Engineering Commons^™

Novel Coating Methods On Centrifugally-Spun Polymer Fibers For Applications In Lithium-Ion Batteries, Jonathan G. Ayala

Theses and Dissertations

The work presented in this thesis focuses on the processing, characterization, and electrochemical results of centrifugally spun composite carbon fiber electrodes for application as anode material in lithium-ion batteries. The work is presented as a compilation of two major projects. First, the use of novel Co3O4 wet coatings to increase the capacity of carbon fibers produced from Polyacrylonitrile (PAN). In this work, PAN fibers are produced via the Forcespinning method, and were heat treated by oxidation in air at 200 °C for four hours, and subsequent carbonization at 600 °C for six hours. The electrochemical performance of the Co3O4/C composite-fiber …

Centrifugally-Spun Ceramic/Carbon Composite Fibers And Their Use As Anode Materials In Li-Ion Batteries, Gabriel Gonzalez

Theses and Dissertations

The work in this thesis focuses in the study of Centrifugally Spun Short Fiber Composites and their Implementation as Alternate Anode Material in Li-Ion Batteries. Due to their high theoretical capacity, abundance, and environmental friendliness, metal oxides have been widely studied as alternate anode materials for lithium ion batteries (LIBs). In this research work, the processing of SnO2 and SnO2/TiO2 ceramic short fibers as well as flexible and porous metal oxide carbon fibers (FPMOCFs) by centrifugal spinning followed by an optimized coating technique is reported. In addition, the electrochemical performance of the composites was also investigated and is provided.

Thermoelectric Generation And Thermophysical Properties Of Metal Oxide Nanofluids, Xinran Hou, Rong-Tsu Wang, Shaowen Huang, Jung-Chang Wang

Journal of Marine Science and Technology

This study describes the comprehensive characterization of the diverse water-based nanofluids involving aluminum oxide, titanium dioxide, and zinc oxide nanoparticles, which were prepared through the two-step synthesis method assisted by a microemulsion ultrasound skill with effects of both weight-percent concentration (wt.%) in the range of 1.0% and 5.0% and between 20 ^oC and 40 ⁰C. The mean cluster size, zeta potential, pH value, viscosity, thermal conductivity, absorbance, light absorption, and electrical charge density of the various nanofluids were surveyed by relative experiments. The results showed that the 2 wt.% Al₂O₃, 2 wt.% TiO_{2 …}

Enhanced Kinetics And Modeling Of Pan-Based Carbon Felt Anodes In Vanadium Redox Flow Batteries, Michael Cyrus Daugherty

Doctoral Dissertations

All-vanadium redox flow batteries (VRFBs) are a promising technology for grid-level energy storage, however, there are still several limitations in the forms of durability, efficiency, and overall costs, which are barriers to its commercial viability. With both bulk electrolyte flowing through its porous matrix and species flux at the solid-electrolyte interface, electrodes are the component of VRFB systems which host electrochemical reactions and facilitate contact between the liquid phase electrolyte and the electronically conductive solid phase. While the more limiting electrode in VRFB systems is dependent on the material, for polyacrylonitrile (PAN)-based carbon felts, the anode constitutes a larger portion …

Micro/Nanostructured Mnco2o4.5 Anodes With High Reversible Capacity And Excellent Rate Capability For Next Generation Lithium-Ion Batteries, Bin Wang, Shifeng Wang, Yuanyuan Tang, Chi-Wing Tsang, Jinchuan Dai, Michael K.H. Leung, Xiao-Ying Lu

Faculty of Science & Technology (THEi)

Lithium-ion batteries have already achieved great success in consumer electronics. However, the electrochemical characteristics of the existing electrodes have constrained their widespread applications in electric vehicles, which need technical demands of high energy density and fast charging. Thus, it is highly desirable to explore high-performance electrodes with high reversible capacity and excellent rate capability. In this study, micro/nanostructured MnCo2O4.5 anodes were synthesized by hydrothermal treatment with the presence of positively charged poly(diallyldimethylammonium chloride). Physicochemical property studies suggested that the as-prepared MnCo2O4.5 of 2–5 µm in diameter was mainly composed of numerous nanoneedles, which were further comprised of many inter-connected nanoparticles. …

