Cellulose-based semi-solid electrolyte as well as preparation method and application thereof
Through the method of composite of cellulose-based semi-solid electrolyte with inorganic fillers, the existing semi-solid electrolytes have been solved, and high stability, good mechanical strength and high ionic conductivity have been achieved, which has improved the safety performance and fast charging and discharge capabilities of lithium metal batteries.
Patent Information
- Application Number
- CN202510267629.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2025-06-10
AI Technical Summary
The existing semi-solid electrolytes have high cost, poor mechanical properties, low ionic conductivity, and unstable electrolyte-negative electrode interface, resulting in reduced performance and safety hazards of lithium metal batteries.
Using cellulose-based semi-solid electrolyte, a three-dimensional network structure is constructed by combining cellulose fibers with inorganic fillers (such as titanium-based lithium ion conductors) and a vacuum suction filtration method is used to improve the mechanical strength and ionic conductivity of the electrolyte.
It achieves high stability, good mechanical strength and high room temperature ionic conductivity, improves the safety performance and fast charging and discharging capabilities of lithium metal batteries, and reduces production costs and operational complexity.
Smart Images
Figure CN120127209A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of lithium batteries, and particularly relates to a cellulose-based semi-solid electrolyte, a preparation method thereof and an application, and more particularly to the application of the cellulose-based semi-solid electrolyte in a lithium battery. Background Art
[0002] Lithium metal batteries (LMBs) are considered the most promising form of chemical power source due to their huge theoretical capacity and volumetric capacity. However, at present, lithium metal batteries have not been commercialized. The main reason is that the side reaction between lithium metal and liquid electrolyte will cause the instability of the solid electrolyte interface (SEI) on the lithium metal anode, resulting in a decline in battery performance. In addition, in the battery system based on liquid electrolyte, there are problems such as easy volatilization and leakage of the electrolyte, and there is a potential risk of thermal runaway, making it difficult to ensure the safety of battery use. Using all-solid electrolytes to replace traditional organic liquid electrolytes is an effective way to solve the safety and stability problems of high-energy-density lithium metal batteries. However, so far, all-solid electrolytes have poor lithium-ion conductivity, low ion migration number, and complex preparation processes. Therefore, the development of semi-solid electrolytes with high lithium-ion conductivity, which can not only achieve the stability of the metal anode but also ensure the safety of the battery, is an important stage in the development of battery technology from liquid batteries to all-solid batteries.
[0003] Organic-inorganic hybrid semi-solid batteries are an advanced battery technology that combines inorganic materials and organic polymers, aiming to overcome the safety hazards of traditional liquid batteries and improve energy density and cycle life. Compared with all-solid battery technology, semi-solid batteries have low cost, high efficiency, and simple processes, which are more conducive to the large-scale application of power batteries at the present stage. Through literature research, it is found that organic-inorganic hybrid semi-solid electrolytes based on renewable cellulose matrices are the most promising semi-solid electrolyte systems at present. On the one hand, introducing a renewable cellulose skeleton into the electrolyte can effectively improve the mechanical formation of the electrolyte and reduce the battery manufacturing cost; on the other hand, introducing inorganic fillers can greatly enhance the lithium-ion transfer at the interface and simultaneously inhibit the growth of lithium dendrites. The key problem lies in how to select inorganic fillers and compound the organic-inorganic composite electrolyte into a film through a suitable process, and simultaneously obtain a solid lithium metal battery with low interfacial resistance, high ion mobility, and conductivity. Summary of the Invention
[0004] In view of this, in order to solve the technical problems in the prior art such as high cost, poor mechanical properties, low ionic conductivity, and unstable electrolyte-anode interface of semi-solid electrolytes, the present invention provides a cellulose-based semi-solid electrolyte, a preparation method thereof and an application.
[0005] The present invention solves the above technical problems by adopting the following technical solutions.
