CN116574196B - Synthesis method of lithium phosphoryl cellulose nanocrystalline and composite gel electrolyte - Google Patents
Synthesis method of lithium phosphoryl cellulose nanocrystalline and composite gel electrolyte Download PDFInfo
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 56
- 229920002678 cellulose Polymers 0.000 title claims abstract description 38
- 239000001913 cellulose Substances 0.000 title claims abstract description 38
- 239000011245 gel electrolyte Substances 0.000 title claims abstract description 38
- 239000002131 composite material Substances 0.000 title claims abstract description 19
- 238000001308 synthesis method Methods 0.000 title claims abstract description 8
- 239000000243 solution Substances 0.000 claims abstract description 80
- 239000002244 precipitate Substances 0.000 claims abstract description 48
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 47
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 39
- 235000010980 cellulose Nutrition 0.000 claims abstract description 37
- 238000003756 stirring Methods 0.000 claims abstract description 33
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims abstract description 29
- 239000008367 deionised water Substances 0.000 claims abstract description 29
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 29
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000007864 aqueous solution Substances 0.000 claims abstract description 23
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229920000168 Microcrystalline cellulose Polymers 0.000 claims abstract description 21
- 235000019813 microcrystalline cellulose Nutrition 0.000 claims abstract description 21
- 239000008108 microcrystalline cellulose Substances 0.000 claims abstract description 21
- 229940016286 microcrystalline cellulose Drugs 0.000 claims abstract description 21
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims abstract description 20
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 12
- 230000007935 neutral effect Effects 0.000 claims abstract description 10
- 238000010438 heat treatment Methods 0.000 claims abstract description 8
- 238000001035 drying Methods 0.000 claims abstract description 7
- 238000001914 filtration Methods 0.000 claims abstract description 7
- 239000000084 colloidal system Substances 0.000 claims abstract description 5
- 238000002791 soaking Methods 0.000 claims abstract description 5
- 238000009210 therapy by ultrasound Methods 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 11
- 239000002159 nanocrystal Substances 0.000 claims description 10
- 229920009405 Polyvinylidenefluoride (PVDF) Film Polymers 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 229920002981 polyvinylidene fluoride Polymers 0.000 abstract description 26
- 239000002033 PVDF binder Substances 0.000 abstract description 25
- 239000012528 membrane Substances 0.000 abstract description 17
- 230000014759 maintenance of location Effects 0.000 abstract description 5
- 238000012360 testing method Methods 0.000 abstract description 4
- 238000005119 centrifugation Methods 0.000 abstract 1
- 239000003792 electrolyte Substances 0.000 description 20
- 238000000502 dialysis Methods 0.000 description 18
- 239000007788 liquid Substances 0.000 description 12
- 239000006228 supernatant Substances 0.000 description 12
- 239000000725 suspension Substances 0.000 description 12
- 229920000642 polymer Polymers 0.000 description 9
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- 239000006255 coating slurry Substances 0.000 description 7
- 229910001416 lithium ion Inorganic materials 0.000 description 7
- -1 polyethylene Polymers 0.000 description 7
- 239000005518 polymer electrolyte Substances 0.000 description 7
- 238000001816 cooling Methods 0.000 description 6
- 239000011521 glass Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 239000007784 solid electrolyte Substances 0.000 description 6
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- LFGREXWGYUGZLY-UHFFFAOYSA-N phosphoryl Chemical group [P]=O LFGREXWGYUGZLY-UHFFFAOYSA-N 0.000 description 5
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 5
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 5
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 5
- 150000001450 anions Chemical class 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000005012 migration Effects 0.000 description 4
- 238000013508 migration Methods 0.000 description 4
- 210000004027 cell Anatomy 0.000 description 3
- 239000005486 organic electrolyte Substances 0.000 description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 210000001787 dendrite Anatomy 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- ODIGIKRIUKFKHP-UHFFFAOYSA-N (n-propan-2-yloxycarbonylanilino) acetate Chemical compound CC(C)OC(=O)N(OC(C)=O)C1=CC=CC=C1 ODIGIKRIUKFKHP-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910015872 LiNi0.8Co0.1Mn0.1O2 Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 229920000891 common polymer Polymers 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000002001 electrolyte material Substances 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 239000007888 film coating Substances 0.000 description 1
