Disordered mesoporous carbon as polysulfide reservoir for improved cyclic performance of lithium–sulfur batteries

Abstract

Mesoporous carbon, which was templated by colloidal silica, was added to a sulfur cathode as a functional material to confine polysulfides to improve the cyclic performance of lithium–sulfur batteries. To investigate the effect of the pore size and the pore volume of mesoporous carbon on the absorption characteristics of the Li-polysulfides, mesoporous carbons with various pore sizes and total pore volumes were prepared by varying the size and the amount of colloidal silica templates. The results show that mesoporous carbon-containing sulfur cathode enhanced the cyclic performance of the batteries significantly. Comparable performances were observed regardless of pore size, suggesting that the pore size is not a critical factor affecting the absorption characteristics of the Li-polysulfides. However, the cyclic performance was affected by the total pore volume, suggesting that a certain pore volume is necessary to confine the majority of the soluble Li-polysulfides generated during cycling and to enhance sulfur utilization. The novel results obtained in this study will contribute to the consolidation of S electrochemistry and further development of high-energy lithium–sulfur batteries.