High sulfur loaded carbon aerogel cathode for lithium–sulfur batteries

Abstract

An attempt made to improve sulfur loading in a template-free porous carbon to the extent of 70 wt% has led to two interesting observations being inferred, viz., 60 wt% sulfur loading exhibits superior electrochemical properties in the S@C composite form and an enhanced 73 wt% sulfur loading leads to the formation-cum-stabilisation of sulfur in its monoclinic phase. Carbon aerogel with tunable properties, derived from the catalyst-aided cross linking of resorcinol and formaldehyde, possessing a specific surface area of 1395 m² g⁻¹ and pore volume of 1.423 cm³ g⁻¹ has been exploited for sulfur loading to form a series of S@C composites. Interestingly, carbon aerogel prepared in the present study offers multifarious advantages such as conducting additive, potential host to accommodate higher concentrations of sulfur and better polysulfide confining matrix. The 60 wt% sulfur loaded carbon aerogel composite exhibits an appreciable specific capacity of 600 mA h g⁻¹ at a C/10 rate up to 100 cycles, 480 mA h g⁻¹ at a 1C and 422 mA h g⁻¹ at a 2C rate. Hence, the capability of carbon aerogel, synthesized through the present study in accommodating higher concentrations of sulfur, effective management of polysulfide shuttle, and provision of favorable electrode–electrolyte interface to facilitate extended cycling possibilities at different current densities has been demonstrated.