MnO2 nanoflakes anchored on reduced graphene oxide nanosheets as high performance anode materials for lithium-ion batteries

Abstract

A MnO₂ nanoflake–reduced graphene oxide (MnO₂–rGO) composite was synthesized by a facile solution method. The composite exhibited excellent electrochemical performance with a reversible capacity of 1430 mA h g⁻¹ and 520 mA h g⁻¹ at current densities of 0.1 A g⁻¹ and 10 A g⁻¹, respectively. MnO₂ in the composite was proved to be fully activated and went through a complete conversion reaction. The improved kinetics in the MnO₂–rGO composite electrode were evidenced by Electrochemical Impedance Spectroscopy (EIS) results, accounting for its extraordinary electrochemical properties compared with that in a simple MnO₂–rGO mixture electrode. Due to the uniform dispersion and firm anchoring of MnO₂ nanoflakes on the rGO surface, the volume expansion of MnO₂ during the charge–discharge process was significantly alleviated. It showed excellent cyclic performance with an extremely large capacity of 1000 mA h g⁻¹ maintained after 200 cycles at the current density of 1 A g⁻¹.