GeOx/Reduced Graphene Oxide Composite as an Anode for Li-Ion Batteries: Enhanced Capacity via Reversible Utilization of Li2O along with Improved Rate Performance



A self-assembled GeOx/reduced graphene oxide (GeOx/RGO) composite, where GeOx nanoparticles are grown directly on reduced graphene oxide sheets, is synthesized via a facile one-step reduction approach and studied by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, electron energy loss spectroscopy elemental mapping, and other techniques. Electrochemical evaluation indicates that incorporation of reduced graphene oxide enhances both the rate capability and reversible capacity of GeOx, with the latter being due to the RGO enabling reversible utilization of Li2O. The composite delivers a high reversible capacity of 1600 mAh g−1 at a current density of 100 mA g−1, and still maintains a capacity of 410 mAh g−1 at a high current density of 20 A g−1. Owing to the flexible reduced graphene oxide sheets enwrapping the GeOx particles, the cycling stability of the composite is also improved significantly. To further demonstrate its feasibility in practical applications, the synthesized GeOx/RGO composite anode is successfully paired with a high voltage LiNi0.5Mn1.5O4 cathode to form a full cell, which shows good cycling and rate performance.