CN114373995A - Composite solid polymer electrolyte and preparation method thereof - Google Patents
Composite solid polymer electrolyte and preparation method thereof Download PDFInfo
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- 239000002131 composite material Substances 0.000 title claims abstract description 39
- 239000007787 solid Substances 0.000 title claims abstract description 28
- 239000005518 polymer electrolyte Substances 0.000 title claims abstract description 27
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- 238000000034 method Methods 0.000 claims abstract description 39
- 239000002002 slurry Substances 0.000 claims abstract description 33
- 238000003756 stirring Methods 0.000 claims abstract description 31
- 239000003792 electrolyte Substances 0.000 claims abstract description 29
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000000843 powder Substances 0.000 claims abstract description 19
- 239000002270 dispersing agent Substances 0.000 claims abstract description 17
- 238000001035 drying Methods 0.000 claims abstract description 17
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 16
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 16
- 239000002033 PVDF binder Substances 0.000 claims abstract description 11
- 238000000576 coating method Methods 0.000 claims abstract description 11
- 239000008151 electrolyte solution Substances 0.000 claims abstract description 10
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims abstract description 10
- 239000011248 coating agent Substances 0.000 claims abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 7
- 238000001291 vacuum drying Methods 0.000 claims abstract description 6
- 239000003960 organic solvent Substances 0.000 claims abstract description 5
- 238000007654 immersion Methods 0.000 claims abstract description 4
- 239000012528 membrane Substances 0.000 claims description 55
- 239000011521 glass Substances 0.000 claims description 21
- 229910052744 lithium Inorganic materials 0.000 claims description 15
- 230000008569 process Effects 0.000 claims description 8
- 229910052582 BN Inorganic materials 0.000 claims description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 7
- 238000000498 ball milling Methods 0.000 claims description 5
- -1 lithium hexafluorophosphate Chemical group 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- 229910013872 LiPF Inorganic materials 0.000 claims description 3
- 101150058243 Lipf gene Proteins 0.000 claims description 3
- 229910013075 LiBF Inorganic materials 0.000 claims description 2
- MHABMANUFPZXEB-UHFFFAOYSA-N O-demethyl-aloesaponarin I Natural products O=C1C2=CC=CC(O)=C2C(=O)C2=C1C=C(O)C(C(O)=O)=C2C MHABMANUFPZXEB-UHFFFAOYSA-N 0.000 claims description 2
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 2
- 238000004528 spin coating Methods 0.000 claims description 2
- 238000010345 tape casting Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 2
- 241001436679 Adama Species 0.000 claims 1
- 239000007784 solid electrolyte Substances 0.000 abstract description 42
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 51
- 230000000052 comparative effect Effects 0.000 description 11
- 229920000642 polymer Polymers 0.000 description 8
- 239000000463 material Substances 0.000 description 6
- 210000001787 dendrite Anatomy 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 3
- 238000009776 industrial production Methods 0.000 description 3
- 239000002135 nanosheet Substances 0.000 description 3
- 238000004537 pulping Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- ORILYTVJVMAKLC-UHFFFAOYSA-N Adamantane Natural products C1C(C2)CC3CC1CC2C3 ORILYTVJVMAKLC-UHFFFAOYSA-N 0.000 description 2
- 238000004132 cross linking Methods 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
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- 239000000126 substance Substances 0.000 description 2
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- 238000013459 approach Methods 0.000 description 1
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- 238000004146 energy storage Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000009477 glass transition Effects 0.000 description 1
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- 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
- H01M10/058—Construction or manufacture
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- 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
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0088—Composites
- H01M2300/0091—Composites in the form of mixtures
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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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- Condensed Matter Physics & Semiconductors (AREA)
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Abstract
The invention relates to a preparation method of a composite solid polymer electrolyte, which comprises the following steps: s1, dispersing electrolyte lithium salt in an organic solvent, and stirring until the electrolyte lithium salt is completely dissolved to obtain an electrolyte solution; s2, adding the boron nitride nano powder and the g-C into the electrolyte solution in sequence while stirring3N4Fully stirring the PEO, the PVDF and the powder dispersant until dark yellow slurry is obtained; s3, coating the slurry on a smooth flat plate, and performing vacuum drying to obtain a solid film on the flat plate; separating the solid film from the flat plate by a water immersion method and floating the solid film; s4, clamping the solid film between two smooth flat plates, and drying to obtain the composite solid polymer electrolyte with smooth surface. The invention solves the technical problems of low mechanical strength, poor surface flatness, lower ionic conductivity, harsh preparation conditions and the like of the PEO solid electrolyte prepared by the prior art.
