Hierarchical structural modulation and Co-Construction of selenium vacancy in ZnSe/NiSe2 heterojunctions to enhance cycling stability and fast ion diffusion kinetics for lithium-ion and sodium-ion batteries

Transition metal selenides are perceived as promising anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) due to their high theoretical specific capacity and structural diversity. Nonetheless, the poor structural stability and sluggish kinetics of metal selenides lead to unsatisfactory electrochemical performance. Herein, we have designed and synthesized ZnSe/NiSe2 bimetallic selenides hollow hierarchical structure with rich selenium vacancies and homogeneous carbon layer (V-ZnSe/NiSe2@H-NC) as anode materials for both LIBs and SIBs. The unique hollow hierarchical morphology and carbon layer provide a large buffer area, leading to enhanced micro-structure stability during cycling. Furthermore, the ZnSe/NiSe2 heterostructure not only offers the pseudocapacitance behavior but also gives rise to a large number of selenium vacancies, which will significantly improve the ion diffusion kinetics. The V-ZnSe/NiSe2@H-NC electrodes exhibit high reversible capacity and remarkable cycling stability in both LIBs and SIBs. The underlying electrochemical ion storage mechanisms are illustrated in detail by electrochemical kinetic analysis, ex-situ Raman, and density functional theory. This work provides a new angle to understand the mechanisms of enhancing performances in bimetallic selenides.