Enhanced the electrochemical performance of Ni-doped α-MnO2 prepared with one-pot process for supercapacitors

Abstract

Poor capacitive behavior caused by low electronic conductivity and slow reaction kinetics is the main obstacle faced by the MnO2 electrode materials in current supercapacitors. Herein, the influence of Ni doping on the capacitive behavior of α-MnO2 synthesized by a low-cost and one-pot chemical coprecipitation method was investigated. During the doping process, the amount of Ni was increased from 0.05 mmol to 0.45 mmol in steps of 0.1 mmol. The structure and chemical composition of Ni-doped MnO2 (MnO2-Ni) were characterized by XRD, FTIR, SEM, EDS, and XPS. Comprehensive studies show that no change in the crystal phase structure of MnO2, while the decrease in the nanoparticle size and the increase in electronic conductivity by Ni doping, which improve the capacitive behavior of α-MnO2. With specific capacitance values increasing with increasing amounts of Ni up to a certain limit 0.25 mmol, the specific capacitance of 325.8 F/g was given by MnO2-Ni electrode at a current density of 0.5 A/g, which was nearly 1.72 times that of MnO2 electrode of 189.47 F/g. Moreover, the MnO2-Ni electrode showed excellent capacitance retention (112%) than the MnO2 electrode (109.5%) after 3000 cycles.