Design And Synthesis Of Novel Nanometallic Catalysts And Electrode Materials For Green Fuel Cells, Jing Zhang

Graduate Dissertations and Theses

The United Nations formally adopted 17 sustainable development goals (SDGs) at its 2015 summit. Many of these goals addressed issues such poverty, hunger, health, education, climate-change, gender equality, water, sanitation, energy, urbanization, environment and social justice. The seventh SDG seeks to ensure access to affordable, reliable, sustainable and modern energy for all. So among all renewable forms of energy, fuel cells with high efficiency have attracted a lot of attention recently. In particular, the direct ethanol fuel cells (DEFCs) and microbial fuel cells (MFCs) are significant due to their green fuel, less waste generated and environmental friendliness. Hence the overall …

Fabrication Challenges And Perspectives On The Use Of Carbon-Electrode Dielectrophoresis In Sample Preparation, Rodrigo Martinez-Duarte

Publications

The focus of this review is to assess the current status of three-dimensional (3D) carbon-electrode dielectrophoresis (carbonDEP) and identify the challenges currently preventing it from its use in high-throughput applications such as sample preparation for diagnostics. The use of 3D electrodes over more traditional planar ones is emphasised here as a way to increase the throughput of DEP devices. Glass-like carbon electrodes are derived through the carbonisation of photoresist structures made using photolithography. These biocompatible carbon electrodes are not ideal electrical conductors but are more electrochemically stable than noble metals such as gold and platinum. They are also significantly less …

Synthesis, Characterization, And Electrochemical Properties Of Polyaniline Thin Films, Soukaina Rami

USF Tampa Graduate Theses and Dissertations

Conjugated polymers have been used in various applications (battery, supercapacitor, electromagnetic shielding, chemical sensor, biosensor, nanocomposite, light-emitting-diode, electrochromic display etc.) due to their excellent conductivity, electrochemical and optical properties, and low cost. Polyaniline has attracted the researchers from all disciplines of science, engineering, and industry due to its redox properties, environmental stability, conductivity, and optical properties. Moreover, it is a polymer with fast electroactive switching and reversible properties displayed at low potential, which is an important feature in many applications. The thin oriented polyaniline films have been fabricated using self-assembly, Langmuir-Blodgett, in-situ self-assembly, layer-by-layer, and electrochemical technique. The focus of …

Sr‐ And Ni‐Doped Lacoo3 And Lafeo3 Perovskites: New Cathode Materials For Solid‐Oxide Fuel Cells, Kevin Huang, Hee Y. Lee, John B. Goodenough

Kevin Huang

An improved cathode material for a solid‐oxide fuel cell would be a mixed electronic and oxide‐ion conductor with a good catalytic activity for oxygen reduction at an operating temperature T _op ≥ 700°C and a thermal expansion matched to that of the electrolyte and interconnect. We report on the properties of Sr‐ and Ni‐doped LaCoO₃ and LaFeO₃ perovskites that meet these criteria. Single‐phase regions were determined by X‐ray diffraction, and thermogravimetric analysis measurements were used to obtain the temperatures above which oxygen loss, and hence oxide‐ion conductivity, occurs. The conductivity and Seebeck measurements indicate the coexistence of both …

Morphological Instability Leading To Formation Of Porous Anodic Oxides, Ömer Çapraz, Kurt Hebert, Pranav Shrotriya

Ömer Özgür Çapraz

No abstract provided.

Manufacturing Of Single Solid Oxide Fuel Cells, Jonathan Torres-Caceres

Electronic Theses and Dissertations

Solid oxide fuel cells (SOFCs) are devices that convert chemical energy into electrical energy and have the potential to become a reliable renewable energy source that can be used on a large scale. SOFCs have 3 main components; the electrolyte, the anode, and the cathode. Typically, SOFCs work by reducing oxygen at the cathode into O2- ions which are then transported via the electrolyte to the anode to combine with a fuel such as hydrogen to produce electricity. Research into better materials and manufacturing methods is necessary to reduce costs and improve efficiency to make the technology commercially viable. The …

Microbiosensors Based On Dna Modified Single-Walled Carbon Nanotube And Pt Black Nanocomposites, Jin Shi, Tae-Gon Cha, Jonathan C. Claussen, Alfred R. Diggs, Jong Hyun Choi, D. Marshall Porterfield

