A cellulose diacetate-based composite solid electrolyte and a preparation method and application thereof

Abstract

This invention belongs to the field of composite solid electrolyte technology, specifically relating to a cellulose diacetate-based composite solid electrolyte, its preparation method, and its application. The method includes dissolving cellulose diacetate in an ionic liquid to obtain solution A; introducing a lithium salt into solution A to obtain a mixed solution B; adding a polymerizable monomer and a thermal initiator to solution B to obtain a mixed solution C; adding ion-conducting ceramic nanofibers to mixed solution C to obtain an electrolyte slurry; and thermally polymerizing to form a film. The combination of high-strength cellulose diacetate and ceramic nanofibers in this composite solid electrolyte significantly increases the mechanical strength of the electrolyte, effectively resisting lithium dendrite growth during charge and discharge and preventing penetration. Simultaneously, the ionic liquid acts as an "ion bridge," facilitating the formation of a continuous organic-inorganic interface and promoting efficient ion migration at the cellulose diacetate-ceramic interface, thereby improving the battery's ionic conductivity and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of composite solid electrolyte technology, specifically relating to a cellulose diacetate-based composite solid electrolyte, its preparation method, and its application. Background Technology

[0002] Solid-state lithium metal batteries have attracted significant attention from both academia and industry due to their high safety and energy density. As a key component of solid-state batteries, the performance of the solid electrolyte directly determines the ionic conductivity and cycle stability. Among the several mainstream solid-state electrolytes currently under research, composite electrolytes, composed of organic polymers and inorganic ceramics, combine the interfacial compatibility and ease of processing of organic electrolytes with the high ionic conductivity and mechanical strength of inorganic electrolytes, making them a research hotspot in the field of solid-state lithium batteries.

[0003] Currently, the polymer matrices used in composite electrolytes are mostly polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene, polyacrylonitrile, and polymethyl methacrylate, etc. The preparation method often involves introducing ceramic particles into the polymer matrix to form a composite solid electrolyte. However, these composite electrolytes can no longer meet the requirements for long cycle life and suppression of lithium dendrites: on the one hand, due to the limitation of the amount of ceramic added, the mechanical strength of the electrolyte is insufficient to resist the growth of lithium dendrites during continuous charging and discharging; on the other hand, the contact between ceramic particles and polymers is a "point contact," hindering ion transport at the organic-inorganic interface. Furthermore, due to intrinsic incompatibility, some ceramic-polymer interfaces cannot conduct ions, making the ionic conductivity insufficient for application requirements.

[0004] Cellulose is a natural high-molecular-weight polysaccharide composed of glucose units linked by β-1,4-glycosidic bonds. It has advantages such as low cost and renewability. Abundant polar groups (such as -OH, -O-) endow cellulose with ion conduction ability, but the dense molecular chain and strong hydrogen bond network reduce Li⁺ transport kinetics and processability. Summary of the Invention

[0005] The purpose of this invention is to provide a cellulose diacetate-based composite solid electrolyte, its preparation method, and its application. The combination of high-strength cellulose diacetate and ceramic nanofibers in the cellulose diacetate-based composite solid electrolyte can significantly increase the mechanical strength of the electrolyte, effectively resisting lithium dendrite growth during charging and discharging and preventing penetration. At the same time, the ionic liquid, as an "ion bridge," helps to form a continuous organic-inorganic interface, promoting efficient ion migration at the cellulose diacetate-ceramic interface, thereby improving the ionic conductivity and cycle stability of the battery.

[0006] To achieve the above objectives, the present invention provides a method for preparing a cellulose diacetate-based composite solid electrolyte, comprising the following steps:

[0007] S1. Dissolve cellulose diacetate in an ionic liquid to obtain solution A; the degree of acetyl substitution of the cellulose diacetate is 2.3~2.4, and the concentration of the cellulose diacetate is 10~15 wt%.

[0008] S2. Add lithium salt to solution A to dissolve and obtain solution B, wherein the lithium salt is 5-15 wt% of the mass of cellulose diacetate.

