Preparation methods and progress of manganese dioxide/graphene based composites in supercapacitors

The latest research progress of MnO₂/graphene based binary and ternary composites in supercapacitors are reviewed. Due to the stacking caused by van der Waals forces, the actual specific capacitance of graphene is not very high. The theoretical specific capacitance of MnO₂ is as high as 1370 F/g, but its pseudo capacitance is limited by the thickness of MnO₂, and the actual specific capacitance is much smaller than the theoretical value. The combination of graphene and MnO₂, where MnO₂ nanostructures anchored between graphene nanosheets as spacers, can effectively inhibit the stacking of graphene and enhance the interface charge transfer. With the synergistic effect of both functions, it is expected to achieve high specific capacitance and high conductivity and good cycling stability. The preparation method and electrochemical performance of MnO₂/graphene composites are introduced. The electrochemical performance of MnO₂/graphene ternary composites are analyzed. The introduction of metal oxides or conductive polymers can further improve the electrochemical performance. Finally, a series of issues for the application of MnO₂/graphene-based multi-component composites and devices are analyzed, such as safety and reliability, large-scale production and cost reduction. With the mature and break-through of technology, it is expected to achieve applications in industry, transportation and daily electronics.