A Self-Transition Strategy toward Nanostructured Cu-MoO2/rGO Composite as Anodes for Lithium-Ion Batteries with High Initial Coulombic Efficiency and Cycle Stability

Abstract

The cycle stability and initial Coulombic efficiency (ICE) of molybdenum dioxide (MoO2) are generally inferior as anode materials for lithium ion batteries. Herein, we report a facile self-transition strategy to prepare a hierarchically nanostructured Cu-MoO2/reduced graphene oxide (rGO) composite. The prepared Cu-MoO2/rGO composite exhibits a reversible capacity as high as 970 mAh g−1 after 200 discharge/charge cycles at 100 mA g−1, superior ICE (80.4%), and excellent cyclability (607 mAh g−1 even after 600 discharge/charge cycles at 500 mA g−1 with a Coulombic efficiency of 98.8%). The enhanced electrochemical performance is attributed to the formation of a multi-hierarchical nanostructure of Cu-MoO2/rGO composite. Such a unique structure well adapts to the volume variation of MoO2 upon cycling and greatly enhances the kinetics of charge transfer. Furthermore, the homogeneous dispersion of Cu nanocrystallites among the MoO2 crystals not only creates the conductive path in the whole structure, but also provides sufficient channels for Li+ insertion/extraction. These results are envisaged to pave the way toward the rational design and fabrication of nanostructured electrode materials with enhanced electrochemical properties for next-generation lithium ion batteries.