[0009] S3. Add the polymerizing monomer and thermal initiator to solution B to obtain solution C; the polymerizing monomer is polyethylene glycol methacrylate;

[0010] S4. Add ceramic nanofibers to solution C and stir thoroughly to obtain electrolyte slurry;

[0011] S5. The electrolyte slurry is thermally polymerized into a film to obtain a cellulose diacetate-based composite solid electrolyte.

[0012] As a preferred embodiment of the preparation method of the cellulose diacetate-based composite solid electrolyte of the present invention: in step S1, the ionic liquid is one or more of N-methyl-N-propylpyrrolidine bisfluorosulfonylimide, 1-butyl-1-methylpiperidine bis(trifluoromethanesulfonylimide) salt, and 1-butyl-4-methylpyridine bis(trifluoromethanesulfonylimide).

[0013] As a preferred embodiment of the preparation method of the cellulose diacetate-based composite solid electrolyte of the present invention: in step S2, the lithium salt is one or more of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide.

[0014] As a preferred embodiment of the preparation method of the cellulose diacetate-based composite solid electrolyte of the present invention, the mass ratio of ceramic nanofibers to cellulose diacetate is 1:1~3; the ceramic nanofibers are aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers.

[0015] As a preferred embodiment of the preparation method of the cellulose diacetate-based composite solid electrolyte of the present invention: in step S3, the mass of the polymeric monomer is 10-12 wt% of solution C, and the mass of the thermal initiator is 1-2 wt% of the polymeric monomer.

[0016] As a preferred embodiment of the preparation method of the cellulose diacetate-based composite solid electrolyte of the present invention: in step S3, the thermal initiator is benzoyl peroxide.

[0017] As a preferred embodiment of the preparation method of the cellulose diacetate-based composite solid electrolyte of the present invention, the ceramic nanofibers have a fiber diameter of 200~500 nm.

[0018] As a preferred embodiment of the preparation method of the cellulose diacetate-based composite solid electrolyte of the present invention: in step S5, the temperature of the thermal polymerization is 60~80 ℃.

[0019] In step S4, the ion-conducting ceramic nanofibers are aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers prepared with reference to "Preparation of Lithium Lanthanum Zirconium Oxide Nanofiber Membranes and Their Application in Solid-State Lithium Batteries" (Chen Qiaojing. Preparation of Lithium Lanthanum Zirconium Oxide Nanofiber Membranes and Their Application in Solid-State Lithium Batteries [D]. Donghua University, 2022.).

[0020] The present invention also provides a method for preparing the aforementioned cellulose diacetate-based composite solid electrolyte. The composite solid electrolyte is composed of high-strength cellulose diacetate and ceramic nanofibers, both of which are ion conductors.

[0021] Applications of the above-mentioned composite solid electrolyte: This cellulose diacetate-based composite solid electrolyte is used in the preparation of batteries.

[0022] The beneficial effects of this invention are as follows: The degree of acetyl substitution in the cellulose diacetate-based composite solid electrolyte is controlled at 2.3-2.4. The introduction of some acetate esters disrupts the large hydrogen bond interactions between molecular chains to a certain extent, significantly improving electrode compatibility and processability. It also provides a suitable electrode for Li… + The transport provides a more relaxed channel, and the introduction of a small amount of acetyl groups will not significantly reduce the mechanical strength of cellulose acetate. Combining it with ceramic nanofibers can significantly increase the mechanical strength of the electrolyte, effectively resisting the growth of lithium dendrites during charging and discharging and preventing penetration. At the same time, the ionic liquid, as an "ion bridge", helps to form a continuous organic-inorganic interface, promoting the efficient migration of ions at the cellulose acetate-ceramic interface, thereby improving the ionic conductivity and cycle stability of the battery.

[0023] In this invention, the degree of acetyl substitution is preferably 2.3 to 2.4, because the degree of acetyl substitution in cellulose acetate affects the ion transport performance and mechanical properties of the solid electrolyte. If the substitution is too low, a large number of hydroxyl groups will still exist in the cellulose acetate molecule, thus the strong hydrogen bond network and dense molecular chains will reduce the lithium-ion transport kinetics and the processability of the material. If the substitution is too high, the interaction between cellulose chains will be too loose, thereby reducing the mechanical properties of the material, leading to a decrease in the structural stability of the electrolyte, and indirectly affecting the ion transport stability. Therefore, when combining cellulose diacetate with fast ion conductor ceramic nanofibers, the optimal degree of acetyl substitution is 2.3 to 2.4 for the overall performance of the combination.

