Hydrothermal synthesis of urchin-like MnO₂ nanostructures and its electrochemical character for supercapacitor

Highlights: • Urchin-like α-MnO₂ nanostructures were synthesized via a hydrothermal process. • The possible formation mechanism of the urchin-like α-MnO₂ was discussed. • The evolution of the urchin-like nanostructures due to the increase of reaction temperature. • The urchin-like α-MnO₂ exhibits high specific capacitance of 151.5 F g⁻¹. • The urchin-like α-MnO₂ shows 93.4% capacitance retention after 1000 cycles. - Abstract: Urchin-like α-MnO₂ nanostructures were successfully synthesized via a simple hydrothermal process at different synthesis temperatures without using any template or surfactant. The microstructure and morphology of as-synthesized products were systematically investigated by focused ion beam, transmission electron microscopy, and high-resolution transmission electron microscopy. The electrochemical test of the prepared MnO₂ exhibits ideal cyclic voltammetry behavior, high specific capacitance (151.5 F g⁻¹ at a current density of 1 A g⁻¹) and excellent cycling stability (93.4% capacitance retention after 1000 cycles) which suggests its promising application as supercapacitor