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CN-119517998-B - Membrane electrode suitable for low-humidity working condition and preparation method

CN119517998BCN 119517998 BCN119517998 BCN 119517998BCN-119517998-B

Abstract

The invention relates to a preparation method of a membrane electrode suitable for a low-humidity working condition, which comprises the following steps of (1) dissolving ionic liquid in ultrapure water, uniformly dispersing to obtain an ionic liquid aqueous solution, (2) uniformly mixing the ionic liquid aqueous solution obtained in the step (1) with a catalyst, coating the ionic liquid on the surface of the catalyst, cleaning and drying the coated catalyst to obtain an ionic liquid coated catalyst, (3) uniformly mixing the ionic liquid coated catalyst obtained in the step (2), an ionomer and a dispersion solvent, preparing catalyst slurry, spraying to prepare a cathode catalytic layer, and (4) hot-pressing the cathode catalytic layer and an anode catalytic layer obtained in the step (3) to two sides of a proton exchange membrane to prepare the membrane electrode. Compared with the prior art, the membrane electrode can ensure the high-efficiency transmission of protons in the catalytic layer under the working condition of low humidity, realize the operation under the wide working condition, enhance the oxygen mass transfer and improve the battery performance under the high current density.

Inventors

  • CHENG XIAOJING
  • ZHANG JUNLIANG
  • SHEN SHUIYUN
  • YAN XIAOHUI
  • YIN JIEWEI
  • LUO LIUXUAN

Assignees

  • 上海交通大学

Dates

Publication Date
20260512
Application Date
20241016

Claims (7)

  1. 1. The preparation method of the membrane electrode suitable for the low-humidity working condition is characterized by comprising the following steps of: (1) Dissolving an ionic liquid in ultrapure water, and uniformly dispersing to obtain an ionic liquid aqueous solution, wherein the ionic liquid is 1-butyl-3-methylimidazole bistrifluoromethane sulfonyl imide salt ([ BMIM ] [ NTF 2 ]), and the mass ratio of the ionic liquid to the ultrapure water is 1:450-1:550; (2) Uniformly mixing the ionic liquid aqueous solution obtained in the step (1) with a catalyst, coating the ionic liquid on the surface of the catalyst by a two-stage rotary evaporation process, and cleaning and drying the coated catalyst to obtain the ionic liquid coated catalyst, wherein the two-stage rotary evaporation process comprises the steps of rotating at 60-80 rpm in a first stage, rotating at 50-60 ℃ in a water bath for 1-10 h, rotating at 80-100 rpm in a second stage, and rotating at 60-80 ℃ in a water bath for 1-10 h; (3) Uniformly mixing the ionic liquid coated catalyst obtained in the step (2) with an ionomer and a dispersion solvent to prepare catalyst slurry, and spraying to prepare a cathode catalytic layer; (4) And (3) hot-pressing the cathode catalytic layer and the anode catalytic layer obtained in the step (3) to two sides of the proton exchange membrane to obtain the prepared membrane electrode.
  2. 2. The method for preparing a membrane electrode suitable for low humidity conditions according to claim 1, wherein the mixing mode of the ionic liquid and the ultrapure water in the step (1) is that the ionic liquid is added into the ultrapure water; The dispersing mode is magnetic stirring, and the dispersing time is 1-5 h.
  3. 3. The method for preparing the membrane electrode suitable for the low-humidity working condition according to claim 1, wherein the mass ratio of the catalyst to the ionic liquid aqueous solution in the step (2) is 1:100-1:5000.
  4. 4. The method for preparing the membrane electrode suitable for the low-humidity working condition according to claim 1, wherein the catalyst in the step (2) is one or more of a carbon-supported platinum catalyst, a carbon-supported platinum alloy catalyst, a core-shell catalyst and a non-noble metal catalyst, the ionomer is a perfluorosulfonic acid ionomer, and the dispersion solvent is one or more of deionized water, isopropanol and ethanol.
  5. 5. The method for preparing the membrane electrode suitable for the low-humidity working condition according to claim 1, wherein the mixing method in the step (3) is ultrasonic dispersion, and the dispersion time is 10-60 min; The spraying method is electrostatic spraying or ultrasonic spraying.
  6. 6. The method for preparing the membrane electrode suitable for the low-humidity working condition according to claim 1, wherein the hot pressing temperature in the step (4) is 120-150 ℃, and the hot pressing time is 1-10min.
  7. 7. A membrane electrode adapted for low humidity conditions, characterized by being manufactured by the method of any one of claims 1-6.

