Aerogel based cathode material for lithium-sulfur battery

Abstract

The exploitation of renewable energy resources and energy storage became an important issue in the last decades. The lithium-sulfur batteries are very attractive due to their very high theoretical specific capacity of 1675 mAh/g and very high specific energy density of 2500 Wh/kg. In addition to these values, sulfur is abundant on earth and inexpensive. With these benefits lithium-sulfur batteries are considered to be the next generation power source in advanced technologies. However, the poor cycle stability caused by polysulfide shuttle and side reactions reduces the active mass quantity resulting in decrease of capacity. Furthermore the volume expansion on the cathode side of about 80 % leads to crack formation and is referred to decrease of capacity. Carbon aerogels are promising materials to be used as cathode matrix for lithium-sulfur batteries. They are carbonized from organic resorcinol-formaldehyde aerogels and exhibit as a highly porous structure with porosities up to 98 %, high surface areas of around 500-3500 m²/ and large total pore volumes of around 2-3 cm³/g. In the presentation the influence of the pore structure and the pore volume distribution on the efficiency of such Li-S-battery systems will be discussed. In addition effects of pulverizing methods, such as ball mill and grinding, on the microstructure of the carbon aerogels will be addressed. The differences between carbon aerogels with different mechanical strength - from very hard to flexible - will be compared and analyzed for batteries application. The effects on the electrochemical properties of the built cells caused by the developed carbon aerogels will be presented.