CN-121983585-A - Fuel cell membrane electrode catalytic layer, membrane electrode, and preparation method and application thereof

Abstract

The invention relates to the technical field of batteries, and provides a fuel cell membrane electrode catalytic layer, a membrane electrode, a preparation method and application thereof, wherein the fuel cell membrane electrode catalytic layer is formed by slurry, and the slurry mainly comprises carbon-ionomer aggregate, catalyst and first ionomer; the carbon-ionomer aggregate is obtained by mixing a second ionomer, a carbon material, and a first solvent, and then removing the first solvent. The catalyst layer prepared by further mixing the carbon-ionomer aggregate, the catalyst and the ionomer can build a continuous proton conduction network inside the catalyst layer, and can also prevent the surfaces of the active nano particles from being covered by the ionomer so as to improve the utilization rate of the catalyst and the electrochemical active area of the membrane electrode, thereby improving the power density of the fuel cell.

Inventors

• CHEN ZHONGWEI
• ZHANG YINING
• CHEN RUITING
• ZHOU QUAN

Assignees

• 榆林中科洁净能源创新研究院
• 中国科学院大连化学物理研究所

Dates

Publication Date

20260505

Application Date

20251212

Claims (10)

1. 1. A fuel cell membrane electrode catalytic layer formed from a slurry, wherein the slurry consists essentially of carbon-ionomer aggregates, a catalyst, and a first ionomer; The carbon-ionomer aggregate is obtained by mixing a second ionomer, a carbon material, and a first solvent, and then removing the first solvent.
2. 2. The fuel cell membrane electrode catalytic layer according to claim 1, characterized in that the first solvent is an organic solvent having a boiling point below 100 ℃, preferably the first solvent is selected from ethanol and/or isopropanol.
3. 3. The fuel cell membrane electrode catalytic layer according to claim 1 or 2 wherein the carbon material is selected from one or a combination of two or more of conductive carbon black, carbon fibers, carbon nanotubes and carbon nanowires.
4. 4. The fuel cell membrane electrode catalytic layer according to any one of claims 1 to 3 wherein the second ionomer is selected from one or a combination of two or more of perfluorosulfonic acid resin, highly oxygen permeable fluorinated ionomer and porous ionomer.
5. 5. The fuel cell membrane electrode catalytic layer according to any one of claims 1 to 4, wherein the mass ratio of the second ionomer to the carbon material is 0.2 to 0.8:1; and/or the mass ratio of the second ionomer to the first solvent is 1:300-400.
6. 6. The fuel cell membrane electrode catalytic layer according to any one of claims 1 to 5, wherein the catalyst is a platinum carbon catalyst, and the mass fraction of carbon carriers in the catalyst is 30 to 70%; preferably, the mass ratio of the carbon material in the carbon-ionomer aggregate to the carbon carrier in the catalyst is 0.5-2:1.
7. 7. The fuel cell membrane electrode catalytic layer according to any one of claims 1 to 6 wherein the first ionomer is selected from one or a combination of two or more of perfluorosulfonic acid resin, highly oxygen permeable fluorinated ionomer and porous ionomer; preferably, the mass ratio of the first ionomer to the carbon carrier in the catalyst is 0.2-0.6:1.
8. 8. The method for producing a fuel cell membrane electrode catalytic layer according to any one of claims 1 to 7, comprising: Mixing a second ionomer, a carbon material and a solvent, and then removing the solvent to obtain a carbon-ionomer aggregate; preparing slurry by taking carbon-ionomer aggregate, catalyst and first ionomer as main raw materials; The slurry forms the fuel cell membrane electrode catalytic layer.
9. 9. A fuel cell membrane electrode is characterized by comprising a proton exchange membrane; and a catalytic layer positioned on one side or both sides of the proton exchange membrane; the catalytic layer is selected from the fuel cell membrane electrode catalytic layer according to any one of claims 1 to 7 or the fuel cell membrane electrode catalytic layer produced by the production method according to claim 8.
10. 10. A fuel cell comprising the fuel cell membrane electrode according to claim 9.

