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CN-122025562-A - Zinc anode surface modified coating material, preparation method and application

CN122025562ACN 122025562 ACN122025562 ACN 122025562ACN-122025562-A

Abstract

The invention discloses a zinc anode surface modified coating material, a preparation method and application thereof, belonging to the field of electrochemical energy storage materials, wherein the coating material is formed by compounding ZIF-8 derived nitrogen doped porous carbon and polyvinylidene fluoride, the mass ratio of the porous carbon to the polyvinylidene fluoride is 6:4-8:2, the preparation method comprises the steps of ZIF-8 nanoparticle synthesis, high-temperature carbonization, slurry preparation, coating and drying, zinc uniform deposition is induced by Zn-N coordination sites of the nitrogen doped carbon to inhibit dendrites, and a PVDF hydrophobic layer blocks water molecules to inhibit hydrogen evolution reaction. The modified zinc cathode is 1 mA cm The lower recyclable layer is 2000 h or more, and the coulombic efficiency is over 99.5 percent.

Inventors

  • YANG HUAN
  • CAI WENLONG

Assignees

  • 四川大学

Dates

Publication Date
20260512
Application Date
20260213

Claims (10)

  1. 1. The zinc anode surface modified coating material is characterized in that the coating material is formed by compounding ZIF-8 derived nitrogen doped porous carbon and polyvinylidene fluoride, the ZIF-8 derived nitrogen doped porous carbon is prepared by carbonizing ZIF-8 nano particles at a high temperature of 700-1000 ℃ in an inert atmosphere, zinc nitrogen coordination sites are reserved in a carbon skeleton, and the specific surface area is 800-1500 m ·g The nitrogen content is 5-15 at%, and the mass ratio of the ZIF-8 derived nitrogen doped porous carbon to polyvinylidene fluoride is 6:4-8:2.
  2. 2. The zinc anode surface modified coating material according to claim 1, wherein the ZIF-8 derived nitrogen-doped porous carbon has a residual zinc content of 0.5-3 wt% and an average pore diameter of 1-5 nm.
  3. 3. The zinc anode surface modified coating material according to claim 1, wherein the thickness of the coating layer formed on the surface of the zinc anode is 1-10 μm.
  4. 4. A preparation method of a zinc anode surface modified coating material according to any one of claims 1-3 is characterized by comprising the following steps of firstly, respectively dissolving zinc salt and 2-methylimidazole in an organic solvent, mixing, reacting at room temperature to obtain ZIF-8 suspension, centrifuging, washing and drying to obtain ZIF-8 nano particles, secondly, preparing nitrogen doped porous carbon, namely carbonizing the ZIF-8 nano particles to 1-4 h at the temperature of 2-10 ℃ per minute under an inert atmosphere, cooling along with a furnace to obtain ZIF-8 derived nitrogen doped porous carbon, thirdly, mixing the ZIF-8 derived nitrogen doped porous carbon with polyvinylidene fluoride according to the mass ratio of 6:4-8:2, adding the organic solvent, dispersing uniformly to obtain coating slurry, fourthly, coating the coating slurry on the surface of the pretreated zinc foil, and drying to obtain the zinc anode with the modified coating.
  5. 5. The method according to claim 4, wherein in the first step, the zinc salt is selected from one or more of zinc nitrate hexahydrate, zinc acetate dihydrate or zinc chloride, the organic solvent is selected from one or more of methanol, ethanol or N, N-dimethylformamide, the molar ratio of the zinc salt to the 2-methylimidazole is 1:4-1:10, and the room temperature reaction time is 12-36 h.
  6. 6. The method of claim 4, wherein in the second step, the inert atmosphere is nitrogen or argon, the carbonization temperature is 800 ℃, and the heat preservation time is 2 h.
  7. 7. The method according to claim 4, wherein in the third step, the organic solvent is N-methylpyrrolidone, and the solid content of the slurry is 10-30 wt%.
  8. 8. The method according to claim 4, wherein in the fourth step, the zinc foil pretreatment comprises sanding to remove an oxide layer, activating with 0.1M hydrochloric acid and washing with deionized water, wherein the coating method is selected from knife coating, spin coating or spray coating, the drying temperature is 50-80 ℃, and the drying time is 6-24 h.
  9. 9. Use of the zinc anode surface modified coating material according to any one of claims 1 to 3 in an aqueous zinc ion battery.
  10. 10. The method according to claim 9, wherein the electrolyte of the aqueous zinc-ion battery is a zinc sulfate solution, a zinc chloride solution or a zinc triflate solution.

