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CN-121983609-A - Sulfonated fluorine-containing polyimide-metal organic framework composite film and preparation method and application thereof

CN121983609ACN 121983609 ACN121983609 ACN 121983609ACN-121983609-A

Abstract

The invention discloses a sulfonated fluorine-containing polyimide-metal organic frame composite membrane and a preparation method and application thereof, and belongs to the technical field of all-vanadium redox flow battery diaphragms. The method comprises the steps of synthesizing sulfonated fluorine-containing polyimide FSPI by a high-temperature one-step method, preparing metal organic framework MIL-101 (Cr) by a hydrothermal method, preparing metal organic framework alpha-Fe 2 O 3 /MIL-101 (Cr) by the hydrothermal method, and preparing the sulfonated fluorine-containing polyimide-metal organic framework composite film FSPI/alpha-Fe 2 O 3 /MIL-101 (Cr) by a tape casting method. The ion transmission channel is regulated by introducing a metal organic framework alpha-Fe 2 O 3 /MIL-101 (Cr) into the sulfonated fluorine-containing polyimide. The regulated ion transmission channel is larger than hydrated protons (< 0.24 nm) and smaller than hydrated vanadium ions (> 0.6 nm), so that the ion selectivity of the sulfonated fluorine-containing polyimide membrane is improved. The composite membrane prepared by the invention has high proton conductivity, good vanadium resistance and excellent ion selectivity. The prepared composite membrane is used in an all-vanadium redox flow battery, so that the cycling stability of the battery is improved.

Inventors

  • WANG XIAOMING
  • LI WEN
  • FENG YU
  • WENG LING
  • YUE DONG

Assignees

  • 哈尔滨理工大学

Dates

Publication Date
20260505
Application Date
20260204

Claims (10)

  1. 1. The preparation method of the sulfonated fluorine-containing polyimide-metal organic framework composite membrane is characterized by comprising the following steps of: Step 1, in an inert gas atmosphere, m-cresol and triethylamine are sequentially added into BDSA, after complete dissolution, TFMB and NTDA are added, benzoic acid is added, stirring reaction is carried out at 70-90 ℃, then heating is carried out to 170-190 ℃ and stirring is continued, after the reaction is completed, the mixture is poured into acetone for precipitation and washing, and vacuum drying is carried out, so that sulfonated fluorine-containing polyimide is obtained; Step 2, adding Cr (NO 3 ) 3 ·9H 2 O, terephthalic acid and hydrofluoric acid into deionized water, performing ultrasonic dispersion, performing hydrothermal reaction at 210-230 ℃, cooling after the reaction is finished, performing centrifugal washing sequentially by using N, N-dimethylformamide and absolute ethyl alcohol, and performing vacuum drying to obtain MIL-101 (Cr); Step 3, adding MIL-101 (Cr) and FeCl 3 ·6H 2 O into deionized water, performing ultrasonic dispersion at room temperature, performing hydrothermal reaction at 130-150 ℃, cooling after the reaction is finished, sequentially performing centrifugal washing by using N, N-dimethylformamide and absolute ethyl alcohol, and performing vacuum drying to obtain alpha-Fe 2 O 3 /MIL-101 (Cr); And 4, adding alpha-Fe 2 O 3 /MIL-101 (Cr) and sulfonated fluorine-containing polyimide into a dimethyl sulfoxide solution, stirring for reaction at 80 ℃, cooling to room temperature after the reaction is finished, drying in vacuum, immersing the mixture into a sulfuric acid solution for protonation treatment after the reaction is finished, and flushing with deionized water.
  2. 2. The method according to claim 1, wherein the mass ratio of BDSA, TFMB, NTDA, m-cresol, triethylamine and benzoic acid is (150-60): (5-8): (50-70): (540-550): (210-220): (210-220).
  3. 3. The method according to claim 1, wherein the ratio of Cr (NO 3 ) 3 ·9H 2 O, terephthalic acid, hydrofluoric acid, and deionized water is (1-3) mmol (1-3) ml (13-15) ml.
  4. 4. The method of claim 1, wherein the ratio of MIL-101 (Cr), feCl 3 ·6H 2 O, and deionized water is (0.1-0.2) g (0.2-0.4) g (20-40) ml.
  5. 5. The method according to claim 1, wherein the mass ratio of alpha-Fe 2 O 3 /MIL-101 (Cr), sulfonated fluorine-containing polyimide and dimethyl sulfoxide is 1 (100-200): 2020-4060.
  6. 6. The method of claim 1, wherein the inert gas is nitrogen.
  7. 7. The method according to claim 1, wherein the film is produced by a solution casting method or a casting method.
  8. 8. The method according to claim 1, wherein the sulfuric acid solution has a concentration of 1-3mol/L.
  9. 9. A sulfonated fluorine-containing polyimide-metal organic framework composite film prepared by the method of any one of claims 1 to 8, wherein the thickness is 5-50 μm, and the alpha-Fe 2 O 3 /MILs-101 (Cr) is a metal organic framework with a heterojunction structure.
  10. 10. A sulfonated fluorine-containing polyimide-metal organic framework composite membrane made by the method of any one of claims 1-8 for use as a separator in an all-vanadium flow battery.

