite obtained in step (2), succinonitrile and polyethylene glycol (molecular weight 200) were mixed in a mass ratio of 20:20:5:10, stirred, frozen on an ice ethanol medium, and freeze-dried at -80 °C for 24 h to obtain a composite electrolyte.

[0036] (4) 0.50 g of glutaraldehyde solution (50 wt%) was added dropwise to the composite electrolyte obtained in step (3), and hot pressed at 120 °C and 50 MPa for 20 min to obtain a paper-based solid electrolyte.

[0037] Example 2

[0038] A method for preparing a paper-based solid electrolyte with high electrical conductivity and flame retardancy comprises the following steps:

[0039] (1) Poplar chemical pulp (M w =800000 g / mol) as raw material, lithium chloride and N,N-dimethylacetamide were added at 150 ℃ to dissolve cellulose in poplar chemical pulp, the mass ratio of poplar chemical pulp, lithium chloride and N,N-dimethylacetamide being 1:4:46. After filtration, a cellulose solution was obtained, to which acryloyl chloride (the molar ratio of acryloyl chloride to cellulose being 1:10) was added dropwise, and the mixture was reacted in an ice-water bath (0 ℃) for 8 h. Then, lithium p-styrene trifluoromethylsulfonyl imide and 0.01 g of benzoin dimethyl ether were added to the solution in the same molar amount as acryloyl chloride, and the mixture was reacted under ultraviolet light for 4 h. The solvent was then removed by rotary evaporation to obtain sulfonyl imide lithiated cellulose.

[0040] (2) Add 1 g of kaolinite and 10 g of lithium hydroxide to 100 mL of hydrogen peroxide solution (30 wt%), stir at 110 °C for 10 h, and dialyze for 2 days to obtain lithiated kaolinite.

[0041] (3) The sulfonimide lithiated cellulose obtained in step (1), the lithiated kaolinite obtained in step (2), ethylene carbonate, and polyethylene glycol (molecular weight 400) were mixed in a mass ratio of 20:20:1:2, stirred, freeze-formed on an ice ethanol medium, and freeze-dried at -60°C for 36 h to obtain a composite electrolyte.

[0042] (4) 0.20 g of glutaraldehyde solution was added dropwise to the composite electrolyte obtained in step (3), and hot pressed at 140 °C and 60 MPa for 20 min to obtain a paper-based solid electrolyte.

[0043] Example 3

[0044] A method for preparing a paper-based solid electrolyte with high electrical conductivity and flame retardancy comprises the following steps:

[0045] (1) Poplar chemical pulp (M w =1000000 g / mol) as raw material, lithium chloride and N,N-dimethylacetamide were added at 150 ℃ to dissolve cellulose in poplar chemical pulp, the mass ratio of poplar chemical pulp, lithium chloride and N,N-dimethylacetamide being 1:4:46. After filtration, a cellulose solution was obtained, to which acryloyl chloride was added dropwise (the molar ratio of acryloyl chloride to cellulose was 5:5). The mixture was reacted in an ice-water bath (0 ℃) for 10 h, and then lithium p-styrene trifluoromethylsulfonyl imide and 0.05 g of 2,2-azobisisobutylamidine dihydrochloride were added in the same molar amount as acryloyl chloride. The mixture was reacted under ultraviolet light for 5 h, and the solvent was removed by rotary evaporation to obtain sulfonyl imide lithiated cellulose.

[0046] (2) Add 1 g of vermiculite and 10 g of lithium hydroxide to 100 mL of hydrogen peroxide solution (30 wt%), stir at 110 °C for 12 h, and dialyze for 3 days to obtain lithiated vermiculite.

[0047] (3) The sulfonimide lithiated cellulose obtained in step (1), the lithiated vermiculite obtained in step (2), ethylene carbonate, and polyethylene glycol (molecular weight 2000) were mixed in a mass ratio of 20:20:4:5, stirred, freeze-formed on an ice ethanol medium, and freeze-dried at -60°C for 48 h to obtain a composite electrolyte.

