Hierarchical MoSe2 yolk–shell microspheres with superior Na-ion storage properties

Abstract

Yolk–shell-structured MoSe₂ microspheres were prepared via a simple selenization process of MoO₃ microspheres. The yolk–shell-structured MoSe₂ and MoO₃ microspheres delivered initial discharge capacities of 527 and 465 mA h g⁻¹ in the voltage range of 0.001–3 V vs. Na/Na⁺ at a current density of 0.2 A g⁻¹, respectively, and their discharge capacities after 50 cycles were 433 and 141 mA h g⁻¹, respectively. The yolk–shell-structured MoSe₂ microspheres also exhibited outstanding high rate capabilities. The hierarchical yolk–shell structure comprised of wrinkled nanosheets facilitated fast Na-ion and electron kinetics, and buffered the large volume changes encountered during cycling.