[0006] A preparation method of a cellulose-based semi-solid electrolyte, comprising the following steps:
[0007] Step 1. Pretreatment of cellulose fibers
[0008] First, disperse the cellulose fiber dispersion in deionized (DDI) water, wash and centrifuge several times to remove additives, then wash and centrifuge the obtained purified cellulose fibers several times with absolute ethanol for dehydration, and finally dilute the obtained dehydrated purified cellulose fibers into absolute ethanol to prepare a purified cellulose fiber dispersion with a solid content of 0.03 - 0.2 g / mL;
[0009] Step 2. Preparation of inorganic fillers
[0010] At room temperature, take Co(NO 3 ) 2 Dissolve it in a mixed solution of methanol and ethanol to obtain solution A, and take 2-methylimidazole and dissolve it in a mixed solution of methanol and ethanol to obtain solution B;
[0011] Add the titanium-based lithium ion conductor to solution B, stir evenly, then mix with solution A, stir evenly, let it stand, centrifuge the precipitate, wash and dry to obtain blue filler powder;
[0012] Step 3. Preparation of the composite semi-solid electrolyte
[0013] Add the blue filler powder to the purified cellulose fiber dispersion, stir for 5 - 25 h to fully react to obtain a mixed slurry, and vacuum filter to form a film to obtain a cellulose mixed film;
[0014] Immerse the cellulose mixed film in the electrolyte for 12 - 30 h, and dry at room temperature to remove the solvent to obtain the cellulose-based semi-solid electrolyte.
[0015] Preferably, in step 1, the cellulose fiber is one or more of bacterial cellulose fiber, plant cellulose fiber, and synthetic cellulose fiber, and the solvent of the cellulose fiber dispersion is deionized water.
[0016] Preferably, in step 2, in the mixed solution of methanol and ethanol, the volume ratio of methanol to ethanol is 1:0.5 - 1:1.5.
[0017] Preferably, in step 2, in solution A, the concentration of Co(NO 3 ) 2 is 0.23 - 0.31 mol / L.
[0018] Preferably, in step 2, the added molar amount of 2-methylimidazole is 1.2 - 6 times the molar amount of Co(NO 3 ) 2
[0019] Preferably, in step two, the titanium-based lithium ion conductor includes LiTiO 2 , Li 2 TiO 3 , Li 4 Ti 5 O 12 or several of them, and the particle size of the titanium-based lithium ion conductor is not more than 500 mesh.
[0020] Preferably, in step two, the added mass of the titanium-based lithium ion conductor is 10% - 32% of the mass of Co(NO 3 ) 2 .
[0021] Preferably, in step three, the added mass of the blue powder filler is 0.1% - 2% of the mass of the purified cellulose fiber dispersion.
[0022] Preferably, in step three, a filter membrane with a pore size of 0.44 μm is used for vacuum filtration to form a film.
[0023] Preferably, in step three, the mass density of the cellulose mixed film is 1 - 4 mg / cm 2 .
[0024] Preferably, in step three, the lithium salt of the electrolyte is 1M LiPF 6 or 1M LiClO 4 , and the electrolyte solvent is a mixed solution of EC and DMC with a ratio of 1:1.
[0025] The present invention also provides a cellulose-based semi-solid electrolyte prepared by the above preparation method.
[0026] The present invention also provides the application of the above cellulose-based semi-solid electrolyte in metal lithium ion batteries.
[0027] Compared with the prior art, the beneficial effects of the present invention are:
[0028] The cellulose-based semi-solid electrolyte of the present invention has good stability, good mechanical strength, high room temperature ionic conductivity, and the assembled battery has good safety performance and can achieve fast charge and discharge.
[0029] The preparation method of the cellulose-based semi-solid electrolyte of the present invention has the advantages of low production cost, simple operation process, and environmental protection of the materials used. A three-dimensional network structure stable interface semi-solid electrolyte diaphragm based on cellulose is constructed by a one-step vacuum filtration method, which is suitable for large-scale production and industrial application. Description of the Drawings
[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.