[0024] The concentration of cellulose diacetate is preferably 10-15 wt%. If the concentration is too high, the viscosity of the slurry system will increase, which is detrimental to the preparation and processing of the solid electrolyte and significantly reduces the uniformity of the electrolyte, thus affecting the electrochemical performance of the battery. If the concentration of cellulose diacetate is too low, it indicates a decrease in the flexible polymer component in the mixed slurry system, which will lead to poorer flexibility of the composite solid electrolyte, thereby increasing the brittleness of the electrolyte, increasing interfacial impedance, and reducing electrochemical stability.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the preparation process of the cellulose diacetate-based composite solid electrolyte in this invention;

[0027] Figure 2 This is a scanning electron microscope image of aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers in Example 1 of the present invention;

[0028] Figure 3 This is a scanning electron microscope image of the cellulose diacetate-based composite solid electrolyte prepared in Example 1 of this invention;

[0029] Figure 4 The cycling curves at 1 C are for battery 1 based on the cellulose diacetate-based composite solid electrolyte in Example 1, battery 5 based on the cellulose diacetate-based solid electrolyte with added ceramic nanoparticles in Comparative Example 1, and battery 6 based on the cellulose diacetate-based solid electrolyte without added ceramic nanofibers in Comparative Example 2. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] The present invention will be explained in more detail through the following embodiments. The purpose of disclosing the present invention is to protect all changes and modifications within the scope of the present invention. The present invention is not limited to the following embodiments.

[0032] Example 1

[0033] S1. Dissolve 10 wt% cellulose diacetate with a degree of substitution of 2.3 in the ionic liquid N-methyl-N-propylpyrrolidine difluorosulfonylimide at 60 °C to obtain mixed solution A;

[0034] S2. Lithium bis(fluorosulfonyl)imide is introduced into solution A and dissolved to obtain mixed solution B, wherein the lithium salt is 5 wt% of the mass of cellulose diacetate.

[0035] S3. Polyethylene glycol methacrylate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number P141172) and thermal initiator benzoyl peroxide are added to solution B to obtain mixed solution C, wherein polyethylene glycol methacrylate accounts for 10 wt% of the mass of solution C and benzoyl peroxide accounts for 1 wt% of the mass of polyethylene glycol methacrylate.

[0036] S4. Add aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers with a fiber diameter of 200 nm to the mixed solution C and stir thoroughly to obtain an electrolyte slurry. The mass ratio of aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers to cellulose diacetate is 1:1. The aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers are prepared according to "2.2.2 Preparation process of Al-doped LLZO fiber membrane" in "Preparation of lithium lanthanum zirconium oxide nanofiber membrane and its application in solid-state lithium battery" (Chen Qiaojing. Preparation of lithium lanthanum zirconium oxide nanofiber membrane and its application in solid-state lithium battery [D]. Donghua University, 2022.), with the calcination temperature modified to 900 ℃.

[0037] S5. The electrolyte slurry obtained above is thermally polymerized into a film at 60 °C to obtain a cellulose diacetate-based composite solid electrolyte.

[0038] like Figure 2 As shown, the diameter of the aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers is approximately 200 nm.

[0039] like Figure 3 As shown, the surface morphology of the cellulose diacetate-based composite solid electrolyte is relatively smooth and flat, which helps to reduce the interfacial impedance of the electrolyte.

[0040] Example 2

[0041] S1. Dissolve 11 wt% cellulose diacetate with a degree of substitution of 2.3 in the ionic liquid N-methyl-N-propylpyrrolidine difluorosulfonylimide at 70 °C to obtain mixed solution A;

[0042] S2. Lithium bis(fluorosulfonyl)imide is introduced into solution A and dissolved to obtain mixed solution B, wherein the lithium salt is 8 wt% of the mass of cellulose diacetate.

[0043] S3. Polyethylene glycol methacrylate monomer and thermal initiator benzoyl peroxide are added to solution B to obtain mixed solution C, wherein polyethylene glycol methacrylate accounts for 10.5 wt% of the mass of solution C, and benzoyl peroxide accounts for 1.3 wt% of the mass of polyethylene glycol methacrylate.

