Carbon-Coated Fe₃O₄/VO_x Hollow Microboxes Derived from Metal-Organic Frameworks as a High-Performance Anode Material...

As the ever-growing demand for high-performance power sources, lithium-ion batteries with high storage capacities and outstanding rate performance have been widely considered as a promising storage device. In this work, starting with metal-organic frameworks, we have developed a facile approach to the synthesis of hybrid Fe₃O₄/VO_x hollow microboxes via the process of hydrolysis and ion exchange and subsequent calcination. In the constructed architecture, the hollow structure provides an efficient lithium ion diffusion pathway and extra space to accommodate the volume expansion during the insertion and extraction of Li⁺. With the assistance of carbon coating, the obtained Fe₃O₄/VO_x@C microboxes exhibit excellent cyclability and enhanced rate performance when employed as an anode material for lithium-ion batteries. As a result, the obtained Fe₃O₄/VO_x@C delivers a high Coulombic efficiency (near 100%) and outstanding reversible specific capacity of 742 mAh g^-1 after 400 cycles at a current density of 0.5 A g^-1. Moreover, a remarkable reversible capacity of 556 mAh g^-1 could be retained even at a current density of 2 A g^-1. This study provides a fundamental understanding for the rational design of other composite oxides as high-performance electrode materials for lithium-ion batteries.