Ultrasonic synthesis of CoO/graphene nanohybrids as high performance anode materials for lithium-ion batteries

A facile ultrasonic method was used to synthesize CoO/graphene nanohybrids by employing Co-4(CO)(12) as a cobalt precursor. The nanohybrids were characterized by SEM, TEM and XPS, and the results show that CoO nanoparticles (3-5 nm) distribute uniformly on the surface of graphene. The CoO/graphene nanohybrids display high performance as an anode material for lithium-ion battery, such as high reversible lithium storage capacity (650 mA.h/g after 50 cycles, almost twice that of commercial graphite anode), high coulombic efficiency (over 95%) and excellent cycling stability. The extraordinary performance arises from the structure of the nanohybrids: the nanosized CoO particles with high dispersity on conductive graphene substrates are beneficial for lithium-ion insertion/extraction, shortening diffusion length for lithium ions and improving conductivity, thus the lithium storage performance was improved.