Hydrothermally decorating MnO2 onto NiCo layered double hydroxide nanosheets for electrochemical energy storage

Abstract

In research out of the sustainable electrochemical energy storage material, NiCo-LDH/MnO2 composite has been prepared via simple hydrothermal method. The experimental characterizations of XRD, SEM/TEM and XPS have been utilized to explore the structure and morphology of prepared composite. The needle-like MnO2 was found adhered to NiCo-LDH sheet. The composite's electrochemical properties were evaluated through cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. It has been realized that the MnO2 dosage not only changes the composite's microstructure but also affects its electrochemical properties. The best specific capacitance (2602 F g−1 at a current density of 1 A g−1) was achieved for the composite sample with 38% MnO2 (mass), which is almost two times high from the same composite in previous reports. With the sample, the assembled asymmetric supercapacitor exhibits a remarkable energy density of 19.56 Wh.Kg−1 at 800.29 W Kg−1. It could be attributed to the synergetic effects of two components as well as their good interfacial coupling. The good electrochemical activity makes our synthesized composite feasible to be applied as electrode material and provides valuable insights for the development of smart capacitors utilizing NiCo-LDH.