Wide-Temperature-Range Li-S Batteries Enabled by Thiodimolybdate [Mo2S12]2- as a Dual-Function Molecular Catalyst for Polysulfide Redox and Lithium Intercalation

In lithium-sulfur batteries, a serious obstacle is the dissolution and diffusion of long-chain polysulfides, resulting in rapid capacity decay and low Coulombic efficiency. At present, a common practice is designing cathode materials to solve this problem, but this gives rise to reduced gravimetric and volumetric energy densities. Herein, we present a thiodimolybdate [Mo2S12](2-) cluster as sulfur host material that can effectively confine the shuttling of polysulfides and contribute its own capacity in Li-S cells. Moreover, the [Mo2S12]2- cluster as a bidirectional catalyst can effectively catalyze polysulfide reduction and lithium sulfide oxidation. We further investigate the catalytic mechanism of [Mo2S12](2-) clusters by theoretical calculations, in situ spectroscopic techniques, and electrochemical studies. The (NH4)(2)Mo2S12/S cathodes show good electrochemical performance under a wide range of temperatures. In addition, a pouch cell fabricated with (NH4)(2)Mo2S12/S cathodes maintains a stable output for more than 50 cycles.

Automated summary

In this study, a sulfur host material thiodimolybdate [Mo2S12](2-) cluster is introduced, which effectively confines the diffusion of polysulfides in lithium-sulfur batteries and exhibits good electrochemical performance.