Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Electrical Engineering and Computer Science

First Advisor

Qiquan Qaio


High cost and environmentally unfavorable impacts are the significant difficulties that prohibit renewable energy storage from many applications. To work with these problems, novel renewable materials such as biomass derived carbon that have high surface area and low cost should be used. Renewable biochar carbon YP-50, synthesized from coconut, and activated using different plasma gases including methane (CH4), carbon dioxide (CO2), hydrogen (H2), and argon (Ar). Compared with the conventional activation method, the plasma treatment takes less effort and time. Significant improvements of the specific capacitance (SC) and specific surface area (SSA) were observed with different plasma treatments. For example, the CH4 plasma treated carbon biochar offered the highest SC of 181.6 F g-1 at 0.05 A g-1 compared with other gases. In addition, the highest energy density of 25.3 wh kg-1 was obtained at the specific power of 0.12 kW kg-1 for CH4 activated carbon. This enhancement of charge storage capacity is distinctly associated with the distribution of a variety of pore sizes and a large surface area. Furthermore, the charge transfer resistance reduced from 21.7 Ω to 1.4 Ω after CH4 was activated. High capacitance retention was achieved due to its excellent electrochemical stability and good performance. Hence, this high-energy plasma treatment with short manufacturing time created a new opportunity for the efficient activation of carbon materials of supercapacitors with high electrochemical performance.

Library of Congress Subject Headings

Energy storage.
Biomass energy.
Renewable natural resources.



Number of Pages



South Dakota State University



Rights Statement

In Copyright