CN117913205A - Preparation method of zinc cathode protective coating based on dual-gradient zinc-philic-conductive - Google Patents
Preparation method of zinc cathode protective coating based on dual-gradient zinc-philic-conductive Download PDFInfo
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- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 title claims abstract description 100
- 239000011701 zinc Substances 0.000 title claims abstract description 100
- 229910052725 zinc Inorganic materials 0.000 title claims abstract description 100
- 239000011253 protective coating Substances 0.000 title claims abstract description 67
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- 229920000049 Carbon (fiber) Polymers 0.000 claims abstract description 73
- 239000004917 carbon fiber Substances 0.000 claims abstract description 73
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 47
- 229920000642 polymer Polymers 0.000 claims abstract description 36
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 28
- 229910052709 silver Inorganic materials 0.000 claims abstract description 28
- 239000004332 silver Substances 0.000 claims abstract description 28
- 239000002002 slurry Substances 0.000 claims abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 238000000576 coating method Methods 0.000 claims abstract description 9
- 239000011248 coating agent Substances 0.000 claims abstract description 8
- 238000007581 slurry coating method Methods 0.000 claims abstract description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 15
- 239000010410 layer Substances 0.000 claims description 13
- 238000003756 stirring Methods 0.000 claims description 13
- 239000008367 deionised water Substances 0.000 claims description 12
- 229910021641 deionized water Inorganic materials 0.000 claims description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 8
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 7
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 7
- PLKATZNSTYDYJW-UHFFFAOYSA-N azane silver Chemical compound N.[Ag] PLKATZNSTYDYJW-UHFFFAOYSA-N 0.000 claims description 7
- 238000009210 therapy by ultrasound Methods 0.000 claims description 7
- 238000001291 vacuum drying Methods 0.000 claims description 7
- 239000002033 PVDF binder Substances 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 6
- 239000000376 reactant Substances 0.000 claims description 6
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- ZFSLODLOARCGLH-UHFFFAOYSA-N isocyanuric acid Chemical compound OC1=NC(O)=NC(O)=N1 ZFSLODLOARCGLH-UHFFFAOYSA-N 0.000 claims description 5
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 5
- CLYVDMAATCIVBF-UHFFFAOYSA-N pigment red 224 Chemical compound C=12C3=CC=C(C(OC4=O)=O)C2=C4C=CC=1C1=CC=C2C(=O)OC(=O)C4=CC=C3C1=C42 CLYVDMAATCIVBF-UHFFFAOYSA-N 0.000 claims description 5
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 238000006116 polymerization reaction Methods 0.000 claims description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 3
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 3
- 238000000137 annealing Methods 0.000 claims description 3
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 claims description 3
- 239000008103 glucose Substances 0.000 claims description 3
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 3
- 230000008021 deposition Effects 0.000 abstract description 13
- 210000001787 dendrite Anatomy 0.000 abstract description 7
- 239000000463 material Substances 0.000 abstract description 4
- 238000013459 approach Methods 0.000 abstract description 3
- 230000002860 competitive effect Effects 0.000 abstract description 3
- 230000002441 reversible effect Effects 0.000 abstract description 3
- 210000004027 cell Anatomy 0.000 description 21
- 230000009977 dual effect Effects 0.000 description 20
- 150000003751 zinc Chemical class 0.000 description 12
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 9
- 239000003792 electrolyte Substances 0.000 description 9
- 229910052802 copper Inorganic materials 0.000 description 7
- 239000010949 copper Substances 0.000 description 7
- 239000000047 product Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000010276 construction Methods 0.000 description 4
- 238000002484 cyclic voltammetry Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 150000001879 copper Chemical class 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 230000005684 electric field Effects 0.000 description 3
- 238000004146 energy storage Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000013538 functional additive Substances 0.000 description 3
- 238000005457 optimization Methods 0.000 description 3
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 description 2
- RRKGBEPNZRCDAP-UHFFFAOYSA-N [C].[Ag] Chemical compound [C].[Ag] RRKGBEPNZRCDAP-UHFFFAOYSA-N 0.000 description 2
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 230000022131 cell cycle Effects 0.000 description 2
