Metal-Organic Frameworks Derived Okra-like SnO2 Encapsulated in Nitrogen-Doped Graphene for Lithium Ion Battery.

A facile process is developed to prepare SnO2-based composites through using metal-organic frameworks (MOFs) as precursors. The nitrogen-doped graphene wrapped okra-like SnO2 composites (SnO2@N-RGO) are successfully synthesized for the first time by using Sn-based metal-organic frameworks (Sn-MOF) as precursors. When utilized as an anode material for lithium-ion batteries, the SnO2@N-RGO composites possess a remarkably superior reversible capacity of 1041 mA h g-1 at a constant current of 200 mA g-1 after 180 charge-discharge processes and excellent rate capability. The excellent performance can be primarily ascribed to the unique structure of 1D okra-like SnO2 in SnO2@N-RGO which are actually composed of a great number of SnO2 primary crystallites and numerous well-defined internal voids, can effectively alleviate the huge volume change of SnO2, and facilitate the transport and storage of lithium ions. Besides, the structural stability acquires further improvement when the okra-like SnO2 are wrapped by N-doped graphene. Similarly, this synthetic strategy can be employed to synthesize other high-capacity metal-oxide-based composites starting from various metal-organic frameworks, exhibiting promising application in novel electrode material field of lithium-ion batteries.