- 238000009501 film coating Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000002329 infrared spectrum Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
- C08B15/05—Derivatives containing elements other than carbon, hydrogen, oxygen, halogens or sulfur
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Nanotechnology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Chemical & Material Sciences (AREA)
- Electrochemistry (AREA)
- Health & Medical Sciences (AREA)
- Organic Chemistry (AREA)
- Composite Materials (AREA)
- Life Sciences & Earth Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Biochemistry (AREA)
- Secondary Cells (AREA)
Abstract
The invention relates to a synthesis method of lithium phosphoryl cellulose nanocrystalline and a composite gel electrolyte, wherein microcrystalline cellulose is added into phosphoric acid aqueous solution, then the solution is stirred at constant temperature, the obtained solution is poured into enough deionized water and is fully stirred until being uniform, and a first precipitate is obtained after centrifugation; and then adding the solution into NaOH aqueous solution, heating, fully stirring, centrifuging to obtain a second precipitate, filtering, collecting, adding the second precipitate into LiOH aqueous solution, fully stirring at room temperature, placing the obtained solution into excessive deionized water, dialyzing at room temperature until water is acid-base neutral, and performing ultrasonic treatment to obtain the lithium cellulose phosphorylate nanocrystalline colloid. Adding polyethylene oxide into the colloid solution of the lithium phosphoryl cellulose nanocrystalline, and stirring at room temperature until the polyethylene oxide is completely dissolved; and soaking the polyvinylidene fluoride membrane in the solution, and then heating and drying to obtain the composite gel electrolyte. The invention improves the capacity retention rate of the battery in a long-cycle test and the stability at high temperature.
Description
Technical Field
The invention belongs to the field of solid-state lithium batteries and electrolyte materials thereof, and particularly relates to a phosphoryl cellulose lithium nanocrystalline and a synthesis method thereof, a composite gel electrolyte based on the phosphoryl cellulose lithium nanocrystalline, and a corresponding solid-state lithium battery.
Background
The lithium ion battery is an important energy storage device and has wide application in the fields of electronic products, new energy automobiles and energy storage. The basic working principle of the lithium ion battery is that lithium ions are reversibly and reciprocally intercalated/deintercalated between a positive electrode material and a negative electrode active material to realize charge and discharge, and the process is usually carried out in an organic electrolyte system. However, flammable organic electrolytes present safety hazards on the one hand; on the other hand, the battery market is in urgent demand for lithium batteries having higher energy density. In recent years, various solid-state batteries using metallic lithium as a negative electrode and using a solid-state electrolyte to replace a conventional electrolyte have become a hot spot for research. The metallic lithium as the negative electrode can improve the energy density of the battery compared with the traditional graphite negative electrode, and the solid electrolyte has higher safety than the organic electrolyte.
In solid electrolytes, a polymer gel electrolyte is a quasi-solid electrolyte system formed by combining a polymer electrolyte with an electrolyte phase. The polymer utilizes the polymer chains of the polymer to absorb as much electrolyte as possible and swell, so that conductive ions can be electromigration in the electrolyte along the pore channels formed by the polymer framework. The conductive mode between the all-solid electrolyte and the electrolyte ensures that the polymer gel electrolyte has higher safety and enough ion conductivity. Due to the high liquid absorption and high porosity of the polymer skeleton, the polymer gel electrolyte not only has higher room temperature ion conductivity than the all-solid electrolyte, but also can avoid the safety problems of thermal runaway and the like of the battery caused by electrolyte flow.
Polyvinylidene fluoride (PVDF) is a common polymer gel electrolyte material, and has the advantages of higher melting point, higher electrolyte liquid absorption rate, no combustion and the like compared with the traditional polyethylene, polypropylene and other diaphragm materials. PVDF is a polymer gel electrolyte material with very good application prospect. However, since a certain amount of ester electrolyte is still contained therein, modification of PVDF gel electrolyte is often required for use in lithium metal batteries. Therefore, the solid electrolyte system with better performance is designed based on the PVDF gel electrolyte, so that the comprehensive performances such as the cycling stability and the safety of the lithium battery are improved, and the method has important significance for the development of the lithium battery industry.