[0048] (4) 0.10 g of hexamethylene diisocyanate was added dropwise to the composite electrolyte obtained in step (3), and hot pressed at 140 °C and 60 MPa for 20 min to obtain a paper-based solid electrolyte.

[0049] Example 4

[0050] A method for preparing a paper-based solid electrolyte with high electrical conductivity and flame retardancy comprises the following steps:

[0051] (1) Eucalyptus chemical pulp (M w =600000 g / mol) as raw material, lithium chloride and N,N-dimethylacetamide were added at 150 ℃ to dissolve cellulose in eucalyptus chemical pulp. The mass ratio of eucalyptus chemical pulp, lithium chloride and N,N-dimethylacetamide was 1:4:46. After filtration, a cellulose solution was obtained. Acryloyl chloride was added dropwise to the cellulose solution (the molar ratio of acryloyl chloride to cellulose was 8:2). The mixture was reacted in an ice-water bath (0 ℃) for 12 h. Then, lithium p-styrene trifluoromethylsulfonyl imide and 0.08 g of 2,2-azobisisobutylamidine dihydrochloride were added to the solution in the same molar amount as acryloyl chloride. The mixture was reacted under ultraviolet light for 3 h. The solvent was removed by rotary evaporation to obtain lithium sulfonyl imide cellulose.

[0052] (2) Add 1 g of vermiculite and 10 g of lithium hydroxide to 100 mL of hydrogen peroxide solution (30 wt%), stir at 100 °C for 12 h, and dialyze for 1 day to obtain lithiated vermiculite.

[0053] (3) The sulfonimide lithiated cellulose obtained in step (1), the lithiated vermiculite obtained in step (2), succinonitrile and polyethylene glycol (molecular weight 5000) were mixed in a mass ratio of 20:20:1:3, stirred, frozen on an ice ethanol medium, and freeze-dried at -50 °C for 24 h to obtain a composite electrolyte.

[0054] (4) 0.20 g of glutaraldehyde was added dropwise to the composite electrolyte obtained in step (3), and hot pressed at 170 °C and 50 MPa for 20 min to obtain a paper-based solid electrolyte.

[0055] Example 5

[0056] A method for preparing a paper-based solid electrolyte with high electrical conductivity and flame retardancy comprises the following steps:

[0057] (1) Poplar chemical pulp (M w =900000 g / mol) as raw materials, lithium chloride and N,N-dimethylacetamide were added at 150 ℃ to dissolve cellulose in poplar chemical pulp. The mass ratio of poplar chemical pulp, lithium chloride and N,N-dimethylacetamide was 1:4:46. After filtration, a cellulose solution was obtained. Acryloyl chloride was added dropwise to the cellulose solution (the molar ratio of acryloyl chloride to cellulose was 2:6). The mixture was reacted in an ice-water bath (0 ℃) for 12 h. Then, lithium p-styrene trifluoromethylsulfonyl imide and 0.04 g of benzoin dimethyl ether were added to the solution in the same molar amount as acryloyl chloride. The mixture was reacted under ultraviolet light for 2 h. The solvent was removed by rotary evaporation to obtain sulfonyl imide lithiated cellulose.

[0058] (2) Add 1 g of kaolinite and 10 g of lithium hydroxide to 100 mL of hydrogen peroxide solution (30 wt%), stir at 100 °C for 16 h, and dialyze for 2 days to obtain lithiated kaolinite.

[0059] (3) The sulfonimide lithiated cellulose obtained in step (1), the lithiated kaolinite obtained in step (2), propylene carbonate, and polyethylene glycol (molecular weight 5000) were mixed in a mass ratio of 20:20:2:8, stirred, freeze-formed on an ice ethanol medium, and freeze-dried at -80°C for 24 h to obtain a composite electrolyte.

[0060] (4) 0.20 g of isophorone diisocyanate was added dropwise to the composite electrolyte obtained in step (3), and hot pressed at 180 °C and 60 MPa for 20 min to obtain a paper-based solid electrolyte.