Description
Technical Field
The invention relates to the technical field of solid electrolytes, in particular to a composite solid polymer electrolyte and a preparation method thereof.
Background
The trend in energy storage systems is toward high energy density batteries, and the use of lithium metal as the anode of the battery can greatly increase the energy density of the battery. However, lithium metal batteries are prone to lithium dendrites during cycling, which can puncture the separator causing short circuits in the battery and thus the battery to burn or explode, greatly limiting the practical application of lithium metal batteries. The solid electrolyte is applied to the lithium metal battery to improve the safety of the lithium metal battery, and particularly, the solid polymer electrolyte is widely concerned due to the advantages of good flexibility, excellent processability, low interface resistance with a lithium metal anode and the like. In the prior art, polyethylene oxide is adopted as a polymer matrix of the all-solid-state polymer electrolyte battery, but a polyethylene oxide based system has high crystallinity and low ionic conductivity at room temperature, and the battery can normally operate only after a certain temperature is raised. However, when the temperature gradually approaches the glass transition temperature of the polymer electrolyte as the temperature rises, the mechanical strength of the electrolyte is greatly reduced, and it is difficult to suppress the growth of lithium dendrites. Research shows that the growth of lithium dendrites can be inhibited by improving the mechanical strength and the interface stability of the polymer electrolyte, and the cycle stability of the lithium metal battery is further improved.
In order to improve the mechanical strength of the polymer electrolyte, researchers have proposed a technique of preparing a polyethylene oxide polymer electrolyte and then coating boron nitride nanosheets prepared by a chemical lift-off method onto a PEO polymer electrolyte membrane by a hot press transfer method. The mechanical strength of the surface of the PEO polymer electrolyte can be enhanced through the boron nitride nanosheet coating layer, the interface of the electrolyte and lithium metal is ensured to be kept stable, the tip effect is reduced, the lithium ion flow is uniformly distributed, the growth of lithium dendrites is inhibited, and the cycling stability and the rate capability of the solid electrolyte are improved. However, although the method improves the mechanical strength of the polymer electrolyte, the prepared electrolyte has larger surface roughness, and the method is not only more complex in process and not suitable for industrial production, but also has insignificant improvement on the overall mechanical property of the polymer electrolyte, thereby limiting the practical application of the PEO polymer electrolyte. In addition, the prior art only focuses on improving the mechanical strength of the polymer electrolyte and inhibiting the growth of lithium dendrites, but does not improve the lithium ion conductivity of the solid electrolyte, and the electrochemical performance is still not ideal.
Disclosure of Invention
Technical problem to be solved
In view of the above disadvantages and shortcomings of the prior art, the present invention provides a composite solid polymer electrolyte and a preparation method thereof, which solves the technical problems of low mechanical strength, poor surface flatness, low ionic conductivity, harsh preparation conditions, etc. of the PEO solid electrolyte prepared by the prior art.