Disclosure of Invention
The invention aims to provide a synthesis method of lithium phosphoryl cellulose nanocrystalline and a composite gel electrolyte, so as to achieve the purpose of battery cycle stability.
In order to solve the above technical problems, according to an aspect of the present invention, there is provided a lithium phosphoryl cellulose nanocrystal having a structural formula:
。
according to another aspect of the present invention, there is provided a method for synthesizing the above-described lithium phosphoryl cellulose nanocrystals, comprising:
adding microcrystalline cellulose into a phosphoric acid aqueous solution with the mass concentration of 54-85% at 80-110 ℃ and stirring at a constant temperature, pouring the obtained solution into enough deionized water, fully stirring until the solution is uniform, and centrifuging to obtain a first precipitate;
step two, filtering and collecting the first precipitate obtained in the step one, adding the first precipitate into an NaOH aqueous solution, heating to 60-80 ℃, fully stirring, and centrifuging to obtain a second precipitate;
and thirdly, filtering and collecting the second precipitate obtained in the second step, adding the second precipitate into a LiOH aqueous solution with the concentration of 1-4 mol/L, fully stirring at room temperature, placing the obtained solution into excessive deionized water, dialyzing at room temperature until water is acid-base neutral, and performing ultrasonic treatment to obtain the lithium phosphoryl cellulose nanocrystalline colloid.
In the first step, the constant-temperature stirring time is 30-180 minutes.
In the first step, the mass ratio of the microcrystalline cellulose to the water is 5-10%.
Further, the deionized water is used in the first step in an amount of at least 10 volume units of deionized water per 1 volume unit of solution.
Further, in the second step, the concentration of the NaOH aqueous solution is 5-10%.
According to another aspect of the present invention, there is provided a method for producing a composite gel electrolyte, characterized by comprising:
step one, adding polyethylene oxide (PEO) into the colloidal solution of the lithium phosphoryl cellulose nanocrystalline, and stirring at room temperature until the polyethylene oxide (PEO) is completely dissolved;
and step two, soaking a polyvinylidene fluoride (PVDF) film in the solution obtained in the step one, and then heating and drying to obtain the lithium phosphoryl cellulose nanocrystalline composite gel electrolyte.
Further, 0.5 to 3 parts by mass of polyethylene oxide is added per 100 parts by mass of the colloidal solution of the nanocrystals.
According to another aspect of the present invention, there is provided a composite gel electrolyte prepared by the above method.
According to another aspect of the present invention, there is provided a solid state lithium battery comprising the composite gel electrolyte described above.
The invention provides a synthesis method of phosphoryl cellulose lithium nanocrystalline, a composite gel electrolyte is prepared on the basis, and a high-performance solid lithium battery is manufactured based on the composite gel electrolyte. The lithium phosphorylate cellulose nanocrystalline provides an effect of regulating and controlling ion transportation at the interface of the gel polymer electrolyte and the lithium metal negative electrode, so that the deposition of lithium ions is more uniform, the uniformity of the lithium metal negative electrode can be effectively improved, and the growth of irregular lithium dendrites can be effectively inhibited. The negatively charged phosphoryl group can generate a certain coulomb repulsive interaction on anions in the electrolyte, so that the migration activity of the anions in the electrolyte is reduced, the migration number of lithium ions is increased, and the side reaction on the surface of the electrode is reduced. The nano-network structure lithium cellulose phosphorylate nanocrystalline increases the specific surface area of the electrolyte surface, improves the mechanical strength of the electrolyte membrane, and improves the heat resistance of the electrolyte membrane, thereby improving the capacity retention rate of the battery in a long-cycle test and the stability at high temperature.
Drawings
FIG. 1 is a transmission electron micrograph of lithium phosphoryl cellulose nanocrystals obtained in example 1;
FIG. 2 is an infrared spectrum of lithium phosphoryl cellulose nanocrystals and their synthesis precursors (phosphoryl cellulose nanocrystals) and synthesis raw materials (microcrystalline cellulose) in example 1;
FIG. 3 is a scanning electron micrograph of the PVDF gel electrolyte membrane of example 1;
fig. 4 is a charge-discharge specific capacity and coulombic efficiency curve of the lithium cellulose acylate nanocrystalline gel polymer electrolyte coating used in a coin cell in example 1;
fig. 5 is a tensile strength test curve of PVDF gel electrolyte membrane coated with gel polymer electrolyte of lithium phosphoryl cellulose nanocrystals provided in example 1.