- 239000011889 copper foil Substances 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910001935 vanadium oxide Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000000840 electrochemical analysis Methods 0.000 description 1
- 238000004299 exfoliation Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 230000037427 ion transport Effects 0.000 description 1
- 239000002346 layers by function Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000010534 mechanism of action Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
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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
- 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
Abstract
The invention provides a preparation method of a zinc cathode protective coating based on dual-gradient zinc-philic-conductive, which comprises the steps of firstly preparing polymer-derived carbon fiber and silver-coated carbon fiber, respectively forming silver-coated carbon fiber slurry and polymer-derived carbon fiber slurry, and then sequentially coating the slurry and the slurry on a zinc sheet by a gradual slurry coating method to obtain a CF/Ag-CF@Zn electrode. The CF/Ag-CF@Zn electrode is provided with the double-gradient protective coating with the top layer of polymer derived carbon fiber and the bottom layer of silver coated carbon fiber, and can directionally guide the internal ion-electron flow to realize a safe bottom zinc deposition mode by means of inherent zinc affinity-conductivity difference of materials, thereby avoiding unfavorable top zinc dendrite growth, realizing a highly reversible and stable zinc cathode, and providing a more competitive approach for reasonably designing the zinc cathode coating to construct an ultra-stable water-based zinc battery.
Description
Technical Field
The invention belongs to the technical field of zinc metal batteries, and particularly relates to a preparation method of a zinc cathode protective coating based on dual-gradient zinc-conducting.
Background
The growing demand for renewable energy has driven the development of highly stable, eco-friendly and economically viable energy storage technologies. Among them, aqueous zinc batteries are receiving a great deal of attention as an emerging large-scale energy storage system. The zinc metal cathode has the advantages of high theoretical capacity (820 mAh g -1), low oxidation-reduction potential (-0.76V vs. Standard Hydrogen Electrode (SHE)), low cost and the like. Meanwhile, the nonflammable water-based electrolyte can simplify the assembly requirement, avoid the explosion risk of the battery device and reduce the manufacturing cost. However, limited by the short cycle life and low utilization of zinc cathodes, the practical use of aqueous zinc batteries still faces many challenges. During zinc deposition/exfoliation, uncontrolled 2D diffusion and sustained growth of zinc dendrites induced by non-uniform electric field distribution can lead to volume changes, parasitic reactions, and even puncture of the separator, resulting in capacity fade ultimately leading to cell failure. Therefore, it is important to effectively protect the zinc anode to inhibit dendrite growth and side reactions and to achieve stable and safe zinc deposition.
To solve the above problems, researchers have proposed various strategies to improve the zinc anode/electrolyte interface stability, mainly including construction of artificial protective coatings, electrolyte optimization and structural design. Among these, the construction of functional protective layers is considered a simple, efficient strategy to improve interface environments and to improve stability, as it avoids continuous consumption of functional additives, expensive concentrated electrolytes, and complex manufacturing techniques. The alloy cathode and the metal-based coating material have higher zinc affinity and conductivity, and can increase nucleation sites and uniform electric field distribution. However, corrosion, competing reactions of metal species, and harsh manufacturing conditions have hampered their widespread use. In addition, inorganic or organic functional coatings have higher ion transport capabilities, but lower electron conduction properties can disrupt interfacial charge transfer and increase polarization voltage. In addition, zinc deposits between the zinc surface and the coating may cause the functional layer to be detached from the zinc surface during repeated cycles. Therefore, the reasonable design of the functional protective coating to carry out directional safe regulation and control on the zinc ion deposition mode is a key strategy for realizing high-performance and dendrite-free zinc cathodes.
Disclosure of Invention
The invention aims to solve the problems, and aims to provide a preparation method of a zinc cathode protective coating based on dual-gradient zinc-philic-conductive.
