A copper-coordinated cationic cellulose nanofibril solid-state electrolyte, and a preparation method and application thereof

Abstract

The application discloses a kind of copper coordination cation cellulose nanofibril solid electrolyte and preparation method and application thereof.The preparation method of the solid electrolyte includes the following steps: (1) cellulose nanofibril CNF is dissolved into NaOH / urea aqueous solution, then glycidyltrimethylammonium chloride is added to carry out etherification reaction, to obtain cationic cellulose nanofibril;(2) cationic cellulose nanofibril is immersed into saturated Cu 2+ Containing NaOH solution to make it coordinate, to obtain copper coordination cation cellulose nanofibril suspension;(3) the dispersion medium of copper coordination cation cellulose nanofibril suspension is replaced by anhydrous acetonitrile, then lithium salt is added, after being mixed uniformly, it is cast into mould, and the copper coordination cation cellulose nanofibril solid electrolyte is obtained by drying.The battery ion conductivity of the solid electrolyte prepared by using the application is high, and the mechanical property and electrochemical performance are excellent.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries, and in particular relates to a copper coordinated cationic cellulose nanofibril solid electrolyte and a preparation method and application thereof. Background Art

[0002] Among various electrochemical energy storage devices, lithium-ion batteries have the advantages of low self-discharge rate, large charge and discharge rate, high energy density, and long cycle life. They are still the ideal power source for electric vehicles, hybrid vehicles, portable electronic products and even large-scale energy storage systems.

[0003] The electrolytes commonly used in lithium-ion batteries are organic solvent-based liquid electrolytes, which are usually composed of organic solvents, lithium salts, and additives. Although such electrolytes have advantages such as high ionic conductivity and good interface wettability, the energy density of commercial liquid lithium-ion batteries (about 260W·h·kg -1 ) has approached the theoretical limit and is difficult to improve further; at the same time, organic solvents are easy to leak and burn, making the battery prone to accidents such as combustion or explosion during overcharging or short circuiting, endangering the personal and property safety of users.

[0004] Polymer solid electrolytes have the characteristics of no organic solvents and can inhibit the growth of lithium dendrites, which can improve the safety performance of lithium-ion batteries. The most commonly used polymer solid electrolyte raw material is polyethylene oxide (PEO), which binds to Li through ether bonds in the amorphous region. + Binding / dissociation complete Li + However, PEO solid electrolytes have defects such as low ionic conductivity, poor mechanical properties, and high glass transition temperature due to high crystallinity at room temperature. Their inability to degrade naturally and their non-renewability also go against the concept of sustainable green production, making them difficult to apply directly in actual production.

[0005] Therefore, it is necessary to select an environmentally friendly material that has excellent performance and green environmental protection properties to prepare solid electrolytes. Summary of the Invention

[0006] The primary purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a method for preparing a copper-coordinated cationic cellulose nanofibril solid electrolyte.

[0007] Another object of the present invention is to provide a copper-coordinated cationic cellulose nanofibril solid electrolyte prepared by the method.

[0008] Another object of the present invention is to provide an application of the copper-coordinated cationic cellulose nanofibril solid electrolyte.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] A preparation method of a copper-coordinated cationic cellulose nanofibril solid-state electrolyte, comprising the following steps:

[0011] (1) stirring and dissolving cellulose nanofibrils (CNF) into a NaOH / urea aqueous solution, then adding glycidyltrimethylammonium chloride as an etherifying agent to introduce cationic groups into the cellulose nanofibrils, and then precipitating the cellulose nanofibrils using ethanol to obtain cationic cellulose nanofibrils;

[0012] (2) immersing the cationic cellulose nanofibrils obtained in step (1) into a saturated Cu 2+ -containing NaOH solution to coordinate with Cu 2+ in the solution to obtain a copper-coordinated cationic cellulose nanofibril suspension;

[0013] (3) centrifuging the copper-coordinated cationic cellulose nanofibril suspension obtained in step (2) and using anhydrous acetonitrile as a new dispersion medium of the copper-coordinated cationic cellulose nanofibrils to obtain a copper-coordinated cationic cellulose nanofibril-anhydrous acetonitrile system;

[0014] (4) adding a lithium salt into the copper-coordinated cationic cellulose nanofibril-anhydrous acetonitrile system obtained in step (3) to stir and mix uniformly, and then casting into a mold to dry to obtain the copper-coordinated cationic cellulose nanofibril solid-state electrolyte.

