Graphene Oxide-Wrapped Co 3 O 4 /NiO Micron Flowers as an Anode of Lithium-Ion Batteries with Enhanced Rate Performance and Cycling Stability.

A graphene oxide-wrapped Co 3 O 4 /NiO (denoted as CNO/GO) micron flower is successfully synthesized by a rapid solvothermal method, which is formed through interpenetrating nanosheets. Nanosheets with a large specific surface area expose a large number of active sites for an electrochemical reaction. Moreover, abundant pores formed during the interpenetration of nanosheets are instrumental in providing enough buffer space to relieve the large volume expansion from the repeated lithium insertion/delithiation processes, and the tightly wrapped GO can effectively sustain the stability of the CNO micron flower structure during the long-term cycle processes. The reversible specific capacity as high as 602.9 mA h g -1 is maintained after 800 cycles at 5000 mA g -1 . In addition, GO with good conductivity can greatly enhance the conductivity of CNO micron flowers, accelerate the transfer of electrons, and then achieve a high rate performance (the reversible specific capacity is 570.2 mA h g -1 at 10 000 mA g -1 ). This work provides a viable method for synthesizing the CNO micron flowers as a promising high-performance transition metal oxide anode for lithium-ion batteries.