(II) technical scheme
In order to achieve the purpose, the invention adopts the main technical scheme that:
in a first aspect, the present invention provides a method for preparing a composite solid polymer electrolyte, comprising:
s1, dispersing electrolyte lithium salt in an organic solvent, and stirring until the electrolyte lithium salt is completely dissolved to obtain an electrolyte solution;
s2, adding the boron nitride nano powder and the g-C into the electrolyte solution in sequence while stirring3N4Fully stirring the PEO, the PVDF and the powder dispersant until dark yellow slurry is obtained;
s3, coating the slurry prepared in the S2 on a smooth flat plate, and performing vacuum drying to obtain a solid film on the flat plate; separating the solid film from the flat plate by a water immersion method and floating the solid film;
s4, clamping the solid film between two smooth flat plates, and drying to obtain the composite solid polymer electrolyte with smooth surface.
According to a preferred embodiment of the present invention, in S1, the electrolyte lithium salt is lithium hexafluorophosphate (LiPF)6) And/or lithium bistrifluoromethanesulfonylimide (LiTFSi). Of course, the electrolyte lithium salt may also be lithium tetrafluoroborate (LiBF)4)。
According to a preferred embodiment of the present invention, in S1, the organic solvent is any one of DMF, NMP, DMAC, and DEF, and is preferably a DEF environmentally friendly solvent.
According to a preferred embodiment of the present invention, in S2, the boron nitride is boron nitride nanopowder prepared by wet ball milling, and the particle size of the boron nitride nanopowder is 45-50 nm.
According to the preferred embodiment of the present invention, in S2, the stirring process is divided into three stages, the first stage is: adding boron nitride nanopowder and g-C into electrolyte solution3N4Adding PEO, PVDF and the powder dispersing agent while stirring at the speed of 300-400rpm (preferably 350 rpm); the second stage is as follows: after the addition is finished, the stirring speed is adjusted to 700-800rpm (preferably 750rpm), and the stirring is carried out for 50-90min (preferably 60 min); the third stage is as follows: the stirring speed is increased to 1000-1200rpm (preferably 1000rpm), and the stirring is carried out for 5-7h (preferably 6h), so as to obtain dark yellow slurry.
According to the preferred embodiment of the present invention, in S3, the smooth flat plate is made of glass, the coating method is knife coating or spin coating, and the coating thickness of the slurry is adjusted according to the thickness of the solid polymer electrolyte membrane to be prepared.
According to the preferred embodiment of the present invention, in S3, the vacuum drying condition is drying at 75-85 ℃ for 5-8 h; preferably at 80 ℃ for 6 h.
According to the preferred embodiment of the present invention, in S1, the concentration of the electrolyte lithium salt in the electrolyte solution is 55-65 g/L; preferably 60 g/L.
According to the preferred embodiment of the present invention, in S2, the electrolyte lithium salt, the boron nitride nanopowder, and g-C3N4The mass ratio of the PEO to the PVDF is 14-16: 6-7:2.5-3.5:30: 5-15; preferably, the mass ratio of the materials is 15:6-7:3:30: 10.
According to a preferred embodiment of the present invention, in S2, the powder dispersant is ada powder dispersant AD8085 or AD8058, and the amount of the powder dispersant is 0.00005-0.0001% of the total volume of the slurry.
In a second aspect, the present invention provides a composite solid polymer electrolyte prepared by the method of any one of the above embodiments.
(III) advantageous effects
Compared with the prior art, the innovation and the technical effects of the invention mainly comprise:
(1) in the preparation of the slurry, PVDF accounting for about 1/3 mass of PEO is added and dispersed into a PEO heterogeneous system, thereby destroying the crystallization of PEO, reducing the crystallinity of PEO, improving the electrochemical properties (including the ionic conductivity, the breakdown voltage and other electrochemical properties), and improving the mechanical strength and flexibility.
