MoS Chalcogel: A High-Capacity Electrode for Conversion-Based Li-Ion Batteries.

Despite large theoretical energy densities, metal-sulfide electrodes for energy storage systems face several limitations that impact the practical realization. Here, we present the solution-processable, room temperature (RT) synthesis, local structures, and application of a sulfur-rich MoS chalcogel as a conversion-based electrode for lithium-sulfide batteries (LiSBs). The structure of the amorphous MoS chalcogel is derived through operando Raman spectroscopy, synchrotron X-ray pair distribution function (PDF), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) analysis, along with ab initio molecular dynamics (AIMD) simulations. A key feature of the three-dimensional (3D) network is the connection of MoS units through S-S bonds. Li/MoS half-cells deliver initial capacity of 1013 mAh g during the first discharge. After the activation cycles, the capacity stabilizes and maintains 312 mAh g at a C/3 rate after 140 cycles, demonstrating sustained performance over subsequent cycling. Such high-capacity and stability are attributed to the high density of (poly)sulfide bonds and the stable Mo-S coordination in MoS chalcogel. These findings showcase the potential of MoS chalcogels as metal-sulfide electrode materials for LiSBs.