A Mo₅N₆ electrocatalyst for efficient Na₂S electrodeposition in room-temperature sodium-sulfur batteries.

ABSTRACT: Metal sulfides electrodeposition in sulfur cathodes mitigates the shuttle effect of polysulfides to achieve high Coulombic efficiency in secondary metal-sulfur batteries. However, fundamental understanding of metal sulfides electrodeposition and kinetics mechanism remains limited. Here using room-temperature sodium-sulfur cells as a model system, we report a Mo₅N₆ cathode material that enables efficient Na₂S electrodeposition to achieve an initial discharge capacity of 512 mAh g^-1 at a specific current of 1 675 mA g^-1, and a final discharge capacity of 186 mAh g^-1 after 10,000 cycles. Combined analyses from synchrotron-based spectroscopic characterizations, electrochemical kinetics measurements and density functional theory computations confirm that the high d-band position results in a low Na₂S₂ dissociation free energy for Mo₅N₆. This promotes Na₂S electrodeposition, and thereby favours long-term cell cycling performance.

SUBMITTER: Ye C 

PROVIDER: S-EPMC8664834 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature