Novel Three-dimensional Hierarchical Flower-like NiO-Co3O4 Composites as High-performance Electrode Materials for Supercapacitors

In the present work, novel three-dimensional (3D) hierarchical NiO-Co3O4 composites are prepared by a facile and template-free hydrothermal method with L-lysine as the chelating agent. The flower-like NiO-Co3O4 composites display a high specific surface area and desirable pore distribution. The electrochemical performances are investigated by cyclic voltammetry, galvanostatic charge-discharge, and cycle life. The results reveal that the novel NiO-Co3O4 composites exhibit a high specific capacitance of 1988.6 F g-1 at 1 A g-1 and 1491.4 F g-1 at 15 A g-1. Furthermore, the composites show an excellent cycling performance and stability with capacity retention of 94.0 % after 1500 cycles at 10 A g-1. The outstanding capacitive behaviors are ascribed to the desirable composition and the unique 3D hierarchical flower-like structure.