Abstract
Lithium-sulfur (Li-S) batteries hold promise to be the next-generation Li energy-storage systems due to the high theoretical energy density (2600 W h ), and the abundance and environmental friendless of sulfur. Nevertheless, challenges arising from the fundamental Li-S chemistry hamper the practical viability of Li-S batteries. Specifically, the dissolution of Li polysulfides and their slow conversion kinetics collectively cause irreversible loss of the active material and short cycle life. Efforts have been intensively dedicated in physical confinement or chemical trapping of Li polysulfides, yet such passive blocking strategy is unable to fundamentally and sufficiently suppress the accumulation of sulfide products in the electrolyte, especially for high sulfur loading and long cycling. Here, we report a Li cation-doped tungsten oxide electrocatalyst that allows accelerated conversion kinetics to counteract the polysulfide dissolution and migration. In addition, the significant lithium sulfide (Li2S) oxidation barrier necessitates activation with a high overpotential, which results in low sulfur utilization and fast capacity decay. Accordingly, we also report a heterostructured WOx/W2C nanocatalyst synthesized via ultrafast Joule heating, and the resulting heterointerfaces contribute to enhance electrocatalytic activity for Li2S oxidation, as well as controlled Li2S deposition. We studied the fundamental relationships between the improved electrocatalytic activity and the optimized structures of the electrocatalysts, demonstrated the electrocatalytic effect on battery performance and highlighted the future design of catalytic materials for the advancement of practical Li-S batteries.
Published Version
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