[0015] The preparation method of the copper-coordinated cationic cellulose nanofibril solid-state electrolyte specifically comprises the following steps:

[0016] S1, cellulose nanofibrils (CNF) are added into a pre-cooled NaOH / urea aqueous solution to -4℃-0℃, after stirring and mixing, the solution is placed in a refrigerator at -10℃-4℃, then taken out and placed at room temperature to stir until the solution is thawed to form a transparent solution; an aqueous solution of glycidyltrimethylammonium chloride (as an etherifying agent) is added to the transparent solution, and the reaction is carried out under stirring at 30℃-50℃, after the reaction is completed, glacial acetic acid is added to terminate the reaction, and anhydrous ethanol (excess) is added to completely precipitate the product, and the precipitate is taken out and washed to obtain cationic cellulose nanofibrils;

[0017] S2, copper wire is placed in a NaOH solution, then cationic cellulose nanofibrils obtained in step S1 are added, soaked and stirred to coordinate with Cu 2+ in the solution to react, after the reaction is completed, water washing is performed to obtain a copper-coordinated cationic cellulose nanofibril suspension;

[0018] S3, pour the copper coordination cation cellulose nanofibril suspension obtained in step S2 into a centrifuge tube, centrifuge, discard the supernatant; then add anhydrous acetonitrile, centrifuge again, discard the supernatant, repeat the operation of adding anhydrous acetonitrile three times or more until the water is completely replaced by anhydrous acetonitrile, to obtain a copper coordination cation cellulose nanofibril-anhydrous acetonitrile system;

[0019] S4, add a lithium salt to the copper coordination cation cellulose nanofibril-anhydrous acetonitrile system obtained in step S3, stir to mix uniformly, then cast into a mold, dry to obtain the copper coordination cation cellulose nanofibril solid-state electrolyte.

[0020] The amount of cellulose nanofibril (CNF) used in step S1 is 3-5 g of absolutely dry cellulose nanofibril per 100 mL of NaOH / urea aqueous solution; preferably 4 g of absolutely dry cellulose nanofibril per 100 mL of NaOH / urea aqueous solution.

[0021] In step S1, the pre-cooling temperature is preferably 0°C.

[0022] The concentration of NaOH in the NaOH / urea aqueous solution in step S1 is 6-7% by mass (preferably 7% by mass), and the concentration of urea is 10-14% by mass (preferably 12% by mass).

[0023] The stirring and mixing time in step S1 is 5-15 min; preferably 10 min.

[0024] The freezing temperature in step S1 is preferably -4°C.

[0025] The freezing time in step S1 is 3-5 h; preferably 4 h.

[0026] The concentration of the glycidyltrimethylammonium chloride aqueous solution in step S1 is 15-25% by mass; preferably 20% by mass.

[0027] The mass ratio of cellulose nanofibril (CNF) to glycidyltrimethylammonium chloride in step S1 is 1:3-5; preferably 1:4.

[0028] The stirring reaction temperature in step S1 is preferably 40°C.

[0029] In step S1, the reaction time under stirring conditions is 1-3 h; preferably 2 h.

[0030] The amount of glacial acetic acid added in step S1 is added according to actual needs to terminate the reaction; preferably, the molar ratio of the total amount of NaOH and urea to the molar amount of glacial acetic acid is 1:1.5-2.5; further preferably, the molar ratio of the total amount of NaOH and urea to the molar amount of glacial acetic acid is 1:1.53-1.55.

[0031] The washing in step S1 is washing with deionized water; preferably, the deionized water is washed for more than 3 times until no other liquid remains.

[0032] The concentration of the NaOH solution in step S2 is 8-12% by mass; preferably, the concentration is 10% by mass.

[0033] The amount of the NaOH solution in step S2 is calculated as 30-50 mL of the NaOH solution per gram of copper wire; preferably, the amount is calculated as 40 mL of the NaOH solution per gram of copper wire.

[0034] The soaking time in step S2 is 3-7 days; preferably, the time is 3 days.

[0035] The washing in step S2 is washing with deionized water for more than 3 times until no alkali solution remains.

[0036] The centrifugation condition in step S3 is 10000 rpm for 5-8 min.

[0037] The lithium salt in step S4 is preferably LiClO4.

