Formation of 2D Amorphous Lithium Sulfide Enabled by MoC Clusters Loaded Carbon Scaffold for High-Performance Lithium Sulfur Batteries.

Lithium-sulfur (Li-S) batteries, operated through the interconversion between sulfur and solid-state lithium sulfide, are regarded as next-generation energy storage systems. However, the sluggish kinetics of lithium sulfide deposition/dissolution, caused by its insoluble and insulated nature, hampers the practical use of Li-S batteries. Herein, leaf-like carbon scaffold (LCS) with the modification of MoC clusters (MoC@LCS) is reported as host material of sulfur powder. During cycles, the dissociative Mo ions at the MoC@LCS/electrolyte interface are detected to exhibit competitive binding energy with Li ions for lithium sulfide anions, which disrupts the deposition behavior of crystalline lithium sulfide and trends a shift in the configuration of lithium sulfide toward an amorphous structure. Combining the related electrochemical study and first-principle calculation, it is revealed that the formation of amorphous lithium sulfides shows significantly improved kinetics for lithium sulfide deposition and decomposition. As a result, the obtained MoC@LCS/S cathode shows an ultralow capacity decay rate of 0.015% per cycle at a high mass loading of 9.5 mg cm after 700 cycles. More strikingly, an ultrahigh sulfur loading of 61.2 mg cm can also be achieved. This work defines an efficacious strategy to advance the commercialization of MoC@LCS host for Li-S batteries.