(2) When the slurry is prepared, the boron nitride nanopowder is directly added and mixed into the slurry of the PEO system, compared with the hot-pressing transfer method in the prior art, the preparation method disclosed by the invention is simple in preparation process, simultaneously can reduce the crystallinity of PEO through blending, can uniformly and effectively improve the overall mechanical strength of the PEO solid electrolyte membrane, reduces the surface roughness of the solid electrolyte membrane, and has the advantages of smoother surface of the electrolyte membrane and better application performance. In addition, the method prepares the boron nitride nanopowder by using wet ball milling, and compared with the boron nitride nanosheet prepared by adopting chemical stripping in the prior art, the particle size is finer (45-50nm), thereby being beneficial to obtaining a solid electrolyte membrane with better surface flatness. In addition, when the slurry is prepared, firstly, a solution of electrolyte lithium salt is prepared, the lithium salt can be completely dissolved in the solvent, and then the boron nitride nano powder and the g-C are added3N4PVDF and the like are stirred, so that the uniformity of the electrolyte lithium salt in the slurry can be ensured.
(3) When preparing the slurry, a certain amount of g-C with a porous lamellar structure is also added3N4Which not only reduces the tendency of the polymer to crystallize by producing a stronger crosslinking with the polymer PEO (confirmed by SEM), but also g-C3N4The introduction of the lithium ion conductive material also provides a larger surface interaction area, provides a channel for more transmission of lithium ions, and improves the conductivity.
(4) When the slurry is prepared, a trace amount of Auda powder dispersing agent AD8085 is also added, and the Auda powder dispersing agent can be adsorbed on the small powder particles to generate electrostatic repulsion to disperse the powder particles, so that the boron nitride nano powder and the g-C which are difficult to disperse originally are enabled to be added3N4Etc. can be rapidly dispersed, thereby making the prepared slurry disperse more rapidly, the time for preparing the slurry, and each doping material in the prepared slurryAnd is more uniformly dispersed, and the properties of the polymer electrolyte membrane prepared therefrom are more stable and uniform. Compared with the prior art, the stirring time for preparing the slurry is obviously shortened due to the addition of the powder dispersing agent (the stirring time of the invention is about 7.5-8h, and the uniform slurry can be prepared).
(5) When the polymer solid electrolyte membrane is prepared, the solid membrane after the slurry is dried is separated from a flat and smooth flat plate by adopting a water immersion method and naturally floats, the method is simple and easy to operate, the problems of difficult membrane stripping, membrane damage/deformation, membrane damage caused by operation problems and the like caused by overlarge membrane size and overlarge membrane thickness are solved, and the method is more suitable for industrial production.
(6) In the whole process of drying the polymer solid electrolyte membrane, the membrane is clamped between two smooth flat plates by adopting a clamping plate method, and the clamping state is kept while drying, so that the problems of membrane wrinkling, surface unevenness and the like caused by drying are avoided by applying certain pressure. Experiments prove that the method can be used for preparing the polymer solid electrolyte membrane with regular shape and flat surface.
In addition, based on the preparation method, compared with the prior art, the method only comprises the operations of dispersing, stirring, pulping, coating, drying, demoulding and the like, does not need special atmosphere environment or large-scale equipment, has simple and easy operation process, and is not limited by harsh process conditions such as a glove box or argon atmosphere protection, and the like, so that the method is more suitable for large-scale industrial production. In a word, the polymer solid electrolyte membrane prepared by the method has the characteristics of adjustable thickness, low cost, environmental protection, good repeatability, stable product quality, easy large-scale production and the like.
Drawings
Fig. 1 is an SEM image of PEO composite solid electrolyte membrane prepared in example 1 of the present invention at different magnifications.
Fig. 2 is a photograph of a real object of the PEO composite solid electrolyte membrane prepared in example 1 of the present invention.
Fig. 3 is a photograph of an actual object of the PEO composite solid electrolyte membrane prepared in comparative example 1.
Fig. 4 is a photograph of an actual object of the PEO composite solid electrolyte membrane prepared in comparative example 3.
Fig. 5 is a photograph of a folded state of a PEO composite solid electrolyte membrane prepared in example 1 of the present invention.
Fig. 6 is a photograph showing the uniformity and transparency of the PEO composite solid electrolyte membrane prepared in example 1 of the present invention.
