Development and characterization of nanostructured Ni(OH)₂ electrodes for energy storage applications

Nanostructured Ni(OH)₂ electrodes grown on metalized, electro-spun nanofibers have been developed and characterized. On an active mass basis these electrodes, measured using an Ag/AgCl reference electrode, showed excellent specific capacitance of 2,123 F/g and specific capacity of 283 mA•h/g compared to the theoretical limits of 2190 F/g and 289 mA•h/g respectively. These electrodes were also able to achieve a maximum specific energy of 90 W•h/kg at a specific power of 727 W/kg and maintain a specific energy of 32 W•h/kg at a power density of 10 kW/kg. When optimized, the nanostructured electrodes had an internal surface area 5 orders of magnitude greater than an equivalent flat plate electrode and achieved a surface area to volume ratio of 2.5x105 cm-¹. Electrical equivalent circuit models were developed to understand device performance and showed a reasonable accuracy when compared with experimental data. Ultimately, device power density was limited by a combination of ohmic resistance and kinetic polarization. Significant mass transport polarization was suppressed due to a combination of low Ni(OH)₂ nanostructure thickness and high electrode porosity. This device architecture features an integrated current collector and the fabrication process does not require any high temperature or electrochemical processing, opening avenues for both cost reduction and manufacturing simplification. Possible applications of this technology are in advanced nickel metal hydride batteries or Ni(OH)₂ asymmetric storage devices.Science, Faculty ofPhysics and Astronomy, Department ofGraduat