Size Tunable Zeolite-Templated Carbon as Microporous Sulfur Host for Lithium-Sulfur Batteries

Spatial confinement of sulfur in porous carbons has been one of the major approaches to address the polysulfide (PS) shuttle problem of lithium-sulfur (Li-S) batteries. Among them, microporous carbon can effectively confine sulfur inside pores, however, it shows low active material utilization due to pore blockage by discharge products. To address this issue, in this work, zeolite-templated carbons (ZTCs) with high surface area and electronic conductivity are used as host material for Li-S battery and their particle size is varied to explore better performances. With decrease of the particle size from 400 to 20 nm, initial sulfur utilization is enhanced from 20.7 to 71.6 %. The smaller ZTC particle delivers a high capacity retention of 94.6 % at 200 cycles. From electrochemical and spectroscopic analyses, it is demonstrated that smaller ZTC particles lead to easier penetration of Li ions inside the pores, resulting in more uniform Li2S deposition on the entire surface of the micropores. Due to its excellent size-tunability and well-defined pore structure, ZTC can be an effective sulfur host for the design of high-performance Li-S batteries.