Assembly control of CoO/reduced graphene oxide composites for their enhanced lithium storage behavior

Abstract

We report on the strategy of controlling the morphology of CoO/reduced graphene oxide (rGO) composites through regulating the assembly of CoO nanoparticles in the CoO/rGO composites by using oleic acid (OA). With increasing of OA amount, the morphologies and structures of CoO/rGO composites display special changes. The OA was found to influence the assembly of CoO nanoparticles on the surface of rGO sheets. As the content of OA is 1 mL, the obtained CoO/rGO composites (S1) shows 3-D network CoO anchored with rGO sheets structure. This 3-D CoO microstructure is composed of intertwined nanowires which assembled by tiny CoO nanoparticles. Moreover, S1 exhibits superior cycle and rate capacitance. The reversible capacity of S1 can reach 1309 mA h·g−1 after 100 cycles at 0.1 A·g−1. Even at 2 A·g−1, the reversible capacity of S1 still maintains 550 mA h·g−1. The excellent electrochemical performance of S1 profits from its unique 3-D structure, accelerating the charge transfer rate in the conversion reaction in the lithiation/delithiation process. It believes that this work will inspire the variation of structural design in transition metal oxides (TMOs) and graphene composites as anode materials for LIBs.