The invention provides a preparation method of a zinc cathode protective coating based on dual-gradient zinc-philic-conductive, which has the characteristics that the preparation method comprises the following steps: step S1, cyanuric acid and perylene-3, 4,9, 10-tetracarboxylic dianhydride are added into dimethylformamide, stirred and mixed at room temperature and transferred into a high-pressure reaction kettle for polymerization, a reactant is obtained, and the reactant is filtered, washed and dried to obtain a black green porous polymer, and then the black green porous polymer is annealed in a nitrogen atmosphere to obtain polymer-derived carbon fibers;
S2, dissolving SnCl 2·2H2 O in H 2 O, adding polymer derived carbon fibers, and performing ultrasonic treatment to obtain Sn 2+ sensitized carbon fibers;
Step S3, adding the Sn 2+ sensitized carbon fiber into fresh silver ammonia solution, dropwise adding glucose and NaOH, stirring at room temperature to obtain a product, washing and drying the product to obtain silver coated carbon fiber;
And S4, respectively mixing polyvinylidene fluoride with polymer-derived carbon fibers and silver-coated carbon fibers, stirring in N-methyl pyrrolidone to respectively obtain polymer-derived carbon fiber slurry and silver-coated carbon fiber slurry, sequentially coating the silver-coated carbon fiber slurry and the polymer-derived carbon fiber slurry on a zinc sheet by a step-by-step slurry coating method, and vacuum drying to obtain the CF/Ag-CF@Zn electrode, wherein the CF/Ag-CF@Zn electrode is provided with a double-gradient protective coating layer composed of polymer-derived carbon fibers as a top layer and silver-coated carbon fibers as a bottom layer.
The preparation method of the zinc anode protective coating based on dual-gradient zinc-conducting can also have the following characteristics: wherein the ratio of cyanuric acid to perylene-3, 4,9, 10-tetracarboxylic dianhydride and dimethylformamide is 1 mmol/10 mL.
The preparation method of the zinc anode protective coating based on dual-gradient zinc-conducting can also have the following characteristics: wherein, in the step S1, polymerization is carried out for 22-26 h at 160-200 ℃.
The preparation method of the zinc anode protective coating based on dual-gradient zinc-conducting can also have the following characteristics: in the step S1, the stirring time is 10-14 h.
The preparation method of the zinc anode protective coating based on dual-gradient zinc-conducting can also have the following characteristics: wherein, in the step S1, when drying is carried out, the vacuum drying is carried out at 70-90 ℃ for 22-26 h.
The preparation method of the zinc anode protective coating based on dual-gradient zinc-conducting can also have the following characteristics: wherein, in the step S1, annealing is performed for 1h to 3h in nitrogen atmosphere at the temperature of 550 ℃ to 650 ℃.
The preparation method of the zinc anode protective coating based on dual-gradient zinc-conducting can also have the following characteristics: in the step S2, the mass ratio of SnCl 2·2H2 O to the polymer-derived carbon fiber is 4:1, the ultrasonic treatment time is 20-40 min, and after the ultrasonic treatment is finished, deionized water and ethanol are used for washing the Sn 2+ sensitized carbon fiber for a plurality of times.
The preparation method of the zinc anode protective coating based on dual-gradient zinc-conducting can also have the following characteristics: in step S3, silver nitrate is added into deionized water, and then ammonia water is added dropwise to prepare a fresh silver-ammonia solution.
The preparation method of the zinc anode protective coating based on dual-gradient zinc-conducting can also have the following characteristics: in the step S3, stirring time is 20-40 min, washing the product with deionized water and ethanol for multiple times, and then vacuum drying at 70-90 ℃ for 22-26 h to obtain the silver-coated carbon fiber.
The preparation method of the zinc anode protective coating based on dual-gradient zinc-conducting can also have the following characteristics: in the step S4, the mass ratio of the polyvinylidene fluoride to the polymer-derived carbon fiber to the silver-coated carbon fiber is 1:4, and the stirring time is 10-14 h.