[0038] The mass ratio of the lithium salt to the copper-coordinated cationic cellulose nanofilament in the copper-coordinated cationic cellulose nanofilament-anhydrous acetonitrile system in step S4 is 1:4-8; preferably, the mass ratio is 1:6.

[0039] In step S4, the lithium salt can be first dissolved in anhydrous acetonitrile to form a lithium salt solution, and then added to the copper-coordinated cationic cellulose nanofilament-anhydrous acetonitrile system.

[0040] The mold in step S4 is preferably a polytetrafluoroethylene mold.

[0041] The drying in step S4 is vacuum drying, preferably, 50-60°C vacuum drying for 24 h; further preferably, 50°C vacuum drying for 24 h.

[0042] A copper-coordinated cationic cellulose nanofilament solid-state electrolyte prepared by the method of any one of the above.

[0043] The application of the copper-coordinated cationic cellulose nanofilament solid-state electrolyte in preparing energy storage materials.

[0044] The application of the copper-coordinated cation cellulose nanofibril solid electrolyte in the preparation of lithium metal solid-state batteries (solid-state lithium batteries, all-solid-state batteries).

[0045] The application of the copper-coordinated cation cellulose nanofibril solid electrolyte in electric vehicles (electric bicycles, electric cars, etc.), energy storage devices, and portable devices (laptops, smartphones, etc.).

[0046] The present application has the following advantages and effects compared with the prior art:

[0047] (1) The present application provides a copper-coordinated cation cellulose nanofibril solid electrolyte, which is mainly composed of copper-coordinated cation cellulose nanofibrils and lithium perchlorate (LiClO4). The solid electrolyte has excellent mechanical properties and electrochemical properties, can effectively inhibit lithium dendrite growth, and the raw materials meet the requirements of green environmental protection and natural degradation.

[0048] (2) The copper-coordinated cation cellulose nanofibril in the present application is first obtained by homogeneously etherifying cellulose nanofibrils with glycidyltrimethylammonium chloride GTMAC to obtain cationic cellulose nanofibrils, and then using Cu 2+ The copper-coordinated cation cellulose nanofibril is obtained by soaking in saturated NaOH solution.

[0049] (3) The copper-coordinated cation cellulose nanofibril solid electrolyte prepared by the present application improves the defects of common polymer solid electrolytes, such as low room temperature ionic conductivity and poor mechanical properties. Although ordinary cellulose nanofibrils can provide high mechanical strength required by solid electrolytes, they often form densely arranged molecular chains due to the presence of abundant hydroxyl groups and a large number of hydrogen bonds, which hinders the transmission of Li + The cationic functional groups grafted on the surface of the copper-coordinated cation cellulose nanofibril and the Cu 2+ coordination occupy a large number of surface hydroxyl groups, reducing the number of hydrogen bonds, which helps the dissociation and transportation of lithium ions, thereby increasing the migration number of Li + The room temperature ionic conductivity of the solid electrolyte can reach 7.29 x 10 -5 S / cm, and the electrochemical stability window can reach 4.58 V.

[0050] (4) The present application uses cellulose nanofibrils to completely replace PEO as the raw material for the preparation of solid electrolytes, which has the advantages of being renewable and naturally degradable, and conforms to the green production concept of sustainable development.

[0051] (5) Common polymer solid-state electrolyte has low room temperature conductivity, so it needs to improve the battery operating temperature, the copper coordination cation cellulose nanofibril solid-state electrolyte prepared by the application has wider thermal stability than the common PEO-based solid-state electrolyte, and still maintains structural stability at 150℃ without electrolyte melting, thereby improving the practical applicable temperature range of lithium batteries. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 The alternating current impedance diagram of the solid-state electrolyte prepared for Example 1 and Comparative Example 1.

[0053] Figure 2 The electrochemical stability window diagram of the lithium sheet / solid-state electrolyte / steel sheet button cell assembled by the solid-state electrolyte prepared for Example 1 and Comparative Example 1.

[0054] Figure 3 The cycle charge-discharge (charge-discharge rate is 0.5C) test result diagram of the full battery assembled by using the solid-state electrolyte prepared for Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0055] The application will be further described in conjunction with the examples below, but the embodiments of the application are not limited thereto. Unless otherwise specified, the reagents, methods and equipment used in the application are the conventional reagents, methods and equipment in the technical field. The test methods in the following examples without specific experimental conditions are usually carried out according to the conventional experimental conditions. Unless otherwise specified, the reagents and raw materials used in the application can be obtained by marketing.