[0044] S4. Add aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers with a fiber diameter of 300 nm to the mixed solution C, stir thoroughly to obtain an electrolyte slurry, and the mass ratio of aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers to cellulose diacetate is 1:1.5.

[0045] S5. The above electrolyte slurry is thermally polymerized at 65 °C to form a film, thereby obtaining a cellulose diacetate-based composite solid electrolyte.

[0046] Example 3

[0047] S1. Dissolve 13 wt% cellulose diacetate with a degree of substitution of 2.4 in the ionic liquid 1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imide at 80 °C to obtain mixed solution A;

[0048] S2. Lithium bis(trifluoromethanesulfonyl)imide is introduced into solution A and dissolved to obtain mixed solution B, wherein the lithium salt is 12 wt% of the mass of cellulose diacetate.

[0049] S3. Polyethylene glycol methacrylate (PEG) and benzoyl peroxide (BPO) are added to solution B to obtain a mixed solution C, wherein PEG is 11 wt% of the mass of solution C and benzoyl peroxide is 1.7 wt% of the mass of PEG.

[0050] S4. Add aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers with a fiber diameter of 400 nm to the mixed solution C, stir thoroughly to obtain an electrolyte slurry, wherein the mass ratio of aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers to cellulose diacetate is 1:2.

[0051] S5. The above electrolyte slurry is thermally polymerized at 70 °C to form a film, thereby obtaining a cellulose diacetate-based composite solid electrolyte.

[0052] Example 4

[0053] S1. Dissolve 15 wt% cellulose diacetate with a degree of substitution of 2.4 in the ionic liquid 1-butyl-4-methylpyridine bis(trifluoromethanesulfonyl)imide at 100 °C to obtain mixed solution A;

[0054] S2. Lithium bis(trifluoromethanesulfonyl)imide is introduced into solution A and dissolved to obtain mixed solution B, wherein the lithium salt is 15 wt% of the mass of cellulose diacetate.

[0055] S3. Polyethylene glycol methacrylate (PEG) and benzoyl peroxide (BPO) are added to solution B to obtain a mixed solution C, wherein PEG is 12 wt% of the mass of solution C and benzoyl peroxide is 2 wt% of the mass of PEG.

[0056] S4. Add aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers with a fiber diameter of 500 nm to the mixed solution C, stir thoroughly to obtain an electrolyte slurry, wherein the mass ratio of aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers to cellulose diacetate is 1:3.

[0057] S5. The above electrolyte slurry is thermally polymerized at 80 °C to form a film, thereby obtaining a cellulose diacetate-based composite solid electrolyte.

[0058] Comparative Example 1

[0059] S1. Dissolve 10 wt% cellulose diacetate with a degree of substitution of 2.3 in the ionic liquid N-methyl-N-propylpyrrolidine difluorosulfonylimide at 60 °C to obtain mixed solution A;

[0060] S2. Lithium bis(fluorosulfonyl)imide is introduced into solution A and dissolved to obtain mixed solution B, wherein the lithium salt is 5 wt% of the mass of cellulose diacetate.

[0061] S3. Polyethylene glycol methacrylate monomer and thermal initiator benzoyl peroxide are added to solution B to obtain mixed solution C, wherein polyethylene glycol methacrylate accounts for 10 wt% of the mass of solution C, and benzoyl peroxide accounts for 1 wt% of the mass of polyethylene glycol methacrylate.

[0062] S4. Add aluminum-doped lithium lanthanum zirconium oxide ceramic nanoparticles with a particle size of 200 nm to the mixed solution C, stir thoroughly to obtain an electrolyte slurry, wherein the mass ratio of aluminum-doped lithium lanthanum zirconium oxide ceramic nanoparticles to cellulose diacetate is 1:1.

[0063] S5. The above electrolyte slurry is thermally polymerized at 60 °C to form a film, thereby obtaining a cellulose diacetate-based composite solid electrolyte with added ceramic nanoparticles.

