Boosting the sodium-ion storage capability of MoSe2 through the synergistic effect of rational sulfur substituting and carbon compositing

Abstract

Molybdenum selenide (MoSe2) has been regarded as a promising anode for sodium-ion storage due to its large interlayer space, acceptable electronic conductivity, and considerable theoretical capacity, but suffers insufficient active sites and serious volume variation, leading to low reversible capacity and poor cycling lifespans. Herein, a facile one-pot hydrothermal method is developed to achieve sulfur substituting and carbon compositing simultaneously and employed to boost the sodium ion storage properties of MoSe2. The effects of sulfur substituting and carbon compositing on the redox kinetics and sodium-ion storage performance are investigated. In short, sulfur substitution mainly enhances the electronic/ionic conductivity and specific capacity of the MoSe2 by tailoring the electron structures and creating anionic vacancies. Carbon compositing mainly improves the cycling stability due to the alleviative aggregation of active materials and the prohibited active materials dissolution. As a result, the optimized MoSe2-xSx@C electrode presents 348.6 mAh g−1 at 0.1 A g−1, and can endure long-term cycling at 4 A g−1 after 600 cycles with acceptable capacity retention of 83.9%, much better than the pure MoSe2 electrode and the MoSe2-xSx electrodes. This work may provide a facile method to enhance the sodium ion storage properties of transition metal dichalcogenides.