The left diagram of FIG. 7 is g-C3N4The right figure is the SEM picture of the electrolyte membrane of example 1.
Detailed Description
For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.
Example 1
This example provides a method for preparing a PEO composite solid electrolyte, which includes:
(1) dissolving an electrolyte: 3g of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) were weighed out and dissolved in 50mL of N-methylpyrrolidone (NMP) and stirred until all was dissolved, during which time the speed was kept at 350 rpm.
(2) Feeding: boron nitride (1.3g) (45-50nm) prepared by wet ball milling and g-C3N4(0.6g), PEO (6g), polyethylene oxide, PVDF (2g) and Adam powder dispersant AD8085(0.05 μ L) were added in this order, and the rotational speed was kept constant during the addition.
(3) Stirring and pulping: stirring is carried out for 30min at 350rpm, then stirring is carried out for 1h at 750rpm, and then stirring is carried out for 6h after the speed is increased to 1000rpm, so as to obtain dark yellow slurry.
(4) And uniformly coating the slurry on a glass plate, wherein the thickness of the glass plate is self-regulated, then putting the glass plate into a vacuum drying oven, drying the glass plate for 6 hours at 80 ℃, taking out the glass plate, soaking the glass plate in a water pool, and taking out the glass plate after the membrane naturally floats.
(5) And placing the film between two layers of glass plates, clamping the glass by using a clamp, and drying in a 60 ℃ oven to obtain the PEO composite solid electrolyte film with adjustable thickness and smooth surface.
The PEO composite solid electrolyte membrane was tested to have an initial size of 27 x 40cm2Thickness of 30 μm, conductivity test using 6 x 4cm2Ruler for tensile testCun is 14 x 1.5cm2Tested by the ionic conductivity of 1.3966mS/cm and the tensile strength of 198kgf/cm2The breakdown voltage was 1.97 kV.
Meanwhile, SEM tests of the PEO composite solid electrolyte membrane prepared in the above example showed that the PEO composite solid electrolyte membrane prepared in this example has better surface flatness and is dense without pinholes, as shown in fig. 1, the right image is magnified 3000 times, and the left image is magnified 500 times.
Referring to fig. 2, it can be seen that the PEO composite solid electrolyte membrane prepared in this example is a uniform milky white solid electrolyte membrane with a flat surface, which indicates that the materials inside the solid electrolyte membrane are distributed very uniformly (otherwise, the materials are in different colors).
As shown in fig. 5, a photograph of the folded state of the PEO composite solid electrolyte membrane prepared in this example (cut into a circular sheet) shows that the electrolyte membrane has excellent flexibility, indicating that it has excellent bending resistance and mechanical strength.
As further shown in FIG. 7, it was found by SEM examination that PEO in the electrolyte membrane was tightly entangled and adhered to g-C3N4Surface to give authentication. This indicates that, in preparing the slurry, g-C of the porous lamellar structure was added3N4Produces stronger cross-linking effect with polymer PEO.
As shown in fig. 6, a photograph (cut into a circular sheet) of the uniformity and transparency of the PEO composite solid electrolyte membrane prepared in this example was seen to be a uniform and semi-transparent milky white color, indicating that various materials inside the electrolyte membrane were very uniformly distributed and the electrolyte membrane had a certain transparency, and was suitable for a specific application field.
Example 2
This example provides a method for preparing a PEO composite solid electrolyte, which includes:
(1) dissolving an electrolyte: 3g of lithium hexafluorophosphate (LiPF) was weighed6) Dissolved in 50mL DEF solvent and stirred until all is dissolved, the process speed was maintained at 350 rpm.
(2) Feeding: ball-milling by a wet methodPrepared boron nitride (1.4g) (45-50nm), g-C3N4(0.56g), PEO (6.15g), polyethylene oxide, PVDF (2.05g) and Adam powder dispersant AD8058(0.06 μ L) were added in this order, and the rotational speed was kept constant during the addition.