Effects and effects of the invention
According to the preparation method of the zinc cathode protective coating based on dual-gradient zinc-conducting, firstly, polymer-derived carbon fibers and silver-coated carbon fibers are prepared, corresponding slurries are respectively formed, and then the polymer-derived carbon fibers and the silver-coated carbon fibers are coated on zinc sheets by a gradual slurry coating method, so that the carbon-silver dual-gradient protective coating with the polymer-derived carbon fibers as the top layer and the silver-coated carbon fibers as the bottom layer is formed. The double-gradient protective coating can directionally guide the internal ion-electron flow to realize a safe bottom zinc deposition mode by means of inherent zinc affinity-conductivity difference of materials, avoid the cell short circuit caused by unfavorable top zinc dendrite growth and penetration of a diaphragm, construct a highly reversible and highly stable zinc cathode, and provide a more competitive approach for reasonably designing the zinc cathode coating to construct an ultra-stable water-based zinc cell. In addition, compared with the methods of electrolyte optimization, structural design and the like in the prior art, the method can avoid continuous consumption of functional additives, expensive concentrated electrolyte and complex manufacturing technology by constructing the dual-gradient protective coating.
Drawings
FIG. 1 is a schematic illustration of the mechanism of action of a dual gradient protective coating in an embodiment of the invention;
FIG. 2 is a scanning electron microscope image of an initial cross section, a recycled cross section, and a recycled top of a dual gradient protective coating modified zinc electrode and pure zinc electrode prepared in an example of the present invention;
FIG. 3 is a symmetrical cell rate performance of a dual gradient protective coating modified zinc electrode and a pure zinc electrode prepared in an example of the invention;
FIG. 4 is a symmetrical cell cycling stability of a dual gradient protective coating modified zinc electrode and a pure zinc electrode prepared in an embodiment of the invention;
FIG. 5 is the coulombic efficiency of half-cell zinc deposition/stripping for dual gradient protective coating modified copper electrodes and pure copper electrodes prepared in the examples of the present invention;
FIG. 6 is a cyclic voltammogram and constant current charge-discharge curve of KVOH full cells constructed with dual gradient protective coating modified zinc electrodes and pure zinc electrodes prepared in the examples of the present invention;
fig. 7 is KVOH full cell cycle performance of a dual gradient protective coating modified zinc electrode and a pure zinc electrode construction prepared in the examples of the present invention.
Detailed Description
In order to make the technical means, creation characteristics, achievement purposes and effects achieved by the present invention easy to understand, the following embodiment describes a preparation method of a zinc negative electrode protective coating based on dual-gradient zinc-philic-conductive with reference to the accompanying drawings.
< Example >
The preparation method of the zinc cathode protective coating based on dual-gradient zinc-conducting comprises the following steps:
Step S1, adding 5mmol of cyanuric acid and 5mmol of perylene-3, 4,9, 10-tetracarboxylic dianhydride into 50mL of dimethylformamide, stirring and mixing at room temperature for 12h, transferring to a high-pressure reaction kettle, polymerizing at 180 ℃ for 24h to obtain a reactant, filtering and washing the reactant with ethanol, and vacuum drying at 80 ℃ for 24h to obtain a black green porous polymer, and annealing the product in a nitrogen atmosphere at 600 ℃ for 2h to obtain the polymer derivative Carbon Fiber (CF).
And S2, dissolving 0.12g of SnCl 2·2H2 O in 10mL of H 2 O, adding 0.03g of polymer-derived carbon fiber, performing ultrasonic treatment for 30min to obtain Sn 2+ sensitized carbon fiber, and washing with deionized water and ethanol for multiple times.
Step S3, firstly, preparing a fresh silver-ammonia solution: 0.6g of silver nitrate was added to 2ml of deionized water, and then an appropriate amount of aqueous ammonia (6.6 wt%) was added dropwise to form a fresh silver ammonia solution. And then adding the Sn 2+ sensitized carbon fiber into fresh silver ammonia solution, dropwise adding a proper amount of glucose and NaOH, stirring at room temperature for 30min to obtain a product, washing the product with deionized water and ethanol for multiple times, and then drying at 80 ℃ in vacuum for 24h to obtain the silver coated carbon fiber (Ag-CF).
