Low cost bio-derived carbon-sprinkled manganese dioxide as an efficient sulfur host for lithium–sulfur batteries

Abstract

Realization of the lithium-sulfur battery system is of major concern because a theoretical cell capacity of 1675 mA h g⁻¹ can be obtained at an average voltage of 2.1 V. The primary issues that hinder the practical applications of this system include its poor utilization of sulfur, limited cycle life and retarded rate performance. In the present study, hemp-derived carbon (C-hemp) is made into a composite with room temperature-synthesized MnO₂, which acts as a host for sulfur in the lithium-sulfur battery system. The composite material is characterized physico-chemically and electrochemically using various techniques. This composite exhibits better electrochemical performance as a sulfur carrier compared to pristine carbon. An initial specific capacity of 926 mA h g⁻¹ is obtained at 0.1 C for C-hemp/MnO₂-sulfur, which surpasses that of the C-hemp-sulfur sample. C-hemp provides a conductive matrix as well as porous sites for the accommodation of sulfur, while MnO₂ exhibits the ability to absorb polysulfide chemically. Thus, this composite is established as a potential cathode for lithium-sulfur batteries.