In situ growth of MnO@Na2Ti6O13 heterojunction nanowires for high performance supercapacitors

Abstract

One-dimensional tunnel and layer frame crystal structure materials are extremely attractive for energy storage in electrode materials. The energy storage properties of the electrode materials depend on their conductivity. Furthermore, the conductivity of electrode materials can be tailored through combination or doping with other materials, which transforms their properties from semiconductor to semimetallic or metallic and allow them to show unequaled performance for storage devices. In this work, heterostructures of manganese oxide (MnO) and modified sodium titanate (Na2Ti6O13) (MnO@Na2Ti6O13) nanowires are attained by the in situ thermal decomposition method. The heterojunction between MnO and Na2Ti6O13 allows the semiconductor properties of pure Na2Ti6O13 to show remarkable metallic behavior for improving the electrochemical performance. The capacitance of MnO@Na2Ti6O13 heterojunction nanowires can reach 272.3 F g−1, a power intensity of 250 W kg−1 at the energy density of 37.83 Wh kg−1 and retain 5000 W kg−1 at 6.67 Wh kg−1 as well. The energy storage mechanism of the MnO@Na2Ti6O13 heterostructure is studied by density functional theory. All of the results show that the MnO@Na2Ti6O13 heterostructure material has the potential to be an excellent supercapacitor material in the future.