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

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.