[0061] Example 6

[0062] (1) Eucalyptus chemical pulp (M w =700000 g / mol) as raw material, lithium chloride and N,N-dimethylacetamide were added at 150 ℃ to dissolve cellulose in eucalyptus chemical pulp. The mass ratio of eucalyptus chemical pulp, lithium chloride and N,N-dimethylacetamide was 1:4:46. After filtration, a cellulose solution was obtained. Acryloyl chloride was added dropwise to the cellulose solution (the molar ratio of acryloyl chloride to cellulose was 1:6). The mixture was reacted in an ice-water bath (0 ℃) for 8 h. Then, lithium p-styrene trifluoromethylsulfonyl imide and 0.03 g of benzoin dimethyl ether were added to the solution in the same molar amount as acryloyl chloride. The mixture was reacted under ultraviolet light for 3 h. The solvent was removed by rotary evaporation to obtain lithium sulfonimide cellulose.

[0063] (2) Add 1 g of vermiculite and 10 g of lithium hydroxide to 100 mL of hydrogen peroxide solution (30 wt%), stir at 120 °C for 24 h, and dialyze for 3 days to obtain lithiated vermiculite.

[0064] (3) The sulfonimide lithiated cellulose obtained in step (1), the lithiated vermiculite obtained in step (2), propylene carbonate, and polyethylene glycol (molecular weight 5000) were mixed in a mass ratio of 20:20:1:5, stirred, frozen on an ice ethanol medium, and freeze-dried at -80°C for 60 h to obtain a composite electrolyte.

[0065] (4) 0.15 g of glutaraldehyde was added dropwise to the composite electrolyte obtained in step (3), and hot pressed at 120 °C and 80 MPa for 20 min to obtain a paper-based solid electrolyte.

[0066] Example 7

[0067] (1) Poplar chemical pulp (M w =1000000 g / mol) as raw material, lithium chloride and N,N-dimethylacetamide were added at 150 ℃ to dissolve cellulose in poplar chemical pulp. The mass ratio of poplar chemical pulp, lithium chloride and N,N-dimethylacetamide was 1:4:46. After filtration, a cellulose solution was obtained. Acryloyl chloride was added dropwise to the cellulose solution (the molar ratio of acryloyl chloride to cellulose was 8:5). The mixture was reacted in an ice-water bath (0 ℃) for 12 h. Then, lithium p-styrene trifluoromethylsulfonyl imide and 0.08 g of 2,2-azobisisobutylamidine dihydrochloride were added to the solution in the same molar amount as acryloyl chloride. The mixture was reacted under ultraviolet light for 4 h. The solvent was removed by rotary evaporation to obtain lithium sulfonimide cellulose.

[0068] (2) Add 1 g of kaolinite and 10 g of lithium hydroxide to 100 mL of hydrogen peroxide solution (30 wt%), stir at 100 °C for 24 h, and dialyze for 3 days to obtain lithiated kaolinite.

[0069] (3) The sulfonimide lithiated cellulose obtained in step (1), the lithiated kaolinite obtained in step (2), fluoroethylene carbonate, and polyethylene glycol (molecular weight 5000) were mixed in a mass ratio of 20:20:3:6, stirred, freeze-formed on an ice ethanol medium, and freeze-dried at -80°C for 96 h to obtain a composite electrolyte.

[0070] (4) 0.10 g of hexamethylene diisocyanate was added dropwise to the composite electrolyte obtained in step (3), and hot pressed at 150 °C and 80 MPa for 20 min to obtain a paper-based solid electrolyte.

