Graphene anchored mesoporous MnO2 nanostructures as stable and high-performance anode materials for Li-ion batteries

Abstract

Among various transition metal oxides, MnO2 is a promising anode material for Li-ion battery applications due to its lower discharge potential, good capacity and high abundance. However, poor electronic conductivity hampers its practical applications. Herein we report two unique mesoporous MnO2–graphene composites, M1-MnO2-G and M8-MnO2-G, where M1 and M8 represent the use of specific silica template, MCM-41 and MCM-48 respectively in deriving these phases. Our results show that as anode materials for Li-ion battery application, both the composites exhibit good cycling stability, high discharge capacity, and superior rate performance. For instance, M1-MnO2-G and M8-MnO2-G deliver stable discharge capacity of 1112 mA h g−1 and 1494 mA h g−1 at C/5 rate. The high specific capacities and superior rate performance of the composites are due to the synergistic effects of graphene integrated mesoporous MnO2. The mesoporous architecture with nano-size wall thickness provides shorter diffusion paths for Li+ ion conduction in addition to facilitating uniform electrolyte infiltration throughout the electrode, while the graphene enhances the electronic conductivity and mechanical strength of the composite electrode. Full cell studies using mesoporous MnO2-Graphene composites anode against LiNi0.8Mn0.1Co0.1O2 cathode (M8-MnO2-G║LiNMC811) indicate very stable capacity (200 cycles at 0.1C) and high rate (5C) performance.