Nanostrucutured MnO₂-TiN nanotube arrays for advanced supercapacitor electrode material

The capacitance of MnO₂ supercapacitors (SCs) is not high as expected due to its low conductivity of MnO₂. The synergistic effects of MnO₂ with high theoretical specific capacitance and TiN with high theoretical conductivity can extremely enhance the electrochemical performance of the MnO₂-TiN electrode material. In this work, we synthesized different nanostructured and crystalline-structured MnO₂ modified TiN nanotube arrays electrode materials by hydrothermal method and explained the formation mechanism of different nanostructured and crystalline-structured MnO_2. The influences of MnO₂ nanostructures and crystalline-structures on the electrochemical performance has been contrasted and discussed. The specific capacitance of δ-MnO₂ nanosheets-TiN nanotube arrays can reach 689.88 F g^-1, the highest value among these samples TN-MO-SS, TN-MO-S, TN-MO-SR, TN-MO-RS, and TN-MO-R. The reason is explained based on MnO₂ nanostructure and crystalline-structure and electron/ion transport properties. The specific capacitance retention rates are 97.2% and 82.4% of initial capacitance after 100 and 500 cycles, respectively, indicating an excellent charging-discharging cycle stability.