Antimony-mediated few-layer metallic MoSe2 with rich selenium vacancies for ultrafast sodium/potassium storage

A novel crystal phase modulation strategy to regulate the electronic structure is presented, whereby doping cation (Sb) into the 2H-MoSe2 lattice to transform it into 1T-phase, which greatly enhances the SIBs/PIBs performances. [Display omitted] •Antimony doping successfully transforms MoSe2 from 2H phase to 1 T phase.•Few-layer 1 T-MoSe2 is confined in N, P-doped bio-carbon with a robust structure.•T-MoSe2/C-1 greatly enhances the conductivity, reduces the diffusion barrier of Na+/K+.•T-MoSe2/C-1 achieves high rate and stable capacity for SIBs/PIBs. Transition metal dichalcogenides with sandwich structure possess high theoretical capacity, while face the challenge of inferior inherent electronic conductivity and dramatic volume fluctuation during cycling, lessening their fascination for electrochemical energy storage material applications. Herein, we report a crystal phase modulation strategy to modulate the electronic structure by doping cation (Sb) into the few-layer 2H-phase MoSe2 lattice, thereby implants abundant selenium vacancies and expands the layer spacing, which transforms it into a 1T-phase (T-MoSe2/C-1). The few-layer 1T-MoSe2 nanosheets are confined within chlorella-derived N, P-doped bio-carbon, endowing T-MoSe2/C-1 with a rock-solid structure, rapid Na+/K+ transport kinetics, and high reversibility. Density functional theory calculations confirm that the antimony atoms in T-MoSe2/C-1 system significantly increase the electronic conductivity, decrease the Na+/K+ diffusion barrier and reinforce the adsorbed capability for Na+/K+. Consequently, the T-MoSe2/C-1 achieves a reversible capacity of 540 mAh/g at 0.5 A/g and delivers as high as 333 mAh/g even at a high rate of 25 A/g for SIBs. As the anode of PIBs, it maintains a stable capacity of 210 mAh/g after 1,000 cycles at 5 A/g. This study provides a new horizon on the phase regulation of transition metal dichalcogenides (TMDs) to improve sodium/potassium-ions storage.