Description

Zinc anode surface modified coating material, preparation method and application Technical Field The invention belongs to the technical field of electrochemical energy storage materials, and particularly relates to a zinc anode surface modified coating material, a preparation method and application thereof. Background Aqueous zinc-ion batteries are highly safe, low-cost, environmentally friendly and have a high theoretical capacity (820 mAh g)) And the like, is considered to be one of secondary battery systems with the most development potential in the field of large-scale energy storage. The zinc cathode has lower oxidation-reduction potential (-0.76V vs. SHE), abundant natural resource reserves and mature recovery process, so that the zinc cathode shows unique competitiveness in practical application. However, zinc cathodes face three major core challenges during cycling, severely limiting the commercialization of aqueous zinc ion batteries. First, zinc dendrite growth problems. During the electroplating/stripping cycle, uneven deposition of zinc ions on the negative electrode surface results in the formation and growth of dendrites. These zinc dendrites not only reduce the efficiency of zinc utilization, but also present a potential safety hazard of puncturing the separator to cause internal shorting of the battery. Studies have shown that uneven distribution of local current density is a major cause of dendrite growth, especially at high current densities and high surface capacities, the dendrite problem is more pronounced. Second, hydrogen evolution side reaction problem. Since the redox potential of zinc is lower than the electrochemical decomposition potential of water, hydrogen Evolution Reaction (HER) inevitably occurs on the surface of the zinc anode, resulting in continuous consumption of electrolyte, corrosion of the zinc anode, and an increase in the internal gas pressure of the battery. The hydrogen generated by the hydrogen evolution reaction can also form a porous and loose deposition layer on the surface of zinc, so that the failure of the zinc cathode is further aggravated. Hydrated zinc ion [ Zn (H)O)]The active water molecules released during desolvation are more prone to decompose and produce hydrogen, which is particularly critical in long-term circulation. Third, zinc utilization is low and non-uniform deposition problems. Because of the lack of effective nucleation sites and ion transport channels on the surface of zinc cathodes, zinc ions tend to preferentially deposit in localized areas, forming dead zinc areas, resulting in a substantial reduction in the efficiency of active zinc utilization. Uneven zinc deposition morphology can also cause dramatic changes in the volume of the negative electrode, destroying the structural integrity of the electrode, ultimately leading to rapid decay in the cell capacity. In view of the above problems, researchers have proposed various solutions including electrolyte engineering, membrane modification, three-dimensional current collector design, interface coating protection, and the like. The interface coating protection strategy directly regulates and controls the transmission and deposition behaviors of zinc ions by constructing a functional protection layer on the surface of the zinc anode, and is considered as one of the most practical technical routes. The interface coating materials reported so far mainly comprise inorganic oxide coatings such as ZnO and TiOAlthough hydrogen evolution reaction can be inhibited to a certain extent, the ionic conduction performance is limited, organic polymer coatings such as polyvinyl alcohol, polyacrylic acid and the like have good flexibility but insufficient mechanical strength, metal Organic Framework (MOF) materials such as ZIF-8, uiO-66 and the like utilize the porous structure to regulate and control ion transmission, but the stability and the conductivity are poor when the metal organic framework is directly used. For example, chinese invention CN118645624a discloses a method for forming an organo-metal phosphate thin film coating on the surface of zinc negative electrode using hydroxyhexidene diphosphate (HEDP), forming a protective layer by chelation of phosphate group with zinc. Although the scheme can effectively inhibit hydrogen evolution reaction, the electronic conductivity of the coating is limited, and the high-rate charge-discharge requirement is difficult to meet. Meanwhile, a single organic phosphoric acid coating has a problem of insufficient stability in long-term circulation. In the prior art, a scheme that ZIF-8 is directly used as a zinc negative electrode protective layer is also reported, and zinc ion deposition is regulated and controlled by utilizing high adsorption energy and high surface diffusion barrier of nitrogen species in the ZIF-8 to zinc ions. However, ZIF-8 itself, which has not been heat-treated, does not have good electron conductivity, and its frame structure has a p