(3) Stirring and pulping: stirring at 350rpm for 30min, then at 750rpm for 80min, and then at 1200rpm for 5h to obtain dark yellow slurry.
(4) And uniformly coating the slurry on a glass plate, wherein the thickness of the glass plate is self-regulated, then putting the glass plate into a vacuum drying oven, drying the glass plate for 6 hours at 80 ℃, taking out the glass plate, soaking the glass plate in a water pool, and taking out the glass plate after the membrane naturally floats.
(5) And placing the film between two layers of glass plates, clamping the glass by using a clamp, and drying in a 60 ℃ oven to obtain the PEO composite solid electrolyte film with adjustable thickness and smooth surface.
It was determined that the PEO composite solid electrolyte membrane prepared in this example was similar in properties to the product prepared in example 1.
Comparative example 1
In the comparative example, on the basis of example 1, boron nitride nanopowder and Adda powder dispersant AD8085 are not added in the process of preparing the slurry. The remaining conditions and procedure were the same as in example 1.
Through testing, the PEO composite solid electrolyte membrane prepared by the comparative example has the thickness of 53 mu m, the ionic conductivity of 0.6260mS/cm and the tensile strength of 117kgf/cm2The breakdown voltage was 1.55 kV.
This demonstrates that the addition of boron nitride nanopowder to the slurry results in a significant reduction in the tensile strength of the PEO electrolyte membrane.
A real photograph of the PEO composite solid electrolyte membrane prepared in this comparative example is shown in fig. 3. Comparing FIG. 3 with FIG. 2, it can be seen that: the PEO composite solid electrolyte membrane of example 1 was uniformly milky white and flat on the surface as a whole (as shown in fig. 2), while the PEO composite solid electrolyte membrane prepared in this example had a very uneven distribution of various materials inside the electrolyte membrane due to the uneven surface color and transparency and the presence of a number of bubble-like patterns on the surface.
Comparative example 2
This comparative example is based on example 1, no g-C was added during the preparation of the slurry3N4. The remaining conditions and procedure were the same as in example 1.
Through tests, the PEO composite solid electrolyte membrane prepared by the comparative example has the thickness of 20.02 mu m, the ionic conductivity of 0.4937mS/cm and the tensile strength of 144kgf/cm2The breakdown voltage was 0.89 kV. Thus, it is shown that no g-C is added to the slurry3N4When powdered, this results in a significant drop in the conductivity of the PEO electrolyte membrane.
Comparative example 3
In the comparative example, on the basis of example 1, in the drying process of the step (5), the film which is soaked in water and floated is directly placed in an oven at 60 ℃ for drying, and the pressing and drying are not carried out in a manner of clamping two glass plates. In the same case as in example 1 with the remaining conditions and steps, a PEO composite solid electrolyte membrane as shown in fig. 4 was obtained.
Comparing FIG. 4 with FIG. 2, it can be seen that: the PEO composite solid electrolyte membrane of example 1 was uniformly milky white in its entirety and had a very flat surface (as shown in fig. 2), whereas the PEO composite solid electrolyte membrane prepared in this example had significant surface wrinkles (as shown in fig. 4). Therefore, in the drying process, if a flat and smooth flat plate is used for clamping the PEO composite solid electrolyte membrane for pressing and drying, a composite solid electrolyte membrane with a flat surface can be obtained.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for preparing a composite solid polymer electrolyte, comprising:
s1, dispersing electrolyte lithium salt in an organic solvent, and stirring until the electrolyte lithium salt is completely dissolved to obtain an electrolyte solution;
s2, adding the boron nitride nano powder and the g-C into the electrolyte solution in sequence while stirring3N4Fully stirring the PEO, the PVDF and the powder dispersant until dark yellow slurry is obtained;
s3, coating the slurry prepared in the S2 on a smooth flat plate, and performing vacuum drying to obtain a solid film on the flat plate; separating the solid film from the flat plate by a water immersion method and floating the solid film;
s4, clamping the solid film between two smooth flat plates, and drying to obtain the composite solid polymer electrolyte with smooth surface.