[0071] Example 8

[0072] (1) Eucalyptus chemical pulp (M w =600000 g / mol) as raw material, lithium chloride and N,N-dimethylacetamide were added at 150 ℃ to dissolve cellulose in eucalyptus chemical pulp. The mass ratio of eucalyptus chemical pulp, lithium chloride and N,N-dimethylacetamide was 1:4:46. After filtration, a cellulose solution was obtained. Acryloyl chloride was added dropwise to the cellulose solution (the molar ratio of acryloyl chloride to cellulose was 2:7). The mixture was reacted in an ice-water bath (0 ℃) for 12 h. Then, lithium p-styrene trifluoromethylsulfonyl imide and 0.04 g of benzoin dimethyl ether were added to the solution in an equal molar amount to that of acryloyl chloride. The mixture was reacted under ultraviolet light for 4 h. The solvent was removed by rotary evaporation to obtain sulfonyl imide lithiated cellulose.

[0073] (2) 1 g of montmorillonite and 10 g of lithium hydroxide were added to 100 mL of hydrogen peroxide solution (30 wt%), stirred at 110 °C for 12 h, and dialyzed for 3 days to obtain lithiated montmorillonite.

[0074] (3) The sulfonimide lithiated cellulose obtained in step (1), the lithiated montmorillonite obtained in step (2), succinonitrile and polyethylene glycol (molecular weight 10,000) were mixed in a mass ratio of 20:20:3:9, stirred, freeze-formed on an ice ethanol medium, and freeze-dried at -50°C for 72 h to obtain a composite electrolyte.

[0075] (4) 0.20 g of hexamethylene diisocyanate was added dropwise to the composite electrolyte obtained in step (3), and hot pressed at 120 °C and 100 MPa for 20 min to obtain a paper-based solid electrolyte.

[0076] Example 9

[0077] (1) Poplar chemical pulp (M w =850000 g / mol) as raw material, lithium chloride and N,N-dimethylacetamide were added at 150 ℃ to dissolve cellulose in poplar chemical pulp, the mass ratio of poplar chemical pulp, lithium chloride and N,N-dimethylacetamide being 1:4:46. After filtration, a cellulose solution was obtained, to which acryloyl chloride was added dropwise (the molar ratio of acryloyl chloride to cellulose was 3:9). The mixture was reacted in an ice-water bath (0 ℃) for 12 h, and then lithium p-styrene trifluoromethylsulfonyl imide and 0.03 g of 2,2-azobisisobutylamidine dihydrochloride were added in the same molar amount as acryloyl chloride. The mixture was reacted under ultraviolet light for 4 h, and the solvent was removed by rotary evaporation to obtain sulfonyl imide lithiated cellulose.

[0078] (2) Add 1 g of montmorillonite and 10 g of lithium hydroxide to 100 mL of hydrogen peroxide solution (30 wt%), stir at 100 °C for 18 h, and dialyze for 3 days to obtain lithiated montmorillonite.

[0079] (3) The sulfonimide lithiated cellulose obtained in step (1), the lithiated montmorillonite obtained in step (2), succinonitrile and polyethylene glycol (molecular weight 10,000) were mixed in a mass ratio of 20:20:1:4, stirred, frozen on an ice ethanol medium, and freeze-dried at -80°C for 48 h to obtain a composite electrolyte.

[0080] (4) 0.10 g of glutaraldehyde was added dropwise to the composite electrolyte obtained in step (3), and hot pressed at 150 °C and 50 MPa for 20 min to obtain a paper-based solid electrolyte.

[0081] Interface impedance test: Take the paper-based electrolyte material prepared in Example 9, assemble it into a battery and then conduct impedance test, which includes the following steps: arranging the lithium iron phosphate positive electrode, paper-based electrolyte and lithium metal in the button battery, and using AC impedance test to obtain the interface impedance. The results are as follows Figure 1 shown.

[0082] Depend on Figure 1 The EIS curve of the paper-based solid electrolyte shows that its interfacial impedance is approximately 35 Ω.

[0083] Microcalorimetry: A small amount of sample (5 mg) from Example 9 was placed in a platinum crucible and heated to 700°C in a nitrogen atmosphere at a constant temperature ramp rate, resulting in complete thermal decomposition. The resulting gas was mixed with excess oxygen and then passed into a 900°C furnace for complete oxidation. The total heat release was recorded as a function of temperature. The heat release rate is shown in Figure 1. Figure 2 shown.