Detailed Description
The structural formula of the lithium phosphoryl cellulose nanocrystalline provided by the typical embodiment of the invention is as follows:
。
the lithium phosphorylate cellulose nanocrystalline provides an effect of regulating and controlling ion transportation at the interface of the gel polymer electrolyte and the lithium metal negative electrode, so that the deposition of lithium ions is more uniform, the uniformity of the lithium metal negative electrode can be effectively improved, and the growth of irregular lithium dendrites can be effectively inhibited. The negatively charged phosphoryl group can generate a certain coulomb repulsive interaction on anions in the electrolyte, so that the migration activity of the anions in the electrolyte is reduced, the migration number of lithium ions is increased, and the side reaction on the surface of the electrode is reduced. The nano-network structure lithium cellulose phosphorylate nanocrystalline increases the specific surface area of the electrolyte surface, improves the mechanical strength of the electrolyte membrane, and improves the heat resistance of the electrolyte membrane, thereby improving the capacity retention rate of the battery in a long-cycle test and the stability at high temperature.
The synthesis method of the lithium phosphoryl cellulose nanocrystalline provided by the exemplary embodiment comprises the following steps.
Adding microcrystalline cellulose (MCC) into an aqueous solution of phosphoric acid with the mass concentration of 54-85% at 80-110 ℃ and stirring at constant temperature for 30-180 minutes, pouring the obtained solution into enough deionized water, stirring fully and uniformly, and centrifuging for 10-30 minutes to obtain a first Precipitate (PCNC), wherein the first precipitate is brown precipitate.
Wherein the mass ratio of the microcrystalline cellulose to the phosphoric acid solution is 5-10%. The deionized water is used in an amount corresponding to at least 10 volume units of deionized water per 1 volume unit of solution.
And step two, filtering and collecting the first precipitate obtained in the step one, adding the first precipitate into a 5-10% NaOH aqueous solution, heating to 60-80 ℃, fully stirring, and centrifuging to obtain a second precipitate, wherein the second precipitate is brown.
Wherein the concentration of the NaOH aqueous solution is 5-10%.
And thirdly, filtering and collecting the second precipitate obtained in the second step, adding the second precipitate into a LiOH aqueous solution with the concentration of 1-4 mol/L, fully stirring at room temperature, placing the obtained solution into excessive deionized water, dialyzing at room temperature until water is acid-base neutral, and performing ultrasonic treatment to obtain the lithium phosphoryl cellulose nanocrystalline colloid.
The synthesis reaction equation is:
the preparation method of the composite gel electrolyte based on the lithium phosphoryl cellulose nanocrystalline comprises the following steps.
Step one, adding polyethylene oxide (PEO) into the colloidal solution of the lithium phosphoryl cellulose nano-crystal in claim 1, and stirring at room temperature until the polyethylene oxide (PEO) is completely dissolved;
wherein, 0.5-3 parts by mass of polyethylene oxide is added per 100 parts by mass of the colloidal solution of the nanocrystalline.
And step two, soaking a polyvinylidene fluoride (PVDF) film in the solution obtained in the step one, and then heating and drying to obtain the lithium phosphoryl cellulose nanocrystalline composite gel electrolyte.
The preparation method of the polyvinylidene fluoride (PVDF) film comprises the following steps:
step one: PVDF and polyvinylpyrrolidone (PVP) are added into N, N-Dimethylacetamide (DMAC) according to a certain proportion, and are fully stirred at room temperature to obtain uniform transparent solution; the proportions of PVDF and PVP added in the N, N-dimethylacetamide are respectively as follows: 80-160 g of PVDF and 1-4 g of PVP are added into each 1 liter of N, N-dimethylacetamide.
Step two: coating the solution obtained in the first step into a uniform and flat film on a glass plate by using a doctor blade with a certain thickness, slowly putting the whole glass plate into excessive room-temperature deionized water, standing for a plurality of minutes until the liquid film is completely phase-converted and automatically separated from the glass plate, flushing the film by the excessive deionized water, and then putting the film on a polytetrafluoroethylene plate, and drying;
step three: and (3) flattening the membrane obtained in the step two by using a roll squeezer to obtain the PVDF gel electrolyte membrane.