[0031] Figure 1 It is the microscopic scanning electron microscope image of the semi-solid electrolyte prepared in Example 1 of the present invention.
[0032] Figure 2 It is the comparison of the cycling performance of the lithium-NCM full cell assembled with the semi-solid electrolyte and the commercial electrolyte prepared in Example 1 of the present invention at room temperature. Detailed implementation manners
[0033] To enable those skilled in the art to better understand the technical solutions of the present invention, the following will further introduce the present invention in detail in combination with embodiments.
[0034] In the following embodiments, various processes and methods not described in detail are conventional methods well known in the art. The materials, reagents, devices, instruments, equipment, etc. used in the following embodiments can be obtained from commercial channels without special instructions.
[0035] Example 1
[0036] A preparation method of a cellulose-based semi-solid electrolyte is as follows:
[0037] (1) Pretreatment of bacterial cellulose fibers: First, disperse 30 g of bacterial cellulose fiber dispersion in deionized water, wash and centrifuge several times to remove additives. Then wash and centrifuge the obtained purified bacterial cellulose fibers several times with anhydrous ethanol for dehydration. Finally, dilute it to 150 ml of anhydrous ethanol solution to prepare a purified cellulose fiber dispersion with a solid content of 0.2 g / mL.
[0038] (2) Preparation of inorganic fillers: At room temperature, weigh 1.74 g of Co(NO 3 ) 2 and dissolve it in a mixed solution of 20 ml of methanol and 20 ml of ethanol, denoted as solution A. Then take 2.07 g of 2-methylimidazole and dissolve it in a mixed solution of 20 ml of methanol and 20 ml of ethanol, denoted as solution B. After adding 0.3 g of LiTiO 2 to solution B, stir evenly, mix it with solution A, stir evenly, let it stand for 18 h, centrifuge the precipitate, wash it twice with anhydrous ethanol, and dry it at 50 °C for 12 h to obtain a blue filler powder, denoted as ZIF-67@LiTiO 2 .
[0039] (3) Preparation of composite solid electrolyte: Add 0.1 g of blue filler powder to 100 g of purified cellulose fiber dispersion, stir for 12 h, and react fully to obtain a mixed slurry. Use a filter membrane with a pore size of 0.44 μm for vacuum filtration to form a film with a mass density of 1.5 mg / cm 2 film, obtaining a bacterial cellulose mixed film. Immerse the bacterial cellulose mixed film in the electrolyte (1 M LiPF 6 dissolved in EC / DMC with a volume ratio of 1:1) for 12 h. After taking it out, dry it at room temperature for 20 min to remove the solvent, forming a cellulose-based semi-solid electrolyte, denoted as BC / ZIF-67@LiTiO 2 , and the scanning electron microscope image is as Figure 1 shown.
[0040] Example 2
[0041] A preparation method of a cellulose-based semi-solid electrolyte is as follows:
[0042] (1) Pretreatment of plant cellulose: First, disperse 30 g of plant cellulose fiber dispersion in deionized water, wash and centrifuge several times to remove additives. Then wash and centrifuge the obtained purified plant cellulose fiber several times with anhydrous ethanol for dehydration. Finally, dilute it to 1000 ml of anhydrous ethanol solution to prepare a purified cellulose fiber dispersion with a solid content of 0.03 g / mL.
[0043] (2) Preparation of inorganic filler: At room temperature, weigh 1.74 g of Co(NO 3 ) 2 and dissolve it in a mixed solution of 15 ml of methanol and 15 ml of ethanol, denoted as solution A. Then take 2.13 g of 2-methylimidazole and dissolve it in a mixed solution of 15 ml of methanol and 15 ml of ethanol, denoted as solution B. Add 0.2 g of Li 2 TiO 3 to solution B, stir evenly, mix it with solution A, stir evenly, let it stand for 12 h, centrifuge the precipitate, wash it once with anhydrous ethanol, and dry it at 30 °C for 6 h to obtain blue filler powder.