[0084] Depend on Figure 2 The heat release curve of the paper-based solid electrolyte shows that the peak heat release rate and heat release capacity of the paper-based solid electrolyte are only 43 W·g -1 and 53 J·g -1 ·K -1 , and its peak heat release rate can be given by Figure 2 It can be read directly. The heat release capacity is the maximum heat release rate per unit mass of material at a unit heating rate. It can be calculated from the ratio of the peak heat release rate to the heating rate. A lower peak heat release rate and heat release capacity indicate that it has a good flame retardant effect.

[0085] The calculation formula for heat release capacity is:

[0086] HRC=pHRR / β

[0087] Where HRC is the heat release capacity, pHRR is the peak heat release rate, and β is the heating rate.

[0088] Example 10

[0089] (1) Poplar chemical pulp (M w =950000 g / mol) as raw materials, lithium chloride and N,N-dimethylacetamide were added at 150 ℃ to dissolve cellulose in eucalyptus chemical pulp. The mass ratio of poplar chemical pulp, lithium chloride and N,N-dimethylacetamide was 1:4:46. After filtration, a cellulose solution was obtained. Acryloyl chloride was added dropwise to the cellulose solution (the molar ratio of acryloyl chloride to cellulose was 3:5). The mixture was reacted in an ice-water bath (0 ℃) for 10 h. Then, lithium p-styrene trifluoromethylsulfonyl imide and 0.05 g of 2,2-azobisisobutylamidine dihydrochloride were added to the solution in the same molar amount as that of acryloyl chloride. The mixture was reacted under ultraviolet light for 1 h. The solvent was removed by rotary evaporation to obtain lithium sulfonyl imide cellulose.

[0090] (2) Add 1 g of vermiculite and 10 g of lithium hydroxide to 100 mL of hydrogen peroxide solution (30 wt%), stir at 120 °C for 12 h, and dialyze for 3 days to obtain lithiated vermiculite.

[0091] (3) The sulfonimide lithiated cellulose obtained in step (1), the lithiated vermiculite obtained in step (2), fluoroethylene carbonate, and polyethylene glycol (molecular weight 10,000) were mixed in a mass ratio of 20:20:3:8, stirred, frozen on an ice ethanol medium, and freeze-dried at -80°C for 48 h to obtain a composite electrolyte.

[0092] (4) 0.10 g of isophorone diisocyanate was added dropwise to the composite electrolyte obtained in step (3), and hot pressed at 170 °C and 70 MPa for 20 min to obtain a paper-based solid electrolyte.

[0093] Example 11

[0094] Interfacial and battery impedance testing: The paper-based electrolyte materials prepared in Examples 1-10 above were assembled into batteries and then subjected to impedance testing. This included arranging the lithium iron phosphate positive electrode, paper-based electrolyte, and lithium metal in a button cell. The interfacial and battery impedances were measured using AC impedance testing. (The interfacial impedance is the starting point of the AC impedance curve, the first point in the front semicircle, where both the interfacial and battery impedances are measured simultaneously.)

[0095] Conductivity test: The paper-based solid electrolyte samples prepared in Examples 1-10 were placed between two sheets of stainless steel (the thickness of the paper-based solid electrolyte samples ranged from 0.5 to 1 mm). Electrochemical impedance spectroscopy (ECI) was performed using a Shanghai Chenhua Chi660E electrochemical workstation. The AC impedance curves of the samples were measured at a frequency of 1 MHz to 1 Hz and an oscillation voltage of 10 mV. (Both conductivity and battery impedance tests were conducted in accordance with international standards. The battery impedance test identifies the impedance between the positive electrode, electrolyte, and negative electrode in the assembled button cell due to the heterogeneous interface. Battery impedance refers to the overall impedance of current passing through the positive electrode, electrolyte, and negative electrode. The ionic conductivity of the electrolyte was tested using flat stainless steel as the conductive medium.)