The following examples are provided to further illustrate the claimed invention. However, examples and comparative examples are provided for the purpose of illustrating embodiments of the present invention and do not exceed the scope of the inventive subject matter, which is not limited by the examples. Unless specifically indicated otherwise, materials and reagents used in the present invention are available from commercial products in the art.
Example 1
After 100mL of aqueous phosphoric acid (85 wt.%) was heated to 100 ℃, 5g of microcrystalline cellulose was added thereto and magnetically stirred at high speed to ensure that all microcrystalline cellulose was mixed with the liquid. The stirring speed and temperature were maintained for 90 minutes, and the solution turned to a transparent pale yellow and then to a darker black. The black solution was poured into 1L of deionized water at 0deg.C and then thoroughly stirred until homogeneous. The solution was allowed to stand for 12 hours and the supernatant was decanted. The solution containing the precipitate in the lower layer was centrifuged at 6000rpm for 10 minutes. The supernatant was decanted, and the entire black precipitate was collected and added to 100mL of 7wt.% aqueous NaOH. The solution was heated to 65℃and stirred at 500rpm for 5 hours. After cooling to room temperature, this solution was centrifuged at 8000rpm for 15 minutes. The upper black solution was decanted, and the entire brown precipitate was collected and added to 100mL of 2mol/L LiOH aqueous solution. Stirring was carried out at 600rpm for 24 hours at room temperature to give a brown-yellow suspension. The suspension is poured into a dialysis bag with the molecular weight cut-off of 4000-6000D and placed into deionized water, water is repeatedly changed until the outside water becomes acid-base neutral, and a small amount of flocculent precipitate and light yellow transparent solution are obtained in the dialysis bag. The dialysis bag contents were transferred to a vessel, thoroughly stirred and sonicated sequentially at 40kHz and 59kHz for 10 minutes to give a clear pale yellow gel. 10mL of this gel was measured, 0.1g of polyethylene oxide was added thereto, and the mixture was stirred sufficiently at room temperature until the polyethylene oxide was completely dissolved, to obtain a coating slurry.
To 100mL of N, N-dimethylacetamide was added 12.8g of polyvinylidene fluoride and 0.32g of polyvinylpyrrolidone. Stirring at room temperature until the solid is completely dissolved, thus obtaining a film coating solution. A proper amount of the coating solution was poured onto a glass plate, and was applied as a liquid film by a doctor blade having a thickness of 200. Mu.m. Slowly immersing the glass plate with the liquid film into excessive deionized water at room temperature, standing for 2 minutes, and automatically separating the PVDF film from the glass plate. And (3) placing the PVDF film on a polytetrafluoroethylene flat plate with a smooth surface, and drying the water in a baking oven at 70 ℃ to obtain the PVDF gel electrolyte membrane. The PVDF gel electrolyte membrane is clamped between two pieces of printing paper, and is repeatedly rolled for 4 times at 15 mu m intervals by a roll squeezer, so that a flat PVDF gel electrolyte membrane is obtained.
And soaking the PVDF gel electrolyte membrane in the coating slurry to fully absorb liquid, taking out and spreading the PVDF gel electrolyte membrane on a polytetrafluoroethylene plate, and drying the PVDF gel electrolyte membrane in a baking oven at 70 ℃ to obtain the PVDF gel electrolyte membrane modified by the phosphoryl cellulose lithium nanocrystalline coating, which is called PCNC-Li@PVDF for short.
Lithium metal button cell (positive) using the lithium phosphoryl cellulose nanocrystalline PVDF gel polymer electrolyte modified coating provided by the inventionExtremely LiNi 0.8 Co 0.1 Mn 0.1 O 2 The electrolyte is 1M LiPF 6 Dmc=3: 7 solution) after 500 weeks of 1C/1C charge-discharge cycle, 92.5 mAh.g -1 The specific discharge capacity (capacity retention rate 51.03%) of the present invention was higher than that of a PVDF gel electrolyte lithium metal coin cell without the modified coating of a lithium phosphoryl cellulose nanocrystal provided by the present invention (73 mA. G) -1 Capacity retention 39.01) was 26.7% higher.
