UNH Chemical Engineering Department Faculty Advisor : Professor Xiaowei Teng

1. Methodology Purpose of the Experiment Results • This project involves the investigation and application of metal oxides (vanadium oxide) for super-capacitors applications. In society and even in the university’s culture, sustainability maintains a large amount of support and requires innovation regularly to keep up with the ever increasing demands of energy. Major leaps can be made in terms of saving energy by replacing inefficient energy sources in their respective applications with fuel cells, batteries, and capacitors. Some areas of particular interest include mobile batteries and such things like car remotes. Because batteries provide energy over a long period of time (high energy density) and capacitors deliver energy in short burst intervals (high power density), research in combining technologies (e.g., super-capacitor) is then at the forefront of the investigation. • What is a typical capacitor: • Purpose: Store energy • Its poor energy density is compensated through its ability to transfer energy with a high rate (power density). • Function includes quick charge/discharge (cycling) with no energy generation characteristics • Moving away from batteries: • Poor cycling capabilities • Limited longevity, needs replacement after discharge • Bridging the gap between batteries and capacitors with Pseudocapacitors: • Capacitors provide greater amounts of energy in small amounts of time • Batteries and fuel cells provide smaller amounts of energy over longer amounts of time • Pseudocapacitors have become a strong candidate to fill this energy/power void • Cyclic Voltammetry- Measures capacitance of VOx / PEDOT mixture (a) • Capacitance a function of scan rate (b). • A scan rate of 5 mV/s resulted in a maximum capacitance of 136 F/g (b). • Chronopotentiometry- Measures actual capacitance of Vox (c) • Upon determination of the competitiveness of the material, full-cell performance analyses were conducted. • Capacitance a function of number of cycles. • Full cell performance indicates metal oxide is suitable for commercial development as a pseudocapacitor. Pseudocapacitors (Super Capacitors): What are they? TEM images of VOx precursors after being annealed at (a) 250 oC and (b) 450 oC Synthesis of V2O5 Conclusion • Synthesized VOx structure to test capacitance capabilities. • Final composition of the rolled up vanadium nanofibres is K0.33V2O5 • After burning the samples at 250 degrees celcius, the structure was found to have unstable morphology and therefore would degrade rapidly with increasing cycles. • Maximum theoretical capacitance was found to be 136 F/g annealed at 450 oC. • Other works found the maximum theoretical capacitance for Vanadium Pentoxide to be between 170-350 F/g annealed at 300 cC Acknowledgements • UNH Chemical Engineering Department • Faculty Advisor : Professor Xiaowei Teng • Graduate Students mentors: Matthew Yeager, Wenxin Du • Collaborators • Prof. N. Aaron Deskins, Worcester Polytechnic Institute, DFT calculations • Dr. Dong Su, Brookhaven National Laboratory, TEM measurements • Drs. Wenqian Xu, Sanjaya D. Senanayake, Jonathan Hanson, Brookhaven National Laboratory, XRD measurements Vanadium Oxide as a Potential Pseudocapacitor AnodeMatthew Sullivan,Brendan Bishop, Wenxin Du, Matthew Yeager,Xiaowei Teng* Department of Chemical Engineering, University of New Hampshire • Reagents: VOSO4xH2O, 10mL/mg H20 in reaction flask • Injected Reagents: KOH, 17.3mL/mg H20 • Synthetic Procedures • stirring VOSO4xH20 in water • injecting KOH to form vanadium hydroxide • oxidizing solution over time by air to form final metal oxide V2O5 References • Yeager,MP, Du,W, Bishop, B, Sullivan, M, Xu,W, Su,D, Senanayake, SD, Hanson, J, Teng, X. “Rolling-Up” Formation of K0.33V2O5 Nanofibers as Superca-pacitors Anode, To be submitted to JACS. • Yeager, MP, Du, W, Bishop, B, Sullivan, M, Xu,W, Su,D, Si, R, Deskin, NA, Senanayake, SD, Hanson, J, Teng, X. ChemSuSChem, Accepted