Microporous novolac-derived carbon beads/sulfur hybrid cathode for lithium-sulfur batteries

Novolac-derived nanoporous carbon beads were used as conductive matrix for lithium-sulfur battery cathodes. We employed a facile self-emulsifying synthesis to obtain sub-micrometer novolac-derived carbon beads with nanopores. After pyrolysis, the carbon beads showed already a specific surface area of 640 m(2) g(-1) which was increased to 2080 m(2) g(-1) after physical activation. The non-activated and the activated carbon beads represent nanoporous carbon with a medium and a high surface area, respectively. This allows us to assess the influence of the porosity on the electrochemical performance of lithium-sulfur battery cathodes. The carbon/sulfur hybrids were obtained from two different approaches of sulfur infiltration: melt-infusion of sulfur (annealing) and in situ formation of sulfur from sodium thiosulfate. The best performance (similar to 880 mAh g(sulfur)(-1) at low charge rate; 5th cycle) and high performance stability (> 600 mAh g(sulfur) (-1) after 100 cycles) were found for the activated carbon beads when using melt infusion of sulfur. (C) 2017 Elsevier B.V. All rights reserved.