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

Abstract

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.