2. The method according to claim 1, wherein in S1, the electrolyte lithium salt is lithium hexafluorophosphate (LiPF)6) Lithium bistrifluoromethanesulfonylimide (LiTFSi), lithium tetrafluoroborate (LiBF)4) At least one of them.
3. The method according to claim 1, wherein in S1, the organic solvent is any one of DMF, NMP, DMAC, and DEF.
4. The preparation method according to claim 1, wherein in S2, the boron nitride is boron nitride nanopowder prepared by wet ball milling, and the particle size of the boron nitride nanopowder is 45-50 nm.
5. The method according to claim 1, wherein in S2, the stirring process is divided into three stages, the first stage is: adding boron nitride nanopowder and g-C into electrolyte solution3N4The PEO, the PVDF and the powder dispersant are added while stirring, and the stirring speed is 300-400 rpm; the second stage is as follows: after the feeding is finished, the stirring speed is adjusted to 700-800rpm, and the stirring is carried out for 50-90 min; the third stage is as follows: the stirring speed is increased to 1000-1200rpm, and the stirring is carried out for 5-7h, so as to obtain dark yellow slurry.
6. The production method according to claim 1, wherein in S3, the smooth flat plate is made of glass, the coating method is knife coating or spin coating, and the coating thickness of the slurry is adjusted according to the thickness of the solid polymer electrolyte membrane to be produced.
7. The production method according to claim 1, wherein in S1, the concentration of the electrolyte lithium salt in the electrolyte solution is 55 to 65 g/L.
8. The method according to claim 1, wherein in S2, the electrolyte lithium salt, the boron nitride nanopowder, and g-C3N4The mass ratio of the PEO to the PVDF is 14-16: 6-7:2.5-3.5:30:5-15.
9. The method according to claim 1, wherein in S2, the powder dispersant is Adama powder dispersant AD8085 or AD8058, and the amount of the powder dispersant is 0.00005-0.0001% of the total volume of the slurry.
10. A composite solid polymer electrolyte prepared by the method of any one of claims 1 to 9.
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| KR101911070B1 (en) * | 2017-04-26 | 2018-10-24 | 한국화학연구원 | Polymer electrolyte membrane including boronnitride, method of preparing the same, and litium secondary battery including the same |
| CN109546207A (en) * | 2018-11-30 | 2019-03-29 | 西安交通大学 | A kind of composite solid polymer electrolyte film and its preparation method and application |
| CN109755645A (en) * | 2018-12-28 | 2019-05-14 | 西安交通大学 | Boron nitride/polyethylene glycol oxide composite solid electrolyte preparation method and application |
| CN109802173A (en) * | 2019-01-24 | 2019-05-24 | 北京化工大学 | A kind of three-phase organic/inorganic plural gel state polymer dielectric and preparation method thereof |
| CN111710901A (en) * | 2020-06-04 | 2020-09-25 | 昆明理工大学 | Composite electrolyte membrane and preparation method thereof |
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| KR101911070B1 (en) * | 2017-04-26 | 2018-10-24 | 한국화학연구원 | Polymer electrolyte membrane including boronnitride, method of preparing the same, and litium secondary battery including the same |
| CN109546207A (en) * | 2018-11-30 | 2019-03-29 | 西安交通大学 | A kind of composite solid polymer electrolyte film and its preparation method and application |
| CN109755645A (en) * | 2018-12-28 | 2019-05-14 | 西安交通大学 | Boron nitride/polyethylene glycol oxide composite solid electrolyte preparation method and application |
| CN109802173A (en) * | 2019-01-24 | 2019-05-24 | 北京化工大学 | A kind of three-phase organic/inorganic plural gel state polymer dielectric and preparation method thereof |
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