Tuning the porous structure of carbon hosts for loading sulfur toward long lifespan cathode materials for Li–S batteries

Abstract

As a crucial component, carbon substrates with appropriate porous structures are highly desired in developing sulfur–carbon cathodes for Li–S batteries with superior performance. Here we show that the electrochemical performance of the sulfur–carbon cathode can be easily adjusted by tuning the pore structure of the carbon substrate. With potassium hydroxide as the activation agent, a series of micro-/mesoporous carbon hosts have been prepared via chemical activation of hydrothermal carbon precursors. The pore structure of the carbon host can be easily controlled by adjusting the activation concentration of KOH, and is found to be directly related to the battery performance of sulfur loaded inside. An optimized pore structure is yielded at a KOH concentration of 1 M, at which the sulfur–carbon cathode shows a high specific capacity, favourable rate capabilities and a long cycle life of 800 cycles at 1 C. The impressive electrochemical performances benefit from the advanced micro-/mesoporous carbon spheres with a large percentage of micropores, moderate activation and surface area.