Graphene Oxide-Wrapped Co3O4/NiO Micron Flowers as an Anode of Lithium-Ion Batteries with Enhanced Rate Performance and Cycling Stability

CNO/GOmicroflowers exhibit a high reversible specific capacityof 602.9 mA h g(-1) at 5000 mA g(-1) after 800 cycles, accompanied by a high Coulombic efficiency ofover 90%, except for the first cycle, indicating that the microflowerstructure and GO play a key role in realizing long-term cycling stabilityand superior reversibility. A grapheneoxide-wrapped Co3O4/NiO(denotedas CNO/GO) micron flower is successfully synthesized by a rapid solvothermalmethod, which is formed through interpenetrating nanosheets. Nanosheetswith a large specific surface area expose a large number of activesites for an electrochemical reaction. Moreover, abundant pores formedduring the interpenetration of nanosheets are instrumental in providingenough buffer space to relieve the large volume expansion from therepeated lithium insertion/delithiation processes, and the tightlywrapped GO can effectively sustain the stability of the CNO micronflower structure during the long-term cycle processes. The reversiblespecific capacity as high as 602.9 mA h g(-1) is maintainedafter 800 cycles at 5000 mA g(-1). In addition, GOwith good conductivity can greatly enhance the conductivity of CNOmicron flowers, accelerate the transfer of electrons, and then achievea high rate performance (the reversible specific capacity is 570.2mA h g(-1) at 10 000 mA g(-1)). This work provides a viable method for synthesizing the CNO micronflowers as a promising high-performance transition metal oxide anodefor lithium-ion batteries.