The PVDF gel electrolyte membrane using the lithium phosphoryl cellulose nanocrystalline gel polymer electrolyte modified coating provided by the invention has obviously improved tensile strength. In the tensile test, the true stress born by the steel is increased from 2.36MPa to 6.33MPa, and the tensile strength is increased from 21.62 kgf cm -2 To 53.46 kgf cm -2 。
Example 2
After 100mL of aqueous phosphoric acid (54 wt.%) was heated to 80 ℃, 5g of microcrystalline cellulose was added thereto and magnetically stirred at high speed to ensure that all microcrystalline cellulose was mixed with the liquid. The stirring speed and temperature were maintained for 30 minutes, and the solution turned to a transparent pale yellow and then to a darker black. The black solution was poured into 1L of deionized water at 0deg.C and then thoroughly stirred until homogeneous. The solution was allowed to stand for 12 hours and the supernatant was decanted. The solution containing the precipitate in the lower layer was centrifuged at 6000rpm for 10 minutes. The supernatant was decanted, all black precipitate was collected and added to 100mL of 5wt.% aqueous NaOH. The solution was heated to 60℃and stirred at 500rpm for 5 hours. After cooling to room temperature, the solution was centrifuged at 8000rpm for 10 minutes. The upper black solution was decanted, and the entire brown precipitate was collected and added to 100mL of 1mol/L LiOH aqueous solution. Stirring was carried out at 600rpm for 24 hours at room temperature to give a brown-yellow suspension. The suspension is poured into a dialysis bag with the molecular weight cut-off of 4000-6000D and placed into deionized water, water is repeatedly changed until the outside water becomes acid-base neutral, and a small amount of flocculent precipitate and light yellow transparent solution are obtained in the dialysis bag. The dialysis bag contents were transferred to a vessel, thoroughly stirred and sonicated sequentially at 40kHz and 59kHz for 10 minutes to give a clear pale yellow gel. 10mL of this gel was measured, 0.1g of polyethylene oxide was added thereto, and the mixture was stirred sufficiently at room temperature until the polyethylene oxide was completely dissolved, to obtain a coating slurry. The remaining steps were the same as in example 1.
Example 3
After 100mL of aqueous phosphoric acid (85 wt.%) was heated to 110 ℃, 10g of microcrystalline cellulose was added thereto and magnetically stirred at high speed to ensure that all microcrystalline cellulose was mixed with the liquid. The stirring speed and temperature were maintained for 180 minutes, and the solution turned to a transparent pale yellow and then to a darker black. The black solution was poured into 1L of deionized water at 0deg.C and then thoroughly stirred until homogeneous. The solution was allowed to stand for 12 hours and the supernatant was decanted. The solution containing the precipitate in the lower layer was centrifuged at 6000rpm for 30 minutes. The supernatant was decanted, all black precipitate was collected and added to 100mL of 10wt.% aqueous NaOH. The solution was heated to 80℃and stirred at 600rpm for 5 hours. After cooling to room temperature, the solution was centrifuged at 8000rpm for 30 minutes. The upper black solution was decanted, and the entire brown precipitate was collected and added to 100mL of 4mol/L LiOH aqueous solution. Stirring was carried out at 600rpm for 24 hours at room temperature to give a brown-yellow suspension. The suspension is poured into a dialysis bag with the molecular weight cut-off of 4000-6000D and placed into deionized water, water is repeatedly changed until the outside water becomes acid-base neutral, and a small amount of flocculent precipitate and light yellow transparent solution are obtained in the dialysis bag. The dialysis bag contents were transferred to a vessel, thoroughly stirred and sonicated sequentially at 40kHz and 59kHz for 10 minutes to give a clear pale yellow gel. 10mL of this gel was measured, 0.3g of polyethylene oxide was added thereto, and the mixture was stirred sufficiently at room temperature until the polyethylene oxide was completely dissolved, to obtain a coating slurry. The remaining steps were the same as in example 1.