And S4, respectively mixing polyvinylidene fluoride with polymer-derived carbon fibers CF and silver-coated carbon fibers Ag-CF in a mass ratio of 1:4, and stirring in N-methylpyrrolidone for 12 hours to respectively obtain polymer-derived carbon fiber slurry and silver-coated carbon fiber slurry. Then, silver-coated carbon fiber slurry and polymer-derived carbon fiber slurry are sequentially coated on a zinc sheet with the thickness of 30 μm by a step-by-step slurry coating method by using a scraper type coater with the heights of 20 μm and 40 μm respectively, and the zinc sheet is dried in vacuum at 80 ℃ for 24 hours to obtain the CF/Ag-CF@Zn electrode.
The CF/Ag-CF@Zn electrode is provided with a double-gradient protective coating layer consisting of polymer derived carbon fibers as a top layer and silver coated carbon fibers as a bottom layer.
Fig. 1 is a schematic diagram of the action mechanism of the dual gradient protective coating in the embodiment of the present invention, fig. 2 is a scanning electron microscope image of an initial cross section, a cross section after circulation, and a top after circulation of the dual gradient protective coating modified zinc electrode and the pure zinc electrode prepared in the embodiment of the present invention, and fig. 2 (a) the dual gradient protective coating modified zinc electrode and (b) the pure zinc electrode.
As shown in fig. 1 and 2, during zinc deposition/stripping, uncontrolled 2D diffusion and uneven electric field distribution will induce continuous growth of top zinc dendrites, while the dual-gradient protective coating in this embodiment can perform directional safe regulation and control on the zinc ion deposition mode by forming dual-gradient zinc-philic-conductive structures on the surface of the zinc negative electrode, and direct ion-electron flow to realize a safe bottom zinc deposition mode, avoid unfavorable top zinc dendrite growth, and realize a high-performance and dendrite-free zinc negative electrode.
Further, in this example, an electrochemical test was also performed, specifically as follows:
a GE-Whatman glass fiber separator was used, and a CR2032 type battery device was used with 2.0M ZnSO 4 as the electrolyte.
The symmetrical battery adopts two identical zinc electrodes or pure zinc electrodes modified by double gradient protective coatings.
The asymmetric battery uses a copper foil or pure copper foil decorated by a double-gradient protective coating as a working electrode and pure zinc as a counter electrode.
The full battery adopts a zinc electrode modified by a double gradient protective coating or a pure zinc electrode as a negative electrode and KVOH as a positive electrode. The preparation method of KVOH positive electrode is as follows:
First, a modified hydrothermal method is adopted to synthesize KVOH: 0.182mg of V 2O5 was dissolved in 25mL of deionized water, and 1mL of 30% H 2O2 was added dropwise. 0.0435mg K 2SO4 was dissolved in 15mL deionized water. The resulting precipitate was washed three times with deionized water and ethanol and dried in vacuo at 80℃for 24 hours to give green KV 12O30-y·nH2 O (KVOH).
Then KVOH, graphite and polyvinylidene fluoride are mixed according to the mass ratio of 7:2:1, and a proper amount of N-methyl pyrrolidone is added for fully grinding to prepare slurry. The slurry is uniformly coated on a titanium foil and dried in vacuum at 80 ℃ for 24 hours, so that KVOH positive electrode is obtained, and the load mass of KVOH is about 3-5mg cm -2. The device energy storage performance was tested by the CHI660E electrochemical workstation.
Fig. 3 is a symmetrical cell rate performance of a dual gradient protective coating modified zinc electrode and a pure zinc electrode prepared in an example of the present invention.
As shown in fig. 3, the double gradient protective coating modified zinc electrode assembled symmetrical cell has a smaller overpotential compared to the symmetrical cell assembled with a pure zinc electrode, indicating that the modified electrode zinc deposition kinetics are more efficient.