[0064] Comparative Example 2

[0065] S1. Dissolve 10 wt% cellulose diacetate with a degree of substitution of 2.3 in the ionic liquid N-methyl-N-propylpyrrolidine difluorosulfonylimide at 60 °C to obtain mixed solution A;

[0066] S2. Lithium bis(fluorosulfonyl)imide is introduced into solution A and dissolved to obtain mixed solution B, wherein the lithium salt is 5 wt% of the mass of cellulose diacetate.

[0067] S3. Polyethylene glycol methacrylate monomer and thermal initiator benzoyl peroxide are added to solution B to obtain an electrolyte slurry, wherein polyethylene glycol methacrylate accounts for 10 wt% of the electrolyte slurry mass and benzoyl peroxide accounts for 1 wt% of the polyethylene glycol methacrylate mass.

[0068] S4. The above electrolyte slurry is thermally polymerized into a film at 60 °C to obtain a cellulose diacetate-based composite solid electrolyte without added ceramic nanofibers.

[0069] Comparative Example 3

[0070] S1. Dissolve 10 wt% cellulose diacetate with a degree of substitution of 2.0 in the ionic liquid N-methyl-N-propylpyrrolidine difluorosulfonylimide at 60 °C to obtain mixed solution A;

[0071] S2. Lithium bis(fluorosulfonyl)imide is introduced into solution A and dissolved to obtain mixed solution B, wherein the lithium salt is 5 wt% of the mass of cellulose diacetate.

[0072] S3. Polyethylene glycol methacrylate monomer and thermal initiator benzoyl peroxide are added to solution B to obtain mixed solution C, wherein polyethylene glycol methacrylate accounts for 10 wt% of the mass of solution C, and benzoyl peroxide accounts for 1 wt% of the mass of polyethylene glycol methacrylate.

[0073] S4. Add aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers with a fiber diameter of 200 nm to the mixed solution C, stir thoroughly to obtain an electrolyte slurry, wherein the mass ratio of aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers to cellulose diacetate is 1:1.

[0074] S5. The electrolyte slurry obtained above is thermally polymerized into a film at 60 °C to obtain a cellulose diacetate-based composite solid electrolyte.

[0075] Comparative Example 4

[0076] S1. Dissolve 10 wt% cellulose diacetate with a degree of substitution of 2.7 in the ionic liquid N-methyl-N-propylpyrrolidine difluorosulfonylimide at 60 °C to obtain mixed solution A;

[0077] S2. Lithium bis(fluorosulfonyl)imide is introduced into solution A and dissolved to obtain mixed solution B, wherein the lithium salt is 5 wt% of the mass of cellulose diacetate.

[0078] S3. Polyethylene glycol methacrylate monomer and thermal initiator benzoyl peroxide are added to solution B to obtain mixed solution C, wherein polyethylene glycol methacrylate accounts for 10 wt% of the mass of solution C, and benzoyl peroxide accounts for 1 wt% of the mass of polyethylene glycol methacrylate.

[0079] S4. Add aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers with a fiber diameter of 200 nm to the mixed solution C, stir thoroughly to obtain an electrolyte slurry, wherein the mass ratio of aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers to cellulose diacetate is 1:1.

[0080] S5. The electrolyte slurry obtained above is thermally polymerized into a film at 60 °C to obtain a cellulose diacetate-based composite solid electrolyte.

[0081] Comparative Example 5

[0082] S1. A mixed solution A is obtained by mixing the polymeric monomer polyethylene glycol methacrylate with the thermal initiator benzoyl peroxide, wherein the benzoyl peroxide is 1 wt% of the mass of polyethylene glycol methacrylate.

[0083] S2. Add aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers with a fiber diameter of 200 nm to mixed solution A, stir thoroughly to obtain electrolyte slurry, and the mass ratio of aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers to mixed solution A is 7:3.

[0084] S3. The electrolyte slurry obtained above is thermally polymerized into a film at 60 °C to obtain an aluminum-doped lithium lanthanum zirconium oxide ceramic nanofiber-based solid electrolyte.

