Double-catalyst-layer structure electrode, preparation method and application of double-catalyst-layer structure electrode in high-temperature membrane fuel cell

Abstract

The invention belongs to the technical field of fuel cells and relates to a double-catalyst-layer structure electrode. The electrode comprises an electrode substrate layer and a dual-catalyst layer attached to the electrode substrate layer. The dual-catalyst layer is formed by mixing a Pt / C catalyst, a binder and a dispersing agent. The dual-catalyst layer sequentially comprises a low-platinum-content catalyst layer and a high-platinum-content catalyst layer from bottom to top, and the electrode substrate layer is formed by uniformly loading slurry formed by carbon powder, the binder and the dispersing agent on a gas diffusion substrate. The invention further relates to a preparation method of the double-catalyst-layer structure electrode, and application of the double-catalyst-layer structure electrode to a high-temperature membrane fuel cell. Compared with the prior art, the double catalytic layers are prepared by combining the gradient distribution of reactants in the catalytic layers, and are activated to form the gradient catalytic layers, so that a gradient distribution reaction interface is provided while good contact between the catalytic layers and the electrode substratelayer and between the catalytic layers and the high-temperature film is maintained, the electrochemical active area is increased, and the catalyst utilization rate is increased. The catalyst accountsfor more than half of the cost of the high-temperature membrane fuel cell, so that the preparation cost of the cell is reduced by providing the double-catalyst-layer structure electrode.

Description

technical field [0001] The invention belongs to the technical field of fuel cells, and relates to electrode materials, in particular to a double-catalyzed layer structure electrode and a preparation method thereof, and also relates to its application in high-temperature membrane fuel cells. Background technique [0002] Fuel cells have attracted extensive attention due to their advantages of cleanliness, high efficiency, and environmental friendliness. The operating temperature of traditional low-temperature batteries is mostly 60-80°C. At this time, the batteries usually need external humidification, and the liquid water produced by the cathode oxygen reduction is difficult to drain out of the battery, resulting in difficulties in water and heat management. In addition, the perfluorosulfonic acid (Nafion) membrane used to conduct protons in its membrane electrode is expensive, which greatly increases the cost of the fuel cell. When the fuel cell operates at a high temperat...

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Problems solved by technology

Therefore, the conventional single-layer cathode catalytic layer tends to cause excessive supply of catalyst in the inner layer (closer to the electrode base layer), insufficient supply of catalyst in the outer layer (closer to the high-temperature membrane side), and low catalyst utilization.

[0004] Chinese patent 201210563370.7 discloses a method for preparing a cathode catalyst layer for high-temperature fuel cells. In this method, phosphoric acid and silicone oil are added to the catalyst slurry to avoid performance degradation caused by poor oxygen mass transfer, but the addition of silicone oil will make the reaction The required three-phase interface is reduced, and the electrochemically active area of ​​the catalyst is reduced

[0005] Chinese patent 201510509980.2 discloses a method for preparing a high-temperature proton exchange membrane fuel cell membrane electrode. The catalytic layer of this method is composed of graphene airgel, polytetrafluoroethylene (PTFE) and catalyst, which improves the life of the proton exchange membrane. Thereby improving the output power of the fuel cell, it does not solve the problem of low catalyst utilization

[0006] Chinese patent 201510939965.1 discloses a preparation method of a high-temperature fuel cell membrane electrode that combines electrospinning technology and introduces a network layer of high-temperature-resistant polymer nanofibers into the diffusion layer and the catalytic layer. The interaction of electrolytes builds a continuous ion transport channel and slows down the loss of liquid electrolyte, thereby improving battery performance. However, in high temperature operation above 150°C, the material exchange in the battery is carried out in the form of gas, and the loss of liquid electrolyte is very small. , so this move increases the transmission path of the gas, and the final catalyst utilization rate is lower

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