Graphene Oxide-Wrapped\nCo₃O₄/NiO Micron Flowers as an Anode of Lithium-Ion\nBatteries with Enhanced\nRate Performance and Cycling Stability

Abstract

A graphene\noxide-wrapped Co₃O₄/NiO\n(denoted\nas CNO/GO) micron flower is successfully synthesized by a rapid solvothermal\nmethod, which is formed through interpenetrating nanosheets. Nanosheets\nwith a large specific surface area expose a large number of active\nsites for an electrochemical reaction. Moreover, abundant pores formed\nduring the interpenetration of nanosheets are instrumental in providing\nenough buffer space to relieve the large volume expansion from the\nrepeated lithium insertion/delithiation processes, and the tightly\nwrapped GO can effectively sustain the stability of the CNO micron\nflower structure during the long-term cycle processes. The reversible\nspecific capacity as high as 602.9 mA h g^–1 is maintained\nafter 800 cycles at 5000 mA g^–1. In addition, GO\nwith good conductivity can greatly enhance the conductivity of CNO\nmicron flowers, accelerate the transfer of electrons, and then achieve\na high rate performance (the reversible specific capacity is 570.2\nmA h g^–1 at 10 000 mA g^–1). This work provides a viable method for synthesizing the CNO micron\nflowers as a promising high-performance transition metal oxide anode\nfor lithium-ion batteries.