Synthesis and Electrochemical Properties of One‐Dimensional γ‐MnOOH Nanorods

Abstract

MnOOH has received much attention from researchers as a supercapacitor electrode material. In this article, one‐dimensional γ‐MnOOH nanorods were prepared by the hydrothermal method using the redox reaction between MnO4− and Mn2+, and the effects of temperatures on the crystalline phases and electrochemical properties of the samples were investigated. The materials were characterized using XRD, FT‐IR, SEM, TEM, Raman and XPS; electrochemical properties were tested using CV, GCD and EIS. The results show that the reaction temperature plays an important role in the generation of γ‐MnOOH. The samples were pure phases of γ‐MnOOH (M‐140) at the reaction temperature of 140 °C, showing interlaced nanorod morphology, and when the reaction temperature was increased to 180 °C, a mixed phase of MnOOH and Mn3O4 appeared. In contrast, the electrochemical performance of γ‐MnOOH nanorods (M‐140) was superior to the other samples, reaching a specific capacitance of 221 F/g at a current density of 0.2 A/g. The capacitance retention was 93.8 % after charging and discharging the M‐140 2000 times at a current density of 6 A/g. Supercapacitors assembled with γ‐MnOOHand activated carbon (AC) have excellent energy storage performance, and a high energy density of 40.6 Wh/kg is obtained at a power density of 196.7 W/kg.