Fabrication And Electrochemical Properties Of Three-dimensional Porous Nickel Hybrid Electrode

Since human society has faced challenges of energy shortage and environmentalpollution, new energy materials and energy storage materials have become an importantdevelopment of the world of science. As a new energy storage materials, electrochemicalsupercapacitor materials have advantages such as high charge-discharge rate and long cyclelife, etc., and attract the widespread attention of governments and scientists. Among them,NiO/Ni(OH)2is one of the most promising electrode materials for supercapacitor due to itshigh specific capacitance (theoretical specific capacitance of3750F/g), environmentfriendliness, and low cost. The present thesis broke the shackles of the traditional methods,combing the template method and cyclic voltammetry growth method to fabricate thethree-dimensional nickel hydroxide-nickel hybrid electrode. The present thesis also exploredeffective ways to prepare high performance electrochemical supercapacitor electrode materialby adjusting the microstructure and composition of the hybrid electrode.In the present thesis, a three-dimensional interconnected porous nickel hydroxide-nickelhybrid electrode was fabricated by electroforming nickel on anodized etched aluminumfollowed by electrochemical treatment. Experimental results showed that porous nickel couldobtain huge specific surface area when it was roughened by cyclic voltammetry cyclingbetween-1.5V and-0.2V. The nickel hydroxide was grown in-situ on the roughened porousnickel by cyclic voltammetry cycling between0and0.5V and the XRD results confirmed theexistence of α-Ni(OH)2. High volumetric capacitance (1559F/cm3) and large arealcapacitance (7.01F/cm2)(at a scan rate of1mv/s) were obtained for the hybrid electrodes.The present hybrid electrodes also showed good cycling stability (93%of the initialcapacitance after500cycles at a scan rate of10mV/s).A periodic pillared-layer α-Ni(OH)2/nickel hybrid electrode was also fabricated byelectroforming nickel on an interconnected anodic alumina photonic crystal template followedby cyclic voltammetry in this thesis. The periodic pillar-layered hybrid electrodes showed theultrahigh volumetric capacitance of1387F/cm3and large areal capacitance of2.51F/cm2 calculated from the discharge curves (at discharge current densities of5mA/cm2) and it alsoshowed good cycling stability (no loss of capacitance after1000cycles at a scan rate of10mV/s). The enhanced capacity performance for the layered hybrid electrode is mainlyattributable to the optimized nanostructure of the current collector.