Controlled synthesis of three-dimensional porous carbon aerogel via catalysts: effects of morphologies toward the performance of lithium-sulfur batteries
ABSTRACT Because of its high specific surface area and high conductivity, carbon aerogel has become one of an ideal sulfur hosts for lithium-sulfur (Li-S) batteries. However, the microstructure of carbon aerogel perplexed by many factors, such as solvents, catalysts. In this work, carbon aerogel (CA) is respectively fabricated through phenol-formaldehyde reaction under two different catalysts of hexamethylenetetramine and sodium hydroxide, and carbonized under high temperature, and loaded with sulfur via diffusion-melting. The physical properties of resulting CA via hexamethylenetetramine catalyst (CAHE) and the electrochemical performances of the obtaining CAHE/S (sulfur) are more outstanding than that of carbon aerogel via sodium hydroxide catalyst (CASH) by scanning electron microscopy, Brunauer-Emmett-Teller characterization, and galvanostatic discharge/charge test and electrochemical impedance spectroscopy. With a comparison of common CASH, and sulfur loaded in CASH (CASH/S), CAHE/S electrode exhibits a relatively high initial discharge specific capacity of 1085.6 mAh g−1, increasing 11% in capacity retention rate at 0.1 C after 100 cycles. After 50 cycles, the capacity attenuation rate is 0.08% per cycle, which displays the excellent performance of the CAHE/S electrode. It is found that the improved performance of CAHE/S is attributed to finer particles and larger specific surface area of CAHE which rapidly improves lithium ion diffusion. This work not only modifies the structure of carbon aerogelbut also provides an important reference value for the potential application of the carbon aerogel in Li-S batteries.