Jonathan C. Claussen

Glucose and ATP biosensors have important applications in diagnostics and research. Biosensors based on conventional materials suffer from low sensitivity and low spatial resolution. Our previous work has shown that combining single-walled carbon nanotubes (SWCNTs) with Pt nanoparticles can significantly enhance the performance of electrochemical biosensors. The immobilization of SWCNTs on biosensors remains challenging due to the aqueous insolubility originating from van der Waals forces. In this study, we used single-stranded DNA (ssDNA) to modify SWCNTs to increase solubility in water. This allowed us to explore new schemes of combining ssDNA-SWCNT and Pt black in aqueous media systems. The result …

Diffuse-Charge Dynamics Of Ionic Liquids In Electrochemical Systems, Hui Zhao

Mechanical Engineering Faculty Research

We employ a continuum theory of solvent-free ionic liquids accounting for both short-range electrostatic correlations and steric effects (finite ion size) [Bazant et al., Phys. Rev. Lett. 106, 046102 (2011)] to study the response of a model microelectrochemical cell to a step voltage. The model problem consists of a 1-1 symmetric ionic liquid between two parallel blocking electrodes, neglecting any transverse transport phenomena. Matched asymptotic expansions in the limit of thin double layers are applied to analyze the resulting one-dimensional equations and study the overall charge-time relation in the weakly nonlinear regime. One important conclusion is that our …

On The Nature Of The Electrochemically Synthesized Hard Fe-0.96 Mass Pct C Alloy Film

A.S. Md Abdul Haseeb

A hard Fe-0.96 mass pet C alloy with a hardness value of 810 HV has been electrochemically synthesized from a ferrous sulfate bath containing a small amount of citric acid and L-ascorbic acid. The nature of the alloy has been investigated by a number of techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Mössbauer spectroscopy, differential scanning calorimetry (DSC), and magnetic measurements. The decomposition behavior of the alloy is also studied and compared with that of thermally prepared martensite. It has been found that the electrochemically deposited Fe-C alloy exists in …

On The Nature Of The Electrochemically Synthesized Hard Fe-0.96 Mass Pct C Alloy Film

A.S. Md Abdul Haseeb

A hard Fe-0.96 mass pet C alloy with a hardness value of 810 HV has been electrochemically synthesized from a ferrous sulfate bath containing a small amount of citric acid and L-ascorbic acid. The nature of the alloy has been investigated by a number of techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Mössbauer spectroscopy, differential scanning calorimetry (DSC), and magnetic measurements. The decomposition behavior of the alloy is also studied and compared with that of thermally prepared martensite. It has been found that the electrochemically deposited Fe-C alloy exists in …

Fuel Cells, Frederick J. Munster Jr.

Maine Collection

Fuel Cells

by Frederick J. Munster Jr.

Edited by: Mr. Christopher Carroll

Maine Department of Economic Development, Augusta, Maine, 1998.

Contents: Hydrogen / Hydrogen Safety / Electrolysis / Electrolyzers / History of Fuel Cells / How Fuel Cells Operate / Fuel Cell Types / Fuel Cell Electrochemistry / Power Systems / Fuel Cells in Transportation / Hydrogen Powered Internal Combustion Engines / Home, Garden, Education and Industry / For More Information / Glossary / References

Sr‐ And Ni‐Doped Lacoo3 And Lafeo3 Perovskites: New Cathode Materials For Solid‐Oxide Fuel Cells, Kevin Huang, Hee Y. Lee, John B. Goodenough

Faculty Publications

An improved cathode material for a solid‐oxide fuel cell would be a mixed electronic and oxide‐ion conductor with a good catalytic activity for oxygen reduction at an operating temperature T _op ≥ 700°C and a thermal expansion matched to that of the electrolyte and interconnect. We report on the properties of Sr‐ and Ni‐doped LaCoO₃ and LaFeO₃ perovskites that meet these criteria. Single‐phase regions were determined by X‐ray diffraction, and thermogravimetric analysis measurements were used to obtain the temperatures above which oxygen loss, and hence oxide‐ion conductivity, occurs. The conductivity and Seebeck measurements indicate the coexistence of both …