The effect of pulverization methods on microstructure of carbon aerogels for metal-sulfur batteries

Abstract

Carbon aerogels are well known open porous solid materials first introduced by Richard Pekala in 1989 [1]. Usually carbon aerogels are derived by pyrolysis of organic precursors such as resorcinol-formaldehyde or melamine-formaldehyde [2]. Due to their high inner surface area of about 2000 to 2500 m²/g, high pore volume of about 3 to 5 cm³/g [3] carbon aerogels have a broad field of applications, such as cathode materials for metal-sulfur batteries. For this application they are used as powder and thus need to be pulverized. However, the pulverization could induce various changes in the microstructure of carbon aerogels. The extent of the changes depends both on the dominant forces of the technique used and on the mechanical and structural properties of the initial monolithic samples. In present work we show the influence of grinding, milling in shaker cryo mill and planetary ball mill on stiff, ductile and flexible carbon aerogels. SEM and TEM images, gas sorption techniques show a strong dependency of introduced energy amount while pulverization on structure modification. Results show that stiff carbon aerogels do not undergo noticeable changes. In contrast, ductile carbon aerogels are very sensitive to friction forces. Soft and flexible carbon aerogels undergo drastically changes in the microstructure. Due to the microstructure carbon aerogels are highly promising materials to be used as a well-defined porous matrix for sulfur to fabricate cathodes of metal-sulfur batteries. Herein the deforming during pulverization of the adjusted porous structure has to be taken into account. Within the presentation the whole production process of carbon aerogel powders from chemical synthesis via carbonization and grinding will be illuminated.