Construction of hierarchical sugar gourd-like (Ni,Co)Se2/(Ni,Co)Se2/CC nanostructure with enhanced performance for hybrid supercapacitor

Abstract

Transitional metal selenides are regarded as promising electrode materials for battery-type electrodes on account of their superior electrical conductivity and high redox activity. It is expected to further improve their electrochemical performance by reasonable designing of the metal selenides’ components and construction of novel nanostructures. Thus, in this article, self-supported sugar gourd-like (Ni,Co)Se2/(Ni,Co)Se2 composites on carbon cloth are prepared by a facile approach. The theoretical calculations indicate that the (Ni,Co)Se2 has higher conductivity and larger adsorption energy of OH- than that of NiSe2 and CoSe2, thus effectively improving the kinetics of their electrochemical reactions. Thanks to synergetic effects from the active materials and their hierarchical nanostructures, the prepared sugar gourd-like (Ni,Co)Se2/(Ni,Co)Se2/CC nanoarrays achieve a high areal specific capacity of 1.278 mAh/cm2 (220.34 mAh/g) at 2 mA/cm2 and 88.9 % capacity retention after 5000 cycles. Furthermore, the flexible hybrid supercapacitor based on the designed nanocomposite demonstrates a high energy density of 0.7051 mWh cm−2 at the power density of 1.6303 mW cm−2 with extraordinary cycling stability. Such eminent energy storage performances strongly certificate that the obtained (Ni,Co)Se2/(Ni,Co)Se2/CC electrode is a potential battery-type electrode material for supercapacitor application.