Description

Sulfonated fluorine-containing polyimide-metal organic framework composite film and preparation method and application thereof Technical Field The invention belongs to the field of all-vanadium redox flow battery diaphragms, and particularly relates to a sulfonated fluorine-containing polyimide-metal organic frame composite film for an all-vanadium redox flow battery, and a preparation method and application thereof. Background To drive the development of renewable energy technologies that utilize clean energy sources (such as solar and wind), it is critical to develop large-scale energy storage systems. Among various energy storage technologies, the all-vanadium redox flow battery is expected to become a feasible choice for large-scale application due to the characteristics of environmental protection, long-cycle stability, high capacity, high power and the like. The proton exchange membrane is used as a core component of the all-vanadium redox flow battery, not only bears the key task of blocking positive and negative electrolyte, but also constructs a high-efficiency proton transmission channel, and plays a decisive role in the performance of the battery. In order to achieve high cell efficiency, it is important to improve proton conductivity and ion selectivity of the membrane. The perfluorosulfonic acid membrane Nafion ® developed by dupont is widely used for its excellent chemical stability and excellent proton conductivity. However, the ion channels (3-5 nm) in Nafion membranes are significantly larger than the diameters of hydrated protons (< 0.24 nm) and hydrated vanadium ions (> 0.6 nm), which results in lower ion selectivity. In addition, its high cost further limits its large-scale application. Therefore, it has become urgent to develop a new film material having excellent properties and low cost. Sulfonated polyimides have been attracting attention for their excellent chemical stability and excellent mechanical properties. Higher Degrees of Sulfonation (DS) are generally required to achieve high proton conductivity in all-vanadium flow batteries. However, too high DS may exacerbate vanadium ion penetration. Therefore, in the development process of the separator, achieving a balance between enhancement of proton conductivity and inhibition of vanadium ion permeation has become a core problem. Ion selectivity (defined as the ratio of proton conductivity to vanadium ion permeability) as a core parameter quantifying the equilibrium relationship directly reflects the proton and vanadium ion screening capability of the proton exchange membrane. Disclosure of Invention Aiming at the problems, the invention provides a sulfonated fluorine-containing polyimide-metal organic frame composite membrane, and a preparation method and application thereof. The invention aims to regulate and control an ion transmission channel by introducing a metal organic framework into sulfonated fluorine-containing polyimide. The regulated ion transmission channel is larger than hydrated protons (< 0.24 nm) and smaller than hydrated vanadium ions (> 0.6 nm), so that the ion selectivity of the sulfonated fluorine-containing polyimide membrane is improved. In order to realize the technical problems, the invention adopts the following technical scheme: The invention aims to provide a preparation method of a sulfonated fluorine-containing polyimide-metal organic frame composite membrane for an all-vanadium redox flow battery, which is characterized by comprising the following steps of: step 1, in an inert gas atmosphere, m-cresol and triethylamine are sequentially added into BDSA, after being completely dissolved, TFMB and NTDA are added, benzoic acid is added, stirring reaction is carried out at 70-90 ℃, then heating is carried out to 170-190 ℃ and stirring is continued, after the reaction is finished, the mixture is poured into acetone for precipitation and washing, and vacuum drying is carried out, so that sulfonated fluorine-containing polyimide is obtained; Step 2, adding Cr (NO 3)3·9H2 O, terephthalic acid and hydrofluoric acid into deionized water, performing ultrasonic dispersion, performing hydrothermal reaction at 210-230 ℃, cooling after the reaction is finished, performing centrifugal washing sequentially by using N, N-dimethylformamide and absolute ethyl alcohol, and performing vacuum drying to obtain MIL-101 (Cr); Adding MIL-101 (Cr) and FeCl 3·6H2 O into deionized water, performing ultrasonic dispersion at room temperature, performing hydrothermal reaction at 130-150 ℃, cooling after the reaction is finished, performing centrifugal washing sequentially by using N, N-dimethylformamide and absolute ethyl alcohol, and performing vacuum drying to obtain alpha-Fe 2O3/MIL-101 (Cr); And 4, adding alpha-Fe 2O3/MIL-101 (Cr) and sulfonated fluorine-containing polyimide into dimethyl sulfoxide solution, stirring for reaction at 80 ℃, cooling to room temperature after the reaction is finished, preparing a film, drying in vacuu