Microwave-assisted design and fabrication of rare earth doped NiMoO4: An admirable electrode material in redox electrolytes with excellent power density for high-end energy storage systems

Abstract

In the recent advancement of energy storage, electrode materials delivering high energy density and the capability to deliver noteworthy power compared to batteries are considered to be promising materials. In this study, hierarchical-structured NiMoO4 and various concentrations of Ce rare earth metal doped NiMoO4 materials have been synthesized by microwave-assisted combustion route. Their structural, morphological, and spectroscopical characteristics have been studied using different characterization and analytical techniques. The α to β-NiMoO4 phase transformation with the same crystal structure has been confirmed after the addition of 5% Ce dopant. The crystallite size, cell volume, and particle size of the β-NiMoO4 seems to be minimal with maximum dislocation density compared to the prepared α-NiMoO4 samples. The initial nanospheres are clustered in different orientations to form different morphological structures. All the samples have been evaluated as electrodes for highly efficient electrochemical supercapacitors. The 5%-Ce doped NiMoO4 electrode has revealed an extraordinary supercapacitive performance showing excellent specific capacitance of 3101.12 Fg‐1 at 1 mA current with good retentivity of 97.65% after 5000 cycles in a three-electrode configuration, which is six times higher value than the prepared pristine NiMoO4 (478.78 Fg‐1). Besides, an asymmetric supercabattery device has been fabricated utilizing NiMoO4‐5% Ce electrode and activated carbon as positive and negative electrodes in a two-electrode configuration. It displayed a fascinating energy density of 29.2 W h kg−1 even at high current density of 5 mA. Prominently, the supercabatteries device showed an admirable 80.55% long-lasting cycling performance retained after 10,000 cycles.