Description

Membrane electrode suitable for low-humidity working condition and preparation method Technical Field The invention relates to the technical field of fuel cells, in particular to a membrane electrode suitable for a low-humidity working condition and a preparation method thereof. Background The proton exchange membrane fuel cell is the most main form of hydrogen energy utilization, can convert chemical energy stored in hydrogen into electric energy through an electrochemical method, and has the advantages of high energy conversion rate, no pollution, quick dynamic response and the like. At present, the main application direction of the fuel cell is a new energy automobile, so that the fuel cell needs to cope with changeable operation conditions, especially low-humidity operation conditions. However, proton transfer in the catalytic layer of the membrane electrode is highly dependent on proton transfer channels constructed by hydration of the ionomer, so that the proton transfer channels are cut off due to the fact that the hydration degree of the ionomer is reduced under a low humidity working condition, and meanwhile, the hydrophobic and hydrophilic areas in the ionomer of the catalytic layer are distributed and changed due to low water content, so that oxygen is not beneficial to penetrating through the ionomer membrane to reach catalytic active sites, and the local oxygen mass transfer resistance is improved. The patent ZL201910585539.0 discloses a preparation method of a membrane electrode capable of improving the low-humidity operation performance of a proton exchange membrane fuel cell, which ensures that the membrane electrode of the proton exchange membrane fuel cell has certain self-humidifying capacity by adding a proper amount of covalent organic framework materials into a cathode catalytic layer and an anode catalytic layer, so that the fuel cell can stably operate under the low-humidity condition, and meanwhile, the proton transfer efficiency inside the cell is obviously improved and the current density and the power density of the cell are also improved to a certain extent due to the certain self-humidifying capacity of the membrane electrode. Meanwhile, the technology directly adds the triazine covalent organic framework material into the slurry of the catalytic layer to directly prepare the catalytic layer, and the triazine covalent organic framework material may be dissolved in product water and carried away from the catalytic layer in the long-time operation process, so that the water retention capacity of the membrane electrode is reduced and the proton transmission performance is weakened. Disclosure of Invention The invention aims to overcome the defects of the prior art and provide a membrane electrode suitable for a low-humidity working condition and a preparation method thereof, which ensure proton transmission and strengthen oxygen local mass transfer. The invention aims at realizing the preparation method of the membrane electrode suitable for the low-humidity working condition, which comprises the following steps: (1) Dissolving the ionic liquid in ultrapure water, and uniformly dispersing to obtain an ionic liquid aqueous solution; (2) Uniformly mixing the ionic liquid aqueous solution obtained in the step (1) with a catalyst, coating the ionic liquid on the surface of the catalyst, and cleaning and drying the coated catalyst to obtain an ionic liquid coated catalyst; (3) Uniformly mixing the ionic liquid coated catalyst obtained in the step (2) with an ionomer and a dispersion solvent to prepare catalyst slurry, and spraying to prepare a cathode catalytic layer; (4) And (3) hot-pressing the cathode catalytic layer and the anode catalytic layer obtained in the step (3) to two sides of the proton exchange membrane to obtain the prepared membrane electrode. Further, the ionic liquid is 1-butyl-3-methylimidazole bis (trifluoromethanesulfonyl imide) salt ([ BMIM ] [ NTF 2 ]). Further, the mass ratio of the ionic liquid to the ultrapure water in the step (1) is 1:200-1:1000. Further, the ionic liquid and the ultrapure water in the step (1) are mixed in such a way that the ionic liquid is added to the ultrapure water, and the ultrapure water cannot be added to the ionic liquid. (adding the ionic liquid before adding the water may cause local agglomeration of the ionic liquid, and affect the dissolution speed and the dissolution effect). The dispersing mode is magnetic stirring, and the dispersing time is 1-5 h. Further, the mass ratio of the catalyst to the ionic liquid aqueous solution in the step (2) is 1:100-1:5000. Further, the coating method in the step (2) is rotary evaporation, and specifically comprises two stages, wherein the rotating speed of the first stage is 60-80 rpm, the water bath temperature is 50-60 ℃, the time is 1-10 h, uneven temperature distribution in the eggplant-shaped bottle can be caused by the too low rotating speed, liquid vibration can be caused by the too