Hierarchically porous sulfur-containing activated carbon monoliths via ice-templating and one-step pyrolysis

Abstract

Hierarchically porous sulfur-containing activated carbons were prepared by ice-templating from an aqueous sodium poly(4-styrenesulfonate) (Na-PSS) solution followed by a single 800 °C pyrolysis step. This thermal treatment induced crosslinking, with the in-situ generation of Na2SO4 (activating agent), before carbonization and activation. The thermal treatment also resulted in the formation of sulfur salts, which could be converted to elemental sulfur upon a simple HCl acid wash. The sulfur content in the monoliths measured by microanalysis could be increased from 17.07 wt. % to 39.74 wt. % by incorporating additional Na2SO4 into the monoliths prior to pyrolysis. The sulfur was uniformly dispersed within the micropores of the carbon, and could be selectively removed by degassing (heating under vacuum) at different temperatures, revealing specific surface areas of up to 1051 m2 g−1. The materials were characterized by various techniques and were also evaluated for their potential as cathode materials for the lithium–sulfur battery. This work may open up new and facile routes to prepare sulfur-containing porous carbons for applications where its presence is beneficial.