Investigation and Design of High-Loading Sulfur Cathodes with a High-Performance Polysulfide Adsorbent for Electrochemically Stable Lithium-Sulfur Batteries

Sulfur cathodes are inexpensive and exhibit a high theoretical charge-storage capacity of 1672 mA・h g−1. Consequently, electrochemical lithium−sulfur batteries can attain a high gravimetric energy density of 400−600 W・h kg−1. Practical high-performance sulfur cathodes depend on the efficient electrochemical utilization of active solid-state materials and high electrochemical stability of active liquid-state materials in cells with high amounts of sulfur. In this study, we systematically investigate a series of oxide-based polysulfide adsorbents that exhibit chemical polysulfide-trapping and electrocatalytic conversion capabilities. After ruling out the possibility of the physical adsorption of polysulfides, various types of oxides are used to develop a cathode with high sulfur loading values of 3.0 and 4.0 mg cm−2 and a sufficient sulfur content of 60 wt %. The analytical results indicate that the presence of SiO2 promotes the adsorption and conversion of a high amount of polysulfides. The prepared high-loading sulfur cathodes optimized through the use of a SiO2 adsorbent exhibit a high charge-storage capacity (895 mA・h g−1), a long cycle life (200 cycles), a high rate performance (C/20−C/2), and a high sulfur loading capability (8.0 mg cm−2) while maintaining a high areal capacity (3.7 mA・h cm−2) and a high energy density (7.9 mW・h cm−2).