Example 4
After 100mL of aqueous phosphoric acid (85 wt.%) was heated to 100 ℃, 10g of microcrystalline cellulose was added thereto and magnetically stirred at high speed to ensure that all microcrystalline cellulose was mixed with the liquid. The stirring speed and temperature were maintained for 120 minutes, and the solution turned to a transparent pale yellow and then to a darker black. The black solution was poured into 1L of deionized water at 0deg.C and then thoroughly stirred until homogeneous. The solution was allowed to stand for 12 hours and the supernatant was decanted. The solution containing the precipitate in the lower layer was centrifuged at 6000rpm for 15 minutes. The supernatant was decanted, all black precipitate was collected and added to 100mL of 8wt.% NaOH aqueous solution. The solution was heated to 70℃and stirred at 600rpm for 5 hours. After cooling to room temperature, this solution was centrifuged at 8000rpm for 15 minutes. The upper black solution was decanted, and the entire brown precipitate was collected and added to 100mL of 2mol/L LiOH aqueous solution. Stirring was carried out at 600rpm for 24 hours at room temperature to give a brown-yellow suspension. The suspension is poured into a dialysis bag with the molecular weight cut-off of 4000-6000D and placed into deionized water, water is repeatedly changed until the outside water becomes acid-base neutral, and a small amount of flocculent precipitate and light yellow transparent solution are obtained in the dialysis bag. The dialysis bag contents were transferred to a vessel, thoroughly stirred and sonicated sequentially at 40kHz and 59kHz for 10 minutes to give a clear pale yellow gel. 10mL of this gel was measured, 0.2g of polyethylene oxide was added thereto, and the mixture was stirred sufficiently at room temperature until the polyethylene oxide was completely dissolved, to obtain a coating slurry. The remaining steps were the same as in example 1.
Example 5
After 100mL of aqueous phosphoric acid (54 wt.%) was heated to 90 ℃, 5g of microcrystalline cellulose was added thereto and magnetically stirred at high speed to ensure that all microcrystalline cellulose was mixed with the liquid. The stirring speed and temperature were maintained for 150 minutes, and the solution turned to a transparent pale yellow and then to a darker black. The black solution was poured into 1L of deionized water at 0deg.C and then thoroughly stirred until homogeneous. The solution was allowed to stand for 12 hours and the supernatant was decanted. The solution containing the precipitate in the lower layer was centrifuged at 6000rpm for 15 minutes. The supernatant was decanted, all black precipitate was collected and added to 100mL of 9wt.% aqueous NaOH. The solution was heated to 75℃and stirred at 600rpm for 5 hours. After cooling to room temperature, this solution was centrifuged at 8000rpm for 15 minutes. The upper black solution was decanted, and the entire brown precipitate was collected and added to 100mL of 3mol/L LiOH aqueous solution. Stirring was carried out at 600rpm for 24 hours at room temperature to give a brown-yellow suspension. The suspension is poured into a dialysis bag with the molecular weight cut-off of 4000-6000D and placed into deionized water, water is repeatedly changed until the outside water becomes acid-base neutral, and a small amount of flocculent precipitate and light yellow transparent solution are obtained in the dialysis bag. The dialysis bag contents were transferred to a vessel, thoroughly stirred and sonicated sequentially at 40kHz and 59kHz for 10 minutes to give a clear pale yellow gel. 10mL of this gel was measured, 0.25g of polyethylene oxide was added thereto, and the mixture was stirred sufficiently at room temperature until the polyethylene oxide was completely dissolved, to obtain a coating slurry. The remaining steps were the same as in example 1.
Example 6
After 100mL of aqueous phosphoric acid (85 wt.%) was heated to 105 ℃, 8g of microcrystalline cellulose was added thereto and magnetically stirred at high speed to ensure that all microcrystalline cellulose was mixed with the liquid. The stirring speed and temperature were maintained for 180 minutes, and the solution turned to a transparent pale yellow and then to a darker black. The black solution was poured into 1L of deionized water at 0deg.C and then thoroughly stirred until homogeneous. The solution was allowed to stand for 12 hours and the supernatant was decanted. The solution containing the precipitate in the lower layer was centrifuged at 6000rpm for 20 minutes. The supernatant was decanted, all black precipitate was collected and added to 100mL of 10wt.% aqueous NaOH. The solution was heated to 80℃and stirred at 600rpm for 5 hours. After cooling to room temperature, the solution was centrifuged at 8000rpm for 30 minutes. The upper black solution was decanted, and the entire brown precipitate was collected and added to 100mL of 1.5mol/L LiOH aqueous solution. Stirring was carried out at 600rpm for 24 hours at room temperature to give a brown-yellow suspension. The suspension is poured into a dialysis bag with the molecular weight cut-off of 4000-6000D and placed into deionized water, water is repeatedly changed until the outside water becomes acid-base neutral, and a small amount of flocculent precipitate and light yellow transparent solution are obtained in the dialysis bag. The dialysis bag contents were transferred to a vessel, thoroughly stirred and sonicated sequentially at 40kHz and 59kHz for 10 minutes to give a clear pale yellow gel. 10mL of this gel was measured, 0.1g of polyethylene oxide was added thereto, and the mixture was stirred sufficiently at room temperature until the polyethylene oxide was completely dissolved, to obtain a coating slurry. The remaining steps were the same as in example 1.