[0044] (3) Preparation of composite semi-solid electrolyte: Add 0.05 g of blue filler powder to 5 g of purified cellulose fiber dispersion, stir for 5 h, and react fully to obtain a mixed slurry. Use a filter membrane with a pore size of 0.44 μm for vacuum filtration to form a 1 mg / cm 2 film, obtaining a plant cellulose mixed film. Immerse the plant cellulose mixed film in the electrolyte (1 M LiPF 6 dissolved in EC / DMC with a volume ratio of 1:1) for 6 h, and dry it at room temperature for 10 min to remove the solvent, forming a cellulose-based semi-solid electrolyte.
[0045] Example 3
[0046] A preparation method of a cellulose-based semi-solid electrolyte is as follows:
[0047] (1) Pretreatment of synthetic cellulose: First, disperse 30 g of synthetic cellulose fiber dispersion in deionized water, wash and centrifuge several times to remove additives. Then wash the obtained purified synthetic cellulose fiber with anhydrous ethanol and centrifuge several times for dehydration. Finally, dilute it to 300 ml of anhydrous ethanol solution to prepare a purified cellulose fiber dispersion with a solid content of 0.1 g / mL.
[0048] (2) Preparation of inorganic filler: At room temperature, weigh 3.48 g of Co(NO 3 ) 2 Dissolve it in a mixed solution of 40 ml of methanol and 40 ml of ethanol, denoted as solution A. Then take 4.5 g of 2-methylimidazole and dissolve it in a mixed solution of 40 ml of methanol and 40 ml of ethanol, denoted as solution B. Add 0.4 g of Li 4 Ti 5 O 2 to solution B, stir evenly, let it stand for 36 h, centrifuge the precipitate, wash it 3 times with anhydrous ethanol, and dry it at 40 °C for 10 h to obtain blue filler powder.
[0049] (3) Preparation of composite semi-solid electrolyte: Add 0.15 g of blue filler powder to 30 g of purified cellulose fiber dispersion, stir for 24 h, fully react to obtain a mixed slurry, and use a filter membrane with a pore size of 0.44 μm for vacuum filtration to form a 2 mg / cm 2 thin film, obtain a synthetic cellulose mixed film, immerse the synthetic cellulose mixed film in an electrolyte (1 M LiPF 6 dissolved in a volume ratio of 1:1 EC / DMC) for 30 h, and dry it at room temperature for 30 min to remove the solvent to form a cellulose-based semi-solid electrolyte.
[0050] Example 4
[0051] A preparation method of a cellulose-based semi-solid electrolyte is as follows:
[0052] (1) Pretreatment of bacterial cellulose: First, disperse 30 g of bacterial cellulose fiber dispersion in deionized water, wash and centrifuge several times to remove additives. Then wash the obtained purified bacterial cellulose fiber with anhydrous ethanol and centrifuge several times for dehydration. Finally, dilute it to 200 ml of anhydrous ethanol solution to prepare a purified cellulose fiber dispersion with a solid content of 0.15 g / mL.
[0053] (2) Preparation of inorganic filler: At room temperature, weigh 1.74 g of Co(NO 3 ) 2Dissolved in a mixed solution of 17 ml of methanol and 17 ml of ethanol, denoted as solution A. Then, 3.00 g of 2-methylimidazole was dissolved in a mixed solution of 17 ml of methanol and 17 ml of ethanol, denoted as solution B. 0.25 g of LiTiO 2 was added to solution B, stirred evenly, left standing for 36 h, the precipitate was centrifuged, washed once with absolute ethanol, and dried at 40 °C for 18 h to obtain blue filler powder.
