Facile synthesis and electrochemical Mg-storage performance of Sb2Se3 nanowires and Bi2Se3 nanosheets
Rechargeable Mg batteries are considered as low-cost and reliable candidates for efficient energy storage, but their development is blocked by lack of suitable cathode materials. In this work, Sb2Se3 nanowires and Bi2Se3 nanosheets are fabricated by facile one-step hydrothermal methods and their Mg-storage performances are systematically investigated. The results show that Bi2Se3 nanosheets with stable hierarchical 2D structure exhibit a better performance. Because of the thin nanosheets structure, Bi2Se3 provides a high Mg-storage capacity of 144 mAh g‒1 and a remarkable rate capability with 65 mAh g‒1 delivered at 1000 mA g‒1. Bi2Se3 also exhibits an outstanding cycleability over 350 cycles owing to the hierarchical structure. Further study reveals that the electrochemical charge/discharge cycling is a typical conversion reaction occurring between Bi3+ and metallic Bi0. Kinetic investigation suggests the high performance is attributed to both of the intrinsic nature of Bi2Se3 and thin nanosheet structure facilitating solid-state Mg2+ diffusion. The present work highlights the selection principal of conversion cathodes for rechargeable Mg batteries, namely matching a soft anion with quasi-soft metal cation. Moreover, facile synthesis approach is also delivered for low-dimensional main-group VI metal chalcogenides to improve the Mg-storage performance.