Claims (9)
1. The synthesis method of the lithium phosphoryl cellulose nanocrystalline is characterized by comprising the following steps of:
adding microcrystalline cellulose into a phosphoric acid aqueous solution with the mass concentration of 54-85% at 80-110 ℃ and stirring at a constant temperature, pouring the obtained solution into enough deionized water, fully stirring until the solution is uniform, and centrifuging to obtain a first precipitate;
step two, filtering and collecting the first precipitate obtained in the step one, adding the first precipitate into an NaOH aqueous solution, heating to 60-80 ℃, fully stirring, and centrifuging to obtain a second precipitate;
and thirdly, filtering and collecting the second precipitate obtained in the second step, adding the second precipitate into a LiOH aqueous solution with the concentration of 1-4 mol/L, fully stirring at room temperature, placing the obtained solution into excessive deionized water, dialyzing at room temperature until water is acid-base neutral, and performing ultrasonic treatment to obtain the lithium phosphoryl cellulose nanocrystalline colloid.
2. The method according to claim 1, characterized in that: in the first step, the constant-temperature stirring time is 30-180 minutes.
3. The method according to claim 1, characterized in that: in the first step, the mass ratio of the microcrystalline cellulose to the phosphoric acid aqueous solution is 5-10%.
4. The method according to claim 1, characterized in that: the deionized water is used in the first step in an amount of at least 10 volume units of deionized water per 1 volume unit of solution.
5. The method according to claim 1, characterized in that: in the second step, the concentration of the NaOH aqueous solution is 5-10%.
6. A method for preparing a composite gel electrolyte, comprising:
step one, adding polyethylene oxide (PEO) into the colloidal solution of the lithium phosphoryl cellulose nano-crystal in claim 1, and stirring at room temperature until the polyethylene oxide (PEO) is completely dissolved;
and step two, soaking a polyvinylidene fluoride (PVDF) film in the solution obtained in the step one, and then heating and drying to obtain the lithium phosphoryl cellulose nanocrystalline composite gel electrolyte.
7. The method for preparing a composite gel electrolyte according to claim 6, wherein: 0.5-3 parts by mass of polyethylene oxide is added into 100 parts by mass of the colloidal solution of the lithium phosphoryl cellulose nanocrystalline.
8. The composite gel electrolyte prepared by the method of claim 6.
9. A solid state lithium battery characterized by: comprising the composite gel electrolyte of claim 8.
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Non-Patent Citations (4)
| Title |
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| Lithiated Phosphoryl Cellulose Nanocrystals Enhance Cycling Stability and Safety of Quasi-Solid-State Lithium Metal Batteries;Cui Baichuan等;ACS applied materials & interfaces;20230824;第15卷(第35期);第41537-41548页 * |
| Phosphorylated cellulose nanofiber as sustainable organic filler and potential flame-retardant for all-solid-state lithium batteries;Aziam H等;Journal of Energy Storage;20230214;第62卷;第106838页 * |
| Recepoglu YK等.SYNTHESIS,CHARACTERIZATION AND ADSORPTION STUDIES OF PHOSPHORYLATED CELLULOSE FOR THE RECOVERY OF LITHIUM FROM AQUEOUS SOLUTIONS.CELLULOSE CHEMISTRY AND TECHNOLOGY.2021,第55卷(第3-4期),第385-401页. * |
| 磷酸化纳米纤维素的制备及其纳米纸性能的研究;谢鸿;中国优秀硕士学位论文全文数据库工程科技Ⅰ辑;20230115(第01期);第B016-1566页 * |
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