Technological Aspects of Hydrogen Fuel Cell Electrodes with Controlled Porosity and Transport Properties

Despite such technical advantages as high energy conversion efficiency, low noise, autonomy, etc., hydrogen fuel cells have not yet been widely used due to insufficiently high economic competitiveness. It is known that a significant fraction of the hydrogen fuel cell cost is the cost of the electrode materials and electrodes. In this regard, the paper studies the electrode materials and electrodes of hydrogen fuel cell. The performance of porous electrochemical electrodes is determined by electrode activity, substance transfer efficiency, and charge transfer efficiency. Since these factors act, as a rule, in the opposite direction, the task of selecting the component composition of the electrode often comes down to obtaining optimization dependencies. It is important to note that transport losses in a running fuel cell are usually dominant. In connection with this, our work focuses on the structure and transport characteristics.

It is believed that the determining factors of the diffusion component of the functioning of the fuel cell are the characteristics of the porous structure of the electrode affecting the conditions of mass exchange and the processes of water condensation. A significant phenomenon is the inhomogeneity of the ionic resistance associated with inhomogeneities of humidity and temperature, since the ionic resistance of proton-conducting component depends on humidity and temperature.

In order to control the porous structure and transport properties, we used the technique of introducing into the electrode material a highly porous functional additive with a large proportion of transport pores and creating the island structure of the proton-conducting polymer Nafion. Two materials were investigated as functional additives: carbon nanofibers and thermally expanded graphite. The fabricated electrode materials and membrane-electrode assemblies were investigated by electron microscopy, voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy.

The result is the dependences connecting the composition of the electrode with its porosity, specific ion and electronic resistance, specific surface area of platinum. The study gives the results of diffusion resistance to mass transport depending on the composition. We have developed the technology of electrode material with increased efficiency of mass and charge transport. The results allow us to predict the electrical characteristics of the cathode, to produce electrodes with desired properties.

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