Fig. 4 is a symmetrical cell cycling stability of a dual gradient protective coating modified zinc electrode and a pure zinc electrode prepared in an example of the invention.
As shown in fig. 4, the symmetrical zinc cell assembled in this example achieved a significant cycle life of over 6700 hours at a current density of 5mA cm -2.
In this embodiment, based on the above method, the pure zinc electrode is replaced by the pure copper electrode, and the copper electrode modified by the dual gradient protective coating is prepared, and meanwhile, the pure copper electrode and the copper electrode modified by the dual gradient protective coating are further subjected to a comparison test. Fig. 5 is the coulombic efficiency of half cell zinc deposition/stripping for dual gradient protective coating modified copper electrodes and pure copper electrodes prepared in the examples of the present invention.
As shown in fig. 5, the dual gradient protective coating modified copper electrode assembled half cell has a more stable coulombic efficiency than the pure copper electrode assembled half cell.
Fig. 6 is a cyclic voltammogram and a constant current charge-discharge curve of KVOH full cells constructed with a dual gradient protective coating modified zinc electrode and a pure zinc electrode prepared in the examples of the present invention, where (a) is a cyclic voltammogram and (a) is a constant current charge-discharge curve.
As shown in fig. 6, the assembled full cell of the zinc electrode modified by the dual gradient protective coating in this embodiment has higher current density and discharge capacity in both the cyclic voltammogram and the constant current charge-discharge curve compared to the full cell of the pure zinc electrode KVOH, which indicates that the zinc-philic-conductive protective coating can improve the reaction kinetics of the cell. Fig. 7 is KVOH full cell cycle performance of a dual gradient protective coating modified zinc electrode and a pure zinc electrode construction prepared in the examples of the present invention.
As shown in fig. 7, the capacity retention rate of the zinc-hydrated vanadium oxide (KVOH) full battery assembled in this example after being charged and discharged for 2000 times at a current density of 5A g -1 is 73% or more.
Effects and effects of the examples
According to the preparation method of the zinc cathode protective coating based on dual-gradient zinc-conducting, firstly, polymer-derived carbon fibers and silver-coated carbon fibers are prepared, corresponding slurries are respectively formed, and then the polymer-derived carbon fibers and the silver-coated carbon fibers are coated on a zinc sheet by a step-by-step slurry coating method, so that the carbon-silver dual-gradient protective coating with the polymer-derived carbon fibers as the top layer and the silver-coated carbon fibers as the bottom layer is formed. The double-gradient protective coating can directionally guide the internal ion-electron flow to realize a safe bottom zinc deposition mode by means of inherent zinc affinity-conductivity difference of materials, avoid the cell short circuit caused by unfavorable top zinc dendrite growth and penetration of a diaphragm, construct a highly reversible and highly stable zinc cathode, and provide a more competitive approach for reasonably designing the zinc cathode coating to construct an ultra-stable water-based zinc cell. In addition, compared with the methods of electrolyte optimization, structural design and the like in the prior art, the method for constructing the dual-gradient protective coating can avoid continuous consumption of functional additives, expensive concentrated electrolyte and complex manufacturing technology.
Further, electrochemical testing of this example shows that the assembled symmetric zinc cell of this example achieved significant cycle life of over 6700 hours and cumulative capacity up to 16.75Ah cm -2 at 5mA cm -2 current density, thanks to the dual gradient protective coating induced safe bottom deposition mode. Meanwhile, the capacity retention rate of the assembled zinc-hydrated vanadium oxide (KVOH) full battery after being circularly charged and discharged for 2000 times under the current density of 5A g -1 is above 68%.
