Synthesis of free-standing MnO₂/reduced graphene oxide membranes and electrochemical investigation of their performances as anode materials for half and full lithium-ion batteries

MnO₂ nanotubes/reduced graphene oxide (MnO₂/RGO) membranes with different MnO₂ contents are successfully synthesized by a facile two-step method including vacuum filtration and subsequent thermal reduction route. The MnO₂ nanotubes obtained are 38 nm in diameter and homogeneously imbedded in RGO sheets as spacers. The synthesized MnO₂/RGO membranes exhibit excellent mechanical flexibilities and free-standing properties. Using the membranes directly as anode materials for lithium batteries (LIBs), the membranes for half LIBs show superb cycling stabilities and rate performances. Importantly, the electrochemical performances of MnO₂/RGO membranes show a strong dependence on the MnO₂ nanotube contents in the hybrids. In addition, our results show that the hybrid membranes with 49.0 wt% MnO₂ nanotube in half LIBs achieve a high reversible capacity of 1006.7 mAh g⁻¹ after 100 cycles at a current density of 0.1 A g⁻¹, which is higher lithium storage capacity than that of reported MnO₂-carbon electrodes. Furthermore, the synthesized full cell (MnO₂/RGO//LiCoO₂) system also exhibit excellent electrochemical performances, which can be attributed to the unique microstructures of MnO₂ and GRO, coupled with the strong synergistic interaction between MnO₂ nanotubes and GRO sheets.