Date of Award
Master of Science (MS)
The fabrication of supercapacitor devices consisting of boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs) has great theoretical capabilities of high specific capacitance, energy density, and power density. Various methods of dispersion and deposition are utilized to optimize such supercapacitors with BNNTs and CNTs, and also to produce devices with only CNTs to use as a benchmark. In addition to capacitance measurements, BNNTs that were exposed to nitric acid were compared to fabricated devices without acid exposure.
Dispersion has been accomplished through the trial of many solvents and surfactants for both CNTs and BNNTs. Deposition techniques that are utilized rely heavily on vacuum filtration and spray deposition techniques. The resultants of fabrication have been tested with capacitance voltage measurements and transmission electron microscopic images are used to analyze solutions.
The highest specific capacitance was found in a fabricated device without including BNNTs, as a device fabricated from CNTs as the electrode, a polymer electrolyte, a dielectric separator of nafion, and foil contacts, had a specific capacitance of 0.51 mF/g. This device also had 0.13 Wh/kg for energy density, and 3.02 kW/kg for power density. However, despite this measurement of highest specific capacitance achieved without using BNNTs, a device made of only CNTs, BNNTs, foil contacts, and electrolyte, had the highest energy density of 0.15 Wh/kg and power density of 4.29 kW/kg. This device also had one of the highest measured specific capacitances of 0.27 mF/g.
The CNTs and BNNTs were chosen to be used together because of costs and availability and their ideal structures for use as an electrode and a separator, respectively. Both materials have lattice structures that can be rolled into tubes to create bonds and also strengthen the material between walls. The porous structures also allow an electrolyte to seep into the pores to promote charge separation. Carbon is an ideal electrode and boron nitride has high dielectric properties suited for a capacitor separator.
The devices showed consistent capacitance characteristics with higher power density than energy density. The techniques used for fabrication, measurement, and further optimization are mentioned throughout this paper. Cleaning BNNTs in nitric acid proved to promote better physical and electrical properties for the resultant solutions and devices.
Demuth, Derek C.. "Carbon and Boron Nitride Nanotube Fabricated Supercapacitors" (2016). Master of Science (MS), thesis, Electrical/Computer Engineering, Old Dominion University, https://digitalcommons.odu.edu/ece_etds/6