[0054] (3) Preparation of composite semi-solid electrolyte: 0.08 g of blue filler powder was added to 80 g of purified cellulose fiber dispersion, stirred for 8 h, and fully reacted to obtain a mixed slurry. Vacuum filtration was carried out using a filter membrane with a pore size of 0.44 μm to form a 1.2 mg / cm 2 film, obtaining a bacterial cellulose mixed film. The bacterial cellulose mixed film was immersed in an electrolyte solution (1 M LiPF 6 dissolved in a 1:1 volume ratio of EC / DMC) for 24 h, and dried at room temperature for 15 min to remove the solvent, forming a cellulose-based semi-solid electrolyte.
[0055] Example 5
[0056] A preparation method of a cellulose-based semi-solid electrolyte is as follows:
[0057] (1) Pretreatment of plant cellulose: First, 30 g of plant cellulose fiber dispersion was dispersed in deionized water, washed and centrifuged several times to remove additives. Then, the obtained purified plant cellulose fiber was washed and centrifuged several times with absolute ethanol for dehydration. Finally, it was diluted to 600 ml of absolute ethanol solution to prepare a purified cellulose fiber dispersion with a solid content of 0.05 g / mL.
[0058] (2) Preparation of inorganic filler: At room temperature, 17.4 g of Co(NO 3 ) 2 was dissolved in a mixed solution of 160 ml of methanol and 160 ml of ethanol, denoted as solution A. Then, 40.20 g of 2-methylimidazole was dissolved in a mixed solution of 16 ml of methanol and 16 ml of ethanol, denoted as solution B. 3.5 g of Li 2 TiO 3 was added to solution B, stirred evenly, left standing for 36 h, the precipitate was centrifuged, washed twice with absolute ethanol, and dried at 40 °C for 10 h to obtain blue filler powder.
[0059] (3) Preparation of composite semi-solid electrolyte: 0.12 g of blue filler powder was added to 10 g of purified cellulose fiber dispersion, stirred for 18 h, and fully reacted to obtain a mixed slurry. Vacuum filtration was carried out using a filter membrane with a pore size of 0.44 μm to form a 1.7 mg / cm 2The plant cellulose mixed membrane was immersed in an electrolyte (1M LiPF 6 It was dissolved in EC / DMC (volume ratio 1:1) for 28 hours and dried at room temperature for 25 minutes to remove the solvent to form a cellulose-based semi-solid electrolyte.
[0060] Example 6
[0061] The nickel-cobalt-manganese 811 ternary material, carbon black and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1 are added to an agate mortar, and ground thoroughly until mixed evenly. 20-30 ml of N-methylpyrrolidone is added dropwise, and ground again to form a uniform slurry with a solid content of 13.9wt% to 19.5wt%. The slurry is coated on a dry carbon-coated aluminum foil with a scraper, first dried at 70°C in a blast drying oven for 3 hours, and then dried at 120°C in a vacuum environment for 12 hours. The electrode is taken out when the temperature drops below 50°C; the taken-out electrode is compacted with a roller press, and then cut into a circular positive electrode with a diameter of 13 mm with a punching machine for standby use.
[0062] A 1 mm thick lithium sheet was selected as the negative electrode.
[0063] The cellulose-based semi-solid electrolyte prepared in Example 1 was selected as the separator and electrolyte, and 15 μL of electrolyte (1M LiPF 6 Dissolved in a volume ratio of 1:1 EC / DMC) to activate the battery.
[0064] All materials were placed in a chamber filled with high purity argon (H 2 O<0.1ppm, O 2 <0.1ppm) in a glove box to assemble CR2025 button cells, and use a battery pressure packaging machine to package the cells; finally, the assembled CR2025 button cells were left to activate at room temperature for 12 hours for later use.
[0065] The electrochemical performance of the prepared product after being assembled into a CR2025 button cell as a semi-solid electrolyte separator was tested. The battery performance test results are as follows: Figure 2 shown.