[0085] Performance testing:

[0086] Using lithium iron phosphate as the positive electrode and lithium metal as the negative electrode, the following batteries were assembled: CR2025 battery one (prepared in Example 1), CR2025 battery two (prepared in Example 2), CR2025 battery three (prepared in Example 3), CR2025 battery four (prepared in Example 4), CR2025 battery five (prepared in Comparative Example 1 with added ceramic nanoparticles), CR2025 battery six (prepared in Comparative Example 2 without added ceramic nanofibers), CR2025 battery seven (prepared in Comparative Example 3), CR2025 battery eight (prepared in Comparative Example 4), and CR2025 battery nine (prepared in Comparative Example 5 with aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers).

[0087] The constant current charge-discharge curves of batteries 1, 2, 3, 4, 5, 6, 7, 8, and 9 were tested using a CT-4000 Xinwei battery analyzer at 1 C, with a voltage range of 2.5-3.8 V.

[0088] Table 1 presents the comparative data of the cycle performance at 1 C for the following batteries based on the cellulose diacetate-based composite solid electrolyte in Example 1, Example 2, Example 3, Example 4, Comparative Example 5, Comparative Example 6, Comparative Example 7, Comparative Example 8, and Comparative Example 9: A battery based on an aluminum-doped lithium lanthanum zirconium oxide ceramic nanofiber-based solid electrolyte.

[0089] Table 1

[0090]

[0091] As can be seen from Table 1, compared with batteries five, six, seven, eight and nine in the comparative examples, batteries one, two, three and four in the embodiments have excellent overall performance.

[0092] To further and more clearly demonstrate the effects of nanofibers and fast-ion conductor ceramics on battery cycle performance, Figure 4 The sequential performance charts for batteries one, five, and six are listed, combined with... Figure 4 As can be seen from Table 1, compared to the CR2025 battery five based on a cellulose diacetate-based solid electrolyte with added ceramic nanoparticles in Comparative Example 1, the CR2025 battery one based on a cellulose diacetate-based composite solid electrolyte in Example 1 has a higher initial discharge specific capacity (166.1 mAh g⁻¹). -1 The high capacity retention (96.6%) and coulombic efficiency (98.9%) indicate that the continuous ceramic nanofibers in this composite solid electrolyte have superior electrochemical performance compared to dispersed ceramic nanoparticles.

[0093] In addition, combined Figure 4 As can be seen from Table 1, compared with the CR2025 battery VI based on cellulose diacetate-based solid electrolyte without added ceramic nanofibers in Comparative Example 2, the CR2025 battery I based on cellulose diacetate-based composite solid electrolyte in Example 1 still exhibits the best cycle stability, proving that the combination of ion conductor ceramic nanofibers and cellulose diacetate has a significant effect on improving the cycle performance of solid-state lithium batteries.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for producing a cellulose diacetate-based composite solid electrolyte, characterized by: The method comprises the following steps: S1, dissolving cellulose diacetate with a degree of substitution of 2.3 in an ionic liquid N-methyl-N-propyl pyrrolidinium bisfluorosulfonylimide at 60°C to obtain a mixed solution A; in the mixed solution A, the concentration of the cellulose diacetate with a degree of substitution of 2.3 is 10 wt%; S2, introducing lithium salt lithium bisfluorosulfonylimide into solution A to obtain a mixed solution B, wherein the lithium salt is 5 wt% of the mass of the cellulose diacetate; S3, adding polymer monomer polyethylene glycol methacrylate and thermal initiator benzoyl peroxide into solution B to obtain a mixed solution C; wherein the polyethylene glycol methacrylate is 10 wt% of the mass of solution C, and the benzoyl peroxide is 1 wt% of the mass of the polyethylene glycol methacrylate; S4, adding aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers with a fiber diameter of 200 nm into the mixed solution C, stirring uniformly to obtain an electrolyte slurry, and the mass ratio of the aluminum-doped lithium lanthanum zirconium oxide ceramic nanofibers to the cellulose diacetate is 1:1; S5, heat polymerizing the electrolyte slurry obtained in step S4 into a film at 60°C to obtain a cellulose diacetate-based composite solid electrolyte.

2. The cellulose diacetate-based composite solid electrolyte prepared by the preparation method of the cellulose diacetate-based composite solid electrolyte according to claim 1.

3. The cellulose diacetate-based composite solid electrolyte according to claim 2 is applied in lithium batteries.

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