Effect of crystallite size on the intercalation pseudocapacitance of lithium nickel vanadate in aqueous electrolyte

Abstract

This work describes lithium nickel vanadate (LiNiVO4) as a pseudocapacitor electrode material for the first time. The micro and nano-sized LiNiVO4 are synthesized via mechanochemical reaction and hydrothermal reaction followed by calcination, respectively. The phase purity, surface morphology and microstructure of the LiNiVO4 synthesized by both methods are analysed by X-ray diffraction and scanning electron microscopy techniques. The lithium ion intercalation-extraction behaviour of the LiNiVO4 electrode material is investigated in 1 M LiOH electrolyte solution. The results demonstrate an improved capacitive performance for nano-sized LiNiVO4 electrode synthesized via hydrothermal reaction due to the collective effect of small size and additional redox sites. The nanocrystalline LiNiVO4 electrode exhibits a high specific capacitance of 456.56 F g−1 at a current density of 0.5 A g−1. The cycle stability test reveals exceptional capacitance retention of 99.60% even after 1000 cycles owing to the unique structural feature which permit intercalation mechanism. These findings demonstrate the significance of lithium transition metal vanadate-based electrode material in the development of lithium ion intercalation pseudocapacitors.