[0066] At the same time, 1 mol / L LiPF 6 The carbonate electrolyte was obtained by dissolving in a mixed solvent of EC and DMC (1:1 volume ratio) as the control group of the experiment, namely the commercial electrolyte.
[0067] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the embodiments. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.
Claims
1. A method for preparing a cellulose-based semi-solid electrolyte, characterized in that: The following steps are involved: Step 1: Pretreatment of cellulose fibers Firstly, the cellulose fiber dispersion is dispersed in deionized water, washed and centrifuged several times to remove additives, then the purified cellulose fibers are washed with anhydrous ethanol and centrifuged several times to dehydrate, and finally the dehydrated purified cellulose fibers are diluted in anhydrous ethanol to prepare a purified cellulose fiber dispersion with a solid content of 0.03-0.2 g / mL; Step 2: Preparation of inorganic filler At room temperature, Co(NO3)2 was dissolved in a mixed solution of methanol and ethanol to obtain solution A, and 2-methylimidazole was dissolved in a mixed solution of methanol and ethanol to obtain solution B; Adding the titanium-based lithium ion conductor to the B solution, stirring evenly, mixing with the A solution, stirring evenly, standing, centrifuging the precipitate, washing, and drying to obtain a blue filler powder; Step 3: Preparation of composite semi-solid electrolyte Adding blue filler powder to the purified cellulose fiber dispersion, stirring for 5-25 hours to fully react, obtaining a mixed slurry, vacuum filtering to form a membrane, and obtaining a cellulose mixed membrane; The cellulose mixed membrane is immersed in the electrolyte for 12 to 30 hours, and then dried at room temperature to remove the solvent to obtain a cellulose-based semi-solid electrolyte.
2. The method for preparing a cellulose-based semi-solid electrolyte according to claim 1, characterized in that: In step 1, the cellulose fiber is one or more of bacterial cellulose fiber, plant cellulose fiber, and synthetic cellulose fiber, and the solvent of the cellulose fiber dispersion is deionized water.
3. The method for preparing a cellulose-based semi-solid electrolyte according to claim 1, characterized in that: In step 2, in the mixed solution of methanol and ethanol, the volume ratio of methanol to ethanol is 1:0.5-1:1.5; In the solution A, the concentration of Co(NO3)2 is 0.23-0.31 mol / L; The added molar amount of the 2-methylimidazole is 1.2-6 times the molar amount of Co(NO3)2.
4. The method for preparing a cellulose-based semi-solid electrolyte according to claim 1, characterized in that: In step 2, the titanium-based lithium ion conductor includes LiTiO2, Li2TiO3, Li4Ti5O 12 One or more of the above, the particle size of the titanium-based lithium ion conductor is not greater than 500 meshes, and the added mass of the titanium-based lithium ion conductor is 10% to 32% of the mass of Co(NO3)2.
5. The method for preparing a cellulose-based semi-solid electrolyte according to claim 1, characterized in that: In step three, the added mass of the blue powder filler is 0.1% to 2% of the mass of the purified cellulose fiber dispersion.
6. The method for preparing a cellulose-based semi-solid electrolyte according to claim 1, characterized in that: In step 3, a filter membrane with a pore size of 0.44 μm is used for vacuum filtration to form a membrane.
7. The method for preparing a cellulose-based semi-solid electrolyte according to claim 1, characterized in that: In step 3, the mass density of the cellulose mixed film is 1-4 mg / cm 2 .
8. The method for preparing a cellulose-based semi-solid electrolyte according to claim 1, characterized in that: In step 3, the lithium salt of the electrolyte is 1M LiPF6 or 1M LiClO4, and the electrolyte solvent is a mixture of EC and DMC in a volume ratio of 1:
1.
9. A cellulose-based semi-solid electrolyte prepared according to the preparation method according to any one of claims 1 to 8.
10. Use of the cellulose-based semi-solid electrolyte according to claim 9 in lithium-ion batteries.