High-entropy metal diselenides propels polyselenides immobilization for high performance sodium storage

Abstract

Metal diselenides-based anode materials for sodium ion batteries have attracted great attention owing to their high theoretical capacity and excellent conductivity. However, some critical issues such as notorious soluble polyselenides shuttle and volumetric expansion extremely limit their application in SIBs. Herein, the high-entropy strategy is applied to this material through embedding Mn, Co, Ni, Fe and Cu elements into the same position in the octahedron structure. Consequently, the as-prepared high-entropy metal diselenides (HE-MSe2) electrode with multiple transition metals can exhibit an enhanced chemical affinity to soluble polyselenides and its specific structure can restrain volumetric expansion. Besides, Cu2Se was produced by an in-situ immobilization reaction between the caught sodium polyselenides and Cu current collector, and the obtained Cu2Se can not only mitigate the shuttle effect, but also contribute to the specific capacity. Moreover, theoretical simulations reveal that the HE-MSe2 shows increased binding energy with sodium ions and fast reaction kinetics, in which multiple transition metal facilitates the anchoring of polyselenides. Benefiting from these advantages, the HE-MSe2 anode presents a high reversible capacity of 440 mAh g−1 at 0.1 A g−1 and 373 mAh g−1 at 1 A g−1 as well as excellent rate performance. This work provides a new avenue to solve the intrinsic problems for designing high-performance anode of SIBs.