Metal–Organic Framework Derived Core–Shell Co/Co₃O₄@N-C Nanocomposites as High Performance Anode Materials for Lithium Ion Batteries

Abstract

Metal-organic frameworks (MOFs) with diverse structures, adjustable pore sizes, and high surface areas have exhibited awesome potential in many fields. Here we report a simple carbonization strategy to obtain a series of core-shell structured Co/Co₃O₄ nanoparticles encapsulated into nitrogen-doped carbon shells from cobalt-based metal-organic framework precursors at different carbonization temperatures. When it is applied as an anodes for lithium ion batteries, the Co/Co₃O₄@N-C-700 electrode delivers a maximum initial discharge capacity of 1535 mAh g^-1, the highest reversible capacity (903 mAh g^-1 at a current density of 100 mA g^-1 after 100 cycles), and the best rate performance (i.e., 774 mAh g^-1 at a current density of 1.0 A g^-1 after 100 cycles) in comparison with those of Co/Co₃O₄@N-C-600 and Co/Co₃O₄@N-C-800 electrodes. The excellent electrochemical performance could be mainly attributed to the unique core-shell structure, abundant graphited carbon, and the well-dispersed Co/Co₃O₄ nanoparticles which can promote the specific capacity through conversion reactions.