[0056] The materials involved in the following examples and comparative examples of the application are as follows:

[0057] The cellulose nanofibril CNF (suspension) used is purchased from Zhejiang Jingahao Green Nanomaterials Co., Ltd., and the preparation method is high-pressure homogenization method, and the solid content is 2wt%;

[0058] The sodium hydroxide (≥97%), urea (≥99.5%), glycidyltrimethylammonium chloride (≥95%) and anhydrous ethanol (≥99.5%) used are all purchased from Shanghai Aldrich Biochemical Technology Co., Ltd.;

[0059] The copper wire used is obtained by cutting the copper sheet (≥99.5%) purchased from Shanghai Maikelin Biochemical Technology Co., Ltd., and the diameter is 1mm;

[0060] The lithium perchlorate (≥95.0%) used is purchased from Sigma Aldrich (Shanghai) Trading Co., Ltd.

[0061] The molecular weight M V= 600000, purchased from Shanghai Aldrin Biochemical Technology Co., Ltd.

[0062] Example 1

[0063] (1) NaOH and urea were added to deionized water to prepare a 7wt% NaOH / 12wt% urea aqueous solution (i.e., the mass concentration of NaOH in the NaOH / urea aqueous solution was 7%, and the mass concentration of urea was 12%), and the solution was pre-cooled to 0°C. Then 4g of cellulose nanofibril CNF with absolute dry mass was added to 100mL of the above solution, stirred at room temperature for 10min, and then placed in a-4°C refrigerator for 4h. After that, intermittent stirring was carried out at room temperature until the solution thawed to obtain a transparent solution.

[0064] (2) 16g of glycidyltrimethylammonium chloride powder was added to 64mL of deionized water, stirred until completely dissolved, and then poured into the CNF-containing NaOH / urea aqueous solution prepared in step (1). The solution was placed in a constant temperature heating magnetic stirrer at 40°C. After 2h, 35g of glacial acetic acid was added to terminate the reaction, and then deionized water was used to wash the cellulose completely precipitated three times to obtain cationic cellulose nanofibril.

[0065] (3) A 200mL 10% mass fraction NaOH aqueous solution (solvent: deionized water) was prepared, and 5g of copper wire was added. Then the cationic cellulose nanofibril prepared in step (2) was added, and the solution was stirred and soaked in a magnetic stirrer for 3 days. After the reaction was completed, the solution was washed with deionized water three times to obtain a copper-coordinated cationic cellulose nanofibril suspension.

[0066] (4) The copper-coordinated cationic cellulose nanofibril suspension prepared in step (3) was poured into a centrifuge tube and placed in a centrifuge. The speed was set to 10000rpm, and the centrifugation time was 5min. The machine was started for centrifugation. After centrifugation, the supernatant in the centrifuge tube was poured out, and anhydrous acetonitrile with the same mass as the poured supernatant was poured into the lower system. The above operation was repeated three times until the deionized water was completely replaced by anhydrous acetonitrile. The solid content of the copper-coordinated cationic cellulose nanofibril-anhydrous acetonitrile system was measured.

[0067] (5) 0.68g of LiClO4 powder was weighed and added to the copper-coordinated cationic cellulose nanofibril-anhydrous acetonitrile system obtained in step (4) (the absolute dry mass of the copper-coordinated cationic cellulose nanofibril in the system was 4g). The mixture was stirred uniformly and poured into a polytetrafluoroethylene mold. The mold was placed in a 50°C vacuum drying oven for 24h to obtain a copper-coordinated cationic cellulose nanofibril solid-state electrolyte.

[0068] Example 2

[0069] The difference from Example 1 is only that the mass of glycidyltrimethylammonium chloride powder in step (2) is adjusted to 12 g, and other step parameters and conditions are the same as those of Example 1.

[0070] Example 3

[0071] The difference from Example 1 is only that the mass of glycidyltrimethylammonium chloride powder in step (2) is adjusted to 20 g, and other step parameters and conditions are the same as those of Example 1.

[0072] Example 4

[0073] The difference from Example 1 is only that the soaking time of cationic cellulose nanofibrils in the solution in step (3) is adjusted to 5 days, and other step parameters and conditions are the same as those of Example 1.