Description

Fuel cell membrane electrode catalytic layer, membrane electrode, and preparation method and application thereof Technical Field The invention relates to the technical field of batteries, in particular to a fuel cell membrane electrode catalytic layer, a membrane electrode, a preparation method and application thereof. Background Proton Exchange Membrane Fuel Cells (PEMFCs) are regarded as clean energy technologies with great application prospects in the fields of new energy automobiles, distributed power generation and the like due to the advantages of high energy conversion efficiency, low working temperature, zero emission, quick starting and the like. The Membrane Electrode (MEA) serves as the core component of the PEMFC, and its performance directly determines the power density, cost and durability of the cell. The membrane electrode is typically composed of an anode, a cathode, and a proton exchange membrane sandwiched therebetween, wherein the catalytic layers on the anode and cathode are the core sites where the electrochemical reaction occurs. The working principle of the PEMFC is that fuel (such as hydrogen) is subjected to oxidation reaction in an anode catalytic layer and is decomposed into protons and electrons, the protons reach a cathode reaction site through a proton exchange membrane and a proton conduction network in a cathode catalytic layer, the electrons reach a cathode through an external circuit, and the protons, the electrons and oxidant (such as oxygen) are subjected to reduction reaction in the cathode catalytic layer to generate water. It follows that mass transfer efficiency, proton conductivity, catalyst utilization and intrinsic activity inside the catalytic layer are three key factors affecting and limiting PEMFC performance. In the prior art, conventional methods for preparing catalytic layers generally employ a "one-step mixing process". The method comprises the steps of mixing noble metal catalyst powder such as platinum carbon (Pt/C) and ionomer solution such as Nafion in a solvent system, dispersing the mixture in an ultrasonic mode to form uniform catalyst slurry, coating the slurry on a proton exchange membrane or a gas diffusion layer, and drying the slurry to form a catalytic layer. The method has simple and mature process and is widely applied. However, the catalytic layer prepared by the above method exhibits a "blanket" structure on a microscopic scale, i.e., the surface of the catalyst particles is generally coated with a layer of ionomer. This structure has the following inherent drawbacks, which lead to the creation of technical problems: (1) Proton conducting networks are undesirable and have high proton conducting resistance, as the ionomer relies on its intrinsic dispersion and self-assembly during the slurry drying film forming process, its distribution inside the catalytic layer is random and non-uniform. This allows the build up of proton conducting networks that may be discontinuous and inefficient, thereby increasing the resistance to proton transport from the proton exchange membrane to the catalytically active sites. (2) The mass transfer resistance is large, the reaction rate is limited, and an ionomer thin layer covered on the surface of the catalyst active site forms an additional diffusion barrier for the transmission of reaction gases such as oxygen and the like. The reactant gases need to first dissolve and permeate through the ionomer layer to reach the catalyst surface to participate in the reaction, which significantly increases mass transfer resistance, especially at high current densities where oxygen starvation can be a major bottleneck in performance. (3) The catalyst has low utilization rate and limited intrinsic activity, and the ionomer directly covers and physically shields the active sites of the catalyst, so that a large amount of noble metal particles such as platinum which are supposed to participate in the reaction cannot contact reactants, and the utilization rate of the catalyst is obviously reduced. At the same time, the sulfonate groups in the ionomer also interact with the platinum active sites, creating a "poisoning" effect that limits the adequate expression of the intrinsic activity of the catalyst. In summary, the preparation method of the conventional catalytic layer and the "covered" structure formed by the method in the prior art have the problems of large proton conduction resistance, high mass transfer resistance, low catalyst utilization rate and the like caused by the inherent structural defects of the conventional catalytic layer although the process is simple. These problems together result in a higher charge transfer resistance of the final fabricated membrane electrode, a lower electrochemical active area (ECSA), and ultimately limited overall fuel cell power density improvement. Therefore, how to optimally design the microstructure of the catalytic layer, and to construct a high-efficiency continuous proton co