Composition and Architecture Design of Double-Shelled Co0.85 Se1- x Sx @Carbon/Graphene Hollow Polyhedron with Superior Alkali (Li, Na, K)-Ion Storage.

The exploration of materials with reversible and stable electrochemical performance is crucial in energy storage, which can (de) intercalate all the alkali-metal ions (Li+ , Na+ , and K+ ). Although transition-metal chalcogenides are investigated continually, the design and controllable preparation of hierarchical nanostructure and subtle composite withstable properties are still great challenges. Herein, component-optimal Co0.85 Se1- x Sx nanoparticles are fabricated by in situ sulfidization of metal organic framework, which are wrapped by the S-doped graphene, constructing a hollow polyhedron framework with double carbon shells (CoSSe@C/G). Benefiting from the synergistic effect of composition regulation and architecture design by S-substitution, the electrochemical kinetic is enhanced by the boosted electrochemistry-active sites, and the volume variation is mitigated by the designed structure, resulting in the advanced alkali-ion storage performance. Thus, it delivers an outstanding reversible capacity of 636.2 mAh g-1 at 2 A g-1 after 1400 cycles for Li-ion batteries. Remarkably, satisfactory initial charge capacities of 548.1 and 532.9 mAh g-1 at 0.1 A g-1 can be obtained for Na-ion and K-ion batteries, respectively. The prominent performance combined with the theory calculation confirms that the synergistic strategy can improve the alkali-ion transportation and structure stability, providing an instructive guide for designing high-performance anode materials for universal alkali-ion storage.