[0074] Example 5

[0075] The difference from Example 1 is only that the soaking time of cationic cellulose nanofibrils in the solution in step (3) is adjusted to 7 days, and other step parameters and conditions are the same as those of Example 1.

[0076] Example 6

[0077] The difference from Example 1 is only that the mass of LiClO4 powder in step (5) is adjusted to 0.5 g, and other step parameters and conditions are the same as those of Example 1.

[0078] Example 7

[0079] The difference from Example 1 is only that the mass of LiClO4 powder in step (5) is adjusted to 1.0 g, and other step parameters and conditions are the same as those of Example 1.

[0080] Comparative Example 1

[0081] (1) Preparation of PEO and LiClO4 with a molar ratio of EO:Li of 16:1, specifically: 2.82 g of PEO and 0.43 g of LiClO4 were weighed and added to 30 mL of anhydrous acetonitrile solvent, and placed in a constant temperature heating magnetic stirrer at 40°C for stirring for 12 h until the mixture was uniform. Then the obtained mixed solution was poured into a polytetrafluoroethylene mold, and placed in a 50°C vacuum drying box for vacuum drying for 24 h to obtain a PEO polymer solid-state electrolyte.

[0082] Comparative Example 2

[0083] (1) NaOH and urea were added to deionized water to prepare a 7wt% NaOH / 12wt% urea aqueous solution (i.e., the mass concentration of NaOH in the NaOH / urea aqueous solution was 7%, and the mass concentration of urea was 12%), and the solution was pre-cooled to 0°C. Then 4 g of cellulose nanofibril CNF with an absolute dry mass was added to 100 mL of the above solution, stirred at room temperature for 10 min, placed in a -4°C refrigerator for 4 h, and then intermittent stirring was performed at room temperature until the solution thawed to obtain a transparent solution.

[0084] (2) 16 g of glycidyltrimethylammonium chloride powder was added to 64 mL of deionized water, stirred until completely dissolved, and then poured into the CNF-containing NaOH / urea aqueous solution prepared in step (1) and placed in a constant temperature heating magnetic stirrer at 40°C. After 2 h, 35 g of glacial acetic acid was added to terminate the reaction, and deionized water was used to wash the cellulose completely precipitated with anhydrous ethanol 3 times to obtain a cationic cellulose nanofibril suspension.

[0085] (3) The cationic cellulose nanofibril suspension prepared in step (2) was poured into a centrifuge tube and placed in a centrifuge, and the speed was set to 10,000 rpm and the centrifugation time was set to 5 min. The machine was started to perform centrifugation. After centrifugation, the supernatant in the centrifuge tube was poured out, and anhydrous acetonitrile with the same mass as the poured supernatant was poured into the lower system. Centrifugation was performed again, and the process was repeated three times until the deionized water was completely replaced by anhydrous acetonitrile. The solid content of the cationic cellulose nanofibril-anhydrous acetonitrile system was measured.

[0086] (4) 0.68 g of LiClO4 powder was weighed and added to the cationic cellulose nanofibril-anhydrous acetonitrile system obtained in step (3) (the absolute dry mass of cationic cellulose nanofibril in the system was 4 g), stirred uniformly, and poured into a polytetrafluoroethylene mold. The mold was placed in a 50°C vacuum drying oven for vacuum drying for 24 h to obtain a cationic cellulose nanofibril solid-state electrolyte.

[0087] Comparative Example 3

[0088] (1) A 200 mL 10% mass fraction NaOH aqueous solution was prepared, and 5 g of copper wire was added. Then 4 g of cellulose nanofibril was added, placed in a magnetic stirrer, stirred and soaked for 3 days. After the reaction was completed, the solution was washed with deionized water 3 times to obtain a copper-coordinated cellulose nanofibril suspension.

[0089] (2) The copper-coordinated cellulose nanofibril suspension prepared in step (1) was poured into a centrifuge tube and placed in a centrifuge, and the speed was set to 10000 rpm and the centrifugation time was set to 5 min. The machine was started for centrifugation. After the end, the supernatant in the centrifuge tube was poured out, and anhydrous acetonitrile equal in mass to the poured-out supernatant was poured into the lower system, and the centrifugation operation was repeated again. The above operation was repeated three times until the deionized water was completely replaced by anhydrous acetonitrile. The solid content of the copper-coordinated cationic cellulose nanofibril-anhydrous acetonitrile system was measured.