It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. The preparation method of the zinc cathode protective coating based on dual-gradient zinc-conducting is characterized by comprising the following steps of:
step S1, cyanuric acid and perylene-3, 4,9, 10-tetracarboxylic dianhydride are added into dimethylformamide, stirred and mixed at room temperature and transferred into a high-pressure reaction kettle for polymerization, a reactant is obtained, and the reactant is filtered, washed and dried to obtain a black green porous polymer, and then the black green porous polymer is annealed in a nitrogen atmosphere to obtain polymer-derived carbon fibers;
S2, dissolving SnCl 2·2H2 O in H 2 O, adding the polymer-derived carbon fiber, and performing ultrasonic treatment to obtain Sn 2+ sensitized carbon fiber;
Step S3, adding the Sn 2+ sensitized carbon fiber into a fresh silver ammonia solution, dropwise adding glucose and NaOH, stirring at room temperature to obtain a product, and washing and drying the product to obtain silver coated carbon fiber;
Step S4, respectively mixing polyvinylidene fluoride with the polymer-derived carbon fibers and the silver-coated carbon fibers, stirring in N-methyl pyrrolidone to respectively obtain polymer-derived carbon fiber slurry and silver-coated carbon fiber slurry, sequentially coating the silver-coated carbon fiber slurry and the polymer-derived carbon fiber slurry on a zinc sheet by a step-by-step slurry coating method, vacuum drying to obtain the CF/Ag-CF@Zn electrode,
The CF/Ag-CF@Zn electrode is provided with a double-gradient protective coating layer, wherein the top layer is the polymer derived carbon fiber, and the bottom layer is the silver coated carbon fiber.
2. The method for preparing the zinc negative electrode protective coating based on dual-gradient zinc-conducting according to claim 1, which is characterized in that:
Wherein, in the step S1, the ratio of the cyanuric acid to the perylene-3, 4,9, 10-tetracarboxylic dianhydride and the dimethylformamide is 1mmol to 10mL.
3. The method for preparing the zinc negative electrode protective coating based on dual-gradient zinc-conducting according to claim 1, which is characterized in that:
wherein, in the step S1, polymerization is carried out for 22-26 h at 160-200 ℃.
4. The method for preparing the zinc negative electrode protective coating based on dual-gradient zinc-conducting according to claim 1, which is characterized in that:
In the step S1, the stirring time is 10-14 h.
5. The method for preparing the zinc negative electrode protective coating based on dual-gradient zinc-conducting according to claim 1, which is characterized in that:
wherein, in the step S1, when drying is carried out, the vacuum drying is carried out at 70-90 ℃ for 22-26 h.
6. The method for preparing the zinc negative electrode protective coating based on dual-gradient zinc-conducting according to claim 1, which is characterized in that:
wherein, in the step S1, annealing is performed for 1h to 3h in nitrogen atmosphere at the temperature of 550 ℃ to 650 ℃.
7. The method for preparing the zinc negative electrode protective coating based on dual-gradient zinc-conducting according to claim 1, which is characterized in that:
In the step S2, the mass ratio of SnCl 2·2H2 O to the polymer-derived carbon fiber is 4:1, the ultrasonic treatment time is 20-40 min, and deionized water and ethanol are used for washing the Sn 2+ sensitized carbon fiber for a plurality of times after the ultrasonic treatment is finished.
8. The method for preparing the zinc negative electrode protective coating based on dual-gradient zinc-conducting according to claim 1, which is characterized in that:
in the step S3, the fresh silver-ammonia solution is prepared by adding silver nitrate into deionized water and then dropwise adding ammonia water.
9. The method for preparing the zinc negative electrode protective coating based on dual-gradient zinc-conducting according to claim 1, which is characterized in that:
In the step S3, stirring time is 20-40 min, the product is washed with deionized water and ethanol for multiple times, and then vacuum drying is carried out at 70-90 ℃ for 22-26 h, so that the silver-coated carbon fiber is obtained.
10. The method for preparing the zinc negative electrode protective coating based on dual-gradient zinc-conducting according to claim 1, which is characterized in that:
In the step S4, the mass ratio of the polyvinylidene fluoride to the polymer-derived carbon fiber to the silver-coated carbon fiber is 1:4, and the stirring time is 10-14 h.
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