Enhanced Supercapacitive Performance of Chemically Grown Cobalt-Nickel Hydroxides on Three-Dimensional Graphene Foam Electrodes

摘要

Chemical growth of mixed cobalt-nickel hydroxides (Co_xNi_(1-x)(OH)2), decorated on graphene foam (GF) with desirable three-dimensional (3D) interconnected porous structure as electrode and its potential energy storage application is discussed. The nanostructured Co_xNi_(1-X)(OH)2 films with different Ni:Co (x) compositions on GF are prepared by using the chemical bath deposition (CBD) method. The structural studies (X-ray diffraction and X-ray photoelectron spectroscopy) of electrodes confirm crystalline nature of Co_xNi_(1-x)(OH)2/GF and crystal structure consists of Ni(OH)2 and Co(OH)2. The morphological properties reveal that nanorods of Co(OH)2 reduce in size with increases in nickel content and are converted into Ni(OH)2 nanoparticles. The electrochemical performance reveals that the Co_(0.66)Ni_(0.33)(OH)2/GF electrode has maximum specific capacitance of ～1847 F g~(-1) in 1 M KOH within a potential window 0 to 0.5 V vs Ag/AgCl at a discharge current density of 5 A g~(-1). The superior pseudoelectrochemical properties of cobalt and nickel are combined and synergistically reinforced with high surface area offered by a conducting, porous 3D graphene framework, which stimulates effective utilization of redox characteristics and communally improves electrochemical performance with charge transport and storage.