[0090] (3) 0.68 g of LiClO4 powder was weighed and added to the copper-coordinated cellulose nanofibril-anhydrous acetonitrile system obtained in step (2) (the absolute dry mass of the cationic cellulose nanofibril in the system was 4 g), stirred uniformly and poured into a polytetrafluoroethylene mold, and placed in a 50°C vacuum drying oven for vacuum drying for 24 h to obtain a copper-coordinated cationic cellulose nanofibril solid-state electrolyte.

[0091] Effect implementation example

[0092] 1. The solid-state electrolytes prepared in the above Examples 1-7 and Comparative Examples 1-3 were punched into 16 mm diameter round pieces, and assembled into steel sheet / solid-state electrolyte / steel sheet button cells (button cell shell model CR2032, steel sheet diameter 16 mm, thickness 0.5 mm and 1 mm) in a glove box to test their ionic conductivity (test temperature 30°C, 60°C). The test frequency was 0.1 MHz-0.1 Hz. The experiment was set up in triplicate.

[0093] 2. The solid-state electrolytes prepared in the above Examples 1-7 and Comparative Examples 1-3 were punched into 16 mm diameter round pieces, and assembled into lithium sheet / solid-state electrolyte / steel sheet button cells (button cell shell model CR2032, lithium sheet diameter 16 mm, thickness 0.5 mm; steel sheet diameter 16 mm, thickness 1 mm) in a glove box to test their electrochemical stability window. The test potential voltage was 2.0V-7.0V, and the scan rate was set to 10 mV / s. The experiment was set up in triplicate.

[0094] 3. The solid-state electrolytes prepared in the above Examples 1-7 and Comparative Examples 1-3 were punched into 16 mm diameter round pieces, and assembled into lithium sheet / solid-state electrolyte / lithium iron phosphate positive electrode button cells (button cell shell model CR2032, lithium sheet diameter 16 mm, thickness 0.5 mm; positive electrode sheet diameter 12 mm) in a glove box for cycle performance testing using a battery cycle system. The test voltage range was 2.0V to 4.2V, and the charge and discharge rate was 0.5C. The experiment was set up in triplicate.

[0095] The test results of Examples 1-7 and Comparative Examples 1-3 are shown in Table 1 and Table 2 below. The AC impedance diagram of the solid-state electrolyte prepared in Example 1 and Comparative Example 1 at 30℃ is shown in Figure 1 , the electrochemical stability window diagram of the lithium sheet / solid-state electrolyte / steel sheet button cell assembled is shown in Figure 2 , and the cyclic charge-discharge (charge-discharge rate is 0.5C) test results of the lithium sheet / solid-state electrolyte / lithium iron phosphate positive electrode button cell assembled are shown in Figure 3 .

[0096] Table 1 Test results of solid-state electrolyte performance of Examples 1-7

[0097]

[0098] Table 2 Test results of solid-state electrolyte performance of Comparative Examples 1-3

[0099]

[0100]

[0101] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for preparing a copper-coordinated cationic cellulose nanofibril solid electrolyte, characterized in that: The steps include: (1) cellulose nanofibrils are stirred and dissolved in a NaOH / urea aqueous solution, and then glycidyl trimethylammonium chloride is added as an etherifying agent to introduce cationic groups into the cellulose nanofibrils, which are then precipitated using ethanol to obtain cationic cellulose nanofibrils; (2) Immerse the cationic cellulose nanofibrils obtained in step (1) in a saturated Cu 2+ NaOH solution, so that it can be combined with Cu 2+ Coordination occurs to obtain a copper-coordinated cationic cellulose nanofibril suspension; (3) centrifuging the copper-coordinated cationic cellulose nanofibril suspension obtained in step (2), and using anhydrous acetonitrile as a new dispersion medium for the copper-coordinated cationic cellulose nanofibrils to obtain a copper-coordinated cationic cellulose nanofibril-anhydrous acetonitrile system; (4) adding lithium salt to the copper coordinated cationic cellulose nanofibril-anhydrous acetonitrile system obtained in step (3), stirring and mixing evenly, casting the mixture into a mold, and drying the mixture to obtain the copper coordinated cationic cellulose nanofibril solid electrolyte.

