Onion Peel Based Porous Carbons as Cathode Components for LiS Battery

Abstract

In recent years, lithium-sulfur (LiS) battery has emerged as promising energy storage systems to replace the conventional lithium ion battery. This battery system uses elemental sulfur as cathodes and Li metal as anodes and possess a higher specific capacity (1,675 mAh/g) compared to that of lithium ion battery. However, some technical problems such as the low conductivity of sulfur, huge volume expansion during cycling and the shuttle effect of polysulfide have prevented this kind of battery system to be commercialized. One method to solve those problems is by using carbon materials as cathode component together with sulfur to form Carbon-sulfur composite cathodes. Carbon materials could improve the electrochemical performance of LiS battery due to the electrical conductivity and highly porous structure. Biomass derived conductive carbon materials have attracted increasing attention on account of their abundance, sustainability, and easy accessibility. Here, onion peel waste has been utilized to synthesize amorphous porous carbon (OPWC) as cathode component for LiS battery. Porous carbons were prepared by using hydrothermal carbonization followed by the chemical activation process using KOH. The carbon-sulfur composites were then obtained after sulfur loading using the melt diffusion method. As obtained OPWC/S composite demonstrates stable cycle performance and a reversible specific capacity of 630 mAh/g after 100 cycles at current density of 0.1 C when used for LiS battery. These improved electrochemical performances may be attributed to the structure of OPWC showing mesoporous structure with defect carbon structure and high specific surface areas. These results show the potential and promising application of onion peel waste based porous carbon in LiS battery.