Hollow Core-Shell Metal-Organic Framework-Derived Porous Carbon Hybrid for Electrochemical Na⁺ Storage

Constructing a core-shell hybrid is usually deemed to take advantage of single metal-organic framework-derived porous carbon for more deficient Na+ storage, but the involvement of a shell layer would basically bring worries about limited ion diffusion kinetics and inefficient utilization of active materials. To deal with this issue, herein we design a porous carbon derived from a hollow core-shell MOF hybrid with a relatively thin shell, which unites the merits of both hollow structure and core-shell structure. According to the experimental results and density functional theory analysis, such a unique hollow core-shell architecture can accommodate additional Na+ adsorption sites, favorable electrochemical kinetics, and improved mechanical strength. The optimized h-MOF-74@ZIF-8-I-C exhibits a high specific capacity of 247.6 mA h g(-1) at 0.1 A g(-1) and excellent rate performance and cycling durability toward Na+ storage. As a result, the prepared hollow core-shell porous carbon hybrid shows a much better electrochemical Na+ storage performance than other single MOF-derived and solid core-shell counterparts. The present work would offer significant reference for optimizing Na+ storage performances of electrode materials by micro/nanostructure engineering.