2. The method according to claim 1, characterized in that The specific steps include: S1. Adding cellulose nanofibrils to a NaOH / urea aqueous solution precooled to -4°C to 0°C, stirring and mixing, freezing the solution in a refrigerator at -10°C to -4°C, then taking it out and stirring it at room temperature until the solution thaws to form a transparent solution; adding a glycidyltrimethylammonium chloride aqueous solution to the transparent solution, reacting at 30°C to 50°C under stirring conditions, and adding glacial acetic acid to terminate the reaction after the reaction is completed. Then, adding anhydrous ethanol to completely precipitate the product, and washing the precipitate to obtain cationic cellulose nanofibrils; S2, put the copper wire into NaOH solution, then add the cationic cellulose nanofibrils obtained in step S1, soak and stir to make them mix with the Cu in the solution. 2+ The coordination reaction occurs, and after the reaction is completed, the suspension is washed with water to obtain a copper-coordinated cationic cellulose nanofiber suspension; S3. Pour the copper-coordinated cationic cellulose nanofibril suspension obtained in step S2 into a centrifuge tube, centrifuge, and discard the supernatant; then add anhydrous acetonitrile, centrifuge again, discard the supernatant, and repeat the process of adding anhydrous acetonitrile three or more times until the water is completely replaced by anhydrous acetonitrile, thereby obtaining a copper-coordinated cationic cellulose nanofibril-anhydrous acetonitrile system; S4. Adding lithium salt to the copper coordinated cationic cellulose nanofibril-anhydrous acetonitrile system obtained in step S3, stirring and mixing evenly, casting the mixture into a mold, and drying to obtain the copper coordinated cationic cellulose nanofibril solid electrolyte.

3. The method according to claim 2, wherein: The concentration of NaOH in the NaOH / urea aqueous solution in step S1 is 6-7% by mass, and the concentration of urea is 10-14% by mass; The concentration of the glycidyltrimethylammonium chloride aqueous solution in step S1 is 15-25% by mass; The mass ratio of the cellulose nanofibrils to glycidyltrimethylammonium chloride in step S1 is 1:3-5; The lithium salt described in step S4 is LiClO4; The mass ratio of the lithium salt in step S4 to the copper-coordinated cationic cellulose nanofibrils in the copper-coordinated cationic cellulose nanofibrils-anhydrous acetonitrile system is 1:4-8.

4. The method according to claim 3, wherein: The concentration of NaOH in the NaOH / urea aqueous solution in step S1 is 7% by mass, and the concentration of urea is 12% by mass; The concentration of the glycidyltrimethylammonium chloride aqueous solution in step S1 is 20% by mass; The mass ratio of the cellulose nanofibrils to glycidyltrimethylammonium chloride in step S1 is 1:4; The mass ratio of the lithium salt described in step S4 to the copper-coordinated cationic cellulose nanofibrils in the copper-coordinated cationic cellulose nanofibrils-anhydrous acetonitrile system is 1:

6.

5. The method according to claim 2, wherein: The concentration of the NaOH solution in step S2 is 8-12% by mass; The amount of NaOH solution used in step S2 is calculated based on 30-50 mL of NaOH solution per gram of copper wire; The soaking time in step S2 is 3 to 7 days.

6. The method according to claim 2, wherein: The stirring and mixing time in step S1 is 5 to 15 minutes; The freezing time in step S1 is 3 to 5 hours; In step S1, the reaction time under stirring conditions is 1 to 3 hours; The washing in step S1 is performed using deionized water; The washing in step S2 is washing with deionized water for more than 3 times until no alkali solution remains; The centrifugation conditions in step S3 are: centrifugation at 10,000 rpm for 5 to 8 minutes; The drying conditions described in step S4 are: vacuum drying at 50-60° C. for 24 h.

7. A copper-coordinated cationic cellulose nanofibril solid electrolyte, characterized by: It is prepared by the method according to any one of claims 1 to 6.

8. Use of the copper-coordinated cationic cellulose nanofibril solid electrolyte according to claim 7 in the preparation of energy storage materials.

9. Use of the copper-coordinated cationic cellulose nanofibril solid electrolyte according to claim 7 in the preparation of lithium metal solid-state batteries.

10. Use of the copper-coordinated cationic cellulose nanofibril solid electrolyte according to claim 7 in electric vehicles, energy storage devices, and / or portable devices.

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