[0096] The resistance results of the battery are shown in Table 1 below.

[0097] Table 1 Battery interface impedance and battery impedance test results

[0098]

[0099] Table 1 shows the interfacial impedance and battery impedance test results of the battery. As can be seen from Table 1, the paper-based solid electrolyte prepared in Example 9 has the lowest interfacial impedance and good ion conductivity. The lithium ions and ion conductive medium in the prepared Example 9 are in an optimal ratio. The cellulose and polyethylene glycol in Example 9 can achieve rapid migration of lithium ions, and the lithiated flaky montmorillonite structure can provide a bridge path for ion conduction.

[0100] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a paper-based solid electrolyte with high electrical conductivity and flame retardancy, characterized in that: The following steps are involved: 1) Using wood chemical pulp as raw material, lithium chloride and N,N-dimethylacetamide are added to dissolve the cellulose in the wood chemical pulp. Acryloyl chloride is added to the cellulose solution and reacted in an ice-water bath. Then, lithium p-styrene trifluoromethylsulfonyl imide and a photoinitiator are added and reacted under ultraviolet light. The solvent is then removed by rotary evaporation to obtain lithium sulfonyl imide cellulose. 2) Adding clay and lithium hydroxide to a hydrogen peroxide solution, mixing and stirring, and dialyzing to obtain lithiated clay; 3) mixing the sulfonimide lithiated cellulose obtained in step 1), the lithiated clay obtained in step (2), the additive, and polyethylene glycol, freeze-forming, and freeze-drying to obtain a composite electrolyte; 4) adding a crosslinking agent to the composite electrolyte obtained in step 3) and hot pressing to obtain a paper-based solid electrolyte.

2. The method for preparing a paper-based solid electrolyte having high electrical conductivity and flame retardancy according to claim 1, wherein: In step 1), the cellulose is selected from chemical pulp of eucalyptus and poplar, and has a molecular weight of 400,000-1,000,000.

3. The method for preparing a paper-based solid electrolyte having high electrical conductivity and flame retardancy according to claim 1, wherein: In step 1), the molar ratio of acryloyl chloride to cellulose is 10:1 to 1:10; and the ice bath time is 6 to 12 h.

4. The method for preparing a paper-based solid electrolyte having high electrical conductivity and flame retardancy according to claim 1, wherein: In step 1), the photoinitiator is selected from one or more of benzoin dimethyl ether and 2,2-azobisisobutylamidine dihydrochloride.

5. The method for preparing a paper-based solid electrolyte having high electrical conductivity and flame retardancy according to claim 1, wherein: In step 2), the clay is selected from one or more of lingonite, montmorillonite and vermiculite; the stirring temperature is 50-120° C., and the stirring time is 6-24 h.

6. The method for preparing a paper-based solid electrolyte with high electrical conductivity and flame retardancy according to claim 1, wherein: In step 2), the additive is selected from one or more of succinonitrile, ethylene carbonate, fluoroethylene carbonate and propylene carbonate.

7. The method for preparing a paper-based solid electrolyte with high electrical conductivity and flame retardancy according to claim 1, wherein: In step 3), the molecular weight of polyethylene glycol is 200-10,000; and the mass ratio of sulfonimide lithiated cellulose, lithiated clay, additive, and polyethylene glycol is 20:20:1:2-20:20:5:

10.

8. The method for preparing a paper-based solid electrolyte with high electrical conductivity and flame retardancy according to claim 1, wherein: In step 4), the cross-linking agent is selected from one or more of glutaraldehyde, hexamethylene diisocyanate, and isophorone diisocyanate; the hot pressing temperature is 120-180° C., and the pressure is 50-100 MPa.

9. A paper-based solid electrolyte with high electrical conductivity and flame retardancy, characterized in that: The paper-based solid electrolyte with high conductivity and flame retardant properties is prepared according to the preparation method of any one of claims 1 to 8.

10. Use of the paper-based solid electrolyte according to claim 9 in lithium battery electrodes.

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