Cellulose substance derived nanofibrous activated carbon as a sulfur host for lithium-sulfur batteries

Abstract

A nanofibrous activated carbon with high surface area was fabricated via the alkali activation process by using the natural cellulose substance (i.e. common laboratory filter paper) as both the structural support and carbon source. The obtained nanofibrous activated carbon was used as a host to further impregnated with sulfur to form the activated-carbon/sulfur composites for lithium-sulfur (Li-S) batteries. The activated-carbon/sulfur composite with a sulfur content of 49.4 wt% exhibited an initial discharge capacity of 1393 mA h g−1 and stabilized at 576 mA h g−1 at a current rate of 0.1 C after 100 cycles. And a good rate capability with a reversible capacity of 789 mA h g−1 was obtained at 0.1 C after 100 charge/discharge cycles. The improvements of the cycling stability and rate capability of the activated-carbon/sulfur composites are attributed to the unique three-dimensional conductive network structures and the high surface area of the nanofibrous activated carbon scaffolds, which not only effectively restrain the dissolution and diffusion of the polysulfide during the discharge process, as well as accommodate the large volume expansion in the formation process of S to Li2S in the lithium-sulfur batteries.