Web Release Date: October 16,
Microstructure and Electrochemical Properties of Al-Substituted Nickel Hydroxides Modified with CoOOH Nanoparticles
and
Institute of New Energy Chemistry Material, Department of Materials Chemistry, Nankai University, Tianjin 300071, China, and School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, Queensland 4001, Australia
Received: July 17, 2007
In Final Form: August 31, 2007
Abstract:
Aluminum-substituted 
-phase nickel hydroxide (Al--Ni(OH)2) microspheres with high structural stability
are synthesized, and their surface modification by CoOOH nanoparticles is made subsequently in order to
improve their electrochemical performance. The morphology, microstructure, and chemical state of the Al--Ni(OH)2 microspheres, before and after coating, are investigated by X-ray diffraction (XRD), scanning
electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS),
and Fourier transform infrared spectra (FTIR). It is found that CoOOH nanoparticles with a rod-like morphology
are either dispersed randomly on the surface or intercalated between nanosheets of the Al--Ni(OH)2
microspheres. The effect of CoOOH nanoparticles on the electrochemical performance of Al--Ni(OH)2
microspheres is investigated by galvanostatic charge-discharge experiments and cyclic voltammetry (CV).
It is demonstrated that the Al--Ni(OH)2 microspheres, coated with 7 wt % CoOOH nanoparticles, have an
enhanced discharge capacity, high-rate discharge ability, discharge potential plateau, and cycle stability. The
improvement of the electrochemical performance of Al--Ni(OH)2 microspheres is mainly attributed to
formation of highly conductive CoOOH nanoparticles on the surface of Al--Ni(OH)2 microspheres and
good electrochemical accessibility of the microspherical aggregates of Al--Ni(OH)2 nanosheets, which result
in the good reversibility and high electrochemical activity of the positive materials.
Download the full text: PDF | HTML
