Carbon aerogels - promising materials for fuel cell applications

Kurzfassung

Carbon aerogels, first introduced by Richard Pekala in 1989, are three-dimensional, open porous solid materials produced via carbonization of organic aerogels based on e.g. resorcinol-formaldehyde, phenol-formaldehyde or melamine-formaldehyde polymers. The synthesis parameters of organic aerogels such as pH-value, the amount of catalyst, the molar ratios of educts, temperature influence the formation of the microstructure of aerogels significantly. The microstructure, in turn, is reflected in properties of aerogels. An increase in pH during stirring leads to the formation of small particles. Differences in the molar ratios of the reactants affect the connectivity between the particles and have a corresponding direct effect on the electrical properties of the aerogel. The final structure of carbon aerogel depends very critically on carbonization process, e.g. temperature, duration, gases. Unique properties of carbon aerogels such as well-controlled porosity and pore size, large specific surface area about 500-2000 m²/g, high electrical conductivity, and low envelope density make them promising material for application in adsorption, catalysis, supercapacitors, fuel cells or as a cathode host in metal-sulfur cells. Their remarkable electrical conductivity is one of the key factors for electrochemical applications. The open-pore network with adjustable microstructure offers a high level of freedom in material design to specifically adapt the carbon matrix to the requirements of the electrode. Within the presentation we will report on the properties of carbon aerogel materials and dependences of the synthesis and carbonization routines.